LockFile
The LockFile
function locks a region in an open file. Locking a region prevents other
processes from accessing the region.
BOOL LockFile(
|
HANDLE hFile, |
// handle of file
to lock |
|
DWORD dwFileOffsetLow, |
// low-order word
of lock region offset |
|
DWORD dwFileOffsetHigh, |
// high-order word
of lock region offset |
|
DWORD nNumberOfBytesToLockLow, |
// low-order word
of length to lock |
|
DWORD nNumberOfBytesToLockHigh |
// high-order word
of length to lock |
|
); |
|
Parameters
hFile
Identifies
the file with a region to be locked. The file handle must have been created
with GENERIC_READ or GENERIC_WRITE access to the file (or both).
dwFileOffsetLow
Specifies the
low-order word of the starting byte offset in the file where the lock should
begin.
dwFileOffsetHigh
Specifies the
high-order word of the starting byte offset in the file where the lock should
begin.
nNumberOfBytesToLockLow
Specifies the
low-order word of the length of the byte range to be locked.
nNumberOfBytesToLockHigh
Specifies the
high-order word of the length of the byte range to be locked.
Return Values
If the
function succeeds, the return value is nonzero.
If the
function fails, the return value is zero. To get extended error information,
call GetLastError.
Remarks
Locking a
region of a file gives the locking process exclusive access to the specified
region. File locks are not inherited by processes created by the locking
process.
Locking a
region of a file denies all other processes both read and write access to the
specified region. Locking a region that goes beyond the current end-of-file
position is not an error.
Locks may not
overlap an existing locked region of the file.
The UnlockFile
function unlocks a file region locked by LockFile.
See Also