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<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!--
This file is part of systemd.
Copyright 2013 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
-->
<refentry id="sd_bus_request_name">
<refentryinfo>
<title>sd_bus_request_name</title>
<productname>systemd</productname>
<authorgroup>
<author>
<contrib>Developer</contrib>
<firstname>Lennart</firstname>
<surname>Poettering</surname>
<email>lennart@poettering.net</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta>
<refentrytitle>sd_bus_request_name</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>sd_bus_request_name</refname>
<refname>sd_bus_release_name</refname>
<refpurpose>Request or release a well-known name on a bus</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>
<funcprototype>
<funcdef>int <function>sd_bus_request_name</function></funcdef>
<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
<paramdef>const char *<parameter>name</parameter></paramdef>
<paramdef>uint64_t <parameter>flags</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_release_name</function></funcdef>
<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
<paramdef>const char *<parameter>name</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><function>sd_bus_request_name()</function> requests a
well-known name on a bus. It takes a bus connection, a valid bus
name and a flags parameter. The flags parameter is a combination
of the following flags:</para>
<variablelist>
<varlistentry>
<term><varname>SD_BUS_NAME_ALLOW_REPLACEMENT</varname></term>
<listitem><para>After acquiring the name successfully, permit
other peers to take over the name when they try to acquire it
with the <varname>SD_BUS_NAME_REPLACE_EXISTING</varname> flag
set. If <varname>SD_BUS_NAME_ALLOW_REPLACEMENT</varname> is
not set on the original request, such a request by other peers
will be denied.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>SD_BUS_NAME_REPLACE_EXISTING</varname></term>
<listitem><para>Take over the name if it is already acquired
by another peer, and that other peer has permitted takeover by
setting <varname>SD_BUS_NAME_ALLOW_REPLACEMENT</varname> while
acquiring it.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>SD_BUS_NAME_QUEUE</varname></term>
<listitem><para>Queue the acquisition of the name when the
name is already taken.</para></listitem>
</varlistentry>
</variablelist>
<para><function>sd_bus_release_name()</function> releases an
acquired well-known name. It takes a bus connection and a valid
bus name as parameters.</para>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>On success, these calls return 0 or a positive integer. On
failure, these calls return a negative errno-style error
code.</para>
<para>If <varname>SD_BUS_NAME_QUEUE</varname> is specified,
<function>sd_bus_request_name()</function> will return 0 when the
name is already taken by another peer and the client has been
added to the queue for the name. In that case, the caller can
subscribe to <literal>NameOwnerChanged</literal> signals to be
notified when the name is successfully acquired.
<function>sd_bus_request_name()</function> returns > 0 when the
name has immediately been acquired successfully.</para>
</refsect1>
<refsect1>
<title>Errors</title>
<para>Returned errors may indicate the following problems:</para>
<variablelist>
<varlistentry>
<term><constant>-EALREADY</constant></term>
<listitem><para>The caller already is the owner of the
specified name.</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-EEXIST</constant></term>
<listitem><para>The name has already been acquired by a
different peer, and SD_BUS_NAME_REPLACE_EXISTING was not
specified or the other peer did not specify
SD_BUS_NAME_ALLOW_REPLACEMENT while acquiring the
name.</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-ESRCH</constant></term>
<listitem><para>It was attempted to release a name that is
currently not registered on the bus.</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-EADDRINUSE</constant></term>
<listitem><para>It was attempted to release a name that is
owned by a different peer on the bus.</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-EINVAL</constant></term>
<listitem><para>A specified parameter is
invalid.</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-ENOTCONN</constant></term>
<listitem><para>The bus connection has been
disconnected.</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-ECHILD</constant></term>
<listitem><para>The bus connection has been created in a
different process than the current one.</para></listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Notes</title>
<para>The <function>sd_bus_acquire_name()</function> and
<function>sd_bus_release_name()</function> interfaces are
available as a shared library, which can be compiled and linked to
with the
<constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
file.</para>
</refsect1>
<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_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>
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