third_party/sqlite/sqlite-src-3100200/src/sqlite.h.in - Issue 2846743003: [sql] Remove SQLite 3.10.2 reference directory.

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Issue 2846743003: [sql] Remove SQLite 3.10.2 reference directory. (Closed)

Patch Set: Created 3 years, 7 months ago

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1 /*

2 ** 2001 September 15

3 **

4 ** The author disclaims copyright to this source code. In place of

5 ** a legal notice, here is a blessing:

6 **

7 ** May you do good and not evil.

8 ** May you find forgiveness for yourself and forgive others.

9 ** May you share freely, never taking more than you give.

10 **

11 *************************************************************************

12 ** This header file defines the interface that the SQLite library

13 ** presents to client programs. If a C-function, structure, datatype,

14 ** or constant definition does not appear in this file, then it is

15 ** not a published API of SQLite, is subject to change without

16 ** notice, and should not be referenced by programs that use SQLite.

17 **

18 ** Some of the definitions that are in this file are marked as

19 ** "experimental". Experimental interfaces are normally new

20 ** features recently added to SQLite. We do not anticipate changes

21 ** to experimental interfaces but reserve the right to make minor changes

22 ** if experience from use "in the wild" suggest such changes are prudent.

23 **

24 ** The official C-language API documentation for SQLite is derived

25 ** from comments in this file. This file is the authoritative source

26 ** on how SQLite interfaces are supposed to operate.

27 **

28 ** The name of this file under configuration management is "sqlite.h.in".

29 ** The makefile makes some minor changes to this file (such as inserting

30 ** the version number) and changes its name to "sqlite3.h" as

31 ** part of the build process.

32 */

33 #ifndef _SQLITE3_H_

34 #define _SQLITE3_H_

35 #include <stdarg.h> /* Needed for the definition of va_list */

36

37 /*

38 ** Make sure we can call this stuff from C++.

39 */

40 #ifdef __cplusplus

41 extern "C" {

42 #endif

43

44

45 /*

46 ** Provide the ability to override linkage features of the interface.

47 */

48 #ifndef SQLITE_EXTERN

49 # define SQLITE_EXTERN extern

50 #endif

51 #ifndef SQLITE_API

52 # define SQLITE_API

53 #endif

54 #ifndef SQLITE_CDECL

55 # define SQLITE_CDECL

56 #endif

57 #ifndef SQLITE_STDCALL

58 # define SQLITE_STDCALL

59 #endif

60

61 /*

62 ** These no-op macros are used in front of interfaces to mark those

63 ** interfaces as either deprecated or experimental. New applications

64 ** should not use deprecated interfaces - they are supported for backwards

65 ** compatibility only. Application writers should be aware that

66 ** experimental interfaces are subject to change in point releases.

67 **

68 ** These macros used to resolve to various kinds of compiler magic that

69 ** would generate warning messages when they were used. But that

70 ** compiler magic ended up generating such a flurry of bug reports

71 ** that we have taken it all out and gone back to using simple

72 ** noop macros.

73 */

74 #define SQLITE_DEPRECATED

75 #define SQLITE_EXPERIMENTAL

76

77 /*

78 ** Ensure these symbols were not defined by some previous header file.

79 */

80 #ifdef SQLITE_VERSION

81 # undef SQLITE_VERSION

82 #endif

83 #ifdef SQLITE_VERSION_NUMBER

84 # undef SQLITE_VERSION_NUMBER

85 #endif

86

87 /*

88 ** CAPI3REF: Compile-Time Library Version Numbers

89 **

90 ** ^(The [SQLITE_VERSION] C preprocessor macro in the sqlite3.h header

91 ** evaluates to a string literal that is the SQLite version in the

92 ** format "X.Y.Z" where X is the major version number (always 3 for

93 ** SQLite3) and Y is the minor version number and Z is the release number.)^

94 ** ^(The [SQLITE_VERSION_NUMBER] C preprocessor macro resolves to an integer

95 ** with the value (X1000000 + Y1000 + Z) where X, Y, and Z are the same

96 ** numbers used in [SQLITE_VERSION].)^

97 ** The SQLITE_VERSION_NUMBER for any given release of SQLite will also

98 ** be larger than the release from which it is derived. Either Y will

99 ** be held constant and Z will be incremented or else Y will be incremented

100 ** and Z will be reset to zero.

101 **

102 ** Since version 3.6.18, SQLite source code has been stored in the

103 ** <a href="http://www.fossil-scm.org/">Fossil configuration management

104 ** system</a>. ^The SQLITE_SOURCE_ID macro evaluates to

105 ** a string which identifies a particular check-in of SQLite

106 ** within its configuration management system. ^The SQLITE_SOURCE_ID

107 ** string contains the date and time of the check-in (UTC) and an SHA1

108 ** hash of the entire source tree.

109 **

110 ** See also: [sqlite3_libversion()],

111 ** [sqlite3_libversion_number()], [sqlite3_sourceid()],

112 ** [sqlite_version()] and [sqlite_source_id()].

113 */

114 #define SQLITE_VERSION "--VERS--"

115 #define SQLITE_VERSION_NUMBER --VERSION-NUMBER--

116 #define SQLITE_SOURCE_ID "--SOURCE-ID--"

117

118 /*

119 ** CAPI3REF: Run-Time Library Version Numbers

120 ** KEYWORDS: sqlite3_version, sqlite3_sourceid

121 **

122 ** These interfaces provide the same information as the [SQLITE_VERSION],

123 ** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros

124 ** but are associated with the library instead of the header file. ^(Cautious

125 ** programmers might include assert() statements in their application to

126 ** verify that values returned by these interfaces match the macros in

127 ** the header, and thus ensure that the application is

128 ** compiled with matching library and header files.

129 **

130 ** <blockquote><pre>

131 ** assert( sqlite3_libversion_number()==SQLITE_VERSION_NUMBER );

132 ** assert( strcmp(sqlite3_sourceid(),SQLITE_SOURCE_ID)==0 );

133 ** assert( strcmp(sqlite3_libversion(),SQLITE_VERSION)==0 );

134 ** </pre></blockquote>)^

135 **

136 ** ^The sqlite3_version[] string constant contains the text of [SQLITE_VERSION]

137 ** macro. ^The sqlite3_libversion() function returns a pointer to the

138 ** to the sqlite3_version[] string constant. The sqlite3_libversion()

139 ** function is provided for use in DLLs since DLL users usually do not have

140 ** direct access to string constants within the DLL. ^The

141 ** sqlite3_libversion_number() function returns an integer equal to

142 ** [SQLITE_VERSION_NUMBER]. ^The sqlite3_sourceid() function returns

143 ** a pointer to a string constant whose value is the same as the

144 ** [SQLITE_SOURCE_ID] C preprocessor macro.

145 **

146 ** See also: [sqlite_version()] and [sqlite_source_id()].

147 */

148 SQLITE_EXTERN const char sqlite3_version[];

149 const char *sqlite3_libversion(void);

150 const char *sqlite3_sourceid(void);

151 int sqlite3_libversion_number(void);

152

153 /*

154 ** CAPI3REF: Run-Time Library Compilation Options Diagnostics

155 **

156 ** ^The sqlite3_compileoption_used() function returns 0 or 1

157 ** indicating whether the specified option was defined at

158 ** compile time. ^The SQLITE_ prefix may be omitted from the

159 ** option name passed to sqlite3_compileoption_used().

160 **

161 ** ^The sqlite3_compileoption_get() function allows iterating

162 ** over the list of options that were defined at compile time by

163 ** returning the N-th compile time option string. ^If N is out of range,

164 ** sqlite3_compileoption_get() returns a NULL pointer. ^The SQLITE_

165 ** prefix is omitted from any strings returned by

166 ** sqlite3_compileoption_get().

167 **

168 ** ^Support for the diagnostic functions sqlite3_compileoption_used()

169 ** and sqlite3_compileoption_get() may be omitted by specifying the

170 ** [SQLITE_OMIT_COMPILEOPTION_DIAGS] option at compile time.

171 **

172 ** See also: SQL functions [sqlite_compileoption_used()] and

173 ** [sqlite_compileoption_get()] and the [compile_options pragma].

174 */

175 #ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS

176 int sqlite3_compileoption_used(const char *zOptName);

177 const char *sqlite3_compileoption_get(int N);

178 #endif

179

180 /*

181 ** CAPI3REF: Test To See If The Library Is Threadsafe

182 **

183 ** ^The sqlite3_threadsafe() function returns zero if and only if

184 ** SQLite was compiled with mutexing code omitted due to the

185 ** [SQLITE_THREADSAFE] compile-time option being set to 0.

186 **

187 ** SQLite can be compiled with or without mutexes. When

188 ** the [SQLITE_THREADSAFE] C preprocessor macro is 1 or 2, mutexes

189 ** are enabled and SQLite is threadsafe. When the

190 ** [SQLITE_THREADSAFE] macro is 0,

191 ** the mutexes are omitted. Without the mutexes, it is not safe

192 ** to use SQLite concurrently from more than one thread.

193 **

194 ** Enabling mutexes incurs a measurable performance penalty.

195 ** So if speed is of utmost importance, it makes sense to disable

196 ** the mutexes. But for maximum safety, mutexes should be enabled.

197 ** ^The default behavior is for mutexes to be enabled.

198 **

199 ** This interface can be used by an application to make sure that the

200 ** version of SQLite that it is linking against was compiled with

201 ** the desired setting of the [SQLITE_THREADSAFE] macro.

202 **

203 ** This interface only reports on the compile-time mutex setting

204 ** of the [SQLITE_THREADSAFE] flag. If SQLite is compiled with

205 ** SQLITE_THREADSAFE=1 or =2 then mutexes are enabled by default but

206 ** can be fully or partially disabled using a call to [sqlite3_config()]

207 ** with the verbs [SQLITE_CONFIG_SINGLETHREAD], [SQLITE_CONFIG_MULTITHREAD],

208 ** or [SQLITE_CONFIG_SERIALIZED]. ^(The return value of the

209 ** sqlite3_threadsafe() function shows only the compile-time setting of

210 ** thread safety, not any run-time changes to that setting made by

211 ** sqlite3_config(). In other words, the return value from sqlite3_threadsafe()

212 ** is unchanged by calls to sqlite3_config().)^

213 **

214 ** See the [threading mode] documentation for additional information.

215 */

216 int sqlite3_threadsafe(void);

217

218 /*

219 ** CAPI3REF: Database Connection Handle

220 ** KEYWORDS: {database connection} {database connections}

221 **

222 ** Each open SQLite database is represented by a pointer to an instance of

223 ** the opaque structure named "sqlite3". It is useful to think of an sqlite3

224 ** pointer as an object. The [sqlite3_open()], [sqlite3_open16()], and

225 ** [sqlite3_open_v2()] interfaces are its constructors, and [sqlite3_close()]

226 ** and [sqlite3_close_v2()] are its destructors. There are many other

227 ** interfaces (such as

228 ** [sqlite3_prepare_v2()], [sqlite3_create_function()], and

229 ** [sqlite3_busy_timeout()] to name but three) that are methods on an

230 ** sqlite3 object.

231 */

232 typedef struct sqlite3 sqlite3;

233

234 /*

235 ** CAPI3REF: 64-Bit Integer Types

236 ** KEYWORDS: sqlite_int64 sqlite_uint64

237 **

238 ** Because there is no cross-platform way to specify 64-bit integer types

239 ** SQLite includes typedefs for 64-bit signed and unsigned integers.

240 **

241 ** The sqlite3_int64 and sqlite3_uint64 are the preferred type definitions.

242 ** The sqlite_int64 and sqlite_uint64 types are supported for backwards

243 ** compatibility only.

244 **

245 ** ^The sqlite3_int64 and sqlite_int64 types can store integer values

246 ** between -9223372036854775808 and +9223372036854775807 inclusive. ^The

247 ** sqlite3_uint64 and sqlite_uint64 types can store integer values

248 ** between 0 and +18446744073709551615 inclusive.

249 */

250 #ifdef SQLITE_INT64_TYPE

251 typedef SQLITE_INT64_TYPE sqlite_int64;

252 typedef unsigned SQLITE_INT64_TYPE sqlite_uint64;

253 #elif defined(_MSC_VER) \|\| defined(__BORLANDC__)

254 typedef __int64 sqlite_int64;

255 typedef unsigned __int64 sqlite_uint64;

256 #else

257 typedef long long int sqlite_int64;

258 typedef unsigned long long int sqlite_uint64;

259 #endif

260 typedef sqlite_int64 sqlite3_int64;

261 typedef sqlite_uint64 sqlite3_uint64;

262

263 /*

264 ** If compiling for a processor that lacks floating point support,

265 ** substitute integer for floating-point.

266 */

267 #ifdef SQLITE_OMIT_FLOATING_POINT

268 # define double sqlite3_int64

269 #endif

270

271 /*

272 ** CAPI3REF: Closing A Database Connection

273 ** DESTRUCTOR: sqlite3

274 **

275 ** ^The sqlite3_close() and sqlite3_close_v2() routines are destructors

276 ** for the [sqlite3] object.

277 ** ^Calls to sqlite3_close() and sqlite3_close_v2() return [SQLITE_OK] if

278 ** the [sqlite3] object is successfully destroyed and all associated

279 ** resources are deallocated.

280 **

281 ** ^If the database connection is associated with unfinalized prepared

282 ** statements or unfinished sqlite3_backup objects then sqlite3_close()

283 ** will leave the database connection open and return [SQLITE_BUSY].

284 ** ^If sqlite3_close_v2() is called with unfinalized prepared statements

285 ** and/or unfinished sqlite3_backups, then the database connection becomes

286 ** an unusable "zombie" which will automatically be deallocated when the

287 ** last prepared statement is finalized or the last sqlite3_backup is

288 ** finished. The sqlite3_close_v2() interface is intended for use with

289 ** host languages that are garbage collected, and where the order in which

290 ** destructors are called is arbitrary.

291 **

292 ** Applications should [sqlite3_finalize \| finalize] all [prepared statements],

293 ** [sqlite3_blob_close \| close] all [BLOB handles], and

294 ** [sqlite3_backup_finish \| finish] all [sqlite3_backup] objects associated

295 ** with the [sqlite3] object prior to attempting to close the object. ^If

296 ** sqlite3_close_v2() is called on a [database connection] that still has

297 ** outstanding [prepared statements], [BLOB handles], and/or

298 ** [sqlite3_backup] objects then it returns [SQLITE_OK] and the deallocation

299 ** of resources is deferred until all [prepared statements], [BLOB handles],

300 ** and [sqlite3_backup] objects are also destroyed.

301 **

302 ** ^If an [sqlite3] object is destroyed while a transaction is open,

303 ** the transaction is automatically rolled back.

304 **

305 ** The C parameter to [sqlite3_close(C)] and [sqlite3_close_v2(C)]

306 ** must be either a NULL

307 ** pointer or an [sqlite3] object pointer obtained

308 ** from [sqlite3_open()], [sqlite3_open16()], or

309 ** [sqlite3_open_v2()], and not previously closed.

310 ** ^Calling sqlite3_close() or sqlite3_close_v2() with a NULL pointer

311 ** argument is a harmless no-op.

312 */

313 int sqlite3_close(sqlite3*);

314 int sqlite3_close_v2(sqlite3*);

315

316 /*

317 ** The type for a callback function.

318 ** This is legacy and deprecated. It is included for historical

319 ** compatibility and is not documented.

320 */

321 typedef int (sqlite3_callback)(void,int,char, char);

322

323 /*

324 ** CAPI3REF: One-Step Query Execution Interface

325 ** METHOD: sqlite3

326 **

327 ** The sqlite3_exec() interface is a convenience wrapper around

328 ** [sqlite3_prepare_v2()], [sqlite3_step()], and [sqlite3_finalize()],

329 ** that allows an application to run multiple statements of SQL

330 ** without having to use a lot of C code.

331 **

332 ** ^The sqlite3_exec() interface runs zero or more UTF-8 encoded,

333 ** semicolon-separate SQL statements passed into its 2nd argument,

334 ** in the context of the [database connection] passed in as its 1st

335 ** argument. ^If the callback function of the 3rd argument to

336 ** sqlite3_exec() is not NULL, then it is invoked for each result row

337 ** coming out of the evaluated SQL statements. ^The 4th argument to

338 ** sqlite3_exec() is relayed through to the 1st argument of each

339 ** callback invocation. ^If the callback pointer to sqlite3_exec()

340 ** is NULL, then no callback is ever invoked and result rows are

341 ** ignored.

342 **

343 ** ^If an error occurs while evaluating the SQL statements passed into

344 ** sqlite3_exec(), then execution of the current statement stops and

345 ** subsequent statements are skipped. ^If the 5th parameter to sqlite3_exec()

346 ** is not NULL then any error message is written into memory obtained

347 ** from [sqlite3_malloc()] and passed back through the 5th parameter.

348 ** To avoid memory leaks, the application should invoke [sqlite3_free()]

349 ** on error message strings returned through the 5th parameter of

350 ** of sqlite3_exec() after the error message string is no longer needed.

351 ** ^If the 5th parameter to sqlite3_exec() is not NULL and no errors

352 ** occur, then sqlite3_exec() sets the pointer in its 5th parameter to

353 ** NULL before returning.

354 **

355 ** ^If an sqlite3_exec() callback returns non-zero, the sqlite3_exec()

356 ** routine returns SQLITE_ABORT without invoking the callback again and

357 ** without running any subsequent SQL statements.

358 **

359 ** ^The 2nd argument to the sqlite3_exec() callback function is the

360 ** number of columns in the result. ^The 3rd argument to the sqlite3_exec()

361 ** callback is an array of pointers to strings obtained as if from

362 ** [sqlite3_column_text()], one for each column. ^If an element of a

363 ** result row is NULL then the corresponding string pointer for the

364 ** sqlite3_exec() callback is a NULL pointer. ^The 4th argument to the

365 ** sqlite3_exec() callback is an array of pointers to strings where each

366 ** entry represents the name of corresponding result column as obtained

367 ** from [sqlite3_column_name()].

368 **

369 ** ^If the 2nd parameter to sqlite3_exec() is a NULL pointer, a pointer

370 ** to an empty string, or a pointer that contains only whitespace and/or

371 ** SQL comments, then no SQL statements are evaluated and the database

372 ** is not changed.

373 **

374 ** Restrictions:

375 **

376 ** <ul>

377 ** <li> The application must ensure that the 1st parameter to sqlite3_exec()

378 ** is a valid and open [database connection].

379 ** <li> The application must not close the [database connection] specified by

380 ** the 1st parameter to sqlite3_exec() while sqlite3_exec() is running.

381 ** <li> The application must not modify the SQL statement text passed into

382 ** the 2nd parameter of sqlite3_exec() while sqlite3_exec() is running.

383 ** </ul>

384 */

385 int sqlite3_exec(

386 sqlite3, / An open database */

387 const char sql, / SQL to be evaluated */

388 int (callback)(void,int,char,char), /* Callback function */

389 void , / 1st argument to callback */

390 char *errmsg / Error msg written here */

391 );

392

393 /*

394 ** CAPI3REF: Result Codes

395 ** KEYWORDS: {result code definitions}

396 **

397 ** Many SQLite functions return an integer result code from the set shown

398 ** here in order to indicate success or failure.

399 **

400 ** New error codes may be added in future versions of SQLite.

401 **

402 ** See also: [extended result code definitions]

403 */

404 #define SQLITE_OK 0 /* Successful result */

405 /* beginning-of-error-codes */

406 #define SQLITE_ERROR 1 /* SQL error or missing database */

407 #define SQLITE_INTERNAL 2 /* Internal logic error in SQLite */

408 #define SQLITE_PERM 3 /* Access permission denied */

409 #define SQLITE_ABORT 4 /* Callback routine requested an abort */

410 #define SQLITE_BUSY 5 /* The database file is locked */

411 #define SQLITE_LOCKED 6 /* A table in the database is locked */

412 #define SQLITE_NOMEM 7 /* A malloc() failed */

413 #define SQLITE_READONLY 8 /* Attempt to write a readonly database */

414 #define SQLITE_INTERRUPT 9 /* Operation terminated by sqlite3_interrupt()*/

415 #define SQLITE_IOERR 10 /* Some kind of disk I/O error occurred */

416 #define SQLITE_CORRUPT 11 /* The database disk image is malformed */

417 #define SQLITE_NOTFOUND 12 /* Unknown opcode in sqlite3_file_control() */

418 #define SQLITE_FULL 13 /* Insertion failed because database is full */

419 #define SQLITE_CANTOPEN 14 /* Unable to open the database file */

420 #define SQLITE_PROTOCOL 15 /* Database lock protocol error */

421 #define SQLITE_EMPTY 16 /* Database is empty */

422 #define SQLITE_SCHEMA 17 /* The database schema changed */

423 #define SQLITE_TOOBIG 18 /* String or BLOB exceeds size limit */

424 #define SQLITE_CONSTRAINT 19 /* Abort due to constraint violation */

425 #define SQLITE_MISMATCH 20 /* Data type mismatch */

426 #define SQLITE_MISUSE 21 /* Library used incorrectly */

427 #define SQLITE_NOLFS 22 /* Uses OS features not supported on host */

428 #define SQLITE_AUTH 23 /* Authorization denied */

429 #define SQLITE_FORMAT 24 /* Auxiliary database format error */

430 #define SQLITE_RANGE 25 /* 2nd parameter to sqlite3_bind out of range */

431 #define SQLITE_NOTADB 26 /* File opened that is not a database file */

432 #define SQLITE_NOTICE 27 /* Notifications from sqlite3_log() */

433 #define SQLITE_WARNING 28 /* Warnings from sqlite3_log() */

434 #define SQLITE_ROW 100 /* sqlite3_step() has another row ready */

435 #define SQLITE_DONE 101 /* sqlite3_step() has finished executing */

436 /* end-of-error-codes */

437

438 /*

439 ** CAPI3REF: Extended Result Codes

440 ** KEYWORDS: {extended result code definitions}

441 **

442 ** In its default configuration, SQLite API routines return one of 30 integer

443 ** [result codes]. However, experience has shown that many of

444 ** these result codes are too coarse-grained. They do not provide as

445 ** much information about problems as programmers might like. In an effort to

446 ** address this, newer versions of SQLite (version 3.3.8 and later) include

447 ** support for additional result codes that provide more detailed information

448 ** about errors. These [extended result codes] are enabled or disabled

449 ** on a per database connection basis using the

450 ** [sqlite3_extended_result_codes()] API. Or, the extended code for

451 ** the most recent error can be obtained using

452 ** [sqlite3_extended_errcode()].

453 */

454 #define SQLITE_IOERR_READ (SQLITE_IOERR \| (1<<8))

455 #define SQLITE_IOERR_SHORT_READ (SQLITE_IOERR \| (2<<8))

456 #define SQLITE_IOERR_WRITE (SQLITE_IOERR \| (3<<8))

457 #define SQLITE_IOERR_FSYNC (SQLITE_IOERR \| (4<<8))

458 #define SQLITE_IOERR_DIR_FSYNC (SQLITE_IOERR \| (5<<8))

459 #define SQLITE_IOERR_TRUNCATE (SQLITE_IOERR \| (6<<8))

460 #define SQLITE_IOERR_FSTAT (SQLITE_IOERR \| (7<<8))

461 #define SQLITE_IOERR_UNLOCK (SQLITE_IOERR \| (8<<8))

462 #define SQLITE_IOERR_RDLOCK (SQLITE_IOERR \| (9<<8))

463 #define SQLITE_IOERR_DELETE (SQLITE_IOERR \| (10<<8))

464 #define SQLITE_IOERR_BLOCKED (SQLITE_IOERR \| (11<<8))

465 #define SQLITE_IOERR_NOMEM (SQLITE_IOERR \| (12<<8))

466 #define SQLITE_IOERR_ACCESS (SQLITE_IOERR \| (13<<8))

467 #define SQLITE_IOERR_CHECKRESERVEDLOCK (SQLITE_IOERR \| (14<<8))

468 #define SQLITE_IOERR_LOCK (SQLITE_IOERR \| (15<<8))

469 #define SQLITE_IOERR_CLOSE (SQLITE_IOERR \| (16<<8))

470 #define SQLITE_IOERR_DIR_CLOSE (SQLITE_IOERR \| (17<<8))

471 #define SQLITE_IOERR_SHMOPEN (SQLITE_IOERR \| (18<<8))

472 #define SQLITE_IOERR_SHMSIZE (SQLITE_IOERR \| (19<<8))

473 #define SQLITE_IOERR_SHMLOCK (SQLITE_IOERR \| (20<<8))

474 #define SQLITE_IOERR_SHMMAP (SQLITE_IOERR \| (21<<8))

475 #define SQLITE_IOERR_SEEK (SQLITE_IOERR \| (22<<8))

476 #define SQLITE_IOERR_DELETE_NOENT (SQLITE_IOERR \| (23<<8))

477 #define SQLITE_IOERR_MMAP (SQLITE_IOERR \| (24<<8))

478 #define SQLITE_IOERR_GETTEMPPATH (SQLITE_IOERR \| (25<<8))

479 #define SQLITE_IOERR_CONVPATH (SQLITE_IOERR \| (26<<8))

480 #define SQLITE_IOERR_VNODE (SQLITE_IOERR \| (27<<8))

481 #define SQLITE_IOERR_AUTH (SQLITE_IOERR \| (28<<8))

482 #define SQLITE_LOCKED_SHAREDCACHE (SQLITE_LOCKED \| (1<<8))

483 #define SQLITE_BUSY_RECOVERY (SQLITE_BUSY \| (1<<8))

484 #define SQLITE_BUSY_SNAPSHOT (SQLITE_BUSY \| (2<<8))

485 #define SQLITE_CANTOPEN_NOTEMPDIR (SQLITE_CANTOPEN \| (1<<8))

486 #define SQLITE_CANTOPEN_ISDIR (SQLITE_CANTOPEN \| (2<<8))

487 #define SQLITE_CANTOPEN_FULLPATH (SQLITE_CANTOPEN \| (3<<8))

488 #define SQLITE_CANTOPEN_CONVPATH (SQLITE_CANTOPEN \| (4<<8))

489 #define SQLITE_CORRUPT_VTAB (SQLITE_CORRUPT \| (1<<8))

490 #define SQLITE_READONLY_RECOVERY (SQLITE_READONLY \| (1<<8))

491 #define SQLITE_READONLY_CANTLOCK (SQLITE_READONLY \| (2<<8))

492 #define SQLITE_READONLY_ROLLBACK (SQLITE_READONLY \| (3<<8))

493 #define SQLITE_READONLY_DBMOVED (SQLITE_READONLY \| (4<<8))

494 #define SQLITE_ABORT_ROLLBACK (SQLITE_ABORT \| (2<<8))

495 #define SQLITE_CONSTRAINT_CHECK (SQLITE_CONSTRAINT \| (1<<8))

496 #define SQLITE_CONSTRAINT_COMMITHOOK (SQLITE_CONSTRAINT \| (2<<8))

497 #define SQLITE_CONSTRAINT_FOREIGNKEY (SQLITE_CONSTRAINT \| (3<<8))

498 #define SQLITE_CONSTRAINT_FUNCTION (SQLITE_CONSTRAINT \| (4<<8))

499 #define SQLITE_CONSTRAINT_NOTNULL (SQLITE_CONSTRAINT \| (5<<8))

500 #define SQLITE_CONSTRAINT_PRIMARYKEY (SQLITE_CONSTRAINT \| (6<<8))

501 #define SQLITE_CONSTRAINT_TRIGGER (SQLITE_CONSTRAINT \| (7<<8))

502 #define SQLITE_CONSTRAINT_UNIQUE (SQLITE_CONSTRAINT \| (8<<8))

503 #define SQLITE_CONSTRAINT_VTAB (SQLITE_CONSTRAINT \| (9<<8))

504 #define SQLITE_CONSTRAINT_ROWID (SQLITE_CONSTRAINT \|(10<<8))

505 #define SQLITE_NOTICE_RECOVER_WAL (SQLITE_NOTICE \| (1<<8))

506 #define SQLITE_NOTICE_RECOVER_ROLLBACK (SQLITE_NOTICE \| (2<<8))

507 #define SQLITE_WARNING_AUTOINDEX (SQLITE_WARNING \| (1<<8))

508 #define SQLITE_AUTH_USER (SQLITE_AUTH \| (1<<8))

509

510 /*

511 ** CAPI3REF: Flags For File Open Operations

512 **

513 ** These bit values are intended for use in the

514 ** 3rd parameter to the [sqlite3_open_v2()] interface and

515 ** in the 4th parameter to the [sqlite3_vfs.xOpen] method.

516 */

517 #define SQLITE_OPEN_READONLY 0x00000001 /* Ok for sqlite3_open_v2() */

518 #define SQLITE_OPEN_READWRITE 0x00000002 /* Ok for sqlite3_open_v2() */

519 #define SQLITE_OPEN_CREATE 0x00000004 /* Ok for sqlite3_open_v2() */

520 #define SQLITE_OPEN_DELETEONCLOSE 0x00000008 /* VFS only */

521 #define SQLITE_OPEN_EXCLUSIVE 0x00000010 /* VFS only */

522 #define SQLITE_OPEN_AUTOPROXY 0x00000020 /* VFS only */

523 #define SQLITE_OPEN_URI 0x00000040 /* Ok for sqlite3_open_v2() */

524 #define SQLITE_OPEN_MEMORY 0x00000080 /* Ok for sqlite3_open_v2() */

525 #define SQLITE_OPEN_MAIN_DB 0x00000100 /* VFS only */

526 #define SQLITE_OPEN_TEMP_DB 0x00000200 /* VFS only */

527 #define SQLITE_OPEN_TRANSIENT_DB 0x00000400 /* VFS only */

528 #define SQLITE_OPEN_MAIN_JOURNAL 0x00000800 /* VFS only */

529 #define SQLITE_OPEN_TEMP_JOURNAL 0x00001000 /* VFS only */

530 #define SQLITE_OPEN_SUBJOURNAL 0x00002000 /* VFS only */

531 #define SQLITE_OPEN_MASTER_JOURNAL 0x00004000 /* VFS only */

532 #define SQLITE_OPEN_NOMUTEX 0x00008000 /* Ok for sqlite3_open_v2() */

533 #define SQLITE_OPEN_FULLMUTEX 0x00010000 /* Ok for sqlite3_open_v2() */

534 #define SQLITE_OPEN_SHAREDCACHE 0x00020000 /* Ok for sqlite3_open_v2() */

535 #define SQLITE_OPEN_PRIVATECACHE 0x00040000 /* Ok for sqlite3_open_v2() */

536 #define SQLITE_OPEN_WAL 0x00080000 /* VFS only */

537

538 /* Reserved: 0x00F00000 */

539

540 /*

541 ** CAPI3REF: Device Characteristics

542 **

543 ** The xDeviceCharacteristics method of the [sqlite3_io_methods]

544 ** object returns an integer which is a vector of these

545 ** bit values expressing I/O characteristics of the mass storage

546 ** device that holds the file that the [sqlite3_io_methods]

547 ** refers to.

548 **

549 ** The SQLITE_IOCAP_ATOMIC property means that all writes of

550 ** any size are atomic. The SQLITE_IOCAP_ATOMICnnn values

551 ** mean that writes of blocks that are nnn bytes in size and

552 ** are aligned to an address which is an integer multiple of

553 ** nnn are atomic. The SQLITE_IOCAP_SAFE_APPEND value means

554 ** that when data is appended to a file, the data is appended

555 ** first then the size of the file is extended, never the other

556 ** way around. The SQLITE_IOCAP_SEQUENTIAL property means that

557 ** information is written to disk in the same order as calls

558 ** to xWrite(). The SQLITE_IOCAP_POWERSAFE_OVERWRITE property means that

559 ** after reboot following a crash or power loss, the only bytes in a

560 ** file that were written at the application level might have changed

561 ** and that adjacent bytes, even bytes within the same sector are

562 ** guaranteed to be unchanged. The SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN

563 ** flag indicate that a file cannot be deleted when open. The

564 ** SQLITE_IOCAP_IMMUTABLE flag indicates that the file is on

565 ** read-only media and cannot be changed even by processes with

566 ** elevated privileges.

567 */

568 #define SQLITE_IOCAP_ATOMIC 0x00000001

569 #define SQLITE_IOCAP_ATOMIC512 0x00000002

570 #define SQLITE_IOCAP_ATOMIC1K 0x00000004

571 #define SQLITE_IOCAP_ATOMIC2K 0x00000008

572 #define SQLITE_IOCAP_ATOMIC4K 0x00000010

573 #define SQLITE_IOCAP_ATOMIC8K 0x00000020

574 #define SQLITE_IOCAP_ATOMIC16K 0x00000040

575 #define SQLITE_IOCAP_ATOMIC32K 0x00000080

576 #define SQLITE_IOCAP_ATOMIC64K 0x00000100

577 #define SQLITE_IOCAP_SAFE_APPEND 0x00000200

578 #define SQLITE_IOCAP_SEQUENTIAL 0x00000400

579 #define SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN 0x00000800

580 #define SQLITE_IOCAP_POWERSAFE_OVERWRITE 0x00001000

581 #define SQLITE_IOCAP_IMMUTABLE 0x00002000

582

583 /*

584 ** CAPI3REF: File Locking Levels

585 **

586 ** SQLite uses one of these integer values as the second

587 ** argument to calls it makes to the xLock() and xUnlock() methods

588 ** of an [sqlite3_io_methods] object.

589 */

590 #define SQLITE_LOCK_NONE 0

591 #define SQLITE_LOCK_SHARED 1

592 #define SQLITE_LOCK_RESERVED 2

593 #define SQLITE_LOCK_PENDING 3

594 #define SQLITE_LOCK_EXCLUSIVE 4

595

596 /*

597 ** CAPI3REF: Synchronization Type Flags

598 **

599 ** When SQLite invokes the xSync() method of an

600 ** [sqlite3_io_methods] object it uses a combination of

601 ** these integer values as the second argument.

602 **

603 ** When the SQLITE_SYNC_DATAONLY flag is used, it means that the

604 ** sync operation only needs to flush data to mass storage. Inode

605 ** information need not be flushed. If the lower four bits of the flag

606 ** equal SQLITE_SYNC_NORMAL, that means to use normal fsync() semantics.

607 ** If the lower four bits equal SQLITE_SYNC_FULL, that means

608 ** to use Mac OS X style fullsync instead of fsync().

609 **

610 ** Do not confuse the SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL flags

611 ** with the [PRAGMA synchronous]=NORMAL and [PRAGMA synchronous]=FULL

612 ** settings. The [synchronous pragma] determines when calls to the

613 ** xSync VFS method occur and applies uniformly across all platforms.

614 ** The SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL flags determine how

615 ** energetic or rigorous or forceful the sync operations are and

616 ** only make a difference on Mac OSX for the default SQLite code.

617 ** (Third-party VFS implementations might also make the distinction

618 ** between SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL, but among the

619 ** operating systems natively supported by SQLite, only Mac OSX

620 ** cares about the difference.)

621 */

622 #define SQLITE_SYNC_NORMAL 0x00002

623 #define SQLITE_SYNC_FULL 0x00003

624 #define SQLITE_SYNC_DATAONLY 0x00010

625

626 /*

627 ** CAPI3REF: OS Interface Open File Handle

628 **

629 ** An [sqlite3_file] object represents an open file in the

630 ** [sqlite3_vfs \| OS interface layer]. Individual OS interface

631 ** implementations will

632 ** want to subclass this object by appending additional fields

633 ** for their own use. The pMethods entry is a pointer to an

634 ** [sqlite3_io_methods] object that defines methods for performing

635 ** I/O operations on the open file.

636 */

637 typedef struct sqlite3_file sqlite3_file;

638 struct sqlite3_file {

639 const struct sqlite3_io_methods pMethods; / Methods for an open file */

640 };

641

642 /*

643 ** CAPI3REF: OS Interface File Virtual Methods Object

644 **

645 ** Every file opened by the [sqlite3_vfs.xOpen] method populates an

646 ** [sqlite3_file] object (or, more commonly, a subclass of the

647 ** [sqlite3_file] object) with a pointer to an instance of this object.

648 ** This object defines the methods used to perform various operations

649 ** against the open file represented by the [sqlite3_file] object.

650 **

651 ** If the [sqlite3_vfs.xOpen] method sets the sqlite3_file.pMethods element

652 ** to a non-NULL pointer, then the sqlite3_io_methods.xClose method

653 ** may be invoked even if the [sqlite3_vfs.xOpen] reported that it failed. The

654 ** only way to prevent a call to xClose following a failed [sqlite3_vfs.xOpen]

655 ** is for the [sqlite3_vfs.xOpen] to set the sqlite3_file.pMethods element

656 ** to NULL.

657 **

658 ** The flags argument to xSync may be one of [SQLITE_SYNC_NORMAL] or

659 ** [SQLITE_SYNC_FULL]. The first choice is the normal fsync().

660 ** The second choice is a Mac OS X style fullsync. The [SQLITE_SYNC_DATAONLY]

661 ** flag may be ORed in to indicate that only the data of the file

662 ** and not its inode needs to be synced.

663 **

664 ** The integer values to xLock() and xUnlock() are one of

665 ** <ul>

666 ** <li> [SQLITE_LOCK_NONE],

667 ** <li> [SQLITE_LOCK_SHARED],

668 ** <li> [SQLITE_LOCK_RESERVED],

669 ** <li> [SQLITE_LOCK_PENDING], or

670 ** <li> [SQLITE_LOCK_EXCLUSIVE].

671 ** </ul>

672 ** xLock() increases the lock. xUnlock() decreases the lock.

673 ** The xCheckReservedLock() method checks whether any database connection,

674 ** either in this process or in some other process, is holding a RESERVED,

675 ** PENDING, or EXCLUSIVE lock on the file. It returns true

676 ** if such a lock exists and false otherwise.

677 **

678 ** The xFileControl() method is a generic interface that allows custom

679 ** VFS implementations to directly control an open file using the

680 ** [sqlite3_file_control()] interface. The second "op" argument is an

681 ** integer opcode. The third argument is a generic pointer intended to

682 ** point to a structure that may contain arguments or space in which to

683 ** write return values. Potential uses for xFileControl() might be

684 ** functions to enable blocking locks with timeouts, to change the

685 ** locking strategy (for example to use dot-file locks), to inquire

686 ** about the status of a lock, or to break stale locks. The SQLite

687 ** core reserves all opcodes less than 100 for its own use.

688 ** A [file control opcodes \| list of opcodes] less than 100 is available.

689 ** Applications that define a custom xFileControl method should use opcodes

690 ** greater than 100 to avoid conflicts. VFS implementations should

691 ** return [SQLITE_NOTFOUND] for file control opcodes that they do not

692 ** recognize.

693 **

694 ** The xSectorSize() method returns the sector size of the

695 ** device that underlies the file. The sector size is the

696 ** minimum write that can be performed without disturbing

697 ** other bytes in the file. The xDeviceCharacteristics()

698 ** method returns a bit vector describing behaviors of the

699 ** underlying device:

700 **

701 ** <ul>

702 ** <li> [SQLITE_IOCAP_ATOMIC]

703 ** <li> [SQLITE_IOCAP_ATOMIC512]

704 ** <li> [SQLITE_IOCAP_ATOMIC1K]

705 ** <li> [SQLITE_IOCAP_ATOMIC2K]

706 ** <li> [SQLITE_IOCAP_ATOMIC4K]

707 ** <li> [SQLITE_IOCAP_ATOMIC8K]

708 ** <li> [SQLITE_IOCAP_ATOMIC16K]

709 ** <li> [SQLITE_IOCAP_ATOMIC32K]

710 ** <li> [SQLITE_IOCAP_ATOMIC64K]

711 ** <li> [SQLITE_IOCAP_SAFE_APPEND]

712 ** <li> [SQLITE_IOCAP_SEQUENTIAL]

713 ** </ul>

714 **

715 ** The SQLITE_IOCAP_ATOMIC property means that all writes of

716 ** any size are atomic. The SQLITE_IOCAP_ATOMICnnn values

717 ** mean that writes of blocks that are nnn bytes in size and

718 ** are aligned to an address which is an integer multiple of

719 ** nnn are atomic. The SQLITE_IOCAP_SAFE_APPEND value means

720 ** that when data is appended to a file, the data is appended

721 ** first then the size of the file is extended, never the other

722 ** way around. The SQLITE_IOCAP_SEQUENTIAL property means that

723 ** information is written to disk in the same order as calls

724 ** to xWrite().

725 **

726 ** If xRead() returns SQLITE_IOERR_SHORT_READ it must also fill

727 ** in the unread portions of the buffer with zeros. A VFS that

728 ** fails to zero-fill short reads might seem to work. However,

729 ** failure to zero-fill short reads will eventually lead to

730 ** database corruption.

731 */

732 typedef struct sqlite3_io_methods sqlite3_io_methods;

733 struct sqlite3_io_methods {

734 int iVersion;

735 int (xClose)(sqlite3_file);

736 int (xRead)(sqlite3_file, void*, int iAmt, sqlite3_int64 iOfst);

737 int (xWrite)(sqlite3_file, const void*, int iAmt, sqlite3_int64 iOfst);

738 int (xTruncate)(sqlite3_file, sqlite3_int64 size);

739 int (xSync)(sqlite3_file, int flags);

740 int (xFileSize)(sqlite3_file, sqlite3_int64 *pSize);

741 int (xLock)(sqlite3_file, int);

742 int (xUnlock)(sqlite3_file, int);

743 int (xCheckReservedLock)(sqlite3_file, int *pResOut);

744 int (xFileControl)(sqlite3_file, int op, void *pArg);

745 int (xSectorSize)(sqlite3_file);

746 int (xDeviceCharacteristics)(sqlite3_file);

747 /* Methods above are valid for version 1 */

748 int (xShmMap)(sqlite3_file, int iPg, int pgsz, int, void volatile**);

749 int (xShmLock)(sqlite3_file, int offset, int n, int flags);

750 void (xShmBarrier)(sqlite3_file);

751 int (xShmUnmap)(sqlite3_file, int deleteFlag);

752 /* Methods above are valid for version 2 */

753 int (xFetch)(sqlite3_file, sqlite3_int64 iOfst, int iAmt, void **pp);

754 int (xUnfetch)(sqlite3_file, sqlite3_int64 iOfst, void *p);

755 /* Methods above are valid for version 3 */

756 /* Additional methods may be added in future releases */

757 };

758

759 /*

760 ** CAPI3REF: Standard File Control Opcodes

761 ** KEYWORDS: {file control opcodes} {file control opcode}

762 **

763 ** These integer constants are opcodes for the xFileControl method

764 ** of the [sqlite3_io_methods] object and for the [sqlite3_file_control()]

765 ** interface.

766 **

767 ** <ul>

768 ** <li>[[SQLITE_FCNTL_LOCKSTATE]]

769 ** The [SQLITE_FCNTL_LOCKSTATE] opcode is used for debugging. This

770 ** opcode causes the xFileControl method to write the current state of

771 ** the lock (one of [SQLITE_LOCK_NONE], [SQLITE_LOCK_SHARED],

772 ** [SQLITE_LOCK_RESERVED], [SQLITE_LOCK_PENDING], or [SQLITE_LOCK_EXCLUSIVE])

773 ** into an integer that the pArg argument points to. This capability

774 ** is used during testing and is only available when the SQLITE_TEST

775 ** compile-time option is used.

776 **

777 ** <li>[[SQLITE_FCNTL_SIZE_HINT]]

778 ** The [SQLITE_FCNTL_SIZE_HINT] opcode is used by SQLite to give the VFS

779 ** layer a hint of how large the database file will grow to be during the

780 ** current transaction. This hint is not guaranteed to be accurate but it

781 ** is often close. The underlying VFS might choose to preallocate database

782 ** file space based on this hint in order to help writes to the database

783 ** file run faster.

784 **

785 ** <li>[[SQLITE_FCNTL_CHUNK_SIZE]]

786 ** The [SQLITE_FCNTL_CHUNK_SIZE] opcode is used to request that the VFS

787 ** extends and truncates the database file in chunks of a size specified

788 ** by the user. The fourth argument to [sqlite3_file_control()] should

789 ** point to an integer (type int) containing the new chunk-size to use

790 ** for the nominated database. Allocating database file space in large

791 ** chunks (say 1MB at a time), may reduce file-system fragmentation and

792 ** improve performance on some systems.

793 **

794 ** <li>[[SQLITE_FCNTL_FILE_POINTER]]

795 ** The [SQLITE_FCNTL_FILE_POINTER] opcode is used to obtain a pointer

796 ** to the [sqlite3_file] object associated with a particular database

797 ** connection. See also [SQLITE_FCNTL_JOURNAL_POINTER].

798 **

799 ** <li>[[SQLITE_FCNTL_JOURNAL_POINTER]]

800 ** The [SQLITE_FCNTL_JOURNAL_POINTER] opcode is used to obtain a pointer

801 ** to the [sqlite3_file] object associated with the journal file (either

802 ** the [rollback journal] or the [write-ahead log]) for a particular database

803 ** connection. See also [SQLITE_FCNTL_FILE_POINTER].

804 **

805 ** <li>[[SQLITE_FCNTL_SYNC_OMITTED]]

806 ** No longer in use.

807 **

808 ** <li>[[SQLITE_FCNTL_SYNC]]

809 ** The [SQLITE_FCNTL_SYNC] opcode is generated internally by SQLite and

810 ** sent to the VFS immediately before the xSync method is invoked on a

811 ** database file descriptor. Or, if the xSync method is not invoked

812 ** because the user has configured SQLite with

813 ** [PRAGMA synchronous \| PRAGMA synchronous=OFF] it is invoked in place

814 ** of the xSync method. In most cases, the pointer argument passed with

815 ** this file-control is NULL. However, if the database file is being synced

816 ** as part of a multi-database commit, the argument points to a nul-terminated

817 ** string containing the transactions master-journal file name. VFSes that

818 ** do not need this signal should silently ignore this opcode. Applications

819 ** should not call [sqlite3_file_control()] with this opcode as doing so may

820 ** disrupt the operation of the specialized VFSes that do require it.

821 **

822 ** <li>[[SQLITE_FCNTL_COMMIT_PHASETWO]]

823 ** The [SQLITE_FCNTL_COMMIT_PHASETWO] opcode is generated internally by SQLite

824 ** and sent to the VFS after a transaction has been committed immediately

825 ** but before the database is unlocked. VFSes that do not need this signal

826 ** should silently ignore this opcode. Applications should not call

827 ** [sqlite3_file_control()] with this opcode as doing so may disrupt the

828 ** operation of the specialized VFSes that do require it.

829 **

830 ** <li>[[SQLITE_FCNTL_WIN32_AV_RETRY]]

831 ** ^The [SQLITE_FCNTL_WIN32_AV_RETRY] opcode is used to configure automatic

832 ** retry counts and intervals for certain disk I/O operations for the

833 ** windows [VFS] in order to provide robustness in the presence of

834 ** anti-virus programs. By default, the windows VFS will retry file read,

835 ** file write, and file delete operations up to 10 times, with a delay

836 ** of 25 milliseconds before the first retry and with the delay increasing

837 ** by an additional 25 milliseconds with each subsequent retry. This

838 ** opcode allows these two values (10 retries and 25 milliseconds of delay)

839 ** to be adjusted. The values are changed for all database connections

840 ** within the same process. The argument is a pointer to an array of two

841 ** integers where the first integer i the new retry count and the second

842 ** integer is the delay. If either integer is negative, then the setting

843 ** is not changed but instead the prior value of that setting is written

844 ** into the array entry, allowing the current retry settings to be

845 ** interrogated. The zDbName parameter is ignored.

846 **

847 ** <li>[[SQLITE_FCNTL_PERSIST_WAL]]

848 ** ^The [SQLITE_FCNTL_PERSIST_WAL] opcode is used to set or query the

849 ** persistent [WAL \| Write Ahead Log] setting. By default, the auxiliary

850 ** write ahead log and shared memory files used for transaction control

851 ** are automatically deleted when the latest connection to the database

852 ** closes. Setting persistent WAL mode causes those files to persist after

853 ** close. Persisting the files is useful when other processes that do not

854 ** have write permission on the directory containing the database file want

855 ** to read the database file, as the WAL and shared memory files must exist

856 ** in order for the database to be readable. The fourth parameter to

857 ** [sqlite3_file_control()] for this opcode should be a pointer to an integer.

858 ** That integer is 0 to disable persistent WAL mode or 1 to enable persistent

859 ** WAL mode. If the integer is -1, then it is overwritten with the current

860 ** WAL persistence setting.

861 **

862 ** <li>[[SQLITE_FCNTL_POWERSAFE_OVERWRITE]]

863 ** ^The [SQLITE_FCNTL_POWERSAFE_OVERWRITE] opcode is used to set or query the

864 ** persistent "powersafe-overwrite" or "PSOW" setting. The PSOW setting

865 ** determines the [SQLITE_IOCAP_POWERSAFE_OVERWRITE] bit of the

866 ** xDeviceCharacteristics methods. The fourth parameter to

867 ** [sqlite3_file_control()] for this opcode should be a pointer to an integer.

868 ** That integer is 0 to disable zero-damage mode or 1 to enable zero-damage

869 ** mode. If the integer is -1, then it is overwritten with the current

870 ** zero-damage mode setting.

871 **

872 ** <li>[[SQLITE_FCNTL_OVERWRITE]]

873 ** ^The [SQLITE_FCNTL_OVERWRITE] opcode is invoked by SQLite after opening

874 ** a write transaction to indicate that, unless it is rolled back for some

875 ** reason, the entire database file will be overwritten by the current

876 ** transaction. This is used by VACUUM operations.

877 **

878 ** <li>[[SQLITE_FCNTL_VFSNAME]]

879 ** ^The [SQLITE_FCNTL_VFSNAME] opcode can be used to obtain the names of

880 ** all [VFSes] in the VFS stack. The names are of all VFS shims and the

881 ** final bottom-level VFS are written into memory obtained from

882 ** [sqlite3_malloc()] and the result is stored in the char* variable

883 ** that the fourth parameter of [sqlite3_file_control()] points to.

884 ** The caller is responsible for freeing the memory when done. As with

885 ** all file-control actions, there is no guarantee that this will actually

886 ** do anything. Callers should initialize the char* variable to a NULL

887 ** pointer in case this file-control is not implemented. This file-control

888 ** is intended for diagnostic use only.

889 **

890 ** <li>[[SQLITE_FCNTL_VFS_POINTER]]

891 ** ^The [SQLITE_FCNTL_VFS_POINTER] opcode finds a pointer to the top-level

892 ** [VFSes] currently in use. ^(The argument X in

893 ** sqlite3_file_control(db,SQLITE_FCNTL_VFS_POINTER,X) must be

894 of type "[sqlite3_vfs] ". This opcodes will set *X

895 ** to a pointer to the top-level VFS.)^

896 ** ^When there are multiple VFS shims in the stack, this opcode finds the

897 ** upper-most shim only.

898 **

899 ** <li>[[SQLITE_FCNTL_PRAGMA]]

900 ** ^Whenever a [PRAGMA] statement is parsed, an [SQLITE_FCNTL_PRAGMA]

901 ** file control is sent to the open [sqlite3_file] object corresponding

902 ** to the database file to which the pragma statement refers. ^The argument

903 ** to the [SQLITE_FCNTL_PRAGMA] file control is an array of

904 pointers to strings (char) in which the second element of the array

905 ** is the name of the pragma and the third element is the argument to the

906 ** pragma or NULL if the pragma has no argument. ^The handler for an

907 ** [SQLITE_FCNTL_PRAGMA] file control can optionally make the first element

908 of the char argument point to a string obtained from [sqlite3_mprintf()]

909 ** or the equivalent and that string will become the result of the pragma or

910 ** the error message if the pragma fails. ^If the

911 ** [SQLITE_FCNTL_PRAGMA] file control returns [SQLITE_NOTFOUND], then normal

912 ** [PRAGMA] processing continues. ^If the [SQLITE_FCNTL_PRAGMA]

913 ** file control returns [SQLITE_OK], then the parser assumes that the

914 ** VFS has handled the PRAGMA itself and the parser generates a no-op

915 ** prepared statement if result string is NULL, or that returns a copy

916 ** of the result string if the string is non-NULL.

917 ** ^If the [SQLITE_FCNTL_PRAGMA] file control returns

918 ** any result code other than [SQLITE_OK] or [SQLITE_NOTFOUND], that means

919 ** that the VFS encountered an error while handling the [PRAGMA] and the

920 ** compilation of the PRAGMA fails with an error. ^The [SQLITE_FCNTL_PRAGMA]

921 ** file control occurs at the beginning of pragma statement analysis and so

922 ** it is able to override built-in [PRAGMA] statements.

923 **

924 ** <li>[[SQLITE_FCNTL_BUSYHANDLER]]

925 ** ^The [SQLITE_FCNTL_BUSYHANDLER]

926 ** file-control may be invoked by SQLite on the database file handle

927 ** shortly after it is opened in order to provide a custom VFS with access

928 to the connections busy-handler callback. The argument is of type (void )

929 ** - an array of two (void ) values. The first (void ) actually points

930 ** to a function of type (int ()(void )). In order to invoke the connections

931 ** busy-handler, this function should be invoked with the second (void *) in

932 ** the array as the only argument. If it returns non-zero, then the operation

933 ** should be retried. If it returns zero, the custom VFS should abandon the

934 ** current operation.

935 **

936 ** <li>[[SQLITE_FCNTL_TEMPFILENAME]]

937 ** ^Application can invoke the [SQLITE_FCNTL_TEMPFILENAME] file-control

938 ** to have SQLite generate a

939 ** temporary filename using the same algorithm that is followed to generate

940 ** temporary filenames for TEMP tables and other internal uses. The

941 argument should be a char which will be filled with the filename

942 ** written into memory obtained from [sqlite3_malloc()]. The caller should

943 ** invoke [sqlite3_free()] on the result to avoid a memory leak.

944 **

945 ** <li>[[SQLITE_FCNTL_MMAP_SIZE]]

946 ** The [SQLITE_FCNTL_MMAP_SIZE] file control is used to query or set the

947 ** maximum number of bytes that will be used for memory-mapped I/O.

948 ** The argument is a pointer to a value of type sqlite3_int64 that

949 ** is an advisory maximum number of bytes in the file to memory map. The

950 ** pointer is overwritten with the old value. The limit is not changed if

951 ** the value originally pointed to is negative, and so the current limit

952 ** can be queried by passing in a pointer to a negative number. This

953 ** file-control is used internally to implement [PRAGMA mmap_size].

954 **

955 ** <li>[[SQLITE_FCNTL_TRACE]]

956 ** The [SQLITE_FCNTL_TRACE] file control provides advisory information

957 ** to the VFS about what the higher layers of the SQLite stack are doing.

958 ** This file control is used by some VFS activity tracing [shims].

959 ** The argument is a zero-terminated string. Higher layers in the

960 ** SQLite stack may generate instances of this file control if

961 ** the [SQLITE_USE_FCNTL_TRACE] compile-time option is enabled.

962 **

963 ** <li>[[SQLITE_FCNTL_HAS_MOVED]]

964 ** The [SQLITE_FCNTL_HAS_MOVED] file control interprets its argument as a

965 ** pointer to an integer and it writes a boolean into that integer depending

966 ** on whether or not the file has been renamed, moved, or deleted since it

967 ** was first opened.

968 **

969 ** <li>[[SQLITE_FCNTL_WIN32_SET_HANDLE]]

970 ** The [SQLITE_FCNTL_WIN32_SET_HANDLE] opcode is used for debugging. This

971 ** opcode causes the xFileControl method to swap the file handle with the one

972 ** pointed to by the pArg argument. This capability is used during testing

973 ** and only needs to be supported when SQLITE_TEST is defined.

974 **

975 ** <li>[[SQLITE_FCNTL_WAL_BLOCK]]

976 ** The [SQLITE_FCNTL_WAL_BLOCK] is a signal to the VFS layer that it might

977 ** be advantageous to block on the next WAL lock if the lock is not immediately

978 ** available. The WAL subsystem issues this signal during rare

979 ** circumstances in order to fix a problem with priority inversion.

980 ** Applications should <em>not</em> use this file-control.

981 **

982 ** <li>[[SQLITE_FCNTL_ZIPVFS]]

983 ** The [SQLITE_FCNTL_ZIPVFS] opcode is implemented by zipvfs only. All other

984 ** VFS should return SQLITE_NOTFOUND for this opcode.

985 **

986 ** <li>[[SQLITE_FCNTL_RBU]]

987 ** The [SQLITE_FCNTL_RBU] opcode is implemented by the special VFS used by

988 ** the RBU extension only. All other VFS should return SQLITE_NOTFOUND for

989 ** this opcode.

990 ** </ul>

991 */

992 #define SQLITE_FCNTL_LOCKSTATE 1

993 #define SQLITE_FCNTL_GET_LOCKPROXYFILE 2

994 #define SQLITE_FCNTL_SET_LOCKPROXYFILE 3

995 #define SQLITE_FCNTL_LAST_ERRNO 4

996 #define SQLITE_FCNTL_SIZE_HINT 5

997 #define SQLITE_FCNTL_CHUNK_SIZE 6

998 #define SQLITE_FCNTL_FILE_POINTER 7

999 #define SQLITE_FCNTL_SYNC_OMITTED 8

1000 #define SQLITE_FCNTL_WIN32_AV_RETRY 9

1001 #define SQLITE_FCNTL_PERSIST_WAL 10

1002 #define SQLITE_FCNTL_OVERWRITE 11

1003 #define SQLITE_FCNTL_VFSNAME 12

1004 #define SQLITE_FCNTL_POWERSAFE_OVERWRITE 13

1005 #define SQLITE_FCNTL_PRAGMA 14

1006 #define SQLITE_FCNTL_BUSYHANDLER 15

1007 #define SQLITE_FCNTL_TEMPFILENAME 16

1008 #define SQLITE_FCNTL_MMAP_SIZE 18

1009 #define SQLITE_FCNTL_TRACE 19

1010 #define SQLITE_FCNTL_HAS_MOVED 20

1011 #define SQLITE_FCNTL_SYNC 21

1012 #define SQLITE_FCNTL_COMMIT_PHASETWO 22

1013 #define SQLITE_FCNTL_WIN32_SET_HANDLE 23

1014 #define SQLITE_FCNTL_WAL_BLOCK 24

1015 #define SQLITE_FCNTL_ZIPVFS 25

1016 #define SQLITE_FCNTL_RBU 26

1017 #define SQLITE_FCNTL_VFS_POINTER 27

1018 #define SQLITE_FCNTL_JOURNAL_POINTER 28

1019

1020 /* deprecated names */

1021 #define SQLITE_GET_LOCKPROXYFILE SQLITE_FCNTL_GET_LOCKPROXYFILE

1022 #define SQLITE_SET_LOCKPROXYFILE SQLITE_FCNTL_SET_LOCKPROXYFILE

1023 #define SQLITE_LAST_ERRNO SQLITE_FCNTL_LAST_ERRNO

1024

1025

1026 /*

1027 ** CAPI3REF: Mutex Handle

1028 **

1029 ** The mutex module within SQLite defines [sqlite3_mutex] to be an

1030 ** abstract type for a mutex object. The SQLite core never looks

1031 ** at the internal representation of an [sqlite3_mutex]. It only

1032 ** deals with pointers to the [sqlite3_mutex] object.

1033 **

1034 ** Mutexes are created using [sqlite3_mutex_alloc()].

1035 */

1036 typedef struct sqlite3_mutex sqlite3_mutex;

1037

1038 /*

1039 ** CAPI3REF: OS Interface Object

1040 **

1041 ** An instance of the sqlite3_vfs object defines the interface between

1042 ** the SQLite core and the underlying operating system. The "vfs"

1043 ** in the name of the object stands for "virtual file system". See

1044 ** the [VFS \| VFS documentation] for further information.

1045 **

1046 ** The value of the iVersion field is initially 1 but may be larger in

1047 ** future versions of SQLite. Additional fields may be appended to this

1048 ** object when the iVersion value is increased. Note that the structure

1049 ** of the sqlite3_vfs object changes in the transaction between

1050 ** SQLite version 3.5.9 and 3.6.0 and yet the iVersion field was not

1051 ** modified.

1052 **

1053 ** The szOsFile field is the size of the subclassed [sqlite3_file]

1054 ** structure used by this VFS. mxPathname is the maximum length of

1055 ** a pathname in this VFS.

1056 **

1057 ** Registered sqlite3_vfs objects are kept on a linked list formed by

1058 ** the pNext pointer. The [sqlite3_vfs_register()]

1059 ** and [sqlite3_vfs_unregister()] interfaces manage this list

1060 ** in a thread-safe way. The [sqlite3_vfs_find()] interface

1061 ** searches the list. Neither the application code nor the VFS

1062 ** implementation should use the pNext pointer.

1063 **

1064 ** The pNext field is the only field in the sqlite3_vfs

1065 ** structure that SQLite will ever modify. SQLite will only access

1066 ** or modify this field while holding a particular static mutex.

1067 ** The application should never modify anything within the sqlite3_vfs

1068 ** object once the object has been registered.

1069 **

1070 ** The zName field holds the name of the VFS module. The name must

1071 ** be unique across all VFS modules.

1072 **

1073 ** [[sqlite3_vfs.xOpen]]

1074 ** ^SQLite guarantees that the zFilename parameter to xOpen

1075 ** is either a NULL pointer or string obtained

1076 ** from xFullPathname() with an optional suffix added.

1077 ** ^If a suffix is added to the zFilename parameter, it will

1078 ** consist of a single "-" character followed by no more than

1079 ** 11 alphanumeric and/or "-" characters.

1080 ** ^SQLite further guarantees that

1081 ** the string will be valid and unchanged until xClose() is

1082 ** called. Because of the previous sentence,

1083 ** the [sqlite3_file] can safely store a pointer to the

1084 ** filename if it needs to remember the filename for some reason.

1085 ** If the zFilename parameter to xOpen is a NULL pointer then xOpen

1086 ** must invent its own temporary name for the file. ^Whenever the

1087 ** xFilename parameter is NULL it will also be the case that the

1088 ** flags parameter will include [SQLITE_OPEN_DELETEONCLOSE].

1089 **

1090 ** The flags argument to xOpen() includes all bits set in

1091 ** the flags argument to [sqlite3_open_v2()]. Or if [sqlite3_open()]

1092 ** or [sqlite3_open16()] is used, then flags includes at least

1093 ** [SQLITE_OPEN_READWRITE] \| [SQLITE_OPEN_CREATE].

1094 ** If xOpen() opens a file read-only then it sets *pOutFlags to

1095 ** include [SQLITE_OPEN_READONLY]. Other bits in *pOutFlags may be set.

1096 **

1097 ** ^(SQLite will also add one of the following flags to the xOpen()

1098 ** call, depending on the object being opened:

1099 **

1100 ** <ul>

1101 ** <li> [SQLITE_OPEN_MAIN_DB]

1102 ** <li> [SQLITE_OPEN_MAIN_JOURNAL]

1103 ** <li> [SQLITE_OPEN_TEMP_DB]

1104 ** <li> [SQLITE_OPEN_TEMP_JOURNAL]

1105 ** <li> [SQLITE_OPEN_TRANSIENT_DB]

1106 ** <li> [SQLITE_OPEN_SUBJOURNAL]

1107 ** <li> [SQLITE_OPEN_MASTER_JOURNAL]

1108 ** <li> [SQLITE_OPEN_WAL]

1109 ** </ul>)^

1110 **

1111 ** The file I/O implementation can use the object type flags to

1112 ** change the way it deals with files. For example, an application

1113 ** that does not care about crash recovery or rollback might make

1114 ** the open of a journal file a no-op. Writes to this journal would

1115 ** also be no-ops, and any attempt to read the journal would return

1116 ** SQLITE_IOERR. Or the implementation might recognize that a database

1117 ** file will be doing page-aligned sector reads and writes in a random

1118 ** order and set up its I/O subsystem accordingly.

1119 **

1120 ** SQLite might also add one of the following flags to the xOpen method:

1121 **

1122 ** <ul>

1123 ** <li> [SQLITE_OPEN_DELETEONCLOSE]

1124 ** <li> [SQLITE_OPEN_EXCLUSIVE]

1125 ** </ul>

1126 **

1127 ** The [SQLITE_OPEN_DELETEONCLOSE] flag means the file should be

1128 ** deleted when it is closed. ^The [SQLITE_OPEN_DELETEONCLOSE]

1129 ** will be set for TEMP databases and their journals, transient

1130 ** databases, and subjournals.

1131 **

1132 ** ^The [SQLITE_OPEN_EXCLUSIVE] flag is always used in conjunction

1133 ** with the [SQLITE_OPEN_CREATE] flag, which are both directly

1134 ** analogous to the O_EXCL and O_CREAT flags of the POSIX open()

1135 ** API. The SQLITE_OPEN_EXCLUSIVE flag, when paired with the

1136 ** SQLITE_OPEN_CREATE, is used to indicate that file should always

1137 ** be created, and that it is an error if it already exists.

1138 ** It is <i>not</i> used to indicate the file should be opened

1139 ** for exclusive access.

1140 **

1141 ** ^At least szOsFile bytes of memory are allocated by SQLite

1142 ** to hold the [sqlite3_file] structure passed as the third

1143 ** argument to xOpen. The xOpen method does not have to

1144 ** allocate the structure; it should just fill it in. Note that

1145 ** the xOpen method must set the sqlite3_file.pMethods to either

1146 ** a valid [sqlite3_io_methods] object or to NULL. xOpen must do

1147 ** this even if the open fails. SQLite expects that the sqlite3_file.pMethods

1148 ** element will be valid after xOpen returns regardless of the success

1149 ** or failure of the xOpen call.

1150 **

1151 ** [[sqlite3_vfs.xAccess]]

1152 ** ^The flags argument to xAccess() may be [SQLITE_ACCESS_EXISTS]

1153 ** to test for the existence of a file, or [SQLITE_ACCESS_READWRITE] to

1154 ** test whether a file is readable and writable, or [SQLITE_ACCESS_READ]

1155 ** to test whether a file is at least readable. The file can be a

1156 ** directory.

1157 **

1158 ** ^SQLite will always allocate at least mxPathname+1 bytes for the

1159 ** output buffer xFullPathname. The exact size of the output buffer

1160 ** is also passed as a parameter to both methods. If the output buffer

1161 ** is not large enough, [SQLITE_CANTOPEN] should be returned. Since this is

1162 ** handled as a fatal error by SQLite, vfs implementations should endeavor

1163 ** to prevent this by setting mxPathname to a sufficiently large value.

1164 **

1165 ** The xRandomness(), xSleep(), xCurrentTime(), and xCurrentTimeInt64()

1166 ** interfaces are not strictly a part of the filesystem, but they are

1167 ** included in the VFS structure for completeness.

1168 ** The xRandomness() function attempts to return nBytes bytes

1169 ** of good-quality randomness into zOut. The return value is

1170 ** the actual number of bytes of randomness obtained.

1171 ** The xSleep() method causes the calling thread to sleep for at

1172 ** least the number of microseconds given. ^The xCurrentTime()

1173 ** method returns a Julian Day Number for the current date and time as

1174 ** a floating point value.

1175 ** ^The xCurrentTimeInt64() method returns, as an integer, the Julian

1176 ** Day Number multiplied by 86400000 (the number of milliseconds in

1177 ** a 24-hour day).

1178 ** ^SQLite will use the xCurrentTimeInt64() method to get the current

1179 ** date and time if that method is available (if iVersion is 2 or

1180 ** greater and the function pointer is not NULL) and will fall back

1181 ** to xCurrentTime() if xCurrentTimeInt64() is unavailable.

1182 **

1183 ** ^The xSetSystemCall(), xGetSystemCall(), and xNestSystemCall() interfaces

1184 ** are not used by the SQLite core. These optional interfaces are provided

1185 ** by some VFSes to facilitate testing of the VFS code. By overriding

1186 ** system calls with functions under its control, a test program can

1187 ** simulate faults and error conditions that would otherwise be difficult

1188 ** or impossible to induce. The set of system calls that can be overridden

1189 ** varies from one VFS to another, and from one version of the same VFS to the

1190 ** next. Applications that use these interfaces must be prepared for any

1191 ** or all of these interfaces to be NULL or for their behavior to change

1192 ** from one release to the next. Applications must not attempt to access

1193 ** any of these methods if the iVersion of the VFS is less than 3.

1194 */

1195 typedef struct sqlite3_vfs sqlite3_vfs;

1196 typedef void (*sqlite3_syscall_ptr)(void);

1197 struct sqlite3_vfs {

1198 int iVersion; /* Structure version number (currently 3) */

1199 int szOsFile; /* Size of subclassed sqlite3_file */

1200 int mxPathname; /* Maximum file pathname length */

1201 sqlite3_vfs pNext; / Next registered VFS */

1202 const char zName; / Name of this virtual file system */

1203 void pAppData; / Pointer to application-specific data */

1204 int (xOpen)(sqlite3_vfs, const char zName, sqlite3_file,

1205 int flags, int *pOutFlags);

1206 int (xDelete)(sqlite3_vfs, const char *zName, int syncDir);

1207 int (xAccess)(sqlite3_vfs, const char zName, int flags, int pResOut);

1208 int (xFullPathname)(sqlite3_vfs, const char zName, int nOut, char zOut);

1209 void (xDlOpen)(sqlite3_vfs, const char zFilename);

1210 void (xDlError)(sqlite3_vfs, int nByte, char *zErrMsg);

1211 void ((xDlSym)(sqlite3_vfs,void, const char *zSymbol))(void);

1212 void (xDlClose)(sqlite3_vfs, void*);

1213 int (xRandomness)(sqlite3_vfs, int nByte, char *zOut);

1214 int (xSleep)(sqlite3_vfs, int microseconds);

1215 int (xCurrentTime)(sqlite3_vfs, double*);

1216 int (xGetLastError)(sqlite3_vfs, int, char *);

1217 /*

1218 ** The methods above are in version 1 of the sqlite_vfs object

1219 ** definition. Those that follow are added in version 2 or later

1220 */

1221 int (xCurrentTimeInt64)(sqlite3_vfs, sqlite3_int64*);

1222 /*

1223 ** The methods above are in versions 1 and 2 of the sqlite_vfs object.

1224 ** Those below are for version 3 and greater.

1225 */

1226 int (xSetSystemCall)(sqlite3_vfs, const char *zName, sqlite3_syscall_ptr);

1227 sqlite3_syscall_ptr (xGetSystemCall)(sqlite3_vfs, const char *zName);

1228 const char (xNextSystemCall)(sqlite3_vfs, const char zName);

1229 /*

1230 ** The methods above are in versions 1 through 3 of the sqlite_vfs object.

1231 ** New fields may be appended in figure versions. The iVersion

1232 ** value will increment whenever this happens.

1233 */

1234 };

1235

1236 /*

1237 ** CAPI3REF: Flags for the xAccess VFS method

1238 **

1239 ** These integer constants can be used as the third parameter to

1240 ** the xAccess method of an [sqlite3_vfs] object. They determine

1241 ** what kind of permissions the xAccess method is looking for.

1242 ** With SQLITE_ACCESS_EXISTS, the xAccess method

1243 ** simply checks whether the file exists.

1244 ** With SQLITE_ACCESS_READWRITE, the xAccess method

1245 ** checks whether the named directory is both readable and writable

1246 ** (in other words, if files can be added, removed, and renamed within

1247 ** the directory).

1248 ** The SQLITE_ACCESS_READWRITE constant is currently used only by the

1249 ** [temp_store_directory pragma], though this could change in a future

1250 ** release of SQLite.

1251 ** With SQLITE_ACCESS_READ, the xAccess method

1252 ** checks whether the file is readable. The SQLITE_ACCESS_READ constant is

1253 ** currently unused, though it might be used in a future release of

1254 ** SQLite.

1255 */

1256 #define SQLITE_ACCESS_EXISTS 0

1257 #define SQLITE_ACCESS_READWRITE 1 /* Used by PRAGMA temp_store_directory */

1258 #define SQLITE_ACCESS_READ 2 /* Unused */

1259

1260 /*

1261 ** CAPI3REF: Flags for the xShmLock VFS method

1262 **

1263 ** These integer constants define the various locking operations

1264 ** allowed by the xShmLock method of [sqlite3_io_methods]. The

1265 ** following are the only legal combinations of flags to the

1266 ** xShmLock method:

1267 **

1268 ** <ul>

1269 ** <li> SQLITE_SHM_LOCK \| SQLITE_SHM_SHARED

1270 ** <li> SQLITE_SHM_LOCK \| SQLITE_SHM_EXCLUSIVE

1271 ** <li> SQLITE_SHM_UNLOCK \| SQLITE_SHM_SHARED

1272 ** <li> SQLITE_SHM_UNLOCK \| SQLITE_SHM_EXCLUSIVE

1273 ** </ul>

1274 **

1275 ** When unlocking, the same SHARED or EXCLUSIVE flag must be supplied as

1276 ** was given on the corresponding lock.

1277 **

1278 ** The xShmLock method can transition between unlocked and SHARED or

1279 ** between unlocked and EXCLUSIVE. It cannot transition between SHARED

1280 ** and EXCLUSIVE.

1281 */

1282 #define SQLITE_SHM_UNLOCK 1

1283 #define SQLITE_SHM_LOCK 2

1284 #define SQLITE_SHM_SHARED 4

1285 #define SQLITE_SHM_EXCLUSIVE 8

1286

1287 /*

1288 ** CAPI3REF: Maximum xShmLock index

1289 **

1290 ** The xShmLock method on [sqlite3_io_methods] may use values

1291 ** between 0 and this upper bound as its "offset" argument.

1292 ** The SQLite core will never attempt to acquire or release a

1293 ** lock outside of this range

1294 */

1295 #define SQLITE_SHM_NLOCK 8

1296

1297

1298 /*

1299 ** CAPI3REF: Initialize The SQLite Library

1300 **

1301 ** ^The sqlite3_initialize() routine initializes the

1302 ** SQLite library. ^The sqlite3_shutdown() routine

1303 ** deallocates any resources that were allocated by sqlite3_initialize().

1304 ** These routines are designed to aid in process initialization and

1305 ** shutdown on embedded systems. Workstation applications using

1306 ** SQLite normally do not need to invoke either of these routines.

1307 **

1308 ** A call to sqlite3_initialize() is an "effective" call if it is

1309 ** the first time sqlite3_initialize() is invoked during the lifetime of

1310 ** the process, or if it is the first time sqlite3_initialize() is invoked

1311 ** following a call to sqlite3_shutdown(). ^(Only an effective call

1312 ** of sqlite3_initialize() does any initialization. All other calls

1313 ** are harmless no-ops.)^

1314 **

1315 ** A call to sqlite3_shutdown() is an "effective" call if it is the first

1316 ** call to sqlite3_shutdown() since the last sqlite3_initialize(). ^(Only

1317 ** an effective call to sqlite3_shutdown() does any deinitialization.

1318 ** All other valid calls to sqlite3_shutdown() are harmless no-ops.)^

1319 **

1320 ** The sqlite3_initialize() interface is threadsafe, but sqlite3_shutdown()

1321 ** is not. The sqlite3_shutdown() interface must only be called from a

1322 ** single thread. All open [database connections] must be closed and all

1323 ** other SQLite resources must be deallocated prior to invoking

1324 ** sqlite3_shutdown().

1325 **

1326 ** Among other things, ^sqlite3_initialize() will invoke

1327 ** sqlite3_os_init(). Similarly, ^sqlite3_shutdown()

1328 ** will invoke sqlite3_os_end().

1329 **

1330 ** ^The sqlite3_initialize() routine returns [SQLITE_OK] on success.

1331 ** ^If for some reason, sqlite3_initialize() is unable to initialize

1332 ** the library (perhaps it is unable to allocate a needed resource such

1333 ** as a mutex) it returns an [error code] other than [SQLITE_OK].

1334 **

1335 ** ^The sqlite3_initialize() routine is called internally by many other

1336 ** SQLite interfaces so that an application usually does not need to

1337 ** invoke sqlite3_initialize() directly. For example, [sqlite3_open()]

1338 ** calls sqlite3_initialize() so the SQLite library will be automatically

1339 ** initialized when [sqlite3_open()] is called if it has not be initialized

1340 ** already. ^However, if SQLite is compiled with the [SQLITE_OMIT_AUTOINIT]

1341 ** compile-time option, then the automatic calls to sqlite3_initialize()

1342 ** are omitted and the application must call sqlite3_initialize() directly

1343 ** prior to using any other SQLite interface. For maximum portability,

1344 ** it is recommended that applications always invoke sqlite3_initialize()

1345 ** directly prior to using any other SQLite interface. Future releases

1346 ** of SQLite may require this. In other words, the behavior exhibited

1347 ** when SQLite is compiled with [SQLITE_OMIT_AUTOINIT] might become the

1348 ** default behavior in some future release of SQLite.

1349 **

1350 ** The sqlite3_os_init() routine does operating-system specific

1351 ** initialization of the SQLite library. The sqlite3_os_end()

1352 ** routine undoes the effect of sqlite3_os_init(). Typical tasks

1353 ** performed by these routines include allocation or deallocation

1354 ** of static resources, initialization of global variables,

1355 ** setting up a default [sqlite3_vfs] module, or setting up

1356 ** a default configuration using [sqlite3_config()].

1357 **

1358 ** The application should never invoke either sqlite3_os_init()

1359 ** or sqlite3_os_end() directly. The application should only invoke

1360 ** sqlite3_initialize() and sqlite3_shutdown(). The sqlite3_os_init()

1361 ** interface is called automatically by sqlite3_initialize() and

1362 ** sqlite3_os_end() is called by sqlite3_shutdown(). Appropriate

1363 ** implementations for sqlite3_os_init() and sqlite3_os_end()

1364 ** are built into SQLite when it is compiled for Unix, Windows, or OS/2.

1365 ** When [custom builds \| built for other platforms]

1366 ** (using the [SQLITE_OS_OTHER=1] compile-time

1367 ** option) the application must supply a suitable implementation for

1368 ** sqlite3_os_init() and sqlite3_os_end(). An application-supplied

1369 ** implementation of sqlite3_os_init() or sqlite3_os_end()

1370 ** must return [SQLITE_OK] on success and some other [error code] upon

1371 ** failure.

1372 */

1373 int sqlite3_initialize(void);

1374 int sqlite3_shutdown(void);

1375 int sqlite3_os_init(void);

1376 int sqlite3_os_end(void);

1377

1378 /*

1379 ** CAPI3REF: Configuring The SQLite Library

1380 **

1381 ** The sqlite3_config() interface is used to make global configuration

1382 ** changes to SQLite in order to tune SQLite to the specific needs of

1383 ** the application. The default configuration is recommended for most

1384 ** applications and so this routine is usually not necessary. It is

1385 ** provided to support rare applications with unusual needs.

1386 **

1387 ** <b>The sqlite3_config() interface is not threadsafe. The application

1388 ** must ensure that no other SQLite interfaces are invoked by other

1389 ** threads while sqlite3_config() is running.</b>

1390 **

1391 ** The sqlite3_config() interface

1392 ** may only be invoked prior to library initialization using

1393 ** [sqlite3_initialize()] or after shutdown by [sqlite3_shutdown()].

1394 ** ^If sqlite3_config() is called after [sqlite3_initialize()] and before

1395 ** [sqlite3_shutdown()] then it will return SQLITE_MISUSE.

1396 ** Note, however, that ^sqlite3_config() can be called as part of the

1397 ** implementation of an application-defined [sqlite3_os_init()].

1398 **

1399 ** The first argument to sqlite3_config() is an integer

1400 ** [configuration option] that determines

1401 ** what property of SQLite is to be configured. Subsequent arguments

1402 ** vary depending on the [configuration option]

1403 ** in the first argument.

1404 **

1405 ** ^When a configuration option is set, sqlite3_config() returns [SQLITE_OK].

1406 ** ^If the option is unknown or SQLite is unable to set the option

1407 ** then this routine returns a non-zero [error code].

1408 */

1409 int sqlite3_config(int, ...);

1410

1411 /*

1412 ** CAPI3REF: Configure database connections

1413 ** METHOD: sqlite3

1414 **

1415 ** The sqlite3_db_config() interface is used to make configuration

1416 ** changes to a [database connection]. The interface is similar to

1417 ** [sqlite3_config()] except that the changes apply to a single

1418 ** [database connection] (specified in the first argument).

1419 **

1420 ** The second argument to sqlite3_db_config(D,V,...) is the

1421 ** [SQLITE_DBCONFIG_LOOKASIDE \| configuration verb] - an integer code

1422 ** that indicates what aspect of the [database connection] is being configured.

1423 ** Subsequent arguments vary depending on the configuration verb.

1424 **

1425 ** ^Calls to sqlite3_db_config() return SQLITE_OK if and only if

1426 ** the call is considered successful.

1427 */

1428 int sqlite3_db_config(sqlite3*, int op, ...);

1429

1430 /*

1431 ** CAPI3REF: Memory Allocation Routines

1432 **

1433 ** An instance of this object defines the interface between SQLite

1434 ** and low-level memory allocation routines.

1435 **

1436 ** This object is used in only one place in the SQLite interface.

1437 ** A pointer to an instance of this object is the argument to

1438 ** [sqlite3_config()] when the configuration option is

1439 ** [SQLITE_CONFIG_MALLOC] or [SQLITE_CONFIG_GETMALLOC].

1440 ** By creating an instance of this object

1441 ** and passing it to [sqlite3_config]([SQLITE_CONFIG_MALLOC])

1442 ** during configuration, an application can specify an alternative

1443 ** memory allocation subsystem for SQLite to use for all of its

1444 ** dynamic memory needs.

1445 **

1446 ** Note that SQLite comes with several [built-in memory allocators]

1447 ** that are perfectly adequate for the overwhelming majority of applications

1448 ** and that this object is only useful to a tiny minority of applications

1449 ** with specialized memory allocation requirements. This object is

1450 ** also used during testing of SQLite in order to specify an alternative

1451 ** memory allocator that simulates memory out-of-memory conditions in

1452 ** order to verify that SQLite recovers gracefully from such

1453 ** conditions.

1454 **

1455 ** The xMalloc, xRealloc, and xFree methods must work like the

1456 ** malloc(), realloc() and free() functions from the standard C library.

1457 ** ^SQLite guarantees that the second argument to

1458 ** xRealloc is always a value returned by a prior call to xRoundup.

1459 **

1460 ** xSize should return the allocated size of a memory allocation

1461 ** previously obtained from xMalloc or xRealloc. The allocated size

1462 ** is always at least as big as the requested size but may be larger.

1463 **

1464 ** The xRoundup method returns what would be the allocated size of

1465 ** a memory allocation given a particular requested size. Most memory

1466 ** allocators round up memory allocations at least to the next multiple

1467 ** of 8. Some allocators round up to a larger multiple or to a power of 2.

1468 ** Every memory allocation request coming in through [sqlite3_malloc()]

1469 ** or [sqlite3_realloc()] first calls xRoundup. If xRoundup returns 0,

1470 ** that causes the corresponding memory allocation to fail.

1471 **

1472 ** The xInit method initializes the memory allocator. For example,

1473 ** it might allocate any require mutexes or initialize internal data

1474 ** structures. The xShutdown method is invoked (indirectly) by

1475 ** [sqlite3_shutdown()] and should deallocate any resources acquired

1476 ** by xInit. The pAppData pointer is used as the only parameter to

1477 ** xInit and xShutdown.

1478 **

1479 ** SQLite holds the [SQLITE_MUTEX_STATIC_MASTER] mutex when it invokes

1480 ** the xInit method, so the xInit method need not be threadsafe. The

1481 ** xShutdown method is only called from [sqlite3_shutdown()] so it does

1482 ** not need to be threadsafe either. For all other methods, SQLite

1483 ** holds the [SQLITE_MUTEX_STATIC_MEM] mutex as long as the

1484 ** [SQLITE_CONFIG_MEMSTATUS] configuration option is turned on (which

1485 ** it is by default) and so the methods are automatically serialized.

1486 ** However, if [SQLITE_CONFIG_MEMSTATUS] is disabled, then the other

1487 ** methods must be threadsafe or else make their own arrangements for

1488 ** serialization.

1489 **

1490 ** SQLite will never invoke xInit() more than once without an intervening

1491 ** call to xShutdown().

1492 */

1493 typedef struct sqlite3_mem_methods sqlite3_mem_methods;

1494 struct sqlite3_mem_methods {

1495 void (xMalloc)(int); /* Memory allocation function */

1496 void (xFree)(void); /* Free a prior allocation */

1497 void (xRealloc)(void,int); / Resize an allocation */

1498 int (xSize)(void); /* Return the size of an allocation */

1499 int (xRoundup)(int); / Round up request size to allocation size */

1500 int (xInit)(void); /* Initialize the memory allocator */

1501 void (xShutdown)(void); /* Deinitialize the memory allocator */

1502 void pAppData; / Argument to xInit() and xShutdown() */

1503 };

1504

1505 /*

1506 ** CAPI3REF: Configuration Options

1507 ** KEYWORDS: {configuration option}

1508 **

1509 ** These constants are the available integer configuration options that

1510 ** can be passed as the first argument to the [sqlite3_config()] interface.

1511 **

1512 ** New configuration options may be added in future releases of SQLite.

1513 ** Existing configuration options might be discontinued. Applications

1514 ** should check the return code from [sqlite3_config()] to make sure that

1515 ** the call worked. The [sqlite3_config()] interface will return a

1516 ** non-zero [error code] if a discontinued or unsupported configuration option

1517 ** is invoked.

1518 **

1519 ** <dl>

1520 ** [[SQLITE_CONFIG_SINGLETHREAD]] <dt>SQLITE_CONFIG_SINGLETHREAD</dt>

1521 ** <dd>There are no arguments to this option. ^This option sets the

1522 ** [threading mode] to Single-thread. In other words, it disables

1523 ** all mutexing and puts SQLite into a mode where it can only be used

1524 ** by a single thread. ^If SQLite is compiled with

1525 ** the [SQLITE_THREADSAFE \| SQLITE_THREADSAFE=0] compile-time option then

1526 ** it is not possible to change the [threading mode] from its default

1527 ** value of Single-thread and so [sqlite3_config()] will return

1528 ** [SQLITE_ERROR] if called with the SQLITE_CONFIG_SINGLETHREAD

1529 ** configuration option.</dd>

1530 **

1531 ** [[SQLITE_CONFIG_MULTITHREAD]] <dt>SQLITE_CONFIG_MULTITHREAD</dt>

1532 ** <dd>There are no arguments to this option. ^This option sets the

1533 ** [threading mode] to Multi-thread. In other words, it disables

1534 ** mutexing on [database connection] and [prepared statement] objects.

1535 ** The application is responsible for serializing access to

1536 ** [database connections] and [prepared statements]. But other mutexes

1537 ** are enabled so that SQLite will be safe to use in a multi-threaded

1538 ** environment as long as no two threads attempt to use the same

1539 ** [database connection] at the same time. ^If SQLite is compiled with

1540 ** the [SQLITE_THREADSAFE \| SQLITE_THREADSAFE=0] compile-time option then

1541 ** it is not possible to set the Multi-thread [threading mode] and

1542 ** [sqlite3_config()] will return [SQLITE_ERROR] if called with the

1543 ** SQLITE_CONFIG_MULTITHREAD configuration option.</dd>

1544 **

1545 ** [[SQLITE_CONFIG_SERIALIZED]] <dt>SQLITE_CONFIG_SERIALIZED</dt>

1546 ** <dd>There are no arguments to this option. ^This option sets the

1547 ** [threading mode] to Serialized. In other words, this option enables

1548 ** all mutexes including the recursive

1549 ** mutexes on [database connection] and [prepared statement] objects.

1550 ** In this mode (which is the default when SQLite is compiled with

1551 ** [SQLITE_THREADSAFE=1]) the SQLite library will itself serialize access

1552 ** to [database connections] and [prepared statements] so that the

1553 ** application is free to use the same [database connection] or the

1554 ** same [prepared statement] in different threads at the same time.

1555 ** ^If SQLite is compiled with

1556 ** the [SQLITE_THREADSAFE \| SQLITE_THREADSAFE=0] compile-time option then

1557 ** it is not possible to set the Serialized [threading mode] and

1558 ** [sqlite3_config()] will return [SQLITE_ERROR] if called with the

1559 ** SQLITE_CONFIG_SERIALIZED configuration option.</dd>

1560 **

1561 ** [[SQLITE_CONFIG_MALLOC]] <dt>SQLITE_CONFIG_MALLOC</dt>

1562 ** <dd> ^(The SQLITE_CONFIG_MALLOC option takes a single argument which is

1563 ** a pointer to an instance of the [sqlite3_mem_methods] structure.

1564 ** The argument specifies

1565 ** alternative low-level memory allocation routines to be used in place of

1566 ** the memory allocation routines built into SQLite.)^ ^SQLite makes

1567 ** its own private copy of the content of the [sqlite3_mem_methods] structure

1568 ** before the [sqlite3_config()] call returns.</dd>

1569 **

1570 ** [[SQLITE_CONFIG_GETMALLOC]] <dt>SQLITE_CONFIG_GETMALLOC</dt>

1571 ** <dd> ^(The SQLITE_CONFIG_GETMALLOC option takes a single argument which

1572 ** is a pointer to an instance of the [sqlite3_mem_methods] structure.

1573 ** The [sqlite3_mem_methods]

1574 ** structure is filled with the currently defined memory allocation routines.)^

1575 ** This option can be used to overload the default memory allocation

1576 ** routines with a wrapper that simulations memory allocation failure or

1577 ** tracks memory usage, for example. </dd>

1578 **

1579 ** [[SQLITE_CONFIG_MEMSTATUS]] <dt>SQLITE_CONFIG_MEMSTATUS</dt>

1580 ** <dd> ^The SQLITE_CONFIG_MEMSTATUS option takes single argument of type int,

1581 ** interpreted as a boolean, which enables or disables the collection of

1582 ** memory allocation statistics. ^(When memory allocation statistics are

1583 ** disabled, the following SQLite interfaces become non-operational:

1584 ** <ul>

1585 ** <li> [sqlite3_memory_used()]

1586 ** <li> [sqlite3_memory_highwater()]

1587 ** <li> [sqlite3_soft_heap_limit64()]

1588 ** <li> [sqlite3_status64()]

1589 ** </ul>)^

1590 ** ^Memory allocation statistics are enabled by default unless SQLite is

1591 ** compiled with [SQLITE_DEFAULT_MEMSTATUS]=0 in which case memory

1592 ** allocation statistics are disabled by default.

1593 ** </dd>

1594 **

1595 ** [[SQLITE_CONFIG_SCRATCH]] <dt>SQLITE_CONFIG_SCRATCH</dt>

1596 ** <dd> ^The SQLITE_CONFIG_SCRATCH option specifies a static memory buffer

1597 ** that SQLite can use for scratch memory. ^(There are three arguments

1598 ** to SQLITE_CONFIG_SCRATCH: A pointer an 8-byte

1599 ** aligned memory buffer from which the scratch allocations will be

1600 ** drawn, the size of each scratch allocation (sz),

1601 ** and the maximum number of scratch allocations (N).)^

1602 ** The first argument must be a pointer to an 8-byte aligned buffer

1603 ** of at least sz*N bytes of memory.

1604 ** ^SQLite will not use more than one scratch buffers per thread.

1605 ** ^SQLite will never request a scratch buffer that is more than 6

1606 ** times the database page size.

1607 ** ^If SQLite needs needs additional

1608 ** scratch memory beyond what is provided by this configuration option, then

1609 ** [sqlite3_malloc()] will be used to obtain the memory needed.<p>

1610 ** ^When the application provides any amount of scratch memory using

1611 ** SQLITE_CONFIG_SCRATCH, SQLite avoids unnecessary large

1612 ** [sqlite3_malloc\|heap allocations].

1613 ** This can help [Robson proof\|prevent memory allocation failures] due to heap

1614 ** fragmentation in low-memory embedded systems.

1615 ** </dd>

1616 **

1617 ** [[SQLITE_CONFIG_PAGECACHE]] <dt>SQLITE_CONFIG_PAGECACHE</dt>

1618 ** <dd> ^The SQLITE_CONFIG_PAGECACHE option specifies a memory pool

1619 ** that SQLite can use for the database page cache with the default page

1620 ** cache implementation.

1621 ** This configuration option is a no-op if an application-define page

1622 ** cache implementation is loaded using the [SQLITE_CONFIG_PCACHE2].

1623 ** ^There are three arguments to SQLITE_CONFIG_PAGECACHE: A pointer to

1624 ** 8-byte aligned memory (pMem), the size of each page cache line (sz),

1625 ** and the number of cache lines (N).

1626 ** The sz argument should be the size of the largest database page

1627 ** (a power of two between 512 and 65536) plus some extra bytes for each

1628 ** page header. ^The number of extra bytes needed by the page header

1629 ** can be determined using [SQLITE_CONFIG_PCACHE_HDRSZ].

1630 ** ^It is harmless, apart from the wasted memory,

1631 ** for the sz parameter to be larger than necessary. The pMem

1632 ** argument must be either a NULL pointer or a pointer to an 8-byte

1633 ** aligned block of memory of at least sz*N bytes, otherwise

1634 ** subsequent behavior is undefined.

1635 ** ^When pMem is not NULL, SQLite will strive to use the memory provided

1636 ** to satisfy page cache needs, falling back to [sqlite3_malloc()] if

1637 ** a page cache line is larger than sz bytes or if all of the pMem buffer

1638 ** is exhausted.

1639 ** ^If pMem is NULL and N is non-zero, then each database connection

1640 ** does an initial bulk allocation for page cache memory

1641 ** from [sqlite3_malloc()] sufficient for N cache lines if N is positive or

1642 ** of -1024*N bytes if N is negative, . ^If additional

1643 ** page cache memory is needed beyond what is provided by the initial

1644 ** allocation, then SQLite goes to [sqlite3_malloc()] separately for each

1645 ** additional cache line. </dd>

1646 **

1647 ** [[SQLITE_CONFIG_HEAP]] <dt>SQLITE_CONFIG_HEAP</dt>

1648 ** <dd> ^The SQLITE_CONFIG_HEAP option specifies a static memory buffer

1649 ** that SQLite will use for all of its dynamic memory allocation needs

1650 ** beyond those provided for by [SQLITE_CONFIG_SCRATCH] and

1651 ** [SQLITE_CONFIG_PAGECACHE].

1652 ** ^The SQLITE_CONFIG_HEAP option is only available if SQLite is compiled

1653 ** with either [SQLITE_ENABLE_MEMSYS3] or [SQLITE_ENABLE_MEMSYS5] and returns

1654 ** [SQLITE_ERROR] if invoked otherwise.

1655 ** ^There are three arguments to SQLITE_CONFIG_HEAP:

1656 ** An 8-byte aligned pointer to the memory,

1657 ** the number of bytes in the memory buffer, and the minimum allocation size.

1658 ** ^If the first pointer (the memory pointer) is NULL, then SQLite reverts

1659 ** to using its default memory allocator (the system malloc() implementation),

1660 ** undoing any prior invocation of [SQLITE_CONFIG_MALLOC]. ^If the

1661 ** memory pointer is not NULL then the alternative memory

1662 ** allocator is engaged to handle all of SQLites memory allocation needs.

1663 ** The first pointer (the memory pointer) must be aligned to an 8-byte

1664 ** boundary or subsequent behavior of SQLite will be undefined.

1665 The minimum allocation size is capped at 212. Reasonable values

1666 for the minimum allocation size are 25 through 2**8.</dd>

1667 **

1668 ** [[SQLITE_CONFIG_MUTEX]] <dt>SQLITE_CONFIG_MUTEX</dt>

1669 ** <dd> ^(The SQLITE_CONFIG_MUTEX option takes a single argument which is a

1670 ** pointer to an instance of the [sqlite3_mutex_methods] structure.

1671 ** The argument specifies alternative low-level mutex routines to be used

1672 ** in place the mutex routines built into SQLite.)^ ^SQLite makes a copy of

1673 ** the content of the [sqlite3_mutex_methods] structure before the call to

1674 ** [sqlite3_config()] returns. ^If SQLite is compiled with

1675 ** the [SQLITE_THREADSAFE \| SQLITE_THREADSAFE=0] compile-time option then

1676 ** the entire mutexing subsystem is omitted from the build and hence calls to

1677 ** [sqlite3_config()] with the SQLITE_CONFIG_MUTEX configuration option will

1678 ** return [SQLITE_ERROR].</dd>

1679 **

1680 ** [[SQLITE_CONFIG_GETMUTEX]] <dt>SQLITE_CONFIG_GETMUTEX</dt>

1681 ** <dd> ^(The SQLITE_CONFIG_GETMUTEX option takes a single argument which

1682 ** is a pointer to an instance of the [sqlite3_mutex_methods] structure. The

1683 ** [sqlite3_mutex_methods]

1684 ** structure is filled with the currently defined mutex routines.)^

1685 ** This option can be used to overload the default mutex allocation

1686 ** routines with a wrapper used to track mutex usage for performance

1687 ** profiling or testing, for example. ^If SQLite is compiled with

1688 ** the [SQLITE_THREADSAFE \| SQLITE_THREADSAFE=0] compile-time option then

1689 ** the entire mutexing subsystem is omitted from the build and hence calls to

1690 ** [sqlite3_config()] with the SQLITE_CONFIG_GETMUTEX configuration option will

1691 ** return [SQLITE_ERROR].</dd>

1692 **

1693 ** [[SQLITE_CONFIG_LOOKASIDE]] <dt>SQLITE_CONFIG_LOOKASIDE</dt>

1694 ** <dd> ^(The SQLITE_CONFIG_LOOKASIDE option takes two arguments that determine

1695 ** the default size of lookaside memory on each [database connection].

1696 ** The first argument is the

1697 ** size of each lookaside buffer slot and the second is the number of

1698 ** slots allocated to each database connection.)^ ^(SQLITE_CONFIG_LOOKASIDE

1699 ** sets the <i>default</i> lookaside size. The [SQLITE_DBCONFIG_LOOKASIDE]

1700 ** option to [sqlite3_db_config()] can be used to change the lookaside

1701 ** configuration on individual connections.)^ </dd>

1702 **

1703 ** [[SQLITE_CONFIG_PCACHE2]] <dt>SQLITE_CONFIG_PCACHE2</dt>

1704 ** <dd> ^(The SQLITE_CONFIG_PCACHE2 option takes a single argument which is

1705 ** a pointer to an [sqlite3_pcache_methods2] object. This object specifies

1706 ** the interface to a custom page cache implementation.)^

1707 ** ^SQLite makes a copy of the [sqlite3_pcache_methods2] object.</dd>

1708 **

1709 ** [[SQLITE_CONFIG_GETPCACHE2]] <dt>SQLITE_CONFIG_GETPCACHE2</dt>

1710 ** <dd> ^(The SQLITE_CONFIG_GETPCACHE2 option takes a single argument which

1711 ** is a pointer to an [sqlite3_pcache_methods2] object. SQLite copies of

1712 ** the current page cache implementation into that object.)^ </dd>

1713 **

1714 ** [[SQLITE_CONFIG_LOG]] <dt>SQLITE_CONFIG_LOG</dt>

1715 ** <dd> The SQLITE_CONFIG_LOG option is used to configure the SQLite

1716 ** global [error log].

1717 ** (^The SQLITE_CONFIG_LOG option takes two arguments: a pointer to a

1718 ** function with a call signature of void()(void,int,const char*),

1719 ** and a pointer to void. ^If the function pointer is not NULL, it is

1720 ** invoked by [sqlite3_log()] to process each logging event. ^If the

1721 ** function pointer is NULL, the [sqlite3_log()] interface becomes a no-op.

1722 ** ^The void pointer that is the second argument to SQLITE_CONFIG_LOG is

1723 ** passed through as the first parameter to the application-defined logger

1724 ** function whenever that function is invoked. ^The second parameter to

1725 ** the logger function is a copy of the first parameter to the corresponding

1726 ** [sqlite3_log()] call and is intended to be a [result code] or an

1727 ** [extended result code]. ^The third parameter passed to the logger is

1728 ** log message after formatting via [sqlite3_snprintf()].

1729 ** The SQLite logging interface is not reentrant; the logger function

1730 ** supplied by the application must not invoke any SQLite interface.

1731 ** In a multi-threaded application, the application-defined logger

1732 ** function must be threadsafe. </dd>

1733 **

1734 ** [[SQLITE_CONFIG_URI]] <dt>SQLITE_CONFIG_URI

1735 ** <dd>^(The SQLITE_CONFIG_URI option takes a single argument of type int.

1736 ** If non-zero, then URI handling is globally enabled. If the parameter is zero,

1737 ** then URI handling is globally disabled.)^ ^If URI handling is globally

1738 ** enabled, all filenames passed to [sqlite3_open()], [sqlite3_open_v2()],

1739 ** [sqlite3_open16()] or

1740 ** specified as part of [ATTACH] commands are interpreted as URIs, regardless

1741 ** of whether or not the [SQLITE_OPEN_URI] flag is set when the database

1742 ** connection is opened. ^If it is globally disabled, filenames are

1743 ** only interpreted as URIs if the SQLITE_OPEN_URI flag is set when the

1744 ** database connection is opened. ^(By default, URI handling is globally

1745 ** disabled. The default value may be changed by compiling with the

1746 ** [SQLITE_USE_URI] symbol defined.)^

1747 **

1748 ** [[SQLITE_CONFIG_COVERING_INDEX_SCAN]] <dt>SQLITE_CONFIG_COVERING_INDEX_SCAN

1749 ** <dd>^The SQLITE_CONFIG_COVERING_INDEX_SCAN option takes a single integer

1750 ** argument which is interpreted as a boolean in order to enable or disable

1751 ** the use of covering indices for full table scans in the query optimizer.

1752 ** ^The default setting is determined

1753 ** by the [SQLITE_ALLOW_COVERING_INDEX_SCAN] compile-time option, or is "on"

1754 ** if that compile-time option is omitted.

1755 ** The ability to disable the use of covering indices for full table scans

1756 ** is because some incorrectly coded legacy applications might malfunction

1757 ** when the optimization is enabled. Providing the ability to

1758 ** disable the optimization allows the older, buggy application code to work

1759 ** without change even with newer versions of SQLite.

1760 **

1761 ** [[SQLITE_CONFIG_PCACHE]] [[SQLITE_CONFIG_GETPCACHE]]

1762 ** <dt>SQLITE_CONFIG_PCACHE and SQLITE_CONFIG_GETPCACHE

1763 ** <dd> These options are obsolete and should not be used by new code.

1764 ** They are retained for backwards compatibility but are now no-ops.

1765 ** </dd>

1766 **

1767 ** [[SQLITE_CONFIG_SQLLOG]]

1768 ** <dt>SQLITE_CONFIG_SQLLOG

1769 ** <dd>This option is only available if sqlite is compiled with the

1770 ** [SQLITE_ENABLE_SQLLOG] pre-processor macro defined. The first argument should

1771 ** be a pointer to a function of type void()(void,sqlite3,const char, int).

1772 ** The second should be of type (void*). The callback is invoked by the library

1773 ** in three separate circumstances, identified by the value passed as the

1774 ** fourth parameter. If the fourth parameter is 0, then the database connection

1775 ** passed as the second argument has just been opened. The third argument

1776 ** points to a buffer containing the name of the main database file. If the

1777 ** fourth parameter is 1, then the SQL statement that the third parameter

1778 ** points to has just been executed. Or, if the fourth parameter is 2, then

1779 ** the connection being passed as the second parameter is being closed. The

1780 ** third parameter is passed NULL In this case. An example of using this

1781 ** configuration option can be seen in the "test_sqllog.c" source file in

1782 ** the canonical SQLite source tree.</dd>

1783 **

1784 ** [[SQLITE_CONFIG_MMAP_SIZE]]

1785 ** <dt>SQLITE_CONFIG_MMAP_SIZE

1786 ** <dd>^SQLITE_CONFIG_MMAP_SIZE takes two 64-bit integer (sqlite3_int64) values

1787 ** that are the default mmap size limit (the default setting for

1788 ** [PRAGMA mmap_size]) and the maximum allowed mmap size limit.

1789 ** ^The default setting can be overridden by each database connection using

1790 ** either the [PRAGMA mmap_size] command, or by using the

1791 ** [SQLITE_FCNTL_MMAP_SIZE] file control. ^(The maximum allowed mmap size

1792 ** will be silently truncated if necessary so that it does not exceed the

1793 ** compile-time maximum mmap size set by the

1794 ** [SQLITE_MAX_MMAP_SIZE] compile-time option.)^

1795 ** ^If either argument to this option is negative, then that argument is

1796 ** changed to its compile-time default.

1797 **

1798 ** [[SQLITE_CONFIG_WIN32_HEAPSIZE]]

1799 ** <dt>SQLITE_CONFIG_WIN32_HEAPSIZE

1800 ** <dd>^The SQLITE_CONFIG_WIN32_HEAPSIZE option is only available if SQLite is

1801 ** compiled for Windows with the [SQLITE_WIN32_MALLOC] pre-processor macro

1802 ** defined. ^SQLITE_CONFIG_WIN32_HEAPSIZE takes a 32-bit unsigned integer value

1803 ** that specifies the maximum size of the created heap.

1804 **

1805 ** [[SQLITE_CONFIG_PCACHE_HDRSZ]]

1806 ** <dt>SQLITE_CONFIG_PCACHE_HDRSZ

1807 ** <dd>^The SQLITE_CONFIG_PCACHE_HDRSZ option takes a single parameter which

1808 ** is a pointer to an integer and writes into that integer the number of extra

1809 ** bytes per page required for each page in [SQLITE_CONFIG_PAGECACHE].

1810 ** The amount of extra space required can change depending on the compiler,

1811 ** target platform, and SQLite version.

1812 **

1813 ** [[SQLITE_CONFIG_PMASZ]]

1814 ** <dt>SQLITE_CONFIG_PMASZ

1815 ** <dd>^The SQLITE_CONFIG_PMASZ option takes a single parameter which

1816 ** is an unsigned integer and sets the "Minimum PMA Size" for the multithreaded

1817 ** sorter to that integer. The default minimum PMA Size is set by the

1818 ** [SQLITE_SORTER_PMASZ] compile-time option. New threads are launched

1819 ** to help with sort operations when multithreaded sorting

1820 ** is enabled (using the [PRAGMA threads] command) and the amount of content

1821 ** to be sorted exceeds the page size times the minimum of the

1822 ** [PRAGMA cache_size] setting and this value.

1823 ** </dl>

1824 */

1825 #define SQLITE_CONFIG_SINGLETHREAD 1 /* nil */

1826 #define SQLITE_CONFIG_MULTITHREAD 2 /* nil */

1827 #define SQLITE_CONFIG_SERIALIZED 3 /* nil */

1828 #define SQLITE_CONFIG_MALLOC 4 /* sqlite3_mem_methods* */

1829 #define SQLITE_CONFIG_GETMALLOC 5 /* sqlite3_mem_methods* */

1830 #define SQLITE_CONFIG_SCRATCH 6 /* void, int sz, int N /

1831 #define SQLITE_CONFIG_PAGECACHE 7 /* void, int sz, int N /

1832 #define SQLITE_CONFIG_HEAP 8 /* void, int nByte, int min /

1833 #define SQLITE_CONFIG_MEMSTATUS 9 /* boolean */

1834 #define SQLITE_CONFIG_MUTEX 10 /* sqlite3_mutex_methods* */

1835 #define SQLITE_CONFIG_GETMUTEX 11 /* sqlite3_mutex_methods* */

1836 /* previously SQLITE_CONFIG_CHUNKALLOC 12 which is now unused. */

1837 #define SQLITE_CONFIG_LOOKASIDE 13 /* int int */

1838 #define SQLITE_CONFIG_PCACHE 14 /* no-op */

1839 #define SQLITE_CONFIG_GETPCACHE 15 /* no-op */

1840 #define SQLITE_CONFIG_LOG 16 /* xFunc, void* */

1841 #define SQLITE_CONFIG_URI 17 /* int */

1842 #define SQLITE_CONFIG_PCACHE2 18 /* sqlite3_pcache_methods2* */

1843 #define SQLITE_CONFIG_GETPCACHE2 19 /* sqlite3_pcache_methods2* */

1844 #define SQLITE_CONFIG_COVERING_INDEX_SCAN 20 /* int */

1845 #define SQLITE_CONFIG_SQLLOG 21 /* xSqllog, void* */

1846 #define SQLITE_CONFIG_MMAP_SIZE 22 /* sqlite3_int64, sqlite3_int64 */

1847 #define SQLITE_CONFIG_WIN32_HEAPSIZE 23 /* int nByte */

1848 #define SQLITE_CONFIG_PCACHE_HDRSZ 24 /* int psz /

1849 #define SQLITE_CONFIG_PMASZ 25 /* unsigned int szPma */

1850

1851 /*

1852 ** CAPI3REF: Database Connection Configuration Options

1853 **

1854 ** These constants are the available integer configuration options that

1855 ** can be passed as the second argument to the [sqlite3_db_config()] interface.

1856 **

1857 ** New configuration options may be added in future releases of SQLite.

1858 ** Existing configuration options might be discontinued. Applications

1859 ** should check the return code from [sqlite3_db_config()] to make sure that

1860 ** the call worked. ^The [sqlite3_db_config()] interface will return a

1861 ** non-zero [error code] if a discontinued or unsupported configuration option

1862 ** is invoked.

1863 **

1864 ** <dl>

1865 ** <dt>SQLITE_DBCONFIG_LOOKASIDE</dt>

1866 ** <dd> ^This option takes three additional arguments that determine the

1867 ** [lookaside memory allocator] configuration for the [database connection].

1868 ** ^The first argument (the third parameter to [sqlite3_db_config()] is a

1869 ** pointer to a memory buffer to use for lookaside memory.

1870 ** ^The first argument after the SQLITE_DBCONFIG_LOOKASIDE verb

1871 ** may be NULL in which case SQLite will allocate the

1872 ** lookaside buffer itself using [sqlite3_malloc()]. ^The second argument is the

1873 ** size of each lookaside buffer slot. ^The third argument is the number of

1874 ** slots. The size of the buffer in the first argument must be greater than

1875 ** or equal to the product of the second and third arguments. The buffer

1876 ** must be aligned to an 8-byte boundary. ^If the second argument to

1877 ** SQLITE_DBCONFIG_LOOKASIDE is not a multiple of 8, it is internally

1878 ** rounded down to the next smaller multiple of 8. ^(The lookaside memory

1879 ** configuration for a database connection can only be changed when that

1880 ** connection is not currently using lookaside memory, or in other words

1881 ** when the "current value" returned by

1882 ** [sqlite3_db_status](D,[SQLITE_CONFIG_LOOKASIDE],...) is zero.

1883 ** Any attempt to change the lookaside memory configuration when lookaside

1884 ** memory is in use leaves the configuration unchanged and returns

1885 ** [SQLITE_BUSY].)^</dd>

1886 **

1887 ** <dt>SQLITE_DBCONFIG_ENABLE_FKEY</dt>

1888 ** <dd> ^This option is used to enable or disable the enforcement of

1889 ** [foreign key constraints]. There should be two additional arguments.

1890 ** The first argument is an integer which is 0 to disable FK enforcement,

1891 ** positive to enable FK enforcement or negative to leave FK enforcement

1892 ** unchanged. The second parameter is a pointer to an integer into which

1893 ** is written 0 or 1 to indicate whether FK enforcement is off or on

1894 ** following this call. The second parameter may be a NULL pointer, in

1895 ** which case the FK enforcement setting is not reported back. </dd>

1896 **

1897 ** <dt>SQLITE_DBCONFIG_ENABLE_TRIGGER</dt>

1898 ** <dd> ^This option is used to enable or disable [CREATE TRIGGER \| triggers].

1899 ** There should be two additional arguments.

1900 ** The first argument is an integer which is 0 to disable triggers,

1901 ** positive to enable triggers or negative to leave the setting unchanged.

1902 ** The second parameter is a pointer to an integer into which

1903 ** is written 0 or 1 to indicate whether triggers are disabled or enabled

1904 ** following this call. The second parameter may be a NULL pointer, in

1905 ** which case the trigger setting is not reported back. </dd>

1906 **

1907 ** </dl>

1908 */

1909 #define SQLITE_DBCONFIG_LOOKASIDE 1001 /* void* int int */

1910 #define SQLITE_DBCONFIG_ENABLE_FKEY 1002 /* int int* */

1911 #define SQLITE_DBCONFIG_ENABLE_TRIGGER 1003 /* int int* */

1912

1913

1914 /*

1915 ** CAPI3REF: Enable Or Disable Extended Result Codes

1916 ** METHOD: sqlite3

1917 **

1918 ** ^The sqlite3_extended_result_codes() routine enables or disables the

1919 ** [extended result codes] feature of SQLite. ^The extended result

1920 ** codes are disabled by default for historical compatibility.

1921 */

1922 int sqlite3_extended_result_codes(sqlite3*, int onoff);

1923

1924 /*

1925 ** CAPI3REF: Last Insert Rowid

1926 ** METHOD: sqlite3

1927 **

1928 ** ^Each entry in most SQLite tables (except for [WITHOUT ROWID] tables)

1929 ** has a unique 64-bit signed

1930 ** integer key called the [ROWID \| "rowid"]. ^The rowid is always available

1931 ** as an undeclared column named ROWID, OID, or _ROWID_ as long as those

1932 ** names are not also used by explicitly declared columns. ^If

1933 ** the table has a column of type [INTEGER PRIMARY KEY] then that column

1934 ** is another alias for the rowid.

1935 **

1936 ** ^The sqlite3_last_insert_rowid(D) interface returns the [rowid] of the

1937 ** most recent successful [INSERT] into a rowid table or [virtual table]

1938 ** on database connection D.

1939 ** ^Inserts into [WITHOUT ROWID] tables are not recorded.

1940 ** ^If no successful [INSERT]s into rowid tables

1941 ** have ever occurred on the database connection D,

1942 ** then sqlite3_last_insert_rowid(D) returns zero.

1943 **

1944 ** ^(If an [INSERT] occurs within a trigger or within a [virtual table]

1945 ** method, then this routine will return the [rowid] of the inserted

1946 ** row as long as the trigger or virtual table method is running.

1947 ** But once the trigger or virtual table method ends, the value returned

1948 ** by this routine reverts to what it was before the trigger or virtual

1949 ** table method began.)^

1950 **

1951 ** ^An [INSERT] that fails due to a constraint violation is not a

1952 ** successful [INSERT] and does not change the value returned by this

1953 ** routine. ^Thus INSERT OR FAIL, INSERT OR IGNORE, INSERT OR ROLLBACK,

1954 ** and INSERT OR ABORT make no changes to the return value of this

1955 ** routine when their insertion fails. ^(When INSERT OR REPLACE

1956 ** encounters a constraint violation, it does not fail. The

1957 ** INSERT continues to completion after deleting rows that caused

1958 ** the constraint problem so INSERT OR REPLACE will always change

1959 ** the return value of this interface.)^

1960 **

1961 ** ^For the purposes of this routine, an [INSERT] is considered to

1962 ** be successful even if it is subsequently rolled back.

1963 **

1964 ** This function is accessible to SQL statements via the

1965 ** [last_insert_rowid() SQL function].

1966 **

1967 ** If a separate thread performs a new [INSERT] on the same

1968 ** database connection while the [sqlite3_last_insert_rowid()]

1969 ** function is running and thus changes the last insert [rowid],

1970 ** then the value returned by [sqlite3_last_insert_rowid()] is

1971 ** unpredictable and might not equal either the old or the new

1972 ** last insert [rowid].

1973 */

1974 sqlite3_int64 sqlite3_last_insert_rowid(sqlite3*);

1975

1976 /*

1977 ** CAPI3REF: Count The Number Of Rows Modified

1978 ** METHOD: sqlite3

1979 **

1980 ** ^This function returns the number of rows modified, inserted or

1981 ** deleted by the most recently completed INSERT, UPDATE or DELETE

1982 ** statement on the database connection specified by the only parameter.

1983 ** ^Executing any other type of SQL statement does not modify the value

1984 ** returned by this function.

1985 **

1986 ** ^Only changes made directly by the INSERT, UPDATE or DELETE statement are

1987 ** considered - auxiliary changes caused by [CREATE TRIGGER \| triggers],

1988 ** [foreign key actions] or [REPLACE] constraint resolution are not counted.

1989 **

1990 ** Changes to a view that are intercepted by

1991 ** [INSTEAD OF trigger \| INSTEAD OF triggers] are not counted. ^The value

1992 ** returned by sqlite3_changes() immediately after an INSERT, UPDATE or

1993 ** DELETE statement run on a view is always zero. Only changes made to real

1994 ** tables are counted.

1995 **

1996 ** Things are more complicated if the sqlite3_changes() function is

1997 ** executed while a trigger program is running. This may happen if the

1998 ** program uses the [changes() SQL function], or if some other callback

1999 ** function invokes sqlite3_changes() directly. Essentially:

2000 **

2001 ** <ul>

2002 ** <li> ^(Before entering a trigger program the value returned by

2003 ** sqlite3_changes() function is saved. After the trigger program

2004 ** has finished, the original value is restored.)^

2005 **

2006 ** <li> ^(Within a trigger program each INSERT, UPDATE and DELETE

2007 ** statement sets the value returned by sqlite3_changes()

2008 ** upon completion as normal. Of course, this value will not include

2009 ** any changes performed by sub-triggers, as the sqlite3_changes()

2010 ** value will be saved and restored after each sub-trigger has run.)^

2011 ** </ul>

2012 **

2013 ** ^This means that if the changes() SQL function (or similar) is used

2014 ** by the first INSERT, UPDATE or DELETE statement within a trigger, it

2015 ** returns the value as set when the calling statement began executing.

2016 ** ^If it is used by the second or subsequent such statement within a trigger

2017 ** program, the value returned reflects the number of rows modified by the

2018 ** previous INSERT, UPDATE or DELETE statement within the same trigger.

2019 **

2020 ** See also the [sqlite3_total_changes()] interface, the

2021 ** [count_changes pragma], and the [changes() SQL function].

2022 **

2023 ** If a separate thread makes changes on the same database connection

2024 ** while [sqlite3_changes()] is running then the value returned

2025 ** is unpredictable and not meaningful.

2026 */

2027 int sqlite3_changes(sqlite3*);

2028

2029 /*

2030 ** CAPI3REF: Total Number Of Rows Modified

2031 ** METHOD: sqlite3

2032 **

2033 ** ^This function returns the total number of rows inserted, modified or

2034 ** deleted by all [INSERT], [UPDATE] or [DELETE] statements completed

2035 ** since the database connection was opened, including those executed as

2036 ** part of trigger programs. ^Executing any other type of SQL statement

2037 ** does not affect the value returned by sqlite3_total_changes().

2038 **

2039 ** ^Changes made as part of [foreign key actions] are included in the

2040 ** count, but those made as part of REPLACE constraint resolution are

2041 ** not. ^Changes to a view that are intercepted by INSTEAD OF triggers

2042 ** are not counted.

2043 **

2044 ** See also the [sqlite3_changes()] interface, the

2045 ** [count_changes pragma], and the [total_changes() SQL function].

2046 **

2047 ** If a separate thread makes changes on the same database connection

2048 ** while [sqlite3_total_changes()] is running then the value

2049 ** returned is unpredictable and not meaningful.

2050 */

2051 int sqlite3_total_changes(sqlite3*);

2052

2053 /*

2054 ** CAPI3REF: Interrupt A Long-Running Query

2055 ** METHOD: sqlite3

2056 **

2057 ** ^This function causes any pending database operation to abort and

2058 ** return at its earliest opportunity. This routine is typically

2059 ** called in response to a user action such as pressing "Cancel"

2060 ** or Ctrl-C where the user wants a long query operation to halt

2061 ** immediately.

2062 **

2063 ** ^It is safe to call this routine from a thread different from the

2064 ** thread that is currently running the database operation. But it

2065 ** is not safe to call this routine with a [database connection] that

2066 ** is closed or might close before sqlite3_interrupt() returns.

2067 **

2068 ** ^If an SQL operation is very nearly finished at the time when

2069 ** sqlite3_interrupt() is called, then it might not have an opportunity

2070 ** to be interrupted and might continue to completion.

2071 **

2072 ** ^An SQL operation that is interrupted will return [SQLITE_INTERRUPT].

2073 ** ^If the interrupted SQL operation is an INSERT, UPDATE, or DELETE

2074 ** that is inside an explicit transaction, then the entire transaction

2075 ** will be rolled back automatically.

2076 **

2077 ** ^The sqlite3_interrupt(D) call is in effect until all currently running

2078 ** SQL statements on [database connection] D complete. ^Any new SQL statements

2079 ** that are started after the sqlite3_interrupt() call and before the

2080 ** running statements reaches zero are interrupted as if they had been

2081 ** running prior to the sqlite3_interrupt() call. ^New SQL statements

2082 ** that are started after the running statement count reaches zero are

2083 ** not effected by the sqlite3_interrupt().

2084 ** ^A call to sqlite3_interrupt(D) that occurs when there are no running

2085 ** SQL statements is a no-op and has no effect on SQL statements

2086 ** that are started after the sqlite3_interrupt() call returns.

2087 **

2088 ** If the database connection closes while [sqlite3_interrupt()]

2089 ** is running then bad things will likely happen.

2090 */

2091 void sqlite3_interrupt(sqlite3*);

2092

2093 /*

2094 ** CAPI3REF: Determine If An SQL Statement Is Complete

2095 **

2096 ** These routines are useful during command-line input to determine if the

2097 ** currently entered text seems to form a complete SQL statement or

2098 ** if additional input is needed before sending the text into

2099 ** SQLite for parsing. ^These routines return 1 if the input string

2100 ** appears to be a complete SQL statement. ^A statement is judged to be

2101 ** complete if it ends with a semicolon token and is not a prefix of a

2102 ** well-formed CREATE TRIGGER statement. ^Semicolons that are embedded within

2103 ** string literals or quoted identifier names or comments are not

2104 ** independent tokens (they are part of the token in which they are

2105 ** embedded) and thus do not count as a statement terminator. ^Whitespace

2106 ** and comments that follow the final semicolon are ignored.

2107 **

2108 ** ^These routines return 0 if the statement is incomplete. ^If a

2109 ** memory allocation fails, then SQLITE_NOMEM is returned.

2110 **

2111 ** ^These routines do not parse the SQL statements thus

2112 ** will not detect syntactically incorrect SQL.

2113 **

2114 ** ^(If SQLite has not been initialized using [sqlite3_initialize()] prior

2115 ** to invoking sqlite3_complete16() then sqlite3_initialize() is invoked

2116 ** automatically by sqlite3_complete16(). If that initialization fails,

2117 ** then the return value from sqlite3_complete16() will be non-zero

2118 ** regardless of whether or not the input SQL is complete.)^

2119 **

2120 ** The input to [sqlite3_complete()] must be a zero-terminated

2121 ** UTF-8 string.

2122 **

2123 ** The input to [sqlite3_complete16()] must be a zero-terminated

2124 ** UTF-16 string in native byte order.

2125 */

2126 int sqlite3_complete(const char *sql);

2127 int sqlite3_complete16(const void *sql);

2128

2129 /*

2130 ** CAPI3REF: Register A Callback To Handle SQLITE_BUSY Errors

2131 ** KEYWORDS: {busy-handler callback} {busy handler}

2132 ** METHOD: sqlite3

2133 **

2134 ** ^The sqlite3_busy_handler(D,X,P) routine sets a callback function X

2135 ** that might be invoked with argument P whenever

2136 ** an attempt is made to access a database table associated with

2137 ** [database connection] D when another thread

2138 ** or process has the table locked.

2139 ** The sqlite3_busy_handler() interface is used to implement

2140 ** [sqlite3_busy_timeout()] and [PRAGMA busy_timeout].

2141 **

2142 ** ^If the busy callback is NULL, then [SQLITE_BUSY]

2143 ** is returned immediately upon encountering the lock. ^If the busy callback

2144 ** is not NULL, then the callback might be invoked with two arguments.

2145 **

2146 ** ^The first argument to the busy handler is a copy of the void* pointer which

2147 ** is the third argument to sqlite3_busy_handler(). ^The second argument to

2148 ** the busy handler callback is the number of times that the busy handler has

2149 ** been invoked previously for the same locking event. ^If the

2150 ** busy callback returns 0, then no additional attempts are made to

2151 ** access the database and [SQLITE_BUSY] is returned

2152 ** to the application.

2153 ** ^If the callback returns non-zero, then another attempt

2154 ** is made to access the database and the cycle repeats.

2155 **

2156 ** The presence of a busy handler does not guarantee that it will be invoked

2157 ** when there is lock contention. ^If SQLite determines that invoking the busy

2158 ** handler could result in a deadlock, it will go ahead and return [SQLITE_BUSY]

2159 ** to the application instead of invoking the

2160 ** busy handler.

2161 ** Consider a scenario where one process is holding a read lock that

2162 ** it is trying to promote to a reserved lock and

2163 ** a second process is holding a reserved lock that it is trying

2164 ** to promote to an exclusive lock. The first process cannot proceed

2165 ** because it is blocked by the second and the second process cannot

2166 ** proceed because it is blocked by the first. If both processes

2167 ** invoke the busy handlers, neither will make any progress. Therefore,

2168 ** SQLite returns [SQLITE_BUSY] for the first process, hoping that this

2169 ** will induce the first process to release its read lock and allow

2170 ** the second process to proceed.

2171 **

2172 ** ^The default busy callback is NULL.

2173 **

2174 ** ^(There can only be a single busy handler defined for each

2175 ** [database connection]. Setting a new busy handler clears any

2176 ** previously set handler.)^ ^Note that calling [sqlite3_busy_timeout()]

2177 ** or evaluating [PRAGMA busy_timeout=N] will change the

2178 ** busy handler and thus clear any previously set busy handler.

2179 **

2180 ** The busy callback should not take any actions which modify the

2181 ** database connection that invoked the busy handler. In other words,

2182 ** the busy handler is not reentrant. Any such actions

2183 ** result in undefined behavior.

2184 **

2185 ** A busy handler must not close the database connection

2186 ** or [prepared statement] that invoked the busy handler.

2187 */

2188 int sqlite3_busy_handler(sqlite3, int()(void,int), void);

2189

2190 /*

2191 ** CAPI3REF: Set A Busy Timeout

2192 ** METHOD: sqlite3

2193 **

2194 ** ^This routine sets a [sqlite3_busy_handler \| busy handler] that sleeps

2195 ** for a specified amount of time when a table is locked. ^The handler

2196 ** will sleep multiple times until at least "ms" milliseconds of sleeping

2197 ** have accumulated. ^After at least "ms" milliseconds of sleeping,

2198 ** the handler returns 0 which causes [sqlite3_step()] to return

2199 ** [SQLITE_BUSY].

2200 **

2201 ** ^Calling this routine with an argument less than or equal to zero

2202 ** turns off all busy handlers.

2203 **

2204 ** ^(There can only be a single busy handler for a particular

2205 ** [database connection] at any given moment. If another busy handler

2206 ** was defined (using [sqlite3_busy_handler()]) prior to calling

2207 ** this routine, that other busy handler is cleared.)^

2208 **

2209 ** See also: [PRAGMA busy_timeout]

2210 */

2211 int sqlite3_busy_timeout(sqlite3*, int ms);

2212

2213 /*

2214 ** CAPI3REF: Convenience Routines For Running Queries

2215 ** METHOD: sqlite3

2216 **

2217 ** This is a legacy interface that is preserved for backwards compatibility.

2218 ** Use of this interface is not recommended.

2219 **

2220 ** Definition: A <b>result table</b> is memory data structure created by the

2221 ** [sqlite3_get_table()] interface. A result table records the

2222 ** complete query results from one or more queries.

2223 **

2224 ** The table conceptually has a number of rows and columns. But

2225 ** these numbers are not part of the result table itself. These

2226 ** numbers are obtained separately. Let N be the number of rows

2227 ** and M be the number of columns.

2228 **

2229 ** A result table is an array of pointers to zero-terminated UTF-8 strings.

2230 ** There are (N+1)*M elements in the array. The first M pointers point

2231 ** to zero-terminated strings that contain the names of the columns.

2232 ** The remaining entries all point to query results. NULL values result

2233 ** in NULL pointers. All other values are in their UTF-8 zero-terminated

2234 ** string representation as returned by [sqlite3_column_text()].

2235 **

2236 ** A result table might consist of one or more memory allocations.

2237 ** It is not safe to pass a result table directly to [sqlite3_free()].

2238 ** A result table should be deallocated using [sqlite3_free_table()].

2239 **

2240 ** ^(As an example of the result table format, suppose a query result

2241 ** is as follows:

2242 **

2243 ** <blockquote><pre>

2244 ** Name \| Age

2245 ** -----------------------

2246 ** Alice \| 43

2247 ** Bob \| 28

2248 ** Cindy \| 21

2249 ** </pre></blockquote>

2250 **

2251 ** There are two column (M==2) and three rows (N==3). Thus the

2252 ** result table has 8 entries. Suppose the result table is stored

2253 ** in an array names azResult. Then azResult holds this content:

2254 **

2255 ** <blockquote><pre>

2256 ** azResult[0] = "Name";

2257 ** azResult[1] = "Age";

2258 ** azResult[2] = "Alice";

2259 ** azResult[3] = "43";

2260 ** azResult[4] = "Bob";

2261 ** azResult[5] = "28";

2262 ** azResult[6] = "Cindy";

2263 ** azResult[7] = "21";

2264 ** </pre></blockquote>)^

2265 **

2266 ** ^The sqlite3_get_table() function evaluates one or more

2267 ** semicolon-separated SQL statements in the zero-terminated UTF-8

2268 ** string of its 2nd parameter and returns a result table to the

2269 ** pointer given in its 3rd parameter.

2270 **

2271 ** After the application has finished with the result from sqlite3_get_table(),

2272 ** it must pass the result table pointer to sqlite3_free_table() in order to

2273 ** release the memory that was malloced. Because of the way the

2274 ** [sqlite3_malloc()] happens within sqlite3_get_table(), the calling

2275 ** function must not try to call [sqlite3_free()] directly. Only

2276 ** [sqlite3_free_table()] is able to release the memory properly and safely.

2277 **

2278 ** The sqlite3_get_table() interface is implemented as a wrapper around

2279 ** [sqlite3_exec()]. The sqlite3_get_table() routine does not have access

2280 ** to any internal data structures of SQLite. It uses only the public

2281 ** interface defined here. As a consequence, errors that occur in the

2282 ** wrapper layer outside of the internal [sqlite3_exec()] call are not

2283 ** reflected in subsequent calls to [sqlite3_errcode()] or

2284 ** [sqlite3_errmsg()].

2285 */

2286 int sqlite3_get_table(

2287 sqlite3 db, / An open database */

2288 const char zSql, / SQL to be evaluated */

2289 char **pazResult, / Results of the query */

2290 int pnRow, / Number of result rows written here */

2291 int pnColumn, / Number of result columns written here */

2292 char *pzErrmsg / Error msg written here */

2293 );

2294 void sqlite3_free_table(char **result);

2295

2296 /*

2297 ** CAPI3REF: Formatted String Printing Functions

2298 **

2299 ** These routines are work-alikes of the "printf()" family of functions

2300 ** from the standard C library.

2301 ** These routines understand most of the common K&R formatting options,

2302 ** plus some additional non-standard formats, detailed below.

2303 ** Note that some of the more obscure formatting options from recent

2304 ** C-library standards are omitted from this implementation.

2305 **

2306 ** ^The sqlite3_mprintf() and sqlite3_vmprintf() routines write their

2307 ** results into memory obtained from [sqlite3_malloc()].

2308 ** The strings returned by these two routines should be

2309 ** released by [sqlite3_free()]. ^Both routines return a

2310 ** NULL pointer if [sqlite3_malloc()] is unable to allocate enough

2311 ** memory to hold the resulting string.

2312 **

2313 ** ^(The sqlite3_snprintf() routine is similar to "snprintf()" from

2314 ** the standard C library. The result is written into the

2315 ** buffer supplied as the second parameter whose size is given by

2316 ** the first parameter. Note that the order of the

2317 ** first two parameters is reversed from snprintf().)^ This is an

2318 ** historical accident that cannot be fixed without breaking

2319 ** backwards compatibility. ^(Note also that sqlite3_snprintf()

2320 ** returns a pointer to its buffer instead of the number of

2321 ** characters actually written into the buffer.)^ We admit that

2322 ** the number of characters written would be a more useful return

2323 ** value but we cannot change the implementation of sqlite3_snprintf()

2324 ** now without breaking compatibility.

2325 **

2326 ** ^As long as the buffer size is greater than zero, sqlite3_snprintf()

2327 ** guarantees that the buffer is always zero-terminated. ^The first

2328 ** parameter "n" is the total size of the buffer, including space for

2329 ** the zero terminator. So the longest string that can be completely

2330 ** written will be n-1 characters.

2331 **

2332 ** ^The sqlite3_vsnprintf() routine is a varargs version of sqlite3_snprintf().

2333 **

2334 ** These routines all implement some additional formatting

2335 ** options that are useful for constructing SQL statements.

2336 ** All of the usual printf() formatting options apply. In addition, there

2337 ** is are "%q", "%Q", "%w" and "%z" options.

2338 **

2339 ** ^(The %q option works like %s in that it substitutes a nul-terminated

2340 ** string from the argument list. But %q also doubles every '\'' character.

2341 ** %q is designed for use inside a string literal.)^ By doubling each '\''

2342 ** character it escapes that character and allows it to be inserted into

2343 ** the string.

2344 **

2345 ** For example, assume the string variable zText contains text as follows:

2346 **

2347 ** <blockquote><pre>

2348 ** char *zText = "It's a happy day!";

2349 ** </pre></blockquote>

2350 **

2351 ** One can use this text in an SQL statement as follows:

2352 **

2353 ** <blockquote><pre>

2354 ** char *zSQL = sqlite3_mprintf("INSERT INTO table VALUES('%q')", zText);

2355 ** sqlite3_exec(db, zSQL, 0, 0, 0);

2356 ** sqlite3_free(zSQL);

2357 ** </pre></blockquote>

2358 **

2359 ** Because the %q format string is used, the '\'' character in zText

2360 ** is escaped and the SQL generated is as follows:

2361 **

2362 ** <blockquote><pre>

2363 ** INSERT INTO table1 VALUES('It''s a happy day!')

2364 ** </pre></blockquote>

2365 **

2366 ** This is correct. Had we used %s instead of %q, the generated SQL

2367 ** would have looked like this:

2368 **

2369 ** <blockquote><pre>

2370 ** INSERT INTO table1 VALUES('It's a happy day!');

2371 ** </pre></blockquote>

2372 **

2373 ** This second example is an SQL syntax error. As a general rule you should

2374 ** always use %q instead of %s when inserting text into a string literal.

2375 **

2376 ** ^(The %Q option works like %q except it also adds single quotes around

2377 ** the outside of the total string. Additionally, if the parameter in the

2378 ** argument list is a NULL pointer, %Q substitutes the text "NULL" (without

2379 ** single quotes).)^ So, for example, one could say:

2380 **

2381 ** <blockquote><pre>

2382 ** char *zSQL = sqlite3_mprintf("INSERT INTO table VALUES(%Q)", zText);

2383 ** sqlite3_exec(db, zSQL, 0, 0, 0);

2384 ** sqlite3_free(zSQL);

2385 ** </pre></blockquote>

2386 **

2387 ** The code above will render a correct SQL statement in the zSQL

2388 ** variable even if the zText variable is a NULL pointer.

2389 **

2390 ** ^(The "%w" formatting option is like "%q" except that it expects to

2391 ** be contained within double-quotes instead of single quotes, and it

2392 ** escapes the double-quote character instead of the single-quote

2393 ** character.)^ The "%w" formatting option is intended for safely inserting

2394 ** table and column names into a constructed SQL statement.

2395 **

2396 ** ^(The "%z" formatting option works like "%s" but with the

2397 ** addition that after the string has been read and copied into

2398 ** the result, [sqlite3_free()] is called on the input string.)^

2399 */

2400 char sqlite3_mprintf(const char,...);

2401 char sqlite3_vmprintf(const char, va_list);

2402 char sqlite3_snprintf(int,char,const char*, ...);

2403 char sqlite3_vsnprintf(int,char,const char*, va_list);

2404

2405 /*

2406 ** CAPI3REF: Memory Allocation Subsystem

2407 **

2408 ** The SQLite core uses these three routines for all of its own

2409 ** internal memory allocation needs. "Core" in the previous sentence

2410 ** does not include operating-system specific VFS implementation. The

2411 ** Windows VFS uses native malloc() and free() for some operations.

2412 **

2413 ** ^The sqlite3_malloc() routine returns a pointer to a block

2414 ** of memory at least N bytes in length, where N is the parameter.

2415 ** ^If sqlite3_malloc() is unable to obtain sufficient free

2416 ** memory, it returns a NULL pointer. ^If the parameter N to

2417 ** sqlite3_malloc() is zero or negative then sqlite3_malloc() returns

2418 ** a NULL pointer.

2419 **

2420 ** ^The sqlite3_malloc64(N) routine works just like

2421 ** sqlite3_malloc(N) except that N is an unsigned 64-bit integer instead

2422 ** of a signed 32-bit integer.

2423 **

2424 ** ^Calling sqlite3_free() with a pointer previously returned

2425 ** by sqlite3_malloc() or sqlite3_realloc() releases that memory so

2426 ** that it might be reused. ^The sqlite3_free() routine is

2427 ** a no-op if is called with a NULL pointer. Passing a NULL pointer

2428 ** to sqlite3_free() is harmless. After being freed, memory

2429 ** should neither be read nor written. Even reading previously freed

2430 ** memory might result in a segmentation fault or other severe error.

2431 ** Memory corruption, a segmentation fault, or other severe error

2432 ** might result if sqlite3_free() is called with a non-NULL pointer that

2433 ** was not obtained from sqlite3_malloc() or sqlite3_realloc().

2434 **

2435 ** ^The sqlite3_realloc(X,N) interface attempts to resize a

2436 ** prior memory allocation X to be at least N bytes.

2437 ** ^If the X parameter to sqlite3_realloc(X,N)

2438 ** is a NULL pointer then its behavior is identical to calling

2439 ** sqlite3_malloc(N).

2440 ** ^If the N parameter to sqlite3_realloc(X,N) is zero or

2441 ** negative then the behavior is exactly the same as calling

2442 ** sqlite3_free(X).

2443 ** ^sqlite3_realloc(X,N) returns a pointer to a memory allocation

2444 ** of at least N bytes in size or NULL if insufficient memory is available.

2445 ** ^If M is the size of the prior allocation, then min(N,M) bytes

2446 ** of the prior allocation are copied into the beginning of buffer returned

2447 ** by sqlite3_realloc(X,N) and the prior allocation is freed.

2448 ** ^If sqlite3_realloc(X,N) returns NULL and N is positive, then the

2449 ** prior allocation is not freed.

2450 **

2451 ** ^The sqlite3_realloc64(X,N) interfaces works the same as

2452 ** sqlite3_realloc(X,N) except that N is a 64-bit unsigned integer instead

2453 ** of a 32-bit signed integer.

2454 **

2455 ** ^If X is a memory allocation previously obtained from sqlite3_malloc(),

2456 ** sqlite3_malloc64(), sqlite3_realloc(), or sqlite3_realloc64(), then

2457 ** sqlite3_msize(X) returns the size of that memory allocation in bytes.

2458 ** ^The value returned by sqlite3_msize(X) might be larger than the number

2459 ** of bytes requested when X was allocated. ^If X is a NULL pointer then

2460 ** sqlite3_msize(X) returns zero. If X points to something that is not

2461 ** the beginning of memory allocation, or if it points to a formerly

2462 ** valid memory allocation that has now been freed, then the behavior

2463 ** of sqlite3_msize(X) is undefined and possibly harmful.

2464 **

2465 ** ^The memory returned by sqlite3_malloc(), sqlite3_realloc(),

2466 ** sqlite3_malloc64(), and sqlite3_realloc64()

2467 ** is always aligned to at least an 8 byte boundary, or to a

2468 ** 4 byte boundary if the [SQLITE_4_BYTE_ALIGNED_MALLOC] compile-time

2469 ** option is used.

2470 **

2471 ** In SQLite version 3.5.0 and 3.5.1, it was possible to define

2472 ** the SQLITE_OMIT_MEMORY_ALLOCATION which would cause the built-in

2473 ** implementation of these routines to be omitted. That capability

2474 ** is no longer provided. Only built-in memory allocators can be used.

2475 **

2476 ** Prior to SQLite version 3.7.10, the Windows OS interface layer called

2477 ** the system malloc() and free() directly when converting

2478 ** filenames between the UTF-8 encoding used by SQLite

2479 ** and whatever filename encoding is used by the particular Windows

2480 ** installation. Memory allocation errors were detected, but

2481 ** they were reported back as [SQLITE_CANTOPEN] or

2482 ** [SQLITE_IOERR] rather than [SQLITE_NOMEM].

2483 **

2484 ** The pointer arguments to [sqlite3_free()] and [sqlite3_realloc()]

2485 ** must be either NULL or else pointers obtained from a prior

2486 ** invocation of [sqlite3_malloc()] or [sqlite3_realloc()] that have

2487 ** not yet been released.

2488 **

2489 ** The application must not read or write any part of

2490 ** a block of memory after it has been released using

2491 ** [sqlite3_free()] or [sqlite3_realloc()].

2492 */

2493 void *sqlite3_malloc(int);

2494 void *sqlite3_malloc64(sqlite3_uint64);

2495 void sqlite3_realloc(void, int);

2496 void sqlite3_realloc64(void, sqlite3_uint64);

2497 void sqlite3_free(void*);

2498 sqlite3_uint64 sqlite3_msize(void*);

2499

2500 /*

2501 ** CAPI3REF: Memory Allocator Statistics

2502 **

2503 ** SQLite provides these two interfaces for reporting on the status

2504 ** of the [sqlite3_malloc()], [sqlite3_free()], and [sqlite3_realloc()]

2505 ** routines, which form the built-in memory allocation subsystem.

2506 **

2507 ** ^The [sqlite3_memory_used()] routine returns the number of bytes

2508 ** of memory currently outstanding (malloced but not freed).

2509 ** ^The [sqlite3_memory_highwater()] routine returns the maximum

2510 ** value of [sqlite3_memory_used()] since the high-water mark

2511 ** was last reset. ^The values returned by [sqlite3_memory_used()] and

2512 ** [sqlite3_memory_highwater()] include any overhead

2513 ** added by SQLite in its implementation of [sqlite3_malloc()],

2514 ** but not overhead added by the any underlying system library

2515 ** routines that [sqlite3_malloc()] may call.

2516 **

2517 ** ^The memory high-water mark is reset to the current value of

2518 ** [sqlite3_memory_used()] if and only if the parameter to

2519 ** [sqlite3_memory_highwater()] is true. ^The value returned

2520 ** by [sqlite3_memory_highwater(1)] is the high-water mark

2521 ** prior to the reset.

2522 */

2523 sqlite3_int64 sqlite3_memory_used(void);

2524 sqlite3_int64 sqlite3_memory_highwater(int resetFlag);

2525

2526 /*

2527 ** CAPI3REF: Pseudo-Random Number Generator

2528 **

2529 ** SQLite contains a high-quality pseudo-random number generator (PRNG) used to

2530 ** select random [ROWID \| ROWIDs] when inserting new records into a table that

2531 ** already uses the largest possible [ROWID]. The PRNG is also used for

2532 ** the build-in random() and randomblob() SQL functions. This interface allows

2533 ** applications to access the same PRNG for other purposes.

2534 **

2535 ** ^A call to this routine stores N bytes of randomness into buffer P.

2536 ** ^The P parameter can be a NULL pointer.

2537 **

2538 ** ^If this routine has not been previously called or if the previous

2539 ** call had N less than one or a NULL pointer for P, then the PRNG is

2540 ** seeded using randomness obtained from the xRandomness method of

2541 ** the default [sqlite3_vfs] object.

2542 ** ^If the previous call to this routine had an N of 1 or more and a

2543 ** non-NULL P then the pseudo-randomness is generated

2544 ** internally and without recourse to the [sqlite3_vfs] xRandomness

2545 ** method.

2546 */

2547 void sqlite3_randomness(int N, void *P);

2548

2549 /*

2550 ** CAPI3REF: Compile-Time Authorization Callbacks

2551 ** METHOD: sqlite3

2552 **

2553 ** ^This routine registers an authorizer callback with a particular

2554 ** [database connection], supplied in the first argument.

2555 ** ^The authorizer callback is invoked as SQL statements are being compiled

2556 ** by [sqlite3_prepare()] or its variants [sqlite3_prepare_v2()],

2557 ** [sqlite3_prepare16()] and [sqlite3_prepare16_v2()]. ^At various

2558 ** points during the compilation process, as logic is being created

2559 ** to perform various actions, the authorizer callback is invoked to

2560 ** see if those actions are allowed. ^The authorizer callback should

2561 ** return [SQLITE_OK] to allow the action, [SQLITE_IGNORE] to disallow the

2562 ** specific action but allow the SQL statement to continue to be

2563 ** compiled, or [SQLITE_DENY] to cause the entire SQL statement to be

2564 ** rejected with an error. ^If the authorizer callback returns

2565 ** any value other than [SQLITE_IGNORE], [SQLITE_OK], or [SQLITE_DENY]

2566 ** then the [sqlite3_prepare_v2()] or equivalent call that triggered

2567 ** the authorizer will fail with an error message.

2568 **

2569 ** When the callback returns [SQLITE_OK], that means the operation

2570 ** requested is ok. ^When the callback returns [SQLITE_DENY], the

2571 ** [sqlite3_prepare_v2()] or equivalent call that triggered the

2572 ** authorizer will fail with an error message explaining that

2573 ** access is denied.

2574 **

2575 ** ^The first parameter to the authorizer callback is a copy of the third

2576 ** parameter to the sqlite3_set_authorizer() interface. ^The second parameter

2577 ** to the callback is an integer [SQLITE_COPY \| action code] that specifies

2578 ** the particular action to be authorized. ^The third through sixth parameters

2579 ** to the callback are zero-terminated strings that contain additional

2580 ** details about the action to be authorized.

2581 **

2582 ** ^If the action code is [SQLITE_READ]

2583 ** and the callback returns [SQLITE_IGNORE] then the

2584 ** [prepared statement] statement is constructed to substitute

2585 ** a NULL value in place of the table column that would have

2586 ** been read if [SQLITE_OK] had been returned. The [SQLITE_IGNORE]

2587 ** return can be used to deny an untrusted user access to individual

2588 ** columns of a table.

2589 ** ^If the action code is [SQLITE_DELETE] and the callback returns

2590 ** [SQLITE_IGNORE] then the [DELETE] operation proceeds but the

2591 ** [truncate optimization] is disabled and all rows are deleted individually.

2592 **

2593 ** An authorizer is used when [sqlite3_prepare \| preparing]

2594 ** SQL statements from an untrusted source, to ensure that the SQL statements

2595 ** do not try to access data they are not allowed to see, or that they do not

2596 ** try to execute malicious statements that damage the database. For

2597 ** example, an application may allow a user to enter arbitrary

2598 ** SQL queries for evaluation by a database. But the application does

2599 ** not want the user to be able to make arbitrary changes to the

2600 ** database. An authorizer could then be put in place while the

2601 ** user-entered SQL is being [sqlite3_prepare \| prepared] that

2602 ** disallows everything except [SELECT] statements.

2603 **

2604 ** Applications that need to process SQL from untrusted sources

2605 ** might also consider lowering resource limits using [sqlite3_limit()]

2606 ** and limiting database size using the [max_page_count] [PRAGMA]

2607 ** in addition to using an authorizer.

2608 **

2609 ** ^(Only a single authorizer can be in place on a database connection

2610 ** at a time. Each call to sqlite3_set_authorizer overrides the

2611 ** previous call.)^ ^Disable the authorizer by installing a NULL callback.

2612 ** The authorizer is disabled by default.

2613 **

2614 ** The authorizer callback must not do anything that will modify

2615 ** the database connection that invoked the authorizer callback.

2616 ** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their

2617 ** database connections for the meaning of "modify" in this paragraph.

2618 **

2619 ** ^When [sqlite3_prepare_v2()] is used to prepare a statement, the

2620 ** statement might be re-prepared during [sqlite3_step()] due to a

2621 ** schema change. Hence, the application should ensure that the

2622 ** correct authorizer callback remains in place during the [sqlite3_step()].

2623 **

2624 ** ^Note that the authorizer callback is invoked only during

2625 ** [sqlite3_prepare()] or its variants. Authorization is not

2626 ** performed during statement evaluation in [sqlite3_step()], unless

2627 ** as stated in the previous paragraph, sqlite3_step() invokes

2628 ** sqlite3_prepare_v2() to reprepare a statement after a schema change.

2629 */

2630 int sqlite3_set_authorizer(

2631 sqlite3*,

2632 int (xAuth)(void,int,const char,const char,const char,const char),

2633 void *pUserData

2634 );

2635

2636 /*

2637 ** CAPI3REF: Authorizer Return Codes

2638 **

2639 ** The [sqlite3_set_authorizer \| authorizer callback function] must

2640 ** return either [SQLITE_OK] or one of these two constants in order

2641 ** to signal SQLite whether or not the action is permitted. See the

2642 ** [sqlite3_set_authorizer \| authorizer documentation] for additional

2643 ** information.

2644 **

2645 ** Note that SQLITE_IGNORE is also used as a [conflict resolution mode]

2646 ** returned from the [sqlite3_vtab_on_conflict()] interface.

2647 */

2648 #define SQLITE_DENY 1 /* Abort the SQL statement with an error */

2649 #define SQLITE_IGNORE 2 /* Don't allow access, but don't generate an error */

2650

2651 /*

2652 ** CAPI3REF: Authorizer Action Codes

2653 **

2654 ** The [sqlite3_set_authorizer()] interface registers a callback function

2655 ** that is invoked to authorize certain SQL statement actions. The

2656 ** second parameter to the callback is an integer code that specifies

2657 ** what action is being authorized. These are the integer action codes that

2658 ** the authorizer callback may be passed.

2659 **

2660 ** These action code values signify what kind of operation is to be

2661 ** authorized. The 3rd and 4th parameters to the authorization

2662 ** callback function will be parameters or NULL depending on which of these

2663 ** codes is used as the second parameter. ^(The 5th parameter to the

2664 ** authorizer callback is the name of the database ("main", "temp",

2665 ** etc.) if applicable.)^ ^The 6th parameter to the authorizer callback

2666 ** is the name of the inner-most trigger or view that is responsible for

2667 ** the access attempt or NULL if this access attempt is directly from

2668 ** top-level SQL code.

2669 */

2670 /***************************************** 3rd ******** 4th *********/

2671 #define SQLITE_CREATE_INDEX 1 /* Index Name Table Name */

2672 #define SQLITE_CREATE_TABLE 2 /* Table Name NULL */

2673 #define SQLITE_CREATE_TEMP_INDEX 3 /* Index Name Table Name */

2674 #define SQLITE_CREATE_TEMP_TABLE 4 /* Table Name NULL */

2675 #define SQLITE_CREATE_TEMP_TRIGGER 5 /* Trigger Name Table Name */

2676 #define SQLITE_CREATE_TEMP_VIEW 6 /* View Name NULL */

2677 #define SQLITE_CREATE_TRIGGER 7 /* Trigger Name Table Name */

2678 #define SQLITE_CREATE_VIEW 8 /* View Name NULL */

2679 #define SQLITE_DELETE 9 /* Table Name NULL */

2680 #define SQLITE_DROP_INDEX 10 /* Index Name Table Name */

2681 #define SQLITE_DROP_TABLE 11 /* Table Name NULL */

2682 #define SQLITE_DROP_TEMP_INDEX 12 /* Index Name Table Name */

2683 #define SQLITE_DROP_TEMP_TABLE 13 /* Table Name NULL */

2684 #define SQLITE_DROP_TEMP_TRIGGER 14 /* Trigger Name Table Name */

2685 #define SQLITE_DROP_TEMP_VIEW 15 /* View Name NULL */

2686 #define SQLITE_DROP_TRIGGER 16 /* Trigger Name Table Name */

2687 #define SQLITE_DROP_VIEW 17 /* View Name NULL */

2688 #define SQLITE_INSERT 18 /* Table Name NULL */

2689 #define SQLITE_PRAGMA 19 /* Pragma Name 1st arg or NULL */

2690 #define SQLITE_READ 20 /* Table Name Column Name */

2691 #define SQLITE_SELECT 21 /* NULL NULL */

2692 #define SQLITE_TRANSACTION 22 /* Operation NULL */

2693 #define SQLITE_UPDATE 23 /* Table Name Column Name */

2694 #define SQLITE_ATTACH 24 /* Filename NULL */

2695 #define SQLITE_DETACH 25 /* Database Name NULL */

2696 #define SQLITE_ALTER_TABLE 26 /* Database Name Table Name */

2697 #define SQLITE_REINDEX 27 /* Index Name NULL */

2698 #define SQLITE_ANALYZE 28 /* Table Name NULL */

2699 #define SQLITE_CREATE_VTABLE 29 /* Table Name Module Name */

2700 #define SQLITE_DROP_VTABLE 30 /* Table Name Module Name */

2701 #define SQLITE_FUNCTION 31 /* NULL Function Name */

2702 #define SQLITE_SAVEPOINT 32 /* Operation Savepoint Name */

2703 #define SQLITE_COPY 0 /* No longer used */

2704 #define SQLITE_RECURSIVE 33 /* NULL NULL */

2705

2706 /*

2707 ** CAPI3REF: Tracing And Profiling Functions

2708 ** METHOD: sqlite3

2709 **

2710 ** These routines register callback functions that can be used for

2711 ** tracing and profiling the execution of SQL statements.

2712 **

2713 ** ^The callback function registered by sqlite3_trace() is invoked at

2714 ** various times when an SQL statement is being run by [sqlite3_step()].

2715 ** ^The sqlite3_trace() callback is invoked with a UTF-8 rendering of the

2716 ** SQL statement text as the statement first begins executing.

2717 ** ^(Additional sqlite3_trace() callbacks might occur

2718 ** as each triggered subprogram is entered. The callbacks for triggers

2719 ** contain a UTF-8 SQL comment that identifies the trigger.)^

2720 **

2721 ** The [SQLITE_TRACE_SIZE_LIMIT] compile-time option can be used to limit

2722 ** the length of [bound parameter] expansion in the output of sqlite3_trace().

2723 **

2724 ** ^The callback function registered by sqlite3_profile() is invoked

2725 ** as each SQL statement finishes. ^The profile callback contains

2726 ** the original statement text and an estimate of wall-clock time

2727 ** of how long that statement took to run. ^The profile callback

2728 ** time is in units of nanoseconds, however the current implementation

2729 ** is only capable of millisecond resolution so the six least significant

2730 ** digits in the time are meaningless. Future versions of SQLite

2731 ** might provide greater resolution on the profiler callback. The

2732 ** sqlite3_profile() function is considered experimental and is

2733 ** subject to change in future versions of SQLite.

2734 */

2735 void sqlite3_trace(sqlite3, void(xTrace)(void,const char), void);

2736 SQLITE_EXPERIMENTAL void sqlite3_profile(sqlite3,

2737 void(xProfile)(void,const char,sqlite3_uint64), void);

2738

2739 /*

2740 ** CAPI3REF: Query Progress Callbacks

2741 ** METHOD: sqlite3

2742 **

2743 ** ^The sqlite3_progress_handler(D,N,X,P) interface causes the callback

2744 ** function X to be invoked periodically during long running calls to

2745 ** [sqlite3_exec()], [sqlite3_step()] and [sqlite3_get_table()] for

2746 ** database connection D. An example use for this

2747 ** interface is to keep a GUI updated during a large query.

2748 **

2749 ** ^The parameter P is passed through as the only parameter to the

2750 ** callback function X. ^The parameter N is the approximate number of

2751 ** [virtual machine instructions] that are evaluated between successive

2752 ** invocations of the callback X. ^If N is less than one then the progress

2753 ** handler is disabled.

2754 **

2755 ** ^Only a single progress handler may be defined at one time per

2756 ** [database connection]; setting a new progress handler cancels the

2757 ** old one. ^Setting parameter X to NULL disables the progress handler.

2758 ** ^The progress handler is also disabled by setting N to a value less

2759 ** than 1.

2760 **

2761 ** ^If the progress callback returns non-zero, the operation is

2762 ** interrupted. This feature can be used to implement a

2763 ** "Cancel" button on a GUI progress dialog box.

2764 **

2765 ** The progress handler callback must not do anything that will modify

2766 ** the database connection that invoked the progress handler.

2767 ** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their

2768 ** database connections for the meaning of "modify" in this paragraph.

2769 **

2770 */

2771 void sqlite3_progress_handler(sqlite3, int, int()(void), void);

2772

2773 /*

2774 ** CAPI3REF: Opening A New Database Connection

2775 ** CONSTRUCTOR: sqlite3

2776 **

2777 ** ^These routines open an SQLite database file as specified by the

2778 ** filename argument. ^The filename argument is interpreted as UTF-8 for

2779 ** sqlite3_open() and sqlite3_open_v2() and as UTF-16 in the native byte

2780 ** order for sqlite3_open16(). ^(A [database connection] handle is usually

2781 ** returned in *ppDb, even if an error occurs. The only exception is that

2782 ** if SQLite is unable to allocate memory to hold the [sqlite3] object,

2783 ** a NULL will be written into *ppDb instead of a pointer to the [sqlite3]

2784 ** object.)^ ^(If the database is opened (and/or created) successfully, then

2785 ** [SQLITE_OK] is returned. Otherwise an [error code] is returned.)^ ^The

2786 ** [sqlite3_errmsg()] or [sqlite3_errmsg16()] routines can be used to obtain

2787 ** an English language description of the error following a failure of any

2788 ** of the sqlite3_open() routines.

2789 **

2790 ** ^The default encoding will be UTF-8 for databases created using

2791 ** sqlite3_open() or sqlite3_open_v2(). ^The default encoding for databases

2792 ** created using sqlite3_open16() will be UTF-16 in the native byte order.

2793 **

2794 ** Whether or not an error occurs when it is opened, resources

2795 ** associated with the [database connection] handle should be released by

2796 ** passing it to [sqlite3_close()] when it is no longer required.

2797 **

2798 ** The sqlite3_open_v2() interface works like sqlite3_open()

2799 ** except that it accepts two additional parameters for additional control

2800 ** over the new database connection. ^(The flags parameter to

2801 ** sqlite3_open_v2() can take one of

2802 ** the following three values, optionally combined with the

2803 ** [SQLITE_OPEN_NOMUTEX], [SQLITE_OPEN_FULLMUTEX], [SQLITE_OPEN_SHAREDCACHE],

2804 ** [SQLITE_OPEN_PRIVATECACHE], and/or [SQLITE_OPEN_URI] flags:)^

2805 **

2806 ** <dl>

2807 ** ^(<dt>[SQLITE_OPEN_READONLY]</dt>

2808 ** <dd>The database is opened in read-only mode. If the database does not

2809 ** already exist, an error is returned.</dd>)^

2810 **

2811 ** ^(<dt>[SQLITE_OPEN_READWRITE]</dt>

2812 ** <dd>The database is opened for reading and writing if possible, or reading

2813 ** only if the file is write protected by the operating system. In either

2814 ** case the database must already exist, otherwise an error is returned.</dd>)^

2815 **

2816 ** ^(<dt>[SQLITE_OPEN_READWRITE] \| [SQLITE_OPEN_CREATE]</dt>

2817 ** <dd>The database is opened for reading and writing, and is created if

2818 ** it does not already exist. This is the behavior that is always used for

2819 ** sqlite3_open() and sqlite3_open16().</dd>)^

2820 ** </dl>

2821 **

2822 ** If the 3rd parameter to sqlite3_open_v2() is not one of the

2823 ** combinations shown above optionally combined with other

2824 ** [SQLITE_OPEN_READONLY \| SQLITE_OPEN_* bits]

2825 ** then the behavior is undefined.

2826 **

2827 ** ^If the [SQLITE_OPEN_NOMUTEX] flag is set, then the database connection

2828 ** opens in the multi-thread [threading mode] as long as the single-thread

2829 ** mode has not been set at compile-time or start-time. ^If the

2830 ** [SQLITE_OPEN_FULLMUTEX] flag is set then the database connection opens

2831 ** in the serialized [threading mode] unless single-thread was

2832 ** previously selected at compile-time or start-time.

2833 ** ^The [SQLITE_OPEN_SHAREDCACHE] flag causes the database connection to be

2834 ** eligible to use [shared cache mode], regardless of whether or not shared

2835 ** cache is enabled using [sqlite3_enable_shared_cache()]. ^The

2836 ** [SQLITE_OPEN_PRIVATECACHE] flag causes the database connection to not

2837 ** participate in [shared cache mode] even if it is enabled.

2838 **

2839 ** ^The fourth parameter to sqlite3_open_v2() is the name of the

2840 ** [sqlite3_vfs] object that defines the operating system interface that

2841 ** the new database connection should use. ^If the fourth parameter is

2842 ** a NULL pointer then the default [sqlite3_vfs] object is used.

2843 **

2844 ** ^If the filename is ":memory:", then a private, temporary in-memory database

2845 ** is created for the connection. ^This in-memory database will vanish when

2846 ** the database connection is closed. Future versions of SQLite might

2847 ** make use of additional special filenames that begin with the ":" character.

2848 ** It is recommended that when a database filename actually does begin with

2849 ** a ":" character you should prefix the filename with a pathname such as

2850 ** "./" to avoid ambiguity.

2851 **

2852 ** ^If the filename is an empty string, then a private, temporary

2853 ** on-disk database will be created. ^This private database will be

2854 ** automatically deleted as soon as the database connection is closed.

2855 **

2856 ** [[URI filenames in sqlite3_open()]] <h3>URI Filenames</h3>

2857 **

2858 ** ^If [URI filename] interpretation is enabled, and the filename argument

2859 ** begins with "file:", then the filename is interpreted as a URI. ^URI

2860 ** filename interpretation is enabled if the [SQLITE_OPEN_URI] flag is

2861 ** set in the fourth argument to sqlite3_open_v2(), or if it has

2862 ** been enabled globally using the [SQLITE_CONFIG_URI] option with the

2863 ** [sqlite3_config()] method or by the [SQLITE_USE_URI] compile-time option.

2864 ** As of SQLite version 3.7.7, URI filename interpretation is turned off

2865 ** by default, but future releases of SQLite might enable URI filename

2866 ** interpretation by default. See "[URI filenames]" for additional

2867 ** information.

2868 **

2869 ** URI filenames are parsed according to RFC 3986. ^If the URI contains an

2870 ** authority, then it must be either an empty string or the string

2871 ** "localhost". ^If the authority is not an empty string or "localhost", an

2872 ** error is returned to the caller. ^The fragment component of a URI, if

2873 ** present, is ignored.

2874 **

2875 ** ^SQLite uses the path component of the URI as the name of the disk file

2876 ** which contains the database. ^If the path begins with a '/' character,

2877 ** then it is interpreted as an absolute path. ^If the path does not begin

2878 ** with a '/' (meaning that the authority section is omitted from the URI)

2879 ** then the path is interpreted as a relative path.

2880 ** ^(On windows, the first component of an absolute path

2881 ** is a drive specification (e.g. "C:").)^

2882 **

2883 ** [[core URI query parameters]]

2884 ** The query component of a URI may contain parameters that are interpreted

2885 ** either by SQLite itself, or by a [VFS \| custom VFS implementation].

2886 ** SQLite and its built-in [VFSes] interpret the

2887 ** following query parameters:

2888 **

2889 ** <ul>

2890 ** <li> <b>vfs</b>: ^The "vfs" parameter may be used to specify the name of

2891 ** a VFS object that provides the operating system interface that should

2892 ** be used to access the database file on disk. ^If this option is set to

2893 ** an empty string the default VFS object is used. ^Specifying an unknown

2894 ** VFS is an error. ^If sqlite3_open_v2() is used and the vfs option is

2895 ** present, then the VFS specified by the option takes precedence over

2896 ** the value passed as the fourth parameter to sqlite3_open_v2().

2897 **

2898 ** <li> <b>mode</b>: ^(The mode parameter may be set to either "ro", "rw",

2899 ** "rwc", or "memory". Attempting to set it to any other value is

2900 ** an error)^.

2901 ** ^If "ro" is specified, then the database is opened for read-only

2902 ** access, just as if the [SQLITE_OPEN_READONLY] flag had been set in the

2903 ** third argument to sqlite3_open_v2(). ^If the mode option is set to

2904 ** "rw", then the database is opened for read-write (but not create)

2905 ** access, as if SQLITE_OPEN_READWRITE (but not SQLITE_OPEN_CREATE) had

2906 ** been set. ^Value "rwc" is equivalent to setting both

2907 ** SQLITE_OPEN_READWRITE and SQLITE_OPEN_CREATE. ^If the mode option is

2908 ** set to "memory" then a pure [in-memory database] that never reads

2909 ** or writes from disk is used. ^It is an error to specify a value for

2910 ** the mode parameter that is less restrictive than that specified by

2911 ** the flags passed in the third parameter to sqlite3_open_v2().

2912 **

2913 ** <li> <b>cache</b>: ^The cache parameter may be set to either "shared" or

2914 ** "private". ^Setting it to "shared" is equivalent to setting the

2915 ** SQLITE_OPEN_SHAREDCACHE bit in the flags argument passed to

2916 ** sqlite3_open_v2(). ^Setting the cache parameter to "private" is

2917 ** equivalent to setting the SQLITE_OPEN_PRIVATECACHE bit.

2918 ** ^If sqlite3_open_v2() is used and the "cache" parameter is present in

2919 ** a URI filename, its value overrides any behavior requested by setting

2920 ** SQLITE_OPEN_PRIVATECACHE or SQLITE_OPEN_SHAREDCACHE flag.

2921 **

2922 ** <li> <b>psow</b>: ^The psow parameter indicates whether or not the

2923 ** [powersafe overwrite] property does or does not apply to the

2924 ** storage media on which the database file resides.

2925 **

2926 ** <li> <b>nolock</b>: ^The nolock parameter is a boolean query parameter

2927 ** which if set disables file locking in rollback journal modes. This

2928 ** is useful for accessing a database on a filesystem that does not

2929 ** support locking. Caution: Database corruption might result if two

2930 ** or more processes write to the same database and any one of those

2931 ** processes uses nolock=1.

2932 **

2933 ** <li> <b>immutable</b>: ^The immutable parameter is a boolean query

2934 ** parameter that indicates that the database file is stored on

2935 ** read-only media. ^When immutable is set, SQLite assumes that the

2936 ** database file cannot be changed, even by a process with higher

2937 ** privilege, and so the database is opened read-only and all locking

2938 ** and change detection is disabled. Caution: Setting the immutable

2939 ** property on a database file that does in fact change can result

2940 ** in incorrect query results and/or [SQLITE_CORRUPT] errors.

2941 ** See also: [SQLITE_IOCAP_IMMUTABLE].

2942 **

2943 ** </ul>

2944 **

2945 ** ^Specifying an unknown parameter in the query component of a URI is not an

2946 ** error. Future versions of SQLite might understand additional query

2947 ** parameters. See "[query parameters with special meaning to SQLite]" for

2948 ** additional information.

2949 **

2950 ** [[URI filename examples]] <h3>URI filename examples</h3>

2951 **

2952 ** <table border="1" align=center cellpadding=5>

2953 ** <tr><th> URI filenames <th> Results

2954 ** <tr><td> file:data.db <td>

2955 ** Open the file "data.db" in the current directory.

2956 ** <tr><td> file:/home/fred/data.db<br>

2957 ** file:///home/fred/data.db <br>

2958 ** file://localhost/home/fred/data.db <br> <td>

2959 ** Open the database file "/home/fred/data.db".

2960 ** <tr><td> file://darkstar/home/fred/data.db <td>

2961 ** An error. "darkstar" is not a recognized authority.

2962 ** <tr><td style="white-space:nowrap">

2963 ** file:///C:/Documents%20and%20Settings/fred/Desktop/data.db

2964 ** <td> Windows only: Open the file "data.db" on fred's desktop on drive

2965 ** C:. Note that the %20 escaping in this example is not strictly

2966 ** necessary - space characters can be used literally

2967 ** in URI filenames.

2968 ** <tr><td> file:data.db?mode=ro&cache=private <td>

2969 ** Open file "data.db" in the current directory for read-only access.

2970 ** Regardless of whether or not shared-cache mode is enabled by

2971 ** default, use a private cache.

2972 ** <tr><td> file:/home/fred/data.db?vfs=unix-dotfile <td>

2973 ** Open file "/home/fred/data.db". Use the special VFS "unix-dotfile"

2974 ** that uses dot-files in place of posix advisory locking.

2975 ** <tr><td> file:data.db?mode=readonly <td>

2976 ** An error. "readonly" is not a valid option for the "mode" parameter.

2977 ** </table>

2978 **

2979 ** ^URI hexadecimal escape sequences (%HH) are supported within the path and

2980 ** query components of a URI. A hexadecimal escape sequence consists of a

2981 ** percent sign - "%" - followed by exactly two hexadecimal digits

2982 ** specifying an octet value. ^Before the path or query components of a

2983 ** URI filename are interpreted, they are encoded using UTF-8 and all

2984 ** hexadecimal escape sequences replaced by a single byte containing the

2985 ** corresponding octet. If this process generates an invalid UTF-8 encoding,

2986 ** the results are undefined.

2987 **

2988 ** <b>Note to Windows users:</b> The encoding used for the filename argument

2989 ** of sqlite3_open() and sqlite3_open_v2() must be UTF-8, not whatever

2990 ** codepage is currently defined. Filenames containing international

2991 ** characters must be converted to UTF-8 prior to passing them into

2992 ** sqlite3_open() or sqlite3_open_v2().

2993 **

2994 ** <b>Note to Windows Runtime users:</b> The temporary directory must be set

2995 ** prior to calling sqlite3_open() or sqlite3_open_v2(). Otherwise, various

2996 ** features that require the use of temporary files may fail.

2997 **

2998 ** See also: [sqlite3_temp_directory]

2999 */

3000 int sqlite3_open(

3001 const char filename, / Database filename (UTF-8) */

3002 sqlite3 *ppDb / OUT: SQLite db handle */

3003 );

3004 int sqlite3_open16(

3005 const void filename, / Database filename (UTF-16) */

3006 sqlite3 *ppDb / OUT: SQLite db handle */

3007 );

3008 int sqlite3_open_v2(

3009 const char filename, / Database filename (UTF-8) */

3010 sqlite3 *ppDb, / OUT: SQLite db handle */

3011 int flags, /* Flags */

3012 const char zVfs / Name of VFS module to use */

3013 );

3014

3015 /*

3016 ** CAPI3REF: Obtain Values For URI Parameters

3017 **

3018 ** These are utility routines, useful to VFS implementations, that check

3019 ** to see if a database file was a URI that contained a specific query

3020 ** parameter, and if so obtains the value of that query parameter.

3021 **

3022 ** If F is the database filename pointer passed into the xOpen() method of

3023 ** a VFS implementation when the flags parameter to xOpen() has one or

3024 ** more of the [SQLITE_OPEN_URI] or [SQLITE_OPEN_MAIN_DB] bits set and

3025 ** P is the name of the query parameter, then

3026 ** sqlite3_uri_parameter(F,P) returns the value of the P

3027 ** parameter if it exists or a NULL pointer if P does not appear as a

3028 ** query parameter on F. If P is a query parameter of F

3029 ** has no explicit value, then sqlite3_uri_parameter(F,P) returns

3030 ** a pointer to an empty string.

3031 **

3032 ** The sqlite3_uri_boolean(F,P,B) routine assumes that P is a boolean

3033 ** parameter and returns true (1) or false (0) according to the value

3034 ** of P. The sqlite3_uri_boolean(F,P,B) routine returns true (1) if the

3035 ** value of query parameter P is one of "yes", "true", or "on" in any

3036 ** case or if the value begins with a non-zero number. The

3037 ** sqlite3_uri_boolean(F,P,B) routines returns false (0) if the value of

3038 ** query parameter P is one of "no", "false", or "off" in any case or

3039 ** if the value begins with a numeric zero. If P is not a query

3040 ** parameter on F or if the value of P is does not match any of the

3041 ** above, then sqlite3_uri_boolean(F,P,B) returns (B!=0).

3042 **

3043 ** The sqlite3_uri_int64(F,P,D) routine converts the value of P into a

3044 ** 64-bit signed integer and returns that integer, or D if P does not

3045 ** exist. If the value of P is something other than an integer, then

3046 ** zero is returned.

3047 **

3048 ** If F is a NULL pointer, then sqlite3_uri_parameter(F,P) returns NULL and

3049 ** sqlite3_uri_boolean(F,P,B) returns B. If F is not a NULL pointer and

3050 ** is not a database file pathname pointer that SQLite passed into the xOpen

3051 ** VFS method, then the behavior of this routine is undefined and probably

3052 ** undesirable.

3053 */

3054 const char sqlite3_uri_parameter(const char zFilename, const char *zParam);

3055 int sqlite3_uri_boolean(const char zFile, const char zParam, int bDefault);

3056 sqlite3_int64 sqlite3_uri_int64(const char, const char, sqlite3_int64);

3057

3058

3059 /*

3060 ** CAPI3REF: Error Codes And Messages

3061 ** METHOD: sqlite3

3062 **

3063 ** ^If the most recent sqlite3_* API call associated with

3064 ** [database connection] D failed, then the sqlite3_errcode(D) interface

3065 ** returns the numeric [result code] or [extended result code] for that

3066 ** API call.

3067 ** If the most recent API call was successful,

3068 ** then the return value from sqlite3_errcode() is undefined.

3069 ** ^The sqlite3_extended_errcode()

3070 ** interface is the same except that it always returns the

3071 ** [extended result code] even when extended result codes are

3072 ** disabled.

3073 **

3074 ** ^The sqlite3_errmsg() and sqlite3_errmsg16() return English-language

3075 ** text that describes the error, as either UTF-8 or UTF-16 respectively.

3076 ** ^(Memory to hold the error message string is managed internally.

3077 ** The application does not need to worry about freeing the result.

3078 ** However, the error string might be overwritten or deallocated by

3079 ** subsequent calls to other SQLite interface functions.)^

3080 **

3081 ** ^The sqlite3_errstr() interface returns the English-language text

3082 ** that describes the [result code], as UTF-8.

3083 ** ^(Memory to hold the error message string is managed internally

3084 ** and must not be freed by the application)^.

3085 **

3086 ** When the serialized [threading mode] is in use, it might be the

3087 ** case that a second error occurs on a separate thread in between

3088 ** the time of the first error and the call to these interfaces.

3089 ** When that happens, the second error will be reported since these

3090 ** interfaces always report the most recent result. To avoid

3091 ** this, each thread can obtain exclusive use of the [database connection] D

3092 ** by invoking [sqlite3_mutex_enter]([sqlite3_db_mutex](D)) before beginning

3093 ** to use D and invoking [sqlite3_mutex_leave]([sqlite3_db_mutex](D)) after

3094 ** all calls to the interfaces listed here are completed.

3095 **

3096 ** If an interface fails with SQLITE_MISUSE, that means the interface

3097 ** was invoked incorrectly by the application. In that case, the

3098 ** error code and message may or may not be set.

3099 */

3100 int sqlite3_errcode(sqlite3 *db);

3101 int sqlite3_extended_errcode(sqlite3 *db);

3102 const char sqlite3_errmsg(sqlite3);

3103 const void sqlite3_errmsg16(sqlite3);

3104 const char *sqlite3_errstr(int);

3105

3106 /*

3107 ** CAPI3REF: Prepared Statement Object

3108 ** KEYWORDS: {prepared statement} {prepared statements}

3109 **

3110 ** An instance of this object represents a single SQL statement that

3111 ** has been compiled into binary form and is ready to be evaluated.

3112 **

3113 ** Think of each SQL statement as a separate computer program. The

3114 ** original SQL text is source code. A prepared statement object

3115 ** is the compiled object code. All SQL must be converted into a

3116 ** prepared statement before it can be run.

3117 **

3118 ** The life-cycle of a prepared statement object usually goes like this:

3119 **

3120 ** <ol>

3121 ** <li> Create the prepared statement object using [sqlite3_prepare_v2()].

3122 ** <li> Bind values to [parameters] using the sqlite3_bind_*()

3123 ** interfaces.

3124 ** <li> Run the SQL by calling [sqlite3_step()] one or more times.

3125 ** <li> Reset the prepared statement using [sqlite3_reset()] then go back

3126 ** to step 2. Do this zero or more times.

3127 ** <li> Destroy the object using [sqlite3_finalize()].

3128 ** </ol>

3129 */

3130 typedef struct sqlite3_stmt sqlite3_stmt;

3131

3132 /*

3133 ** CAPI3REF: Run-time Limits

3134 ** METHOD: sqlite3

3135 **

3136 ** ^(This interface allows the size of various constructs to be limited

3137 ** on a connection by connection basis. The first parameter is the

3138 ** [database connection] whose limit is to be set or queried. The

3139 ** second parameter is one of the [limit categories] that define a

3140 ** class of constructs to be size limited. The third parameter is the

3141 ** new limit for that construct.)^

3142 **

3143 ** ^If the new limit is a negative number, the limit is unchanged.

3144 ** ^(For each limit category SQLITE_LIMIT_<i>NAME</i> there is a

3145 ** [limits \| hard upper bound]

3146 ** set at compile-time by a C preprocessor macro called

3147 ** [limits \| SQLITE_MAX_<i>NAME</i>].

3148 ** (The "_LIMIT_" in the name is changed to "_MAX_".))^

3149 ** ^Attempts to increase a limit above its hard upper bound are

3150 ** silently truncated to the hard upper bound.

3151 **

3152 ** ^Regardless of whether or not the limit was changed, the

3153 ** [sqlite3_limit()] interface returns the prior value of the limit.

3154 ** ^Hence, to find the current value of a limit without changing it,

3155 ** simply invoke this interface with the third parameter set to -1.

3156 **

3157 ** Run-time limits are intended for use in applications that manage

3158 ** both their own internal database and also databases that are controlled

3159 ** by untrusted external sources. An example application might be a

3160 ** web browser that has its own databases for storing history and

3161 ** separate databases controlled by JavaScript applications downloaded

3162 ** off the Internet. The internal databases can be given the

3163 ** large, default limits. Databases managed by external sources can

3164 ** be given much smaller limits designed to prevent a denial of service

3165 ** attack. Developers might also want to use the [sqlite3_set_authorizer()]

3166 ** interface to further control untrusted SQL. The size of the database

3167 ** created by an untrusted script can be contained using the

3168 ** [max_page_count] [PRAGMA].

3169 **

3170 ** New run-time limit categories may be added in future releases.

3171 */

3172 int sqlite3_limit(sqlite3*, int id, int newVal);

3173

3174 /*

3175 ** CAPI3REF: Run-Time Limit Categories

3176 ** KEYWORDS: {limit category} {*limit categories}

3177 **

3178 ** These constants define various performance limits

3179 ** that can be lowered at run-time using [sqlite3_limit()].

3180 ** The synopsis of the meanings of the various limits is shown below.

3181 ** Additional information is available at [limits \| Limits in SQLite].

3182 **

3183 ** <dl>

3184 ** [[SQLITE_LIMIT_LENGTH]] ^(<dt>SQLITE_LIMIT_LENGTH</dt>

3185 ** <dd>The maximum size of any string or BLOB or table row, in bytes.<dd>)^

3186 **

3187 ** [[SQLITE_LIMIT_SQL_LENGTH]] ^(<dt>SQLITE_LIMIT_SQL_LENGTH</dt>

3188 ** <dd>The maximum length of an SQL statement, in bytes.</dd>)^

3189 **

3190 ** [[SQLITE_LIMIT_COLUMN]] ^(<dt>SQLITE_LIMIT_COLUMN</dt>

3191 ** <dd>The maximum number of columns in a table definition or in the

3192 ** result set of a [SELECT] or the maximum number of columns in an index

3193 ** or in an ORDER BY or GROUP BY clause.</dd>)^

3194 **

3195 ** [[SQLITE_LIMIT_EXPR_DEPTH]] ^(<dt>SQLITE_LIMIT_EXPR_DEPTH</dt>

3196 ** <dd>The maximum depth of the parse tree on any expression.</dd>)^

3197 **

3198 ** [[SQLITE_LIMIT_COMPOUND_SELECT]] ^(<dt>SQLITE_LIMIT_COMPOUND_SELECT</dt>

3199 ** <dd>The maximum number of terms in a compound SELECT statement.</dd>)^

3200 **

3201 ** [[SQLITE_LIMIT_VDBE_OP]] ^(<dt>SQLITE_LIMIT_VDBE_OP</dt>

3202 ** <dd>The maximum number of instructions in a virtual machine program

3203 ** used to implement an SQL statement. This limit is not currently

3204 ** enforced, though that might be added in some future release of

3205 ** SQLite.</dd>)^

3206 **

3207 ** [[SQLITE_LIMIT_FUNCTION_ARG]] ^(<dt>SQLITE_LIMIT_FUNCTION_ARG</dt>

3208 ** <dd>The maximum number of arguments on a function.</dd>)^

3209 **

3210 ** [[SQLITE_LIMIT_ATTACHED]] ^(<dt>SQLITE_LIMIT_ATTACHED</dt>

3211 ** <dd>The maximum number of [ATTACH \| attached databases].)^</dd>

3212 **

3213 ** [[SQLITE_LIMIT_LIKE_PATTERN_LENGTH]]

3214 ** ^(<dt>SQLITE_LIMIT_LIKE_PATTERN_LENGTH</dt>

3215 ** <dd>The maximum length of the pattern argument to the [LIKE] or

3216 ** [GLOB] operators.</dd>)^

3217 **

3218 ** [[SQLITE_LIMIT_VARIABLE_NUMBER]]

3219 ** ^(<dt>SQLITE_LIMIT_VARIABLE_NUMBER</dt>

3220 ** <dd>The maximum index number of any [parameter] in an SQL statement.)^

3221 **

3222 ** [[SQLITE_LIMIT_TRIGGER_DEPTH]] ^(<dt>SQLITE_LIMIT_TRIGGER_DEPTH</dt>

3223 ** <dd>The maximum depth of recursion for triggers.</dd>)^

3224 **

3225 ** [[SQLITE_LIMIT_WORKER_THREADS]] ^(<dt>SQLITE_LIMIT_WORKER_THREADS</dt>

3226 ** <dd>The maximum number of auxiliary worker threads that a single

3227 ** [prepared statement] may start.</dd>)^

3228 ** </dl>

3229 */

3230 #define SQLITE_LIMIT_LENGTH 0

3231 #define SQLITE_LIMIT_SQL_LENGTH 1

3232 #define SQLITE_LIMIT_COLUMN 2

3233 #define SQLITE_LIMIT_EXPR_DEPTH 3

3234 #define SQLITE_LIMIT_COMPOUND_SELECT 4

3235 #define SQLITE_LIMIT_VDBE_OP 5

3236 #define SQLITE_LIMIT_FUNCTION_ARG 6

3237 #define SQLITE_LIMIT_ATTACHED 7

3238 #define SQLITE_LIMIT_LIKE_PATTERN_LENGTH 8

3239 #define SQLITE_LIMIT_VARIABLE_NUMBER 9

3240 #define SQLITE_LIMIT_TRIGGER_DEPTH 10

3241 #define SQLITE_LIMIT_WORKER_THREADS 11

3242

3243 /*

3244 ** CAPI3REF: Compiling An SQL Statement

3245 ** KEYWORDS: {SQL statement compiler}

3246 ** METHOD: sqlite3

3247 ** CONSTRUCTOR: sqlite3_stmt

3248 **

3249 ** To execute an SQL query, it must first be compiled into a byte-code

3250 ** program using one of these routines.

3251 **

3252 ** The first argument, "db", is a [database connection] obtained from a

3253 ** prior successful call to [sqlite3_open()], [sqlite3_open_v2()] or

3254 ** [sqlite3_open16()]. The database connection must not have been closed.

3255 **

3256 ** The second argument, "zSql", is the statement to be compiled, encoded

3257 ** as either UTF-8 or UTF-16. The sqlite3_prepare() and sqlite3_prepare_v2()

3258 ** interfaces use UTF-8, and sqlite3_prepare16() and sqlite3_prepare16_v2()

3259 ** use UTF-16.

3260 **

3261 ** ^If the nByte argument is negative, then zSql is read up to the

3262 ** first zero terminator. ^If nByte is positive, then it is the

3263 ** number of bytes read from zSql. ^If nByte is zero, then no prepared

3264 ** statement is generated.

3265 ** If the caller knows that the supplied string is nul-terminated, then

3266 ** there is a small performance advantage to passing an nByte parameter that

3267 ** is the number of bytes in the input string <i>including</i>

3268 ** the nul-terminator.

3269 **

3270 ** ^If pzTail is not NULL then *pzTail is made to point to the first byte

3271 ** past the end of the first SQL statement in zSql. These routines only

3272 ** compile the first statement in zSql, so *pzTail is left pointing to

3273 ** what remains uncompiled.

3274 **

3275 ** ^*ppStmt is left pointing to a compiled [prepared statement] that can be

3276 ** executed using [sqlite3_step()]. ^If there is an error, *ppStmt is set

3277 ** to NULL. ^If the input text contains no SQL (if the input is an empty

3278 ** string or a comment) then *ppStmt is set to NULL.

3279 ** The calling procedure is responsible for deleting the compiled

3280 ** SQL statement using [sqlite3_finalize()] after it has finished with it.

3281 ** ppStmt may not be NULL.

3282 **

3283 ** ^On success, the sqlite3_prepare() family of routines return [SQLITE_OK];

3284 ** otherwise an [error code] is returned.

3285 **

3286 ** The sqlite3_prepare_v2() and sqlite3_prepare16_v2() interfaces are

3287 ** recommended for all new programs. The two older interfaces are retained

3288 ** for backwards compatibility, but their use is discouraged.

3289 ** ^In the "v2" interfaces, the prepared statement

3290 ** that is returned (the [sqlite3_stmt] object) contains a copy of the

3291 ** original SQL text. This causes the [sqlite3_step()] interface to

3292 ** behave differently in three ways:

3293 **

3294 ** <ol>

3295 ** <li>

3296 ** ^If the database schema changes, instead of returning [SQLITE_SCHEMA] as it

3297 ** always used to do, [sqlite3_step()] will automatically recompile the SQL

3298 ** statement and try to run it again. As many as [SQLITE_MAX_SCHEMA_RETRY]

3299 ** retries will occur before sqlite3_step() gives up and returns an error.

3300 ** </li>

3301 **

3302 ** <li>

3303 ** ^When an error occurs, [sqlite3_step()] will return one of the detailed

3304 ** [error codes] or [extended error codes]. ^The legacy behavior was that

3305 ** [sqlite3_step()] would only return a generic [SQLITE_ERROR] result code

3306 ** and the application would have to make a second call to [sqlite3_reset()]

3307 ** in order to find the underlying cause of the problem. With the "v2" prepare

3308 ** interfaces, the underlying reason for the error is returned immediately.

3309 ** </li>

3310 **

3311 ** <li>

3312 ** ^If the specific value bound to [parameter \| host parameter] in the

3313 ** WHERE clause might influence the choice of query plan for a statement,

3314 ** then the statement will be automatically recompiled, as if there had been

3315 ** a schema change, on the first [sqlite3_step()] call following any change

3316 ** to the [sqlite3_bind_text \| bindings] of that [parameter].

3317 ** ^The specific value of WHERE-clause [parameter] might influence the

3318 ** choice of query plan if the parameter is the left-hand side of a [LIKE]

3319 ** or [GLOB] operator or if the parameter is compared to an indexed column

3320 ** and the [SQLITE_ENABLE_STAT3] compile-time option is enabled.

3321 ** </li>

3322 ** </ol>

3323 */

3324 int sqlite3_prepare(

3325 sqlite3 db, / Database handle */

3326 const char zSql, / SQL statement, UTF-8 encoded */

3327 int nByte, /* Maximum length of zSql in bytes. */

3328 sqlite3_stmt *ppStmt, / OUT: Statement handle */

3329 const char *pzTail / OUT: Pointer to unused portion of zSql */

3330 );

3331 int sqlite3_prepare_v2(

3332 sqlite3 db, / Database handle */

3333 const char zSql, / SQL statement, UTF-8 encoded */

3334 int nByte, /* Maximum length of zSql in bytes. */

3335 sqlite3_stmt *ppStmt, / OUT: Statement handle */

3336 const char *pzTail / OUT: Pointer to unused portion of zSql */

3337 );

3338 int sqlite3_prepare16(

3339 sqlite3 db, / Database handle */

3340 const void zSql, / SQL statement, UTF-16 encoded */

3341 int nByte, /* Maximum length of zSql in bytes. */

3342 sqlite3_stmt *ppStmt, / OUT: Statement handle */

3343 const void *pzTail / OUT: Pointer to unused portion of zSql */

3344 );

3345 int sqlite3_prepare16_v2(

3346 sqlite3 db, / Database handle */

3347 const void zSql, / SQL statement, UTF-16 encoded */

3348 int nByte, /* Maximum length of zSql in bytes. */

3349 sqlite3_stmt *ppStmt, / OUT: Statement handle */

3350 const void *pzTail / OUT: Pointer to unused portion of zSql */

3351 );

3352

3353 /*

3354 ** CAPI3REF: Retrieving Statement SQL

3355 ** METHOD: sqlite3_stmt

3356 **

3357 ** ^This interface can be used to retrieve a saved copy of the original

3358 ** SQL text used to create a [prepared statement] if that statement was

3359 ** compiled using either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()].

3360 */

3361 const char sqlite3_sql(sqlite3_stmt pStmt);

3362

3363 /*

3364 ** CAPI3REF: Determine If An SQL Statement Writes The Database

3365 ** METHOD: sqlite3_stmt

3366 **

3367 ** ^The sqlite3_stmt_readonly(X) interface returns true (non-zero) if

3368 ** and only if the [prepared statement] X makes no direct changes to

3369 ** the content of the database file.

3370 **

3371 ** Note that [application-defined SQL functions] or

3372 ** [virtual tables] might change the database indirectly as a side effect.

3373 ** ^(For example, if an application defines a function "eval()" that

3374 ** calls [sqlite3_exec()], then the following SQL statement would

3375 ** change the database file through side-effects:

3376 **

3377 ** <blockquote><pre>

3378 ** SELECT eval('DELETE FROM t1') FROM t2;

3379 ** </pre></blockquote>

3380 **

3381 ** But because the [SELECT] statement does not change the database file

3382 ** directly, sqlite3_stmt_readonly() would still return true.)^

3383 **

3384 ** ^Transaction control statements such as [BEGIN], [COMMIT], [ROLLBACK],

3385 ** [SAVEPOINT], and [RELEASE] cause sqlite3_stmt_readonly() to return true,

3386 ** since the statements themselves do not actually modify the database but

3387 ** rather they control the timing of when other statements modify the

3388 ** database. ^The [ATTACH] and [DETACH] statements also cause

3389 ** sqlite3_stmt_readonly() to return true since, while those statements

3390 ** change the configuration of a database connection, they do not make

3391 ** changes to the content of the database files on disk.

3392 */

3393 int sqlite3_stmt_readonly(sqlite3_stmt *pStmt);

3394

3395 /*

3396 ** CAPI3REF: Determine If A Prepared Statement Has Been Reset

3397 ** METHOD: sqlite3_stmt

3398 **

3399 ** ^The sqlite3_stmt_busy(S) interface returns true (non-zero) if the

3400 ** [prepared statement] S has been stepped at least once using

3401 ** [sqlite3_step(S)] but has neither run to completion (returned

3402 ** [SQLITE_DONE] from [sqlite3_step(S)]) nor

3403 ** been reset using [sqlite3_reset(S)]. ^The sqlite3_stmt_busy(S)

3404 ** interface returns false if S is a NULL pointer. If S is not a

3405 ** NULL pointer and is not a pointer to a valid [prepared statement]

3406 ** object, then the behavior is undefined and probably undesirable.

3407 **

3408 ** This interface can be used in combination [sqlite3_next_stmt()]

3409 ** to locate all prepared statements associated with a database

3410 ** connection that are in need of being reset. This can be used,

3411 ** for example, in diagnostic routines to search for prepared

3412 ** statements that are holding a transaction open.

3413 */

3414 int sqlite3_stmt_busy(sqlite3_stmt*);

3415

3416 /*

3417 ** CAPI3REF: Dynamically Typed Value Object

3418 ** KEYWORDS: {protected sqlite3_value} {unprotected sqlite3_value}

3419 **

3420 ** SQLite uses the sqlite3_value object to represent all values

3421 ** that can be stored in a database table. SQLite uses dynamic typing

3422 ** for the values it stores. ^Values stored in sqlite3_value objects

3423 ** can be integers, floating point values, strings, BLOBs, or NULL.

3424 **

3425 ** An sqlite3_value object may be either "protected" or "unprotected".

3426 ** Some interfaces require a protected sqlite3_value. Other interfaces

3427 ** will accept either a protected or an unprotected sqlite3_value.

3428 ** Every interface that accepts sqlite3_value arguments specifies

3429 ** whether or not it requires a protected sqlite3_value. The

3430 ** [sqlite3_value_dup()] interface can be used to construct a new

3431 ** protected sqlite3_value from an unprotected sqlite3_value.

3432 **

3433 ** The terms "protected" and "unprotected" refer to whether or not

3434 ** a mutex is held. An internal mutex is held for a protected

3435 ** sqlite3_value object but no mutex is held for an unprotected

3436 ** sqlite3_value object. If SQLite is compiled to be single-threaded

3437 ** (with [SQLITE_THREADSAFE=0] and with [sqlite3_threadsafe()] returning 0)

3438 ** or if SQLite is run in one of reduced mutex modes

3439 ** [SQLITE_CONFIG_SINGLETHREAD] or [SQLITE_CONFIG_MULTITHREAD]

3440 ** then there is no distinction between protected and unprotected

3441 ** sqlite3_value objects and they can be used interchangeably. However,

3442 ** for maximum code portability it is recommended that applications

3443 ** still make the distinction between protected and unprotected

3444 ** sqlite3_value objects even when not strictly required.

3445 **

3446 ** ^The sqlite3_value objects that are passed as parameters into the

3447 ** implementation of [application-defined SQL functions] are protected.

3448 ** ^The sqlite3_value object returned by

3449 ** [sqlite3_column_value()] is unprotected.

3450 ** Unprotected sqlite3_value objects may only be used with

3451 ** [sqlite3_result_value()] and [sqlite3_bind_value()].

3452 ** The [sqlite3_value_blob \| sqlite3_value_type()] family of

3453 ** interfaces require protected sqlite3_value objects.

3454 */

3455 typedef struct Mem sqlite3_value;

3456

3457 /*

3458 ** CAPI3REF: SQL Function Context Object

3459 **

3460 ** The context in which an SQL function executes is stored in an

3461 ** sqlite3_context object. ^A pointer to an sqlite3_context object

3462 ** is always first parameter to [application-defined SQL functions].

3463 ** The application-defined SQL function implementation will pass this

3464 ** pointer through into calls to [sqlite3_result_int \| sqlite3_result()],

3465 ** [sqlite3_aggregate_context()], [sqlite3_user_data()],

3466 ** [sqlite3_context_db_handle()], [sqlite3_get_auxdata()],

3467 ** and/or [sqlite3_set_auxdata()].

3468 */

3469 typedef struct sqlite3_context sqlite3_context;

3470

3471 /*

3472 ** CAPI3REF: Binding Values To Prepared Statements

3473 ** KEYWORDS: {host parameter} {host parameters} {host parameter name}

3474 ** KEYWORDS: {SQL parameter} {SQL parameters} {parameter binding}

3475 ** METHOD: sqlite3_stmt

3476 **

3477 ** ^(In the SQL statement text input to [sqlite3_prepare_v2()] and its variants,

3478 ** literals may be replaced by a [parameter] that matches one of following

3479 ** templates:

3480 **

3481 ** <ul>

3482 ** <li> ?

3483 ** <li> ?NNN

3484 ** <li> :VVV

3485 ** <li> @VVV

3486 ** <li> $VVV

3487 ** </ul>

3488 **

3489 ** In the templates above, NNN represents an integer literal,

3490 ** and VVV represents an alphanumeric identifier.)^ ^The values of these

3491 ** parameters (also called "host parameter names" or "SQL parameters")

3492 ** can be set using the sqlite3_bind_*() routines defined here.

3493 **

3494 ** ^The first argument to the sqlite3_bind_*() routines is always

3495 ** a pointer to the [sqlite3_stmt] object returned from

3496 ** [sqlite3_prepare_v2()] or its variants.

3497 **

3498 ** ^The second argument is the index of the SQL parameter to be set.

3499 ** ^The leftmost SQL parameter has an index of 1. ^When the same named

3500 ** SQL parameter is used more than once, second and subsequent

3501 ** occurrences have the same index as the first occurrence.

3502 ** ^The index for named parameters can be looked up using the

3503 ** [sqlite3_bind_parameter_index()] API if desired. ^The index

3504 ** for "?NNN" parameters is the value of NNN.

3505 ** ^The NNN value must be between 1 and the [sqlite3_limit()]

3506 ** parameter [SQLITE_LIMIT_VARIABLE_NUMBER] (default value: 999).

3507 **

3508 ** ^The third argument is the value to bind to the parameter.

3509 ** ^If the third parameter to sqlite3_bind_text() or sqlite3_bind_text16()

3510 ** or sqlite3_bind_blob() is a NULL pointer then the fourth parameter

3511 ** is ignored and the end result is the same as sqlite3_bind_null().

3512 **

3513 ** ^(In those routines that have a fourth argument, its value is the

3514 ** number of bytes in the parameter. To be clear: the value is the

3515 ** number of <u>bytes</u> in the value, not the number of characters.)^

3516 ** ^If the fourth parameter to sqlite3_bind_text() or sqlite3_bind_text16()

3517 ** is negative, then the length of the string is

3518 ** the number of bytes up to the first zero terminator.

3519 ** If the fourth parameter to sqlite3_bind_blob() is negative, then

3520 ** the behavior is undefined.

3521 ** If a non-negative fourth parameter is provided to sqlite3_bind_text()

3522 ** or sqlite3_bind_text16() or sqlite3_bind_text64() then

3523 ** that parameter must be the byte offset

3524 ** where the NUL terminator would occur assuming the string were NUL

3525 ** terminated. If any NUL characters occur at byte offsets less than

3526 ** the value of the fourth parameter then the resulting string value will

3527 ** contain embedded NULs. The result of expressions involving strings

3528 ** with embedded NULs is undefined.

3529 **

3530 ** ^The fifth argument to the BLOB and string binding interfaces

3531 ** is a destructor used to dispose of the BLOB or

3532 ** string after SQLite has finished with it. ^The destructor is called

3533 ** to dispose of the BLOB or string even if the call to bind API fails.

3534 ** ^If the fifth argument is

3535 ** the special value [SQLITE_STATIC], then SQLite assumes that the

3536 ** information is in static, unmanaged space and does not need to be freed.

3537 ** ^If the fifth argument has the value [SQLITE_TRANSIENT], then

3538 ** SQLite makes its own private copy of the data immediately, before

3539 ** the sqlite3_bind_*() routine returns.

3540 **

3541 ** ^The sixth argument to sqlite3_bind_text64() must be one of

3542 ** [SQLITE_UTF8], [SQLITE_UTF16], [SQLITE_UTF16BE], or [SQLITE_UTF16LE]

3543 ** to specify the encoding of the text in the third parameter. If

3544 ** the sixth argument to sqlite3_bind_text64() is not one of the

3545 ** allowed values shown above, or if the text encoding is different

3546 ** from the encoding specified by the sixth parameter, then the behavior

3547 ** is undefined.

3548 **

3549 ** ^The sqlite3_bind_zeroblob() routine binds a BLOB of length N that

3550 ** is filled with zeroes. ^A zeroblob uses a fixed amount of memory

3551 ** (just an integer to hold its size) while it is being processed.

3552 ** Zeroblobs are intended to serve as placeholders for BLOBs whose

3553 ** content is later written using

3554 ** [sqlite3_blob_open \| incremental BLOB I/O] routines.

3555 ** ^A negative value for the zeroblob results in a zero-length BLOB.

3556 **

3557 ** ^If any of the sqlite3_bind_*() routines are called with a NULL pointer

3558 ** for the [prepared statement] or with a prepared statement for which

3559 ** [sqlite3_step()] has been called more recently than [sqlite3_reset()],

3560 ** then the call will return [SQLITE_MISUSE]. If any sqlite3_bind_()

3561 ** routine is passed a [prepared statement] that has been finalized, the

3562 ** result is undefined and probably harmful.

3563 **

3564 ** ^Bindings are not cleared by the [sqlite3_reset()] routine.

3565 ** ^Unbound parameters are interpreted as NULL.

3566 **

3567 ** ^The sqlite3_bind_* routines return [SQLITE_OK] on success or an

3568 ** [error code] if anything goes wrong.

3569 ** ^[SQLITE_TOOBIG] might be returned if the size of a string or BLOB

3570 ** exceeds limits imposed by [sqlite3_limit]([SQLITE_LIMIT_LENGTH]) or

3571 ** [SQLITE_MAX_LENGTH].

3572 ** ^[SQLITE_RANGE] is returned if the parameter

3573 ** index is out of range. ^[SQLITE_NOMEM] is returned if malloc() fails.

3574 **

3575 ** See also: [sqlite3_bind_parameter_count()],

3576 ** [sqlite3_bind_parameter_name()], and [sqlite3_bind_parameter_index()].

3577 */

3578 int sqlite3_bind_blob(sqlite3_stmt, int, const void, int n, void()(void));

3579 int sqlite3_bind_blob64(sqlite3_stmt, int, const void, sqlite3_uint64,

3580 void()(void));

3581 int sqlite3_bind_double(sqlite3_stmt*, int, double);

3582 int sqlite3_bind_int(sqlite3_stmt*, int, int);

3583 int sqlite3_bind_int64(sqlite3_stmt*, int, sqlite3_int64);

3584 int sqlite3_bind_null(sqlite3_stmt*, int);

3585 int sqlite3_bind_text(sqlite3_stmt,int,const char,int,void()(void));

3586 int sqlite3_bind_text16(sqlite3_stmt, int, const void, int, void()(void));

3587 int sqlite3_bind_text64(sqlite3_stmt, int, const char, sqlite3_uint64,

3588 void()(void), unsigned char encoding);

3589 int sqlite3_bind_value(sqlite3_stmt, int, const sqlite3_value);

3590 int sqlite3_bind_zeroblob(sqlite3_stmt*, int, int n);

3591 int sqlite3_bind_zeroblob64(sqlite3_stmt*, int, sqlite3_uint64);

3592

3593 /*

3594 ** CAPI3REF: Number Of SQL Parameters

3595 ** METHOD: sqlite3_stmt

3596 **

3597 ** ^This routine can be used to find the number of [SQL parameters]

3598 ** in a [prepared statement]. SQL parameters are tokens of the

3599 ** form "?", "?NNN", ":AAA", "$AAA", or "@AAA" that serve as

3600 ** placeholders for values that are [sqlite3_bind_blob \| bound]

3601 ** to the parameters at a later time.

3602 **

3603 ** ^(This routine actually returns the index of the largest (rightmost)

3604 ** parameter. For all forms except ?NNN, this will correspond to the

3605 ** number of unique parameters. If parameters of the ?NNN form are used,

3606 ** there may be gaps in the list.)^

3607 **

3608 ** See also: [sqlite3_bind_blob\|sqlite3_bind()],

3609 ** [sqlite3_bind_parameter_name()], and

3610 ** [sqlite3_bind_parameter_index()].

3611 */

3612 int sqlite3_bind_parameter_count(sqlite3_stmt*);

3613

3614 /*

3615 ** CAPI3REF: Name Of A Host Parameter

3616 ** METHOD: sqlite3_stmt

3617 **

3618 ** ^The sqlite3_bind_parameter_name(P,N) interface returns

3619 ** the name of the N-th [SQL parameter] in the [prepared statement] P.

3620 ** ^(SQL parameters of the form "?NNN" or ":AAA" or "@AAA" or "$AAA"

3621 ** have a name which is the string "?NNN" or ":AAA" or "@AAA" or "$AAA"

3622 ** respectively.

3623 ** In other words, the initial ":" or "$" or "@" or "?"

3624 ** is included as part of the name.)^

3625 ** ^Parameters of the form "?" without a following integer have no name

3626 ** and are referred to as "nameless" or "anonymous parameters".

3627 **

3628 ** ^The first host parameter has an index of 1, not 0.

3629 **

3630 ** ^If the value N is out of range or if the N-th parameter is

3631 ** nameless, then NULL is returned. ^The returned string is

3632 ** always in UTF-8 encoding even if the named parameter was

3633 ** originally specified as UTF-16 in [sqlite3_prepare16()] or

3634 ** [sqlite3_prepare16_v2()].

3635 **

3636 ** See also: [sqlite3_bind_blob\|sqlite3_bind()],

3637 ** [sqlite3_bind_parameter_count()], and

3638 ** [sqlite3_bind_parameter_index()].

3639 */

3640 const char sqlite3_bind_parameter_name(sqlite3_stmt, int);

3641

3642 /*

3643 ** CAPI3REF: Index Of A Parameter With A Given Name

3644 ** METHOD: sqlite3_stmt

3645 **

3646 ** ^Return the index of an SQL parameter given its name. ^The

3647 ** index value returned is suitable for use as the second

3648 ** parameter to [sqlite3_bind_blob\|sqlite3_bind()]. ^A zero

3649 ** is returned if no matching parameter is found. ^The parameter

3650 ** name must be given in UTF-8 even if the original statement

3651 ** was prepared from UTF-16 text using [sqlite3_prepare16_v2()].

3652 **

3653 ** See also: [sqlite3_bind_blob\|sqlite3_bind()],

3654 ** [sqlite3_bind_parameter_count()], and

3655 ** [sqlite3_bind_parameter_name()].

3656 */

3657 int sqlite3_bind_parameter_index(sqlite3_stmt, const char zName);

3658

3659 /*

3660 ** CAPI3REF: Reset All Bindings On A Prepared Statement

3661 ** METHOD: sqlite3_stmt

3662 **

3663 ** ^Contrary to the intuition of many, [sqlite3_reset()] does not reset

3664 ** the [sqlite3_bind_blob \| bindings] on a [prepared statement].

3665 ** ^Use this routine to reset all host parameters to NULL.

3666 */

3667 int sqlite3_clear_bindings(sqlite3_stmt*);

3668

3669 /*

3670 ** CAPI3REF: Number Of Columns In A Result Set

3671 ** METHOD: sqlite3_stmt

3672 **

3673 ** ^Return the number of columns in the result set returned by the

3674 ** [prepared statement]. ^This routine returns 0 if pStmt is an SQL

3675 ** statement that does not return data (for example an [UPDATE]).

3676 **

3677 ** See also: [sqlite3_data_count()]

3678 */

3679 int sqlite3_column_count(sqlite3_stmt *pStmt);

3680

3681 /*

3682 ** CAPI3REF: Column Names In A Result Set

3683 ** METHOD: sqlite3_stmt

3684 **

3685 ** ^These routines return the name assigned to a particular column

3686 ** in the result set of a [SELECT] statement. ^The sqlite3_column_name()

3687 ** interface returns a pointer to a zero-terminated UTF-8 string

3688 ** and sqlite3_column_name16() returns a pointer to a zero-terminated

3689 ** UTF-16 string. ^The first parameter is the [prepared statement]

3690 ** that implements the [SELECT] statement. ^The second parameter is the

3691 ** column number. ^The leftmost column is number 0.

3692 **

3693 ** ^The returned string pointer is valid until either the [prepared statement]

3694 ** is destroyed by [sqlite3_finalize()] or until the statement is automatically

3695 ** reprepared by the first call to [sqlite3_step()] for a particular run

3696 ** or until the next call to

3697 ** sqlite3_column_name() or sqlite3_column_name16() on the same column.

3698 **

3699 ** ^If sqlite3_malloc() fails during the processing of either routine

3700 ** (for example during a conversion from UTF-8 to UTF-16) then a

3701 ** NULL pointer is returned.

3702 **

3703 ** ^The name of a result column is the value of the "AS" clause for

3704 ** that column, if there is an AS clause. If there is no AS clause

3705 ** then the name of the column is unspecified and may change from

3706 ** one release of SQLite to the next.

3707 */

3708 const char sqlite3_column_name(sqlite3_stmt, int N);

3709 const void sqlite3_column_name16(sqlite3_stmt, int N);

3710

3711 /*

3712 ** CAPI3REF: Source Of Data In A Query Result

3713 ** METHOD: sqlite3_stmt

3714 **

3715 ** ^These routines provide a means to determine the database, table, and

3716 ** table column that is the origin of a particular result column in

3717 ** [SELECT] statement.

3718 ** ^The name of the database or table or column can be returned as

3719 ** either a UTF-8 or UTF-16 string. ^The _database_ routines return

3720 ** the database name, the _table_ routines return the table name, and

3721 ** the origin_ routines return the column name.

3722 ** ^The returned string is valid until the [prepared statement] is destroyed

3723 ** using [sqlite3_finalize()] or until the statement is automatically

3724 ** reprepared by the first call to [sqlite3_step()] for a particular run

3725 ** or until the same information is requested

3726 ** again in a different encoding.

3727 **

3728 ** ^The names returned are the original un-aliased names of the

3729 ** database, table, and column.

3730 **

3731 ** ^The first argument to these interfaces is a [prepared statement].

3732 ** ^These functions return information about the Nth result column returned by

3733 ** the statement, where N is the second function argument.

3734 ** ^The left-most column is column 0 for these routines.

3735 **

3736 ** ^If the Nth column returned by the statement is an expression or

3737 ** subquery and is not a column value, then all of these functions return

3738 ** NULL. ^These routine might also return NULL if a memory allocation error

3739 ** occurs. ^Otherwise, they return the name of the attached database, table,

3740 ** or column that query result column was extracted from.

3741 **

3742 ** ^As with all other SQLite APIs, those whose names end with "16" return

3743 ** UTF-16 encoded strings and the other functions return UTF-8.

3744 **

3745 ** ^These APIs are only available if the library was compiled with the

3746 ** [SQLITE_ENABLE_COLUMN_METADATA] C-preprocessor symbol.

3747 **

3748 ** If two or more threads call one or more of these routines against the same

3749 ** prepared statement and column at the same time then the results are

3750 ** undefined.

3751 **

3752 ** If two or more threads call one or more

3753 ** [sqlite3_column_database_name \| column metadata interfaces]

3754 ** for the same [prepared statement] and result column

3755 ** at the same time then the results are undefined.

3756 */

3757 const char sqlite3_column_database_name(sqlite3_stmt,int);

3758 const void sqlite3_column_database_name16(sqlite3_stmt,int);

3759 const char sqlite3_column_table_name(sqlite3_stmt,int);

3760 const void sqlite3_column_table_name16(sqlite3_stmt,int);

3761 const char sqlite3_column_origin_name(sqlite3_stmt,int);

3762 const void sqlite3_column_origin_name16(sqlite3_stmt,int);

3763

3764 /*

3765 ** CAPI3REF: Declared Datatype Of A Query Result

3766 ** METHOD: sqlite3_stmt

3767 **

3768 ** ^(The first parameter is a [prepared statement].

3769 ** If this statement is a [SELECT] statement and the Nth column of the

3770 ** returned result set of that [SELECT] is a table column (not an

3771 ** expression or subquery) then the declared type of the table

3772 ** column is returned.)^ ^If the Nth column of the result set is an

3773 ** expression or subquery, then a NULL pointer is returned.

3774 ** ^The returned string is always UTF-8 encoded.

3775 **

3776 ** ^(For example, given the database schema:

3777 **

3778 ** CREATE TABLE t1(c1 VARIANT);

3779 **

3780 ** and the following statement to be compiled:

3781 **

3782 ** SELECT c1 + 1, c1 FROM t1;

3783 **

3784 ** this routine would return the string "VARIANT" for the second result

3785 ** column (i==1), and a NULL pointer for the first result column (i==0).)^

3786 **

3787 ** ^SQLite uses dynamic run-time typing. ^So just because a column

3788 ** is declared to contain a particular type does not mean that the

3789 ** data stored in that column is of the declared type. SQLite is

3790 ** strongly typed, but the typing is dynamic not static. ^Type

3791 ** is associated with individual values, not with the containers

3792 ** used to hold those values.

3793 */

3794 const char sqlite3_column_decltype(sqlite3_stmt,int);

3795 const void sqlite3_column_decltype16(sqlite3_stmt,int);

3796

3797 /*

3798 ** CAPI3REF: Evaluate An SQL Statement

3799 ** METHOD: sqlite3_stmt

3800 **

3801 ** After a [prepared statement] has been prepared using either

3802 ** [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()] or one of the legacy

3803 ** interfaces [sqlite3_prepare()] or [sqlite3_prepare16()], this function

3804 ** must be called one or more times to evaluate the statement.

3805 **

3806 ** The details of the behavior of the sqlite3_step() interface depend

3807 ** on whether the statement was prepared using the newer "v2" interface

3808 ** [sqlite3_prepare_v2()] and [sqlite3_prepare16_v2()] or the older legacy

3809 ** interface [sqlite3_prepare()] and [sqlite3_prepare16()]. The use of the

3810 ** new "v2" interface is recommended for new applications but the legacy

3811 ** interface will continue to be supported.

3812 **

3813 ** ^In the legacy interface, the return value will be either [SQLITE_BUSY],

3814 ** [SQLITE_DONE], [SQLITE_ROW], [SQLITE_ERROR], or [SQLITE_MISUSE].

3815 ** ^With the "v2" interface, any of the other [result codes] or

3816 ** [extended result codes] might be returned as well.

3817 **

3818 ** ^[SQLITE_BUSY] means that the database engine was unable to acquire the

3819 ** database locks it needs to do its job. ^If the statement is a [COMMIT]

3820 ** or occurs outside of an explicit transaction, then you can retry the

3821 ** statement. If the statement is not a [COMMIT] and occurs within an

3822 ** explicit transaction then you should rollback the transaction before

3823 ** continuing.

3824 **

3825 ** ^[SQLITE_DONE] means that the statement has finished executing

3826 ** successfully. sqlite3_step() should not be called again on this virtual

3827 ** machine without first calling [sqlite3_reset()] to reset the virtual

3828 ** machine back to its initial state.

3829 **

3830 ** ^If the SQL statement being executed returns any data, then [SQLITE_ROW]

3831 ** is returned each time a new row of data is ready for processing by the

3832 ** caller. The values may be accessed using the [column access functions].

3833 ** sqlite3_step() is called again to retrieve the next row of data.

3834 **

3835 ** ^[SQLITE_ERROR] means that a run-time error (such as a constraint

3836 ** violation) has occurred. sqlite3_step() should not be called again on

3837 ** the VM. More information may be found by calling [sqlite3_errmsg()].

3838 ** ^With the legacy interface, a more specific error code (for example,

3839 ** [SQLITE_INTERRUPT], [SQLITE_SCHEMA], [SQLITE_CORRUPT], and so forth)

3840 ** can be obtained by calling [sqlite3_reset()] on the

3841 ** [prepared statement]. ^In the "v2" interface,

3842 ** the more specific error code is returned directly by sqlite3_step().

3843 **

3844 ** [SQLITE_MISUSE] means that the this routine was called inappropriately.

3845 ** Perhaps it was called on a [prepared statement] that has

3846 ** already been [sqlite3_finalize \| finalized] or on one that had

3847 ** previously returned [SQLITE_ERROR] or [SQLITE_DONE]. Or it could

3848 ** be the case that the same database connection is being used by two or

3849 ** more threads at the same moment in time.

3850 **

3851 ** For all versions of SQLite up to and including 3.6.23.1, a call to

3852 ** [sqlite3_reset()] was required after sqlite3_step() returned anything

3853 ** other than [SQLITE_ROW] before any subsequent invocation of

3854 ** sqlite3_step(). Failure to reset the prepared statement using

3855 ** [sqlite3_reset()] would result in an [SQLITE_MISUSE] return from

3856 ** sqlite3_step(). But after version 3.6.23.1, sqlite3_step() began

3857 ** calling [sqlite3_reset()] automatically in this circumstance rather

3858 ** than returning [SQLITE_MISUSE]. This is not considered a compatibility

3859 ** break because any application that ever receives an SQLITE_MISUSE error

3860 ** is broken by definition. The [SQLITE_OMIT_AUTORESET] compile-time option

3861 ** can be used to restore the legacy behavior.

3862 **

3863 ** <b>Goofy Interface Alert:</b> In the legacy interface, the sqlite3_step()

3864 ** API always returns a generic error code, [SQLITE_ERROR], following any

3865 ** error other than [SQLITE_BUSY] and [SQLITE_MISUSE]. You must call

3866 ** [sqlite3_reset()] or [sqlite3_finalize()] in order to find one of the

3867 ** specific [error codes] that better describes the error.

3868 ** We admit that this is a goofy design. The problem has been fixed

3869 ** with the "v2" interface. If you prepare all of your SQL statements

3870 ** using either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()] instead

3871 ** of the legacy [sqlite3_prepare()] and [sqlite3_prepare16()] interfaces,

3872 ** then the more specific [error codes] are returned directly

3873 ** by sqlite3_step(). The use of the "v2" interface is recommended.

3874 */

3875 int sqlite3_step(sqlite3_stmt*);

3876

3877 /*

3878 ** CAPI3REF: Number of columns in a result set

3879 ** METHOD: sqlite3_stmt

3880 **

3881 ** ^The sqlite3_data_count(P) interface returns the number of columns in the

3882 ** current row of the result set of [prepared statement] P.

3883 ** ^If prepared statement P does not have results ready to return

3884 ** (via calls to the [sqlite3_column_int \| sqlite3_column_*()] of

3885 ** interfaces) then sqlite3_data_count(P) returns 0.

3886 ** ^The sqlite3_data_count(P) routine also returns 0 if P is a NULL pointer.

3887 ** ^The sqlite3_data_count(P) routine returns 0 if the previous call to

3888 ** [sqlite3_step](P) returned [SQLITE_DONE]. ^The sqlite3_data_count(P)

3889 ** will return non-zero if previous call to [sqlite3_step](P) returned

3890 ** [SQLITE_ROW], except in the case of the [PRAGMA incremental_vacuum]

3891 ** where it always returns zero since each step of that multi-step

3892 ** pragma returns 0 columns of data.

3893 **

3894 ** See also: [sqlite3_column_count()]

3895 */

3896 int sqlite3_data_count(sqlite3_stmt *pStmt);

3897

3898 /*

3899 ** CAPI3REF: Fundamental Datatypes

3900 ** KEYWORDS: SQLITE_TEXT

3901 **

3902 ** ^(Every value in SQLite has one of five fundamental datatypes:

3903 **

3904 ** <ul>

3905 ** <li> 64-bit signed integer

3906 ** <li> 64-bit IEEE floating point number

3907 ** <li> string

3908 ** <li> BLOB

3909 ** <li> NULL

3910 ** </ul>)^

3911 **

3912 ** These constants are codes for each of those types.

3913 **

3914 ** Note that the SQLITE_TEXT constant was also used in SQLite version 2

3915 ** for a completely different meaning. Software that links against both

3916 ** SQLite version 2 and SQLite version 3 should use SQLITE3_TEXT, not

3917 ** SQLITE_TEXT.

3918 */

3919 #define SQLITE_INTEGER 1

3920 #define SQLITE_FLOAT 2

3921 #define SQLITE_BLOB 4

3922 #define SQLITE_NULL 5

3923 #ifdef SQLITE_TEXT

3924 # undef SQLITE_TEXT

3925 #else

3926 # define SQLITE_TEXT 3

3927 #endif

3928 #define SQLITE3_TEXT 3

3929

3930 /*

3931 ** CAPI3REF: Result Values From A Query

3932 ** KEYWORDS: {column access functions}

3933 ** METHOD: sqlite3_stmt

3934 **

3935 ** ^These routines return information about a single column of the current

3936 ** result row of a query. ^In every case the first argument is a pointer

3937 ** to the [prepared statement] that is being evaluated (the [sqlite3_stmt*]

3938 ** that was returned from [sqlite3_prepare_v2()] or one of its variants)

3939 ** and the second argument is the index of the column for which information

3940 ** should be returned. ^The leftmost column of the result set has the index 0.

3941 ** ^The number of columns in the result can be determined using

3942 ** [sqlite3_column_count()].

3943 **

3944 ** If the SQL statement does not currently point to a valid row, or if the

3945 ** column index is out of range, the result is undefined.

3946 ** These routines may only be called when the most recent call to

3947 ** [sqlite3_step()] has returned [SQLITE_ROW] and neither

3948 ** [sqlite3_reset()] nor [sqlite3_finalize()] have been called subsequently.

3949 ** If any of these routines are called after [sqlite3_reset()] or

3950 ** [sqlite3_finalize()] or after [sqlite3_step()] has returned

3951 ** something other than [SQLITE_ROW], the results are undefined.

3952 ** If [sqlite3_step()] or [sqlite3_reset()] or [sqlite3_finalize()]

3953 ** are called from a different thread while any of these routines

3954 ** are pending, then the results are undefined.

3955 **

3956 ** ^The sqlite3_column_type() routine returns the

3957 ** [SQLITE_INTEGER \| datatype code] for the initial data type

3958 ** of the result column. ^The returned value is one of [SQLITE_INTEGER],

3959 ** [SQLITE_FLOAT], [SQLITE_TEXT], [SQLITE_BLOB], or [SQLITE_NULL]. The value

3960 ** returned by sqlite3_column_type() is only meaningful if no type

3961 ** conversions have occurred as described below. After a type conversion,

3962 ** the value returned by sqlite3_column_type() is undefined. Future

3963 ** versions of SQLite may change the behavior of sqlite3_column_type()

3964 ** following a type conversion.

3965 **

3966 ** ^If the result is a BLOB or UTF-8 string then the sqlite3_column_bytes()

3967 ** routine returns the number of bytes in that BLOB or string.

3968 ** ^If the result is a UTF-16 string, then sqlite3_column_bytes() converts

3969 ** the string to UTF-8 and then returns the number of bytes.

3970 ** ^If the result is a numeric value then sqlite3_column_bytes() uses

3971 ** [sqlite3_snprintf()] to convert that value to a UTF-8 string and returns

3972 ** the number of bytes in that string.

3973 ** ^If the result is NULL, then sqlite3_column_bytes() returns zero.

3974 **

3975 ** ^If the result is a BLOB or UTF-16 string then the sqlite3_column_bytes16()

3976 ** routine returns the number of bytes in that BLOB or string.

3977 ** ^If the result is a UTF-8 string, then sqlite3_column_bytes16() converts

3978 ** the string to UTF-16 and then returns the number of bytes.

3979 ** ^If the result is a numeric value then sqlite3_column_bytes16() uses

3980 ** [sqlite3_snprintf()] to convert that value to a UTF-16 string and returns

3981 ** the number of bytes in that string.

3982 ** ^If the result is NULL, then sqlite3_column_bytes16() returns zero.

3983 **

3984 ** ^The values returned by [sqlite3_column_bytes()] and

3985 ** [sqlite3_column_bytes16()] do not include the zero terminators at the end

3986 ** of the string. ^For clarity: the values returned by

3987 ** [sqlite3_column_bytes()] and [sqlite3_column_bytes16()] are the number of

3988 ** bytes in the string, not the number of characters.

3989 **

3990 ** ^Strings returned by sqlite3_column_text() and sqlite3_column_text16(),

3991 ** even empty strings, are always zero-terminated. ^The return

3992 ** value from sqlite3_column_blob() for a zero-length BLOB is a NULL pointer.

3993 **

3994 ** <b>Warning:</b> ^The object returned by [sqlite3_column_value()] is an

3995 ** [unprotected sqlite3_value] object. In a multithreaded environment,

3996 ** an unprotected sqlite3_value object may only be used safely with

3997 ** [sqlite3_bind_value()] and [sqlite3_result_value()].

3998 ** If the [unprotected sqlite3_value] object returned by

3999 ** [sqlite3_column_value()] is used in any other way, including calls

4000 ** to routines like [sqlite3_value_int()], [sqlite3_value_text()],

4001 ** or [sqlite3_value_bytes()], the behavior is not threadsafe.

4002 **

4003 ** These routines attempt to convert the value where appropriate. ^For

4004 ** example, if the internal representation is FLOAT and a text result

4005 ** is requested, [sqlite3_snprintf()] is used internally to perform the

4006 ** conversion automatically. ^(The following table details the conversions

4007 ** that are applied:

4008 **

4009 ** <blockquote>

4010 ** <table border="1">

4011 ** <tr><th> Internal<br>Type <th> Requested<br>Type <th> Conversion

4012 **

4013 ** <tr><td> NULL <td> INTEGER <td> Result is 0

4014 ** <tr><td> NULL <td> FLOAT <td> Result is 0.0

4015 ** <tr><td> NULL <td> TEXT <td> Result is a NULL pointer

4016 ** <tr><td> NULL <td> BLOB <td> Result is a NULL pointer

4017 ** <tr><td> INTEGER <td> FLOAT <td> Convert from integer to float

4018 ** <tr><td> INTEGER <td> TEXT <td> ASCII rendering of the integer

4019 ** <tr><td> INTEGER <td> BLOB <td> Same as INTEGER->TEXT

4020 ** <tr><td> FLOAT <td> INTEGER <td> [CAST] to INTEGER

4021 ** <tr><td> FLOAT <td> TEXT <td> ASCII rendering of the float

4022 ** <tr><td> FLOAT <td> BLOB <td> [CAST] to BLOB

4023 ** <tr><td> TEXT <td> INTEGER <td> [CAST] to INTEGER

4024 ** <tr><td> TEXT <td> FLOAT <td> [CAST] to REAL

4025 ** <tr><td> TEXT <td> BLOB <td> No change

4026 ** <tr><td> BLOB <td> INTEGER <td> [CAST] to INTEGER

4027 ** <tr><td> BLOB <td> FLOAT <td> [CAST] to REAL

4028 ** <tr><td> BLOB <td> TEXT <td> Add a zero terminator if needed

4029 ** </table>

4030 ** </blockquote>)^

4031 **

4032 ** Note that when type conversions occur, pointers returned by prior

4033 ** calls to sqlite3_column_blob(), sqlite3_column_text(), and/or

4034 ** sqlite3_column_text16() may be invalidated.

4035 ** Type conversions and pointer invalidations might occur

4036 ** in the following cases:

4037 **

4038 ** <ul>

4039 ** <li> The initial content is a BLOB and sqlite3_column_text() or

4040 ** sqlite3_column_text16() is called. A zero-terminator might

4041 ** need to be added to the string.</li>

4042 ** <li> The initial content is UTF-8 text and sqlite3_column_bytes16() or

4043 ** sqlite3_column_text16() is called. The content must be converted

4044 ** to UTF-16.</li>

4045 ** <li> The initial content is UTF-16 text and sqlite3_column_bytes() or

4046 ** sqlite3_column_text() is called. The content must be converted

4047 ** to UTF-8.</li>

4048 ** </ul>

4049 **

4050 ** ^Conversions between UTF-16be and UTF-16le are always done in place and do

4051 ** not invalidate a prior pointer, though of course the content of the buffer

4052 ** that the prior pointer references will have been modified. Other kinds

4053 ** of conversion are done in place when it is possible, but sometimes they

4054 ** are not possible and in those cases prior pointers are invalidated.

4055 **

4056 ** The safest policy is to invoke these routines

4057 ** in one of the following ways:

4058 **

4059 ** <ul>

4060 ** <li>sqlite3_column_text() followed by sqlite3_column_bytes()</li>

4061 ** <li>sqlite3_column_blob() followed by sqlite3_column_bytes()</li>

4062 ** <li>sqlite3_column_text16() followed by sqlite3_column_bytes16()</li>

4063 ** </ul>

4064 **

4065 ** In other words, you should call sqlite3_column_text(),

4066 ** sqlite3_column_blob(), or sqlite3_column_text16() first to force the result

4067 ** into the desired format, then invoke sqlite3_column_bytes() or

4068 ** sqlite3_column_bytes16() to find the size of the result. Do not mix calls

4069 ** to sqlite3_column_text() or sqlite3_column_blob() with calls to

4070 ** sqlite3_column_bytes16(), and do not mix calls to sqlite3_column_text16()

4071 ** with calls to sqlite3_column_bytes().

4072 **

4073 ** ^The pointers returned are valid until a type conversion occurs as

4074 ** described above, or until [sqlite3_step()] or [sqlite3_reset()] or

4075 ** [sqlite3_finalize()] is called. ^The memory space used to hold strings

4076 ** and BLOBs is freed automatically. Do <em>not</em> pass the pointers returned

4077 ** from [sqlite3_column_blob()], [sqlite3_column_text()], etc. into

4078 ** [sqlite3_free()].

4079 **

4080 ** ^(If a memory allocation error occurs during the evaluation of any

4081 ** of these routines, a default value is returned. The default value

4082 ** is either the integer 0, the floating point number 0.0, or a NULL

4083 ** pointer. Subsequent calls to [sqlite3_errcode()] will return

4084 ** [SQLITE_NOMEM].)^

4085 */

4086 const void sqlite3_column_blob(sqlite3_stmt, int iCol);

4087 int sqlite3_column_bytes(sqlite3_stmt*, int iCol);

4088 int sqlite3_column_bytes16(sqlite3_stmt*, int iCol);

4089 double sqlite3_column_double(sqlite3_stmt*, int iCol);

4090 int sqlite3_column_int(sqlite3_stmt*, int iCol);

4091 sqlite3_int64 sqlite3_column_int64(sqlite3_stmt*, int iCol);

4092 const unsigned char sqlite3_column_text(sqlite3_stmt, int iCol);

4093 const void sqlite3_column_text16(sqlite3_stmt, int iCol);

4094 int sqlite3_column_type(sqlite3_stmt*, int iCol);

4095 sqlite3_value sqlite3_column_value(sqlite3_stmt, int iCol);

4096

4097 /*

4098 ** CAPI3REF: Destroy A Prepared Statement Object

4099 ** DESTRUCTOR: sqlite3_stmt

4100 **

4101 ** ^The sqlite3_finalize() function is called to delete a [prepared statement].

4102 ** ^If the most recent evaluation of the statement encountered no errors

4103 ** or if the statement is never been evaluated, then sqlite3_finalize() returns

4104 ** SQLITE_OK. ^If the most recent evaluation of statement S failed, then

4105 ** sqlite3_finalize(S) returns the appropriate [error code] or

4106 ** [extended error code].

4107 **

4108 ** ^The sqlite3_finalize(S) routine can be called at any point during

4109 ** the life cycle of [prepared statement] S:

4110 ** before statement S is ever evaluated, after

4111 ** one or more calls to [sqlite3_reset()], or after any call

4112 ** to [sqlite3_step()] regardless of whether or not the statement has

4113 ** completed execution.

4114 **

4115 ** ^Invoking sqlite3_finalize() on a NULL pointer is a harmless no-op.

4116 **

4117 ** The application must finalize every [prepared statement] in order to avoid

4118 ** resource leaks. It is a grievous error for the application to try to use

4119 ** a prepared statement after it has been finalized. Any use of a prepared

4120 ** statement after it has been finalized can result in undefined and

4121 ** undesirable behavior such as segfaults and heap corruption.

4122 */

4123 int sqlite3_finalize(sqlite3_stmt *pStmt);

4124

4125 /*

4126 ** CAPI3REF: Reset A Prepared Statement Object

4127 ** METHOD: sqlite3_stmt

4128 **

4129 ** The sqlite3_reset() function is called to reset a [prepared statement]

4130 ** object back to its initial state, ready to be re-executed.

4131 ** ^Any SQL statement variables that had values bound to them using

4132 ** the [sqlite3_bind_blob \| sqlite3_bind_*() API] retain their values.

4133 ** Use [sqlite3_clear_bindings()] to reset the bindings.

4134 **

4135 ** ^The [sqlite3_reset(S)] interface resets the [prepared statement] S

4136 ** back to the beginning of its program.

4137 **

4138 ** ^If the most recent call to [sqlite3_step(S)] for the

4139 ** [prepared statement] S returned [SQLITE_ROW] or [SQLITE_DONE],

4140 ** or if [sqlite3_step(S)] has never before been called on S,

4141 ** then [sqlite3_reset(S)] returns [SQLITE_OK].

4142 **

4143 ** ^If the most recent call to [sqlite3_step(S)] for the

4144 ** [prepared statement] S indicated an error, then

4145 ** [sqlite3_reset(S)] returns an appropriate [error code].

4146 **

4147 ** ^The [sqlite3_reset(S)] interface does not change the values

4148 ** of any [sqlite3_bind_blob\|bindings] on the [prepared statement] S.

4149 */

4150 int sqlite3_reset(sqlite3_stmt *pStmt);

4151

4152 /*

4153 ** CAPI3REF: Create Or Redefine SQL Functions

4154 ** KEYWORDS: {function creation routines}

4155 ** KEYWORDS: {application-defined SQL function}

4156 ** KEYWORDS: {application-defined SQL functions}

4157 ** METHOD: sqlite3

4158 **

4159 ** ^These functions (collectively known as "function creation routines")

4160 ** are used to add SQL functions or aggregates or to redefine the behavior

4161 ** of existing SQL functions or aggregates. The only differences between

4162 ** these routines are the text encoding expected for

4163 ** the second parameter (the name of the function being created)

4164 ** and the presence or absence of a destructor callback for

4165 ** the application data pointer.

4166 **

4167 ** ^The first parameter is the [database connection] to which the SQL

4168 ** function is to be added. ^If an application uses more than one database

4169 ** connection then application-defined SQL functions must be added

4170 ** to each database connection separately.

4171 **

4172 ** ^The second parameter is the name of the SQL function to be created or

4173 ** redefined. ^The length of the name is limited to 255 bytes in a UTF-8

4174 ** representation, exclusive of the zero-terminator. ^Note that the name

4175 ** length limit is in UTF-8 bytes, not characters nor UTF-16 bytes.

4176 ** ^Any attempt to create a function with a longer name

4177 ** will result in [SQLITE_MISUSE] being returned.

4178 **

4179 ** ^The third parameter (nArg)

4180 ** is the number of arguments that the SQL function or

4181 ** aggregate takes. ^If this parameter is -1, then the SQL function or

4182 ** aggregate may take any number of arguments between 0 and the limit

4183 ** set by [sqlite3_limit]([SQLITE_LIMIT_FUNCTION_ARG]). If the third

4184 ** parameter is less than -1 or greater than 127 then the behavior is

4185 ** undefined.

4186 **

4187 ** ^The fourth parameter, eTextRep, specifies what

4188 ** [SQLITE_UTF8 \| text encoding] this SQL function prefers for

4189 ** its parameters. The application should set this parameter to

4190 ** [SQLITE_UTF16LE] if the function implementation invokes

4191 ** [sqlite3_value_text16le()] on an input, or [SQLITE_UTF16BE] if the

4192 ** implementation invokes [sqlite3_value_text16be()] on an input, or

4193 ** [SQLITE_UTF16] if [sqlite3_value_text16()] is used, or [SQLITE_UTF8]

4194 ** otherwise. ^The same SQL function may be registered multiple times using

4195 ** different preferred text encodings, with different implementations for

4196 ** each encoding.

4197 ** ^When multiple implementations of the same function are available, SQLite

4198 ** will pick the one that involves the least amount of data conversion.

4199 **

4200 ** ^The fourth parameter may optionally be ORed with [SQLITE_DETERMINISTIC]

4201 ** to signal that the function will always return the same result given

4202 ** the same inputs within a single SQL statement. Most SQL functions are

4203 ** deterministic. The built-in [random()] SQL function is an example of a

4204 ** function that is not deterministic. The SQLite query planner is able to

4205 ** perform additional optimizations on deterministic functions, so use

4206 ** of the [SQLITE_DETERMINISTIC] flag is recommended where possible.

4207 **

4208 ** ^(The fifth parameter is an arbitrary pointer. The implementation of the

4209 ** function can gain access to this pointer using [sqlite3_user_data()].)^

4210 **

4211 ** ^The sixth, seventh and eighth parameters, xFunc, xStep and xFinal, are

4212 ** pointers to C-language functions that implement the SQL function or

4213 ** aggregate. ^A scalar SQL function requires an implementation of the xFunc

4214 ** callback only; NULL pointers must be passed as the xStep and xFinal

4215 ** parameters. ^An aggregate SQL function requires an implementation of xStep

4216 ** and xFinal and NULL pointer must be passed for xFunc. ^To delete an existing

4217 ** SQL function or aggregate, pass NULL pointers for all three function

4218 ** callbacks.

4219 **

4220 ** ^(If the ninth parameter to sqlite3_create_function_v2() is not NULL,

4221 ** then it is destructor for the application data pointer.

4222 ** The destructor is invoked when the function is deleted, either by being

4223 ** overloaded or when the database connection closes.)^

4224 ** ^The destructor is also invoked if the call to

4225 ** sqlite3_create_function_v2() fails.

4226 ** ^When the destructor callback of the tenth parameter is invoked, it

4227 ** is passed a single argument which is a copy of the application data

4228 ** pointer which was the fifth parameter to sqlite3_create_function_v2().

4229 **

4230 ** ^It is permitted to register multiple implementations of the same

4231 ** functions with the same name but with either differing numbers of

4232 ** arguments or differing preferred text encodings. ^SQLite will use

4233 ** the implementation that most closely matches the way in which the

4234 ** SQL function is used. ^A function implementation with a non-negative

4235 ** nArg parameter is a better match than a function implementation with

4236 ** a negative nArg. ^A function where the preferred text encoding

4237 ** matches the database encoding is a better

4238 ** match than a function where the encoding is different.

4239 ** ^A function where the encoding difference is between UTF16le and UTF16be

4240 ** is a closer match than a function where the encoding difference is

4241 ** between UTF8 and UTF16.

4242 **

4243 ** ^Built-in functions may be overloaded by new application-defined functions.

4244 **

4245 ** ^An application-defined function is permitted to call other

4246 ** SQLite interfaces. However, such calls must not

4247 ** close the database connection nor finalize or reset the prepared

4248 ** statement in which the function is running.

4249 */

4250 int sqlite3_create_function(

4251 sqlite3 *db,

4252 const char *zFunctionName,

4253 int nArg,

4254 int eTextRep,

4255 void *pApp,

4256 void (xFunc)(sqlite3_context,int,sqlite3_value**),

4257 void (xStep)(sqlite3_context,int,sqlite3_value**),

4258 void (xFinal)(sqlite3_context)

4259 );

4260 int sqlite3_create_function16(

4261 sqlite3 *db,

4262 const void *zFunctionName,

4263 int nArg,

4264 int eTextRep,

4265 void *pApp,

4266 void (xFunc)(sqlite3_context,int,sqlite3_value**),

4267 void (xStep)(sqlite3_context,int,sqlite3_value**),

4268 void (xFinal)(sqlite3_context)

4269 );

4270 int sqlite3_create_function_v2(

4271 sqlite3 *db,

4272 const char *zFunctionName,

4273 int nArg,

4274 int eTextRep,

4275 void *pApp,

4276 void (xFunc)(sqlite3_context,int,sqlite3_value**),

4277 void (xStep)(sqlite3_context,int,sqlite3_value**),

4278 void (xFinal)(sqlite3_context),

4279 void(xDestroy)(void)

4280 );

4281

4282 /*

4283 ** CAPI3REF: Text Encodings

4284 **

4285 ** These constant define integer codes that represent the various

4286 ** text encodings supported by SQLite.

4287 */

4288 #define SQLITE_UTF8 1 /* IMP: R-37514-35566 */

4289 #define SQLITE_UTF16LE 2 /* IMP: R-03371-37637 */

4290 #define SQLITE_UTF16BE 3 /* IMP: R-51971-34154 */

4291 #define SQLITE_UTF16 4 /* Use native byte order */

4292 #define SQLITE_ANY 5 /* Deprecated */

4293 #define SQLITE_UTF16_ALIGNED 8 /* sqlite3_create_collation only */

4294

4295 /*

4296 ** CAPI3REF: Function Flags

4297 **

4298 ** These constants may be ORed together with the

4299 ** [SQLITE_UTF8 \| preferred text encoding] as the fourth argument

4300 ** to [sqlite3_create_function()], [sqlite3_create_function16()], or

4301 ** [sqlite3_create_function_v2()].

4302 */

4303 #define SQLITE_DETERMINISTIC 0x800

4304

4305 /*

4306 ** CAPI3REF: Deprecated Functions

4307 ** DEPRECATED

4308 **

4309 ** These functions are [deprecated]. In order to maintain

4310 ** backwards compatibility with older code, these functions continue

4311 ** to be supported. However, new applications should avoid

4312 ** the use of these functions. To encourage programmers to avoid

4313 ** these functions, we will not explain what they do.

4314 */

4315 #ifndef SQLITE_OMIT_DEPRECATED

4316 SQLITE_DEPRECATED int sqlite3_aggregate_count(sqlite3_context*);

4317 SQLITE_DEPRECATED int sqlite3_expired(sqlite3_stmt*);

4318 SQLITE_DEPRECATED int sqlite3_transfer_bindings(sqlite3_stmt, sqlite3_stmt);

4319 SQLITE_DEPRECATED int sqlite3_global_recover(void);

4320 SQLITE_DEPRECATED void sqlite3_thread_cleanup(void);

4321 SQLITE_DEPRECATED int sqlite3_memory_alarm(void()(void,sqlite3_int64,int),

4322 void*,sqlite3_int64);

4323 #endif

4324

4325 /*

4326 ** CAPI3REF: Obtaining SQL Values

4327 ** METHOD: sqlite3_value

4328 **

4329 ** The C-language implementation of SQL functions and aggregates uses

4330 ** this set of interface routines to access the parameter values on

4331 ** the function or aggregate.

4332 **

4333 ** The xFunc (for scalar functions) or xStep (for aggregates) parameters

4334 ** to [sqlite3_create_function()] and [sqlite3_create_function16()]

4335 ** define callbacks that implement the SQL functions and aggregates.

4336 ** The 3rd parameter to these callbacks is an array of pointers to

4337 ** [protected sqlite3_value] objects. There is one [sqlite3_value] object for

4338 ** each parameter to the SQL function. These routines are used to

4339 ** extract values from the [sqlite3_value] objects.

4340 **

4341 ** These routines work only with [protected sqlite3_value] objects.

4342 ** Any attempt to use these routines on an [unprotected sqlite3_value]

4343 ** object results in undefined behavior.

4344 **

4345 ** ^These routines work just like the corresponding [column access functions]

4346 ** except that these routines take a single [protected sqlite3_value] object

4347 ** pointer instead of a [sqlite3_stmt*] pointer and an integer column number.

4348 **

4349 ** ^The sqlite3_value_text16() interface extracts a UTF-16 string

4350 ** in the native byte-order of the host machine. ^The

4351 ** sqlite3_value_text16be() and sqlite3_value_text16le() interfaces

4352 ** extract UTF-16 strings as big-endian and little-endian respectively.

4353 **

4354 ** ^(The sqlite3_value_numeric_type() interface attempts to apply

4355 ** numeric affinity to the value. This means that an attempt is

4356 ** made to convert the value to an integer or floating point. If

4357 ** such a conversion is possible without loss of information (in other

4358 ** words, if the value is a string that looks like a number)

4359 ** then the conversion is performed. Otherwise no conversion occurs.

4360 ** The [SQLITE_INTEGER \| datatype] after conversion is returned.)^

4361 **

4362 ** Please pay particular attention to the fact that the pointer returned

4363 ** from [sqlite3_value_blob()], [sqlite3_value_text()], or

4364 ** [sqlite3_value_text16()] can be invalidated by a subsequent call to

4365 ** [sqlite3_value_bytes()], [sqlite3_value_bytes16()], [sqlite3_value_text()],

4366 ** or [sqlite3_value_text16()].

4367 **

4368 ** These routines must be called from the same thread as

4369 ** the SQL function that supplied the [sqlite3_value*] parameters.

4370 */

4371 const void sqlite3_value_blob(sqlite3_value);

4372 int sqlite3_value_bytes(sqlite3_value*);

4373 int sqlite3_value_bytes16(sqlite3_value*);

4374 double sqlite3_value_double(sqlite3_value*);

4375 int sqlite3_value_int(sqlite3_value*);

4376 sqlite3_int64 sqlite3_value_int64(sqlite3_value*);

4377 const unsigned char sqlite3_value_text(sqlite3_value);

4378 const void sqlite3_value_text16(sqlite3_value);

4379 const void sqlite3_value_text16le(sqlite3_value);

4380 const void sqlite3_value_text16be(sqlite3_value);

4381 int sqlite3_value_type(sqlite3_value*);

4382 int sqlite3_value_numeric_type(sqlite3_value*);

4383

4384 /*

4385 ** CAPI3REF: Finding The Subtype Of SQL Values

4386 ** METHOD: sqlite3_value

4387 **

4388 ** The sqlite3_value_subtype(V) function returns the subtype for

4389 ** an [application-defined SQL function] argument V. The subtype

4390 ** information can be used to pass a limited amount of context from

4391 ** one SQL function to another. Use the [sqlite3_result_subtype()]

4392 ** routine to set the subtype for the return value of an SQL function.

4393 **

4394 ** SQLite makes no use of subtype itself. It merely passes the subtype

4395 ** from the result of one [application-defined SQL function] into the

4396 ** input of another.

4397 */

4398 unsigned int sqlite3_value_subtype(sqlite3_value*);

4399

4400 /*

4401 ** CAPI3REF: Copy And Free SQL Values

4402 ** METHOD: sqlite3_value

4403 **

4404 ** ^The sqlite3_value_dup(V) interface makes a copy of the [sqlite3_value]

4405 ** object D and returns a pointer to that copy. ^The [sqlite3_value] returned

4406 ** is a [protected sqlite3_value] object even if the input is not.

4407 ** ^The sqlite3_value_dup(V) interface returns NULL if V is NULL or if a

4408 ** memory allocation fails.

4409 **

4410 ** ^The sqlite3_value_free(V) interface frees an [sqlite3_value] object

4411 ** previously obtained from [sqlite3_value_dup()]. ^If V is a NULL pointer

4412 ** then sqlite3_value_free(V) is a harmless no-op.

4413 */

4414 sqlite3_value sqlite3_value_dup(const sqlite3_value);

4415 void sqlite3_value_free(sqlite3_value*);

4416

4417 /*

4418 ** CAPI3REF: Obtain Aggregate Function Context

4419 ** METHOD: sqlite3_context

4420 **

4421 ** Implementations of aggregate SQL functions use this

4422 ** routine to allocate memory for storing their state.

4423 **

4424 ** ^The first time the sqlite3_aggregate_context(C,N) routine is called

4425 ** for a particular aggregate function, SQLite

4426 ** allocates N of memory, zeroes out that memory, and returns a pointer

4427 ** to the new memory. ^On second and subsequent calls to

4428 ** sqlite3_aggregate_context() for the same aggregate function instance,

4429 ** the same buffer is returned. Sqlite3_aggregate_context() is normally

4430 ** called once for each invocation of the xStep callback and then one

4431 ** last time when the xFinal callback is invoked. ^(When no rows match

4432 ** an aggregate query, the xStep() callback of the aggregate function

4433 ** implementation is never called and xFinal() is called exactly once.

4434 ** In those cases, sqlite3_aggregate_context() might be called for the

4435 ** first time from within xFinal().)^

4436 **

4437 ** ^The sqlite3_aggregate_context(C,N) routine returns a NULL pointer

4438 ** when first called if N is less than or equal to zero or if a memory

4439 ** allocate error occurs.

4440 **

4441 ** ^(The amount of space allocated by sqlite3_aggregate_context(C,N) is

4442 ** determined by the N parameter on first successful call. Changing the

4443 ** value of N in subsequent call to sqlite3_aggregate_context() within

4444 ** the same aggregate function instance will not resize the memory

4445 ** allocation.)^ Within the xFinal callback, it is customary to set

4446 ** N=0 in calls to sqlite3_aggregate_context(C,N) so that no

4447 ** pointless memory allocations occur.

4448 **

4449 ** ^SQLite automatically frees the memory allocated by

4450 ** sqlite3_aggregate_context() when the aggregate query concludes.

4451 **

4452 ** The first parameter must be a copy of the

4453 ** [sqlite3_context \| SQL function context] that is the first parameter

4454 ** to the xStep or xFinal callback routine that implements the aggregate

4455 ** function.

4456 **

4457 ** This routine must be called from the same thread in which

4458 ** the aggregate SQL function is running.

4459 */

4460 void sqlite3_aggregate_context(sqlite3_context, int nBytes);

4461

4462 /*

4463 ** CAPI3REF: User Data For Functions

4464 ** METHOD: sqlite3_context

4465 **

4466 ** ^The sqlite3_user_data() interface returns a copy of

4467 ** the pointer that was the pUserData parameter (the 5th parameter)

4468 ** of the [sqlite3_create_function()]

4469 ** and [sqlite3_create_function16()] routines that originally

4470 ** registered the application defined function.

4471 **

4472 ** This routine must be called from the same thread in which

4473 ** the application-defined function is running.

4474 */

4475 void sqlite3_user_data(sqlite3_context);

4476

4477 /*

4478 ** CAPI3REF: Database Connection For Functions

4479 ** METHOD: sqlite3_context

4480 **

4481 ** ^The sqlite3_context_db_handle() interface returns a copy of

4482 ** the pointer to the [database connection] (the 1st parameter)

4483 ** of the [sqlite3_create_function()]

4484 ** and [sqlite3_create_function16()] routines that originally

4485 ** registered the application defined function.

4486 */

4487 sqlite3 sqlite3_context_db_handle(sqlite3_context);

4488

4489 /*

4490 ** CAPI3REF: Function Auxiliary Data

4491 ** METHOD: sqlite3_context

4492 **

4493 ** These functions may be used by (non-aggregate) SQL functions to

4494 ** associate metadata with argument values. If the same value is passed to

4495 ** multiple invocations of the same SQL function during query execution, under

4496 ** some circumstances the associated metadata may be preserved. An example

4497 ** of where this might be useful is in a regular-expression matching

4498 ** function. The compiled version of the regular expression can be stored as

4499 ** metadata associated with the pattern string.

4500 ** Then as long as the pattern string remains the same,

4501 ** the compiled regular expression can be reused on multiple

4502 ** invocations of the same function.

4503 **

4504 ** ^The sqlite3_get_auxdata() interface returns a pointer to the metadata

4505 ** associated by the sqlite3_set_auxdata() function with the Nth argument

4506 ** value to the application-defined function. ^If there is no metadata

4507 ** associated with the function argument, this sqlite3_get_auxdata() interface

4508 ** returns a NULL pointer.

4509 **

4510 ** ^The sqlite3_set_auxdata(C,N,P,X) interface saves P as metadata for the N-th

4511 ** argument of the application-defined function. ^Subsequent

4512 ** calls to sqlite3_get_auxdata(C,N) return P from the most recent

4513 ** sqlite3_set_auxdata(C,N,P,X) call if the metadata is still valid or

4514 ** NULL if the metadata has been discarded.

4515 ** ^After each call to sqlite3_set_auxdata(C,N,P,X) where X is not NULL,

4516 ** SQLite will invoke the destructor function X with parameter P exactly

4517 ** once, when the metadata is discarded.

4518 ** SQLite is free to discard the metadata at any time, including: <ul>

4519 ** <li> when the corresponding function parameter changes, or

4520 ** <li> when [sqlite3_reset()] or [sqlite3_finalize()] is called for the

4521 ** SQL statement, or

4522 ** <li> when sqlite3_set_auxdata() is invoked again on the same parameter, or

4523 ** <li> during the original sqlite3_set_auxdata() call when a memory

4524 ** allocation error occurs. </ul>)^

4525 **

4526 ** Note the last bullet in particular. The destructor X in

4527 ** sqlite3_set_auxdata(C,N,P,X) might be called immediately, before the

4528 ** sqlite3_set_auxdata() interface even returns. Hence sqlite3_set_auxdata()

4529 ** should be called near the end of the function implementation and the

4530 ** function implementation should not make any use of P after

4531 ** sqlite3_set_auxdata() has been called.

4532 **

4533 ** ^(In practice, metadata is preserved between function calls for

4534 ** function parameters that are compile-time constants, including literal

4535 ** values and [parameters] and expressions composed from the same.)^

4536 **

4537 ** These routines must be called from the same thread in which

4538 ** the SQL function is running.

4539 */

4540 void sqlite3_get_auxdata(sqlite3_context, int N);

4541 void sqlite3_set_auxdata(sqlite3_context, int N, void, void ()(void));

4542

4543

4544 /*

4545 ** CAPI3REF: Constants Defining Special Destructor Behavior

4546 **

4547 ** These are special values for the destructor that is passed in as the

4548 ** final argument to routines like [sqlite3_result_blob()]. ^If the destructor

4549 ** argument is SQLITE_STATIC, it means that the content pointer is constant

4550 ** and will never change. It does not need to be destroyed. ^The

4551 ** SQLITE_TRANSIENT value means that the content will likely change in

4552 ** the near future and that SQLite should make its own private copy of

4553 ** the content before returning.

4554 **

4555 ** The typedef is necessary to work around problems in certain

4556 ** C++ compilers.

4557 */

4558 typedef void (sqlite3_destructor_type)(void);

4559 #define SQLITE_STATIC ((sqlite3_destructor_type)0)

4560 #define SQLITE_TRANSIENT ((sqlite3_destructor_type)-1)

4561

4562 /*

4563 ** CAPI3REF: Setting The Result Of An SQL Function

4564 ** METHOD: sqlite3_context

4565 **

4566 ** These routines are used by the xFunc or xFinal callbacks that

4567 ** implement SQL functions and aggregates. See

4568 ** [sqlite3_create_function()] and [sqlite3_create_function16()]

4569 ** for additional information.

4570 **

4571 ** These functions work very much like the [parameter binding] family of

4572 ** functions used to bind values to host parameters in prepared statements.

4573 ** Refer to the [SQL parameter] documentation for additional information.

4574 **

4575 ** ^The sqlite3_result_blob() interface sets the result from

4576 ** an application-defined function to be the BLOB whose content is pointed

4577 ** to by the second parameter and which is N bytes long where N is the

4578 ** third parameter.

4579 **

4580 ** ^The sqlite3_result_zeroblob(C,N) and sqlite3_result_zeroblob64(C,N)

4581 ** interfaces set the result of the application-defined function to be

4582 ** a BLOB containing all zero bytes and N bytes in size.

4583 **

4584 ** ^The sqlite3_result_double() interface sets the result from

4585 ** an application-defined function to be a floating point value specified

4586 ** by its 2nd argument.

4587 **

4588 ** ^The sqlite3_result_error() and sqlite3_result_error16() functions

4589 ** cause the implemented SQL function to throw an exception.

4590 ** ^SQLite uses the string pointed to by the

4591 ** 2nd parameter of sqlite3_result_error() or sqlite3_result_error16()

4592 ** as the text of an error message. ^SQLite interprets the error

4593 ** message string from sqlite3_result_error() as UTF-8. ^SQLite

4594 ** interprets the string from sqlite3_result_error16() as UTF-16 in native

4595 ** byte order. ^If the third parameter to sqlite3_result_error()

4596 ** or sqlite3_result_error16() is negative then SQLite takes as the error

4597 ** message all text up through the first zero character.

4598 ** ^If the third parameter to sqlite3_result_error() or

4599 ** sqlite3_result_error16() is non-negative then SQLite takes that many

4600 ** bytes (not characters) from the 2nd parameter as the error message.

4601 ** ^The sqlite3_result_error() and sqlite3_result_error16()

4602 ** routines make a private copy of the error message text before

4603 ** they return. Hence, the calling function can deallocate or

4604 ** modify the text after they return without harm.

4605 ** ^The sqlite3_result_error_code() function changes the error code

4606 ** returned by SQLite as a result of an error in a function. ^By default,

4607 ** the error code is SQLITE_ERROR. ^A subsequent call to sqlite3_result_error()

4608 ** or sqlite3_result_error16() resets the error code to SQLITE_ERROR.

4609 **

4610 ** ^The sqlite3_result_error_toobig() interface causes SQLite to throw an

4611 ** error indicating that a string or BLOB is too long to represent.

4612 **

4613 ** ^The sqlite3_result_error_nomem() interface causes SQLite to throw an

4614 ** error indicating that a memory allocation failed.

4615 **

4616 ** ^The sqlite3_result_int() interface sets the return value

4617 ** of the application-defined function to be the 32-bit signed integer

4618 ** value given in the 2nd argument.

4619 ** ^The sqlite3_result_int64() interface sets the return value

4620 ** of the application-defined function to be the 64-bit signed integer

4621 ** value given in the 2nd argument.

4622 **

4623 ** ^The sqlite3_result_null() interface sets the return value

4624 ** of the application-defined function to be NULL.

4625 **

4626 ** ^The sqlite3_result_text(), sqlite3_result_text16(),

4627 ** sqlite3_result_text16le(), and sqlite3_result_text16be() interfaces

4628 ** set the return value of the application-defined function to be

4629 ** a text string which is represented as UTF-8, UTF-16 native byte order,

4630 ** UTF-16 little endian, or UTF-16 big endian, respectively.

4631 ** ^The sqlite3_result_text64() interface sets the return value of an

4632 ** application-defined function to be a text string in an encoding

4633 ** specified by the fifth (and last) parameter, which must be one

4634 ** of [SQLITE_UTF8], [SQLITE_UTF16], [SQLITE_UTF16BE], or [SQLITE_UTF16LE].

4635 ** ^SQLite takes the text result from the application from

4636 ** the 2nd parameter of the sqlite3_result_text* interfaces.

4637 ** ^If the 3rd parameter to the sqlite3_result_text* interfaces

4638 ** is negative, then SQLite takes result text from the 2nd parameter

4639 ** through the first zero character.

4640 ** ^If the 3rd parameter to the sqlite3_result_text* interfaces

4641 ** is non-negative, then as many bytes (not characters) of the text

4642 ** pointed to by the 2nd parameter are taken as the application-defined

4643 ** function result. If the 3rd parameter is non-negative, then it

4644 ** must be the byte offset into the string where the NUL terminator would

4645 ** appear if the string where NUL terminated. If any NUL characters occur

4646 ** in the string at a byte offset that is less than the value of the 3rd

4647 ** parameter, then the resulting string will contain embedded NULs and the

4648 ** result of expressions operating on strings with embedded NULs is undefined.

4649 ** ^If the 4th parameter to the sqlite3_result_text* interfaces

4650 ** or sqlite3_result_blob is a non-NULL pointer, then SQLite calls that

4651 ** function as the destructor on the text or BLOB result when it has

4652 ** finished using that result.

4653 ** ^If the 4th parameter to the sqlite3_result_text* interfaces or to

4654 ** sqlite3_result_blob is the special constant SQLITE_STATIC, then SQLite

4655 ** assumes that the text or BLOB result is in constant space and does not

4656 ** copy the content of the parameter nor call a destructor on the content

4657 ** when it has finished using that result.

4658 ** ^If the 4th parameter to the sqlite3_result_text* interfaces

4659 ** or sqlite3_result_blob is the special constant SQLITE_TRANSIENT

4660 ** then SQLite makes a copy of the result into space obtained from

4661 ** from [sqlite3_malloc()] before it returns.

4662 **

4663 ** ^The sqlite3_result_value() interface sets the result of

4664 ** the application-defined function to be a copy of the

4665 ** [unprotected sqlite3_value] object specified by the 2nd parameter. ^The

4666 ** sqlite3_result_value() interface makes a copy of the [sqlite3_value]

4667 ** so that the [sqlite3_value] specified in the parameter may change or

4668 ** be deallocated after sqlite3_result_value() returns without harm.

4669 ** ^A [protected sqlite3_value] object may always be used where an

4670 ** [unprotected sqlite3_value] object is required, so either

4671 ** kind of [sqlite3_value] object can be used with this interface.

4672 **

4673 ** If these routines are called from within the different thread

4674 ** than the one containing the application-defined function that received

4675 ** the [sqlite3_context] pointer, the results are undefined.

4676 */

4677 void sqlite3_result_blob(sqlite3_context, const void, int, void()(void));

4678 void sqlite3_result_blob64(sqlite3_context,const void,

4679 sqlite3_uint64,void()(void));

4680 void sqlite3_result_double(sqlite3_context*, double);

4681 void sqlite3_result_error(sqlite3_context, const char, int);

4682 void sqlite3_result_error16(sqlite3_context, const void, int);

4683 void sqlite3_result_error_toobig(sqlite3_context*);

4684 void sqlite3_result_error_nomem(sqlite3_context*);

4685 void sqlite3_result_error_code(sqlite3_context*, int);

4686 void sqlite3_result_int(sqlite3_context*, int);

4687 void sqlite3_result_int64(sqlite3_context*, sqlite3_int64);

4688 void sqlite3_result_null(sqlite3_context*);

4689 void sqlite3_result_text(sqlite3_context, const char, int, void()(void));

4690 void sqlite3_result_text64(sqlite3_context, const char,sqlite3_uint64,

4691 void()(void), unsigned char encoding);

4692 void sqlite3_result_text16(sqlite3_context, const void, int, void()(void));

4693 void sqlite3_result_text16le(sqlite3_context, const void, int,void()(void));

4694 void sqlite3_result_text16be(sqlite3_context, const void, int,void()(void));

4695 void sqlite3_result_value(sqlite3_context, sqlite3_value);

4696 void sqlite3_result_zeroblob(sqlite3_context*, int n);

4697 int sqlite3_result_zeroblob64(sqlite3_context*, sqlite3_uint64 n);

4698

4699

4700 /*

4701 ** CAPI3REF: Setting The Subtype Of An SQL Function

4702 ** METHOD: sqlite3_context

4703 **

4704 ** The sqlite3_result_subtype(C,T) function causes the subtype of

4705 ** the result from the [application-defined SQL function] with

4706 ** [sqlite3_context] C to be the value T. Only the lower 8 bits

4707 ** of the subtype T are preserved in current versions of SQLite;

4708 ** higher order bits are discarded.

4709 ** The number of subtype bytes preserved by SQLite might increase

4710 ** in future releases of SQLite.

4711 */

4712 void sqlite3_result_subtype(sqlite3_context*,unsigned int);

4713

4714 /*

4715 ** CAPI3REF: Define New Collating Sequences

4716 ** METHOD: sqlite3

4717 **

4718 ** ^These functions add, remove, or modify a [collation] associated

4719 ** with the [database connection] specified as the first argument.

4720 **

4721 ** ^The name of the collation is a UTF-8 string

4722 ** for sqlite3_create_collation() and sqlite3_create_collation_v2()

4723 ** and a UTF-16 string in native byte order for sqlite3_create_collation16().

4724 ** ^Collation names that compare equal according to [sqlite3_strnicmp()] are

4725 ** considered to be the same name.

4726 **

4727 ** ^(The third argument (eTextRep) must be one of the constants:

4728 ** <ul>

4729 ** <li> [SQLITE_UTF8],

4730 ** <li> [SQLITE_UTF16LE],

4731 ** <li> [SQLITE_UTF16BE],

4732 ** <li> [SQLITE_UTF16], or

4733 ** <li> [SQLITE_UTF16_ALIGNED].

4734 ** </ul>)^

4735 ** ^The eTextRep argument determines the encoding of strings passed

4736 ** to the collating function callback, xCallback.

4737 ** ^The [SQLITE_UTF16] and [SQLITE_UTF16_ALIGNED] values for eTextRep

4738 ** force strings to be UTF16 with native byte order.

4739 ** ^The [SQLITE_UTF16_ALIGNED] value for eTextRep forces strings to begin

4740 ** on an even byte address.

4741 **

4742 ** ^The fourth argument, pArg, is an application data pointer that is passed

4743 ** through as the first argument to the collating function callback.

4744 **

4745 ** ^The fifth argument, xCallback, is a pointer to the collating function.

4746 ** ^Multiple collating functions can be registered using the same name but

4747 ** with different eTextRep parameters and SQLite will use whichever

4748 ** function requires the least amount of data transformation.

4749 ** ^If the xCallback argument is NULL then the collating function is

4750 ** deleted. ^When all collating functions having the same name are deleted,

4751 ** that collation is no longer usable.

4752 **

4753 ** ^The collating function callback is invoked with a copy of the pArg

4754 ** application data pointer and with two strings in the encoding specified

4755 ** by the eTextRep argument. The collating function must return an

4756 ** integer that is negative, zero, or positive

4757 ** if the first string is less than, equal to, or greater than the second,

4758 ** respectively. A collating function must always return the same answer

4759 ** given the same inputs. If two or more collating functions are registered

4760 ** to the same collation name (using different eTextRep values) then all

4761 ** must give an equivalent answer when invoked with equivalent strings.

4762 ** The collating function must obey the following properties for all

4763 ** strings A, B, and C:

4764 **

4765 ** <ol>

4766 ** <li> If A==B then B==A.

4767 ** <li> If A==B and B==C then A==C.

4768 ** <li> If A<B THEN B>A.

4769 ** <li> If A<B and B<C then A<C.

4770 ** </ol>

4771 **

4772 ** If a collating function fails any of the above constraints and that

4773 ** collating function is registered and used, then the behavior of SQLite

4774 ** is undefined.

4775 **

4776 ** ^The sqlite3_create_collation_v2() works like sqlite3_create_collation()

4777 ** with the addition that the xDestroy callback is invoked on pArg when

4778 ** the collating function is deleted.

4779 ** ^Collating functions are deleted when they are overridden by later

4780 ** calls to the collation creation functions or when the

4781 ** [database connection] is closed using [sqlite3_close()].

4782 **

4783 ** ^The xDestroy callback is <u>not</u> called if the

4784 ** sqlite3_create_collation_v2() function fails. Applications that invoke

4785 ** sqlite3_create_collation_v2() with a non-NULL xDestroy argument should

4786 ** check the return code and dispose of the application data pointer

4787 ** themselves rather than expecting SQLite to deal with it for them.

4788 ** This is different from every other SQLite interface. The inconsistency

4789 ** is unfortunate but cannot be changed without breaking backwards

4790 ** compatibility.

4791 **

4792 ** See also: [sqlite3_collation_needed()] and [sqlite3_collation_needed16()].

4793 */

4794 int sqlite3_create_collation(

4795 sqlite3*,

4796 const char *zName,

4797 int eTextRep,

4798 void *pArg,

4799 int(xCompare)(void,int,const void,int,const void)

4800 );

4801 int sqlite3_create_collation_v2(

4802 sqlite3*,

4803 const char *zName,

4804 int eTextRep,

4805 void *pArg,

4806 int(xCompare)(void,int,const void,int,const void),

4807 void(xDestroy)(void)

4808 );

4809 int sqlite3_create_collation16(

4810 sqlite3*,

4811 const void *zName,

4812 int eTextRep,

4813 void *pArg,

4814 int(xCompare)(void,int,const void,int,const void)

4815 );

4816

4817 /*

4818 ** CAPI3REF: Collation Needed Callbacks

4819 ** METHOD: sqlite3

4820 **

4821 ** ^To avoid having to register all collation sequences before a database

4822 ** can be used, a single callback function may be registered with the

4823 ** [database connection] to be invoked whenever an undefined collation

4824 ** sequence is required.

4825 **

4826 ** ^If the function is registered using the sqlite3_collation_needed() API,

4827 ** then it is passed the names of undefined collation sequences as strings

4828 ** encoded in UTF-8. ^If sqlite3_collation_needed16() is used,

4829 ** the names are passed as UTF-16 in machine native byte order.

4830 ** ^A call to either function replaces the existing collation-needed callback.

4831 **

4832 ** ^(When the callback is invoked, the first argument passed is a copy

4833 ** of the second argument to sqlite3_collation_needed() or

4834 ** sqlite3_collation_needed16(). The second argument is the database

4835 ** connection. The third argument is one of [SQLITE_UTF8], [SQLITE_UTF16BE],

4836 ** or [SQLITE_UTF16LE], indicating the most desirable form of the collation

4837 ** sequence function required. The fourth parameter is the name of the

4838 ** required collation sequence.)^

4839 **

4840 ** The callback function should register the desired collation using

4841 ** [sqlite3_create_collation()], [sqlite3_create_collation16()], or

4842 ** [sqlite3_create_collation_v2()].

4843 */

4844 int sqlite3_collation_needed(

4845 sqlite3*,

4846 void*,

4847 void()(void,sqlite3,int eTextRep,const char)

4848 );

4849 int sqlite3_collation_needed16(

4850 sqlite3*,

4851 void*,

4852 void()(void,sqlite3,int eTextRep,const void)

4853 );

4854

4855 #ifdef SQLITE_HAS_CODEC

4856 /*

4857 ** Specify the key for an encrypted database. This routine should be

4858 ** called right after sqlite3_open().

4859 **

4860 ** The code to implement this API is not available in the public release

4861 ** of SQLite.

4862 */

4863 int sqlite3_key(

4864 sqlite3 db, / Database to be rekeyed */

4865 const void pKey, int nKey / The key */

4866 );

4867 int sqlite3_key_v2(

4868 sqlite3 db, / Database to be rekeyed */

4869 const char zDbName, / Name of the database */

4870 const void pKey, int nKey / The key */

4871 );

4872

4873 /*

4874 ** Change the key on an open database. If the current database is not

4875 ** encrypted, this routine will encrypt it. If pNew==0 or nNew==0, the

4876 ** database is decrypted.

4877 **

4878 ** The code to implement this API is not available in the public release

4879 ** of SQLite.

4880 */

4881 int sqlite3_rekey(

4882 sqlite3 db, / Database to be rekeyed */

4883 const void pKey, int nKey / The new key */

4884 );

4885 int sqlite3_rekey_v2(

4886 sqlite3 db, / Database to be rekeyed */

4887 const char zDbName, / Name of the database */

4888 const void pKey, int nKey / The new key */

4889 );

4890

4891 /*

4892 ** Specify the activation key for a SEE database. Unless

4893 ** activated, none of the SEE routines will work.

4894 */

4895 void sqlite3_activate_see(

4896 const char zPassPhrase / Activation phrase */

4897 );

4898 #endif

4899

4900 #ifdef SQLITE_ENABLE_CEROD

4901 /*

4902 ** Specify the activation key for a CEROD database. Unless

4903 ** activated, none of the CEROD routines will work.

4904 */

4905 void sqlite3_activate_cerod(

4906 const char zPassPhrase / Activation phrase */

4907 );

4908 #endif

4909

4910 /*

4911 ** CAPI3REF: Suspend Execution For A Short Time

4912 **

4913 ** The sqlite3_sleep() function causes the current thread to suspend execution

4914 ** for at least a number of milliseconds specified in its parameter.

4915 **

4916 ** If the operating system does not support sleep requests with

4917 ** millisecond time resolution, then the time will be rounded up to

4918 ** the nearest second. The number of milliseconds of sleep actually

4919 ** requested from the operating system is returned.

4920 **

4921 ** ^SQLite implements this interface by calling the xSleep()

4922 ** method of the default [sqlite3_vfs] object. If the xSleep() method

4923 ** of the default VFS is not implemented correctly, or not implemented at

4924 ** all, then the behavior of sqlite3_sleep() may deviate from the description

4925 ** in the previous paragraphs.

4926 */

4927 int sqlite3_sleep(int);

4928

4929 /*

4930 ** CAPI3REF: Name Of The Folder Holding Temporary Files

4931 **

4932 ** ^(If this global variable is made to point to a string which is

4933 ** the name of a folder (a.k.a. directory), then all temporary files

4934 ** created by SQLite when using a built-in [sqlite3_vfs \| VFS]

4935 ** will be placed in that directory.)^ ^If this variable

4936 ** is a NULL pointer, then SQLite performs a search for an appropriate

4937 ** temporary file directory.

4938 **

4939 ** Applications are strongly discouraged from using this global variable.

4940 ** It is required to set a temporary folder on Windows Runtime (WinRT).

4941 ** But for all other platforms, it is highly recommended that applications

4942 ** neither read nor write this variable. This global variable is a relic

4943 ** that exists for backwards compatibility of legacy applications and should

4944 ** be avoided in new projects.

4945 **

4946 ** It is not safe to read or modify this variable in more than one

4947 ** thread at a time. It is not safe to read or modify this variable

4948 ** if a [database connection] is being used at the same time in a separate

4949 ** thread.

4950 ** It is intended that this variable be set once

4951 ** as part of process initialization and before any SQLite interface

4952 ** routines have been called and that this variable remain unchanged

4953 ** thereafter.

4954 **

4955 ** ^The [temp_store_directory pragma] may modify this variable and cause

4956 ** it to point to memory obtained from [sqlite3_malloc]. ^Furthermore,

4957 ** the [temp_store_directory pragma] always assumes that any string

4958 ** that this variable points to is held in memory obtained from

4959 ** [sqlite3_malloc] and the pragma may attempt to free that memory

4960 ** using [sqlite3_free].

4961 ** Hence, if this variable is modified directly, either it should be

4962 ** made NULL or made to point to memory obtained from [sqlite3_malloc]

4963 ** or else the use of the [temp_store_directory pragma] should be avoided.

4964 ** Except when requested by the [temp_store_directory pragma], SQLite

4965 ** does not free the memory that sqlite3_temp_directory points to. If

4966 ** the application wants that memory to be freed, it must do

4967 ** so itself, taking care to only do so after all [database connection]

4968 ** objects have been destroyed.

4969 **

4970 ** <b>Note to Windows Runtime users:</b> The temporary directory must be set

4971 ** prior to calling [sqlite3_open] or [sqlite3_open_v2]. Otherwise, various

4972 ** features that require the use of temporary files may fail. Here is an

4973 ** example of how to do this using C++ with the Windows Runtime:

4974 **

4975 ** <blockquote><pre>

4976 ** LPCWSTR zPath = Windows::Storage::ApplicationData::Current->

4977 **   TemporaryFolder->Path->Data();

4978 ** char zPathBuf[MAX_PATH + 1];

4979 ** memset(zPathBuf, 0, sizeof(zPathBuf));

4980 ** WideCharToMultiByte(CP_UTF8, 0, zPath, -1, zPathBuf, sizeof(zPathBuf),

4981 **   NULL, NULL);

4982 ** sqlite3_temp_directory = sqlite3_mprintf("%s", zPathBuf);

4983 ** </pre></blockquote>

4984 */

4985 SQLITE_EXTERN char *sqlite3_temp_directory;

4986

4987 /*

4988 ** CAPI3REF: Name Of The Folder Holding Database Files

4989 **

4990 ** ^(If this global variable is made to point to a string which is

4991 ** the name of a folder (a.k.a. directory), then all database files

4992 ** specified with a relative pathname and created or accessed by

4993 ** SQLite when using a built-in windows [sqlite3_vfs \| VFS] will be assumed

4994 ** to be relative to that directory.)^ ^If this variable is a NULL

4995 ** pointer, then SQLite assumes that all database files specified

4996 ** with a relative pathname are relative to the current directory

4997 ** for the process. Only the windows VFS makes use of this global

4998 ** variable; it is ignored by the unix VFS.

4999 **

5000 ** Changing the value of this variable while a database connection is

5001 ** open can result in a corrupt database.

5002 **

5003 ** It is not safe to read or modify this variable in more than one

5004 ** thread at a time. It is not safe to read or modify this variable

5005 ** if a [database connection] is being used at the same time in a separate

5006 ** thread.

5007 ** It is intended that this variable be set once

5008 ** as part of process initialization and before any SQLite interface

5009 ** routines have been called and that this variable remain unchanged

5010 ** thereafter.

5011 **

5012 ** ^The [data_store_directory pragma] may modify this variable and cause

5013 ** it to point to memory obtained from [sqlite3_malloc]. ^Furthermore,

5014 ** the [data_store_directory pragma] always assumes that any string

5015 ** that this variable points to is held in memory obtained from

5016 ** [sqlite3_malloc] and the pragma may attempt to free that memory

5017 ** using [sqlite3_free].

5018 ** Hence, if this variable is modified directly, either it should be

5019 ** made NULL or made to point to memory obtained from [sqlite3_malloc]

5020 ** or else the use of the [data_store_directory pragma] should be avoided.

5021 */

5022 SQLITE_EXTERN char *sqlite3_data_directory;

5023

5024 /*

5025 ** CAPI3REF: Test For Auto-Commit Mode

5026 ** KEYWORDS: {autocommit mode}

5027 ** METHOD: sqlite3

5028 **

5029 ** ^The sqlite3_get_autocommit() interface returns non-zero or

5030 ** zero if the given database connection is or is not in autocommit mode,

5031 ** respectively. ^Autocommit mode is on by default.

5032 ** ^Autocommit mode is disabled by a [BEGIN] statement.

5033 ** ^Autocommit mode is re-enabled by a [COMMIT] or [ROLLBACK].

5034 **

5035 ** If certain kinds of errors occur on a statement within a multi-statement

5036 ** transaction (errors including [SQLITE_FULL], [SQLITE_IOERR],

5037 ** [SQLITE_NOMEM], [SQLITE_BUSY], and [SQLITE_INTERRUPT]) then the

5038 ** transaction might be rolled back automatically. The only way to

5039 ** find out whether SQLite automatically rolled back the transaction after

5040 ** an error is to use this function.

5041 **

5042 ** If another thread changes the autocommit status of the database

5043 ** connection while this routine is running, then the return value

5044 ** is undefined.

5045 */

5046 int sqlite3_get_autocommit(sqlite3*);

5047

5048 /*

5049 ** CAPI3REF: Find The Database Handle Of A Prepared Statement

5050 ** METHOD: sqlite3_stmt

5051 **

5052 ** ^The sqlite3_db_handle interface returns the [database connection] handle

5053 ** to which a [prepared statement] belongs. ^The [database connection]

5054 ** returned by sqlite3_db_handle is the same [database connection]

5055 ** that was the first argument

5056 ** to the [sqlite3_prepare_v2()] call (or its variants) that was used to

5057 ** create the statement in the first place.

5058 */

5059 sqlite3 sqlite3_db_handle(sqlite3_stmt);

5060

5061 /*

5062 ** CAPI3REF: Return The Filename For A Database Connection

5063 ** METHOD: sqlite3

5064 **

5065 ** ^The sqlite3_db_filename(D,N) interface returns a pointer to a filename

5066 ** associated with database N of connection D. ^The main database file

5067 ** has the name "main". If there is no attached database N on the database

5068 ** connection D, or if database N is a temporary or in-memory database, then

5069 ** a NULL pointer is returned.

5070 **

5071 ** ^The filename returned by this function is the output of the

5072 ** xFullPathname method of the [VFS]. ^In other words, the filename

5073 ** will be an absolute pathname, even if the filename used

5074 ** to open the database originally was a URI or relative pathname.

5075 */

5076 const char sqlite3_db_filename(sqlite3 db, const char *zDbName);

5077

5078 /*

5079 ** CAPI3REF: Determine if a database is read-only

5080 ** METHOD: sqlite3

5081 **

5082 ** ^The sqlite3_db_readonly(D,N) interface returns 1 if the database N

5083 ** of connection D is read-only, 0 if it is read/write, or -1 if N is not

5084 ** the name of a database on connection D.

5085 */

5086 int sqlite3_db_readonly(sqlite3 db, const char zDbName);

5087

5088 /*

5089 ** CAPI3REF: Find the next prepared statement

5090 ** METHOD: sqlite3

5091 **

5092 ** ^This interface returns a pointer to the next [prepared statement] after

5093 ** pStmt associated with the [database connection] pDb. ^If pStmt is NULL

5094 ** then this interface returns a pointer to the first prepared statement

5095 ** associated with the database connection pDb. ^If no prepared statement

5096 ** satisfies the conditions of this routine, it returns NULL.

5097 **

5098 ** The [database connection] pointer D in a call to

5099 ** [sqlite3_next_stmt(D,S)] must refer to an open database

5100 ** connection and in particular must not be a NULL pointer.

5101 */

5102 sqlite3_stmt sqlite3_next_stmt(sqlite3 pDb, sqlite3_stmt *pStmt);

5103

5104 /*

5105 ** CAPI3REF: Commit And Rollback Notification Callbacks

5106 ** METHOD: sqlite3

5107 **

5108 ** ^The sqlite3_commit_hook() interface registers a callback

5109 ** function to be invoked whenever a transaction is [COMMIT \| committed].

5110 ** ^Any callback set by a previous call to sqlite3_commit_hook()

5111 ** for the same database connection is overridden.

5112 ** ^The sqlite3_rollback_hook() interface registers a callback

5113 ** function to be invoked whenever a transaction is [ROLLBACK \| rolled back].

5114 ** ^Any callback set by a previous call to sqlite3_rollback_hook()

5115 ** for the same database connection is overridden.

5116 ** ^The pArg argument is passed through to the callback.

5117 ** ^If the callback on a commit hook function returns non-zero,

5118 ** then the commit is converted into a rollback.

5119 **

5120 ** ^The sqlite3_commit_hook(D,C,P) and sqlite3_rollback_hook(D,C,P) functions

5121 ** return the P argument from the previous call of the same function

5122 ** on the same [database connection] D, or NULL for

5123 ** the first call for each function on D.

5124 **

5125 ** The commit and rollback hook callbacks are not reentrant.

5126 ** The callback implementation must not do anything that will modify

5127 ** the database connection that invoked the callback. Any actions

5128 ** to modify the database connection must be deferred until after the

5129 ** completion of the [sqlite3_step()] call that triggered the commit

5130 ** or rollback hook in the first place.

5131 ** Note that running any other SQL statements, including SELECT statements,

5132 ** or merely calling [sqlite3_prepare_v2()] and [sqlite3_step()] will modify

5133 ** the database connections for the meaning of "modify" in this paragraph.

5134 **

5135 ** ^Registering a NULL function disables the callback.

5136 **

5137 ** ^When the commit hook callback routine returns zero, the [COMMIT]

5138 ** operation is allowed to continue normally. ^If the commit hook

5139 ** returns non-zero, then the [COMMIT] is converted into a [ROLLBACK].

5140 ** ^The rollback hook is invoked on a rollback that results from a commit

5141 ** hook returning non-zero, just as it would be with any other rollback.

5142 **

5143 ** ^For the purposes of this API, a transaction is said to have been

5144 ** rolled back if an explicit "ROLLBACK" statement is executed, or

5145 ** an error or constraint causes an implicit rollback to occur.

5146 ** ^The rollback callback is not invoked if a transaction is

5147 ** automatically rolled back because the database connection is closed.

5148 **

5149 ** See also the [sqlite3_update_hook()] interface.

5150 */

5151 void sqlite3_commit_hook(sqlite3, int()(void), void*);

5152 void sqlite3_rollback_hook(sqlite3, void()(void ), void*);

5153

5154 /*

5155 ** CAPI3REF: Data Change Notification Callbacks

5156 ** METHOD: sqlite3

5157 **

5158 ** ^The sqlite3_update_hook() interface registers a callback function

5159 ** with the [database connection] identified by the first argument

5160 ** to be invoked whenever a row is updated, inserted or deleted in

5161 ** a rowid table.

5162 ** ^Any callback set by a previous call to this function

5163 ** for the same database connection is overridden.

5164 **

5165 ** ^The second argument is a pointer to the function to invoke when a

5166 ** row is updated, inserted or deleted in a rowid table.

5167 ** ^The first argument to the callback is a copy of the third argument

5168 ** to sqlite3_update_hook().

5169 ** ^The second callback argument is one of [SQLITE_INSERT], [SQLITE_DELETE],

5170 ** or [SQLITE_UPDATE], depending on the operation that caused the callback

5171 ** to be invoked.

5172 ** ^The third and fourth arguments to the callback contain pointers to the

5173 ** database and table name containing the affected row.

5174 ** ^The final callback parameter is the [rowid] of the row.

5175 ** ^In the case of an update, this is the [rowid] after the update takes place.

5176 **

5177 ** ^(The update hook is not invoked when internal system tables are

5178 ** modified (i.e. sqlite_master and sqlite_sequence).)^

5179 ** ^The update hook is not invoked when [WITHOUT ROWID] tables are modified.

5180 **

5181 ** ^In the current implementation, the update hook

5182 ** is not invoked when duplication rows are deleted because of an

5183 ** [ON CONFLICT \| ON CONFLICT REPLACE] clause. ^Nor is the update hook

5184 ** invoked when rows are deleted using the [truncate optimization].

5185 ** The exceptions defined in this paragraph might change in a future

5186 ** release of SQLite.

5187 **

5188 ** The update hook implementation must not do anything that will modify

5189 ** the database connection that invoked the update hook. Any actions

5190 ** to modify the database connection must be deferred until after the

5191 ** completion of the [sqlite3_step()] call that triggered the update hook.

5192 ** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their

5193 ** database connections for the meaning of "modify" in this paragraph.

5194 **

5195 ** ^The sqlite3_update_hook(D,C,P) function

5196 ** returns the P argument from the previous call

5197 ** on the same [database connection] D, or NULL for

5198 ** the first call on D.

5199 **

5200 ** See also the [sqlite3_commit_hook()] and [sqlite3_rollback_hook()]

5201 ** interfaces.

5202 */

5203 void *sqlite3_update_hook(

5204 sqlite3*,

5205 void()(void ,int ,char const ,char const ,sqlite3_int64),

5206 void*

5207 );

5208

5209 /*

5210 ** CAPI3REF: Enable Or Disable Shared Pager Cache

5211 **

5212 ** ^(This routine enables or disables the sharing of the database cache

5213 ** and schema data structures between [database connection \| connections]

5214 ** to the same database. Sharing is enabled if the argument is true

5215 ** and disabled if the argument is false.)^

5216 **

5217 ** ^Cache sharing is enabled and disabled for an entire process.

5218 ** This is a change as of SQLite version 3.5.0. In prior versions of SQLite,

5219 ** sharing was enabled or disabled for each thread separately.

5220 **

5221 ** ^(The cache sharing mode set by this interface effects all subsequent

5222 ** calls to [sqlite3_open()], [sqlite3_open_v2()], and [sqlite3_open16()].

5223 ** Existing database connections continue use the sharing mode

5224 ** that was in effect at the time they were opened.)^

5225 **

5226 ** ^(This routine returns [SQLITE_OK] if shared cache was enabled or disabled

5227 ** successfully. An [error code] is returned otherwise.)^

5228 **

5229 ** ^Shared cache is disabled by default. But this might change in

5230 ** future releases of SQLite. Applications that care about shared

5231 ** cache setting should set it explicitly.

5232 **

5233 ** Note: This method is disabled on MacOS X 10.7 and iOS version 5.0

5234 ** and will always return SQLITE_MISUSE. On those systems,

5235 ** shared cache mode should be enabled per-database connection via

5236 ** [sqlite3_open_v2()] with [SQLITE_OPEN_SHAREDCACHE].

5237 **

5238 ** This interface is threadsafe on processors where writing a

5239 ** 32-bit integer is atomic.

5240 **

5241 ** See Also: [SQLite Shared-Cache Mode]

5242 */

5243 int sqlite3_enable_shared_cache(int);

5244

5245 /*

5246 ** CAPI3REF: Attempt To Free Heap Memory

5247 **

5248 ** ^The sqlite3_release_memory() interface attempts to free N bytes

5249 ** of heap memory by deallocating non-essential memory allocations

5250 ** held by the database library. Memory used to cache database

5251 ** pages to improve performance is an example of non-essential memory.

5252 ** ^sqlite3_release_memory() returns the number of bytes actually freed,

5253 ** which might be more or less than the amount requested.

5254 ** ^The sqlite3_release_memory() routine is a no-op returning zero

5255 ** if SQLite is not compiled with [SQLITE_ENABLE_MEMORY_MANAGEMENT].

5256 **

5257 ** See also: [sqlite3_db_release_memory()]

5258 */

5259 int sqlite3_release_memory(int);

5260

5261 /*

5262 ** CAPI3REF: Free Memory Used By A Database Connection

5263 ** METHOD: sqlite3

5264 **

5265 ** ^The sqlite3_db_release_memory(D) interface attempts to free as much heap

5266 ** memory as possible from database connection D. Unlike the

5267 ** [sqlite3_release_memory()] interface, this interface is in effect even

5268 ** when the [SQLITE_ENABLE_MEMORY_MANAGEMENT] compile-time option is

5269 ** omitted.

5270 **

5271 ** See also: [sqlite3_release_memory()]

5272 */

5273 int sqlite3_db_release_memory(sqlite3*);

5274

5275 /*

5276 ** CAPI3REF: Impose A Limit On Heap Size

5277 **

5278 ** ^The sqlite3_soft_heap_limit64() interface sets and/or queries the

5279 ** soft limit on the amount of heap memory that may be allocated by SQLite.

5280 ** ^SQLite strives to keep heap memory utilization below the soft heap

5281 ** limit by reducing the number of pages held in the page cache

5282 ** as heap memory usages approaches the limit.

5283 ** ^The soft heap limit is "soft" because even though SQLite strives to stay

5284 ** below the limit, it will exceed the limit rather than generate

5285 ** an [SQLITE_NOMEM] error. In other words, the soft heap limit

5286 ** is advisory only.

5287 **

5288 ** ^The return value from sqlite3_soft_heap_limit64() is the size of

5289 ** the soft heap limit prior to the call, or negative in the case of an

5290 ** error. ^If the argument N is negative

5291 ** then no change is made to the soft heap limit. Hence, the current

5292 ** size of the soft heap limit can be determined by invoking

5293 ** sqlite3_soft_heap_limit64() with a negative argument.

5294 **

5295 ** ^If the argument N is zero then the soft heap limit is disabled.

5296 **

5297 ** ^(The soft heap limit is not enforced in the current implementation

5298 ** if one or more of following conditions are true:

5299 **

5300 ** <ul>

5301 ** <li> The soft heap limit is set to zero.

5302 ** <li> Memory accounting is disabled using a combination of the

5303 ** [sqlite3_config]([SQLITE_CONFIG_MEMSTATUS],...) start-time option and

5304 ** the [SQLITE_DEFAULT_MEMSTATUS] compile-time option.

5305 ** <li> An alternative page cache implementation is specified using

5306 ** [sqlite3_config]([SQLITE_CONFIG_PCACHE2],...).

5307 ** <li> The page cache allocates from its own memory pool supplied

5308 ** by [sqlite3_config]([SQLITE_CONFIG_PAGECACHE],...) rather than

5309 ** from the heap.

5310 ** </ul>)^

5311 **

5312 ** Beginning with SQLite version 3.7.3, the soft heap limit is enforced

5313 ** regardless of whether or not the [SQLITE_ENABLE_MEMORY_MANAGEMENT]

5314 ** compile-time option is invoked. With [SQLITE_ENABLE_MEMORY_MANAGEMENT],

5315 ** the soft heap limit is enforced on every memory allocation. Without

5316 ** [SQLITE_ENABLE_MEMORY_MANAGEMENT], the soft heap limit is only enforced

5317 ** when memory is allocated by the page cache. Testing suggests that because

5318 ** the page cache is the predominate memory user in SQLite, most

5319 ** applications will achieve adequate soft heap limit enforcement without

5320 ** the use of [SQLITE_ENABLE_MEMORY_MANAGEMENT].

5321 **

5322 ** The circumstances under which SQLite will enforce the soft heap limit may

5323 ** changes in future releases of SQLite.

5324 */

5325 sqlite3_int64 sqlite3_soft_heap_limit64(sqlite3_int64 N);

5326

5327 /*

5328 ** CAPI3REF: Deprecated Soft Heap Limit Interface

5329 ** DEPRECATED

5330 **

5331 ** This is a deprecated version of the [sqlite3_soft_heap_limit64()]

5332 ** interface. This routine is provided for historical compatibility

5333 ** only. All new applications should use the

5334 ** [sqlite3_soft_heap_limit64()] interface rather than this one.

5335 */

5336 SQLITE_DEPRECATED void sqlite3_soft_heap_limit(int N);

5337

5338

5339 /*

5340 ** CAPI3REF: Extract Metadata About A Column Of A Table

5341 ** METHOD: sqlite3

5342 **

5343 ** ^(The sqlite3_table_column_metadata(X,D,T,C,....) routine returns

5344 ** information about column C of table T in database D

5345 ** on [database connection] X.)^ ^The sqlite3_table_column_metadata()

5346 ** interface returns SQLITE_OK and fills in the non-NULL pointers in

5347 ** the final five arguments with appropriate values if the specified

5348 ** column exists. ^The sqlite3_table_column_metadata() interface returns

5349 ** SQLITE_ERROR and if the specified column does not exist.

5350 ** ^If the column-name parameter to sqlite3_table_column_metadata() is a

5351 ** NULL pointer, then this routine simply checks for the existance of the

5352 ** table and returns SQLITE_OK if the table exists and SQLITE_ERROR if it

5353 ** does not.

5354 **

5355 ** ^The column is identified by the second, third and fourth parameters to

5356 ** this function. ^(The second parameter is either the name of the database

5357 ** (i.e. "main", "temp", or an attached database) containing the specified

5358 ** table or NULL.)^ ^If it is NULL, then all attached databases are searched

5359 ** for the table using the same algorithm used by the database engine to

5360 ** resolve unqualified table references.

5361 **

5362 ** ^The third and fourth parameters to this function are the table and column

5363 ** name of the desired column, respectively.

5364 **

5365 ** ^Metadata is returned by writing to the memory locations passed as the 5th

5366 ** and subsequent parameters to this function. ^Any of these arguments may be

5367 ** NULL, in which case the corresponding element of metadata is omitted.

5368 **

5369 ** ^(<blockquote>

5370 ** <table border="1">

5371 ** <tr><th> Parameter <th> Output<br>Type <th> Description

5372 **

5373 ** <tr><td> 5th <td> const char* <td> Data type

5374 ** <tr><td> 6th <td> const char* <td> Name of default collation sequence

5375 ** <tr><td> 7th <td> int <td> True if column has a NOT NULL constraint

5376 ** <tr><td> 8th <td> int <td> True if column is part of the PRIMARY KEY

5377 ** <tr><td> 9th <td> int <td> True if column is [AUTOINCREMENT]

5378 ** </table>

5379 ** </blockquote>)^

5380 **

5381 ** ^The memory pointed to by the character pointers returned for the

5382 ** declaration type and collation sequence is valid until the next

5383 ** call to any SQLite API function.

5384 **

5385 ** ^If the specified table is actually a view, an [error code] is returned.

5386 **

5387 ** ^If the specified column is "rowid", "oid" or "_rowid_" and the table

5388 ** is not a [WITHOUT ROWID] table and an

5389 ** [INTEGER PRIMARY KEY] column has been explicitly declared, then the output

5390 ** parameters are set for the explicitly declared column. ^(If there is no

5391 ** [INTEGER PRIMARY KEY] column, then the outputs

5392 ** for the [rowid] are set as follows:

5393 **

5394 ** <pre>

5395 ** data type: "INTEGER"

5396 ** collation sequence: "BINARY"

5397 ** not null: 0

5398 ** primary key: 1

5399 ** auto increment: 0

5400 ** </pre>)^

5401 **

5402 ** ^This function causes all database schemas to be read from disk and

5403 ** parsed, if that has not already been done, and returns an error if

5404 ** any errors are encountered while loading the schema.

5405 */

5406 int sqlite3_table_column_metadata(

5407 sqlite3 db, / Connection handle */

5408 const char zDbName, / Database name or NULL */

5409 const char zTableName, / Table name */

5410 const char zColumnName, / Column name */

5411 char const *pzDataType, / OUTPUT: Declared data type */

5412 char const *pzCollSeq, / OUTPUT: Collation sequence name */

5413 int pNotNull, / OUTPUT: True if NOT NULL constraint exists */

5414 int pPrimaryKey, / OUTPUT: True if column part of PK */

5415 int pAutoinc / OUTPUT: True if column is auto-increment */

5416 );

5417

5418 /*

5419 ** CAPI3REF: Load An Extension

5420 ** METHOD: sqlite3

5421 **

5422 ** ^This interface loads an SQLite extension library from the named file.

5423 **

5424 ** ^The sqlite3_load_extension() interface attempts to load an

5425 ** [SQLite extension] library contained in the file zFile. If

5426 ** the file cannot be loaded directly, attempts are made to load

5427 ** with various operating-system specific extensions added.

5428 ** So for example, if "samplelib" cannot be loaded, then names like

5429 ** "samplelib.so" or "samplelib.dylib" or "samplelib.dll" might

5430 ** be tried also.

5431 **

5432 ** ^The entry point is zProc.

5433 ** ^(zProc may be 0, in which case SQLite will try to come up with an

5434 ** entry point name on its own. It first tries "sqlite3_extension_init".

5435 ** If that does not work, it constructs a name "sqlite3_X_init" where the

5436 ** X is consists of the lower-case equivalent of all ASCII alphabetic

5437 ** characters in the filename from the last "/" to the first following

5438 ** "." and omitting any initial "lib".)^

5439 ** ^The sqlite3_load_extension() interface returns

5440 ** [SQLITE_OK] on success and [SQLITE_ERROR] if something goes wrong.

5441 ** ^If an error occurs and pzErrMsg is not 0, then the

5442 ** [sqlite3_load_extension()] interface shall attempt to

5443 ** fill *pzErrMsg with error message text stored in memory

5444 ** obtained from [sqlite3_malloc()]. The calling function

5445 ** should free this memory by calling [sqlite3_free()].

5446 **

5447 ** ^Extension loading must be enabled using

5448 ** [sqlite3_enable_load_extension()] prior to calling this API,

5449 ** otherwise an error will be returned.

5450 **

5451 ** See also the [load_extension() SQL function].

5452 */

5453 int sqlite3_load_extension(

5454 sqlite3 db, / Load the extension into this database connection */

5455 const char zFile, / Name of the shared library containing extension */

5456 const char zProc, / Entry point. Derived from zFile if 0 */

5457 char *pzErrMsg / Put error message here if not 0 */

5458 );

5459

5460 /*

5461 ** CAPI3REF: Enable Or Disable Extension Loading

5462 ** METHOD: sqlite3

5463 **

5464 ** ^So as not to open security holes in older applications that are

5465 ** unprepared to deal with [extension loading], and as a means of disabling

5466 ** [extension loading] while evaluating user-entered SQL, the following API

5467 ** is provided to turn the [sqlite3_load_extension()] mechanism on and off.

5468 **

5469 ** ^Extension loading is off by default.

5470 ** ^Call the sqlite3_enable_load_extension() routine with onoff==1

5471 ** to turn extension loading on and call it with onoff==0 to turn

5472 ** it back off again.

5473 */

5474 int sqlite3_enable_load_extension(sqlite3 *db, int onoff);

5475

5476 /*

5477 ** CAPI3REF: Automatically Load Statically Linked Extensions

5478 **

5479 ** ^This interface causes the xEntryPoint() function to be invoked for

5480 ** each new [database connection] that is created. The idea here is that

5481 ** xEntryPoint() is the entry point for a statically linked [SQLite extension]

5482 ** that is to be automatically loaded into all new database connections.

5483 **

5484 ** ^(Even though the function prototype shows that xEntryPoint() takes

5485 ** no arguments and returns void, SQLite invokes xEntryPoint() with three

5486 ** arguments and expects and integer result as if the signature of the

5487 ** entry point where as follows:

5488 **

5489 ** <blockquote><pre>

5490 **   int xEntryPoint(

5491 **   sqlite3 *db,

5492   const char pzErrMsg,

5493 **   const struct sqlite3_api_routines *pThunk

5494 **   );

5495 ** </pre></blockquote>)^

5496 **

5497 ** If the xEntryPoint routine encounters an error, it should make *pzErrMsg

5498 ** point to an appropriate error message (obtained from [sqlite3_mprintf()])

5499 ** and return an appropriate [error code]. ^SQLite ensures that *pzErrMsg

5500 ** is NULL before calling the xEntryPoint(). ^SQLite will invoke

5501 ** [sqlite3_free()] on *pzErrMsg after xEntryPoint() returns. ^If any

5502 ** xEntryPoint() returns an error, the [sqlite3_open()], [sqlite3_open16()],

5503 ** or [sqlite3_open_v2()] call that provoked the xEntryPoint() will fail.

5504 **

5505 ** ^Calling sqlite3_auto_extension(X) with an entry point X that is already

5506 ** on the list of automatic extensions is a harmless no-op. ^No entry point

5507 ** will be called more than once for each database connection that is opened.

5508 **

5509 ** See also: [sqlite3_reset_auto_extension()]

5510 ** and [sqlite3_cancel_auto_extension()]

5511 */

5512 int sqlite3_auto_extension(void (*xEntryPoint)(void));

5513

5514 /*

5515 ** CAPI3REF: Cancel Automatic Extension Loading

5516 **

5517 ** ^The [sqlite3_cancel_auto_extension(X)] interface unregisters the

5518 ** initialization routine X that was registered using a prior call to

5519 ** [sqlite3_auto_extension(X)]. ^The [sqlite3_cancel_auto_extension(X)]

5520 ** routine returns 1 if initialization routine X was successfully

5521 ** unregistered and it returns 0 if X was not on the list of initialization

5522 ** routines.

5523 */

5524 int sqlite3_cancel_auto_extension(void (*xEntryPoint)(void));

5525

5526 /*

5527 ** CAPI3REF: Reset Automatic Extension Loading

5528 **

5529 ** ^This interface disables all automatic extensions previously

5530 ** registered using [sqlite3_auto_extension()].

5531 */

5532 void sqlite3_reset_auto_extension(void);

5533

5534 /*

5535 ** The interface to the virtual-table mechanism is currently considered

5536 ** to be experimental. The interface might change in incompatible ways.

5537 ** If this is a problem for you, do not use the interface at this time.

5538 **

5539 ** When the virtual-table mechanism stabilizes, we will declare the

5540 ** interface fixed, support it indefinitely, and remove this comment.

5541 */

5542

5543 /*

5544 ** Structures used by the virtual table interface

5545 */

5546 typedef struct sqlite3_vtab sqlite3_vtab;

5547 typedef struct sqlite3_index_info sqlite3_index_info;

5548 typedef struct sqlite3_vtab_cursor sqlite3_vtab_cursor;

5549 typedef struct sqlite3_module sqlite3_module;

5550

5551 /*

5552 ** CAPI3REF: Virtual Table Object

5553 ** KEYWORDS: sqlite3_module {virtual table module}

5554 **

5555 ** This structure, sometimes called a "virtual table module",

5556 ** defines the implementation of a [virtual tables].

5557 ** This structure consists mostly of methods for the module.

5558 **

5559 ** ^A virtual table module is created by filling in a persistent

5560 ** instance of this structure and passing a pointer to that instance

5561 ** to [sqlite3_create_module()] or [sqlite3_create_module_v2()].

5562 ** ^The registration remains valid until it is replaced by a different

5563 ** module or until the [database connection] closes. The content

5564 ** of this structure must not change while it is registered with

5565 ** any database connection.

5566 */

5567 struct sqlite3_module {

5568 int iVersion;

5569 int (xCreate)(sqlite3, void *pAux,

5570 int argc, const char constargv,

5571 sqlite3_vtab ppVTab, char);

5572 int (xConnect)(sqlite3, void *pAux,

5573 int argc, const char constargv,

5574 sqlite3_vtab ppVTab, char);

5575 int (xBestIndex)(sqlite3_vtab pVTab, sqlite3_index_info*);

5576 int (xDisconnect)(sqlite3_vtab pVTab);

5577 int (xDestroy)(sqlite3_vtab pVTab);

5578 int (xOpen)(sqlite3_vtab pVTab, sqlite3_vtab_cursor **ppCursor);

5579 int (xClose)(sqlite3_vtab_cursor);

5580 int (xFilter)(sqlite3_vtab_cursor, int idxNum, const char *idxStr,

5581 int argc, sqlite3_value **argv);

5582 int (xNext)(sqlite3_vtab_cursor);

5583 int (xEof)(sqlite3_vtab_cursor);

5584 int (xColumn)(sqlite3_vtab_cursor, sqlite3_context*, int);

5585 int (xRowid)(sqlite3_vtab_cursor, sqlite3_int64 *pRowid);

5586 int (xUpdate)(sqlite3_vtab , int, sqlite3_value *, sqlite3_int64 );

5587 int (xBegin)(sqlite3_vtab pVTab);

5588 int (xSync)(sqlite3_vtab pVTab);

5589 int (xCommit)(sqlite3_vtab pVTab);

5590 int (xRollback)(sqlite3_vtab pVTab);

5591 int (xFindFunction)(sqlite3_vtab pVtab, int nArg, const char *zName,

5592 void (*pxFunc)(sqlite3_context,int,sqlite3_value**),

5593 void **ppArg);

5594 int (xRename)(sqlite3_vtab pVtab, const char *zNew);

5595 /* The methods above are in version 1 of the sqlite_module object. Those

5596 ** below are for version 2 and greater. */

5597 int (xSavepoint)(sqlite3_vtab pVTab, int);

5598 int (xRelease)(sqlite3_vtab pVTab, int);

5599 int (xRollbackTo)(sqlite3_vtab pVTab, int);

5600 };

5601

5602 /*

5603 ** CAPI3REF: Virtual Table Indexing Information

5604 ** KEYWORDS: sqlite3_index_info

5605 **

5606 ** The sqlite3_index_info structure and its substructures is used as part

5607 ** of the [virtual table] interface to

5608 ** pass information into and receive the reply from the [xBestIndex]

5609 method of a [virtual table module]. The fields under Inputs** are the

5610 ** inputs to xBestIndex and are read-only. xBestIndex inserts its

5611 results into the Outputs** fields.

5612 **

5613 ** ^(The aConstraint[] array records WHERE clause constraints of the form:

5614 **

5615 ** <blockquote>column OP expr</blockquote>

5616 **

5617 ** where OP is =, <, <=, >, or >=.)^ ^(The particular operator is

5618 ** stored in aConstraint[].op using one of the

5619 ** [SQLITE_INDEX_CONSTRAINT_EQ \| SQLITE_INDEX_CONSTRAINT_ values].)^

5620 ** ^(The index of the column is stored in

5621 ** aConstraint[].iColumn.)^ ^(aConstraint[].usable is TRUE if the

5622 ** expr on the right-hand side can be evaluated (and thus the constraint

5623 ** is usable) and false if it cannot.)^

5624 **

5625 ** ^The optimizer automatically inverts terms of the form "expr OP column"

5626 ** and makes other simplifications to the WHERE clause in an attempt to

5627 ** get as many WHERE clause terms into the form shown above as possible.

5628 ** ^The aConstraint[] array only reports WHERE clause terms that are

5629 ** relevant to the particular virtual table being queried.

5630 **

5631 ** ^Information about the ORDER BY clause is stored in aOrderBy[].

5632 ** ^Each term of aOrderBy records a column of the ORDER BY clause.

5633 **

5634 ** The colUsed field indicates which columns of the virtual table may be

5635 ** required by the current scan. Virtual table columns are numbered from

5636 ** zero in the order in which they appear within the CREATE TABLE statement

5637 ** passed to sqlite3_declare_vtab(). For the first 63 columns (columns 0-62),

5638 ** the corresponding bit is set within the colUsed mask if the column may be

5639 ** required by SQLite. If the table has at least 64 columns and any column

5640 ** to the right of the first 63 is required, then bit 63 of colUsed is also

5641 ** set. In other words, column iCol may be required if the expression

5642 ** (colUsed & ((sqlite3_uint64)1 << (iCol>=63 ? 63 : iCol))) evaluates to

5643 ** non-zero.

5644 **

5645 ** The [xBestIndex] method must fill aConstraintUsage[] with information

5646 ** about what parameters to pass to xFilter. ^If argvIndex>0 then

5647 ** the right-hand side of the corresponding aConstraint[] is evaluated

5648 ** and becomes the argvIndex-th entry in argv. ^(If aConstraintUsage[].omit

5649 ** is true, then the constraint is assumed to be fully handled by the

5650 ** virtual table and is not checked again by SQLite.)^

5651 **

5652 ** ^The idxNum and idxPtr values are recorded and passed into the

5653 ** [xFilter] method.

5654 ** ^[sqlite3_free()] is used to free idxPtr if and only if

5655 ** needToFreeIdxPtr is true.

5656 **

5657 ** ^The orderByConsumed means that output from [xFilter]/[xNext] will occur in

5658 ** the correct order to satisfy the ORDER BY clause so that no separate

5659 ** sorting step is required.

5660 **

5661 ** ^The estimatedCost value is an estimate of the cost of a particular

5662 ** strategy. A cost of N indicates that the cost of the strategy is similar

5663 ** to a linear scan of an SQLite table with N rows. A cost of log(N)

5664 ** indicates that the expense of the operation is similar to that of a

5665 ** binary search on a unique indexed field of an SQLite table with N rows.

5666 **

5667 ** ^The estimatedRows value is an estimate of the number of rows that

5668 ** will be returned by the strategy.

5669 **

5670 ** The xBestIndex method may optionally populate the idxFlags field with a

5671 ** mask of SQLITE_INDEX_SCAN_* flags. Currently there is only one such flag -

5672 ** SQLITE_INDEX_SCAN_UNIQUE. If the xBestIndex method sets this flag, SQLite

5673 ** assumes that the strategy may visit at most one row.

5674 **

5675 ** Additionally, if xBestIndex sets the SQLITE_INDEX_SCAN_UNIQUE flag, then

5676 ** SQLite also assumes that if a call to the xUpdate() method is made as

5677 ** part of the same statement to delete or update a virtual table row and the

5678 ** implementation returns SQLITE_CONSTRAINT, then there is no need to rollback

5679 ** any database changes. In other words, if the xUpdate() returns

5680 ** SQLITE_CONSTRAINT, the database contents must be exactly as they were

5681 ** before xUpdate was called. By contrast, if SQLITE_INDEX_SCAN_UNIQUE is not

5682 ** set and xUpdate returns SQLITE_CONSTRAINT, any database changes made by

5683 ** the xUpdate method are automatically rolled back by SQLite.

5684 **

5685 ** IMPORTANT: The estimatedRows field was added to the sqlite3_index_info

5686 ** structure for SQLite version 3.8.2. If a virtual table extension is

5687 ** used with an SQLite version earlier than 3.8.2, the results of attempting

5688 ** to read or write the estimatedRows field are undefined (but are likely

5689 ** to included crashing the application). The estimatedRows field should

5690 ** therefore only be used if [sqlite3_libversion_number()] returns a

5691 ** value greater than or equal to 3008002. Similarly, the idxFlags field

5692 ** was added for version 3.9.0. It may therefore only be used if

5693 ** sqlite3_libversion_number() returns a value greater than or equal to

5694 ** 3009000.

5695 */

5696 struct sqlite3_index_info {

5697 /* Inputs */

5698 int nConstraint; /* Number of entries in aConstraint */

5699 struct sqlite3_index_constraint {

5700 int iColumn; /* Column on left-hand side of constraint */

5701 unsigned char op; /* Constraint operator */

5702 unsigned char usable; /* True if this constraint is usable */

5703 int iTermOffset; /* Used internally - xBestIndex should ignore */

5704 } aConstraint; / Table of WHERE clause constraints */

5705 int nOrderBy; /* Number of terms in the ORDER BY clause */

5706 struct sqlite3_index_orderby {

5707 int iColumn; /* Column number */

5708 unsigned char desc; /* True for DESC. False for ASC. */

5709 } aOrderBy; / The ORDER BY clause */

5710 /* Outputs */

5711 struct sqlite3_index_constraint_usage {

5712 int argvIndex; /* if >0, constraint is part of argv to xFilter */

5713 unsigned char omit; /* Do not code a test for this constraint */

5714 } *aConstraintUsage;

5715 int idxNum; /* Number used to identify the index */

5716 char idxStr; / String, possibly obtained from sqlite3_malloc */

5717 int needToFreeIdxStr; /* Free idxStr using sqlite3_free() if true */

5718 int orderByConsumed; /* True if output is already ordered */

5719 double estimatedCost; /* Estimated cost of using this index */

5720 /* Fields below are only available in SQLite 3.8.2 and later */

5721 sqlite3_int64 estimatedRows; /* Estimated number of rows returned */

5722 /* Fields below are only available in SQLite 3.9.0 and later */

5723 int idxFlags; /* Mask of SQLITE_INDEX_SCAN_* flags */

5724 /* Fields below are only available in SQLite 3.10.0 and later */

5725 sqlite3_uint64 colUsed; /* Input: Mask of columns used by statement */

5726 };

5727

5728 /*

5729 ** CAPI3REF: Virtual Table Scan Flags

5730 */

5731 #define SQLITE_INDEX_SCAN_UNIQUE 1 /* Scan visits at most 1 row */

5732

5733 /*

5734 ** CAPI3REF: Virtual Table Constraint Operator Codes

5735 **

5736 ** These macros defined the allowed values for the

5737 ** [sqlite3_index_info].aConstraint[].op field. Each value represents

5738 ** an operator that is part of a constraint term in the wHERE clause of

5739 ** a query that uses a [virtual table].

5740 */

5741 #define SQLITE_INDEX_CONSTRAINT_EQ 2

5742 #define SQLITE_INDEX_CONSTRAINT_GT 4

5743 #define SQLITE_INDEX_CONSTRAINT_LE 8

5744 #define SQLITE_INDEX_CONSTRAINT_LT 16

5745 #define SQLITE_INDEX_CONSTRAINT_GE 32

5746 #define SQLITE_INDEX_CONSTRAINT_MATCH 64

5747 #define SQLITE_INDEX_CONSTRAINT_LIKE 65

5748 #define SQLITE_INDEX_CONSTRAINT_GLOB 66

5749 #define SQLITE_INDEX_CONSTRAINT_REGEXP 67

5750

5751 /*

5752 ** CAPI3REF: Register A Virtual Table Implementation

5753 ** METHOD: sqlite3

5754 **

5755 ** ^These routines are used to register a new [virtual table module] name.

5756 ** ^Module names must be registered before

5757 ** creating a new [virtual table] using the module and before using a

5758 ** preexisting [virtual table] for the module.

5759 **

5760 ** ^The module name is registered on the [database connection] specified

5761 ** by the first parameter. ^The name of the module is given by the

5762 ** second parameter. ^The third parameter is a pointer to

5763 ** the implementation of the [virtual table module]. ^The fourth

5764 ** parameter is an arbitrary client data pointer that is passed through

5765 ** into the [xCreate] and [xConnect] methods of the virtual table module

5766 ** when a new virtual table is be being created or reinitialized.

5767 **

5768 ** ^The sqlite3_create_module_v2() interface has a fifth parameter which

5769 ** is a pointer to a destructor for the pClientData. ^SQLite will

5770 ** invoke the destructor function (if it is not NULL) when SQLite

5771 ** no longer needs the pClientData pointer. ^The destructor will also

5772 ** be invoked if the call to sqlite3_create_module_v2() fails.

5773 ** ^The sqlite3_create_module()

5774 ** interface is equivalent to sqlite3_create_module_v2() with a NULL

5775 ** destructor.

5776 */

5777 int sqlite3_create_module(

5778 sqlite3 db, / SQLite connection to register module with */

5779 const char zName, / Name of the module */

5780 const sqlite3_module p, / Methods for the module */

5781 void pClientData / Client data for xCreate/xConnect */

5782 );

5783 int sqlite3_create_module_v2(

5784 sqlite3 db, / SQLite connection to register module with */

5785 const char zName, / Name of the module */

5786 const sqlite3_module p, / Methods for the module */

5787 void pClientData, / Client data for xCreate/xConnect */

5788 void(xDestroy)(void) /* Module destructor function */

5789 );

5790

5791 /*

5792 ** CAPI3REF: Virtual Table Instance Object

5793 ** KEYWORDS: sqlite3_vtab

5794 **

5795 ** Every [virtual table module] implementation uses a subclass

5796 ** of this object to describe a particular instance

5797 ** of the [virtual table]. Each subclass will

5798 ** be tailored to the specific needs of the module implementation.

5799 ** The purpose of this superclass is to define certain fields that are

5800 ** common to all module implementations.

5801 **

5802 ** ^Virtual tables methods can set an error message by assigning a

5803 ** string obtained from [sqlite3_mprintf()] to zErrMsg. The method should

5804 ** take care that any prior string is freed by a call to [sqlite3_free()]

5805 ** prior to assigning a new string to zErrMsg. ^After the error message

5806 ** is delivered up to the client application, the string will be automatically

5807 ** freed by sqlite3_free() and the zErrMsg field will be zeroed.

5808 */

5809 struct sqlite3_vtab {

5810 const sqlite3_module pModule; / The module for this virtual table */

5811 int nRef; /* Number of open cursors */

5812 char zErrMsg; / Error message from sqlite3_mprintf() */

5813 /* Virtual table implementations will typically add additional fields */

5814 };

5815

5816 /*

5817 ** CAPI3REF: Virtual Table Cursor Object

5818 ** KEYWORDS: sqlite3_vtab_cursor {virtual table cursor}

5819 **

5820 ** Every [virtual table module] implementation uses a subclass of the

5821 ** following structure to describe cursors that point into the

5822 ** [virtual table] and are used

5823 ** to loop through the virtual table. Cursors are created using the

5824 ** [sqlite3_module.xOpen \| xOpen] method of the module and are destroyed

5825 ** by the [sqlite3_module.xClose \| xClose] method. Cursors are used

5826 ** by the [xFilter], [xNext], [xEof], [xColumn], and [xRowid] methods

5827 ** of the module. Each module implementation will define

5828 ** the content of a cursor structure to suit its own needs.

5829 **

5830 ** This superclass exists in order to define fields of the cursor that

5831 ** are common to all implementations.

5832 */

5833 struct sqlite3_vtab_cursor {

5834 sqlite3_vtab pVtab; / Virtual table of this cursor */

5835 /* Virtual table implementations will typically add additional fields */

5836 };

5837

5838 /*

5839 ** CAPI3REF: Declare The Schema Of A Virtual Table

5840 **

5841 ** ^The [xCreate] and [xConnect] methods of a

5842 ** [virtual table module] call this interface

5843 ** to declare the format (the names and datatypes of the columns) of

5844 ** the virtual tables they implement.

5845 */

5846 int sqlite3_declare_vtab(sqlite3, const char zSQL);

5847

5848 /*

5849 ** CAPI3REF: Overload A Function For A Virtual Table

5850 ** METHOD: sqlite3

5851 **

5852 ** ^(Virtual tables can provide alternative implementations of functions

5853 ** using the [xFindFunction] method of the [virtual table module].

5854 ** But global versions of those functions

5855 ** must exist in order to be overloaded.)^

5856 **

5857 ** ^(This API makes sure a global version of a function with a particular

5858 ** name and number of parameters exists. If no such function exists

5859 ** before this API is called, a new function is created.)^ ^The implementation

5860 ** of the new function always causes an exception to be thrown. So

5861 ** the new function is not good for anything by itself. Its only

5862 ** purpose is to be a placeholder function that can be overloaded

5863 ** by a [virtual table].

5864 */

5865 int sqlite3_overload_function(sqlite3, const char zFuncName, int nArg);

5866

5867 /*

5868 ** The interface to the virtual-table mechanism defined above (back up

5869 ** to a comment remarkably similar to this one) is currently considered

5870 ** to be experimental. The interface might change in incompatible ways.

5871 ** If this is a problem for you, do not use the interface at this time.

5872 **

5873 ** When the virtual-table mechanism stabilizes, we will declare the

5874 ** interface fixed, support it indefinitely, and remove this comment.

5875 */

5876

5877 /*

5878 ** CAPI3REF: A Handle To An Open BLOB

5879 ** KEYWORDS: {BLOB handle} {BLOB handles}

5880 **

5881 ** An instance of this object represents an open BLOB on which

5882 ** [sqlite3_blob_open \| incremental BLOB I/O] can be performed.

5883 ** ^Objects of this type are created by [sqlite3_blob_open()]

5884 ** and destroyed by [sqlite3_blob_close()].

5885 ** ^The [sqlite3_blob_read()] and [sqlite3_blob_write()] interfaces

5886 ** can be used to read or write small subsections of the BLOB.

5887 ** ^The [sqlite3_blob_bytes()] interface returns the size of the BLOB in bytes.

5888 */

5889 typedef struct sqlite3_blob sqlite3_blob;

5890

5891 /*

5892 ** CAPI3REF: Open A BLOB For Incremental I/O

5893 ** METHOD: sqlite3

5894 ** CONSTRUCTOR: sqlite3_blob

5895 **

5896 ** ^(This interfaces opens a [BLOB handle \| handle] to the BLOB located

5897 ** in row iRow, column zColumn, table zTable in database zDb;

5898 ** in other words, the same BLOB that would be selected by:

5899 **

5900 ** <pre>

5901 ** SELECT zColumn FROM zDb.zTable WHERE [rowid] = iRow;

5902 ** </pre>)^

5903 **

5904 ** ^(Parameter zDb is not the filename that contains the database, but

5905 ** rather the symbolic name of the database. For attached databases, this is

5906 ** the name that appears after the AS keyword in the [ATTACH] statement.

5907 ** For the main database file, the database name is "main". For TEMP

5908 ** tables, the database name is "temp".)^

5909 **

5910 ** ^If the flags parameter is non-zero, then the BLOB is opened for read

5911 ** and write access. ^If the flags parameter is zero, the BLOB is opened for

5912 ** read-only access.

5913 **

5914 ** ^(On success, [SQLITE_OK] is returned and the new [BLOB handle] is stored

5915 ** in *ppBlob. Otherwise an [error code] is returned and, unless the error

5916 ** code is SQLITE_MISUSE, *ppBlob is set to NULL.)^ ^This means that, provided

5917 ** the API is not misused, it is always safe to call [sqlite3_blob_close()]

5918 ** on *ppBlob after this function it returns.

5919 **

5920 ** This function fails with SQLITE_ERROR if any of the following are true:

5921 ** <ul>

5922 ** <li> ^(Database zDb does not exist)^,

5923 ** <li> ^(Table zTable does not exist within database zDb)^,

5924 ** <li> ^(Table zTable is a WITHOUT ROWID table)^,

5925 ** <li> ^(Column zColumn does not exist)^,

5926 ** <li> ^(Row iRow is not present in the table)^,

5927 ** <li> ^(The specified column of row iRow contains a value that is not

5928 ** a TEXT or BLOB value)^,

5929 ** <li> ^(Column zColumn is part of an index, PRIMARY KEY or UNIQUE

5930 ** constraint and the blob is being opened for read/write access)^,

5931 ** <li> ^([foreign key constraints \| Foreign key constraints] are enabled,

5932 ** column zColumn is part of a [child key] definition and the blob is

5933 ** being opened for read/write access)^.

5934 ** </ul>

5935 **

5936 ** ^Unless it returns SQLITE_MISUSE, this function sets the

5937 ** [database connection] error code and message accessible via

5938 ** [sqlite3_errcode()] and [sqlite3_errmsg()] and related functions.

5939 **

5940 **

5941 ** ^(If the row that a BLOB handle points to is modified by an

5942 ** [UPDATE], [DELETE], or by [ON CONFLICT] side-effects

5943 ** then the BLOB handle is marked as "expired".

5944 ** This is true if any column of the row is changed, even a column

5945 ** other than the one the BLOB handle is open on.)^

5946 ** ^Calls to [sqlite3_blob_read()] and [sqlite3_blob_write()] for

5947 ** an expired BLOB handle fail with a return code of [SQLITE_ABORT].

5948 ** ^(Changes written into a BLOB prior to the BLOB expiring are not

5949 ** rolled back by the expiration of the BLOB. Such changes will eventually

5950 ** commit if the transaction continues to completion.)^

5951 **

5952 ** ^Use the [sqlite3_blob_bytes()] interface to determine the size of

5953 ** the opened blob. ^The size of a blob may not be changed by this

5954 ** interface. Use the [UPDATE] SQL command to change the size of a

5955 ** blob.

5956 **

5957 ** ^The [sqlite3_bind_zeroblob()] and [sqlite3_result_zeroblob()] interfaces

5958 ** and the built-in [zeroblob] SQL function may be used to create a

5959 ** zero-filled blob to read or write using the incremental-blob interface.

5960 **

5961 ** To avoid a resource leak, every open [BLOB handle] should eventually

5962 ** be released by a call to [sqlite3_blob_close()].

5963 */

5964 int sqlite3_blob_open(

5965 sqlite3*,

5966 const char *zDb,

5967 const char *zTable,

5968 const char *zColumn,

5969 sqlite3_int64 iRow,

5970 int flags,

5971 sqlite3_blob **ppBlob

5972 );

5973

5974 /*

5975 ** CAPI3REF: Move a BLOB Handle to a New Row

5976 ** METHOD: sqlite3_blob

5977 **

5978 ** ^This function is used to move an existing blob handle so that it points

5979 ** to a different row of the same database table. ^The new row is identified

5980 ** by the rowid value passed as the second argument. Only the row can be

5981 ** changed. ^The database, table and column on which the blob handle is open

5982 ** remain the same. Moving an existing blob handle to a new row can be

5983 ** faster than closing the existing handle and opening a new one.

5984 **

5985 ** ^(The new row must meet the same criteria as for [sqlite3_blob_open()] -

5986 ** it must exist and there must be either a blob or text value stored in

5987 ** the nominated column.)^ ^If the new row is not present in the table, or if

5988 ** it does not contain a blob or text value, or if another error occurs, an

5989 ** SQLite error code is returned and the blob handle is considered aborted.

5990 ** ^All subsequent calls to [sqlite3_blob_read()], [sqlite3_blob_write()] or

5991 ** [sqlite3_blob_reopen()] on an aborted blob handle immediately return

5992 ** SQLITE_ABORT. ^Calling [sqlite3_blob_bytes()] on an aborted blob handle

5993 ** always returns zero.

5994 **

5995 ** ^This function sets the database handle error code and message.

5996 */

5997 int sqlite3_blob_reopen(sqlite3_blob *, sqlite3_int64);

5998

5999 /*

6000 ** CAPI3REF: Close A BLOB Handle

6001 ** DESTRUCTOR: sqlite3_blob

6002 **

6003 ** ^This function closes an open [BLOB handle]. ^(The BLOB handle is closed

6004 ** unconditionally. Even if this routine returns an error code, the

6005 ** handle is still closed.)^

6006 **

6007 ** ^If the blob handle being closed was opened for read-write access, and if

6008 ** the database is in auto-commit mode and there are no other open read-write

6009 ** blob handles or active write statements, the current transaction is

6010 ** committed. ^If an error occurs while committing the transaction, an error

6011 ** code is returned and the transaction rolled back.

6012 **

6013 ** Calling this function with an argument that is not a NULL pointer or an

6014 ** open blob handle results in undefined behaviour. ^Calling this routine

6015 ** with a null pointer (such as would be returned by a failed call to

6016 ** [sqlite3_blob_open()]) is a harmless no-op. ^Otherwise, if this function

6017 ** is passed a valid open blob handle, the values returned by the

6018 ** sqlite3_errcode() and sqlite3_errmsg() functions are set before returning.

6019 */

6020 int sqlite3_blob_close(sqlite3_blob *);

6021

6022 /*

6023 ** CAPI3REF: Return The Size Of An Open BLOB

6024 ** METHOD: sqlite3_blob

6025 **

6026 ** ^Returns the size in bytes of the BLOB accessible via the

6027 ** successfully opened [BLOB handle] in its only argument. ^The

6028 ** incremental blob I/O routines can only read or overwriting existing

6029 ** blob content; they cannot change the size of a blob.

6030 **

6031 ** This routine only works on a [BLOB handle] which has been created

6032 ** by a prior successful call to [sqlite3_blob_open()] and which has not

6033 ** been closed by [sqlite3_blob_close()]. Passing any other pointer in

6034 ** to this routine results in undefined and probably undesirable behavior.

6035 */

6036 int sqlite3_blob_bytes(sqlite3_blob *);

6037

6038 /*

6039 ** CAPI3REF: Read Data From A BLOB Incrementally

6040 ** METHOD: sqlite3_blob

6041 **

6042 ** ^(This function is used to read data from an open [BLOB handle] into a

6043 ** caller-supplied buffer. N bytes of data are copied into buffer Z

6044 ** from the open BLOB, starting at offset iOffset.)^

6045 **

6046 ** ^If offset iOffset is less than N bytes from the end of the BLOB,

6047 ** [SQLITE_ERROR] is returned and no data is read. ^If N or iOffset is

6048 ** less than zero, [SQLITE_ERROR] is returned and no data is read.

6049 ** ^The size of the blob (and hence the maximum value of N+iOffset)

6050 ** can be determined using the [sqlite3_blob_bytes()] interface.

6051 **

6052 ** ^An attempt to read from an expired [BLOB handle] fails with an

6053 ** error code of [SQLITE_ABORT].

6054 **

6055 ** ^(On success, sqlite3_blob_read() returns SQLITE_OK.

6056 ** Otherwise, an [error code] or an [extended error code] is returned.)^

6057 **

6058 ** This routine only works on a [BLOB handle] which has been created

6059 ** by a prior successful call to [sqlite3_blob_open()] and which has not

6060 ** been closed by [sqlite3_blob_close()]. Passing any other pointer in

6061 ** to this routine results in undefined and probably undesirable behavior.

6062 **

6063 ** See also: [sqlite3_blob_write()].

6064 */

6065 int sqlite3_blob_read(sqlite3_blob , void Z, int N, int iOffset);

6066

6067 /*

6068 ** CAPI3REF: Write Data Into A BLOB Incrementally

6069 ** METHOD: sqlite3_blob

6070 **

6071 ** ^(This function is used to write data into an open [BLOB handle] from a

6072 ** caller-supplied buffer. N bytes of data are copied from the buffer Z

6073 ** into the open BLOB, starting at offset iOffset.)^

6074 **

6075 ** ^(On success, sqlite3_blob_write() returns SQLITE_OK.

6076 ** Otherwise, an [error code] or an [extended error code] is returned.)^

6077 ** ^Unless SQLITE_MISUSE is returned, this function sets the

6078 ** [database connection] error code and message accessible via

6079 ** [sqlite3_errcode()] and [sqlite3_errmsg()] and related functions.

6080 **

6081 ** ^If the [BLOB handle] passed as the first argument was not opened for

6082 ** writing (the flags parameter to [sqlite3_blob_open()] was zero),

6083 ** this function returns [SQLITE_READONLY].

6084 **

6085 ** This function may only modify the contents of the BLOB; it is

6086 ** not possible to increase the size of a BLOB using this API.

6087 ** ^If offset iOffset is less than N bytes from the end of the BLOB,

6088 ** [SQLITE_ERROR] is returned and no data is written. The size of the

6089 ** BLOB (and hence the maximum value of N+iOffset) can be determined

6090 ** using the [sqlite3_blob_bytes()] interface. ^If N or iOffset are less

6091 ** than zero [SQLITE_ERROR] is returned and no data is written.

6092 **

6093 ** ^An attempt to write to an expired [BLOB handle] fails with an

6094 ** error code of [SQLITE_ABORT]. ^Writes to the BLOB that occurred

6095 ** before the [BLOB handle] expired are not rolled back by the

6096 ** expiration of the handle, though of course those changes might

6097 ** have been overwritten by the statement that expired the BLOB handle

6098 ** or by other independent statements.

6099 **

6100 ** This routine only works on a [BLOB handle] which has been created

6101 ** by a prior successful call to [sqlite3_blob_open()] and which has not

6102 ** been closed by [sqlite3_blob_close()]. Passing any other pointer in

6103 ** to this routine results in undefined and probably undesirable behavior.

6104 **

6105 ** See also: [sqlite3_blob_read()].

6106 */

6107 int sqlite3_blob_write(sqlite3_blob , const void z, int n, int iOffset);

6108

6109 /*

6110 ** CAPI3REF: Virtual File System Objects

6111 **

6112 ** A virtual filesystem (VFS) is an [sqlite3_vfs] object

6113 ** that SQLite uses to interact

6114 ** with the underlying operating system. Most SQLite builds come with a

6115 ** single default VFS that is appropriate for the host computer.

6116 ** New VFSes can be registered and existing VFSes can be unregistered.

6117 ** The following interfaces are provided.

6118 **

6119 ** ^The sqlite3_vfs_find() interface returns a pointer to a VFS given its name.

6120 ** ^Names are case sensitive.

6121 ** ^Names are zero-terminated UTF-8 strings.

6122 ** ^If there is no match, a NULL pointer is returned.

6123 ** ^If zVfsName is NULL then the default VFS is returned.

6124 **

6125 ** ^New VFSes are registered with sqlite3_vfs_register().

6126 ** ^Each new VFS becomes the default VFS if the makeDflt flag is set.

6127 ** ^The same VFS can be registered multiple times without injury.

6128 ** ^To make an existing VFS into the default VFS, register it again

6129 ** with the makeDflt flag set. If two different VFSes with the

6130 ** same name are registered, the behavior is undefined. If a

6131 ** VFS is registered with a name that is NULL or an empty string,

6132 ** then the behavior is undefined.

6133 **

6134 ** ^Unregister a VFS with the sqlite3_vfs_unregister() interface.

6135 ** ^(If the default VFS is unregistered, another VFS is chosen as

6136 ** the default. The choice for the new VFS is arbitrary.)^

6137 */

6138 sqlite3_vfs sqlite3_vfs_find(const char zVfsName);

6139 int sqlite3_vfs_register(sqlite3_vfs*, int makeDflt);

6140 int sqlite3_vfs_unregister(sqlite3_vfs*);

6141

6142 /*

6143 ** CAPI3REF: Mutexes

6144 **

6145 ** The SQLite core uses these routines for thread

6146 ** synchronization. Though they are intended for internal

6147 ** use by SQLite, code that links against SQLite is

6148 ** permitted to use any of these routines.

6149 **

6150 ** The SQLite source code contains multiple implementations

6151 ** of these mutex routines. An appropriate implementation

6152 ** is selected automatically at compile-time. The following

6153 ** implementations are available in the SQLite core:

6154 **

6155 ** <ul>

6156 ** <li> SQLITE_MUTEX_PTHREADS

6157 ** <li> SQLITE_MUTEX_W32

6158 ** <li> SQLITE_MUTEX_NOOP

6159 ** </ul>

6160 **

6161 ** The SQLITE_MUTEX_NOOP implementation is a set of routines

6162 ** that does no real locking and is appropriate for use in

6163 ** a single-threaded application. The SQLITE_MUTEX_PTHREADS and

6164 ** SQLITE_MUTEX_W32 implementations are appropriate for use on Unix

6165 ** and Windows.

6166 **

6167 ** If SQLite is compiled with the SQLITE_MUTEX_APPDEF preprocessor

6168 ** macro defined (with "-DSQLITE_MUTEX_APPDEF=1"), then no mutex

6169 ** implementation is included with the library. In this case the

6170 ** application must supply a custom mutex implementation using the

6171 ** [SQLITE_CONFIG_MUTEX] option of the sqlite3_config() function

6172 ** before calling sqlite3_initialize() or any other public sqlite3_

6173 ** function that calls sqlite3_initialize().

6174 **

6175 ** ^The sqlite3_mutex_alloc() routine allocates a new

6176 ** mutex and returns a pointer to it. ^The sqlite3_mutex_alloc()

6177 ** routine returns NULL if it is unable to allocate the requested

6178 ** mutex. The argument to sqlite3_mutex_alloc() must one of these

6179 ** integer constants:

6180 **

6181 ** <ul>

6182 ** <li> SQLITE_MUTEX_FAST

6183 ** <li> SQLITE_MUTEX_RECURSIVE

6184 ** <li> SQLITE_MUTEX_STATIC_MASTER

6185 ** <li> SQLITE_MUTEX_STATIC_MEM

6186 ** <li> SQLITE_MUTEX_STATIC_OPEN

6187 ** <li> SQLITE_MUTEX_STATIC_PRNG

6188 ** <li> SQLITE_MUTEX_STATIC_LRU

6189 ** <li> SQLITE_MUTEX_STATIC_PMEM

6190 ** <li> SQLITE_MUTEX_STATIC_APP1

6191 ** <li> SQLITE_MUTEX_STATIC_APP2

6192 ** <li> SQLITE_MUTEX_STATIC_APP3

6193 ** <li> SQLITE_MUTEX_STATIC_VFS1

6194 ** <li> SQLITE_MUTEX_STATIC_VFS2

6195 ** <li> SQLITE_MUTEX_STATIC_VFS3

6196 ** </ul>

6197 **

6198 ** ^The first two constants (SQLITE_MUTEX_FAST and SQLITE_MUTEX_RECURSIVE)

6199 ** cause sqlite3_mutex_alloc() to create

6200 ** a new mutex. ^The new mutex is recursive when SQLITE_MUTEX_RECURSIVE

6201 ** is used but not necessarily so when SQLITE_MUTEX_FAST is used.

6202 ** The mutex implementation does not need to make a distinction

6203 ** between SQLITE_MUTEX_RECURSIVE and SQLITE_MUTEX_FAST if it does

6204 ** not want to. SQLite will only request a recursive mutex in

6205 ** cases where it really needs one. If a faster non-recursive mutex

6206 ** implementation is available on the host platform, the mutex subsystem

6207 ** might return such a mutex in response to SQLITE_MUTEX_FAST.

6208 **

6209 ** ^The other allowed parameters to sqlite3_mutex_alloc() (anything other

6210 ** than SQLITE_MUTEX_FAST and SQLITE_MUTEX_RECURSIVE) each return

6211 ** a pointer to a static preexisting mutex. ^Nine static mutexes are

6212 ** used by the current version of SQLite. Future versions of SQLite

6213 ** may add additional static mutexes. Static mutexes are for internal

6214 ** use by SQLite only. Applications that use SQLite mutexes should

6215 ** use only the dynamic mutexes returned by SQLITE_MUTEX_FAST or

6216 ** SQLITE_MUTEX_RECURSIVE.

6217 **

6218 ** ^Note that if one of the dynamic mutex parameters (SQLITE_MUTEX_FAST

6219 ** or SQLITE_MUTEX_RECURSIVE) is used then sqlite3_mutex_alloc()

6220 ** returns a different mutex on every call. ^For the static

6221 ** mutex types, the same mutex is returned on every call that has

6222 ** the same type number.

6223 **

6224 ** ^The sqlite3_mutex_free() routine deallocates a previously

6225 ** allocated dynamic mutex. Attempting to deallocate a static

6226 ** mutex results in undefined behavior.

6227 **

6228 ** ^The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt

6229 ** to enter a mutex. ^If another thread is already within the mutex,

6230 ** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return

6231 ** SQLITE_BUSY. ^The sqlite3_mutex_try() interface returns [SQLITE_OK]

6232 ** upon successful entry. ^(Mutexes created using

6233 ** SQLITE_MUTEX_RECURSIVE can be entered multiple times by the same thread.

6234 ** In such cases, the

6235 ** mutex must be exited an equal number of times before another thread

6236 ** can enter.)^ If the same thread tries to enter any mutex other

6237 ** than an SQLITE_MUTEX_RECURSIVE more than once, the behavior is undefined.

6238 **

6239 ** ^(Some systems (for example, Windows 95) do not support the operation

6240 ** implemented by sqlite3_mutex_try(). On those systems, sqlite3_mutex_try()

6241 ** will always return SQLITE_BUSY. The SQLite core only ever uses

6242 ** sqlite3_mutex_try() as an optimization so this is acceptable

6243 ** behavior.)^

6244 **

6245 ** ^The sqlite3_mutex_leave() routine exits a mutex that was

6246 ** previously entered by the same thread. The behavior

6247 ** is undefined if the mutex is not currently entered by the

6248 ** calling thread or is not currently allocated.

6249 **

6250 ** ^If the argument to sqlite3_mutex_enter(), sqlite3_mutex_try(), or

6251 ** sqlite3_mutex_leave() is a NULL pointer, then all three routines

6252 ** behave as no-ops.

6253 **

6254 ** See also: [sqlite3_mutex_held()] and [sqlite3_mutex_notheld()].

6255 */

6256 sqlite3_mutex *sqlite3_mutex_alloc(int);

6257 void sqlite3_mutex_free(sqlite3_mutex*);

6258 void sqlite3_mutex_enter(sqlite3_mutex*);

6259 int sqlite3_mutex_try(sqlite3_mutex*);

6260 void sqlite3_mutex_leave(sqlite3_mutex*);

6261

6262 /*

6263 ** CAPI3REF: Mutex Methods Object

6264 **

6265 ** An instance of this structure defines the low-level routines

6266 ** used to allocate and use mutexes.

6267 **

6268 ** Usually, the default mutex implementations provided by SQLite are

6269 ** sufficient, however the application has the option of substituting a custom

6270 ** implementation for specialized deployments or systems for which SQLite

6271 ** does not provide a suitable implementation. In this case, the application

6272 ** creates and populates an instance of this structure to pass

6273 ** to sqlite3_config() along with the [SQLITE_CONFIG_MUTEX] option.

6274 ** Additionally, an instance of this structure can be used as an

6275 ** output variable when querying the system for the current mutex

6276 ** implementation, using the [SQLITE_CONFIG_GETMUTEX] option.

6277 **

6278 ** ^The xMutexInit method defined by this structure is invoked as

6279 ** part of system initialization by the sqlite3_initialize() function.

6280 ** ^The xMutexInit routine is called by SQLite exactly once for each

6281 ** effective call to [sqlite3_initialize()].

6282 **

6283 ** ^The xMutexEnd method defined by this structure is invoked as

6284 ** part of system shutdown by the sqlite3_shutdown() function. The

6285 ** implementation of this method is expected to release all outstanding

6286 ** resources obtained by the mutex methods implementation, especially

6287 ** those obtained by the xMutexInit method. ^The xMutexEnd()

6288 ** interface is invoked exactly once for each call to [sqlite3_shutdown()].

6289 **

6290 ** ^(The remaining seven methods defined by this structure (xMutexAlloc,

6291 ** xMutexFree, xMutexEnter, xMutexTry, xMutexLeave, xMutexHeld and

6292 ** xMutexNotheld) implement the following interfaces (respectively):

6293 **

6294 ** <ul>

6295 ** <li> [sqlite3_mutex_alloc()] </li>

6296 ** <li> [sqlite3_mutex_free()] </li>

6297 ** <li> [sqlite3_mutex_enter()] </li>

6298 ** <li> [sqlite3_mutex_try()] </li>

6299 ** <li> [sqlite3_mutex_leave()] </li>

6300 ** <li> [sqlite3_mutex_held()] </li>

6301 ** <li> [sqlite3_mutex_notheld()] </li>

6302 ** </ul>)^

6303 **

6304 ** The only difference is that the public sqlite3_XXX functions enumerated

6305 ** above silently ignore any invocations that pass a NULL pointer instead

6306 ** of a valid mutex handle. The implementations of the methods defined

6307 ** by this structure are not required to handle this case, the results

6308 ** of passing a NULL pointer instead of a valid mutex handle are undefined

6309 ** (i.e. it is acceptable to provide an implementation that segfaults if

6310 ** it is passed a NULL pointer).

6311 **

6312 ** The xMutexInit() method must be threadsafe. It must be harmless to

6313 ** invoke xMutexInit() multiple times within the same process and without

6314 ** intervening calls to xMutexEnd(). Second and subsequent calls to

6315 ** xMutexInit() must be no-ops.

6316 **

6317 ** xMutexInit() must not use SQLite memory allocation ([sqlite3_malloc()]

6318 ** and its associates). Similarly, xMutexAlloc() must not use SQLite memory

6319 ** allocation for a static mutex. ^However xMutexAlloc() may use SQLite

6320 ** memory allocation for a fast or recursive mutex.

6321 **

6322 ** ^SQLite will invoke the xMutexEnd() method when [sqlite3_shutdown()] is

6323 ** called, but only if the prior call to xMutexInit returned SQLITE_OK.

6324 ** If xMutexInit fails in any way, it is expected to clean up after itself

6325 ** prior to returning.

6326 */

6327 typedef struct sqlite3_mutex_methods sqlite3_mutex_methods;

6328 struct sqlite3_mutex_methods {

6329 int (*xMutexInit)(void);

6330 int (*xMutexEnd)(void);

6331 sqlite3_mutex (xMutexAlloc)(int);

6332 void (xMutexFree)(sqlite3_mutex );

6333 void (xMutexEnter)(sqlite3_mutex );

6334 int (xMutexTry)(sqlite3_mutex );

6335 void (xMutexLeave)(sqlite3_mutex );

6336 int (xMutexHeld)(sqlite3_mutex );

6337 int (xMutexNotheld)(sqlite3_mutex );

6338 };

6339

6340 /*

6341 ** CAPI3REF: Mutex Verification Routines

6342 **

6343 ** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routines

6344 ** are intended for use inside assert() statements. The SQLite core

6345 ** never uses these routines except inside an assert() and applications

6346 ** are advised to follow the lead of the core. The SQLite core only

6347 ** provides implementations for these routines when it is compiled

6348 ** with the SQLITE_DEBUG flag. External mutex implementations

6349 ** are only required to provide these routines if SQLITE_DEBUG is

6350 ** defined and if NDEBUG is not defined.

6351 **

6352 ** These routines should return true if the mutex in their argument

6353 ** is held or not held, respectively, by the calling thread.

6354 **

6355 ** The implementation is not required to provide versions of these

6356 ** routines that actually work. If the implementation does not provide working

6357 ** versions of these routines, it should at least provide stubs that always

6358 ** return true so that one does not get spurious assertion failures.

6359 **

6360 ** If the argument to sqlite3_mutex_held() is a NULL pointer then

6361 ** the routine should return 1. This seems counter-intuitive since

6362 ** clearly the mutex cannot be held if it does not exist. But

6363 ** the reason the mutex does not exist is because the build is not

6364 ** using mutexes. And we do not want the assert() containing the

6365 ** call to sqlite3_mutex_held() to fail, so a non-zero return is

6366 ** the appropriate thing to do. The sqlite3_mutex_notheld()

6367 ** interface should also return 1 when given a NULL pointer.

6368 */

6369 #ifndef NDEBUG

6370 int sqlite3_mutex_held(sqlite3_mutex*);

6371 int sqlite3_mutex_notheld(sqlite3_mutex*);

6372 #endif

6373

6374 /*

6375 ** CAPI3REF: Mutex Types

6376 **

6377 ** The [sqlite3_mutex_alloc()] interface takes a single argument

6378 ** which is one of these integer constants.

6379 **

6380 ** The set of static mutexes may change from one SQLite release to the

6381 ** next. Applications that override the built-in mutex logic must be

6382 ** prepared to accommodate additional static mutexes.

6383 */

6384 #define SQLITE_MUTEX_FAST 0

6385 #define SQLITE_MUTEX_RECURSIVE 1

6386 #define SQLITE_MUTEX_STATIC_MASTER 2

6387 #define SQLITE_MUTEX_STATIC_MEM 3 /* sqlite3_malloc() */

6388 #define SQLITE_MUTEX_STATIC_MEM2 4 /* NOT USED */

6389 #define SQLITE_MUTEX_STATIC_OPEN 4 /* sqlite3BtreeOpen() */

6390 #define SQLITE_MUTEX_STATIC_PRNG 5 /* sqlite3_random() */

6391 #define SQLITE_MUTEX_STATIC_LRU 6 /* lru page list */

6392 #define SQLITE_MUTEX_STATIC_LRU2 7 /* NOT USED */

6393 #define SQLITE_MUTEX_STATIC_PMEM 7 /* sqlite3PageMalloc() */

6394 #define SQLITE_MUTEX_STATIC_APP1 8 /* For use by application */

6395 #define SQLITE_MUTEX_STATIC_APP2 9 /* For use by application */

6396 #define SQLITE_MUTEX_STATIC_APP3 10 /* For use by application */

6397 #define SQLITE_MUTEX_STATIC_VFS1 11 /* For use by built-in VFS */

6398 #define SQLITE_MUTEX_STATIC_VFS2 12 /* For use by extension VFS */

6399 #define SQLITE_MUTEX_STATIC_VFS3 13 /* For use by application VFS */

6400

6401 /*

6402 ** CAPI3REF: Retrieve the mutex for a database connection

6403 ** METHOD: sqlite3

6404 **

6405 ** ^This interface returns a pointer the [sqlite3_mutex] object that

6406 ** serializes access to the [database connection] given in the argument

6407 ** when the [threading mode] is Serialized.

6408 ** ^If the [threading mode] is Single-thread or Multi-thread then this

6409 ** routine returns a NULL pointer.

6410 */

6411 sqlite3_mutex sqlite3_db_mutex(sqlite3);

6412

6413 /*

6414 ** CAPI3REF: Low-Level Control Of Database Files

6415 ** METHOD: sqlite3

6416 **

6417 ** ^The [sqlite3_file_control()] interface makes a direct call to the

6418 ** xFileControl method for the [sqlite3_io_methods] object associated

6419 ** with a particular database identified by the second argument. ^The

6420 ** name of the database is "main" for the main database or "temp" for the

6421 ** TEMP database, or the name that appears after the AS keyword for

6422 ** databases that are added using the [ATTACH] SQL command.

6423 ** ^A NULL pointer can be used in place of "main" to refer to the

6424 ** main database file.

6425 ** ^The third and fourth parameters to this routine

6426 ** are passed directly through to the second and third parameters of

6427 ** the xFileControl method. ^The return value of the xFileControl

6428 ** method becomes the return value of this routine.

6429 **

6430 ** ^The SQLITE_FCNTL_FILE_POINTER value for the op parameter causes

6431 ** a pointer to the underlying [sqlite3_file] object to be written into

6432 ** the space pointed to by the 4th parameter. ^The SQLITE_FCNTL_FILE_POINTER

6433 ** case is a short-circuit path which does not actually invoke the

6434 ** underlying sqlite3_io_methods.xFileControl method.

6435 **

6436 ** ^If the second parameter (zDbName) does not match the name of any

6437 ** open database file, then SQLITE_ERROR is returned. ^This error

6438 ** code is not remembered and will not be recalled by [sqlite3_errcode()]

6439 ** or [sqlite3_errmsg()]. The underlying xFileControl method might

6440 ** also return SQLITE_ERROR. There is no way to distinguish between

6441 ** an incorrect zDbName and an SQLITE_ERROR return from the underlying

6442 ** xFileControl method.

6443 **

6444 ** See also: [SQLITE_FCNTL_LOCKSTATE]

6445 */

6446 int sqlite3_file_control(sqlite3, const char zDbName, int op, void*);

6447

6448 /*

6449 ** CAPI3REF: Testing Interface

6450 **

6451 ** ^The sqlite3_test_control() interface is used to read out internal

6452 ** state of SQLite and to inject faults into SQLite for testing

6453 ** purposes. ^The first parameter is an operation code that determines

6454 ** the number, meaning, and operation of all subsequent parameters.

6455 **

6456 ** This interface is not for use by applications. It exists solely

6457 ** for verifying the correct operation of the SQLite library. Depending

6458 ** on how the SQLite library is compiled, this interface might not exist.

6459 **

6460 ** The details of the operation codes, their meanings, the parameters

6461 ** they take, and what they do are all subject to change without notice.

6462 ** Unlike most of the SQLite API, this function is not guaranteed to

6463 ** operate consistently from one release to the next.

6464 */

6465 int sqlite3_test_control(int op, ...);

6466

6467 /*

6468 ** CAPI3REF: Testing Interface Operation Codes

6469 **

6470 ** These constants are the valid operation code parameters used

6471 ** as the first argument to [sqlite3_test_control()].

6472 **

6473 ** These parameters and their meanings are subject to change

6474 ** without notice. These values are for testing purposes only.

6475 ** Applications should not use any of these parameters or the

6476 ** [sqlite3_test_control()] interface.

6477 */

6478 #define SQLITE_TESTCTRL_FIRST 5

6479 #define SQLITE_TESTCTRL_PRNG_SAVE 5

6480 #define SQLITE_TESTCTRL_PRNG_RESTORE 6

6481 #define SQLITE_TESTCTRL_PRNG_RESET 7

6482 #define SQLITE_TESTCTRL_BITVEC_TEST 8

6483 #define SQLITE_TESTCTRL_FAULT_INSTALL 9

6484 #define SQLITE_TESTCTRL_BENIGN_MALLOC_HOOKS 10

6485 #define SQLITE_TESTCTRL_PENDING_BYTE 11

6486 #define SQLITE_TESTCTRL_ASSERT 12

6487 #define SQLITE_TESTCTRL_ALWAYS 13

6488 #define SQLITE_TESTCTRL_RESERVE 14

6489 #define SQLITE_TESTCTRL_OPTIMIZATIONS 15

6490 #define SQLITE_TESTCTRL_ISKEYWORD 16

6491 #define SQLITE_TESTCTRL_SCRATCHMALLOC 17

6492 #define SQLITE_TESTCTRL_LOCALTIME_FAULT 18

6493 #define SQLITE_TESTCTRL_EXPLAIN_STMT 19 /* NOT USED */

6494 #define SQLITE_TESTCTRL_NEVER_CORRUPT 20

6495 #define SQLITE_TESTCTRL_VDBE_COVERAGE 21

6496 #define SQLITE_TESTCTRL_BYTEORDER 22

6497 #define SQLITE_TESTCTRL_ISINIT 23

6498 #define SQLITE_TESTCTRL_SORTER_MMAP 24

6499 #define SQLITE_TESTCTRL_IMPOSTER 25

6500 #define SQLITE_TESTCTRL_LAST 25

6501

6502 /*

6503 ** CAPI3REF: SQLite Runtime Status

6504 **

6505 ** ^These interfaces are used to retrieve runtime status information

6506 ** about the performance of SQLite, and optionally to reset various

6507 ** highwater marks. ^The first argument is an integer code for

6508 ** the specific parameter to measure. ^(Recognized integer codes

6509 ** are of the form [status parameters \| SQLITE_STATUS_...].)^

6510 ** ^The current value of the parameter is returned into *pCurrent.

6511 ** ^The highest recorded value is returned in *pHighwater. ^If the

6512 ** resetFlag is true, then the highest record value is reset after

6513 ** *pHighwater is written. ^(Some parameters do not record the highest

6514 ** value. For those parameters

6515 ** nothing is written into *pHighwater and the resetFlag is ignored.)^

6516 ** ^(Other parameters record only the highwater mark and not the current

6517 ** value. For these latter parameters nothing is written into *pCurrent.)^

6518 **

6519 ** ^The sqlite3_status() and sqlite3_status64() routines return

6520 ** SQLITE_OK on success and a non-zero [error code] on failure.

6521 **

6522 ** If either the current value or the highwater mark is too large to

6523 ** be represented by a 32-bit integer, then the values returned by

6524 ** sqlite3_status() are undefined.

6525 **

6526 ** See also: [sqlite3_db_status()]

6527 */

6528 int sqlite3_status(int op, int pCurrent, int pHighwater, int resetFlag);

6529 int sqlite3_status64(

6530 int op,

6531 sqlite3_int64 *pCurrent,

6532 sqlite3_int64 *pHighwater,

6533 int resetFlag

6534 );

6535

6536

6537 /*

6538 ** CAPI3REF: Status Parameters

6539 ** KEYWORDS: {status parameters}

6540 **

6541 ** These integer constants designate various run-time status parameters

6542 ** that can be returned by [sqlite3_status()].

6543 **

6544 ** <dl>

6545 ** [[SQLITE_STATUS_MEMORY_USED]] ^(<dt>SQLITE_STATUS_MEMORY_USED</dt>

6546 ** <dd>This parameter is the current amount of memory checked out

6547 ** using [sqlite3_malloc()], either directly or indirectly. The

6548 ** figure includes calls made to [sqlite3_malloc()] by the application

6549 ** and internal memory usage by the SQLite library. Scratch memory

6550 ** controlled by [SQLITE_CONFIG_SCRATCH] and auxiliary page-cache

6551 ** memory controlled by [SQLITE_CONFIG_PAGECACHE] is not included in

6552 ** this parameter. The amount returned is the sum of the allocation

6553 ** sizes as reported by the xSize method in [sqlite3_mem_methods].</dd>)^

6554 **

6555 ** [[SQLITE_STATUS_MALLOC_SIZE]] ^(<dt>SQLITE_STATUS_MALLOC_SIZE</dt>

6556 ** <dd>This parameter records the largest memory allocation request

6557 ** handed to [sqlite3_malloc()] or [sqlite3_realloc()] (or their

6558 ** internal equivalents). Only the value returned in the

6559 ** *pHighwater parameter to [sqlite3_status()] is of interest.

6560 ** The value written into the *pCurrent parameter is undefined.</dd>)^

6561 **

6562 ** [[SQLITE_STATUS_MALLOC_COUNT]] ^(<dt>SQLITE_STATUS_MALLOC_COUNT</dt>

6563 ** <dd>This parameter records the number of separate memory allocations

6564 ** currently checked out.</dd>)^

6565 **

6566 ** [[SQLITE_STATUS_PAGECACHE_USED]] ^(<dt>SQLITE_STATUS_PAGECACHE_USED</dt>

6567 ** <dd>This parameter returns the number of pages used out of the

6568 ** [pagecache memory allocator] that was configured using

6569 ** [SQLITE_CONFIG_PAGECACHE]. The

6570 ** value returned is in pages, not in bytes.</dd>)^

6571 **

6572 ** [[SQLITE_STATUS_PAGECACHE_OVERFLOW]]

6573 ** ^(<dt>SQLITE_STATUS_PAGECACHE_OVERFLOW</dt>

6574 ** <dd>This parameter returns the number of bytes of page cache

6575 ** allocation which could not be satisfied by the [SQLITE_CONFIG_PAGECACHE]

6576 ** buffer and where forced to overflow to [sqlite3_malloc()]. The

6577 ** returned value includes allocations that overflowed because they

6578 ** where too large (they were larger than the "sz" parameter to

6579 ** [SQLITE_CONFIG_PAGECACHE]) and allocations that overflowed because

6580 ** no space was left in the page cache.</dd>)^

6581 **

6582 ** [[SQLITE_STATUS_PAGECACHE_SIZE]] ^(<dt>SQLITE_STATUS_PAGECACHE_SIZE</dt>

6583 ** <dd>This parameter records the largest memory allocation request

6584 ** handed to [pagecache memory allocator]. Only the value returned in the

6585 ** *pHighwater parameter to [sqlite3_status()] is of interest.

6586 ** The value written into the *pCurrent parameter is undefined.</dd>)^

6587 **

6588 ** [[SQLITE_STATUS_SCRATCH_USED]] ^(<dt>SQLITE_STATUS_SCRATCH_USED</dt>

6589 ** <dd>This parameter returns the number of allocations used out of the

6590 ** [scratch memory allocator] configured using

6591 ** [SQLITE_CONFIG_SCRATCH]. The value returned is in allocations, not

6592 ** in bytes. Since a single thread may only have one scratch allocation

6593 ** outstanding at time, this parameter also reports the number of threads

6594 ** using scratch memory at the same time.</dd>)^

6595 **

6596 ** [[SQLITE_STATUS_SCRATCH_OVERFLOW]] ^(<dt>SQLITE_STATUS_SCRATCH_OVERFLOW</dt>

6597 ** <dd>This parameter returns the number of bytes of scratch memory

6598 ** allocation which could not be satisfied by the [SQLITE_CONFIG_SCRATCH]

6599 ** buffer and where forced to overflow to [sqlite3_malloc()]. The values

6600 ** returned include overflows because the requested allocation was too

6601 ** larger (that is, because the requested allocation was larger than the

6602 ** "sz" parameter to [SQLITE_CONFIG_SCRATCH]) and because no scratch buffer

6603 ** slots were available.

6604 ** </dd>)^

6605 **

6606 ** [[SQLITE_STATUS_SCRATCH_SIZE]] ^(<dt>SQLITE_STATUS_SCRATCH_SIZE</dt>

6607 ** <dd>This parameter records the largest memory allocation request

6608 ** handed to [scratch memory allocator]. Only the value returned in the

6609 ** *pHighwater parameter to [sqlite3_status()] is of interest.

6610 ** The value written into the *pCurrent parameter is undefined.</dd>)^

6611 **

6612 ** [[SQLITE_STATUS_PARSER_STACK]] ^(<dt>SQLITE_STATUS_PARSER_STACK</dt>

6613 ** <dd>The *pHighwater parameter records the deepest parser stack.

6614 ** The pCurrent value is undefined. The pHighwater value is only

6615 ** meaningful if SQLite is compiled with [YYTRACKMAXSTACKDEPTH].</dd>)^

6616 ** </dl>

6617 **

6618 ** New status parameters may be added from time to time.

6619 */

6620 #define SQLITE_STATUS_MEMORY_USED 0

6621 #define SQLITE_STATUS_PAGECACHE_USED 1

6622 #define SQLITE_STATUS_PAGECACHE_OVERFLOW 2

6623 #define SQLITE_STATUS_SCRATCH_USED 3

6624 #define SQLITE_STATUS_SCRATCH_OVERFLOW 4

6625 #define SQLITE_STATUS_MALLOC_SIZE 5

6626 #define SQLITE_STATUS_PARSER_STACK 6

6627 #define SQLITE_STATUS_PAGECACHE_SIZE 7

6628 #define SQLITE_STATUS_SCRATCH_SIZE 8

6629 #define SQLITE_STATUS_MALLOC_COUNT 9

6630

6631 /*

6632 ** CAPI3REF: Database Connection Status

6633 ** METHOD: sqlite3

6634 **

6635 ** ^This interface is used to retrieve runtime status information

6636 ** about a single [database connection]. ^The first argument is the

6637 ** database connection object to be interrogated. ^The second argument

6638 ** is an integer constant, taken from the set of

6639 ** [SQLITE_DBSTATUS options], that

6640 ** determines the parameter to interrogate. The set of

6641 ** [SQLITE_DBSTATUS options] is likely

6642 ** to grow in future releases of SQLite.

6643 **

6644 ** ^The current value of the requested parameter is written into *pCur

6645 ** and the highest instantaneous value is written into *pHiwtr. ^If

6646 ** the resetFlg is true, then the highest instantaneous value is

6647 ** reset back down to the current value.

6648 **

6649 ** ^The sqlite3_db_status() routine returns SQLITE_OK on success and a

6650 ** non-zero [error code] on failure.

6651 **

6652 ** See also: [sqlite3_status()] and [sqlite3_stmt_status()].

6653 */

6654 int sqlite3_db_status(sqlite3, int op, int pCur, int *pHiwtr, int resetFlg);

6655

6656 /*

6657 ** CAPI3REF: Status Parameters for database connections

6658 ** KEYWORDS: {SQLITE_DBSTATUS options}

6659 **

6660 ** These constants are the available integer "verbs" that can be passed as

6661 ** the second argument to the [sqlite3_db_status()] interface.

6662 **

6663 ** New verbs may be added in future releases of SQLite. Existing verbs

6664 ** might be discontinued. Applications should check the return code from

6665 ** [sqlite3_db_status()] to make sure that the call worked.

6666 ** The [sqlite3_db_status()] interface will return a non-zero error code

6667 ** if a discontinued or unsupported verb is invoked.

6668 **

6669 ** <dl>

6670 ** [[SQLITE_DBSTATUS_LOOKASIDE_USED]] ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_USED</dt>

6671 ** <dd>This parameter returns the number of lookaside memory slots currently

6672 ** checked out.</dd>)^

6673 **

6674 ** [[SQLITE_DBSTATUS_LOOKASIDE_HIT]] ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_HIT</dt>

6675 ** <dd>This parameter returns the number malloc attempts that were

6676 ** satisfied using lookaside memory. Only the high-water value is meaningful;

6677 ** the current value is always zero.)^

6678 **

6679 ** [[SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE]]

6680 ** ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE</dt>

6681 ** <dd>This parameter returns the number malloc attempts that might have

6682 ** been satisfied using lookaside memory but failed due to the amount of

6683 ** memory requested being larger than the lookaside slot size.

6684 ** Only the high-water value is meaningful;

6685 ** the current value is always zero.)^

6686 **

6687 ** [[SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL]]

6688 ** ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL</dt>

6689 ** <dd>This parameter returns the number malloc attempts that might have

6690 ** been satisfied using lookaside memory but failed due to all lookaside

6691 ** memory already being in use.

6692 ** Only the high-water value is meaningful;

6693 ** the current value is always zero.)^

6694 **

6695 ** [[SQLITE_DBSTATUS_CACHE_USED]] ^(<dt>SQLITE_DBSTATUS_CACHE_USED</dt>

6696 ** <dd>This parameter returns the approximate number of bytes of heap

6697 ** memory used by all pager caches associated with the database connection.)^

6698 ** ^The highwater mark associated with SQLITE_DBSTATUS_CACHE_USED is always 0.

6699 **

6700 ** [[SQLITE_DBSTATUS_SCHEMA_USED]] ^(<dt>SQLITE_DBSTATUS_SCHEMA_USED</dt>

6701 ** <dd>This parameter returns the approximate number of bytes of heap

6702 ** memory used to store the schema for all databases associated

6703 ** with the connection - main, temp, and any [ATTACH]-ed databases.)^

6704 ** ^The full amount of memory used by the schemas is reported, even if the

6705 ** schema memory is shared with other database connections due to

6706 ** [shared cache mode] being enabled.

6707 ** ^The highwater mark associated with SQLITE_DBSTATUS_SCHEMA_USED is always 0.

6708 **

6709 ** [[SQLITE_DBSTATUS_STMT_USED]] ^(<dt>SQLITE_DBSTATUS_STMT_USED</dt>

6710 ** <dd>This parameter returns the approximate number of bytes of heap

6711 ** and lookaside memory used by all prepared statements associated with

6712 ** the database connection.)^

6713 ** ^The highwater mark associated with SQLITE_DBSTATUS_STMT_USED is always 0.

6714 ** </dd>

6715 **

6716 ** [[SQLITE_DBSTATUS_CACHE_HIT]] ^(<dt>SQLITE_DBSTATUS_CACHE_HIT</dt>

6717 ** <dd>This parameter returns the number of pager cache hits that have

6718 ** occurred.)^ ^The highwater mark associated with SQLITE_DBSTATUS_CACHE_HIT

6719 ** is always 0.

6720 ** </dd>

6721 **

6722 ** [[SQLITE_DBSTATUS_CACHE_MISS]] ^(<dt>SQLITE_DBSTATUS_CACHE_MISS</dt>

6723 ** <dd>This parameter returns the number of pager cache misses that have

6724 ** occurred.)^ ^The highwater mark associated with SQLITE_DBSTATUS_CACHE_MISS

6725 ** is always 0.

6726 ** </dd>

6727 **

6728 ** [[SQLITE_DBSTATUS_CACHE_WRITE]] ^(<dt>SQLITE_DBSTATUS_CACHE_WRITE</dt>

6729 ** <dd>This parameter returns the number of dirty cache entries that have

6730 ** been written to disk. Specifically, the number of pages written to the

6731 ** wal file in wal mode databases, or the number of pages written to the

6732 ** database file in rollback mode databases. Any pages written as part of

6733 ** transaction rollback or database recovery operations are not included.

6734 ** If an IO or other error occurs while writing a page to disk, the effect

6735 ** on subsequent SQLITE_DBSTATUS_CACHE_WRITE requests is undefined.)^ ^The

6736 ** highwater mark associated with SQLITE_DBSTATUS_CACHE_WRITE is always 0.

6737 ** </dd>

6738 **

6739 ** [[SQLITE_DBSTATUS_DEFERRED_FKS]] ^(<dt>SQLITE_DBSTATUS_DEFERRED_FKS</dt>

6740 ** <dd>This parameter returns zero for the current value if and only if

6741 ** all foreign key constraints (deferred or immediate) have been

6742 ** resolved.)^ ^The highwater mark is always 0.

6743 ** </dd>

6744 ** </dl>

6745 */

6746 #define SQLITE_DBSTATUS_LOOKASIDE_USED 0

6747 #define SQLITE_DBSTATUS_CACHE_USED 1

6748 #define SQLITE_DBSTATUS_SCHEMA_USED 2

6749 #define SQLITE_DBSTATUS_STMT_USED 3

6750 #define SQLITE_DBSTATUS_LOOKASIDE_HIT 4

6751 #define SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE 5

6752 #define SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL 6

6753 #define SQLITE_DBSTATUS_CACHE_HIT 7

6754 #define SQLITE_DBSTATUS_CACHE_MISS 8

6755 #define SQLITE_DBSTATUS_CACHE_WRITE 9

6756 #define SQLITE_DBSTATUS_DEFERRED_FKS 10

6757 #define SQLITE_DBSTATUS_MAX 10 /* Largest defined DBSTATUS */

6758

6759

6760 /*

6761 ** CAPI3REF: Prepared Statement Status

6762 ** METHOD: sqlite3_stmt

6763 **

6764 ** ^(Each prepared statement maintains various

6765 ** [SQLITE_STMTSTATUS counters] that measure the number

6766 ** of times it has performed specific operations.)^ These counters can

6767 ** be used to monitor the performance characteristics of the prepared

6768 ** statements. For example, if the number of table steps greatly exceeds

6769 ** the number of table searches or result rows, that would tend to indicate

6770 ** that the prepared statement is using a full table scan rather than

6771 ** an index.

6772 **

6773 ** ^(This interface is used to retrieve and reset counter values from

6774 ** a [prepared statement]. The first argument is the prepared statement

6775 ** object to be interrogated. The second argument

6776 ** is an integer code for a specific [SQLITE_STMTSTATUS counter]

6777 ** to be interrogated.)^

6778 ** ^The current value of the requested counter is returned.

6779 ** ^If the resetFlg is true, then the counter is reset to zero after this

6780 ** interface call returns.

6781 **

6782 ** See also: [sqlite3_status()] and [sqlite3_db_status()].

6783 */

6784 int sqlite3_stmt_status(sqlite3_stmt*, int op,int resetFlg);

6785

6786 /*

6787 ** CAPI3REF: Status Parameters for prepared statements

6788 ** KEYWORDS: {SQLITE_STMTSTATUS counter} {SQLITE_STMTSTATUS counters}

6789 **

6790 ** These preprocessor macros define integer codes that name counter

6791 ** values associated with the [sqlite3_stmt_status()] interface.

6792 ** The meanings of the various counters are as follows:

6793 **

6794 ** <dl>

6795 ** [[SQLITE_STMTSTATUS_FULLSCAN_STEP]] <dt>SQLITE_STMTSTATUS_FULLSCAN_STEP</dt>

6796 ** <dd>^This is the number of times that SQLite has stepped forward in

6797 ** a table as part of a full table scan. Large numbers for this counter

6798 ** may indicate opportunities for performance improvement through

6799 ** careful use of indices.</dd>

6800 **

6801 ** [[SQLITE_STMTSTATUS_SORT]] <dt>SQLITE_STMTSTATUS_SORT</dt>

6802 ** <dd>^This is the number of sort operations that have occurred.

6803 ** A non-zero value in this counter may indicate an opportunity to

6804 ** improvement performance through careful use of indices.</dd>

6805 **

6806 ** [[SQLITE_STMTSTATUS_AUTOINDEX]] <dt>SQLITE_STMTSTATUS_AUTOINDEX</dt>

6807 ** <dd>^This is the number of rows inserted into transient indices that

6808 ** were created automatically in order to help joins run faster.

6809 ** A non-zero value in this counter may indicate an opportunity to

6810 ** improvement performance by adding permanent indices that do not

6811 ** need to be reinitialized each time the statement is run.</dd>

6812 **

6813 ** [[SQLITE_STMTSTATUS_VM_STEP]] <dt>SQLITE_STMTSTATUS_VM_STEP</dt>

6814 ** <dd>^This is the number of virtual machine operations executed

6815 ** by the prepared statement if that number is less than or equal

6816 ** to 2147483647. The number of virtual machine operations can be

6817 ** used as a proxy for the total work done by the prepared statement.

6818 ** If the number of virtual machine operations exceeds 2147483647

6819 ** then the value returned by this statement status code is undefined.

6820 ** </dd>

6821 ** </dl>

6822 */

6823 #define SQLITE_STMTSTATUS_FULLSCAN_STEP 1

6824 #define SQLITE_STMTSTATUS_SORT 2

6825 #define SQLITE_STMTSTATUS_AUTOINDEX 3

6826 #define SQLITE_STMTSTATUS_VM_STEP 4

6827

6828 /*

6829 ** CAPI3REF: Custom Page Cache Object

6830 **

6831 ** The sqlite3_pcache type is opaque. It is implemented by

6832 ** the pluggable module. The SQLite core has no knowledge of

6833 ** its size or internal structure and never deals with the

6834 ** sqlite3_pcache object except by holding and passing pointers

6835 ** to the object.

6836 **

6837 ** See [sqlite3_pcache_methods2] for additional information.

6838 */

6839 typedef struct sqlite3_pcache sqlite3_pcache;

6840

6841 /*

6842 ** CAPI3REF: Custom Page Cache Object

6843 **

6844 ** The sqlite3_pcache_page object represents a single page in the

6845 ** page cache. The page cache will allocate instances of this

6846 ** object. Various methods of the page cache use pointers to instances

6847 ** of this object as parameters or as their return value.

6848 **

6849 ** See [sqlite3_pcache_methods2] for additional information.

6850 */

6851 typedef struct sqlite3_pcache_page sqlite3_pcache_page;

6852 struct sqlite3_pcache_page {

6853 void pBuf; / The content of the page */

6854 void pExtra; / Extra information associated with the page */

6855 };

6856

6857 /*

6858 ** CAPI3REF: Application Defined Page Cache.

6859 ** KEYWORDS: {page cache}

6860 **

6861 ** ^(The [sqlite3_config]([SQLITE_CONFIG_PCACHE2], ...) interface can

6862 ** register an alternative page cache implementation by passing in an

6863 ** instance of the sqlite3_pcache_methods2 structure.)^

6864 ** In many applications, most of the heap memory allocated by

6865 ** SQLite is used for the page cache.

6866 ** By implementing a

6867 ** custom page cache using this API, an application can better control

6868 ** the amount of memory consumed by SQLite, the way in which

6869 ** that memory is allocated and released, and the policies used to

6870 ** determine exactly which parts of a database file are cached and for

6871 ** how long.

6872 **

6873 ** The alternative page cache mechanism is an

6874 ** extreme measure that is only needed by the most demanding applications.

6875 ** The built-in page cache is recommended for most uses.

6876 **

6877 ** ^(The contents of the sqlite3_pcache_methods2 structure are copied to an

6878 ** internal buffer by SQLite within the call to [sqlite3_config]. Hence

6879 ** the application may discard the parameter after the call to

6880 ** [sqlite3_config()] returns.)^

6881 **

6882 ** [[the xInit() page cache method]]

6883 ** ^(The xInit() method is called once for each effective

6884 ** call to [sqlite3_initialize()])^

6885 ** (usually only once during the lifetime of the process). ^(The xInit()

6886 ** method is passed a copy of the sqlite3_pcache_methods2.pArg value.)^

6887 ** The intent of the xInit() method is to set up global data structures

6888 ** required by the custom page cache implementation.

6889 ** ^(If the xInit() method is NULL, then the

6890 ** built-in default page cache is used instead of the application defined

6891 ** page cache.)^

6892 **

6893 ** [[the xShutdown() page cache method]]

6894 ** ^The xShutdown() method is called by [sqlite3_shutdown()].

6895 ** It can be used to clean up

6896 ** any outstanding resources before process shutdown, if required.

6897 ** ^The xShutdown() method may be NULL.

6898 **

6899 ** ^SQLite automatically serializes calls to the xInit method,

6900 ** so the xInit method need not be threadsafe. ^The

6901 ** xShutdown method is only called from [sqlite3_shutdown()] so it does

6902 ** not need to be threadsafe either. All other methods must be threadsafe

6903 ** in multithreaded applications.

6904 **

6905 ** ^SQLite will never invoke xInit() more than once without an intervening

6906 ** call to xShutdown().

6907 **

6908 ** [[the xCreate() page cache methods]]

6909 ** ^SQLite invokes the xCreate() method to construct a new cache instance.

6910 ** SQLite will typically create one cache instance for each open database file,

6911 ** though this is not guaranteed. ^The

6912 ** first parameter, szPage, is the size in bytes of the pages that must

6913 ** be allocated by the cache. ^szPage will always a power of two. ^The

6914 ** second parameter szExtra is a number of bytes of extra storage

6915 ** associated with each page cache entry. ^The szExtra parameter will

6916 ** a number less than 250. SQLite will use the

6917 ** extra szExtra bytes on each page to store metadata about the underlying

6918 ** database page on disk. The value passed into szExtra depends

6919 ** on the SQLite version, the target platform, and how SQLite was compiled.

6920 ** ^The third argument to xCreate(), bPurgeable, is true if the cache being

6921 ** created will be used to cache database pages of a file stored on disk, or

6922 ** false if it is used for an in-memory database. The cache implementation

6923 ** does not have to do anything special based with the value of bPurgeable;

6924 ** it is purely advisory. ^On a cache where bPurgeable is false, SQLite will

6925 ** never invoke xUnpin() except to deliberately delete a page.

6926 ** ^In other words, calls to xUnpin() on a cache with bPurgeable set to

6927 ** false will always have the "discard" flag set to true.

6928 ** ^Hence, a cache created with bPurgeable false will

6929 ** never contain any unpinned pages.

6930 **

6931 ** [[the xCachesize() page cache method]]

6932 ** ^(The xCachesize() method may be called at any time by SQLite to set the

6933 ** suggested maximum cache-size (number of pages stored by) the cache

6934 ** instance passed as the first argument. This is the value configured using

6935 ** the SQLite "[PRAGMA cache_size]" command.)^ As with the bPurgeable

6936 ** parameter, the implementation is not required to do anything with this

6937 ** value; it is advisory only.

6938 **

6939 ** [[the xPagecount() page cache methods]]

6940 ** The xPagecount() method must return the number of pages currently

6941 ** stored in the cache, both pinned and unpinned.

6942 **

6943 ** [[the xFetch() page cache methods]]

6944 ** The xFetch() method locates a page in the cache and returns a pointer to

6945 ** an sqlite3_pcache_page object associated with that page, or a NULL pointer.

6946 ** The pBuf element of the returned sqlite3_pcache_page object will be a

6947 ** pointer to a buffer of szPage bytes used to store the content of a

6948 ** single database page. The pExtra element of sqlite3_pcache_page will be

6949 ** a pointer to the szExtra bytes of extra storage that SQLite has requested

6950 ** for each entry in the page cache.

6951 **

6952 ** The page to be fetched is determined by the key. ^The minimum key value

6953 ** is 1. After it has been retrieved using xFetch, the page is considered

6954 ** to be "pinned".

6955 **

6956 ** If the requested page is already in the page cache, then the page cache

6957 ** implementation must return a pointer to the page buffer with its content

6958 ** intact. If the requested page is not already in the cache, then the

6959 ** cache implementation should use the value of the createFlag

6960 ** parameter to help it determined what action to take:

6961 **

6962 ** <table border=1 width=85% align=center>

6963 ** <tr><th> createFlag <th> Behavior when page is not already in cache

6964 ** <tr><td> 0 <td> Do not allocate a new page. Return NULL.

6965 ** <tr><td> 1 <td> Allocate a new page if it easy and convenient to do so.

6966 ** Otherwise return NULL.

6967 ** <tr><td> 2 <td> Make every effort to allocate a new page. Only return

6968 ** NULL if allocating a new page is effectively impossible.

6969 ** </table>

6970 **

6971 ** ^(SQLite will normally invoke xFetch() with a createFlag of 0 or 1. SQLite

6972 ** will only use a createFlag of 2 after a prior call with a createFlag of 1

6973 ** failed.)^ In between the to xFetch() calls, SQLite may

6974 ** attempt to unpin one or more cache pages by spilling the content of

6975 ** pinned pages to disk and synching the operating system disk cache.

6976 **

6977 ** [[the xUnpin() page cache method]]

6978 ** ^xUnpin() is called by SQLite with a pointer to a currently pinned page

6979 ** as its second argument. If the third parameter, discard, is non-zero,

6980 ** then the page must be evicted from the cache.

6981 ** ^If the discard parameter is

6982 ** zero, then the page may be discarded or retained at the discretion of

6983 ** page cache implementation. ^The page cache implementation

6984 ** may choose to evict unpinned pages at any time.

6985 **

6986 ** The cache must not perform any reference counting. A single

6987 ** call to xUnpin() unpins the page regardless of the number of prior calls

6988 ** to xFetch().

6989 **

6990 ** [[the xRekey() page cache methods]]

6991 ** The xRekey() method is used to change the key value associated with the

6992 ** page passed as the second argument. If the cache

6993 ** previously contains an entry associated with newKey, it must be

6994 ** discarded. ^Any prior cache entry associated with newKey is guaranteed not

6995 ** to be pinned.

6996 **

6997 ** When SQLite calls the xTruncate() method, the cache must discard all

6998 ** existing cache entries with page numbers (keys) greater than or equal

6999 ** to the value of the iLimit parameter passed to xTruncate(). If any

7000 ** of these pages are pinned, they are implicitly unpinned, meaning that

7001 ** they can be safely discarded.

7002 **

7003 ** [[the xDestroy() page cache method]]

7004 ** ^The xDestroy() method is used to delete a cache allocated by xCreate().

7005 ** All resources associated with the specified cache should be freed. ^After

7006 ** calling the xDestroy() method, SQLite considers the [sqlite3_pcache*]

7007 ** handle invalid, and will not use it with any other sqlite3_pcache_methods2

7008 ** functions.

7009 **

7010 ** [[the xShrink() page cache method]]

7011 ** ^SQLite invokes the xShrink() method when it wants the page cache to

7012 ** free up as much of heap memory as possible. The page cache implementation

7013 ** is not obligated to free any memory, but well-behaved implementations should

7014 ** do their best.

7015 */

7016 typedef struct sqlite3_pcache_methods2 sqlite3_pcache_methods2;

7017 struct sqlite3_pcache_methods2 {

7018 int iVersion;

7019 void *pArg;

7020 int (xInit)(void);

7021 void (xShutdown)(void);

7022 sqlite3_pcache (xCreate)(int szPage, int szExtra, int bPurgeable);

7023 void (xCachesize)(sqlite3_pcache, int nCachesize);

7024 int (xPagecount)(sqlite3_pcache);

7025 sqlite3_pcache_page (xFetch)(sqlite3_pcache*, unsigned key, int createFlag);

7026 void (xUnpin)(sqlite3_pcache, sqlite3_pcache_page*, int discard);

7027 void (xRekey)(sqlite3_pcache, sqlite3_pcache_page*,

7028 unsigned oldKey, unsigned newKey);

7029 void (xTruncate)(sqlite3_pcache, unsigned iLimit);

7030 void (xDestroy)(sqlite3_pcache);

7031 void (xShrink)(sqlite3_pcache);

7032 };

7033

7034 /*

7035 ** This is the obsolete pcache_methods object that has now been replaced

7036 ** by sqlite3_pcache_methods2. This object is not used by SQLite. It is

7037 ** retained in the header file for backwards compatibility only.

7038 */

7039 typedef struct sqlite3_pcache_methods sqlite3_pcache_methods;

7040 struct sqlite3_pcache_methods {

7041 void *pArg;

7042 int (xInit)(void);

7043 void (xShutdown)(void);

7044 sqlite3_pcache (xCreate)(int szPage, int bPurgeable);

7045 void (xCachesize)(sqlite3_pcache, int nCachesize);

7046 int (xPagecount)(sqlite3_pcache);

7047 void (xFetch)(sqlite3_pcache*, unsigned key, int createFlag);

7048 void (xUnpin)(sqlite3_pcache, void*, int discard);

7049 void (xRekey)(sqlite3_pcache, void*, unsigned oldKey, unsigned newKey);

7050 void (xTruncate)(sqlite3_pcache, unsigned iLimit);

7051 void (xDestroy)(sqlite3_pcache);

7052 };

7053

7054

7055 /*

7056 ** CAPI3REF: Online Backup Object

7057 **

7058 ** The sqlite3_backup object records state information about an ongoing

7059 ** online backup operation. ^The sqlite3_backup object is created by

7060 ** a call to [sqlite3_backup_init()] and is destroyed by a call to

7061 ** [sqlite3_backup_finish()].

7062 **

7063 ** See Also: [Using the SQLite Online Backup API]

7064 */

7065 typedef struct sqlite3_backup sqlite3_backup;

7066

7067 /*

7068 ** CAPI3REF: Online Backup API.

7069 **

7070 ** The backup API copies the content of one database into another.

7071 ** It is useful either for creating backups of databases or

7072 ** for copying in-memory databases to or from persistent files.

7073 **

7074 ** See Also: [Using the SQLite Online Backup API]

7075 **

7076 ** ^SQLite holds a write transaction open on the destination database file

7077 ** for the duration of the backup operation.

7078 ** ^The source database is read-locked only while it is being read;

7079 ** it is not locked continuously for the entire backup operation.

7080 ** ^Thus, the backup may be performed on a live source database without

7081 ** preventing other database connections from

7082 ** reading or writing to the source database while the backup is underway.

7083 **

7084 ** ^(To perform a backup operation:

7085 ** <ol>

7086 ** <li><b>sqlite3_backup_init()</b> is called once to initialize the

7087 ** backup,

7088 ** <li><b>sqlite3_backup_step()</b> is called one or more times to transfer

7089 ** the data between the two databases, and finally

7090 ** <li><b>sqlite3_backup_finish()</b> is called to release all resources

7091 ** associated with the backup operation.

7092 ** </ol>)^

7093 ** There should be exactly one call to sqlite3_backup_finish() for each

7094 ** successful call to sqlite3_backup_init().

7095 **

7096 ** [[sqlite3_backup_init()]] <b>sqlite3_backup_init()</b>

7097 **

7098 ** ^The D and N arguments to sqlite3_backup_init(D,N,S,M) are the

7099 ** [database connection] associated with the destination database

7100 ** and the database name, respectively.

7101 ** ^The database name is "main" for the main database, "temp" for the

7102 ** temporary database, or the name specified after the AS keyword in

7103 ** an [ATTACH] statement for an attached database.

7104 ** ^The S and M arguments passed to

7105 ** sqlite3_backup_init(D,N,S,M) identify the [database connection]

7106 ** and database name of the source database, respectively.

7107 ** ^The source and destination [database connections] (parameters S and D)

7108 ** must be different or else sqlite3_backup_init(D,N,S,M) will fail with

7109 ** an error.

7110 **

7111 ** ^A call to sqlite3_backup_init() will fail, returning SQLITE_ERROR, if

7112 ** there is already a read or read-write transaction open on the

7113 ** destination database.

7114 **

7115 ** ^If an error occurs within sqlite3_backup_init(D,N,S,M), then NULL is

7116 ** returned and an error code and error message are stored in the

7117 ** destination [database connection] D.

7118 ** ^The error code and message for the failed call to sqlite3_backup_init()

7119 ** can be retrieved using the [sqlite3_errcode()], [sqlite3_errmsg()], and/or

7120 ** [sqlite3_errmsg16()] functions.

7121 ** ^A successful call to sqlite3_backup_init() returns a pointer to an

7122 ** [sqlite3_backup] object.

7123 ** ^The [sqlite3_backup] object may be used with the sqlite3_backup_step() and

7124 ** sqlite3_backup_finish() functions to perform the specified backup

7125 ** operation.

7126 **

7127 ** [[sqlite3_backup_step()]] <b>sqlite3_backup_step()</b>

7128 **

7129 ** ^Function sqlite3_backup_step(B,N) will copy up to N pages between

7130 ** the source and destination databases specified by [sqlite3_backup] object B.

7131 ** ^If N is negative, all remaining source pages are copied.

7132 ** ^If sqlite3_backup_step(B,N) successfully copies N pages and there

7133 ** are still more pages to be copied, then the function returns [SQLITE_OK].

7134 ** ^If sqlite3_backup_step(B,N) successfully finishes copying all pages

7135 ** from source to destination, then it returns [SQLITE_DONE].

7136 ** ^If an error occurs while running sqlite3_backup_step(B,N),

7137 ** then an [error code] is returned. ^As well as [SQLITE_OK] and

7138 ** [SQLITE_DONE], a call to sqlite3_backup_step() may return [SQLITE_READONLY],

7139 ** [SQLITE_NOMEM], [SQLITE_BUSY], [SQLITE_LOCKED], or an

7140 ** [SQLITE_IOERR_ACCESS \| SQLITE_IOERR_XXX] extended error code.

7141 **

7142 ** ^(The sqlite3_backup_step() might return [SQLITE_READONLY] if

7143 ** <ol>

7144 ** <li> the destination database was opened read-only, or

7145 ** <li> the destination database is using write-ahead-log journaling

7146 ** and the destination and source page sizes differ, or

7147 ** <li> the destination database is an in-memory database and the

7148 ** destination and source page sizes differ.

7149 ** </ol>)^

7150 **

7151 ** ^If sqlite3_backup_step() cannot obtain a required file-system lock, then

7152 ** the [sqlite3_busy_handler \| busy-handler function]

7153 ** is invoked (if one is specified). ^If the

7154 ** busy-handler returns non-zero before the lock is available, then

7155 ** [SQLITE_BUSY] is returned to the caller. ^In this case the call to

7156 ** sqlite3_backup_step() can be retried later. ^If the source

7157 ** [database connection]

7158 ** is being used to write to the source database when sqlite3_backup_step()

7159 ** is called, then [SQLITE_LOCKED] is returned immediately. ^Again, in this

7160 ** case the call to sqlite3_backup_step() can be retried later on. ^(If

7161 ** [SQLITE_IOERR_ACCESS \| SQLITE_IOERR_XXX], [SQLITE_NOMEM], or

7162 ** [SQLITE_READONLY] is returned, then

7163 ** there is no point in retrying the call to sqlite3_backup_step(). These

7164 ** errors are considered fatal.)^ The application must accept

7165 ** that the backup operation has failed and pass the backup operation handle

7166 ** to the sqlite3_backup_finish() to release associated resources.

7167 **

7168 ** ^The first call to sqlite3_backup_step() obtains an exclusive lock

7169 ** on the destination file. ^The exclusive lock is not released until either

7170 ** sqlite3_backup_finish() is called or the backup operation is complete

7171 ** and sqlite3_backup_step() returns [SQLITE_DONE]. ^Every call to

7172 ** sqlite3_backup_step() obtains a [shared lock] on the source database that

7173 ** lasts for the duration of the sqlite3_backup_step() call.

7174 ** ^Because the source database is not locked between calls to

7175 ** sqlite3_backup_step(), the source database may be modified mid-way

7176 ** through the backup process. ^If the source database is modified by an

7177 ** external process or via a database connection other than the one being

7178 ** used by the backup operation, then the backup will be automatically

7179 ** restarted by the next call to sqlite3_backup_step(). ^If the source

7180 ** database is modified by the using the same database connection as is used

7181 ** by the backup operation, then the backup database is automatically

7182 ** updated at the same time.

7183 **

7184 ** [[sqlite3_backup_finish()]] <b>sqlite3_backup_finish()</b>

7185 **

7186 ** When sqlite3_backup_step() has returned [SQLITE_DONE], or when the

7187 ** application wishes to abandon the backup operation, the application

7188 ** should destroy the [sqlite3_backup] by passing it to sqlite3_backup_finish().

7189 ** ^The sqlite3_backup_finish() interfaces releases all

7190 ** resources associated with the [sqlite3_backup] object.

7191 ** ^If sqlite3_backup_step() has not yet returned [SQLITE_DONE], then any

7192 ** active write-transaction on the destination database is rolled back.

7193 ** The [sqlite3_backup] object is invalid

7194 ** and may not be used following a call to sqlite3_backup_finish().

7195 **

7196 ** ^The value returned by sqlite3_backup_finish is [SQLITE_OK] if no

7197 ** sqlite3_backup_step() errors occurred, regardless or whether or not

7198 ** sqlite3_backup_step() completed.

7199 ** ^If an out-of-memory condition or IO error occurred during any prior

7200 ** sqlite3_backup_step() call on the same [sqlite3_backup] object, then

7201 ** sqlite3_backup_finish() returns the corresponding [error code].

7202 **

7203 ** ^A return of [SQLITE_BUSY] or [SQLITE_LOCKED] from sqlite3_backup_step()

7204 ** is not a permanent error and does not affect the return value of

7205 ** sqlite3_backup_finish().

7206 **

7207 ** [[sqlite3_backup_remaining()]] [[sqlite3_backup_pagecount()]]

7208 ** <b>sqlite3_backup_remaining() and sqlite3_backup_pagecount()</b>

7209 **

7210 ** ^The sqlite3_backup_remaining() routine returns the number of pages still

7211 ** to be backed up at the conclusion of the most recent sqlite3_backup_step().

7212 ** ^The sqlite3_backup_pagecount() routine returns the total number of pages

7213 ** in the source database at the conclusion of the most recent

7214 ** sqlite3_backup_step().

7215 ** ^(The values returned by these functions are only updated by

7216 ** sqlite3_backup_step(). If the source database is modified in a way that

7217 ** changes the size of the source database or the number of pages remaining,

7218 ** those changes are not reflected in the output of sqlite3_backup_pagecount()

7219 ** and sqlite3_backup_remaining() until after the next

7220 ** sqlite3_backup_step().)^

7221 **

7222 ** <b>Concurrent Usage of Database Handles</b>

7223 **

7224 ** ^The source [database connection] may be used by the application for other

7225 ** purposes while a backup operation is underway or being initialized.

7226 ** ^If SQLite is compiled and configured to support threadsafe database

7227 ** connections, then the source database connection may be used concurrently

7228 ** from within other threads.

7229 **

7230 ** However, the application must guarantee that the destination

7231 ** [database connection] is not passed to any other API (by any thread) after

7232 ** sqlite3_backup_init() is called and before the corresponding call to

7233 ** sqlite3_backup_finish(). SQLite does not currently check to see

7234 ** if the application incorrectly accesses the destination [database connection]

7235 ** and so no error code is reported, but the operations may malfunction

7236 ** nevertheless. Use of the destination database connection while a

7237 ** backup is in progress might also also cause a mutex deadlock.

7238 **

7239 ** If running in [shared cache mode], the application must

7240 ** guarantee that the shared cache used by the destination database

7241 ** is not accessed while the backup is running. In practice this means

7242 ** that the application must guarantee that the disk file being

7243 ** backed up to is not accessed by any connection within the process,

7244 ** not just the specific connection that was passed to sqlite3_backup_init().

7245 **

7246 ** The [sqlite3_backup] object itself is partially threadsafe. Multiple

7247 ** threads may safely make multiple concurrent calls to sqlite3_backup_step().

7248 ** However, the sqlite3_backup_remaining() and sqlite3_backup_pagecount()

7249 ** APIs are not strictly speaking threadsafe. If they are invoked at the

7250 ** same time as another thread is invoking sqlite3_backup_step() it is

7251 ** possible that they return invalid values.

7252 */

7253 sqlite3_backup *sqlite3_backup_init(

7254 sqlite3 pDest, / Destination database handle */

7255 const char zDestName, / Destination database name */

7256 sqlite3 pSource, / Source database handle */

7257 const char zSourceName / Source database name */

7258 );

7259 int sqlite3_backup_step(sqlite3_backup *p, int nPage);

7260 int sqlite3_backup_finish(sqlite3_backup *p);

7261 int sqlite3_backup_remaining(sqlite3_backup *p);

7262 int sqlite3_backup_pagecount(sqlite3_backup *p);

7263

7264 /*

7265 ** CAPI3REF: Unlock Notification

7266 ** METHOD: sqlite3

7267 **

7268 ** ^When running in shared-cache mode, a database operation may fail with

7269 ** an [SQLITE_LOCKED] error if the required locks on the shared-cache or

7270 ** individual tables within the shared-cache cannot be obtained. See

7271 ** [SQLite Shared-Cache Mode] for a description of shared-cache locking.

7272 ** ^This API may be used to register a callback that SQLite will invoke

7273 ** when the connection currently holding the required lock relinquishes it.

7274 ** ^This API is only available if the library was compiled with the

7275 ** [SQLITE_ENABLE_UNLOCK_NOTIFY] C-preprocessor symbol defined.

7276 **

7277 ** See Also: [Using the SQLite Unlock Notification Feature].

7278 **

7279 ** ^Shared-cache locks are released when a database connection concludes

7280 ** its current transaction, either by committing it or rolling it back.

7281 **

7282 ** ^When a connection (known as the blocked connection) fails to obtain a

7283 ** shared-cache lock and SQLITE_LOCKED is returned to the caller, the

7284 ** identity of the database connection (the blocking connection) that

7285 ** has locked the required resource is stored internally. ^After an

7286 ** application receives an SQLITE_LOCKED error, it may call the

7287 ** sqlite3_unlock_notify() method with the blocked connection handle as

7288 ** the first argument to register for a callback that will be invoked

7289 ** when the blocking connections current transaction is concluded. ^The

7290 ** callback is invoked from within the [sqlite3_step] or [sqlite3_close]

7291 ** call that concludes the blocking connections transaction.

7292 **

7293 ** ^(If sqlite3_unlock_notify() is called in a multi-threaded application,

7294 ** there is a chance that the blocking connection will have already

7295 ** concluded its transaction by the time sqlite3_unlock_notify() is invoked.

7296 ** If this happens, then the specified callback is invoked immediately,

7297 ** from within the call to sqlite3_unlock_notify().)^

7298 **

7299 ** ^If the blocked connection is attempting to obtain a write-lock on a

7300 ** shared-cache table, and more than one other connection currently holds

7301 ** a read-lock on the same table, then SQLite arbitrarily selects one of

7302 ** the other connections to use as the blocking connection.

7303 **

7304 ** ^(There may be at most one unlock-notify callback registered by a

7305 ** blocked connection. If sqlite3_unlock_notify() is called when the

7306 ** blocked connection already has a registered unlock-notify callback,

7307 ** then the new callback replaces the old.)^ ^If sqlite3_unlock_notify() is

7308 ** called with a NULL pointer as its second argument, then any existing

7309 ** unlock-notify callback is canceled. ^The blocked connections

7310 ** unlock-notify callback may also be canceled by closing the blocked

7311 ** connection using [sqlite3_close()].

7312 **

7313 ** The unlock-notify callback is not reentrant. If an application invokes

7314 ** any sqlite3_xxx API functions from within an unlock-notify callback, a

7315 ** crash or deadlock may be the result.

7316 **

7317 ** ^Unless deadlock is detected (see below), sqlite3_unlock_notify() always

7318 ** returns SQLITE_OK.

7319 **

7320 ** <b>Callback Invocation Details</b>

7321 **

7322 ** When an unlock-notify callback is registered, the application provides a

7323 ** single void* pointer that is passed to the callback when it is invoked.

7324 ** However, the signature of the callback function allows SQLite to pass

7325 ** it an array of void* context pointers. The first argument passed to

7326 ** an unlock-notify callback is a pointer to an array of void* pointers,

7327 ** and the second is the number of entries in the array.

7328 **

7329 ** When a blocking connections transaction is concluded, there may be

7330 ** more than one blocked connection that has registered for an unlock-notify

7331 ** callback. ^If two or more such blocked connections have specified the

7332 ** same callback function, then instead of invoking the callback function

7333 ** multiple times, it is invoked once with the set of void* context pointers

7334 ** specified by the blocked connections bundled together into an array.

7335 ** This gives the application an opportunity to prioritize any actions

7336 ** related to the set of unblocked database connections.

7337 **

7338 ** <b>Deadlock Detection</b>

7339 **

7340 ** Assuming that after registering for an unlock-notify callback a

7341 ** database waits for the callback to be issued before taking any further

7342 ** action (a reasonable assumption), then using this API may cause the

7343 ** application to deadlock. For example, if connection X is waiting for

7344 ** connection Y's transaction to be concluded, and similarly connection

7345 ** Y is waiting on connection X's transaction, then neither connection

7346 ** will proceed and the system may remain deadlocked indefinitely.

7347 **

7348 ** To avoid this scenario, the sqlite3_unlock_notify() performs deadlock

7349 ** detection. ^If a given call to sqlite3_unlock_notify() would put the

7350 ** system in a deadlocked state, then SQLITE_LOCKED is returned and no

7351 ** unlock-notify callback is registered. The system is said to be in

7352 ** a deadlocked state if connection A has registered for an unlock-notify

7353 ** callback on the conclusion of connection B's transaction, and connection

7354 ** B has itself registered for an unlock-notify callback when connection

7355 ** A's transaction is concluded. ^Indirect deadlock is also detected, so

7356 ** the system is also considered to be deadlocked if connection B has

7357 ** registered for an unlock-notify callback on the conclusion of connection

7358 ** C's transaction, where connection C is waiting on connection A. ^Any

7359 ** number of levels of indirection are allowed.

7360 **

7361 ** <b>The "DROP TABLE" Exception</b>

7362 **

7363 ** When a call to [sqlite3_step()] returns SQLITE_LOCKED, it is almost

7364 ** always appropriate to call sqlite3_unlock_notify(). There is however,

7365 ** one exception. When executing a "DROP TABLE" or "DROP INDEX" statement,

7366 ** SQLite checks if there are any currently executing SELECT statements

7367 ** that belong to the same connection. If there are, SQLITE_LOCKED is

7368 ** returned. In this case there is no "blocking connection", so invoking

7369 ** sqlite3_unlock_notify() results in the unlock-notify callback being

7370 ** invoked immediately. If the application then re-attempts the "DROP TABLE"

7371 ** or "DROP INDEX" query, an infinite loop might be the result.

7372 **

7373 ** One way around this problem is to check the extended error code returned

7374 ** by an sqlite3_step() call. ^(If there is a blocking connection, then the

7375 ** extended error code is set to SQLITE_LOCKED_SHAREDCACHE. Otherwise, in

7376 ** the special "DROP TABLE/INDEX" case, the extended error code is just

7377 ** SQLITE_LOCKED.)^

7378 */

7379 int sqlite3_unlock_notify(

7380 sqlite3 pBlocked, / Waiting connection */

7381 void (xNotify)(void apArg, int nArg), / Callback function to invoke */

7382 void pNotifyArg / Argument to pass to xNotify */

7383 );

7384

7385

7386 /*

7387 ** CAPI3REF: String Comparison

7388 **

7389 ** ^The [sqlite3_stricmp()] and [sqlite3_strnicmp()] APIs allow applications

7390 ** and extensions to compare the contents of two buffers containing UTF-8

7391 ** strings in a case-independent fashion, using the same definition of "case

7392 ** independence" that SQLite uses internally when comparing identifiers.

7393 */

7394 int sqlite3_stricmp(const char , const char );

7395 int sqlite3_strnicmp(const char , const char , int);

7396

7397 /*

7398 ** CAPI3REF: String Globbing

7399 *

7400 ** ^The [sqlite3_strglob(P,X)] interface returns zero if and only if

7401 ** string X matches the [GLOB] pattern P.

7402 ** ^The definition of [GLOB] pattern matching used in

7403 ** [sqlite3_strglob(P,X)] is the same as for the "X GLOB P" operator in the

7404 ** SQL dialect understood by SQLite. ^The [sqlite3_strglob(P,X)] function

7405 ** is case sensitive.

7406 **

7407 ** Note that this routine returns zero on a match and non-zero if the strings

7408 ** do not match, the same as [sqlite3_stricmp()] and [sqlite3_strnicmp()].

7409 **

7410 ** See also: [sqlite3_strlike()].

7411 */

7412 int sqlite3_strglob(const char zGlob, const char zStr);

7413

7414 /*

7415 ** CAPI3REF: String LIKE Matching

7416 *

7417 ** ^The [sqlite3_strlike(P,X,E)] interface returns zero if and only if

7418 ** string X matches the [LIKE] pattern P with escape character E.

7419 ** ^The definition of [LIKE] pattern matching used in

7420 ** [sqlite3_strlike(P,X,E)] is the same as for the "X LIKE P ESCAPE E"

7421 ** operator in the SQL dialect understood by SQLite. ^For "X LIKE P" without

7422 ** the ESCAPE clause, set the E parameter of [sqlite3_strlike(P,X,E)] to 0.

7423 ** ^As with the LIKE operator, the [sqlite3_strlike(P,X,E)] function is case

7424 ** insensitive - equivalent upper and lower case ASCII characters match

7425 ** one another.

7426 **

7427 ** ^The [sqlite3_strlike(P,X,E)] function matches Unicode characters, though

7428 ** only ASCII characters are case folded.

7429 **

7430 ** Note that this routine returns zero on a match and non-zero if the strings

7431 ** do not match, the same as [sqlite3_stricmp()] and [sqlite3_strnicmp()].

7432 **

7433 ** See also: [sqlite3_strglob()].

7434 */

7435 int sqlite3_strlike(const char zGlob, const char zStr, unsigned int cEsc);

7436

7437 /*

7438 ** CAPI3REF: Error Logging Interface

7439 **

7440 ** ^The [sqlite3_log()] interface writes a message into the [error log]

7441 ** established by the [SQLITE_CONFIG_LOG] option to [sqlite3_config()].

7442 ** ^If logging is enabled, the zFormat string and subsequent arguments are

7443 ** used with [sqlite3_snprintf()] to generate the final output string.

7444 **

7445 ** The sqlite3_log() interface is intended for use by extensions such as

7446 ** virtual tables, collating functions, and SQL functions. While there is

7447 ** nothing to prevent an application from calling sqlite3_log(), doing so

7448 ** is considered bad form.

7449 **

7450 ** The zFormat string must not be NULL.

7451 **

7452 ** To avoid deadlocks and other threading problems, the sqlite3_log() routine

7453 ** will not use dynamically allocated memory. The log message is stored in

7454 ** a fixed-length buffer on the stack. If the log message is longer than

7455 ** a few hundred characters, it will be truncated to the length of the

7456 ** buffer.

7457 */

7458 void sqlite3_log(int iErrCode, const char *zFormat, ...);

7459

7460 /*

7461 ** CAPI3REF: Write-Ahead Log Commit Hook

7462 ** METHOD: sqlite3

7463 **

7464 ** ^The [sqlite3_wal_hook()] function is used to register a callback that

7465 ** is invoked each time data is committed to a database in wal mode.

7466 **

7467 ** ^(The callback is invoked by SQLite after the commit has taken place and

7468 ** the associated write-lock on the database released)^, so the implementation

7469 ** may read, write or [checkpoint] the database as required.

7470 **

7471 ** ^The first parameter passed to the callback function when it is invoked

7472 ** is a copy of the third parameter passed to sqlite3_wal_hook() when

7473 ** registering the callback. ^The second is a copy of the database handle.

7474 ** ^The third parameter is the name of the database that was written to -

7475 ** either "main" or the name of an [ATTACH]-ed database. ^The fourth parameter

7476 ** is the number of pages currently in the write-ahead log file,

7477 ** including those that were just committed.

7478 **

7479 ** The callback function should normally return [SQLITE_OK]. ^If an error

7480 ** code is returned, that error will propagate back up through the

7481 ** SQLite code base to cause the statement that provoked the callback

7482 ** to report an error, though the commit will have still occurred. If the

7483 ** callback returns [SQLITE_ROW] or [SQLITE_DONE], or if it returns a value

7484 ** that does not correspond to any valid SQLite error code, the results

7485 ** are undefined.

7486 **

7487 ** A single database handle may have at most a single write-ahead log callback

7488 ** registered at one time. ^Calling [sqlite3_wal_hook()] replaces any

7489 ** previously registered write-ahead log callback. ^Note that the

7490 ** [sqlite3_wal_autocheckpoint()] interface and the

7491 ** [wal_autocheckpoint pragma] both invoke [sqlite3_wal_hook()] and will

7492 ** those overwrite any prior [sqlite3_wal_hook()] settings.

7493 */

7494 void *sqlite3_wal_hook(

7495 sqlite3*,

7496 int()(void ,sqlite3,const char,int),

7497 void*

7498 );

7499

7500 /*

7501 ** CAPI3REF: Configure an auto-checkpoint

7502 ** METHOD: sqlite3

7503 **

7504 ** ^The [sqlite3_wal_autocheckpoint(D,N)] is a wrapper around

7505 ** [sqlite3_wal_hook()] that causes any database on [database connection] D

7506 ** to automatically [checkpoint]

7507 ** after committing a transaction if there are N or

7508 ** more frames in the [write-ahead log] file. ^Passing zero or

7509 ** a negative value as the nFrame parameter disables automatic

7510 ** checkpoints entirely.

7511 **

7512 ** ^The callback registered by this function replaces any existing callback

7513 ** registered using [sqlite3_wal_hook()]. ^Likewise, registering a callback

7514 ** using [sqlite3_wal_hook()] disables the automatic checkpoint mechanism

7515 ** configured by this function.

7516 **

7517 ** ^The [wal_autocheckpoint pragma] can be used to invoke this interface

7518 ** from SQL.

7519 **

7520 ** ^Checkpoints initiated by this mechanism are

7521 ** [sqlite3_wal_checkpoint_v2\|PASSIVE].

7522 **

7523 ** ^Every new [database connection] defaults to having the auto-checkpoint

7524 ** enabled with a threshold of 1000 or [SQLITE_DEFAULT_WAL_AUTOCHECKPOINT]

7525 ** pages. The use of this interface

7526 ** is only necessary if the default setting is found to be suboptimal

7527 ** for a particular application.

7528 */

7529 int sqlite3_wal_autocheckpoint(sqlite3 *db, int N);

7530

7531 /*

7532 ** CAPI3REF: Checkpoint a database

7533 ** METHOD: sqlite3

7534 **

7535 ** ^(The sqlite3_wal_checkpoint(D,X) is equivalent to

7536 ** [sqlite3_wal_checkpoint_v2](D,X,[SQLITE_CHECKPOINT_PASSIVE],0,0).)^

7537 **

7538 ** In brief, sqlite3_wal_checkpoint(D,X) causes the content in the

7539 ** [write-ahead log] for database X on [database connection] D to be

7540 ** transferred into the database file and for the write-ahead log to

7541 ** be reset. See the [checkpointing] documentation for addition

7542 ** information.

7543 **

7544 ** This interface used to be the only way to cause a checkpoint to

7545 ** occur. But then the newer and more powerful [sqlite3_wal_checkpoint_v2()]

7546 ** interface was added. This interface is retained for backwards

7547 ** compatibility and as a convenience for applications that need to manually

7548 ** start a callback but which do not need the full power (and corresponding

7549 ** complication) of [sqlite3_wal_checkpoint_v2()].

7550 */

7551 int sqlite3_wal_checkpoint(sqlite3 db, const char zDb);

7552

7553 /*

7554 ** CAPI3REF: Checkpoint a database

7555 ** METHOD: sqlite3

7556 **

7557 ** ^(The sqlite3_wal_checkpoint_v2(D,X,M,L,C) interface runs a checkpoint

7558 ** operation on database X of [database connection] D in mode M. Status

7559 ** information is written back into integers pointed to by L and C.)^

7560 ** ^(The M parameter must be a valid [checkpoint mode]:)^

7561 **

7562 ** <dl>

7563 ** <dt>SQLITE_CHECKPOINT_PASSIVE<dd>

7564 ** ^Checkpoint as many frames as possible without waiting for any database

7565 ** readers or writers to finish, then sync the database file if all frames

7566 ** in the log were checkpointed. ^The [busy-handler callback]

7567 ** is never invoked in the SQLITE_CHECKPOINT_PASSIVE mode.

7568 ** ^On the other hand, passive mode might leave the checkpoint unfinished

7569 ** if there are concurrent readers or writers.

7570 **

7571 ** <dt>SQLITE_CHECKPOINT_FULL<dd>

7572 ** ^This mode blocks (it invokes the

7573 ** [sqlite3_busy_handler\|busy-handler callback]) until there is no

7574 ** database writer and all readers are reading from the most recent database

7575 ** snapshot. ^It then checkpoints all frames in the log file and syncs the

7576 ** database file. ^This mode blocks new database writers while it is pending,

7577 ** but new database readers are allowed to continue unimpeded.

7578 **

7579 ** <dt>SQLITE_CHECKPOINT_RESTART<dd>

7580 ** ^This mode works the same way as SQLITE_CHECKPOINT_FULL with the addition

7581 ** that after checkpointing the log file it blocks (calls the

7582 ** [busy-handler callback])

7583 ** until all readers are reading from the database file only. ^This ensures

7584 ** that the next writer will restart the log file from the beginning.

7585 ** ^Like SQLITE_CHECKPOINT_FULL, this mode blocks new

7586 ** database writer attempts while it is pending, but does not impede readers.

7587 **

7588 ** <dt>SQLITE_CHECKPOINT_TRUNCATE<dd>

7589 ** ^This mode works the same way as SQLITE_CHECKPOINT_RESTART with the

7590 ** addition that it also truncates the log file to zero bytes just prior

7591 ** to a successful return.

7592 ** </dl>

7593 **

7594 ** ^If pnLog is not NULL, then *pnLog is set to the total number of frames in

7595 ** the log file or to -1 if the checkpoint could not run because

7596 ** of an error or because the database is not in [WAL mode]. ^If pnCkpt is not

7597 ** NULL,then *pnCkpt is set to the total number of checkpointed frames in the

7598 ** log file (including any that were already checkpointed before the function

7599 ** was called) or to -1 if the checkpoint could not run due to an error or

7600 ** because the database is not in WAL mode. ^Note that upon successful

7601 ** completion of an SQLITE_CHECKPOINT_TRUNCATE, the log file will have been

7602 ** truncated to zero bytes and so both pnLog and pnCkpt will be set to zero.

7603 **

7604 ** ^All calls obtain an exclusive "checkpoint" lock on the database file. ^If

7605 ** any other process is running a checkpoint operation at the same time, the

7606 ** lock cannot be obtained and SQLITE_BUSY is returned. ^Even if there is a

7607 ** busy-handler configured, it will not be invoked in this case.

7608 **

7609 ** ^The SQLITE_CHECKPOINT_FULL, RESTART and TRUNCATE modes also obtain the

7610 ** exclusive "writer" lock on the database file. ^If the writer lock cannot be

7611 ** obtained immediately, and a busy-handler is configured, it is invoked and

7612 ** the writer lock retried until either the busy-handler returns 0 or the lock

7613 ** is successfully obtained. ^The busy-handler is also invoked while waiting for

7614 ** database readers as described above. ^If the busy-handler returns 0 before

7615 ** the writer lock is obtained or while waiting for database readers, the

7616 ** checkpoint operation proceeds from that point in the same way as

7617 ** SQLITE_CHECKPOINT_PASSIVE - checkpointing as many frames as possible

7618 ** without blocking any further. ^SQLITE_BUSY is returned in this case.

7619 **

7620 ** ^If parameter zDb is NULL or points to a zero length string, then the

7621 ** specified operation is attempted on all WAL databases [attached] to

7622 ** [database connection] db. In this case the

7623 ** values written to output parameters pnLog and pnCkpt are undefined. ^If

7624 ** an SQLITE_BUSY error is encountered when processing one or more of the

7625 ** attached WAL databases, the operation is still attempted on any remaining

7626 ** attached databases and SQLITE_BUSY is returned at the end. ^If any other

7627 ** error occurs while processing an attached database, processing is abandoned

7628 ** and the error code is returned to the caller immediately. ^If no error

7629 ** (SQLITE_BUSY or otherwise) is encountered while processing the attached

7630 ** databases, SQLITE_OK is returned.

7631 **

7632 ** ^If database zDb is the name of an attached database that is not in WAL

7633 ** mode, SQLITE_OK is returned and both pnLog and pnCkpt set to -1. ^If

7634 ** zDb is not NULL (or a zero length string) and is not the name of any

7635 ** attached database, SQLITE_ERROR is returned to the caller.

7636 **

7637 ** ^Unless it returns SQLITE_MISUSE,

7638 ** the sqlite3_wal_checkpoint_v2() interface

7639 ** sets the error information that is queried by

7640 ** [sqlite3_errcode()] and [sqlite3_errmsg()].

7641 **

7642 ** ^The [PRAGMA wal_checkpoint] command can be used to invoke this interface

7643 ** from SQL.

7644 */

7645 int sqlite3_wal_checkpoint_v2(

7646 sqlite3 db, / Database handle */

7647 const char zDb, / Name of attached database (or NULL) */

7648 int eMode, /* SQLITE_CHECKPOINT_* value */

7649 int pnLog, / OUT: Size of WAL log in frames */

7650 int pnCkpt / OUT: Total number of frames checkpointed */

7651 );

7652

7653 /*

7654 ** CAPI3REF: Checkpoint Mode Values

7655 ** KEYWORDS: {checkpoint mode}

7656 **

7657 ** These constants define all valid values for the "checkpoint mode" passed

7658 ** as the third parameter to the [sqlite3_wal_checkpoint_v2()] interface.

7659 ** See the [sqlite3_wal_checkpoint_v2()] documentation for details on the

7660 ** meaning of each of these checkpoint modes.

7661 */

7662 #define SQLITE_CHECKPOINT_PASSIVE 0 /* Do as much as possible w/o blocking */

7663 #define SQLITE_CHECKPOINT_FULL 1 /* Wait for writers, then checkpoint */

7664 #define SQLITE_CHECKPOINT_RESTART 2 /* Like FULL but wait for for readers */

7665 #define SQLITE_CHECKPOINT_TRUNCATE 3 /* Like RESTART but also truncate WAL */

7666

7667 /*

7668 ** CAPI3REF: Virtual Table Interface Configuration

7669 **

7670 ** This function may be called by either the [xConnect] or [xCreate] method

7671 ** of a [virtual table] implementation to configure

7672 ** various facets of the virtual table interface.

7673 **

7674 ** If this interface is invoked outside the context of an xConnect or

7675 ** xCreate virtual table method then the behavior is undefined.

7676 **

7677 ** At present, there is only one option that may be configured using

7678 ** this function. (See [SQLITE_VTAB_CONSTRAINT_SUPPORT].) Further options

7679 ** may be added in the future.

7680 */

7681 int sqlite3_vtab_config(sqlite3*, int op, ...);

7682

7683 /*

7684 ** CAPI3REF: Virtual Table Configuration Options

7685 **

7686 ** These macros define the various options to the

7687 ** [sqlite3_vtab_config()] interface that [virtual table] implementations

7688 ** can use to customize and optimize their behavior.

7689 **

7690 ** <dl>

7691 ** <dt>SQLITE_VTAB_CONSTRAINT_SUPPORT

7692 ** <dd>Calls of the form

7693 ** [sqlite3_vtab_config](db,SQLITE_VTAB_CONSTRAINT_SUPPORT,X) are supported,

7694 ** where X is an integer. If X is zero, then the [virtual table] whose

7695 ** [xCreate] or [xConnect] method invoked [sqlite3_vtab_config()] does not

7696 ** support constraints. In this configuration (which is the default) if

7697 ** a call to the [xUpdate] method returns [SQLITE_CONSTRAINT], then the entire

7698 ** statement is rolled back as if [ON CONFLICT \| OR ABORT] had been

7699 ** specified as part of the users SQL statement, regardless of the actual

7700 ** ON CONFLICT mode specified.

7701 **

7702 ** If X is non-zero, then the virtual table implementation guarantees

7703 ** that if [xUpdate] returns [SQLITE_CONSTRAINT], it will do so before

7704 ** any modifications to internal or persistent data structures have been made.

7705 ** If the [ON CONFLICT] mode is ABORT, FAIL, IGNORE or ROLLBACK, SQLite

7706 ** is able to roll back a statement or database transaction, and abandon

7707 ** or continue processing the current SQL statement as appropriate.

7708 ** If the ON CONFLICT mode is REPLACE and the [xUpdate] method returns

7709 ** [SQLITE_CONSTRAINT], SQLite handles this as if the ON CONFLICT mode

7710 ** had been ABORT.

7711 **

7712 ** Virtual table implementations that are required to handle OR REPLACE

7713 ** must do so within the [xUpdate] method. If a call to the

7714 ** [sqlite3_vtab_on_conflict()] function indicates that the current ON

7715 ** CONFLICT policy is REPLACE, the virtual table implementation should

7716 ** silently replace the appropriate rows within the xUpdate callback and

7717 ** return SQLITE_OK. Or, if this is not possible, it may return

7718 ** SQLITE_CONSTRAINT, in which case SQLite falls back to OR ABORT

7719 ** constraint handling.

7720 ** </dl>

7721 */

7722 #define SQLITE_VTAB_CONSTRAINT_SUPPORT 1

7723

7724 /*

7725 ** CAPI3REF: Determine The Virtual Table Conflict Policy

7726 **

7727 ** This function may only be called from within a call to the [xUpdate] method

7728 ** of a [virtual table] implementation for an INSERT or UPDATE operation. ^The

7729 ** value returned is one of [SQLITE_ROLLBACK], [SQLITE_IGNORE], [SQLITE_FAIL],

7730 ** [SQLITE_ABORT], or [SQLITE_REPLACE], according to the [ON CONFLICT] mode

7731 ** of the SQL statement that triggered the call to the [xUpdate] method of the

7732 ** [virtual table].

7733 */

7734 int sqlite3_vtab_on_conflict(sqlite3 *);

7735

7736 /*

7737 ** CAPI3REF: Conflict resolution modes

7738 ** KEYWORDS: {conflict resolution mode}

7739 **

7740 ** These constants are returned by [sqlite3_vtab_on_conflict()] to

7741 ** inform a [virtual table] implementation what the [ON CONFLICT] mode

7742 ** is for the SQL statement being evaluated.

7743 **

7744 ** Note that the [SQLITE_IGNORE] constant is also used as a potential

7745 ** return value from the [sqlite3_set_authorizer()] callback and that

7746 ** [SQLITE_ABORT] is also a [result code].

7747 */

7748 #define SQLITE_ROLLBACK 1

7749 /* #define SQLITE_IGNORE 2 // Also used by sqlite3_authorizer() callback */

7750 #define SQLITE_FAIL 3

7751 /* #define SQLITE_ABORT 4 // Also an error code */

7752 #define SQLITE_REPLACE 5

7753

7754 /*

7755 ** CAPI3REF: Prepared Statement Scan Status Opcodes

7756 ** KEYWORDS: {scanstatus options}

7757 **

7758 ** The following constants can be used for the T parameter to the

7759 ** [sqlite3_stmt_scanstatus(S,X,T,V)] interface. Each constant designates a

7760 ** different metric for sqlite3_stmt_scanstatus() to return.

7761 **

7762 ** When the value returned to V is a string, space to hold that string is

7763 ** managed by the prepared statement S and will be automatically freed when

7764 ** S is finalized.

7765 **

7766 ** <dl>

7767 ** [[SQLITE_SCANSTAT_NLOOP]] <dt>SQLITE_SCANSTAT_NLOOP</dt>

7768 ** <dd>^The [sqlite3_int64] variable pointed to by the T parameter will be

7769 ** set to the total number of times that the X-th loop has run.</dd>

7770 **

7771 ** [[SQLITE_SCANSTAT_NVISIT]] <dt>SQLITE_SCANSTAT_NVISIT</dt>

7772 ** <dd>^The [sqlite3_int64] variable pointed to by the T parameter will be set

7773 ** to the total number of rows examined by all iterations of the X-th loop.</dd>

7774 **

7775 ** [[SQLITE_SCANSTAT_EST]] <dt>SQLITE_SCANSTAT_EST</dt>

7776 ** <dd>^The "double" variable pointed to by the T parameter will be set to the

7777 ** query planner's estimate for the average number of rows output from each

7778 ** iteration of the X-th loop. If the query planner's estimates was accurate,

7779 ** then this value will approximate the quotient NVISIT/NLOOP and the

7780 ** product of this value for all prior loops with the same SELECTID will

7781 ** be the NLOOP value for the current loop.

7782 **

7783 ** [[SQLITE_SCANSTAT_NAME]] <dt>SQLITE_SCANSTAT_NAME</dt>

7784 ** <dd>^The "const char *" variable pointed to by the T parameter will be set

7785 ** to a zero-terminated UTF-8 string containing the name of the index or table

7786 ** used for the X-th loop.

7787 **

7788 ** [[SQLITE_SCANSTAT_EXPLAIN]] <dt>SQLITE_SCANSTAT_EXPLAIN</dt>

7789 ** <dd>^The "const char *" variable pointed to by the T parameter will be set

7790 ** to a zero-terminated UTF-8 string containing the [EXPLAIN QUERY PLAN]

7791 ** description for the X-th loop.

7792 **

7793 ** [[SQLITE_SCANSTAT_SELECTID]] <dt>SQLITE_SCANSTAT_SELECT</dt>

7794 ** <dd>^The "int" variable pointed to by the T parameter will be set to the

7795 ** "select-id" for the X-th loop. The select-id identifies which query or

7796 ** subquery the loop is part of. The main query has a select-id of zero.

7797 ** The select-id is the same value as is output in the first column

7798 ** of an [EXPLAIN QUERY PLAN] query.

7799 ** </dl>

7800 */

7801 #define SQLITE_SCANSTAT_NLOOP 0

7802 #define SQLITE_SCANSTAT_NVISIT 1

7803 #define SQLITE_SCANSTAT_EST 2

7804 #define SQLITE_SCANSTAT_NAME 3

7805 #define SQLITE_SCANSTAT_EXPLAIN 4

7806 #define SQLITE_SCANSTAT_SELECTID 5

7807

7808 /*

7809 ** CAPI3REF: Prepared Statement Scan Status

7810 ** METHOD: sqlite3_stmt

7811 **

7812 ** This interface returns information about the predicted and measured

7813 ** performance for pStmt. Advanced applications can use this

7814 ** interface to compare the predicted and the measured performance and

7815 ** issue warnings and/or rerun [ANALYZE] if discrepancies are found.

7816 **

7817 ** Since this interface is expected to be rarely used, it is only

7818 ** available if SQLite is compiled using the [SQLITE_ENABLE_STMT_SCANSTATUS]

7819 ** compile-time option.

7820 **

7821 ** The "iScanStatusOp" parameter determines which status information to return.

7822 ** The "iScanStatusOp" must be one of the [scanstatus options] or the behavior

7823 ** of this interface is undefined.

7824 ** ^The requested measurement is written into a variable pointed to by

7825 ** the "pOut" parameter.

7826 ** Parameter "idx" identifies the specific loop to retrieve statistics for.

7827 ** Loops are numbered starting from zero. ^If idx is out of range - less than

7828 ** zero or greater than or equal to the total number of loops used to implement

7829 ** the statement - a non-zero value is returned and the variable that pOut

7830 ** points to is unchanged.

7831 **

7832 ** ^Statistics might not be available for all loops in all statements. ^In cases

7833 ** where there exist loops with no available statistics, this function behaves

7834 ** as if the loop did not exist - it returns non-zero and leave the variable

7835 ** that pOut points to unchanged.

7836 **

7837 ** See also: [sqlite3_stmt_scanstatus_reset()]

7838 */

7839 int sqlite3_stmt_scanstatus(

7840 sqlite3_stmt pStmt, / Prepared statement for which info desired */

7841 int idx, /* Index of loop to report on */

7842 int iScanStatusOp, /* Information desired. SQLITE_SCANSTAT_* */

7843 void pOut / Result written here */

7844 );

7845

7846 /*

7847 ** CAPI3REF: Zero Scan-Status Counters

7848 ** METHOD: sqlite3_stmt

7849 **

7850 ** ^Zero all [sqlite3_stmt_scanstatus()] related event counters.

7851 **

7852 ** This API is only available if the library is built with pre-processor

7853 ** symbol [SQLITE_ENABLE_STMT_SCANSTATUS] defined.

7854 */

7855 void sqlite3_stmt_scanstatus_reset(sqlite3_stmt*);

7856

7857 /*

7858 ** CAPI3REF: Flush caches to disk mid-transaction

7859 **

7860 ** ^If a write-transaction is open on [database connection] D when the

7861 ** [sqlite3_db_cacheflush(D)] interface invoked, any dirty

7862 ** pages in the pager-cache that are not currently in use are written out

7863 ** to disk. A dirty page may be in use if a database cursor created by an

7864 ** active SQL statement is reading from it, or if it is page 1 of a database

7865 ** file (page 1 is always "in use"). ^The [sqlite3_db_cacheflush(D)]

7866 ** interface flushes caches for all schemas - "main", "temp", and

7867 ** any [attached] databases.

7868 **

7869 ** ^If this function needs to obtain extra database locks before dirty pages

7870 ** can be flushed to disk, it does so. ^If those locks cannot be obtained

7871 ** immediately and there is a busy-handler callback configured, it is invoked

7872 ** in the usual manner. ^If the required lock still cannot be obtained, then

7873 ** the database is skipped and an attempt made to flush any dirty pages

7874 ** belonging to the next (if any) database. ^If any databases are skipped

7875 ** because locks cannot be obtained, but no other error occurs, this

7876 ** function returns SQLITE_BUSY.

7877 **

7878 ** ^If any other error occurs while flushing dirty pages to disk (for

7879 ** example an IO error or out-of-memory condition), then processing is

7880 ** abandoned and an SQLite [error code] is returned to the caller immediately.

7881 **

7882 ** ^Otherwise, if no error occurs, [sqlite3_db_cacheflush()] returns SQLITE_OK.

7883 **

7884 ** ^This function does not set the database handle error code or message

7885 ** returned by the [sqlite3_errcode()] and [sqlite3_errmsg()] functions.

7886 */

7887 int sqlite3_db_cacheflush(sqlite3*);

7888

7889 /*

7890 ** CAPI3REF: Database Snapshot

7891 ** KEYWORDS: {snapshot}

7892 ** EXPERIMENTAL

7893 **

7894 ** An instance of the snapshot object records the state of a [WAL mode]

7895 ** database for some specific point in history.

7896 **

7897 ** In [WAL mode], multiple [database connections] that are open on the

7898 ** same database file can each be reading a different historical version

7899 ** of the database file. When a [database connection] begins a read

7900 ** transaction, that connection sees an unchanging copy of the database

7901 ** as it existed for the point in time when the transaction first started.

7902 ** Subsequent changes to the database from other connections are not seen

7903 ** by the reader until a new read transaction is started.

7904 **

7905 ** The sqlite3_snapshot object records state information about an historical

7906 ** version of the database file so that it is possible to later open a new read

7907 ** transaction that sees that historical version of the database rather than

7908 ** the most recent version.

7909 **

7910 ** The constructor for this object is [sqlite3_snapshot_get()]. The

7911 ** [sqlite3_snapshot_open()] method causes a fresh read transaction to refer

7912 ** to an historical snapshot (if possible). The destructor for

7913 ** sqlite3_snapshot objects is [sqlite3_snapshot_free()].

7914 */

7915 typedef struct sqlite3_snapshot sqlite3_snapshot;

7916

7917 /*

7918 ** CAPI3REF: Record A Database Snapshot

7919 ** EXPERIMENTAL

7920 **

7921 ** ^The [sqlite3_snapshot_get(D,S,P)] interface attempts to make a

7922 ** new [sqlite3_snapshot] object that records the current state of

7923 ** schema S in database connection D. ^On success, the

7924 ** [sqlite3_snapshot_get(D,S,P)] interface writes a pointer to the newly

7925 ** created [sqlite3_snapshot] object into *P and returns SQLITE_OK.

7926 ** ^If schema S of [database connection] D is not a [WAL mode] database

7927 ** that is in a read transaction, then [sqlite3_snapshot_get(D,S,P)]

7928 ** leaves the *P value unchanged and returns an appropriate [error code].

7929 **

7930 ** The [sqlite3_snapshot] object returned from a successful call to

7931 ** [sqlite3_snapshot_get()] must be freed using [sqlite3_snapshot_free()]

7932 ** to avoid a memory leak.

7933 **

7934 ** The [sqlite3_snapshot_get()] interface is only available when the

7935 ** SQLITE_ENABLE_SNAPSHOT compile-time option is used.

7936 */

7937 SQLITE_EXPERIMENTAL int sqlite3_snapshot_get(

7938 sqlite3 *db,

7939 const char *zSchema,

7940 sqlite3_snapshot **ppSnapshot

7941 );

7942

7943 /*

7944 ** CAPI3REF: Start a read transaction on an historical snapshot

7945 ** EXPERIMENTAL

7946 **

7947 ** ^The [sqlite3_snapshot_open(D,S,P)] interface attempts to move the

7948 ** read transaction that is currently open on schema S of

7949 ** [database connection] D so that it refers to historical [snapshot] P.

7950 ** ^The [sqlite3_snapshot_open()] interface returns SQLITE_OK on success

7951 ** or an appropriate [error code] if it fails.

7952 **

7953 ** ^In order to succeed, a call to [sqlite3_snapshot_open(D,S,P)] must be

7954 ** the first operation, apart from other sqlite3_snapshot_open() calls,

7955 ** following the [BEGIN] that starts a new read transaction.

7956 ** ^A [snapshot] will fail to open if it has been overwritten by a

7957 ** [checkpoint].

7958 **

7959 ** The [sqlite3_snapshot_open()] interface is only available when the

7960 ** SQLITE_ENABLE_SNAPSHOT compile-time option is used.

7961 */

7962 SQLITE_EXPERIMENTAL int sqlite3_snapshot_open(

7963 sqlite3 *db,

7964 const char *zSchema,

7965 sqlite3_snapshot *pSnapshot

7966 );

7967

7968 /*

7969 ** CAPI3REF: Destroy a snapshot

7970 ** EXPERIMENTAL

7971 **

7972 ** ^The [sqlite3_snapshot_free(P)] interface destroys [sqlite3_snapshot] P.

7973 ** The application must eventually free every [sqlite3_snapshot] object

7974 ** using this routine to avoid a memory leak.

7975 **

7976 ** The [sqlite3_snapshot_free()] interface is only available when the

7977 ** SQLITE_ENABLE_SNAPSHOT compile-time option is used.

7978 */

7979 SQLITE_EXPERIMENTAL void sqlite3_snapshot_free(sqlite3_snapshot*);

7980

7981 /*

7982 ** Undo the hack that converts floating point types to integer for

7983 ** builds on processors without floating point support.

7984 */

7985 #ifdef SQLITE_OMIT_FLOATING_POINT

7986 # undef double

7987 #endif

7988

7989 #ifdef __cplusplus

7990 } /* End of the 'extern "C"' block */

7991 #endif

7992 #endif /* _SQLITE3_H_ */

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