Back-patch addition of stack overflow and interrupt checks for lquery.

tglsfdc · tglsfdc · commit 94c9152dc880 · 2020-03-31T11:37:44.000-04:00
Experimentation shows that it's not hard at all to drive the old implementation of "ltree ~ lquery" match to stack overflow, so throw in a check_stack_depth() call, as I just did in HEAD. I wasn't able to make it take a long time, because all the pathological cases I tried hit stack overflow first; but I bet there are some others that do take a long time, so add CHECK_FOR_INTERRUPTS() too. Discussion: https://postgr.es/m/CAP_rww=waX2Oo6q+MbMSiZ9ktdj6eaJj0cQzNu=Ry2cCDij5fw@mail.gmail.com
diff --git a/contrib/ltree/lquery_op.c b/contrib/ltree/lquery_op.c
@@ -8,6 +8,7 @@
 #include <ctype.h>
 
 #include "catalog/pg_collation.h"
+#include "miscadmin.h"
 #include "utils/formatting.h"
 #include "ltree.h"
 
@@ -165,6 +166,12 @@ checkCond(lquery_level *curq, int query_numlevel, ltree_level *curt, int tree_nu
 	lquery_level *prevq = NULL;
 	ltree_level *prevt = NULL;
 
+	/* Since this function recurses, it could be driven to stack overflow */
+	check_stack_depth();
+
+	/* Pathological patterns could take awhile, too */
+	CHECK_FOR_INTERRUPTS();
+
 	if (SomeStack.muse)
 	{
 		high_pos = SomeStack.high_pos;
