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 13208526297fe6f3b7ff034412f5a6f149243a7c..3d6d611b07140062362b7b042a840f0384993f5f 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 1.84.4.3 2007/06/29 01:52:04 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/adt/formatting.c,v 1.84.4.4 2009/03/12 00:53:56 tgl Exp $
  *
  *
  *      Portions Copyright (c) 1999-2005, PostgreSQL Global Development Group
@@ -349,7 +349,7 @@ 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;