man/sd_bus_request_name.xml

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  11   Copyright 2013 Lennart Poettering
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  26
  27 <refentry id="sd_bus_request_name">
  28
  29   <refentryinfo>
  30     <title>sd_bus_request_name</title>
  31     <productname>systemd</productname>
  32
  33     <authorgroup>
  34       <author>
  35         <contrib>Developer</contrib>
  36         <firstname>Lennart</firstname>
  37         <surname>Poettering</surname>
  38         <email>lennart@poettering.net</email>
  39       </author>
  40     </authorgroup>
  41   </refentryinfo>
  42
  43   <refmeta>
  44     <refentrytitle>sd_bus_request_name</refentrytitle>
  45     <manvolnum>3</manvolnum>
  46   </refmeta>
  47
  48   <refnamediv>
  49     <refname>sd_bus_request_name</refname>
  50     <refname>sd_bus_release_name</refname>
  51     <refpurpose>Request or release a well-known name on a bus</refpurpose>
  52   </refnamediv>
  53
  54   <refsynopsisdiv>
  55     <funcsynopsis>
  56       <funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>
  57
  58       <funcprototype>
  59         <funcdef>int <function>sd_bus_request_name</function></funcdef>
  60         <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
  61         <paramdef>const char *<parameter>name</parameter></paramdef>
  62         <paramdef>uint64_t <parameter>flags</parameter></paramdef>
  63       </funcprototype>
  64
  65       <funcprototype>
  66         <funcdef>int <function>sd_bus_release_name</function></funcdef>
  67         <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
  68         <paramdef>const char *<parameter>name</parameter></paramdef>
  69       </funcprototype>
  70     </funcsynopsis>
  71   </refsynopsisdiv>
  72
  73   <refsect1>
  74     <title>Description</title>
  75
  76     <para><function>sd_bus_request_name()</function> requests a
  77     well-known name on a bus. It takes a bus connection, a valid bus
  78     name and a flags parameter. The flags parameter is a combination
  79     of the following flags:</para>
  80
  81     <variablelist>
  82       <varlistentry>
  83         <term><varname>SD_BUS_NAME_ALLOW_REPLACEMENT</varname></term>
  84
  85         <listitem><para>After acquiring the name successfully, permit
  86         other peers to take over the name when they try to acquire it
  87         with the <varname>SD_BUS_NAME_REPLACE_EXISTING</varname> flag
  88         set. If <varname>SD_BUS_NAME_ALLOW_REPLACEMENT</varname> is
  89         not set on the original request, such a request by other peers
  90         will be denied.</para></listitem>
  91       </varlistentry>
  92
  93       <varlistentry>
  94         <term><varname>SD_BUS_NAME_REPLACE_EXISTING</varname></term>
  95
  96         <listitem><para>Take over the name if it is already acquired
  97         by another peer, and that other peer has permitted takeover by
  98         setting <varname>SD_BUS_NAME_ALLOW_REPLACEMENT</varname> while
  99         acquiring it.</para></listitem>
 100       </varlistentry>
 101
 102       <varlistentry>
 103         <term><varname>SD_BUS_NAME_QUEUE</varname></term>
 104
 105         <listitem><para>Queue the acquisition of the name when the
 106         name is already taken.</para></listitem>
 107       </varlistentry>
 108     </variablelist>
 109
 110     <para><function>sd_bus_release_name()</function> releases an
 111     acquired well-known name. It takes a bus connection and a valid
 112     bus name as parameters.</para>
 113   </refsect1>
 114
 115   <refsect1>
 116     <title>Return Value</title>
 117
 118     <para>On success, these calls return 0 or a positive integer. On
 119     failure, these calls return a negative errno-style error
 120     code.</para>
 121
 122     <para>If <varname>SD_BUS_NAME_QUEUE</varname> is specified,
 123     <function>sd_bus_request_name()</function> will return 0 when the
 124     name is already taken by another peer and the client has been
 125     added to the queue for the name. In that case, the caller can
 126     subscribe to <literal>NameOwnerChanged</literal> signals to be
 127     notified when the name is successfully acquired.
 128     <function>sd_bus_request_name()</function> returns &gt; 0 when the
 129     name has immediately been acquired successfully.</para>
 130   </refsect1>
 131
 132   <refsect1>
 133     <title>Errors</title>
 134
 135     <para>Returned errors may indicate the following problems:</para>
 136
 137     <variablelist>
 138       <varlistentry>
 139         <term><constant>-EALREADY</constant></term>
 140
 141         <listitem><para>The caller already is the owner of the
 142         specified name.</para></listitem>
 143       </varlistentry>
 144
 145       <varlistentry>
 146         <term><constant>-EEXIST</constant></term>
 147
 148         <listitem><para>The name has already been acquired by a
 149         different peer, and SD_BUS_NAME_REPLACE_EXISTING was not
 150         specified or the other peer did not specify
 151         SD_BUS_NAME_ALLOW_REPLACEMENT while acquiring the
 152         name.</para></listitem>
 153       </varlistentry>
 154
 155       <varlistentry>
 156         <term><constant>-ESRCH</constant></term>
 157
 158         <listitem><para>It was attempted to release a name that is
 159         currently not registered on the bus.</para></listitem>
 160       </varlistentry>
 161
 162       <varlistentry>
 163         <term><constant>-EADDRINUSE</constant></term>
 164
 165         <listitem><para>It was attempted to release a name that is
 166         owned by a different peer on the bus.</para></listitem>
 167       </varlistentry>
 168
 169       <varlistentry>
 170         <term><constant>-EINVAL</constant></term>
 171
 172         <listitem><para>A specified parameter is
 173         invalid.</para></listitem>
 174       </varlistentry>
 175
 176       <varlistentry>
 177         <term><constant>-ENOTCONN</constant></term>
 178
 179         <listitem><para>The bus connection has been
 180         disconnected.</para></listitem>
 181       </varlistentry>
 182
 183       <varlistentry>
 184         <term><constant>-ECHILD</constant></term>
 185
 186         <listitem><para>The bus connection has been created in a
 187         different process than the current one.</para></listitem>
 188       </varlistentry>
 189     </variablelist>
 190   </refsect1>
 191
 192   <refsect1>
 193     <title>Notes</title>
 194
 195     <para>The <function>sd_bus_acquire_name()</function> and
 196     <function>sd_bus_release_name()</function> interfaces are
 197     available as a shared library, which can be compiled and linked to
 198     with the
 199     <constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 200     file.</para>
 201   </refsect1>
 202
 203   <refsect1>
 204     <title>See Also</title>
 205
 206     <para>
 207       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 208       <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 209       <citerefentry><refentrytitle>sd_bus_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 210     </para>
 211   </refsect1>
 212
 213 </refentry>