1 <?xml version='
1.0'
?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
2 <!DOCTYPE refentry PUBLIC
"-//OASIS//DTD DocBook XML V4.2//EN"
3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
6 SPDX-License-Identifier: LGPL-2.1+
8 Copyright 2015 Lennart Poettering
11 <refentry id=
"sd_event_source_set_userdata" xmlns:
xi=
"http://www.w3.org/2001/XInclude">
14 <title>sd_event_source_set_userdata
</title>
15 <productname>systemd
</productname>
19 <contrib>Developer
</contrib>
20 <firstname>Lennart
</firstname>
21 <surname>Poettering
</surname>
22 <email>lennart@poettering.net
</email>
28 <refentrytitle>sd_event_source_set_userdata
</refentrytitle>
29 <manvolnum>3</manvolnum>
33 <refname>sd_event_source_set_userdata
</refname>
34 <refname>sd_event_source_get_userdata
</refname>
36 <refpurpose>Set or retrieve user data pointer of event sources
</refpurpose>
41 <funcsynopsisinfo>#include
<systemd/sd-event.h
></funcsynopsisinfo>
44 <funcdef>void*
<function>sd_event_source_set_userdata
</function></funcdef>
45 <paramdef>sd_event_source *
<parameter>source
</parameter></paramdef>
46 <paramdef>void *
<parameter>userdata
</parameter></paramdef>
50 <funcdef>void*
<function>sd_event_source_get_userdata
</function></funcdef>
51 <paramdef>sd_event_source *
<parameter>source
</parameter></paramdef>
58 <title>Description
</title>
60 <para><function>sd_event_source_set_userdata()
</function> may be
61 used to set an arbitrary user data pointer for the event source
62 object specified as
<parameter>source
</parameter>. The user data
63 pointer is usually specified when creating an event source object
65 <citerefentry><refentrytitle>sd_event_add_io
</refentrytitle><manvolnum>3</manvolnum></citerefentry>
67 <citerefentry><refentrytitle>sd_event_add_time
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
68 and may be updated with this call. The user data pointer is also
69 passed to all handler callback functions associated with the event
70 source. The
<parameter>userdata
</parameter> parameter specifies
71 the new user data pointer to set, the function returns the
72 previous user data pointer. Note that
<constant>NULL
</constant> is
73 a valid user data pointer.
</para>
75 <para><function>sd_event_source_get_userdata()
</function> may be
76 used to query the current user data pointer assigned to the event
77 source object
<parameter>source
</parameter>.
</para>
81 <title>Return Value
</title>
84 <function>sd_event_source_set_userdata()
</function> and
85 <function>sd_event_source_get_userdata()
</function> return the
86 previously set user data pointer. On failure, they return
90 <xi:include href=
"libsystemd-pkgconfig.xml" />
93 <title>See Also
</title>
96 <citerefentry><refentrytitle>sd-event
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
97 <citerefentry><refentrytitle>sd_event_add_io
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
98 <citerefentry><refentrytitle>sd_event_add_time
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
99 <citerefentry><refentrytitle>sd_event_add_child
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
100 <citerefentry><refentrytitle>sd_event_add_signal
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
101 <citerefentry><refentrytitle>sd_event_add_defer
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
102 <citerefentry><refentrytitle>sd_event_source_set_description
</refentrytitle><manvolnum>3</manvolnum></citerefentry>