man/sd_bus_set_fd.xml

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   6   SPDX-License-Identifier: LGPL-2.1-or-later
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   8   Copyright © 2016 Julian Orth
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  10
  11 <refentry id="sd_bus_set_fd" xmlns:xi="http://www.w3.org/2001/XInclude">
  12
  13   <refentryinfo>
  14     <title>sd_bus_set_fd</title>
  15     <productname>systemd</productname>
  16   </refentryinfo>
  17
  18   <refmeta>
  19     <refentrytitle>sd_bus_set_fd</refentrytitle>
  20     <manvolnum>3</manvolnum>
  21   </refmeta>
  22
  23   <refnamediv>
  24     <refname>sd_bus_set_fd</refname>
  25
  26     <refpurpose>Set the file descriptors to use for bus communication</refpurpose>
  27   </refnamediv>
  28
  29   <refsynopsisdiv>
  30     <funcsynopsis>
  31       <funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>
  32
  33       <funcprototype>
  34         <funcdef>int <function>sd_bus_set_fd</function></funcdef>
  35         <paramdef>sd_bus *<parameter>bus</parameter></paramdef>
  36         <paramdef>int <parameter>input_fd</parameter></paramdef>
  37         <paramdef>int <parameter>output_fd</parameter></paramdef>
  38       </funcprototype>
  39     </funcsynopsis>
  40   </refsynopsisdiv>
  41
  42   <refsect1>
  43     <title>Description</title>
  44
  45     <para><function>sd_bus_set_fd()</function> sets the file descriptors used to communicate by a bus
  46     connection object. Both <parameter>input_fd</parameter> and <parameter>output_fd</parameter> must be
  47     valid file descriptors, referring to stream-based file objects (e.g. a stream socket, a pair of pipes or
  48     FIFOs, or even a TTY device). <parameter>input_fd</parameter> must be readable, and
  49     <parameter>output_fd</parameter> must be writable. The same file descriptor may be used (and typically is
  50     used) as both the input and the output file descriptor. This function must be called before the bus
  51     connection is started via
  52     <citerefentry><refentrytitle>sd_bus_start</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
  53
  54     <para>The bus connection object will take possession of the passed file descriptors and will close them
  55     automatically when it is freed. Use
  56     <citerefentry><refentrytitle>sd_bus_set_close_on_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>
  57     to turn off this behaviour.</para>
  58   </refsect1>
  59
  60   <refsect1>
  61     <title>Return Value</title>
  62
  63     <para>On success, <function>sd_bus_set_fd()</function> returns a non-negative integer. On
  64     failure, it returns a negative errno-style error code.</para>
  65
  66     <refsect2>
  67       <title>Errors</title>
  68
  69       <para>Returned errors may indicate the following problems:</para>
  70
  71       <variablelist>
  72         <varlistentry>
  73           <term><constant>-EINVAL</constant></term>
  74
  75           <listitem><para>An invalid bus object was passed.</para>
  76
  77           <xi:include href="version-info.xml" xpointer="v248"/></listitem>
  78         </varlistentry>
  79
  80         <varlistentry>
  81           <term><constant>-ECHILD</constant></term>
  82
  83           <listitem><para>The bus connection was allocated in a parent process and is being reused
  84           in a child process after <function>fork()</function>.</para>
  85
  86           <xi:include href="version-info.xml" xpointer="v248"/></listitem>
  87         </varlistentry>
  88
  89         <varlistentry>
  90           <term><constant>-EBADF</constant></term>
  91
  92           <listitem><para>An invalid file descriptor was passed to
  93           <function>sd_bus_set_fd()</function>.</para>
  94
  95           <xi:include href="version-info.xml" xpointer="v248"/></listitem>
  96         </varlistentry>
  97
  98         <varlistentry>
  99           <term><constant>-ENOPKG</constant></term>
 100
 101           <listitem><para>The bus cannot be resolved.</para>
 102
 103           <xi:include href="version-info.xml" xpointer="v248"/></listitem>
 104         </varlistentry>
 105
 106         <varlistentry>
 107           <term><constant>-EPERM</constant></term>
 108
 109           <listitem><para>The bus connection has already been started.</para>
 110
 111           <xi:include href="version-info.xml" xpointer="v248"/></listitem>
 112         </varlistentry>
 113       </variablelist>
 114     </refsect2>
 115   </refsect1>
 116
 117   <xi:include href="libsystemd-pkgconfig.xml" />
 118
 119   <refsect1>
 120     <title>History</title>
 121     <para><function>sd_bus_set_fd()</function> was added in version 248.</para>
 122   </refsect1>
 123
 124   <refsect1>
 125     <title>See Also</title>
 126
 127     <para>
 128       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 129       <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 130       <citerefentry><refentrytitle>sd_bus_get_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
 131       <citerefentry><refentrytitle>sd_bus_start</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 132     </para>
 133   </refsect1>
 134
 135 </refentry>