1<?xml version='1.0'?> <!--*-nxml-*--> 2<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" 3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" [ 4<!ENTITY % entities SYSTEM "custom-entities.ent" > 5%entities; 6]> 7<!-- SPDX-License-Identifier: LGPL-2.1-or-later --> 8 9<refentry id="udev_device_has_tag" 10 xmlns:xi="http://www.w3.org/2001/XInclude"> 11 12 <refentryinfo> 13 <title>udev_device_has_tag</title> 14 <productname>systemd</productname> 15 </refentryinfo> 16 17 <refmeta> 18 <refentrytitle>udev_device_has_tag</refentrytitle> 19 <manvolnum>3</manvolnum> 20 </refmeta> 21 22 <refnamediv> 23 <refname>udev_device_has_tag</refname> 24 <refname>udev_device_has_current_tag</refname> 25 <refname>udev_device_get_devlinks_list_entry</refname> 26 <refname>udev_device_get_properties_list_entry</refname> 27 <refname>udev_device_get_tags_list_entry</refname> 28 <refname>udev_device_get_current_tags_list_entry</refname> 29 <refname>udev_device_get_sysattr_list_entry</refname> 30 <refname>udev_device_get_property_value</refname> 31 <refname>udev_device_get_sysattr_value</refname> 32 <refname>udev_device_set_sysattr_value</refname> 33 34 <refpurpose>Retrieve or set device attributes</refpurpose> 35 </refnamediv> 36 37 <refsynopsisdiv> 38 <funcsynopsis> 39 <funcsynopsisinfo>#include <libudev.h></funcsynopsisinfo> 40 41 <funcprototype> 42 <funcdef>int <function>udev_device_has_tag</function></funcdef> 43 <paramdef>struct udev_device *<parameter>udev_device</parameter></paramdef> 44 <paramdef>const char *<parameter>tag</parameter></paramdef> 45 </funcprototype> 46 47 <funcprototype> 48 <funcdef>int <function>udev_device_has_current_tag</function></funcdef> 49 <paramdef>struct udev_device *<parameter>udev_device</parameter></paramdef> 50 <paramdef>const char *<parameter>tag</parameter></paramdef> 51 </funcprototype> 52 53 <funcprototype> 54 <funcdef>struct udev_list_entry *<function>udev_device_get_devlinks_list_entry</function></funcdef> 55 <paramdef>struct udev_device *<parameter>udev_device</parameter></paramdef> 56 </funcprototype> 57 58 <funcprototype> 59 <funcdef>struct udev_list_entry *<function>udev_device_get_properties_list_entry</function></funcdef> 60 <paramdef>struct udev_device *<parameter>udev_device</parameter></paramdef> 61 </funcprototype> 62 63 <funcprototype> 64 <funcdef>struct udev_list_entry *<function>udev_device_get_tags_list_entry</function></funcdef> 65 <paramdef>struct udev_device *<parameter>udev_device</parameter></paramdef> 66 </funcprototype> 67 68 <funcprototype> 69 <funcdef>struct udev_list_entry *<function>udev_device_get_current_tags_list_entry</function></funcdef> 70 <paramdef>struct udev_device *<parameter>udev_device</parameter></paramdef> 71 </funcprototype> 72 73 <funcprototype> 74 <funcdef>struct udev_list_entry *<function>udev_device_get_sysattr_list_entry</function></funcdef> 75 <paramdef>struct udev_device *<parameter>udev_device</parameter></paramdef> 76 </funcprototype> 77 78 <funcprototype> 79 <funcdef>const char *<function>udev_device_get_property_value</function></funcdef> 80 <paramdef>struct udev_device *<parameter>udev_device</parameter></paramdef> 81 <paramdef>const char *<parameter>key</parameter></paramdef> 82 </funcprototype> 83 84 <funcprototype> 85 <funcdef>const char *<function>udev_device_get_sysattr_value</function></funcdef> 86 <paramdef>struct udev_device *<parameter>udev_device</parameter></paramdef> 87 <paramdef>const char *<parameter>sysattr</parameter></paramdef> 88 </funcprototype> 89 90 <funcprototype> 91 <funcdef>int <function>udev_device_set_sysattr_value</function></funcdef> 92 <paramdef>struct udev_device *<parameter>udev_device</parameter></paramdef> 93 <paramdef>const char *<parameter>sysattr</parameter></paramdef> 94 <paramdef>const char *<parameter>value</parameter></paramdef> 95 </funcprototype> 96 97 </funcsynopsis> 98 </refsynopsisdiv> 99 100 <refsect1> 101 <title>Description</title> 102 103 <para><function>udev_device_has_tag()</function> returns a valuer larger than zero if the specified 104 device object has the indicated tag assigned to it, and zero otherwise. See 105 <citerefentry><refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum></citerefentry> for details on 106 the tags concept. <function>udev_device_has_current_tag()</function> executes a similar check, however 107 only determines whether the indicated tag was set as result of the most recent event seen for the 108 device. Tags are "sticky", i.e. once set for a device they remain on the device until the device is 109 unplugged, even if the rules run for later events of the same device do not set them anymore. Any tag for 110 which <function>udev_device_has_current_tag()</function> returns true will hence also return true when 111 passed to <function>udev_device_has_tag()</function>, but the opposite might not be true, in case a tag is 112 no longer configured by the rules applied to the most recent device even.</para> 113 114 <para><function>udev_device_get_tags_list_entry()</function> returns a 115 <structname>udev_list_entry</structname> object, encapsulating a list of tags set for the specified 116 device. Similar, <function>udev_device_get_current_tags_list_entry()</function> returns a list of tags 117 set for the specified device as effect of the most recent device event seen (see above for details on the 118 difference).</para> 119 </refsect1> 120 121 <refsect1> 122 <title>Return Value</title> 123 124 <para>On success, <function>udev_device_has_tag()</function> and 125 <function>udev_device_has_current_tag()</function> return positive or <constant>0</constant>, depending 126 on whether the device has the given tag or not. On failure, a negative error code is returned.</para> 127 128 <para>On success, <function>udev_device_get_devlinks_list_entry()</function>, 129 <function>udev_device_get_properties_list_entry()</function>, 130 <function>udev_device_get_tags_list_entry()</function>, 131 <function>udev_device_get_current_tags_list_entry()</function> and 132 <function>udev_device_get_sysattr_list_entry()</function> return a pointer to the first entry of the 133 retrieved list. If that list is empty, or if an error occurred, <constant>NULL</constant> is 134 returned.</para> 135 136 <para>On success, 137 <function>udev_device_get_property_value()</function> and 138 <function>udev_device_get_sysattr_value()</function> return a 139 pointer to a constant string of the requested value. On error, 140 <constant>NULL</constant> is returned. Attributes that may 141 contain <constant>NUL</constant> bytes should not be retrieved 142 with <function>udev_device_get_sysattr_value()</function>; 143 instead, read them directly from the files within the device's 144 <property>syspath</property>.</para> 145 146 <para>On success, 147 <function>udev_device_set_sysattr_value()</function> returns 148 an integer greater than, or equal to, <constant>0</constant>. 149 On failure, a negative error code is returned. Values that 150 contain <constant>NUL</constant> bytes should not be set with 151 this function; instead, write them directly to the files within 152 the device's <property>syspath</property>.</para> 153 </refsect1> 154 155 <refsect1> 156 <title>See Also</title> 157 158 <para> 159 <citerefentry><refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum></citerefentry>, 160 <citerefentry><refentrytitle>udev_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>, 161 <citerefentry><refentrytitle>udev_device_new_from_syspath</refentrytitle><manvolnum>3</manvolnum></citerefentry>, 162 <citerefentry><refentrytitle>udev_device_get_syspath</refentrytitle><manvolnum>3</manvolnum></citerefentry>, 163 <citerefentry><refentrytitle>udev_enumerate_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>, 164 <citerefentry><refentrytitle>udev_monitor_new_from_netlink</refentrytitle><manvolnum>3</manvolnum></citerefentry>, 165 <citerefentry><refentrytitle>udev_list_entry</refentrytitle><manvolnum>3</manvolnum></citerefentry>, 166 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, 167 </para> 168 </refsect1> 169 170</refentry> 171