1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
|
<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
<!ENTITY % entities SYSTEM "custom-entities.ent" >
%entities;
]>
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
<refentry id="udev_device_has_tag"
xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>udev_device_has_tag</title>
<productname>systemd</productname>
</refentryinfo>
<refmeta>
<refentrytitle>udev_device_has_tag</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>udev_device_has_tag</refname>
<refname>udev_device_has_current_tag</refname>
<refname>udev_device_get_devlinks_list_entry</refname>
<refname>udev_device_get_properties_list_entry</refname>
<refname>udev_device_get_tags_list_entry</refname>
<refname>udev_device_get_current_tags_list_entry</refname>
<refname>udev_device_get_sysattr_list_entry</refname>
<refname>udev_device_get_property_value</refname>
<refname>udev_device_get_sysattr_value</refname>
<refname>udev_device_set_sysattr_value</refname>
<refpurpose>Retrieve or set device attributes</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include <libudev.h></funcsynopsisinfo>
<funcprototype>
<funcdef>int <function>udev_device_has_tag</function></funcdef>
<paramdef>struct udev_device *<parameter>udev_device</parameter></paramdef>
<paramdef>const char *<parameter>tag</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>udev_device_has_current_tag</function></funcdef>
<paramdef>struct udev_device *<parameter>udev_device</parameter></paramdef>
<paramdef>const char *<parameter>tag</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>struct udev_list_entry *<function>udev_device_get_devlinks_list_entry</function></funcdef>
<paramdef>struct udev_device *<parameter>udev_device</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>struct udev_list_entry *<function>udev_device_get_properties_list_entry</function></funcdef>
<paramdef>struct udev_device *<parameter>udev_device</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>struct udev_list_entry *<function>udev_device_get_tags_list_entry</function></funcdef>
<paramdef>struct udev_device *<parameter>udev_device</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>struct udev_list_entry *<function>udev_device_get_current_tags_list_entry</function></funcdef>
<paramdef>struct udev_device *<parameter>udev_device</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>struct udev_list_entry *<function>udev_device_get_sysattr_list_entry</function></funcdef>
<paramdef>struct udev_device *<parameter>udev_device</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>const char *<function>udev_device_get_property_value</function></funcdef>
<paramdef>struct udev_device *<parameter>udev_device</parameter></paramdef>
<paramdef>const char *<parameter>key</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>const char *<function>udev_device_get_sysattr_value</function></funcdef>
<paramdef>struct udev_device *<parameter>udev_device</parameter></paramdef>
<paramdef>const char *<parameter>sysattr</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>udev_device_set_sysattr_value</function></funcdef>
<paramdef>struct udev_device *<parameter>udev_device</parameter></paramdef>
<paramdef>const char *<parameter>sysattr</parameter></paramdef>
<paramdef>const char *<parameter>value</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><function>udev_device_has_tag()</function> returns a value larger than zero if the specified
device object has the indicated tag assigned to it, and zero otherwise. See
<citerefentry><refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum></citerefentry> for details on
the tags concept. <function>udev_device_has_current_tag()</function> executes a similar check, however
only determines whether the indicated tag was set as result of the most recent event seen for the
device. Tags are "sticky", i.e. once set for a device they remain on the device until the device is
unplugged, even if the rules run for later events of the same device do not set them anymore. Any tag for
which <function>udev_device_has_current_tag()</function> returns true will hence also return true when
passed to <function>udev_device_has_tag()</function>, but the opposite might not be true, in case a tag is
no longer configured by the rules applied to the most recent device even.</para>
<para><function>udev_device_get_tags_list_entry()</function> returns a
<structname>udev_list_entry</structname> object, encapsulating a list of tags set for the specified
device. Similar, <function>udev_device_get_current_tags_list_entry()</function> returns a list of tags
set for the specified device as effect of the most recent device event seen (see above for details on the
difference).</para>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>On success, <function>udev_device_has_tag()</function> and
<function>udev_device_has_current_tag()</function> return positive or <constant>0</constant>, depending
on whether the device has the given tag or not. On failure, a negative error code is returned.</para>
<para>On success, <function>udev_device_get_devlinks_list_entry()</function>,
<function>udev_device_get_properties_list_entry()</function>,
<function>udev_device_get_tags_list_entry()</function>,
<function>udev_device_get_current_tags_list_entry()</function> and
<function>udev_device_get_sysattr_list_entry()</function> return a pointer to the first entry of the
retrieved list. If that list is empty, or if an error occurred, <constant>NULL</constant> is
returned.</para>
<para>On success,
<function>udev_device_get_property_value()</function> and
<function>udev_device_get_sysattr_value()</function> return a
pointer to a constant string of the requested value. On error,
<constant>NULL</constant> is returned. Attributes that may
contain <constant>NUL</constant> bytes should not be retrieved
with <function>udev_device_get_sysattr_value()</function>;
instead, read them directly from the files within the device's
<property>syspath</property>.</para>
<para>On success,
<function>udev_device_set_sysattr_value()</function> returns
an integer greater than, or equal to, <constant>0</constant>.
On failure, a negative error code is returned. Values that
contain <constant>NUL</constant> bytes should not be set with
this function; instead, write them directly to the files within
the device's <property>syspath</property>.</para>
</refsect1>
<refsect1>
<title>History</title>
<para><function>udev_device_get_devlinks_list_entry()</function>,
<function>udev_device_get_properties_list_entry()</function>,
<function>udev_device_get_tags_list_entry()</function>,
<function>udev_device_get_sysattr_list_entry()</function>,
<function>udev_device_get_property_value()</function>,
<function>udev_device_has_tag()</function>,
<function>udev_device_get_sysattr_value()</function>, and
<function>udev_device_set_sysattr_value()</function> were added in version 221.</para>
<para><function>udev_device_has_current_tag()</function> and
<function>udev_device_get_current_tags_list_entry()</function> were added in version 247.</para>
</refsect1>
<refsect1>
<title>See Also</title>
<para><simplelist type="inline">
<member><citerefentry><refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum></citerefentry></member>
<member><citerefentry><refentrytitle>udev_new</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
<member><citerefentry><refentrytitle>udev_device_new_from_syspath</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
<member><citerefentry><refentrytitle>udev_device_get_syspath</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
<member><citerefentry><refentrytitle>udev_enumerate_new</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
<member><citerefentry><refentrytitle>udev_monitor_new_from_netlink</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
<member><citerefentry><refentrytitle>udev_list_entry</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
<member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
</simplelist></para>
</refsect1>
</refentry>
|
