/*
** Lower the locking level on file descriptor id to locktype. locktype
** must be either NO_LOCK or SHARED_LOCK.
**
** If the locking level of the file descriptor is already at or below
** the requested locking level, this routine is a no-op.
**
** It is not possible for this routine to fail if the second argument
** is NO_LOCK. If the second argument is SHARED_LOCK then this routine
** might return SQLITE_IOERR;
*/
static int os2Unlock( sqlite3_file *id, int locktype ){
int type;
os2File *pFile = (os2File*)id;
APIRET rc = SQLITE_OK;
APIRET res = NO_ERROR;
FILELOCK LockArea,
UnlockArea;
memset(&LockArea, 0, sizeof(LockArea));
memset(&UnlockArea, 0, sizeof(UnlockArea));
assert( pFile!=0 );
assert( locktype<=SHARED_LOCK );
OSTRACE4( "UNLOCK %d to %d was %d\n", pFile->h, locktype, pFile->locktype );
type = pFile->locktype;
if( type>=EXCLUSIVE_LOCK ){
LockArea.lOffset = 0L;
LockArea.lRange = 0L;
UnlockArea.lOffset = SHARED_FIRST;
UnlockArea.lRange = SHARED_SIZE;
res = DosSetFileLocks( pFile->h, &UnlockArea, &LockArea, LOCK_TIMEOUT, 0L );
OSTRACE3( "UNLOCK %d exclusive lock res=%d\n", pFile->h, res );
if( locktype==SHARED_LOCK && getReadLock(pFile) != NO_ERROR ){
/* This should never happen. We should always be able to
** reacquire the read lock */
OSTRACE3( "UNLOCK %d to %d getReadLock() failed\n", pFile->h, locktype );
rc = SQLITE_IOERR_UNLOCK;
}
}
if( type>=RESERVED_LOCK ){
LockArea.lOffset = 0L;
LockArea.lRange = 0L;
UnlockArea.lOffset = RESERVED_BYTE;
UnlockArea.lRange = 1L;
res = DosSetFileLocks( pFile->h, &UnlockArea, &LockArea, LOCK_TIMEOUT, 0L );
OSTRACE3( "UNLOCK %d reserved res=%d\n", pFile->h, res );
}
if( locktype==NO_LOCK && type>=SHARED_LOCK ){
res = unlockReadLock(pFile);
OSTRACE5( "UNLOCK %d is %d want %d res=%d\n", pFile->h, type, locktype, res );
}
if( type>=PENDING_LOCK ){
LockArea.lOffset = 0L;
LockArea.lRange = 0L;
UnlockArea.lOffset = PENDING_BYTE;
UnlockArea.lRange = 1L;
res = DosSetFileLocks( pFile->h, &UnlockArea, &LockArea, LOCK_TIMEOUT, 0L );
OSTRACE3( "UNLOCK %d pending res=%d\n", pFile->h, res );
}
pFile->locktype = locktype;
OSTRACE3( "UNLOCK %d now %d\n", pFile->h, pFile->locktype );
return rc;
}
/*
** Lock the file with the lock specified by parameter locktype - one
** of the following:
**
** (1) SHARED_LOCK
** (2) RESERVED_LOCK
** (3) PENDING_LOCK
** (4) EXCLUSIVE_LOCK
**
** Sometimes when requesting one lock state, additional lock states
** are inserted in between. The locking might fail on one of the later
** transitions leaving the lock state different from what it started but
** still short of its goal. The following chart shows the allowed
** transitions and the inserted intermediate states:
**
** UNLOCKED -> SHARED
** SHARED -> RESERVED
** SHARED -> (PENDING) -> EXCLUSIVE
** RESERVED -> (PENDING) -> EXCLUSIVE
** PENDING -> EXCLUSIVE
**
** This routine will only increase a lock. The winUnlock() routine
** erases all locks at once and returns us immediately to locking level 0.
** It is not possible to lower the locking level one step at a time. You
** must go straight to locking level 0.
*/
int winLock(sqlite3_file *id, int locktype){
int rc = SQLITE_OK; /* Return code from subroutines */
int res = 1; /* Result of a windows lock call */
int newLocktype; /* Set pFile->locktype to this value before exiting */
int gotPendingLock = 0;/* True if we acquired a PENDING lock this time */
symbianFile *pFile = (symbianFile*)id;
assert( pFile!=0 );
OSTRACE5("LOCK %d %d was %d(%d)\n",
pFile->h, locktype, pFile->locktype, pFile->sharedLockByte);
// one smartphone only one application can control the database
TInt size = 0;
if (pFile->file.Size(size) == KErrNone) return SQLITE_OK;
return SQLITE_BUSY;
}
/*
** Seek to the offset in id->offset then read cnt bytes into pBuf.
** Return the number of bytes actually read. Update the offset.
*/
static int seekAndWrite(unixFile *id, i64 offset, const void *pBuf, int cnt){
int got;
i64 newOffset;
TIMER_START;
#if defined(USE_PREAD)
got = pwrite(id->h, pBuf, cnt, offset);
#elif defined(USE_PREAD64)
got = pwrite64(id->h, pBuf, cnt, offset);
#else
newOffset = lseek(id->h, offset, SEEK_SET);
if( newOffset!=offset ){
return -1;
}
got = write(id->h, pBuf, cnt);
#endif
TIMER_END;
OSTRACE5("WRITE %-3d %5d %7lld %llu\n", id->h, got, offset, TIMER_ELAPSED);
return got;
}
/*
** Seek to the offset passed as the second argument, then read cnt
** bytes into pBuf. Return the number of bytes actually read.
**
** NB: If you define USE_PREAD or USE_PREAD64, then it might also
** be necessary to define _XOPEN_SOURCE to be 500. This varies from
** one system to another. Since SQLite does not define USE_PREAD
** any any form by default, we will not attempt to define _XOPEN_SOURCE.
** See tickets #2741 and #2681.
*/
static int seekAndRead(unixFile *id, sqlite3_int64 offset, void *pBuf, int cnt){
int got;
i64 newOffset;
TIMER_START;
#if defined(USE_PREAD)
got = pread(id->h, pBuf, cnt, offset);
SimulateIOError( got = -1 );
#elif defined(USE_PREAD64)
got = pread64(id->h, pBuf, cnt, offset);
SimulateIOError( got = -1 );
#else
newOffset = lseek(id->h, offset, SEEK_SET);
SimulateIOError( newOffset-- );
if( newOffset!=offset ){
return -1;
}
got = read(id->h, pBuf, cnt);
#endif
TIMER_END;
OSTRACE5("READ %-3d %5d %7lld %llu\n", id->h, got, offset, TIMER_ELAPSED);
return got;
}
