systemd/man/sd_bus_request_name.xml

214 lines
7.3 KiB
XML
Raw Blame History

This file contains invisible Unicode characters

This file contains invisible Unicode characters that are indistinguishable to humans but may be processed differently by a computer. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

<?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 service 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 service 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. This is also
generated when the requested name is a special service name
reserved by the D-Bus specification, or when the operation is
requested on a connection that does not refer to a
bus.</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>