ITS#8321 deinit empty cursors

Always unset C_INIT flag if the cursor's target DB has been deleted

Author: hyc

libraries/liblmdb/mdb.c

@@ -5163,8 +5163,11 @@ mdb_cursor_pop(MDB_cursor *mc)
 			mc->mc_pg[mc->mc_top]->mp_pgno, DDBI(mc), (void *) mc));
 
 		mc->mc_snum--;
-		if (mc->mc_snum)
+		if (mc->mc_snum) {
 			mc->mc_top--;
+		} else {
+			mc->mc_flags &= ~C_INITIALIZED;
+		}
 	}
 }
 
@@ -6820,6 +6823,7 @@ mdb_cursor_del(MDB_cursor *mc, unsigned int flags)
 		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;
+			mc->mc_xcursor->mx_cursor.mc_flags &= ~C_INITIALIZED;
 		} else {
 			if (!F_ISSET(leaf->mn_flags, F_SUBDATA)) {
 				mc->mc_xcursor->mx_cursor.mc_pg[0] = NODEDATA(leaf);
@@ -6857,6 +6861,8 @@ mdb_cursor_del(MDB_cursor *mc, unsigned int flags)
 				mc->mc_db->md_entries--;
 				mc->mc_flags |= C_DEL;
 				return rc;
+			} else {
+				mc->mc_xcursor->mx_cursor.mc_flags &= ~C_INITIALIZED;
 			}
 			/* otherwise fall thru and delete the sub-DB */
 		}
@@ -9646,6 +9652,7 @@ mdb_drop0(MDB_cursor *mc, int subs)
 	} else if (rc == MDB_NOTFOUND) {
 		rc = MDB_SUCCESS;
 	}
+	mc->mc_flags &= ~C_INITIALIZED;
 	return rc;
 }