UnlockFileEx
The UnlockFileEx
function unlocks a previously locked byte range in an open file.
BOOL UnlockFileEx(
|
HANDLE hFile, |
// handle of file
to unlock |
|
DWORD dwReserved, |
// reserved, must
be set to zero |
|
DWORD nNumberOfBytesToUnlockLow, |
// low order
32-bits of length to unlock |
|
DWORD nNumberOfBytesToUnlockHigh, |
// high order
32-bits of length to unlock |
|
LPOVERLAPPED lpOverlapped |
// addr. of struct.
with unlock region start offset |
|
); |
|
Parameters
hFile
Identifies an
open handle to a file that is to have an existing locked region unlocked. The
handle must have been created with either GENERIC_READ or GENERIC_WRITE access
to the file.
dwReserved
Reserved
parameter; must be zero.
nNumberOfBytesToUnlockLow
Specifies the
low-order 32-bits of the length of the byte range to unlock.
nNumberOfBytesToUnlockHigh
Specifies the
high-order 32-bits of the length of the byte range to unlock.
lpOverlapped
Points to an OVERLAPPED structure that the
function uses with the unlocking request. This structure contains the file
offset of the beginning of the unlock range.
Return Values
If the
function succeeds, the return value is nonzero.
If the
function fails, the return value is zero or NULL. To get extended error
information, call GetLastError.
Remarks
Unlocking a
region of a file releases a previously acquired lock on a file. The region to
unlock must correspond exactly to an existing locked region. Two adjacent
regions of a file can not be locked separately and then unlocked using a single
region that spans both locked regions.
If a process
terminates with a portion of a file locked or closes a file that has
outstanding locks, the behavior is not specified.
See Also