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 #ifdef SQLITE_TEST
 129   if( op!=SQLITE_FCNTL_COMMIT_PHASETWO ){
 130     /* Faults are not injected into COMMIT_PHASETWO because, assuming SQLite
 131     ** is using a regular VFS, it is called after the corresponding
 132     ** transaction has been committed. Injecting a fault at this point
 133     ** confuses the test scripts - the COMMIT comand returns SQLITE_NOMEM
 134     ** but the transaction is committed anyway.
 135     **
 136     ** The core must call OsFileControl() though, not OsFileControlHint(),
 137     ** as if a custom VFS (e.g. zipvfs) returns an error here, it probably
 138     ** means the commit really has failed and an error should be returned
 139     ** to the user.  */
 140     DO_OS_MALLOC_TEST(id);
 141   }
 142 #endif
 143   return id->pMethods->xFileControl(id, op, pArg);
 144 }
 145 void sqlite3OsFileControlHint(sqlite3_file *id, int op, void *pArg){
 146   (void)id->pMethods->xFileControl(id, op, pArg);
 147 }
 148
 149 int sqlite3OsSectorSize(sqlite3_file *id){
 150   int (*xSectorSize)(sqlite3_file*) = id->pMethods->xSectorSize;
 151   return (xSectorSize ? xSectorSize(id) : SQLITE_DEFAULT_SECTOR_SIZE);
 152 }
 153 int sqlite3OsDeviceCharacteristics(sqlite3_file *id){
 154   return id->pMethods->xDeviceCharacteristics(id);
 155 }
 156 #ifndef SQLITE_OMIT_WAL
 157 int sqlite3OsShmLock(sqlite3_file *id, int offset, int n, int flags){
 158   return id->pMethods->xShmLock(id, offset, n, flags);
 159 }
 160 void sqlite3OsShmBarrier(sqlite3_file *id){
 161   id->pMethods->xShmBarrier(id);
 162 }
 163 int sqlite3OsShmUnmap(sqlite3_file *id, int deleteFlag){
 164   return id->pMethods->xShmUnmap(id, deleteFlag);
 165 }
 166 int sqlite3OsShmMap(
 167   sqlite3_file *id,               /* Database file handle */
 168   int iPage,
 169   int pgsz,
 170   int bExtend,                    /* True to extend file if necessary */
 171   void volatile **pp              /* OUT: Pointer to mapping */
 172 ){
 173   DO_OS_MALLOC_TEST(id);
 174   return id->pMethods->xShmMap(id, iPage, pgsz, bExtend, pp);
 175 }
 176 #endif /* SQLITE_OMIT_WAL */
 177
 178 #if SQLITE_MAX_MMAP_SIZE>0
 179 /* The real implementation of xFetch and xUnfetch */
 180 int sqlite3OsFetch(sqlite3_file *id, i64 iOff, int iAmt, void **pp){
 181   DO_OS_MALLOC_TEST(id);
 182   return id->pMethods->xFetch(id, iOff, iAmt, pp);
 183 }
 184 int sqlite3OsUnfetch(sqlite3_file *id, i64 iOff, void *p){
 185   return id->pMethods->xUnfetch(id, iOff, p);
 186 }
 187 #else
 188 /* No-op stubs to use when memory-mapped I/O is disabled */
 189 int sqlite3OsFetch(sqlite3_file *id, i64 iOff, int iAmt, void **pp){
 190   *pp = 0;
 191   return SQLITE_OK;
 192 }
 193 int sqlite3OsUnfetch(sqlite3_file *id, i64 iOff, void *p){
 194   return SQLITE_OK;
 195 }
 196 #endif
 197
 198 /*
 199 ** The next group of routines are convenience wrappers around the
 200 ** VFS methods.
 201 */
 202 int sqlite3OsOpen(
 203   sqlite3_vfs *pVfs,
 204   const char *zPath,
 205   sqlite3_file *pFile,
 206   int flags,
 207   int *pFlagsOut
 208 ){
 209   int rc;
 210   DO_OS_MALLOC_TEST(0);
 211   /* 0x87f7f is a mask of SQLITE_OPEN_ flags that are valid to be passed
 212   ** down into the VFS layer.  Some SQLITE_OPEN_ flags (for example,
 213   ** SQLITE_OPEN_FULLMUTEX or SQLITE_OPEN_SHAREDCACHE) are blocked before
 214   ** reaching the VFS. */
 215   rc = pVfs->xOpen(pVfs, zPath, pFile, flags & 0x87f7f, pFlagsOut);
 216   assert( rc==SQLITE_OK || pFile->pMethods==0 );
 217   return rc;
 218 }
 219 int sqlite3OsDelete(sqlite3_vfs *pVfs, const char *zPath, int dirSync){
 220   DO_OS_MALLOC_TEST(0);
 221   assert( dirSync==0 || dirSync==1 );
 222   return pVfs->xDelete(pVfs, zPath, dirSync);
 223 }
 224 int sqlite3OsAccess(
 225   sqlite3_vfs *pVfs,
 226   const char *zPath,
 227   int flags,
 228   int *pResOut
 229 ){
 230   DO_OS_MALLOC_TEST(0);
 231   return pVfs->xAccess(pVfs, zPath, flags, pResOut);
 232 }
 233 int sqlite3OsFullPathname(
 234   sqlite3_vfs *pVfs,
 235   const char *zPath,
 236   int nPathOut,
 237   char *zPathOut
 238 ){
 239   DO_OS_MALLOC_TEST(0);
 240   zPathOut[0] = 0;
 241   return pVfs->xFullPathname(pVfs, zPath, nPathOut, zPathOut);
 242 }
 243 #ifndef SQLITE_OMIT_LOAD_EXTENSION
 244 void *sqlite3OsDlOpen(sqlite3_vfs *pVfs, const char *zPath){
 245   return pVfs->xDlOpen(pVfs, zPath);
 246 }
 247 void sqlite3OsDlError(sqlite3_vfs *pVfs, int nByte, char *zBufOut){
 248   pVfs->xDlError(pVfs, nByte, zBufOut);
 249 }
 250 void (*sqlite3OsDlSym(sqlite3_vfs *pVfs, void *pHdle, const char *zSym))(void){
 251   return pVfs->xDlSym(pVfs, pHdle, zSym);
 252 }
 253 void sqlite3OsDlClose(sqlite3_vfs *pVfs, void *pHandle){
 254   pVfs->xDlClose(pVfs, pHandle);
 255 }
 256 #endif /* SQLITE_OMIT_LOAD_EXTENSION */
 257 int sqlite3OsRandomness(sqlite3_vfs *pVfs, int nByte, char *zBufOut){
 258   return pVfs->xRandomness(pVfs, nByte, zBufOut);
 259 }
 260 int sqlite3OsSleep(sqlite3_vfs *pVfs, int nMicro){
 261   return pVfs->xSleep(pVfs, nMicro);
 262 }
 263 int sqlite3OsGetLastError(sqlite3_vfs *pVfs){
 264   return pVfs->xGetLastError ? pVfs->xGetLastError(pVfs, 0, 0) : 0;
 265 }
 266 int sqlite3OsCurrentTimeInt64(sqlite3_vfs *pVfs, sqlite3_int64 *pTimeOut){
 267   int rc;
 268   /* IMPLEMENTATION-OF: R-49045-42493 SQLite will use the xCurrentTimeInt64()
 269   ** method to get the current date and time if that method is available
 270   ** (if iVersion is 2 or greater and the function pointer is not NULL) and
 271   ** will fall back to xCurrentTime() if xCurrentTimeInt64() is
 272   ** unavailable.
 273   */
 274   if( pVfs->iVersion>=2 && pVfs->xCurrentTimeInt64 ){
 275     rc = pVfs->xCurrentTimeInt64(pVfs, pTimeOut);
 276   }else{
 277     double r;
 278     rc = pVfs->xCurrentTime(pVfs, &r);
 279     *pTimeOut = (sqlite3_int64)(r*86400000.0);
 280   }
 281   return rc;
 282 }
 283
 284 int sqlite3OsOpenMalloc(
 285   sqlite3_vfs *pVfs,
 286   const char *zFile,
 287   sqlite3_file **ppFile,
 288   int flags,
 289   int *pOutFlags
 290 ){
 291   int rc;
 292   sqlite3_file *pFile;
 293   pFile = (sqlite3_file *)sqlite3MallocZero(pVfs->szOsFile);
 294   if( pFile ){
 295     rc = sqlite3OsOpen(pVfs, zFile, pFile, flags, pOutFlags);
 296     if( rc!=SQLITE_OK ){
 297       sqlite3_free(pFile);
 298     }else{
 299       *ppFile = pFile;
 300     }
 301   }else{
 302     rc = SQLITE_NOMEM_BKPT;
 303   }
 304   return rc;
 305 }
 306 void sqlite3OsCloseFree(sqlite3_file *pFile){
 307   assert( pFile );
 308   sqlite3OsClose(pFile);
 309   sqlite3_free(pFile);
 310 }
 311
 312 /*
 313 ** This function is a wrapper around the OS specific implementation of
 314 ** sqlite3_os_init(). The purpose of the wrapper is to provide the
 315 ** ability to simulate a malloc failure, so that the handling of an
 316 ** error in sqlite3_os_init() by the upper layers can be tested.
 317 */
 318 int sqlite3OsInit(void){
 319   void *p = sqlite3_malloc(10);
 320   if( p==0 ) return SQLITE_NOMEM_BKPT;
 321   sqlite3_free(p);
 322   return sqlite3_os_init();
 323 }
 324
 325 /*
 326 ** The list of all registered VFS implementations.
 327 */
 328 static sqlite3_vfs * SQLITE_WSD vfsList = 0;
 329 #define vfsList GLOBAL(sqlite3_vfs *, vfsList)
 330
 331 /*
 332 ** Locate a VFS by name.  If no name is given, simply return the
 333 ** first VFS on the list.
 334 */
 335 sqlite3_vfs *sqlite3_vfs_find(const char *zVfs){
 336   sqlite3_vfs *pVfs = 0;
 337 #if SQLITE_THREADSAFE
 338   sqlite3_mutex *mutex;
 339 #endif
 340 #ifndef SQLITE_OMIT_AUTOINIT
 341   int rc = sqlite3_initialize();
 342   if( rc ) return 0;
 343 #endif
 344 #if SQLITE_THREADSAFE
 345   mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
 346 #endif
 347   sqlite3_mutex_enter(mutex);
 348   for(pVfs = vfsList; pVfs; pVfs=pVfs->pNext){
 349     if( zVfs==0 ) break;
 350     if( strcmp(zVfs, pVfs->zName)==0 ) break;
 351   }
 352   sqlite3_mutex_leave(mutex);
 353   return pVfs;
 354 }
 355
 356 /*
 357 ** Unlink a VFS from the linked list
 358 */
 359 static void vfsUnlink(sqlite3_vfs *pVfs){
 360   assert( sqlite3_mutex_held(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER)) );
 361   if( pVfs==0 ){
 362     /* No-op */
 363   }else if( vfsList==pVfs ){
 364     vfsList = pVfs->pNext;
 365   }else if( vfsList ){
 366     sqlite3_vfs *p = vfsList;
 367     while( p->pNext && p->pNext!=pVfs ){
 368       p = p->pNext;
 369     }
 370     if( p->pNext==pVfs ){
 371       p->pNext = pVfs->pNext;
 372     }
 373   }
 374 }
 375
 376 /*
 377 ** Register a VFS with the system.  It is harmless to register the same
 378 ** VFS multiple times.  The new VFS becomes the default if makeDflt is
 379 ** true.
 380 */
 381 int sqlite3_vfs_register(sqlite3_vfs *pVfs, int makeDflt){
 382   MUTEX_LOGIC(sqlite3_mutex *mutex;)
 383 #ifndef SQLITE_OMIT_AUTOINIT
 384   int rc = sqlite3_initialize();
 385   if( rc ) return rc;
 386 #endif
 387 #ifdef SQLITE_ENABLE_API_ARMOR
 388   if( pVfs==0 ) return SQLITE_MISUSE_BKPT;
 389 #endif
 390
 391   MUTEX_LOGIC( mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER); )
 392   sqlite3_mutex_enter(mutex);
 393   vfsUnlink(pVfs);
 394   if( makeDflt || vfsList==0 ){
 395     pVfs->pNext = vfsList;
 396     vfsList = pVfs;
 397   }else{
 398     pVfs->pNext = vfsList->pNext;
 399     vfsList->pNext = pVfs;
 400   }
 401   assert(vfsList);
 402   sqlite3_mutex_leave(mutex);
 403   return SQLITE_OK;
 404 }
 405
 406 /*
 407 ** Unregister a VFS so that it is no longer accessible.
 408 */
 409 int sqlite3_vfs_unregister(sqlite3_vfs *pVfs){
 410 #if SQLITE_THREADSAFE
 411   sqlite3_mutex *mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
 412 #endif
 413   sqlite3_mutex_enter(mutex);
 414   vfsUnlink(pVfs);
 415   sqlite3_mutex_leave(mutex);
 416   return SQLITE_OK;
 417 }