Adding upstream version 252.22.upstream/252.22

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

1 files changed, 207 insertions, 0 deletions

diff --git a/man/sd_event_add_signal.xml b/man/sd_event_add_signal.xml
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+<?xml version='1.0'?>
+<!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_event_add_signal" xmlns:xi="http://www.w3.org/2001/XInclude">
+
+  <refentryinfo>
+    <title>sd_event_add_signal</title>
+    <productname>systemd</productname>
+  </refentryinfo>
+
+  <refmeta>
+    <refentrytitle>sd_event_add_signal</refentrytitle>
+    <manvolnum>3</manvolnum>
+  </refmeta>
+
+  <refnamediv>
+    <refname>sd_event_add_signal</refname>
+    <refname>sd_event_source_get_signal</refname>
+    <refname>sd_event_signal_handler_t</refname>
+    <refname>SD_EVENT_SIGNAL_PROCMASK</refname>
+
+    <refpurpose>Add a UNIX process signal event source to an event
+    loop</refpurpose>
+  </refnamediv>
+
+  <refsynopsisdiv>
+    <funcsynopsis>
+      <funcsynopsisinfo>#include &lt;systemd/sd-event.h&gt;</funcsynopsisinfo>
+
+      <funcsynopsisinfo><token>typedef</token> struct sd_event_source sd_event_source;</funcsynopsisinfo>
+
+      <funcsynopsisinfo><constant>SD_EVENT_SIGNAL_PROCMASK</constant></funcsynopsisinfo>
+
+      <funcprototype>
+        <funcdef>typedef int (*<function>sd_event_signal_handler_t</function>)</funcdef>
+        <paramdef>sd_event_source *<parameter>s</parameter></paramdef>
+        <paramdef>const struct signalfd_siginfo *<parameter>si</parameter></paramdef>
+        <paramdef>void *<parameter>userdata</parameter></paramdef>
+      </funcprototype>
+
+      <funcprototype>
+        <funcdef>int <function>sd_event_add_signal</function></funcdef>
+        <paramdef>sd_event *<parameter>event</parameter></paramdef>
+        <paramdef>sd_event_source **<parameter>source</parameter></paramdef>
+        <paramdef>int <parameter>signal</parameter></paramdef>
+        <paramdef>sd_event_signal_handler_t <parameter>handler</parameter></paramdef>
+        <paramdef>void *<parameter>userdata</parameter></paramdef>
+      </funcprototype>
+
+      <funcprototype>
+        <funcdef>int <function>sd_event_source_get_signal</function></funcdef>
+        <paramdef>sd_event_source *<parameter>source</parameter></paramdef>
+      </funcprototype>
+    </funcsynopsis>
+  </refsynopsisdiv>
+
+  <refsect1>
+    <title>Description</title>
+
+    <para><function>sd_event_add_signal()</function> adds a new UNIX process signal event source to an event
+    loop. The event loop object is specified in the <parameter>event</parameter> parameter, and the event
+    source object is returned in the <parameter>source</parameter> parameter. The
+    <parameter>signal</parameter> parameter specifies the numeric signal to be handled (see <citerefentry
+    project='man-pages'><refentrytitle>signal</refentrytitle><manvolnum>7</manvolnum></citerefentry>).</para>
+
+    <para>The <parameter>handler</parameter> parameter is a function to call when the signal is received or
+    <constant>NULL</constant>. The handler function will be passed the <parameter>userdata</parameter>
+    pointer, which may be chosen freely by the caller. The handler also receives a pointer to a
+    <structname>signalfd_siginfo</structname> structure containing information about the received signal. See
+    <citerefentry
+    project='man-pages'><refentrytitle>signalfd</refentrytitle><manvolnum>2</manvolnum></citerefentry> for
+    further information. The handler may return negative to signal an error (see below), other return values
+    are ignored. If <parameter>handler</parameter> is <constant>NULL</constant>, a default handler that calls
+    <citerefentry><refentrytitle>sd_event_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry> will be
+    used.</para>
+
+    <para>Only a single handler may be installed for a specific signal. The signal must be blocked in all
+    threads before this function is called (using <citerefentry
+    project='man-pages'><refentrytitle>sigprocmask</refentrytitle><manvolnum>2</manvolnum></citerefentry> or
+    <citerefentry
+    project='man-pages'><refentrytitle>pthread_sigmask</refentrytitle><manvolnum>3</manvolnum></citerefentry>). For
+    convenience, if the special flag <constant>SD_EVENT_SIGNAL_PROCMASK</constant> is ORed into the specified
+    signal the signal will be automatically masked as necessary, for the calling thread. Note that this only
+    works reliably if the signal is already masked in all other threads of the process, or if there are no
+    other threads at the moment of invocation.</para>
+
+    <para>By default, the event source is enabled permanently (<constant>SD_EVENT_ON</constant>), but this
+    may be changed with
+    <citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
+    If the handler function returns a negative error code, it will either be disabled after the invocation,
+    even if the <constant>SD_EVENT_ON</constant> mode was requested before, or it will cause the loop to
+    terminate, see
+    <citerefentry><refentrytitle>sd_event_source_set_exit_on_failure</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
+    </para>
+
+    <para>To destroy an event source object use
+    <citerefentry><refentrytitle>sd_event_source_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+    but note that the event source is only removed from the event loop
+    when all references to the event source are dropped. To make sure
+    an event source does not fire anymore, even if it is still referenced,
+    disable the event source using
+    <citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+    with <constant>SD_EVENT_OFF</constant>.</para>
+
+    <para>If the second parameter of
+    <function>sd_event_add_signal()</function> is
+    <constant>NULL</constant> no reference to the event source object
+    is returned. In this case the event source is considered
+    "floating", and will be destroyed implicitly when the event loop
+    itself is destroyed.</para>
+
+    <para>If the <parameter>handler</parameter> parameter to <function>sd_event_add_signal()</function> is
+    <constant>NULL</constant>, and the event source fires, this will be considered a request to exit the
+    event loop. In this case, the <parameter>userdata</parameter> parameter, cast to an integer, is passed as
+    the exit code parameter to
+    <citerefentry><refentrytitle>sd_event_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
+
+    <para><function>sd_event_source_get_signal()</function> returns
+    the configured signal number of an event source created previously
+    with <function>sd_event_add_signal()</function>. It takes the
+    event source object as the <parameter>source</parameter>
+    parameter.</para>
+  </refsect1>
+
+  <refsect1>
+    <title>Return Value</title>
+
+    <para>On success, these functions return 0 or a positive
+    integer. On failure, they return a negative errno-style error
+    code.</para>
+
+    <refsect2>
+      <title>Errors</title>
+
+      <para>Returned errors may indicate the following problems:</para>
+
+      <variablelist>
+        <varlistentry>
+          <term><constant>-ENOMEM</constant></term>
+
+          <listitem><para>Not enough memory to allocate an object.</para></listitem>
+        </varlistentry>
+
+        <varlistentry>
+          <term><constant>-EINVAL</constant></term>
+
+          <listitem><para>An invalid argument has been passed.</para></listitem>
+        </varlistentry>
+
+        <varlistentry>
+          <term><constant>-EBUSY</constant></term>
+
+          <listitem><para>A handler is already installed for this
+          signal or the signal was not blocked previously.</para></listitem>
+        </varlistentry>
+
+        <varlistentry>
+          <term><constant>-ESTALE</constant></term>
+
+          <listitem><para>The event loop is already terminated.</para></listitem>
+        </varlistentry>
+
+        <varlistentry>
+          <term><constant>-ECHILD</constant></term>
+
+          <listitem><para>The event loop has been created in a different process.</para></listitem>
+        </varlistentry>
+
+        <varlistentry>
+          <term><constant>-EDOM</constant></term>
+
+          <listitem><para>The passed event source is not a signal event source.</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-event</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sd_event_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sd_event_now</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sd_event_add_child</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sd_event_add_inotify</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sd_event_source_set_description</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sd_event_source_set_userdata</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sd_event_source_set_floating</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry project='man-pages'><refentrytitle>signal</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
+      <citerefentry project='man-pages'><refentrytitle>signalfd</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
+      <citerefentry project='man-pages'><refentrytitle>sigprocmask</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
+      <citerefentry project='man-pages'><refentrytitle>pthread_sigmask</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+    </para>
+  </refsect1>
+
+</refentry>