* hurd/hurd/signal.h (struct hurd_sigstate): New member `preempters'. cvs/libc-960102

	(hurd_preempt_signals, hurd_unpreempt_signals): Decls removed.
	* hurd/hurd/sigpreempt.h: New file.
	* hurd/preempt-sig.c: Rewritten with new interface.
	* sysdeps/mach/hurd/jmp-unwind.c (_longjmp_unwind): Remove local signal
	preempters being unwound past.

	* db: New directory, 4.4 BSD db package incorporated from BSD db-1.85
	release.

	* sysdeps/unix/sysv/linux/sys/param.h: Several new macros for BSD
	compatibility.

1 files changed, 827 insertions, 0 deletions

diff --git a/db/btree/bt_split.c b/db/btree/bt_split.c
new file mode 100644
index 0000000000..1646d82159
--- /dev/null
+++ b/db/btree/bt_split.c
@@ -0,0 +1,827 @@
+/*-
+ * Copyright (c) 1990, 1993, 1994
+ *	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.
+ */
+
+#if defined(LIBC_SCCS) && !defined(lint)
+static char sccsid[] = "@(#)bt_split.c	8.9 (Berkeley) 7/26/94";
+#endif /* LIBC_SCCS and not lint */
+
+#include <sys/types.h>
+
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <db.h>
+#include "btree.h"
+
+static int	 bt_broot __P((BTREE *, PAGE *, PAGE *, PAGE *));
+static PAGE	*bt_page
+		    __P((BTREE *, PAGE *, PAGE **, PAGE **, indx_t *, size_t));
+static int	 bt_preserve __P((BTREE *, pgno_t));
+static PAGE	*bt_psplit
+		    __P((BTREE *, PAGE *, PAGE *, PAGE *, indx_t *, size_t));
+static PAGE	*bt_root
+		    __P((BTREE *, PAGE *, PAGE **, PAGE **, indx_t *, size_t));
+static int	 bt_rroot __P((BTREE *, PAGE *, PAGE *, PAGE *));
+static recno_t	 rec_total __P((PAGE *));
+
+#ifdef STATISTICS
+u_long	bt_rootsplit, bt_split, bt_sortsplit, bt_pfxsaved;
+#endif
+
+/*
+ * __BT_SPLIT -- Split the tree.
+ *
+ * Parameters:
+ *	t:	tree
+ *	sp:	page to split
+ *	key:	key to insert
+ *	data:	data to insert
+ *	flags:	BIGKEY/BIGDATA flags
+ *	ilen:	insert length
+ *	skip:	index to leave open
+ *
+ * Returns:
+ *	RET_ERROR, RET_SUCCESS
+ */
+int
+__bt_split(t, sp, key, data, flags, ilen, argskip)
+	BTREE *t;
+	PAGE *sp;
+	const DBT *key, *data;
+	int flags;
+	size_t ilen;
+	u_int32_t argskip;
+{
+	BINTERNAL *bi;
+	BLEAF *bl, *tbl;
+	DBT a, b;
+	EPGNO *parent;
+	PAGE *h, *l, *r, *lchild, *rchild;
+	indx_t nxtindex;
+	u_int16_t skip;
+	u_int32_t n, nbytes, nksize;
+	int parentsplit;
+	char *dest;
+
+	/*
+	 * Split the page into two pages, l and r.  The split routines return
+	 * a pointer to the page into which the key should be inserted and with
+	 * skip set to the offset which should be used.  Additionally, l and r
+	 * are pinned.
+	 */
+	skip = argskip;
+	h = sp->pgno == P_ROOT ?
+	    bt_root(t, sp, &l, &r, &skip, ilen) :
+	    bt_page(t, sp, &l, &r, &skip, ilen);
+	if (h == NULL)
+		return (RET_ERROR);
+
+	/*
+	 * Insert the new key/data pair into the leaf page.  (Key inserts
+	 * always cause a leaf page to split first.)
+	 */
+	h->linp[skip] = h->upper -= ilen;
+	dest = (char *)h + h->upper;
+	if (F_ISSET(t, R_RECNO))
+		WR_RLEAF(dest, data, flags)
+	else
+		WR_BLEAF(dest, key, data, flags)
+
+	/* If the root page was split, make it look right. */
+	if (sp->pgno == P_ROOT &&
+	    (F_ISSET(t, R_RECNO) ?
+	    bt_rroot(t, sp, l, r) : bt_broot(t, sp, l, r)) == RET_ERROR)
+		goto err2;
+
+	/*
+	 * Now we walk the parent page stack -- a LIFO stack of the pages that
+	 * were traversed when we searched for the page that split.  Each stack
+	 * entry is a page number and a page index offset.  The offset is for
+	 * the page traversed on the search.  We've just split a page, so we
+	 * have to insert a new key into the parent page.
+	 *
+	 * If the insert into the parent page causes it to split, may have to
+	 * continue splitting all the way up the tree.  We stop if the root
+	 * splits or the page inserted into didn't have to split to hold the
+	 * new key.  Some algorithms replace the key for the old page as well
+	 * as the new page.  We don't, as there's no reason to believe that the
+	 * first key on the old page is any better than the key we have, and,
+	 * in the case of a key being placed at index 0 causing the split, the
+	 * key is unavailable.
+	 *
+	 * There are a maximum of 5 pages pinned at any time.  We keep the left
+	 * and right pages pinned while working on the parent.   The 5 are the
+	 * two children, left parent and right parent (when the parent splits)
+	 * and the root page or the overflow key page when calling bt_preserve.
+	 * This code must make sure that all pins are released other than the
+	 * root page or overflow page which is unlocked elsewhere.
+	 */
+	while ((parent = BT_POP(t)) != NULL) {
+		lchild = l;
+		rchild = r;
+
+		/* Get the parent page. */
+		if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
+			goto err2;
+
+	 	/*
+		 * The new key goes ONE AFTER the index, because the split
+		 * was to the right.
+		 */
+		skip = parent->index + 1;
+
+		/*
+		 * Calculate the space needed on the parent page.
+		 *
+		 * Prefix trees: space hack when inserting into BINTERNAL
+		 * pages.  Retain only what's needed to distinguish between
+		 * the new entry and the LAST entry on the page to its left.
+		 * If the keys compare equal, retain the entire key.  Note,
+		 * we don't touch overflow keys, and the entire key must be
+		 * retained for the next-to-left most key on the leftmost
+		 * page of each level, or the search will fail.  Applicable
+		 * ONLY to internal pages that have leaf pages as children.
+		 * Further reduction of the key between pairs of internal
+		 * pages loses too much information.
+		 */
+		switch (rchild->flags & P_TYPE) {
+		case P_BINTERNAL:
+			bi = GETBINTERNAL(rchild, 0);
+			nbytes = NBINTERNAL(bi->ksize);
+			break;
+		case P_BLEAF:
+			bl = GETBLEAF(rchild, 0);
+			nbytes = NBINTERNAL(bl->ksize);
+			if (t->bt_pfx && !(bl->flags & P_BIGKEY) &&
+			    (h->prevpg != P_INVALID || skip > 1)) {
+				tbl = GETBLEAF(lchild, NEXTINDEX(lchild) - 1);
+				a.size = tbl->ksize;
+				a.data = tbl->bytes;
+				b.size = bl->ksize;
+				b.data = bl->bytes;
+				nksize = t->bt_pfx(&a, &b);
+				n = NBINTERNAL(nksize);
+				if (n < nbytes) {
+#ifdef STATISTICS
+					bt_pfxsaved += nbytes - n;
+#endif
+					nbytes = n;
+				} else
+					nksize = 0;
+			} else
+				nksize = 0;
+			break;
+		case P_RINTERNAL:
+		case P_RLEAF:
+			nbytes = NRINTERNAL;
+			break;
+		default:
+			abort();
+		}
+
+		/* Split the parent page if necessary or shift the indices. */
+		if (h->upper - h->lower < nbytes + sizeof(indx_t)) {
+			sp = h;
+			h = h->pgno == P_ROOT ?
+			    bt_root(t, h, &l, &r, &skip, nbytes) :
+			    bt_page(t, h, &l, &r, &skip, nbytes);
+			if (h == NULL)
+				goto err1;
+			parentsplit = 1;
+		} else {
+			if (skip < (nxtindex = NEXTINDEX(h)))
+				memmove(h->linp + skip + 1, h->linp + skip,
+				    (nxtindex - skip) * sizeof(indx_t));
+			h->lower += sizeof(indx_t);
+			parentsplit = 0;
+		}
+
+		/* Insert the key into the parent page. */
+		switch (rchild->flags & P_TYPE) {
+		case P_BINTERNAL:
+			h->linp[skip] = h->upper -= nbytes;
+			dest = (char *)h + h->linp[skip];
+			memmove(dest, bi, nbytes);
+			((BINTERNAL *)dest)->pgno = rchild->pgno;
+			break;
+		case P_BLEAF:
+			h->linp[skip] = h->upper -= nbytes;
+			dest = (char *)h + h->linp[skip];
+			WR_BINTERNAL(dest, nksize ? nksize : bl->ksize,
+			    rchild->pgno, bl->flags & P_BIGKEY);
+			memmove(dest, bl->bytes, nksize ? nksize : bl->ksize);
+			if (bl->flags & P_BIGKEY &&
+			    bt_preserve(t, *(pgno_t *)bl->bytes) == RET_ERROR)
+				goto err1;
+			break;
+		case P_RINTERNAL:
+			/*
+			 * Update the left page count.  If split
+			 * added at index 0, fix the correct page.
+			 */
+			if (skip > 0)
+				dest = (char *)h + h->linp[skip - 1];
+			else
+				dest = (char *)l + l->linp[NEXTINDEX(l) - 1];
+			((RINTERNAL *)dest)->nrecs = rec_total(lchild);
+			((RINTERNAL *)dest)->pgno = lchild->pgno;
+
+			/* Update the right page count. */
+			h->linp[skip] = h->upper -= nbytes;
+			dest = (char *)h + h->linp[skip];
+			((RINTERNAL *)dest)->nrecs = rec_total(rchild);
+			((RINTERNAL *)dest)->pgno = rchild->pgno;
+			break;
+		case P_RLEAF:
+			/*
+			 * Update the left page count.  If split
+			 * added at index 0, fix the correct page.
+			 */
+			if (skip > 0)
+				dest = (char *)h + h->linp[skip - 1];
+			else
+				dest = (char *)l + l->linp[NEXTINDEX(l) - 1];
+			((RINTERNAL *)dest)->nrecs = NEXTINDEX(lchild);
+			((RINTERNAL *)dest)->pgno = lchild->pgno;
+
+			/* Update the right page count. */
+			h->linp[skip] = h->upper -= nbytes;
+			dest = (char *)h + h->linp[skip];
+			((RINTERNAL *)dest)->nrecs = NEXTINDEX(rchild);
+			((RINTERNAL *)dest)->pgno = rchild->pgno;
+			break;
+		default:
+			abort();
+		}
+
+		/* Unpin the held pages. */
+		if (!parentsplit) {
+			mpool_put(t->bt_mp, h, MPOOL_DIRTY);
+			break;
+		}
+
+		/* If the root page was split, make it look right. */
+		if (sp->pgno == P_ROOT &&
+		    (F_ISSET(t, R_RECNO) ?
+		    bt_rroot(t, sp, l, r) : bt_broot(t, sp, l, r)) == RET_ERROR)
+			goto err1;
+
+		mpool_put(t->bt_mp, lchild, MPOOL_DIRTY);
+		mpool_put(t->bt_mp, rchild, MPOOL_DIRTY);
+	}
+
+	/* Unpin the held pages. */
+	mpool_put(t->bt_mp, l, MPOOL_DIRTY);
+	mpool_put(t->bt_mp, r, MPOOL_DIRTY);
+
+	/* Clear any pages left on the stack. */
+	return (RET_SUCCESS);
+
+	/*
+	 * If something fails in the above loop we were already walking back
+	 * up the tree and the tree is now inconsistent.  Nothing much we can
+	 * do about it but release any memory we're holding.
+	 */
+err1:	mpool_put(t->bt_mp, lchild, MPOOL_DIRTY);
+	mpool_put(t->bt_mp, rchild, MPOOL_DIRTY);
+
+err2:	mpool_put(t->bt_mp, l, 0);
+	mpool_put(t->bt_mp, r, 0);
+	__dbpanic(t->bt_dbp);
+	return (RET_ERROR);
+}
+
+/*
+ * BT_PAGE -- Split a non-root page of a btree.
+ *
+ * Parameters:
+ *	t:	tree
+ *	h:	root page
+ *	lp:	pointer to left page pointer
+ *	rp:	pointer to right page pointer
+ *	skip:	pointer to index to leave open
+ *	ilen:	insert length
+ *
+ * Returns:
+ *	Pointer to page in which to insert or NULL on error.
+ */
+static PAGE *
+bt_page(t, h, lp, rp, skip, ilen)
+	BTREE *t;
+	PAGE *h, **lp, **rp;
+	indx_t *skip;
+	size_t ilen;
+{
+	PAGE *l, *r, *tp;
+	pgno_t npg;
+
+#ifdef STATISTICS
+	++bt_split;
+#endif
+	/* Put the new right page for the split into place. */
+	if ((r = __bt_new(t, &npg)) == NULL)
+		return (NULL);
+	r->pgno = npg;
+	r->lower = BTDATAOFF;
+	r->upper = t->bt_psize;
+	r->nextpg = h->nextpg;
+	r->prevpg = h->pgno;
+	r->flags = h->flags & P_TYPE;
+
+	/*
+	 * If we're splitting the last page on a level because we're appending
+	 * a key to it (skip is NEXTINDEX()), it's likely that the data is
+	 * sorted.  Adding an empty page on the side of the level is less work
+	 * and can push the fill factor much higher than normal.  If we're
+	 * wrong it's no big deal, we'll just do the split the right way next
+	 * time.  It may look like it's equally easy to do a similar hack for
+	 * reverse sorted data, that is, split the tree left, but it's not.
+	 * Don't even try.
+	 */
+	if (h->nextpg == P_INVALID && *skip == NEXTINDEX(h)) {
+#ifdef STATISTICS
+		++bt_sortsplit;
+#endif
+		h->nextpg = r->pgno;
+		r->lower = BTDATAOFF + sizeof(indx_t);
+		*skip = 0;
+		*lp = h;
+		*rp = r;
+		return (r);
+	}
+
+	/* Put the new left page for the split into place. */
+	if ((l = (PAGE *)malloc(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;
+	l->lower = BTDATAOFF;
+	l->upper = t->bt_psize;
+	l->flags = h->flags & P_TYPE;
+
+	/* Fix up the previous pointer of the page after the split page. */
+	if (h->nextpg != P_INVALID) {
+		if ((tp = mpool_get(t->bt_mp, h->nextpg, 0)) == NULL) {
+			free(l);
+			/* XXX mpool_free(t->bt_mp, r->pgno); */
+			return (NULL);
+		}
+		tp->prevpg = r->pgno;
+		mpool_put(t->bt_mp, tp, MPOOL_DIRTY);
+	}
+
+	/*
+	 * Split right.  The key/data pairs aren't sorted in the btree page so
+	 * it's simpler to copy the data from the split page onto two new pages
+	 * instead of copying half the data to the right page and compacting
+	 * the left page in place.  Since the left page can't change, we have
+	 * to swap the original and the allocated left page after the split.
+	 */
+	tp = bt_psplit(t, h, l, r, skip, ilen);
+
+	/* Move the new left page onto the old left page. */
+	memmove(h, l, t->bt_psize);
+	if (tp == l)
+		tp = h;
+	free(l);
+
+	*lp = h;
+	*rp = r;
+	return (tp);
+}
+
+/*
+ * BT_ROOT -- Split the root page of a btree.
+ *
+ * Parameters:
+ *	t:	tree
+ *	h:	root page
+ *	lp:	pointer to left page pointer
+ *	rp:	pointer to right page pointer
+ *	skip:	pointer to index to leave open
+ *	ilen:	insert length
+ *
+ * Returns:
+ *	Pointer to page in which to insert or NULL on error.
+ */
+static PAGE *
+bt_root(t, h, lp, rp, skip, ilen)
+	BTREE *t;
+	PAGE *h, **lp, **rp;
+	indx_t *skip;
+	size_t ilen;
+{
+	PAGE *l, *r, *tp;
+	pgno_t lnpg, rnpg;
+
+#ifdef STATISTICS
+	++bt_split;
+	++bt_rootsplit;
+#endif
+	/* Put the new left and right pages for the split into place. */
+	if ((l = __bt_new(t, &lnpg)) == NULL ||
+	    (r = __bt_new(t, &rnpg)) == NULL)
+		return (NULL);
+	l->pgno = lnpg;
+	r->pgno = rnpg;
+	l->nextpg = r->pgno;
+	r->prevpg = l->pgno;
+	l->prevpg = r->nextpg = P_INVALID;
+	l->lower = r->lower = BTDATAOFF;
+	l->upper = r->upper = t->bt_psize;
+	l->flags = r->flags = h->flags & P_TYPE;
+
+	/* Split the root page. */
+	tp = bt_psplit(t, h, l, r, skip, ilen);
+
+	*lp = l;
+	*rp = r;
+	return (tp);
+}
+
+/*
+ * BT_RROOT -- Fix up the recno root page after it has been split.
+ *
+ * Parameters:
+ *	t:	tree
+ *	h:	root page
+ *	l:	left page
+ *	r:	right page
+ *
+ * Returns:
+ *	RET_ERROR, RET_SUCCESS
+ */
+static int
+bt_rroot(t, h, l, r)
+	BTREE *t;
+	PAGE *h, *l, *r;
+{
+	char *dest;
+
+	/* Insert the left and right keys, set the header information. */
+	h->linp[0] = h->upper = t->bt_psize - NRINTERNAL;
+	dest = (char *)h + h->upper;
+	WR_RINTERNAL(dest,
+	    l->flags & P_RLEAF ? NEXTINDEX(l) : rec_total(l), l->pgno);
+
+	h->linp[1] = h->upper -= NRINTERNAL;
+	dest = (char *)h + h->upper;
+	WR_RINTERNAL(dest,
+	    r->flags & P_RLEAF ? NEXTINDEX(r) : rec_total(r), r->pgno);
+
+	h->lower = BTDATAOFF + 2 * sizeof(indx_t);
+
+	/* Unpin the root page, set to recno internal page. */
+	h->flags &= ~P_TYPE;
+	h->flags |= P_RINTERNAL;
+	mpool_put(t->bt_mp, h, MPOOL_DIRTY);
+
+	return (RET_SUCCESS);
+}
+
+/*
+ * BT_BROOT -- Fix up the btree root page after it has been split.
+ *
+ * Parameters:
+ *	t:	tree
+ *	h:	root page
+ *	l:	left page
+ *	r:	right page
+ *
+ * Returns:
+ *	RET_ERROR, RET_SUCCESS
+ */
+static int
+bt_broot(t, h, l, r)
+	BTREE *t;
+	PAGE *h, *l, *r;
+{
+	BINTERNAL *bi;
+	BLEAF *bl;
+	u_int32_t nbytes;
+	char *dest;
+
+	/*
+	 * If the root page was a leaf page, change it into an internal page.
+	 * We copy the key we split on (but not the key's data, in the case of
+	 * a leaf page) to the new root page.
+	 *
+	 * The btree comparison code guarantees that the left-most key on any
+	 * level of the tree is never used, so it doesn't need to be filled in.
+	 */
+	nbytes = NBINTERNAL(0);
+	h->linp[0] = h->upper = t->bt_psize - nbytes;
+	dest = (char *)h + h->upper;
+	WR_BINTERNAL(dest, 0, l->pgno, 0);
+
+	switch (h->flags & P_TYPE) {
+	case P_BLEAF:
+		bl = GETBLEAF(r, 0);
+		nbytes = NBINTERNAL(bl->ksize);
+		h->linp[1] = h->upper -= nbytes;
+		dest = (char *)h + h->upper;
+		WR_BINTERNAL(dest, bl->ksize, r->pgno, 0);
+		memmove(dest, bl->bytes, bl->ksize);
+
+		/*
+		 * If the key is on an overflow page, mark the overflow chain
+		 * so it isn't deleted when the leaf copy of the key is deleted.
+		 */
+		if (bl->flags & P_BIGKEY &&
+		    bt_preserve(t, *(pgno_t *)bl->bytes) == RET_ERROR)
+			return (RET_ERROR);
+		break;
+	case P_BINTERNAL:
+		bi = GETBINTERNAL(r, 0);
+		nbytes = NBINTERNAL(bi->ksize);
+		h->linp[1] = h->upper -= nbytes;
+		dest = (char *)h + h->upper;
+		memmove(dest, bi, nbytes);
+		((BINTERNAL *)dest)->pgno = r->pgno;
+		break;
+	default:
+		abort();
+	}
+
+	/* There are two keys on the page. */
+	h->lower = BTDATAOFF + 2 * sizeof(indx_t);
+
+	/* Unpin the root page, set to btree internal page. */
+	h->flags &= ~P_TYPE;
+	h->flags |= P_BINTERNAL;
+	mpool_put(t->bt_mp, h, MPOOL_DIRTY);
+
+	return (RET_SUCCESS);
+}
+
+/*
+ * BT_PSPLIT -- Do the real work of splitting the page.
+ *
+ * Parameters:
+ *	t:	tree
+ *	h:	page to be split
+ *	l:	page to put lower half of data
+ *	r:	page to put upper half of data
+ *	pskip:	pointer to index to leave open
+ *	ilen:	insert length
+ *
+ * Returns:
+ *	Pointer to page in which to insert.
+ */
+static PAGE *
+bt_psplit(t, h, l, r, pskip, ilen)
+	BTREE *t;
+	PAGE *h, *l, *r;
+	indx_t *pskip;
+	size_t ilen;
+{
+	BINTERNAL *bi;
+	BLEAF *bl;
+	CURSOR *c;
+	RLEAF *rl;
+	PAGE *rval;
+	void *src;
+	indx_t full, half, nxt, off, skip, top, used;
+	u_int32_t nbytes;
+	int bigkeycnt, isbigkey;
+
+	/*
+	 * Split the data to the left and right pages.  Leave the skip index
+	 * open.  Additionally, make some effort not to split on an overflow
+	 * key.  This makes internal page processing faster and can save
+	 * space as overflow keys used by internal pages are never deleted.
+	 */
+	bigkeycnt = 0;
+	skip = *pskip;
+	full = t->bt_psize - BTDATAOFF;
+	half = full / 2;
+	used = 0;
+	for (nxt = off = 0, top = NEXTINDEX(h); nxt < top; ++off) {
+		if (skip == off) {
+			nbytes = ilen;
+			isbigkey = 0;		/* XXX: not really known. */
+		} else
+			switch (h->flags & P_TYPE) {
+			case P_BINTERNAL:
+				src = bi = GETBINTERNAL(h, nxt);
+				nbytes = NBINTERNAL(bi->ksize);
+				isbigkey = bi->flags & P_BIGKEY;
+				break;
+			case P_BLEAF:
+				src = bl = GETBLEAF(h, nxt);
+				nbytes = NBLEAF(bl);
+				isbigkey = bl->flags & P_BIGKEY;
+				break;
+			case P_RINTERNAL:
+				src = GETRINTERNAL(h, nxt);
+				nbytes = NRINTERNAL;
+				isbigkey = 0;
+				break;
+			case P_RLEAF:
+				src = rl = GETRLEAF(h, nxt);
+				nbytes = NRLEAF(rl);
+				isbigkey = 0;
+				break;
+			default:
+				abort();
+			}
+
+		/*
+		 * If the key/data pairs are substantial fractions of the max
+		 * possible size for the page, it's possible to get situations
+		 * where we decide to try and copy too much onto the left page.
+		 * Make sure that doesn't happen.
+		 */
+		if (skip <= off && used + nbytes >= full) {
+			--off;
+			break;
+		}
+
+		/* Copy the key/data pair, if not the skipped index. */
+		if (skip != off) {
+			++nxt;
+
+			l->linp[off] = l->upper -= nbytes;
+			memmove((char *)l + l->upper, src, nbytes);
+		}
+
+		used += nbytes;
+		if (used >= half) {
+			if (!isbigkey || bigkeycnt == 3)
+				break;
+			else
+				++bigkeycnt;
+		}
+	}
+
+	/*
+	 * Off is the last offset that's valid for the left page.
+	 * Nxt is the first offset to be placed on the right page.
+	 */
+	l->lower += (off + 1) * sizeof(indx_t);
+
+	/*
+	 * If splitting the page that the cursor was on, the cursor has to be
+	 * adjusted to point to the same record as before the split.  If the
+	 * cursor is at or past the skipped slot, the cursor is incremented by
+	 * one.  If the cursor is on the right page, it is decremented by the
+	 * number of records split to the left page.
+	 */
+	c = &t->bt_cursor;
+	if (F_ISSET(c, CURS_INIT) && c->pg.pgno == h->pgno) {
+		if (c->pg.index >= skip)
+			++c->pg.index;
+		if (c->pg.index < nxt)			/* Left page. */
+			c->pg.pgno = l->pgno;
+		else {					/* Right page. */
+			c->pg.pgno = r->pgno;
+			c->pg.index -= nxt;
+		}
+	}
+
+	/*
+	 * If the skipped index was on the left page, just return that page.
+	 * Otherwise, adjust the skip index to reflect the new position on
+	 * the right page.
+	 */
+	if (skip <= off) {
+		skip = 0;
+		rval = l;
+	} else {
+		rval = r;
+		*pskip -= nxt;
+	}
+
+	for (off = 0; nxt < top; ++off) {
+		if (skip == nxt) {
+			++off;
+			skip = 0;
+		}
+		switch (h->flags & P_TYPE) {
+		case P_BINTERNAL:
+			src = bi = GETBINTERNAL(h, nxt);
+			nbytes = NBINTERNAL(bi->ksize);
+			break;
+		case P_BLEAF:
+			src = bl = GETBLEAF(h, nxt);
+			nbytes = NBLEAF(bl);
+			break;
+		case P_RINTERNAL:
+			src = GETRINTERNAL(h, nxt);
+			nbytes = NRINTERNAL;
+			break;
+		case P_RLEAF:
+			src = rl = GETRLEAF(h, nxt);
+			nbytes = NRLEAF(rl);
+			break;
+		default:
+			abort();
+		}
+		++nxt;
+		r->linp[off] = r->upper -= nbytes;
+		memmove((char *)r + r->upper, src, nbytes);
+	}
+	r->lower += off * sizeof(indx_t);
+
+	/* If the key is being appended to the page, adjust the index. */
+	if (skip == top)
+		r->lower += sizeof(indx_t);
+
+	return (rval);
+}
+
+/*
+ * BT_PRESERVE -- Mark a chain of pages as used by an internal node.
+ *
+ * Chains of indirect blocks pointed to by leaf nodes get reclaimed when the
+ * record that references them gets deleted.  Chains pointed to by internal
+ * pages never get deleted.  This routine marks a chain as pointed to by an
+ * internal page.
+ *
+ * Parameters:
+ *	t:	tree
+ *	pg:	page number of first page in the chain.
+ *
+ * Returns:
+ *	RET_SUCCESS, RET_ERROR.
+ */
+static int
+bt_preserve(t, pg)
+	BTREE *t;
+	pgno_t pg;
+{
+	PAGE *h;
+
+	if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
+		return (RET_ERROR);
+	h->flags |= P_PRESERVE;
+	mpool_put(t->bt_mp, h, MPOOL_DIRTY);
+	return (RET_SUCCESS);
+}
+
+/*
+ * REC_TOTAL -- Return the number of recno entries below a page.
+ *
+ * Parameters:
+ *	h:	page
+ *
+ * Returns:
+ *	The number of recno entries below a page.
+ *
+ * XXX
+ * These values could be set by the bt_psplit routine.  The problem is that the
+ * entry has to be popped off of the stack etc. or the values have to be passed
+ * all the way back to bt_split/bt_rroot and it's not very clean.
+ */
+static recno_t
+rec_total(h)
+	PAGE *h;
+{
+	recno_t recs;
+	indx_t nxt, top;
+
+	for (recs = 0, nxt = 0, top = NEXTINDEX(h); nxt < top; ++nxt)
+		recs += GETRINTERNAL(h, nxt)->nrecs;
+	return (recs);
+}