Adding upstream version 255.4.upstream/255.4

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

1 files changed, 228 insertions, 0 deletions

diff --git a/man/sd_event_new.xml b/man/sd_event_new.xml
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+++ b/man/sd_event_new.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_new" xmlns:xi="http://www.w3.org/2001/XInclude">
+
+  <refentryinfo>
+    <title>sd_event_new</title>
+    <productname>systemd</productname>
+  </refentryinfo>
+
+  <refmeta>
+    <refentrytitle>sd_event_new</refentrytitle>
+    <manvolnum>3</manvolnum>
+  </refmeta>
+
+  <refnamediv>
+    <refname>sd_event_new</refname>
+    <refname>sd_event_default</refname>
+    <refname>sd_event_ref</refname>
+    <refname>sd_event_unref</refname>
+    <refname>sd_event_unrefp</refname>
+    <refname>sd_event_get_tid</refname>
+    <refname>sd_event</refname>
+
+    <refpurpose>Acquire and release an event loop object</refpurpose>
+  </refnamediv>
+
+  <refsynopsisdiv>
+    <funcsynopsis>
+      <funcsynopsisinfo>#include &lt;systemd/sd-event.h&gt;</funcsynopsisinfo>
+
+      <funcsynopsisinfo><token>typedef</token> struct sd_event sd_event;</funcsynopsisinfo>
+
+      <funcprototype>
+        <funcdef>int <function>sd_event_new</function></funcdef>
+        <paramdef>sd_event **<parameter>event</parameter></paramdef>
+      </funcprototype>
+
+      <funcprototype>
+        <funcdef>int <function>sd_event_default</function></funcdef>
+        <paramdef>sd_event **<parameter>event</parameter></paramdef>
+      </funcprototype>
+
+      <funcprototype>
+        <funcdef>sd_event *<function>sd_event_ref</function></funcdef>
+        <paramdef>sd_event *<parameter>event</parameter></paramdef>
+      </funcprototype>
+
+      <funcprototype>
+        <funcdef>sd_event *<function>sd_event_unref</function></funcdef>
+        <paramdef>sd_event *<parameter>event</parameter></paramdef>
+      </funcprototype>
+
+      <funcprototype>
+        <funcdef>void <function>sd_event_unrefp</function></funcdef>
+        <paramdef>sd_event **<parameter>event</parameter></paramdef>
+      </funcprototype>
+
+      <funcprototype>
+        <funcdef>int <function>sd_event_get_tid</function></funcdef>
+        <paramdef>sd_event *<parameter>event</parameter></paramdef>
+        <paramdef>pid_t *<parameter>tid</parameter></paramdef>
+      </funcprototype>
+
+    </funcsynopsis>
+  </refsynopsisdiv>
+
+  <refsect1>
+    <title>Description</title>
+
+    <para><function>sd_event_new()</function> allocates a new event
+    loop object. The event loop object is returned in the
+    <parameter>event</parameter> parameter. After use, drop
+    the returned reference with
+    <function>sd_event_unref()</function>. When the last reference is
+    dropped, the object is freed.</para>
+
+    <para><function>sd_event_default()</function> acquires a reference
+    to the default event loop object of the calling thread, possibly
+    allocating a new object if no default event loop object has been
+    allocated yet for the thread. After use, drop the returned
+    reference with <function>sd_event_unref()</function>. When the
+    last reference is dropped, the event loop is freed. If this
+    function is called while the object returned from a previous call
+    from the same thread is still referenced, the same object is
+    returned again, but the reference is increased by one. It is
+    recommended to use this call instead of
+    <function>sd_event_new()</function> in order to share event loop
+    objects between various components that are dispatched in the same
+    thread. All threads have exactly either zero or one default event loop
+    objects associated, but never more.</para>
+
+    <para>After allocating an event loop object, add event sources to
+    it with
+    <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_signal</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_add_post</refentrytitle><manvolnum>3</manvolnum></citerefentry> or
+    <citerefentry><refentrytitle>sd_event_add_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+    and then execute the event loop using
+    <citerefentry><refentrytitle>sd_event_loop</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
+
+    <para><function>sd_event_ref()</function> increases the reference
+    count of the specified event loop object by one.</para>
+
+    <para><function>sd_event_unref()</function> decreases the
+    reference count of the specified event loop object by one. If
+    the count hits zero, the object is freed. Note that it
+    is freed regardless of whether it is the default event loop object for a
+    thread or not. This means that allocating an event loop with
+    <function>sd_event_default()</function>, then releasing it, and
+    then acquiring a new one with
+    <function>sd_event_default()</function> will result in two
+    distinct objects. Note that, in order to free an event loop object,
+    all remaining event sources of the event loop also need to be
+    freed as each keeps a reference to it.</para>
+
+    <para><function>sd_event_unrefp()</function> is similar to
+    <function>sd_event_unref()</function> but takes a pointer to a
+    pointer to an <type>sd_event</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 an event loop object that is freed
+    automatically as the code block is left:</para>
+
+    <programlisting>{
+        __attribute__((cleanup(sd_event_unrefp))) sd_event *event = NULL;
+        int r;
+        …
+        r = sd_event_default(&amp;event);
+        if (r &lt; 0) {
+          errno = -r;
+          fprintf(stderr, "Failed to allocate event loop: %m\n");
+        }
+        …
+}</programlisting>
+
+    <para><function>sd_event_ref()</function>,
+    <function>sd_event_unref()</function> and
+    <function>sd_event_unrefp()</function> execute no operation if the
+    passed in event loop object is <constant>NULL</constant>.</para>
+
+    <para><function>sd_event_get_tid()</function> retrieves the thread
+    identifier ("TID") of the thread the specified event loop object
+    is associated with. This call is only supported for event loops
+    allocated with <function>sd_event_default()</function>, and
+    returns the identifier for the thread the event loop is the
+    default event loop of. See <citerefentry
+    project='man-pages'><refentrytitle>gettid</refentrytitle><manvolnum>2</manvolnum></citerefentry>
+    for more information on thread identifiers.</para>
+  </refsect1>
+
+  <refsect1>
+    <title>Return Value</title>
+
+    <para>On success, <function>sd_event_new()</function>, <function>sd_event_default()</function> and
+    <function>sd_event_get_tid()</function> return 0 or a positive integer. On failure, they return a
+    negative errno-style error code. <function>sd_event_ref()</function> always returns a pointer to the
+    event loop object passed in. <function>sd_event_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>-ENOMEM</constant></term>
+
+          <listitem><para>Not enough memory to allocate the object.</para></listitem>
+        </varlistentry>
+
+        <varlistentry>
+          <term><constant>-EMFILE</constant></term>
+
+          <listitem><para>The maximum number of event loops has been allocated.</para></listitem>
+
+        </varlistentry>
+
+        <varlistentry>
+          <term><constant>-ENXIO</constant></term>
+
+          <listitem><para><function>sd_event_get_tid()</function> was invoked on an event loop object that
+          was not allocated with <function>sd_event_default()</function>.</para></listitem>
+        </varlistentry>
+
+      </variablelist>
+    </refsect2>
+  </refsect1>
+
+  <xi:include href="libsystemd-pkgconfig.xml" />
+
+  <refsect1>
+    <title>History</title>
+    <para><function>sd_event_new()</function>,
+    <function>sd_event_default()</function>,
+    <function>sd_event_ref()</function>, and
+    <function>sd_event_unref()</function> were added in version 213.</para>
+    <para><function>sd_event_unrefp()</function> and
+    <function>sd_event_get_tid()</function> were added in version 229.</para>
+  </refsect1>
+
+  <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_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sd_event_add_signal</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_run</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry project='man-pages'><refentrytitle>gettid</refentrytitle><manvolnum>2</manvolnum></citerefentry>
+    </para>
+  </refsect1>
+
+</refentry>