handle truncation in vsnprintf and reduce size of char time_buffer[] …

…to 20

20 is sufficient

src/datum_logger.c

@@ -118,7 +118,7 @@ int datum_logger_queue_msg(const char *func, int level, const char *format, ...)
 	va_list args;
 	struct timeval tv;
 	struct tm tm_info;
-	char time_buffer[40];
+	char time_buffer[20];
 
 	if ((level < log_level_console) && (level < log_level_file)) {
 		return 0;
@@ -201,8 +201,13 @@ int datum_logger_queue_msg(const char *func, int level, const char *format, ...)
 	msg->calling_function[47] = 0;
 	msg->msg = &msg_buffer[buffer_id][msg_buf_idx[buffer_id]];
 	va_start(args, format);
-	i = vsnprintf(msg->msg, sizeof(msg->msg), format, args);
-	msg->msg[i] = 0;
+	i = vsnprintf(msg->msg, 1023, format, args);
+
+	// clamp i to actual written value in order not to waste buffer space
+	if (i >= 1023) {
+		i = 1022;
+	}
+
 	va_end(args);
 
 	if (((msg_buf_idx[buffer_id]+i+2) > msg_buf_maxsz) || (dlog_queue_next[buffer_id] >= dlog_queue_max_entries)) {
@@ -251,7 +256,7 @@ void * datum_logger_thread(void *ptr) {
 	struct tm tm_info_storage;
 	struct tm *tm_info;
 	DLOG_MSG *msg;
-	char time_buffer[40];
+	char time_buffer[20];
 	char log_line[1200];
 	FILE *log_handle = NULL;
 	time_t next_log_rotate = get_midnight_timestamp();