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