Merge pull request #15448 from keszybz/logind-avoid-polkit-query

logind: avoid polkit query for SetWallMessage()

src/login/loginctl.c

@@ -825,7 +825,15 @@ static int show_properties(sd_bus *bus, const char *path, bool *new_line) {
 
         *new_line = true;
 
-        r = bus_print_all_properties(bus, "org.freedesktop.login1", path, print_property, arg_property, arg_value, arg_all, NULL);
+        r = bus_print_all_properties(
+                        bus,
+                        "org.freedesktop.login1",
+                        path,
+                        print_property,
+                        arg_property,
+                        arg_value,
+                        arg_all,
+                        NULL);
         if (r < 0)
                 return bus_log_parse_error(r);
 
@@ -1347,7 +1355,6 @@ static int help(int argc, char *argv[], void *userdata) {
 }
 
 static int parse_argv(int argc, char *argv[]) {
-
         enum {
                 ARG_VERSION = 0x100,
                 ARG_VALUE,
@@ -1486,7 +1493,6 @@ static int parse_argv(int argc, char *argv[]) {
 }
 
 static int loginctl_main(int argc, char *argv[], sd_bus *bus) {
-
         static const Verb verbs[] = {
                 { "help",              VERB_ANY, VERB_ANY, 0,            help              },
                 { "list-sessions",     VERB_ANY, 1,        VERB_DEFAULT, list_sessions     },

src/login/logind-dbus.c

@@ -3170,6 +3170,12 @@ static int method_set_wall_message(
         if (r < 0)
                 return r;
 
+        /* Short-circuit the operation if the desired state is already in place, to
+         * avoid an unnecessary polkit permission check. */
+        if (streq_ptr(m->wall_message, empty_to_null(wall_message)) &&
+            m->enable_wall_messages == enable_wall_messages)
+                goto done;
+
         r = bus_verify_polkit_async(message,
                                     CAP_SYS_ADMIN,
                                     "org.freedesktop.login1.set-wall-message",
@@ -3189,6 +3195,7 @@ static int method_set_wall_message(
 
         m->enable_wall_messages = enable_wall_messages;
 
+ done:
         return sd_bus_reply_method_return(message, NULL);
 }