Adding upstream version 252.22.upstream/252.22upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 249 insertions, 0 deletions

diff --git a/man/sd_login_monitor_new.xml b/man/sd_login_monitor_new.xml
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+<?xml version='1.0'?> <!--*-nxml-*-->
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
+  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
+
+<refentry id="sd_login_monitor_new" conditional='HAVE_PAM'
+          xmlns:xi="http://www.w3.org/2001/XInclude">
+
+  <refentryinfo>
+    <title>sd_login_monitor_new</title>
+    <productname>systemd</productname>
+  </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_unrefp</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 &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>void <function>sd_login_monitor_unrefp</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_unrefp()</function> is similar to
+    <function>sd_login_monitor_unref()</function> but takes a pointer
+    to a pointer to an <type>sd_login_monitor</type> object. This call
+    is useful in conjunction with GCC's and LLVM's <ulink
+    url="https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html">Clean-up
+    Variable Attribute</ulink>. Note that this function is defined as
+    inline function. Use a declaration like the following, in order to
+    allocate a login monitor object that is freed automatically as the
+    code block is left:</para>
+
+    <programlisting>{
+  __attribute__((cleanup(sd_login_monitor_unrefp))) sd_login_monitor *m = NULL;
+  int r;
+  …
+  r = sd_login_monitor_new(NULL, &amp;m);
+  if (r &lt; 0) {
+    errno = -r;
+    fprintf(stderr, "Failed to allocate login monitor object: %m\n");
+  }
+  …
+}</programlisting>
+
+    <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_unref()</function> and
+    <function>sd_login_monitor_unrefp()</function> execute no
+    operation if the passed in monitor object is
+    <constant>NULL</constant>.</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 'µs' timeout into
+    relative 'ms', use code like the following:</para>
+
+    <programlisting>uint64_t t;
+int msec;
+sd_login_monitor_get_timeout(m, &amp;t);
+if (t == (uint64_t) -1)
+  msec = -1;
+else {
+  struct timespec ts;
+  uint64_t n;
+  clock_gettime(CLOCK_MONOTONIC, &amp;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>
+
+    <refsect2>
+      <title>Errors</title>
+
+      <para>Returned errors may indicate the following problems:</para>
+
+      <variablelist>
+
+        <varlistentry>
+          <term><constant>-EINVAL</constant></term>
+
+          <listitem><para>An input parameter was invalid (out of range, or <constant>NULL</constant>, where
+          that is not accepted). The specified category to watch is not known.</para></listitem>
+        </varlistentry>
+
+        <varlistentry>
+          <term><constant>-ENOMEM</constant></term>
+
+          <listitem><para>Memory allocation failed.</para></listitem>
+        </varlistentry>
+      </variablelist>
+    </refsect2>
+  </refsect1>
+
+  <xi:include href="libsystemd-pkgconfig.xml" />
+
+  <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>