So, when I use g_cancellable_cancel () on the GCancellable that gets provided through 
  gdata_picasaweb_service_upload_file () 
to 
  gdata_output_stream_splice (), 
the returned response_body from 
  gdata_upload_stream_get_response () 
ends up being NULL, and my programme crashes. 


Here's the culprit code:

GDataPicasaWebFile *
gdata_picasaweb_service_upload_file (..., GCancellable cancellable, ...) {
        ...

        g_output_stream_splice (output_stream, input_stream, G_OUTPUT_STREAM_SPLICE_CLOSE_SOURCE | G_OUTPUT_STREAM_SPLICE_CLOSE_TARGET,
                                cancellable, error);
        ...
        /* Get the response from the server */
        response_body = gdata_upload_stream_get_response (GDATA_UPLOAD_STREAM (output_stream), &response_length);
        g_assert (response_body != NULL && response_length > 0);
        ...
}




Here's a partial stack trace from the code I was writing:

+ Trace 219125