Merge pull request #19736 from poettering/udev-trigger-uuid

sd-device: add support for triggering devices with UUID support

man/sd_id128_get_machine.xml

@@ -99,12 +99,16 @@
     <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> for details. The
     ID is cached internally. In future a different mechanism to determine the invocation ID may be added.</para>
 
-    <para>Note that <function>sd_id128_get_machine_app_specific()</function>, <function>sd_id128_get_boot()</function>,
+    <para>Note that <function>sd_id128_get_machine_app_specific()</function>,
-    <function>sd_id128_get_boot_app_specific()</function>, and <function>sd_id128_get_invocation()</function> always
+    <function>sd_id128_get_boot()</function>, <function>sd_id128_get_boot_app_specific()</function>, and
-    return UUID v4 compatible IDs.  <function>sd_id128_get_machine()</function> will also return a UUID v4-compatible
+    <function>sd_id128_get_invocation()</function> always return UUID v4 compatible IDs.
-    ID on new installations but might not on older. It is possible to convert the machine ID into a UUID v4-compatible
+    <function>sd_id128_get_machine()</function> will also return a UUID v4-compatible ID on new installations
-    one. For more information, see
+    but might not on older. It is possible to convert the machine ID into a UUID v4-compatible one. For more
-    <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
+    information, see
+    <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>. It is
+    hence guaranteed that thes functions will never return the ID consisting of all zero or all one bits
+    (<constant>SD_ID128_NULL</constant>, <constant>SD_ID128_ALLF</constant>) — with the possible exception of
+    <function>sd_id128_get_machine()</function>, as mentioned.</para>
 
     <para>For more information about the <literal>sd_id128_t</literal>
     type see

man/sd_id128_randomize.xml

@@ -42,8 +42,9 @@
     <filename>/dev/urandom</filename> kernel random number
     generator.</para>
 
-    <para>Note that <function>sd_id128_randomize()</function> always
+    <para>Note that <function>sd_id128_randomize()</function> always returns a UUID v4-compatible ID. It is
-    returns a UUID v4-compatible ID.</para>
+    hence guaranteed that this function will never return the ID consisting of all zero or all one bits
+    (<constant>SD_ID128_NULL</constant>, <constant>SD_ID128_ALLF</constant>).</para>
 
     <para>For more information about the <literal>sd_id128_t</literal>
     type, see

man/udevadm.xml

@@ -375,6 +375,15 @@
             the same command to finish.</para>
           </listitem>
         </varlistentry>
+        <varlistentry>
+          <term><option>--uuid</option></term>
+          <listitem>
+            <para>Trigger the synthetic device events, and associate a randomized UUID with each. These UUIDs
+            are printed to standard output, one line for each event. These UUIDs are included in the uevent
+            environment block (in the <literal>SYNTH_UUID=</literal> property) and may be used to track
+            delivery of the generated events.</para>
+          </listitem>
+        </varlistentry>
         <varlistentry>
           <term><option>--wait-daemon[=<replaceable>SECONDS</replaceable>]</option></term>
           <listitem>

src/basic/hash-funcs.c

@@ -14,7 +14,7 @@ DEFINE_HASH_OPS_WITH_KEY_DESTRUCTOR(string_hash_ops_free,
                                     char, string_hash_func, string_compare_func, free);
 DEFINE_HASH_OPS_FULL(string_hash_ops_free_free,
                      char, string_hash_func, string_compare_func, free,
-                     char, free);
+                     void, free);
 
 void path_hash_func(const char *q, struct siphash *state) {
         size_t n;
@@ -57,6 +57,9 @@ void path_hash_func(const char *q, struct siphash *state) {
 DEFINE_HASH_OPS(path_hash_ops, char, path_hash_func, path_compare);
 DEFINE_HASH_OPS_WITH_KEY_DESTRUCTOR(path_hash_ops_free,
                                     char, path_hash_func, path_compare, free);
+DEFINE_HASH_OPS_FULL(path_hash_ops_free_free,
+                     char, path_hash_func, path_compare, free,
+                     void, free);
 
 void trivial_hash_func(const void *p, struct siphash *state) {
         siphash24_compress(&p, sizeof(p), state);

src/basic/hash-funcs.h

@@ -82,6 +82,7 @@ extern const struct hash_ops string_hash_ops_free_free;
 void path_hash_func(const char *p, struct siphash *state);
 extern const struct hash_ops path_hash_ops;
 extern const struct hash_ops path_hash_ops_free;
+extern const struct hash_ops path_hash_ops_free_free;
 
 /* This will compare the passed pointers directly, and will not dereference them. This is hence not useful for strings
  * or suchlike. */

src/libsystemd/libsystemd.sym

@@ -757,4 +757,6 @@ global:
         sd_device_monitor_filter_add_match_sysattr;
         sd_device_monitor_filter_add_match_parent;
         sd_device_get_usec_initialized;
+        sd_device_trigger_with_uuid;
+        sd_device_get_trigger_uuid;
 } LIBSYSTEMD_248;

src/libsystemd/sd-device/sd-device.c

@@ -16,6 +16,7 @@
 #include "fileio.h"
 #include "fs-util.h"
 #include "hashmap.h"
+#include "id128-util.h"
 #include "macro.h"
 #include "parse-util.h"
 #include "path-util.h"
@@ -1869,6 +1870,34 @@ _public_ int sd_device_get_property_value(sd_device *device, const char *key, co
         return 0;
 }
 
+_public_ int sd_device_get_trigger_uuid(sd_device *device, sd_id128_t *ret) {
+        const char *s;
+        sd_id128_t id;
+        int r;
+
+        assert_return(device, -EINVAL);
+
+        /* Retrieves the UUID attached to a uevent when triggering it from userspace via
+         * sd_device_trigger_with_uuid() or an equivalent interface. Returns -ENOENT if the record is not
+         * caused by a synthetic event and -ENODATA if it was but no UUID was specified */
+
+        r = sd_device_get_property_value(device, "SYNTH_UUID", &s);
+        if (r < 0)
+                return r;
+
+        if (streq(s, "0")) /* SYNTH_UUID=0 is set whenever a device is triggered by userspace without specifying a UUID */
+                return -ENODATA;
+
+        r = sd_id128_from_string(s, &id);
+        if (r < 0)
+                return r;
+
+        if (ret)
+                *ret = id;
+
+        return 0;
+}
+
 static int device_cache_sysattr_value(sd_device *device, const char *key, char *value) {
         _cleanup_free_ char *new_key = NULL, *old_value = NULL;
         int r;
@@ -2096,5 +2125,41 @@ _public_ int sd_device_trigger(sd_device *device, sd_device_action_t action) {
         if (!s)
                 return -EINVAL;
 
+        /* This uses the simple no-UUID interface of kernel < 4.13 */
         return sd_device_set_sysattr_value(device, "uevent", s);
 }
+
+_public_ int sd_device_trigger_with_uuid(
+                sd_device *device,
+                sd_device_action_t action,
+                sd_id128_t *ret_uuid) {
+
+        char buf[ID128_UUID_STRING_MAX];
+        const char *s, *j;
+        sd_id128_t u;
+        int r;
+
+        assert_return(device, -EINVAL);
+
+        /* If noone wants to know the UUID, use the simple interface from pre-4.13 times */
+        if (!ret_uuid)
+                return sd_device_trigger(device, action);
+
+        s = device_action_to_string(action);
+        if (!s)
+                return -EINVAL;
+
+        r = sd_id128_randomize(&u);
+        if (r < 0)
+                return r;
+
+        id128_to_uuid_string(u, buf);
+        j = strjoina(s, " ", buf);
+
+        r = sd_device_set_sysattr_value(device, "uevent", j);
+        if (r < 0)
+                return r;
+
+        *ret_uuid = u;
+        return 0;
+}

src/systemd/sd-device.h

@@ -24,6 +24,7 @@
 #include <sys/types.h>
 
 #include "sd-event.h"
+#include "sd-id128.h"
 
 #include "_sd-common.h"
 
@@ -96,11 +97,13 @@ const char *sd_device_get_sysattr_next(sd_device *device);
 int sd_device_has_tag(sd_device *device, const char *tag);
 int sd_device_has_current_tag(sd_device *device, const char *tag);
 int sd_device_get_property_value(sd_device *device, const char *key, const char **value);
+int sd_device_get_trigger_uuid(sd_device *device, sd_id128_t *ret);
 int sd_device_get_sysattr_value(sd_device *device, const char *sysattr, const char **_value);
 
 int sd_device_set_sysattr_value(sd_device *device, const char *sysattr, const char *value);
 int sd_device_set_sysattr_valuef(sd_device *device, const char *sysattr, const char *format, ...) _sd_printf_(3, 4);
 int sd_device_trigger(sd_device *device, sd_device_action_t action);
+int sd_device_trigger_with_uuid(sd_device *device, sd_device_action_t action, sd_id128_t *ret_uuid);
 
 /* device enumerator */
 

src/udev/udevadm-trigger.c

@@ -24,8 +24,14 @@
 static bool arg_verbose = false;
 static bool arg_dry_run = false;
 static bool arg_quiet = false;
+static bool arg_uuid = false;
 
-static int exec_list(sd_device_enumerator *e, sd_device_action_t action, Set **settle_set) {
+static int exec_list(
+                sd_device_enumerator *e,
+                sd_device_action_t action,
+                Hashmap *settle_hashmap) {
+
+        bool skip_uuid_logic = false;
         const char *action_str;
         sd_device *d;
         int r, ret = 0;
@@ -33,18 +39,33 @@ static int exec_list(sd_device_enumerator *e, sd_device_action_t action, Set **s
         action_str = device_action_to_string(action);
 
         FOREACH_DEVICE_AND_SUBSYSTEM(e, d) {
+                sd_id128_t id = SD_ID128_NULL;
                 const char *syspath;
 
-                if (sd_device_get_syspath(d, &syspath) < 0)
+                r = sd_device_get_syspath(d, &syspath);
+                if (r < 0) {
+                        log_debug_errno(r, "Failed to get syspath of enumerated devices, ignoring: %m");
                         continue;
+                }
 
                 if (arg_verbose)
-                        printf("%s\n", strna(syspath));
+                        printf("%s\n", syspath);
 
                 if (arg_dry_run)
                         continue;
 
-                r = sd_device_trigger(d, action);
+                /* Use the UUID mode if the user explicitly asked for it, or if --settle has been specified,
+                 * so that we can recognize our own uevent. */
+                r = sd_device_trigger_with_uuid(d, action, (arg_uuid || settle_hashmap) && !skip_uuid_logic ? &id : NULL);
+                if (r == -EINVAL && !arg_uuid && settle_hashmap && !skip_uuid_logic) {
+                        /* If we specified a UUID because of the settling logic, and we got EINVAL this might
+                         * be caused by an old kernel which doesn't know the UUID logic (pre-4.13). Let's try
+                         * if it works without the UUID logic then. */
+                        r = sd_device_trigger(d, action);
+                        if (r != -EINVAL)
+                                skip_uuid_logic = true; /* dropping the uuid stuff changed the return code,
+                                                         * hence don't bother next time */
+                }
                 if (r < 0) {
                         /* ENOENT may be returned when a device does not have /uevent or is already
                          * removed. Hence, this is logged at debug level and ignored.
@@ -86,10 +107,28 @@ static int exec_list(sd_device_enumerator *e, sd_device_action_t action, Set **s
                         continue;
                 }
 
-                if (settle_set) {
+                /* If the user asked for it, write event UUID to stdout */
-                        r = set_put_strdup(settle_set, syspath);
+                if (arg_uuid)
+                        printf(SD_ID128_FORMAT_STR "\n", SD_ID128_FORMAT_VAL(id));
+
+                if (settle_hashmap) {
+                        _cleanup_free_ sd_id128_t *mid = NULL;
+                        _cleanup_free_ char *sp = NULL;
+
+                        sp = strdup(syspath);
+                        if (!sp)
+                                return log_oom();
+
+                        mid = newdup(sd_id128_t, &id, 1);
+                        if (!d)
+                                return log_oom();
+
+                        r = hashmap_put(settle_hashmap, sp, mid);
                         if (r < 0)
                                 return log_oom();
+
+                        TAKE_PTR(sp);
+                        TAKE_PTR(mid);
                 }
         }
 
@@ -97,24 +136,51 @@ static int exec_list(sd_device_enumerator *e, sd_device_action_t action, Set **s
 }
 
 static int device_monitor_handler(sd_device_monitor *m, sd_device *dev, void *userdata) {
-        _cleanup_free_ char *val = NULL;
+        Hashmap *settle_hashmap = userdata;
-        Set *settle_set = userdata;
+        sd_id128_t *settle_id;
         const char *syspath;
+        char *k;
+        int r;
 
         assert(dev);
-        assert(settle_set);
+        assert(settle_hashmap);
 
-        if (sd_device_get_syspath(dev, &syspath) < 0)
+        r = sd_device_get_syspath(dev, &syspath);
+        if (r < 0) {
+                log_debug_errno(r, "Failed to get syspath of device event, ignoring: %m");
                 return 0;
+        }
+
+        settle_id = hashmap_get2(settle_hashmap, syspath, (void**) &k);
+        if (!settle_id) {
+                log_debug("Got uevent for unexpected device '%s', ignoring.", syspath);
+                return 0;
+        }
+        if (!sd_id128_is_null(*settle_id)) { /* If this is SD_ID128_NULL then we are on pre-4.13 and have no UUID to check, hence don't */
+                sd_id128_t event_id;
+
+                r = sd_device_get_trigger_uuid(dev, &event_id);
+                if (r < 0) {
+                        log_debug_errno(r, "Got uevent without synthetic UUID for device '%s', ignoring: %m", syspath);
+                        return 0;
+                }
+
+                if (!sd_id128_equal(event_id, *settle_id)) {
+                        log_debug("Got uevent not matching expected UUID for device '%s', ignoring.", syspath);
+                        return 0;
+                }
+        }
 
         if (arg_verbose)
                 printf("settle %s\n", syspath);
 
-        val = set_remove(settle_set, syspath);
+        if (arg_uuid)
-        if (!val)
+                printf("settle " SD_ID128_FORMAT_STR "\n", SD_ID128_FORMAT_VAL(*settle_id));
-                log_debug("Got epoll event on syspath %s not present in syspath set", syspath);
 
-        if (set_isempty(settle_set))
+        free(hashmap_remove(settle_hashmap, syspath));
+        free(k);
+
+        if (hashmap_isempty(settle_hashmap))
                 return sd_event_exit(sd_device_monitor_get_event(m), 0);
 
         return 0;
@@ -162,7 +228,8 @@ static int help(void) {
                "  -b --parent-match=NAME            Trigger devices with that parent device\n"
                "  -w --settle                       Wait for the triggered events to complete\n"
                "     --wait-daemon[=SECONDS]        Wait for udevd daemon to be initialized\n"
-               "                                    before triggering uevents\n",
+               "                                    before triggering uevents\n"
+               "     --uuid                         Print synthetic uevent UUID\n",
                program_invocation_short_name);
 
         return 0;
@@ -172,6 +239,7 @@ int trigger_main(int argc, char *argv[], void *userdata) {
         enum {
                 ARG_NAME = 0x100,
                 ARG_PING,
+                ARG_UUID,
         };
 
         static const struct option options[] = {
@@ -193,6 +261,7 @@ int trigger_main(int argc, char *argv[], void *userdata) {
                 { "wait-daemon",       optional_argument, NULL, ARG_PING },
                 { "version",           no_argument,       NULL, 'V'      },
                 { "help",              no_argument,       NULL, 'h'      },
+                { "uuid",              no_argument,       NULL, ARG_UUID },
                 {}
         };
         enum {
@@ -203,7 +272,7 @@ int trigger_main(int argc, char *argv[], void *userdata) {
         _cleanup_(sd_device_enumerator_unrefp) sd_device_enumerator *e = NULL;
         _cleanup_(sd_device_monitor_unrefp) sd_device_monitor *m = NULL;
         _cleanup_(sd_event_unrefp) sd_event *event = NULL;
-        _cleanup_set_free_ Set *settle_set = NULL;
+        _cleanup_hashmap_free_ Hashmap *settle_hashmap = NULL;
         usec_t ping_timeout_usec = 5 * USEC_PER_SEC;
         bool settle = false, ping = false;
         int c, r;
@@ -327,7 +396,7 @@ int trigger_main(int argc, char *argv[], void *userdata) {
                         break;
                 }
 
-                case ARG_PING: {
+                case ARG_PING:
                         ping = true;
                         if (optarg) {
                                 r = parse_sec(optarg, &ping_timeout_usec);
@@ -335,7 +404,10 @@ int trigger_main(int argc, char *argv[], void *userdata) {
                                         log_error_errno(r, "Failed to parse timeout value '%s', ignoring: %m", optarg);
                         }
                         break;
-                }
+
+                case ARG_UUID:
+                        arg_uuid = true;
+                        break;
 
                 case 'V':
                         return print_version();
@@ -377,8 +449,8 @@ int trigger_main(int argc, char *argv[], void *userdata) {
         }
 
         if (settle) {
-                settle_set = set_new(&string_hash_ops_free);
+                settle_hashmap = hashmap_new(&path_hash_ops_free_free);
-                if (!settle_set)
+                if (!settle_hashmap)
                         return log_oom();
 
                 r = sd_event_default(&event);
@@ -393,7 +465,7 @@ int trigger_main(int argc, char *argv[], void *userdata) {
                 if (r < 0)
                         return log_error_errno(r, "Failed to attach event to device monitor: %m");
 
-                r = sd_device_monitor_start(m, device_monitor_handler, settle_set);
+                r = sd_device_monitor_start(m, device_monitor_handler, settle_hashmap);
                 if (r < 0)
                         return log_error_errno(r, "Failed to start device monitor: %m");
         }
@@ -413,11 +485,11 @@ int trigger_main(int argc, char *argv[], void *userdata) {
                 assert_not_reached("Unknown device type");
         }
 
-        r = exec_list(e, action, settle ? &settle_set : NULL);
+        r = exec_list(e, action, settle_hashmap);
         if (r < 0)
                 return r;
 
-        if (event && !set_isempty(settle_set)) {
+        if (event && !hashmap_isempty(settle_hashmap)) {
                 r = sd_event_loop(event);
                 if (r < 0)
                         return log_error_errno(r, "Event loop failed: %m");