2 <!DOCTYPE refentry PUBLIC
"-//OASIS//DTD DocBook XML V4.5//EN"
3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
4 <!-- SPDX-License-Identifier: LGPL-2.1+ -->
6 <refentry id=
"sd_event_source_set_userdata" xmlns:
xi=
"http://www.w3.org/2001/XInclude">
9 <title>sd_event_source_set_userdata
</title>
10 <productname>systemd
</productname>
14 <refentrytitle>sd_event_source_set_userdata
</refentrytitle>
15 <manvolnum>3</manvolnum>
19 <refname>sd_event_source_set_userdata
</refname>
20 <refname>sd_event_source_get_userdata
</refname>
22 <refpurpose>Set or retrieve user data pointer of event sources
</refpurpose>
27 <funcsynopsisinfo>#include
<systemd/sd-event.h
></funcsynopsisinfo>
30 <funcdef>void*
<function>sd_event_source_set_userdata
</function></funcdef>
31 <paramdef>sd_event_source *
<parameter>source
</parameter></paramdef>
32 <paramdef>void *
<parameter>userdata
</parameter></paramdef>
36 <funcdef>void*
<function>sd_event_source_get_userdata
</function></funcdef>
37 <paramdef>sd_event_source *
<parameter>source
</parameter></paramdef>
44 <title>Description
</title>
46 <para><function>sd_event_source_set_userdata()
</function> may be
47 used to set an arbitrary user data pointer for the event source
48 object specified as
<parameter>source
</parameter>. The user data
49 pointer is usually specified when creating an event source object
51 <citerefentry><refentrytitle>sd_event_add_io
</refentrytitle><manvolnum>3</manvolnum></citerefentry>
53 <citerefentry><refentrytitle>sd_event_add_time
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
54 and may be updated with this call. The user data pointer is also
55 passed to all handler callback functions associated with the event
56 source. The
<parameter>userdata
</parameter> parameter specifies
57 the new user data pointer to set, the function returns the
58 previous user data pointer. Note that
<constant>NULL
</constant> is
59 a valid user data pointer.
</para>
61 <para><function>sd_event_source_get_userdata()
</function> may be
62 used to query the current user data pointer assigned to the event
63 source object
<parameter>source
</parameter>.
</para>
67 <title>Return Value
</title>
70 <function>sd_event_source_set_userdata()
</function> and
71 <function>sd_event_source_get_userdata()
</function> return the
72 previously set user data pointer. On failure, they return
76 <xi:include href=
"libsystemd-pkgconfig.xml" />
79 <title>See Also
</title>
82 <citerefentry><refentrytitle>sd-event
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
83 <citerefentry><refentrytitle>sd_event_add_io
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
84 <citerefentry><refentrytitle>sd_event_add_time
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
85 <citerefentry><refentrytitle>sd_event_add_signal
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
86 <citerefentry><refentrytitle>sd_event_add_child
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
87 <citerefentry><refentrytitle>sd_event_add_inotify
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
88 <citerefentry><refentrytitle>sd_event_add_defer
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
89 <citerefentry><refentrytitle>sd_event_source_set_description
</refentrytitle><manvolnum>3</manvolnum></citerefentry>