* 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.

15 files changed, 4797 insertions, 0 deletions

diff --git a/db/btree/bt_close.c b/db/btree/bt_close.c
new file mode 100644
index 0000000000..27f9ab660f
--- /dev/null
+++ b/db/btree/bt_close.c
@@ -0,0 +1,182 @@
+/*-
+ * 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_close.c	8.7 (Berkeley) 8/17/94";
+#endif /* LIBC_SCCS and not lint */
+
+#include <sys/param.h>
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <db.h>
+#include "btree.h"
+
+static int bt_meta __P((BTREE *));
+
+/*
+ * BT_CLOSE -- Close a btree.
+ *
+ * Parameters:
+ *	dbp:	pointer to access method
+ *
+ * Returns:
+ *	RET_ERROR, RET_SUCCESS
+ */
+int
+__bt_close(dbp)
+	DB *dbp;
+{
+	BTREE *t;
+	int fd;
+
+	t = dbp->internal;
+
+	/* Toss any page pinned across calls. */
+	if (t->bt_pinned != NULL) {
+		mpool_put(t->bt_mp, t->bt_pinned, 0);
+		t->bt_pinned = NULL;
+	}
+
+	/* Sync the tree. */
+	if (__bt_sync(dbp, 0) == RET_ERROR)
+		return (RET_ERROR);
+
+	/* Close the memory pool. */
+	if (mpool_close(t->bt_mp) == RET_ERROR)
+		return (RET_ERROR);
+
+	/* Free random memory. */
+	if (t->bt_cursor.key.data != NULL) {
+		free(t->bt_cursor.key.data);
+		t->bt_cursor.key.size = 0;
+		t->bt_cursor.key.data = NULL;
+	}
+	if (t->bt_rkey.data) {
+		free(t->bt_rkey.data);
+		t->bt_rkey.size = 0;
+		t->bt_rkey.data = NULL;
+	}
+	if (t->bt_rdata.data) {
+		free(t->bt_rdata.data);
+		t->bt_rdata.size = 0;
+		t->bt_rdata.data = NULL;
+	}
+
+	fd = t->bt_fd;
+	free(t);
+	free(dbp);
+	return (close(fd) ? RET_ERROR : RET_SUCCESS);
+}
+
+/*
+ * BT_SYNC -- sync the btree to disk.
+ *
+ * Parameters:
+ *	dbp:	pointer to access method
+ *
+ * Returns:
+ *	RET_SUCCESS, RET_ERROR.
+ */
+int
+__bt_sync(dbp, flags)
+	const DB *dbp;
+	u_int flags;
+{
+	BTREE *t;
+	int status;
+
+	t = dbp->internal;
+
+	/* Toss any page pinned across calls. */
+	if (t->bt_pinned != NULL) {
+		mpool_put(t->bt_mp, t->bt_pinned, 0);
+		t->bt_pinned = NULL;
+	}
+
+	/* Sync doesn't currently take any flags. */
+	if (flags != 0) {
+		errno = EINVAL;
+		return (RET_ERROR);
+	}
+
+	if (F_ISSET(t, B_INMEM | B_RDONLY) || !F_ISSET(t, B_MODIFIED))
+		return (RET_SUCCESS);
+
+	if (F_ISSET(t, B_METADIRTY) && bt_meta(t) == RET_ERROR)
+		return (RET_ERROR);
+
+	if ((status = mpool_sync(t->bt_mp)) == RET_SUCCESS)
+		F_CLR(t, B_MODIFIED);
+
+	return (status);
+}
+
+/*
+ * BT_META -- write the tree meta data to disk.
+ *
+ * Parameters:
+ *	t:	tree
+ *
+ * Returns:
+ *	RET_ERROR, RET_SUCCESS
+ */
+static int
+bt_meta(t)
+	BTREE *t;
+{
+	BTMETA m;
+	void *p;
+
+	if ((p = mpool_get(t->bt_mp, P_META, 0)) == NULL)
+		return (RET_ERROR);
+
+	/* Fill in metadata. */
+	m.magic = BTREEMAGIC;
+	m.version = BTREEVERSION;
+	m.psize = t->bt_psize;
+	m.free = t->bt_free;
+	m.nrecs = t->bt_nrecs;
+	m.flags = F_ISSET(t, SAVEMETA);
+
+	memmove(p, &m, sizeof(BTMETA));
+	mpool_put(t->bt_mp, p, MPOOL_DIRTY);
+	return (RET_SUCCESS);
+}
diff --git a/db/btree/bt_conv.c b/db/btree/bt_conv.c
new file mode 100644
index 0000000000..1cb208b14d
--- /dev/null
+++ b/db/btree/bt_conv.c
@@ -0,0 +1,221 @@
+/*-
+ * 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_conv.c	8.5 (Berkeley) 8/17/94";
+#endif /* LIBC_SCCS and not lint */
+
+#include <sys/param.h>
+
+#include <stdio.h>
+
+#include <db.h>
+#include "btree.h"
+
+static void mswap __P((PAGE *));
+
+/*
+ * __BT_BPGIN, __BT_BPGOUT --
+ *	Convert host-specific number layout to/from the host-independent
+ *	format stored on disk.
+ *
+ * Parameters:
+ *	t:	tree
+ *	pg:	page number
+ *	h:	page to convert
+ */
+void
+__bt_pgin(t, pg, pp)
+	void *t;
+	pgno_t pg;
+	void *pp;
+{
+	PAGE *h;
+	indx_t i, top;
+	u_char flags;
+	char *p;
+
+	if (!F_ISSET(((BTREE *)t), B_NEEDSWAP))
+		return;
+	if (pg == P_META) {
+		mswap(pp);
+		return;
+	}
+
+	h = pp;
+	M_32_SWAP(h->pgno);
+	M_32_SWAP(h->prevpg);
+	M_32_SWAP(h->nextpg);
+	M_32_SWAP(h->flags);
+	M_16_SWAP(h->lower);
+	M_16_SWAP(h->upper);
+
+	top = NEXTINDEX(h);
+	if ((h->flags & P_TYPE) == P_BINTERNAL)
+		for (i = 0; i < top; i++) {
+			M_16_SWAP(h->linp[i]);
+			p = (char *)GETBINTERNAL(h, i);
+			P_32_SWAP(p);
+			p += sizeof(u_int32_t);
+			P_32_SWAP(p);
+			p += sizeof(pgno_t);
+			if (*(u_char *)p & P_BIGKEY) {
+				p += sizeof(u_char);
+				P_32_SWAP(p);
+				p += sizeof(pgno_t);
+				P_32_SWAP(p);
+			}
+		}
+	else if ((h->flags & P_TYPE) == P_BLEAF)
+		for (i = 0; i < top; i++) {
+			M_16_SWAP(h->linp[i]);
+			p = (char *)GETBLEAF(h, i);
+			P_32_SWAP(p);
+			p += sizeof(u_int32_t);
+			P_32_SWAP(p);
+			p += sizeof(u_int32_t);
+			flags = *(u_char *)p;
+			if (flags & (P_BIGKEY | P_BIGDATA)) {
+				p += sizeof(u_char);
+				if (flags & P_BIGKEY) {
+					P_32_SWAP(p);
+					p += sizeof(pgno_t);
+					P_32_SWAP(p);
+				}
+				if (flags & P_BIGDATA) {
+					p += sizeof(u_int32_t);
+					P_32_SWAP(p);
+					p += sizeof(pgno_t);
+					P_32_SWAP(p);
+				}
+			}
+		}
+}
+
+void
+__bt_pgout(t, pg, pp)
+	void *t;
+	pgno_t pg;
+	void *pp;
+{
+	PAGE *h;
+	indx_t i, top;
+	u_char flags;
+	char *p;
+
+	if (!F_ISSET(((BTREE *)t), B_NEEDSWAP))
+		return;
+	if (pg == P_META) {
+		mswap(pp);
+		return;
+	}
+
+	h = pp;
+	top = NEXTINDEX(h);
+	if ((h->flags & P_TYPE) == P_BINTERNAL)
+		for (i = 0; i < top; i++) {
+			p = (char *)GETBINTERNAL(h, i);
+			P_32_SWAP(p);
+			p += sizeof(u_int32_t);
+			P_32_SWAP(p);
+			p += sizeof(pgno_t);
+			if (*(u_char *)p & P_BIGKEY) {
+				p += sizeof(u_char);
+				P_32_SWAP(p);
+				p += sizeof(pgno_t);
+				P_32_SWAP(p);
+			}
+			M_16_SWAP(h->linp[i]);
+		}
+	else if ((h->flags & P_TYPE) == P_BLEAF)
+		for (i = 0; i < top; i++) {
+			p = (char *)GETBLEAF(h, i);
+			P_32_SWAP(p);
+			p += sizeof(u_int32_t);
+			P_32_SWAP(p);
+			p += sizeof(u_int32_t);
+			flags = *(u_char *)p;
+			if (flags & (P_BIGKEY | P_BIGDATA)) {
+				p += sizeof(u_char);
+				if (flags & P_BIGKEY) {
+					P_32_SWAP(p);
+					p += sizeof(pgno_t);
+					P_32_SWAP(p);
+				}
+				if (flags & P_BIGDATA) {
+					p += sizeof(u_int32_t);
+					P_32_SWAP(p);
+					p += sizeof(pgno_t);
+					P_32_SWAP(p);
+				}
+			}
+			M_16_SWAP(h->linp[i]);
+		}
+
+	M_32_SWAP(h->pgno);
+	M_32_SWAP(h->prevpg);
+	M_32_SWAP(h->nextpg);
+	M_32_SWAP(h->flags);
+	M_16_SWAP(h->lower);
+	M_16_SWAP(h->upper);
+}
+
+/*
+ * MSWAP -- Actually swap the bytes on the meta page.
+ *
+ * Parameters:
+ *	p:	page to convert
+ */
+static void
+mswap(pg)
+	PAGE *pg;
+{
+	char *p;
+
+	p = (char *)pg;
+	P_32_SWAP(p);		/* magic */
+	p += sizeof(u_int32_t);
+	P_32_SWAP(p);		/* version */
+	p += sizeof(u_int32_t);
+	P_32_SWAP(p);		/* psize */
+	p += sizeof(u_int32_t);
+	P_32_SWAP(p);		/* free */
+	p += sizeof(u_int32_t);
+	P_32_SWAP(p);		/* nrecs */
+	p += sizeof(u_int32_t);
+	P_32_SWAP(p);		/* flags */
+	p += sizeof(u_int32_t);
+}
diff --git a/db/btree/bt_debug.c b/db/btree/bt_debug.c
new file mode 100644
index 0000000000..3aefbe7622
--- /dev/null
+++ b/db/btree/bt_debug.c
@@ -0,0 +1,329 @@
+/*-
+ * 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_debug.c	8.5 (Berkeley) 8/17/94";
+#endif /* LIBC_SCCS and not lint */
+
+#include <sys/param.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <db.h>
+#include "btree.h"
+
+#ifdef DEBUG
+/*
+ * BT_DUMP -- Dump the tree
+ *
+ * Parameters:
+ *	dbp:	pointer to the DB
+ */
+void
+__bt_dump(dbp)
+	DB *dbp;
+{
+	BTREE *t;
+	PAGE *h;
+	pgno_t i;
+	char *sep;
+
+	t = dbp->internal;
+	(void)fprintf(stderr, "%s: pgsz %d",
+	    F_ISSET(t, B_INMEM) ? "memory" : "disk", t->bt_psize);
+	if (F_ISSET(t, R_RECNO))
+		(void)fprintf(stderr, " keys %lu", t->bt_nrecs);
+#undef X
+#define	X(flag, name) \
+	if (F_ISSET(t, flag)) { \
+		(void)fprintf(stderr, "%s%s", sep, name); \
+		sep = ", "; \
+	}
+	if (t->flags != 0) {
+		sep = " flags (";
+		X(R_FIXLEN,	"FIXLEN");
+		X(B_INMEM,	"INMEM");
+		X(B_NODUPS,	"NODUPS");
+		X(B_RDONLY,	"RDONLY");
+		X(R_RECNO,	"RECNO");
+		X(B_METADIRTY,"METADIRTY");
+		(void)fprintf(stderr, ")\n");
+	}
+#undef X
+
+	for (i = P_ROOT; (h = mpool_get(t->bt_mp, i, 0)) != NULL; ++i) {
+		__bt_dpage(h);
+		(void)mpool_put(t->bt_mp, h, 0);
+	}
+}
+
+/*
+ * BT_DMPAGE -- Dump the meta page
+ *
+ * Parameters:
+ *	h:	pointer to the PAGE
+ */
+void
+__bt_dmpage(h)
+	PAGE *h;
+{
+	BTMETA *m;
+	char *sep;
+
+	m = (BTMETA *)h;
+	(void)fprintf(stderr, "magic %lx\n", m->magic);
+	(void)fprintf(stderr, "version %lu\n", m->version);
+	(void)fprintf(stderr, "psize %lu\n", m->psize);
+	(void)fprintf(stderr, "free %lu\n", m->free);
+	(void)fprintf(stderr, "nrecs %lu\n", m->nrecs);
+	(void)fprintf(stderr, "flags %lu", m->flags);
+#undef X
+#define	X(flag, name) \
+	if (m->flags & flag) { \
+		(void)fprintf(stderr, "%s%s", sep, name); \
+		sep = ", "; \
+	}
+	if (m->flags) {
+		sep = " (";
+		X(B_NODUPS,	"NODUPS");
+		X(R_RECNO,	"RECNO");
+		(void)fprintf(stderr, ")");
+	}
+}
+
+/*
+ * BT_DNPAGE -- Dump the page
+ *
+ * Parameters:
+ *	n:	page number to dump.
+ */
+void
+__bt_dnpage(dbp, pgno)
+	DB *dbp;
+	pgno_t pgno;
+{
+	BTREE *t;
+	PAGE *h;
+
+	t = dbp->internal;
+	if ((h = mpool_get(t->bt_mp, pgno, 0)) != NULL) {
+		__bt_dpage(h);
+		(void)mpool_put(t->bt_mp, h, 0);
+	}
+}
+
+/*
+ * BT_DPAGE -- Dump the page
+ *
+ * Parameters:
+ *	h:	pointer to the PAGE
+ */
+void
+__bt_dpage(h)
+	PAGE *h;
+{
+	BINTERNAL *bi;
+	BLEAF *bl;
+	RINTERNAL *ri;
+	RLEAF *rl;
+	indx_t cur, top;
+	char *sep;
+
+	(void)fprintf(stderr, "    page %d: (", h->pgno);
+#undef X
+#define	X(flag, name) \
+	if (h->flags & flag) { \
+		(void)fprintf(stderr, "%s%s", sep, name); \
+		sep = ", "; \
+	}
+	sep = "";
+	X(P_BINTERNAL,	"BINTERNAL")		/* types */
+	X(P_BLEAF,	"BLEAF")
+	X(P_RINTERNAL,	"RINTERNAL")		/* types */
+	X(P_RLEAF,	"RLEAF")
+	X(P_OVERFLOW,	"OVERFLOW")
+	X(P_PRESERVE,	"PRESERVE");
+	(void)fprintf(stderr, ")\n");
+#undef X
+
+	(void)fprintf(stderr, "\tprev %2d next %2d", h->prevpg, h->nextpg);
+	if (h->flags & P_OVERFLOW)
+		return;
+
+	top = NEXTINDEX(h);
+	(void)fprintf(stderr, " lower %3d upper %3d nextind %d\n",
+	    h->lower, h->upper, top);
+	for (cur = 0; cur < top; cur++) {
+		(void)fprintf(stderr, "\t[%03d] %4d ", cur, h->linp[cur]);
+		switch (h->flags & P_TYPE) {
+		case P_BINTERNAL:
+			bi = GETBINTERNAL(h, cur);
+			(void)fprintf(stderr,
+			    "size %03d pgno %03d", bi->ksize, bi->pgno);
+			if (bi->flags & P_BIGKEY)
+				(void)fprintf(stderr, " (indirect)");
+			else if (bi->ksize)
+				(void)fprintf(stderr,
+				    " {%.*s}", (int)bi->ksize, bi->bytes);
+			break;
+		case P_RINTERNAL:
+			ri = GETRINTERNAL(h, cur);
+			(void)fprintf(stderr, "entries %03d pgno %03d",
+				ri->nrecs, ri->pgno);
+			break;
+		case P_BLEAF:
+			bl = GETBLEAF(h, cur);
+			if (bl->flags & P_BIGKEY)
+				(void)fprintf(stderr,
+				    "big key page %lu size %u/",
+				    *(pgno_t *)bl->bytes,
+				    *(u_int32_t *)(bl->bytes + sizeof(pgno_t)));
+			else if (bl->ksize)
+				(void)fprintf(stderr, "%s/", bl->bytes);
+			if (bl->flags & P_BIGDATA)
+				(void)fprintf(stderr,
+				    "big data page %lu size %u",
+				    *(pgno_t *)(bl->bytes + bl->ksize),
+				    *(u_int32_t *)(bl->bytes + bl->ksize +
+				    sizeof(pgno_t)));
+			else if (bl->dsize)
+				(void)fprintf(stderr, "%.*s",
+				    (int)bl->dsize, bl->bytes + bl->ksize);
+			break;
+		case P_RLEAF:
+			rl = GETRLEAF(h, cur);
+			if (rl->flags & P_BIGDATA)
+				(void)fprintf(stderr,
+				    "big data page %lu size %u",
+				    *(pgno_t *)rl->bytes,
+				    *(u_int32_t *)(rl->bytes + sizeof(pgno_t)));
+			else if (rl->dsize)
+				(void)fprintf(stderr,
+				    "%.*s", (int)rl->dsize, rl->bytes);
+			break;
+		}
+		(void)fprintf(stderr, "\n");
+	}
+}
+#endif
+
+#ifdef STATISTICS
+/*
+ * BT_STAT -- Gather/print the tree statistics
+ *
+ * Parameters:
+ *	dbp:	pointer to the DB
+ */
+void
+__bt_stat(dbp)
+	DB *dbp;
+{
+	extern u_long bt_cache_hit, bt_cache_miss, bt_pfxsaved, bt_rootsplit;
+	extern u_long bt_sortsplit, bt_split;
+	BTREE *t;
+	PAGE *h;
+	pgno_t i, pcont, pinternal, pleaf;
+	u_long ifree, lfree, nkeys;
+	int levels;
+
+	t = dbp->internal;
+	pcont = pinternal = pleaf = 0;
+	nkeys = ifree = lfree = 0;
+	for (i = P_ROOT; (h = mpool_get(t->bt_mp, i, 0)) != NULL; ++i) {
+		switch (h->flags & P_TYPE) {
+		case P_BINTERNAL:
+		case P_RINTERNAL:
+			++pinternal;
+			ifree += h->upper - h->lower;
+			break;
+		case P_BLEAF:
+		case P_RLEAF:
+			++pleaf;
+			lfree += h->upper - h->lower;
+			nkeys += NEXTINDEX(h);
+			break;
+		case P_OVERFLOW:
+			++pcont;
+			break;
+		}
+		(void)mpool_put(t->bt_mp, h, 0);
+	}
+
+	/* Count the levels of the tree. */
+	for (i = P_ROOT, levels = 0 ;; ++levels) {
+		h = mpool_get(t->bt_mp, i, 0);
+		if (h->flags & (P_BLEAF|P_RLEAF)) {
+			if (levels == 0)
+				levels = 1;
+			(void)mpool_put(t->bt_mp, h, 0);
+			break;
+		}
+		i = F_ISSET(t, R_RECNO) ?
+		    GETRINTERNAL(h, 0)->pgno :
+		    GETBINTERNAL(h, 0)->pgno;
+		(void)mpool_put(t->bt_mp, h, 0);
+	}
+
+	(void)fprintf(stderr, "%d level%s with %ld keys",
+	    levels, levels == 1 ? "" : "s", nkeys);
+	if (F_ISSET(t, R_RECNO))
+		(void)fprintf(stderr, " (%ld header count)", t->bt_nrecs);
+	(void)fprintf(stderr,
+	    "\n%lu pages (leaf %ld, internal %ld, overflow %ld)\n",
+	    pinternal + pleaf + pcont, pleaf, pinternal, pcont);
+	(void)fprintf(stderr, "%ld cache hits, %ld cache misses\n",
+	    bt_cache_hit, bt_cache_miss);
+	(void)fprintf(stderr, "%ld splits (%ld root splits, %ld sort splits)\n",
+	    bt_split, bt_rootsplit, bt_sortsplit);
+	pleaf *= t->bt_psize - BTDATAOFF;
+	if (pleaf)
+		(void)fprintf(stderr,
+		    "%.0f%% leaf fill (%ld bytes used, %ld bytes free)\n",
+		    ((double)(pleaf - lfree) / pleaf) * 100,
+		    pleaf - lfree, lfree);
+	pinternal *= t->bt_psize - BTDATAOFF;
+	if (pinternal)
+		(void)fprintf(stderr,
+		    "%.0f%% internal fill (%ld bytes used, %ld bytes free\n",
+		    ((double)(pinternal - ifree) / pinternal) * 100,
+		    pinternal - ifree, ifree);
+	if (bt_pfxsaved)
+		(void)fprintf(stderr, "prefix checking removed %lu bytes.\n",
+		    bt_pfxsaved);
+}
+#endif
diff --git a/db/btree/bt_delete.c b/db/btree/bt_delete.c
new file mode 100644
index 0000000000..ece1ab656e
--- /dev/null
+++ b/db/btree/bt_delete.c
@@ -0,0 +1,657 @@
+/*-
+ * 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_delete.c	8.13 (Berkeley) 7/28/94";
+#endif /* LIBC_SCCS and not lint */
+
+#include <sys/types.h>
+
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+
+#include <db.h>
+#include "btree.h"
+
+static int __bt_bdelete __P((BTREE *, const DBT *));
+static int __bt_curdel __P((BTREE *, const DBT *, PAGE *, u_int));
+static int __bt_pdelete __P((BTREE *, PAGE *));
+static int __bt_relink __P((BTREE *, PAGE *));
+static int __bt_stkacq __P((BTREE *, PAGE **, CURSOR *));
+
+/*
+ * __bt_delete
+ *	Delete the item(s) referenced by a key.
+ *
+ * Return RET_SPECIAL if the key is not found.
+ */
+int
+__bt_delete(dbp, key, flags)
+	const DB *dbp;
+	const DBT *key;
+	u_int flags;
+{
+	BTREE *t;
+	CURSOR *c;
+	PAGE *h;
+	int status;
+
+	t = dbp->internal;
+
+	/* Toss any page pinned across calls. */
+	if (t->bt_pinned != NULL) {
+		mpool_put(t->bt_mp, t->bt_pinned, 0);
+		t->bt_pinned = NULL;
+	}
+
+	/* Check for change to a read-only tree. */
+	if (F_ISSET(t, B_RDONLY)) {
+		errno = EPERM;
+		return (RET_ERROR);
+	}
+
+	switch (flags) {
+	case 0:
+		status = __bt_bdelete(t, key);
+		break;
+	case R_CURSOR:
+		/*
+		 * If flags is R_CURSOR, delete the cursor.  Must already
+		 * have started a scan and not have already deleted it.
+		 */
+		c = &t->bt_cursor;
+		if (F_ISSET(c, CURS_INIT)) {
+			if (F_ISSET(c, CURS_ACQUIRE | CURS_AFTER | CURS_BEFORE))
+				return (RET_SPECIAL);
+			if ((h = mpool_get(t->bt_mp, c->pg.pgno, 0)) == NULL)
+				return (RET_ERROR);
+
+			/*
+			 * If the page is about to be emptied, we'll need to
+			 * delete it, which means we have to acquire a stack.
+			 */
+			if (NEXTINDEX(h) == 1)
+				if (__bt_stkacq(t, &h, &t->bt_cursor))
+					return (RET_ERROR);
+
+			status = __bt_dleaf(t, NULL, h, c->pg.index);
+
+			if (NEXTINDEX(h) == 0 && status == RET_SUCCESS) {
+				if (__bt_pdelete(t, h))
+					return (RET_ERROR);
+			} else
+				mpool_put(t->bt_mp,
+				    h, status == RET_SUCCESS ? MPOOL_DIRTY : 0);
+			break;
+		}
+		/* FALLTHROUGH */
+	default:
+		errno = EINVAL;
+		return (RET_ERROR);
+	}
+	if (status == RET_SUCCESS)
+		F_SET(t, B_MODIFIED);
+	return (status);
+}
+
+/*
+ * __bt_stkacq --
+ *	Acquire a stack so we can delete a cursor entry.
+ *
+ * Parameters:
+ *	  t:	tree
+ *	 hp:	pointer to current, pinned PAGE pointer
+ *	  c:	pointer to the cursor
+ *
+ * Returns:
+ *	0 on success, 1 on failure
+ */
+static int
+__bt_stkacq(t, hp, c)
+	BTREE *t;
+	PAGE **hp;
+	CURSOR *c;
+{
+	BINTERNAL *bi;
+	EPG *e;
+	EPGNO *parent;
+	PAGE *h;
+	indx_t index;
+	pgno_t pgno;
+	recno_t nextpg, prevpg;
+	int exact, level;
+	
+	/*
+	 * Find the first occurrence of the key in the tree.  Toss the
+	 * currently locked page so we don't hit an already-locked page.
+	 */
+	h = *hp;
+	mpool_put(t->bt_mp, h, 0);
+	if ((e = __bt_search(t, &c->key, &exact)) == NULL)
+		return (1);
+	h = e->page;
+
+	/* See if we got it in one shot. */
+	if (h->pgno == c->pg.pgno)
+		goto ret;
+
+	/*
+	 * Move right, looking for the page.  At each move we have to move
+	 * up the stack until we don't have to move to the next page.  If
+	 * we have to change pages at an internal level, we have to fix the
+	 * stack back up.
+	 */
+	while (h->pgno != c->pg.pgno) {
+		if ((nextpg = h->nextpg) == P_INVALID)
+			break;
+		mpool_put(t->bt_mp, h, 0);
+
+		/* Move up the stack. */
+		for (level = 0; (parent = BT_POP(t)) != NULL; ++level) {
+			/* Get the parent page. */
+			if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
+				return (1);
+
+			/* Move to the next index. */
+			if (parent->index != NEXTINDEX(h) - 1) {
+				index = parent->index + 1;
+				BT_PUSH(t, h->pgno, index);
+				break;
+			}
+			mpool_put(t->bt_mp, h, 0);
+		}
+
+		/* Restore the stack. */
+		while (level--) {
+			/* Push the next level down onto the stack. */
+			bi = GETBINTERNAL(h, index);
+			pgno = bi->pgno;
+			BT_PUSH(t, pgno, 0);
+
+			/* Lose the currently pinned page. */
+			mpool_put(t->bt_mp, h, 0);
+
+			/* Get the next level down. */
+			if ((h = mpool_get(t->bt_mp, pgno, 0)) == NULL)
+				return (1);
+			index = 0;
+		}
+		mpool_put(t->bt_mp, h, 0);
+		if ((h = mpool_get(t->bt_mp, nextpg, 0)) == NULL)
+			return (1);
+	}
+
+	if (h->pgno == c->pg.pgno)
+		goto ret;
+
+	/* Reacquire the original stack. */
+	mpool_put(t->bt_mp, h, 0);
+	if ((e = __bt_search(t, &c->key, &exact)) == NULL)
+		return (1);
+	h = e->page;
+
+	/*
+	 * Move left, looking for the page.  At each move we have to move
+	 * up the stack until we don't have to change pages to move to the
+	 * next page.  If we have to change pages at an internal level, we
+	 * have to fix the stack back up.
+	 */
+	while (h->pgno != c->pg.pgno) {
+		if ((prevpg = h->prevpg) == P_INVALID)
+			break;
+		mpool_put(t->bt_mp, h, 0);
+
+		/* Move up the stack. */
+		for (level = 0; (parent = BT_POP(t)) != NULL; ++level) {
+			/* Get the parent page. */
+			if ((h = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
+				return (1);
+
+			/* Move to the next index. */
+			if (parent->index != 0) {
+				index = parent->index - 1;
+				BT_PUSH(t, h->pgno, index);
+				break;
+			}
+			mpool_put(t->bt_mp, h, 0);
+		}
+
+		/* Restore the stack. */
+		while (level--) {
+			/* Push the next level down onto the stack. */
+			bi = GETBINTERNAL(h, index);
+			pgno = bi->pgno;
+
+			/* Lose the currently pinned page. */
+			mpool_put(t->bt_mp, h, 0);
+
+			/* Get the next level down. */
+			if ((h = mpool_get(t->bt_mp, pgno, 0)) == NULL)
+				return (1);
+
+			index = NEXTINDEX(h) - 1;
+			BT_PUSH(t, pgno, index);
+		}
+		mpool_put(t->bt_mp, h, 0);
+		if ((h = mpool_get(t->bt_mp, prevpg, 0)) == NULL)
+			return (1);
+	}
+	
+
+ret:	mpool_put(t->bt_mp, h, 0);
+	return ((*hp = mpool_get(t->bt_mp, c->pg.pgno, 0)) == NULL);
+}
+
+/*
+ * __bt_bdelete --
+ *	Delete all key/data pairs matching the specified key.
+ *
+ * Parameters:
+ *	  t:	tree
+ *	key:	key to delete
+ *
+ * Returns:
+ *	RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found.
+ */
+static int
+__bt_bdelete(t, key)
+	BTREE *t;
+	const DBT *key;
+{
+	EPG *e;
+	PAGE *h;
+	int deleted, exact, redo;
+
+	deleted = 0;
+
+	/* Find any matching record; __bt_search pins the page. */
+loop:	if ((e = __bt_search(t, key, &exact)) == NULL)
+		return (deleted ? RET_SUCCESS : RET_ERROR);
+	if (!exact) {
+		mpool_put(t->bt_mp, e->page, 0);
+		return (deleted ? RET_SUCCESS : RET_SPECIAL);
+	}
+
+	/*
+	 * Delete forward, then delete backward, from the found key.  If
+	 * there are duplicates and we reach either side of the page, do
+	 * the key search again, so that we get them all.
+	 */
+	redo = 0;
+	h = e->page;
+	do {
+		if (__bt_dleaf(t, key, h, e->index)) {
+			mpool_put(t->bt_mp, h, 0);
+			return (RET_ERROR);
+		}
+		if (F_ISSET(t, B_NODUPS)) {
+			if (NEXTINDEX(h) == 0) {
+				if (__bt_pdelete(t, h))
+					return (RET_ERROR);
+			} else
+				mpool_put(t->bt_mp, h, MPOOL_DIRTY);
+			return (RET_SUCCESS);
+		}
+		deleted = 1;
+	} while (e->index < NEXTINDEX(h) && __bt_cmp(t, key, e) == 0);
+
+	/* Check for right-hand edge of the page. */
+	if (e->index == NEXTINDEX(h))
+		redo = 1;
+
+	/* Delete from the key to the beginning of the page. */
+	while (e->index-- > 0) {
+		if (__bt_cmp(t, key, e) != 0)
+			break;
+		if (__bt_dleaf(t, key, h, e->index) == RET_ERROR) {
+			mpool_put(t->bt_mp, h, 0);
+			return (RET_ERROR);
+		}
+		if (e->index == 0)
+			redo = 1;
+	}
+
+	/* Check for an empty page. */
+	if (NEXTINDEX(h) == 0) {
+		if (__bt_pdelete(t, h))
+			return (RET_ERROR);
+		goto loop;
+	}
+
+	/* Put the page. */
+	mpool_put(t->bt_mp, h, MPOOL_DIRTY);
+
+	if (redo)
+		goto loop;
+	return (RET_SUCCESS);
+}
+
+/*
+ * __bt_pdelete --
+ *	Delete a single page from the tree.
+ *
+ * Parameters:
+ *	t:	tree
+ *	h:	leaf page
+ *
+ * Returns:
+ *	RET_SUCCESS, RET_ERROR.
+ *
+ * Side-effects:
+ *	mpool_put's the page
+ */
+static int
+__bt_pdelete(t, h)
+	BTREE *t;
+	PAGE *h;
+{
+	BINTERNAL *bi;
+	PAGE *pg;
+	EPGNO *parent;
+	indx_t cnt, index, *ip, offset;
+	u_int32_t nksize;
+	char *from;
+
+	/*
+	 * Walk the parent page stack -- a LIFO stack of the pages that were
+	 * traversed when we searched for the page where the delete occurred.
+	 * 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 deleted
+	 * a page, so we have to delete the key from the parent page.
+	 *
+	 * If the delete from the parent page makes it empty, this process may
+	 * continue all the way up the tree.  We stop if we reach the root page
+	 * (which is never deleted, it's just not worth the effort) or if the
+	 * delete does not empty the page.
+	 */
+	while ((parent = BT_POP(t)) != NULL) {
+		/* Get the parent page. */
+		if ((pg = mpool_get(t->bt_mp, parent->pgno, 0)) == NULL)
+			return (RET_ERROR);
+		
+		index = parent->index;
+		bi = GETBINTERNAL(pg, index);
+
+		/* Free any overflow pages. */
+		if (bi->flags & P_BIGKEY &&
+		    __ovfl_delete(t, bi->bytes) == RET_ERROR) {
+			mpool_put(t->bt_mp, pg, 0);
+			return (RET_ERROR);
+		}
+
+		/*
+		 * Free the parent if it has only the one key and it's not the
+		 * root page. If it's the rootpage, turn it back into an empty
+		 * leaf page.
+		 */
+		if (NEXTINDEX(pg) == 1)
+			if (pg->pgno == P_ROOT) {
+				pg->lower = BTDATAOFF;
+				pg->upper = t->bt_psize;
+				pg->flags = P_BLEAF;
+			} else {
+				if (__bt_relink(t, pg) || __bt_free(t, pg))
+					return (RET_ERROR);
+				continue;
+			}
+		else {
+			/* Pack remaining key items at the end of the page. */
+			nksize = NBINTERNAL(bi->ksize);
+			from = (char *)pg + pg->upper;
+			memmove(from + nksize, from, (char *)bi - from);
+			pg->upper += nksize;
+
+			/* Adjust indices' offsets, shift the indices down. */
+			offset = pg->linp[index];
+			for (cnt = index, ip = &pg->linp[0]; cnt--; ++ip)
+				if (ip[0] < offset)
+					ip[0] += nksize;
+			for (cnt = NEXTINDEX(pg) - index; --cnt; ++ip)
+				ip[0] = ip[1] < offset ? ip[1] + nksize : ip[1];
+			pg->lower -= sizeof(indx_t);
+		}
+
+		mpool_put(t->bt_mp, pg, MPOOL_DIRTY);
+		break;
+	}
+
+	/* Free the leaf page, as long as it wasn't the root. */
+	if (h->pgno == P_ROOT) {
+		mpool_put(t->bt_mp, h, MPOOL_DIRTY);
+		return (RET_SUCCESS);
+	}
+	return (__bt_relink(t, h) || __bt_free(t, h));
+}
+
+/*
+ * __bt_dleaf --
+ *	Delete a single record from a leaf page.
+ *
+ * Parameters:
+ *	t:	tree
+ *    key:	referenced key
+ *	h:	page
+ *	index:	index on page to delete
+ *
+ * Returns:
+ *	RET_SUCCESS, RET_ERROR.
+ */
+int
+__bt_dleaf(t, key, h, index)
+	BTREE *t;
+	const DBT *key;
+	PAGE *h;
+	u_int index;
+{
+	BLEAF *bl;
+	indx_t cnt, *ip, offset;
+	u_int32_t nbytes;
+	void *to;
+	char *from;
+
+	/* If this record is referenced by the cursor, delete the cursor. */
+	if (F_ISSET(&t->bt_cursor, CURS_INIT) &&
+	    !F_ISSET(&t->bt_cursor, CURS_ACQUIRE) &&
+	    t->bt_cursor.pg.pgno == h->pgno && t->bt_cursor.pg.index == index &&
+	    __bt_curdel(t, key, h, index))
+		return (RET_ERROR);
+
+	/* If the entry uses overflow pages, make them available for reuse. */
+	to = bl = GETBLEAF(h, index);
+	if (bl->flags & P_BIGKEY && __ovfl_delete(t, bl->bytes) == RET_ERROR)
+		return (RET_ERROR);
+	if (bl->flags & P_BIGDATA &&
+	    __ovfl_delete(t, bl->bytes + bl->ksize) == RET_ERROR)
+		return (RET_ERROR);
+
+	/* Pack the remaining key/data items at the end of the page. */
+	nbytes = NBLEAF(bl);
+	from = (char *)h + h->upper;
+	memmove(from + nbytes, from, (char *)to - from);
+	h->upper += nbytes;
+
+	/* Adjust the indices' offsets, shift the indices down. */
+	offset = h->linp[index];
+	for (cnt = index, ip = &h->linp[0]; cnt--; ++ip)
+		if (ip[0] < offset)
+			ip[0] += nbytes;
+	for (cnt = NEXTINDEX(h) - index; --cnt; ++ip)
+		ip[0] = ip[1] < offset ? ip[1] + nbytes : ip[1];
+	h->lower -= sizeof(indx_t);
+
+	/* If the cursor is on this page, adjust it as necessary. */
+	if (F_ISSET(&t->bt_cursor, CURS_INIT) &&
+	    !F_ISSET(&t->bt_cursor, CURS_ACQUIRE) &&
+	    t->bt_cursor.pg.pgno == h->pgno && t->bt_cursor.pg.index > index)
+		--t->bt_cursor.pg.index;
+
+	return (RET_SUCCESS);
+}
+
+/*
+ * __bt_curdel --
+ *	Delete the cursor.
+ *
+ * Parameters:
+ *	t:	tree
+ *    key:	referenced key (or NULL)
+ *	h:	page
+ *  index:	index on page to delete
+ *
+ * Returns:
+ *	RET_SUCCESS, RET_ERROR.
+ */
+static int
+__bt_curdel(t, key, h, index)
+	BTREE *t;
+	const DBT *key;
+	PAGE *h;
+	u_int index;
+{
+	CURSOR *c;
+	EPG e;
+	PAGE *pg;
+	int curcopy, status;
+
+	/*
+	 * If there are duplicates, move forward or backward to one.
+	 * Otherwise, copy the key into the cursor area.
+	 */
+	c = &t->bt_cursor;
+	F_CLR(c, CURS_AFTER | CURS_BEFORE | CURS_ACQUIRE);
+
+	curcopy = 0;
+	if (!F_ISSET(t, B_NODUPS)) {
+		/*
+		 * We're going to have to do comparisons.  If we weren't
+		 * provided a copy of the key, i.e. the user is deleting
+		 * the current cursor position, get one.
+		 */
+		if (key == NULL) {
+			e.page = h;
+			e.index = index;
+			if ((status = __bt_ret(t, &e,
+			    &c->key, &c->key, NULL, NULL, 1)) != RET_SUCCESS)
+				return (status);
+			curcopy = 1;
+			key = &c->key;
+		}
+		/* Check previous key, if not at the beginning of the page. */
+		if (index > 0) { 
+			e.page = h;
+			e.index = index - 1;
+			if (__bt_cmp(t, key, &e) == 0) {
+				F_SET(c, CURS_BEFORE);
+				goto dup2;
+			}
+		}
+		/* Check next key, if not at the end of the page. */
+		if (index < NEXTINDEX(h) - 1) {
+			e.page = h;
+			e.index = index + 1;
+			if (__bt_cmp(t, key, &e) == 0) {
+				F_SET(c, CURS_AFTER);
+				goto dup2;
+			}
+		}
+		/* Check previous key if at the beginning of the page. */
+		if (index == 0 && h->prevpg != P_INVALID) {
+			if ((pg = mpool_get(t->bt_mp, h->prevpg, 0)) == NULL)
+				return (RET_ERROR);
+			e.page = pg;
+			e.index = NEXTINDEX(pg) - 1;
+			if (__bt_cmp(t, key, &e) == 0) {
+				F_SET(c, CURS_BEFORE);
+				goto dup1;
+			}
+			mpool_put(t->bt_mp, pg, 0);
+		}
+		/* Check next key if at the end of the page. */
+		if (index == NEXTINDEX(h) - 1 && h->nextpg != P_INVALID) {
+			if ((pg = mpool_get(t->bt_mp, h->nextpg, 0)) == NULL)
+				return (RET_ERROR);
+			e.page = pg;
+			e.index = 0;
+			if (__bt_cmp(t, key, &e) == 0) {
+				F_SET(c, CURS_AFTER);
+dup1:				mpool_put(t->bt_mp, pg, 0);
+dup2:				c->pg.pgno = e.page->pgno;
+				c->pg.index = e.index;
+				return (RET_SUCCESS);
+			}
+			mpool_put(t->bt_mp, pg, 0);
+		}
+	}
+	e.page = h;
+	e.index = index;
+	if (curcopy || (status =
+	    __bt_ret(t, &e, &c->key, &c->key, NULL, NULL, 1)) == RET_SUCCESS) {
+		F_SET(c, CURS_ACQUIRE);
+		return (RET_SUCCESS);
+	}
+	return (status);
+}
+
+/*
+ * __bt_relink --
+ *	Link around a deleted page.
+ *
+ * Parameters:
+ *	t:	tree
+ *	h:	page to be deleted
+ */
+static int
+__bt_relink(t, h)
+	BTREE *t;
+	PAGE *h;
+{
+	PAGE *pg;
+
+	if (h->nextpg != P_INVALID) {
+		if ((pg = mpool_get(t->bt_mp, h->nextpg, 0)) == NULL)
+			return (RET_ERROR);
+		pg->prevpg = h->prevpg;
+		mpool_put(t->bt_mp, pg, MPOOL_DIRTY);
+	}
+	if (h->prevpg != P_INVALID) {
+		if ((pg = mpool_get(t->bt_mp, h->prevpg, 0)) == NULL)
+			return (RET_ERROR);
+		pg->nextpg = h->nextpg;
+		mpool_put(t->bt_mp, pg, MPOOL_DIRTY);
+	}
+	return (0);
+}
diff --git a/db/btree/bt_get.c b/db/btree/bt_get.c
new file mode 100644
index 0000000000..74824c73f4
--- /dev/null
+++ b/db/btree/bt_get.c
@@ -0,0 +1,105 @@
+/*-
+ * 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_get.c	8.6 (Berkeley) 7/20/94";
+#endif /* LIBC_SCCS and not lint */
+
+#include <sys/types.h>
+
+#include <errno.h>
+#include <stddef.h>
+#include <stdio.h>
+
+#include <db.h>
+#include "btree.h"
+
+/*
+ * __BT_GET -- Get a record from the btree.
+ *
+ * Parameters:
+ *	dbp:	pointer to access method
+ *	key:	key to find
+ *	data:	data to return
+ *	flag:	currently unused
+ *
+ * Returns:
+ *	RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key not found.
+ */
+int
+__bt_get(dbp, key, data, flags)
+	const DB *dbp;
+	const DBT *key;
+	DBT *data;
+	u_int flags;
+{
+	BTREE *t;
+	EPG *e;
+	int exact, status;
+
+	t = dbp->internal;
+
+	/* Toss any page pinned across calls. */
+	if (t->bt_pinned != NULL) {
+		mpool_put(t->bt_mp, t->bt_pinned, 0);
+		t->bt_pinned = NULL;
+	}
+
+	/* Get currently doesn't take any flags. */
+	if (flags) {
+		errno = EINVAL;
+		return (RET_ERROR);
+	}
+
+	if ((e = __bt_search(t, key, &exact)) == NULL)
+		return (RET_ERROR);
+	if (!exact) {
+		mpool_put(t->bt_mp, e->page, 0);
+		return (RET_SPECIAL);
+	}
+
+	status = __bt_ret(t, e, NULL, NULL, data, &t->bt_rdata, 0);
+
+	/*
+	 * If the user is doing concurrent access, we copied the
+	 * key/data, toss the page.
+	 */
+	if (F_ISSET(t, B_DB_LOCK))
+		mpool_put(t->bt_mp, e->page, 0);
+	else
+		t->bt_pinned = e->page;
+	return (status);
+}
diff --git a/db/btree/bt_open.c b/db/btree/bt_open.c
new file mode 100644
index 0000000000..f052249777
--- /dev/null
+++ b/db/btree/bt_open.c
@@ -0,0 +1,444 @@
+/*-
+ * 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_open.c	8.10 (Berkeley) 8/17/94";
+#endif /* LIBC_SCCS and not lint */
+
+/*
+ * Implementation of btree access method for 4.4BSD.
+ *
+ * The design here was originally based on that of the btree access method
+ * used in the Postgres database system at UC Berkeley.  This implementation
+ * is wholly independent of the Postgres code.
+ */
+
+#include <sys/param.h>
+#include <sys/stat.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <db.h>
+#include "btree.h"
+
+#ifdef DEBUG
+#undef	MINPSIZE
+#define	MINPSIZE	128
+#endif
+
+static int byteorder __P((void));
+static int nroot __P((BTREE *));
+static int tmp __P((void));
+
+/*
+ * __BT_OPEN -- Open a btree.
+ *
+ * Creates and fills a DB struct, and calls the routine that actually
+ * opens the btree.
+ *
+ * Parameters:
+ *	fname:	filename (NULL for in-memory trees)
+ *	flags:	open flag bits
+ *	mode:	open permission bits
+ *	b:	BTREEINFO pointer
+ *
+ * Returns:
+ *	NULL on failure, pointer to DB on success.
+ *
+ */
+DB *
+__bt_open(fname, flags, mode, openinfo, dflags)
+	const char *fname;
+	int flags, mode, dflags;
+	const BTREEINFO *openinfo;
+{
+	struct stat sb;
+	BTMETA m;
+	BTREE *t;
+	BTREEINFO b;
+	DB *dbp;
+	pgno_t ncache;
+	ssize_t nr;
+	int machine_lorder;
+
+	t = NULL;
+
+	/*
+	 * Intention is to make sure all of the user's selections are okay
+	 * here and then use them without checking.  Can't be complete, since
+	 * we don't know the right page size, lorder or flags until the backing
+	 * file is opened.  Also, the file's page size can cause the cachesize
+	 * to change.
+	 */
+	machine_lorder = byteorder();
+	if (openinfo) {
+		b = *openinfo;
+
+		/* Flags: R_DUP. */
+		if (b.flags & ~(R_DUP))
+			goto einval;
+
+		/*
+		 * Page size must be indx_t aligned and >= MINPSIZE.  Default
+		 * page size is set farther on, based on the underlying file
+		 * transfer size.
+		 */
+		if (b.psize &&
+		    (b.psize < MINPSIZE || b.psize > MAX_PAGE_OFFSET + 1 ||
+		    b.psize & sizeof(indx_t) - 1))
+			goto einval;
+
+		/* Minimum number of keys per page; absolute minimum is 2. */
+		if (b.minkeypage) {
+			if (b.minkeypage < 2)
+				goto einval;
+		} else
+			b.minkeypage = DEFMINKEYPAGE;
+
+		/* If no comparison, use default comparison and prefix. */
+		if (b.compare == NULL) {
+			b.compare = __bt_defcmp;
+			if (b.prefix == NULL)
+				b.prefix = __bt_defpfx;
+		}
+
+		if (b.lorder == 0)
+			b.lorder = machine_lorder;
+	} else {
+		b.compare = __bt_defcmp;
+		b.cachesize = 0;
+		b.flags = 0;
+		b.lorder = machine_lorder;
+		b.minkeypage = DEFMINKEYPAGE;
+		b.prefix = __bt_defpfx;
+		b.psize = 0;
+	}
+
+	/* Check for the ubiquitous PDP-11. */
+	if (b.lorder != BIG_ENDIAN && b.lorder != LITTLE_ENDIAN)
+		goto einval;
+
+	/* Allocate and initialize DB and BTREE structures. */
+	if ((t = (BTREE *)malloc(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;
+	t->bt_cmp = b.compare;
+	t->bt_pfx = b.prefix;
+	t->bt_rfd = -1;
+
+	if ((t->bt_dbp = dbp = (DB *)malloc(sizeof(DB))) == NULL)
+		goto err;
+	memset(t->bt_dbp, 0, sizeof(DB));
+	if (t->bt_lorder != machine_lorder)
+		F_SET(t, B_NEEDSWAP);
+
+	dbp->type = DB_BTREE;
+	dbp->internal = t;
+	dbp->close = __bt_close;
+	dbp->del = __bt_delete;
+	dbp->fd = __bt_fd;
+	dbp->get = __bt_get;
+	dbp->put = __bt_put;
+	dbp->seq = __bt_seq;
+	dbp->sync = __bt_sync;
+
+	/*
+	 * If no file name was supplied, this is an in-memory btree and we
+	 * open a backing temporary file.  Otherwise, it's a disk-based tree.
+	 */
+	if (fname) {
+		switch (flags & O_ACCMODE) {
+		case O_RDONLY:
+			F_SET(t, B_RDONLY);
+			break;
+		case O_RDWR:
+			break;
+		case O_WRONLY:
+		default:
+			goto einval;
+		}
+		
+		if ((t->bt_fd = open(fname, flags, mode)) < 0)
+			goto err;
+
+	} else {
+		if ((flags & O_ACCMODE) != O_RDWR)
+			goto einval;
+		if ((t->bt_fd = tmp()) == -1)
+			goto err;
+		F_SET(t, B_INMEM);
+	}
+
+	if (fcntl(t->bt_fd, F_SETFD, 1) == -1)
+		goto err;
+
+	if (fstat(t->bt_fd, &sb))
+		goto err;
+	if (sb.st_size) {
+		if ((nr = read(t->bt_fd, &m, sizeof(BTMETA))) < 0)
+			goto err;
+		if (nr != sizeof(BTMETA))
+			goto eftype;
+
+		/*
+		 * Read in the meta-data.  This can change the notion of what
+		 * the lorder, page size and flags are, and, when the page size
+		 * changes, the cachesize value can change too.  If the user
+		 * specified the wrong byte order for an existing database, we
+		 * don't bother to return an error, we just clear the NEEDSWAP
+		 * bit.
+		 */
+		if (m.magic == BTREEMAGIC)
+			F_CLR(t, B_NEEDSWAP);
+		else {
+			F_SET(t, B_NEEDSWAP);
+			M_32_SWAP(m.magic);
+			M_32_SWAP(m.version);
+			M_32_SWAP(m.psize);
+			M_32_SWAP(m.free);
+			M_32_SWAP(m.nrecs);
+			M_32_SWAP(m.flags);
+		}
+		if (m.magic != BTREEMAGIC || m.version != BTREEVERSION)
+			goto eftype;
+		if (m.psize < MINPSIZE || m.psize > MAX_PAGE_OFFSET + 1 ||
+		    m.psize & sizeof(indx_t) - 1)
+			goto eftype;
+		if (m.flags & ~SAVEMETA)
+			goto eftype;
+		b.psize = m.psize;
+		F_SET(t, m.flags);
+		t->bt_free = m.free;
+		t->bt_nrecs = m.nrecs;
+	} else {
+		/*
+		 * Set the page size to the best value for I/O to this file.
+		 * Don't overflow the page offset type.
+		 */
+		if (b.psize == 0) {
+			b.psize = sb.st_blksize;
+			if (b.psize < MINPSIZE)
+				b.psize = MINPSIZE;
+			if (b.psize > MAX_PAGE_OFFSET + 1)
+				b.psize = MAX_PAGE_OFFSET + 1;
+		}
+
+		/* Set flag if duplicates permitted. */
+		if (!(b.flags & R_DUP))
+			F_SET(t, B_NODUPS);
+
+		t->bt_free = P_INVALID;
+		t->bt_nrecs = 0;
+		F_SET(t, B_METADIRTY);
+	}
+
+	t->bt_psize = b.psize;
+
+	/* Set the cache size; must be a multiple of the page size. */
+	if (b.cachesize && b.cachesize & b.psize - 1)
+		b.cachesize += (~b.cachesize & b.psize - 1) + 1;
+	if (b.cachesize < b.psize * MINCACHE)
+		b.cachesize = b.psize * MINCACHE;
+
+	/* Calculate number of pages to cache. */
+	ncache = (b.cachesize + t->bt_psize - 1) / t->bt_psize;
+
+	/*
+	 * The btree data structure requires that at least two keys can fit on
+	 * a page, but other than that there's no fixed requirement.  The user
+	 * specified a minimum number per page, and we translated that into the
+	 * number of bytes a key/data pair can use before being placed on an
+	 * overflow page.  This calculation includes the page header, the size
+	 * of the index referencing the leaf item and the size of the leaf item
+	 * structure.  Also, don't let the user specify a minkeypage such that
+	 * a key/data pair won't fit even if both key and data are on overflow
+	 * pages.
+	 */
+	t->bt_ovflsize = (t->bt_psize - BTDATAOFF) / b.minkeypage -
+	    (sizeof(indx_t) + NBLEAFDBT(0, 0));
+	if (t->bt_ovflsize < NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t))
+		t->bt_ovflsize =
+		    NBLEAFDBT(NOVFLSIZE, NOVFLSIZE) + sizeof(indx_t);
+
+	/* Initialize the buffer pool. */
+	if ((t->bt_mp =
+	    mpool_open(NULL, t->bt_fd, t->bt_psize, ncache)) == NULL)
+		goto err;
+	if (!F_ISSET(t, B_INMEM))
+		mpool_filter(t->bt_mp, __bt_pgin, __bt_pgout, t);
+
+	/* Create a root page if new tree. */
+	if (nroot(t) == RET_ERROR)
+		goto err;
+
+	/* Global flags. */
+	if (dflags & DB_LOCK)
+		F_SET(t, B_DB_LOCK);
+	if (dflags & DB_SHMEM)
+		F_SET(t, B_DB_SHMEM);
+	if (dflags & DB_TXN)
+		F_SET(t, B_DB_TXN);
+
+	return (dbp);
+
+einval:	errno = EINVAL;
+	goto err;
+
+eftype:	errno = EFTYPE;
+	goto err;
+
+err:	if (t) {
+		if (t->bt_dbp)
+			free(t->bt_dbp);
+		if (t->bt_fd != -1)
+			(void)close(t->bt_fd);
+		free(t);
+	}
+	return (NULL);
+}
+
+/*
+ * NROOT -- Create the root of a new tree.
+ *
+ * Parameters:
+ *	t:	tree
+ *
+ * Returns:
+ *	RET_ERROR, RET_SUCCESS
+ */
+static int
+nroot(t)
+	BTREE *t;
+{
+	PAGE *meta, *root;
+	pgno_t npg;
+
+	if ((meta = mpool_get(t->bt_mp, 0, 0)) != NULL) {
+		mpool_put(t->bt_mp, meta, 0);
+		return (RET_SUCCESS);
+	}
+	if (errno != EINVAL)		/* It's OK to not exist. */
+		return (RET_ERROR);
+	errno = 0;
+
+	if ((meta = mpool_new(t->bt_mp, &npg)) == NULL)
+		return (RET_ERROR);
+
+	if ((root = mpool_new(t->bt_mp, &npg)) == NULL)
+		return (RET_ERROR);
+
+	if (npg != P_ROOT)
+		return (RET_ERROR);
+	root->pgno = npg;
+	root->prevpg = root->nextpg = P_INVALID;
+	root->lower = BTDATAOFF;
+	root->upper = t->bt_psize;
+	root->flags = P_BLEAF;
+	memset(meta, 0, t->bt_psize);
+	mpool_put(t->bt_mp, meta, MPOOL_DIRTY);
+	mpool_put(t->bt_mp, root, MPOOL_DIRTY);
+	return (RET_SUCCESS);
+}
+
+static int
+tmp()
+{
+	sigset_t set, oset;
+	int fd;
+	char *envtmp;
+	char path[MAXPATHLEN];
+
+	envtmp = getenv("TMPDIR");
+	(void)snprintf(path,
+	    sizeof(path), "%s/bt.XXXXXX", envtmp ? envtmp : "/tmp");
+
+	(void)sigfillset(&set);
+	(void)sigprocmask(SIG_BLOCK, &set, &oset);
+	if ((fd = mkstemp(path)) != -1)
+		(void)unlink(path);
+	(void)sigprocmask(SIG_SETMASK, &oset, NULL);
+	return(fd);
+}
+
+static int
+byteorder()
+{
+	u_int32_t x;
+	u_char *p;
+
+	x = 0x01020304;
+	p = (u_char *)&x;
+	switch (*p) {
+	case 1:
+		return (BIG_ENDIAN);
+	case 4:
+		return (LITTLE_ENDIAN);
+	default:
+		return (0);
+	}
+}
+
+int
+__bt_fd(dbp)
+        const DB *dbp;
+{
+	BTREE *t;
+
+	t = dbp->internal;
+
+	/* Toss any page pinned across calls. */
+	if (t->bt_pinned != NULL) {
+		mpool_put(t->bt_mp, t->bt_pinned, 0);
+		t->bt_pinned = NULL;
+	}
+
+	/* In-memory database can't have a file descriptor. */
+	if (F_ISSET(t, B_INMEM)) {
+		errno = ENOENT;
+		return (-1);
+	}
+	return (t->bt_fd);
+}
diff --git a/db/btree/bt_overflow.c b/db/btree/bt_overflow.c
new file mode 100644
index 0000000000..b28b8e0471
--- /dev/null
+++ b/db/btree/bt_overflow.c
@@ -0,0 +1,228 @@
+/*-
+ * 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_overflow.c	8.5 (Berkeley) 7/16/94";
+#endif /* LIBC_SCCS and not lint */
+
+#include <sys/param.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <db.h>
+#include "btree.h"
+
+/*
+ * Big key/data code.
+ *
+ * Big key and data entries are stored on linked lists of pages.  The initial
+ * reference is byte string stored with the key or data and is the page number
+ * and size.  The actual record is stored in a chain of pages linked by the
+ * nextpg field of the PAGE header.
+ *
+ * The first page of the chain has a special property.  If the record is used
+ * by an internal page, it cannot be deleted and the P_PRESERVE bit will be set
+ * in the header.
+ *
+ * XXX
+ * A single DBT is written to each chain, so a lot of space on the last page
+ * is wasted.  This is a fairly major bug for some data sets.
+ */
+
+/*
+ * __OVFL_GET -- Get an overflow key/data item.
+ *
+ * Parameters:
+ *	t:	tree
+ *	p:	pointer to { pgno_t, u_int32_t }
+ *	buf:	storage address
+ *	bufsz:	storage size
+ *
+ * Returns:
+ *	RET_ERROR, RET_SUCCESS
+ */
+int
+__ovfl_get(t, p, ssz, buf, bufsz)
+	BTREE *t;
+	void *p;
+	size_t *ssz;
+	void **buf;
+	size_t *bufsz;
+{
+	PAGE *h;
+	pgno_t pg;
+	size_t nb, plen;
+	u_int32_t sz;
+
+	memmove(&pg, p, sizeof(pgno_t));
+	memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(u_int32_t));
+	*ssz = sz;
+
+#ifdef DEBUG
+	if (pg == P_INVALID || sz == 0)
+		abort();
+#endif
+	/* Make the buffer bigger as necessary. */
+	if (*bufsz < sz) {
+		*buf = (char *)(*buf == NULL ? malloc(sz) : realloc(*buf, sz));
+		if (*buf == NULL)
+			return (RET_ERROR);
+		*bufsz = sz;
+	}
+
+	/*
+	 * Step through the linked list of pages, copying the data on each one
+	 * into the buffer.  Never copy more than the data's length.
+	 */
+	plen = t->bt_psize - BTDATAOFF;
+	for (p = *buf;; p = (char *)p + nb, pg = h->nextpg) {
+		if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
+			return (RET_ERROR);
+
+		nb = MIN(sz, plen);
+		memmove(p, (char *)h + BTDATAOFF, nb);
+		mpool_put(t->bt_mp, h, 0);
+
+		if ((sz -= nb) == 0)
+			break;
+	}
+	return (RET_SUCCESS);
+}
+
+/*
+ * __OVFL_PUT -- Store an overflow key/data item.
+ *
+ * Parameters:
+ *	t:	tree
+ *	data:	DBT to store
+ *	pgno:	storage page number
+ *
+ * Returns:
+ *	RET_ERROR, RET_SUCCESS
+ */
+int
+__ovfl_put(t, dbt, pg)
+	BTREE *t;
+	const DBT *dbt;
+	pgno_t *pg;
+{
+	PAGE *h, *last;
+	void *p;
+	pgno_t npg;
+	size_t nb, plen;
+	u_int32_t sz;
+
+	/*
+	 * Allocate pages and copy the key/data record into them.  Store the
+	 * number of the first page in the chain.
+	 */
+	plen = t->bt_psize - BTDATAOFF;
+	for (last = NULL, p = dbt->data, sz = dbt->size;;
+	    p = (char *)p + plen, last = h) {
+		if ((h = __bt_new(t, &npg)) == NULL)
+			return (RET_ERROR);
+
+		h->pgno = npg;
+		h->nextpg = h->prevpg = P_INVALID;
+		h->flags = P_OVERFLOW;
+		h->lower = h->upper = 0;
+
+		nb = MIN(sz, plen);
+		memmove((char *)h + BTDATAOFF, p, nb);
+
+		if (last) {
+			last->nextpg = h->pgno;
+			mpool_put(t->bt_mp, last, MPOOL_DIRTY);
+		} else
+			*pg = h->pgno;
+
+		if ((sz -= nb) == 0) {
+			mpool_put(t->bt_mp, h, MPOOL_DIRTY);
+			break;
+		}
+	}
+	return (RET_SUCCESS);
+}
+
+/*
+ * __OVFL_DELETE -- Delete an overflow chain.
+ *
+ * Parameters:
+ *	t:	tree
+ *	p:	pointer to { pgno_t, u_int32_t }
+ *
+ * Returns:
+ *	RET_ERROR, RET_SUCCESS
+ */
+int
+__ovfl_delete(t, p)
+	BTREE *t;
+	void *p;
+{
+	PAGE *h;
+	pgno_t pg;
+	size_t plen;
+	u_int32_t sz;
+
+	memmove(&pg, p, sizeof(pgno_t));
+	memmove(&sz, (char *)p + sizeof(pgno_t), sizeof(u_int32_t));
+
+#ifdef DEBUG
+	if (pg == P_INVALID || sz == 0)
+		abort();
+#endif
+	if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
+		return (RET_ERROR);
+
+	/* Don't delete chains used by internal pages. */
+	if (h->flags & P_PRESERVE) {
+		mpool_put(t->bt_mp, h, 0);
+		return (RET_SUCCESS);
+	}
+
+	/* Step through the chain, calling the free routine for each page. */
+	for (plen = t->bt_psize - BTDATAOFF;; sz -= plen) {
+		pg = h->nextpg;
+		__bt_free(t, h);
+		if (sz <= plen)
+			break;
+		if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
+			return (RET_ERROR);
+	}
+	return (RET_SUCCESS);
+}
diff --git a/db/btree/bt_page.c b/db/btree/bt_page.c
new file mode 100644
index 0000000000..0d9d138d5c
--- /dev/null
+++ b/db/btree/bt_page.c
@@ -0,0 +1,98 @@
+/*-
+ * Copyright (c) 1990, 1993, 1994
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * 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_page.c	8.3 (Berkeley) 7/14/94";
+#endif /* LIBC_SCCS and not lint */
+
+#include <sys/types.h>
+
+#include <stdio.h>
+
+#include <db.h>
+#include "btree.h"
+
+/*
+ * __bt_free --
+ *	Put a page on the freelist.
+ *
+ * Parameters:
+ *	t:	tree
+ *	h:	page to free
+ *
+ * Returns:
+ *	RET_ERROR, RET_SUCCESS
+ *
+ * Side-effect:
+ *	mpool_put's the page.
+ */
+int
+__bt_free(t, h)
+	BTREE *t;
+	PAGE *h;
+{
+	/* Insert the page at the head of the free list. */
+	h->prevpg = P_INVALID;
+	h->nextpg = t->bt_free;
+	t->bt_free = h->pgno;
+
+	/* Make sure the page gets written back. */
+	return (mpool_put(t->bt_mp, h, MPOOL_DIRTY));
+}
+
+/*
+ * __bt_new --
+ *	Get a new page, preferably from the freelist.
+ *
+ * Parameters:
+ *	t:	tree
+ *	npg:	storage for page number.
+ *
+ * Returns:
+ *	Pointer to a page, NULL on error.
+ */
+PAGE *
+__bt_new(t, npg)
+	BTREE *t;
+	pgno_t *npg;
+{
+	PAGE *h;
+
+	if (t->bt_free != P_INVALID &&
+	    (h = mpool_get(t->bt_mp, t->bt_free, 0)) != NULL) {
+		*npg = t->bt_free;
+		t->bt_free = h->nextpg;
+		return (h);
+	}
+	return (mpool_new(t->bt_mp, npg));
+}
diff --git a/db/btree/bt_put.c b/db/btree/bt_put.c
new file mode 100644
index 0000000000..952be09e55
--- /dev/null
+++ b/db/btree/bt_put.c
@@ -0,0 +1,320 @@
+/*-
+ * 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_put.c	8.8 (Berkeley) 7/26/94";
+#endif /* LIBC_SCCS and not lint */
+
+#include <sys/types.h>
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <db.h>
+#include "btree.h"
+
+static EPG *bt_fast __P((BTREE *, const DBT *, const DBT *, int *));
+
+/*
+ * __BT_PUT -- Add a btree item to the tree.
+ *
+ * Parameters:
+ *	dbp:	pointer to access method
+ *	key:	key
+ *	data:	data
+ *	flag:	R_NOOVERWRITE
+ *
+ * Returns:
+ *	RET_ERROR, RET_SUCCESS and RET_SPECIAL if the key is already in the
+ *	tree and R_NOOVERWRITE specified.
+ */
+int
+__bt_put(dbp, key, data, flags)
+	const DB *dbp;
+	DBT *key;
+	const DBT *data;
+	u_int flags;
+{
+	BTREE *t;
+	DBT tkey, tdata;
+	EPG *e;
+	PAGE *h;
+	indx_t index, nxtindex;
+	pgno_t pg;
+	u_int32_t nbytes;
+	int dflags, exact, status;
+	char *dest, db[NOVFLSIZE], kb[NOVFLSIZE];
+
+	t = dbp->internal;
+
+	/* Toss any page pinned across calls. */
+	if (t->bt_pinned != NULL) {
+		mpool_put(t->bt_mp, t->bt_pinned, 0);
+		t->bt_pinned = NULL;
+	}
+
+	/* Check for change to a read-only tree. */
+	if (F_ISSET(t, B_RDONLY)) {
+		errno = EPERM;
+		return (RET_ERROR);
+	}
+
+	switch (flags) {
+	case 0:
+	case R_NOOVERWRITE:
+		break;
+	case R_CURSOR:
+		/*
+		 * If flags is R_CURSOR, put the cursor.  Must already
+		 * have started a scan and not have already deleted it.
+		 */
+		if (F_ISSET(&t->bt_cursor, CURS_INIT) &&
+		    !F_ISSET(&t->bt_cursor,
+		        CURS_ACQUIRE | CURS_AFTER | CURS_BEFORE))
+			break;
+		/* FALLTHROUGH */
+	default:
+		errno = EINVAL;
+		return (RET_ERROR);
+	}
+
+	/*
+	 * If the key/data pair won't fit on a page, store it on overflow
+	 * pages.  Only put the key on the overflow page if the pair are
+	 * still too big after moving the data to an overflow page.
+	 *
+	 * XXX
+	 * If the insert fails later on, the overflow pages aren't recovered.
+	 */
+	dflags = 0;
+	if (key->size + data->size > t->bt_ovflsize) {
+		if (key->size > t->bt_ovflsize) {
+storekey:		if (__ovfl_put(t, key, &pg) == RET_ERROR)
+				return (RET_ERROR);
+			tkey.data = kb;
+			tkey.size = NOVFLSIZE;
+			memmove(kb, &pg, sizeof(pgno_t));
+			memmove(kb + sizeof(pgno_t),
+			    &key->size, sizeof(u_int32_t));
+			dflags |= P_BIGKEY;
+			key = &tkey;
+		}
+		if (key->size + data->size > t->bt_ovflsize) {
+			if (__ovfl_put(t, data, &pg) == RET_ERROR)
+				return (RET_ERROR);
+			tdata.data = db;
+			tdata.size = NOVFLSIZE;
+			memmove(db, &pg, sizeof(pgno_t));
+			memmove(db + sizeof(pgno_t),
+			    &data->size, sizeof(u_int32_t));
+			dflags |= P_BIGDATA;
+			data = &tdata;
+		}
+		if (key->size + data->size > t->bt_ovflsize)
+			goto storekey;
+	}
+
+	/* Replace the cursor. */
+	if (flags == R_CURSOR) {
+		if ((h = mpool_get(t->bt_mp, t->bt_cursor.pg.pgno, 0)) == NULL)
+			return (RET_ERROR);
+		index = t->bt_cursor.pg.index;
+		goto delete;
+	}
+
+	/*
+	 * Find the key to delete, or, the location at which to insert.
+	 * Bt_fast and __bt_search both pin the returned page.
+	 */
+	if (t->bt_order == NOT || (e = bt_fast(t, key, data, &exact)) == NULL)
+		if ((e = __bt_search(t, key, &exact)) == NULL)
+			return (RET_ERROR);
+	h = e->page;
+	index = e->index;
+
+	/*
+	 * Add the key/data pair to the tree.  If an identical key is already
+	 * in the tree, and R_NOOVERWRITE is set, an error is returned.  If
+	 * R_NOOVERWRITE is not set, the key is either added (if duplicates are
+	 * permitted) or an error is returned.
+	 */
+	switch (flags) {
+	case R_NOOVERWRITE:
+		if (!exact)
+			break;
+		mpool_put(t->bt_mp, h, 0);
+		return (RET_SPECIAL);
+	default:
+		if (!exact || !F_ISSET(t, B_NODUPS))
+			break;
+		/*
+		 * !!!
+		 * Note, the delete may empty the page, so we need to put a
+		 * new entry into the page immediately.
+		 */
+delete:		if (__bt_dleaf(t, key, h, index) == RET_ERROR) {
+			mpool_put(t->bt_mp, h, 0);
+			return (RET_ERROR);
+		}
+		break;
+	}
+
+	/*
+	 * If not enough room, or the user has put a ceiling on the number of
+	 * keys permitted in the page, split the page.  The split code will
+	 * insert the key and data and unpin the current page.  If inserting
+	 * into the offset array, shift the pointers up.
+	 */
+	nbytes = NBLEAFDBT(key->size, data->size);
+	if (h->upper - h->lower < nbytes + sizeof(indx_t)) {
+		if ((status = __bt_split(t, h, key,
+		    data, dflags, nbytes, index)) != RET_SUCCESS)
+			return (status);
+		goto success;
+	}
+
+	if (index < (nxtindex = NEXTINDEX(h)))
+		memmove(h->linp + index + 1, h->linp + index,
+		    (nxtindex - index) * sizeof(indx_t));
+	h->lower += sizeof(indx_t);
+
+	h->linp[index] = h->upper -= nbytes;
+	dest = (char *)h + h->upper;
+	WR_BLEAF(dest, key, data, dflags);
+
+	/* If the cursor is on this page, adjust it as necessary. */
+	if (F_ISSET(&t->bt_cursor, CURS_INIT) &&
+	    !F_ISSET(&t->bt_cursor, CURS_ACQUIRE) &&
+	    t->bt_cursor.pg.pgno == h->pgno && t->bt_cursor.pg.index >= index)
+		++t->bt_cursor.pg.index;
+
+	if (t->bt_order == NOT)
+		if (h->nextpg == P_INVALID) {
+			if (index == NEXTINDEX(h) - 1) {
+				t->bt_order = FORWARD;
+				t->bt_last.index = index;
+				t->bt_last.pgno = h->pgno;
+			}
+		} else if (h->prevpg == P_INVALID) {
+			if (index == 0) {
+				t->bt_order = BACK;
+				t->bt_last.index = 0;
+				t->bt_last.pgno = h->pgno;
+			}
+		}
+
+	mpool_put(t->bt_mp, h, MPOOL_DIRTY);
+
+success:
+	if (flags == R_SETCURSOR)
+		__bt_setcur(t, e->page->pgno, e->index);
+
+	F_SET(t, B_MODIFIED);
+	return (RET_SUCCESS);
+}
+
+#ifdef STATISTICS
+u_long bt_cache_hit, bt_cache_miss;
+#endif
+
+/*
+ * BT_FAST -- Do a quick check for sorted data.
+ *
+ * Parameters:
+ *	t:	tree
+ *	key:	key to insert
+ *
+ * Returns:
+ * 	EPG for new record or NULL if not found.
+ */
+static EPG *
+bt_fast(t, key, data, exactp)
+	BTREE *t;
+	const DBT *key, *data;
+	int *exactp;
+{
+	PAGE *h;
+	u_int32_t nbytes;
+	int cmp;
+
+	if ((h = mpool_get(t->bt_mp, t->bt_last.pgno, 0)) == NULL) {
+		t->bt_order = NOT;
+		return (NULL);
+	}
+	t->bt_cur.page = h;
+	t->bt_cur.index = t->bt_last.index;
+
+	/*
+	 * If won't fit in this page or have too many keys in this page,
+	 * have to search to get split stack.
+	 */
+	nbytes = NBLEAFDBT(key->size, data->size);
+	if (h->upper - h->lower < nbytes + sizeof(indx_t))
+		goto miss;
+
+	if (t->bt_order == FORWARD) {
+		if (t->bt_cur.page->nextpg != P_INVALID)
+			goto miss;
+		if (t->bt_cur.index != NEXTINDEX(h) - 1)
+			goto miss;
+		if ((cmp = __bt_cmp(t, key, &t->bt_cur)) < 0)
+			goto miss;
+		t->bt_last.index = cmp ? ++t->bt_cur.index : t->bt_cur.index;
+	} else {
+		if (t->bt_cur.page->prevpg != P_INVALID)
+			goto miss;
+		if (t->bt_cur.index != 0)
+			goto miss;
+		if ((cmp = __bt_cmp(t, key, &t->bt_cur)) > 0)
+			goto miss;
+		t->bt_last.index = 0;
+	}
+	*exactp = cmp == 0;
+#ifdef STATISTICS
+	++bt_cache_hit;
+#endif
+	return (&t->bt_cur);
+
+miss:
+#ifdef STATISTICS
+	++bt_cache_miss;
+#endif
+	t->bt_order = NOT;
+	mpool_put(t->bt_mp, h, 0);
+	return (NULL);
+}
diff --git a/db/btree/bt_search.c b/db/btree/bt_search.c
new file mode 100644
index 0000000000..485afcbbf0
--- /dev/null
+++ b/db/btree/bt_search.c
@@ -0,0 +1,213 @@
+/*-
+ * 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_search.c	8.8 (Berkeley) 7/31/94";
+#endif /* LIBC_SCCS and not lint */
+
+#include <sys/types.h>
+
+#include <stdio.h>
+
+#include <db.h>
+#include "btree.h"
+
+static int __bt_snext __P((BTREE *, PAGE *, const DBT *, int *));
+static int __bt_sprev __P((BTREE *, PAGE *, const DBT *, int *));
+
+/*
+ * __bt_search --
+ *	Search a btree for a key.
+ *
+ * Parameters:
+ *	t:	tree to search
+ *	key:	key to find
+ *	exactp:	pointer to exact match flag
+ *
+ * Returns:
+ *	The EPG for matching record, if any, or the EPG for the location
+ *	of the key, if it were inserted into the tree, is entered into
+ *	the bt_cur field of the tree.  A pointer to the field is returned.
+ */
+EPG *
+__bt_search(t, key, exactp)
+	BTREE *t;
+	const DBT *key;
+	int *exactp;
+{
+	PAGE *h;
+	indx_t base, index, lim;
+	pgno_t pg;
+	int cmp;
+
+	BT_CLR(t);
+	for (pg = P_ROOT;;) {
+		if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
+			return (NULL);
+
+		/* Do a binary search on the current page. */
+		t->bt_cur.page = h;
+		for (base = 0, lim = NEXTINDEX(h); lim; lim >>= 1) {
+			t->bt_cur.index = index = base + (lim >> 1);
+			if ((cmp = __bt_cmp(t, key, &t->bt_cur)) == 0) {
+				if (h->flags & P_BLEAF) {
+					*exactp = 1;
+					return (&t->bt_cur);
+				}
+				goto next;
+			}
+			if (cmp > 0) {
+				base = index + 1;
+				--lim;
+			}
+		}
+
+		/*
+		 * If it's a leaf page, we're almost done.  If no duplicates
+		 * are allowed, or we have an exact match, we're done.  Else,
+		 * it's possible that there were matching keys on this page,
+		 * which later deleted, and we're on a page with no matches
+		 * while there are matches on other pages.  If at the start or
+		 * end of a page, check the adjacent page.
+		 */
+		if (h->flags & P_BLEAF) {
+			if (!F_ISSET(t, B_NODUPS)) {
+				if (base == 0 &&
+				    h->prevpg != P_INVALID &&
+				    __bt_sprev(t, h, key, exactp))
+					return (&t->bt_cur);
+				if (base == NEXTINDEX(h) &&
+				    h->nextpg != P_INVALID &&
+				    __bt_snext(t, h, key, exactp))
+					return (&t->bt_cur);
+			}
+			*exactp = 0;
+			t->bt_cur.index = base;
+			return (&t->bt_cur);
+		}
+
+		/*
+		 * No match found.  Base is the smallest index greater than
+		 * key and may be zero or a last + 1 index.  If it's non-zero,
+		 * decrement by one, and record the internal page which should
+		 * be a parent page for the key.  If a split later occurs, the
+		 * inserted page will be to the right of the saved page.
+		 */
+		index = base ? base - 1 : base;
+
+next:		BT_PUSH(t, h->pgno, index);
+		pg = GETBINTERNAL(h, index)->pgno;
+		mpool_put(t->bt_mp, h, 0);
+	}
+}
+
+/*
+ * __bt_snext --
+ *	Check for an exact match after the key.
+ *
+ * Parameters:
+ *	t:	tree
+ *	h:	current page
+ *	key:	key
+ *	exactp:	pointer to exact match flag
+ *
+ * Returns:
+ *	If an exact match found.
+ */
+static int
+__bt_snext(t, h, key, exactp)
+	BTREE *t;
+	PAGE *h;
+	const DBT *key;
+	int *exactp;
+{
+	EPG e;
+
+	/*
+	 * Get the next page.  The key is either an exact
+	 * match, or not as good as the one we already have.
+	 */
+	if ((e.page = mpool_get(t->bt_mp, h->nextpg, 0)) == NULL)
+		return (0);
+	e.index = 0;
+	if (__bt_cmp(t, key, &e) == 0) {
+		mpool_put(t->bt_mp, h, 0);
+		t->bt_cur = e;
+		*exactp = 1;
+		return (1);
+	}
+	mpool_put(t->bt_mp, e.page, 0);
+	return (0);
+}
+
+/*
+ * __bt_sprev --
+ *	Check for an exact match before the key.
+ *
+ * Parameters:
+ *	t:	tree
+ *	h:	current page
+ *	key:	key
+ *	exactp:	pointer to exact match flag
+ *
+ * Returns:
+ *	If an exact match found.
+ */
+static int
+__bt_sprev(t, h, key, exactp)
+	BTREE *t;
+	PAGE *h;
+	const DBT *key;
+	int *exactp;
+{
+	EPG e;
+
+	/*
+	 * Get the previous page.  The key is either an exact
+	 * match, or not as good as the one we already have.
+	 */
+	if ((e.page = mpool_get(t->bt_mp, h->prevpg, 0)) == NULL)
+		return (0);
+	e.index = NEXTINDEX(e.page) - 1;
+	if (__bt_cmp(t, key, &e) == 0) {
+		mpool_put(t->bt_mp, h, 0);
+		t->bt_cur = e;
+		*exactp = 1;
+		return (1);
+	}
+	mpool_put(t->bt_mp, e.page, 0);
+	return (0);
+}
diff --git a/db/btree/bt_seq.c b/db/btree/bt_seq.c
new file mode 100644
index 0000000000..303b481903
--- /dev/null
+++ b/db/btree/bt_seq.c
@@ -0,0 +1,460 @@
+/*-
+ * 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_seq.c	8.7 (Berkeley) 7/20/94";
+#endif /* LIBC_SCCS and not lint */
+
+#include <sys/types.h>
+
+#include <errno.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <db.h>
+#include "btree.h"
+
+static int __bt_first __P((BTREE *, const DBT *, EPG *, int *));
+static int __bt_seqadv __P((BTREE *, EPG *, int));
+static int __bt_seqset __P((BTREE *, EPG *, DBT *, int));
+
+/*
+ * Sequential scan support.
+ *
+ * The tree can be scanned sequentially, starting from either end of the
+ * tree or from any specific key.  A scan request before any scanning is
+ * done is initialized as starting from the least node.
+ */
+
+/*
+ * __bt_seq --
+ *	Btree sequential scan interface.
+ *
+ * Parameters:
+ *	dbp:	pointer to access method
+ *	key:	key for positioning and return value
+ *	data:	data return value
+ *	flags:	R_CURSOR, R_FIRST, R_LAST, R_NEXT, R_PREV.
+ *
+ * Returns:
+ *	RET_ERROR, RET_SUCCESS or RET_SPECIAL if there's no next key.
+ */
+int
+__bt_seq(dbp, key, data, flags)
+	const DB *dbp;
+	DBT *key, *data;
+	u_int flags;
+{
+	BTREE *t;
+	EPG e;
+	int status;
+
+	t = dbp->internal;
+
+	/* Toss any page pinned across calls. */
+	if (t->bt_pinned != NULL) {
+		mpool_put(t->bt_mp, t->bt_pinned, 0);
+		t->bt_pinned = NULL;
+	}
+
+	/*
+	 * If scan unitialized as yet, or starting at a specific record, set
+	 * the scan to a specific key.  Both __bt_seqset and __bt_seqadv pin
+	 * the page the cursor references if they're successful.
+	 */
+	switch (flags) {
+	case R_NEXT:
+	case R_PREV:
+		if (F_ISSET(&t->bt_cursor, CURS_INIT)) {
+			status = __bt_seqadv(t, &e, flags);
+			break;
+		}
+		/* FALLTHROUGH */
+	case R_FIRST:
+	case R_LAST:
+	case R_CURSOR:
+		status = __bt_seqset(t, &e, key, flags);
+		break;
+	default:
+		errno = EINVAL;
+		return (RET_ERROR);
+	}
+
+	if (status == RET_SUCCESS) {
+		__bt_setcur(t, e.page->pgno, e.index);
+
+		status =
+		    __bt_ret(t, &e, key, &t->bt_rkey, data, &t->bt_rdata, 0);
+
+		/*
+		 * If the user is doing concurrent access, we copied the
+		 * key/data, toss the page.
+		 */
+		if (F_ISSET(t, B_DB_LOCK))
+			mpool_put(t->bt_mp, e.page, 0);
+		else
+			t->bt_pinned = e.page;
+	}
+	return (status);
+}
+
+/*
+ * __bt_seqset --
+ *	Set the sequential scan to a specific key.
+ *
+ * Parameters:
+ *	t:	tree
+ *	ep:	storage for returned key
+ *	key:	key for initial scan position
+ *	flags:	R_CURSOR, R_FIRST, R_LAST, R_NEXT, R_PREV
+ *
+ * Side effects:
+ *	Pins the page the cursor references.
+ *
+ * Returns:
+ *	RET_ERROR, RET_SUCCESS or RET_SPECIAL if there's no next key.
+ */
+static int
+__bt_seqset(t, ep, key, flags)
+	BTREE *t;
+	EPG *ep;
+	DBT *key;
+	int flags;
+{
+	PAGE *h;
+	pgno_t pg;
+	int exact;
+
+	/*
+	 * Find the first, last or specific key in the tree and point the
+	 * cursor at it.  The cursor may not be moved until a new key has
+	 * been found.
+	 */
+	switch (flags) {
+	case R_CURSOR:				/* Keyed scan. */
+		/*
+		 * Find the first instance of the key or the smallest key
+		 * which is greater than or equal to the specified key.
+		 */
+		if (key->data == NULL || key->size == 0) {
+			errno = EINVAL;
+			return (RET_ERROR);
+		}
+		return (__bt_first(t, key, ep, &exact));
+	case R_FIRST:				/* First record. */
+	case R_NEXT:
+		/* Walk down the left-hand side of the tree. */
+		for (pg = P_ROOT;;) {
+			if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
+				return (RET_ERROR);
+
+			/* Check for an empty tree. */
+			if (NEXTINDEX(h) == 0) {
+				mpool_put(t->bt_mp, h, 0);
+				return (RET_SPECIAL);
+			}
+
+			if (h->flags & (P_BLEAF | P_RLEAF))
+				break;
+			pg = GETBINTERNAL(h, 0)->pgno;
+			mpool_put(t->bt_mp, h, 0);
+		}
+		ep->page = h;
+		ep->index = 0;
+		break;
+	case R_LAST:				/* Last record. */
+	case R_PREV:
+		/* Walk down the right-hand side of the tree. */
+		for (pg = P_ROOT;;) {
+			if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
+				return (RET_ERROR);
+
+			/* Check for an empty tree. */
+			if (NEXTINDEX(h) == 0) {
+				mpool_put(t->bt_mp, h, 0);
+				return (RET_SPECIAL);
+			}
+
+			if (h->flags & (P_BLEAF | P_RLEAF))
+				break;
+			pg = GETBINTERNAL(h, NEXTINDEX(h) - 1)->pgno;
+			mpool_put(t->bt_mp, h, 0);
+		}
+
+		ep->page = h;
+		ep->index = NEXTINDEX(h) - 1;
+		break;
+	}
+	return (RET_SUCCESS);
+}
+
+/*
+ * __bt_seqadvance --
+ *	Advance the sequential scan.
+ *
+ * Parameters:
+ *	t:	tree
+ *	flags:	R_NEXT, R_PREV
+ *
+ * Side effects:
+ *	Pins the page the new key/data record is on.
+ *
+ * Returns:
+ *	RET_ERROR, RET_SUCCESS or RET_SPECIAL if there's no next key.
+ */
+static int
+__bt_seqadv(t, ep, flags)
+	BTREE *t;
+	EPG *ep;
+	int flags;
+{
+	CURSOR *c;
+	PAGE *h;
+	indx_t index;
+	pgno_t pg;
+	int exact;
+
+	/*
+	 * There are a couple of states that we can be in.  The cursor has
+	 * been initialized by the time we get here, but that's all we know.
+	 */
+	c = &t->bt_cursor;
+
+	/*
+	 * The cursor was deleted where there weren't any duplicate records,
+	 * so the key was saved.  Find out where that key would go in the
+	 * current tree.  It doesn't matter if the returned key is an exact
+	 * match or not -- if it's an exact match, the record was added after
+	 * the delete so we can just return it.  If not, as long as there's
+	 * a record there, return it.
+	 */
+	if (F_ISSET(c, CURS_ACQUIRE))
+		return (__bt_first(t, &c->key, ep, &exact));
+
+	/* Get the page referenced by the cursor. */
+	if ((h = mpool_get(t->bt_mp, c->pg.pgno, 0)) == NULL)
+		return (RET_ERROR);
+
+	/*
+ 	 * Find the next/previous record in the tree and point the cursor at
+	 * it.  The cursor may not be moved until a new key has been found.
+	 */
+	switch (flags) {
+	case R_NEXT:			/* Next record. */
+		/*
+		 * The cursor was deleted in duplicate records, and moved
+		 * forward to a record that has yet to be returned.  Clear
+		 * that flag, and return the record.
+		 */
+		if (F_ISSET(c, CURS_AFTER))
+			goto usecurrent;
+		index = c->pg.index;
+		if (++index == NEXTINDEX(h)) {
+			pg = h->nextpg;
+			mpool_put(t->bt_mp, h, 0);
+			if (pg == P_INVALID)
+				return (RET_SPECIAL);
+			if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
+				return (RET_ERROR);
+			index = 0;
+		}
+		break;
+	case R_PREV:			/* Previous record. */
+		/*
+		 * The cursor was deleted in duplicate records, and moved
+		 * backward to a record that has yet to be returned.  Clear
+		 * that flag, and return the record.
+		 */
+		if (F_ISSET(c, CURS_BEFORE)) {
+usecurrent:		F_CLR(c, CURS_AFTER | CURS_BEFORE);
+			ep->page = h;
+			ep->index = c->pg.index;
+			return (RET_SUCCESS);
+		}
+		index = c->pg.index;
+		if (index == 0) {
+			pg = h->prevpg;
+			mpool_put(t->bt_mp, h, 0);
+			if (pg == P_INVALID)
+				return (RET_SPECIAL);
+			if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
+				return (RET_ERROR);
+			index = NEXTINDEX(h) - 1;
+		} else
+			--index;
+		break;
+	}
+
+	ep->page = h;
+	ep->index = index;
+	return (RET_SUCCESS);
+}
+
+/*
+ * __bt_first --
+ *	Find the first entry.
+ *
+ * Parameters:
+ *	t:	the tree
+ *    key:	the key
+ *  erval:	return EPG
+ * exactp:	pointer to exact match flag
+ *
+ * Returns:
+ *	The first entry in the tree greater than or equal to key,
+ *	or RET_SPECIAL if no such key exists.
+ */
+static int
+__bt_first(t, key, erval, exactp)
+	BTREE *t;
+	const DBT *key;
+	EPG *erval;
+	int *exactp;
+{
+	PAGE *h;
+	EPG *ep, save;
+	pgno_t pg;
+
+	/*
+	 * Find any matching record; __bt_search pins the page.
+	 *
+	 * If it's an exact match and duplicates are possible, walk backwards
+	 * in the tree until we find the first one.  Otherwise, make sure it's
+	 * a valid key (__bt_search may return an index just past the end of a
+	 * page) and return it.
+	 */
+	if ((ep = __bt_search(t, key, exactp)) == NULL)
+		return (NULL);
+	if (*exactp) {
+		if (F_ISSET(t, B_NODUPS)) {
+			*erval = *ep;
+			return (RET_SUCCESS);
+		}
+			
+		/*
+		 * Walk backwards, as long as the entry matches and there are
+		 * keys left in the tree.  Save a copy of each match in case
+		 * we go too far.
+		 */
+		save = *ep;
+		h = ep->page;
+		do {
+			if (save.page->pgno != ep->page->pgno) {
+				mpool_put(t->bt_mp, save.page, 0);
+				save = *ep;
+			} else
+				save.index = ep->index;
+
+			/*
+			 * Don't unpin the page the last (or original) match
+			 * was on, but make sure it's unpinned if an error
+			 * occurs.
+			 */
+			if (ep->index == 0) {
+				if (h->prevpg == P_INVALID)
+					break;
+				if (h->pgno != save.page->pgno)
+					mpool_put(t->bt_mp, h, 0);
+				if ((h = mpool_get(t->bt_mp,
+				    h->prevpg, 0)) == NULL) {
+					if (h->pgno == save.page->pgno)
+						mpool_put(t->bt_mp,
+						    save.page, 0);
+					return (RET_ERROR);
+				}
+				ep->page = h;
+				ep->index = NEXTINDEX(h);
+			}
+			--ep->index;
+		} while (__bt_cmp(t, key, ep) == 0);
+
+		/*
+		 * Reach here with the last page that was looked at pinned,
+		 * which may or may not be the same as the last (or original)
+		 * match page.  If it's not useful, release it.
+		 */
+		if (h->pgno != save.page->pgno)
+			mpool_put(t->bt_mp, h, 0);
+
+		*erval = save;
+		return (RET_SUCCESS);
+	}
+
+	/* If at the end of a page, find the next entry. */
+	if (ep->index == NEXTINDEX(ep->page)) {
+		h = ep->page;
+		pg = h->nextpg;
+		mpool_put(t->bt_mp, h, 0);
+		if (pg == P_INVALID)
+			return (RET_SPECIAL);
+		if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL)
+			return (RET_ERROR);
+		ep->index = 0;
+		ep->page = h;
+	}
+	*erval = *ep;
+	return (RET_SUCCESS);
+}
+
+/*
+ * __bt_setcur --
+ *	Set the cursor to an entry in the tree.
+ *
+ * Parameters:
+ *	t:	the tree
+ *   pgno:	page number
+ *  index:	page index
+ */
+void
+__bt_setcur(t, pgno, index)
+	BTREE *t;
+	pgno_t pgno;
+	u_int index;
+{
+	/* Lose any already deleted key. */
+	if (t->bt_cursor.key.data != NULL) {
+		free(t->bt_cursor.key.data);
+		t->bt_cursor.key.size = 0;
+		t->bt_cursor.key.data = NULL;
+	}
+	F_CLR(&t->bt_cursor, CURS_ACQUIRE | CURS_AFTER | CURS_BEFORE);
+
+	/* Update the cursor. */
+	t->bt_cursor.pg.pgno = pgno;
+	t->bt_cursor.pg.index = index;
+	F_SET(&t->bt_cursor, CURS_INIT);
+}
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);
+}
diff --git a/db/btree/bt_utils.c b/db/btree/bt_utils.c
new file mode 100644
index 0000000000..9c1438eb84
--- /dev/null
+++ b/db/btree/bt_utils.c
@@ -0,0 +1,260 @@
+/*-
+ * 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_utils.c	8.8 (Berkeley) 7/20/94";
+#endif /* LIBC_SCCS and not lint */
+
+#include <sys/param.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <db.h>
+#include "btree.h"
+
+/*
+ * __bt_ret --
+ *	Build return key/data pair.
+ *
+ * Parameters:
+ *	t:	tree
+ *	e:	key/data pair to be returned
+ *	key:	user's key structure (NULL if not to be filled in)
+ *	rkey:	memory area to hold key
+ *	data:	user's data structure (NULL if not to be filled in)
+ *	rdata:	memory area to hold data
+ *       copy:	always copy the key/data item
+ *
+ * Returns:
+ *	RET_SUCCESS, RET_ERROR.
+ */
+int
+__bt_ret(t, e, key, rkey, data, rdata, copy)
+	BTREE *t;
+	EPG *e;
+	DBT *key, *rkey, *data, *rdata;
+	int copy;
+{
+	BLEAF *bl;
+	void *p;
+
+	bl = GETBLEAF(e->page, e->index);
+
+	/*
+	 * We must copy big keys/data to make them contigous.  Otherwise,
+	 * leave the page pinned and don't copy unless the user specified
+	 * concurrent access.
+	 */
+	if (key == NULL)
+		goto dataonly;
+
+	if (bl->flags & P_BIGKEY) {
+		if (__ovfl_get(t, bl->bytes,
+		    &key->size, &rkey->data, &rkey->size))
+			return (RET_ERROR);
+		key->data = rkey->data;
+	} else if (copy || F_ISSET(t, B_DB_LOCK)) {
+		if (bl->ksize > rkey->size) {
+			p = (void *)(rkey->data == NULL ?
+			    malloc(bl->ksize) : realloc(rkey->data, bl->ksize));
+			if (p == NULL)
+				return (RET_ERROR);
+			rkey->data = p;
+			rkey->size = bl->ksize;
+		}
+		memmove(rkey->data, bl->bytes, bl->ksize);
+		key->size = bl->ksize;
+		key->data = rkey->data;
+	} else {
+		key->size = bl->ksize;
+		key->data = bl->bytes;
+	}
+
+dataonly:
+	if (data == NULL)
+		return (RET_SUCCESS);
+
+	if (bl->flags & P_BIGDATA) {
+		if (__ovfl_get(t, bl->bytes + bl->ksize,
+		    &data->size, &rdata->data, &rdata->size))
+			return (RET_ERROR);
+		data->data = rdata->data;
+	} else if (copy || F_ISSET(t, B_DB_LOCK)) {
+		/* Use +1 in case the first record retrieved is 0 length. */
+		if (bl->dsize + 1 > rdata->size) {
+			p = (void *)(rdata->data == NULL ?
+			    malloc(bl->dsize + 1) :
+			    realloc(rdata->data, bl->dsize + 1));
+			if (p == NULL)
+				return (RET_ERROR);
+			rdata->data = p;
+			rdata->size = bl->dsize + 1;
+		}
+		memmove(rdata->data, bl->bytes + bl->ksize, bl->dsize);
+		data->size = bl->dsize;
+		data->data = rdata->data;
+	} else {
+		data->size = bl->dsize;
+		data->data = bl->bytes + bl->ksize;
+	}
+
+	return (RET_SUCCESS);
+}
+
+/*
+ * __BT_CMP -- Compare a key to a given record.
+ *
+ * Parameters:
+ *	t:	tree
+ *	k1:	DBT pointer of first arg to comparison
+ *	e:	pointer to EPG for comparison
+ *
+ * Returns:
+ *	< 0 if k1 is < record
+ *	= 0 if k1 is = record
+ *	> 0 if k1 is > record
+ */
+int
+__bt_cmp(t, k1, e)
+	BTREE *t;
+	const DBT *k1;
+	EPG *e;
+{
+	BINTERNAL *bi;
+	BLEAF *bl;
+	DBT k2;
+	PAGE *h;
+	void *bigkey;
+
+	/*
+	 * The left-most key on internal pages, at any level of the tree, is
+	 * guaranteed by the following code to be less than any user key.
+	 * This saves us from having to update the leftmost key on an internal
+	 * page when the user inserts a new key in the tree smaller than
+	 * anything we've yet seen.
+	 */
+	h = e->page;
+	if (e->index == 0 && h->prevpg == P_INVALID && !(h->flags & P_BLEAF))
+		return (1);
+
+	bigkey = NULL;
+	if (h->flags & P_BLEAF) {
+		bl = GETBLEAF(h, e->index);
+		if (bl->flags & P_BIGKEY)
+			bigkey = bl->bytes;
+		else {
+			k2.data = bl->bytes;
+			k2.size = bl->ksize;
+		}
+	} else {
+		bi = GETBINTERNAL(h, e->index);
+		if (bi->flags & P_BIGKEY)
+			bigkey = bi->bytes;
+		else {
+			k2.data = bi->bytes;
+			k2.size = bi->ksize;
+		}
+	}
+
+	if (bigkey) {
+		if (__ovfl_get(t, bigkey,
+		    &k2.size, &t->bt_rdata.data, &t->bt_rdata.size))
+			return (RET_ERROR);
+		k2.data = t->bt_rdata.data;
+	}
+	return ((*t->bt_cmp)(k1, &k2));
+}
+
+/*
+ * __BT_DEFCMP -- Default comparison routine.
+ *
+ * Parameters:
+ *	a:	DBT #1
+ *	b: 	DBT #2
+ *
+ * Returns:
+ *	< 0 if a is < b
+ *	= 0 if a is = b
+ *	> 0 if a is > b
+ */
+int
+__bt_defcmp(a, b)
+	const DBT *a, *b;
+{
+	register size_t len;
+	register u_char *p1, *p2;
+
+	/*
+	 * XXX
+	 * If a size_t doesn't fit in an int, this routine can lose.
+	 * What we need is a integral type which is guaranteed to be
+	 * larger than a size_t, and there is no such thing.
+	 */
+	len = MIN(a->size, b->size);
+	for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2)
+		if (*p1 != *p2)
+			return ((int)*p1 - (int)*p2);
+	return ((int)a->size - (int)b->size);
+}
+
+/*
+ * __BT_DEFPFX -- Default prefix routine.
+ *
+ * Parameters:
+ *	a:	DBT #1
+ *	b: 	DBT #2
+ *
+ * Returns:
+ *	Number of bytes needed to distinguish b from a.
+ */
+size_t
+__bt_defpfx(a, b)
+	const DBT *a, *b;
+{
+	register u_char *p1, *p2;
+	register size_t cnt, len;
+
+	cnt = 1;
+	len = MIN(a->size, b->size);
+	for (p1 = a->data, p2 = b->data; len--; ++p1, ++p2, ++cnt)
+		if (*p1 != *p2)
+			return (cnt);
+
+	/* a->size must be <= b->size, or they wouldn't be in this order. */
+	return (a->size < b->size ? a->size + 1 : a->size);
+}
diff --git a/db/btree/btree.h b/db/btree/btree.h
new file mode 100644
index 0000000000..36d35c998b
--- /dev/null
+++ b/db/btree/btree.h
@@ -0,0 +1,383 @@
+/*-
+ * Copyright (c) 1991, 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.
+ *
+ *	@(#)btree.h	8.11 (Berkeley) 8/17/94
+ */
+
+/* Macros to set/clear/test flags. */
+#define	F_SET(p, f)	(p)->flags |= (f)
+#define	F_CLR(p, f)	(p)->flags &= ~(f)
+#define	F_ISSET(p, f)	((p)->flags & (f))
+
+#include <mpool.h>
+
+#define	DEFMINKEYPAGE	(2)		/* Minimum keys per page */
+#define	MINCACHE	(5)		/* Minimum cached pages */
+#define	MINPSIZE	(512)		/* Minimum page size */
+
+/*
+ * Page 0 of a btree file contains a copy of the meta-data.  This page is also
+ * used as an out-of-band page, i.e. page pointers that point to nowhere point
+ * to page 0.  Page 1 is the root of the btree.
+ */
+#define	P_INVALID	 0		/* Invalid tree page number. */
+#define	P_META		 0		/* Tree metadata page number. */
+#define	P_ROOT		 1		/* Tree root page number. */
+
+/*
+ * There are five page layouts in the btree: btree internal pages (BINTERNAL),
+ * btree leaf pages (BLEAF), recno internal pages (RINTERNAL), recno leaf pages
+ * (RLEAF) and overflow pages.  All five page types have a page header (PAGE).
+ * This implementation requires that values within structures NOT be padded.
+ * (ANSI C permits random padding.)  If your compiler pads randomly you'll have
+ * to do some work to get this package to run.
+ */
+typedef struct _page {
+	pgno_t	pgno;			/* this page's page number */
+	pgno_t	prevpg;			/* left sibling */
+	pgno_t	nextpg;			/* right sibling */
+
+#define	P_BINTERNAL	0x01		/* btree internal page */
+#define	P_BLEAF		0x02		/* leaf page */
+#define	P_OVERFLOW	0x04		/* overflow page */
+#define	P_RINTERNAL	0x08		/* recno internal page */
+#define	P_RLEAF		0x10		/* leaf page */
+#define P_TYPE		0x1f		/* type mask */
+#define	P_PRESERVE	0x20		/* never delete this chain of pages */
+	u_int32_t flags;
+
+	indx_t	lower;			/* lower bound of free space on page */
+	indx_t	upper;			/* upper bound of free space on page */
+	indx_t	linp[1];		/* indx_t-aligned VAR. LENGTH DATA */
+} PAGE;
+
+/* First and next index. */
+#define	BTDATAOFF							\
+	(sizeof(pgno_t) + sizeof(pgno_t) + sizeof(pgno_t) +		\
+	    sizeof(u_int32_t) + sizeof(indx_t) + sizeof(indx_t))
+#define	NEXTINDEX(p)	(((p)->lower - BTDATAOFF) / sizeof(indx_t))
+
+/*
+ * For pages other than overflow pages, there is an array of offsets into the
+ * rest of the page immediately following the page header.  Each offset is to
+ * an item which is unique to the type of page.  The h_lower offset is just
+ * past the last filled-in index.  The h_upper offset is the first item on the
+ * page.  Offsets are from the beginning of the page.
+ *
+ * If an item is too big to store on a single page, a flag is set and the item
+ * is a { page, size } pair such that the page is the first page of an overflow
+ * chain with size bytes of item.  Overflow pages are simply bytes without any
+ * external structure.
+ *
+ * The page number and size fields in the items are pgno_t-aligned so they can
+ * be manipulated without copying.  (This presumes that 32 bit items can be
+ * manipulated on this system.)
+ */
+#define	LALIGN(n)	(((n) + sizeof(pgno_t) - 1) & ~(sizeof(pgno_t) - 1))
+#define	NOVFLSIZE	(sizeof(pgno_t) + sizeof(u_int32_t))
+
+/*
+ * For the btree internal pages, the item is a key.  BINTERNALs are {key, pgno}
+ * pairs, such that the key compares less than or equal to all of the records
+ * on that page.  For a tree without duplicate keys, an internal page with two
+ * consecutive keys, a and b, will have all records greater than or equal to a
+ * and less than b stored on the page associated with a.  Duplicate keys are
+ * somewhat special and can cause duplicate internal and leaf page records and
+ * some minor modifications of the above rule.
+ */
+typedef struct _binternal {
+	u_int32_t ksize;		/* key size */
+	pgno_t	pgno;			/* page number stored on */
+#define	P_BIGDATA	0x01		/* overflow data */
+#define	P_BIGKEY	0x02		/* overflow key */
+	u_char	flags;
+	char	bytes[1];		/* data */
+} BINTERNAL;
+
+/* Get the page's BINTERNAL structure at index indx. */
+#define	GETBINTERNAL(pg, indx)						\
+	((BINTERNAL *)((char *)(pg) + (pg)->linp[indx]))
+
+/* Get the number of bytes in the entry. */
+#define NBINTERNAL(len)							\
+	LALIGN(sizeof(u_int32_t) + sizeof(pgno_t) + sizeof(u_char) + (len))
+
+/* Copy a BINTERNAL entry to the page. */
+#define	WR_BINTERNAL(p, size, pgno, flags) {				\
+	*(u_int32_t *)p = size;						\
+	p += sizeof(u_int32_t);						\
+	*(pgno_t *)p = pgno;						\
+	p += sizeof(pgno_t);						\
+	*(u_char *)p = flags;						\
+	p += sizeof(u_char);						\
+}
+
+/*
+ * For the recno internal pages, the item is a page number with the number of
+ * keys found on that page and below.
+ */
+typedef struct _rinternal {
+	recno_t	nrecs;			/* number of records */
+	pgno_t	pgno;			/* page number stored below */
+} RINTERNAL;
+
+/* Get the page's RINTERNAL structure at index indx. */
+#define	GETRINTERNAL(pg, indx)						\
+	((RINTERNAL *)((char *)(pg) + (pg)->linp[indx]))
+
+/* Get the number of bytes in the entry. */
+#define NRINTERNAL							\
+	LALIGN(sizeof(recno_t) + sizeof(pgno_t))
+
+/* Copy a RINTERAL entry to the page. */
+#define	WR_RINTERNAL(p, nrecs, pgno) {					\
+	*(recno_t *)p = nrecs;						\
+	p += sizeof(recno_t);						\
+	*(pgno_t *)p = pgno;						\
+}
+
+/* For the btree leaf pages, the item is a key and data pair. */
+typedef struct _bleaf {
+	u_int32_t	ksize;		/* size of key */
+	u_int32_t	dsize;		/* size of data */
+	u_char	flags;			/* P_BIGDATA, P_BIGKEY */
+	char	bytes[1];		/* data */
+} BLEAF;
+
+/* Get the page's BLEAF structure at index indx. */
+#define	GETBLEAF(pg, indx)						\
+	((BLEAF *)((char *)(pg) + (pg)->linp[indx]))
+
+/* Get the number of bytes in the entry. */
+#define NBLEAF(p)	NBLEAFDBT((p)->ksize, (p)->dsize)
+
+/* Get the number of bytes in the user's key/data pair. */
+#define NBLEAFDBT(ksize, dsize)						\
+	LALIGN(sizeof(u_int32_t) + sizeof(u_int32_t) + sizeof(u_char) +	\
+	    (ksize) + (dsize))
+
+/* Copy a BLEAF entry to the page. */
+#define	WR_BLEAF(p, key, data, flags) {					\
+	*(u_int32_t *)p = key->size;					\
+	p += sizeof(u_int32_t);						\
+	*(u_int32_t *)p = data->size;					\
+	p += sizeof(u_int32_t);						\
+	*(u_char *)p = flags;						\
+	p += sizeof(u_char);						\
+	memmove(p, key->data, key->size);				\
+	p += key->size;							\
+	memmove(p, data->data, data->size);				\
+}
+
+/* For the recno leaf pages, the item is a data entry. */
+typedef struct _rleaf {
+	u_int32_t	dsize;		/* size of data */
+	u_char	flags;			/* P_BIGDATA */
+	char	bytes[1];
+} RLEAF;
+
+/* Get the page's RLEAF structure at index indx. */
+#define	GETRLEAF(pg, indx)						\
+	((RLEAF *)((char *)(pg) + (pg)->linp[indx]))
+
+/* Get the number of bytes in the entry. */
+#define NRLEAF(p)	NRLEAFDBT((p)->dsize)
+
+/* Get the number of bytes from the user's data. */
+#define	NRLEAFDBT(dsize)						\
+	LALIGN(sizeof(u_int32_t) + sizeof(u_char) + (dsize))
+
+/* Copy a RLEAF entry to the page. */
+#define	WR_RLEAF(p, data, flags) {					\
+	*(u_int32_t *)p = data->size;					\
+	p += sizeof(u_int32_t);						\
+	*(u_char *)p = flags;						\
+	p += sizeof(u_char);						\
+	memmove(p, data->data, data->size);				\
+}
+
+/*
+ * A record in the tree is either a pointer to a page and an index in the page
+ * or a page number and an index.  These structures are used as a cursor, stack
+ * entry and search returns as well as to pass records to other routines.
+ *
+ * One comment about searches.  Internal page searches must find the largest
+ * record less than key in the tree so that descents work.  Leaf page searches
+ * must find the smallest record greater than key so that the returned index
+ * is the record's correct position for insertion.
+ */
+typedef struct _epgno {
+	pgno_t	pgno;			/* the page number */
+	indx_t	index;			/* the index on the page */
+} EPGNO;
+
+typedef struct _epg {
+	PAGE	*page;			/* the (pinned) page */
+	indx_t	 index;			/* the index on the page */
+} EPG;
+
+/*
+ * About cursors.  The cursor (and the page that contained the key/data pair
+ * that it referenced) can be deleted, which makes things a bit tricky.  If
+ * there are no duplicates of the cursor key in the tree (i.e. B_NODUPS is set
+ * or there simply aren't any duplicates of the key) we copy the key that it
+ * referenced when it's deleted, and reacquire a new cursor key if the cursor
+ * is used again.  If there are duplicates keys, we move to the next/previous
+ * key, and set a flag so that we know what happened.  NOTE: if duplicate (to
+ * the cursor) keys are added to the tree during this process, it is undefined
+ * if they will be returned or not in a cursor scan.
+ *
+ * The flags determine the possible states of the cursor:
+ *
+ * CURS_INIT	The cursor references *something*.
+ * CURS_ACQUIRE	The cursor was deleted, and a key has been saved so that
+ *		we can reacquire the right position in the tree.
+ * CURS_AFTER, CURS_BEFORE
+ *		The cursor was deleted, and now references a key/data pair
+ *		that has not yet been returned, either before or after the
+ *		deleted key/data pair.
+ * XXX
+ * This structure is broken out so that we can eventually offer multiple
+ * cursors as part of the DB interface.
+ */
+typedef struct _cursor {
+	EPGNO	 pg;			/* B: Saved tree reference. */
+	DBT	 key;			/* B: Saved key, or key.data == NULL. */
+	recno_t	 rcursor;		/* R: recno cursor (1-based) */
+
+#define	CURS_ACQUIRE	0x01		/*  B: Cursor needs to be reacquired. */
+#define	CURS_AFTER	0x02		/*  B: Unreturned cursor after key. */
+#define	CURS_BEFORE	0x04		/*  B: Unreturned cursor before key. */
+#define	CURS_INIT	0x08		/* RB: Cursor initialized. */
+	u_int8_t flags;
+} CURSOR;
+
+/*
+ * The metadata of the tree.  The nrecs field is used only by the RECNO code.
+ * This is because the btree doesn't really need it and it requires that every
+ * put or delete call modify the metadata.
+ */
+typedef struct _btmeta {
+	u_int32_t	magic;		/* magic number */
+	u_int32_t	version;	/* version */
+	u_int32_t	psize;		/* page size */
+	u_int32_t	free;		/* page number of first free page */
+	u_int32_t	nrecs;		/* R: number of records */
+
+#define	SAVEMETA	(B_NODUPS | R_RECNO)
+	u_int32_t	flags;		/* bt_flags & SAVEMETA */
+} BTMETA;
+
+/* The in-memory btree/recno data structure. */
+typedef struct _btree {
+	MPOOL	 *bt_mp;		/* memory pool cookie */
+
+	DB	 *bt_dbp;		/* pointer to enclosing DB */
+
+	EPG	  bt_cur;		/* current (pinned) page */
+	PAGE	 *bt_pinned;		/* page pinned across calls */
+
+	CURSOR	  bt_cursor;		/* cursor */
+
+#define	BT_PUSH(t, p, i) {						\
+	t->bt_sp->pgno = p; 						\
+	t->bt_sp->index = i; 						\
+	++t->bt_sp;							\
+}
+#define	BT_POP(t)	(t->bt_sp == t->bt_stack ? NULL : --t->bt_sp)
+#define	BT_CLR(t)	(t->bt_sp = t->bt_stack)
+	EPGNO	  bt_stack[50];		/* stack of parent pages */
+	EPGNO	 *bt_sp;		/* current stack pointer */
+
+	DBT	  bt_rkey;		/* returned key */
+	DBT	  bt_rdata;		/* returned data */
+
+	int	  bt_fd;		/* tree file descriptor */
+
+	pgno_t	  bt_free;		/* next free page */
+	u_int32_t bt_psize;		/* page size */
+	indx_t	  bt_ovflsize;		/* cut-off for key/data overflow */
+	int	  bt_lorder;		/* byte order */
+					/* sorted order */
+	enum { NOT, BACK, FORWARD } bt_order;
+	EPGNO	  bt_last;		/* last insert */
+
+					/* B: key comparison function */
+	int	(*bt_cmp) __P((const DBT *, const DBT *));
+					/* B: prefix comparison function */
+	size_t	(*bt_pfx) __P((const DBT *, const DBT *));
+					/* R: recno input function */
+	int	(*bt_irec) __P((struct _btree *, recno_t));
+
+	FILE	 *bt_rfp;		/* R: record FILE pointer */
+	int	  bt_rfd;		/* R: record file descriptor */
+
+	caddr_t	  bt_cmap;		/* R: current point in mapped space */
+	caddr_t	  bt_smap;		/* R: start of mapped space */
+	caddr_t   bt_emap;		/* R: end of mapped space */
+	size_t	  bt_msize;		/* R: size of mapped region. */
+
+	recno_t	  bt_nrecs;		/* R: number of records */
+	size_t	  bt_reclen;		/* R: fixed record length */
+	u_char	  bt_bval;		/* R: delimiting byte/pad character */
+
+/*
+ * NB:
+ * B_NODUPS and R_RECNO are stored on disk, and may not be changed.
+ */
+#define	B_INMEM		0x00001		/* in-memory tree */
+#define	B_METADIRTY	0x00002		/* need to write metadata */
+#define	B_MODIFIED	0x00004		/* tree modified */
+#define	B_NEEDSWAP	0x00008		/* if byte order requires swapping */
+#define	B_RDONLY	0x00010		/* read-only tree */
+
+#define	B_NODUPS	0x00020		/* no duplicate keys permitted */
+#define	R_RECNO		0x00080		/* record oriented tree */
+
+#define	R_CLOSEFP	0x00040		/* opened a file pointer */
+#define	R_EOF		0x00100		/* end of input file reached. */
+#define	R_FIXLEN	0x00200		/* fixed length records */
+#define	R_MEMMAPPED	0x00400		/* memory mapped file. */
+#define	R_INMEM		0x00800		/* in-memory file */
+#define	R_MODIFIED	0x01000		/* modified file */
+#define	R_RDONLY	0x02000		/* read-only file */
+
+#define	B_DB_LOCK	0x04000		/* DB_LOCK specified. */
+#define	B_DB_SHMEM	0x08000		/* DB_SHMEM specified. */
+#define	B_DB_TXN	0x10000		/* DB_TXN specified. */
+	u_int32_t flags;
+} BTREE;
+
+#include "extern.h"
diff --git a/db/btree/extern.h b/db/btree/extern.h
new file mode 100644
index 0000000000..ebd9c54923
--- /dev/null
+++ b/db/btree/extern.h
@@ -0,0 +1,70 @@
+/*-
+ * Copyright (c) 1991, 1993, 1994
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * 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.
+ *
+ *	@(#)extern.h	8.10 (Berkeley) 7/20/94
+ */
+
+int	 __bt_close __P((DB *));
+int	 __bt_cmp __P((BTREE *, const DBT *, EPG *));
+int	 __bt_crsrdel __P((BTREE *, EPGNO *));
+int	 __bt_defcmp __P((const DBT *, const DBT *));
+size_t	 __bt_defpfx __P((const DBT *, const DBT *));
+int	 __bt_delete __P((const DB *, const DBT *, u_int));
+int	 __bt_dleaf __P((BTREE *, const DBT *, PAGE *, u_int));
+int	 __bt_fd __P((const DB *));
+int	 __bt_free __P((BTREE *, PAGE *));
+int	 __bt_get __P((const DB *, const DBT *, DBT *, u_int));
+PAGE	*__bt_new __P((BTREE *, pgno_t *));
+void	 __bt_pgin __P((void *, pgno_t, void *));
+void	 __bt_pgout __P((void *, pgno_t, void *));
+int	 __bt_push __P((BTREE *, pgno_t, int));
+int	 __bt_put __P((const DB *dbp, DBT *, const DBT *, u_int));
+int	 __bt_ret __P((BTREE *, EPG *, DBT *, DBT *, DBT *, DBT *, int));
+EPG	*__bt_search __P((BTREE *, const DBT *, int *));
+int	 __bt_seq __P((const DB *, DBT *, DBT *, u_int));
+void	 __bt_setcur __P((BTREE *, pgno_t, u_int));
+int	 __bt_split __P((BTREE *, PAGE *,
+	    const DBT *, const DBT *, int, size_t, u_int32_t));
+int	 __bt_sync __P((const DB *, u_int));
+
+int	 __ovfl_delete __P((BTREE *, void *));
+int	 __ovfl_get __P((BTREE *, void *, size_t *, void **, size_t *));
+int	 __ovfl_put __P((BTREE *, const DBT *, pgno_t *));
+
+#ifdef DEBUG
+void	 __bt_dnpage __P((DB *, pgno_t));
+void	 __bt_dpage __P((PAGE *));
+void	 __bt_dump __P((DB *));
+#endif
+#ifdef STATISTICS
+void	 __bt_stat __P((DB *));
+#endif