g_part_parm_str
error = g_part_parm_str(req, ap->name,
error = g_part_parm_str(req, ap->name, &gpp.gpp_flags);
error = g_part_parm_str(req, ap->name, &gpp.gpp_label);
error = g_part_parm_str(req, ap->name, &gpp.gpp_type);