/*

 ** 2005 November 29

 **

 ** The author disclaims copyright to this source code.  In place of

 ** a legal notice, here is a blessing:

 **

 **    May you do good and not evil.

 **    May you find forgiveness for yourself and forgive others.

 **    May you share freely, never taking more than you give.

 **

 ******************************************************************************

 **

 ** This file contains OS interface code that is common to all

 ** architectures.

 **

 ** $Id: os.c,v 1.123 2008/09/23 16:41:30 danielk1977 Exp $

 */

 #define _SQLITE_OS_C_ 1

 #include "sqliteInt.h"

 #undef _SQLITE_OS_C_

 /*

 ** The default SQLite sqlite3_vfs implementations do not allocate

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

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

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

 ** function returning SQLITE_IOERR_NOMEM using the DO_OS_MALLOC_TEST macro.

 **

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

 ** testing:

 **

 **     sqlite3OsOpen()

 **     sqlite3OsRead()

 **     sqlite3OsWrite()

 **     sqlite3OsSync()

 **     sqlite3OsLock()

 **

 */

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

   #define DO_OS_MALLOC_TEST if (1) {            \

     void *pTstAlloc = sqlite3Malloc(10);       \

     if (!pTstAlloc) return SQLITE_IOERR_NOMEM;  \

     sqlite3_free(pTstAlloc);                    \

   }

 #else

   #define DO_OS_MALLOC_TEST

 #endif

 /*

 ** The following routines are convenience wrappers around methods

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

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

 ** C++ instead of plain old C.

 */

 int sqlite3OsClose(sqlite3_file *pId){

   int rc = SQLITE_OK;

   if( pId->pMethods ){

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

     pId->pMethods = 0;

   }

   return rc;

 }

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

   DO_OS_MALLOC_TEST;

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

 }

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

   DO_OS_MALLOC_TEST;

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

 }

 int sqlite3OsTruncate(sqlite3_file *id, i64 size){

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

 }

 int sqlite3OsSync(sqlite3_file *id, int flags){

   DO_OS_MALLOC_TEST;

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

 }

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

   DO_OS_MALLOC_TEST;

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

 }

 int sqlite3OsLock(sqlite3_file *id, int lockType){

   DO_OS_MALLOC_TEST;

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

 }

 int sqlite3OsUnlock(sqlite3_file *id, int lockType){

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

 }

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

   DO_OS_MALLOC_TEST;

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

 }

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

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

 }

 int sqlite3OsSectorSize(sqlite3_file *id){

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

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

 }

 int sqlite3OsDeviceCharacteristics(sqlite3_file *id){

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

 }

 /*

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

 ** VFS methods.

 */

 int sqlite3OsOpen(

   sqlite3_vfs *pVfs, 

   const char *zPath, 

   sqlite3_file *pFile, 

   int flags, 

   int *pFlagsOut

 ){

   DO_OS_MALLOC_TEST;

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

 }

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

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

 }

 int sqlite3OsAccess(

   sqlite3_vfs *pVfs, 

   const char *zPath, 

   int flags, 

   int *pResOut

 ){

   DO_OS_MALLOC_TEST;

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

 }

 int sqlite3OsFullPathname(

   sqlite3_vfs *pVfs, 

   const char *zPath, 

   int nPathOut, 

   char *zPathOut

 ){

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

 }

 #ifndef SQLITE_OMIT_LOAD_EXTENSION

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

   return pVfs->xDlOpen(pVfs, zPath);

 }

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

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

 }

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

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

 }

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

   pVfs->xDlClose(pVfs, pHandle);

 }

 #endif /* SQLITE_OMIT_LOAD_EXTENSION */

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

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

 }

 int sqlite3OsSleep(sqlite3_vfs *pVfs, int nMicro){

   return pVfs->xSleep(pVfs, nMicro);

 }

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

   return pVfs->xCurrentTime(pVfs, pTimeOut);

 }

 int sqlite3OsOpenMalloc(

   sqlite3_vfs *pVfs, 

   const char *zFile, 

   sqlite3_file **ppFile, 

   int flags,

   int *pOutFlags

 ){

   int rc = SQLITE_NOMEM;

   sqlite3_file *pFile;

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

   if( pFile ){

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

     if( rc!=SQLITE_OK ){

       sqlite3_free(pFile);

     }else{

       *ppFile = pFile;

     }

   }

   return rc;

 }

 int sqlite3OsCloseFree(sqlite3_file *pFile){

   int rc = SQLITE_OK;

   assert( pFile );

   rc = sqlite3OsClose(pFile);

   sqlite3_free(pFile);

   return rc;

 }

 /*

 ** The list of all registered VFS implementations.

 */

 static sqlite3_vfs * SQLITE_WSD vfsList = 0;

 #define vfsList GLOBAL(sqlite3_vfs *, vfsList)

 /*

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

 ** first VFS on the list.

 */

 SQLITE_EXPORT sqlite3_vfs *sqlite3_vfs_find(const char *zVfs){

   sqlite3_vfs *pVfs = 0;

 #ifndef SQLITE_MUTEX_NOOP

   sqlite3_mutex *mutex;

 #endif

 #ifndef SQLITE_OMIT_AUTOINIT

   int rc = sqlite3_initialize();

   if( rc ) return 0;

 #endif

 #ifndef SQLITE_MUTEX_NOOP

   mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);

 #endif

   sqlite3_mutex_enter(mutex);

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

     if( zVfs==0 ) break;

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

   }

   sqlite3_mutex_leave(mutex);

   return pVfs;

 }

 /*

 ** Unlink a VFS from the linked list

 */

 static void vfsUnlink(sqlite3_vfs *pVfs){

   assert( sqlite3_mutex_held(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER)) );

   if( pVfs==0 ){

     /* No-op */

   }else if( vfsList==pVfs ){

     vfsList = pVfs->pNext;

   }else if( vfsList ){

     sqlite3_vfs *p = vfsList;

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

       p = p->pNext;

     }

     if( p->pNext==pVfs ){

       p->pNext = pVfs->pNext;

     }

   }

 }

 /*

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

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

 ** true.

 */

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

   sqlite3_mutex *mutex = 0;

 #ifndef SQLITE_OMIT_AUTOINIT

   int rc = sqlite3_initialize();

   if( rc ) return rc;

 #endif

   mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);

   sqlite3_mutex_enter(mutex);

   vfsUnlink(pVfs);

   if( makeDflt || vfsList==0 ){

     pVfs->pNext = vfsList;

     vfsList = pVfs;

   }else{

     pVfs->pNext = vfsList->pNext;

     vfsList->pNext = pVfs;

   }

   assert(vfsList);

   sqlite3_mutex_leave(mutex);

   return SQLITE_OK;

 }

 /*

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

 */

 SQLITE_EXPORT int sqlite3_vfs_unregister(sqlite3_vfs *pVfs){

 #ifndef SQLITE_MUTEX_NOOP

   sqlite3_mutex *mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MASTER);

 #endif

   sqlite3_mutex_enter(mutex);

   vfsUnlink(pVfs);

   sqlite3_mutex_leave(mutex);

   return SQLITE_OK;

 }