From 88c556680ca3faa40f7428c7705455d744a9859e Mon Sep 17 00:00:00 2001
From: Alvaro Herrera
Date: Fri, 2 Aug 2013 12:49:03 -0400
Subject: Fix crash in error report of invalid tuple lock

My tweak of these error messages in commit c359a1b082 contained the
thinko that a query would always have rowMarks set for a query
containing a locking clause.  Not so: when declaring a cursor, for
instance, rowMarks isn't set at the point we're checking, so we'd be
dereferencing a NULL pointer.

The fix is to pass the lock strength to the function raising the error,
instead of trying to reverse-engineer it.  The result not only is more
robust, but it also seems cleaner overall.

Per report from Robert Haas.
---
 src/backend/optimizer/plan/planner.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

(limited to 'src/backend/optimizer')

diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 9ff8050080f..49bd9302fa5 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -1962,7 +1962,8 @@ preprocess_rowmarks(PlannerInfo *root)
 		 * CTIDs invalid.  This is also checked at parse time, but that's
 		 * insufficient because of rule substitution, query pullup, etc.
 		 */
-		CheckSelectLocking(parse);
+		CheckSelectLocking(parse, ((RowMarkClause *)
+							linitial(parse->rowMarks))->strength);
 	}
 	else
 	{
-- 
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