man/udev_new.xml

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   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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   8 <!--
   9   SPDX-License-Identifier: LGPL-2.1+
  10
  11   This file is part of systemd.
  12
  13   Copyright 2015 David Herrmann <dh.herrmann@gmail.com>
  14 -->
  15
  16 <refentry id="udev_new"
  17   xmlns:xi="http://www.w3.org/2001/XInclude">
  18
  19   <refentryinfo>
  20     <title>udev_new</title>
  21     <productname>systemd</productname>
  22
  23     <authorgroup>
  24       <author>
  25         <contrib>Developer</contrib>
  26         <firstname>David</firstname>
  27         <surname>Herrmann</surname>
  28         <email>dh.herrmann@gmail.com</email>
  29       </author>
  30     </authorgroup>
  31   </refentryinfo>
  32
  33   <refmeta>
  34     <refentrytitle>udev_new</refentrytitle>
  35     <manvolnum>3</manvolnum>
  36   </refmeta>
  37
  38   <refnamediv>
  39     <refname>udev_new</refname>
  40     <refname>udev_ref</refname>
  41     <refname>udev_unref</refname>
  42
  43     <refpurpose>Create, acquire and release a udev context object</refpurpose>
  44   </refnamediv>
  45
  46   <refsynopsisdiv>
  47     <funcsynopsis>
  48       <funcsynopsisinfo>#include &lt;libudev.h&gt;</funcsynopsisinfo>
  49
  50       <funcprototype>
  51         <funcdef>struct udev *<function>udev_new</function></funcdef>
  52         <paramdef><parameter>void</parameter></paramdef>
  53       </funcprototype>
  54
  55       <funcprototype>
  56         <funcdef>struct udev *<function>udev_ref</function></funcdef>
  57         <paramdef>struct udev *<parameter>udev</parameter></paramdef>
  58       </funcprototype>
  59
  60       <funcprototype>
  61         <funcdef>struct udev *<function>udev_unref</function></funcdef>
  62         <paramdef>struct udev *<parameter>udev</parameter></paramdef>
  63       </funcprototype>
  64
  65     </funcsynopsis>
  66   </refsynopsisdiv>
  67
  68   <refsect1>
  69     <title>Description</title>
  70
  71     <para><function>udev_new()</function> allocates a new udev context
  72     object and returns a pointer to it. This object is opaque and must
  73     not be accessed by the caller via different means than functions
  74     provided by libudev. Initially, the reference count of the context
  75     is 1. You can acquire further references, and drop gained references
  76     via <function>udev_ref()</function> and
  77     <function>udev_unref()</function>. Once the reference count hits 0,
  78     the context object is destroyed and freed.</para>
  79   </refsect1>
  80
  81   <refsect1>
  82     <title>Return Value</title>
  83
  84     <para>On success, <function>udev_new()</function> returns a pointer
  85     to the allocated udev context. On failure, <constant>NULL</constant>
  86     is returned. <function>udev_ref()</function> returns the argument
  87     that it was passed, unmodified. <function>udev_unref()</function>
  88     always returns <constant>NULL</constant>.</para>
  89   </refsect1>
  90
  91   <refsect1>
  92     <title>See Also</title>
  93
  94     <para>
  95       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
  96     </para>
  97   </refsect1>
  98
  99 </refentry>