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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.</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></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></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>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>