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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_close"
xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>sd_bus_close</title>
<productname>systemd</productname>
</refentryinfo>
<refmeta>
<refentrytitle>sd_bus_close</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>sd_bus_close</refname>
<refname>sd_bus_flush</refname>
<refname>sd_bus_default_flush_close</refname>
<refpurpose>Close and flush a bus connection</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>
<funcprototype>
<funcdef>void <function>sd_bus_close</function></funcdef>
<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_bus_flush</function></funcdef>
<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>void <function>sd_bus_default_flush_close</function></funcdef>
<paramdef>void</paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><function>sd_bus_close()</function> disconnects the specified bus connection. When this
call is invoked and the specified bus object refers to an active connection it is immediately
terminated. No further messages may be sent or received on it. Any messages queued in the bus
object (both incoming and outgoing) are released. If invoked on <constant>NULL</constant> bus
object or when the bus connection is already closed this function executes no operation. This
call does not free or unreference the bus object itself. Use
<citerefentry><refentrytitle>sd_bus_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>
for that.</para>
<para><function>sd_bus_flush()</function> synchronously writes out all outgoing queued message
on a bus connection if there are any. This function call may block if the peer is not processing
bus messages quickly.</para>
<para>Before a program exits it is usually a good idea to flush any pending messages with
<function>sd_bus_flush()</function> and then close connections with
<function>sd_bus_close()</function> to ensure that no unwritten messages are lost, no further
messages may be queued and all incoming but unprocessed messages are released. After both
operations have been done, it is a good idea to also drop any remaining references to the bus
object so that it may be freed. Since these three operations are frequently done together a
helper call
<citerefentry><refentrytitle>sd_bus_flush_close_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>
is provided that combines them into one.</para>
<para><function>sd_bus_default_flush_close()</function> is similar to
<function>sd_bus_flush_close_unref()</function>, but does not take a bus pointer argument and
instead iterates over any of the "default" buses opened by
<citerefentry><refentrytitle>sd_bus_default</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_default_user</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_default_system</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
and similar calls. <function>sd_bus_default_flush_close()</function> is particularly useful to
clean up any buses opened using those calls before the program exits.</para>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>On success, <function>sd_bus_flush()</function> returns a non-negative integer. On
failure, it returns a negative errno-style error code.</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, library or module instance.</para>
</listitem>
</varlistentry>
</variablelist>
</refsect2>
</refsect1>
<xi:include href="libsystemd-pkgconfig.xml" />
<refsect1>
<title>History</title>
<para><function>sd_bus_close()</function> and
<function>sd_bus_flush()</function> were added in version 240.</para>
<para><function>sd_bus_default_flush_close()</function> was added in version 246.</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_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_set_close_on_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>
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