<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>.
+ <function>sd_bus_add_match()</function> installs a match rule for incoming messages received on the specified bus
+ connection object <parameter>bus</parameter>. The syntax of the match rule expression passed in
+ <parameter>match</parameter> is described in the <ulink
+ url="https://dbus.freedesktop.org/doc/dbus-specification.html">D-Bus Specification</ulink>. The specified handler
+ function <parameter>callback</parameter> is called for eaching incoming message matching the specified
+ expression, the <parameter>userdata</parameter> parameter is passed as-is to the callback function.
</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.
+ On success, and if non-<constant>NULL</constant>, the <parameter>slot</parameter> return parameter will be set to
+ a slot object that may be used as a reference to the installed match, and may be utilized to remove it again at a
+ later time with
+ <citerefentry><refentrytitle>sd_bus_slot_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>. If
+ specified as <constant>NULL</constant> the lifetime of the match is bound to the lifetime of the bus object itself, and the match
+ cannot be removed independently.
</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
+ 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>
<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.
+ 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>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>
</para>
</refsect1>