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    && op!=SQLITE_FCNTL_CKPT_DONE
 133    && op!=SQLITE_FCNTL_CKPT_START
 134   ){
 135     /* Faults are not injected into COMMIT_PHASETWO because, assuming SQLite
 136     ** is using a regular VFS, it is called after the corresponding
 137     ** transaction has been committed. Injecting a fault at this point
 138     ** confuses the test scripts - the COMMIT comand returns SQLITE_NOMEM
 139     ** but the transaction is committed anyway.
 140     **
 141     ** The core must call OsFileControl() though, not OsFileControlHint(),
 142     ** as if a custom VFS (e.g. zipvfs) returns an error here, it probably
 143     ** means the commit really has failed and an error should be returned
 144     ** to the user.
 145     **
 146     ** The CKPT_DONE and CKPT_START file-controls are write-only signals
 147     ** to the cksumvfs.  Their return code is meaningless and is ignored
 148     ** by the SQLite core, so there is no point in simulating OOMs for them.
 149     */
 150     DO_OS_MALLOC_TEST(id);
 151   }
 152 #endif
 153   return id->pMethods->xFileControl(id, op, pArg);
 154 }
 155 void sqlite3OsFileControlHint(sqlite3_file *id, int op, void *pArg){
 156   if( id->pMethods ) (void)id->pMethods->xFileControl(id, op, pArg);
 157 }
 158
 159 int sqlite3OsSectorSize(sqlite3_file *id){
 160   int (*xSectorSize)(sqlite3_file*) = id->pMethods->xSectorSize;
 161   return (xSectorSize ? xSectorSize(id) : SQLITE_DEFAULT_SECTOR_SIZE);
 162 }
 163 int sqlite3OsDeviceCharacteristics(sqlite3_file *id){
 164   if( NEVER(id->pMethods==0) ) return 0;
 165   return id->pMethods->xDeviceCharacteristics(id);
 166 }
 167 #ifndef SQLITE_OMIT_WAL
 168 int sqlite3OsShmLock(sqlite3_file *id, int offset, int n, int flags){
 169   return id->pMethods->xShmLock(id, offset, n, flags);
 170 }
 171 void sqlite3OsShmBarrier(sqlite3_file *id){
 172   id->pMethods->xShmBarrier(id);
 173 }
 174 int sqlite3OsShmUnmap(sqlite3_file *id, int deleteFlag){
 175   return id->pMethods->xShmUnmap(id, deleteFlag);
 176 }
 177 int sqlite3OsShmMap(
 178   sqlite3_file *id,               /* Database file handle */
 179   int iPage,
 180   int pgsz,
 181   int bExtend,                    /* True to extend file if necessary */
 182   void volatile **pp              /* OUT: Pointer to mapping */
 183 ){
 184   DO_OS_MALLOC_TEST(id);
 185   return id->pMethods->xShmMap(id, iPage, pgsz, bExtend, pp);
 186 }
 187 #endif /* SQLITE_OMIT_WAL */
 188
 189 #if SQLITE_MAX_MMAP_SIZE>0
 190 /* The real implementation of xFetch and xUnfetch */
 191 int sqlite3OsFetch(sqlite3_file *id, i64 iOff, int iAmt, void **pp){
 192   DO_OS_MALLOC_TEST(id);
 193   return id->pMethods->xFetch(id, iOff, iAmt, pp);
 194 }
 195 int sqlite3OsUnfetch(sqlite3_file *id, i64 iOff, void *p){
 196   return id->pMethods->xUnfetch(id, iOff, p);
 197 }
 198 #else
 199 /* No-op stubs to use when memory-mapped I/O is disabled */
 200 int sqlite3OsFetch(sqlite3_file *id, i64 iOff, int iAmt, void **pp){
 201   *pp = 0;
 202   return SQLITE_OK;
 203 }
 204 int sqlite3OsUnfetch(sqlite3_file *id, i64 iOff, void *p){
 205   return SQLITE_OK;
 206 }
 207 #endif
 208
 209 /*
 210 ** The next group of routines are convenience wrappers around the
 211 ** VFS methods.
 212 */
 213 int sqlite3OsOpen(
 214   sqlite3_vfs *pVfs,
 215   const char *zPath,
 216   sqlite3_file *pFile,
 217   int flags,
 218   int *pFlagsOut
 219 ){
 220   int rc;
 221   DO_OS_MALLOC_TEST(0);
 222   /* 0x87f7f is a mask of SQLITE_OPEN_ flags that are valid to be passed
 223   ** down into the VFS layer.  Some SQLITE_OPEN_ flags (for example,
 224   ** SQLITE_OPEN_FULLMUTEX or SQLITE_OPEN_SHAREDCACHE) are blocked before
 225   ** reaching the VFS. */
 226   rc = pVfs->xOpen(pVfs, zPath, pFile, flags & 0x1087f7f, pFlagsOut);
 227   assert( rc==SQLITE_OK || pFile->pMethods==0 );
 228   return rc;
 229 }
 230 int sqlite3OsDelete(sqlite3_vfs *pVfs, const char *zPath, int dirSync){
 231   DO_OS_MALLOC_TEST(0);
 232   assert( dirSync==0 || dirSync==1 );
 233   return pVfs->xDelete!=0 ? pVfs->xDelete(pVfs, zPath, dirSync) : SQLITE_OK;
 234 }
 235 int sqlite3OsAccess(
 236   sqlite3_vfs *pVfs,
 237   const char *zPath,
 238   int flags,
 239   int *pResOut
 240 ){
 241   DO_OS_MALLOC_TEST(0);
 242   return pVfs->xAccess(pVfs, zPath, flags, pResOut);
 243 }
 244 int sqlite3OsFullPathname(
 245   sqlite3_vfs *pVfs,
 246   const char *zPath,
 247   int nPathOut,
 248   char *zPathOut
 249 ){
 250   DO_OS_MALLOC_TEST(0);
 251   zPathOut[0] = 0;
 252   return pVfs->xFullPathname(pVfs, zPath, nPathOut, zPathOut);
 253 }
 254 #ifndef SQLITE_OMIT_LOAD_EXTENSION
 255 void *sqlite3OsDlOpen(sqlite3_vfs *pVfs, const char *zPath){
 256   assert( zPath!=0 );
 257   assert( strlen(zPath)<=SQLITE_MAX_PATHLEN );  /* tag-20210611-1 */
 258   return pVfs->xDlOpen(pVfs, zPath);
 259 }
 260 void sqlite3OsDlError(sqlite3_vfs *pVfs, int nByte, char *zBufOut){
 261   pVfs->xDlError(pVfs, nByte, zBufOut);
 262 }
 263 void (*sqlite3OsDlSym(sqlite3_vfs *pVfs, void *pHdle, const char *zSym))(void){
 264   return pVfs->xDlSym(pVfs, pHdle, zSym);
 265 }
 266 void sqlite3OsDlClose(sqlite3_vfs *pVfs, void *pHandle){
 267   pVfs->xDlClose(pVfs, pHandle);
 268 }
 269 #endif /* SQLITE_OMIT_LOAD_EXTENSION */
 270 int sqlite3OsRandomness(sqlite3_vfs *pVfs, int nByte, char *zBufOut){
 271   if( sqlite3Config.iPrngSeed ){
 272     memset(zBufOut, 0, nByte);
 273     if( ALWAYS(nByte>(signed)sizeof(unsigned)) ) nByte = sizeof(unsigned int);
 274     memcpy(zBufOut, &sqlite3Config.iPrngSeed, nByte);
 275     return SQLITE_OK;
 276   }else{
 277     return pVfs->xRandomness(pVfs, nByte, zBufOut);
 278   }
 279
 280 }
 281 int sqlite3OsSleep(sqlite3_vfs *pVfs, int nMicro){
 282   return pVfs->xSleep(pVfs, nMicro);
 283 }
 284 int sqlite3OsGetLastError(sqlite3_vfs *pVfs){
 285   return pVfs->xGetLastError ? pVfs->xGetLastError(pVfs, 0, 0) : 0;
 286 }
 287 int sqlite3OsCurrentTimeInt64(sqlite3_vfs *pVfs, sqlite3_int64 *pTimeOut){
 288   int rc;
 289   /* IMPLEMENTATION-OF: R-49045-42493 SQLite will use the xCurrentTimeInt64()
 290   ** method to get the current date and time if that method is available
 291   ** (if iVersion is 2 or greater and the function pointer is not NULL) and
 292   ** will fall back to xCurrentTime() if xCurrentTimeInt64() is
 293   ** unavailable.
 294   */
 295   if( pVfs->iVersion>=2 && pVfs->xCurrentTimeInt64 ){
 296     rc = pVfs->xCurrentTimeInt64(pVfs, pTimeOut);
 297   }else{
 298     double r;
 299     rc = pVfs->xCurrentTime(pVfs, &r);
 300     *pTimeOut = (sqlite3_int64)(r*86400000.0);
 301   }
 302   return rc;
 303 }
 304
 305 int sqlite3OsOpenMalloc(
 306   sqlite3_vfs *pVfs,
 307   const char *zFile,
 308   sqlite3_file **ppFile,
 309   int flags,
 310   int *pOutFlags
 311 ){
 312   int rc;
 313   sqlite3_file *pFile;
 314   pFile = (sqlite3_file *)sqlite3MallocZero(pVfs->szOsFile);
 315   if( pFile ){
 316     rc = sqlite3OsOpen(pVfs, zFile, pFile, flags, pOutFlags);
 317     if( rc!=SQLITE_OK ){
 318       sqlite3_free(pFile);
 319       *ppFile = 0;
 320     }else{
 321       *ppFile = pFile;
 322     }
 323   }else{
 324     *ppFile = 0;
 325     rc = SQLITE_NOMEM_BKPT;
 326   }
 327   assert( *ppFile!=0 || rc!=SQLITE_OK );
 328   return rc;
 329 }
 330 void sqlite3OsCloseFree(sqlite3_file *pFile){
 331   assert( pFile );
 332   sqlite3OsClose(pFile);
 333   sqlite3_free(pFile);
 334 }
 335
 336 /*
 337 ** This function is a wrapper around the OS specific implementation of
 338 ** sqlite3_os_init(). The purpose of the wrapper is to provide the
 339 ** ability to simulate a malloc failure, so that the handling of an
 340 ** error in sqlite3_os_init() by the upper layers can be tested.
 341 */
 342 int sqlite3OsInit(void){
 343   void *p = sqlite3_malloc(10);
 344   if( p==0 ) return SQLITE_NOMEM_BKPT;
 345   sqlite3_free(p);
 346   return sqlite3_os_init();
 347 }
 348
 349 /*
 350 ** The list of all registered VFS implementations.
 351 */
 352 static sqlite3_vfs * SQLITE_WSD vfsList = 0;
 353 #define vfsList GLOBAL(sqlite3_vfs *, vfsList)
 354
 355 /*
 356 ** Locate a VFS by name.  If no name is given, simply return the
 357 ** first VFS on the list.
 358 */
 359 sqlite3_vfs *sqlite3_vfs_find(const char *zVfs){
 360   sqlite3_vfs *pVfs = 0;
 361 #if SQLITE_THREADSAFE
 362   sqlite3_mutex *mutex;
 363 #endif
 364 #ifndef SQLITE_OMIT_AUTOINIT
 365   int rc = sqlite3_initialize();
 366   if( rc ) return 0;
 367 #endif
 368 #if SQLITE_THREADSAFE
 369   mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MAIN);
 370 #endif
 371   sqlite3_mutex_enter(mutex);
 372   for(pVfs = vfsList; pVfs; pVfs=pVfs->pNext){
 373     if( zVfs==0 ) break;
 374     if( strcmp(zVfs, pVfs->zName)==0 ) break;
 375   }
 376   sqlite3_mutex_leave(mutex);
 377   return pVfs;
 378 }
 379
 380 /*
 381 ** Unlink a VFS from the linked list
 382 */
 383 static void vfsUnlink(sqlite3_vfs *pVfs){
 384   assert( sqlite3_mutex_held(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MAIN)) );
 385   if( pVfs==0 ){
 386     /* No-op */
 387   }else if( vfsList==pVfs ){
 388     vfsList = pVfs->pNext;
 389   }else if( vfsList ){
 390     sqlite3_vfs *p = vfsList;
 391     while( p->pNext && p->pNext!=pVfs ){
 392       p = p->pNext;
 393     }
 394     if( p->pNext==pVfs ){
 395       p->pNext = pVfs->pNext;
 396     }
 397   }
 398 }
 399
 400 /*
 401 ** Register a VFS with the system.  It is harmless to register the same
 402 ** VFS multiple times.  The new VFS becomes the default if makeDflt is
 403 ** true.
 404 */
 405 int sqlite3_vfs_register(sqlite3_vfs *pVfs, int makeDflt){
 406   MUTEX_LOGIC(sqlite3_mutex *mutex;)
 407 #ifndef SQLITE_OMIT_AUTOINIT
 408   int rc = sqlite3_initialize();
 409   if( rc ) return rc;
 410 #endif
 411 #ifdef SQLITE_ENABLE_API_ARMOR
 412   if( pVfs==0 ) return SQLITE_MISUSE_BKPT;
 413 #endif
 414
 415   MUTEX_LOGIC( mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MAIN); )
 416   sqlite3_mutex_enter(mutex);
 417   vfsUnlink(pVfs);
 418   if( makeDflt || vfsList==0 ){
 419     pVfs->pNext = vfsList;
 420     vfsList = pVfs;
 421   }else{
 422     pVfs->pNext = vfsList->pNext;
 423     vfsList->pNext = pVfs;
 424   }
 425   assert(vfsList);
 426   sqlite3_mutex_leave(mutex);
 427   return SQLITE_OK;
 428 }
 429
 430 /*
 431 ** Unregister a VFS so that it is no longer accessible.
 432 */
 433 int sqlite3_vfs_unregister(sqlite3_vfs *pVfs){
 434   MUTEX_LOGIC(sqlite3_mutex *mutex;)
 435 #ifndef SQLITE_OMIT_AUTOINIT
 436   int rc = sqlite3_initialize();
 437   if( rc ) return rc;
 438 #endif
 439   MUTEX_LOGIC( mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MAIN); )
 440   sqlite3_mutex_enter(mutex);
 441   vfsUnlink(pVfs);
 442   sqlite3_mutex_leave(mutex);
 443   return SQLITE_OK;
 444 }