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125 lines
4.9 KiB
XML
125 lines
4.9 KiB
XML
<?xml version='1.0'?>
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!-- SPDX-License-Identifier: LGPL-2.1+ -->
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<refentry id="sd_bus_start"
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xmlns:xi="http://www.w3.org/2001/XInclude">
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<refentryinfo>
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<title>sd_bus_start</title>
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<productname>systemd</productname>
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</refentryinfo>
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<refmeta>
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<refentrytitle>sd_bus_start</refentrytitle>
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<manvolnum>3</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>sd_bus_start</refname>
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<refpurpose>Initiate a bus connection to the D-bus broker daemon
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</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<funcsynopsis>
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<funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>
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<funcprototype>
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<funcdef>int <function>sd_bus_start</function></funcdef>
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<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><function>sd_bus_start()</function> connects an existing bus connection object to the D-Bus
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broker daemon, usually
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<citerefentry project='die-net'><refentrytitle>dbus-daemon</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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or
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<citerefentry project='mankier'><refentrytitle>dbus-broker</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
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The mechanism to use for the connection must be configured before the call to
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<function>sd_bus_start()</function>, using one of
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<citerefentry><refentrytitle>sd_bus_set_address</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_bus_set_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry>, or
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<citerefentry><refentrytitle>sd_bus_set_exec</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
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<function>sd_bus_start()</function> will open the connection socket or spawn the executable as
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needed, and asynchronously start a <function>org.freedesktop.DBus.Hello()</function> call. The
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answer to the Hello call will be processed later from
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<citerefentry><refentrytitle>sd_bus_process</refentrytitle><manvolnum>3</manvolnum></citerefentry>. If
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opening of the connection or queuing of the asynchronous call fail, the connection will be closed with
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<citerefentry><refentrytitle>sd_bus_close</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
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<para>In most cases, it is better to use
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<citerefentry><refentrytitle>sd_bus_default_user</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_bus_default_system</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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or related calls instead of the more low-level <function>sd_bus_new()</function> and
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<function>sd_bus_start()</function>. The higher-level functions not only allocate a bus object but also
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start the connection to a well-known bus in a single function call.</para>
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</refsect1>
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<refsect1>
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<title>Return Value</title>
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<para>On success, this function returns a non-negative integer. On failure, it returns a negative
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errno-style error code.</para>
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<refsect2 id='errors'>
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<title>Errors</title>
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<variablelist>
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<varlistentry>
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<term><constant>-EINVAL</constant></term>
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<listitem><para>The input parameter <parameter>bus</parameter> is <constant>NULL</constant>.
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-ENOPKG</constant></term>
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<listitem><para>Bus object <parameter>bus</parameter> could not be resolved.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-EPERM</constant></term>
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<listitem><para>The input parameter <parameter>bus</parameter> is in a wrong state
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(<function>sd_bus_start()</function> may only be called once on a newly-created bus object).</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-ECHILD</constant></term>
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<listitem><para>The bus object <parameter>bus</parameter> was created in a different
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process.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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<para>In addition, other connection-related errors may be returned. See
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<citerefentry><refentrytitle>sd_bus_send</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
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</refsect2>
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</refsect1>
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<xi:include href="libsystemd-pkgconfig.xml" />
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<refsect1>
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<title>See Also</title>
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<para>
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_bus_default</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_bus_call_async</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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