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| 1 /* |
| 2 ** 2001 September 16 |
| 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 ** |
| 13 ** This header file (together with is companion C source-code file |
| 14 ** "os.c") attempt to abstract the underlying operating system so that |
| 15 ** the SQLite library will work on both POSIX and windows systems. |
| 16 ** |
| 17 ** This header file is #include-ed by sqliteInt.h and thus ends up |
| 18 ** being included by every source file. |
| 19 */ |
| 20 #ifndef _SQLITE_OS_H_ |
| 21 #define _SQLITE_OS_H_ |
| 22 |
| 23 /* |
| 24 ** Figure out if we are dealing with Unix, Windows, or some other |
| 25 ** operating system. After the following block of preprocess macros, |
| 26 ** all of SQLITE_OS_UNIX, SQLITE_OS_WIN, SQLITE_OS_OS2, and SQLITE_OS_OTHER |
| 27 ** will defined to either 1 or 0. One of the four will be 1. The other |
| 28 ** three will be 0. |
| 29 */ |
| 30 #if defined(SQLITE_OS_OTHER) |
| 31 # if SQLITE_OS_OTHER==1 |
| 32 # undef SQLITE_OS_UNIX |
| 33 # define SQLITE_OS_UNIX 0 |
| 34 # undef SQLITE_OS_WIN |
| 35 # define SQLITE_OS_WIN 0 |
| 36 # undef SQLITE_OS_OS2 |
| 37 # define SQLITE_OS_OS2 0 |
| 38 # else |
| 39 # undef SQLITE_OS_OTHER |
| 40 # endif |
| 41 #endif |
| 42 #if !defined(SQLITE_OS_UNIX) && !defined(SQLITE_OS_OTHER) |
| 43 # define SQLITE_OS_OTHER 0 |
| 44 # ifndef SQLITE_OS_WIN |
| 45 # if defined(_WIN32) || defined(WIN32) || defined(__CYGWIN__) || defined(__MIN
GW32__) || defined(__BORLANDC__) |
| 46 # define SQLITE_OS_WIN 1 |
| 47 # define SQLITE_OS_UNIX 0 |
| 48 # define SQLITE_OS_OS2 0 |
| 49 # elif defined(__EMX__) || defined(_OS2) || defined(OS2) || defined(_OS2_) ||
defined(__OS2__) |
| 50 # define SQLITE_OS_WIN 0 |
| 51 # define SQLITE_OS_UNIX 0 |
| 52 # define SQLITE_OS_OS2 1 |
| 53 # else |
| 54 # define SQLITE_OS_WIN 0 |
| 55 # define SQLITE_OS_UNIX 1 |
| 56 # define SQLITE_OS_OS2 0 |
| 57 # endif |
| 58 # else |
| 59 # define SQLITE_OS_UNIX 0 |
| 60 # define SQLITE_OS_OS2 0 |
| 61 # endif |
| 62 #else |
| 63 # ifndef SQLITE_OS_WIN |
| 64 # define SQLITE_OS_WIN 0 |
| 65 # endif |
| 66 #endif |
| 67 |
| 68 /* |
| 69 ** Determine if we are dealing with WindowsCE - which has a much |
| 70 ** reduced API. |
| 71 */ |
| 72 #if defined(_WIN32_WCE) |
| 73 # define SQLITE_OS_WINCE 1 |
| 74 #else |
| 75 # define SQLITE_OS_WINCE 0 |
| 76 #endif |
| 77 |
| 78 |
| 79 /* |
| 80 ** Define the maximum size of a temporary filename |
| 81 */ |
| 82 #if SQLITE_OS_WIN |
| 83 # include <windows.h> |
| 84 # define SQLITE_TEMPNAME_SIZE (MAX_PATH+50) |
| 85 #elif SQLITE_OS_OS2 |
| 86 # if (__GNUC__ > 3 || __GNUC__ == 3 && __GNUC_MINOR__ >= 3) && defined(OS2_HIGH_
MEMORY) |
| 87 # include <os2safe.h> /* has to be included before os2.h for linking to work */ |
| 88 # endif |
| 89 # define INCL_DOSDATETIME |
| 90 # define INCL_DOSFILEMGR |
| 91 # define INCL_DOSERRORS |
| 92 # define INCL_DOSMISC |
| 93 # define INCL_DOSPROCESS |
| 94 # define INCL_DOSMODULEMGR |
| 95 # define INCL_DOSSEMAPHORES |
| 96 # include <os2.h> |
| 97 # include <uconv.h> |
| 98 # define SQLITE_TEMPNAME_SIZE (CCHMAXPATHCOMP) |
| 99 #else |
| 100 # define SQLITE_TEMPNAME_SIZE 200 |
| 101 #endif |
| 102 |
| 103 /* If the SET_FULLSYNC macro is not defined above, then make it |
| 104 ** a no-op |
| 105 */ |
| 106 #ifndef SET_FULLSYNC |
| 107 # define SET_FULLSYNC(x,y) |
| 108 #endif |
| 109 |
| 110 /* |
| 111 ** The default size of a disk sector |
| 112 */ |
| 113 #ifndef SQLITE_DEFAULT_SECTOR_SIZE |
| 114 # define SQLITE_DEFAULT_SECTOR_SIZE 512 |
| 115 #endif |
| 116 |
| 117 /* |
| 118 ** Temporary files are named starting with this prefix followed by 16 random |
| 119 ** alphanumeric characters, and no file extension. They are stored in the |
| 120 ** OS's standard temporary file directory, and are deleted prior to exit. |
| 121 ** If sqlite is being embedded in another program, you may wish to change the |
| 122 ** prefix to reflect your program's name, so that if your program exits |
| 123 ** prematurely, old temporary files can be easily identified. This can be done |
| 124 ** using -DSQLITE_TEMP_FILE_PREFIX=myprefix_ on the compiler command line. |
| 125 ** |
| 126 ** 2006-10-31: The default prefix used to be "sqlite_". But then |
| 127 ** Mcafee started using SQLite in their anti-virus product and it |
| 128 ** started putting files with the "sqlite" name in the c:/temp folder. |
| 129 ** This annoyed many windows users. Those users would then do a |
| 130 ** Google search for "sqlite", find the telephone numbers of the |
| 131 ** developers and call to wake them up at night and complain. |
| 132 ** For this reason, the default name prefix is changed to be "sqlite" |
| 133 ** spelled backwards. So the temp files are still identified, but |
| 134 ** anybody smart enough to figure out the code is also likely smart |
| 135 ** enough to know that calling the developer will not help get rid |
| 136 ** of the file. |
| 137 */ |
| 138 #ifndef SQLITE_TEMP_FILE_PREFIX |
| 139 # define SQLITE_TEMP_FILE_PREFIX "etilqs_" |
| 140 #endif |
| 141 |
| 142 /* |
| 143 ** The following values may be passed as the second argument to |
| 144 ** sqlite3OsLock(). The various locks exhibit the following semantics: |
| 145 ** |
| 146 ** SHARED: Any number of processes may hold a SHARED lock simultaneously. |
| 147 ** RESERVED: A single process may hold a RESERVED lock on a file at |
| 148 ** any time. Other processes may hold and obtain new SHARED locks. |
| 149 ** PENDING: A single process may hold a PENDING lock on a file at |
| 150 ** any one time. Existing SHARED locks may persist, but no new |
| 151 ** SHARED locks may be obtained by other processes. |
| 152 ** EXCLUSIVE: An EXCLUSIVE lock precludes all other locks. |
| 153 ** |
| 154 ** PENDING_LOCK may not be passed directly to sqlite3OsLock(). Instead, a |
| 155 ** process that requests an EXCLUSIVE lock may actually obtain a PENDING |
| 156 ** lock. This can be upgraded to an EXCLUSIVE lock by a subsequent call to |
| 157 ** sqlite3OsLock(). |
| 158 */ |
| 159 #define NO_LOCK 0 |
| 160 #define SHARED_LOCK 1 |
| 161 #define RESERVED_LOCK 2 |
| 162 #define PENDING_LOCK 3 |
| 163 #define EXCLUSIVE_LOCK 4 |
| 164 |
| 165 /* |
| 166 ** File Locking Notes: (Mostly about windows but also some info for Unix) |
| 167 ** |
| 168 ** We cannot use LockFileEx() or UnlockFileEx() on Win95/98/ME because |
| 169 ** those functions are not available. So we use only LockFile() and |
| 170 ** UnlockFile(). |
| 171 ** |
| 172 ** LockFile() prevents not just writing but also reading by other processes. |
| 173 ** A SHARED_LOCK is obtained by locking a single randomly-chosen |
| 174 ** byte out of a specific range of bytes. The lock byte is obtained at |
| 175 ** random so two separate readers can probably access the file at the |
| 176 ** same time, unless they are unlucky and choose the same lock byte. |
| 177 ** An EXCLUSIVE_LOCK is obtained by locking all bytes in the range. |
| 178 ** There can only be one writer. A RESERVED_LOCK is obtained by locking |
| 179 ** a single byte of the file that is designated as the reserved lock byte. |
| 180 ** A PENDING_LOCK is obtained by locking a designated byte different from |
| 181 ** the RESERVED_LOCK byte. |
| 182 ** |
| 183 ** On WinNT/2K/XP systems, LockFileEx() and UnlockFileEx() are available, |
| 184 ** which means we can use reader/writer locks. When reader/writer locks |
| 185 ** are used, the lock is placed on the same range of bytes that is used |
| 186 ** for probabilistic locking in Win95/98/ME. Hence, the locking scheme |
| 187 ** will support two or more Win95 readers or two or more WinNT readers. |
| 188 ** But a single Win95 reader will lock out all WinNT readers and a single |
| 189 ** WinNT reader will lock out all other Win95 readers. |
| 190 ** |
| 191 ** The following #defines specify the range of bytes used for locking. |
| 192 ** SHARED_SIZE is the number of bytes available in the pool from which |
| 193 ** a random byte is selected for a shared lock. The pool of bytes for |
| 194 ** shared locks begins at SHARED_FIRST. |
| 195 ** |
| 196 ** The same locking strategy and |
| 197 ** byte ranges are used for Unix. This leaves open the possiblity of having |
| 198 ** clients on win95, winNT, and unix all talking to the same shared file |
| 199 ** and all locking correctly. To do so would require that samba (or whatever |
| 200 ** tool is being used for file sharing) implements locks correctly between |
| 201 ** windows and unix. I'm guessing that isn't likely to happen, but by |
| 202 ** using the same locking range we are at least open to the possibility. |
| 203 ** |
| 204 ** Locking in windows is manditory. For this reason, we cannot store |
| 205 ** actual data in the bytes used for locking. The pager never allocates |
| 206 ** the pages involved in locking therefore. SHARED_SIZE is selected so |
| 207 ** that all locks will fit on a single page even at the minimum page size. |
| 208 ** PENDING_BYTE defines the beginning of the locks. By default PENDING_BYTE |
| 209 ** is set high so that we don't have to allocate an unused page except |
| 210 ** for very large databases. But one should test the page skipping logic |
| 211 ** by setting PENDING_BYTE low and running the entire regression suite. |
| 212 ** |
| 213 ** Changing the value of PENDING_BYTE results in a subtly incompatible |
| 214 ** file format. Depending on how it is changed, you might not notice |
| 215 ** the incompatibility right away, even running a full regression test. |
| 216 ** The default location of PENDING_BYTE is the first byte past the |
| 217 ** 1GB boundary. |
| 218 ** |
| 219 */ |
| 220 #ifdef SQLITE_OMIT_WSD |
| 221 # define PENDING_BYTE (0x40000000) |
| 222 #else |
| 223 # define PENDING_BYTE sqlite3PendingByte |
| 224 #endif |
| 225 #define RESERVED_BYTE (PENDING_BYTE+1) |
| 226 #define SHARED_FIRST (PENDING_BYTE+2) |
| 227 #define SHARED_SIZE 510 |
| 228 |
| 229 /* |
| 230 ** Wrapper around OS specific sqlite3_os_init() function. |
| 231 */ |
| 232 int sqlite3OsInit(void); |
| 233 |
| 234 /* |
| 235 ** Functions for accessing sqlite3_file methods |
| 236 */ |
| 237 int sqlite3OsClose(sqlite3_file*); |
| 238 int sqlite3OsRead(sqlite3_file*, void*, int amt, i64 offset); |
| 239 int sqlite3OsWrite(sqlite3_file*, const void*, int amt, i64 offset); |
| 240 int sqlite3OsTruncate(sqlite3_file*, i64 size); |
| 241 int sqlite3OsSync(sqlite3_file*, int); |
| 242 int sqlite3OsFileSize(sqlite3_file*, i64 *pSize); |
| 243 int sqlite3OsLock(sqlite3_file*, int); |
| 244 int sqlite3OsUnlock(sqlite3_file*, int); |
| 245 int sqlite3OsCheckReservedLock(sqlite3_file *id, int *pResOut); |
| 246 int sqlite3OsFileControl(sqlite3_file*,int,void*); |
| 247 #define SQLITE_FCNTL_DB_UNCHANGED 0xca093fa0 |
| 248 int sqlite3OsSectorSize(sqlite3_file *id); |
| 249 int sqlite3OsDeviceCharacteristics(sqlite3_file *id); |
| 250 int sqlite3OsShmMap(sqlite3_file *,int,int,int,void volatile **); |
| 251 int sqlite3OsShmLock(sqlite3_file *id, int, int, int); |
| 252 void sqlite3OsShmBarrier(sqlite3_file *id); |
| 253 int sqlite3OsShmUnmap(sqlite3_file *id, int); |
| 254 |
| 255 /* |
| 256 ** Functions for accessing sqlite3_vfs methods |
| 257 */ |
| 258 int sqlite3OsOpen(sqlite3_vfs *, const char *, sqlite3_file*, int, int *); |
| 259 int sqlite3OsDelete(sqlite3_vfs *, const char *, int); |
| 260 int sqlite3OsAccess(sqlite3_vfs *, const char *, int, int *pResOut); |
| 261 int sqlite3OsFullPathname(sqlite3_vfs *, const char *, int, char *); |
| 262 #ifndef SQLITE_OMIT_LOAD_EXTENSION |
| 263 void *sqlite3OsDlOpen(sqlite3_vfs *, const char *); |
| 264 void sqlite3OsDlError(sqlite3_vfs *, int, char *); |
| 265 void (*sqlite3OsDlSym(sqlite3_vfs *, void *, const char *))(void); |
| 266 void sqlite3OsDlClose(sqlite3_vfs *, void *); |
| 267 #endif /* SQLITE_OMIT_LOAD_EXTENSION */ |
| 268 int sqlite3OsRandomness(sqlite3_vfs *, int, char *); |
| 269 int sqlite3OsSleep(sqlite3_vfs *, int); |
| 270 int sqlite3OsCurrentTimeInt64(sqlite3_vfs *, sqlite3_int64*); |
| 271 |
| 272 /* |
| 273 ** Convenience functions for opening and closing files using |
| 274 ** sqlite3_malloc() to obtain space for the file-handle structure. |
| 275 */ |
| 276 int sqlite3OsOpenMalloc(sqlite3_vfs *, const char *, sqlite3_file **, int,int*); |
| 277 int sqlite3OsCloseFree(sqlite3_file *); |
| 278 |
| 279 #endif /* _SQLITE_OS_H_ */ |
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