1 <?xml version='1.0'?> <!--*-nxml-*-->
2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
6 This file is part of systemd.
8 Copyright 2013 Lennart Poettering
10 systemd is free software; you can redistribute it and/or modify it
11 under the terms of the GNU Lesser General Public License as published by
12 the Free Software Foundation; either version 2.1 of the License, or
13 (at your option) any later version.
15 systemd is distributed in the hope that it will be useful, but
16 WITHOUT ANY WARRANTY; without even the implied warranty of
17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 Lesser General Public License for more details.
20 You should have received a copy of the GNU Lesser General Public License
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24 <refentry id="sd_bus_request_name">
27 <title>sd_bus_request_name</title>
28 <productname>systemd</productname>
32 <contrib>Developer</contrib>
33 <firstname>Lennart</firstname>
34 <surname>Poettering</surname>
35 <email>lennart@poettering.net</email>
41 <refentrytitle>sd_bus_request_name</refentrytitle>
42 <manvolnum>3</manvolnum>
46 <refname>sd_bus_request_name</refname>
47 <refname>sd_bus_release_name</refname>
48 <refpurpose>Request or release a well-known name on a bus</refpurpose>
53 <funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>
56 <funcdef>int <function>sd_bus_request_name</function></funcdef>
57 <paramdef>sd_bus* <parameter>bus</parameter></paramdef>
58 <paramdef>const char *<parameter>name</parameter></paramdef>
59 <paramdef>unsigned <parameter>flags</parameter></paramdef>
63 <funcdef>int <function>sd_bus_release_name</function></funcdef>
64 <paramdef>sd_bus* <parameter>bus</parameter></paramdef>
65 <paramdef>const char *<parameter>name</parameter></paramdef>
73 <title>Description</title>
75 <para><function>sd_bus_request_name()</function> requests
76 a well-known name on a bus. It takes a bus connection,
77 a valid bus name and a flags parameter. The flags
78 parameter is a combination of the following
83 <term><varname>SD_BUS_NAME_ALLOW_REPLACEMENT</varname></term>
85 <listitem><para>After acquiring the
86 name successuflly, permit other peers
87 to take over the name when they try to
89 <varname>SD_BUS_NAME_REPLACE_EXISTING</varname>
91 <varname>SD_BUS_NAME_ALLOW_REPLACEMENT</varname>
92 is not set on the original request
93 such a request by other peers will be
94 denied.</para></listitem>
98 <term><varname>SD_BUS_NAME_REPLACE_EXISTING</varname></term>
100 <listitem><para>Take over a the name
101 if it is already acquired by a another
102 peer, and that other peer permitted
103 taking it over by setting
104 <varname>SD_BUS_NAME_ALLOW_REPLACEMENT</varname>
105 while acquiring it.</para></listitem>
109 <term><varname>SD_BUS_NAME_QUEUE</varname></term>
111 <listitem><para>Queue name
112 acquisition when the name is already
113 taken.</para></listitem>
117 <para><function>sd_bus_release_name()</function> releases
118 an acquired well-known name. It takes a bus connection
119 and a valid bus name as parameters.</para>
123 <title>Return Value</title>
125 <para>On success, these calls return 0 or a positive
126 integer. On failure, these calls return a negative
127 errno-style error code.</para>
129 <para>If <varname>SD_BUS_NAME_QUEUE</varname> is
130 specified <function>sd_bus_request_name()</function>
131 will return 0 when the name is already taken by
132 another peer and the client has been added to the
133 queue for the name. In that case the caller can
134 subscribe to <literal>NameOwnerChanged</literal>
135 signals to be notified when the name is successfully
136 acquired. <function>sd_bus_request_name()</function>
137 returns > 0 when the name has immediately been
138 acquired successfully.</para>
142 <title>Errors</title>
144 <para>Returned errors may indicate the following problems:</para>
148 <term><varname>-EALREADY</varname></term>
150 <listitem><para>The caller already is
151 the owner of the specified
152 name.</para></listitem>
156 <term><varname>-EEXIST</varname></term>
158 <listitem><para>The name has already
159 been acquired by a different peer, and
160 SD_BUS_NAME_REPLACE_EXISTING was not
161 specified or the other peer did not
162 specify SD_BUS_NAME_ALLOW_REPLACEMENT
164 name.</para></listitem>
168 <term><varname>-EINVAL</varname></term>
170 <listitem><para>A specified parameter
171 is invalid.</para></listitem>
175 <term><varname>-ENOTCONN</varname></term>
177 <listitem><para>The bus connection has
178 been disconnected.</para></listitem>
182 <term><varname>-ECHILD</varname></term>
184 <listitem><para>The bus connection has
185 been created in a different process
186 than the current.</para></listitem>
194 <para>The <function>sd_bus_acquire_name()</function>
195 and <function>sd_bus_release_bame()</function>
196 interfaces are available as shared library, which can
197 be compiled and linked to with the
198 <constant>libsystemd-bus</constant> <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
203 <title>See Also</title>
206 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
207 <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
208 <citerefentry><refentrytitle>sd_bus_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>