When allocating memory, zero out them if we don't intend to overwrite them

all; before freeing memory, zero out them before we release it as free
heap.  This will eliminate some potential information leak issue.

While there, remove the PURIFY option.  There is a slight difference between
the new behavior and the old -DPURIFY behavior, with the latter initializes
memory with 0xff's.  The difference between old and new approach does not
generate observable difference.

Obtained from:	OpenBSD (partly).

lib/libc/db/README

@@ -1,4 +1,5 @@
 #	@(#)README	8.27 (Berkeley) 9/1/94
+# $FreeBSD$
 
 This is version 1.85 of the Berkeley DB code.
 
@@ -31,10 +32,3 @@ mpool		The memory pool routines.
 recno		The fixed/variable length record routines.
 test		Test package.
 
-============================================
-Debugging:
-
-If you're running a memory checker (e.g. Purify) on DB, make sure that
-you recompile it with "-DPURIFY" in the CFLAGS, first.  By default,
-allocated pages are not initialized by the DB code, and they will show
-up as reads of uninitialized memory in the buffer write routines.

lib/libc/db/btree/bt_open.c

@@ -156,9 +156,8 @@ __bt_open(const char *fname, int flags, int mode, const BTREEINFO *openinfo, int
 		goto einval;
 
 	/* Allocate and initialize DB and BTREE structures. */
-	if ((t = (BTREE *)malloc(sizeof(BTREE))) == NULL)
+	if ((t = (BTREE *)calloc(1, sizeof(BTREE))) == NULL)
 		goto err;
-	memset(t, 0, sizeof(BTREE));
 	t->bt_fd = -1;			/* Don't close unopened fd on error. */
 	t->bt_lorder = b.lorder;
 	t->bt_order = NOT;
@@ -166,9 +165,8 @@ __bt_open(const char *fname, int flags, int mode, const BTREEINFO *openinfo, int
 	t->bt_pfx = b.prefix;
 	t->bt_rfd = -1;
 
-	if ((t->bt_dbp = dbp = (DB *)malloc(sizeof(DB))) == NULL)
+	if ((t->bt_dbp = dbp = (DB *)calloc(1, sizeof(DB))) == NULL)
 		goto err;
-	memset(t->bt_dbp, 0, sizeof(DB));
 	if (t->bt_lorder != machine_lorder)
 		F_SET(t, B_NEEDSWAP);
 

lib/libc/db/btree/bt_split.c

@@ -372,13 +372,10 @@ bt_page(BTREE *t, PAGE *h, PAGE **lp, PAGE **rp, indx_t *skip, size_t ilen)
 	}
 
 	/* Put the new left page for the split into place. */
-	if ((l = (PAGE *)malloc(t->bt_psize)) == NULL) {
+	if ((l = (PAGE *)calloc(1, t->bt_psize)) == NULL) {
 		mpool_put(t->bt_mp, r, 0);
 		return (NULL);
 	}
-#ifdef PURIFY
-	memset(l, 0xff, t->bt_psize);
-#endif
 	l->pgno = h->pgno;
 	l->nextpg = r->pgno;
 	l->prevpg = h->prevpg;

lib/libc/db/hash/hash_buf.c

@@ -57,6 +57,7 @@ __FBSDID("$FreeBSD$");
 #include <stddef.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 
 #ifdef DEBUG
 #include <assert.h>
@@ -169,18 +170,12 @@ newbuf(HTAB *hashp, u_int32_t addr, BUFHEAD *prev_bp)
 	 */
 	if (hashp->nbufs || (bp->flags & BUF_PIN)) {
 		/* Allocate a new one */
-		if ((bp = (BUFHEAD *)malloc(sizeof(BUFHEAD))) == NULL)
+		if ((bp = (BUFHEAD *)calloc(1, sizeof(BUFHEAD))) == NULL)
 			return (NULL);
-#ifdef PURIFY
-		memset(bp, 0xff, sizeof(BUFHEAD));
-#endif
-		if ((bp->page = (char *)malloc(hashp->BSIZE)) == NULL) {
+		if ((bp->page = (char *)calloc(1, hashp->BSIZE)) == NULL) {
 			free(bp);
 			return (NULL);
 		}
-#ifdef PURIFY
-		memset(bp->page, 0xff, hashp->BSIZE);
-#endif
 		if (hashp->nbufs)
 			hashp->nbufs--;
 	} else {
@@ -319,8 +314,10 @@ __buf_free(HTAB *hashp, int do_free, int to_disk)
 		}
 		/* Check if we are freeing stuff */
 		if (do_free) {
-			if (bp->page)
+			if (bp->page) {
+				(void)memset(bp->page, 0, hashp->BSIZE);
 				free(bp->page);
+			}
 			BUF_REMOVE(bp);
 			free(bp);
 			bp = LRU;

lib/libc/db/mpool/mpool.c

@@ -332,13 +332,10 @@ mpool_bkt(MPOOL *mp)
 			return (bp);
 		}
 
-new:	if ((bp = (BKT *)malloc(sizeof(BKT) + mp->pagesize)) == NULL)
+new:	if ((bp = (BKT *)calloc(1, sizeof(BKT) + mp->pagesize)) == NULL)
 		return (NULL);
 #ifdef STATISTICS
 	++mp->pagealloc;
-#endif
-#if defined(DEBUG) || defined(PURIFY)
-	memset(bp, 0xff, sizeof(BKT) + mp->pagesize);
 #endif
 	bp->page = (char *)bp + sizeof(BKT);
 	++mp->curcache;