NTSTATUS
NtReadRequestData(
  IN  HANDLE PortHandle,
  IN  PPORT_MESSAGE Message,
  IN  ULONG DataEntryIndex,
  OUT PVOID Buffer,
  IN  ULONG BufferSize,
  OUT PULONG NumberOfBytesRead OPTIONAL
  );

Routine Description:

    This routine is used to copy data from a port message into the user
    supplied buffer.

Arguments:

    PortHandle - Supplies the port from which the message is being read

    Message - Supplies the message that we are trying to read

    DataEntryIndex - Supplies the index of the port data entry in the
        preceeding message that we are reading

    Buffer - Supplies the location into which the data is to be read

    BufferSize - Supplies the size, in bytes, of the preceeding buffer

    NumberOfBytesRead - Optionally returns the number of bytes read into
        the buffer

Return Value:

    NTSTATUS - An appropriate status value