man/udev_new.xml

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   7 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
   8
   9 <refentry id="udev_new"
  10   xmlns:xi="http://www.w3.org/2001/XInclude">
  11
  12   <refentryinfo>
  13     <title>udev_new</title>
  14     <productname>systemd</productname>
  15   </refentryinfo>
  16
  17   <refmeta>
  18     <refentrytitle>udev_new</refentrytitle>
  19     <manvolnum>3</manvolnum>
  20   </refmeta>
  21
  22   <refnamediv>
  23     <refname>udev_new</refname>
  24     <refname>udev_ref</refname>
  25     <refname>udev_unref</refname>
  26
  27     <refpurpose>Create, acquire and release a udev context object</refpurpose>
  28   </refnamediv>
  29
  30   <refsynopsisdiv>
  31     <funcsynopsis>
  32       <funcsynopsisinfo>#include &lt;libudev.h&gt;</funcsynopsisinfo>
  33
  34       <funcprototype>
  35         <funcdef>struct udev *<function>udev_new</function></funcdef>
  36         <paramdef><parameter>void</parameter></paramdef>
  37       </funcprototype>
  38
  39       <funcprototype>
  40         <funcdef>struct udev *<function>udev_ref</function></funcdef>
  41         <paramdef>struct udev *<parameter>udev</parameter></paramdef>
  42       </funcprototype>
  43
  44       <funcprototype>
  45         <funcdef>struct udev *<function>udev_unref</function></funcdef>
  46         <paramdef>struct udev *<parameter>udev</parameter></paramdef>
  47       </funcprototype>
  48
  49     </funcsynopsis>
  50   </refsynopsisdiv>
  51
  52   <refsect1>
  53     <title>Description</title>
  54
  55     <para><function>udev_new()</function> allocates a new udev context
  56     object and returns a pointer to it. This object is opaque and must
  57     not be accessed by the caller via different means than functions
  58     provided by libudev. Initially, the reference count of the context
  59     is 1. You can acquire further references, and drop gained references
  60     via <function>udev_ref()</function> and
  61     <function>udev_unref()</function>. Once the reference count hits 0,
  62     the context object is destroyed and freed.</para>
  63   </refsect1>
  64
  65   <refsect1>
  66     <title>Return Value</title>
  67
  68     <para>On success, <function>udev_new()</function> returns a pointer
  69     to the allocated udev context. On failure, <constant>NULL</constant>
  70     is returned. <function>udev_ref()</function> returns the argument
  71     that it was passed, unmodified. <function>udev_unref()</function>
  72     always returns <constant>NULL</constant>.</para>
  73   </refsect1>
  74
  75   <refsect1>
  76     <title>History</title>
  77     <para><function>udev_new()</function>,
  78     <function>udev_ref()</function>, and
  79     <function>udev_unref()</function> were added in version 221.</para>
  80   </refsect1>
  81
  82   <refsect1>
  83     <title>See Also</title>
  84
  85     <para><simplelist type="inline">
  86       <member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
  87       <member><citerefentry><refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
  88     </simplelist></para>
  89   </refsect1>
  90
  91 </refentry>