id128: allow combining --app with show

This effectively exposes sd_id128_get_app_specific() on the commandline.

Fixes https://github.com/systemd/systemd/issues/27514.

src/id128/id128.c

@@ -68,8 +68,16 @@ static int verb_invocation_id(int argc, char **argv, void *userdata) {
 }
 
 static int show_one(Table **table, const char *name, sd_id128_t uuid, bool first) {
+        sd_id128_t u;
         int r;
 
+        assert(table);
+
+        if (sd_id128_is_null(arg_app))
+                u = uuid;
+        else
+                assert_se(sd_id128_get_app_specific(uuid, arg_app, &u) == 0);
+
         if (arg_mode == ID128_PRINT_PRETTY) {
                 _cleanup_free_ char *id = NULL;
 
@@ -79,7 +87,7 @@ static int show_one(Table **table, const char *name, sd_id128_t uuid, bool first
 
                 ascii_strupper(id);
 
-                r = id128_pretty_print_sample(id, uuid);
+                r = id128_pretty_print_sample(id, u);
                 if (r < 0)
                         return r;
                 if (!first)
@@ -87,7 +95,7 @@ static int show_one(Table **table, const char *name, sd_id128_t uuid, bool first
                 return 0;
 
         } else if (arg_value)
-                return id128_pretty_print(uuid, arg_mode);
+                return id128_pretty_print(u, arg_mode);
 
         else {
                 if (!*table) {
@@ -100,7 +108,7 @@ static int show_one(Table **table, const char *name, sd_id128_t uuid, bool first
                 return table_add_many(*table,
                                       TABLE_STRING, name,
                                       arg_mode == ID128_PRINT_ID128 ? TABLE_ID128 : TABLE_UUID,
-                                      uuid);
+                                      u);
         }
 }
 

src/test/test-id128.c

@@ -180,6 +180,7 @@ TEST(id128) {
         assert_se(lseek(fd, 0, SEEK_SET) == 0);
         assert_se(id128_read_fd(fd, ID128_FORMAT_ANY, NULL) == -EUCLEAN);
 
+        /* build/systemd-id128 -a f03daaeb1c334b43a732172944bf772e show 51df0b4bc3b04c9780e299b98ca373b8 */
         assert_se(sd_id128_get_app_specific(SD_ID128_MAKE(51,df,0b,4b,c3,b0,4c,97,80,e2,99,b9,8c,a3,73,b8),
                                             SD_ID128_MAKE(f0,3d,aa,eb,1c,33,4b,43,a7,32,17,29,44,bf,77,2e), &id) >= 0);
         assert_se(sd_id128_equal(id, SD_ID128_MAKE(1d,ee,59,54,e7,5c,4d,6f,b9,6c,c6,c0,4c,a1,8a,86)));