Logsys: Ensure logging PID is really corosync

When serivce plugin calls fork and child uses logsys, it may lead to
corrupted fdata (idx is updated but it's not shared between child and
parent, but fdata is mmaped file and this is shared).

Solutions is to:
- Store corosync pid
- On log, check if current pid == corosync pid
- If so -> store in fdata, if not -> don't store

Signed-off-by: Jan Friesse <jfriesse@redhat.com>
Reviewed-by: Fabio M. Di Nitto <fdinitto@redhat.com>

exec/logsys.c

@@ -205,6 +205,8 @@ static int logsys_dropped_messages = 0;
 
 void *logsys_rec_end;
 
+static pid_t startup_pid = 0;
+
 static DECLARE_LIST_INIT(logsys_print_finished_records);
 
 #define FDMAX_ARGS	64
@@ -1242,16 +1244,20 @@ void _logsys_log_vprintf (
 		short_file_name++; /* move past the "/" */
 #endif /* BUILDING_IN_PLACE */
 
-	/*
-	 * Create a log record
-	 */
-	_logsys_log_rec (
-		rec_ident,
-		function_name,
-		short_file_name,
-		file_line,
-		logsys_print_buffer, len + 1,
-		LOGSYS_REC_END);
+	if (startup_pid == 0 || startup_pid == getpid()) {
+		/*
+		 * Create a log record if we are really true corosync
+		 * process (not fork of some service) or if we didn't finished
+		 * initialization yet.
+		 */
+		_logsys_log_rec (
+			rec_ident,
+			function_name,
+			short_file_name,
+			file_line,
+			logsys_print_buffer, len + 1,
+			LOGSYS_REC_END);
+	}
 
 	/*
 	 * If logsys is not going to print a message to a log target don't
@@ -1324,6 +1330,8 @@ int _logsys_config_subsys_get (const char *subsys)
 void logsys_fork_completed (void)
 {
 	logsys_loggers[LOGSYS_MAX_SUBSYS_COUNT].mode &= ~LOGSYS_MODE_FORK;
+	startup_pid = getpid();
+
 	(void)_logsys_wthread_create ();
 }