userdb: add support for looking up users or groups by uuid.

This propagates the UUID lookup parameter through the API permitting
lookups to be done by uuid.

src/shared/user-record.c

@@ -2777,7 +2777,8 @@ bool userdb_match_is_set(const UserDBMatch *match) {
         return !strv_isempty(match->fuzzy_names) ||
                 !FLAGS_SET(match->disposition_mask, USER_DISPOSITION_MASK_ALL) ||
                 match->uid_min > 0 ||
-                match->uid_max < UID_INVALID-1;
+                match->uid_max < UID_INVALID-1 ||
+                !sd_id128_is_null(match->uuid);
 }
 
 void userdb_match_done(UserDBMatch *match) {
@@ -2836,6 +2837,9 @@ bool user_record_match(UserRecord *u, const UserDBMatch *match) {
         if (!BIT_SET(match->disposition_mask, user_record_disposition(u)))
                 return false;
 
+        if (!sd_id128_is_null(match->uuid) && !sd_id128_equal(match->uuid, u->uuid))
+                return false;
+
         if (!strv_isempty(match->fuzzy_names)) {
 
                 /* Note this array of names is sparse, i.e. various entries listed in it will be

src/shared/user-record.h

@@ -513,6 +513,7 @@ typedef struct UserDBMatch {
                 uid_t uid_max;
                 gid_t gid_max;
         };
+        sd_id128_t uuid;
 } UserDBMatch;
 
 #define USER_DISPOSITION_MASK_ALL ((UINT64_C(1) << _USER_DISPOSITION_MAX) - UINT64_C(1))
@@ -522,6 +523,7 @@ typedef struct UserDBMatch {
                 .disposition_mask = USER_DISPOSITION_MASK_ALL,  \
                 .uid_min = 0,                                   \
                 .uid_max = UID_INVALID-1,                       \
+                .uuid = SD_ID128_NULL,                          \
        }
 
 /* Maybe useful when we want to resolve root and system user/group but want to refuse nobody user/group. */

src/shared/userdb.c

@@ -799,27 +799,29 @@ nomatch:
         return 0;
 }
 
-static int query_append_disposition_mask(sd_json_variant **query, uint64_t mask) {
+static int query_append_common(sd_json_variant **query, const UserDBMatch *match) {
         int r;
+        _cleanup_strv_free_ char **dispositions = NULL;
 
         assert(query);
 
-        if (FLAGS_SET(mask, USER_DISPOSITION_MASK_ALL))
-                return 0;
+        uint64_t mask = match->disposition_mask;
+        if (FLAGS_SET(mask, USER_DISPOSITION_MASK_ALL)) {
+                for (UserDisposition d = 0; d < _USER_DISPOSITION_MAX; d++) {
+                        if (!BIT_SET(mask, d))
+                                continue;
 
-        _cleanup_strv_free_ char **dispositions = NULL;
-        for (UserDisposition d = 0; d < _USER_DISPOSITION_MAX; d++) {
-                if (!BITS_SET(mask, d))
-                        continue;
-
-                r = strv_extend(&dispositions, user_disposition_to_string(d));
-                if (r < 0)
-                        return r;
+                        r = strv_extend(&dispositions, user_disposition_to_string(d));
+                        if (r < 0)
+                                return r;
+                }
         }
 
         return sd_json_variant_merge_objectbo(
                         query,
-                        SD_JSON_BUILD_PAIR_STRV("dispositionMask", dispositions));
+                        SD_JSON_BUILD_PAIR_CONDITION(!strv_isempty(match->fuzzy_names), "fuzzyNames", SD_JSON_BUILD_STRV(match->fuzzy_names)),
+                        SD_JSON_BUILD_PAIR_CONDITION(!sd_id128_is_null(match->uuid), "uuid", SD_JSON_BUILD_UUID(match->uuid)),
+                        SD_JSON_BUILD_PAIR_CONDITION(!strv_isempty(dispositions), "dispositionMask", SD_JSON_BUILD_STRV(dispositions)));
 }
 
 static int query_append_uid_match(sd_json_variant **query, const UserDBMatch *match) {
@@ -832,13 +834,12 @@ static int query_append_uid_match(sd_json_variant **query, const UserDBMatch *ma
 
         r = sd_json_variant_merge_objectbo(
                         query,
-                        SD_JSON_BUILD_PAIR_CONDITION(!strv_isempty(match->fuzzy_names), "fuzzyNames", SD_JSON_BUILD_STRV(match->fuzzy_names)),
                         SD_JSON_BUILD_PAIR_CONDITION(match->uid_min > 0, "uidMin", SD_JSON_BUILD_UNSIGNED(match->uid_min)),
                         SD_JSON_BUILD_PAIR_CONDITION(match->uid_max < UID_INVALID-1, "uidMax", SD_JSON_BUILD_UNSIGNED(match->uid_max)));
         if (r < 0)
                 return r;
 
-        return query_append_disposition_mask(query, match->disposition_mask);
+        return query_append_common(query, match);
 }
 
 static int userdb_by_name_fallbacks(
@@ -1298,13 +1299,13 @@ static int query_append_gid_match(sd_json_variant **query, const UserDBMatch *ma
 
         r = sd_json_variant_merge_objectbo(
                         query,
-                        SD_JSON_BUILD_PAIR_CONDITION(!strv_isempty(match->fuzzy_names), "fuzzyNames", SD_JSON_BUILD_STRV(match->fuzzy_names)),
                         SD_JSON_BUILD_PAIR_CONDITION(match->gid_min > 0, "gidMin", SD_JSON_BUILD_UNSIGNED(match->gid_min)),
                         SD_JSON_BUILD_PAIR_CONDITION(match->gid_max < GID_INVALID-1, "gidMax", SD_JSON_BUILD_UNSIGNED(match->gid_max)));
+
         if (r < 0)
                 return r;
 
-        return query_append_disposition_mask(query, match->disposition_mask);
+        return query_append_common(query, match);
 }
 
 static int groupdb_by_name_fallbacks(