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man: add SD_HWDB_FOREACH_PROPERTY with an example

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This commit is contained in:
Zbigniew Jędrzejewski-Szmek 2020-04-21 09:07:08 +02:00
parent ec7ea47dae
commit 32c4d2ba62
3 changed files with 57 additions and 1 deletions
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28
man/hwdb-usb-device.c Normal file
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@ -0,0 +1,28 @@
#include <stdio.h>
#include <stdint.h>
#include <sd-hwdb.h>
int print_usb_properties(uint16_t vid, uint16_t pid) {
char match[15];
sd_hwdb *hwdb;
const char *key, *value;
int r;
/* Match this USB vendor and product ID combination */
snprintf(match, sizeof match, "usb:v%04Xp%04X", vid, pid);
r = sd_hwdb_new(&hwdb);
if (r < 0)
return r;
SD_HWDB_FOREACH_PROPERTY(hwdb, match, key, value)
printf("%s: \"%s\" → \"%s\"\n", match, key, value);
sd_hwdb_unref(hwdb);
return 0;
}
int main(int argc, char **argv) {
print_usb_properties(0x046D, 0xC534);
return 0;
}

5
man/rules/meson.build
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@ -560,7 +560,10 @@ manpages = [
'3',
['sd_get_machine_names', 'sd_get_sessions', 'sd_get_uids'],
'HAVE_PAM'],
['sd_hwdb_get', '3', ['sd_hwdb_enumerate', 'sd_hwdb_seek'], ''],
['sd_hwdb_get',
'3',
['SD_HWDB_FOREACH_PROPERTY', 'sd_hwdb_enumerate', 'sd_hwdb_seek'],
''],
['sd_hwdb_new', '3', ['sd_hwdb_ref', 'sd_hwdb_unref'], ''],
['sd_id128_get_machine',
'3',

25
man/sd_hwdb_get.xml
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@ -18,6 +18,7 @@
<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>
@ -47,6 +48,13 @@
<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>
@ -75,6 +83,10 @@
<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 interation simply stops on error. See the example below.</para>
</refsect1>
<refsect1>
@ -118,6 +130,19 @@
<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>See Also</title>