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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><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</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>