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1 | <?xml version='1.0'?> <!--*-nxml-*--> |
2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" | |
3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" [ | |
4 | <!ENTITY % entities SYSTEM "custom-entities.ent" > | |
5 | %entities; | |
6 | ]> | |
7 | ||
8 | <!-- | |
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9 | SPDX-License-Identifier: LGPL-2.1+ |
10 | ||
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11 | This file is part of systemd. |
12 | ||
13 | Copyright 2015 David Herrmann <dh.herrmann@gmail.com> | |
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14 | --> |
15 | ||
16 | <refentry id="udev_device_new_from_syspath" | |
17 | xmlns:xi="http://www.w3.org/2001/XInclude"> | |
18 | ||
19 | <refentryinfo> | |
20 | <title>udev_device_new_from_syspath</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_device_new_from_syspath</refentrytitle> | |
35 | <manvolnum>3</manvolnum> | |
36 | </refmeta> | |
37 | ||
38 | <refnamediv> | |
39 | <refname>udev_device_new_from_syspath</refname> | |
40 | <refname>udev_device_new_from_devnum</refname> | |
41 | <refname>udev_device_new_from_subsystem_sysname</refname> | |
42 | <refname>udev_device_new_from_device_id</refname> | |
43 | <refname>udev_device_new_from_environment</refname> | |
44 | <refname>udev_device_ref</refname> | |
45 | <refname>udev_device_unref</refname> | |
46 | ||
47 | <refpurpose>Create, acquire and release a udev device object</refpurpose> | |
48 | </refnamediv> | |
49 | ||
50 | <refsynopsisdiv> | |
51 | <funcsynopsis> | |
52 | <funcsynopsisinfo>#include <libudev.h></funcsynopsisinfo> | |
53 | ||
54 | <funcprototype> | |
55 | <funcdef>struct udev_device *<function>udev_device_new_from_syspath</function></funcdef> | |
56 | <paramdef>struct udev *<parameter>udev</parameter></paramdef> | |
57 | <paramdef>const char *<parameter>syspath</parameter></paramdef> | |
58 | </funcprototype> | |
59 | ||
60 | <funcprototype> | |
61 | <funcdef>struct udev_device *<function>udev_device_new_from_devnum</function></funcdef> | |
62 | <paramdef>struct udev *<parameter>udev</parameter></paramdef> | |
63 | <paramdef>char <parameter>type</parameter></paramdef> | |
64 | <paramdef>dev_t <parameter>devnum</parameter></paramdef> | |
65 | </funcprototype> | |
66 | ||
67 | <funcprototype> | |
68 | <funcdef>struct udev_device *<function>udev_device_new_from_subsystem_sysname</function></funcdef> | |
69 | <paramdef>struct udev *<parameter>udev</parameter></paramdef> | |
70 | <paramdef>const char *<parameter>subsystem</parameter></paramdef> | |
71 | <paramdef>const char *<parameter>sysname</parameter></paramdef> | |
72 | </funcprototype> | |
73 | ||
74 | <funcprototype> | |
75 | <funcdef>struct udev_device *<function>udev_device_new_from_device_id</function></funcdef> | |
76 | <paramdef>struct udev *<parameter>udev</parameter></paramdef> | |
77 | <paramdef>const char *<parameter>id</parameter></paramdef> | |
78 | </funcprototype> | |
79 | ||
80 | <funcprototype> | |
81 | <funcdef>struct udev_device *<function>udev_device_new_from_environment</function></funcdef> | |
82 | <paramdef>struct udev *<parameter>udev</parameter></paramdef> | |
83 | </funcprototype> | |
84 | ||
85 | <funcprototype> | |
86 | <funcdef>struct udev_device *<function>udev_device_ref</function></funcdef> | |
87 | <paramdef>struct udev_device *<parameter>udev_device</parameter></paramdef> | |
88 | </funcprototype> | |
89 | ||
90 | <funcprototype> | |
91 | <funcdef>struct udev_device *<function>udev_device_unref</function></funcdef> | |
92 | <paramdef>struct udev_device *<parameter>udev_device</parameter></paramdef> | |
93 | </funcprototype> | |
94 | ||
95 | </funcsynopsis> | |
96 | </refsynopsisdiv> | |
97 | ||
00dbd902 | 98 | <refsect1> |
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99 | <title>Description</title> |
100 | ||
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101 | <para><function>udev_device_new_from_syspath</function>, |
102 | <function>udev_device_new_from_devnum</function>, | |
103 | <function>udev_device_new_from_subsystem_sysname</function>, | |
104 | <function>udev_device_new_from_device_id</function>, and | |
105 | <function>udev_device_new_from_environment</function> | |
106 | allocate a new udev device object and returns a pointer to it. This | |
107 | object is opaque and must not be accessed by the caller via different | |
108 | means than functions provided by libudev. Initially, the reference count | |
109 | of the device is 1. You can acquire further references, and drop | |
110 | gained references via <function>udev_device_ref()</function> and | |
111 | <function>udev_device_unref()</function>. Once the reference count hits 0, | |
112 | the device object is destroyed and freed.</para> | |
113 | ||
114 | <para><function>udev_device_new_from_syspath</function>, | |
115 | <function>udev_device_new_from_devnum</function>, | |
116 | <function>udev_device_new_from_subsystem_sysname</function>, and | |
117 | <function>udev_device_new_from_device_id</function> | |
118 | create the device object based on information found in | |
b938cb90 | 119 | <filename>/sys</filename>, annotated with properties from the udev-internal |
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120 | device database. A syspath is any subdirectory of <filename>/sys</filename>, |
121 | with the restriction that a subdirectory of <filename>/sys/devices</filename> | |
122 | (or a symlink to one) represents a real device and as such must contain | |
123 | a <filename>uevent</filename> file. <function>udev_device_new_from_devnum</function> | |
124 | takes a device type, which can be <constant>b</constant> for block devices or | |
125 | <constant>c</constant> for character devices, as well as a devnum (see | |
524f3e5c | 126 | <citerefentry project='man-pages'><refentrytitle>makedev</refentrytitle><manvolnum>3</manvolnum></citerefentry>). |
00dbd902 | 127 | <function>udev_device_new_from_subsystem_sysname</function> looks up devices based |
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128 | on the provided subsystem and sysname |
129 | (see <citerefentry><refentrytitle>udev_device_get_subsystem</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
130 | and | |
131 | <citerefentry><refentrytitle>udev_device_get_sysname</refentrytitle><manvolnum>3</manvolnum></citerefentry>) | |
132 | and <function>udev_device_new_from_device_id</function> looks up devices based on the provided | |
a8eaaee7 | 133 | device ID, which is a special string in one of the following four forms: |
2ef24a16 TG |
134 | <table> |
135 | <title>Device ID strings</title> | |
136 | ||
137 | <tgroup cols='2'> | |
138 | <colspec colname='example' /> | |
139 | <colspec colname='explanation' /> | |
140 | <thead><row> | |
141 | <entry>Example</entry> | |
142 | <entry>Explanation</entry> | |
143 | </row></thead> | |
144 | <tbody> | |
145 | <row><entry><varname>b8:2</varname></entry> | |
146 | <entry>block device major:minor</entry></row> | |
147 | ||
148 | <row><entry><varname>c128:1</varname></entry> | |
149 | <entry>char device major:minor</entry></row> | |
150 | ||
151 | <row><entry><varname>n3</varname></entry> | |
152 | <entry>network device ifindex</entry></row> | |
153 | ||
154 | <row><entry><varname>+sound:card29</varname></entry> | |
155 | <entry>kernel driver core subsystem:device name</entry></row> | |
156 | </tbody> | |
157 | </tgroup> | |
158 | </table> | |
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159 | </para> |
160 | ||
161 | <para><function>udev_device_new_from_environment</function> | |
162 | creates a device from the current environment (see | |
524f3e5c | 163 | <citerefentry project='man-pages'><refentrytitle>environ</refentrytitle><manvolnum>7</manvolnum></citerefentry>). |
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164 | Each key-value pair is interpreted in the same way as if it was |
165 | received in an uevent (see | |
166 | <citerefentry><refentrytitle>udev_monitor_receive_device</refentrytitle><manvolnum>3</manvolnum></citerefentry>). | |
167 | The keys <constant>DEVPATH</constant>, <constant>SUBSYSTEM</constant>, | |
168 | <constant>ACTION</constant>, and <constant>SEQNUM</constant> are mandatory.</para> | |
169 | ||
170 | </refsect1> | |
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171 | |
172 | <refsect1> | |
173 | <title>Return Value</title> | |
174 | ||
175 | <para>On success, <function>udev_device_new_from_syspath()</function>, | |
176 | <function>udev_device_new_from_devnum()</function>, | |
177 | <function>udev_device_new_from_subsystem_sysname()</function>, | |
178 | <function>udev_device_new_from_device_id()</function> and | |
179 | <function>udev_device_new_from_environment()</function> return a | |
180 | pointer to the allocated udev device. On failure, | |
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181 | <constant>NULL</constant> is returned, |
182 | and <varname>errno</varname> is set appropriately. | |
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183 | <function>udev_device_ref()</function> returns the argument |
184 | that it was passed, unmodified. | |
185 | <function>udev_device_unref()</function> always returns | |
186 | <constant>NULL</constant>.</para> | |
187 | </refsect1> | |
188 | ||
189 | <refsect1> | |
190 | <title>See Also</title> | |
191 | ||
192 | <para> | |
193 | <citerefentry><refentrytitle>udev_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
194 | <citerefentry><refentrytitle>udev_device_get_syspath</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
195 | <citerefentry><refentrytitle>udev_device_has_tag</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
196 | <citerefentry><refentrytitle>udev_enumerate_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
197 | <citerefentry><refentrytitle>udev_monitor_new_from_netlink</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
198 | <citerefentry><refentrytitle>udev_list_entry</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
199 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
200 | </para> | |
201 | </refsect1> | |
202 | ||
203 | </refentry> |