1 <?xml version='1.0'?> <!--*-nxml-*-->
2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
6 This file is part of elogind.
8 Copyright 2010 Lennart Poettering
10 elogind is free software; you can redistribute it and/or modify it
11 under the terms of the GNU Lesser General Public License as published by
12 the Free Software Foundation; either version 2.1 of the License, or
13 (at your option) any later version.
15 elogind is distributed in the hope that it will be useful, but
16 WITHOUT ANY WARRANTY; without even the implied warranty of
17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 Lesser General Public License for more details.
20 You should have received a copy of the GNU Lesser General Public License
21 along with elogind; If not, see <http://www.gnu.org/licenses/>.
24 <refentry id="sd_seat_get_active" conditional='HAVE_PAM'>
27 <title>sd_seat_get_active</title>
28 <productname>elogind</productname>
32 <contrib>Developer</contrib>
33 <firstname>Lennart</firstname>
34 <surname>Poettering</surname>
35 <email>lennart@poettering.net</email>
41 <refentrytitle>sd_seat_get_active</refentrytitle>
42 <manvolnum>3</manvolnum>
46 <refname>sd_seat_get_active</refname>
47 <refname>sd_seat_get_sessions</refname>
48 <refname>sd_seat_can_multi_session</refname>
49 <refname>sd_seat_can_tty</refname>
50 <refname>sd_seat_can_graphical</refname>
51 <refpurpose>Determine state of a specific seat</refpurpose>
56 <funcsynopsisinfo>#include <elogind/sd-login.h></funcsynopsisinfo>
59 <funcdef>int <function>sd_seat_get_active</function></funcdef>
60 <paramdef>const char *<parameter>seat</parameter></paramdef>
61 <paramdef>char **<parameter>session</parameter></paramdef>
62 <paramdef>uid_t *<parameter>uid</parameter></paramdef>
66 <funcdef>int <function>sd_seat_get_sessions</function></funcdef>
67 <paramdef>const char *<parameter>seat</parameter></paramdef>
68 <paramdef>char ***<parameter>sessions</parameter></paramdef>
69 <paramdef>uid_t **<parameter>uid</parameter></paramdef>
70 <paramdef>unsigned int *<parameter>n_uids</parameter></paramdef>
74 <funcdef>int <function>sd_seat_can_multi_session</function></funcdef>
75 <paramdef>const char *<parameter>seat</parameter></paramdef>
79 <funcdef>int <function>sd_seat_can_tty</function></funcdef>
80 <paramdef>const char *<parameter>seat</parameter></paramdef>
84 <funcdef>int <function>sd_seat_can_graphical</function></funcdef>
85 <paramdef>const char *<parameter>seat</parameter></paramdef>
91 <title>Description</title>
93 <para><function>sd_seat_get_active()</function> may be used to
94 determine which session is currently active on a seat, if there is
95 any. Returns the session identifier and the user identifier of the
96 Unix user the session is belonging to. Either the session or the
97 user identifier parameter can be passed <constant>NULL</constant>,
98 in case only one of the parameters shall be queried. The returned
99 string needs to be freed with the libc
100 <citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
101 call after use.</para>
103 <para><function>sd_seat_get_sessions()</function> may be used to
104 determine all sessions on the specified seat. Returns two arrays,
105 one (<constant>NULL</constant> terminated) with the session
106 identifiers of the sessions and one with the user identifiers of
107 the Unix users the sessions belong to. An additional parameter may
108 be used to return the number of entries in the latter array. This
109 value is the same the return value, if the latter is nonnegative.
110 The two arrays and the last parameter may be passed as
111 <constant>NULL</constant> in case these values need not to be
112 determined. The arrays and the strings referenced by them need to
113 be freed with the libc
114 <citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
115 call after use. Note that instead of an empty array
116 <constant>NULL</constant> may be returned and should be considered
117 equivalent to an empty array.</para>
119 <para><function>sd_seat_can_multi_session()</function> may be used
120 to determine whether a specific seat is capable of multi-session,
121 i.e. allows multiple login sessions in parallel (with only one
122 being active at a time).</para>
124 <para><function>sd_seat_can_tty()</function> may be used to
125 determine whether a specific seat provides TTY functionality, i.e.
126 is useful as a text console.</para>
128 <para><function>sd_seat_can_graphical()</function> may be used to
129 determine whether a specific seat provides graphics functionality,
130 i.e. is useful as a graphics display.</para>
132 <para>If the <varname>seat</varname> parameter of any of these
133 functions is passed as <constant>NULL</constant>, the operation is
134 executed for the seat of the session of the calling process, if
139 <title>Return Value</title>
141 <para> On success, <function>sd_seat_get_active()</function>
142 returns 0 or a positive integer. On success,
143 <function>sd_seat_get_sessions()</function> returns the number of
144 entries in the session identifier array. If the test succeeds,
145 <function>sd_seat_can_multi_session</function>,
146 <function>sd_seat_can_tty</function> and
147 <function>sd_seat_can_graphical</function> return a positive
148 integer, if it fails 0. On failure, these calls return a negative
149 errno-style error code.</para>
153 <title>Errors</title>
155 <para>Returned errors may indicate the following problems:</para>
160 <term><constant>-ENODATA</constant></term>
162 <listitem><para>The given field is not specified for the described
168 <term><constant>-ENXIO</constant></term>
170 <listitem><para>The specified seat is unknown.</para>
175 <term><constant>-EINVAL</constant></term>
177 <listitem><para>An input parameter was invalid (out of range,
178 or NULL, where that is not accepted).</para></listitem>
182 <term><constant>-ENOMEM</constant></term>
184 <listitem><para>Memory allocation failed.</para></listitem>
192 <para>The <function>sd_seat_get_active()</function>,
193 <function>sd_seat_get_sessions()</function>,
194 <function>sd_seat_can_multi_session()</function>,
195 <function>sd_seat_can_tty()</function> and
196 <function>sd_seat_can_graphical()</function> interfaces are
197 available as a shared library, which can be compiled and linked to
199 <constant>libelogind</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
204 <title>See Also</title>
207 <citerefentry><refentrytitle>elogind</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
208 <citerefentry><refentrytitle>sd-login</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
209 <citerefentry><refentrytitle>sd_session_get_seat</refentrytitle><manvolnum>3</manvolnum></citerefentry>