From eb83fca4b703f89d0727eb0b52110775bb602c79 Mon Sep 17 00:00:00 2001
From: Liang Chang <l-chang@users.sourceforge.net>
Date: Sat, 20 Feb 2021 01:35:13 +0800
Subject: [PATCH] ttsnoop: check the return value from tt_message_op to avoid a
 segmentation fault.

---
 cde/programs/ttsnoop/DtTt.C | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/cde/programs/ttsnoop/DtTt.C b/cde/programs/ttsnoop/DtTt.C
index ffd208fa9..8569cabf1 100644
--- a/cde/programs/ttsnoop/DtTt.C
+++ b/cde/programs/ttsnoop/DtTt.C
@@ -559,7 +559,7 @@ _DtTtChoices(
 			std::ostringstream itemStream;
 			itemStream << (void *)dtTtMessages[ i ];
 			char *op = tt_message_op( dtTtMessages[ i ] );
-			if (! tt_is_err( tt_ptr_error( op ))) {
+			if (op && ! tt_is_err( tt_ptr_error( op ))) {
 				itemStream << " " << op;
 				tt_free( op );
 			}