<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*--> <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> <!-- This file is part of systemd. Copyright 2016 Julian Orth systemd is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. systemd is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with systemd; If not, see <http://www.gnu.org/licenses/>. --> <refentry id="sd_bus_add_match"> <refentryinfo> <title>sd_bus_add_match</title> <productname>systemd</productname> <authorgroup> <author> <firstname>Julian</firstname> <surname>Orth</surname> <email>ju.orth@gmail.com</email> </author> </authorgroup> </refentryinfo> <refmeta> <refentrytitle>sd_bus_add_match</refentrytitle> <manvolnum>3</manvolnum> </refmeta> <refnamediv> <refname>sd_bus_add_match</refname> <refpurpose>Add a match rule for message dispatching</refpurpose> </refnamediv> <refsynopsisdiv> <funcsynopsis> <funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo> <funcprototype> <funcdef>int <function>sd_bus_add_match</function></funcdef> <paramdef>sd_bus *<parameter>bus</parameter></paramdef> <paramdef>sd_bus_slot **<parameter>slot</parameter></paramdef> <paramdef>const char *<parameter>match</parameter></paramdef> <paramdef>sd_bus_message_handler_t <parameter>callback</parameter></paramdef> <paramdef>void *<parameter>userdata</parameter></paramdef> </funcprototype> <funcprototype> <funcdef>typedef int (*<function>sd_bus_message_handler_t</function>)</funcdef> <paramdef>sd_bus_message *<parameter>m</parameter></paramdef> <paramdef>void *<parameter>userdata</parameter></paramdef> <paramdef>sd_bus_error *<parameter>ret_error</parameter></paramdef> </funcprototype> </funcsynopsis> </refsynopsisdiv> <refsect1> <title>Description</title> <para> <function>sd_bus_add_match()</function> adds a match rule used to dispatch incoming messages. The syntax of the rule passed in <parameter>match</parameter> is described in the <ulink url="https://dbus.freedesktop.org/doc/dbus-specification.html">D-Bus Specification</ulink>. </para> <para> The message <parameter>m</parameter> passed to the callback is only borrowed, that is, the callback should not call <citerefentry><refentrytitle>sd_bus_message_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry> on it. If the callback wants to hold on to the message beyond the lifetime of the callback, it needs to call <citerefentry><refentrytitle>sd_bus_message_ref</refentrytitle><manvolnum>3</manvolnum></citerefentry> to create a new reference. </para> <para> If an error occurs during the callback invocation, the callback should return a negative error number. If it wants other callbacks that match the same rule to be called, it should return 0. Otherwise it should return a positive integer. </para> </refsect1> <refsect1> <title>Return Value</title> <para> On success, <function>sd_bus_add_match()</function> returns 0 or a positive integer. On failure, it returns a negative errno-style error code. </para> </refsect1> <refsect1> <title>See Also</title> <para> <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>, </para> </refsect1> </refentry>