LockFile

Overview

Group

Quick Info

Windows NT
Yes
Win95
Yes
Win32s
Yes
Import Library
kernel32.lib
Header File
winbase.h
Unicode
No
Platform Notes
None

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.