UnmapViewOfFile

The UnmapViewOfFile function unmaps a previously mapped view of a file from the caller's virtual address space.

Syntax

BOOL UnmapViewOfFile(
  _In_ PVOID BaseAddress
);
            

Parameters

Return value

If the function succeeds, the return value is TRUE.

If the function fails, the return value is FALSE. To get extended error information, call GetLastError.

Remarks

Calling UnmapViewOfFile frees the virtual address space that was previously committed for the specified file mapping. The underlying physical pages are not affected until the file mapping object itself is deleted by closing its handle.

If you have mapped a view of a file multiple times using MapViewOfFile, MapViewOfFileEx, or MapViewOfFileNuma, you must call UnmapViewOfFile once for each successful call to these mapping functions.

It is an error to unmap a view of a file that has been modified and not yet written to disk. Ensure all changes are flushed to the file before unmapping the view, or use FlushViewOfFile if necessary.

Requirements

See also

• CreateFileMapping
• FlushViewOfFile
• MapViewOfFile
• MapViewOfFileEx
• MapViewOfFileNuma
• VirtualAlloc
• VirtualFree