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UnlockFileEx function

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.

Windows Phone 8: This API is supported.

Windows Phone 8.1: This API is supported.

In Windows 8 and Windows Server 2012, this function is supported by the following technologies.

TechnologySupported

Server Message Block (SMB) 3.0 protocol

Yes

SMB 3.0 Transparent Failover (TFO)

Yes

SMB 3.0 with Scale-out File Shares (SO)

Yes

Cluster Shared Volume File System (CsvFS)

Yes

Resilient File System (ReFS)

Yes

 

Requirements

Minimum supported client

Windows XP [desktop apps | Windows Store apps]

Minimum supported server

Windows Server 2003 [desktop apps | Windows Store apps]

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

See also

CreateFile
File Management Functions
LockFile
LockFileEx
OVERLAPPED
Synchronous and Asynchronous I/O
UnlockFile

 

 

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