--- /dev/null
+++ Libc/Libc-320/db/btree/bt_stack.c
@@ -0,0 +1,113 @@
+/*
+ * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
+ *
+ * @APPLE_LICENSE_HEADER_START@
+ * 
+ * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
+ * 
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this
+ * file.
+ * 
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ * 
+ * @APPLE_LICENSE_HEADER_END@
+ */
+/*
+ * Copyright (c) 1990, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Mike Olson.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by the University of
+ *	California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+
+#include <sys/types.h>
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <db.h>
+#include "btree.h"
+
+/*
+ * When a page splits, a new record has to be inserted into its parent page.
+ * This page may have to split as well, all the way up to the root.  Since
+ * parent pointers in each page would be expensive, we maintain a stack of
+ * parent pages as we descend the tree.
+ *
+ * XXX
+ * This is a concurrency problem -- if user a builds a stack, then user b
+ * splits the tree, then user a tries to split the tree, there's a new level
+ * in the tree that user a doesn't know about.
+ */
+
+/*
+ * __BT_PUSH -- Push parent page info onto the stack (LIFO).
+ *
+ * Parameters:
+ *	t:	tree
+ *	pgno:	page
+ *	index:	page index
+ *
+ * Returns:
+ * 	RET_ERROR, RET_SUCCESS
+ */
+int
+__bt_push(t, pgno, index)
+	BTREE *t;
+	pgno_t pgno;
+	indx_t index;
+{
+	if (t->bt_sp == t->bt_maxstack) {
+		t->bt_maxstack += 50;
+		if ((t->bt_stack = (EPGNO *)realloc(t->bt_stack,
+		    t->bt_maxstack * sizeof(EPGNO))) == NULL) {
+			t->bt_maxstack -= 50;
+			return (RET_ERROR);
+		}
+	}
+
+	t->bt_stack[t->bt_sp].pgno = pgno;
+	t->bt_stack[t->bt_sp].index = index;
+	++t->bt_sp;
+	return (RET_SUCCESS);
+}