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systemd-stable/man/sd_hwdb_new.xml
Nick Rosbrook 60f0ba7556 sd-hwdb: add sd_hwdb_new_from_path
The existing sd_hwdb_new function always initializes the hwdb from the
first successful hwdb.bin it finds from hwdb_bin_paths. This means there
is currently no way to initialize a hwdb from an explicit path, which
would be useful for systemd-hwdb query.

Add sd_hwdb_new_from_path to allow a sd_hwdb to be initialized from a
custom path outside of hwdb_bin_paths.
2022-05-27 09:40:54 -04:00

132 lines
4.8 KiB
XML

<?xml version='1.0'?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
<refentry id="sd_hwdb_new" xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>sd_hwdb_new</title>
<productname>systemd</productname>
</refentryinfo>
<refmeta>
<refentrytitle>sd_hwdb_new</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>sd_hwdb_new</refname>
<refname>sd_hwdb_new_from_path</refname>
<refname>sd_hwdb_ref</refname>
<refname>sd_hwdb_unref</refname>
<refpurpose>Create a new hwdb object and create or destroy references to it</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include &lt;systemd/sd-hwdb.h&gt;</funcsynopsisinfo>
<funcprototype>
<funcdef>int <function>sd_hwdb_new</function></funcdef>
<paramdef>sd_hwdb **<parameter>hwdb</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_hwdb_new_from_path</function></funcdef>
<paramdef>const char *<parameter>path</parameter></paramdef>
<paramdef>sd_hwdb **<parameter>hwdb</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>sd_hwdb* <function>sd_hwdb_ref</function></funcdef>
<paramdef>sd_hwdb *<parameter>hwdb</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>sd_hwdb* <function>sd_hwdb_unref</function></funcdef>
<paramdef>sd_hwdb *<parameter>hwdb</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><function>sd_hwdb_new()</function> creates a new hwdb object to access the binary hwdb
database. Upon initialization, the file containing the binary representation of the hardware database is
located and opened. The new object is returned in <parameter>hwdb</parameter>.</para>
<para><function>sd_hwdb_new_from_path()</function> may be used to specify the path from which the binary
hardware database should be opened.</para>
<para>The <parameter>hwdb</parameter> object is reference counted. <function>sd_hwdb_ref()</function> and
<function>sd_hwdb_unref()</function> may be used to get a new reference or destroy an existing reference
to an object. The caller must dispose of the reference acquired with <function>sd_hwdb_new()</function>
by calling <function>sd_hwdb_unref()</function> when done with the object.</para>
<para>Use
<citerefentry><refentrytitle>sd_hwdb_seek</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_hwdb_get</refentrytitle><manvolnum>3</manvolnum></citerefentry>, and
<citerefentry><refentrytitle>sd_hwdb_enumerate</refentrytitle><manvolnum>3</manvolnum></citerefentry> to
access entries.</para>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>On success, <function>sd_hwdb_new()</function> and <function>sd_hwdb_new_from_path()</function>
return a non-negative integer. On failure, a negative errno-style error code is returned.</para>
<para><function>sd_hwdb_ref()</function> always returns the argument.
</para>
<para><function>sd_hwdb_unref()</function> always returns <constant>NULL</constant>.
</para>
<refsect2>
<title>Errors</title>
<para>Returned errors may indicate the following problems:</para>
<variablelist>
<varlistentry>
<term><constant>-ENOENT</constant></term>
<listitem><para>The binary hardware database file could not be located. See
<citerefentry><refentrytitle>systemd-hwdb</refentrytitle><manvolnum>8</manvolnum></citerefentry>
for more information.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>-EINVAL</constant></term>
<listitem><para>The located binary hardware database file is in an incompatible format.
</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-ENOMEM</constant></term>
<listitem><para>Memory allocation failed.</para></listitem>
</varlistentry>
</variablelist>
</refsect2>
</refsect1>
<xi:include href="libsystemd-pkgconfig.xml" />
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd-hwdb</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-hwdb</refentrytitle><manvolnum>3</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>