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.
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21 along with systemd; If not, see <http://www.gnu.org/licenses/>.
24 <refentry id="sd_bus_request_name" conditional="ENABLE_KDBUS">
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>uint64_t <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>
71 <title>Description</title>
73 <para><function>sd_bus_request_name()</function> requests
74 a well-known name on a bus. It takes a bus connection,
75 a valid bus name and a flags parameter. The flags
76 parameter is a combination of the following
81 <term><varname>SD_BUS_NAME_ALLOW_REPLACEMENT</varname></term>
83 <listitem><para>After acquiring the
84 name successfully, permit other peers
85 to take over the name when they try to
87 <varname>SD_BUS_NAME_REPLACE_EXISTING</varname>
89 <varname>SD_BUS_NAME_ALLOW_REPLACEMENT</varname>
90 is not set on the original request,
91 such a request by other peers will be
92 denied.</para></listitem>
96 <term><varname>SD_BUS_NAME_REPLACE_EXISTING</varname></term>
98 <listitem><para>Take over the name
99 if it is already acquired by another
100 peer, and that other peer has permitted
102 <varname>SD_BUS_NAME_ALLOW_REPLACEMENT</varname>
103 while acquiring it.</para></listitem>
107 <term><varname>SD_BUS_NAME_QUEUE</varname></term>
109 <listitem><para>Queue the acquisition
110 of the name when the name is already
111 taken.</para></listitem>
115 <para><function>sd_bus_release_name()</function> releases
116 an acquired well-known name. It takes a bus connection
117 and a valid bus name as parameters.</para>
121 <title>Return Value</title>
123 <para>On success, these calls return 0 or a positive
124 integer. On failure, these calls return a negative
125 errno-style error code.</para>
127 <para>If <varname>SD_BUS_NAME_QUEUE</varname> is
128 specified, <function>sd_bus_request_name()</function>
129 will return 0 when the name is already taken by
130 another peer and the client has been added to the
131 queue for the name. In that case, the caller can
132 subscribe to <literal>NameOwnerChanged</literal>
133 signals to be notified when the name is successfully
134 acquired. <function>sd_bus_request_name()</function>
135 returns > 0 when the name has immediately been
136 acquired successfully.</para>
140 <title>Errors</title>
142 <para>Returned errors may indicate the following problems:</para>
146 <term><constant>-EALREADY</constant></term>
148 <listitem><para>The caller already is
149 the owner of the specified
150 name.</para></listitem>
154 <term><constant>-EEXIST</constant></term>
156 <listitem><para>The name has already
157 been acquired by a different peer, and
158 SD_BUS_NAME_REPLACE_EXISTING was not
159 specified or the other peer did not
160 specify SD_BUS_NAME_ALLOW_REPLACEMENT
162 name.</para></listitem>
166 <term><constant>-ESRCH</constant></term>
168 <listitem><para>It was attempted to
169 release a name that is currently not
171 bus.</para></listitem>
175 <term><constant>-EADDRINUSE</constant></term>
177 <listitem><para>It was attempted to
178 release a name that is owned by a
179 different peer on the
180 bus.</para></listitem>
184 <term><constant>-EINVAL</constant></term>
186 <listitem><para>A specified parameter
187 is invalid.</para></listitem>
191 <term><constant>-ENOTCONN</constant></term>
193 <listitem><para>The bus connection has
194 been disconnected.</para></listitem>
198 <term><constant>-ECHILD</constant></term>
200 <listitem><para>The bus connection has
201 been created in a different process
202 than the current one.</para></listitem>
210 <para>The <function>sd_bus_acquire_name()</function>
211 and <function>sd_bus_release_name()</function>
212 interfaces are available as a shared library, which can
213 be compiled and linked to with the
214 <constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
219 <title>See Also</title>
222 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
223 <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
224 <citerefentry><refentrytitle>sd_bus_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>