os.c

sqlite数据库源码

  int rc;
  id->dirfd = -1;
  id->fd = open(zFilename, O_RDWR|O_CREAT|O_LARGEFILE|O_BINARY, 0644);
  if( id->fd<0 ){
#ifdef EISDIR
    if( errno==EISDIR ){
      return SQLITE_CANTOPEN;
    }
#endif
    id->fd = open(zFilename, O_RDONLY|O_LARGEFILE|O_BINARY);
    if( id->fd<0 ){
      return SQLITE_CANTOPEN; 
    }
    *pReadonly = 1;
  }else{
    *pReadonly = 0;
  }
  sqliteOsEnterMutex();
  rc = findLockInfo(id->fd, &id->pLock, &id->pOpen);
  sqliteOsLeaveMutex();
  if( rc ){
    close(id->fd);
    return SQLITE_NOMEM;
  }
  id->locked = 0;
  TRACE3("OPEN    %-3d %s\n", id->fd, zFilename);
  OpenCounter(+1);
  return SQLITE_OK;
#endif
#if OS_WIN
  HANDLE h = CreateFile(zFilename,
     GENERIC_READ | GENERIC_WRITE,
     FILE_SHARE_READ | FILE_SHARE_WRITE,
     NULL,
     OPEN_ALWAYS,
     FILE_ATTRIBUTE_NORMAL | FILE_FLAG_RANDOM_ACCESS,
     NULL
  );
  if( h==INVALID_HANDLE_VALUE ){
    h = CreateFile(zFilename,
       GENERIC_READ,
       FILE_SHARE_READ,
       NULL,
       OPEN_ALWAYS,
       FILE_ATTRIBUTE_NORMAL | FILE_FLAG_RANDOM_ACCESS,
       NULL
    );
    if( h==INVALID_HANDLE_VALUE ){
      return SQLITE_CANTOPEN;
    }
    *pReadonly = 1;
  }else{
    *pReadonly = 0;
  }
  id->h = h;
  id->locked = 0;
  OpenCounter(+1);
  return SQLITE_OK;
#endif
#if OS_MAC
  FSSpec fsSpec;
# ifdef _LARGE_FILE
  HFSUniStr255 dfName;
  FSRef fsRef;
  if( __path2fss(zFilename, &fsSpec) != noErr ){
    if( HCreate(fsSpec.vRefNum, fsSpec.parID, fsSpec.name, 'SQLI', cDocumentFile) != noErr )
      return SQLITE_CANTOPEN;
  }
  if( FSpMakeFSRef(&fsSpec, &fsRef) != noErr )
    return SQLITE_CANTOPEN;
  FSGetDataForkName(&dfName);
  if( FSOpenFork(&fsRef, dfName.length, dfName.unicode,
                 fsRdWrShPerm, &(id->refNum)) != noErr ){
    if( FSOpenFork(&fsRef, dfName.length, dfName.unicode,
                   fsRdWrPerm, &(id->refNum)) != noErr ){
      if (FSOpenFork(&fsRef, dfName.length, dfName.unicode,
                   fsRdPerm, &(id->refNum)) != noErr )
        return SQLITE_CANTOPEN;
      else
        *pReadonly = 1;
    } else
      *pReadonly = 0;
  } else
    *pReadonly = 0;
# else
  __path2fss(zFilename, &fsSpec);
  if( !sqliteOsFileExists(zFilename) ){
    if( HCreate(fsSpec.vRefNum, fsSpec.parID, fsSpec.name, 'SQLI', cDocumentFile) != noErr )
      return SQLITE_CANTOPEN;
  }
  if( HOpenDF(fsSpec.vRefNum, fsSpec.parID, fsSpec.name, fsRdWrShPerm, &(id->refNum)) != noErr ){
    if( HOpenDF(fsSpec.vRefNum, fsSpec.parID, fsSpec.name, fsRdWrPerm, &(id->refNum)) != noErr ){
      if( HOpenDF(fsSpec.vRefNum, fsSpec.parID, fsSpec.name, fsRdPerm, &(id->refNum)) != noErr )
        return SQLITE_CANTOPEN;
      else
        *pReadonly = 1;
    } else
      *pReadonly = 0;
  } else
    *pReadonly = 0;
# endif
  if( HOpenRF(fsSpec.vRefNum, fsSpec.parID, fsSpec.name, fsRdWrShPerm, &(id->refNumRF)) != noErr){
    id->refNumRF = -1;
  }
  id->locked = 0;
  id->delOnClose = 0;
  OpenCounter(+1);
  return SQLITE_OK;
#endif
}


/*
** Attempt to open a new file for exclusive access by this process.
** The file will be opened for both reading and writing.  To avoid
** a potential security problem, we do not allow the file to have
** previously existed.  Nor do we allow the file to be a symbolic
** link.
**
** If delFlag is true, then make arrangements to automatically delete
** the file when it is closed.
**
** On success, write the file handle into *id and return SQLITE_OK.
**
** On failure, return SQLITE_CANTOPEN.
*/
int sqliteOsOpenExclusive(const char *zFilename, OsFile *id, int delFlag){
#if OS_UNIX
  int rc;
  if( access(zFilename, 0)==0 ){
    return SQLITE_CANTOPEN;
  }
  id->dirfd = -1;
  id->fd = open(zFilename,
                O_RDWR|O_CREAT|O_EXCL|O_NOFOLLOW|O_LARGEFILE|O_BINARY, 0600);
  if( id->fd<0 ){
    return SQLITE_CANTOPEN;
  }
  sqliteOsEnterMutex();
  rc = findLockInfo(id->fd, &id->pLock, &id->pOpen);
  sqliteOsLeaveMutex();
  if( rc ){
    close(id->fd);
    unlink(zFilename);
    return SQLITE_NOMEM;
  }
  id->locked = 0;
  if( delFlag ){
    unlink(zFilename);
  }
  TRACE3("OPEN-EX %-3d %s\n", id->fd, zFilename);
  OpenCounter(+1);
  return SQLITE_OK;
#endif
#if OS_WIN
  HANDLE h;
  int fileflags;
  if( delFlag ){
    fileflags = FILE_ATTRIBUTE_TEMPORARY | FILE_FLAG_RANDOM_ACCESS 
                     | FILE_FLAG_DELETE_ON_CLOSE;
  }else{
    fileflags = FILE_FLAG_RANDOM_ACCESS;
  }
  h = CreateFile(zFilename,
     GENERIC_READ | GENERIC_WRITE,
     0,
     NULL,
     CREATE_ALWAYS,
     fileflags,
     NULL
  );
  if( h==INVALID_HANDLE_VALUE ){
    return SQLITE_CANTOPEN;
  }
  id->h = h;
  id->locked = 0;
  OpenCounter(+1);
  return SQLITE_OK;
#endif
#if OS_MAC
  FSSpec fsSpec;
# ifdef _LARGE_FILE
  HFSUniStr255 dfName;
  FSRef fsRef;
  __path2fss(zFilename, &fsSpec);
  if( HCreate(fsSpec.vRefNum, fsSpec.parID, fsSpec.name, 'SQLI', cDocumentFile) != noErr )
    return SQLITE_CANTOPEN;
  if( FSpMakeFSRef(&fsSpec, &fsRef) != noErr )
    return SQLITE_CANTOPEN;
  FSGetDataForkName(&dfName);
  if( FSOpenFork(&fsRef, dfName.length, dfName.unicode,
                 fsRdWrPerm, &(id->refNum)) != noErr )
    return SQLITE_CANTOPEN;
# else
  __path2fss(zFilename, &fsSpec);
  if( HCreate(fsSpec.vRefNum, fsSpec.parID, fsSpec.name, 'SQLI', cDocumentFile) != noErr )
    return SQLITE_CANTOPEN;
  if( HOpenDF(fsSpec.vRefNum, fsSpec.parID, fsSpec.name, fsRdWrPerm, &(id->refNum)) != noErr )
    return SQLITE_CANTOPEN;
# endif
  id->refNumRF = -1;
  id->locked = 0;
  id->delOnClose = delFlag;
  if (delFlag)
    id->pathToDel = sqliteOsFullPathname(zFilename);
  OpenCounter(+1);
  return SQLITE_OK;
#endif
}

/*
** Attempt to open a new file for read-only access.
**
** On success, write the file handle into *id and return SQLITE_OK.
**
** On failure, return SQLITE_CANTOPEN.
*/
int sqliteOsOpenReadOnly(const char *zFilename, OsFile *id){
#if OS_UNIX
  int rc;
  id->dirfd = -1;
  id->fd = open(zFilename, O_RDONLY|O_LARGEFILE|O_BINARY);
  if( id->fd<0 ){
    return SQLITE_CANTOPEN;
  }
  sqliteOsEnterMutex();
  rc = findLockInfo(id->fd, &id->pLock, &id->pOpen);
  sqliteOsLeaveMutex();
  if( rc ){
    close(id->fd);
    return SQLITE_NOMEM;
  }
  id->locked = 0;
  TRACE3("OPEN-RO %-3d %s\n", id->fd, zFilename);
  OpenCounter(+1);
  return SQLITE_OK;
#endif
#if OS_WIN
  HANDLE h = CreateFile(zFilename,
     GENERIC_READ,
     0,
     NULL,
     OPEN_EXISTING,
     FILE_ATTRIBUTE_NORMAL | FILE_FLAG_RANDOM_ACCESS,
     NULL
  );
  if( h==INVALID_HANDLE_VALUE ){
    return SQLITE_CANTOPEN;
  }
  id->h = h;
  id->locked = 0;
  OpenCounter(+1);
  return SQLITE_OK;
#endif
#if OS_MAC
  FSSpec fsSpec;
# ifdef _LARGE_FILE
  HFSUniStr255 dfName;
  FSRef fsRef;
  if( __path2fss(zFilename, &fsSpec) != noErr )
    return SQLITE_CANTOPEN;
  if( FSpMakeFSRef(&fsSpec, &fsRef) != noErr )
    return SQLITE_CANTOPEN;
  FSGetDataForkName(&dfName);
  if( FSOpenFork(&fsRef, dfName.length, dfName.unicode,
                 fsRdPerm, &(id->refNum)) != noErr )
    return SQLITE_CANTOPEN;
# else
  __path2fss(zFilename, &fsSpec);
  if( HOpenDF(fsSpec.vRefNum, fsSpec.parID, fsSpec.name, fsRdPerm, &(id->refNum)) != noErr )
    return SQLITE_CANTOPEN;
# endif
  if( HOpenRF(fsSpec.vRefNum, fsSpec.parID, fsSpec.name, fsRdWrShPerm, &(id->refNumRF)) != noErr){
    id->refNumRF = -1;
  }
  id->locked = 0;
  id->delOnClose = 0;
  OpenCounter(+1);
  return SQLITE_OK;
#endif
}

/*
** Attempt to open a file descriptor for the directory that contains a
** file.  This file descriptor can be used to fsync() the directory
** in order to make sure the creation of a new file is actually written
** to disk.
**
** This routine is only meaningful for Unix.  It is a no-op under
** windows since windows does not support hard links.
**
** On success, a handle for a previously open file is at *id is
** updated with the new directory file descriptor and SQLITE_OK is
** returned.
**
** On failure, the function returns SQLITE_CANTOPEN and leaves
** *id unchanged.
*/
int sqliteOsOpenDirectory(
  const char *zDirname,
  OsFile *id
){
#if OS_UNIX
  if( id->fd<0 ){
    /* Do not open the directory if the corresponding file is not already
    ** open. */
    return SQLITE_CANTOPEN;
  }
  assert( id->dirfd<0 );
  id->dirfd = open(zDirname, O_RDONLY|O_BINARY, 0644);
  if( id->dirfd<0 ){
    return SQLITE_CANTOPEN; 
  }
  TRACE3("OPENDIR %-3d %s\n", id->dirfd, zDirname);
#endif
  return SQLITE_OK;
}

/*
** If the following global variable points to a string which is the
** name of a directory, then that directory will be used to store
** temporary files.
*/
const char *sqlite_temp_directory = 0;

/*
** Create a temporary file name in zBuf.  zBuf must be big enough to
** hold at least SQLITE_TEMPNAME_SIZE characters.
*/
int sqliteOsTempFileName(char *zBuf){
#if OS_UNIX
  static const char *azDirs[] = {
     0,
     "/var/tmp",
     "/usr/tmp",
     "/tmp",
     ".",
  };
  static unsigned char zChars[] =
    "abcdefghijklmnopqrstuvwxyz"
    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    "0123456789";
  int i, j;
  struct stat buf;
  const char *zDir = ".";
  azDirs[0] = sqlite_temp_directory;
  for(i=0; i<sizeof(azDirs)/sizeof(azDirs[0]); i++){
    if( azDirs[i]==0 ) continue;
    if( stat(azDirs[i], &buf) ) continue;
    if( !S_ISDIR(buf.st_mode) ) continue;
    if( access(azDirs[i], 07) ) continue;
    zDir = azDirs[i];
    break;
  }
  do{
    sprintf(zBuf, "%s/"TEMP_FILE_PREFIX, zDir);
    j = strlen(zBuf);
    sqliteRandomness(15, &zBuf[j]);
    for(i=0; i<15; i++, j++){
      zBuf[j] = (char)zChars[ ((unsigned char)zBuf[j])%(sizeof(zChars)-1) ];
    }
    zBuf[j] = 0;
  }while( access(zBuf,0)==0 );
#endif
#if OS_WIN
  static char zChars[] =
    "abcdefghijklmnopqrstuvwxyz"
    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    "0123456789";
  int i, j;
  const char *zDir;
  char zTempPath[SQLITE_TEMPNAME_SIZE];
  if( sqlite_temp_directory==0 ){
    GetTempPath(SQLITE_TEMPNAME_SIZE-30, zTempPath);
    for(i=strlen(zTempPath); i>0 && zTempPath[i-1]=='\\'; i--){}
    zTempPath[i] = 0;
    zDir = zTempPath;
  }else{
    zDir = sqlite_temp_directory;
  }
  for(;;){
    sprintf(zBuf, "%s\\"TEMP_FILE_PREFIX, zDir);
    j = strlen(zBuf);
    sqliteRandomness(15, &zBuf[j]);
    for(i=0; i<15; i++, j++){
      zBuf[j] = (char)zChars[ ((unsigned char)zBuf[j])%(sizeof(zChars)-1) ];
    }
    zBuf[j] = 0;
    if( !sqliteOsFileExists(zBuf) ) break;
  }
#endif
#if OS_MAC
  static char zChars[] =
    "abcdefghijklmnopqrstuvwxyz"
    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    "0123456789";
  int i, j;
  char *zDir;
  char zTempPath[SQLITE_TEMPNAME_SIZE];
  char zdirName[32];
  CInfoPBRec infoRec;
  Str31 dirName;
  memset(&infoRec, 0, sizeof(infoRec));
  memset(zTempPath, 0, SQLITE_TEMPNAME_SIZE);
  if( sqlite_temp_directory!=0 ){
    zDir = sqlite_temp_directory;
  }else if( FindFolder(kOnSystemDisk, kTemporaryFolderType,  kCreateFolder,
       &(infoRec.dirInfo.ioVRefNum), &(infoRec.dirInfo.ioDrParID)) == noErr ){
    infoRec.dirInfo.ioNamePtr = dirName;
    do{
      infoRec.dirInfo.ioFDirIndex = -1;
      infoRec.dirInfo.ioDrDirID = infoRec.dirInfo.ioDrParID;
      if( PBGetCatInfoSync(&infoRec) == noErr ){
        CopyPascalStringToC(dirName, zdirName);
        i = strlen(zdirName);
        memmove(&(zTempPath[i+1]), zTempPath, strlen(zTempPath));
        strcpy(zTempPath, zdirName);
        zTempPath[i] = ':';
      }else{
        *zTempPath = 0;
        break;
      }
    } while( infoRec.dirInfo.ioDrDirID != fsRtDirID );
    zDir = zTempPath;
  }
  if( zDir[0]==0 ){
    getcwd(zTempPath, SQLITE_TEMPNAME_SIZE-24);
    zDir = zTempPath;
  }
  for(;;){
    sprintf(zBuf, "%s"TEMP_FILE_PREFIX, zDir);
    j = strlen(zBuf);
    sqliteRandomness(15, &zBuf[j]);
    for(i=0; i<15; i++, j++){
      zBuf[j] = (char)zChars[ ((unsigned char)zBuf[j])%(sizeof(zChars)-1) ];
    }
    zBuf[j] = 0;
    if( !sqliteOsFileExists(zBuf) ) break;
  }
#endif
  return SQLITE_OK; 
}

/*
** Close a file.
*/
int sqliteOsClose(OsFile *id){
#if OS_UNIX
  sqliteOsUnlock(id);
  if( id->dirfd>=0 ) close(id->dirfd);
  id->dirfd = -1;
  sqliteOsEnterMutex();
  if( id->pOpen->nLock ){
    /* If there are outstanding locks, do not actually close the file just
    ** yet because that would clear those locks.  Instead, add the file
    ** descriptor to pOpen->aPending.  It will be automatically closed when
    ** the last lock is cleared.
    */
    int *aNew;
    struct openCnt *pOpen = id->pOpen;
    pOpen->nPending++;
    aNew = sqliteRealloc( pOpen->aPending, pOpen->nPending*sizeof(int) );