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<refentry id="sd_bus_request_name" conditional="ENABLE_KDBUS">

<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 &lt;systemd/sd-bus.h&gt;</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 &gt; 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>