X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=man%2Fsd_login_monitor_new.xml;h=c6c58390a2b863705bd9973fc9e1ce794b2dfb19;hb=a5b55c5ad6cdfc629b29ac7feefe99af850dfc3a;hp=26af0ea247f3eb358ba7bde6d93152572756165c;hpb=e10375f2c0f5dd0dc8508f3ca165eb8aa63c64fb;p=elogind.git

diff --git a/man/sd_login_monitor_new.xml b/man/sd_login_monitor_new.xml
index 26af0ea24..c6c58390a 100644
--- a/man/sd_login_monitor_new.xml
+++ b/man/sd_login_monitor_new.xml
@@ -1,6 +1,6 @@
 <?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">
+  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 
 <!--
   This file is part of systemd.
@@ -23,224 +23,265 @@
 
 <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 &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>
-
-                        <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, NULL 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
-                <literal>POLLIN</literal>, <literal>POLLOUT</literal>
-                and similar to fill into the
-                <literal>.events</literal> field of <literal>struct
-                pollfd</literal>.</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 CLOCK_MONOTONIC for
-                timing out <function>poll()</function> in
-                <literal>timeout_usec</literal>. See
-                <citerefentry><refentrytitle>clock_gettime</refentrytitle><manvolnum>2</manvolnum></citerefentry>
-                for details about
-                <literal>CLOCK_MONOTONIC</literal>. If there's no
-                timeout to wait for this will fill in
-                <literal>(uint64_t) -1</literal> 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;
+  <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_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_default(&amp;m);
+        if (r &lt; 0)
+                fprintf(stderr, "Failed to allocate login monitor object: %s\n", strerror(-r));
+        …
+}</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;
+         msec = -1;
 else {
-        struct timespec ts;
-        uint64_t n;
-        clock_getttime(CLOCK_MONOTONIC, &amp;ts);
-        n = (uint64_t) ts.tv_sec * 1000000 + ts.tv_nsec / 1000;
-        msec = t > n ? (int) ((t - n + 999) / 1000) : 0;
+         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 <literal>msec</literal>
-                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 <literal>POLLIN</literal>,
-                <literal>POLLOUT</literal> and suchlike. 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>,
-                <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 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>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>
+    <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>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 NULL, 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>
+  </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>