man: grammar and wording improvements

[thirdparty/systemd.git] / man / sd_bus_request_name.xml

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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
        "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">

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<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 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-bus</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>