man/sd_event_source_set_userdata.xml

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   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
   3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
   4
   5 <!--
   6   SPDX-License-Identifier: LGPL-2.1+
   7 -->
   8
   9 <refentry id="sd_event_source_set_userdata" xmlns:xi="http://www.w3.org/2001/XInclude">
  10
  11   <refentryinfo>
  12     <title>sd_event_source_set_userdata</title>
  13     <productname>elogind</productname>
  14   </refentryinfo>
  15
  16   <refmeta>
  17     <refentrytitle>sd_event_source_set_userdata</refentrytitle>
  18     <manvolnum>3</manvolnum>
  19   </refmeta>
  20
  21   <refnamediv>
  22     <refname>sd_event_source_set_userdata</refname>
  23     <refname>sd_event_source_get_userdata</refname>
  24
  25     <refpurpose>Set or retrieve user data pointer of event sources</refpurpose>
  26   </refnamediv>
  27
  28   <refsynopsisdiv>
  29     <funcsynopsis>
  30       <funcsynopsisinfo>#include &lt;elogind/sd-event.h&gt;</funcsynopsisinfo>
  31
  32       <funcprototype>
  33         <funcdef>void* <function>sd_event_source_set_userdata</function></funcdef>
  34         <paramdef>sd_event_source *<parameter>source</parameter></paramdef>
  35         <paramdef>void *<parameter>userdata</parameter></paramdef>
  36       </funcprototype>
  37
  38       <funcprototype>
  39         <funcdef>void* <function>sd_event_source_get_userdata</function></funcdef>
  40         <paramdef>sd_event_source *<parameter>source</parameter></paramdef>
  41       </funcprototype>
  42
  43     </funcsynopsis>
  44   </refsynopsisdiv>
  45
  46   <refsect1>
  47     <title>Description</title>
  48
  49     <para><function>sd_event_source_set_userdata()</function> may be
  50     used to set an arbitrary user data pointer for the event source
  51     object specified as <parameter>source</parameter>. The user data
  52     pointer is usually specified when creating an event source object
  53     with calls such as
  54     <citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>
  55     or
  56     <citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
  57     and may be updated with this call. The user data pointer is also
  58     passed to all handler callback functions associated with the event
  59     source. The <parameter>userdata</parameter> parameter specifies
  60     the new user data pointer to set, the function returns the
  61     previous user data pointer. Note that <constant>NULL</constant> is
  62     a valid user data pointer.</para>
  63
  64     <para><function>sd_event_source_get_userdata()</function> may be
  65     used to query the current user data pointer assigned to the event
  66     source object <parameter>source</parameter>.</para>
  67   </refsect1>
  68
  69   <refsect1>
  70     <title>Return Value</title>
  71
  72     <para>On success,
  73     <function>sd_event_source_set_userdata()</function> and
  74     <function>sd_event_source_get_userdata()</function> return the
  75     previously set user data pointer. On failure, they return
  76     NULL.</para>
  77   </refsect1>
  78
  79   <xi:include href="libelogind-pkgconfig.xml" />
  80
  81   <refsect1>
  82     <title>See Also</title>
  83
  84     <para>
  85       <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
  86       <citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
  87       <citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
  88       <citerefentry><refentrytitle>sd_event_add_child</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
  89       <citerefentry><refentrytitle>sd_event_add_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
  90       <citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
  91       <citerefentry><refentrytitle>sd_event_source_set_description</refentrytitle><manvolnum>3</manvolnum></citerefentry>
  92     </para>
  93   </refsect1>
  94
  95 </refentry>