set output string pointer to NULL after freeing it

1 files changed, 6 insertions, 3 deletions

diff --git a/gpib.c b/gpib.c
index 7711e25..6210b79 100644
--- a/gpib.c
+++ b/gpib.c
@@ -635,8 +635,9 @@ int GPIB_check_for_device_clear_signal(void)
 
 		TNT_4882_Status(STB,0x10,CLEAR);        // Clear MAV bit
 		g_free (globals.Registers.pending_output_message);
+		globals.Registers.pending_output_message = NULL;
 
-                TNT_Holdoff_off();
+		TNT_Holdoff_off();
 		TNT_INT_STATUS();
 
 		return TRUE;
@@ -788,6 +789,7 @@ void GPIB_start_query_response(gpointer *ignore_this, char *in_string)
 	if (globals.Registers.pending_output_message != NULL) {
 		queue_error_for_gpib_only(query_error_interrupted);
 		g_free (globals.Registers.pending_output_message);
+		globals.Registers.pending_output_message = NULL;
 	}
 
 	globals.Registers.pending_output_message = g_strdup_printf ("%s\n", in_string);
@@ -798,8 +800,8 @@ void GPIB_start_query_response(gpointer *ignore_this, char *in_string)
 void GPIB_finish_query_response()
 {
 	if (!globals.HWDetect.gpib) {
-                return;
-        }
+		return;
+	}
 
 	if (globals.Registers.pending_output_message == NULL) {
 		return;
@@ -888,6 +890,7 @@ void GPIB_finish_query_response()
 		INTERFACE_STATUS|=UCMPL;			// Set the user complete bit
 
 		g_free (globals.Registers.pending_output_message);
+		globals.Registers.pending_output_message = NULL;
 
 		if (GPIB_check_for_device_clear_signal()) {
 			return;