/* ** 2001 September 16 ** ** The author disclaims copyright to this source code. In place of ** a legal notice, here is a blessing: ** ** May you do good and not evil. ** May you find forgiveness for yourself and forgive others. ** May you share freely, never taking more than you give. ** ****************************************************************************** ** ** This header file (together with is companion C source-code file ** "os.c") attempt to abstract the underlying operating system so that ** the SQLite library will work on both POSIX and windows systems. ** ** This header file is #include-ed by sqliteInt.h and thus ends up ** being included by every source file. */ #ifndef _SQLITE_OS_H_ #define _SQLITE_OS_H_ /* ** Figure out if we are dealing with Unix, Windows, or some other ** operating system. After the following block of preprocess macros, ** all of SQLITE_OS_UNIX, SQLITE_OS_WIN, SQLITE_OS_OS2, and SQLITE_OS_OTHER ** will defined to either 1 or 0. One of the four will be 1. The other ** three will be 0. */ #if defined(SQLITE_OS_OTHER) # if SQLITE_OS_OTHER==1 # undef SQLITE_OS_UNIX # define SQLITE_OS_UNIX 0 # undef SQLITE_OS_WIN # define SQLITE_OS_WIN 0 # undef SQLITE_OS_OS2 # define SQLITE_OS_OS2 0 # else # undef SQLITE_OS_OTHER # endif #endif #if !defined(SQLITE_OS_UNIX) && !defined(SQLITE_OS_OTHER) # define SQLITE_OS_OTHER 0 # ifndef SQLITE_OS_WIN # if defined(_WIN32) || defined(WIN32) || defined(__CYGWIN__) || defined(__MINGW32__) || defined(__BORLANDC__) # define SQLITE_OS_WIN 1 # define SQLITE_OS_UNIX 0 # define SQLITE_OS_OS2 0 # elif defined(__EMX__) || defined(_OS2) || defined(OS2) || defined(_OS2_) || defined(__OS2__) # define SQLITE_OS_WIN 0 # define SQLITE_OS_UNIX 0 # define SQLITE_OS_OS2 1 # else # define SQLITE_OS_WIN 0 # define SQLITE_OS_UNIX 1 # define SQLITE_OS_OS2 0 # endif # else # define SQLITE_OS_UNIX 0 # define SQLITE_OS_OS2 0 # endif #else # ifndef SQLITE_OS_WIN # define SQLITE_OS_WIN 0 # endif #endif /* ** Determine if we are dealing with WindowsCE - which has a much ** reduced API. */ #if defined(_WIN32_WCE) # define SQLITE_OS_WINCE 1 #else # define SQLITE_OS_WINCE 0 #endif /* ** Define the maximum size of a temporary filename */ #if SQLITE_OS_WIN # include # define SQLITE_TEMPNAME_SIZE (MAX_PATH+50) #elif SQLITE_OS_OS2 # if (__GNUC__ > 3 || __GNUC__ == 3 && __GNUC_MINOR__ >= 3) && defined(OS2_HIGH_MEMORY) # include /* has to be included before os2.h for linking to work */ # endif # define INCL_DOSDATETIME # define INCL_DOSFILEMGR # define INCL_DOSERRORS # define INCL_DOSMISC # define INCL_DOSPROCESS # define INCL_DOSMODULEMGR # define INCL_DOSSEMAPHORES # include # include # define SQLITE_TEMPNAME_SIZE (CCHMAXPATHCOMP) #else # define SQLITE_TEMPNAME_SIZE 200 #endif /* If the SET_FULLSYNC macro is not defined above, then make it ** a no-op */ #ifndef SET_FULLSYNC # define SET_FULLSYNC(x,y) #endif /* ** The default size of a disk sector */ #ifndef SQLITE_DEFAULT_SECTOR_SIZE # define SQLITE_DEFAULT_SECTOR_SIZE 512 #endif /* ** Temporary files are named starting with this prefix followed by 16 random ** alphanumeric characters, and no file extension. They are stored in the ** OS's standard temporary file directory, and are deleted prior to exit. ** If sqlite is being embedded in another program, you may wish to change the ** prefix to reflect your program's name, so that if your program exits ** prematurely, old temporary files can be easily identified. This can be done ** using -DSQLITE_TEMP_FILE_PREFIX=myprefix_ on the compiler command line. ** ** 2006-10-31: The default prefix used to be "sqlite_". But then ** Mcafee started using SQLite in their anti-virus product and it ** started putting files with the "sqlite" name in the c:/temp folder. ** This annoyed many windows users. Those users would then do a ** Google search for "sqlite", find the telephone numbers of the ** developers and call to wake them up at night and complain. ** For this reason, the default name prefix is changed to be "sqlite" ** spelled backwards. So the temp files are still identified, but ** anybody smart enough to figure out the code is also likely smart ** enough to know that calling the developer will not help get rid ** of the file. */ #ifndef SQLITE_TEMP_FILE_PREFIX # define SQLITE_TEMP_FILE_PREFIX "etilqs_" #endif /* ** The following values may be passed as the second argument to ** sqlite3OsLock(). The various locks exhibit the following semantics: ** ** SHARED: Any number of processes may hold a SHARED lock simultaneously. ** RESERVED: A single process may hold a RESERVED lock on a file at ** any time. Other processes may hold and obtain new SHARED locks. ** PENDING: A single process may hold a PENDING lock on a file at ** any one time. Existing SHARED locks may persist, but no new ** SHARED locks may be obtained by other processes. ** EXCLUSIVE: An EXCLUSIVE lock precludes all other locks. ** ** PENDING_LOCK may not be passed directly to sqlite3OsLock(). Instead, a ** process that requests an EXCLUSIVE lock may actually obtain a PENDING ** lock. This can be upgraded to an EXCLUSIVE lock by a subsequent call to ** sqlite3OsLock(). */ #define NO_LOCK 0 #define SHARED_LOCK 1 #define RESERVED_LOCK 2 #define PENDING_LOCK 3 #define EXCLUSIVE_LOCK 4 /* ** File Locking Notes: (Mostly about windows but also some info for Unix) ** ** We cannot use LockFileEx() or UnlockFileEx() on Win95/98/ME because ** those functions are not available. So we use only LockFile() and ** UnlockFile(). ** ** LockFile() prevents not just writing but also reading by other processes. ** A SHARED_LOCK is obtained by locking a single randomly-chosen ** byte out of a specific range of bytes. The lock byte is obtained at ** random so two separate readers can probably access the file at the ** same time, unless they are unlucky and choose the same lock byte. ** An EXCLUSIVE_LOCK is obtained by locking all bytes in the range. ** There can only be one writer. A RESERVED_LOCK is obtained by locking ** a single byte of the file that is designated as the reserved lock byte. ** A PENDING_LOCK is obtained by locking a designated byte different from ** the RESERVED_LOCK byte. ** ** On WinNT/2K/XP systems, LockFileEx() and UnlockFileEx() are available, ** which means we can use reader/writer locks. When reader/writer locks ** are used, the lock is placed on the same range of bytes that is used ** for probabilistic locking in Win95/98/ME. Hence, the locking scheme ** will support two or more Win95 readers or two or more WinNT readers. ** But a single Win95 reader will lock out all WinNT readers and a single ** WinNT reader will lock out all other Win95 readers. ** ** The following #defines specify the range of bytes used for locking. ** SHARED_SIZE is the number of bytes available in the pool from which ** a random byte is selected for a shared lock. The pool of bytes for ** shared locks begins at SHARED_FIRST. ** ** The same locking strategy and ** byte ranges are used for Unix. This leaves open the possiblity of having ** clients on win95, winNT, and unix all talking to the same shared file ** and all locking correctly. To do so would require that samba (or whatever ** tool is being used for file sharing) implements locks correctly between ** windows and unix. I'm guessing that isn't likely to happen, but by ** using the same locking range we are at least open to the possibility. ** ** Locking in windows is manditory. For this reason, we cannot store ** actual data in the bytes used for locking. The pager never allocates ** the pages involved in locking therefore. SHARED_SIZE is selected so ** that all locks will fit on a single page even at the minimum page size. ** PENDING_BYTE defines the beginning of the locks. By default PENDING_BYTE ** is set high so that we don't have to allocate an unused page except ** for very large databases. But one should test the page skipping logic ** by setting PENDING_BYTE low and running the entire regression suite. ** ** Changing the value of PENDING_BYTE results in a subtly incompatible ** file format. Depending on how it is changed, you might not notice ** the incompatibility right away, even running a full regression test. ** The default location of PENDING_BYTE is the first byte past the ** 1GB boundary. ** */ #define PENDING_BYTE sqlite3PendingByte #define RESERVED_BYTE (PENDING_BYTE+1) #define SHARED_FIRST (PENDING_BYTE+2) #define SHARED_SIZE 510 /* ** Wrapper around OS specific sqlite3_os_init() function. */ int sqlite3OsInit(void); /* ** Functions for accessing sqlite3_file methods */ int sqlite3OsClose(sqlite3_file*); int sqlite3OsRead(sqlite3_file*, void*, int amt, i64 offset); int sqlite3OsWrite(sqlite3_file*, const void*, int amt, i64 offset); int sqlite3OsTruncate(sqlite3_file*, i64 size); int sqlite3OsSync(sqlite3_file*, int); int sqlite3OsFileSize(sqlite3_file*, i64 *pSize); int sqlite3OsLock(sqlite3_file*, int); int sqlite3OsUnlock(sqlite3_file*, int); int sqlite3OsCheckReservedLock(sqlite3_file *id, int *pResOut); int sqlite3OsFileControl(sqlite3_file*,int,void*); #define SQLITE_FCNTL_DB_UNCHANGED 0xca093fa0 int sqlite3OsSectorSize(sqlite3_file *id); int sqlite3OsDeviceCharacteristics(sqlite3_file *id); int sqlite3OsShmOpen(sqlite3_file *id); int sqlite3OsShmSize(sqlite3_file *id, int, int*); int sqlite3OsShmGet(sqlite3_file *id, int, int*, void volatile**); int sqlite3OsShmRelease(sqlite3_file *id); int sqlite3OsShmLock(sqlite3_file *id, int, int*); int sqlite3OsShmClose(sqlite3_file *id, int); /* ** Functions for accessing sqlite3_vfs methods */ int sqlite3OsOpen(sqlite3_vfs *, const char *, sqlite3_file*, int, int *); int sqlite3OsDelete(sqlite3_vfs *, const char *, int); int sqlite3OsAccess(sqlite3_vfs *, const char *, int, int *pResOut); int sqlite3OsFullPathname(sqlite3_vfs *, const char *, int, char *); #ifndef SQLITE_OMIT_LOAD_EXTENSION void *sqlite3OsDlOpen(sqlite3_vfs *, const char *); void sqlite3OsDlError(sqlite3_vfs *, int, char *); void (*sqlite3OsDlSym(sqlite3_vfs *, void *, const char *))(void); void sqlite3OsDlClose(sqlite3_vfs *, void *); #endif /* SQLITE_OMIT_LOAD_EXTENSION */ int sqlite3OsRandomness(sqlite3_vfs *, int, char *); int sqlite3OsSleep(sqlite3_vfs *, int); int sqlite3OsCurrentTimeInt64(sqlite3_vfs *, sqlite3_int64*); /* ** Convenience functions for opening and closing files using ** sqlite3_malloc() to obtain space for the file-handle structure. */ int sqlite3OsOpenMalloc(sqlite3_vfs *, const char *, sqlite3_file **, int,int*); int sqlite3OsCloseFree(sqlite3_file *); #endif /* _SQLITE_OS_H_ */