sd_bus_request_name.xml 9.91 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228
<?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" 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>