This function maps an already open file into a caller-accessible buffer if the file is currently unmapped.

VOID NdisMapFile(
  PVOID* MappedBuffer,
  NDIS_HANDLE FileHandle


  • Status
    [out] Points to a caller-supplied variable in which this function returns the status of the mapping operation, which can be one of the following:

      The caller has exclusive access to the file contents until NdisUnmapFile is called.


      The caller cannot access the file contents at this time.

  • MappedBuffer
    [out] Points to a caller-supplied variable in which this function returns the base virtual address of the mapped file contents or NULL.
  • FileHandle
    [in] Specifies the handle returned by a preceding call to NdisOpenFile.

Return Values



NdisMapFile associates or maps a virtual address range with an opened file so the driver can access the file contents. NdisMapFile allows only one mapping of a particular file to be outstanding at any time. Consequently, a successful caller is given exclusive access to the file data until NdisUnmapFile or NdisCloseFile is called.

A NIC driver can map and unmap such an open file as necessary, using alternating calls to NdisMapFile and NdisUnmapFile. A call to NdisCloseFile releases the FileHandle and de-allocates the buffer containing the file contents.

A NIC driver can call NdisMapFile only during initialization.


OS Versions: Windows CE .NET 4.0 and later.
Header: Ndis.h.
Link Library: Ndis.dll.

See Also

NdisCloseFile | NdisOpenFile | NdisUnmapFile

 Last updated on Tuesday, May 18, 2004

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