Replace max_expr_depth parameter with a max_stack_depth parameter that

is measured in kilobytes and checked against actual physical execution
stack depth, as per my proposal of 30-Dec.  This gives us a fairly
bulletproof defense against crashing due to runaway recursive functions.

1 files changed, 3 insertions, 33 deletions

diff --git a/src/backend/parser/parse_expr.c b/src/backend/parser/parse_expr.c
index 3881cc39538..83daae9b62b 100644
--- a/src/backend/parser/parse_expr.c
+++ b/src/backend/parser/parse_expr.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/parse_expr.c,v 1.166 2004/03/17 20:48:42 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/parse_expr.c,v 1.167 2004/03/24 22:40:29 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -35,9 +35,6 @@
 #include "utils/syscache.h"
 
 
-int			max_expr_depth = DEFAULT_MAX_EXPR_DEPTH;
-static int	expr_depth_counter = 0;
-
 bool		Transform_null_equals = false;
 
 static Node *typecast_expression(ParseState *pstate, Node *expr,
@@ -48,19 +45,6 @@ static Node *transformIndirection(ParseState *pstate, Node *basenode,
 
 
 /*
- * Initialize for parsing a new query.
- *
- * We reset the expression depth counter here, in case it was left nonzero
- * due to ereport()'ing out of the last parsing operation.
- */
-void
-parse_expr_init(void)
-{
-	expr_depth_counter = 0;
-}
-
-
-/*
  * transformExpr -
  *	  Analyze and transform expressions. Type checking and type casting is
  *	  done here. The optimizer and the executor cannot handle the original
@@ -92,20 +76,8 @@ transformExpr(ParseState *pstate, Node *expr)
 	if (expr == NULL)
 		return NULL;
 
-	/*
-	 * Guard against an overly complex expression leading to coredump due
-	 * to stack overflow here, or in later recursive routines that
-	 * traverse expression trees.  Note that this is very unlikely to
-	 * happen except with pathological queries; but we don't want someone
-	 * to be able to crash the backend quite that easily...
-	 */
-	if (++expr_depth_counter > max_expr_depth)
-		ereport(ERROR,
-				(errcode(ERRCODE_STATEMENT_TOO_COMPLEX),
-				 errmsg("expression too complex"),
-				 errdetail("Nesting depth exceeds maximum expression depth %d.",
-						   max_expr_depth),
-				 errhint("Increase the configuration parameter \"max_expr_depth\".")));
+	/* Guard against stack overflow due to overly complex expressions */
+	check_stack_depth();
 
 	switch (nodeTag(expr))
 	{
@@ -938,8 +910,6 @@ transformExpr(ParseState *pstate, Node *expr)
 			break;
 	}
 
-	expr_depth_counter--;
-
 	return result;
 }