udevadm: Propagate return code from verb result

udevadm lock did not propagate the return code from the child process
because all positive values were treated as success.

v2:
Now 'udevadm test-builtin' ignores all positive return values from the
builtin commands. Otherwise, as the hwdb builtin returns an positive value
when a matching entry found, 'udevadm test-builtin hwdb' will fail.

v3:
Initialize partition table before calling 'sfdisk --delete'.

Co-authored-by: Yu Watanabe <watanabe.yu+github@gmail.com>

src/udev/udevadm-test-builtin.c

@@ -104,9 +104,12 @@ int builtin_main(int argc, char *argv[], void *userdata) {
         }
 
         r = udev_builtin_run(event, cmd, arg_command, true);
-        if (r < 0)
+        if (r < 0) {
                 log_debug_errno(r, "Builtin command '%s' fails: %m", arg_command);
+                goto finish;
+        }
 
+        r = 0;
 finish:
         udev_builtin_exit();
         return r;

src/udev/udevadm.c

@@ -137,4 +137,4 @@ static int run(int argc, char *argv[]) {
         return udevadm_main(argc, argv);
 }
 
-DEFINE_MAIN_FUNCTION(run);
+DEFINE_MAIN_FUNCTION_WITH_POSITIVE_FAILURE(run);