IStream::UnlockRegion

Removes the access restriction on a range of bytes previously restricted with IStream::LockRegion.
HRESULT UnlockRegion(

ULARGE_INTEGER libOffset,	//Specifies the byte offset for the beginning of the range
ULARGE_INTEGER cb,	//Specifies the length of the range in bytes
DWORD dwLockType	//Specifies the access restriction previously placed on the range
);

Parameters
libOffset

[in]Specifies the byte offset for the beginning of the range.

[in]Specifies, in bytes, the length of the range to be restricted.

dwLockType

[in]Specifies the access restrictions previously placed on the range.

Return Values
S_OK

The byte range was unlocked.

STG_E_INVALIDFUNCTION

Locking is not supported at all or the specific type of lock requested is not supported.

STG_E_LOCKVIOLATION

The requested unlock cannot be granted.

Comments
This method unlocks a region previously locked with the IStream::LockRegion method. Locked regions must later be explicitly unlocked by calling IStream::UnlockRegion with exactly the same values for the libOffset, cb, and dwLockType parameters. The region must be unlocked before the stream is released. Two adjacent regions cannot be locked separately and then unlocked with a single unlock call.