+let magic_string = "SXSI_INDEX"
+let version_string = "1"
+
+let pos fd =
+ Unix.lseek fd 0 Unix.SEEK_CUR
+
+let pr_pos fd = Printf.eprintf "At position %i\n%!" (pos fd)
+
+let write fd s =
+ let sl = String.length s in
+ let ssl = Printf.sprintf "%020i" sl in
+ ignore (Unix.write fd ssl 0 20);
+ ignore (Unix.write fd s 0 (String.length s))
+
+let rec really_read fd buffer start length =
+ if length <= 0 then () else
+ match Unix.read fd buffer start length with
+ 0 -> raise End_of_file
+ | r -> really_read fd buffer (start + r) (length - r);;
+
+let read fd =
+ let buffer = String.create 20 in
+ let _ = really_read fd buffer 0 20 in
+ let size = int_of_string buffer in
+ let buffer = String.create size in
+ let _ = really_read fd buffer 0 size in
+ buffer
+
+
+let save t str =
+ let fd = Unix.openfile str [ Unix.O_WRONLY;Unix.O_TRUNC;Unix.O_CREAT] 0o644 in
+ let out_c = Unix.out_channel_of_descr fd in
+ let _ = set_binary_mode_out out_c true in
+ output_string out_c magic_string;
+ output_char out_c '\n';
+ output_string out_c version_string;
+ output_char out_c '\n';
+ Marshal.to_channel out_c t.ttable [ ];
+ (* we need to move the fd to the correct position *)
+ flush out_c;
+ ignore (Unix.lseek fd (pos_out out_c) Unix.SEEK_SET);
+ tree_save t.doc fd;
+ close_out out_c