diff --git a/libraries/liblmdb/COPYRIGHT b/libraries/liblmdb/COPYRIGHT
index 4482816cf5..e0eb484c7a 100644
--- a/libraries/liblmdb/COPYRIGHT
+++ b/libraries/liblmdb/COPYRIGHT
@@ -1,4 +1,4 @@
-Copyright 2011-2013 Howard Chu, Symas Corp.
+Copyright 2011-2014 Howard Chu, Symas Corp.
 All rights reserved.
 
 Redistribution and use in source and binary forms, with or without
diff --git a/libraries/liblmdb/lmdb.h b/libraries/liblmdb/lmdb.h
index 62f0a485de..7a38a29cbb 100644
--- a/libraries/liblmdb/lmdb.h
+++ b/libraries/liblmdb/lmdb.h
@@ -408,7 +408,7 @@ typedef enum MDB_cursor_op {
 #define MDB_BAD_RSLOT		(-30783)
 	/** Transaction cannot recover - it must be aborted */
 #define MDB_BAD_TXN			(-30782)
-	/** Too big key/data, key is empty, or wrong DUPFIXED size */
+	/** Unsupported size of key/DB name/data, or wrong DUPFIXED size */
 #define MDB_BAD_VALSIZE		(-30781)
 #define MDB_LAST_ERRCODE	MDB_BAD_VALSIZE
 /** @} */
@@ -784,6 +784,10 @@ int  mdb_env_get_maxreaders(MDB_env *env, unsigned int *readers);
 	 * environment. Simpler applications that use the environment as a single
 	 * unnamed database can ignore this option.
 	 * This function may only be called after #mdb_env_create() and before #mdb_env_open().
+	 *
+	 * Currently a moderate number of slots are cheap but a huge number gets
+	 * expensive: 7-120 words per transaction, and every #mdb_dbi_open()
+	 * does a linear search of the opened slots.
 	 * @param[in] env An environment handle returned by #mdb_env_create()
 	 * @param[in] dbs The maximum number of databases
 	 * @return A non-zero error value on failure and 0 on success. Some possible
@@ -951,7 +955,7 @@ int  mdb_txn_renew(MDB_txn *txn);
 	 * independently of whether such a database exists.
 	 * The database handle may be discarded by calling #mdb_dbi_close().
 	 * The old database handle is returned if the database was already open.
-	 * The handle must only be closed once.
+	 * The handle may only be closed once.
 	 * The database handle will be private to the current transaction until
 	 * the transaction is successfully committed. If the transaction is
 	 * aborted the handle will be closed automatically.
@@ -963,7 +967,8 @@ int  mdb_txn_renew(MDB_txn *txn);
 	 * use this function.
 	 *
 	 * To use named databases (with name != NULL), #mdb_env_set_maxdbs()
-	 * must be called before opening the environment.
+	 * must be called before opening the environment.  Database names
+	 * are kept as keys in the unnamed database.
 	 * @param[in] txn A transaction handle returned by #mdb_txn_begin()
 	 * @param[in] name The name of the database to open. If only a single
 	 * 	database is needed in the environment, this value may be NULL.
@@ -1033,12 +1038,19 @@ int  mdb_stat(MDB_txn *txn, MDB_dbi dbi, MDB_stat *stat);
 	 */
 int mdb_dbi_flags(MDB_txn *txn, MDB_dbi dbi, unsigned int *flags);
 
-	/** @brief Close a database handle.
+	/** @brief Close a database handle. Normally unnecessary. Use with care:
 	 *
 	 * This call is not mutex protected. Handles should only be closed by
 	 * a single thread, and only if no other threads are going to reference
 	 * the database handle or one of its cursors any further. Do not close
 	 * a handle if an existing transaction has modified its database.
+	 * Doing so can cause misbehavior from database corruption to errors
+	 * like MDB_BAD_VALSIZE (since the DB name is gone).
+	 *
+	 * Closing a database handle is not necessary, but lets #mdb_dbi_open()
+	 * reuse the handle value.  Usually it's better to set a bigger
+	 * #mdb_env_set_maxdbs(), unless that value would be large.
+	 *
 	 * @param[in] env An environment handle returned by #mdb_env_create()
 	 * @param[in] dbi A database handle returned by #mdb_dbi_open()
 	 */
@@ -1046,6 +1058,7 @@ void mdb_dbi_close(MDB_env *env, MDB_dbi dbi);
 
 	/** @brief Empty or delete+close a database.
 	 *
+	 * See #mdb_dbi_close() for restrictions about closing the DB handle.
 	 * @param[in] txn A transaction handle returned by #mdb_txn_begin()
 	 * @param[in] dbi A database handle returned by #mdb_dbi_open()
 	 * @param[in] del 0 to empty the DB, 1 to delete it from the
@@ -1323,9 +1336,9 @@ int  mdb_cursor_get(MDB_cursor *cursor, MDB_val *key, MDB_val *data,
 	/** @brief Store by cursor.
 	 *
 	 * This function stores key/data pairs into the database.
-	 * If the function fails for any reason, the state of the cursor will be
-	 * unchanged. If the function succeeds and an item is inserted into the
-	 * database, the cursor is always positioned to refer to the newly inserted item.
+	 * The cursor is positioned at the new item, or on failure usually near it.
+	 * @note Earlier documentation incorrectly said errors would leave the
+	 * state of the cursor unchanged.
 	 * @param[in] cursor A cursor handle returned by #mdb_cursor_open()
 	 * @param[in] key The key operated on.
 	 * @param[in] data The data operated on.
@@ -1334,7 +1347,9 @@ int  mdb_cursor_get(MDB_cursor *cursor, MDB_val *key, MDB_val *data,
 	 * <ul>
 	 *	<li>#MDB_CURRENT - overwrite the data of the key/data pair to which
 	 *		the cursor refers with the specified data item. The \b key
-	 *		parameter is ignored.  The \b data size must match the original.
+	 *		parameter is not used for positioning the cursor, but should
+	 *		still be provided. If using sorted duplicates (#MDB_DUPSORT)
+	 *		the data item must still sort into the same place.
 	 *	<li>#MDB_NODUPDATA - enter the new key/data pair only if it does not
 	 *		already appear in the database. This flag may only be specified
 	 *		if the database was opened with #MDB_DUPSORT. The function will
diff --git a/libraries/liblmdb/mdb.c b/libraries/liblmdb/mdb.c
index 71b025fa68..4377ee8ea6 100644
--- a/libraries/liblmdb/mdb.c
+++ b/libraries/liblmdb/mdb.c
@@ -1202,7 +1202,7 @@ static char *const mdb_errstr[] = {
 	"MDB_INCOMPATIBLE: Operation and DB incompatible, or DB flags changed",
 	"MDB_BAD_RSLOT: Invalid reuse of reader locktable slot",
 	"MDB_BAD_TXN: Transaction cannot recover - it must be aborted",
-	"MDB_BAD_VALSIZE: Too big key/data, key is empty, or wrong DUPFIXED size",
+	"MDB_BAD_VALSIZE: Unsupported size of key/DB name/data, or wrong DUPFIXED size",
 };
 
 char *
@@ -2770,23 +2770,20 @@ mdb_freelist_save(MDB_txn *txn)
 		mop += mop_len;
 		rc = mdb_cursor_first(&mc, &key, &data);
 		for (; !rc; rc = mdb_cursor_next(&mc, &key, &data, MDB_NEXT)) {
-			unsigned flags = MDB_CURRENT;
 			txnid_t id = *(txnid_t *)key.mv_data;
 			ssize_t	len = (ssize_t)(data.mv_size / sizeof(MDB_ID)) - 1;
 			MDB_ID save;
 
 			mdb_tassert(txn, len >= 0 && id <= env->me_pglast);
+			key.mv_data = &id;
 			if (len > mop_len) {
 				len = mop_len;
 				data.mv_size = (len + 1) * sizeof(MDB_ID);
-				/* Drop MDB_CURRENT when changing the data size */
-				key.mv_data = &id;
-				flags = 0;
 			}
 			data.mv_data = mop -= len;
 			save = mop[0];
 			mop[0] = len;
-			rc = mdb_cursor_put(&mc, &key, &data, flags);
+			rc = mdb_cursor_put(&mc, &key, &data, MDB_CURRENT);
 			mop[0] = save;
 			if (rc || !(mop_len -= len))
 				break;
@@ -3680,7 +3677,9 @@ static void NTAPI mdb_tls_callback(PVOID module, DWORD reason, PVOID ptr)
 	case DLL_THREAD_DETACH:
 		for (i=0; i<mdb_tls_nkeys; i++) {
 			MDB_reader *r = pthread_getspecific(mdb_tls_keys[i]);
-			mdb_env_reader_dest(r);
+			if (r) {
+				mdb_env_reader_dest(r);
+			}
 		}
 		break;
 	case DLL_PROCESS_DETACH: break;
@@ -4547,6 +4546,13 @@ mdb_cmp_cint(const MDB_val *a, const MDB_val *b)
 #endif
 }
 
+/** Compare two items pointing at size_t's of unknown alignment. */
+#ifdef MISALIGNED_OK
+# define mdb_cmp_clong mdb_cmp_long
+#else
+# define mdb_cmp_clong mdb_cmp_cint
+#endif
+
 /** Compare two items lexically */
 static int
 mdb_cmp_memn(const MDB_val *a, const MDB_val *b)
@@ -5415,7 +5421,7 @@ mdb_cursor_set(MDB_cursor *mc, MDB_val *key, MDB_val *data,
 		if (!mc->mc_top) {
 			/* There are no other pages */
 			mc->mc_ki[mc->mc_top] = 0;
-			if (op == MDB_SET_RANGE) {
+			if (op == MDB_SET_RANGE && !exactp) {
 				rc = 0;
 				goto set1;
 			} else
@@ -5800,14 +5806,14 @@ mdb_cursor_put(MDB_cursor *mc, MDB_val *key, MDB_val *data,
 	uint16_t	fp_flags;
 	MDB_val		xdata, *rdata, dkey, olddata;
 	MDB_db dummy;
-	int do_sub = 0, insert;
+	int do_sub = 0, insert_key, insert_data;
 	unsigned int mcount = 0, dcount = 0, nospill;
 	size_t nsize;
 	int rc, rc2;
 	unsigned int nflags;
 	DKBUF;
 
-	if (mc == NULL)
+	if (mc == NULL || key == NULL)
 		return EINVAL;
 
 	env = mc->mc_txn->mt_env;
@@ -5828,16 +5834,8 @@ mdb_cursor_put(MDB_cursor *mc, MDB_val *key, MDB_val *data,
 	if (mc->mc_txn->mt_flags & (MDB_TXN_RDONLY|MDB_TXN_ERROR))
 		return (mc->mc_txn->mt_flags & MDB_TXN_RDONLY) ? EACCES : MDB_BAD_TXN;
 
-	if (flags != MDB_CURRENT) {
-		if (key == NULL)
-			return EINVAL;
-		if (key->mv_size-1 >= ENV_MAXKEY(env))
-			return MDB_BAD_VALSIZE;
-	} else {
-		/* Ignore key except in sub-cursor, where key holds the data */
-		if (!(mc->mc_flags & C_SUB))
-			key = NULL;
-	}
+	if (key->mv_size-1 >= ENV_MAXKEY(env))
+		return MDB_BAD_VALSIZE;
 
 #if SIZE_MAX > MAXDATASIZE
 	if (data->mv_size > ((mc->mc_db->md_flags & MDB_DUPSORT) ? ENV_MAXKEY(env) : MAXDATASIZE))
@@ -5927,8 +5925,8 @@ mdb_cursor_put(MDB_cursor *mc, MDB_val *key, MDB_val *data,
 			return rc2;
 	}
 
-	insert = rc;
-	if (insert) {
+	insert_key = insert_data = rc;
+	if (insert_key) {
 		/* The key does not exist */
 		DPRINTF(("inserting key at index %i", mc->mc_ki[mc->mc_top]));
 		if ((mc->mc_db->md_flags & MDB_DUPSORT) &&
@@ -5978,21 +5976,14 @@ more:
 
 #if UINT_MAX < SIZE_MAX
 				if (mc->mc_dbx->md_dcmp == mdb_cmp_int && olddata.mv_size == sizeof(size_t))
-#ifdef MISALIGNED_OK
-					mc->mc_dbx->md_dcmp = mdb_cmp_long;
-#else
-					mc->mc_dbx->md_dcmp = mdb_cmp_cint;
-#endif
+					mc->mc_dbx->md_dcmp = mdb_cmp_clong;
 #endif
 				/* if data matches, skip it */
 				if (!mc->mc_dbx->md_dcmp(data, &olddata)) {
 					if (flags & MDB_NODUPDATA)
-						rc = MDB_KEYEXIST;
-					else if (flags & MDB_MULTIPLE)
-						goto next_mult;
-					else
-						rc = MDB_SUCCESS;
-					return rc;
+						return MDB_KEYEXIST;
+					rc = MDB_SUCCESS;
+					goto next_sub;
 				}
 
 				/* Back up original data item */
@@ -6089,7 +6080,7 @@ prep_subDB:
 			rdata = &xdata;
 			flags |= F_DUPDATA;
 			do_sub = 1;
-			if (!insert)
+			if (!insert_key)
 				mdb_node_del(mc, 0);
 			goto new_sub;
 		}
@@ -6130,8 +6121,8 @@ current:
 						return ENOMEM;
 					id2.mid = pg;
 					id2.mptr = np;
-					rc = mdb_mid2l_insert(mc->mc_txn->mt_u.dirty_list, &id2);
-					mdb_cassert(mc, rc == 0);
+					rc2 = mdb_mid2l_insert(mc->mc_txn->mt_u.dirty_list, &id2);
+					mdb_cassert(mc, rc2 == 0);
 					if (!(flags & MDB_RESERVE)) {
 						/* Copy end of page, adjusting alignment so
 						 * compiler may copy words instead of bytes.
@@ -6149,7 +6140,7 @@ current:
 					data->mv_data = METADATA(omp);
 				else
 					memcpy(METADATA(omp), data->mv_data, data->mv_size);
-				goto done;
+				return MDB_SUCCESS;
 			  }
 			}
 			if ((rc2 = mdb_ovpage_free(mc, omp)) != MDB_SUCCESS)
@@ -6165,10 +6156,9 @@ current:
 				memcpy(olddata.mv_data, data->mv_data, data->mv_size);
 			else
 				memcpy(NODEKEY(leaf), key->mv_data, key->mv_size);
-			goto done;
+			return MDB_SUCCESS;
 		}
 		mdb_node_del(mc, 0);
-		mc->mc_db->md_entries--;
 	}
 
 	rdata = data;
@@ -6178,14 +6168,14 @@ new_sub:
 	nsize = IS_LEAF2(mc->mc_pg[mc->mc_top]) ? key->mv_size : mdb_leaf_size(env, key, rdata);
 	if (SIZELEFT(mc->mc_pg[mc->mc_top]) < nsize) {
 		if (( flags & (F_DUPDATA|F_SUBDATA)) == F_DUPDATA )
-			nflags &= ~MDB_APPEND;
-		if (!insert)
+			nflags &= ~MDB_APPEND; /* sub-page may need room to grow */
+		if (!insert_key)
 			nflags |= MDB_SPLIT_REPLACE;
 		rc = mdb_page_split(mc, key, rdata, P_INVALID, nflags);
 	} else {
 		/* There is room already in this leaf page. */
 		rc = mdb_node_add(mc, mc->mc_ki[mc->mc_top], key, rdata, 0, nflags);
-		if (rc == 0 && !do_sub && insert) {
+		if (rc == 0 && insert_key) {
 			/* Adjust other cursors pointing to mp */
 			MDB_cursor *m2, *m3;
 			MDB_dbi dbi = mc->mc_dbi;
@@ -6205,9 +6195,7 @@ new_sub:
 		}
 	}
 
-	if (rc != MDB_SUCCESS)
-		mc->mc_txn->mt_flags |= MDB_TXN_ERROR;
-	else {
+	if (rc == MDB_SUCCESS) {
 		/* Now store the actual data in the child DB. Note that we're
 		 * storing the user data in the keys field, so there are strict
 		 * size limits on dupdata. The actual data fields of the child
@@ -6215,6 +6203,7 @@ new_sub:
 		 */
 		if (do_sub) {
 			int xflags;
+			size_t ecount;
 put_sub:
 			xdata.mv_size = 0;
 			xdata.mv_data = "";
@@ -6229,10 +6218,8 @@ put_sub:
 			/* converted, write the original data first */
 			if (dkey.mv_size) {
 				rc = mdb_cursor_put(&mc->mc_xcursor->mx_cursor, &dkey, &xdata, xflags);
-				if (rc) {
-					mc->mc_txn->mt_flags |= MDB_TXN_ERROR;
-					return rc == MDB_KEYEXIST ? MDB_CORRUPTED : rc;
-				}
+				if (rc)
+					goto bad_sub;
 				{
 					/* Adjust other cursors pointing to mp */
 					MDB_cursor *m2;
@@ -6250,6 +6237,7 @@ put_sub:
 				/* we've done our job */
 				dkey.mv_size = 0;
 			}
+			ecount = mc->mc_xcursor->mx_db.md_entries;
 			if (flags & MDB_APPENDDUP)
 				xflags |= MDB_APPEND;
 			rc = mdb_cursor_put(&mc->mc_xcursor->mx_cursor, data, &xdata, xflags);
@@ -6257,31 +6245,39 @@ put_sub:
 				void *db = NODEDATA(leaf);
 				memcpy(db, &mc->mc_xcursor->mx_db, sizeof(MDB_db));
 			}
+			insert_data = mc->mc_xcursor->mx_db.md_entries - ecount;
 		}
-		/* sub-writes might have failed so check rc again.
-		 * Don't increment count if we just replaced an existing item.
-		 */
-		if (!rc && !(flags & MDB_CURRENT))
+		/* Increment count unless we just replaced an existing item. */
+		if (insert_data)
 			mc->mc_db->md_entries++;
+		if (insert_key) {
+			/* Invalidate txn if we created an empty sub-DB */
+			if (rc)
+				goto bad_sub;
+			/* If we succeeded and the key didn't exist before,
+			 * make sure the cursor is marked valid.
+			 */
+			mc->mc_flags |= C_INITIALIZED;
+		}
+next_sub:
 		if (flags & MDB_MULTIPLE) {
 			if (!rc) {
-next_mult:
 				mcount++;
 				/* let caller know how many succeeded, if any */
 				data[1].mv_size = mcount;
 				if (mcount < dcount) {
 					data[0].mv_data = (char *)data[0].mv_data + data[0].mv_size;
+					insert_key = insert_data = 0;
 					goto more;
 				}
 			}
 		}
+		return rc;
+bad_sub:
+		if (rc == MDB_KEYEXIST)	/* should not happen, we deleted that item */
+			rc = MDB_CORRUPTED;
 	}
-done:
-	/* If we succeeded and the key didn't exist before, make sure
-	 * the cursor is marked valid.
-	 */
-	if (!rc && insert)
-		mc->mc_flags |= C_INITIALIZED;
+	mc->mc_txn->mt_flags |= MDB_TXN_ERROR;
 	return rc;
 }
 
@@ -6314,7 +6310,10 @@ mdb_cursor_del(MDB_cursor *mc, unsigned int flags)
 	leaf = NODEPTR(mp, mc->mc_ki[mc->mc_top]);
 
 	if (F_ISSET(leaf->mn_flags, F_DUPDATA)) {
-		if (!(flags & MDB_NODUPDATA)) {
+		if (flags & MDB_NODUPDATA) {
+			/* mdb_cursor_del0() will subtract the final entry */
+			mc->mc_db->md_entries -= mc->mc_xcursor->mx_db.md_entries - 1;
+		} else {
 			if (!F_ISSET(leaf->mn_flags, F_SUBDATA)) {
 				mc->mc_xcursor->mx_cursor.mc_pg[0] = NODEDATA(leaf);
 			}
@@ -6353,7 +6352,6 @@ mdb_cursor_del(MDB_cursor *mc, unsigned int flags)
 			rc = mdb_drop0(&mc->mc_xcursor->mx_cursor, 0);
 			if (rc)
 				goto fail;
-			mc->mc_db->md_entries -= mc->mc_xcursor->mx_db.md_entries;
 		}
 	}
 
@@ -6782,11 +6780,7 @@ mdb_xcursor_init1(MDB_cursor *mc, MDB_node *node)
 	mx->mx_dbflag = DB_VALID|DB_DIRTY; /* DB_DIRTY guides mdb_cursor_touch */
 #if UINT_MAX < SIZE_MAX
 	if (mx->mx_dbx.md_cmp == mdb_cmp_int && mx->mx_db.md_pad == sizeof(size_t))
-#ifdef MISALIGNED_OK
-		mx->mx_dbx.md_cmp = mdb_cmp_long;
-#else
-		mx->mx_dbx.md_cmp = mdb_cmp_cint;
-#endif
+		mx->mx_dbx.md_cmp = mdb_cmp_clong;
 #endif
 }
 
@@ -7295,9 +7289,18 @@ mdb_page_merge(MDB_cursor *csrc, MDB_cursor *cdst)
 			}
 		}
 	}
-	mdb_cursor_pop(csrc);
-
-	return mdb_rebalance(csrc);
+	{
+		unsigned int snum = cdst->mc_snum;
+		uint16_t depth = cdst->mc_db->md_depth;
+		mdb_cursor_pop(cdst);
+		rc = mdb_rebalance(cdst);
+		/* Did the tree shrink? */
+		if (depth > cdst->mc_db->md_depth)
+			snum--;
+		cdst->mc_snum = snum;
+		cdst->mc_top = snum-1;
+	}
+	return rc;
 }
 
 /** Copy the contents of a cursor.
@@ -7335,6 +7338,7 @@ mdb_rebalance(MDB_cursor *mc)
 	int rc;
 	unsigned int ptop, minkeys;
 	MDB_cursor	mn;
+	indx_t oldki;
 
 	minkeys = 1 + (IS_BRANCH(mc->mc_pg[mc->mc_top]));
 	DPRINTF(("rebalancing %s page %"Z"u (has %u keys, %.1f%% full)",
@@ -7385,6 +7389,7 @@ mdb_rebalance(MDB_cursor *mc)
 				}
 			}
 		} else if (IS_BRANCH(mp) && NUMKEYS(mp) == 1) {
+			int i;
 			DPUTS("collapsing root page!");
 			rc = mdb_midl_append(&mc->mc_txn->mt_free_pgs, mp->mp_pgno);
 			if (rc)
@@ -7396,6 +7401,10 @@ mdb_rebalance(MDB_cursor *mc)
 			mc->mc_db->md_depth--;
 			mc->mc_db->md_branch_pages--;
 			mc->mc_ki[0] = mc->mc_ki[1];
+			for (i = 1; i<mc->mc_db->md_depth; i++) {
+				mc->mc_pg[i] = mc->mc_pg[i+1];
+				mc->mc_ki[i] = mc->mc_ki[i+1];
+			}
 			{
 				/* Adjust other cursors pointing to mp */
 				MDB_cursor *m2, *m3;
@@ -7408,7 +7417,6 @@ mdb_rebalance(MDB_cursor *mc)
 						m3 = m2;
 					if (m3 == mc || m3->mc_snum < mc->mc_snum) continue;
 					if (m3->mc_pg[0] == mp) {
-						int i;
 						m3->mc_snum--;
 						m3->mc_top--;
 						for (i=0; i<m3->mc_snum; i++) {
@@ -7439,6 +7447,7 @@ mdb_rebalance(MDB_cursor *mc)
 	mdb_cursor_copy(mc, &mn);
 	mn.mc_xcursor = NULL;
 
+	oldki = mc->mc_ki[mc->mc_top];
 	if (mc->mc_ki[ptop] == 0) {
 		/* We're the leftmost leaf in our parent.
 		 */
@@ -7472,18 +7481,23 @@ mdb_rebalance(MDB_cursor *mc)
 	 * (A branch page must never have less than 2 keys.)
 	 */
 	minkeys = 1 + (IS_BRANCH(mn.mc_pg[mn.mc_top]));
-	if (PAGEFILL(mc->mc_txn->mt_env, mn.mc_pg[mn.mc_top]) >= FILL_THRESHOLD && NUMKEYS(mn.mc_pg[mn.mc_top]) > minkeys)
-		return mdb_node_move(&mn, mc);
-	else {
-		if (mc->mc_ki[ptop] == 0)
+	if (PAGEFILL(mc->mc_txn->mt_env, mn.mc_pg[mn.mc_top]) >= FILL_THRESHOLD && NUMKEYS(mn.mc_pg[mn.mc_top]) > minkeys) {
+		rc = mdb_node_move(&mn, mc);
+		if (mc->mc_ki[ptop]) {
+			oldki++;
+		}
+	} else {
+		if (mc->mc_ki[ptop] == 0) {
 			rc = mdb_page_merge(&mn, mc);
-		else {
+		} else {
+			oldki += NUMKEYS(mn.mc_pg[mn.mc_top]);
 			mn.mc_ki[mn.mc_top] += mc->mc_ki[mn.mc_top] + 1;
 			rc = mdb_page_merge(mc, &mn);
 			mdb_cursor_copy(&mn, mc);
 		}
-		mc->mc_flags &= ~(C_INITIALIZED|C_EOF);
+		mc->mc_flags &= ~C_EOF;
 	}
+	mc->mc_ki[mc->mc_top] = oldki;
 	return rc;
 }
 
diff --git a/libraries/libmdb/mdb.c b/libraries/libmdb/mdb.c
new file mode 100644
index 0000000000..bd39a203f2
--- /dev/null
+++ b/libraries/libmdb/mdb.c
@@ -0,0 +1,3678 @@
+/* mdb.c - memory-mapped database library */
+/*
+ * Copyright 2011 Howard Chu, Symas Corp.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted only as authorized by the OpenLDAP
+ * Public License.
+ *
+ * A copy of this license is available in the file LICENSE in the
+ * top-level directory of the distribution or, alternatively, at
+ * <http://www.OpenLDAP.org/license.html>.
+ *
+ * This code is derived from btree.c written by Martin Hedenfalk.
+ *
+ * Copyright (c) 2009, 2010 Martin Hedenfalk <martin@bzero.se>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/param.h>
+#include <sys/uio.h>
+#include <sys/mman.h>
+#ifdef HAVE_SYS_FILE_H
+#include <sys/file.h>
+#endif
+#include <fcntl.h>
+
+#include <assert.h>
+#include <errno.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+#include <pthread.h>
+
+#include "mdb.h"
+
+#define ULONG		unsigned long
+typedef ULONG		pgno_t;
+
+#include "midl.h"
+
+/* Note: If O_DSYNC is undefined but exists in /usr/include,
+ * preferably set some compiler flag to get the definition.
+ * Otherwise compile with the less efficient -DMDB_DSYNC=O_SYNC.
+ */
+#ifndef MDB_DSYNC
+# define MDB_DSYNC	O_DSYNC
+#endif
+
+#ifndef DEBUG
+#define DEBUG 1
+#endif
+
+#if !(__STDC_VERSION__ >= 199901L || defined(__GNUC__))
+# define DPRINTF	(void)	/* Vararg macros may be unsupported */
+#elif DEBUG
+# define DPRINTF(fmt, ...)	/* Requires 2 or more args */ \
+	fprintf(stderr, "%s:%d: " fmt "\n", __func__, __LINE__, __VA_ARGS__)
+#else
+# define DPRINTF(fmt, ...)	((void) 0)
+#endif
+#define DPUTS(arg)	DPRINTF("%s", arg)
+
+#define PAGESIZE	 4096
+#define MDB_MINKEYS	 2
+#define MDB_MAGIC	 0xBEEFC0DE
+#define MDB_VERSION	 1
+#define MAXKEYSIZE	 511
+#if DEBUG
+#define	KBUF	(MAXKEYSIZE*2+1)
+#define DKBUF	char kbuf[KBUF]
+#define	DKEY(x)	mdb_dkey(x, kbuf)
+#else
+#define	DKBUF
+#define DKEY(x)
+#endif
+
+#define P_INVALID	 (~0UL)
+
+#define F_ISSET(w, f)	 (((w) & (f)) == (f))
+
+typedef uint16_t	 indx_t;
+
+#define DEFAULT_READERS	126
+#define DEFAULT_MAPSIZE	1048576
+
+/* Lock descriptor stuff */
+#ifndef CACHELINE
+#define CACHELINE	64	/* most CPUs. Itanium uses 128 */
+#endif
+
+typedef struct MDB_rxbody {
+	ULONG		mrb_txnid;
+	pid_t		mrb_pid;
+	pthread_t	mrb_tid;
+} MDB_rxbody;
+
+typedef struct MDB_reader {
+	union {
+		MDB_rxbody mrx;
+#define	mr_txnid	mru.mrx.mrb_txnid
+#define	mr_pid	mru.mrx.mrb_pid
+#define	mr_tid	mru.mrx.mrb_tid
+		/* cache line alignment */
+		char pad[(sizeof(MDB_rxbody)+CACHELINE-1) & ~(CACHELINE-1)];
+	} mru;
+} MDB_reader;
+
+typedef struct MDB_txbody {
+	uint32_t	mtb_magic;
+	uint32_t	mtb_version;
+	pthread_mutex_t	mtb_mutex;
+	ULONG		mtb_txnid;
+	uint32_t	mtb_numreaders;
+	uint32_t	mtb_me_toggle;
+} MDB_txbody;
+
+typedef struct MDB_txninfo {
+	union {
+		MDB_txbody mtb;
+#define mti_magic	mt1.mtb.mtb_magic
+#define mti_version	mt1.mtb.mtb_version
+#define mti_mutex	mt1.mtb.mtb_mutex
+#define mti_txnid	mt1.mtb.mtb_txnid
+#define mti_numreaders	mt1.mtb.mtb_numreaders
+#define mti_me_toggle	mt1.mtb.mtb_me_toggle
+		char pad[(sizeof(MDB_txbody)+CACHELINE-1) & ~(CACHELINE-1)];
+	} mt1;
+	union {
+		pthread_mutex_t	mt2_wmutex;
+#define mti_wmutex	mt2.mt2_wmutex
+		char pad[(sizeof(pthread_mutex_t)+CACHELINE-1) & ~(CACHELINE-1)];
+	} mt2;
+	MDB_reader	mti_readers[1];
+} MDB_txninfo;
+
+/* Common header for all page types. Overflow pages
+ * occupy a number of contiguous pages with no
+ * headers on any page after the first.
+ */
+typedef struct MDB_page {		/* represents a page of storage */
+#define	mp_pgno		mp_p.p_pgno
+	union padded {
+		pgno_t		p_pgno;		/* page number */
+		void *		p_align;	/* for IL32P64 */
+	} mp_p;
+#define	P_BRANCH	 0x01		/* branch page */
+#define	P_LEAF		 0x02		/* leaf page */
+#define	P_OVERFLOW	 0x04		/* overflow page */
+#define	P_META		 0x08		/* meta page */
+#define	P_DIRTY		 0x10		/* dirty page */
+#define	P_LEAF2		 0x20		/* DB with small, fixed size keys and no data */
+	uint32_t	mp_flags;
+#define mp_lower	mp_pb.pb.pb_lower
+#define mp_upper	mp_pb.pb.pb_upper
+#define mp_pages	mp_pb.pb_pages
+	union page_bounds {
+		struct {
+			indx_t		pb_lower;		/* lower bound of free space */
+			indx_t		pb_upper;		/* upper bound of free space */
+		} pb;
+		uint32_t	pb_pages;	/* number of overflow pages */
+	} mp_pb;
+	indx_t		mp_ptrs[1];		/* dynamic size */
+} MDB_page;
+
+#define PAGEHDRSZ	 ((unsigned) offsetof(MDB_page, mp_ptrs))
+
+#define NUMKEYS(p)	 (((p)->mp_lower - PAGEHDRSZ) >> 1)
+#define SIZELEFT(p)	 (indx_t)((p)->mp_upper - (p)->mp_lower)
+#define PAGEFILL(env, p) (1000L * ((env)->me_psize - PAGEHDRSZ - SIZELEFT(p)) / \
+				((env)->me_psize - PAGEHDRSZ))
+#define IS_LEAF(p)	 F_ISSET((p)->mp_flags, P_LEAF)
+#define IS_LEAF2(p)	 F_ISSET((p)->mp_flags, P_LEAF2)
+#define IS_BRANCH(p)	 F_ISSET((p)->mp_flags, P_BRANCH)
+#define IS_OVERFLOW(p)	 F_ISSET((p)->mp_flags, P_OVERFLOW)
+
+#define OVPAGES(size, psize)	((PAGEHDRSZ-1 + (size)) / (psize) + 1)
+
+typedef struct MDB_db {
+	uint32_t	md_pad;		/* also ksize for LEAF2 pages */
+	uint16_t	md_flags;
+	uint16_t	md_depth;
+	ULONG		md_branch_pages;
+	ULONG		md_leaf_pages;
+	ULONG		md_overflow_pages;
+	ULONG		md_entries;
+	pgno_t		md_root;
+} MDB_db;
+
+#define	FREE_DBI	0
+#define	MAIN_DBI	1
+
+typedef struct MDB_meta {			/* meta (footer) page content */
+	uint32_t	mm_magic;
+	uint32_t	mm_version;
+	void		*mm_address;		/* address for fixed mapping */
+	size_t		mm_mapsize;			/* size of mmap region */
+	MDB_db		mm_dbs[2];			/* first is free space, 2nd is main db */
+#define	mm_psize	mm_dbs[0].md_pad
+#define	mm_flags	mm_dbs[0].md_flags
+	pgno_t		mm_last_pg;			/* last used page in file */
+	ULONG		mm_txnid;			/* txnid that committed this page */
+} MDB_meta;
+
+typedef struct MDB_dhead {					/* a dirty page */
+	MDB_page	*md_parent;
+	unsigned	md_pi;				/* parent index */
+	int			md_num;
+} MDB_dhead;
+
+typedef struct MDB_dpage {
+	MDB_dhead	h;
+	MDB_page	p;
+} MDB_dpage;
+
+typedef struct MDB_oldpages {
+	struct MDB_oldpages *mo_next;
+	ULONG		mo_txnid;
+	pgno_t		mo_pages[1];	/* dynamic */
+} MDB_oldpages;
+
+typedef struct MDB_pageparent {
+	MDB_page *mp_page;
+	MDB_page *mp_parent;
+	unsigned mp_pi;
+} MDB_pageparent;
+
+static MDB_dpage *mdb_alloc_page(MDB_txn *txn, MDB_page *parent, unsigned int parent_idx, int num);
+static int 		mdb_touch(MDB_txn *txn, MDB_pageparent *mp);
+
+typedef struct MDB_ppage {					/* ordered list of pages */
+	MDB_page		*mp_page;
+	unsigned int	mp_ki;		/* cursor index on page */
+} MDB_ppage;
+
+#define CURSOR_TOP(c)		 (&(c)->mc_stack[(c)->mc_snum-1])
+#define CURSOR_PARENT(c)	 (&(c)->mc_stack[(c)->mc_snum-2])
+
+struct MDB_xcursor;
+
+struct MDB_cursor {
+	MDB_txn		*mc_txn;
+	MDB_ppage	mc_stack[32];		/* stack of parent pages */
+	unsigned int	mc_snum;		/* number of pushed pages */
+	MDB_dbi		mc_dbi;
+	short		mc_initialized;	/* 1 if initialized */
+	short		mc_eof;		/* 1 if end is reached */
+	struct MDB_xcursor	*mc_xcursor;
+};
+
+#define METADATA(p)	 ((void *)((char *)(p) + PAGEHDRSZ))
+
+typedef struct MDB_node {
+#define mn_pgno		 mn_p.np_pgno
+#define mn_dsize	 mn_p.np_dsize
+	union {
+		pgno_t		 np_pgno;	/* child page number */
+		uint32_t	 np_dsize;	/* leaf data size */
+	} mn_p;
+	unsigned int	mn_flags:4;
+	unsigned int	mn_ksize:12;			/* key size */
+#define F_BIGDATA	 0x01			/* data put on overflow page */
+#define F_SUBDATA	 0x02			/* data is a sub-database */
+#define F_DUPDATA	 0x04			/* data has duplicates */
+	char		mn_data[1];
+} MDB_node;
+
+typedef struct MDB_dbx {
+	MDB_val		md_name;
+	MDB_cmp_func	*md_cmp;		/* user compare function */
+	MDB_cmp_func	*md_dcmp;		/* user dupsort function */
+	MDB_rel_func	*md_rel;		/* user relocate function */
+	MDB_dbi	md_parent;
+	unsigned int	md_dirty;
+} MDB_dbx;
+
+struct MDB_txn {
+	pgno_t		mt_next_pgno;	/* next unallocated page */
+	ULONG		mt_txnid;
+	ULONG		mt_oldest;
+	MDB_env		*mt_env;	
+	pgno_t		*mt_free_pgs;	/* this is an IDL */
+	union {
+		MIDL2	*dirty_list;	/* modified pages */
+		MDB_reader	*reader;
+	} mt_u;
+	MDB_dbx		*mt_dbxs;		/* array */
+	MDB_db		*mt_dbs;
+	unsigned int	mt_numdbs;
+
+#define MDB_TXN_RDONLY		0x01		/* read-only transaction */
+#define MDB_TXN_ERROR		0x02		/* an error has occurred */
+#define MDB_TXN_METOGGLE	0x04		/* used meta page 1 */
+	unsigned int	mt_flags;
+};
+
+/* Context for sorted-dup records */
+typedef struct MDB_xcursor {
+	MDB_cursor mx_cursor;
+	MDB_txn mx_txn;
+	MDB_dbx	mx_dbxs[4];
+	MDB_db	mx_dbs[4];
+} MDB_xcursor;
+
+struct MDB_env {
+	int			me_fd;
+	int			me_lfd;
+	int			me_mfd;			/* just for writing the meta pages */
+#define	MDB_FATAL_ERROR	0x80000000U
+	uint32_t 	me_flags;
+	uint32_t	me_extrapad;	/* unused for now */
+	unsigned int	me_maxreaders;
+	unsigned int	me_numdbs;
+	unsigned int	me_maxdbs;
+	char		*me_path;
+	char		*me_map;
+	MDB_txninfo	*me_txns;
+	MDB_meta	*me_metas[2];
+	MDB_meta	*me_meta;
+	MDB_txn		*me_txn;		/* current write transaction */
+	size_t		me_mapsize;
+	off_t		me_size;		/* current file size */
+	pgno_t		me_maxpg;		/* me_mapsize / me_psize */
+	unsigned int	me_psize;
+	unsigned int	me_db_toggle;
+	MDB_dbx		*me_dbxs;		/* array */
+	MDB_db		*me_dbs[2];
+	MDB_oldpages *me_pghead;
+	pthread_key_t	me_txkey;	/* thread-key for readers */
+	MDB_dpage	*me_dpages;
+	pgno_t		me_free_pgs[MDB_IDL_UM_SIZE];
+	MIDL2		me_dirty_list[MDB_IDL_DB_SIZE];
+};
+
+#define NODESIZE	 offsetof(MDB_node, mn_data)
+
+#define INDXSIZE(k)	 (NODESIZE + ((k) == NULL ? 0 : (k)->mv_size))
+#define LEAFSIZE(k, d)	 (NODESIZE + (k)->mv_size + (d)->mv_size)
+#define NODEPTR(p, i)	 ((MDB_node *)((char *)(p) + (p)->mp_ptrs[i]))
+#define NODEKEY(node)	 (void *)((node)->mn_data)
+#define NODEDATA(node)	 (void *)((char *)(node)->mn_data + (node)->mn_ksize)
+#define NODEPGNO(node)	 ((node)->mn_pgno)
+#define NODEDSZ(node)	 ((node)->mn_dsize)
+#define NODEKSZ(node)	 ((node)->mn_ksize)
+#define LEAF2KEY(p, i, ks)	((char *)(p) + PAGEHDRSZ + ((i)*(ks)))
+
+#define MDB_SET_KEY(node, key)	if (key!=NULL) {(key)->mv_size = NODEKSZ(node); (key)->mv_data = NODEKEY(node);}
+
+#define MDB_COMMIT_PAGES	 64	/* max number of pages to write in one commit */
+
+static int  mdb_search_page_root(MDB_txn *txn,
+			    MDB_dbi dbi, MDB_val *key,
+			    MDB_cursor *cursor, int modify,
+			    MDB_pageparent *mpp);
+static int  mdb_search_page(MDB_txn *txn,
+			    MDB_dbi dbi, MDB_val *key,
+			    MDB_cursor *cursor, int modify,
+			    MDB_pageparent *mpp);
+
+static int  mdb_env_read_header(MDB_env *env, MDB_meta *meta);
+static int  mdb_env_read_meta(MDB_env *env, int *which);
+static int  mdb_env_write_meta(MDB_txn *txn);
+static MDB_page *mdb_get_page(MDB_txn *txn, pgno_t pgno);
+
+static MDB_node *mdb_search_node(MDB_txn *txn, MDB_dbi dbi, MDB_page *mp,
+			    MDB_val *key, int *exactp, unsigned int *kip);
+static int  mdb_add_node(MDB_txn *txn, MDB_dbi dbi, MDB_page *mp,
+			    indx_t indx, MDB_val *key, MDB_val *data,
+			    pgno_t pgno, uint8_t flags);
+static void mdb_del_node(MDB_page *mp, indx_t indx, int ksize);
+static int mdb_del0(MDB_txn *txn, MDB_dbi dbi, unsigned int ki,
+    MDB_pageparent *mpp, MDB_node *leaf);
+static int mdb_put0(MDB_txn *txn, MDB_dbi dbi,
+    MDB_val *key, MDB_val *data, unsigned int flags);
+static int  mdb_read_data(MDB_txn *txn, MDB_node *leaf, MDB_val *data);
+
+static int		 mdb_rebalance(MDB_txn *txn, MDB_dbi dbi, MDB_pageparent *mp);
+static int		 mdb_update_key(MDB_page *mp, indx_t indx, MDB_val *key);
+static int		 mdb_move_node(MDB_txn *txn, MDB_dbi dbi, 
+				MDB_pageparent *src, indx_t srcindx,
+				MDB_pageparent *dst, indx_t dstindx);
+static int		 mdb_merge(MDB_txn *txn, MDB_dbi dbi, MDB_pageparent *src,
+			    MDB_pageparent *dst);
+static int		 mdb_split(MDB_txn *txn, MDB_dbi dbi, MDB_page **mpp,
+			    unsigned int *newindxp, MDB_val *newkey,
+			    MDB_val *newdata, pgno_t newpgno);
+static MDB_dpage *mdb_new_page(MDB_txn *txn, MDB_dbi dbi, uint32_t flags, int num);
+
+static void		 cursor_pop_page(MDB_cursor *cursor);
+static MDB_ppage *cursor_push_page(MDB_cursor *cursor,
+			    MDB_page *mp);
+
+static int		 mdb_sibling(MDB_cursor *cursor, int move_right);
+static int		 mdb_cursor_next(MDB_cursor *cursor,
+			    MDB_val *key, MDB_val *data, MDB_cursor_op op);
+static int		 mdb_cursor_prev(MDB_cursor *cursor,
+			    MDB_val *key, MDB_val *data, MDB_cursor_op op);
+static int		 mdb_cursor_set(MDB_cursor *cursor,
+			    MDB_val *key, MDB_val *data, MDB_cursor_op op, int *exactp);
+static int		 mdb_cursor_first(MDB_cursor *cursor,
+			    MDB_val *key, MDB_val *data);
+static int		 mdb_cursor_last(MDB_cursor *cursor,
+			    MDB_val *key, MDB_val *data);
+
+static void		mdb_xcursor_init0(MDB_txn *txn, MDB_dbi dbi, MDB_xcursor *mx);
+static void		mdb_xcursor_init1(MDB_txn *txn, MDB_dbi dbi, MDB_xcursor *mx, MDB_node *node);
+static void		mdb_xcursor_fini(MDB_txn *txn, MDB_dbi dbi, MDB_xcursor *mx);
+
+static size_t		 mdb_leaf_size(MDB_env *env, MDB_val *key,
+			    MDB_val *data);
+static size_t		 mdb_branch_size(MDB_env *env, MDB_val *key);
+
+static int		 memncmp(const void *s1, size_t n1,
+				 const void *s2, size_t n2);
+static int		 memnrcmp(const void *s1, size_t n1,
+				  const void *s2, size_t n2);
+
+static int
+memncmp(const void *s1, size_t n1, const void *s2, size_t n2)
+{
+	int diff, len_diff = -1;
+
+	if (n1 >= n2) {
+		len_diff = (n1 > n2);
+		n1 = n2;
+	}
+	diff = memcmp(s1, s2, n1);
+	return diff ? diff : len_diff;
+}
+
+static int
+memnrcmp(const void *s1, size_t n1, const void *s2, size_t n2)
+{
+	const unsigned char	*p1, *p2, *p1_lim;
+
+	if (n2 == 0)
+		return n1 != 0;
+	if (n1 == 0)
+		return -1;
+
+	p1 = (const unsigned char *)s1 + n1 - 1;
+	p2 = (const unsigned char *)s2 + n2 - 1;
+
+	for (p1_lim = (n1 <= n2 ? s1 : s2);  *p1 == *p2;  p1--, p2--) {
+		if (p1 == p1_lim)
+			return (p1 != s1) ? (p1 != p2) : (p2 != s2) ? -1 : 0;
+	}
+	return *p1 - *p2;
+}
+
+char *
+mdb_version(int *maj, int *min, int *pat)
+{
+	*maj = MDB_VERSION_MAJOR;
+	*min = MDB_VERSION_MINOR;
+	*pat = MDB_VERSION_PATCH;
+	return MDB_VERSION_STRING;
+}
+
+static char *const errstr[] = {
+	"MDB_KEYEXIST: Key/data pair already exists",
+	"MDB_NOTFOUND: No matching key/data pair found",
+	"MDB_PAGE_NOTFOUND: Requested page not found",
+	"MDB_CORRUPTED: Located page was wrong type",
+	"MDB_PANIC: Update of meta page failed",
+	"MDB_VERSION_MISMATCH: Database environment version mismatch"
+};
+
+char *
+mdb_strerror(int err)
+{
+	if (!err)
+		return ("Successful return: 0");
+
+	if (err >= MDB_KEYEXIST && err <= MDB_VERSION_MISMATCH)
+		return errstr[err - MDB_KEYEXIST];
+
+	return strerror(err);
+}
+
+static char *
+mdb_dkey(MDB_val *key, char *buf)
+{
+	char *ptr = buf;
+	unsigned char *c = key->mv_data;
+	unsigned int i;
+	if (key->mv_size > MAXKEYSIZE)
+		return "MAXKEYSIZE";
+	for (i=0; i<key->mv_size; i++)
+		ptr += sprintf(ptr, "%02x", *c++);
+	return buf;
+}
+
+int
+mdb_cmp(MDB_txn *txn, MDB_dbi dbi, const MDB_val *a, const MDB_val *b)
+{
+	if (txn->mt_dbxs[dbi].md_cmp)
+		return txn->mt_dbxs[dbi].md_cmp(a, b);
+
+	if (txn->mt_dbs[dbi].md_flags & (MDB_REVERSEKEY
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+		|MDB_INTEGERKEY
+#endif
+	))
+		return memnrcmp(a->mv_data, a->mv_size, b->mv_data, b->mv_size);
+	else
+		return memncmp((char *)a->mv_data, a->mv_size, b->mv_data, b->mv_size);
+}
+
+int
+mdb_dcmp(MDB_txn *txn, MDB_dbi dbi, const MDB_val *a, const MDB_val *b)
+{
+	if (txn->mt_dbxs[dbi].md_dcmp)
+		return txn->mt_dbxs[dbi].md_dcmp(a, b);
+
+	if (txn->mt_dbs[dbi].md_flags & (0
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+		|MDB_INTEGERDUP
+#endif
+	))
+		return memnrcmp(a->mv_data, a->mv_size, b->mv_data, b->mv_size);
+	else
+		return memncmp((char *)a->mv_data, a->mv_size, b->mv_data, b->mv_size);
+}
+
+/* Allocate new page(s) for writing */
+static MDB_dpage *
+mdb_alloc_page(MDB_txn *txn, MDB_page *parent, unsigned int parent_idx, int num)
+{
+	MDB_dpage *dp;
+	pgno_t pgno = P_INVALID;
+	ULONG oldest;
+	MIDL2 mid;
+
+	if (txn->mt_txnid > 2) {
+
+	oldest = txn->mt_txnid - 2;
+	if (!txn->mt_env->me_pghead && txn->mt_dbs[FREE_DBI].md_root != P_INVALID) {
+		/* See if there's anything in the free DB */
+		MDB_pageparent mpp;
+		MDB_node *leaf;
+		ULONG *kptr;
+
+		mpp.mp_parent = NULL;
+		mpp.mp_pi = 0;
+		mdb_search_page(txn, FREE_DBI, NULL, NULL, 0, &mpp);
+		leaf = NODEPTR(mpp.mp_page, 0);
+		kptr = (ULONG *)NODEKEY(leaf);
+
+		/* It's potentially usable, unless there are still
+		 * older readers outstanding. Grab it.
+		 */
+		if (oldest > *kptr) {
+			MDB_oldpages *mop;
+			MDB_val data;
+			pgno_t *idl;
+
+			mdb_read_data(txn, leaf, &data);
+			idl = (ULONG *)data.mv_data;
+			mop = malloc(sizeof(MDB_oldpages) + MDB_IDL_SIZEOF(idl) - sizeof(pgno_t));
+			mop->mo_next = txn->mt_env->me_pghead;
+			mop->mo_txnid = *kptr;
+			txn->mt_env->me_pghead = mop;
+			memcpy(mop->mo_pages, idl, MDB_IDL_SIZEOF(idl));
+
+#if DEBUG > 1
+			{
+				unsigned int i;
+				DPRINTF("IDL read txn %lu root %lu num %lu",
+					mop->mo_txnid, txn->mt_dbs[FREE_DBI].md_root, idl[0]);
+				for (i=0; i<idl[0]; i++) {
+					DPRINTF("IDL %lu", idl[i+1]);
+				}
+			}
+#endif
+			/* drop this IDL from the DB */
+			mpp.mp_parent = NULL;
+			mpp.mp_pi = 0;
+			mdb_search_page(txn, FREE_DBI, NULL, NULL, 1, &mpp);
+			leaf = NODEPTR(mpp.mp_page, 0);
+			mdb_del0(txn, FREE_DBI, 0, &mpp, leaf);
+		}
+	}
+	if (txn->mt_env->me_pghead) {
+		unsigned int i;
+		for (i=0; i<txn->mt_env->me_txns->mti_numreaders; i++) {
+			ULONG mr = txn->mt_env->me_txns->mti_readers[i].mr_txnid;
+			if (!mr) continue;
+			if (mr < oldest)
+				oldest = txn->mt_env->me_txns->mti_readers[i].mr_txnid;
+		}
+		if (oldest > txn->mt_env->me_pghead->mo_txnid) {
+			MDB_oldpages *mop = txn->mt_env->me_pghead;
+			txn->mt_oldest = oldest;
+			if (num > 1) {
+				/* FIXME: For now, always use fresh pages. We
+				 * really ought to search the free list for a
+				 * contiguous range.
+				 */
+				;
+			} else {
+				/* peel pages off tail, so we only have to truncate the list */
+				pgno = MDB_IDL_LAST(mop->mo_pages);
+				if (MDB_IDL_IS_RANGE(mop->mo_pages)) {
+					mop->mo_pages[2]++;
+					if (mop->mo_pages[2] > mop->mo_pages[1])
+						mop->mo_pages[0] = 0;
+				} else {
+					mop->mo_pages[0]--;
+				}
+				if (MDB_IDL_IS_ZERO(mop->mo_pages)) {
+					txn->mt_env->me_pghead = mop->mo_next;
+					free(mop);
+				}
+			}
+		}
+	}
+	}
+
+	if (pgno == P_INVALID) {
+		/* DB size is maxed out */
+		if (txn->mt_next_pgno + num >= txn->mt_env->me_maxpg)
+			return NULL;
+	}
+	if (txn->mt_env->me_dpages && num == 1) {
+		dp = txn->mt_env->me_dpages;
+		txn->mt_env->me_dpages = (MDB_dpage *)dp->h.md_parent;
+	} else {
+		if ((dp = malloc(txn->mt_env->me_psize * num + sizeof(MDB_dhead))) == NULL)
+			return NULL;
+	}
+	dp->h.md_num = num;
+	dp->h.md_parent = parent;
+	dp->h.md_pi = parent_idx;
+	if (pgno == P_INVALID) {
+		dp->p.mp_pgno = txn->mt_next_pgno;
+		txn->mt_next_pgno += num;
+	} else {
+		dp->p.mp_pgno = pgno;
+	}
+	mid.mid = dp->p.mp_pgno;
+	mid.mptr = dp;
+	mdb_midl2_insert(txn->mt_u.dirty_list, &mid);
+
+	return dp;
+}
+
+/* Touch a page: make it dirty and re-insert into tree with updated pgno.
+ */
+static int
+mdb_touch(MDB_txn *txn, MDB_pageparent *pp)
+{
+	MDB_page *mp = pp->mp_page;
+	pgno_t	pgno;
+	assert(txn != NULL);
+	assert(pp != NULL);
+
+	if (!F_ISSET(mp->mp_flags, P_DIRTY)) {
+		MDB_dpage *dp;
+		if ((dp = mdb_alloc_page(txn, pp->mp_parent, pp->mp_pi, 1)) == NULL)
+			return ENOMEM;
+		DPRINTF("touched page %lu -> %lu", mp->mp_pgno, dp->p.mp_pgno);
+		mdb_midl_insert(txn->mt_free_pgs, mp->mp_pgno);
+		pgno = dp->p.mp_pgno;
+		memcpy(&dp->p, mp, txn->mt_env->me_psize);
+		mp = &dp->p;
+		mp->mp_pgno = pgno;
+		mp->mp_flags |= P_DIRTY;
+
+		/* Update the page number to new touched page. */
+		if (pp->mp_parent != NULL)
+			NODEPGNO(NODEPTR(pp->mp_parent, pp->mp_pi)) = mp->mp_pgno;
+		pp->mp_page = mp;
+	}
+	return 0;
+}
+
+int
+mdb_env_sync(MDB_env *env, int force)
+{
+	int rc = 0;
+	if (force || !F_ISSET(env->me_flags, MDB_NOSYNC)) {
+		if (fdatasync(env->me_fd))
+			rc = errno;
+	}
+	return rc;
+}
+
+int
+mdb_txn_begin(MDB_env *env, int rdonly, MDB_txn **ret)
+{
+	MDB_txn	*txn;
+	int rc, toggle;
+
+	if (env->me_flags & MDB_FATAL_ERROR) {
+		DPUTS("mdb_txn_begin: environment had fatal error, must shutdown!");
+		return MDB_PANIC;
+	}
+	if ((txn = calloc(1, sizeof(MDB_txn))) == NULL) {
+		DPRINTF("calloc: %s", strerror(errno));
+		return ENOMEM;
+	}
+
+	if (rdonly) {
+		txn->mt_flags |= MDB_TXN_RDONLY;
+	} else {
+		txn->mt_u.dirty_list = env->me_dirty_list;
+		txn->mt_u.dirty_list[0].mid = 0;
+		txn->mt_free_pgs = env->me_free_pgs;
+		txn->mt_free_pgs[0] = 0;
+
+		pthread_mutex_lock(&env->me_txns->mti_wmutex);
+		env->me_txns->mti_txnid++;
+	}
+
+	txn->mt_txnid = env->me_txns->mti_txnid;
+	if (rdonly) {
+		MDB_reader *r = pthread_getspecific(env->me_txkey);
+		if (!r) {
+			unsigned int i;
+			pthread_mutex_lock(&env->me_txns->mti_mutex);
+			for (i=0; i<env->me_txns->mti_numreaders; i++)
+				if (env->me_txns->mti_readers[i].mr_pid == 0)
+					break;
+			if (i == env->me_maxreaders) {
+				pthread_mutex_unlock(&env->me_txns->mti_mutex);
+				return ENOSPC;
+			}
+			env->me_txns->mti_readers[i].mr_pid = getpid();
+			env->me_txns->mti_readers[i].mr_tid = pthread_self();
+			r = &env->me_txns->mti_readers[i];
+			pthread_setspecific(env->me_txkey, r);
+			if (i >= env->me_txns->mti_numreaders)
+				env->me_txns->mti_numreaders = i+1;
+			pthread_mutex_unlock(&env->me_txns->mti_mutex);
+		}
+		r->mr_txnid = txn->mt_txnid;
+		txn->mt_u.reader = r;
+	} else {
+		env->me_txn = txn;
+	}
+
+	txn->mt_env = env;
+
+	toggle = env->me_txns->mti_me_toggle;
+	if ((rc = mdb_env_read_meta(env, &toggle)) != MDB_SUCCESS) {
+		mdb_txn_abort(txn);
+		return rc;
+	}
+
+	/* Copy the DB arrays */
+	txn->mt_numdbs = env->me_numdbs;
+	txn->mt_dbxs = env->me_dbxs;	/* mostly static anyway */
+	txn->mt_dbs = malloc(env->me_maxdbs * sizeof(MDB_db));
+	memcpy(txn->mt_dbs, env->me_meta->mm_dbs, 2 * sizeof(MDB_db));
+	if (txn->mt_numdbs > 2)
+		memcpy(txn->mt_dbs+2, env->me_dbs[env->me_db_toggle]+2,
+			(txn->mt_numdbs - 2) * sizeof(MDB_db));
+
+	if (!rdonly) {
+		if (toggle)
+			txn->mt_flags |= MDB_TXN_METOGGLE;
+		txn->mt_next_pgno = env->me_meta->mm_last_pg+1;
+	}
+
+	DPRINTF("begin transaction %lu on mdbenv %p, root page %lu",
+		txn->mt_txnid, (void *) env, txn->mt_dbs[MAIN_DBI].md_root);
+
+	*ret = txn;
+	return MDB_SUCCESS;
+}
+
+void
+mdb_txn_abort(MDB_txn *txn)
+{
+	MDB_env	*env;
+
+	if (txn == NULL)
+		return;
+
+	env = txn->mt_env;
+	DPRINTF("abort transaction %lu on mdbenv %p, root page %lu",
+		txn->mt_txnid, (void *) env, txn->mt_dbs[MAIN_DBI].md_root);
+
+	free(txn->mt_dbs);
+
+	if (F_ISSET(txn->mt_flags, MDB_TXN_RDONLY)) {
+		txn->mt_u.reader->mr_txnid = 0;
+	} else {
+		MDB_oldpages *mop;
+		MDB_dpage *dp;
+		unsigned int i;
+
+		/* return all dirty pages to dpage list */
+		for (i=1; i<=txn->mt_u.dirty_list[0].mid; i++) {
+			dp = txn->mt_u.dirty_list[i].mptr;
+			if (dp->h.md_num == 1) {
+				dp->h.md_parent = (MDB_page *)txn->mt_env->me_dpages;
+				txn->mt_env->me_dpages = dp;
+			} else {
+				/* large pages just get freed directly */
+				free(dp);
+			}
+		}
+
+		while ((mop = txn->mt_env->me_pghead)) {
+			txn->mt_env->me_pghead = mop->mo_next;
+			free(mop);
+		}
+
+		env->me_txn = NULL;
+		env->me_txns->mti_txnid--;
+		for (i=2; i<env->me_numdbs; i++)
+			env->me_dbxs[i].md_dirty = 0;
+		pthread_mutex_unlock(&env->me_txns->mti_wmutex);
+	}
+
+	free(txn);
+}
+
+int
+mdb_txn_commit(MDB_txn *txn)
+{
+	int		 n, done;
+	unsigned int i;
+	ssize_t		 rc;
+	off_t		 size;
+	MDB_dpage	*dp;
+	MDB_env	*env;
+	pgno_t	next;
+	struct iovec	 iov[MDB_COMMIT_PAGES];
+
+	assert(txn != NULL);
+	assert(txn->mt_env != NULL);
+
+	env = txn->mt_env;
+
+	if (F_ISSET(txn->mt_flags, MDB_TXN_RDONLY)) {
+		mdb_txn_abort(txn);
+		return MDB_SUCCESS;
+	}
+
+	if (txn != env->me_txn) {
+		DPUTS("attempt to commit unknown transaction");
+		mdb_txn_abort(txn);
+		return EINVAL;
+	}
+
+	if (F_ISSET(txn->mt_flags, MDB_TXN_ERROR)) {
+		DPUTS("error flag is set, can't commit");
+		mdb_txn_abort(txn);
+		return EINVAL;
+	}
+
+	if (!txn->mt_u.dirty_list[0].mid)
+		goto done;
+
+	DPRINTF("committing transaction %lu on mdbenv %p, root page %lu",
+	    txn->mt_txnid, (void *) env, txn->mt_dbs[MAIN_DBI].md_root);
+
+	/* should only be one record now */
+	if (env->me_pghead) {
+		MDB_val key, data;
+		MDB_oldpages *mop;
+
+		mop = env->me_pghead;
+		key.mv_size = sizeof(pgno_t);
+		key.mv_data = (char *)&mop->mo_txnid;
+		data.mv_size = MDB_IDL_SIZEOF(mop->mo_pages);
+		data.mv_data = mop->mo_pages;
+		mdb_put0(txn, FREE_DBI, &key, &data, 0);
+		free(env->me_pghead);
+		env->me_pghead = NULL;
+	}
+	/* save to free list */
+	if (!MDB_IDL_IS_ZERO(txn->mt_free_pgs)) {
+		MDB_val key, data;
+		MDB_pageparent mpp;
+
+		/* make sure last page of freeDB is touched and on freelist */
+		key.mv_size = MAXKEYSIZE+1;
+		key.mv_data = NULL;
+		mpp.mp_parent = NULL;
+		mpp.mp_pi = 0;
+		mdb_search_page(txn, FREE_DBI, &key, NULL, 1, &mpp);
+
+#if DEBUG > 1
+		{
+			unsigned int i;
+			ULONG *idl = txn->mt_free_pgs;
+			DPRINTF("IDL write txn %lu root %lu num %lu",
+				txn->mt_txnid, txn->mt_dbs[FREE_DBI].md_root, idl[0]);
+			for (i=0; i<idl[0]; i++) {
+				DPRINTF("IDL %lu", idl[i+1]);
+			}
+		}
+#endif
+		/* write to last page of freeDB */
+		key.mv_size = sizeof(pgno_t);
+		key.mv_data = (char *)&txn->mt_txnid;
+		data.mv_size = MDB_IDL_SIZEOF(txn->mt_free_pgs);
+		data.mv_data = txn->mt_free_pgs;
+		mdb_put0(txn, FREE_DBI, &key, &data, 0);
+	}
+
+	/* Update DB root pointers. Their pages have already been
+	 * touched so this is all in-place and cannot fail.
+	 */
+	{
+		MDB_val data;
+		data.mv_size = sizeof(MDB_db);
+
+		for (i = 2; i < txn->mt_numdbs; i++) {
+			if (txn->mt_dbxs[i].md_dirty) {
+				data.mv_data = &txn->mt_dbs[i];
+				mdb_put0(txn, MAIN_DBI, &txn->mt_dbxs[i].md_name, &data, 0);
+			}
+		}
+	}
+
+	/* Commit up to MDB_COMMIT_PAGES dirty pages to disk until done.
+	 */
+	next = 0;
+	i = 1;
+	do {
+		n = 0;
+		done = 1;
+		size = 0;
+		for (; i<=txn->mt_u.dirty_list[0].mid; i++) {
+			dp = txn->mt_u.dirty_list[i].mptr;
+			if (dp->p.mp_pgno != next) {
+				if (n) {
+					DPRINTF("committing %u dirty pages", n);
+					rc = writev(env->me_fd, iov, n);
+					if (rc != size) {
+						n = errno;
+						if (rc > 0)
+							DPUTS("short write, filesystem full?");
+						else
+							DPRINTF("writev: %s", strerror(errno));
+						mdb_txn_abort(txn);
+						return n;
+					}
+					n = 0;
+					size = 0;
+				}
+				lseek(env->me_fd, dp->p.mp_pgno * env->me_psize, SEEK_SET);
+				next = dp->p.mp_pgno;
+			}
+			DPRINTF("committing page %lu", dp->p.mp_pgno);
+			iov[n].iov_len = env->me_psize * dp->h.md_num;
+			iov[n].iov_base = &dp->p;
+			size += iov[n].iov_len;
+			next = dp->p.mp_pgno + dp->h.md_num;
+			/* clear dirty flag */
+			dp->p.mp_flags &= ~P_DIRTY;
+			if (++n >= MDB_COMMIT_PAGES) {
+				done = 0;
+				break;
+			}
+		}
+
+		if (n == 0)
+			break;
+
+		DPRINTF("committing %u dirty pages", n);
+		rc = writev(env->me_fd, iov, n);
+		if (rc != size) {
+			n = errno;
+			if (rc > 0)
+				DPUTS("short write, filesystem full?");
+			else
+				DPRINTF("writev: %s", strerror(errno));
+			mdb_txn_abort(txn);
+			return n;
+		}
+
+	} while (!done);
+
+	/* Drop the dirty pages.
+	 */
+	for (i=1; i<=txn->mt_u.dirty_list[0].mid; i++) {
+		dp = txn->mt_u.dirty_list[i].mptr;
+		if (dp->h.md_num == 1) {
+			dp->h.md_parent = (MDB_page *)txn->mt_env->me_dpages;
+			txn->mt_env->me_dpages = dp;
+		} else {
+			free(dp);
+		}
+		txn->mt_u.dirty_list[i].mid = 0;
+	}
+
+	if ((n = mdb_env_sync(env, 0)) != 0 ||
+	    (n = mdb_env_write_meta(txn)) != MDB_SUCCESS) {
+		mdb_txn_abort(txn);
+		return n;
+	}
+
+done:
+	env->me_txn = NULL;
+	/* update the DB tables */
+	{
+		int toggle = !env->me_db_toggle;
+
+		for (i = 2; i < env->me_numdbs; i++) {
+			if (txn->mt_dbxs[i].md_dirty) {
+				env->me_dbs[toggle][i] = txn->mt_dbs[i];
+				txn->mt_dbxs[i].md_dirty = 0;
+			}
+		}
+		for (i = env->me_numdbs; i < txn->mt_numdbs; i++) {
+			txn->mt_dbxs[i].md_dirty = 0;
+			env->me_dbxs[i] = txn->mt_dbxs[i];
+			env->me_dbs[toggle][i] = txn->mt_dbs[i];
+		}
+		env->me_db_toggle = toggle;
+		env->me_numdbs = txn->mt_numdbs;
+
+		free(txn->mt_dbs);
+	}
+
+	pthread_mutex_unlock(&env->me_txns->mti_wmutex);
+	free(txn);
+
+	return MDB_SUCCESS;
+}
+
+static int
+mdb_env_read_header(MDB_env *env, MDB_meta *meta)
+{
+	char		 page[PAGESIZE];
+	MDB_page	*p;
+	MDB_meta	*m;
+	int		 rc;
+
+	assert(env != NULL);
+
+	/* We don't know the page size yet, so use a minimum value.
+	 */
+
+	if ((rc = pread(env->me_fd, page, PAGESIZE, 0)) == 0) {
+		return ENOENT;
+	} else if (rc != PAGESIZE) {
+		if (rc > 0)
+			errno = EINVAL;
+		DPRINTF("read: %s", strerror(errno));
+		return errno;
+	}
+
+	p = (MDB_page *)page;
+
+	if (!F_ISSET(p->mp_flags, P_META)) {
+		DPRINTF("page %lu not a meta page", p->mp_pgno);
+		return EINVAL;
+	}
+
+	m = METADATA(p);
+	if (m->mm_magic != MDB_MAGIC) {
+		DPUTS("meta has invalid magic");
+		return EINVAL;
+	}
+
+	if (m->mm_version != MDB_VERSION) {
+		DPRINTF("database is version %u, expected version %u",
+		    m->mm_version, MDB_VERSION);
+		return MDB_VERSION_MISMATCH;
+	}
+
+	memcpy(meta, m, sizeof(*m));
+	return 0;
+}
+
+static int
+mdb_env_init_meta(MDB_env *env, MDB_meta *meta)
+{
+	MDB_page *p, *q;
+	MDB_meta *m;
+	int rc;
+	unsigned int	 psize;
+
+	DPUTS("writing new meta page");
+	psize = sysconf(_SC_PAGE_SIZE);
+
+	meta->mm_magic = MDB_MAGIC;
+	meta->mm_version = MDB_VERSION;
+	meta->mm_psize = psize;
+	meta->mm_last_pg = 1;
+	meta->mm_flags = env->me_flags & 0xffff;
+	meta->mm_flags |= MDB_INTEGERKEY;
+	meta->mm_dbs[0].md_root = P_INVALID;
+	meta->mm_dbs[1].md_root = P_INVALID;
+
+	p = calloc(2, psize);
+	p->mp_pgno = 0;
+	p->mp_flags = P_META;
+
+	m = METADATA(p);
+	memcpy(m, meta, sizeof(*meta));
+
+	q = (MDB_page *)((char *)p + psize);
+
+	q->mp_pgno = 1;
+	q->mp_flags = P_META;
+
+	m = METADATA(q);
+	memcpy(m, meta, sizeof(*meta));
+
+	rc = write(env->me_fd, p, psize * 2);
+	free(p);
+	return (rc == (int)psize * 2) ? MDB_SUCCESS : errno;
+}
+
+static int
+mdb_env_write_meta(MDB_txn *txn)
+{
+	MDB_env *env;
+	MDB_meta	meta, metab;
+	off_t off;
+	int rc, len, toggle;
+	char *ptr;
+
+	assert(txn != NULL);
+	assert(txn->mt_env != NULL);
+
+	toggle = !F_ISSET(txn->mt_flags, MDB_TXN_METOGGLE);
+	DPRINTF("writing meta page %d for root page %lu",
+		toggle, txn->mt_dbs[MAIN_DBI].md_root);
+
+	env = txn->mt_env;
+
+	metab.mm_txnid = env->me_metas[toggle]->mm_txnid;
+	metab.mm_last_pg = env->me_metas[toggle]->mm_last_pg;
+
+	ptr = (char *)&meta;
+	off = offsetof(MDB_meta, mm_dbs[0].md_depth);
+	len = sizeof(MDB_meta) - off;
+
+	ptr += off;
+	meta.mm_dbs[0] = txn->mt_dbs[0];
+	meta.mm_dbs[1] = txn->mt_dbs[1];
+	meta.mm_last_pg = txn->mt_next_pgno - 1;
+	meta.mm_txnid = txn->mt_txnid;
+
+	if (toggle)
+		off += env->me_psize;
+	off += PAGEHDRSZ;
+
+	/* Write to the SYNC fd */
+	rc = pwrite(env->me_mfd, ptr, len, off);
+	if (rc != len) {
+		int r2;
+		rc = errno;
+		DPUTS("write failed, disk error?");
+		/* On a failure, the pagecache still contains the new data.
+		 * Write some old data back, to prevent it from being used.
+		 * Use the non-SYNC fd; we know it will fail anyway.
+		 */
+		meta.mm_last_pg = metab.mm_last_pg;
+		meta.mm_txnid = metab.mm_txnid;
+		r2 = pwrite(env->me_fd, ptr, len, off);
+		env->me_flags |= MDB_FATAL_ERROR;
+		return rc;
+	}
+	txn->mt_env->me_txns->mti_me_toggle = toggle;
+
+	return MDB_SUCCESS;
+}
+
+static int
+mdb_env_read_meta(MDB_env *env, int *which)
+{
+	int toggle = 0;
+
+	assert(env != NULL);
+
+	if (which)
+		toggle = *which;
+	else if (env->me_metas[0]->mm_txnid < env->me_metas[1]->mm_txnid)
+		toggle = 1;
+
+	if (env->me_meta != env->me_metas[toggle])
+		env->me_meta = env->me_metas[toggle];
+
+	DPRINTF("Using meta page %d", toggle);
+
+	return MDB_SUCCESS;
+}
+
+int
+mdb_env_create(MDB_env **env)
+{
+	MDB_env *e;
+
+	e = calloc(1, sizeof(MDB_env));
+	if (!e) return ENOMEM;
+
+	e->me_maxreaders = DEFAULT_READERS;
+	e->me_maxdbs = 2;
+	e->me_fd = -1;
+	e->me_lfd = -1;
+	e->me_mfd = -1;
+	*env = e;
+	return MDB_SUCCESS;
+}
+
+int
+mdb_env_set_mapsize(MDB_env *env, size_t size)
+{
+	if (env->me_map)
+		return EINVAL;
+	env->me_mapsize = size;
+	return MDB_SUCCESS;
+}
+
+int
+mdb_env_set_maxdbs(MDB_env *env, int dbs)
+{
+	env->me_maxdbs = dbs;
+	return MDB_SUCCESS;
+}
+
+int
+mdb_env_set_maxreaders(MDB_env *env, int readers)
+{
+	env->me_maxreaders = readers;
+	return MDB_SUCCESS;
+}
+
+int
+mdb_env_get_maxreaders(MDB_env *env, int *readers)
+{
+	if (!env || !readers)
+		return EINVAL;
+	*readers = env->me_maxreaders;
+	return MDB_SUCCESS;
+}
+
+static int
+mdb_env_open2(MDB_env *env, unsigned int flags)
+{
+	int i, newenv = 0;
+	MDB_meta meta;
+	MDB_page *p;
+
+	env->me_flags = flags;
+
+	memset(&meta, 0, sizeof(meta));
+
+	if ((i = mdb_env_read_header(env, &meta)) != 0) {
+		if (i != ENOENT)
+			return i;
+		DPUTS("new mdbenv");
+		newenv = 1;
+	}
+
+	if (!env->me_mapsize) {
+		env->me_mapsize = newenv ? DEFAULT_MAPSIZE : meta.mm_mapsize;
+	}
+
+	i = MAP_SHARED;
+	if (meta.mm_address && (flags & MDB_FIXEDMAP))
+		i |= MAP_FIXED;
+	env->me_map = mmap(meta.mm_address, env->me_mapsize, PROT_READ, i,
+		env->me_fd, 0);
+	if (env->me_map == MAP_FAILED)
+		return errno;
+
+	if (newenv) {
+		meta.mm_mapsize = env->me_mapsize;
+		if (flags & MDB_FIXEDMAP)
+			meta.mm_address = env->me_map;
+		i = mdb_env_init_meta(env, &meta);
+		if (i != MDB_SUCCESS) {
+			munmap(env->me_map, env->me_mapsize);
+			return i;
+		}
+	}
+	env->me_psize = meta.mm_psize;
+
+	env->me_maxpg = env->me_mapsize / env->me_psize;
+
+	p = (MDB_page *)env->me_map;
+	env->me_metas[0] = METADATA(p);
+	env->me_metas[1] = (MDB_meta *)((char *)env->me_metas[0] + meta.mm_psize);
+
+	if ((i = mdb_env_read_meta(env, NULL)) != 0)
+		return i;
+
+	DPRINTF("opened database version %u, pagesize %u",
+	    env->me_meta->mm_version, env->me_psize);
+	DPRINTF("depth: %u", env->me_meta->mm_dbs[MAIN_DBI].md_depth);
+	DPRINTF("entries: %lu", env->me_meta->mm_dbs[MAIN_DBI].md_entries);
+	DPRINTF("branch pages: %lu", env->me_meta->mm_dbs[MAIN_DBI].md_branch_pages);
+	DPRINTF("leaf pages: %lu", env->me_meta->mm_dbs[MAIN_DBI].md_leaf_pages);
+	DPRINTF("overflow pages: %lu", env->me_meta->mm_dbs[MAIN_DBI].md_overflow_pages);
+	DPRINTF("root: %lu", env->me_meta->mm_dbs[MAIN_DBI].md_root);
+
+	return MDB_SUCCESS;
+}
+
+static void
+mdb_env_reader_dest(void *ptr)
+{
+	MDB_reader *reader = ptr;
+
+	reader->mr_txnid = 0;
+	reader->mr_pid = 0;
+	reader->mr_tid = 0;
+}
+
+/* downgrade the exclusive lock on the region back to shared */
+static void
+mdb_env_share_locks(MDB_env *env)
+{
+	struct flock lock_info;
+
+	env->me_txns->mti_txnid = env->me_meta->mm_txnid;
+	if (env->me_metas[0]->mm_txnid < env->me_metas[1]->mm_txnid)
+		env->me_txns->mti_me_toggle = 1;
+
+	memset((void *)&lock_info, 0, sizeof(lock_info));
+	lock_info.l_type = F_RDLCK;
+	lock_info.l_whence = SEEK_SET;
+	lock_info.l_start = 0;
+	lock_info.l_len = 1;
+	fcntl(env->me_lfd, F_SETLK, &lock_info);
+}
+
+static int
+mdb_env_setup_locks(MDB_env *env, char *lpath, int mode, int *excl)
+{
+	int rc;
+	off_t size, rsize;
+	struct flock lock_info;
+
+	*excl = 0;
+
+	if ((env->me_lfd = open(lpath, O_RDWR|O_CREAT, mode)) == -1) {
+		rc = errno;
+		return rc;
+	}
+	/* Try to get exclusive lock. If we succeed, then
+	 * nobody is using the lock region and we should initialize it.
+	 */
+	memset((void *)&lock_info, 0, sizeof(lock_info));
+	lock_info.l_type = F_WRLCK;
+	lock_info.l_whence = SEEK_SET;
+	lock_info.l_start = 0;
+	lock_info.l_len = 1;
+	rc = fcntl(env->me_lfd, F_SETLK, &lock_info);
+	if (rc == 0) {
+		*excl = 1;
+	} else {
+		lock_info.l_type = F_RDLCK;
+		rc = fcntl(env->me_lfd, F_SETLK, &lock_info);
+		if (rc) {
+			rc = errno;
+			goto fail;
+		}
+	}
+	size = lseek(env->me_lfd, 0, SEEK_END);
+	rsize = (env->me_maxreaders-1) * sizeof(MDB_reader) + sizeof(MDB_txninfo);
+	if (size < rsize && *excl) {
+		if (ftruncate(env->me_lfd, rsize) != 0) {
+			rc = errno;
+			goto fail;
+		}
+	} else {
+		rsize = size;
+		size = rsize - sizeof(MDB_txninfo);
+		env->me_maxreaders = size/sizeof(MDB_reader) + 1;
+	}
+	env->me_txns = mmap(0, rsize, PROT_READ|PROT_WRITE, MAP_SHARED,
+		env->me_lfd, 0);
+	if (env->me_txns == MAP_FAILED) {
+		rc = errno;
+		goto fail;
+	}
+	if (*excl) {
+		pthread_mutexattr_t mattr;
+
+		pthread_mutexattr_init(&mattr);
+		rc = pthread_mutexattr_setpshared(&mattr, PTHREAD_PROCESS_SHARED);
+		if (rc) {
+			goto fail;
+		}
+		pthread_mutex_init(&env->me_txns->mti_mutex, &mattr);
+		pthread_mutex_init(&env->me_txns->mti_wmutex, &mattr);
+		env->me_txns->mti_version = MDB_VERSION;
+		env->me_txns->mti_magic = MDB_MAGIC;
+		env->me_txns->mti_txnid = 0;
+		env->me_txns->mti_numreaders = 0;
+		env->me_txns->mti_me_toggle = 0;
+
+	} else {
+		if (env->me_txns->mti_magic != MDB_MAGIC) {
+			DPUTS("lock region has invalid magic");
+			rc = EINVAL;
+			goto fail;
+		}
+		if (env->me_txns->mti_version != MDB_VERSION) {
+			DPRINTF("lock region is version %u, expected version %u",
+				env->me_txns->mti_version, MDB_VERSION);
+			rc = MDB_VERSION_MISMATCH;
+			goto fail;
+		}
+		if (errno != EACCES && errno != EAGAIN) {
+			rc = errno;
+			goto fail;
+		}
+	}
+	return MDB_SUCCESS;
+
+fail:
+	close(env->me_lfd);
+	env->me_lfd = -1;
+	return rc;
+
+}
+
+#define LOCKNAME	"/lock.mdb"
+#define DATANAME	"/data.mdb"
+int
+mdb_env_open(MDB_env *env, const char *path, unsigned int flags, mode_t mode)
+{
+	int		oflags, rc, len, excl;
+	char *lpath, *dpath;
+
+	len = strlen(path);
+	lpath = malloc(len + sizeof(LOCKNAME) + len + sizeof(DATANAME));
+	if (!lpath)
+		return ENOMEM;
+	dpath = lpath + len + sizeof(LOCKNAME);
+	sprintf(lpath, "%s" LOCKNAME, path);
+	sprintf(dpath, "%s" DATANAME, path);
+
+	rc = mdb_env_setup_locks(env, lpath, mode, &excl);
+	if (rc)
+		goto leave;
+
+	if (F_ISSET(flags, MDB_RDONLY))
+		oflags = O_RDONLY;
+	else
+		oflags = O_RDWR | O_CREAT;
+
+	if ((env->me_fd = open(dpath, oflags, mode)) == -1) {
+		rc = errno;
+		goto leave;
+	}
+
+	if ((rc = mdb_env_open2(env, flags)) == MDB_SUCCESS) {
+		/* synchronous fd for meta writes */
+		if (!(flags & (MDB_RDONLY|MDB_NOSYNC)))
+			oflags |= MDB_DSYNC;
+		if ((env->me_mfd = open(dpath, oflags, mode)) == -1) {
+			rc = errno;
+			goto leave;
+		}
+
+		env->me_path = strdup(path);
+		DPRINTF("opened dbenv %p", (void *) env);
+		pthread_key_create(&env->me_txkey, mdb_env_reader_dest);
+		if (excl)
+			mdb_env_share_locks(env);
+		env->me_dbxs = calloc(env->me_maxdbs, sizeof(MDB_dbx));
+		env->me_dbs[0] = calloc(env->me_maxdbs, sizeof(MDB_db));
+		env->me_dbs[1] = calloc(env->me_maxdbs, sizeof(MDB_db));
+		env->me_numdbs = 2;
+	}
+
+leave:
+	if (rc) {
+		if (env->me_fd >= 0) {
+			close(env->me_fd);
+			env->me_fd = -1;
+		}
+		if (env->me_lfd >= 0) {
+			close(env->me_lfd);
+			env->me_lfd = -1;
+		}
+	}
+	free(lpath);
+	return rc;
+}
+
+void
+mdb_env_close(MDB_env *env)
+{
+	MDB_dpage *dp;
+
+	if (env == NULL)
+		return;
+
+	while (env->me_dpages) {
+		dp = env->me_dpages;
+		env->me_dpages = (MDB_dpage *)dp->h.md_parent;
+		free(dp);
+	}
+
+	free(env->me_dbs[1]);
+	free(env->me_dbs[0]);
+	free(env->me_dbxs);
+	free(env->me_path);
+
+	pthread_key_delete(env->me_txkey);
+
+	if (env->me_map) {
+		munmap(env->me_map, env->me_mapsize);
+	}
+	close(env->me_mfd);
+	close(env->me_fd);
+	if (env->me_txns) {
+		pid_t pid = getpid();
+		size_t size = (env->me_maxreaders-1) * sizeof(MDB_reader) + sizeof(MDB_txninfo);
+		int i;
+		for (i=0; i<env->me_txns->mti_numreaders; i++)
+			if (env->me_txns->mti_readers[i].mr_pid == pid)
+				env->me_txns->mti_readers[i].mr_pid = 0;
+		munmap(env->me_txns, size);
+	}
+	close(env->me_lfd);
+	free(env);
+}
+
+/* Search for key within a leaf page, using binary search.
+ * Returns the smallest entry larger or equal to the key.
+ * If exactp is non-null, stores whether the found entry was an exact match
+ * in *exactp (1 or 0).
+ * If kip is non-null, stores the index of the found entry in *kip.
+ * If no entry larger or equal to the key is found, returns NULL.
+ */
+static MDB_node *
+mdb_search_node(MDB_txn *txn, MDB_dbi dbi, MDB_page *mp, MDB_val *key,
+    int *exactp, unsigned int *kip)
+{
+	unsigned int	 i = 0;
+	int		 low, high;
+	int		 rc = 0;
+	MDB_node	*node = NULL;
+	MDB_val	 nodekey;
+	DKBUF;
+
+	DPRINTF("searching %u keys in %s page %lu",
+	    NUMKEYS(mp),
+	    IS_LEAF(mp) ? "leaf" : "branch",
+	    mp->mp_pgno);
+
+	assert(NUMKEYS(mp) > 0);
+
+	memset(&nodekey, 0, sizeof(nodekey));
+
+	low = IS_LEAF(mp) ? 0 : 1;
+	high = NUMKEYS(mp) - 1;
+	while (low <= high) {
+		i = (low + high) >> 1;
+
+		if (IS_LEAF2(mp)) {
+			nodekey.mv_size = txn->mt_dbs[dbi].md_pad;
+			nodekey.mv_data = LEAF2KEY(mp, i, nodekey.mv_size);
+		} else {
+			node = NODEPTR(mp, i);
+
+			nodekey.mv_size = node->mn_ksize;
+			nodekey.mv_data = NODEKEY(node);
+		}
+
+		rc = mdb_cmp(txn, dbi, key, &nodekey);
+
+		if (IS_LEAF(mp))
+			DPRINTF("found leaf index %u [%s], rc = %i",
+			    i, DKEY(&nodekey), rc);
+		else
+			DPRINTF("found branch index %u [%s -> %lu], rc = %i",
+			    i, DKEY(&nodekey), NODEPGNO(node), rc);
+
+		if (rc == 0)
+			break;
+		if (rc > 0)
+			low = i + 1;
+		else
+			high = i - 1;
+	}
+
+	if (rc > 0) {	/* Found entry is less than the key. */
+		i++;	/* Skip to get the smallest entry larger than key. */
+		if (i >= NUMKEYS(mp))
+			/* There is no entry larger or equal to the key. */
+			return NULL;
+	}
+	if (exactp)
+		*exactp = (rc == 0);
+	if (kip)	/* Store the key index if requested. */
+		*kip = i;
+
+	/* nodeptr is fake for LEAF2 */
+	return IS_LEAF2(mp) ? NODEPTR(mp, 0) : NODEPTR(mp, i);
+}
+
+static void
+cursor_pop_page(MDB_cursor *cursor)
+{
+	MDB_ppage	*top;
+
+	if (cursor->mc_snum) {
+		top = CURSOR_TOP(cursor);
+		cursor->mc_snum--;
+
+		DPRINTF("popped page %lu off db %u cursor %p", top->mp_page->mp_pgno,
+			cursor->mc_dbi, (void *) cursor);
+	}
+}
+
+static MDB_ppage *
+cursor_push_page(MDB_cursor *cursor, MDB_page *mp)
+{
+	MDB_ppage	*ppage;
+
+	DPRINTF("pushing page %lu on db %u cursor %p", mp->mp_pgno,
+		cursor->mc_dbi, (void *) cursor);
+
+	ppage = &cursor->mc_stack[cursor->mc_snum++];
+	ppage->mp_page = mp;
+	ppage->mp_ki = 0;
+	return ppage;
+}
+
+static MDB_page *
+mdb_get_page(MDB_txn *txn, pgno_t pgno)
+{
+	MDB_page *p = NULL;
+	int found = 0;
+
+	if (!F_ISSET(txn->mt_flags, MDB_TXN_RDONLY) && txn->mt_u.dirty_list[0].mid) {
+		MDB_dpage *dp;
+		MIDL2 id;
+		unsigned x;
+		id.mid = pgno;
+		x = mdb_midl2_search(txn->mt_u.dirty_list, &id);
+		if (x <= txn->mt_u.dirty_list[0].mid && txn->mt_u.dirty_list[x].mid == pgno) {
+			dp = txn->mt_u.dirty_list[x].mptr;
+			p = &dp->p;
+			found = 1;
+		}
+	}
+	if (!found) {
+		if (pgno > txn->mt_env->me_meta->mm_last_pg)
+			return NULL;
+		p = (MDB_page *)(txn->mt_env->me_map + txn->mt_env->me_psize * pgno);
+	}
+	return p;
+}
+
+static int
+mdb_search_page_root(MDB_txn *txn, MDB_dbi dbi, MDB_val *key,
+    MDB_cursor *cursor, int modify, MDB_pageparent *mpp)
+{
+	MDB_page	*mp = mpp->mp_page;
+	DKBUF;
+	int rc;
+
+	if (cursor && cursor_push_page(cursor, mp) == NULL)
+		return ENOMEM;
+
+	while (IS_BRANCH(mp)) {
+		unsigned int	 i = 0;
+		MDB_node	*node;
+
+		DPRINTF("branch page %lu has %u keys", mp->mp_pgno, NUMKEYS(mp));
+		assert(NUMKEYS(mp) > 1);
+		DPRINTF("found index 0 to page %lu", NODEPGNO(NODEPTR(mp, 0)));
+
+		if (key == NULL)	/* Initialize cursor to first page. */
+			i = 0;
+		else if (key->mv_size > MAXKEYSIZE && key->mv_data == NULL) {
+							/* cursor to last page */
+			i = NUMKEYS(mp)-1;
+		} else {
+			int	 exact;
+			node = mdb_search_node(txn, dbi, mp, key, &exact, &i);
+			if (node == NULL)
+				i = NUMKEYS(mp) - 1;
+			else if (!exact) {
+				assert(i > 0);
+				i--;
+			}
+		}
+
+		if (key)
+			DPRINTF("following index %u for key [%s]",
+			    i, DKEY(key));
+		assert(i < NUMKEYS(mp));
+		node = NODEPTR(mp, i);
+
+		if (cursor)
+			CURSOR_TOP(cursor)->mp_ki = i;
+
+		mpp->mp_parent = mp;
+		if ((mp = mdb_get_page(txn, NODEPGNO(node))) == NULL)
+			return MDB_PAGE_NOTFOUND;
+		mpp->mp_pi = i;
+		mpp->mp_page = mp;
+
+		if (cursor && cursor_push_page(cursor, mp) == NULL)
+			return ENOMEM;
+
+		if (modify) {
+			MDB_dhead *dh = ((MDB_dhead *)mp)-1;
+			if ((rc = mdb_touch(txn, mpp)) != 0)
+				return rc;
+			dh = ((MDB_dhead *)mpp->mp_page)-1;
+			dh->md_parent = mpp->mp_parent;
+			dh->md_pi = mpp->mp_pi;
+		}
+
+		mp = mpp->mp_page;
+	}
+
+	if (!IS_LEAF(mp)) {
+		DPRINTF("internal error, index points to a %02X page!?",
+		    mp->mp_flags);
+		return MDB_CORRUPTED;
+	}
+
+	DPRINTF("found leaf page %lu for key [%s]", mp->mp_pgno,
+	    key ? DKEY(key) : NULL);
+
+	return MDB_SUCCESS;
+}
+
+/* Search for the page a given key should be in.
+ * Stores a pointer to the found page in *mpp.
+ * If key is NULL, search for the lowest page (used by mdb_cursor_first).
+ * If cursor is non-null, pushes parent pages on the cursor stack.
+ * If modify is true, visited pages are updated with new page numbers.
+ */
+static int
+mdb_search_page(MDB_txn *txn, MDB_dbi dbi, MDB_val *key,
+    MDB_cursor *cursor, int modify, MDB_pageparent *mpp)
+{
+	int		 rc;
+	pgno_t		 root;
+
+	/* Choose which root page to start with. If a transaction is given
+	 * use the root page from the transaction, otherwise read the last
+	 * committed root page.
+	 */
+	if (F_ISSET(txn->mt_flags, MDB_TXN_ERROR)) {
+		DPUTS("transaction has failed, must abort");
+		return EINVAL;
+	} else
+		root = txn->mt_dbs[dbi].md_root;
+
+	if (root == P_INVALID) {		/* Tree is empty. */
+		DPUTS("tree is empty");
+		return MDB_NOTFOUND;
+	}
+
+	if ((mpp->mp_page = mdb_get_page(txn, root)) == NULL)
+		return MDB_PAGE_NOTFOUND;
+
+	DPRINTF("root page has flags 0x%X", mpp->mp_page->mp_flags);
+
+	if (modify) {
+		/* For sub-databases, update main root first */
+		if (dbi > MAIN_DBI && !txn->mt_dbxs[dbi].md_dirty) {
+			MDB_pageparent mp2;
+			rc = mdb_search_page(txn, MAIN_DBI, &txn->mt_dbxs[dbi].md_name,
+				NULL, 1, &mp2);
+			if (rc)
+				return rc;
+			txn->mt_dbxs[dbi].md_dirty = 1;
+		}
+		if (!F_ISSET(mpp->mp_page->mp_flags, P_DIRTY)) {
+			mpp->mp_parent = NULL;
+			mpp->mp_pi = 0;
+			if ((rc = mdb_touch(txn, mpp)))
+				return rc;
+			txn->mt_dbs[dbi].md_root = mpp->mp_page->mp_pgno;
+		}
+	}
+
+	return mdb_search_page_root(txn, dbi, key, cursor, modify, mpp);
+}
+
+static int
+mdb_read_data(MDB_txn *txn, MDB_node *leaf, MDB_val *data)
+{
+	MDB_page	*omp;		/* overflow mpage */
+	pgno_t		 pgno;
+
+	if (!F_ISSET(leaf->mn_flags, F_BIGDATA)) {
+		data->mv_size = leaf->mn_dsize;
+		data->mv_data = NODEDATA(leaf);
+		return MDB_SUCCESS;
+	}
+
+	/* Read overflow data.
+	 */
+	data->mv_size = leaf->mn_dsize;
+	memcpy(&pgno, NODEDATA(leaf), sizeof(pgno));
+	if ((omp = mdb_get_page(txn, pgno)) == NULL) {
+		DPRINTF("read overflow page %lu failed", pgno);
+		return MDB_PAGE_NOTFOUND;
+	}
+	data->mv_data = METADATA(omp);
+
+	return MDB_SUCCESS;
+}
+
+int
+mdb_get(MDB_txn *txn, MDB_dbi dbi,
+    MDB_val *key, MDB_val *data)
+{
+	int		 rc, exact;
+	MDB_node	*leaf;
+	MDB_pageparent mpp;
+	DKBUF;
+
+	assert(key);
+	assert(data);
+	DPRINTF("===> get db %u key [%s]", dbi, DKEY(key));
+
+	if (txn == NULL || !dbi || dbi >= txn->mt_numdbs)
+		return EINVAL;
+
+	if (key->mv_size == 0 || key->mv_size > MAXKEYSIZE) {
+		return EINVAL;
+	}
+
+	if ((rc = mdb_search_page(txn, dbi, key, NULL, 0, &mpp)) != MDB_SUCCESS)
+		return rc;
+
+	leaf = mdb_search_node(txn, dbi, mpp.mp_page, key, &exact, NULL);
+	if (leaf && exact) {
+		/* Return first duplicate data item */
+		if (F_ISSET(leaf->mn_flags, F_DUPDATA)) {
+			MDB_xcursor mx;
+
+			mdb_xcursor_init0(txn, dbi, &mx);
+			mdb_xcursor_init1(txn, dbi, &mx, leaf);
+			rc = mdb_search_page(&mx.mx_txn, mx.mx_cursor.mc_dbi, NULL, NULL, 0, &mpp);
+			if (rc != MDB_SUCCESS)
+				return rc;
+			if (IS_LEAF2(mpp.mp_page)) {
+				data->mv_size = txn->mt_dbs[dbi].md_pad;
+				data->mv_data = LEAF2KEY(mpp.mp_page, 0, data->mv_size);
+			} else {
+				leaf = NODEPTR(mpp.mp_page, 0);
+				data->mv_size = NODEKSZ(leaf);
+				data->mv_data = NODEKEY(leaf);
+			}
+		} else {
+			rc = mdb_read_data(txn, leaf, data);
+		}
+	} else {
+		rc = MDB_NOTFOUND;
+	}
+
+	return rc;
+}
+
+static int
+mdb_sibling(MDB_cursor *cursor, int move_right)
+{
+	int		 rc;
+	MDB_node	*indx;
+	MDB_ppage	*parent;
+	MDB_page	*mp;
+
+	if (cursor->mc_snum < 2) {
+		return MDB_NOTFOUND;		/* root has no siblings */
+	}
+	parent = CURSOR_PARENT(cursor);
+
+	DPRINTF("parent page is page %lu, index %u",
+	    parent->mp_page->mp_pgno, parent->mp_ki);
+
+	cursor_pop_page(cursor);
+	if (move_right ? (parent->mp_ki + 1 >= NUMKEYS(parent->mp_page))
+		       : (parent->mp_ki == 0)) {
+		DPRINTF("no more keys left, moving to %s sibling",
+		    move_right ? "right" : "left");
+		if ((rc = mdb_sibling(cursor, move_right)) != MDB_SUCCESS)
+			return rc;
+		parent = CURSOR_TOP(cursor);
+	} else {
+		if (move_right)
+			parent->mp_ki++;
+		else
+			parent->mp_ki--;
+		DPRINTF("just moving to %s index key %u",
+		    move_right ? "right" : "left", parent->mp_ki);
+	}
+	assert(IS_BRANCH(parent->mp_page));
+
+	indx = NODEPTR(parent->mp_page, parent->mp_ki);
+	if ((mp = mdb_get_page(cursor->mc_txn, NODEPGNO(indx))) == NULL)
+		return MDB_PAGE_NOTFOUND;
+#if 0
+	mp->parent = parent->mp_page;
+	mp->parent_index = parent->mp_ki;
+#endif
+
+	cursor_push_page(cursor, mp);
+
+	return MDB_SUCCESS;
+}
+
+static int
+mdb_cursor_next(MDB_cursor *cursor, MDB_val *key, MDB_val *data, MDB_cursor_op op)
+{
+	MDB_ppage	*top;
+	MDB_page	*mp;
+	MDB_node	*leaf;
+	int rc;
+
+	if (cursor->mc_eof) {
+		return MDB_NOTFOUND;
+	}
+
+	assert(cursor->mc_initialized);
+
+	top = CURSOR_TOP(cursor);
+	mp = top->mp_page;
+
+	if (cursor->mc_txn->mt_dbs[cursor->mc_dbi].md_flags & MDB_DUPSORT) {
+		leaf = NODEPTR(mp, top->mp_ki);
+		if (F_ISSET(leaf->mn_flags, F_DUPDATA)) {
+			if (op == MDB_NEXT || op == MDB_NEXT_DUP) {
+				rc = mdb_cursor_next(&cursor->mc_xcursor->mx_cursor, data, NULL, MDB_NEXT);
+				if (op != MDB_NEXT || rc == MDB_SUCCESS)
+					return rc;
+			}
+		} else {
+			cursor->mc_xcursor->mx_cursor.mc_initialized = 0;
+			if (op == MDB_NEXT_DUP)
+				return MDB_NOTFOUND;
+		}
+	}
+
+	DPRINTF("cursor_next: top page is %lu in cursor %p", mp->mp_pgno, (void *) cursor);
+
+	if (top->mp_ki + 1 >= NUMKEYS(mp)) {
+		DPUTS("=====> move to next sibling page");
+		if (mdb_sibling(cursor, 1) != MDB_SUCCESS) {
+			cursor->mc_eof = 1;
+			return MDB_NOTFOUND;
+		}
+		top = CURSOR_TOP(cursor);
+		mp = top->mp_page;
+		DPRINTF("next page is %lu, key index %u", mp->mp_pgno, top->mp_ki);
+	} else
+		top->mp_ki++;
+
+	DPRINTF("==> cursor points to page %lu with %u keys, key index %u",
+	    mp->mp_pgno, NUMKEYS(mp), top->mp_ki);
+
+	if (IS_LEAF2(mp)) {
+		key->mv_size = cursor->mc_txn->mt_dbs[cursor->mc_dbi].md_pad;
+		key->mv_data = LEAF2KEY(mp, top->mp_ki, key->mv_size);
+		return MDB_SUCCESS;
+	}
+
+	assert(IS_LEAF(mp));
+	leaf = NODEPTR(mp, top->mp_ki);
+
+	if (F_ISSET(leaf->mn_flags, F_DUPDATA)) {
+		mdb_xcursor_init1(cursor->mc_txn, cursor->mc_dbi, cursor->mc_xcursor, leaf);
+	}
+	if (data) {
+		if ((rc = mdb_read_data(cursor->mc_txn, leaf, data) != MDB_SUCCESS))
+			return rc;
+
+		if (F_ISSET(leaf->mn_flags, F_DUPDATA)) {
+			rc = mdb_cursor_first(&cursor->mc_xcursor->mx_cursor, data, NULL);
+			if (rc != MDB_SUCCESS)
+				return rc;
+		}
+	}
+
+	MDB_SET_KEY(leaf, key);
+	return MDB_SUCCESS;
+}
+
+static int
+mdb_cursor_prev(MDB_cursor *cursor, MDB_val *key, MDB_val *data, MDB_cursor_op op)
+{
+	MDB_ppage	*top;
+	MDB_page	*mp;
+	MDB_node	*leaf;
+	int rc;
+
+	assert(cursor->mc_initialized);
+
+	top = CURSOR_TOP(cursor);
+	mp = top->mp_page;
+
+	if (cursor->mc_txn->mt_dbs[cursor->mc_dbi].md_flags & MDB_DUPSORT) {
+		leaf = NODEPTR(mp, top->mp_ki);
+		if (op == MDB_PREV || op == MDB_PREV_DUP) {
+			if (F_ISSET(leaf->mn_flags, F_DUPDATA)) {
+				rc = mdb_cursor_prev(&cursor->mc_xcursor->mx_cursor, data, NULL, MDB_PREV);
+				if (op != MDB_PREV || rc == MDB_SUCCESS)
+					return rc;
+			} else {
+				cursor->mc_xcursor->mx_cursor.mc_initialized = 0;
+				if (op == MDB_PREV_DUP)
+					return MDB_NOTFOUND;
+			}
+		}
+	}
+
+	DPRINTF("cursor_prev: top page is %lu in cursor %p", mp->mp_pgno, (void *) cursor);
+
+	if (top->mp_ki == 0)  {
+		DPUTS("=====> move to prev sibling page");
+		if (mdb_sibling(cursor, 0) != MDB_SUCCESS) {
+			cursor->mc_initialized = 0;
+			return MDB_NOTFOUND;
+		}
+		top = CURSOR_TOP(cursor);
+		mp = top->mp_page;
+		top->mp_ki = NUMKEYS(mp) - 1;
+		DPRINTF("prev page is %lu, key index %u", mp->mp_pgno, top->mp_ki);
+	} else
+		top->mp_ki--;
+
+	cursor->mc_eof = 0;
+
+	DPRINTF("==> cursor points to page %lu with %u keys, key index %u",
+	    mp->mp_pgno, NUMKEYS(mp), top->mp_ki);
+
+	if (IS_LEAF2(mp)) {
+		key->mv_size = cursor->mc_txn->mt_dbs[cursor->mc_dbi].md_pad;
+		key->mv_data = LEAF2KEY(mp, top->mp_ki, key->mv_size);
+		return MDB_SUCCESS;
+	}
+
+	assert(IS_LEAF(mp));
+	leaf = NODEPTR(mp, top->mp_ki);
+
+	if (F_ISSET(leaf->mn_flags, F_DUPDATA)) {
+		mdb_xcursor_init1(cursor->mc_txn, cursor->mc_dbi, cursor->mc_xcursor, leaf);
+	}
+	if (data) {
+		if ((rc = mdb_read_data(cursor->mc_txn, leaf, data) != MDB_SUCCESS))
+			return rc;
+
+		if (F_ISSET(leaf->mn_flags, F_DUPDATA)) {
+			rc = mdb_cursor_last(&cursor->mc_xcursor->mx_cursor, data, NULL);
+			if (rc != MDB_SUCCESS)
+				return rc;
+		}
+	}
+
+	MDB_SET_KEY(leaf, key);
+	return MDB_SUCCESS;
+}
+
+static int
+mdb_cursor_set(MDB_cursor *cursor, MDB_val *key, MDB_val *data,
+    MDB_cursor_op op, int *exactp)
+{
+	int		 rc;
+	MDB_node	*leaf;
+	MDB_ppage	*top;
+	MDB_pageparent mpp;
+	DKBUF;
+
+	assert(cursor);
+	assert(key);
+	assert(key->mv_size > 0);
+
+	/* See if we're already on the right page */
+	if (cursor->mc_initialized) {
+		MDB_val nodekey;
+		top = CURSOR_TOP(cursor);
+		/* Don't try this for LEAF2 pages. Maybe support that later. */
+		if ((top->mp_page->mp_flags & (P_LEAF|P_LEAF2)) == P_LEAF) {
+			leaf = NODEPTR(top->mp_page, 0);
+			MDB_SET_KEY(leaf, &nodekey);
+			rc = mdb_cmp(cursor->mc_txn, cursor->mc_dbi, key, &nodekey);
+			if (rc >= 0) {
+				leaf = NODEPTR(top->mp_page, NUMKEYS(top->mp_page)-1);
+				MDB_SET_KEY(leaf, &nodekey);
+				rc = mdb_cmp(cursor->mc_txn, cursor->mc_dbi, key, &nodekey);
+				if (rc <= 0) {
+					/* we're already on the right page */
+					mpp.mp_page = top->mp_page;
+					rc = 0;
+					goto set2;
+				}
+			}
+		}
+	}
+	cursor->mc_snum = 0;
+
+	rc = mdb_search_page(cursor->mc_txn, cursor->mc_dbi, key, cursor, 0, &mpp);
+	if (rc != MDB_SUCCESS)
+		return rc;
+
+	assert(IS_LEAF(mpp.mp_page));
+
+	top = CURSOR_TOP(cursor);
+set2:
+	leaf = mdb_search_node(cursor->mc_txn, cursor->mc_dbi, mpp.mp_page, key, exactp, &top->mp_ki);
+	if (exactp != NULL && !*exactp) {
+		/* MDB_SET specified and not an exact match. */
+		return MDB_NOTFOUND;
+	}
+
+	if (leaf == NULL) {
+		DPUTS("===> inexact leaf not found, goto sibling");
+		if ((rc = mdb_sibling(cursor, 1)) != MDB_SUCCESS)
+			return rc;		/* no entries matched */
+		top = CURSOR_TOP(cursor);
+		top->mp_ki = 0;
+		mpp.mp_page = top->mp_page;
+		assert(IS_LEAF(mpp.mp_page));
+		leaf = NODEPTR(mpp.mp_page, 0);
+	}
+
+	cursor->mc_initialized = 1;
+	cursor->mc_eof = 0;
+
+	if (IS_LEAF2(mpp.mp_page)) {
+		key->mv_size = cursor->mc_txn->mt_dbs[cursor->mc_dbi].md_pad;
+		key->mv_data = LEAF2KEY(mpp.mp_page, top->mp_ki, key->mv_size);
+		return MDB_SUCCESS;
+	}
+
+	if (F_ISSET(leaf->mn_flags, F_DUPDATA)) {
+		mdb_xcursor_init1(cursor->mc_txn, cursor->mc_dbi, cursor->mc_xcursor, leaf);
+	}
+	if (data) {
+		if (F_ISSET(leaf->mn_flags, F_DUPDATA)) {
+			if (op == MDB_SET || op == MDB_SET_RANGE) {
+				rc = mdb_cursor_first(&cursor->mc_xcursor->mx_cursor, data, NULL);
+			} else {
+				int ex2, *ex2p;
+				if (op == MDB_GET_BOTH) {
+					ex2p = &ex2;
+				} else {
+					ex2p = NULL;
+				}
+				rc = mdb_cursor_set(&cursor->mc_xcursor->mx_cursor, data, NULL, MDB_SET_RANGE, ex2p);
+				if (rc != MDB_SUCCESS)
+					return rc;
+			}
+		} else if (op == MDB_GET_BOTH || op == MDB_GET_BOTH_RANGE) {
+			MDB_val d2;
+			if ((rc = mdb_read_data(cursor->mc_txn, leaf, &d2)) != MDB_SUCCESS)
+				return rc;
+			rc = mdb_dcmp(cursor->mc_txn, cursor->mc_dbi, data, &d2);
+			if (rc) {
+				if (op == MDB_GET_BOTH || rc > 0)
+					return MDB_NOTFOUND;
+			}
+
+		} else {
+			if ((rc = mdb_read_data(cursor->mc_txn, leaf, data)) != MDB_SUCCESS)
+				return rc;
+		}
+	}
+
+	/* The key already matches in all other cases */
+	if (op == MDB_SET_RANGE)
+		MDB_SET_KEY(leaf, key);
+	DPRINTF("==> cursor placed on key [%s]", DKEY(key));
+
+	return rc;
+}
+
+static int
+mdb_cursor_first(MDB_cursor *cursor, MDB_val *key, MDB_val *data)
+{
+	int		 rc;
+	MDB_pageparent	mpp;
+	MDB_node	*leaf;
+
+	cursor->mc_snum = 0;
+
+	rc = mdb_search_page(cursor->mc_txn, cursor->mc_dbi, NULL, cursor, 0, &mpp);
+	if (rc != MDB_SUCCESS)
+		return rc;
+	assert(IS_LEAF(mpp.mp_page));
+
+	leaf = NODEPTR(mpp.mp_page, 0);
+	cursor->mc_initialized = 1;
+	cursor->mc_eof = 0;
+
+	if (IS_LEAF2(mpp.mp_page)) {
+		key->mv_size = cursor->mc_txn->mt_dbs[cursor->mc_dbi].md_pad;
+		key->mv_data = LEAF2KEY(mpp.mp_page, 0, key->mv_size);
+		return MDB_SUCCESS;
+	}
+
+	if (data) {
+		if (F_ISSET(leaf->mn_flags, F_DUPDATA)) {
+			mdb_xcursor_init1(cursor->mc_txn, cursor->mc_dbi, cursor->mc_xcursor, leaf);
+			rc = mdb_cursor_first(&cursor->mc_xcursor->mx_cursor, data, NULL);
+			if (rc)
+				return rc;
+		} else {
+			if (cursor->mc_xcursor)
+				cursor->mc_xcursor->mx_cursor.mc_initialized = 0;
+			if ((rc = mdb_read_data(cursor->mc_txn, leaf, data)) != MDB_SUCCESS)
+				return rc;
+		}
+	}
+	MDB_SET_KEY(leaf, key);
+	return MDB_SUCCESS;
+}
+
+static int
+mdb_cursor_last(MDB_cursor *cursor, MDB_val *key, MDB_val *data)
+{
+	int		 rc;
+	MDB_ppage	*top;
+	MDB_pageparent	mpp;
+	MDB_node	*leaf;
+	MDB_val	lkey;
+
+	cursor->mc_snum = 0;
+
+	lkey.mv_size = MAXKEYSIZE+1;
+	lkey.mv_data = NULL;
+
+	rc = mdb_search_page(cursor->mc_txn, cursor->mc_dbi, &lkey, cursor, 0, &mpp);
+	if (rc != MDB_SUCCESS)
+		return rc;
+	assert(IS_LEAF(mpp.mp_page));
+
+	leaf = NODEPTR(mpp.mp_page, NUMKEYS(mpp.mp_page)-1);
+	cursor->mc_initialized = 1;
+	cursor->mc_eof = 0;
+
+	top = CURSOR_TOP(cursor);
+	top->mp_ki = NUMKEYS(top->mp_page) - 1;
+
+	if (IS_LEAF2(mpp.mp_page)) {
+		key->mv_size = cursor->mc_txn->mt_dbs[cursor->mc_dbi].md_pad;
+		key->mv_data = LEAF2KEY(mpp.mp_page, top->mp_ki, key->mv_size);
+		return MDB_SUCCESS;
+	}
+
+	if (data) {
+		if (F_ISSET(leaf->mn_flags, F_DUPDATA)) {
+			mdb_xcursor_init1(cursor->mc_txn, cursor->mc_dbi, cursor->mc_xcursor, leaf);
+			rc = mdb_cursor_last(&cursor->mc_xcursor->mx_cursor, data, NULL);
+			if (rc)
+				return rc;
+		} else {
+			if ((rc = mdb_read_data(cursor->mc_txn, leaf, data)) != MDB_SUCCESS)
+				return rc;
+		}
+	}
+
+	MDB_SET_KEY(leaf, key);
+	return MDB_SUCCESS;
+}
+
+int
+mdb_cursor_get(MDB_cursor *cursor, MDB_val *key, MDB_val *data,
+    MDB_cursor_op op)
+{
+	int		 rc;
+	int		 exact = 0;
+
+	assert(cursor);
+
+	switch (op) {
+	case MDB_GET_BOTH:
+	case MDB_GET_BOTH_RANGE:
+		if (data == NULL || cursor->mc_xcursor == NULL) {
+			rc = EINVAL;
+			break;
+		}
+		/* FALLTHRU */
+	case MDB_SET:
+	case MDB_SET_RANGE:
+		if (key == NULL || key->mv_size == 0 || key->mv_size > MAXKEYSIZE) {
+			rc = EINVAL;
+		} else if (op == MDB_SET_RANGE)
+			rc = mdb_cursor_set(cursor, key, data, op, NULL);
+		else
+			rc = mdb_cursor_set(cursor, key, data, op, &exact);
+		break;
+	case MDB_GET_MULTIPLE:
+		if (data == NULL ||
+			!(cursor->mc_txn->mt_dbs[cursor->mc_dbi].md_flags & MDB_DUPFIXED) ||
+			!cursor->mc_initialized) {
+			rc = EINVAL;
+			break;
+		}
+		rc = MDB_SUCCESS;
+		if (!cursor->mc_xcursor->mx_cursor.mc_initialized || cursor->mc_xcursor->mx_cursor.mc_eof)
+			break;
+		goto fetchm;
+	case MDB_NEXT_MULTIPLE:
+		if (data == NULL ||
+			!(cursor->mc_txn->mt_dbs[cursor->mc_dbi].md_flags & MDB_DUPFIXED)) {
+			rc = EINVAL;
+			break;
+		}
+		if (!cursor->mc_initialized)
+			rc = mdb_cursor_first(cursor, key, data);
+		else
+			rc = mdb_cursor_next(cursor, key, data, MDB_NEXT_DUP);
+		if (rc == MDB_SUCCESS) {
+			if (cursor->mc_xcursor->mx_cursor.mc_initialized) {
+				MDB_ppage	*top;
+fetchm:
+				top = CURSOR_TOP(&cursor->mc_xcursor->mx_cursor);
+				data->mv_size = NUMKEYS(top->mp_page) *
+					cursor->mc_xcursor->mx_txn.mt_dbs[cursor->mc_xcursor->mx_cursor.mc_dbi].md_pad;
+				data->mv_data = METADATA(top->mp_page);
+				top->mp_ki = NUMKEYS(top->mp_page)-1;
+			} else {
+				rc = MDB_NOTFOUND;
+			}
+		}
+		break;
+	case MDB_NEXT:
+	case MDB_NEXT_DUP:
+	case MDB_NEXT_NODUP:
+		if (!cursor->mc_initialized)
+			rc = mdb_cursor_first(cursor, key, data);
+		else
+			rc = mdb_cursor_next(cursor, key, data, op);
+		break;
+	case MDB_PREV:
+	case MDB_PREV_DUP:
+	case MDB_PREV_NODUP:
+		if (!cursor->mc_initialized || cursor->mc_eof)
+			rc = mdb_cursor_last(cursor, key, data);
+		else
+			rc = mdb_cursor_prev(cursor, key, data, op);
+		break;
+	case MDB_FIRST:
+		rc = mdb_cursor_first(cursor, key, data);
+		break;
+	case MDB_LAST:
+		rc = mdb_cursor_last(cursor, key, data);
+		break;
+	default:
+		DPRINTF("unhandled/unimplemented cursor operation %u", op);
+		rc = EINVAL;
+		break;
+	}
+
+	return rc;
+}
+
+/* Allocate a page and initialize it
+ */
+static MDB_dpage *
+mdb_new_page(MDB_txn *txn, MDB_dbi dbi, uint32_t flags, int num)
+{
+	MDB_dpage	*dp;
+
+	if ((dp = mdb_alloc_page(txn, NULL, 0, num)) == NULL)
+		return NULL;
+	DPRINTF("allocated new mpage %lu, page size %u",
+	    dp->p.mp_pgno, txn->mt_env->me_psize);
+	dp->p.mp_flags = flags | P_DIRTY;
+	dp->p.mp_lower = PAGEHDRSZ;
+	dp->p.mp_upper = txn->mt_env->me_psize;
+
+	if (IS_BRANCH(&dp->p))
+		txn->mt_dbs[dbi].md_branch_pages++;
+	else if (IS_LEAF(&dp->p))
+		txn->mt_dbs[dbi].md_leaf_pages++;
+	else if (IS_OVERFLOW(&dp->p)) {
+		txn->mt_dbs[dbi].md_overflow_pages += num;
+		dp->p.mp_pages = num;
+	}
+
+	return dp;
+}
+
+static size_t
+mdb_leaf_size(MDB_env *env, MDB_val *key, MDB_val *data)
+{
+	size_t		 sz;
+
+	sz = LEAFSIZE(key, data);
+	if (data->mv_size >= env->me_psize / MDB_MINKEYS) {
+		/* put on overflow page */
+		sz -= data->mv_size - sizeof(pgno_t);
+	}
+
+	return sz + sizeof(indx_t);
+}
+
+static size_t
+mdb_branch_size(MDB_env *env, MDB_val *key)
+{
+	size_t		 sz;
+
+	sz = INDXSIZE(key);
+	if (sz >= env->me_psize / MDB_MINKEYS) {
+		/* put on overflow page */
+		/* not implemented */
+		/* sz -= key->size - sizeof(pgno_t); */
+	}
+
+	return sz + sizeof(indx_t);
+}
+
+static int
+mdb_add_node(MDB_txn *txn, MDB_dbi dbi, MDB_page *mp, indx_t indx,
+    MDB_val *key, MDB_val *data, pgno_t pgno, uint8_t flags)
+{
+	unsigned int	 i;
+	size_t		 node_size = NODESIZE;
+	indx_t		 ofs;
+	MDB_node	*node;
+	MDB_dpage	*ofp = NULL;		/* overflow page */
+	DKBUF;
+
+	assert(mp->mp_upper >= mp->mp_lower);
+
+	DPRINTF("add node [%s] to %s page %lu at index %i, key size %zu",
+	    key ? DKEY(key) : NULL,
+	    IS_LEAF(mp) ? "leaf" : "branch",
+	    mp->mp_pgno, indx, key ? key->mv_size : 0);
+
+	if (IS_LEAF2(mp)) {
+		/* Move higher keys up one slot. */
+		int ksize = txn->mt_dbs[dbi].md_pad, dif;
+		char *ptr = LEAF2KEY(mp, indx, ksize);
+		dif = NUMKEYS(mp) - indx;
+		if (dif > 0)
+			memmove(ptr+ksize, ptr, dif*ksize);
+		/* insert new key */
+		memcpy(ptr, key->mv_data, ksize);
+
+		/* Just using these for counting */
+		mp->mp_lower += sizeof(indx_t);
+		mp->mp_upper -= ksize - sizeof(indx_t);
+		return MDB_SUCCESS;
+	}
+
+	if (key != NULL)
+		node_size += key->mv_size;
+
+	if (IS_LEAF(mp)) {
+		assert(data);
+		if (F_ISSET(flags, F_BIGDATA)) {
+			/* Data already on overflow page. */
+			node_size += sizeof(pgno_t);
+		} else if (data->mv_size >= txn->mt_env->me_psize / MDB_MINKEYS) {
+			int ovpages = OVPAGES(data->mv_size, txn->mt_env->me_psize);
+			/* Put data on overflow page. */
+			DPRINTF("data size is %zu, put on overflow page",
+			    data->mv_size);
+			node_size += sizeof(pgno_t);
+			if ((ofp = mdb_new_page(txn, dbi, P_OVERFLOW, ovpages)) == NULL)
+				return ENOMEM;
+			DPRINTF("allocated overflow page %lu", ofp->p.mp_pgno);
+			flags |= F_BIGDATA;
+		} else {
+			node_size += data->mv_size;
+		}
+	}
+
+	if (node_size + sizeof(indx_t) > SIZELEFT(mp)) {
+		DPRINTF("not enough room in page %lu, got %u ptrs",
+		    mp->mp_pgno, NUMKEYS(mp));
+		DPRINTF("upper - lower = %u - %u = %u", mp->mp_upper, mp->mp_lower,
+		    mp->mp_upper - mp->mp_lower);
+		DPRINTF("node size = %zu", node_size);
+		return ENOSPC;
+	}
+
+	/* Move higher pointers up one slot. */
+	for (i = NUMKEYS(mp); i > indx; i--)
+		mp->mp_ptrs[i] = mp->mp_ptrs[i - 1];
+
+	/* Adjust free space offsets. */
+	ofs = mp->mp_upper - node_size;
+	assert(ofs >= mp->mp_lower + sizeof(indx_t));
+	mp->mp_ptrs[indx] = ofs;
+	mp->mp_upper = ofs;
+	mp->mp_lower += sizeof(indx_t);
+
+	/* Write the node data. */
+	node = NODEPTR(mp, indx);
+	node->mn_ksize = (key == NULL) ? 0 : key->mv_size;
+	node->mn_flags = flags;
+	if (IS_LEAF(mp))
+		node->mn_dsize = data->mv_size;
+	else
+		NODEPGNO(node) = pgno;
+
+	if (key)
+		memcpy(NODEKEY(node), key->mv_data, key->mv_size);
+
+	if (IS_LEAF(mp)) {
+		assert(key);
+		if (ofp == NULL) {
+			if (F_ISSET(flags, F_BIGDATA))
+				memcpy(node->mn_data + key->mv_size, data->mv_data,
+				    sizeof(pgno_t));
+			else
+				memcpy(node->mn_data + key->mv_size, data->mv_data,
+				    data->mv_size);
+		} else {
+			memcpy(node->mn_data + key->mv_size, &ofp->p.mp_pgno,
+			    sizeof(pgno_t));
+			memcpy(METADATA(&ofp->p), data->mv_data, data->mv_size);
+		}
+	}
+
+	return MDB_SUCCESS;
+}
+
+static void
+mdb_del_node(MDB_page *mp, indx_t indx, int ksize)
+{
+	unsigned int	 sz;
+	indx_t		 i, j, numkeys, ptr;
+	MDB_node	*node;
+	char		*base;
+
+	DPRINTF("delete node %u on %s page %lu", indx,
+	    IS_LEAF(mp) ? "leaf" : "branch", mp->mp_pgno);
+	assert(indx < NUMKEYS(mp));
+
+	if (IS_LEAF2(mp)) {
+		int x = NUMKEYS(mp) - 1 - indx;
+		base = LEAF2KEY(mp, indx, ksize);
+		if (x)
+			memmove(base, base + ksize, x * ksize);
+		mp->mp_lower -= sizeof(indx_t);
+		mp->mp_upper += ksize - sizeof(indx_t);
+		return;
+	}
+
+	node = NODEPTR(mp, indx);
+	sz = NODESIZE + node->mn_ksize;
+	if (IS_LEAF(mp)) {
+		if (F_ISSET(node->mn_flags, F_BIGDATA))
+			sz += sizeof(pgno_t);
+		else
+			sz += NODEDSZ(node);
+	}
+
+	ptr = mp->mp_ptrs[indx];
+	numkeys = NUMKEYS(mp);
+	for (i = j = 0; i < numkeys; i++) {
+		if (i != indx) {
+			mp->mp_ptrs[j] = mp->mp_ptrs[i];
+			if (mp->mp_ptrs[i] < ptr)
+				mp->mp_ptrs[j] += sz;
+			j++;
+		}
+	}
+
+	base = (char *)mp + mp->mp_upper;
+	memmove(base + sz, base, ptr - mp->mp_upper);
+
+	mp->mp_lower -= sizeof(indx_t);
+	mp->mp_upper += sz;
+}
+
+static void
+mdb_xcursor_init0(MDB_txn *txn, MDB_dbi dbi, MDB_xcursor *mx)
+{
+	MDB_dbi dbn;
+
+	mx->mx_txn = *txn;
+	mx->mx_txn.mt_dbxs = mx->mx_dbxs;
+	mx->mx_txn.mt_dbs = mx->mx_dbs;
+	mx->mx_dbxs[0] = txn->mt_dbxs[0];
+	mx->mx_dbxs[1] = txn->mt_dbxs[1];
+	if (dbi > 1) {
+		mx->mx_dbxs[2] = txn->mt_dbxs[dbi];
+		dbn = 2;
+	} else {
+		dbn = 1;
+	}
+	mx->mx_dbxs[dbn+1].md_parent = dbn;
+	mx->mx_dbxs[dbn+1].md_cmp = mx->mx_dbxs[dbn].md_dcmp;
+	mx->mx_dbxs[dbn+1].md_rel = mx->mx_dbxs[dbn].md_rel;
+	mx->mx_dbxs[dbn+1].md_dirty = 0;
+	mx->mx_txn.mt_numdbs = dbn+2;
+
+	mx->mx_cursor.mc_snum = 0;
+	mx->mx_cursor.mc_txn = &mx->mx_txn;
+	mx->mx_cursor.mc_dbi = dbn+1;
+}
+
+static void
+mdb_xcursor_init1(MDB_txn *txn, MDB_dbi dbi, MDB_xcursor *mx, MDB_node *node)
+{
+	MDB_db *db = NODEDATA(node);
+	MDB_dbi dbn;
+	mx->mx_dbs[0] = txn->mt_dbs[0];
+	mx->mx_dbs[1] = txn->mt_dbs[1];
+	if (dbi > 1) {
+		mx->mx_dbs[2] = txn->mt_dbs[dbi];
+		dbn = 3;
+	} else {
+		dbn = 2;
+	}
+	mx->mx_dbs[dbn] = *db;
+	mx->mx_dbxs[dbn].md_name.mv_data = NODEKEY(node);
+	mx->mx_dbxs[dbn].md_name.mv_size = node->mn_ksize;
+	mx->mx_txn.mt_next_pgno = txn->mt_next_pgno;
+	mx->mx_txn.mt_oldest = txn->mt_oldest;
+	mx->mx_txn.mt_u = txn->mt_u;
+	mx->mx_cursor.mc_initialized = 0;
+	mx->mx_cursor.mc_eof = 0;
+}
+
+static void
+mdb_xcursor_fini(MDB_txn *txn, MDB_dbi dbi, MDB_xcursor *mx)
+{
+	txn->mt_next_pgno = mx->mx_txn.mt_next_pgno;
+	txn->mt_oldest = mx->mx_txn.mt_oldest;
+	txn->mt_u = mx->mx_txn.mt_u;
+	txn->mt_dbs[0] = mx->mx_dbs[0];
+	txn->mt_dbs[1] = mx->mx_dbs[1];
+	txn->mt_dbxs[0].md_dirty = mx->mx_dbxs[0].md_dirty;
+	txn->mt_dbxs[1].md_dirty = mx->mx_dbxs[1].md_dirty;
+	if (dbi > 1) {
+		txn->mt_dbs[dbi] = mx->mx_dbs[2];
+		txn->mt_dbxs[dbi].md_dirty = mx->mx_dbxs[2].md_dirty;
+	}
+}
+
+int
+mdb_cursor_open(MDB_txn *txn, MDB_dbi dbi, MDB_cursor **ret)
+{
+	MDB_cursor	*cursor;
+	size_t size = sizeof(MDB_cursor);
+
+	if (txn == NULL || ret == NULL || !dbi || dbi >= txn->mt_numdbs)
+		return EINVAL;
+
+	if (txn->mt_dbs[dbi].md_flags & MDB_DUPSORT)
+		size += sizeof(MDB_xcursor);
+
+	if ((cursor = calloc(1, size)) != NULL) {
+		cursor->mc_dbi = dbi;
+		cursor->mc_txn = txn;
+		if (txn->mt_dbs[dbi].md_flags & MDB_DUPSORT) {
+			MDB_xcursor *mx = (MDB_xcursor *)(cursor + 1);
+			cursor->mc_xcursor = mx;
+			mdb_xcursor_init0(txn, dbi, mx);
+		}
+	} else {
+		return ENOMEM;
+	}
+
+	*ret = cursor;
+
+	return MDB_SUCCESS;
+}
+
+/* Return the count of duplicate data items for the current key */
+int
+mdb_cursor_count(MDB_cursor *mc, unsigned long *countp)
+{
+	MDB_ppage	*top;
+	MDB_node	*leaf;
+
+	if (mc == NULL || countp == NULL)
+		return EINVAL;
+
+	if (!(mc->mc_txn->mt_dbs[mc->mc_dbi].md_flags & MDB_DUPSORT))
+		return EINVAL;
+
+	top = CURSOR_TOP(mc);
+	leaf = NODEPTR(top->mp_page, top->mp_ki);
+	if (!F_ISSET(leaf->mn_flags, F_DUPDATA)) {
+		*countp = 1;
+	} else {
+		if (!mc->mc_xcursor->mx_cursor.mc_initialized)
+			return EINVAL;
+
+		*countp = mc->mc_xcursor->mx_txn.mt_dbs[mc->mc_xcursor->mx_cursor.mc_dbi].md_entries;
+	}
+	return MDB_SUCCESS;
+}
+
+void
+mdb_cursor_close(MDB_cursor *cursor)
+{
+	if (cursor != NULL) {
+		free(cursor);
+	}
+}
+
+static int
+mdb_update_key(MDB_page *mp, indx_t indx, MDB_val *key)
+{
+	indx_t			 ptr, i, numkeys;
+	int			 delta;
+	size_t			 len;
+	MDB_node		*node;
+	char			*base;
+	DKBUF;
+
+	node = NODEPTR(mp, indx);
+	ptr = mp->mp_ptrs[indx];
+	DPRINTF("update key %u (ofs %u) [%.*s] to [%s] on page %lu",
+	    indx, ptr,
+	    (int)node->mn_ksize, (char *)NODEKEY(node),
+		DKEY(key),
+	    mp->mp_pgno);
+
+	delta = key->mv_size - node->mn_ksize;
+	if (delta) {
+		if (delta > 0 && SIZELEFT(mp) < delta) {
+			DPRINTF("OUCH! Not enough room, delta = %d", delta);
+			return ENOSPC;
+		}
+
+		numkeys = NUMKEYS(mp);
+		for (i = 0; i < numkeys; i++) {
+			if (mp->mp_ptrs[i] <= ptr)
+				mp->mp_ptrs[i] -= delta;
+		}
+
+		base = (char *)mp + mp->mp_upper;
+		len = ptr - mp->mp_upper + NODESIZE;
+		memmove(base - delta, base, len);
+		mp->mp_upper -= delta;
+
+		node = NODEPTR(mp, indx);
+		node->mn_ksize = key->mv_size;
+	}
+
+	memcpy(NODEKEY(node), key->mv_data, key->mv_size);
+
+	return MDB_SUCCESS;
+}
+
+/* Move a node from src to dst.
+ */
+static int
+mdb_move_node(MDB_txn *txn, MDB_dbi dbi, MDB_pageparent *src, indx_t srcindx,
+    MDB_pageparent *dst, indx_t dstindx)
+{
+	int			 rc;
+	MDB_node		*srcnode;
+	MDB_val		 key, data;
+	DKBUF;
+
+	/* Mark src and dst as dirty. */
+	if ((rc = mdb_touch(txn, src)) ||
+	    (rc = mdb_touch(txn, dst)))
+		return rc;;
+
+	if (IS_LEAF2(src->mp_page)) {
+		srcnode = NODEPTR(src->mp_page, 0);	/* fake */
+		key.mv_size = txn->mt_dbs[dbi].md_pad;
+		key.mv_data = LEAF2KEY(src->mp_page, srcindx, key.mv_size);
+		data.mv_size = 0;
+		data.mv_data = NULL;
+	} else {
+		srcnode = NODEPTR(src->mp_page, srcindx);
+		key.mv_size = NODEKSZ(srcnode);
+		key.mv_data = NODEKEY(srcnode);
+		data.mv_size = NODEDSZ(srcnode);
+		data.mv_data = NODEDATA(srcnode);
+	}
+	DPRINTF("moving %s node %u [%s] on page %lu to node %u on page %lu",
+	    IS_LEAF(src->mp_page) ? "leaf" : "branch",
+	    srcindx,
+		DKEY(&key),
+	    src->mp_page->mp_pgno,
+	    dstindx, dst->mp_page->mp_pgno);
+
+	/* Add the node to the destination page.
+	 */
+	rc = mdb_add_node(txn, dbi, dst->mp_page, dstindx, &key, &data, NODEPGNO(srcnode),
+	    srcnode->mn_flags);
+	if (rc != MDB_SUCCESS)
+		return rc;
+
+	/* Delete the node from the source page.
+	 */
+	mdb_del_node(src->mp_page, srcindx, key.mv_size);
+
+	/* The key value just changed due to del_node, find it again.
+	 */
+	if (!IS_LEAF2(src->mp_page)) {
+		srcnode = NODEPTR(src->mp_page, srcindx);
+		key.mv_data = NODEKEY(srcnode);
+	}
+
+	/* Update the parent separators.
+	 */
+	if (srcindx == 0) {
+		if (src->mp_pi != 0) {
+			DPRINTF("update separator for source page %lu to [%s]",
+				src->mp_page->mp_pgno, DKEY(&key));
+			if ((rc = mdb_update_key(src->mp_parent, src->mp_pi,
+				&key)) != MDB_SUCCESS)
+				return rc;
+		}
+		if (IS_BRANCH(src->mp_page)) {
+			MDB_val	 nullkey;
+			nullkey.mv_size = 0;
+			assert(mdb_update_key(src->mp_page, 0, &nullkey) == MDB_SUCCESS);
+		}
+	}
+
+	if (dstindx == 0) {
+		if (dst->mp_pi != 0) {
+			DPRINTF("update separator for destination page %lu to [%s]",
+				dst->mp_page->mp_pgno, DKEY(&key));
+			if ((rc = mdb_update_key(dst->mp_parent, dst->mp_pi,
+				&key)) != MDB_SUCCESS)
+				return rc;
+		}
+		if (IS_BRANCH(dst->mp_page)) {
+			MDB_val	 nullkey;
+			nullkey.mv_size = 0;
+			assert(mdb_update_key(dst->mp_page, 0, &nullkey) == MDB_SUCCESS);
+		}
+	}
+
+	return MDB_SUCCESS;
+}
+
+static int
+mdb_merge(MDB_txn *txn, MDB_dbi dbi, MDB_pageparent *src, MDB_pageparent *dst)
+{
+	int			 rc;
+	indx_t			 i;
+	MDB_node		*srcnode;
+	MDB_val		 key, data;
+	MDB_pageparent	mpp;
+	MDB_dhead *dh;
+
+	DPRINTF("merging page %lu and %lu", src->mp_page->mp_pgno, dst->mp_page->mp_pgno);
+
+	assert(txn != NULL);
+	assert(src->mp_parent);	/* can't merge root page */
+	assert(dst->mp_parent);
+
+	/* Mark src and dst as dirty. */
+	if ((rc = mdb_touch(txn, src)) ||
+	    (rc = mdb_touch(txn, dst)))
+		return rc;
+
+	/* Move all nodes from src to dst.
+	 */
+	if (IS_LEAF2(src->mp_page)) {
+		key.mv_size = txn->mt_dbs[dbi].md_pad;
+		key.mv_data = METADATA(src->mp_page);
+		for (i = 0; i < NUMKEYS(src->mp_page); i++) {
+			rc = mdb_add_node(txn, dbi, dst->mp_page, NUMKEYS(dst->mp_page), &key,
+				NULL, 0, 0);
+			if (rc != MDB_SUCCESS)
+				return rc;
+			key.mv_data = (char *)key.mv_data + key.mv_size;
+		}
+	} else {
+		for (i = 0; i < NUMKEYS(src->mp_page); i++) {
+			srcnode = NODEPTR(src->mp_page, i);
+
+			key.mv_size = srcnode->mn_ksize;
+			key.mv_data = NODEKEY(srcnode);
+			data.mv_size = NODEDSZ(srcnode);
+			data.mv_data = NODEDATA(srcnode);
+			rc = mdb_add_node(txn, dbi, dst->mp_page, NUMKEYS(dst->mp_page), &key,
+				&data, NODEPGNO(srcnode), srcnode->mn_flags);
+			if (rc != MDB_SUCCESS)
+				return rc;
+		}
+	}
+
+	DPRINTF("dst page %lu now has %u keys (%.1f%% filled)",
+	    dst->mp_page->mp_pgno, NUMKEYS(dst->mp_page), (float)PAGEFILL(txn->mt_env, dst->mp_page) / 10);
+
+	/* Unlink the src page from parent.
+	 */
+	mdb_del_node(src->mp_parent, src->mp_pi, 0);
+	if (src->mp_pi == 0) {
+		key.mv_size = 0;
+		if ((rc = mdb_update_key(src->mp_parent, 0, &key)) != MDB_SUCCESS)
+			return rc;
+	}
+
+	if (IS_LEAF(src->mp_page))
+		txn->mt_dbs[dbi].md_leaf_pages--;
+	else
+		txn->mt_dbs[dbi].md_branch_pages--;
+
+	mpp.mp_page = src->mp_parent;
+	dh = (MDB_dhead *)src->mp_parent;
+	dh--;
+	mpp.mp_parent = dh->md_parent;
+	mpp.mp_pi = dh->md_pi;
+
+	return mdb_rebalance(txn, dbi, &mpp);
+}
+
+#define FILL_THRESHOLD	 250
+
+static int
+mdb_rebalance(MDB_txn *txn, MDB_dbi dbi, MDB_pageparent *mpp)
+{
+	MDB_node	*node;
+	MDB_page	*root;
+	MDB_pageparent npp;
+	indx_t		 si = 0, di = 0;
+
+	assert(txn != NULL);
+	assert(mpp != NULL);
+
+	DPRINTF("rebalancing %s page %lu (has %u keys, %.1f%% full)",
+	    IS_LEAF(mpp->mp_page) ? "leaf" : "branch",
+	    mpp->mp_page->mp_pgno, NUMKEYS(mpp->mp_page), (float)PAGEFILL(txn->mt_env, mpp->mp_page) / 10);
+
+	if (PAGEFILL(txn->mt_env, mpp->mp_page) >= FILL_THRESHOLD) {
+		DPRINTF("no need to rebalance page %lu, above fill threshold",
+		    mpp->mp_page->mp_pgno);
+		return MDB_SUCCESS;
+	}
+
+	if (mpp->mp_parent == NULL) {
+		if (NUMKEYS(mpp->mp_page) == 0) {
+			DPUTS("tree is completely empty");
+			txn->mt_dbs[dbi].md_root = P_INVALID;
+			txn->mt_dbs[dbi].md_depth = 0;
+			txn->mt_dbs[dbi].md_leaf_pages = 0;
+		} else if (IS_BRANCH(mpp->mp_page) && NUMKEYS(mpp->mp_page) == 1) {
+			DPUTS("collapsing root page!");
+			txn->mt_dbs[dbi].md_root = NODEPGNO(NODEPTR(mpp->mp_page, 0));
+			if ((root = mdb_get_page(txn, txn->mt_dbs[dbi].md_root)) == NULL)
+				return MDB_PAGE_NOTFOUND;
+			txn->mt_dbs[dbi].md_depth--;
+			txn->mt_dbs[dbi].md_branch_pages--;
+		} else
+			DPUTS("root page doesn't need rebalancing");
+		return MDB_SUCCESS;
+	}
+
+	/* The parent (branch page) must have at least 2 pointers,
+	 * otherwise the tree is invalid.
+	 */
+	assert(NUMKEYS(mpp->mp_parent) > 1);
+
+	/* Leaf page fill factor is below the threshold.
+	 * Try to move keys from left or right neighbor, or
+	 * merge with a neighbor page.
+	 */
+
+	/* Find neighbors.
+	 */
+	if (mpp->mp_pi == 0) {
+		/* We're the leftmost leaf in our parent.
+		 */
+		DPUTS("reading right neighbor");
+		node = NODEPTR(mpp->mp_parent, mpp->mp_pi + 1);
+		if ((npp.mp_page = mdb_get_page(txn, NODEPGNO(node))) == NULL)
+			return MDB_PAGE_NOTFOUND;
+		npp.mp_pi = mpp->mp_pi + 1;
+		si = 0;
+		di = NUMKEYS(mpp->mp_page);
+	} else {
+		/* There is at least one neighbor to the left.
+		 */
+		DPUTS("reading left neighbor");
+		node = NODEPTR(mpp->mp_parent, mpp->mp_pi - 1);
+		if ((npp.mp_page = mdb_get_page(txn, NODEPGNO(node))) == NULL)
+			return MDB_PAGE_NOTFOUND;
+		npp.mp_pi = mpp->mp_pi - 1;
+		si = NUMKEYS(npp.mp_page) - 1;
+		di = 0;
+	}
+	npp.mp_parent = mpp->mp_parent;
+
+	DPRINTF("found neighbor page %lu (%u keys, %.1f%% full)",
+	    npp.mp_page->mp_pgno, NUMKEYS(npp.mp_page), (float)PAGEFILL(txn->mt_env, npp.mp_page) / 10);
+
+	/* If the neighbor page is above threshold and has at least two
+	 * keys, move one key from it.
+	 *
+	 * Otherwise we should try to merge them.
+	 */
+	if (PAGEFILL(txn->mt_env, npp.mp_page) >= FILL_THRESHOLD && NUMKEYS(npp.mp_page) >= 2)
+		return mdb_move_node(txn, dbi, &npp, si, mpp, di);
+	else { /* FIXME: if (has_enough_room()) */
+		if (mpp->mp_pi == 0)
+			return mdb_merge(txn, dbi, &npp, mpp);
+		else
+			return mdb_merge(txn, dbi, mpp, &npp);
+	}
+}
+
+static int
+mdb_del0(MDB_txn *txn, MDB_dbi dbi, unsigned int ki, MDB_pageparent *mpp, MDB_node *leaf)
+{
+	int rc;
+
+	/* add overflow pages to free list */
+	if (!IS_LEAF2(mpp->mp_page) && F_ISSET(leaf->mn_flags, F_BIGDATA)) {
+		int i, ovpages;
+		pgno_t pg;
+
+		memcpy(&pg, NODEDATA(leaf), sizeof(pg));
+		ovpages = OVPAGES(NODEDSZ(leaf), txn->mt_env->me_psize);
+		for (i=0; i<ovpages; i++) {
+			DPRINTF("freed ov page %lu", pg);
+			mdb_midl_insert(txn->mt_free_pgs, pg);
+			pg++;
+		}
+	}
+	mdb_del_node(mpp->mp_page, ki, txn->mt_dbs[dbi].md_pad);
+	txn->mt_dbs[dbi].md_entries--;
+	rc = mdb_rebalance(txn, dbi, mpp);
+	if (rc != MDB_SUCCESS)
+		txn->mt_flags |= MDB_TXN_ERROR;
+
+	return rc;
+}
+
+int
+mdb_del(MDB_txn *txn, MDB_dbi dbi,
+    MDB_val *key, MDB_val *data,
+	unsigned int flags)
+{
+	int		 rc, exact;
+	unsigned int	 ki;
+	MDB_node	*leaf;
+	MDB_pageparent	mpp;
+	DKBUF;
+
+	assert(key != NULL);
+
+	DPRINTF("====> delete db %u key [%s]", dbi, DKEY(key));
+
+	if (txn == NULL || !dbi || dbi >= txn->mt_numdbs)
+		return EINVAL;
+
+	if (F_ISSET(txn->mt_flags, MDB_TXN_RDONLY)) {
+		return EINVAL;
+	}
+
+	if (key->mv_size == 0 || key->mv_size > MAXKEYSIZE) {
+		return EINVAL;
+	}
+
+	mpp.mp_parent = NULL;
+	mpp.mp_pi = 0;
+	if ((rc = mdb_search_page(txn, dbi, key, NULL, 1, &mpp)) != MDB_SUCCESS)
+		return rc;
+
+	leaf = mdb_search_node(txn, dbi, mpp.mp_page, key, &exact, &ki);
+	if (leaf == NULL || !exact) {
+		return MDB_NOTFOUND;
+	}
+
+	if (!IS_LEAF2(mpp.mp_page) && F_ISSET(leaf->mn_flags, F_DUPDATA)) {
+		MDB_xcursor mx;
+		MDB_pageparent mp2;
+
+		mdb_xcursor_init0(txn, dbi, &mx);
+		mdb_xcursor_init1(txn, dbi, &mx, leaf);
+		if (flags == MDB_DEL_DUP) {
+			rc = mdb_del(&mx.mx_txn, mx.mx_cursor.mc_dbi, data, NULL, 0);
+			mdb_xcursor_fini(txn, dbi, &mx);
+			if (rc != MDB_SUCCESS)
+				return rc;
+			/* If sub-DB still has entries, we're done */
+			if (mx.mx_txn.mt_dbs[mx.mx_cursor.mc_dbi].md_root != P_INVALID) {
+				memcpy(NODEDATA(leaf), &mx.mx_txn.mt_dbs[mx.mx_cursor.mc_dbi],
+					sizeof(MDB_db));
+				txn->mt_dbs[dbi].md_entries--;
+				return rc;
+			}
+			/* otherwise fall thru and delete the sub-DB */
+		} else {
+			/* add all the child DB's pages to the free list */
+			rc = mdb_search_page(&mx.mx_txn, mx.mx_cursor.mc_dbi,
+				NULL, &mx.mx_cursor, 0, &mp2);
+			if (rc == MDB_SUCCESS) {
+				MDB_ppage *top, *parent;
+				MDB_node *ni;
+				unsigned int i;
+
+				cursor_pop_page(&mx.mx_cursor);
+				if (mx.mx_cursor.mc_snum) {
+					top = CURSOR_TOP(&mx.mx_cursor);
+					while (mx.mx_cursor.mc_snum > 1) {
+						parent = CURSOR_PARENT(&mx.mx_cursor);
+						for (i=0; i<NUMKEYS(top->mp_page); i++) {
+							ni = NODEPTR(top->mp_page, i);
+							mdb_midl_insert(txn->mt_free_pgs, NODEPGNO(ni));
+						}
+						parent->mp_ki++;
+						if (parent->mp_ki >= NUMKEYS(parent->mp_page)) {
+							cursor_pop_page(&mx.mx_cursor);
+							top = parent;
+						} else {
+							ni = NODEPTR(parent->mp_page, parent->mp_ki);
+							top->mp_page = mdb_get_page(&mx.mx_txn, NODEPGNO(ni));
+						}
+					}
+				}
+				mdb_midl_insert(txn->mt_free_pgs, mx.mx_txn.mt_dbs[mx.mx_cursor.mc_dbi].md_root);
+			}
+		}
+	}
+
+	if (data && (rc = mdb_read_data(txn, leaf, data)) != MDB_SUCCESS)
+		return rc;
+
+	return mdb_del0(txn, dbi, ki, &mpp, leaf);
+}
+
+/* Split page <*mpp>, and insert <key,(data|newpgno)> in either left or
+ * right sibling, at index <*newindxp> (as if unsplit). Updates *mpp and
+ * *newindxp with the actual values after split, ie if *mpp and *newindxp
+ * refer to a node in the new right sibling page.
+ */
+static int
+mdb_split(MDB_txn *txn, MDB_dbi dbi, MDB_page **mpp, unsigned int *newindxp,
+    MDB_val *newkey, MDB_val *newdata, pgno_t newpgno)
+{
+	uint8_t		 flags;
+	int		 rc = MDB_SUCCESS, ins_new = 0;
+	indx_t		 newindx;
+	pgno_t		 pgno = 0;
+	unsigned int	 i, j, split_indx;
+	MDB_node	*node;
+	MDB_val	 sepkey, rkey, rdata;
+	MDB_page	*copy;
+	MDB_dpage	*mdp, *rdp, *pdp;
+	MDB_dhead *dh;
+	DKBUF;
+
+	assert(txn != NULL);
+
+	dh = ((MDB_dhead *)*mpp) - 1;
+	mdp = (MDB_dpage *)dh;
+	newindx = *newindxp;
+
+	DPRINTF("-----> splitting %s page %lu and adding [%s] at index %i",
+	    IS_LEAF(&mdp->p) ? "leaf" : "branch", mdp->p.mp_pgno,
+	    DKEY(newkey), *newindxp);
+
+	if (mdp->h.md_parent == NULL) {
+		if ((pdp = mdb_new_page(txn, dbi, P_BRANCH, 1)) == NULL)
+			return ENOMEM;
+		mdp->h.md_pi = 0;
+		mdp->h.md_parent = &pdp->p;
+		txn->mt_dbs[dbi].md_root = pdp->p.mp_pgno;
+		DPRINTF("root split! new root = %lu", pdp->p.mp_pgno);
+		txn->mt_dbs[dbi].md_depth++;
+
+		/* Add left (implicit) pointer. */
+		if ((rc = mdb_add_node(txn, dbi, &pdp->p, 0, NULL, NULL,
+		    mdp->p.mp_pgno, 0)) != MDB_SUCCESS)
+			return rc;
+	} else {
+		DPRINTF("parent branch page is %lu", mdp->h.md_parent->mp_pgno);
+	}
+
+	/* Create a right sibling. */
+	if ((rdp = mdb_new_page(txn, dbi, mdp->p.mp_flags, 1)) == NULL)
+		return ENOMEM;
+	rdp->h.md_parent = mdp->h.md_parent;
+	rdp->h.md_pi = mdp->h.md_pi + 1;
+	DPRINTF("new right sibling: page %lu", rdp->p.mp_pgno);
+
+	split_indx = NUMKEYS(&mdp->p) / 2 + 1;
+
+	if (IS_LEAF2(&rdp->p)) {
+		char *split, *ins;
+		int x;
+		unsigned int nkeys = NUMKEYS(&mdp->p), lsize, rsize, ksize;
+		/* Move half of the keys to the right sibling */
+		copy = NULL;
+		x = *newindxp - split_indx;
+		ksize = txn->mt_dbs[dbi].md_pad;
+		split = LEAF2KEY(&mdp->p, split_indx, ksize);
+		rsize = (nkeys - split_indx) * ksize;
+		lsize = (nkeys - split_indx) * sizeof(indx_t);
+		mdp->p.mp_lower -= lsize;
+		rdp->p.mp_lower += lsize;
+		mdp->p.mp_upper += rsize - lsize;
+		rdp->p.mp_upper -= rsize - lsize;
+		sepkey.mv_size = ksize;
+		if (newindx == split_indx) {
+			sepkey.mv_data = newkey->mv_data;
+		} else {
+			sepkey.mv_data = split;
+		}
+		if (x<0) {
+			ins = LEAF2KEY(&mdp->p, *newindxp, ksize);
+			memcpy(&rdp->p.mp_ptrs, split, rsize);
+			sepkey.mv_data = &rdp->p.mp_ptrs;
+			memmove(ins+ksize, ins, (split_indx - *newindxp) * ksize);
+			memcpy(ins, newkey->mv_data, ksize);
+			mdp->p.mp_lower += sizeof(indx_t);
+			mdp->p.mp_upper -= ksize - sizeof(indx_t);
+		} else {
+			if (x)
+				memcpy(&rdp->p.mp_ptrs, split, x * ksize);
+			ins = LEAF2KEY(&rdp->p, x, ksize);
+			memcpy(ins, newkey->mv_data, ksize);
+			memcpy(ins+ksize, split + x * ksize, rsize - x * ksize);
+			rdp->p.mp_lower += sizeof(indx_t);
+			rdp->p.mp_upper -= ksize - sizeof(indx_t);
+			*newindxp = x;
+			*mpp = &rdp->p;
+		}
+		goto newsep;
+	}
+
+	/* Move half of the keys to the right sibling. */
+	if ((copy = malloc(txn->mt_env->me_psize)) == NULL)
+		return ENOMEM;
+	memcpy(copy, &mdp->p, txn->mt_env->me_psize);
+	memset(&mdp->p.mp_ptrs, 0, txn->mt_env->me_psize - PAGEHDRSZ);
+	mdp->p.mp_lower = PAGEHDRSZ;
+	mdp->p.mp_upper = txn->mt_env->me_psize;
+
+	/* First find the separating key between the split pages.
+	 */
+	memset(&sepkey, 0, sizeof(sepkey));
+	if (newindx == split_indx) {
+		sepkey.mv_size = newkey->mv_size;
+		sepkey.mv_data = newkey->mv_data;
+	} else {
+		node = NODEPTR(copy, split_indx);
+		sepkey.mv_size = node->mn_ksize;
+		sepkey.mv_data = NODEKEY(node);
+	}
+
+newsep:
+	DPRINTF("separator is [%s]", DKEY(&sepkey));
+
+	/* Copy separator key to the parent.
+	 */
+	if (SIZELEFT(rdp->h.md_parent) < mdb_branch_size(txn->mt_env, &sepkey)) {
+		rc = mdb_split(txn, dbi, &rdp->h.md_parent, &rdp->h.md_pi,
+		    &sepkey, NULL, rdp->p.mp_pgno);
+
+		/* Right page might now have changed parent.
+		 * Check if left page also changed parent.
+		 */
+		if (rdp->h.md_parent != mdp->h.md_parent &&
+		    mdp->h.md_pi >= NUMKEYS(mdp->h.md_parent)) {
+			mdp->h.md_parent = rdp->h.md_parent;
+			mdp->h.md_pi = rdp->h.md_pi - 1;
+		}
+	} else {
+		rc = mdb_add_node(txn, dbi, rdp->h.md_parent, rdp->h.md_pi,
+		    &sepkey, NULL, rdp->p.mp_pgno, 0);
+	}
+	if (IS_LEAF2(&rdp->p)) {
+		return rc;
+	}
+	if (rc != MDB_SUCCESS) {
+		free(copy);
+		return rc;
+	}
+
+	for (i = j = 0; i <= NUMKEYS(copy); j++) {
+		if (i < split_indx) {
+			/* Re-insert in left sibling. */
+			pdp = mdp;
+		} else {
+			/* Insert in right sibling. */
+			if (i == split_indx)
+				/* Reset insert index for right sibling. */
+				j = (i == newindx && ins_new);
+			pdp = rdp;
+		}
+
+		if (i == newindx && !ins_new) {
+			/* Insert the original entry that caused the split. */
+			rkey.mv_data = newkey->mv_data;
+			rkey.mv_size = newkey->mv_size;
+			if (IS_LEAF(&mdp->p)) {
+				rdata.mv_data = newdata->mv_data;
+				rdata.mv_size = newdata->mv_size;
+			} else
+				pgno = newpgno;
+			flags = 0;
+
+			ins_new = 1;
+
+			/* Update page and index for the new key. */
+			*newindxp = j;
+			*mpp = &pdp->p;
+		} else if (i == NUMKEYS(copy)) {
+			break;
+		} else {
+			node = NODEPTR(copy, i);
+			rkey.mv_data = NODEKEY(node);
+			rkey.mv_size = node->mn_ksize;
+			if (IS_LEAF(&mdp->p)) {
+				rdata.mv_data = NODEDATA(node);
+				rdata.mv_size = node->mn_dsize;
+			} else
+				pgno = NODEPGNO(node);
+			flags = node->mn_flags;
+
+			i++;
+		}
+
+		if (!IS_LEAF(&mdp->p) && j == 0) {
+			/* First branch index doesn't need key data. */
+			rkey.mv_size = 0;
+		}
+
+		rc = mdb_add_node(txn, dbi, &pdp->p, j, &rkey, &rdata, pgno,flags);
+	}
+
+	free(copy);
+	return rc;
+}
+
+static int
+mdb_put0(MDB_txn *txn, MDB_dbi dbi,
+    MDB_val *key, MDB_val *data, unsigned int flags)
+{
+	int		 rc = MDB_SUCCESS, exact;
+	unsigned int	 ki;
+	MDB_node	*leaf;
+	MDB_pageparent	mpp;
+	MDB_val	xdata, *rdata, dkey;
+	MDB_db dummy;
+	char dbuf[PAGESIZE];
+	int do_sub = 0;
+	size_t nsize;
+	DKBUF;
+
+	DPRINTF("==> put db %u key [%s], size %zu, data size %zu",
+		dbi, DKEY(key), key->mv_size, data->mv_size);
+
+	dkey.mv_size = 0;
+	mpp.mp_parent = NULL;
+	mpp.mp_pi = 0;
+	rc = mdb_search_page(txn, dbi, key, NULL, 1, &mpp);
+	if (rc == MDB_SUCCESS) {
+		leaf = mdb_search_node(txn, dbi, mpp.mp_page, key, &exact, &ki);
+		if (leaf && exact) {
+			if (flags == MDB_NOOVERWRITE) {
+				DPRINTF("duplicate key [%s]", DKEY(key));
+				return MDB_KEYEXIST;
+			}
+			/* there's only a key anyway, so this is a no-op */
+			if (IS_LEAF2(mpp.mp_page))
+				return MDB_SUCCESS;
+
+			if (F_ISSET(txn->mt_dbs[dbi].md_flags, MDB_DUPSORT)) {
+				/* Was a single item before, must convert now */
+				if (!F_ISSET(leaf->mn_flags, F_DUPDATA)) {
+					dkey.mv_size = NODEDSZ(leaf);
+					dkey.mv_data = dbuf;
+					memcpy(dbuf, NODEDATA(leaf), dkey.mv_size);
+					/* data matches, ignore it */
+					if (!mdb_dcmp(txn, dbi, data, &dkey))
+						return (flags == MDB_NODUPDATA) ? MDB_KEYEXIST : MDB_SUCCESS;
+					memset(&dummy, 0, sizeof(dummy));
+					if (txn->mt_dbs[dbi].md_flags & MDB_DUPFIXED) {
+						dummy.md_pad = data->mv_size;
+						dummy.md_flags = MDB_DUPFIXED;
+						if (txn->mt_dbs[dbi].md_flags & MDB_INTEGERDUP)
+							dummy.md_flags |= MDB_INTEGERKEY;
+					}
+					dummy.md_root = P_INVALID;
+					if (dkey.mv_size == sizeof(MDB_db)) {
+						memcpy(NODEDATA(leaf), &dummy, sizeof(dummy));
+						goto put_sub;
+					}
+					mdb_del_node(mpp.mp_page, ki, 0);
+					do_sub = 1;
+					rdata = &xdata;
+					xdata.mv_size = sizeof(MDB_db);
+					xdata.mv_data = &dummy;
+					goto new_sub;
+				}
+				goto put_sub;
+			}
+			/* same size, just replace it */
+			if (NODEDSZ(leaf) == data->mv_size) {
+				memcpy(NODEDATA(leaf), data->mv_data, data->mv_size);
+				goto done;
+			}
+			mdb_del_node(mpp.mp_page, ki, 0);
+		}
+		if (leaf == NULL) {		/* append if not found */
+			ki = NUMKEYS(mpp.mp_page);
+			DPRINTF("appending key at index %i", ki);
+		}
+	} else if (rc == MDB_NOTFOUND) {
+		MDB_dpage *dp;
+		/* new file, just write a root leaf page */
+		DPUTS("allocating new root leaf page");
+		if ((dp = mdb_new_page(txn, dbi, P_LEAF, 1)) == NULL) {
+			return ENOMEM;
+		}
+		mpp.mp_page = &dp->p;
+		txn->mt_dbs[dbi].md_root = mpp.mp_page->mp_pgno;
+		txn->mt_dbs[dbi].md_depth++;
+		txn->mt_dbxs[dbi].md_dirty = 1;
+		if ((txn->mt_dbs[dbi].md_flags & (MDB_DUPSORT|MDB_DUPFIXED)) == MDB_DUPFIXED)
+			mpp.mp_page->mp_flags |= P_LEAF2;
+		ki = 0;
+	}
+	else
+		goto done;
+
+	assert(IS_LEAF(mpp.mp_page));
+	DPRINTF("there are %u keys, should insert new key at index %i",
+		NUMKEYS(mpp.mp_page), ki);
+
+	rdata = data;
+
+new_sub:
+	nsize = IS_LEAF2(mpp.mp_page) ? key->mv_size : mdb_leaf_size(txn->mt_env, key, rdata);
+	if (SIZELEFT(mpp.mp_page) < nsize) {
+		rc = mdb_split(txn, dbi, &mpp.mp_page, &ki, key, rdata, P_INVALID);
+	} else {
+		/* There is room already in this leaf page. */
+		rc = mdb_add_node(txn, dbi, mpp.mp_page, ki, key, rdata, 0, 0);
+	}
+
+	if (rc != MDB_SUCCESS)
+		txn->mt_flags |= MDB_TXN_ERROR;
+	else {
+		/* Remember if we just added a subdatabase */
+		if (flags & F_SUBDATA) {
+			leaf = NODEPTR(mpp.mp_page, ki);
+			leaf->mn_flags |= F_SUBDATA;
+		}
+
+		/* Now store the actual data in the child DB. Note that we're
+		 * storing the user data in the keys field, so there are strict
+		 * size limits on dupdata. The actual data fields of the child
+		 * DB are all zero size.
+		 */
+		if (do_sub) {
+			MDB_xcursor mx;
+
+			leaf = NODEPTR(mpp.mp_page, ki);
+put_sub:
+			mdb_xcursor_init0(txn, dbi, &mx);
+			mdb_xcursor_init1(txn, dbi, &mx, leaf);
+			xdata.mv_size = 0;
+			xdata.mv_data = "";
+			if (flags == MDB_NODUPDATA)
+				flags = MDB_NOOVERWRITE;
+			/* converted, write the original data first */
+			if (dkey.mv_size) {
+				rc = mdb_put0(&mx.mx_txn, mx.mx_cursor.mc_dbi, &dkey, &xdata, flags);
+				if (rc) return rc;
+				leaf->mn_flags |= F_DUPDATA;
+			}
+			rc = mdb_put0(&mx.mx_txn, mx.mx_cursor.mc_dbi, data, &xdata, flags);
+			mdb_xcursor_fini(txn, dbi, &mx);
+			memcpy(NODEDATA(leaf), &mx.mx_txn.mt_dbs[mx.mx_cursor.mc_dbi],
+				sizeof(MDB_db));
+		}
+		txn->mt_dbs[dbi].md_entries++;
+	}
+
+done:
+	return rc;
+}
+
+int
+mdb_put(MDB_txn *txn, MDB_dbi dbi,
+    MDB_val *key, MDB_val *data, unsigned int flags)
+{
+	assert(key != NULL);
+	assert(data != NULL);
+
+	if (txn == NULL || !dbi || dbi >= txn->mt_numdbs)
+		return EINVAL;
+
+	if (F_ISSET(txn->mt_flags, MDB_TXN_RDONLY)) {
+		return EINVAL;
+	}
+
+	if (key->mv_size == 0 || key->mv_size > MAXKEYSIZE) {
+		return EINVAL;
+	}
+
+	if ((flags & (MDB_NOOVERWRITE|MDB_NODUPDATA)) != flags)
+		return EINVAL;
+
+	return mdb_put0(txn, dbi, key, data, flags);
+}
+
+int
+mdb_env_set_flags(MDB_env *env, unsigned int flag, int onoff)
+{
+#define	CHANGEABLE	(MDB_NOSYNC)
+	if ((flag & CHANGEABLE) != flag)
+		return EINVAL;
+	if (onoff)
+		env->me_flags |= flag;
+	else
+		env->me_flags &= ~flag;
+	return MDB_SUCCESS;
+}
+
+int
+mdb_env_get_flags(MDB_env *env, unsigned int *arg)
+{
+	if (!env || !arg)
+		return EINVAL;
+
+	*arg = env->me_flags;
+	return MDB_SUCCESS;
+}
+
+int
+mdb_env_get_path(MDB_env *env, const char **arg)
+{
+	if (!env || !arg)
+		return EINVAL;
+
+	*arg = env->me_path;
+	return MDB_SUCCESS;
+}
+
+static int
+mdb_stat0(MDB_env *env, MDB_db *db, MDB_stat *arg)
+{
+	arg->ms_psize = env->me_psize;
+	arg->ms_depth = db->md_depth;
+	arg->ms_branch_pages = db->md_branch_pages;
+	arg->ms_leaf_pages = db->md_leaf_pages;
+	arg->ms_overflow_pages = db->md_overflow_pages;
+	arg->ms_entries = db->md_entries;
+
+	return MDB_SUCCESS;
+}
+int
+mdb_env_stat(MDB_env *env, MDB_stat *arg)
+{
+	if (env == NULL || arg == NULL)
+		return EINVAL;
+
+	return mdb_stat0(env, &env->me_meta->mm_dbs[MAIN_DBI], arg);
+}
+
+int mdb_open(MDB_txn *txn, const char *name, unsigned int flags, MDB_dbi *dbi)
+{
+	MDB_val key, data;
+	MDB_dbi i;
+	int rc, dirty = 0;
+	size_t len;
+
+	/* main DB? */
+	if (!name) {
+		*dbi = MAIN_DBI;
+		if (flags & (MDB_DUPSORT|MDB_REVERSEKEY|MDB_INTEGERKEY))
+			txn->mt_dbs[MAIN_DBI].md_flags |= (flags & (MDB_DUPSORT|MDB_REVERSEKEY|MDB_INTEGERKEY));
+		return MDB_SUCCESS;
+	}
+
+	/* Is the DB already open? */
+	len = strlen(name);
+	for (i=2; i<txn->mt_numdbs; i++) {
+		if (len == txn->mt_dbxs[i].md_name.mv_size &&
+			!strncmp(name, txn->mt_dbxs[i].md_name.mv_data, len)) {
+			*dbi = i;
+			return MDB_SUCCESS;
+		}
+	}
+
+	if (txn->mt_numdbs >= txn->mt_env->me_maxdbs - 1)
+		return ENFILE;
+
+	/* Find the DB info */
+	key.mv_size = len;
+	key.mv_data = (void *)name;
+	rc = mdb_get(txn, MAIN_DBI, &key, &data);
+
+	/* Create if requested */
+	if (rc == MDB_NOTFOUND && (flags & MDB_CREATE)) {
+		MDB_db dummy;
+		data.mv_size = sizeof(MDB_db);
+		data.mv_data = &dummy;
+		memset(&dummy, 0, sizeof(dummy));
+		dummy.md_root = P_INVALID;
+		dummy.md_flags = flags & 0xffff;
+		rc = mdb_put0(txn, MAIN_DBI, &key, &data, F_SUBDATA);
+		dirty = 1;
+	}
+
+	/* OK, got info, add to table */
+	if (rc == MDB_SUCCESS) {
+		txn->mt_dbxs[txn->mt_numdbs].md_name.mv_data = strdup(name);
+		txn->mt_dbxs[txn->mt_numdbs].md_name.mv_size = len;
+		txn->mt_dbxs[txn->mt_numdbs].md_cmp = NULL;
+		txn->mt_dbxs[txn->mt_numdbs].md_dcmp = NULL;
+		txn->mt_dbxs[txn->mt_numdbs].md_rel = NULL;
+		txn->mt_dbxs[txn->mt_numdbs].md_parent = MAIN_DBI;
+		txn->mt_dbxs[txn->mt_numdbs].md_dirty = dirty;
+		memcpy(&txn->mt_dbs[txn->mt_numdbs], data.mv_data, sizeof(MDB_db));
+		*dbi = txn->mt_numdbs;
+		txn->mt_env->me_dbs[0][txn->mt_numdbs] = txn->mt_dbs[txn->mt_numdbs];
+		txn->mt_env->me_dbs[1][txn->mt_numdbs] = txn->mt_dbs[txn->mt_numdbs];
+		txn->mt_numdbs++;
+	}
+
+	return rc;
+}
+
+int mdb_stat(MDB_txn *txn, MDB_dbi dbi, MDB_stat *arg)
+{
+	if (txn == NULL || arg == NULL || dbi >= txn->mt_numdbs)
+		return EINVAL;
+
+	return mdb_stat0(txn->mt_env, &txn->mt_dbs[dbi], arg);
+}
+
+void mdb_close(MDB_txn *txn, MDB_dbi dbi)
+{
+	char *ptr;
+	if (dbi <= MAIN_DBI || dbi >= txn->mt_numdbs)
+		return;
+	ptr = txn->mt_dbxs[dbi].md_name.mv_data;
+	txn->mt_dbxs[dbi].md_name.mv_data = NULL;
+	txn->mt_dbxs[dbi].md_name.mv_size = 0;
+	free(ptr);
+}
+
+int mdb_set_compare(MDB_txn *txn, MDB_dbi dbi, MDB_cmp_func *cmp)
+{
+	if (txn == NULL || !dbi || dbi >= txn->mt_numdbs)
+		return EINVAL;
+
+	txn->mt_dbxs[dbi].md_cmp = cmp;
+	return MDB_SUCCESS;
+}
+
+int mdb_set_dupsort(MDB_txn *txn, MDB_dbi dbi, MDB_cmp_func *cmp)
+{
+	if (txn == NULL || !dbi || dbi >= txn->mt_numdbs)
+		return EINVAL;
+
+	txn->mt_dbxs[dbi].md_dcmp = cmp;
+	return MDB_SUCCESS;
+}
+
+int mdb_set_relfunc(MDB_txn *txn, MDB_dbi dbi, MDB_rel_func *rel)
+{
+	if (txn == NULL || !dbi || dbi >= txn->mt_numdbs)
+		return EINVAL;
+
+	txn->mt_dbxs[dbi].md_rel = rel;
+	return MDB_SUCCESS;
+}