+++ /dev/null
-<?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>libelogind</constant> <citerefentry project='die-net'><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>
~ianmdlvl / elogind.git / blobdiff