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 systemd.
8 Copyright 2010 Lennart Poettering
10 systemd 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 systemd 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 systemd; If not, see <http://www.gnu.org/licenses/>.
24 <refentry id="sd_login_monitor_new" conditional='HAVE_PAM'>
27 <title>sd_login_monitor_new</title>
28 <productname>systemd</productname>
32 <contrib>Developer</contrib>
33 <firstname>Lennart</firstname>
34 <surname>Poettering</surname>
35 <email>lennart@poettering.net</email>
41 <refentrytitle>sd_login_monitor_new</refentrytitle>
42 <manvolnum>3</manvolnum>
46 <refname>sd_login_monitor_new</refname>
47 <refname>sd_login_monitor_unref</refname>
48 <refname>sd_login_monitor_flush</refname>
49 <refname>sd_login_monitor_get_fd</refname>
50 <refname>sd_login_monitor</refname>
51 <refpurpose>Monitor login sessions, seats and users</refpurpose>
56 <funcsynopsisinfo>#include <systemd/sd-login.h></funcsynopsisinfo>
59 <funcdef>int <function>sd_login_monitor_new</function></funcdef>
60 <paramdef>const char* <parameter>category</parameter></paramdef>
61 <paramdef>sd_login_monitor** <parameter>ret</parameter></paramdef>
65 <funcdef>sd_login_monitor* <function>sd_login_monitor_unref</function></funcdef>
66 <paramdef>sd_login_monitor* <parameter>m</parameter></paramdef>
70 <funcdef>int <function>sd_login_monitor_flush</function></funcdef>
71 <paramdef>sd_login_monitor* <parameter>m</parameter></paramdef>
75 <funcdef>int <function>sd_login_monitor_get_fd</function></funcdef>
76 <paramdef>sd_login_monitor* <parameter>m</parameter></paramdef>
83 <title>Description</title>
85 <para><function>sd_login_monitor_new()</function> may
86 be used to monitor login sessions, users and seats. Via
87 a monitor object a file descriptor can be integrated
88 into an application defined event loop which is woken
89 up each time a user logs in, logs out or a seat is
90 added or removed, or a session, user, or seat changes
91 state otherwise. The first parameter takes a string
92 which can be <literal>seat</literal> (to get
93 only notifications about seats being added, removed or
94 changed), <literal>session</literal> (to get only
95 notifications about sessions being created or removed
96 or changed) or <literal>uid</literal> (to get only
97 notifications when a user changes state in respect to
98 logins). If notifications shall be generated in all
99 these conditions, NULL may be passed. Note that in the
100 future additional categories may be defined. The
101 second parameter returns a monitor object and needs to
103 <function>sd_login_monitor_unref()</function> call
106 <para><function>sd_login_monitor_unref()</function>
107 may be used to destroy a monitor object. Note that
108 this will invalidate any file descriptor returned by
109 <function>sd_login_monitor_get_fd()</function>.</para>
111 <para><function>sd_login_monitor_flush()</function>
112 may be used to reset the wakeup state of the monitor
113 object. Whenever an event causes the monitor to wake
114 up the event loop via the file descriptor this
115 function needs to be called to reset the wake-up
116 state. If this call is not invoked the file descriptor
117 will immediately wake up the event loop again.</para>
119 <para><function>sd_login_monitor_get_fd()</function>
120 may be used to retrieve the file descriptor of the
121 monitor object that may be integrated in an
122 application defined event loop, based around
123 <citerefentry><refentrytitle>poll</refentrytitle><manvolnum>2</manvolnum></citerefentry>
124 or a similar interface. The application should include
125 the returned file descriptor as wake up source for
126 POLLIN events. Whenever a wake-up is triggered the
127 file descriptor needs to be reset via
128 <function>sd_login_monitor_flush()</function>. An
129 application needs to reread the login state with a
131 <citerefentry><refentrytitle>sd_get_seats</refentrytitle><manvolnum>3</manvolnum></citerefentry>
132 or similar to determine what changed.</para>
136 <title>Return Value</title>
139 <function>sd_login_monitor_new()</function> and
140 <function>sd_login_monitor_flush()</function> return 0
141 or a positive integer. On success
142 <function>sd_login_monitor_get_fd()</function> returns
143 a Unix file descriptor. On failure, these calls return
144 a negative errno-style error code.</para>
146 <para><function>sd_login_monitor_unref()</function>
147 always returns NULL.</para>
153 <para>The <function>sd_login_monitor_new()</function>,
154 <function>sd_login_monitor_unref()</function>, <function>sd_login_monitor_flush()</function> and
155 <function>sd_login_monitor_get_fd()</function> interfaces
156 are available as shared library, which can be compiled
157 and linked to with the
158 <literal>libsystemd-login</literal>
159 <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
164 <title>See Also</title>
167 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
168 <citerefentry><refentrytitle>sd-login</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
169 <citerefentry><refentrytitle>sd_get_seats</refentrytitle><manvolnum>3</manvolnum></citerefentry>