1<?xml version='1.0'?> <!--*-nxml-*--> 2<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" 3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> 4<!-- SPDX-License-Identifier: LGPL-2.1-or-later --> 5 6<refentry id="sd_bus_message_get_signature" xmlns:xi="http://www.w3.org/2001/XInclude"> 7 <refentryinfo> 8 <title>sd_bus_message_get_signature</title> 9 <productname>systemd</productname> 10 </refentryinfo> 11 12 <refmeta> 13 <refentrytitle>sd_bus_message_get_signature</refentrytitle> 14 <manvolnum>3</manvolnum> 15 </refmeta> 16 17 <refnamediv> 18 <refname>sd_bus_message_get_signature</refname> 19 <refname>sd_bus_message_is_empty</refname> 20 <refname>sd_bus_message_has_signature</refname> 21 22 <refpurpose>Query bus message signature</refpurpose> 23 </refnamediv> 24 25 <refsynopsisdiv> 26 <funcsynopsis> 27 <funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo> 28 29 <funcprototype> 30 <funcdef>const char* <function>sd_bus_message_get_signature</function></funcdef> 31 <paramdef>sd_bus_message *<parameter>message</parameter></paramdef> 32 <paramdef>int <parameter>complete</parameter></paramdef> 33 </funcprototype> 34 35 <funcprototype> 36 <funcdef>int <function>sd_bus_message_is_empty</function></funcdef> 37 <paramdef>sd_bus_message *<parameter>message</parameter></paramdef> 38 </funcprototype> 39 40 <funcprototype> 41 <funcdef>int <function>sd_bus_message_has_signature</function></funcdef> 42 <paramdef>sd_bus_message *<parameter>message</parameter></paramdef> 43 <paramdef>const char *<parameter>signature</parameter></paramdef> 44 </funcprototype> 45 </funcsynopsis> 46 47 </refsynopsisdiv> 48 49 <refsect1> 50 <title>Description</title> 51 52 <para><function>sd_bus_message_get_signature()</function> returns the signature of message 53 <parameter>message</parameter>. If <parameter>complete</parameter> is true, the signature of the 54 whole message is returned, and just the signature of the currently open container otherwise. 55 </para> 56 57 <para><function>sd_bus_message_is_empty()</function> returns true if the message is empty, 58 i.e. when its signature is empty.</para> 59 60 <para><function>sd_bus_message_has_signature()</function> returns true if the signature of the 61 message <parameter>message</parameter> matches given <parameter>signature</parameter>. Parameter 62 <parameter>signature</parameter> may be <constant>NULL</constant>, this is treated the same as 63 an empty string, which is equivalent to calling <function>sd_bus_message_is_empty()</function>. 64 </para> 65</refsect1> 66 67 <refsect1> 68 <title>Return Value</title> 69 70 <para>On success, <function>sd_bus_message_get_signature()</function> returns 71 the signature, and <constant>NULL</constant> on error.</para> 72 73 <para>The other functions return 0 or a positive integer on success. On failure, they return a 74 negative errno-style error code.</para> 75 76 <refsect2> 77 <title>Errors</title> 78 79 <para>Returned errors may indicate the following problems:</para> 80 81 <variablelist> 82 <varlistentry> 83 <term><constant>-EINVAL</constant></term> 84 85 <listitem><para>The <parameter>message</parameter> parameter is <constant>NULL</constant>. 86 </para></listitem> 87 </varlistentry> 88 89 <varlistentry> 90 <term><constant>NULL</constant></term> 91 92 <listitem><para>The <parameter>message</parameter> parameter is <constant>NULL</constant>. 93 </para></listitem> 94 </varlistentry> 95 </variablelist> 96 </refsect2> 97 </refsect1> 98 99 <xi:include href="libsystemd-pkgconfig.xml" /> 100 101 <refsect1> 102 <title>See Also</title> 103 104 <para> 105 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, 106 <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>, 107 <citerefentry><refentrytitle>sd_bus_message_new</refentrytitle><manvolnum>3</manvolnum></citerefentry> 108 </para> 109 </refsect1> 110 111</refentry> 112