Retrieve the size of the buffer needed by calling the method
		with a null pointer and length of zero. This should trigger an
		insufficient buffer error and return the size needed for the
		buffer.

def __get_table_size(self):
		"""
		Retrieve the size of the buffer needed by calling the method
		with a null pointer and length of zero. This should trigger an
		insufficient buffer error and return the size needed for the
		buffer.
		"""
		length = ctypes.wintypes.DWORD()
		res = self.method(None, length, False)
		if res != errors.ERROR_INSUFFICIENT_BUFFER:
			raise RuntimeError("Error getting table length (%d)" % res)
		return length.value