[thirdparty/systemd.git] / man / sd_login_monitor_new.xml

<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
        "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">

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<refentry id="sd_login_monitor_new">

        <refentryinfo>
                <title>sd_login_monitor_new</title>
                <productname>systemd</productname>

                <authorgroup>
                        <author>
                                <contrib>Developer</contrib>
                                <firstname>Lennart</firstname>
                                <surname>Poettering</surname>
                                <email>lennart@poettering.net</email>
                        </author>
                </authorgroup>
        </refentryinfo>

        <refmeta>
                <refentrytitle>sd_login_monitor_new</refentrytitle>
                <manvolnum>3</manvolnum>
        </refmeta>

        <refnamediv>
                <refname>sd_login_monitor_new</refname>
                <refname>sd_login_monitor_unref</refname>
                <refname>sd_login_monitor_flush</refname>
                <refname>sd_login_monitor_get_fd</refname>
                <refpurpose>Monitor login sessions, seats and users</refpurpose>
        </refnamediv>

        <refsynopsisdiv>
                <funcsynopsis>
                        <funcsynopsisinfo>#include &lt;systemd/sd-login.h&gt;</funcsynopsisinfo>

                        <funcprototype>
                                <funcdef>int <function>sd_login_monitor_new</function></funcdef>
                                <paramdef>const char* <parameter>category</parameter></paramdef>
                                <paramdef>sd_login_monitor** <parameter>ret</parameter></paramdef>
                        </funcprototype>

                        <funcprototype>
                                <funcdef>sd_login_monitor* <function>sd_login_monitor_unref</function></funcdef>
                                <paramdef>sd_login_monitor* <parameter>m</parameter></paramdef>
                        </funcprototype>

                        <funcprototype>
                                <funcdef>int <function>sd_login_monitor_flush</function></funcdef>
                                <paramdef>sd_login_monitor* <parameter>m</parameter></paramdef>
                        </funcprototype>

                        <funcprototype>
                                <funcdef>int <function>sd_login_monitor_get_fd</function></funcdef>
                                <paramdef>sd_login_monitor* <parameter>m</parameter></paramdef>
                        </funcprototype>

                </funcsynopsis>
        </refsynopsisdiv>

        <refsect1>
                <title>Description</title>

                <para><function>sd_login_monitor_new()</function> may
                be used to monitor login session, users and seats. Via
                a monitor object a file descriptor can be integrated
                into an application defined event loop which is woken
                up each time a user logs in, logs out or a seat is
                added or removed, or a session, user, or seat changes
                state otherwise. The first parameter takes a string
                which can be either <literal>seat</literal> (to get
                only notifications about seats being added, removed or
                changed), <literal>session</literal> (to get only
                notifications about sessions being created or removed
                or changed) or <literal>uid</literal> (to get only
                notifications when a user changes state in respect to
                logins). If notifications shall be generated in all
                these conditions, NULL may be passed. Note that in
                future additional categories may be defined. The
                second parameter returns a monitor object and needs to
                be freed with the
                <function>sd_login_monitor_unref()</function> call
                after use.</para>

                <para><function>sd_login_monitor_unref()</function>
                may be used to destroy a monitor object. Note that
                this will invalidate any file descriptor returned by
                <function>sd_login_monitor_get_fd()</function>.</para>

                <para><function>sd_login_monitor_flush()</function>
                may be used to reset the wakeup state of the monitor
                object. Whenever an event causes the monitor to wake
                up the event loop via the file descriptor this
                function needs to be called to reset the wake-up
                state. If this call is not invoked the file descriptor
                will immediately wake up the event loop again.</para>

                <para><function>sd_login_monitor_get_fd()</function>
                may be used to retrieve the file descriptor of the
                monitor object that may be integrated in an
                application defined event loop, based around
                <citerefentry><refentrytitle>poll</refentrytitle><manvolnum>2</manvolnum></citerefentry>
                or a similar interface. The application should include
                the returned file descriptor as wake up source for
                POLLIN events. Whenever a wake-up is triggered the
                file descriptor needs to be reset via
                <function>sd_login_monitor_flush()</function>. An
                application needs to reread the login state with a
                function like
                <citerefentry><refentrytitle>sd_get_seats</refentrytitle><manvolnum>3</manvolnum></citerefentry>
                or similar to determine what changed.</para>
        </refsect1>

        <refsect1>
                <title>Return Value</title>

                <para>On success
                <function>sd_login_monitor_new()</function> and
                <function>sd_login_monitor_flush()</function> return 0
                or a positive integer. On success
                <function>sd_login_monitor_get_fd()</function> returns
                a Unix file descriptor. On failure, these calls return
                a negative errno-style error code.</para>

                <para><function>sd_login_monitor_unref()</function>
                always returns NULL.</para>
        </refsect1>

        <refsect1>
                <title>Notes</title>

                <para>The <function>sd_login_monitor_new()</function>,
                <function>sd_login_monitor_unref()</function>, <function>sd_login_monitor_flush()</function> and
                <function>sd_login_monitor_get_fd()</function> interfaces
                are available as shared library, which can be compiled
                and linked to with the
                <literal>libsystemd-login</literal>
                <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
                file.</para>
        </refsect1>

        <refsect1>
                <title>See Also</title>

                <para>
                        <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>sd-login</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>sd_get_seats</refentrytitle><manvolnum>3</manvolnum></citerefentry>
                </para>
        </refsect1>

</refentry>
Commit	Line	Data
0b3b020a LP	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">
	4
	5	<!--
	6	This file is part of systemd.
	7
	8	Copyright 2010 Lennart Poettering
	9
	10	systemd is free software; you can redistribute it and/or modify it
5430f7f2 LP	11	under the terms of the GNU Lesser General Public License as published by
5430f7f2 LP	12	the Free Software Foundation; either version 2.1 of the License, or
0b3b020a LP	13	(at your option) any later version.
	14
	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
5430f7f2	18	Lesser General Public License for more details.
0b3b020a	19
5430f7f2	20	You should have received a copy of the GNU Lesser General Public License
0b3b020a LP	21	along with systemd; If not, see <http://www.gnu.org/licenses/>.
	22	-->
	23
	24	<refentry id="sd_login_monitor_new">
	25
	26	<refentryinfo>
	27	<title>sd_login_monitor_new</title>
	28	<productname>systemd</productname>
	29
	30	<authorgroup>
	31	<author>
	32	<contrib>Developer</contrib>
	33	<firstname>Lennart</firstname>
	34	<surname>Poettering</surname>
	35	<email>lennart@poettering.net</email>
	36	</author>
	37	</authorgroup>
	38	</refentryinfo>
	39
	40	<refmeta>
	41	<refentrytitle>sd_login_monitor_new</refentrytitle>
	42	<manvolnum>3</manvolnum>
	43	</refmeta>
	44
	45	<refnamediv>
	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	<refpurpose>Monitor login sessions, seats and users</refpurpose>
	51	</refnamediv>
	52
	53	<refsynopsisdiv>
	54	<funcsynopsis>
	55	<funcsynopsisinfo>#include <systemd/sd-login.h></funcsynopsisinfo>
	56
	57	<funcprototype>
	58	<funcdef>int <function>sd_login_monitor_new</function></funcdef>
	59	<paramdef>const char* <parameter>category</parameter></paramdef>
	60	<paramdef>sd_login_monitor** <parameter>ret</parameter></paramdef>
	61	</funcprototype>
	62
	63	<funcprototype>
	64	<funcdef>sd_login_monitor* <function>sd_login_monitor_unref</function></funcdef>
	65	<paramdef>sd_login_monitor* <parameter>m</parameter></paramdef>
	66	</funcprototype>
	67
	68	<funcprototype>
	69	<funcdef>int <function>sd_login_monitor_flush</function></funcdef>
	70	<paramdef>sd_login_monitor* <parameter>m</parameter></paramdef>
	71	</funcprototype>
	72
	73	<funcprototype>
	74	<funcdef>int <function>sd_login_monitor_get_fd</function></funcdef>
	75	<paramdef>sd_login_monitor* <parameter>m</parameter></paramdef>
	76	</funcprototype>
	77
	78	</funcsynopsis>
	79	</refsynopsisdiv>
	80
	81	<refsect1>
	82	<title>Description</title>
	83
	84	<para><function>sd_login_monitor_new()</function> may
85	be used to monitor login session, users and seats. Via
86	a monitor object a file descriptor can be integrated
87	into an application defined event loop which is woken
88	up each time a user logs in, logs out or a seat is
89	added or removed, or a session, user, or seat changes
90	state otherwise. The first parameter takes a string
91	which can be either <literal>seat</literal> (to get
92	only notifications about seats being added, removed or
93	changed), <literal>session</literal> (to get only
94	notifications about sessions being created or removed
95	or changed) or <literal>uid</literal> (to get only
96	notifications when a user changes state in respect to
97	logins). If notifications shall be generated in all
98	these conditions, NULL may be passed. Note that in
99	future additional categories may be defined. The
100	second parameter returns a monitor object and needs to
101	be freed with the
102	<function>sd_login_monitor_unref()</function> call
103	after use.</para>
104
105	<para><function>sd_login_monitor_unref()</function>
106	may be used to destroy a monitor object. Note that
107	this will invalidate any file descriptor returned by
108	<function>sd_login_monitor_get_fd()</function>.</para>
109
110	<para><function>sd_login_monitor_flush()</function>
111	may be used to reset the wakeup state of the monitor
112	object. Whenever an event causes the monitor to wake
113	up the event loop via the file descriptor this
114	function needs to be called to reset the wake-up
115	state. If this call is not invoked the file descriptor
116	will immediately wake up the event loop again.</para>
117
118	<para><function>sd_login_monitor_get_fd()</function>
119	may be used to retrieve the file descriptor of the
120	monitor object that may be integrated in an
121	application defined event loop, based around
122	<citerefentry><refentrytitle>poll</refentrytitle><manvolnum>2</manvolnum></citerefentry>
123	or a similar interface. The application should include
124	the returned file descriptor as wake up source for
125	POLLIN events. Whenever a wake-up is triggered the
126	file descriptor needs to be reset via
127	<function>sd_login_monitor_flush()</function>. An
128	application needs to reread the login state with a
129	function like
130	<citerefentry><refentrytitle>sd_get_seats</refentrytitle><manvolnum>3</manvolnum></citerefentry>
131	or similar to determine what changed.</para>
132	</refsect1>
133
134	<refsect1>
135	<title>Return Value</title>
136
137	<para>On success
138	<function>sd_login_monitor_new()</function> and
139	<function>sd_login_monitor_flush()</function> return 0
140	or a positive integer. On success
141	<function>sd_login_monitor_get_fd()</function> returns
142	a Unix file descriptor. On failure, these calls return
143	a negative errno-style error code.</para>
144
145	<para><function>sd_login_monitor_unref()</function>
146	always returns NULL.</para>
147	</refsect1>
148
149	<refsect1>
150	<title>Notes</title>
151
152	<para>The <function>sd_login_monitor_new()</function>,
153	<function>sd_login_monitor_unref()</function>, <function>sd_login_monitor_flush()</function> and
154	<function>sd_login_monitor_get_fd()</function> interfaces
155	are available as shared library, which can be compiled
156	and linked to with the
157	<literal>libsystemd-login</literal>
158	<citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
159	file.</para>
160	</refsect1>
161
162	<refsect1>
163	<title>See Also</title>
164
165	<para>
166	<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
167	<citerefentry><refentrytitle>sd-login</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
595aae37	168	<citerefentry><refentrytitle>sd_get_seats</refentrytitle><manvolnum>3</manvolnum></citerefentry>
0b3b020a LP	169	</para>
	170	</refsect1>
	171
	172	</refentry>