mirror of
https://github.com/systemd/systemd.git
synced 2024-11-06 16:59:03 +03:00
242 lines
10 KiB
XML
242 lines
10 KiB
XML
<?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">
|
||
|
||
<!--
|
||
SPDX-License-Identifier: LGPL-2.1+
|
||
|
||
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_request_name_async</refname>
|
||
<refname>sd_bus_release_name</refname>
|
||
<refname>sd_bus_release_name_async</refname>
|
||
<refpurpose>Request or release a well-known service 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_request_name_async</function></funcdef>
|
||
<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
|
||
<paramdef>sd_bus_slot **<parameter>slot</parameter></paramdef>
|
||
<paramdef>const char *<parameter>name</parameter></paramdef>
|
||
<paramdef>uint64_t <parameter>flags</parameter></paramdef>
|
||
<paramdef>sd_bus_message_handler_t <parameter>callback</parameter></paramdef>
|
||
<paramdef>void *<parameter>userdata</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>
|
||
|
||
<funcprototype>
|
||
<funcdef>int <function>sd_bus_release_name_async</function></funcdef>
|
||
<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
|
||
<paramdef>sd_bus_slot **<parameter>slot</parameter></paramdef>
|
||
<paramdef>const char *<parameter>name</parameter></paramdef>
|
||
<paramdef>sd_bus_message_handler_t <parameter>callback</parameter></paramdef>
|
||
<paramdef>void *<parameter>userdata</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_request_name()</function> operates in a synchronous fashion: a message requesting the name
|
||
is sent to the bus broker, and the call waits until the broker responds.</para>
|
||
|
||
<para><function>sd_bus_request_name_async()</function> is an asynchronous version of of
|
||
<function>sd_bus_release_name()</function>. Instead of waiting for the request to complete, the request message is
|
||
enqueued. The specified <parameter>callback</parameter> will be called when the broker's response is received. If
|
||
the parameter is specified as <constant>NULL</constant> a default implementation is used instead which will
|
||
terminate the connection when the name cannot be acquired. The function returns a slot object in its
|
||
<parameter>slot</parameter> parameter — if it is passed as non-<constant>NULL</constant> — which may be used as a
|
||
reference to the name request operation. Use
|
||
<citerefentry><refentrytitle>sd_bus_slot_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry> to destroy
|
||
this reference. Note that destroying the reference will not unregister the name, but simply ensure the specified
|
||
callback is no longer called.</para>
|
||
|
||
<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. This function operates synchronously, sending a release request message to the
|
||
bus broker and waiting for it to reply.</para>
|
||
|
||
<para><function>sd_bus_release_name_async()</function> is an asynchronous version of
|
||
<function>sd_bus_release_name()</function>. The specified <parameter>callback</parameter> function is called when
|
||
the name has been released successfully. If specified as <constant>NULL</constant> a generic implementation is used
|
||
that ignores the result of the operation. As above, the <parameter>slot</parameter> (if
|
||
non-<constant>NULL</constant>) is set to an object that may be used to reference the operation.</para>
|
||
|
||
<para>These functions are supported only on bus connections, i.e. connections to a bus broker and not on direct
|
||
connections.</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. 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 the other interfaces described here 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>,
|
||
<citerefentry><refentrytitle>sd_bus_slot_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>
|
||
</para>
|
||
</refsect1>
|
||
|
||
</refentry>
|