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<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
<!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 2017 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_is_open">
<refentryinfo>
<title>sd_bus_is_open</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_is_open</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>sd_bus_is_open</refname>
<refname>sd_bus_is_ready</refname>
<refpurpose>Check whether the a bus connection is open or ready.</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>
<funcprototype>
<funcdef>int <function>sd_bus_is_open</function></funcdef>
<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_is_ready</function></funcdef>
<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><function>sd_bus_is_open()</function> checks whether the specified bus connection is open, i.e. in the
process of being established, already established or in the process of being torn down. It returns zero when the
connection has not been started yet
(i.e. <citerefentry><refentrytitle>sd_bus_start</refentrytitle><manvolnum>3</manvolnum></citerefentry> or some
equivalent call has not been invoked yet), or is fully terminated again (for example after
<citerefentry><refentrytitle>sd_bus_close</refentrytitle><manvolnum>3</manvolnum></citerefentry>), it returns
positive otherwise.</para>
<para><function>sd_bus_is_ready()</function> checks whether the specified connection is fully established,
i.e. completed the connection and authentication phases of the protocol and received the
<function>Hello()</function> method call response, and is not in the process of being torn down again. It returns
zero outside of this state, and positive otherwise. Effectively, this function returns positive while regular
messages can be sent or received on the connection.</para>
<para>To be notified when the connection is fully established, use
<citerefentry><refentrytitle>sd_bus_set_connected_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry> and
install a match for the <function>Connected()</function> signal on the
<literal>org.freedesktop.DBus.Local</literal> interface. To be notified when the connection is torn down again,
install a match for the <function>Disconnected()</function> signal on the
<literal>org.freedesktop.DBus.Local</literal> interface.</para>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>On success, these functions return 0 or a positive integer. On failure, they return a negative errno-style
error code.</para>
</refsect1>
<refsect1>
<title>Errors</title>
<para>Returned errors may indicate the following problems:</para>
<variablelist>
<varlistentry>
<term><constant>-ECHILD</constant></term>
<listitem><para>The bus connection has been created in a different process.</para></listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Notes</title>
<para><function>sd_bus_is_open()</function> and <function>sd_bus_is_ready()</function> 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_start</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_close</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_set_connected_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>
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