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06255d6f | 1 | <?xml version='1.0'?> <!--*-nxml-*--> |
3a54a157 | 2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" |
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3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" [ |
4 | <!ENTITY % entities SYSTEM "custom-entities.ent" > | |
5 | %entities; | |
6 | ]> | |
0307f791 | 7 | <!-- SPDX-License-Identifier: LGPL-2.1+ --> |
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8 | |
9 | <refentry id="udev_device_new_from_syspath" | |
10 | xmlns:xi="http://www.w3.org/2001/XInclude"> | |
11 | ||
12 | <refentryinfo> | |
13 | <title>udev_device_new_from_syspath</title> | |
14 | <productname>systemd</productname> | |
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15 | </refentryinfo> |
16 | ||
17 | <refmeta> | |
18 | <refentrytitle>udev_device_new_from_syspath</refentrytitle> | |
19 | <manvolnum>3</manvolnum> | |
20 | </refmeta> | |
21 | ||
22 | <refnamediv> | |
23 | <refname>udev_device_new_from_syspath</refname> | |
24 | <refname>udev_device_new_from_devnum</refname> | |
25 | <refname>udev_device_new_from_subsystem_sysname</refname> | |
26 | <refname>udev_device_new_from_device_id</refname> | |
27 | <refname>udev_device_new_from_environment</refname> | |
28 | <refname>udev_device_ref</refname> | |
29 | <refname>udev_device_unref</refname> | |
30 | ||
31 | <refpurpose>Create, acquire and release a udev device object</refpurpose> | |
32 | </refnamediv> | |
33 | ||
34 | <refsynopsisdiv> | |
35 | <funcsynopsis> | |
36 | <funcsynopsisinfo>#include <libudev.h></funcsynopsisinfo> | |
37 | ||
38 | <funcprototype> | |
39 | <funcdef>struct udev_device *<function>udev_device_new_from_syspath</function></funcdef> | |
40 | <paramdef>struct udev *<parameter>udev</parameter></paramdef> | |
41 | <paramdef>const char *<parameter>syspath</parameter></paramdef> | |
42 | </funcprototype> | |
43 | ||
44 | <funcprototype> | |
45 | <funcdef>struct udev_device *<function>udev_device_new_from_devnum</function></funcdef> | |
46 | <paramdef>struct udev *<parameter>udev</parameter></paramdef> | |
47 | <paramdef>char <parameter>type</parameter></paramdef> | |
48 | <paramdef>dev_t <parameter>devnum</parameter></paramdef> | |
49 | </funcprototype> | |
50 | ||
51 | <funcprototype> | |
52 | <funcdef>struct udev_device *<function>udev_device_new_from_subsystem_sysname</function></funcdef> | |
53 | <paramdef>struct udev *<parameter>udev</parameter></paramdef> | |
54 | <paramdef>const char *<parameter>subsystem</parameter></paramdef> | |
55 | <paramdef>const char *<parameter>sysname</parameter></paramdef> | |
56 | </funcprototype> | |
57 | ||
58 | <funcprototype> | |
59 | <funcdef>struct udev_device *<function>udev_device_new_from_device_id</function></funcdef> | |
60 | <paramdef>struct udev *<parameter>udev</parameter></paramdef> | |
61 | <paramdef>const char *<parameter>id</parameter></paramdef> | |
62 | </funcprototype> | |
63 | ||
64 | <funcprototype> | |
65 | <funcdef>struct udev_device *<function>udev_device_new_from_environment</function></funcdef> | |
66 | <paramdef>struct udev *<parameter>udev</parameter></paramdef> | |
67 | </funcprototype> | |
68 | ||
69 | <funcprototype> | |
70 | <funcdef>struct udev_device *<function>udev_device_ref</function></funcdef> | |
71 | <paramdef>struct udev_device *<parameter>udev_device</parameter></paramdef> | |
72 | </funcprototype> | |
73 | ||
74 | <funcprototype> | |
75 | <funcdef>struct udev_device *<function>udev_device_unref</function></funcdef> | |
76 | <paramdef>struct udev_device *<parameter>udev_device</parameter></paramdef> | |
77 | </funcprototype> | |
78 | ||
79 | </funcsynopsis> | |
80 | </refsynopsisdiv> | |
81 | ||
00dbd902 | 82 | <refsect1> |
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83 | <title>Description</title> |
84 | ||
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85 | <para><function>udev_device_new_from_syspath</function>, |
86 | <function>udev_device_new_from_devnum</function>, | |
87 | <function>udev_device_new_from_subsystem_sysname</function>, | |
88 | <function>udev_device_new_from_device_id</function>, and | |
89 | <function>udev_device_new_from_environment</function> | |
90 | allocate a new udev device object and returns a pointer to it. This | |
91 | object is opaque and must not be accessed by the caller via different | |
92 | means than functions provided by libudev. Initially, the reference count | |
93 | of the device is 1. You can acquire further references, and drop | |
94 | gained references via <function>udev_device_ref()</function> and | |
95 | <function>udev_device_unref()</function>. Once the reference count hits 0, | |
96 | the device object is destroyed and freed.</para> | |
97 | ||
98 | <para><function>udev_device_new_from_syspath</function>, | |
99 | <function>udev_device_new_from_devnum</function>, | |
100 | <function>udev_device_new_from_subsystem_sysname</function>, and | |
101 | <function>udev_device_new_from_device_id</function> | |
102 | create the device object based on information found in | |
b938cb90 | 103 | <filename>/sys</filename>, annotated with properties from the udev-internal |
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104 | device database. A syspath is any subdirectory of <filename>/sys</filename>, |
105 | with the restriction that a subdirectory of <filename>/sys/devices</filename> | |
106 | (or a symlink to one) represents a real device and as such must contain | |
107 | a <filename>uevent</filename> file. <function>udev_device_new_from_devnum</function> | |
108 | takes a device type, which can be <constant>b</constant> for block devices or | |
109 | <constant>c</constant> for character devices, as well as a devnum (see | |
524f3e5c | 110 | <citerefentry project='man-pages'><refentrytitle>makedev</refentrytitle><manvolnum>3</manvolnum></citerefentry>). |
00dbd902 | 111 | <function>udev_device_new_from_subsystem_sysname</function> looks up devices based |
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112 | on the provided subsystem and sysname |
113 | (see <citerefentry><refentrytitle>udev_device_get_subsystem</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
114 | and | |
115 | <citerefentry><refentrytitle>udev_device_get_sysname</refentrytitle><manvolnum>3</manvolnum></citerefentry>) | |
116 | and <function>udev_device_new_from_device_id</function> looks up devices based on the provided | |
a8eaaee7 | 117 | device ID, which is a special string in one of the following four forms: |
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118 | <table> |
119 | <title>Device ID strings</title> | |
120 | ||
121 | <tgroup cols='2'> | |
122 | <colspec colname='example' /> | |
123 | <colspec colname='explanation' /> | |
124 | <thead><row> | |
125 | <entry>Example</entry> | |
126 | <entry>Explanation</entry> | |
127 | </row></thead> | |
128 | <tbody> | |
129 | <row><entry><varname>b8:2</varname></entry> | |
130 | <entry>block device major:minor</entry></row> | |
131 | ||
132 | <row><entry><varname>c128:1</varname></entry> | |
133 | <entry>char device major:minor</entry></row> | |
134 | ||
135 | <row><entry><varname>n3</varname></entry> | |
136 | <entry>network device ifindex</entry></row> | |
137 | ||
138 | <row><entry><varname>+sound:card29</varname></entry> | |
139 | <entry>kernel driver core subsystem:device name</entry></row> | |
140 | </tbody> | |
141 | </tgroup> | |
142 | </table> | |
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143 | </para> |
144 | ||
145 | <para><function>udev_device_new_from_environment</function> | |
146 | creates a device from the current environment (see | |
524f3e5c | 147 | <citerefentry project='man-pages'><refentrytitle>environ</refentrytitle><manvolnum>7</manvolnum></citerefentry>). |
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148 | Each key-value pair is interpreted in the same way as if it was |
149 | received in an uevent (see | |
150 | <citerefentry><refentrytitle>udev_monitor_receive_device</refentrytitle><manvolnum>3</manvolnum></citerefentry>). | |
151 | The keys <constant>DEVPATH</constant>, <constant>SUBSYSTEM</constant>, | |
152 | <constant>ACTION</constant>, and <constant>SEQNUM</constant> are mandatory.</para> | |
153 | ||
154 | </refsect1> | |
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155 | |
156 | <refsect1> | |
157 | <title>Return Value</title> | |
158 | ||
159 | <para>On success, <function>udev_device_new_from_syspath()</function>, | |
160 | <function>udev_device_new_from_devnum()</function>, | |
161 | <function>udev_device_new_from_subsystem_sysname()</function>, | |
162 | <function>udev_device_new_from_device_id()</function> and | |
163 | <function>udev_device_new_from_environment()</function> return a | |
164 | pointer to the allocated udev device. On failure, | |
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165 | <constant>NULL</constant> is returned, |
166 | and <varname>errno</varname> is set appropriately. | |
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167 | <function>udev_device_ref()</function> returns the argument |
168 | that it was passed, unmodified. | |
169 | <function>udev_device_unref()</function> always returns | |
170 | <constant>NULL</constant>.</para> | |
171 | </refsect1> | |
172 | ||
173 | <refsect1> | |
174 | <title>See Also</title> | |
175 | ||
176 | <para> | |
177 | <citerefentry><refentrytitle>udev_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
178 | <citerefentry><refentrytitle>udev_device_get_syspath</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
179 | <citerefentry><refentrytitle>udev_device_has_tag</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
180 | <citerefentry><refentrytitle>udev_enumerate_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
181 | <citerefentry><refentrytitle>udev_monitor_new_from_netlink</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
182 | <citerefentry><refentrytitle>udev_list_entry</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
183 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
184 | </para> | |
185 | </refsect1> | |
186 | ||
187 | </refentry> |