systemctl: add command set-log-level

Command changes current log level

src/systemctl/systemctl.c

@@ -4462,6 +4462,51 @@ finish:
         return r;
 }
 
+static int set_log_level(DBusConnection *bus, char **args) {
+        _cleanup_dbus_error_free_ DBusError error;
+        _cleanup_dbus_message_unref_ DBusMessage *m = NULL, *reply = NULL;
+        DBusMessageIter iter, sub;
+        const char* property = "LogLevel";
+        const char* interface = "org.freedesktop.systemd1.Manager";
+        const char* value;
+
+        assert(bus);
+        assert(args);
+
+        value = args[1];
+        dbus_error_init(&error);
+
+        m = dbus_message_new_method_call("org.freedesktop.systemd1",
+                                         "/org/freedesktop/systemd1",
+                                         "org.freedesktop.DBus.Properties",
+                                         "Set");
+        if (!m)
+                return log_oom();
+
+        dbus_message_iter_init_append(m, &iter);
+
+        if (!dbus_message_iter_append_basic(&iter, DBUS_TYPE_STRING, &interface) ||
+            !dbus_message_iter_append_basic(&iter, DBUS_TYPE_STRING, &property) ||
+            !dbus_message_iter_open_container(&iter, DBUS_TYPE_VARIANT, "s", &sub))
+                return log_oom();
+
+        if (!dbus_message_iter_append_basic(&sub, DBUS_TYPE_STRING, &value)) {
+                dbus_message_iter_abandon_container(&iter, &sub);
+                return log_oom();
+        }
+
+        if (!dbus_message_iter_close_container(&iter, &sub))
+                return log_oom();
+
+        reply = dbus_connection_send_with_reply_and_block(bus, m, -1, &error);
+        if (!reply) {
+                log_error("Failed to issue method call: %s", bus_error_message(&error));
+                return -EIO;
+        }
+
+        return 0;
+}
+
 static int unit_is_enabled(DBusConnection *bus, char **args) {
         _cleanup_dbus_error_free_ DBusError error;
         int r;
@@ -5707,6 +5752,7 @@ static int systemctl_main(DBusConnection *bus, int argc, char *argv[], DBusError
                 { "list-dependencies",     LESS,  2, list_dependencies },
                 { "set-default",           EQUAL, 2, enable_unit       },
                 { "get-default",           LESS,  1, get_default       },
+                { "set-log-level",         EQUAL, 2, set_log_level     },
         };
 
         int left;