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113 lines
4.5 KiB
XML
113 lines
4.5 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_is_open"
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xmlns:xi="http://www.w3.org/2001/XInclude">
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<refentryinfo>
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<title>sd_bus_is_open</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_is_open</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_is_open</refname>
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<refname>sd_bus_is_ready</refname>
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<refpurpose>Check whether the bus connection is open or ready</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_is_open</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_is_ready</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_is_open()</function> checks whether the specified bus connection is open, i.e. in the
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process of being established, already established or in the process of being torn down. It returns zero when the
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connection has not been started yet
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(i.e. <citerefentry><refentrytitle>sd_bus_start</refentrytitle><manvolnum>3</manvolnum></citerefentry> or some
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equivalent call has not been invoked yet), or is fully terminated again (for example after
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<citerefentry><refentrytitle>sd_bus_close</refentrytitle><manvolnum>3</manvolnum></citerefentry>), it returns
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positive otherwise.</para>
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<para><function>sd_bus_is_ready()</function> checks whether the specified connection is fully established,
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i.e. completed the connection and authentication phases of the protocol and received the
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<function>Hello()</function> method call response, and is not in the process of being torn down again. It returns
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zero outside of this state, and positive otherwise. Effectively, this function returns positive while regular
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messages can be sent or received on the connection.</para>
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<para>The <parameter>bus</parameter> argument may be <constant>NULL</constant>, zero is also returned in
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that case.</para>
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<para>To be notified when the connection is fully established, use
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<citerefentry><refentrytitle>sd_bus_set_connected_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry> and
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install a match for the <function>Connected()</function> signal on the
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<literal>org.freedesktop.DBus.Local</literal> interface. To be notified when the connection is torn down again,
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install a match for the <function>Disconnected()</function> signal on the
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<literal>org.freedesktop.DBus.Local</literal> interface.</para>
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</refsect1>
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<refsect1>
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<title>Return Value</title>
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<para>Those functions return 0 if the bus is <emphasis>not</emphasis> in the given state, and a positive
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integer when it is. On failure, a negative errno-style error code is returned.</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></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_is_open()</function> and
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<function>sd_bus_is_ready()</function> were added in version 237.</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_start</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_bus_close</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_bus_set_connected_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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