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1 | <?xml version='1.0'?> <!--*-nxml-*--> | |
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+ --> | |
5 | ||
6 | <refentry id="sd_seat_get_active" conditional='HAVE_PAM' | |
7 | xmlns:xi="http://www.w3.org/2001/XInclude"> | |
8 | ||
9 | <refentryinfo> | |
10 | <title>sd_seat_get_active</title> | |
11 | <productname>systemd</productname> | |
12 | </refentryinfo> | |
13 | ||
14 | <refmeta> | |
15 | <refentrytitle>sd_seat_get_active</refentrytitle> | |
16 | <manvolnum>3</manvolnum> | |
17 | </refmeta> | |
18 | ||
19 | <refnamediv> | |
20 | <refname>sd_seat_get_active</refname> | |
21 | <refname>sd_seat_get_sessions</refname> | |
22 | <refname>sd_seat_can_multi_session</refname> | |
23 | <refname>sd_seat_can_tty</refname> | |
24 | <refname>sd_seat_can_graphical</refname> | |
25 | <refpurpose>Determine state of a specific seat</refpurpose> | |
26 | </refnamediv> | |
27 | ||
28 | <refsynopsisdiv> | |
29 | <funcsynopsis> | |
30 | <funcsynopsisinfo>#include <systemd/sd-login.h></funcsynopsisinfo> | |
31 | ||
32 | <funcprototype> | |
33 | <funcdef>int <function>sd_seat_get_active</function></funcdef> | |
34 | <paramdef>const char *<parameter>seat</parameter></paramdef> | |
35 | <paramdef>char **<parameter>session</parameter></paramdef> | |
36 | <paramdef>uid_t *<parameter>uid</parameter></paramdef> | |
37 | </funcprototype> | |
38 | ||
39 | <funcprototype> | |
40 | <funcdef>int <function>sd_seat_get_sessions</function></funcdef> | |
41 | <paramdef>const char *<parameter>seat</parameter></paramdef> | |
42 | <paramdef>char ***<parameter>sessions</parameter></paramdef> | |
43 | <paramdef>uid_t **<parameter>uid</parameter></paramdef> | |
44 | <paramdef>unsigned int *<parameter>n_uids</parameter></paramdef> | |
45 | </funcprototype> | |
46 | ||
47 | <funcprototype> | |
48 | <funcdef>int <function>sd_seat_can_multi_session</function></funcdef> | |
49 | <paramdef>const char *<parameter>seat</parameter></paramdef> | |
50 | </funcprototype> | |
51 | ||
52 | <funcprototype> | |
53 | <funcdef>int <function>sd_seat_can_tty</function></funcdef> | |
54 | <paramdef>const char *<parameter>seat</parameter></paramdef> | |
55 | </funcprototype> | |
56 | ||
57 | <funcprototype> | |
58 | <funcdef>int <function>sd_seat_can_graphical</function></funcdef> | |
59 | <paramdef>const char *<parameter>seat</parameter></paramdef> | |
60 | </funcprototype> | |
61 | </funcsynopsis> | |
62 | </refsynopsisdiv> | |
63 | ||
64 | <refsect1> | |
65 | <title>Description</title> | |
66 | ||
67 | <para><function>sd_seat_get_active()</function> may be used to | |
68 | determine which session is currently active on a seat, if there is | |
69 | any. Returns the session identifier and the user identifier of the | |
70 | Unix user the session is belonging to. Either the session or the | |
71 | user identifier parameter can be passed <constant>NULL</constant>, | |
72 | in case only one of the parameters shall be queried. The returned | |
73 | string needs to be freed with the libc | |
74 | <citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
75 | call after use.</para> | |
76 | ||
77 | <para><function>sd_seat_get_sessions()</function> may be used to | |
78 | determine all sessions on the specified seat. Returns two arrays, | |
79 | one (<constant>NULL</constant> terminated) with the session | |
80 | identifiers of the sessions and one with the user identifiers of | |
81 | the Unix users the sessions belong to. An additional parameter may | |
82 | be used to return the number of entries in the latter array. This | |
83 | value is the same the return value, if the latter is nonnegative. | |
84 | The two arrays and the last parameter may be passed as | |
85 | <constant>NULL</constant> in case these values need not to be | |
86 | determined. The arrays and the strings referenced by them need to | |
87 | be freed with the libc | |
88 | <citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
89 | call after use. Note that instead of an empty array | |
90 | <constant>NULL</constant> may be returned and should be considered | |
91 | equivalent to an empty array.</para> | |
92 | ||
93 | <para><function>sd_seat_can_multi_session()</function> may be used | |
94 | to determine whether a specific seat is capable of multi-session, | |
95 | i.e. allows multiple login sessions in parallel (with only one | |
96 | being active at a time).</para> | |
97 | ||
98 | <para><function>sd_seat_can_tty()</function> may be used to | |
99 | determine whether a specific seat provides TTY functionality, i.e. | |
100 | is useful as a text console.</para> | |
101 | ||
102 | <para><function>sd_seat_can_graphical()</function> may be used to | |
103 | determine whether a specific seat provides graphics functionality, | |
104 | i.e. is useful as a graphics display.</para> | |
105 | ||
106 | <para>If the <varname>seat</varname> parameter of any of these | |
107 | functions is passed as <constant>NULL</constant>, the operation is | |
108 | executed for the seat of the session of the calling process, if | |
109 | there is any.</para> | |
110 | </refsect1> | |
111 | ||
112 | <refsect1> | |
113 | <title>Return Value</title> | |
114 | ||
115 | <para> On success, <function>sd_seat_get_active()</function> returns 0 or a positive integer. On success, | |
116 | <function>sd_seat_get_sessions()</function> returns the number of entries in the session identifier | |
117 | array. If the test succeeds, <function>sd_seat_can_multi_session</function>, | |
118 | <function>sd_seat_can_tty</function> and <function>sd_seat_can_graphical</function> return a positive | |
119 | integer, if it fails 0. On failure, these calls return a negative errno-style error code.</para> | |
120 | ||
121 | <refsect2> | |
122 | <title>Errors</title> | |
123 | ||
124 | <para>Returned errors may indicate the following problems:</para> | |
125 | ||
126 | <variablelist> | |
127 | ||
128 | <varlistentry> | |
129 | <term><constant>-ENODATA</constant></term> | |
130 | ||
131 | <listitem><para>The given field is not specified for the described seat.</para> | |
132 | </listitem> | |
133 | </varlistentry> | |
134 | ||
135 | <varlistentry> | |
136 | <term><constant>-ENXIO</constant></term> | |
137 | ||
138 | <listitem><para>The specified seat is unknown.</para> | |
139 | </listitem> | |
140 | </varlistentry> | |
141 | ||
142 | <varlistentry> | |
143 | <term><constant>-EINVAL</constant></term> | |
144 | ||
145 | <listitem><para>An input parameter was invalid (out of range, or <constant>NULL</constant>, where | |
146 | that is not accepted).</para></listitem> | |
147 | </varlistentry> | |
148 | ||
149 | <varlistentry> | |
150 | <term><constant>-ENOMEM</constant></term> | |
151 | ||
152 | <listitem><para>Memory allocation failed.</para></listitem> | |
153 | </varlistentry> | |
154 | </variablelist> | |
155 | </refsect2> | |
156 | </refsect1> | |
157 | ||
158 | <xi:include href="libsystemd-pkgconfig.xml" /> | |
159 | ||
160 | <refsect1> | |
161 | <title>See Also</title> | |
162 | ||
163 | <para> | |
164 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
165 | <citerefentry><refentrytitle>sd-login</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
166 | <citerefentry><refentrytitle>sd_session_get_seat</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
167 | </para> | |
168 | </refsect1> | |
169 | ||
170 | </refentry> |