webengine/webkitutils/SqliteSymbian/os.h
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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 #ifndef _SQLITE_OS_H_
       
    18 #define _SQLITE_OS_H_
       
    19 
       
    20 /*
       
    21 ** Figure out if we are dealing with Unix, Windows, or some other
       
    22 ** operating system.
       
    23 */
       
    24 #if !defined(OS_UNIX) && !defined(OS_OTHER)
       
    25 # define OS_OTHER 0
       
    26 # ifndef OS_WIN
       
    27 #   if defined(_WIN32) || defined(WIN32) || defined(__CYGWIN__) || defined(__MINGW32__) || defined(__BORLANDC__)
       
    28 #     define OS_WIN 1
       
    29 #     define OS_UNIX 0
       
    30 #     define OS_OS2 0
       
    31 #   elif defined(_EMX_) || defined(_OS2) || defined(OS2) || defined(_OS2_) || defined(__OS2__)
       
    32 #     define OS_WIN 0
       
    33 #     define OS_UNIX 0
       
    34 #     define OS_OS2 1
       
    35 #   else
       
    36 #     define OS_WIN 0
       
    37 #     define OS_UNIX 1
       
    38 #     define OS_OS2 0
       
    39 #  endif
       
    40 # else
       
    41 #  define OS_UNIX 0
       
    42 #  define OS_OS2 0
       
    43 # endif
       
    44 #else
       
    45 # ifndef OS_WIN
       
    46 #  define OS_WIN 0
       
    47 # endif
       
    48 #endif
       
    49 
       
    50 #undef OS_WIN
       
    51 #undef OS_UNIX
       
    52 #undef OS_OS2
       
    53 #undef OS_OTHER
       
    54 
       
    55 /*
       
    56 ** Define the maximum size of a temporary filename
       
    57 */
       
    58 #if OS_WIN
       
    59 # include <windows.h>
       
    60 # define SQLITE_TEMPNAME_SIZE (MAX_PATH+50)
       
    61 #elif OS_OS2
       
    62 # define INCL_DOSDATETIME
       
    63 # define INCL_DOSFILEMGR
       
    64 # define INCL_DOSERRORS
       
    65 # define INCL_DOSMISC
       
    66 # define INCL_DOSPROCESS
       
    67 # include <os2.h>
       
    68 # define SQLITE_TEMPNAME_SIZE (CCHMAXPATHCOMP)
       
    69 #else
       
    70 # define SQLITE_TEMPNAME_SIZE 200
       
    71 #endif
       
    72 
       
    73 /* If the SET_FULLSYNC macro is not defined above, then make it
       
    74 ** a no-op
       
    75 */
       
    76 #ifndef SET_FULLSYNC
       
    77 # define SET_FULLSYNC(x,y)
       
    78 #endif
       
    79 
       
    80 /*
       
    81 ** Temporary files are named starting with this prefix followed by 16 random
       
    82 ** alphanumeric characters, and no file extension. They are stored in the
       
    83 ** OS's standard temporary file directory, and are deleted prior to exit.
       
    84 ** If sqlite is being embedded in another program, you may wish to change the
       
    85 ** prefix to reflect your program's name, so that if your program exits
       
    86 ** prematurely, old temporary files can be easily identified. This can be done
       
    87 ** using -DTEMP_FILE_PREFIX=myprefix_ on the compiler command line.
       
    88 */
       
    89 #ifndef TEMP_FILE_PREFIX
       
    90 # define TEMP_FILE_PREFIX "sqlite_"
       
    91 #endif
       
    92 
       
    93 /*
       
    94 ** Define the interfaces for Unix, Windows, and OS/2.
       
    95 */
       
    96 #if OS_UNIX
       
    97 #define sqlite3OsOpenReadWrite      sqlite3UnixOpenReadWrite
       
    98 #define sqlite3OsOpenExclusive      sqlite3UnixOpenExclusive
       
    99 #define sqlite3OsOpenReadOnly       sqlite3UnixOpenReadOnly
       
   100 #define sqlite3OsDelete             sqlite3UnixDelete
       
   101 #define sqlite3OsFileExists         sqlite3UnixFileExists
       
   102 #define sqlite3OsFullPathname       sqlite3UnixFullPathname
       
   103 #define sqlite3OsIsDirWritable      sqlite3UnixIsDirWritable
       
   104 #define sqlite3OsSyncDirectory      sqlite3UnixSyncDirectory
       
   105 #define sqlite3OsTempFileName       sqlite3UnixTempFileName
       
   106 #define sqlite3OsRandomSeed         sqlite3UnixRandomSeed
       
   107 #define sqlite3OsSleep              sqlite3UnixSleep
       
   108 #define sqlite3OsCurrentTime        sqlite3UnixCurrentTime
       
   109 #define sqlite3OsEnterMutex         sqlite3UnixEnterMutex
       
   110 #define sqlite3OsLeaveMutex         sqlite3UnixLeaveMutex
       
   111 #define sqlite3OsInMutex            sqlite3UnixInMutex
       
   112 #define sqlite3OsThreadSpecificData sqlite3UnixThreadSpecificData
       
   113 #define sqlite3OsMalloc             sqlite3GenericMalloc
       
   114 #define sqlite3OsRealloc            sqlite3GenericRealloc
       
   115 #define sqlite3OsFree               sqlite3GenericFree
       
   116 #define sqlite3OsAllocationSize     sqlite3GenericAllocationSize
       
   117 #endif
       
   118 #if OS_WIN
       
   119 #define sqlite3OsOpenReadWrite      sqlite3WinOpenReadWrite
       
   120 #define sqlite3OsOpenExclusive      sqlite3WinOpenExclusive
       
   121 #define sqlite3OsOpenReadOnly       sqlite3WinOpenReadOnly
       
   122 #define sqlite3OsDelete             sqlite3WinDelete
       
   123 #define sqlite3OsFileExists         sqlite3WinFileExists
       
   124 #define sqlite3OsFullPathname       sqlite3WinFullPathname
       
   125 #define sqlite3OsIsDirWritable      sqlite3WinIsDirWritable
       
   126 #define sqlite3OsSyncDirectory      sqlite3WinSyncDirectory
       
   127 #define sqlite3OsTempFileName       sqlite3WinTempFileName
       
   128 #define sqlite3OsRandomSeed         sqlite3WinRandomSeed
       
   129 #define sqlite3OsSleep              sqlite3WinSleep
       
   130 #define sqlite3OsCurrentTime        sqlite3WinCurrentTime
       
   131 #define sqlite3OsEnterMutex         sqlite3WinEnterMutex
       
   132 #define sqlite3OsLeaveMutex         sqlite3WinLeaveMutex
       
   133 #define sqlite3OsInMutex            sqlite3WinInMutex
       
   134 #define sqlite3OsThreadSpecificData sqlite3WinThreadSpecificData
       
   135 #define sqlite3OsMalloc             sqlite3GenericMalloc
       
   136 #define sqlite3OsRealloc            sqlite3GenericRealloc
       
   137 #define sqlite3OsFree               sqlite3GenericFree
       
   138 #define sqlite3OsAllocationSize     sqlite3GenericAllocationSize
       
   139 #endif
       
   140 #if OS_OS2
       
   141 #define sqlite3OsOpenReadWrite      sqlite3Os2OpenReadWrite
       
   142 #define sqlite3OsOpenExclusive      sqlite3Os2OpenExclusive
       
   143 #define sqlite3OsOpenReadOnly       sqlite3Os2OpenReadOnly
       
   144 #define sqlite3OsDelete             sqlite3Os2Delete
       
   145 #define sqlite3OsFileExists         sqlite3Os2FileExists
       
   146 #define sqlite3OsFullPathname       sqlite3Os2FullPathname
       
   147 #define sqlite3OsIsDirWritable      sqlite3Os2IsDirWritable
       
   148 #define sqlite3OsSyncDirectory      sqlite3Os2SyncDirectory
       
   149 #define sqlite3OsTempFileName       sqlite3Os2TempFileName
       
   150 #define sqlite3OsRandomSeed         sqlite3Os2RandomSeed
       
   151 #define sqlite3OsSleep              sqlite3Os2Sleep
       
   152 #define sqlite3OsCurrentTime        sqlite3Os2CurrentTime
       
   153 #define sqlite3OsEnterMutex         sqlite3Os2EnterMutex
       
   154 #define sqlite3OsLeaveMutex         sqlite3Os2LeaveMutex
       
   155 #define sqlite3OsInMutex            sqlite3Os2InMutex
       
   156 #define sqlite3OsThreadSpecificData sqlite3Os2ThreadSpecificData
       
   157 #define sqlite3OsMalloc             sqlite3GenericMalloc
       
   158 #define sqlite3OsRealloc            sqlite3GenericRealloc
       
   159 #define sqlite3OsFree               sqlite3GenericFree
       
   160 #define sqlite3OsAllocationSize     sqlite3GenericAllocationSize
       
   161 #endif
       
   162 #if OS_SYMBIAN
       
   163 #define sqlite3OsOpenReadWrite      sqlite3SymbianOpenReadWrite
       
   164 #define sqlite3OsOpenExclusive      sqlite3SymbianOpenExclusive
       
   165 #define sqlite3OsOpenReadOnly       sqlite3SymbianOpenReadOnly
       
   166 #define sqlite3OsDelete             sqlite3SymbianDelete
       
   167 #define sqlite3OsFileExists         sqlite3SymbianFileExists
       
   168 #define sqlite3OsFullPathname       sqlite3SymbianFullPathname
       
   169 #define sqlite3OsIsDirWritable      sqlite3SymbianIsDirWritable
       
   170 #define sqlite3OsSyncDirectory      sqlite3SymbianSyncDirectory
       
   171 #define sqlite3OsTempFileName       sqlite3SymbianTempFileName
       
   172 #define sqlite3OsRandomSeed         sqlite3SymbianRandomSeed
       
   173 #define sqlite3OsSleep              sqlite3SymbianSleep
       
   174 #define sqlite3OsCurrentTime        sqlite3SymbianCurrentTime
       
   175 #define sqlite3OsEnterMutex         sqlite3SymbianEnterMutex
       
   176 #define sqlite3OsLeaveMutex         sqlite3SymbianLeaveMutex
       
   177 #define sqlite3OsInMutex            sqlite3SymbianInMutex
       
   178 #define sqlite3OsThreadSpecificData sqlite3SymbianThreadSpecificData
       
   179 #define sqlite3OsMalloc             sqlite3SymbianMalloc
       
   180 #define sqlite3OsRealloc            sqlite3SymbianRealloc
       
   181 #define sqlite3OsFree               sqlite3SymbianFree
       
   182 #define sqlite3OsAllocationSize     sqlite3SymbianAllocationSize
       
   183 #endif
       
   184 
       
   185 
       
   186 /*
       
   187 ** If using an alternative OS interface, then we must have an "os_other.h"
       
   188 ** header file available for that interface.  Presumably the "os_other.h"
       
   189 ** header file contains #defines similar to those above.
       
   190 */
       
   191 #if OS_OTHER
       
   192 # include "os_other.h"
       
   193 #endif
       
   194 
       
   195 
       
   196 
       
   197 /*
       
   198 ** Forward declarations
       
   199 */
       
   200 typedef struct OsFile OsFile;
       
   201 typedef struct IoMethod IoMethod;
       
   202 
       
   203 /*
       
   204 ** An instance of the following structure contains pointers to all
       
   205 ** methods on an OsFile object.
       
   206 */
       
   207 struct IoMethod {
       
   208   int (*xClose)(OsFile**);
       
   209   int (*xOpenDirectory)(OsFile*, const char*);
       
   210   int (*xRead)(OsFile*, void*, int amt);
       
   211   int (*xWrite)(OsFile*, const void*, int amt);
       
   212   int (*xSeek)(OsFile*, i64 offset);
       
   213   int (*xTruncate)(OsFile*, i64 size);
       
   214   int (*xSync)(OsFile*, int);
       
   215   void (*xSetFullSync)(OsFile *id, int setting);
       
   216   int (*xFileHandle)(OsFile *id);
       
   217   int (*xFileSize)(OsFile*, i64 *pSize);
       
   218   int (*xLock)(OsFile*, int);
       
   219   int (*xUnlock)(OsFile*, int);
       
   220   int (*xLockState)(OsFile *id);
       
   221   int (*xCheckReservedLock)(OsFile *id);
       
   222 };
       
   223 
       
   224 /*
       
   225 ** The OsFile object describes an open disk file in an OS-dependent way.
       
   226 ** The version of OsFile defined here is a generic version.  Each OS
       
   227 ** implementation defines its own subclass of this structure that contains
       
   228 ** additional information needed to handle file I/O.  But the pMethod
       
   229 ** entry (pointing to the virtual function table) always occurs first
       
   230 ** so that we can always find the appropriate methods.
       
   231 */
       
   232 struct OsFile {
       
   233   IoMethod const *pMethod;
       
   234 };
       
   235 
       
   236 /*
       
   237 ** The following values may be passed as the second argument to
       
   238 ** sqlite3OsLock(). The various locks exhibit the following semantics:
       
   239 **
       
   240 ** SHARED:    Any number of processes may hold a SHARED lock simultaneously.
       
   241 ** RESERVED:  A single process may hold a RESERVED lock on a file at
       
   242 **            any time. Other processes may hold and obtain new SHARED locks.
       
   243 ** PENDING:   A single process may hold a PENDING lock on a file at
       
   244 **            any one time. Existing SHARED locks may persist, but no new
       
   245 **            SHARED locks may be obtained by other processes.
       
   246 ** EXCLUSIVE: An EXCLUSIVE lock precludes all other locks.
       
   247 **
       
   248 ** PENDING_LOCK may not be passed directly to sqlite3OsLock(). Instead, a
       
   249 ** process that requests an EXCLUSIVE lock may actually obtain a PENDING
       
   250 ** lock. This can be upgraded to an EXCLUSIVE lock by a subsequent call to
       
   251 ** sqlite3OsLock().
       
   252 */
       
   253 #define NO_LOCK         0
       
   254 #define SHARED_LOCK     1
       
   255 #define RESERVED_LOCK   2
       
   256 #define PENDING_LOCK    3
       
   257 #define EXCLUSIVE_LOCK  4
       
   258 
       
   259 /*
       
   260 ** File Locking Notes:  (Mostly about windows but also some info for Unix)
       
   261 **
       
   262 ** We cannot use LockFileEx() or UnlockFileEx() on Win95/98/ME because
       
   263 ** those functions are not available.  So we use only LockFile() and
       
   264 ** UnlockFile().
       
   265 **
       
   266 ** LockFile() prevents not just writing but also reading by other processes.
       
   267 ** A SHARED_LOCK is obtained by locking a single randomly-chosen 
       
   268 ** byte out of a specific range of bytes. The lock byte is obtained at 
       
   269 ** random so two separate readers can probably access the file at the 
       
   270 ** same time, unless they are unlucky and choose the same lock byte.
       
   271 ** An EXCLUSIVE_LOCK is obtained by locking all bytes in the range.
       
   272 ** There can only be one writer.  A RESERVED_LOCK is obtained by locking
       
   273 ** a single byte of the file that is designated as the reserved lock byte.
       
   274 ** A PENDING_LOCK is obtained by locking a designated byte different from
       
   275 ** the RESERVED_LOCK byte.
       
   276 **
       
   277 ** On WinNT/2K/XP systems, LockFileEx() and UnlockFileEx() are available,
       
   278 ** which means we can use reader/writer locks.  When reader/writer locks
       
   279 ** are used, the lock is placed on the same range of bytes that is used
       
   280 ** for probabilistic locking in Win95/98/ME.  Hence, the locking scheme
       
   281 ** will support two or more Win95 readers or two or more WinNT readers.
       
   282 ** But a single Win95 reader will lock out all WinNT readers and a single
       
   283 ** WinNT reader will lock out all other Win95 readers.
       
   284 **
       
   285 ** The following #defines specify the range of bytes used for locking.
       
   286 ** SHARED_SIZE is the number of bytes available in the pool from which
       
   287 ** a random byte is selected for a shared lock.  The pool of bytes for
       
   288 ** shared locks begins at SHARED_FIRST. 
       
   289 **
       
   290 ** These #defines are available in sqlite_aux.h so that adaptors for
       
   291 ** connecting SQLite to other operating systems can use the same byte
       
   292 ** ranges for locking.  In particular, the same locking strategy and
       
   293 ** byte ranges are used for Unix.  This leaves open the possiblity of having
       
   294 ** clients on win95, winNT, and unix all talking to the same shared file
       
   295 ** and all locking correctly.  To do so would require that samba (or whatever
       
   296 ** tool is being used for file sharing) implements locks correctly between
       
   297 ** windows and unix.  I'm guessing that isn't likely to happen, but by
       
   298 ** using the same locking range we are at least open to the possibility.
       
   299 **
       
   300 ** Locking in windows is manditory.  For this reason, we cannot store
       
   301 ** actual data in the bytes used for locking.  The pager never allocates
       
   302 ** the pages involved in locking therefore.  SHARED_SIZE is selected so
       
   303 ** that all locks will fit on a single page even at the minimum page size.
       
   304 ** PENDING_BYTE defines the beginning of the locks.  By default PENDING_BYTE
       
   305 ** is set high so that we don't have to allocate an unused page except
       
   306 ** for very large databases.  But one should test the page skipping logic 
       
   307 ** by setting PENDING_BYTE low and running the entire regression suite.
       
   308 **
       
   309 ** Changing the value of PENDING_BYTE results in a subtly incompatible
       
   310 ** file format.  Depending on how it is changed, you might not notice
       
   311 ** the incompatibility right away, even running a full regression test.
       
   312 ** The default location of PENDING_BYTE is the first byte past the
       
   313 ** 1GB boundary.
       
   314 **
       
   315 */
       
   316 #ifndef SQLITE_TEST
       
   317 #define PENDING_BYTE      0x40000000  /* First byte past the 1GB boundary */
       
   318 #else
       
   319 extern unsigned int sqlite3_pending_byte;
       
   320 #define PENDING_BYTE sqlite3_pending_byte
       
   321 #endif
       
   322 
       
   323 #define RESERVED_BYTE     (PENDING_BYTE+1)
       
   324 #define SHARED_FIRST      (PENDING_BYTE+2)
       
   325 #define SHARED_SIZE       510
       
   326 
       
   327 /*
       
   328 ** Prototypes for operating system interface routines.
       
   329 */
       
   330 int sqlite3OsClose(OsFile**);
       
   331 int sqlite3OsOpenDirectory(OsFile*, const char*);
       
   332 int sqlite3OsRead(OsFile*, void*, int amt);
       
   333 int sqlite3OsWrite(OsFile*, const void*, int amt);
       
   334 int sqlite3OsSeek(OsFile*, i64 offset);
       
   335 int sqlite3OsTruncate(OsFile*, i64 size);
       
   336 int sqlite3OsSync(OsFile*, int);
       
   337 void sqlite3OsSetFullSync(OsFile *id, int setting);
       
   338 int sqlite3OsFileHandle(OsFile *id);
       
   339 int sqlite3OsFileSize(OsFile*, i64 *pSize);
       
   340 int sqlite3OsLock(OsFile*, int);
       
   341 int sqlite3OsUnlock(OsFile*, int);
       
   342 int sqlite3OsLockState(OsFile *id);
       
   343 int sqlite3OsCheckReservedLock(OsFile *id);
       
   344 int sqlite3OsOpenReadWrite(const char*, OsFile**, int*);
       
   345 int sqlite3OsOpenExclusive(const char*, OsFile**, int);
       
   346 int sqlite3OsOpenReadOnly(const char*, OsFile**);
       
   347 int sqlite3OsDelete(const char*);
       
   348 int sqlite3OsFileExists(const char*);
       
   349 char *sqlite3OsFullPathname(const char*);
       
   350 int sqlite3OsIsDirWritable(char*);
       
   351 int sqlite3OsSyncDirectory(const char*);
       
   352 int sqlite3OsTempFileName(char*);
       
   353 int sqlite3OsRandomSeed(char*);
       
   354 int sqlite3OsSleep(int ms);
       
   355 int sqlite3OsCurrentTime(double*);
       
   356 void sqlite3OsEnterMutex(void);
       
   357 void sqlite3OsLeaveMutex(void);
       
   358 int sqlite3OsInMutex(int);
       
   359 ThreadData *sqlite3OsThreadSpecificData(int);
       
   360 void *sqlite3OsMalloc(int);
       
   361 void *sqlite3OsRealloc(void *, int);
       
   362 void sqlite3OsFree(void *);
       
   363 int sqlite3OsAllocationSize(void *);
       
   364 
       
   365 /*
       
   366 ** If the SQLITE_ENABLE_REDEF_IO macro is defined, then the OS-layer
       
   367 ** interface routines are not called directly but are invoked using
       
   368 ** pointers to functions.  This allows the implementation of various
       
   369 ** OS-layer interface routines to be modified at run-time.  There are
       
   370 ** obscure but legitimate reasons for wanting to do this.  But for
       
   371 ** most users, a direct call to the underlying interface is preferable
       
   372 ** so the the redefinable I/O interface is turned off by default.
       
   373 */
       
   374 #ifdef SQLITE_ENABLE_REDEF_IO
       
   375 
       
   376 /*
       
   377 ** When redefinable I/O is enabled, a single global instance of the
       
   378 ** following structure holds pointers to the routines that SQLite 
       
   379 ** uses to talk with the underlying operating system.  Modify this
       
   380 ** structure (before using any SQLite API!) to accomodate perculiar
       
   381 ** operating system interfaces or behaviors.
       
   382 */
       
   383 struct sqlite3OsVtbl {
       
   384   int (*xOpenReadWrite)(const char*, OsFile**, int*);
       
   385   int (*xOpenExclusive)(const char*, OsFile**, int);
       
   386   int (*xOpenReadOnly)(const char*, OsFile**);
       
   387 
       
   388   int (*xDelete)(const char*);
       
   389   int (*xFileExists)(const char*);
       
   390   char *(*xFullPathname)(const char*);
       
   391   int (*xIsDirWritable)(char*);
       
   392   int (*xSyncDirectory)(const char*);
       
   393   int (*xTempFileName)(char*);
       
   394 
       
   395   int (*xRandomSeed)(char*);
       
   396   int (*xSleep)(int ms);
       
   397   int (*xCurrentTime)(double*);
       
   398 
       
   399   void (*xEnterMutex)(void);
       
   400   void (*xLeaveMutex)(void);
       
   401   int (*xInMutex)(int);
       
   402   ThreadData *(*xThreadSpecificData)(int);
       
   403 
       
   404   void *(*xMalloc)(int);
       
   405   void *(*xRealloc)(void *, int);
       
   406   void (*xFree)(void *);
       
   407   int (*xAllocationSize)(void *);
       
   408 };
       
   409 
       
   410 /* Macro used to comment out routines that do not exists when there is
       
   411 ** no disk I/O 
       
   412 */
       
   413 #ifdef SQLITE_OMIT_DISKIO
       
   414 # define IF_DISKIO(X)  0
       
   415 #else
       
   416 # define IF_DISKIO(X)  X
       
   417 #endif
       
   418 
       
   419 #ifdef _SQLITE_OS_C_
       
   420   /*
       
   421   ** The os.c file implements the global virtual function table.
       
   422   */
       
   423   struct sqlite3OsVtbl sqlite3Os = {
       
   424     IF_DISKIO( sqlite3OsOpenReadWrite ),
       
   425     IF_DISKIO( sqlite3OsOpenExclusive ),
       
   426     IF_DISKIO( sqlite3OsOpenReadOnly ),
       
   427     IF_DISKIO( sqlite3OsDelete ),
       
   428     IF_DISKIO( sqlite3OsFileExists ),
       
   429     IF_DISKIO( sqlite3OsFullPathname ),
       
   430     IF_DISKIO( sqlite3OsIsDirWritable ),
       
   431     IF_DISKIO( sqlite3OsSyncDirectory ),
       
   432     IF_DISKIO( sqlite3OsTempFileName ),
       
   433     sqlite3OsRandomSeed,
       
   434     sqlite3OsSleep,
       
   435     sqlite3OsCurrentTime,
       
   436     sqlite3OsEnterMutex,
       
   437     sqlite3OsLeaveMutex,
       
   438     sqlite3OsInMutex,
       
   439     sqlite3OsThreadSpecificData,
       
   440     sqlite3OsMalloc,
       
   441     sqlite3OsRealloc,
       
   442     sqlite3OsFree,
       
   443     sqlite3OsAllocationSize
       
   444   };
       
   445 #else
       
   446   /*
       
   447   ** Files other than os.c just reference the global virtual function table. 
       
   448   */
       
   449   extern struct sqlite3OsVtbl sqlite3Os;
       
   450 #endif /* _SQLITE_OS_C_ */
       
   451 
       
   452 
       
   453 /* This additional API routine is available with redefinable I/O */
       
   454 struct sqlite3OsVtbl *sqlite3_os_switch(void);
       
   455 
       
   456 
       
   457 /*
       
   458 ** Redefine the OS interface to go through the virtual function table
       
   459 ** rather than calling routines directly.
       
   460 */
       
   461 #undef sqlite3OsOpenReadWrite
       
   462 #undef sqlite3OsOpenExclusive
       
   463 #undef sqlite3OsOpenReadOnly
       
   464 #undef sqlite3OsDelete
       
   465 #undef sqlite3OsFileExists
       
   466 #undef sqlite3OsFullPathname
       
   467 #undef sqlite3OsIsDirWritable
       
   468 #undef sqlite3OsSyncDirectory
       
   469 #undef sqlite3OsTempFileName
       
   470 #undef sqlite3OsRandomSeed
       
   471 #undef sqlite3OsSleep
       
   472 #undef sqlite3OsCurrentTime
       
   473 #undef sqlite3OsEnterMutex
       
   474 #undef sqlite3OsLeaveMutex
       
   475 #undef sqlite3OsInMutex
       
   476 #undef sqlite3OsThreadSpecificData
       
   477 #undef sqlite3OsMalloc
       
   478 #undef sqlite3OsRealloc
       
   479 #undef sqlite3OsFree
       
   480 #undef sqlite3OsAllocationSize
       
   481 #define sqlite3OsOpenReadWrite      sqlite3Os.xOpenReadWrite
       
   482 #define sqlite3OsOpenExclusive      sqlite3Os.xOpenExclusive
       
   483 #define sqlite3OsOpenReadOnly       sqlite3Os.xOpenReadOnly
       
   484 #define sqlite3OsDelete             sqlite3Os.xDelete
       
   485 #define sqlite3OsFileExists         sqlite3Os.xFileExists
       
   486 #define sqlite3OsFullPathname       sqlite3Os.xFullPathname
       
   487 #define sqlite3OsIsDirWritable      sqlite3Os.xIsDirWritable
       
   488 #define sqlite3OsSyncDirectory      sqlite3Os.xSyncDirectory
       
   489 #define sqlite3OsTempFileName       sqlite3Os.xTempFileName
       
   490 #define sqlite3OsRandomSeed         sqlite3Os.xRandomSeed
       
   491 #define sqlite3OsSleep              sqlite3Os.xSleep
       
   492 #define sqlite3OsCurrentTime        sqlite3Os.xCurrentTime
       
   493 #define sqlite3OsEnterMutex         sqlite3Os.xEnterMutex
       
   494 #define sqlite3OsLeaveMutex         sqlite3Os.xLeaveMutex
       
   495 #define sqlite3OsInMutex            sqlite3Os.xInMutex
       
   496 #define sqlite3OsThreadSpecificData sqlite3Os.xThreadSpecificData
       
   497 #define sqlite3OsMalloc             sqlite3Os.xMalloc
       
   498 #define sqlite3OsRealloc            sqlite3Os.xRealloc
       
   499 #define sqlite3OsFree               sqlite3Os.xFree
       
   500 #define sqlite3OsAllocationSize     sqlite3Os.xAllocationSize
       
   501 
       
   502 #endif /* SQLITE_ENABLE_REDEF_IO */
       
   503 
       
   504 #endif /* _SQLITE_OS_H_ */