Loggers specify what log messages they want to receive during registration.

This also allows us to generate the log message only once for all
loggers that need it (avoids calls to custom printf specifier callbacks).

To update the log levels loggers can simply be registered again.

src/libcharon/plugins/stroke/stroke_control.c

@@ -58,11 +58,11 @@ struct stroke_log_info_t {
  * logging to the stroke interface
  */
 static bool stroke_log(stroke_log_info_t *info, debug_t group, level_t level,
-					   ike_sa_t *ike_sa, char *format, va_list args)
+					   ike_sa_t *ike_sa, char *message)
 {
 	if (level <= info->level)
 	{
-		if (vfprintf(info->out, format, args) < 0 ||
+		if (fprintf(info->out, message) < 0 ||
 			fprintf(info->out, "\n") < 0 ||
 			fflush(info->out) != 0)
 		{

src/libcharon/plugins/stroke/stroke_socket.c

@@ -517,12 +517,14 @@ static void stroke_loglevel(private_stroke_socket_t *this,
 	while (enumerator->enumerate(enumerator, &sys_logger))
 	{
 		sys_logger->set_level(sys_logger, group, msg->loglevel.level);
+		charon->bus->add_logger(charon->bus, &sys_logger->logger);
 	}
 	enumerator->destroy(enumerator);
 	enumerator = charon->file_loggers->create_enumerator(charon->file_loggers);
 	while (enumerator->enumerate(enumerator, &file_logger))
 	{
 		file_logger->set_level(file_logger, group, msg->loglevel.level);
+		charon->bus->add_logger(charon->bus, &file_logger->logger);
 	}
 	enumerator->destroy(enumerator);
 }