sd-event: add destroy callback logic to sd-event too

This adds what has been added to sd_bus_slot and sd_bus_track to
sd_event too.

2 files changed, 116 insertions, 0 deletions

diff --git a/man/rules/meson.build b/man/rules/meson.build
index 88c832815..13295da9d 100644
--- a/man/rules/meson.build
+++ b/man/rules/meson.build
@@ -317,6 +317,10 @@ manpages = [
   '3',
   ['sd_event_source_get_description'],
   ''],
+ ['sd_event_source_set_destroy_callback',
+  '3',
+  ['sd_event_destroy_t', 'sd_event_source_get_destroy_callback'],
+  ''],
  ['sd_event_source_set_enabled',
   '3',
   ['SD_EVENT_OFF',
diff --git a/man/sd_event_source_set_destroy_callback.xml b/man/sd_event_source_set_destroy_callback.xml
new file mode 100644
index 000000000..aa6d0e1b3
--- /dev/null
+++ b/man/sd_event_source_set_destroy_callback.xml
@@ -0,0 +1,112 @@
+<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
+"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+
+<!-- SPDX-License-Identifier: LGPL-2.1+ -->
+
+<refentry id="sd_event_source_set_destroy_callback"
+          xmlns:xi="http://www.w3.org/2001/XInclude">
+
+  <refentryinfo>
+    <title>sd_event_source_set_destroy_callback</title>
+    <productname>elogind</productname>
+  </refentryinfo>
+
+  <refmeta>
+    <refentrytitle>sd_event_source_set_destroy_callback</refentrytitle>
+    <manvolnum>3</manvolnum>
+  </refmeta>
+
+  <refnamediv>
+    <refname>sd_event_source_set_destroy_callback</refname>
+    <refname>sd_event_source_get_destroy_callback</refname>
+    <refname>sd_event_destroy_t</refname>
+
+    <refpurpose>Define the callback function for resource cleanup.</refpurpose>
+  </refnamediv>
+
+  <refsynopsisdiv>
+    <funcsynopsis>
+      <funcsynopsisinfo>#include &lt;elogind/sd-event.h&gt;</funcsynopsisinfo>
+
+      <funcprototype>
+        <funcdef>typedef int (*<function>sd_event_destroy_t</function>)</funcdef>
+        <paramdef>void *<parameter>userdata</parameter></paramdef>
+      </funcprototype>
+
+      <funcprototype>
+        <funcdef>int <function>sd_event_source_set_destroy_callback</function></funcdef>
+        <paramdef>sd_event_source *<parameter>source</parameter></paramdef>
+        <paramdef>sd_event_destroy_t <parameter>callback</parameter></paramdef>
+      </funcprototype>
+
+      <funcprototype>
+        <funcdef>int <function>sd_event_source_get_destroy_callback</function></funcdef>
+        <paramdef>sd_event_source *<parameter>source</parameter></paramdef>
+        <paramdef>sd_event_destroy_t *<parameter>callback</parameter></paramdef>
+      </funcprototype>
+
+    </funcsynopsis>
+  </refsynopsisdiv>
+
+  <refsect1>
+    <title>Description</title>
+
+    <para><function>sd_event_source_set_destroy_callback()</function> sets <parameter>callback</parameter> as the
+    callback function to be called right before the event source object <parameter>source</parameter> is
+    deallocated. The <parameter>userdata</parameter> pointer from the event source object will be passed as the
+    <parameter>userdata</parameter> parameter. This pointer can be set by an argument to the constructor functions, see
+    <citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>, or directly,
+    see
+    <citerefentry><refentrytitle>sd_event_source_set_userdata</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
+    This callback function is called even if <parameter>userdata</parameter> is <constant>NULL</constant>. Note that
+    this callback is invoked at a time where the event source object itself is already invalidated, and executing
+    operations or taking new references to the event source object is not permissible.</para>
+
+    <para><function>sd_event_source_get_destroy_callback()</function> returns the current callback
+    for <parameter>source</parameter> in the <parameter>callback</parameter> parameter.</para>
+  </refsect1>
+
+  <refsect1>
+    <title>Return Value</title>
+
+    <para>On success, <function>sd_event_source_set_destroy_callback()</function> returns 0 or a positive integer. On
+    failure, it returns a negative errno-style error code.</para>
+
+    <para><function>sd_event_source_get_destroy_callback()</function> returns positive if the destroy callback function
+    is set, 0 if not. On failure, returns a negative errno-style error code.</para>
+  </refsect1>
+
+  <refsect1>
+    <title>Errors</title>
+
+    <para>Returned errors may indicate the following problems:</para>
+
+    <variablelist>
+      <varlistentry>
+        <term><constant>-EINVAL</constant></term>
+
+        <listitem><para>The <parameter>source</parameter> parameter is <constant>NULL</constant>.</para></listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+
+  <xi:include href="libelogind-pkgconfig.xml" />
+
+  <refsect1>
+    <title>See Also</title>
+
+    <para>
+      <citerefentry><refentrytitle>elogind</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_source_set_userdata</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+    </para>
+  </refsect1>
+
+</refentry>