Avoid possible instantiation of Prolog data in the trace interception

smucclaw · Dec 4, 2023 · ada966b · ada966b
1 parent e763cfd
commit ada966b
Showing 1 changed file with 8 additions and 4 deletions.
diff --git a/lib/trace.pl b/lib/trace.pl
@@ -95,10 +95,14 @@
 
 user:prolog_trace_interception(Port, Frame, CHP, Action) :-
 	trace_pengines,
-	catch(trace_interception(Port, Frame, CHP, Action), E, true),
-	(   var(E)
-	->  true
-	;   abort			% tracer ignores non-abort exceptions.
+	State = state(0),
+	(   catch(trace_interception(Port, Frame, CHP, Action), E, true),
+	    (   var(E)
+	    ->  nb_setarg(1, State, Action)
+	    ;   abort			% tracer ignores non-abort exceptions.
+	    ),
+	    fail
+	;   arg(1, State, Action)
 	).
 
 trace_interception(Port, Frame, _CHP, Action) :-