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udevadm: allow a .device unit to be specified for query and trigger

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This is convenient when working with device units in systemd. Instead of
converting the systemd unit name to a path to feed to udevadm, udevadm
info|trigger can be called directly on the unit name.

The man page is reworked a bit to describe the modern syntax with positional
arguments first. It's just simpler to use than the positional options.
This commit is contained in:
Zbigniew Jędrzejewski-Szmek 2018-12-10 11:46:21 +01:00
parent d539f79176
commit b6854081ff
3 changed files with 46 additions and 34 deletions
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53
man/udevadm.xml
View File

@ -76,39 +76,40 @@
<refsect2><title>udevadm info
<arg choice="opt"><replaceable>options</replaceable></arg>
<arg choice="opt"><replaceable>devpath</replaceable>|<replaceable>file</replaceable></arg>
<arg choice="opt"><replaceable>devpath</replaceable>|<replaceable>file</replaceable>|<replaceable>unit</replaceable></arg>
</title>
<para>Queries the udev database for device information
stored in the udev database. It can also query the properties
of a device from its sysfs representation to help creating udev
rules that match this device.</para>
<para>Query the udev database for device information.</para>
<para>A positional argument should be used to specify a device. It may be a device name (in which case
it must start with <filename>/dev/</filename>), a sys path (in which case it must start with
<filename>/sys/</filename>), or a systemd device unit name (in which case it must end with
<literal>.device</literal>, see
<citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
</para>
<variablelist>
<varlistentry>
<term><option>-q</option></term>
<term><option>--query=<replaceable>TYPE</replaceable></option></term>
<listitem>
<para>Query the database for the specified type of device
data. It needs the <option>--path</option> or
<option>--name</option> to identify the specified device.
<para>Query the database for the specified type of device data.
Valid <replaceable>TYPE</replaceable>s are:
<constant>name</constant>, <constant>symlink</constant>,
<constant>path</constant>, <constant>property</constant>,
<constant>all</constant>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-p</option></term>
<term><option>--path=<replaceable>DEVPATH</replaceable></option></term>
<listitem>
<para>The <filename>/sys</filename> path of the device to
query, e.g.
<filename><optional>/sys</optional>/class/block/sda</filename>.
Note that this option usually is not very useful, since
<command>udev</command> can guess the type of the
argument, so <command>udevadm info
--path=/class/block/sda</command> is equivalent to
<command>udevadm info /sys/class/block/sda</command>.</para>
<para>The <filename>/sys</filename> path of the device to query, e.g.
<filename><optional>/sys</optional>/class/block/sda</filename>. This option is an alternative to
the positional argument with a <filename>/sys/</filename> prefix. <command>udevadm info
--path=/class/block/sda</command> is equivalent to <command>udevadm info
/sys/class/block/sda</command>.</para>
</listitem>
</varlistentry>
<varlistentry>
@ -116,11 +117,9 @@
<term><option>--name=<replaceable>FILE</replaceable></option></term>
<listitem>
<para>The name of the device node or a symlink to query,
e.g. <filename><optional>/dev</optional>/sda</filename>.
Note that this option usually is not very useful, since
<command>udev</command> can guess the type of the
argument, so <command>udevadm info --name=sda</command> is
equivalent to <command>udevadm info /dev/sda</command>.</para>
e.g. <filename><optional>/dev</optional>/sda</filename>. This option is an alternative to the
positional argument with a <filename>/dev/</filename> prefix. <command>udevadm info
--name=sda</command> is equivalent to <command>udevadm info /dev/sda</command>.</para>
</listitem>
</varlistentry>
<varlistentry>
@ -179,17 +178,17 @@
<xi:include href="standard-options.xml" xpointer="help" />
</variablelist>
<para>In addition, an optional positional argument can be used
to specify a device name or a sys path. It must start with
<filename>/dev</filename> or <filename>/sys</filename>
respectively.</para>
</refsect2>
<refsect2><title>udevadm trigger
<arg choice="opt"><replaceable>options</replaceable></arg>
<arg choice="opt" rep="repeat"><replaceable>devpath</replaceable>|<replaceable>file</replaceable></arg></title>
<arg choice="opt" rep="repeat"><replaceable>devpath</replaceable>|<replaceable>file</replaceable>|<replaceable>unit</replaceable></arg>
</title>
<para>Request device events from the kernel. Primarily used to replay events at system coldplug time.</para>
<para>Takes one or more device specifications as arguments. See the description of <command>info</command>
above.</para>
<variablelist>
<varlistentry>
<term><option>-v</option></term>

2
src/udev/udevadm-info.c
View File

@ -440,7 +440,7 @@ int info_main(int argc, char *argv[], void *userdata) {
r = find_device(argv[optind], NULL, &device);
if (r == -EINVAL)
return log_error_errno(r, "Bad argument \"%s\", an absolute path in /dev/ or /sys expected: %m",
return log_error_errno(r, "Bad argument \"%s\", expected an absolute path in /dev/ or /sys or a unit name: %m",
argv[optind]);
if (r < 0)
return log_error_errno(r, "Unknown device \"%s\": %m", argv[optind]);

23
src/udev/udevadm-util.c
View File

@ -6,18 +6,31 @@
#include "device-private.h"
#include "path-util.h"
#include "udevadm-util.h"
#include "unit-name.h"
int find_device(const char *id, const char *prefix, sd_device **ret) {
_cleanup_free_ char *buf = NULL;
_cleanup_free_ char *path = NULL;
int r;
assert(id);
assert(ret);
if (prefix && !path_startswith(id, prefix)) {
buf = path_join(prefix, id);
if (!buf)
if (prefix) {
if (!path_startswith(id, prefix)) {
id = path = path_join(prefix, id);
if (!path)
return -ENOMEM;
id = buf;
}
} else {
/* In cases where the argument is generic (no prefix specified),
* check if the argument looks like a device unit name. */
if (unit_name_is_valid(id, UNIT_NAME_PLAIN) &&
unit_name_to_type(id) == UNIT_DEVICE) {
r = unit_name_to_path(id, &path);
if (r < 0)
return log_debug_errno(r, "Failed to convert \"%s\" to a device path: %m", id);
id = path;
}
}
if (path_startswith(id, "/sys/"))