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 #define _SQLITE_OS_C_ 1
  17 #include "sqliteInt.h"
  18 #undef _SQLITE_OS_C_
  19
  20 /*
  21 ** The default SQLite sqlite3_vfs implementations do not allocate
  22 ** memory (actually, os_unix.c allocates a small amount of memory
  23 ** from within OsOpen()), but some third-party implementations may.
  24 ** So we test the effects of a malloc() failing and the sqlite3OsXXX()
  25 ** function returning SQLITE_IOERR_NOMEM using the DO_OS_MALLOC_TEST macro.
  26 **
  27 ** The following functions are instrumented for malloc() failure
  28 ** testing:
  29 **
  30 **     sqlite3OsRead()
  31 **     sqlite3OsWrite()
  32 **     sqlite3OsSync()
  33 **     sqlite3OsFileSize()
  34 **     sqlite3OsLock()
  35 **     sqlite3OsCheckReservedLock()
  36 **     sqlite3OsFileControl()
  37 **     sqlite3OsShmMap()
  38 **     sqlite3OsOpen()
  39 **     sqlite3OsDelete()
  40 **     sqlite3OsAccess()
  41 **     sqlite3OsFullPathname()
  42 **
  43 */
  44 #if defined(SQLITE_TEST)
  45 int sqlite3_memdebug_vfs_oom_test = 1;
  46   #define DO_OS_MALLOC_TEST(x)                                       \
  47   if (sqlite3_memdebug_vfs_oom_test && (!x || !sqlite3IsMemJournal(x))) {  \
  48     void *pTstAlloc = sqlite3Malloc(10);                             \
  49     if (!pTstAlloc) return SQLITE_IOERR_NOMEM;                       \
  50     sqlite3_free(pTstAlloc);                                         \
  51   }
  52 #else
  53   #define DO_OS_MALLOC_TEST(x)
  54 #endif
  55
  56 /*
  57 ** The following routines are convenience wrappers around methods
  58 ** of the sqlite3_file object.  This is mostly just syntactic sugar. All
  59 ** of this would be completely automatic if SQLite were coded using
  60 ** C++ instead of plain old C.
  61 */
  62 int sqlite3OsClose(sqlite3_file *pId){
  63   int rc = SQLITE_OK;
  64   if( pId->pMethods ){
  65     rc = pId->pMethods->xClose(pId);
  66     pId->pMethods = 0;
  67   }
  68   return rc;
  69 }
  70 int sqlite3OsRead(sqlite3_file *id, void *pBuf, int amt, i64 offset){
  71   DO_OS_MALLOC_TEST(id);
  72   return id->pMethods->xRead(id, pBuf, amt, offset);
  73 }
  74 int sqlite3OsWrite(sqlite3_file *id, const void *pBuf, int amt, i64 offset){
  75   DO_OS_MALLOC_TEST(id);
  76   return id->pMethods->xWrite(id, pBuf, amt, offset);
  77 }
  78 int sqlite3OsTruncate(sqlite3_file *id, i64 size){
  79   return id->pMethods->xTruncate(id, size);
  80 }
  81 int sqlite3OsSync(sqlite3_file *id, int flags){
  82   DO_OS_MALLOC_TEST(id);
  83   return id->pMethods->xSync(id, flags);
  84 }
  85 int sqlite3OsFileSize(sqlite3_file *id, i64 *pSize){
  86   DO_OS_MALLOC_TEST(id);
  87   return id->pMethods->xFileSize(id, pSize);
  88 }
  89 int sqlite3OsLock(sqlite3_file *id, int lockType){
  90   DO_OS_MALLOC_TEST(id);
  91   return id->pMethods->xLock(id, lockType);
  92 }
  93 int sqlite3OsUnlock(sqlite3_file *id, int lockType){
  94   return id->pMethods->xUnlock(id, lockType);
  95 }
  96 int sqlite3OsCheckReservedLock(sqlite3_file *id, int *pResOut){
  97   DO_OS_MALLOC_TEST(id);
  98   return id->pMethods->xCheckReservedLock(id, pResOut);
  99 }
 100
 101 /*
 102 ** Use sqlite3OsFileControl() when we are doing something that might fail
 103 ** and we need to know about the failures.  Use sqlite3OsFileControlHint()
 104 ** when simply tossing information over the wall to the VFS and we do not
 105 ** really care if the VFS receives and understands the information since it
 106 ** is only a hint and can be safely ignored.  The sqlite3OsFileControlHint()
 107 ** routine has no return value since the return value would be meaningless.
 108 */
 109 int sqlite3OsFileControl(sqlite3_file *id, int op, void *pArg){
 110   DO_OS_MALLOC_TEST(id);
 111   return id->pMethods->xFileControl(id, op, pArg);
 112 }
 113 void sqlite3OsFileControlHint(sqlite3_file *id, int op, void *pArg){
 114   (void)id->pMethods->xFileControl(id, op, pArg);
 115 }
 116
 117 int sqlite3OsSectorSize(sqlite3_file *id){
 118   int (*xSectorSize)(sqlite3_file*) = id->pMethods->xSectorSize;
 119   return (xSectorSize ? xSectorSize(id) : SQLITE_DEFAULT_SECTOR_SIZE);
 120 }
 121 int sqlite3OsDeviceCharacteristics(sqlite3_file *id){
 122   return id->pMethods->xDeviceCharacteristics(id);
 123 }
 124 int sqlite3OsShmLock(sqlite3_file *id, int offset, int n, int flags){
 125   return id->pMethods->xShmLock(id, offset, n, flags);
 126 }
 127 void sqlite3OsShmBarrier(sqlite3_file *id){
 128   id->pMethods->xShmBarrier(id);
 129 }
 130 int sqlite3OsShmUnmap(sqlite3_file *id, int deleteFlag){
 131   return id->pMethods->xShmUnmap(id, deleteFlag);
 132 }
 133 int sqlite3OsShmMap(
 134   sqlite3_file *id,               /* Database file handle */
 135   int iPage,
 136   int pgsz,
 137   int bExtend,                    /* True to extend file if necessary */
 138   void volatile **pp              /* OUT: Pointer to mapping */
 139 ){
 140   DO_OS_MALLOC_TEST(id);
 141   return id->pMethods->xShmMap(id, iPage, pgsz, bExtend, pp);
 142 }
 143
 144 /*
 145 ** The next group of routines are convenience wrappers around the
 146 ** VFS methods.
 147 */
 148 int sqlite3OsOpen(
 149   sqlite3_vfs *pVfs,
 150   const char *zPath,
 151   sqlite3_file *pFile,
 152   int flags,
 153   int *pFlagsOut
 154 ){
 155   int rc;
 156   DO_OS_MALLOC_TEST(0);
 157   /* 0x87f7f is a mask of SQLITE_OPEN_ flags that are valid to be passed
 158   ** down into the VFS layer.  Some SQLITE_OPEN_ flags (for example,
 159   ** SQLITE_OPEN_FULLMUTEX or SQLITE_OPEN_SHAREDCACHE) are blocked before
 160   ** reaching the VFS. */
 161   rc = pVfs->xOpen(pVfs, zPath, pFile, flags & 0x87f7f, pFlagsOut);
 162   assert( rc==SQLITE_OK || pFile->pMethods==0 );
 163   return rc;
 164 }
 165 int sqlite3OsDelete(sqlite3_vfs *pVfs, const char *zPath, int dirSync){
 166   DO_OS_MALLOC_TEST(0);
 167   assert( dirSync==0 || dirSync==1 );
 168   return pVfs->xDelete(pVfs, zPath, dirSync);
 169 }
 170 int sqlite3OsAccess(
 171   sqlite3_vfs *pVfs,
 172   const char *zPath,
 173   int flags,
 174   int *pResOut
 175 ){
 176   DO_OS_MALLOC_TEST(0);
 177   return pVfs->xAccess(pVfs, zPath, flags, pResOut);
 178 }
 179 int sqlite3OsFullPathname(
 180   sqlite3_vfs *pVfs,
 181   const char *zPath,
 182   int nPathOut,
 183   char *zPathOut
 184 ){
 185   DO_OS_MALLOC_TEST(0);
 186   zPathOut[0] = 0;
 187   return pVfs->xFullPathname(pVfs, zPath, nPathOut, zPathOut);
 188 }
 189 #ifndef SQLITE_OMIT_LOAD_EXTENSION
 190 void *sqlite3OsDlOpen(sqlite3_vfs *pVfs, const char *zPath){
 191   return pVfs->xDlOpen(pVfs, zPath);
 192 }
 193 void sqlite3OsDlError(sqlite3_vfs *pVfs, int nByte, char *zBufOut){
 194   pVfs->xDlError(pVfs, nByte, zBufOut);
 195 }
 196 void (*sqlite3OsDlSym(sqlite3_vfs *pVfs, void *pHdle, const char *zSym))(void){
 197   return pVfs->xDlSym(pVfs, pHdle, zSym);
 198 }
 199 void sqlite3OsDlClose(sqlite3_vfs *pVfs, void *pHandle){
 200   pVfs->xDlClose(pVfs, pHandle);
 201 }
 202 #endif /* SQLITE_OMIT_LOAD_EXTENSION */
 203 int sqlite3OsRandomness(sqlite3_vfs *pVfs, int nByte, char *zBufOut){
 204   return pVfs->xRandomness(pVfs, nByte, zBufOut);
 205 }
 206 int sqlite3OsSleep(sqlite3_vfs *pVfs, int nMicro){
 207   return pVfs->xSleep(pVfs, nMicro);
 208 }
 209 int sqlite3OsCurrentTimeInt64(sqlite3_vfs *pVfs, sqlite3_int64 *pTimeOut){
 210   int rc;
 211   /* IMPLEMENTATION-OF: R-49045-42493 SQLite will use the xCurrentTimeInt64()
 212   ** method to get the current date and time if that method is available
 213   ** (if iVersion is 2 or greater and the function pointer is not NULL) and
 214   ** will fall back to xCurrentTime() if xCurrentTimeInt64() is
 215   ** unavailable.
 216   */
 217   if( pVfs->iVersion>=2 && pVfs->xCurrentTimeInt64 ){
 218     rc = pVfs->xCurrentTimeInt64(pVfs, pTimeOut);
 219   }else{
 220     double r;
 221     rc = pVfs->xCurrentTime(pVfs, &r);
 222     *pTimeOut = (sqlite3_int64)(r*86400000.0);
 223   }
 224   return rc;
 225 }
 226
 227 int sqlite3OsOpenMalloc(
 228   sqlite3_vfs *pVfs,
 229   const char *zFile,
 230   sqlite3_file **ppFile,
 231   int flags,
 232   int *pOutFlags
 233 ){
 234   int rc = SQLITE_NOMEM;
 235   sqlite3_file *pFile;
 236   pFile = (sqlite3_file *)sqlite3MallocZero(pVfs->szOsFile);
 237   if( pFile ){
 238     rc = sqlite3OsOpen(pVfs, zFile, pFile, flags, pOutFlags);
 239     if( rc!=SQLITE_OK ){
 240       sqlite3_free(pFile);
 241     }else{
 242       *ppFile = pFile;
 243     }
 244   }
 245   return rc;
 246 }
 247 int sqlite3OsCloseFree(sqlite3_file *pFile){
 248   int rc = SQLITE_OK;
 249   assert( pFile );
 250   rc = sqlite3OsClose(pFile);
 251   sqlite3_free(pFile);
 252   return rc;
 253 }
 254
 255 /*
 256 ** This function is a wrapper around the OS specific implementation of
 257 ** sqlite3_os_init(). The purpose of the wrapper is to provide the
 258 ** ability to simulate a malloc failure, so that the handling of an
 259 ** error in sqlite3_os_init() by the upper layers can be tested.
 260 */
 261 int sqlite3OsInit(void){
 262   void *p = sqlite3_malloc(10);
 263   if( p==0 ) return SQLITE_NOMEM;
 264   sqlite3_free(p);
 265   return sqlite3_os_init();
 266 }
 267
 268 /*
 269 ** The list of all registered VFS implementations.
 270 */
 271 static sqlite3_vfs * SQLITE_WSD vfsList = 0;
 272 #define vfsList GLOBAL(sqlite3_vfs *, vfsList)
 273
 274 /*
 275 ** Locate a VFS by name.  If no name is given, simply return the
 276 ** first VFS on the list.
 277 */
 278 sqlite3_vfs *sqlite3_vfs_find(const char *zVfs){
 279   sqlite3_vfs *pVfs = 0;
 280 #if SQLITE_THREADSAFE
 281   sqlite3_mutex *mutex;
 282 #endif
 283 #ifndef SQLITE_OMIT_AUTOINIT
 284   int rc = sqlite3_initialize();
 285   if( rc ) return 0;
 286 #endif
 287 #if SQLITE_THREADSAFE
 288   mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
 289 #endif
 290   sqlite3_mutex_enter(mutex);
 291   for(pVfs = vfsList; pVfs; pVfs=pVfs->pNext){
 292     if( zVfs==0 ) break;
 293     if( strcmp(zVfs, pVfs->zName)==0 ) break;
 294   }
 295   sqlite3_mutex_leave(mutex);
 296   return pVfs;
 297 }
 298
 299 /*
 300 ** Unlink a VFS from the linked list
 301 */
 302 static void vfsUnlink(sqlite3_vfs *pVfs){
 303   assert( sqlite3_mutex_held(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER)) );
 304   if( pVfs==0 ){
 305     /* No-op */
 306   }else if( vfsList==pVfs ){
 307     vfsList = pVfs->pNext;
 308   }else if( vfsList ){
 309     sqlite3_vfs *p = vfsList;
 310     while( p->pNext && p->pNext!=pVfs ){
 311       p = p->pNext;
 312     }
 313     if( p->pNext==pVfs ){
 314       p->pNext = pVfs->pNext;
 315     }
 316   }
 317 }
 318
 319 /*
 320 ** Register a VFS with the system.  It is harmless to register the same
 321 ** VFS multiple times.  The new VFS becomes the default if makeDflt is
 322 ** true.
 323 */
 324 int sqlite3_vfs_register(sqlite3_vfs *pVfs, int makeDflt){
 325   MUTEX_LOGIC(sqlite3_mutex *mutex;)
 326 #ifndef SQLITE_OMIT_AUTOINIT
 327   int rc = sqlite3_initialize();
 328   if( rc ) return rc;
 329 #endif
 330   MUTEX_LOGIC( mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER); )
 331   sqlite3_mutex_enter(mutex);
 332   vfsUnlink(pVfs);
 333   if( makeDflt || vfsList==0 ){
 334     pVfs->pNext = vfsList;
 335     vfsList = pVfs;
 336   }else{
 337     pVfs->pNext = vfsList->pNext;
 338     vfsList->pNext = pVfs;
 339   }
 340   assert(vfsList);
 341   sqlite3_mutex_leave(mutex);
 342   return SQLITE_OK;
 343 }
 344
 345 /*
 346 ** Unregister a VFS so that it is no longer accessible.
 347 */
 348 int sqlite3_vfs_unregister(sqlite3_vfs *pVfs){
 349 #if SQLITE_THREADSAFE
 350   sqlite3_mutex *mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
 351 #endif
 352   sqlite3_mutex_enter(mutex);
 353   vfsUnlink(pVfs);
 354   sqlite3_mutex_leave(mutex);
 355   return SQLITE_OK;
 356 }