Prep for next commit: C_WRITEMAP, C_ORIG_RDONLY.

No change in behavior.

libraries/liblmdb/mdb.c

@@ -1298,6 +1298,10 @@ struct MDB_cursor {
 #define C_SUB	0x04			/**< Cursor is a sub-cursor */
 #define C_DEL	0x08			/**< last op was a cursor_del */
 #define C_UNTRACK	0x40		/**< Un-track cursor when closing */
+#define C_WRITEMAP	MDB_TXN_WRITEMAP /**< Copy of txn flag */
+/** Read-only cursor into the txn's original snapshot in the map.
+ */
+#define C_ORIG_RDONLY	MDB_TXN_RDONLY
 /** @} */
 	unsigned int	mc_flags;	/**< @ref mdb_cursor */
 	MDB_page	*mc_pg[CURSOR_STACK];	/**< stack of pushed pages */
@@ -5915,7 +5919,7 @@ mdb_page_get(MDB_cursor *mc, pgno_t pgno, MDB_page **ret, int *lvl)
 	MDB_page *p = NULL;
 	int level;
 
-	if (! (txn->mt_flags & (MDB_TXN_RDONLY|MDB_TXN_WRITEMAP))) {
+	if (! (mc->mc_flags & (C_ORIG_RDONLY|C_WRITEMAP))) {
 		MDB_txn *tx2 = txn;
 		level = 1;
 		do {
@@ -8038,7 +8042,7 @@ mdb_xcursor_init0(MDB_cursor *mc)
 	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_cursor.mc_flags = C_SUB | (mc->mc_flags & (C_ORIG_RDONLY|C_WRITEMAP));
 	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;
@@ -8057,12 +8061,12 @@ mdb_xcursor_init1(MDB_cursor *mc, MDB_node *node)
 {
 	MDB_xcursor *mx = mc->mc_xcursor;
 
+	mx->mx_cursor.mc_flags &= C_SUB|C_ORIG_RDONLY|C_WRITEMAP;
 	if (node->mn_flags & F_SUBDATA) {
 		memcpy(&mx->mx_db, NODEDATA(node), sizeof(MDB_db));
 		mx->mx_cursor.mc_pg[0] = 0;
 		mx->mx_cursor.mc_snum = 0;
 		mx->mx_cursor.mc_top = 0;
-		mx->mx_cursor.mc_flags = C_SUB;
 	} else {
 		MDB_page *fp = NODEDATA(node);
 		mx->mx_db.md_pad = 0;
@@ -8075,7 +8079,7 @@ mdb_xcursor_init1(MDB_cursor *mc, MDB_node *node)
 		COPY_PGNO(mx->mx_db.md_root, fp->mp_pgno);
 		mx->mx_cursor.mc_snum = 1;
 		mx->mx_cursor.mc_top = 0;
-		mx->mx_cursor.mc_flags = C_INITIALIZED|C_SUB;
+		mx->mx_cursor.mc_flags |= C_INITIALIZED;
 		mx->mx_cursor.mc_pg[0] = fp;
 		mx->mx_cursor.mc_ki[0] = 0;
 		if (mc->mc_db->md_flags & MDB_DUPFIXED) {
@@ -8141,7 +8145,7 @@ mdb_cursor_init(MDB_cursor *mc, MDB_txn *txn, MDB_dbi dbi, MDB_xcursor *mx)
 	mc->mc_top = 0;
 	mc->mc_pg[0] = 0;
 	mc->mc_ki[0] = 0;
-	mc->mc_flags = 0;
+	mc->mc_flags = txn->mt_flags & (C_ORIG_RDONLY|C_WRITEMAP);
 	if (txn->mt_dbs[dbi].md_flags & MDB_DUPSORT) {
 		mdb_tassert(txn, mx != NULL);
 		mc->mc_xcursor = mx;