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/4.5/docbookx.dtd">
4 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
6 <refentry id=
"sd_bus_message_get_signature" xmlns:
xi=
"http://www.w3.org/2001/XInclude">
8 <title>sd_bus_message_get_signature
</title>
9 <productname>systemd
</productname>
13 <refentrytitle>sd_bus_message_get_signature
</refentrytitle>
14 <manvolnum>3</manvolnum>
18 <refname>sd_bus_message_get_signature
</refname>
19 <refname>sd_bus_message_is_empty
</refname>
20 <refname>sd_bus_message_has_signature
</refname>
22 <refpurpose>Query bus message signature
</refpurpose>
27 <funcsynopsisinfo>#include
<systemd/sd-bus.h
></funcsynopsisinfo>
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>
36 <funcdef>int
<function>sd_bus_message_is_empty
</function></funcdef>
37 <paramdef>sd_bus_message *
<parameter>message
</parameter></paramdef>
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>
50 <title>Description
</title>
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.
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>
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>.
68 <title>Return Value
</title>
70 <para>On success,
<function>sd_bus_message_get_signature()
</function> returns
71 the signature, and
<constant>NULL
</constant> on error.
</para>
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>
79 <para>Returned errors may indicate the following problems:
</para>
83 <term><constant>-EINVAL
</constant></term>
85 <listitem><para>The
<parameter>message
</parameter> parameter is
<constant>NULL
</constant>.
90 <term><constant>NULL
</constant></term>
92 <listitem><para>The
<parameter>message
</parameter> parameter is
<constant>NULL
</constant>.
99 <xi:include href=
"libsystemd-pkgconfig.xml" />
102 <title>History
</title>
103 <para><function>sd_bus_message_get_signature()
</function>,
104 <function>sd_bus_message_is_empty()
</function>, and
105 <function>sd_bus_message_has_signature()
</function> were added in version
240.
</para>
109 <title>See Also
</title>
111 <para><simplelist type=
"inline">
112 <member><citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
113 <member><citerefentry><refentrytitle>sd-bus
</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
114 <member><citerefentry><refentrytitle>sd_bus_message_new
</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>