udevadm: introduce cat command

This introduces 'udevadm cat' command, that shows udev rules files or
udev.conf, which may be useful for debugging.

Closes #35818.

diff --git a/man/udevadm.xml b/man/udevadm.xml
index 842b7b5ab50bf10afd596cc76c0ad664cefa178d..507ab49b48435391c1ee9820da02bd3c71e3430d 100644 (file)
--- a/man/udevadm.xml
+++ b/man/udevadm.xml
@@ -53,6 +53,11 @@
       <arg choice="opt" rep="repeat">options</arg>
       <arg choice="opt" rep="repeat"><replaceable>file</replaceable></arg>
     </cmdsynopsis>
+    <cmdsynopsis>
+      <command>udevadm cat</command>
+      <arg choice="opt" rep="repeat">options</arg>
+      <arg choice="opt" rep="repeat"><replaceable>file</replaceable></arg>
+    </cmdsynopsis>
     <cmdsynopsis>
       <command>udevadm wait <optional>options</optional> <replaceable>device|syspath</replaceable></command>
     </cmdsynopsis>
@@ -1019,6 +1024,65 @@
       </variablelist>
     </refsect2>
 
+    <refsect2>
+      <title>udevadm cat
+      <optional><replaceable>options</replaceable></optional>
+      <optional><replaceable>file</replaceable></optional>
+      …
+      </title>
+
+      <para>Show udev rules files or udev.conf.</para>
+
+      <para>Positional arguments can be used to specify one or more files to show. Each argument must be an
+      absolute path to a udev rules file or a directory that contains rules files, or a file name of udev
+      rules file (e.g. <filename>99-systemd.rules</filename>). If a file name is specified, the file will be
+      searched in the <filename>udev/rules.d</filename> directories that are processed by
+      <command>systemd-udevd</command>, and searched in the current working directory if not found. If no
+      files are specified, the udev rules are read from the files located in the same
+      <filename>udev/rules.d</filename> directories that are processed by <command>systemd-udevd</command>.
+      See <citerefentry><refentrytitle>udev</refentrytitle><manvolnum>7</manvolnum></citerefentry> for more
+      details about the search paths.</para>
+
+      <variablelist>
+        <varlistentry>
+          <term><option>--root=<replaceable>PATH</replaceable></option></term>
+          <listitem>
+            <para>When looking for udev rules files located in the <filename>udev/rules.d</filename>
+            directories, operate on files underneath the specified root path <replaceable>PATH</replaceable>.
+            When a file name is specified, and it is not found in the <filename>udev/rules.d</filename>
+            directories, the file will be searched in the specified root path
+            <replaceable>PATH</replaceable>, rather than the current working directory.</para>
+
+            <xi:include href="version-info.xml" xpointer="v258"/>
+          </listitem>
+        </varlistentry>
+
+        <varlistentry>
+          <term><option>--tldr</option></term>
+          <listitem>
+            <para>Only print the "interesting" parts of the configuration files, skipping comments and empty
+            lines and section headers followed only by comments and empty lines.</para>
+
+            <xi:include href="version-info.xml" xpointer="v258"/>
+          </listitem>
+        </varlistentry>
+
+        <varlistentry>
+          <term><option>--config</option></term>
+          <listitem>
+            <para>Shows
+            <citerefentry><refentrytitle>udev.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+            files, rather than udev rules files. When specified, no udev rules file cannot be specified.
+            </para>
+
+            <xi:include href="version-info.xml" xpointer="v258"/>
+          </listitem>
+        </varlistentry>
+
+        <xi:include href="standard-options.xml" xpointer="help" />
+      </variablelist>
+    </refsect2>
+
     <refsect2>
       <title>udevadm wait
       <optional><replaceable>options</replaceable></optional>

diff --git a/shell-completion/bash/udevadm b/shell-completion/bash/udevadm
index bc8dc5515bcd02f5f5eb0d671dbfd5e0ee46e804..02a025ff451ccb6676498ebc657b1323c02c70ad 100644 (file)
--- a/shell-completion/bash/udevadm
+++ b/shell-completion/bash/udevadm
@@ -103,11 +103,13 @@ _udevadm() {
         [TEST_BUILTIN]='-a --action'
         [VERIFY_STANDALONE]='--no-summary --no-style'
         [VERIFY_ARG]='-N --resolve-names --root'
+        [CAT_STANDALONE]='--tldr --config'
+        [CAT_ARG]='--root'
         [WAIT]='-t --timeout --initialized=no --removed --settle'
         [LOCK]='-t --timeout -d --device -b --backing -p --print'
     )
 
-    local verbs=(info trigger settle control monitor test-builtin test verify wait lock)
+    local verbs=(info trigger settle control monitor test-builtin test verify cat wait lock)
     local builtins=(blkid btrfs hwdb input_id keyboard kmod net_driver net_id net_setup_link path_id uaccess usb_id)
 
     for ((i=0; i < COMP_CWORD; i++)); do
@@ -323,6 +325,30 @@ _udevadm() {
             fi
             ;;
 
+        'cat')
+            if __contains_word "$prev" ${OPTS[CAT_ARG]}; then
+                case $prev in
+                    --root)
+                        comps=''
+                        compopt -o dirnames
+                        ;;
+                    *)
+                        comps=''
+                        ;;
+                esac
+            elif [[ $cur = -* ]]; then
+                comps="${OPTS[COMMON]} ${OPTS[CAT_ARG]} ${OPTS[CAT_STANDALONE]}"
+            elif __contains_word "--config" ${COMP_WORDS[*]}; then
+                comps="${OPTS[COMMON]} ${OPTS[CAT_ARG]} ${OPTS[CAT_STANDALONE]}"
+            elif [[ $cur = */* ]]; then
+                comps=$( __get_udev_rules_files )
+                compopt -o dirnames
+            else
+                comps=$( __get_udev_rules_names )
+                compopt -o default
+            fi
+            ;;
+
         'wait')
             if __contains_word "$prev" ${OPTS[WAIT]}; then
                 case $prev in

diff --git a/shell-completion/zsh/_udevadm b/shell-completion/zsh/_udevadm
index 6c8478da75fc4e8f65471be20329a2a9b3c155bd..7572b09f67fc277a7b3eb155f2d718388be677ae 100644 (file)
--- a/shell-completion/zsh/_udevadm
+++ b/shell-completion/zsh/_udevadm
@@ -126,6 +126,17 @@ _udevadm_verify(){
         '*::files:_files'
 }
 
+(( $+functions[_udevadm_cat] )) ||
+_udevadm_cat(){
+    _arguments \
+        '(- *)'{-h,--help}'[Show help]' \
+        '(- *)'{-V,--version}'[Show package version]' \
+        '--root=[Operate on catalog hierarchy under specified directory]:directories:_directories' \
+        --tldr'[Skip comments and empty lines.]' \
+        --config'[Show udev.conf.]' \
+        '*::files:_files'
+}
+
 (( $+functions[_udevadm_wait] )) ||
 _udevadm_wait(){
     _arguments \

diff --git a/src/udev/meson.build b/src/udev/meson.build
index 8b40e02a8b8300080838c39fd6f256e553f36b0c..697d1081419bc80c9cc560c47f036e12f2bceb67 100644 (file)
--- a/src/udev/meson.build
+++ b/src/udev/meson.build
@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: LGPL-2.1-or-later
 
 udevadm_sources = files(
+        'udevadm-cat.c',
         'udevadm-control.c',
         'udevadm-hwdb.c',
         'udevadm-info.c',

diff --git a/src/udev/udevadm-cat.c b/src/udev/udevadm-cat.c
new file mode 100644 (file)
index 0000000..2d7e869
--- /dev/null
+++ b/src/udev/udevadm-cat.c
@@ -0,0 +1,110 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include <getopt.h>
+
+#include "log.h"
+#include "parse-argument.h"
+#include "pretty-print.h"
+#include "static-destruct.h"
+#include "strv.h"
+#include "udevadm.h"
+#include "udevadm-util.h"
+
+static char *arg_root = NULL;
+static CatFlags arg_cat_flags = 0;
+static bool arg_config = false;
+
+STATIC_DESTRUCTOR_REGISTER(arg_root, freep);
+
+static int help(void) {
+        _cleanup_free_ char *link = NULL;
+        int r;
+
+        r = terminal_urlify_man("udevadm", "8", &link);
+        if (r < 0)
+                return log_oom();
+
+        printf("%s cat [OPTIONS] [FILE...]\n"
+               "\n%sShow udev rules files.%s\n\n"
+               "  -h --help            Show this help\n"
+               "  -V --version         Show package version\n"
+               "     --root=PATH       Operate on an alternate filesystem root\n"
+               "     --tldr            Skip comments and empty lines\n"
+               "     --config          Show udev.conf rather than udev rules files\n"
+               "\nSee the %s for details.\n",
+               program_invocation_short_name,
+               ansi_highlight(),
+               ansi_normal(),
+               link);
+
+        return 0;
+}
+
+static int parse_argv(int argc, char *argv[]) {
+        enum {
+                ARG_ROOT = 0x100,
+                ARG_TLDR,
+                ARG_CONFIG,
+        };
+        static const struct option options[] = {
+                { "help",          no_argument,       NULL, 'h'             },
+                { "version",       no_argument,       NULL, 'V'             },
+                { "root",          required_argument, NULL, ARG_ROOT        },
+                { "tldr",          no_argument,       NULL, ARG_TLDR        },
+                { "config",        no_argument,       NULL, ARG_CONFIG      },
+                {}
+        };
+
+        int r, c;
+
+        assert(argc >= 0);
+        assert(argv);
+
+        while ((c = getopt_long(argc, argv, "hVN:", options, NULL)) >= 0)
+                switch (c) {
+                case 'h':
+                        return help();
+                case 'V':
+                        return print_version();
+                case ARG_ROOT:
+                        r = parse_path_argument(optarg, /* suppress_root= */ true, &arg_root);
+                        if (r < 0)
+                                return r;
+                        break;
+                case ARG_TLDR:
+                        arg_cat_flags = CAT_TLDR;
+                        break;
+                case ARG_CONFIG:
+                        arg_config = true;
+                        break;
+                case '?':
+                        return -EINVAL;
+                default:
+                        assert_not_reached();
+                }
+
+        if (arg_config && optind < argc)
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+                                       "Combination of --config and FILEs is not supported.");
+
+        return 1;
+}
+
+int cat_main(int argc, char *argv[], void *userdata) {
+        int r;
+
+        r = parse_argv(argc, argv);
+        if (r <= 0)
+                return r;
+
+        if (arg_config)
+                return conf_files_cat(arg_root, "udev/udev.conf", arg_cat_flags);
+
+        _cleanup_strv_free_ char **files = NULL;
+        r = search_rules_files(strv_skip(argv, optind), arg_root, &files);
+        if (r < 0)
+                return r;
+
+        /* udev rules file does not support dropin configs. So, we can safely pass multiple files as dropins. */
+        return cat_files(/* file = */ NULL, /* dropins = */ files, arg_cat_flags);
+}

diff --git a/src/udev/udevadm.c b/src/udev/udevadm.c
index 30b6ddb7282ff178bc0c5d5fe8f3d26afe4e74f8..ebf1e5190ccb7fa476eab2790a72d6baf12a6d5a 100644 (file)
--- a/src/udev/udevadm.c
+++ b/src/udev/udevadm.c
@@ -26,6 +26,7 @@ static int help(void) {
                 { "test",         "Test an event run"                 },
                 { "test-builtin", "Test a built-in command"           },
                 { "verify",       "Verify udev rules files"           },
+                { "cat",          "Show udev rules files"             },
                 { "wait",         "Wait for device or device symlink" },
                 { "lock",         "Lock a block device"               },
         };
@@ -97,6 +98,7 @@ static int help_main(int argc, char *argv[], void *userdata) {
 
 static int udevadm_main(int argc, char *argv[]) {
         static const Verb verbs[] = {
+                { "cat",          VERB_ANY, VERB_ANY, 0, cat_main     },
                 { "info",         VERB_ANY, VERB_ANY, 0, info_main    },
                 { "trigger",      VERB_ANY, VERB_ANY, 0, trigger_main },
                 { "settle",       VERB_ANY, VERB_ANY, 0, settle_main  },

diff --git a/src/udev/udevadm.h b/src/udev/udevadm.h
index 7920a70d5b1812788f460f75cf958543e7ca2b67..e39dbf655d474a9a360ac0a92d4ffc3af3982b8a 100644 (file)
--- a/src/udev/udevadm.h
+++ b/src/udev/udevadm.h
@@ -5,6 +5,7 @@
 
 #include "macro.h"
 
+int cat_main(int argc, char *argv[], void *userdata);
 int info_main(int argc, char *argv[], void *userdata);
 int trigger_main(int argc, char *argv[], void *userdata);
 int settle_main(int argc, char *argv[], void *userdata);

diff --git a/test/units/TEST-17-UDEV.10.sh b/test/units/TEST-17-UDEV.10.sh
index 8643e9e6bb48a44705143a930a6a4df68d58160b..b8f5648a47348f39c38ece1dda8fa5cf1f054ed7 100755 (executable)
--- a/test/units/TEST-17-UDEV.10.sh
+++ b/test/units/TEST-17-UDEV.10.sh
@@ -33,6 +33,15 @@ udevadm settle --timeout 30
 
 udevadm -h
 
+udevadm cat
+udevadm cat 99-systemd
+udevadm cat 99-systemd.rules
+udevadm cat /usr/lib/udev/rules.d/99-systemd.rules
+udevadm cat /usr/lib/udev/rules.d
+(! udevadm cat /dev/null)
+udevadm cat --config
+udevadm cat -h
+
 INVOCATION_ID=$(systemctl show --property InvocationID --value systemd-udevd.service)
 udevadm control -e
 # Wait for systemd-udevd.service being restarted.