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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 ** Attempt to automatically detect the operating system and setup the | |
| 25 ** necessary pre-processor macros for it. | |
| 26 */ | |
| 27 #include "os_setup.h" | |
| 28 | |
| 29 /* If the SET_FULLSYNC macro is not defined above, then make it | |
| 30 ** a no-op | |
| 31 */ | |
| 32 #ifndef SET_FULLSYNC | |
| 33 # define SET_FULLSYNC(x,y) | |
| 34 #endif | |
| 35 | |
| 36 /* | |
| 37 ** The default size of a disk sector | |
| 38 */ | |
| 39 #ifndef SQLITE_DEFAULT_SECTOR_SIZE | |
| 40 # define SQLITE_DEFAULT_SECTOR_SIZE 4096 | |
| 41 #endif | |
| 42 | |
| 43 /* | |
| 44 ** Temporary files are named starting with this prefix followed by 16 random | |
| 45 ** alphanumeric characters, and no file extension. They are stored in the | |
| 46 ** OS's standard temporary file directory, and are deleted prior to exit. | |
| 47 ** If sqlite is being embedded in another program, you may wish to change the | |
| 48 ** prefix to reflect your program's name, so that if your program exits | |
| 49 ** prematurely, old temporary files can be easily identified. This can be done | |
| 50 ** using -DSQLITE_TEMP_FILE_PREFIX=myprefix_ on the compiler command line. | |
| 51 ** | |
| 52 ** 2006-10-31: The default prefix used to be "sqlite_". But then | |
| 53 ** Mcafee started using SQLite in their anti-virus product and it | |
| 54 ** started putting files with the "sqlite" name in the c:/temp folder. | |
| 55 ** This annoyed many windows users. Those users would then do a | |
| 56 ** Google search for "sqlite", find the telephone numbers of the | |
| 57 ** developers and call to wake them up at night and complain. | |
| 58 ** For this reason, the default name prefix is changed to be "sqlite" | |
| 59 ** spelled backwards. So the temp files are still identified, but | |
| 60 ** anybody smart enough to figure out the code is also likely smart | |
| 61 ** enough to know that calling the developer will not help get rid | |
| 62 ** of the file. | |
| 63 */ | |
| 64 #ifndef SQLITE_TEMP_FILE_PREFIX | |
| 65 # define SQLITE_TEMP_FILE_PREFIX "etilqs_" | |
| 66 #endif | |
| 67 | |
| 68 /* | |
| 69 ** The following values may be passed as the second argument to | |
| 70 ** sqlite3OsLock(). The various locks exhibit the following semantics: | |
| 71 ** | |
| 72 ** SHARED: Any number of processes may hold a SHARED lock simultaneously. | |
| 73 ** RESERVED: A single process may hold a RESERVED lock on a file at | |
| 74 ** any time. Other processes may hold and obtain new SHARED locks. | |
| 75 ** PENDING: A single process may hold a PENDING lock on a file at | |
| 76 ** any one time. Existing SHARED locks may persist, but no new | |
| 77 ** SHARED locks may be obtained by other processes. | |
| 78 ** EXCLUSIVE: An EXCLUSIVE lock precludes all other locks. | |
| 79 ** | |
| 80 ** PENDING_LOCK may not be passed directly to sqlite3OsLock(). Instead, a | |
| 81 ** process that requests an EXCLUSIVE lock may actually obtain a PENDING | |
| 82 ** lock. This can be upgraded to an EXCLUSIVE lock by a subsequent call to | |
| 83 ** sqlite3OsLock(). | |
| 84 */ | |
| 85 #define NO_LOCK 0 | |
| 86 #define SHARED_LOCK 1 | |
| 87 #define RESERVED_LOCK 2 | |
| 88 #define PENDING_LOCK 3 | |
| 89 #define EXCLUSIVE_LOCK 4 | |
| 90 | |
| 91 /* | |
| 92 ** File Locking Notes: (Mostly about windows but also some info for Unix) | |
| 93 ** | |
| 94 ** We cannot use LockFileEx() or UnlockFileEx() on Win95/98/ME because | |
| 95 ** those functions are not available. So we use only LockFile() and | |
| 96 ** UnlockFile(). | |
| 97 ** | |
| 98 ** LockFile() prevents not just writing but also reading by other processes. | |
| 99 ** A SHARED_LOCK is obtained by locking a single randomly-chosen | |
| 100 ** byte out of a specific range of bytes. The lock byte is obtained at | |
| 101 ** random so two separate readers can probably access the file at the | |
| 102 ** same time, unless they are unlucky and choose the same lock byte. | |
| 103 ** An EXCLUSIVE_LOCK is obtained by locking all bytes in the range. | |
| 104 ** There can only be one writer. A RESERVED_LOCK is obtained by locking | |
| 105 ** a single byte of the file that is designated as the reserved lock byte. | |
| 106 ** A PENDING_LOCK is obtained by locking a designated byte different from | |
| 107 ** the RESERVED_LOCK byte. | |
| 108 ** | |
| 109 ** On WinNT/2K/XP systems, LockFileEx() and UnlockFileEx() are available, | |
| 110 ** which means we can use reader/writer locks. When reader/writer locks | |
| 111 ** are used, the lock is placed on the same range of bytes that is used | |
| 112 ** for probabilistic locking in Win95/98/ME. Hence, the locking scheme | |
| 113 ** will support two or more Win95 readers or two or more WinNT readers. | |
| 114 ** But a single Win95 reader will lock out all WinNT readers and a single | |
| 115 ** WinNT reader will lock out all other Win95 readers. | |
| 116 ** | |
| 117 ** The following #defines specify the range of bytes used for locking. | |
| 118 ** SHARED_SIZE is the number of bytes available in the pool from which | |
| 119 ** a random byte is selected for a shared lock. The pool of bytes for | |
| 120 ** shared locks begins at SHARED_FIRST. | |
| 121 ** | |
| 122 ** The same locking strategy and | |
| 123 ** byte ranges are used for Unix. This leaves open the possibility of having | |
| 124 ** clients on win95, winNT, and unix all talking to the same shared file | |
| 125 ** and all locking correctly. To do so would require that samba (or whatever | |
| 126 ** tool is being used for file sharing) implements locks correctly between | |
| 127 ** windows and unix. I'm guessing that isn't likely to happen, but by | |
| 128 ** using the same locking range we are at least open to the possibility. | |
| 129 ** | |
| 130 ** Locking in windows is manditory. For this reason, we cannot store | |
| 131 ** actual data in the bytes used for locking. The pager never allocates | |
| 132 ** the pages involved in locking therefore. SHARED_SIZE is selected so | |
| 133 ** that all locks will fit on a single page even at the minimum page size. | |
| 134 ** PENDING_BYTE defines the beginning of the locks. By default PENDING_BYTE | |
| 135 ** is set high so that we don't have to allocate an unused page except | |
| 136 ** for very large databases. But one should test the page skipping logic | |
| 137 ** by setting PENDING_BYTE low and running the entire regression suite. | |
| 138 ** | |
| 139 ** Changing the value of PENDING_BYTE results in a subtly incompatible | |
| 140 ** file format. Depending on how it is changed, you might not notice | |
| 141 ** the incompatibility right away, even running a full regression test. | |
| 142 ** The default location of PENDING_BYTE is the first byte past the | |
| 143 ** 1GB boundary. | |
| 144 ** | |
| 145 */ | |
| 146 #ifdef SQLITE_OMIT_WSD | |
| 147 # define PENDING_BYTE (0x40000000) | |
| 148 #else | |
| 149 # define PENDING_BYTE sqlite3PendingByte | |
| 150 #endif | |
| 151 #define RESERVED_BYTE (PENDING_BYTE+1) | |
| 152 #define SHARED_FIRST (PENDING_BYTE+2) | |
| 153 #define SHARED_SIZE 510 | |
| 154 | |
| 155 /* | |
| 156 ** Wrapper around OS specific sqlite3_os_init() function. | |
| 157 */ | |
| 158 int sqlite3OsInit(void); | |
| 159 | |
| 160 /* | |
| 161 ** Functions for accessing sqlite3_file methods | |
| 162 */ | |
| 163 int sqlite3OsClose(sqlite3_file*); | |
| 164 int sqlite3OsRead(sqlite3_file*, void*, int amt, i64 offset); | |
| 165 int sqlite3OsWrite(sqlite3_file*, const void*, int amt, i64 offset); | |
| 166 int sqlite3OsTruncate(sqlite3_file*, i64 size); | |
| 167 int sqlite3OsSync(sqlite3_file*, int); | |
| 168 int sqlite3OsFileSize(sqlite3_file*, i64 *pSize); | |
| 169 int sqlite3OsLock(sqlite3_file*, int); | |
| 170 int sqlite3OsUnlock(sqlite3_file*, int); | |
| 171 int sqlite3OsCheckReservedLock(sqlite3_file *id, int *pResOut); | |
| 172 int sqlite3OsFileControl(sqlite3_file*,int,void*); | |
| 173 void sqlite3OsFileControlHint(sqlite3_file*,int,void*); | |
| 174 #define SQLITE_FCNTL_DB_UNCHANGED 0xca093fa0 | |
| 175 int sqlite3OsSectorSize(sqlite3_file *id); | |
| 176 int sqlite3OsDeviceCharacteristics(sqlite3_file *id); | |
| 177 int sqlite3OsShmMap(sqlite3_file *,int,int,int,void volatile **); | |
| 178 int sqlite3OsShmLock(sqlite3_file *id, int, int, int); | |
| 179 void sqlite3OsShmBarrier(sqlite3_file *id); | |
| 180 int sqlite3OsShmUnmap(sqlite3_file *id, int); | |
| 181 int sqlite3OsFetch(sqlite3_file *id, i64, int, void **); | |
| 182 int sqlite3OsUnfetch(sqlite3_file *, i64, void *); | |
| 183 | |
| 184 | |
| 185 /* | |
| 186 ** Functions for accessing sqlite3_vfs methods | |
| 187 */ | |
| 188 int sqlite3OsOpen(sqlite3_vfs *, const char *, sqlite3_file*, int, int *); | |
| 189 int sqlite3OsDelete(sqlite3_vfs *, const char *, int); | |
| 190 int sqlite3OsAccess(sqlite3_vfs *, const char *, int, int *pResOut); | |
| 191 int sqlite3OsFullPathname(sqlite3_vfs *, const char *, int, char *); | |
| 192 #ifndef SQLITE_OMIT_LOAD_EXTENSION | |
| 193 void *sqlite3OsDlOpen(sqlite3_vfs *, const char *); | |
| 194 void sqlite3OsDlError(sqlite3_vfs *, int, char *); | |
| 195 void (*sqlite3OsDlSym(sqlite3_vfs *, void *, const char *))(void); | |
| 196 void sqlite3OsDlClose(sqlite3_vfs *, void *); | |
| 197 #endif /* SQLITE_OMIT_LOAD_EXTENSION */ | |
| 198 int sqlite3OsRandomness(sqlite3_vfs *, int, char *); | |
| 199 int sqlite3OsSleep(sqlite3_vfs *, int); | |
| 200 int sqlite3OsCurrentTimeInt64(sqlite3_vfs *, sqlite3_int64*); | |
| 201 | |
| 202 /* | |
| 203 ** Convenience functions for opening and closing files using | |
| 204 ** sqlite3_malloc() to obtain space for the file-handle structure. | |
| 205 */ | |
| 206 int sqlite3OsOpenMalloc(sqlite3_vfs *, const char *, sqlite3_file **, int,int*); | |
| 207 int sqlite3OsCloseFree(sqlite3_file *); | |
| 208 | |
| 209 #endif /* _SQLITE_OS_H_ */ | |
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Chromium Code Reviews
Issue 2363173002:
[sqlite] Remove obsolete reference version 3.8.7.4. (Closed)
