diff --git a/bucket.go b/bucket.go
index 6e7b791..d0b2ac2 100644
--- a/bucket.go
+++ b/bucket.go
@@ -1,5 +1,9 @@
 package bolt
 
+const (
+	MDB_DUPSORT = 0x04
+)
+
 // TODO: #define MDB_VALID	0x8000		/**< DB handle is valid, for me_dbflags */
 // TODO: #define PERSISTENT_FLAGS	(0xffff & ~(MDB_VALID))
 // TODO: #define VALID_FLAGS	(MDB_REVERSEKEY|MDB_DUPSORT|MDB_INTEGERKEY|MDB_DUPFIXED|MDB_INTEGERDUP|MDB_REVERSEDUP|MDB_CREATE)
diff --git a/cursor.go b/cursor.go
index bd85a3b..e5b3444 100644
--- a/cursor.go
+++ b/cursor.go
@@ -2,15 +2,18 @@ package bolt
 
 // TODO: #define CURSOR_STACK		 32
 
-// TODO: #define C_INITIALIZED	0x01	/**< cursor has been initialized and is valid */
-// TODO: #define C_EOF	0x02			/**< No more data */
-// TODO: #define C_SUB	0x04			/**< Cursor is a sub-cursor */
-// TODO: #define C_DEL	0x08			/**< last op was a cursor_del */
-// TODO: #define C_SPLITTING	0x20		/**< Cursor is in page_split */
-// TODO: #define C_UNTRACK	0x40		/**< Un-track cursor when closing */
+const (
+	c_initialized = 0x01 /**< cursor has been initialized and is valid */
+	c_eof         = 0x02 /**< No more data */
+	c_sub         = 0x04 /**< Cursor is a sub-cursor */
+	c_del         = 0x08 /**< last op was a cursor_del */
+	c_splitting   = 0x20 /**< Cursor is in page_split */
+	c_untrack     = 0x40 /**< Un-track cursor when closing */
+)
 
 // TODO: #define MDB_NOSPILL	0x8000 /** Do not spill pages to disk if txn is getting full, may fail instead */
 
+/*
 type Cursor interface {
 	First() error
 	FirstDup() error
@@ -28,37 +31,75 @@ type Cursor interface {
 	Set() ([]byte, []byte, error)
 	SetRange() ([]byte, []byte, error)
 }
+*/
 
-type cursor struct {
+type Cursor struct {
 	flags       int
-	_next       *cursor
-	backup      *cursor
-	xcursor     *xcursor
-	transaction *transaction
+	next        *Cursor
+	backup      *Cursor
+	subcursor   *Cursor
+	transaction *Transaction
 	bucketId    int
-	bucket      *Bucket
-	// bucketx     *bucketx
-	bucketFlag int
-	snum       int
-	top        int
-	page       []*page
-	ki         []int /**< stack of page indices */
+	bucket      *txnbucket
+	subbucket   *Bucket
+	// subbucketx    *bucketx
+	subbucketFlag int
+	snum          int
+	top           int
+	page          []*page
+	ki            []int /**< stack of page indices */
 }
 
-type xcursor struct {
-	cursor cursor
-	bucket *Bucket
-	// bucketx    *bucketx
-	bucketFlag int
+// Initialize a cursor for a given transaction and database.
+func (c *Cursor) init(t *Transaction, b *txnbucket, sub *Cursor) {
+	c.next = nil
+	c.backup = nil
+	c.transaction = t
+	c.bucket = b
+	c.snum = 0
+	c.top = 0
+	// TODO: mc->mc_pg[0] = 0;
+	c.flags = 0
+
+	if (b.flags & MDB_DUPSORT) != 0 {
+		sub.subcursor = nil
+		sub.transaction = t
+		sub.bucket = b
+		sub.snum = 0
+		sub.top = 0
+		sub.flags = c_sub
+		// TODO: mx->mx_dbx.md_name.mv_size = 0;
+		// TODO: mx->mx_dbx.md_name.mv_data = NULL;
+		c.subcursor = sub
+	} else {
+		c.subcursor = nil
+	}
+
+	// Find the root page if the bucket is stale.
+	if (c.bucket.flags & txnb_stale) != 0 {
+		c.findPage(nil, ps_rootonly)
+	}
 }
 
+//                                                                            //
+//                                                                            //
+//                                                                            //
+//                                                                            //
+//                                                                            //
+// ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ CONVERTED ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ //
+//                                                                            //
+//                                                                            //
+//                                                                            //
+//                                                                            //
+//                                                                            //
+
 // Set or clear P_KEEP in dirty, non-overflow, non-sub pages watched by txn.
 // @param[in] mc A cursor handle for the current operation.
 // @param[in] pflags Flags of the pages to update:
 // P_DIRTY to set P_KEEP, P_DIRTY|P_KEEP to clear it.
 // @param[in] all No shortcuts. Needed except after a full #mdb_page_flush().
 // @return 0 on success, non-zero on failure.
-func (c *cursor) xkeep(pflags int, all int) error {
+func (c *Cursor) xkeep(pflags int, all int) error {
 	/*
 		enum { Mask = P_SUBP|P_DIRTY|P_KEEP };
 		MDB_txn *txn = mc->mc_txn;
@@ -149,7 +190,7 @@ func (c *cursor) xkeep(pflags int, all int) error {
 // @param[in] key For a put operation, the key being stored.
 // @param[in] data For a put operation, the data being stored.
 // @return 0 on success, non-zero on failure.
-func (c *cursor) spill(key []byte, data []byte) error {
+func (c *Cursor) spill(key []byte, data []byte) error {
 	/*
 			MDB_txn *txn = m0->mc_txn;
 			MDB_page *dp;
@@ -424,7 +465,7 @@ func (p *page) copyTo(dst *page, size int) {
 // Touch a page: make it dirty and re-insert into tree with updated pgno.
 // @param[in] mc cursor pointing to the page to be touched
 // @return 0 on success, non-zero on failure.
-func (c *cursor) page_touch() int {
+func (c *Cursor) page_touch() int {
 	/*
 			MDB_page *mp = mc->mc_pg[mc->mc_top], *np;
 			MDB_txn *txn = mc->mc_txn;
@@ -532,7 +573,7 @@ func (c *cursor) page_touch() int {
 // in *exactp (1 or 0).
 // Updates the cursor index with the index of the found entry.
 // If no entry larger or equal to the key is found, returns NULL.
-func (c *cursor) search(key []byte) (*node, bool) {
+func (c *Cursor) search(key []byte) (*node, bool) {
 	/*
 			unsigned int	 i = 0, nkeys;
 			int		 low, high;
@@ -623,7 +664,7 @@ func (c *cursor) search(key []byte) (*node, bool) {
 	return nil, false
 }
 
-func (c *cursor) pop() {
+func (c *Cursor) pop() {
 	/*
 			if (mc->mc_snum) {
 		#if MDB_DEBUG
@@ -640,7 +681,7 @@ func (c *cursor) pop() {
 }
 
 /** Push a page onto the top of the cursor's stack. */
-func (c *cursor) push(p *page) error {
+func (c *Cursor) push(p *page) error {
 	/*
 		DPRINTF(("pushing page %"Z"u on db %d cursor %p", mp->mp_pgno,
 			DDBI(mc), (void *) mc));
@@ -661,7 +702,7 @@ func (c *cursor) push(p *page) error {
 
 // Finish #mdb_page_search() / #mdb_page_search_lowest().
 // The cursor is at the root page, set up the rest of it.
-func (c *cursor) searchRoot(key []byte, flags int) error {
+func (c *Cursor) searchRoot(key []byte, flags int) error {
 	/*
 		MDB_page	*mp = mc->mc_pg[mc->mc_top];
 		int rc;
@@ -733,7 +774,7 @@ func (c *cursor) searchRoot(key []byte, flags int) error {
 // before calling mdb_page_search_root(), because the callers
 // are all in situations where the current page is known to
 // be underfilled.
-func (c *cursor) searchLowest() error {
+func (c *Cursor) searchLowest() error {
 	/*
 		MDB_page	*mp = mc->mc_pg[mc->mc_top];
 		MDB_node	*node = NODEPTR(mp, 0);
@@ -760,7 +801,7 @@ func (c *cursor) searchLowest() error {
 //   This is used by #mdb_cursor_first() and #mdb_cursor_last().
 //   If MDB_PS_ROOTONLY set, just fetch root node, no further lookups.
 // @return 0 on success, non-zero on failure.
-func (c *cursor) findPage(key []byte, flags int) error {
+func (c *Cursor) findPage(key []byte, flags int) error {
 	/*
 		int		 rc;
 		pgno_t		 root;
@@ -831,7 +872,7 @@ func (c *cursor) findPage(key []byte, flags int) error {
 	return nil
 }
 
-func (c *cursor) freeOverflowPage(p *page) error {
+func (c *Cursor) freeOverflowPage(p *page) error {
 	/*
 			MDB_txn *txn = mc->mc_txn;
 			pgno_t pg = mp->mp_pgno;
@@ -913,7 +954,7 @@ func (c *cursor) freeOverflowPage(p *page) error {
 // @param[in] move_right Non-zero if the right sibling is requested,
 // otherwise the left sibling.
 // @return 0 on success, non-zero on failure.
-func (c *cursor) sibling(moveRight bool) error {
+func (c *Cursor) sibling(moveRight bool) error {
 	/*
 		int		 rc;
 		MDB_node	*indx;
@@ -964,7 +1005,7 @@ func (c *cursor) sibling(moveRight bool) error {
 }
 
 // Move the cursor to the next data item.
-func (c *cursor) next(key []byte, data []byte, op int) error {
+func (c *Cursor) Next(key []byte, data []byte, op int) error {
 	/*
 			MDB_page	*mp;
 			MDB_node	*leaf;
@@ -1046,7 +1087,7 @@ func (c *cursor) next(key []byte, data []byte, op int) error {
 }
 
 // Move the cursor to the previous data item.
-func (c *cursor) prev(key []byte, data []byte, op int) error {
+func (c *Cursor) prev(key []byte, data []byte, op int) error {
 	/*
 		MDB_page	*mp;
 		MDB_node	*leaf;
@@ -1124,7 +1165,7 @@ func (c *cursor) prev(key []byte, data []byte, op int) error {
 
 // Set the cursor on a specific data item.
 // (bool return is whether it is exact).
-func (c *cursor) set(key []byte, data []byte, op int) (error, bool) {
+func (c *Cursor) set(key []byte, data []byte, op int) (error, bool) {
 	/*
 			int		 rc;
 			MDB_page	*mp;
@@ -1310,7 +1351,7 @@ func (c *cursor) set(key []byte, data []byte, op int) (error, bool) {
 }
 
 // Move the cursor to the first item in the database.
-func (c *cursor) first(key []byte, data []byte) error {
+func (c *Cursor) first(key []byte, data []byte) error {
 	/*
 		int		 rc;
 		MDB_node	*leaf;
@@ -1355,7 +1396,7 @@ func (c *cursor) first(key []byte, data []byte) error {
 }
 
 // Move the cursor to the last item in the database.
-func (c *cursor) last() ([]byte, []byte) {
+func (c *Cursor) last() ([]byte, []byte) {
 	/*
 		int		 rc;
 		MDB_node	*leaf;
@@ -1401,7 +1442,7 @@ func (c *cursor) last() ([]byte, []byte) {
 	return nil, nil
 }
 
-func (c *cursor) Get(key []byte, data []byte, op int) ([]byte, []byte, error) {
+func (c *Cursor) Get(key []byte, data []byte, op int) ([]byte, []byte, error) {
 	/*
 			int		 rc;
 			int		 exact = 0;
@@ -1569,7 +1610,7 @@ func (c *cursor) Get(key []byte, data []byte, op int) ([]byte, []byte, error) {
 // Touch all the pages in the cursor stack. Set mc_top.
 //	Makes sure all the pages are writable, before attempting a write operation.
 // @param[in] mc The cursor to operate on.
-func (c *cursor) touch() error {
+func (c *Cursor) touch() error {
 	/*
 			int rc = MDB_SUCCESS;
 
@@ -2072,7 +2113,7 @@ func (c *cursor) touch() error {
 	return nil
 }
 
-func (c *cursor) Del(flags int) error {
+func (c *Cursor) Del(flags int) error {
 	/*
 		MDB_node	*leaf;
 		MDB_page	*mp;
@@ -2152,7 +2193,7 @@ func (c *cursor) Del(flags int) error {
 // unless allocating overflow pages for a large record.
 // @param[out] mp Address of a page, or NULL on failure.
 // @return 0 on success, non-zero on failure.
-func (c *cursor) newPage(flags int, num int) ([]*page, error) {
+func (c *Cursor) newPage(flags int, num int) ([]*page, error) {
 	/*
 		MDB_page	*np;
 		int rc;
@@ -2194,7 +2235,7 @@ func (c *cursor) newPage(flags int, num int) ([]*page, error) {
 //	should never happen since all callers already calculate the
 //	page's free space before calling this function.
 // </ul>
-func (c *cursor) addNode(index int, key []byte, data []byte, pgno int, flags int) error {
+func (c *Cursor) addNode(index int, key []byte, data []byte, pgno int, flags int) error {
 	/*
 			unsigned int	 i;
 			size_t		 node_size = NODESIZE;
@@ -2323,7 +2364,7 @@ func (c *cursor) addNode(index int, key []byte, data []byte, pgno int, flags int
 // @param[in] indx The index of the node to delete.
 // @param[in] ksize The size of a node. Only used if the page is
 // part of a #MDB_DUPFIXED database.
-func (c *cursor) deleteNode(ksize int) {
+func (c *Cursor) deleteNode(ksize int) {
 	/*
 		MDB_page *mp = mc->mc_pg[mc->mc_top];
 		indx_t	indx = mc->mc_ki[mc->mc_top];
@@ -2375,41 +2416,12 @@ func (c *cursor) deleteNode(ksize int) {
 	*/
 }
 
-// Initial setup of a sorted-dups cursor.
-// Sorted duplicates are implemented as a sub-database for the given key.
-// The duplicate data items are actually keys of the sub-database.
-// Operations on the duplicate data items are performed using a sub-cursor
-// initialized when the sub-database is first accessed. This function does
-// the preliminary setup of the sub-cursor, filling in the fields that
-// depend only on the parent DB.
-// @param[in] mc The main cursor whose sorted-dups cursor is to be initialized.
-func (c *cursor) xcursor_init0() {
-	/*
-		MDB_xcursor *mx = mc->mc_xcursor;
-
-		mx->mx_cursor.mc_xcursor = NULL;
-		mx->mx_cursor.mc_txn = mc->mc_txn;
-		mx->mx_cursor.mc_db = &mx->mx_db;
-		mx->mx_cursor.mc_dbx = &mx->mx_dbx;
-		mx->mx_cursor.mc_dbi = mc->mc_dbi;
-		mx->mx_cursor.mc_dbflag = &mx->mx_dbflag;
-		mx->mx_cursor.mc_snum = 0;
-		mx->mx_cursor.mc_top = 0;
-		mx->mx_cursor.mc_flags = C_SUB;
-		mx->mx_dbx.md_name.mv_size = 0;
-		mx->mx_dbx.md_name.mv_data = NULL;
-		mx->mx_dbx.md_cmp = mc->mc_dbx->md_dcmp;
-		mx->mx_dbx.md_dcmp = NULL;
-		mx->mx_dbx.md_rel = mc->mc_dbx->md_rel;
-	*/
-}
-
 // Final setup of a sorted-dups cursor.
 //	Sets up the fields that depend on the data from the main cursor.
 // @param[in] mc The main cursor whose sorted-dups cursor is to be initialized.
 // @param[in] node The data containing the #MDB_db record for the
 // sorted-dup database.
-func (c *cursor) xcursor_init1(n *node) {
+func (c *Cursor) xcursor_init1(n *node) {
 	/*
 			MDB_xcursor *mx = mc->mc_xcursor;
 
@@ -2455,35 +2467,8 @@ func (c *cursor) xcursor_init1(n *node) {
 	*/
 }
 
-// Initialize a cursor for a given transaction and database.
-func (c *cursor) init(t *transaction, bucket *Bucket, mx *xcursor) {
-	/*
-		mc->mc_next = NULL;
-		mc->mc_backup = NULL;
-		mc->mc_dbi = dbi;
-		mc->mc_txn = txn;
-		mc->mc_db = &txn->mt_dbs[dbi];
-		mc->mc_dbx = &txn->mt_dbxs[dbi];
-		mc->mc_dbflag = &txn->mt_dbflags[dbi];
-		mc->mc_snum = 0;
-		mc->mc_top = 0;
-		mc->mc_pg[0] = 0;
-		mc->mc_flags = 0;
-		if (txn->mt_dbs[dbi].md_flags & MDB_DUPSORT) {
-			mdb_tassert(txn, mx != NULL);
-			mc->mc_xcursor = mx;
-			mdb_xcursor_init0(mc);
-		} else {
-			mc->mc_xcursor = NULL;
-		}
-		if (*mc->mc_dbflag & DB_STALE) {
-			mdb_page_search(mc, NULL, MDB_PS_ROOTONLY);
-		}
-	*/
-}
-
 // Return the count of duplicate data items for the current key.
-func (c *cursor) count() (int, error) {
+func (c *Cursor) count() (int, error) {
 	/*
 		MDB_node	*leaf;
 
@@ -2507,7 +2492,7 @@ func (c *cursor) count() (int, error) {
 	return 0, nil
 }
 
-func (c *cursor) Close() {
+func (c *Cursor) Close() {
 	/*
 		if (mc && !mc->mc_backup) {
 			// remove from txn, if tracked
@@ -2522,23 +2507,19 @@ func (c *cursor) Close() {
 	*/
 }
 
-func (c *cursor) Transaction() Transaction {
-	/*
-		if (!mc) return NULL;
-		return mc->mc_txn;
-	*/
-	return nil
+func (c *Cursor) Transaction() *Transaction {
+	return c.transaction
 }
 
-func (c *cursor) Bucket() *Bucket {
-	return c.bucket
+func (c *Cursor) Bucket() *Bucket {
+	return c.bucket.bucket
 }
 
 // Replace the key for a branch node with a new key.
 // @param[in] mc Cursor pointing to the node to operate on.
 // @param[in] key The new key to use.
 // @return 0 on success, non-zero on failure.
-func (c *cursor) updateKey(key []byte) error {
+func (c *Cursor) updateKey(key []byte) error {
 	/*
 			MDB_page		*mp;
 			MDB_node		*node;
@@ -2609,7 +2590,7 @@ func (c *cursor) updateKey(key []byte) error {
 }
 
 // Move a node from csrc to cdst.
-func (c *cursor) moveNodeTo(dst *cursor) error {
+func (c *Cursor) moveNodeTo(dst *Cursor) error {
 	/*
 		MDB_node		*srcnode;
 		MDB_val		 key, data;
@@ -2786,7 +2767,7 @@ func (c *cursor) moveNodeTo(dst *cursor) error {
 //	the \b csrc page will be freed.
 // @param[in] csrc Cursor pointing to the source page.
 // @param[in] cdst Cursor pointing to the destination page.
-func (c *cursor) mergePage(dst *cursor) error {
+func (c *Cursor) mergePage(dst *Cursor) error {
 	/*
 		int			 rc;
 		indx_t			 i, j;
@@ -2901,7 +2882,7 @@ func (c *cursor) mergePage(dst *cursor) error {
 // Copy the contents of a cursor.
 // @param[in] csrc The cursor to copy from.
 // @param[out] cdst The cursor to copy to.
-func (c *cursor) copyTo(dst *cursor) {
+func (c *Cursor) copyTo(dst *Cursor) {
 	/*
 		unsigned int i;
 
@@ -2924,7 +2905,7 @@ func (c *cursor) copyTo(dst *cursor) {
 // @param[in] mc Cursor pointing to the page where rebalancing
 // should begin.
 // @return 0 on success, non-zero on failure.
-func (c *cursor) rebalance() error {
+func (c *Cursor) rebalance() error {
 	/*
 		MDB_node	*node;
 		int rc;
@@ -3079,7 +3060,7 @@ func (c *cursor) rebalance() error {
 }
 
 // Complete a delete operation started by #mdb_cursor_del().
-func (c *cursor) del0(leaf *node) error {
+func (c *Cursor) del0(leaf *node) error {
 	/*
 		int rc;
 		MDB_page *mp;
@@ -3149,7 +3130,7 @@ func (c *cursor) del0(leaf *node) error {
 // @param[in] newpgno The page number, if the new node is a branch node.
 // @param[in] nflags The #NODE_ADD_FLAGS for the new node.
 // @return 0 on success, non-zero on failure.
-func (c *cursor) splitPage(newKey []byte, newData []byte, newpgno int, nflags int) error {
+func (c *Cursor) splitPage(newKey []byte, newData []byte, newpgno int, nflags int) error {
 	/*
 		unsigned int flags;
 		int		 rc = MDB_SUCCESS, new_root = 0, did_split = 0;
@@ -3533,7 +3514,7 @@ func (c *cursor) splitPage(newKey []byte, newData []byte, newpgno int, nflags in
 // @param[in] mc Cursor on the DB to free.
 // @param[in] subs non-Zero to check for sub-DBs in this DB.
 // @return 0 on success, non-zero on failure.
-func (c *cursor) drop0(subs int) error {
+func (c *Cursor) drop0(subs int) error {
 	/*
 		int rc;
 
diff --git a/db.go b/db.go
index f5c103d..b13ec5f 100644
--- a/db.go
+++ b/db.go
@@ -15,7 +15,9 @@ const (
 	IntegerDupKey
 )
 
-var DatabaseAlreadyOpenedError = &Error{"Database already open", nil}
+var DatabaseNotOpenError = &Error{"db is not open", nil}
+var DatabaseAlreadyOpenedError = &Error{"db already open", nil}
+var TransactionInProgressError = &Error{"writable transaction is already in progress", nil}
 
 // TODO: #define	MDB_FATAL_ERROR	0x80000000U /** Failed to update the meta page. Probably an I/O error. */
 // TODO: #define	MDB_ENV_ACTIVE	0x20000000U /** Some fields are initialized. */
@@ -44,9 +46,9 @@ type DB struct {
 	mmapSize        int /**< size of the data memory map */
 	size            int /**< current file size */
 	pbuf            []byte
-	transaction     *transaction /**< current write transaction */
+	transaction     *Transaction /**< current write transaction */
 	maxPageNumber   int          /**< me_mapsize / me_psize */
-	pageState       pageState    /**< state of old pages from freeDB */
+	pagestate       pagestate    /**< state of old pages from freeDB */
 	dpages          []*page      /**< list of malloc'd blocks for re-use */
 	freePages       []int        /** IDL of pages that became unused in a write txn */
 	dirtyPages      []int        /** ID2L of pages written during a write txn. Length MDB_IDL_UM_SIZE. */
@@ -203,12 +205,50 @@ func (db *DB) close() {
 	// TODO
 }
 
+// Transaction creates a transaction that's associated with this database.
+func (db *DB) Transaction(writable bool) (*Transaction, error) {
+	db.Lock()
+	defer db.Unlock()
+
+	// Exit if the database is not open yet.
+	if !db.opened {
+		return nil, DatabaseNotOpenError
+	}
+	// Exit if a writable transaction is currently in progress.
+	if writable && db.transaction != nil {
+		return nil, TransactionInProgressError
+	}
+
+	// Create a transaction associated with the database.
+	t := &Transaction{
+		db:       db,
+		writable: writable,
+	}
+
+	// We only allow one writable transaction at a time so save the reference.
+	if writable {
+		db.transaction = t
+	}
+
+	return t, nil
+}
+
 // page retrieves a page reference from a given byte array based on the current page size.
 func (db *DB) page(b []byte, id int) *page {
 	return (*page)(unsafe.Pointer(&b[id*db.pageSize]))
 }
 
+//                                                                            //
+//                                                                            //
+//                                                                            //
+//                                                                            //
+//                                                                            //
 // ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ CONVERTED ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ //
+//                                                                            //
+//                                                                            //
+//                                                                            //
+//                                                                            //
+//                                                                            //
 
 func (db *DB) freePage(p *page) {
 	/*
@@ -266,103 +306,6 @@ func (db *DB) sync(force bool) error {
 	return nil
 }
 
-func (db *DB) Transaction(parent *transaction, flags int) (*transaction, error) {
-	/*
-		MDB_txn *txn;
-		MDB_ntxn *ntxn;
-		int rc, size, tsize = sizeof(MDB_txn);
-
-		if (env->me_flags & MDB_FATAL_ERROR) {
-			DPUTS("environment had fatal error, must shutdown!");
-			return MDB_PANIC;
-		}
-		if ((env->me_flags & MDB_RDONLY) && !(flags & MDB_RDONLY))
-			return EACCES;
-		if (parent) {
-			// Nested transactions: Max 1 child, write txns only, no writemap
-			if (parent->mt_child ||
-				(flags & MDB_RDONLY) ||
-				(parent->mt_flags & (MDB_TXN_RDONLY|MDB_TXN_ERROR)) ||
-				(env->me_flags & MDB_WRITEMAP))
-			{
-				return (parent->mt_flags & MDB_TXN_RDONLY) ? EINVAL : MDB_BAD_TXN;
-			}
-			tsize = sizeof(MDB_ntxn);
-		}
-		size = tsize + env->me_maxdbs * (sizeof(MDB_db)+1);
-		if (!(flags & MDB_RDONLY))
-			size += env->me_maxdbs * sizeof(MDB_cursor *);
-
-		if ((txn = calloc(1, size)) == NULL) {
-			DPRINTF(("calloc: %s", strerror(ErrCode())));
-			return ENOMEM;
-		}
-		txn->mt_dbs = (MDB_db *) ((char *)txn + tsize);
-		if (flags & MDB_RDONLY) {
-			txn->mt_flags |= MDB_TXN_RDONLY;
-			txn->mt_dbflags = (unsigned char *)(txn->mt_dbs + env->me_maxdbs);
-		} else {
-			txn->mt_cursors = (MDB_cursor **)(txn->mt_dbs + env->me_maxdbs);
-			txn->mt_dbflags = (unsigned char *)(txn->mt_cursors + env->me_maxdbs);
-		}
-		txn->mt_env = env;
-
-		if (parent) {
-			unsigned int i;
-			txn->mt_u.dirty_list = malloc(sizeof(MDB_ID2)*MDB_IDL_UM_SIZE);
-			if (!txn->mt_u.dirty_list ||
-				!(txn->mt_free_pgs = mdb_midl_alloc(MDB_IDL_UM_MAX)))
-			{
-				free(txn->mt_u.dirty_list);
-				free(txn);
-				return ENOMEM;
-			}
-			txn->mt_txnid = parent->mt_txnid;
-			txn->mt_dirty_room = parent->mt_dirty_room;
-			txn->mt_u.dirty_list[0].mid = 0;
-			txn->mt_spill_pgs = NULL;
-			txn->mt_next_pgno = parent->mt_next_pgno;
-			parent->mt_child = txn;
-			txn->mt_parent = parent;
-			txn->mt_numdbs = parent->mt_numdbs;
-			txn->mt_flags = parent->mt_flags;
-			txn->mt_dbxs = parent->mt_dbxs;
-			memcpy(txn->mt_dbs, parent->mt_dbs, txn->mt_numdbs * sizeof(MDB_db));
-			// Copy parent's mt_dbflags, but clear DB_NEW
-			for (i=0; i<txn->mt_numdbs; i++)
-				txn->mt_dbflags[i] = parent->mt_dbflags[i] & ~DB_NEW;
-			rc = 0;
-			ntxn = (MDB_ntxn *)txn;
-			ntxn->mnt_pgstate = env->me_pgstate; // save parent me_pghead & co
-			if (env->me_pghead) {
-				size = MDB_IDL_SIZEOF(env->me_pghead);
-				env->me_pghead = mdb_midl_alloc(env->me_pghead[0]);
-				if (env->me_pghead)
-					memcpy(env->me_pghead, ntxn->mnt_pgstate.mf_pghead, size);
-				else
-					rc = ENOMEM;
-			}
-			if (!rc)
-				rc = mdb_cursor_shadow(parent, txn);
-			if (rc)
-				mdb_txn_reset0(txn, "beginchild-fail");
-		} else {
-			rc = mdb_txn_renew0(txn);
-		}
-		if (rc)
-			free(txn);
-		else {
-			*ret = txn;
-			DPRINTF(("begin txn %"Z"u%c %p on mdbenv %p, root page %"Z"u",
-				txn->mt_txnid, (txn->mt_flags & MDB_TXN_RDONLY) ? 'r' : 'w',
-				(void *) txn, (void *) env, txn->mt_dbs[MAIN_DBI].md_root));
-		}
-
-		return rc;
-	*/
-	return nil, nil
-}
-
 // Check both meta pages to see which one is newer.
 // @param[in] env the environment handle
 // @return meta toggle (0 or 1).
diff --git a/db_test.go b/db_test.go
index cf36c37..b9c4afe 100644
--- a/db_test.go
+++ b/db_test.go
@@ -180,6 +180,41 @@ func TestDBCorruptMeta1(t *testing.T) {
 	})
 }
 
+//--------------------------------------
+// Transaction()
+//--------------------------------------
+
+// Ensure that a database cannot open a transaction when it's not open.
+func TestDBTransactionDatabaseNotOpenError(t *testing.T) {
+	withDB(func(db *DB, path string) {
+		txn, err := db.Transaction(false)
+		assert.Nil(t, txn)
+		assert.Equal(t, err, DatabaseNotOpenError)
+	})
+}
+
+// Ensure that a database cannot open a writable transaction while one is in progress.
+func TestDBTransactionInProgressError(t *testing.T) {
+	withOpenDB(func(db *DB, path string) {
+		db.Transaction(true)
+		txn, err := db.Transaction(true)
+		assert.Nil(t, txn)
+		assert.Equal(t, err, TransactionInProgressError)
+	})
+}
+
+// Ensure that a database can create a new writable transaction.
+func TestDBTransactionWriter(t *testing.T) {
+	withOpenDB(func(db *DB, path string) {
+		txn, err := db.Transaction(true)
+		if assert.NotNil(t, txn) {
+			assert.Equal(t, txn.db, db)
+			assert.Equal(t, txn.writable, true)
+		}
+		assert.NoError(t, err)
+	})
+}
+
 // withDB executes a function with a database reference.
 func withDB(fn func(*DB, string)) {
 	f, _ := ioutil.TempFile("", "bolt-")
@@ -200,3 +235,14 @@ func withMockDB(fn func(*DB, *mockos, *mocksyscall, string)) {
 	db.syscall = syscall
 	fn(db, os, syscall, "/mock/db")
 }
+
+// withOpenDB executes a function with an already opened database.
+func withOpenDB(fn func(*DB, string)) {
+	withDB(func(db *DB, path string) {
+		if err := db.Open(path, 0666); err != nil {
+			panic("cannot open db: " + err.Error())
+		}
+		defer db.Close()
+		fn(db, path)
+	})
+}
diff --git a/page.go b/page.go
index 5827f96..33fa0c2 100644
--- a/page.go
+++ b/page.go
@@ -38,10 +38,12 @@ const maxWriteByteCount uint = 0x80000000 // TODO: #define MAX_WRITE 0x80000000U
 // #define MDB_COMMIT_PAGES	IOV_MAX
 // #endif
 
-// TODO: #define MDB_PS_MODIFY	1
-// TODO: #define MDB_PS_ROOTONLY	2
-// TODO: #define MDB_PS_FIRST	4
-// TODO: #define MDB_PS_LAST		8
+const (
+	MDB_PS_MODIFY   = 1
+	MDB_PS_ROOTONLY = 2
+	MDB_PS_FIRST    = 4
+	MDB_PS_LAST     = 8
+)
 
 // TODO: #define MDB_SPLIT_REPLACE	MDB_APPENDDUP	/**< newkey is not new */
 
@@ -58,7 +60,7 @@ type page struct {
 	ptr      int
 }
 
-type pageState struct {
+type pagestate struct {
 	head int /**< Reclaimed freeDB pages, or NULL before use */
 	last int /**< ID of last used record, or 0 if !mf_pghead */
 }
diff --git a/transaction.go b/transaction.go
index 4ca2d35..4525a31 100644
--- a/transaction.go
+++ b/transaction.go
@@ -1,44 +1,143 @@
 package bolt
 
-// TODO: #define DB_DIRTY	0x01		/**< DB was modified or is DUPSORT data */
-// TODO: #define DB_STALE	0x02		/**< Named-DB record is older than txnID */
-// TODO: #define DB_NEW		0x04		/**< Named-DB handle opened in this txn */
-// TODO: #define DB_VALID	0x08		/**< DB handle is valid, see also #MDB_VALID */
+var TransactionExistingChildError = &Error{"txn already has a child", nil}
+var TransactionReadOnlyChildError = &Error{"read-only txn cannot create a child", nil}
 
-// TODO: #define MDB_TXN_RDONLY		0x01		/**< read-only transaction */
-// TODO: #define MDB_TXN_ERROR		0x02		/**< an error has occurred */
-// TODO: #define MDB_TXN_DIRTY		0x04		/**< must write, even if dirty list is empty */
-// TODO: #define MDB_TXN_SPILLS		0x08		/**< txn or a parent has spilled pages */
+const (
+	txnb_dirty = 0x01 /**< DB was modified or is DUPSORT data */
+	txnb_stale = 0x02 /**< Named-DB record is older than txnID */
+	txnb_new   = 0x04 /**< Named-DB handle opened in this txn */
+	txnb_valid = 0x08 /**< DB handle is valid, see also #MDB_VALID */
+)
 
-type Transaction interface {
-}
+const (
+	ps_modify   = 1
+	ps_rootonly = 2
+	ps_first    = 4
+	ps_last     = 8
+)
 
-type transaction struct {
-	id             int
-	flags          int
-	db             *DB
-	parent         *transaction
-	child          *transaction
-	nextPageNumber int
-	freePages      []int
-	spillPages     []int
-	dirtyList      []int
-	reader         *reader
+type Transaction struct {
+	id       int
+	db       *DB
+	writable bool
+	dirty    bool
+	spilled  bool
+	err      error
+	parent   *Transaction
+	child    *Transaction
+	buckets  []*txnbucket
+
+	pgno       int
+	freePages  []pgno
+	spillPages []pgno
+	dirtyList  []pgno
+	reader     *reader
 	// TODO: bucketxs []*bucketx
-	buckets     []*Bucket
-	bucketFlags []int
-	cursors     []*cursor
 	// Implicit from slices? TODO: MDB_dbi mt_numdbs;
-	mt_dirty_room int
+	dirty_room int
+	pagestate  pagestate
 }
 
-// ntxn represents a nested transaction.
-type ntxn struct {
-	transaction *transaction /**< the transaction */
-	pageState   pageState    /**< parent transaction's saved freestate */
+type txnbucket struct {
+	bucket *Bucket
+	cursor *Cursor
+	flags  int
 }
 
-func (t *transaction) allocPage(num int) *page {
+// Transaction begins a nested child transaction. Child transactions are only
+// available to writable transactions and a transaction can only have one child
+// at a time.
+func (t *Transaction) Transaction() (*Transaction, error) {
+	// Exit if parent already has a child transaction.
+	if t.child != nil {
+		return nil, TransactionExistingChildError
+	}
+	// Exit if using parent for read-only transaction.
+	if !t.writable {
+		return nil, TransactionReadOnlyChildError
+	}
+	// TODO: Exit if parent is in an error state.
+
+	// Create the child transaction and attach the parent.
+	child := &Transaction{
+		id:        t.id,
+		db:        t.db,
+		parent:    t,
+		writable:  true,
+		pgno:      t.pgno,
+		pagestate: t.db.pagestate,
+	}
+	copy(child.buckets, t.buckets)
+
+	// TODO: Remove DB_NEW flag.
+	t.child = child
+
+	// TODO: wtf?
+	// if (env->me_pghead) {
+	//   size = MDB_IDL_SIZEOF(env->me_pghead);
+	//   env->me_pghead = mdb_midl_alloc(env->me_pghead[0]);
+	//   if (env->me_pghead)
+	//     memcpy(env->me_pghead, ntxn->mnt_pgstate.mf_pghead, size);
+	//   else
+	//     rc = ENOMEM;
+	// }
+
+	// TODO: Back up parent transaction's cursors.
+	// if t.shadow(child); err != nil {
+	// 	child.reset0()
+	// 	return err
+	// }
+
+	return child, nil
+}
+
+func (t *Transaction) Cursor(b *Bucket) (*Cursor, error) {
+	// TODO: if !(txn->mt_dbflags[dbi] & DB_VALID) return InvalidBucketError
+	// TODO: if (txn->mt_flags & MDB_TXN_ERROR) return BadTransactionError
+
+	// Allow read access to the freelist
+	// TODO: if (!dbi && !F_ISSET(txn->mt_flags, MDB_TXN_RDONLY))
+
+	/*
+		MDB_cursor	*mc;
+		size_t size = sizeof(MDB_cursor);
+
+		// Allow read access to the freelist
+		if (!dbi && !F_ISSET(txn->mt_flags, MDB_TXN_RDONLY))
+			return EINVAL;
+
+		if ((mc = malloc(size)) != NULL) {
+			mdb_cursor_init(mc, txn, dbi, (MDB_xcursor *)(mc + 1));
+			if (txn->mt_cursors) {
+				mc->mc_next = txn->mt_cursors[dbi];
+				txn->mt_cursors[dbi] = mc;
+				mc->mc_flags |= C_UNTRACK;
+			}
+		} else {
+			return ENOMEM;
+		}
+
+		*ret = mc;
+
+		return MDB_SUCCESS;
+	*/
+	return nil, nil
+}
+
+//                                                                            //
+//                                                                            //
+//                                                                            //
+//                                                                            //
+//                                                                            //
+// ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ CONVERTED ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ //
+//                                                                            //
+//                                                                            //
+//                                                                            //
+//                                                                            //
+//                                                                            //
+
+func (t *Transaction) allocPage(num int) *page {
 	/*
 		MDB_env *env = txn->mt_env;
 		MDB_page *ret = env->me_dpages;
@@ -74,7 +173,7 @@ func (t *transaction) allocPage(num int) *page {
 }
 
 // Find oldest txnid still referenced. Expects txn->mt_txnid > 0.
-func (t *transaction) oldest() int {
+func (t *Transaction) oldest() int {
 	/*
 		int i;
 		txnid_t mr, oldest = txn->mt_txnid - 1;
@@ -94,7 +193,7 @@ func (t *transaction) oldest() int {
 }
 
 // Add a page to the txn's dirty list
-func (t *transaction) dirty(p *page) {
+func (t *Transaction) addDirtyPage(p *page) {
 	/*
 		MDB_ID2 mid;
 		int rc, (*insert)(MDB_ID2L, MDB_ID2 *);
@@ -119,7 +218,7 @@ func (t *transaction) dirty(p *page) {
 // @param[in] mp the page being referenced. It must not be dirty.
 // @param[out] ret the writable page, if any. ret is unchanged if
 // mp wasn't spilled.
-func (t *transaction) unspill(p *page) *page {
+func (t *Transaction) unspill(p *page) *page {
 	/*
 		MDB_env *env = txn->mt_env;
 		const MDB_txn *tx2;
@@ -173,7 +272,7 @@ func (t *transaction) unspill(p *page) *page {
 }
 
 // Back up parent txn's cursors, then grab the originals for tracking
-func (t *transaction) shadow(dst *transaction) error {
+func (t *Transaction) shadow(dst *Transaction) error {
 	/*
 		MDB_cursor *mc, *bk;
 		MDB_xcursor *mx;
@@ -214,7 +313,7 @@ func (t *transaction) shadow(dst *transaction) error {
 // @param[in] txn the transaction handle.
 // @param[in] merge true to keep changes to parent cursors, false to revert.
 // @return 0 on success, non-zero on failure.
-func (t *transaction) closeCursors(merge bool) {
+func (t *Transaction) closeCursors(merge bool) {
 	/*
 		MDB_cursor **cursors = txn->mt_cursors, *mc, *next, *bk;
 		MDB_xcursor *mx;
@@ -252,7 +351,7 @@ func (t *transaction) closeCursors(merge bool) {
 // Common code for #mdb_txn_begin() and #mdb_txn_renew().
 // @param[in] txn the transaction handle to initialize
 // @return 0 on success, non-zero on failure.
-func (t *transaction) renew() error {
+func (t *Transaction) renew() error {
 	/*
 			MDB_env *env = txn->mt_env;
 			MDB_txninfo *ti = env->me_txns;
@@ -366,7 +465,7 @@ func (t *transaction) renew() error {
 	return nil
 }
 
-func (t *transaction) Renew() error {
+func (t *Transaction) Renew() error {
 	/*
 		int rc;
 
@@ -389,12 +488,12 @@ func (t *transaction) Renew() error {
 	return nil
 }
 
-func (t *transaction) DB() *DB {
+func (t *Transaction) DB() *DB {
 	return t.db
 }
 
 // Export or close DBI handles opened in this txn.
-func (t *transaction) updateBuckets(keep bool) {
+func (t *Transaction) updateBuckets(keep bool) {
 	/*
 		int i;
 		MDB_dbi n = txn->mt_numdbs;
@@ -423,7 +522,7 @@ func (t *transaction) updateBuckets(keep bool) {
 // May be called twice for readonly txns: First reset it, then abort.
 // @param[in] txn the transaction handle to reset
 // @param[in] act why the transaction is being reset
-func (t *transaction) reset(act string) {
+func (t *Transaction) reset(act string) {
 	/*
 		MDB_env	*env = txn->mt_env;
 
@@ -472,7 +571,7 @@ func (t *transaction) reset(act string) {
 	*/
 }
 
-func (t *transaction) Reset() {
+func (t *Transaction) Reset() {
 	/*
 		if (txn == NULL)
 			return;
@@ -485,7 +584,7 @@ func (t *transaction) Reset() {
 	*/
 }
 
-func (t *transaction) Abort() {
+func (t *Transaction) Abort() {
 	/*
 		if (txn == NULL)
 			return;
@@ -504,7 +603,7 @@ func (t *transaction) Abort() {
 
 // Save the freelist as of this transaction to the freeDB.
 // This changes the freelist. Keep trying until it stabilizes.
-func (t *transaction) saveFreelist() error {
+func (t *Transaction) saveFreelist() error {
 	/*
 			// env->me_pghead[] can grow and shrink during this call.
 			// env->me_pglast and txn->mt_free_pgs[] can only grow.
@@ -662,7 +761,7 @@ func (t *transaction) saveFreelist() error {
 // @param[in] txn the transaction that's being committed
 // @param[in] keep number of initial pages in dirty_list to keep dirty.
 // @return 0 on success, non-zero on failure.
-func (t *transaction) flush(keep bool) error {
+func (t *Transaction) flush(keep bool) error {
 	/*
 			MDB_env		*env = txn->mt_env;
 			MDB_ID2L	dl = txn->mt_u.dirty_list;
@@ -1005,7 +1104,7 @@ func (t *transaction) flush(keep bool) error {
 // Update the environment info to commit a transaction.
 // @param[in] txn the transaction that's being committed
 // @return 0 on success, non-zero on failure.
-func (t *transaction) writeMeta() error {
+func (t *Transaction) writeMeta() error {
 	/*
 			MDB_env *env;
 			MDB_meta	meta, metab, *mp;
@@ -1129,7 +1228,7 @@ func (t *transaction) writeMeta() error {
 // @param[out] ret address of a pointer where the page's address will be stored.
 // @param[out] lvl dirty_list inheritance level of found page. 1=current txn, 0=mapped page.
 // @return 0 on success, non-zero on failure.
-func (t *transaction) getPage(id int) (*page, int, error) {
+func (t *Transaction) getPage(id int) (*page, int, error) {
 	/*
 			MDB_env *env = txn->mt_env;
 			MDB_page *p = NULL;
@@ -1188,7 +1287,7 @@ func (t *transaction) getPage(id int) (*page, int, error) {
 // @param[in] leaf The node being read.
 // @param[out] data Updated to point to the node's data.
 // @return 0 on success, non-zero on failure.
-func (t *transaction) readNode(leaf *node, data []byte) error {
+func (t *Transaction) readNode(leaf *node, data []byte) error {
 	/*
 		MDB_page	*omp;		// overflow page
 		pgno_t		 pgno;
@@ -1214,7 +1313,7 @@ func (t *transaction) readNode(leaf *node, data []byte) error {
 	return nil
 }
 
-func (t *transaction) Get(bucket Bucket, key []byte) ([]byte, error) {
+func (t *Transaction) Get(bucket Bucket, key []byte) ([]byte, error) {
 	/*
 		MDB_cursor	mc;
 		MDB_xcursor	mx;
@@ -1238,43 +1337,7 @@ func (t *transaction) Get(bucket Bucket, key []byte) ([]byte, error) {
 	return nil, nil
 }
 
-func (t *transaction) Cursor(b Bucket) (Cursor, error) {
-	/*
-		MDB_cursor	*mc;
-		size_t size = sizeof(MDB_cursor);
-
-		if (txn == NULL || ret == NULL || dbi >= txn->mt_numdbs || !(txn->mt_dbflags[dbi] & DB_VALID))
-			return EINVAL;
-
-		if (txn->mt_flags & MDB_TXN_ERROR)
-			return MDB_BAD_TXN;
-
-		// Allow read access to the freelist
-		if (!dbi && !F_ISSET(txn->mt_flags, MDB_TXN_RDONLY))
-			return EINVAL;
-
-		if (txn->mt_dbs[dbi].md_flags & MDB_DUPSORT)
-			size += sizeof(MDB_xcursor);
-
-		if ((mc = malloc(size)) != NULL) {
-			mdb_cursor_init(mc, txn, dbi, (MDB_xcursor *)(mc + 1));
-			if (txn->mt_cursors) {
-				mc->mc_next = txn->mt_cursors[dbi];
-				txn->mt_cursors[dbi] = mc;
-				mc->mc_flags |= C_UNTRACK;
-			}
-		} else {
-			return ENOMEM;
-		}
-
-		*ret = mc;
-
-		return MDB_SUCCESS;
-	*/
-	return nil, nil
-}
-
-func (t *transaction) Renew1(c Cursor) error {
+func (t *Transaction) Renew1(c Cursor) error {
 	/*
 		if (txn == NULL || mc == NULL || mc->mc_dbi >= txn->mt_numdbs)
 			return EINVAL;
@@ -1288,7 +1351,7 @@ func (t *transaction) Renew1(c Cursor) error {
 	return nil
 }
 
-func (t *transaction) Delete(b *Bucket, key []byte, data []byte) error {
+func (t *Transaction) Delete(b *Bucket, key []byte, data []byte) error {
 	/*
 		MDB_cursor mc;
 		MDB_xcursor mx;
@@ -1343,7 +1406,7 @@ func (t *transaction) Delete(b *Bucket, key []byte, data []byte) error {
 	return nil
 }
 
-func (t *transaction) Put(b Bucket, key []byte, data []byte, flags int) error {
+func (t *Transaction) Put(b Bucket, key []byte, data []byte, flags int) error {
 	/*
 		MDB_cursor mc;
 		MDB_xcursor mx;
@@ -1363,7 +1426,7 @@ func (t *transaction) Put(b Bucket, key []byte, data []byte, flags int) error {
 	return nil
 }
 
-func (t *transaction) Bucket(name string, flags int) (*Bucket, error) {
+func (t *Transaction) Bucket(name string, flags int) (*Bucket, error) {
 	/*
 		MDB_val key, data;
 		MDB_dbi i;
@@ -1467,7 +1530,7 @@ func (t *transaction) Bucket(name string, flags int) (*Bucket, error) {
 	return nil, nil
 }
 
-func (t *transaction) Stat(b Bucket) *stat {
+func (t *Transaction) Stat(b Bucket) *stat {
 	/*
 		if (txn == NULL || arg == NULL || dbi >= txn->mt_numdbs)
 			return EINVAL;
@@ -1483,7 +1546,7 @@ func (t *transaction) Stat(b Bucket) *stat {
 	return nil
 }
 
-func (t *transaction) BucketFlags(b Bucket) (int, error) {
+func (t *Transaction) BucketFlags(b Bucket) (int, error) {
 	/*
 		// We could return the flags for the FREE_DBI too but what's the point?
 		if (txn == NULL || dbi < MAIN_DBI || dbi >= txn->mt_numdbs)
@@ -1494,7 +1557,7 @@ func (t *transaction) BucketFlags(b Bucket) (int, error) {
 	return 0, nil
 }
 
-func (t *transaction) Drop(b *Bucket, del int) error {
+func (t *Transaction) Drop(b *Bucket, del int) error {
 	/*
 			MDB_cursor *mc, *m2;
 			int rc;