Fix core dump due to null-pointer dereference in to_char() when datetime

format codes are misapplied to a numeric argument.  (The code still produces
a pretty bogus error message in such cases, but I'll settle for stopping the
crash for now.)  Per bug #4700 from Sergey Burladyan.

Problem exists in all supported branches, so patch all the way back.
In HEAD, also clean up some ugly coding in the nearby cache management
code.

diff --git a/src/backend/utils/adt/formatting.c b/src/backend/utils/adt/formatting.c
index 0e7c9ddff4213da7ec9ce1ba7c5a78addb01be2d..5af4788d0f2efe004636006690977017105e3de4 100644 (file)
--- a/src/backend/utils/adt/formatting.c
+++ b/src/backend/utils/adt/formatting.c
@@ -1,7 +1,7 @@
 /* -----------------------------------------------------------------------
  * formatting.c
  *
- * $PostgreSQL: pgsql/src/backend/utils/adt/formatting.c,v 1.116.2.3 2007/06/29 01:51:49 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/adt/formatting.c,v 1.116.2.4 2009/03/12 00:53:41 tgl Exp $
  *
  *
  *      Portions Copyright (c) 1999-2006, PostgreSQL Global Development Group
@@ -356,7 +356,7 @@ static int  DCHCounter = 0;
 
 /* global cache for --- number part */
 static NUMCacheEntry NUMCache[NUM_CACHE_FIELDS + 1];
-static NUMCacheEntry *last_NUMCacheEntry;
+static NUMCacheEntry *last_NUMCacheEntry = NUMCache + 0;
 
 static int     n_NUMCache = 0;         /* number of entries */
 static int     NUMCounter = 0;