UnlockFileEx function (Windows)

Switch View :

Classic

Lightweight

ScriptFree

Site Feedback

UnlockFileEx function

Applies to: desktop apps | Metro style apps

Unlocks a region in the specified file. This function can operate either synchronously or asynchronously.

Syntax

BOOL WINAPI UnlockFileEx(
  __in        HANDLE hFile,
  __reserved  DWORD dwReserved,
  __in        DWORD nNumberOfBytesToUnlockLow,
  __in        DWORD nNumberOfBytesToUnlockHigh,
  __inout     LPOVERLAPPED lpOverlapped
);

Parameters

hFile [in]: A handle to the file. The handle must have been created with either the GENERIC_READ or GENERIC_WRITE access right. For more information, see File Security and Access Rights.
dwReserved: Reserved parameter; must be zero.
nNumberOfBytesToUnlockLow [in]: The low-order part of the length of the byte range to unlock.
nNumberOfBytesToUnlockHigh [in]: The high-order part of the length of the byte range to unlock.
lpOverlapped [in, out]: A pointer 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. You must initialize the hEvent member to a valid handle or zero. For more information, see Synchronous and Asynchronous I/O.

Return value

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 the file. The region to unlock must correspond exactly to an existing locked region. Two adjacent regions of a file cannot be locked separately and then unlocked using a single region that spans both locked regions.

Locks are released before the CloseHandle function is finished processing.

Requirements

Minimum supported client	Windows XP
Minimum supported server	Windows Server 2003
Header	FileAPI.h (include Windows.h); WinBase.h on Windows Server 2008 R2, Windows 7, Windows Server 2008, Windows Vista, Windows Server 2003, and Windows XP (include Windows.h)
Library	Kernel32.lib
DLL	Kernel32.dll