the #GAsyncResult that was provided to the callback.
a #gsize to get the length of the data read in.
a string with the data that was read before encountering any of the stop characters. Set @length to a #gsize to get the length of the string. This function will return %NULL on an error.
GException on failure.
2.20
Finish an asynchronous call started by g_data_input_stream_read_until_async().