From 41d28499a28249549d8f589370348479ff7232af Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sat, 18 Jun 2005 20:51:59 +0000
Subject: [PATCH] When using C-string lookup keys in a dynahash.c hash table,
 use strncpy() not memcpy() to copy the offered key into the hash table during
 HASH_ENTER. This avoids possible core dump if the passed key is located very
 near the end of memory.  Per report from Stefan Kaltenbrunner.

---
 src/backend/utils/hash/dynahash.c | 12 ++++++++++--
 src/include/utils/hsearch.h       |  4 +++-
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/src/backend/utils/hash/dynahash.c b/src/backend/utils/hash/dynahash.c
index c6f9b023697..ef92103b64a 100644
--- a/src/backend/utils/hash/dynahash.c
+++ b/src/backend/utils/hash/dynahash.c
@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/hash/dynahash.c,v 1.48 2003/08/19 01:13:41 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/hash/dynahash.c,v 1.48.2.1 2005/06/18 20:51:59 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -144,6 +144,14 @@ hash_create(const char *tabname, long nelem, HASHCTL *info, int flags)
 	else
 		hashp->match = memcmp;
 
+	/*
+	 * Similarly, the key-copying function defaults to strncpy() or memcpy().
+	 */
+	if (hashp->hash == string_hash)
+		hashp->keycopy = (HashCopyFunc) strncpy;
+	else
+		hashp->keycopy = memcpy;
+
 	if (flags & HASH_SHARED_MEM)
 	{
 		/*
@@ -644,7 +652,7 @@ hash_search(HTAB *hashp,
 
 			/* copy key into record */
 			currBucket->hashvalue = hashvalue;
-			memcpy(ELEMENTKEY(currBucket), keyPtr, hctl->keysize);
+			hashp->keycopy(ELEMENTKEY(currBucket), keyPtr, hctl->keysize);
 
 			/* caller is expected to fill the data field on return */
 
diff --git a/src/include/utils/hsearch.h b/src/include/utils/hsearch.h
index 05d26e9a150..d6f43163811 100644
--- a/src/include/utils/hsearch.h
+++ b/src/include/utils/hsearch.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: hsearch.h,v 1.29 2003/08/19 01:13:41 tgl Exp $
+ * $Id: hsearch.h,v 1.29.2.1 2005/06/18 20:51:59 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -24,6 +24,7 @@
 typedef uint32 (*HashValueFunc) (const void *key, Size keysize);
 typedef int (*HashCompareFunc) (const void *key1, const void *key2,
 								Size keysize);
+typedef void *(*HashCopyFunc) (void *dest, const void *src, Size keysize);
 
 /*
  * Space allocation function for a hashtable --- designed to match malloc().
@@ -108,6 +109,7 @@ typedef struct HTAB
 								 * used */
 	char	   *tabname;		/* table name (for error messages) */
 	bool		isshared;		/* true if table is in shared memory */
+	HashCopyFunc keycopy;		/* key copying function */
 } HTAB;
 
 /* Parameter data structure for hash_create */