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 #if SQLITE_MAX_MMAP_SIZE>0
 145 /* The real implementation of xFetch and xUnfetch */
 146 int sqlite3OsFetch(sqlite3_file *id, i64 iOff, int iAmt, void **pp){
 147   DO_OS_MALLOC_TEST(id);
 148   return id->pMethods->xFetch(id, iOff, iAmt, pp);
 149 }
 150 int sqlite3OsUnfetch(sqlite3_file *id, i64 iOff, void *p){
 151   return id->pMethods->xUnfetch(id, iOff, p);
 152 }
 153 #else
 154 /* No-op stubs to use when memory-mapped I/O is disabled */
 155 int sqlite3OsFetch(sqlite3_file *id, i64 iOff, int iAmt, void **pp){
 156   *pp = 0;
 157   return SQLITE_OK;
 158 }
 159 int sqlite3OsUnfetch(sqlite3_file *id, i64 iOff, void *p){
 160   return SQLITE_OK;
 161 }
 162 #endif
 163
 164 /*
 165 ** The next group of routines are convenience wrappers around the
 166 ** VFS methods.
 167 */
 168 int sqlite3OsOpen(
 169   sqlite3_vfs *pVfs,
 170   const char *zPath,
 171   sqlite3_file *pFile,
 172   int flags,
 173   int *pFlagsOut
 174 ){
 175   int rc;
 176   DO_OS_MALLOC_TEST(0);
 177   /* 0x87f7f is a mask of SQLITE_OPEN_ flags that are valid to be passed
 178   ** down into the VFS layer.  Some SQLITE_OPEN_ flags (for example,
 179   ** SQLITE_OPEN_FULLMUTEX or SQLITE_OPEN_SHAREDCACHE) are blocked before
 180   ** reaching the VFS. */
 181   rc = pVfs->xOpen(pVfs, zPath, pFile, flags & 0x87f7f, pFlagsOut);
 182   assert( rc==SQLITE_OK || pFile->pMethods==0 );
 183   return rc;
 184 }
 185 int sqlite3OsDelete(sqlite3_vfs *pVfs, const char *zPath, int dirSync){
 186   DO_OS_MALLOC_TEST(0);
 187   assert( dirSync==0 || dirSync==1 );
 188   return pVfs->xDelete(pVfs, zPath, dirSync);
 189 }
 190 int sqlite3OsAccess(
 191   sqlite3_vfs *pVfs,
 192   const char *zPath,
 193   int flags,
 194   int *pResOut
 195 ){
 196   DO_OS_MALLOC_TEST(0);
 197   return pVfs->xAccess(pVfs, zPath, flags, pResOut);
 198 }
 199 int sqlite3OsFullPathname(
 200   sqlite3_vfs *pVfs,
 201   const char *zPath,
 202   int nPathOut,
 203   char *zPathOut
 204 ){
 205   DO_OS_MALLOC_TEST(0);
 206   zPathOut[0] = 0;
 207   return pVfs->xFullPathname(pVfs, zPath, nPathOut, zPathOut);
 208 }
 209 #ifndef SQLITE_OMIT_LOAD_EXTENSION
 210 void *sqlite3OsDlOpen(sqlite3_vfs *pVfs, const char *zPath){
 211   return pVfs->xDlOpen(pVfs, zPath);
 212 }
 213 void sqlite3OsDlError(sqlite3_vfs *pVfs, int nByte, char *zBufOut){
 214   pVfs->xDlError(pVfs, nByte, zBufOut);
 215 }
 216 void (*sqlite3OsDlSym(sqlite3_vfs *pVfs, void *pHdle, const char *zSym))(void){
 217   return pVfs->xDlSym(pVfs, pHdle, zSym);
 218 }
 219 void sqlite3OsDlClose(sqlite3_vfs *pVfs, void *pHandle){
 220   pVfs->xDlClose(pVfs, pHandle);
 221 }
 222 #endif /* SQLITE_OMIT_LOAD_EXTENSION */
 223 int sqlite3OsRandomness(sqlite3_vfs *pVfs, int nByte, char *zBufOut){
 224   return pVfs->xRandomness(pVfs, nByte, zBufOut);
 225 }
 226 int sqlite3OsSleep(sqlite3_vfs *pVfs, int nMicro){
 227   return pVfs->xSleep(pVfs, nMicro);
 228 }
 229 int sqlite3OsCurrentTimeInt64(sqlite3_vfs *pVfs, sqlite3_int64 *pTimeOut){
 230   int rc;
 231   /* IMPLEMENTATION-OF: R-49045-42493 SQLite will use the xCurrentTimeInt64()
 232   ** method to get the current date and time if that method is available
 233   ** (if iVersion is 2 or greater and the function pointer is not NULL) and
 234   ** will fall back to xCurrentTime() if xCurrentTimeInt64() is
 235   ** unavailable.
 236   */
 237   if( pVfs->iVersion>=2 && pVfs->xCurrentTimeInt64 ){
 238     rc = pVfs->xCurrentTimeInt64(pVfs, pTimeOut);
 239   }else{
 240     double r;
 241     rc = pVfs->xCurrentTime(pVfs, &r);
 242     *pTimeOut = (sqlite3_int64)(r*86400000.0);
 243   }
 244   return rc;
 245 }
 246
 247 int sqlite3OsOpenMalloc(
 248   sqlite3_vfs *pVfs,
 249   const char *zFile,
 250   sqlite3_file **ppFile,
 251   int flags,
 252   int *pOutFlags
 253 ){
 254   int rc = SQLITE_NOMEM;
 255   sqlite3_file *pFile;
 256   pFile = (sqlite3_file *)sqlite3MallocZero(pVfs->szOsFile);
 257   if( pFile ){
 258     rc = sqlite3OsOpen(pVfs, zFile, pFile, flags, pOutFlags);
 259     if( rc!=SQLITE_OK ){
 260       sqlite3_free(pFile);
 261     }else{
 262       *ppFile = pFile;
 263     }
 264   }
 265   return rc;
 266 }
 267 int sqlite3OsCloseFree(sqlite3_file *pFile){
 268   int rc = SQLITE_OK;
 269   assert( pFile );
 270   rc = sqlite3OsClose(pFile);
 271   sqlite3_free(pFile);
 272   return rc;
 273 }
 274
 275 /*
 276 ** This function is a wrapper around the OS specific implementation of
 277 ** sqlite3_os_init(). The purpose of the wrapper is to provide the
 278 ** ability to simulate a malloc failure, so that the handling of an
 279 ** error in sqlite3_os_init() by the upper layers can be tested.
 280 */
 281 int sqlite3OsInit(void){
 282   void *p = sqlite3_malloc(10);
 283   if( p==0 ) return SQLITE_NOMEM;
 284   sqlite3_free(p);
 285   return sqlite3_os_init();
 286 }
 287
 288 /*
 289 ** The list of all registered VFS implementations.
 290 */
 291 static sqlite3_vfs * SQLITE_WSD vfsList = 0;
 292 #define vfsList GLOBAL(sqlite3_vfs *, vfsList)
 293
 294 /*
 295 ** Locate a VFS by name.  If no name is given, simply return the
 296 ** first VFS on the list.
 297 */
 298 sqlite3_vfs *sqlite3_vfs_find(const char *zVfs){
 299   sqlite3_vfs *pVfs = 0;
 300 #if SQLITE_THREADSAFE
 301   sqlite3_mutex *mutex;
 302 #endif
 303 #ifndef SQLITE_OMIT_AUTOINIT
 304   int rc = sqlite3_initialize();
 305   if( rc ) return 0;
 306 #endif
 307 #if SQLITE_THREADSAFE
 308   mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
 309 #endif
 310   sqlite3_mutex_enter(mutex);
 311   for(pVfs = vfsList; pVfs; pVfs=pVfs->pNext){
 312     if( zVfs==0 ) break;
 313     if( strcmp(zVfs, pVfs->zName)==0 ) break;
 314   }
 315   sqlite3_mutex_leave(mutex);
 316   return pVfs;
 317 }
 318
 319 /*
 320 ** Unlink a VFS from the linked list
 321 */
 322 static void vfsUnlink(sqlite3_vfs *pVfs){
 323   assert( sqlite3_mutex_held(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER)) );
 324   if( pVfs==0 ){
 325     /* No-op */
 326   }else if( vfsList==pVfs ){
 327     vfsList = pVfs->pNext;
 328   }else if( vfsList ){
 329     sqlite3_vfs *p = vfsList;
 330     while( p->pNext && p->pNext!=pVfs ){
 331       p = p->pNext;
 332     }
 333     if( p->pNext==pVfs ){
 334       p->pNext = pVfs->pNext;
 335     }
 336   }
 337 }
 338
 339 /*
 340 ** Register a VFS with the system.  It is harmless to register the same
 341 ** VFS multiple times.  The new VFS becomes the default if makeDflt is
 342 ** true.
 343 */
 344 int sqlite3_vfs_register(sqlite3_vfs *pVfs, int makeDflt){
 345   MUTEX_LOGIC(sqlite3_mutex *mutex;)
 346 #ifndef SQLITE_OMIT_AUTOINIT
 347   int rc = sqlite3_initialize();
 348   if( rc ) return rc;
 349 #endif
 350   MUTEX_LOGIC( mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER); )
 351   sqlite3_mutex_enter(mutex);
 352   vfsUnlink(pVfs);
 353   if( makeDflt || vfsList==0 ){
 354     pVfs->pNext = vfsList;
 355     vfsList = pVfs;
 356   }else{
 357     pVfs->pNext = vfsList->pNext;
 358     vfsList->pNext = pVfs;
 359   }
 360   assert(vfsList);
 361   sqlite3_mutex_leave(mutex);
 362   return SQLITE_OK;
 363 }
 364
 365 /*
 366 ** Unregister a VFS so that it is no longer accessible.
 367 */
 368 int sqlite3_vfs_unregister(sqlite3_vfs *pVfs){
 369 #if SQLITE_THREADSAFE
 370   sqlite3_mutex *mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);
 371 #endif
 372   sqlite3_mutex_enter(mutex);
 373   vfsUnlink(pVfs);
 374   sqlite3_mutex_leave(mutex);
 375   return SQLITE_OK;
 376 }