Adding upstream version 255.4.upstream/255.4

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

1 files changed, 246 insertions, 0 deletions

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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_inotify" xmlns:xi="http://www.w3.org/2001/XInclude">
+
+  <refentryinfo>
+    <title>sd_event_add_inotify</title>
+    <productname>systemd</productname>
+  </refentryinfo>
+
+  <refmeta>
+    <refentrytitle>sd_event_add_inotify</refentrytitle>
+    <manvolnum>3</manvolnum>
+  </refmeta>
+
+  <refnamediv>
+    <refname>sd_event_add_inotify</refname>
+    <refname>sd_event_add_inotify_fd</refname>
+    <refname>sd_event_source_get_inotify_mask</refname>
+    <refname>sd_event_inotify_handler_t</refname>
+
+    <refpurpose>Add an "inotify" file system inode 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>
+
+      <funcprototype>
+        <funcdef>typedef int (*<function>sd_event_inotify_handler_t</function>)</funcdef>
+        <paramdef>sd_event_source *<parameter>s</parameter></paramdef>
+        <paramdef>const struct inotify_event *<parameter>event</parameter></paramdef>
+        <paramdef>void *<parameter>userdata</parameter></paramdef>
+      </funcprototype>
+
+      <funcprototype>
+        <funcdef>int <function>sd_event_add_inotify</function></funcdef>
+        <paramdef>sd_event *<parameter>event</parameter></paramdef>
+        <paramdef>sd_event_source **<parameter>source</parameter></paramdef>
+        <paramdef>const char *<parameter>path</parameter></paramdef>
+        <paramdef>uint32_t <parameter>mask</parameter></paramdef>
+        <paramdef>sd_event_inotify_handler_t <parameter>handler</parameter></paramdef>
+        <paramdef>void *<parameter>userdata</parameter></paramdef>
+      </funcprototype>
+
+      <funcprototype>
+        <funcdef>int <function>sd_event_add_inotify_fd</function></funcdef>
+        <paramdef>sd_event *<parameter>event</parameter></paramdef>
+        <paramdef>sd_event_source **<parameter>source</parameter></paramdef>
+        <paramdef>int <parameter>fd</parameter></paramdef>
+        <paramdef>uint32_t <parameter>mask</parameter></paramdef>
+        <paramdef>sd_event_inotify_handler_t <parameter>handler</parameter></paramdef>
+        <paramdef>void *<parameter>userdata</parameter></paramdef>
+      </funcprototype>
+
+      <funcprototype>
+        <funcdef>int <function>sd_event_source_get_inotify_mask</function></funcdef>
+        <paramdef>sd_event_source *<parameter>source</parameter></paramdef>
+        <paramdef>uint32_t *<parameter>mask</parameter></paramdef>
+      </funcprototype>
+
+    </funcsynopsis>
+  </refsynopsisdiv>
+
+  <refsect1>
+    <title>Description</title>
+
+    <para><function>sd_event_add_inotify()</function> adds a new <citerefentry
+    project='man-pages'><refentrytitle>inotify</refentrytitle><manvolnum>7</manvolnum></citerefentry> file
+    system inode event source to an event loop. The event loop object is specified in the
+    <parameter>event</parameter> parameter, the event source object is returned in the
+    <parameter>source</parameter> parameter. The <parameter>path</parameter> parameter specifies the path of
+    the file system inode to watch. The <parameter>mask</parameter> parameter specifies which types of inode
+    events to watch specifically. It must contain an OR-ed combination of <constant>IN_ACCESS</constant>,
+    <constant>IN_ATTRIB</constant>, <constant>IN_CLOSE_WRITE</constant>, … flags. See <citerefentry
+    project='man-pages'><refentrytitle>inotify</refentrytitle><manvolnum>7</manvolnum></citerefentry> for
+    further information.</para>
+
+    <para>The <parameter>handler</parameter> must reference a function to call when the inode changes 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>struct
+    inotify_event</structname> structure containing information about the inode event. 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><function>sd_event_add_inotify_fd()</function> is identical to
+    <function>sd_event_add_inotify()</function>, except that it takes a file descriptor to an inode (possibly
+    an <constant>O_PATH</constant> one, but any other will do too) instead of a path in the file system.
+    </para>
+
+    <para>If multiple event sources are installed for the same inode the backing inotify watch descriptor is
+    automatically shared. The mask parameter may contain any flag defined by the inotify API, with the exception of
+    <constant>IN_MASK_ADD</constant>.</para>
+
+    <para>The handler is enabled continuously (<constant>SD_EVENT_ON</constant>), but this may be changed with
+    <citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
+    Alternatively, the <constant>IN_ONESHOT</constant> mask flag may be used to request
+    <constant>SD_EVENT_ONESHOT</constant> mode. If the handler function returns a negative error code, it
+    will be disabled after the invocation, even if the <constant>SD_EVENT_ON</constant> mode was requested
+    before.</para>
+
+    <para>As a special limitation the priority of inotify event sources may only be altered (see
+    <citerefentry><refentrytitle>sd_event_source_set_priority</refentrytitle><manvolnum>3</manvolnum></citerefentry>)
+    in the time between creation of the event source object with <function>sd_event_add_inotify()</function> and the
+    beginning of the next event loop iteration. Attempts of changing the priority any later will be refused. Consider
+    freeing and allocating a new inotify event source to change the priority at that point.</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 when there's still a reference to it kept, consider disabling
+    it with
+    <citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
+
+    <para>If the second parameter of <function>sd_event_add_inotify()</function> is passed as
+    <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_inotify()</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_inotify_mask()</function> retrieves the configured inotify watch mask of an
+    event source created previously with <function>sd_event_add_inotify()</function>. It takes the event source object
+    as the <parameter>source</parameter> parameter and a pointer to a <type>uint32_t</type> variable to return the mask
+    in.</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. This includes specifying a mask with
+          <constant>IN_MASK_ADD</constant> set.</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, library or module instance.</para></listitem>
+
+        </varlistentry>
+
+        <varlistentry>
+          <term><constant>-EDOM</constant></term>
+
+          <listitem><para>The passed event source is not an inotify process event source.</para></listitem>
+        </varlistentry>
+
+        <varlistentry>
+          <term><constant>-EBADF</constant></term>
+
+          <listitem><para>The passed file descriptor is not valid.</para>
+
+          <xi:include href="version-info.xml" xpointer="v250"/></listitem>
+        </varlistentry>
+
+        <varlistentry>
+          <term><constant>-ENOSYS</constant></term>
+
+          <listitem><para><function>sd_event_add_inotify_fd()</function> was called without
+          <filename>/proc/</filename> mounted.</para>
+
+          <xi:include href="version-info.xml" xpointer="v250"/></listitem>
+        </varlistentry>
+
+      </variablelist>
+    </refsect2>
+  </refsect1>
+
+  <refsect1>
+    <title>Examples</title>
+
+    <example>
+      <title>A simple program that uses inotify to monitor one or two directories</title>
+
+      <programlisting><xi:include href="inotify-watch-tmp.c" parse="text" /></programlisting>
+    </example>
+  </refsect1>
+
+  <xi:include href="libsystemd-pkgconfig.xml" />
+
+  <refsect1>
+    <title>History</title>
+    <para><function>sd_event_inotify_handler_t()</function>,
+    <function>sd_event_add_inotify()</function>, and
+    <function>sd_event_source_get_inotify_mask()</function> were added in version 239.</para>
+    <para><function>sd_event_add_inotify_fd()</function> was added in version 250.</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_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_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sd_event_add_child</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sd_event_source_set_priority</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sd_event_source_set_userdata</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sd_event_source_set_description</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sd_event_source_set_floating</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry project='man-pages'><refentrytitle>waitid</refentrytitle><manvolnum>2</manvolnum></citerefentry>
+    </para>
+  </refsect1>
+
+</refentry>