postdata = g_strdup_printf("{\"protocolVersion\":\"0.8\",\"createSessionRequest\":{\"fields\":[{\"external\":{\"name\":\"file\",\"filename\":\"%s\",\"put\":{},\"size\":%" G_GSIZE_FORMAT "}},{\"inlined\":{\"name\":\"client\",\"content\":\"hangouts\",\"contentType\":\"text/plain\"}}]}}", filename, (gsize) purple_image_get_data_size(image));