| <?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"> |
| |
| <!-- |
| This file is part of systemd. |
| |
| Copyright 2010 Lennart Poettering |
| |
| systemd is free software; you can redistribute it and/or modify it |
| under the terms of the GNU Lesser General Public License as published by |
| the Free Software Foundation; either version 2.1 of the License, or |
| (at your option) any later version. |
| |
| systemd is distributed in the hope that it will be useful, but |
| WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public License |
| along with systemd; If not, see <http://www.gnu.org/licenses/>. |
| --> |
| |
| <refentry id="sd_login_monitor_new" conditional='HAVE_PAM'> |
| |
| <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> |
| <refname>sd_login_monitor_get_events</refname> |
| <refname>sd_login_monitor_get_timeout</refname> |
| <refname>sd_login_monitor</refname> |
| <refpurpose>Monitor login sessions, seats, users and virtual machines/containers</refpurpose> |
| </refnamediv> |
| |
| <refsynopsisdiv> |
| <funcsynopsis> |
| <funcsynopsisinfo>#include <systemd/sd-login.h></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> |
| |
| <funcprototype> |
| <funcdef>int <function>sd_login_monitor_get_events</function></funcdef> |
| <paramdef>sd_login_monitor *<parameter>m</parameter></paramdef> |
| </funcprototype> |
| |
| <funcprototype> |
| <funcdef>int <function>sd_login_monitor_get_timeout</function></funcdef> |
| <paramdef>sd_login_monitor *<parameter>m</parameter></paramdef> |
| <paramdef>uint64_t *<parameter>timeout_usec</parameter></paramdef> |
| </funcprototype> |
| |
| </funcsynopsis> |
| </refsynopsisdiv> |
| |
| <refsect1> |
| <title>Description</title> |
| |
| <para><function>sd_login_monitor_new()</function> may |
| be used to monitor login sessions, users, seats, and |
| virtual machines/containers. 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, seat or virtual machine/container |
| changes state otherwise. The first parameter takes a |
| string which can be <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), <literal>uid</literal> (to get only |
| notifications when a user changes state in respect to |
| logins) or <literal>machine</literal> (to get only |
| notifications when a virtual machine or container is |
| started or stopped). If notifications shall be |
| generated in all these conditions, <constant>NULL</constant> may be |
| passed. Note that in the 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 the |
| events mask returned by |
| <function>sd_login_monitor_get_events()</function>. It |
| should pass a timeout value as returned by |
| <function>sd_login_monitor_get_timeout()</function>. 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> |
| |
| <para><function>sd_login_monitor_get_events()</function> |
| will return the <function>poll()</function> mask to |
| wait for. This function will return a combination of |
| <constant>POLLIN</constant>, <constant>POLLOUT</constant> |
| and similar to fill into the |
| <literal>.events</literal> field of <varname>struct |
| pollfd</varname>.</para> |
| |
| <para><function>sd_login_monitor_get_timeout()</function> |
| will return a timeout value for usage in |
| <function>poll()</function>. This returns a value in |
| microseconds since the epoch of <constant>CLOCK_MONOTONIC</constant> |
| for timing out <function>poll()</function> in |
| <varname>timeout_usec</varname>. See |
| <citerefentry><refentrytitle>clock_gettime</refentrytitle><manvolnum>2</manvolnum></citerefentry> |
| for details about |
| <constant>CLOCK_MONOTONIC</constant>. If there is no |
| timeout to wait for this will fill in |
| <constant>(uint64_t) -1</constant> instead. Note that |
| <function>poll()</function> takes a relative timeout |
| in milliseconds rather than an absolute timeout in |
| microseconds. To convert the absolute 'us' timeout into |
| relative 'ms', use code like the following:</para> |
| |
| <programlisting>uint64_t t; |
| int msec; |
| sd_login_monitor_get_timeout(m, &t); |
| if (t == (uint64_t) -1) |
| msec = -1; |
| else { |
| struct timespec ts; |
| uint64_t n; |
| clock_getttime(CLOCK_MONOTONIC, &ts); |
| n = (uint64_t) ts.tv_sec * 1000000 + ts.tv_nsec / 1000; |
| msec = t > n ? (int) ((t - n + 999) / 1000) : 0; |
| }</programlisting> |
| |
| <para>The code above does not do any error checking |
| for brevity's sake. The calculated <varname>msec</varname> |
| integer can be passed directly as |
| <function>poll()</function>'s timeout |
| parameter.</para> |
| </refsect1> |
| |
| <refsect1> |
| <title>Return Value</title> |
| |
| <para>On success, |
| <function>sd_login_monitor_new()</function>, |
| <function>sd_login_monitor_flush()</function> and |
| <function>sd_login_monitor_get_timeout()</function> |
| return 0 or a positive integer. On success, |
| <function>sd_login_monitor_get_fd()</function> returns |
| a Unix file descriptor. On success, |
| <function>sd_login_monitor_get_events()</function> |
| returns a combination of <constant>POLLIN</constant>, |
| <constant>POLLOUT</constant> and suchlike. On failure, |
| these calls return a negative errno-style error |
| code.</para> |
| |
| <para><function>sd_login_monitor_unref()</function> |
| always returns <constant>NULL</constant>.</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>, |
| <function>sd_login_monitor_get_fd()</function>, |
| <function>sd_login_monitor_get_events()</function> and |
| <function>sd_login_monitor_get_timeout()</function> |
| interfaces are available as a shared library, which can |
| be compiled and linked to with the |
| <constant>libsystemd</constant> <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>3</manvolnum></citerefentry>, |
| <citerefentry><refentrytitle>sd_get_seats</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
| <citerefentry><refentrytitle>poll</refentrytitle><manvolnum>2</manvolnum></citerefentry>, |
| <citerefentry><refentrytitle>clock_gettime</refentrytitle><manvolnum>2</manvolnum></citerefentry> |
| </para> |
| </refsect1> |
| |
| </refentry> |