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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 | |
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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 | |
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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 |
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21 | along with systemd; If not, see <http://www.gnu.org/licenses/>. |
22 | --> | |
23 | ||
56ba3c78 | 24 | <refentry id="sd_login_monitor_new" conditional='HAVE_PAM'> |
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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> | |
dace83cb | 50 | <refname>sd_login_monitor_get_events</refname> |
667c24a6 | 51 | <refname>sd_login_monitor_get_timeout</refname> |
976c46f8 | 52 | <refname>sd_login_monitor</refname> |
e10375f2 | 53 | <refpurpose>Monitor login sessions, seats, users and virtual machines/containers</refpurpose> |
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54 | </refnamediv> |
55 | ||
56 | <refsynopsisdiv> | |
57 | <funcsynopsis> | |
58 | <funcsynopsisinfo>#include <systemd/sd-login.h></funcsynopsisinfo> | |
59 | ||
60 | <funcprototype> | |
61 | <funcdef>int <function>sd_login_monitor_new</function></funcdef> | |
62 | <paramdef>const char* <parameter>category</parameter></paramdef> | |
63 | <paramdef>sd_login_monitor** <parameter>ret</parameter></paramdef> | |
64 | </funcprototype> | |
65 | ||
66 | <funcprototype> | |
67 | <funcdef>sd_login_monitor* <function>sd_login_monitor_unref</function></funcdef> | |
68 | <paramdef>sd_login_monitor* <parameter>m</parameter></paramdef> | |
69 | </funcprototype> | |
70 | ||
71 | <funcprototype> | |
72 | <funcdef>int <function>sd_login_monitor_flush</function></funcdef> | |
73 | <paramdef>sd_login_monitor* <parameter>m</parameter></paramdef> | |
74 | </funcprototype> | |
75 | ||
76 | <funcprototype> | |
77 | <funcdef>int <function>sd_login_monitor_get_fd</function></funcdef> | |
78 | <paramdef>sd_login_monitor* <parameter>m</parameter></paramdef> | |
79 | </funcprototype> | |
80 | ||
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81 | <funcprototype> |
82 | <funcdef>int <function>sd_login_monitor_get_events</function></funcdef> | |
83 | <paramdef>sd_login_monitor* <parameter>m</parameter></paramdef> | |
84 | </funcprototype> | |
85 | ||
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86 | <funcprototype> |
87 | <funcdef>int <function>sd_login_monitor_get_timeout</function></funcdef> | |
88 | <paramdef>sd_login_monitor* <parameter>m</parameter></paramdef> | |
89 | <paramdef>uint64_t* <parameter>timeout_usec</parameter></paramdef> | |
90 | </funcprototype> | |
91 | ||
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92 | </funcsynopsis> |
93 | </refsynopsisdiv> | |
94 | ||
95 | <refsect1> | |
96 | <title>Description</title> | |
97 | ||
98 | <para><function>sd_login_monitor_new()</function> may | |
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99 | be used to monitor login sessions, users, seats and |
100 | virtual machines/containers. Via a monitor object a | |
101 | file descriptor can be integrated into an application | |
102 | defined event loop which is woken up each time a user | |
103 | logs in, logs out or a seat is added or removed, or a | |
104 | session, user, seat or virtual machine/container | |
105 | changes state otherwise. The first parameter takes a | |
106 | string which can be <literal>seat</literal> (to get | |
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107 | only notifications about seats being added, removed or |
108 | changed), <literal>session</literal> (to get only | |
109 | notifications about sessions being created or removed | |
e10375f2 | 110 | or changed), <literal>uid</literal> (to get only |
0b3b020a | 111 | notifications when a user changes state in respect to |
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112 | logins) or <literal>machine</literal> (to get only |
113 | notifications when a virtual machine or container is | |
114 | started or stopped). If notifications shall be | |
115 | generated in all these conditions, NULL may be | |
116 | passed. Note that in the future additional categories | |
117 | may be defined. The second parameter returns a monitor | |
118 | object and needs to be freed with the | |
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119 | <function>sd_login_monitor_unref()</function> call |
120 | after use.</para> | |
121 | ||
122 | <para><function>sd_login_monitor_unref()</function> | |
123 | may be used to destroy a monitor object. Note that | |
124 | this will invalidate any file descriptor returned by | |
125 | <function>sd_login_monitor_get_fd()</function>.</para> | |
126 | ||
127 | <para><function>sd_login_monitor_flush()</function> | |
128 | may be used to reset the wakeup state of the monitor | |
129 | object. Whenever an event causes the monitor to wake | |
130 | up the event loop via the file descriptor this | |
131 | function needs to be called to reset the wake-up | |
132 | state. If this call is not invoked the file descriptor | |
133 | will immediately wake up the event loop again.</para> | |
134 | ||
135 | <para><function>sd_login_monitor_get_fd()</function> | |
136 | may be used to retrieve the file descriptor of the | |
137 | monitor object that may be integrated in an | |
138 | application defined event loop, based around | |
139 | <citerefentry><refentrytitle>poll</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
140 | or a similar interface. The application should include | |
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141 | the returned file descriptor as wake-up source for the |
142 | events mask returned by | |
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143 | <function>sd_login_monitor_get_events()</function>. It |
144 | should pass a timeout value as returned by | |
145 | <function>sd_login_monitor_get_timeout()</function>. Whenever | |
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146 | a wake-up is triggered the file descriptor needs to be |
147 | reset via | |
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148 | <function>sd_login_monitor_flush()</function>. An |
149 | application needs to reread the login state with a | |
150 | function like | |
151 | <citerefentry><refentrytitle>sd_get_seats</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
152 | or similar to determine what changed.</para> | |
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153 | |
154 | <para><function>sd_login_monitor_get_events()</function> | |
155 | will return the <function>poll()</function> mask to | |
156 | wait for. This function will return a combination of | |
157 | <literal>POLLIN</literal>, <literal>POLLOUT</literal> | |
158 | and similar to fill into the | |
159 | <literal>.events</literal> field of <literal>struct | |
160 | pollfd</literal>.</para> | |
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161 | |
162 | <para><function>sd_login_monitor_get_timeout()</function> | |
163 | will return a timeout value for usage in | |
164 | <function>poll()</function>. This returns a value in | |
165 | microseconds since the epoch of CLOCK_MONOTONIC for | |
166 | timing out <function>poll()</function> in | |
167 | <literal>timeout_usec</literal>. See | |
168 | <citerefentry><refentrytitle>clock_gettime</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
169 | for details about | |
170 | <literal>CLOCK_MONOTONIC</literal>. If there's no | |
171 | timeout to wait for this will fill in | |
172 | <literal>(uint64_t) -1</literal> instead. Note that | |
173 | <function>poll()</function> takes a relative timeout | |
174 | in milliseconds rather than an absolute timeout in | |
175 | microseconds. To convert the absolute 'us' timeout into | |
176 | relative 'ms', use code like the following:</para> | |
177 | ||
178 | <programlisting>uint64_t t; | |
179 | int msec; | |
180 | sd_login_monitor_get_timeout(m, &t); | |
181 | if (t == (uint64_t) -1) | |
182 | msec = -1; | |
183 | else { | |
184 | struct timespec ts; | |
185 | uint64_t n; | |
186 | clock_getttime(CLOCK_MONOTONIC, &ts); | |
187 | n = (uint64_t) ts.tv_sec * 1000000 + ts.tv_nsec / 1000; | |
188 | msec = t > n ? (int) ((t - n + 999) / 1000) : 0; | |
189 | }</programlisting> | |
190 | ||
191 | <para>The code above does not do any error checking | |
192 | for brevity's sake. The calculated <literal>msec</literal> | |
193 | integer can be passed directly as | |
194 | <function>poll()</function>'s timeout | |
195 | parameter.</para> | |
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196 | </refsect1> |
197 | ||
198 | <refsect1> | |
199 | <title>Return Value</title> | |
200 | ||
201 | <para>On success | |
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202 | <function>sd_login_monitor_new()</function>, |
203 | <function>sd_login_monitor_flush()</function> and | |
204 | <function>sd_login_monitor_get_timeout()</function> | |
205 | return 0 or a positive integer. On success | |
0b3b020a | 206 | <function>sd_login_monitor_get_fd()</function> returns |
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207 | a Unix file descriptor. On success |
208 | <function>sd_login_monitor_get_events()</function> | |
209 | returns a combination of <literal>POLLIN</literal>, | |
210 | <literal>POLLOUT</literal> and suchlike. On failure, | |
211 | these calls return a negative errno-style error | |
212 | code.</para> | |
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213 | |
214 | <para><function>sd_login_monitor_unref()</function> | |
215 | always returns NULL.</para> | |
216 | </refsect1> | |
217 | ||
218 | <refsect1> | |
219 | <title>Notes</title> | |
220 | ||
221 | <para>The <function>sd_login_monitor_new()</function>, | |
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222 | <function>sd_login_monitor_unref()</function>, |
223 | <function>sd_login_monitor_flush()</function>, | |
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224 | <function>sd_login_monitor_get_fd()</function>, |
225 | <function>sd_login_monitor_get_events()</function> and | |
226 | <function>sd_login_monitor_get_timeout()</function> | |
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227 | interfaces are available as shared library, which can |
228 | be compiled and linked to with the | |
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229 | <literal>libsystemd-login</literal> |
230 | <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
231 | file.</para> | |
232 | </refsect1> | |
233 | ||
234 | <refsect1> | |
235 | <title>See Also</title> | |
236 | ||
237 | <para> | |
238 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
cb07866b | 239 | <citerefentry><refentrytitle>sd-login</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
dace83cb | 240 | <citerefentry><refentrytitle>sd_get_seats</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
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241 | <citerefentry><refentrytitle>poll</refentrytitle><manvolnum>2</manvolnum></citerefentry>, |
242 | <citerefentry><refentrytitle>clock_gettime</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
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243 | </para> |
244 | </refsect1> | |
245 | ||
246 | </refentry> |