src/os.c

   1 /*
   2 ** 2005 November 29
   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 file contains OS interface code that is common to all
  14 ** architectures.
  15 */
  16 #include "sqliteInt.h"
  17
  18 /*
  19 ** If we compile with the SQLITE_TEST macro set, then the following block
  20 ** of code will give us the ability to simulate a disk I/O error.  This
  21 ** is used for testing the I/O recovery logic.
  22 */
  23 #if defined(SQLITE_TEST)
  24 int sqlite3_io_error_hit = 0;            /* Total number of I/O Errors */
  25 int sqlite3_io_error_hardhit = 0;        /* Number of non-benign errors */
  26 int sqlite3_io_error_pending = 0;        /* Count down to first I/O error */
  27 int sqlite3_io_error_persist = 0;        /* True if I/O errors persist */
  28 int sqlite3_io_error_benign = 0;         /* True if errors are benign */
  29 int sqlite3_diskfull_pending = 0;
  30 int sqlite3_diskfull = 0;
  31 #endif /* defined(SQLITE_TEST) */
  32
  33 /*
  34 ** When testing, also keep a count of the number of open files.
  35 */
  36 #if defined(SQLITE_TEST)
  37 int sqlite3_open_file_count = 0;
  38 #endif /* defined(SQLITE_TEST) */
  39
  40 /*
  41 ** The default SQLite sqlite3_vfs implementations do not allocate
  42 ** memory (actually, os_unix.c allocates a small amount of memory
  43 ** from within OsOpen()), but some third-party implementations may.
  44 ** So we test the effects of a malloc() failing and the sqlite3OsXXX()
  45 ** function returning SQLITE_IOERR_NOMEM using the DO_OS_MALLOC_TEST macro.
  46 **
  47 ** The following functions are instrumented for malloc() failure
  48 ** testing:
  49 **
  50 **     sqlite3OsRead()
  51 **     sqlite3OsWrite()
  52 **     sqlite3OsSync()
  53 **     sqlite3OsFileSize()
  54 **     sqlite3OsLock()
  55 **     sqlite3OsCheckReservedLock()
  56 **     sqlite3OsFileControl()
  57 **     sqlite3OsShmMap()
  58 **     sqlite3OsOpen()
  59 **     sqlite3OsDelete()
  60 **     sqlite3OsAccess()
  61 **     sqlite3OsFullPathname()
  62 **
  63 */
  64 #if defined(SQLITE_TEST)
  65 int sqlite3_memdebug_vfs_oom_test = 1;
  66   #define DO_OS_MALLOC_TEST(x)                                       \
  67   if (sqlite3_memdebug_vfs_oom_test && (!x || !sqlite3JournalIsInMemory(x))) { \
  68     void *pTstAlloc = sqlite3Malloc(10);                             \
  69     if (!pTstAlloc) return SQLITE_IOERR_NOMEM_BKPT;                  \
  70     sqlite3_free(pTstAlloc);                                         \
  71   }
  72 #else
  73   #define DO_OS_MALLOC_TEST(x)
  74 #endif
  75
  76 /*
  77 ** The following routines are convenience wrappers around methods
  78 ** of the sqlite3_file object.  This is mostly just syntactic sugar. All
  79 ** of this would be completely automatic if SQLite were coded using
  80 ** C++ instead of plain old C.
  81 */
  82 void sqlite3OsClose(sqlite3_file *pId){
  83   if( pId->pMethods ){
  84     pId->pMethods->xClose(pId);
  85     pId->pMethods = 0;
  86   }
  87 }
  88 int sqlite3OsRead(sqlite3_file *id, void *pBuf, int amt, i64 offset){
  89   DO_OS_MALLOC_TEST(id);
  90   return id->pMethods->xRead(id, pBuf, amt, offset);
  91 }
  92 int sqlite3OsWrite(sqlite3_file *id, const void *pBuf, int amt, i64 offset){
  93   DO_OS_MALLOC_TEST(id);
  94   return id->pMethods->xWrite(id, pBuf, amt, offset);
  95 }
  96 int sqlite3OsTruncate(sqlite3_file *id, i64 size){
  97   return id->pMethods->xTruncate(id, size);
  98 }
  99 int sqlite3OsSync(sqlite3_file *id, int flags){
 100   DO_OS_MALLOC_TEST(id);
 101   return flags ? id->pMethods->xSync(id, flags) : SQLITE_OK;
 102 }
 103 int sqlite3OsFileSize(sqlite3_file *id, i64 *pSize){
 104   DO_OS_MALLOC_TEST(id);
 105   return id->pMethods->xFileSize(id, pSize);
 106 }
 107 int sqlite3OsLock(sqlite3_file *id, int lockType){
 108   DO_OS_MALLOC_TEST(id);
 109   return id->pMethods->xLock(id, lockType);
 110 }
 111 int sqlite3OsUnlock(sqlite3_file *id, int lockType){
 112   return id->pMethods->xUnlock(id, lockType);
 113 }
 114 int sqlite3OsCheckReservedLock(sqlite3_file *id, int *pResOut){
 115   DO_OS_MALLOC_TEST(id);
 116   return id->pMethods->xCheckReservedLock(id, pResOut);
 117 }
 118
 119 /*
 120 ** Use sqlite3OsFileControl() when we are doing something that might fail
 121 ** and we need to know about the failures.  Use sqlite3OsFileControlHint()
 122 ** when simply tossing information over the wall to the VFS and we do not
 123 ** really care if the VFS receives and understands the information since it
 124 ** is only a hint and can be safely ignored.  The sqlite3OsFileControlHint()
 125 ** routine has no return value since the return value would be meaningless.
 126 */
 127 int sqlite3OsFileControl(sqlite3_file *id, int op, void *pArg){
 128   if( id->pMethods==0 ) return SQLITE_NOTFOUND;
 129 #ifdef SQLITE_TEST
 130   if( op!=SQLITE_FCNTL_COMMIT_PHASETWO
 131    && op!=SQLITE_FCNTL_LOCK_TIMEOUT
 132   ){
 133     /* Faults are not injected into COMMIT_PHASETWO because, assuming SQLite
 134     ** is using a regular VFS, it is called after the corresponding
 135     ** transaction has been committed. Injecting a fault at this point
 136     ** confuses the test scripts - the COMMIT comand returns SQLITE_NOMEM
 137     ** but the transaction is committed anyway.
 138     **
 139     ** The core must call OsFileControl() though, not OsFileControlHint(),
 140     ** as if a custom VFS (e.g. zipvfs) returns an error here, it probably
 141     ** means the commit really has failed and an error should be returned
 142     ** to the user.  */
 143     DO_OS_MALLOC_TEST(id);
 144   }
 145 #endif
 146   return id->pMethods->xFileControl(id, op, pArg);
 147 }
 148 void sqlite3OsFileControlHint(sqlite3_file *id, int op, void *pArg){
 149   if( id->pMethods ) (void)id->pMethods->xFileControl(id, op, pArg);
 150 }
 151
 152 int sqlite3OsSectorSize(sqlite3_file *id){
 153   int (*xSectorSize)(sqlite3_file*) = id->pMethods->xSectorSize;
 154   return (xSectorSize ? xSectorSize(id) : SQLITE_DEFAULT_SECTOR_SIZE);
 155 }
 156 int sqlite3OsDeviceCharacteristics(sqlite3_file *id){
 157   return id->pMethods->xDeviceCharacteristics(id);
 158 }
 159 #ifndef SQLITE_OMIT_WAL
 160 int sqlite3OsShmLock(sqlite3_file *id, int offset, int n, int flags){
 161   return id->pMethods->xShmLock(id, offset, n, flags);
 162 }
 163 void sqlite3OsShmBarrier(sqlite3_file *id){
 164   id->pMethods->xShmBarrier(id);
 165 }
 166 int sqlite3OsShmUnmap(sqlite3_file *id, int deleteFlag){
 167   return id->pMethods->xShmUnmap(id, deleteFlag);
 168 }
 169 int sqlite3OsShmMap(
 170   sqlite3_file *id,               /* Database file handle */
 171   int iPage,
 172   int pgsz,
 173   int bExtend,                    /* True to extend file if necessary */
 174   void volatile **pp              /* OUT: Pointer to mapping */
 175 ){
 176   DO_OS_MALLOC_TEST(id);
 177   return id->pMethods->xShmMap(id, iPage, pgsz, bExtend, pp);
 178 }
 179 #endif /* SQLITE_OMIT_WAL */
 180
 181 #if SQLITE_MAX_MMAP_SIZE>0
 182 /* The real implementation of xFetch and xUnfetch */
 183 int sqlite3OsFetch(sqlite3_file *id, i64 iOff, int iAmt, void **pp){
 184   DO_OS_MALLOC_TEST(id);
 185   return id->pMethods->xFetch(id, iOff, iAmt, pp);
 186 }
 187 int sqlite3OsUnfetch(sqlite3_file *id, i64 iOff, void *p){
 188   return id->pMethods->xUnfetch(id, iOff, p);
 189 }
 190 #else
 191 /* No-op stubs to use when memory-mapped I/O is disabled */
 192 int sqlite3OsFetch(sqlite3_file *id, i64 iOff, int iAmt, void **pp){
 193   *pp = 0;
 194   return SQLITE_OK;
 195 }
 196 int sqlite3OsUnfetch(sqlite3_file *id, i64 iOff, void *p){
 197   return SQLITE_OK;
 198 }
 199 #endif
 200
 201 /*
 202 ** The next group of routines are convenience wrappers around the
 203 ** VFS methods.
 204 */
 205 int sqlite3OsOpen(
 206   sqlite3_vfs *pVfs,
 207   const char *zPath,
 208   sqlite3_file *pFile,
 209   int flags,
 210   int *pFlagsOut
 211 ){
 212   int rc;
 213   DO_OS_MALLOC_TEST(0);
 214   /* 0x87f7f is a mask of SQLITE_OPEN_ flags that are valid to be passed
 215   ** down into the VFS layer.  Some SQLITE_OPEN_ flags (for example,
 216   ** SQLITE_OPEN_FULLMUTEX or SQLITE_OPEN_SHAREDCACHE) are blocked before
 217   ** reaching the VFS. */
 218   rc = pVfs->xOpen(pVfs, zPath, pFile, flags & 0x1087f7f, pFlagsOut);
 219   assert( rc==SQLITE_OK || pFile->pMethods==0 );
 220   return rc;
 221 }
 222 int sqlite3OsDelete(sqlite3_vfs *pVfs, const char *zPath, int dirSync){
 223   DO_OS_MALLOC_TEST(0);
 224   assert( dirSync==0 || dirSync==1 );
 225   return pVfs->xDelete(pVfs, zPath, dirSync);
 226 }
 227 int sqlite3OsAccess(
 228   sqlite3_vfs *pVfs,
 229   const char *zPath,
 230   int flags,
 231   int *pResOut
 232 ){
 233   DO_OS_MALLOC_TEST(0);
 234   return pVfs->xAccess(pVfs, zPath, flags, pResOut);
 235 }
 236 int sqlite3OsFullPathname(
 237   sqlite3_vfs *pVfs,
 238   const char *zPath,
 239   int nPathOut,
 240   char *zPathOut
 241 ){
 242   DO_OS_MALLOC_TEST(0);
 243   zPathOut[0] = 0;
 244   return pVfs->xFullPathname(pVfs, zPath, nPathOut, zPathOut);
 245 }
 246 #ifndef SQLITE_OMIT_LOAD_EXTENSION
 247 void *sqlite3OsDlOpen(sqlite3_vfs *pVfs, const char *zPath){
 248   return pVfs->xDlOpen(pVfs, zPath);
 249 }
 250 void sqlite3OsDlError(sqlite3_vfs *pVfs, int nByte, char *zBufOut){
 251   pVfs->xDlError(pVfs, nByte, zBufOut);
 252 }
 253 void (*sqlite3OsDlSym(sqlite3_vfs *pVfs, void *pHdle, const char *zSym))(void){
 254   return pVfs->xDlSym(pVfs, pHdle, zSym);
 255 }
 256 void sqlite3OsDlClose(sqlite3_vfs *pVfs, void *pHandle){
 257   pVfs->xDlClose(pVfs, pHandle);
 258 }
 259 #endif /* SQLITE_OMIT_LOAD_EXTENSION */
 260 int sqlite3OsRandomness(sqlite3_vfs *pVfs, int nByte, char *zBufOut){
 261   if( sqlite3Config.iPrngSeed ){
 262     memset(zBufOut, 0, nByte);
 263     if( ALWAYS(nByte>(signed)sizeof(unsigned)) ) nByte = sizeof(unsigned int);
 264     memcpy(zBufOut, &sqlite3Config.iPrngSeed, nByte);
 265     return SQLITE_OK;
 266   }else{
 267     return pVfs->xRandomness(pVfs, nByte, zBufOut);
 268   }
 269
 270 }
 271 int sqlite3OsSleep(sqlite3_vfs *pVfs, int nMicro){
 272   return pVfs->xSleep(pVfs, nMicro);
 273 }
 274 int sqlite3OsGetLastError(sqlite3_vfs *pVfs){
 275   return pVfs->xGetLastError ? pVfs->xGetLastError(pVfs, 0, 0) : 0;
 276 }
 277 int sqlite3OsCurrentTimeInt64(sqlite3_vfs *pVfs, sqlite3_int64 *pTimeOut){
 278   int rc;
 279   /* IMPLEMENTATION-OF: R-49045-42493 SQLite will use the xCurrentTimeInt64()
 280   ** method to get the current date and time if that method is available
 281   ** (if iVersion is 2 or greater and the function pointer is not NULL) and
 282   ** will fall back to xCurrentTime() if xCurrentTimeInt64() is
 283   ** unavailable.
 284   */
 285   if( pVfs->iVersion>=2 && pVfs->xCurrentTimeInt64 ){
 286     rc = pVfs->xCurrentTimeInt64(pVfs, pTimeOut);
 287   }else{
 288     double r;
 289     rc = pVfs->xCurrentTime(pVfs, &r);
 290     *pTimeOut = (sqlite3_int64)(r*86400000.0);
 291   }
 292   return rc;
 293 }
 294
 295 int sqlite3OsOpenMalloc(
 296   sqlite3_vfs *pVfs,
 297   const char *zFile,
 298   sqlite3_file **ppFile,
 299   int flags,
 300   int *pOutFlags
 301 ){
 302   int rc;
 303   sqlite3_file *pFile;
 304   pFile = (sqlite3_file *)sqlite3MallocZero(pVfs->szOsFile);
 305   if( pFile ){
 306     rc = sqlite3OsOpen(pVfs, zFile, pFile, flags, pOutFlags);
 307     if( rc!=SQLITE_OK ){
 308       sqlite3_free(pFile);
 309     }else{
 310       *ppFile = pFile;
 311     }
 312   }else{
 313     rc = SQLITE_NOMEM_BKPT;
 314   }
 315   return rc;
 316 }
 317 void sqlite3OsCloseFree(sqlite3_file *pFile){
 318   assert( pFile );
 319   sqlite3OsClose(pFile);
 320   sqlite3_free(pFile);
 321 }
 322
 323 /*
 324 ** This function is a wrapper around the OS specific implementation of
 325 ** sqlite3_os_init(). The purpose of the wrapper is to provide the
 326 ** ability to simulate a malloc failure, so that the handling of an
 327 ** error in sqlite3_os_init() by the upper layers can be tested.
 328 */
 329 int sqlite3OsInit(void){
 330   void *p = sqlite3_malloc(10);
 331   if( p==0 ) return SQLITE_NOMEM_BKPT;
 332   sqlite3_free(p);
 333   return sqlite3_os_init();
 334 }
 335
 336 /*
 337 ** The list of all registered VFS implementations.
 338 */
 339 static sqlite3_vfs * SQLITE_WSD vfsList = 0;
 340 #define vfsList GLOBAL(sqlite3_vfs *, vfsList)
 341
 342 /*
 343 ** Locate a VFS by name.  If no name is given, simply return the
 344 ** first VFS on the list.
 345 */
 346 sqlite3_vfs *sqlite3_vfs_find(const char *zVfs){
 347   sqlite3_vfs *pVfs = 0;
 348 #if SQLITE_THREADSAFE
 349   sqlite3_mutex *mutex;
 350 #endif
 351 #ifndef SQLITE_OMIT_AUTOINIT
 352   int rc = sqlite3_initialize();
 353   if( rc ) return 0;
 354 #endif
 355 #if SQLITE_THREADSAFE
 356   mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MAIN);
 357 #endif
 358   sqlite3_mutex_enter(mutex);
 359   for(pVfs = vfsList; pVfs; pVfs=pVfs->pNext){
 360     if( zVfs==0 ) break;
 361     if( strcmp(zVfs, pVfs->zName)==0 ) break;
 362   }
 363   sqlite3_mutex_leave(mutex);
 364   return pVfs;
 365 }
 366
 367 /*
 368 ** Unlink a VFS from the linked list
 369 */
 370 static void vfsUnlink(sqlite3_vfs *pVfs){
 371   assert( sqlite3_mutex_held(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MAIN)) );
 372   if( pVfs==0 ){
 373     /* No-op */
 374   }else if( vfsList==pVfs ){
 375     vfsList = pVfs->pNext;
 376   }else if( vfsList ){
 377     sqlite3_vfs *p = vfsList;
 378     while( p->pNext && p->pNext!=pVfs ){
 379       p = p->pNext;
 380     }
 381     if( p->pNext==pVfs ){
 382       p->pNext = pVfs->pNext;
 383     }
 384   }
 385 }
 386
 387 /*
 388 ** Register a VFS with the system.  It is harmless to register the same
 389 ** VFS multiple times.  The new VFS becomes the default if makeDflt is
 390 ** true.
 391 */
 392 int sqlite3_vfs_register(sqlite3_vfs *pVfs, int makeDflt){
 393   MUTEX_LOGIC(sqlite3_mutex *mutex;)
 394 #ifndef SQLITE_OMIT_AUTOINIT
 395   int rc = sqlite3_initialize();
 396   if( rc ) return rc;
 397 #endif
 398 #ifdef SQLITE_ENABLE_API_ARMOR
 399   if( pVfs==0 ) return SQLITE_MISUSE_BKPT;
 400 #endif
 401
 402   MUTEX_LOGIC( mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MAIN); )
 403   sqlite3_mutex_enter(mutex);
 404   vfsUnlink(pVfs);
 405   if( makeDflt || vfsList==0 ){
 406     pVfs->pNext = vfsList;
 407     vfsList = pVfs;
 408   }else{
 409     pVfs->pNext = vfsList->pNext;
 410     vfsList->pNext = pVfs;
 411   }
 412   assert(vfsList);
 413   sqlite3_mutex_leave(mutex);
 414   return SQLITE_OK;
 415 }
 416
 417 /*
 418 ** Unregister a VFS so that it is no longer accessible.
 419 */
 420 int sqlite3_vfs_unregister(sqlite3_vfs *pVfs){
 421   MUTEX_LOGIC(sqlite3_mutex *mutex;)
 422 #ifndef SQLITE_OMIT_AUTOINIT
 423   int rc = sqlite3_initialize();
 424   if( rc ) return rc;
 425 #endif
 426   MUTEX_LOGIC( mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MAIN); )
 427   sqlite3_mutex_enter(mutex);
 428   vfsUnlink(pVfs);
 429   sqlite3_mutex_leave(mutex);
 430   return SQLITE_OK;
 431 }