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<?xml version='1.0'?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
<refentry id="sd_bus_is_open"
xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>sd_bus_is_open</title>
<productname>systemd</productname>
</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 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>The <parameter>bus</parameter> argument may be <constant>NULL</constant>, zero is also returned in
that case.</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>Those functions return 0 if the bus is <emphasis>not</emphasis> in the given state, and a positive
integer when it is. On failure, a negative errno-style error code is returned.</para>
<refsect2>
<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>
</refsect2>
</refsect1>
<xi:include href="libsystemd-pkgconfig.xml" />
<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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