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