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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><varname>-EALREADY</varname></term>
<listitem><para>The caller already is
the owner of the specified
name.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>-EEXIST</varname></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><varname>-ESRCH</varname></term>
<listitem><para>It was attempted to
release a name that is currently not
registered on the
bus.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>-EADDRINUSE</varname></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><varname>-EINVAL</varname></term>
<listitem><para>A specified parameter
is invalid.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>-ENOTCONN</varname></term>
<listitem><para>The bus connection has
been disconnected.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>-ECHILD</varname></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-bus</constant> <citerefentry><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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