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<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
<refentry id="sd_bus_message_get_signature" xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>sd_bus_message_get_signature</title>
<productname>systemd</productname>
</refentryinfo>
<refmeta>
<refentrytitle>sd_bus_message_get_signature</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>sd_bus_message_get_signature</refname>
<refname>sd_bus_message_is_empty</refname>
<refname>sd_bus_message_has_signature</refname>
<refpurpose>Query bus message signature</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>
<funcprototype>
<funcdef>const char* <function>sd_bus_message_get_signature</function></funcdef>
<paramdef>sd_bus_message *<parameter>message</parameter></paramdef>
<paramdef>int <parameter>complete</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_message_is_empty</function></funcdef>
<paramdef>sd_bus_message *<parameter>message</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_message_has_signature</function></funcdef>
<paramdef>sd_bus_message *<parameter>message</parameter></paramdef>
<paramdef>const char *<parameter>signature</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><function>sd_bus_message_get_signature()</function> returns the signature of message
<parameter>message</parameter>. If <parameter>complete</parameter> is true, the signature of the
whole message is returned, and just the signature of the currently open container otherwise.
</para>
<para><function>sd_bus_message_is_empty()</function> returns true if the message is empty,
i.e. when its signature is empty.</para>
<para><function>sd_bus_message_has_signature()</function> returns true if the signature of the
message <parameter>message</parameter> matches given <parameter>signature</parameter>. Parameter
<parameter>signature</parameter> may be <constant>NULL</constant>, this is treated the same as
an empty string, which is equivalent to calling <function>sd_bus_message_is_empty()</function>.
</para>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>On success, <function>sd_bus_message_get_signature()</function> returns
the signature, and <constant>NULL</constant> on error.</para>
<para>The other functions return 0 or a positive integer on success. On failure, they return a
negative errno-style error code.</para>
<refsect2>
<title>Errors</title>
<para>Returned errors may indicate the following problems:</para>
<variablelist>
<varlistentry>
<term><constant>-EINVAL</constant></term>
<listitem><para>The <parameter>message</parameter> parameter is <constant>NULL</constant>.
</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>NULL</constant></term>
<listitem><para>The <parameter>message</parameter> parameter is <constant>NULL</constant>.
</para></listitem>
</varlistentry>
</variablelist>
</refsect2>
</refsect1>
<xi:include href="libsystemd-pkgconfig.xml" />
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_message_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>
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