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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
Copyright © 2016 Julian Orth
-->
<refentry id="sd_bus_set_fd" xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>sd_bus_set_fd</title>
<productname>systemd</productname>
</refentryinfo>
<refmeta>
<refentrytitle>sd_bus_set_fd</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>sd_bus_set_fd</refname>
<refpurpose>Set the file descriptors to use for bus communication</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>
<funcprototype>
<funcdef>int <function>sd_bus_set_fd</function></funcdef>
<paramdef>sd_bus *<parameter>bus</parameter></paramdef>
<paramdef>int <parameter>input_fd</parameter></paramdef>
<paramdef>int <parameter>output_fd</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><function>sd_bus_set_fd()</function> sets the file descriptors used to communicate by a bus
connection object. Both <parameter>input_fd</parameter> and <parameter>output_fd</parameter> must be
valid file descriptors, referring to stream-based file objects (e.g. a stream socket, a pair of pipes or
FIFOs, or even a TTY device). <parameter>input_fd</parameter> must be readable, and
<parameter>output_fd</parameter> must be writable. The same file descriptor may be used (and typically is
used) as both the input and the output file descriptor. This function must be called before the bus
connection is started via
<citerefentry><refentrytitle>sd_bus_start</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
<para>The bus connection object will take possession of the passed file descriptors and will close them
automatically when it is freed. Use
<citerefentry><refentrytitle>sd_bus_set_close_on_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>
to turn off this behaviour.</para>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>On success, <function>sd_bus_set_fd()</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>-EINVAL</constant></term>
<listitem><para>An invalid bus object was passed.</para>
<xi:include href="version-info.xml" xpointer="v248"/></listitem>
</varlistentry>
<varlistentry>
<term><constant>-ECHILD</constant></term>
<listitem><para>The bus connection was allocated in a parent process and is being reused
in a child process after <function>fork()</function>.</para>
<xi:include href="version-info.xml" xpointer="v248"/></listitem>
</varlistentry>
<varlistentry>
<term><constant>-EBADF</constant></term>
<listitem><para>An invalid file descriptor was passed to
<function>sd_bus_set_fd()</function>.</para>
<xi:include href="version-info.xml" xpointer="v248"/></listitem>
</varlistentry>
<varlistentry>
<term><constant>-ENOPKG</constant></term>
<listitem><para>The bus cannot be resolved.</para>
<xi:include href="version-info.xml" xpointer="v248"/></listitem>
</varlistentry>
<varlistentry>
<term><constant>-EPERM</constant></term>
<listitem><para>The bus connection has already been started.</para>
<xi:include href="version-info.xml" xpointer="v248"/></listitem>
</varlistentry>
</variablelist>
</refsect2>
</refsect1>
<xi:include href="libsystemd-pkgconfig.xml" />
<refsect1>
<title>History</title>
<para><function>sd_bus_set_fd()</function> was added in version 248.</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_get_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_bus_start</refentrytitle><manvolnum>3</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>
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