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+
9 <refentry id=
"sd_event_source_set_userdata" xmlns:
xi=
"http://www.w3.org/2001/XInclude">
12 <title>sd_event_source_set_userdata
</title>
13 <productname>systemd
</productname>
17 <refentrytitle>sd_event_source_set_userdata
</refentrytitle>
18 <manvolnum>3</manvolnum>
22 <refname>sd_event_source_set_userdata
</refname>
23 <refname>sd_event_source_get_userdata
</refname>
25 <refpurpose>Set or retrieve user data pointer of event sources
</refpurpose>
30 <funcsynopsisinfo>#include
<systemd/sd-event.h
></funcsynopsisinfo>
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>
39 <funcdef>void*
<function>sd_event_source_get_userdata
</function></funcdef>
40 <paramdef>sd_event_source *
<parameter>source
</parameter></paramdef>
47 <title>Description
</title>
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
54 <citerefentry><refentrytitle>sd_event_add_io
</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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>
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>
70 <title>Return Value
</title>
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
79 <xi:include href=
"libsystemd-pkgconfig.xml" />
82 <title>See Also
</title>
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_signal
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
89 <citerefentry><refentrytitle>sd_event_add_child
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
90 <citerefentry><refentrytitle>sd_event_add_inotify
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
91 <citerefentry><refentrytitle>sd_event_add_defer
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
92 <citerefentry><refentrytitle>sd_event_source_set_description
</refentrytitle><manvolnum>3</manvolnum></citerefentry>