mirror of
https://github.com/systemd/systemd.git
synced 2024-11-23 02:03:37 +08:00
172 lines
6.9 KiB
XML
172 lines
6.9 KiB
XML
<?xml version='1.0'?>
|
|
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
|
|
"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
|
|
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
|
|
|
|
<refentry id="sd_hwdb_get" xmlns:xi="http://www.w3.org/2001/XInclude">
|
|
<refentryinfo>
|
|
<title>sd_hwdb_get</title>
|
|
<productname>systemd</productname>
|
|
</refentryinfo>
|
|
|
|
<refmeta>
|
|
<refentrytitle>sd_hwdb_get</refentrytitle>
|
|
<manvolnum>3</manvolnum>
|
|
</refmeta>
|
|
|
|
<refnamediv>
|
|
<refname>sd_hwdb_get</refname>
|
|
<refname>sd_hwdb_seek</refname>
|
|
<refname>sd_hwdb_enumerate</refname>
|
|
<refname>SD_HWDB_FOREACH_PROPERTY</refname>
|
|
|
|
<refpurpose>Seek to a location in hwdb or access entries</refpurpose>
|
|
</refnamediv>
|
|
|
|
<refsynopsisdiv>
|
|
<funcsynopsis>
|
|
<funcsynopsisinfo>#include <systemd/sd-hwdb.h></funcsynopsisinfo>
|
|
|
|
<funcprototype>
|
|
<funcdef>int <function>sd_hwdb_get</function></funcdef>
|
|
<paramdef>sd_hwdb *<parameter>hwdb</parameter></paramdef>
|
|
<paramdef>const char *<parameter>modalias</parameter></paramdef>
|
|
<paramdef>const char *<parameter>key</parameter></paramdef>
|
|
<paramdef>const char **<parameter>value</parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
<funcprototype>
|
|
<funcdef>int <function>sd_hwdb_seek</function></funcdef>
|
|
<paramdef>sd_hwdb *<parameter>hwdb</parameter></paramdef>
|
|
<paramdef>const char *<parameter>modalias</parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
<funcprototype>
|
|
<funcdef>int <function>sd_hwdb_enumerate</function></funcdef>
|
|
<paramdef>sd_hwdb *<parameter>hwdb</parameter></paramdef>
|
|
<paramdef>const char **<parameter>key</parameter></paramdef>
|
|
<paramdef>const char **<parameter>value</parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
<funcprototype>
|
|
<funcdef><function>SD_HWDB_FOREACH_PROPERTY</function></funcdef>
|
|
<paramdef>hwdb</paramdef>
|
|
<paramdef>modalias</paramdef>
|
|
<paramdef>key</paramdef>
|
|
<paramdef>value</paramdef>
|
|
</funcprototype>
|
|
</funcsynopsis>
|
|
</refsynopsisdiv>
|
|
|
|
<refsect1>
|
|
<title>Description</title>
|
|
|
|
<para><function>sd_hwdb_get()</function> queries the <parameter>hwdb</parameter> object created earlier
|
|
with <citerefentry><refentrytitle>sd_hwdb_new</refentrytitle><manvolnum>3</manvolnum></citerefentry> for
|
|
entries matching the specified string <parameter>modalias</parameter>, and returns the value
|
|
corresponding to the key <parameter>key</parameter>. The value is returned as a
|
|
<constant>NUL</constant>-terminated string in <parameter>value</parameter>. It must not be modified by
|
|
the caller and is valid as long as a reference to <parameter>hwdb</parameter> is kept. When multiple
|
|
patterns in the database match <parameter>modalias</parameter>, the one with the highest priority is
|
|
used. See <citerefentry><refentrytitle>hwdb</refentrytitle><manvolnum>7</manvolnum></citerefentry> for
|
|
details.</para>
|
|
|
|
<para><function>sd_hwdb_seek()</function> selects entries matching the specified string
|
|
<parameter>modalias</parameter>. Subsequent queries with <function>sd_hwdb_enumerate()</function> will
|
|
access the key-value pairs for that string.</para>
|
|
|
|
<para><function>sd_hwdb_enumerate()</function> returns (in turn) all the key-value pairs defined for the
|
|
string used with <function>sd_hwdb_seek()</function>. Each pair is returned as
|
|
<constant>NUL</constant>-terminated strings in <parameter>key</parameter> and
|
|
<parameter>value</parameter>. The strings must not be modified by the caller and are valid as long as a
|
|
reference to <parameter>hwdb</parameter> is kept. When multiple patterns in the database match
|
|
<parameter>modalias</parameter>, the combination of all matching key-value pairs is used. See
|
|
<citerefentry><refentrytitle>hwdb</refentrytitle><manvolnum>7</manvolnum></citerefentry> for
|
|
details.</para>
|
|
|
|
<para>The <function>SD_HWDB_FOREACH_PROPERTY()</function> macro combines
|
|
<function>sd_hwdb_seek()</function> and <function>sd_hwdb_enumerate()</function>. No error handling is
|
|
performed and iteration simply stops on error. See the example below.</para>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>Return Value</title>
|
|
|
|
<para>On success, <function>sd_hwdb_get()</function> and <function>sd_hwdb_seek()</function> return a
|
|
non-negative integer. On failure, they return a negative errno-style error code.</para>
|
|
|
|
<para><function>sd_hwdb_enumerate()</function> returns a positive integer if another key-value pair was found or zero if
|
|
all entries have already been enumerated. On failure, it returns a negative errno-style error code.
|
|
</para>
|
|
|
|
<refsect2>
|
|
<title>Errors</title>
|
|
|
|
<para>Returned errors may indicate the following problems:</para>
|
|
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><constant>-EINVAL</constant></term>
|
|
|
|
<listitem><para>A parameter is <constant>NULL</constant>.</para>
|
|
|
|
<xi:include href="version-info.xml" xpointer="v246"/></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><constant>-ENOENT</constant></term>
|
|
|
|
<listitem><para>An entry for the specified <parameter>modalias</parameter> was not found.
|
|
</para>
|
|
|
|
<xi:include href="version-info.xml" xpointer="v246"/></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><constant>-EAGAIN</constant></term>
|
|
|
|
<listitem><para><function>sd_hwdb_seek()</function> was not called before
|
|
<function>sd_hwdb_enumerate()</function>.</para>
|
|
|
|
<xi:include href="version-info.xml" xpointer="v246"/></listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</refsect2>
|
|
</refsect1>
|
|
|
|
<xi:include href="libsystemd-pkgconfig.xml" />
|
|
|
|
<refsect1>
|
|
<title>Examples</title>
|
|
|
|
<example>
|
|
<title>Look up hwdb entries for a USB device</title>
|
|
|
|
<programlisting><xi:include href="hwdb-usb-device.c" parse="text" /></programlisting>
|
|
|
|
<para>The effect is similar to calling <command>systemd-hwdb query usb:v046DpC534</command>.
|
|
</para>
|
|
</example>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>History</title>
|
|
<para><function>sd_hwdb_get()</function>,
|
|
<function>sd_hwdb_seek()</function>,
|
|
<function>sd_hwdb_enumerate()</function>, and
|
|
<function>SD_HWDB_FOREACH_PROPERTY()</function> were added in version 246.</para>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>See Also</title>
|
|
|
|
<para><simplelist type="inline">
|
|
<member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
|
|
<member><citerefentry><refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
|
|
<member><citerefentry><refentrytitle>sd-hwdb</refentrytitle><manvolnum>3</manvolnum></citerefentry></member>
|
|
<member><citerefentry><refentrytitle>systemd-hwdb</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
|
|
</simplelist></para>
|
|
</refsect1>
|
|
|
|
</refentry>
|