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 ** $Id: os.c,v 1.124 2008/10/07 15:25:48 drh Exp $

    17 */

    18 #define _SQLITE_OS_C_ 1

    19 #include "sqliteInt.h"

    20 #undef _SQLITE_OS_C_

    21 

    22 /*

    23 ** The default SQLite sqlite3_vfs implementations do not allocate

    24 ** memory (actually, os_unix.c allocates a small amount of memory

    25 ** from within OsOpen()), but some third-party implementations may.

    26 ** So we test the effects of a malloc() failing and the sqlite3OsXXX()

    27 ** function returning SQLITE_IOERR_NOMEM using the DO_OS_MALLOC_TEST macro.

    28 **

    29 ** The following functions are instrumented for malloc() failure 

    30 ** testing:

    31 **

    32 **     sqlite3OsOpen()

    33 **     sqlite3OsRead()

    34 **     sqlite3OsWrite()

    35 **     sqlite3OsSync()

    36 **     sqlite3OsLock()

    37 **

    38 */

    39 #if defined(SQLITE_TEST) && (SQLITE_OS_WIN==0)

    40   #define DO_OS_MALLOC_TEST if (1) {            \

    41     void *pTstAlloc = sqlite3Malloc(10);       \

    42     if (!pTstAlloc) return SQLITE_IOERR_NOMEM;  \

    43     sqlite3_free(pTstAlloc);                    \

    44   }

    45 #else

    46   #define DO_OS_MALLOC_TEST

    47 #endif

    48 

    49 /*

    50 ** The following routines are convenience wrappers around methods

    51 ** of the sqlite3_file object.  This is mostly just syntactic sugar. All

    52 ** of this would be completely automatic if SQLite were coded using

    53 ** C++ instead of plain old C.

    54 */

    55 int sqlite3OsClose(sqlite3_file *pId){

    56   int rc = SQLITE_OK;

    57   if( pId->pMethods ){

    58     rc = pId->pMethods->xClose(pId);

    59     pId->pMethods = 0;

    60   }

    61   return rc;

    62 }

    63 int sqlite3OsRead(sqlite3_file *id, void *pBuf, int amt, i64 offset){

    64   DO_OS_MALLOC_TEST;

    65   return id->pMethods->xRead(id, pBuf, amt, offset);

    66 }

    67 int sqlite3OsWrite(sqlite3_file *id, const void *pBuf, int amt, i64 offset){

    68   DO_OS_MALLOC_TEST;

    69   return id->pMethods->xWrite(id, pBuf, amt, offset);

    70 }

    71 int sqlite3OsTruncate(sqlite3_file *id, i64 size){

    72   return id->pMethods->xTruncate(id, size);

    73 }

    74 int sqlite3OsSync(sqlite3_file *id, int flags){

    75   DO_OS_MALLOC_TEST;

    76   return id->pMethods->xSync(id, flags);

    77 }

    78 int sqlite3OsFileSize(sqlite3_file *id, i64 *pSize){

    79   DO_OS_MALLOC_TEST;

    80   return id->pMethods->xFileSize(id, pSize);

    81 }

    82 int sqlite3OsLock(sqlite3_file *id, int lockType){

    83   DO_OS_MALLOC_TEST;

    84   return id->pMethods->xLock(id, lockType);

    85 }

    86 int sqlite3OsUnlock(sqlite3_file *id, int lockType){

    87   return id->pMethods->xUnlock(id, lockType);

    88 }

    89 int sqlite3OsCheckReservedLock(sqlite3_file *id, int *pResOut){

    90   DO_OS_MALLOC_TEST;

    91   return id->pMethods->xCheckReservedLock(id, pResOut);

    92 }

    93 int sqlite3OsFileControl(sqlite3_file *id, int op, void *pArg){

    94   return id->pMethods->xFileControl(id, op, pArg);

    95 }

    96 int sqlite3OsSectorSize(sqlite3_file *id){

    97   int (*xSectorSize)(sqlite3_file*) = id->pMethods->xSectorSize;

    98   return (xSectorSize ? xSectorSize(id) : SQLITE_DEFAULT_SECTOR_SIZE);

    99 }

   100 int sqlite3OsDeviceCharacteristics(sqlite3_file *id){

   101   return id->pMethods->xDeviceCharacteristics(id);

   102 }

   103 

   104 /*

   105 ** The next group of routines are convenience wrappers around the

   106 ** VFS methods.

   107 */

   108 int sqlite3OsOpen(

   109   sqlite3_vfs *pVfs, 

   110   const char *zPath, 

   111   sqlite3_file *pFile, 

   112   int flags, 

   113   int *pFlagsOut

   114 ){

   115   DO_OS_MALLOC_TEST;

   116   return pVfs->xOpen(pVfs, zPath, pFile, flags, pFlagsOut);

   117 }

   118 int sqlite3OsDelete(sqlite3_vfs *pVfs, const char *zPath, int dirSync){

   119   return pVfs->xDelete(pVfs, zPath, dirSync);

   120 }

   121 int sqlite3OsAccess(

   122   sqlite3_vfs *pVfs, 

   123   const char *zPath, 

   124   int flags, 

   125   int *pResOut

   126 ){

   127   DO_OS_MALLOC_TEST;

   128   return pVfs->xAccess(pVfs, zPath, flags, pResOut);

   129 }

   130 int sqlite3OsFullPathname(

   131   sqlite3_vfs *pVfs, 

   132   const char *zPath, 

   133   int nPathOut, 

   134   char *zPathOut

   135 ){

   136   return pVfs->xFullPathname(pVfs, zPath, nPathOut, zPathOut);

   137 }

   138 #ifndef SQLITE_OMIT_LOAD_EXTENSION

   139 void *sqlite3OsDlOpen(sqlite3_vfs *pVfs, const char *zPath){

   140   return pVfs->xDlOpen(pVfs, zPath);

   141 }

   142 void sqlite3OsDlError(sqlite3_vfs *pVfs, int nByte, char *zBufOut){

   143   pVfs->xDlError(pVfs, nByte, zBufOut);

   144 }

   145 void *sqlite3OsDlSym(sqlite3_vfs *pVfs, void *pHandle, const char *zSymbol){

   146   return pVfs->xDlSym(pVfs, pHandle, zSymbol);

   147 }

   148 void sqlite3OsDlClose(sqlite3_vfs *pVfs, void *pHandle){

   149   pVfs->xDlClose(pVfs, pHandle);

   150 }

   151 #endif /* SQLITE_OMIT_LOAD_EXTENSION */

   152 int sqlite3OsRandomness(sqlite3_vfs *pVfs, int nByte, char *zBufOut){

   153   return pVfs->xRandomness(pVfs, nByte, zBufOut);

   154 }

   155 int sqlite3OsSleep(sqlite3_vfs *pVfs, int nMicro){

   156   return pVfs->xSleep(pVfs, nMicro);

   157 }

   158 int sqlite3OsCurrentTime(sqlite3_vfs *pVfs, double *pTimeOut){

   159   return pVfs->xCurrentTime(pVfs, pTimeOut);

   160 }

   161 

   162 int sqlite3OsOpenMalloc(

   163   sqlite3_vfs *pVfs, 

   164   const char *zFile, 

   165   sqlite3_file **ppFile, 

   166   int flags,

   167   int *pOutFlags

   168 ){

   169   int rc = SQLITE_NOMEM;

   170   sqlite3_file *pFile;

   171   pFile = (sqlite3_file *)sqlite3Malloc(pVfs->szOsFile);

   172   if( pFile ){

   173     rc = sqlite3OsOpen(pVfs, zFile, pFile, flags, pOutFlags);

   174     if( rc!=SQLITE_OK ){

   175       sqlite3_free(pFile);

   176     }else{

   177       *ppFile = pFile;

   178     }

   179   }

   180   return rc;

   181 }

   182 int sqlite3OsCloseFree(sqlite3_file *pFile){

   183   int rc = SQLITE_OK;

   184   assert( pFile );

   185   rc = sqlite3OsClose(pFile);

   186   sqlite3_free(pFile);

   187   return rc;

   188 }

   189 

   190 /*

   191 ** The list of all registered VFS implementations.

   192 */

   193 static sqlite3_vfs * SQLITE_WSD vfsList = 0;

   194 #define vfsList GLOBAL(sqlite3_vfs *, vfsList)

   195 

   196 /*

   197 ** Locate a VFS by name.  If no name is given, simply return the

   198 ** first VFS on the list.

   199 */

   200 sqlite3_vfs *sqlite3_vfs_find(const char *zVfs){

   201   sqlite3_vfs *pVfs = 0;

   202 #if SQLITE_THREADSAFE

   203   sqlite3_mutex *mutex;

   204 #endif

   205 #ifndef SQLITE_OMIT_AUTOINIT

   206   int rc = sqlite3_initialize();

   207   if( rc ) return 0;

   208 #endif

   209 #if SQLITE_THREADSAFE

   210   mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);

   211 #endif

   212   sqlite3_mutex_enter(mutex);

   213   for(pVfs = vfsList; pVfs; pVfs=pVfs->pNext){

   214     if( zVfs==0 ) break;

   215     if( strcmp(zVfs, pVfs->zName)==0 ) break;

   216   }

   217   sqlite3_mutex_leave(mutex);

   218   return pVfs;

   219 }

   220 

   221 /*

   222 ** Unlink a VFS from the linked list

   223 */

   224 static void vfsUnlink(sqlite3_vfs *pVfs){

   225   assert( sqlite3_mutex_held(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER)) );

   226   if( pVfs==0 ){

   227     /* No-op */

   228   }else if( vfsList==pVfs ){

   229     vfsList = pVfs->pNext;

   230   }else if( vfsList ){

   231     sqlite3_vfs *p = vfsList;

   232     while( p->pNext && p->pNext!=pVfs ){

   233       p = p->pNext;

   234     }

   235     if( p->pNext==pVfs ){

   236       p->pNext = pVfs->pNext;

   237     }

   238   }

   239 }

   240 

   241 /*

   242 ** Register a VFS with the system.  It is harmless to register the same

   243 ** VFS multiple times.  The new VFS becomes the default if makeDflt is

   244 ** true.

   245 */

   246 int sqlite3_vfs_register(sqlite3_vfs *pVfs, int makeDflt){

   247   sqlite3_mutex *mutex = 0;

   248 #ifndef SQLITE_OMIT_AUTOINIT

   249   int rc = sqlite3_initialize();

   250   if( rc ) return rc;

   251 #endif

   252   mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);

   253   sqlite3_mutex_enter(mutex);

   254   vfsUnlink(pVfs);

   255   if( makeDflt || vfsList==0 ){

   256     pVfs->pNext = vfsList;

   257     vfsList = pVfs;

   258   }else{

   259     pVfs->pNext = vfsList->pNext;

   260     vfsList->pNext = pVfs;

   261   }

   262   assert(vfsList);

   263   sqlite3_mutex_leave(mutex);

   264   return SQLITE_OK;

   265 }

   266 

   267 /*

   268 ** Unregister a VFS so that it is no longer accessible.

   269 */

   270 int sqlite3_vfs_unregister(sqlite3_vfs *pVfs){

   271 #if SQLITE_THREADSAFE

   272   sqlite3_mutex *mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);

   273 #endif

   274   sqlite3_mutex_enter(mutex);

   275   vfsUnlink(pVfs);

   276   sqlite3_mutex_leave(mutex);

   277   return SQLITE_OK;

   278 }