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1 | <?xml version='1.0'?> <!--*-nxml-*--> |
2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" | |
12b42c76 | 3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
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4 | |
5 | <!-- | |
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6 | SPDX-License-Identifier: LGPL-2.1+ |
7 | ||
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8 | This file is part of systemd. |
9 | ||
10 | Copyright 2010 Lennart Poettering | |
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11 | --> |
12 | ||
56ba3c78 | 13 | <refentry id="sd_seat_get_active" conditional='HAVE_PAM'> |
0b3b020a | 14 | |
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15 | <refentryinfo> |
16 | <title>sd_seat_get_active</title> | |
17 | <productname>systemd</productname> | |
18 | ||
19 | <authorgroup> | |
20 | <author> | |
21 | <contrib>Developer</contrib> | |
22 | <firstname>Lennart</firstname> | |
23 | <surname>Poettering</surname> | |
24 | <email>lennart@poettering.net</email> | |
25 | </author> | |
26 | </authorgroup> | |
27 | </refentryinfo> | |
28 | ||
29 | <refmeta> | |
30 | <refentrytitle>sd_seat_get_active</refentrytitle> | |
31 | <manvolnum>3</manvolnum> | |
32 | </refmeta> | |
33 | ||
34 | <refnamediv> | |
35 | <refname>sd_seat_get_active</refname> | |
36 | <refname>sd_seat_get_sessions</refname> | |
37 | <refname>sd_seat_can_multi_session</refname> | |
38 | <refname>sd_seat_can_tty</refname> | |
39 | <refname>sd_seat_can_graphical</refname> | |
40 | <refpurpose>Determine state of a specific seat</refpurpose> | |
41 | </refnamediv> | |
42 | ||
43 | <refsynopsisdiv> | |
44 | <funcsynopsis> | |
45 | <funcsynopsisinfo>#include <systemd/sd-login.h></funcsynopsisinfo> | |
46 | ||
47 | <funcprototype> | |
48 | <funcdef>int <function>sd_seat_get_active</function></funcdef> | |
49 | <paramdef>const char *<parameter>seat</parameter></paramdef> | |
50 | <paramdef>char **<parameter>session</parameter></paramdef> | |
51 | <paramdef>uid_t *<parameter>uid</parameter></paramdef> | |
52 | </funcprototype> | |
53 | ||
54 | <funcprototype> | |
55 | <funcdef>int <function>sd_seat_get_sessions</function></funcdef> | |
56 | <paramdef>const char *<parameter>seat</parameter></paramdef> | |
57 | <paramdef>char ***<parameter>sessions</parameter></paramdef> | |
58 | <paramdef>uid_t **<parameter>uid</parameter></paramdef> | |
59 | <paramdef>unsigned int *<parameter>n_uids</parameter></paramdef> | |
60 | </funcprototype> | |
61 | ||
62 | <funcprototype> | |
63 | <funcdef>int <function>sd_seat_can_multi_session</function></funcdef> | |
64 | <paramdef>const char *<parameter>seat</parameter></paramdef> | |
65 | </funcprototype> | |
66 | ||
67 | <funcprototype> | |
68 | <funcdef>int <function>sd_seat_can_tty</function></funcdef> | |
69 | <paramdef>const char *<parameter>seat</parameter></paramdef> | |
70 | </funcprototype> | |
71 | ||
72 | <funcprototype> | |
73 | <funcdef>int <function>sd_seat_can_graphical</function></funcdef> | |
74 | <paramdef>const char *<parameter>seat</parameter></paramdef> | |
75 | </funcprototype> | |
76 | </funcsynopsis> | |
77 | </refsynopsisdiv> | |
78 | ||
79 | <refsect1> | |
80 | <title>Description</title> | |
81 | ||
82 | <para><function>sd_seat_get_active()</function> may be used to | |
83 | determine which session is currently active on a seat, if there is | |
84 | any. Returns the session identifier and the user identifier of the | |
85 | Unix user the session is belonging to. Either the session or the | |
86 | user identifier parameter can be passed <constant>NULL</constant>, | |
87 | in case only one of the parameters shall be queried. The returned | |
88 | string needs to be freed with the libc | |
89 | <citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
90 | call after use.</para> | |
91 | ||
92 | <para><function>sd_seat_get_sessions()</function> may be used to | |
93 | determine all sessions on the specified seat. Returns two arrays, | |
94 | one (<constant>NULL</constant> terminated) with the session | |
95 | identifiers of the sessions and one with the user identifiers of | |
96 | the Unix users the sessions belong to. An additional parameter may | |
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97 | be used to return the number of entries in the latter array. This |
98 | value is the same the return value, if the latter is nonnegative. | |
99 | The two arrays and the last parameter may be passed as | |
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100 | <constant>NULL</constant> in case these values need not to be |
101 | determined. The arrays and the strings referenced by them need to | |
102 | be freed with the libc | |
103 | <citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
104 | call after use. Note that instead of an empty array | |
105 | <constant>NULL</constant> may be returned and should be considered | |
106 | equivalent to an empty array.</para> | |
107 | ||
108 | <para><function>sd_seat_can_multi_session()</function> may be used | |
109 | to determine whether a specific seat is capable of multi-session, | |
110 | i.e. allows multiple login sessions in parallel (with only one | |
111 | being active at a time).</para> | |
112 | ||
113 | <para><function>sd_seat_can_tty()</function> may be used to | |
114 | determine whether a specific seat provides TTY functionality, i.e. | |
115 | is useful as a text console.</para> | |
116 | ||
117 | <para><function>sd_seat_can_graphical()</function> may be used to | |
118 | determine whether a specific seat provides graphics functionality, | |
119 | i.e. is useful as a graphics display.</para> | |
120 | ||
121 | <para>If the <varname>seat</varname> parameter of any of these | |
122 | functions is passed as <constant>NULL</constant>, the operation is | |
123 | executed for the seat of the session of the calling process, if | |
124 | there is any.</para> | |
125 | </refsect1> | |
126 | ||
127 | <refsect1> | |
128 | <title>Return Value</title> | |
129 | ||
130 | <para> On success, <function>sd_seat_get_active()</function> | |
131 | returns 0 or a positive integer. On success, | |
132 | <function>sd_seat_get_sessions()</function> returns the number of | |
133 | entries in the session identifier array. If the test succeeds, | |
134 | <function>sd_seat_can_multi_session</function>, | |
135 | <function>sd_seat_can_tty</function> and | |
136 | <function>sd_seat_can_graphical</function> return a positive | |
137 | integer, if it fails 0. On failure, these calls return a negative | |
138 | errno-style error code.</para> | |
139 | </refsect1> | |
140 | ||
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141 | <refsect1> |
142 | <title>Errors</title> | |
143 | ||
144 | <para>Returned errors may indicate the following problems:</para> | |
145 | ||
146 | <variablelist> | |
147 | ||
148 | <varlistentry> | |
149 | <term><constant>-ENODATA</constant></term> | |
150 | ||
a8eaaee7 | 151 | <listitem><para>The given field is not specified for the described |
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152 | seat.</para> |
153 | </listitem> | |
154 | </varlistentry> | |
155 | ||
156 | <varlistentry> | |
157 | <term><constant>-ENXIO</constant></term> | |
158 | ||
159 | <listitem><para>The specified seat is unknown.</para> | |
160 | </listitem> | |
161 | </varlistentry> | |
162 | ||
163 | <varlistentry> | |
164 | <term><constant>-EINVAL</constant></term> | |
165 | ||
166 | <listitem><para>An input parameter was invalid (out of range, | |
7ca41557 | 167 | or NULL, where that is not accepted).</para></listitem> |
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168 | </varlistentry> |
169 | ||
170 | <varlistentry> | |
171 | <term><constant>-ENOMEM</constant></term> | |
172 | ||
173 | <listitem><para>Memory allocation failed.</para></listitem> | |
174 | </varlistentry> | |
175 | </variablelist> | |
176 | </refsect1> | |
177 | ||
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178 | <refsect1> |
179 | <title>Notes</title> | |
180 | ||
181 | <para>The <function>sd_seat_get_active()</function>, | |
182 | <function>sd_seat_get_sessions()</function>, | |
183 | <function>sd_seat_can_multi_session()</function>, | |
184 | <function>sd_seat_can_tty()</function> and | |
7f3fdb7f | 185 | <function>sd_seat_can_graphical()</function> interfaces are |
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186 | available as a shared library, which can be compiled and linked to |
187 | with the | |
188 | <constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
189 | file.</para> | |
190 | </refsect1> | |
191 | ||
192 | <refsect1> | |
193 | <title>See Also</title> | |
194 | ||
195 | <para> | |
196 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
197 | <citerefentry><refentrytitle>sd-login</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
198 | <citerefentry><refentrytitle>sd_session_get_seat</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
199 | </para> | |
200 | </refsect1> | |
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201 | |
202 | </refentry> |