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[helm.git] / components / extlib / hMarshal.ml

diff --git a/components/extlib/hMarshal.ml b/components/extlib/hMarshal.ml
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+(* Copyright (C) 2005, HELM Team.
+ * 
+ * This file is part of HELM, an Hypertextual, Electronic
+ * Library of Mathematics, developed at the Computer Science
+ * Department, University of Bologna, Italy.
+ * 
+ * HELM is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ * 
+ * HELM is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with HELM; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+ * MA  02111-1307, USA.
+ * 
+ * For details, see the HELM World-Wide-Web page,
+ * http://helm.cs.unibo.it/
+ *)
+
+(* $Id$ *)
+
+exception Corrupt_file of string
+exception Format_mismatch of string
+exception Version_mismatch of string
+
+let ensure_path_exists fname = HExtlib.mkdir (Filename.dirname fname)
+let marshal_flags = []
+
+let save ~fmt ~version ~fname data =
+  ensure_path_exists fname;
+  let oc = open_out fname in
+  let marshalled = Marshal.to_string data marshal_flags in
+  output_binary_int oc (Hashtbl.hash fmt);        (* field 1 *)
+  output_binary_int oc version;                   (* field 2 *)
+  output_string oc fmt;                           (* field 3 *)
+  output_string oc (string_of_int version);       (* field 4 *)
+  output_binary_int oc (Hashtbl.hash marshalled); (* field 5 *)
+  output_string oc marshalled;                    (* field 6 *)
+  close_out oc;
+  HExtlib.chmod 0o664 fname
+
+let expect ic fname s =
+  let len = String.length s in
+  let buf = String.create len in
+  really_input ic buf 0 len;
+  if buf <> s then raise (Corrupt_file fname)
+
+let load ~fmt ~version ~fname =
+  let ic = open_in fname in
+  HExtlib.finally
+    (fun () -> close_in ic)
+    (fun () ->
+      try
+        let fmt' = input_binary_int ic in         (* field 1 *)
+        if fmt' <> Hashtbl.hash fmt then raise (Format_mismatch fname);
+        let version' = input_binary_int ic in     (* field 2 *)
+        if version' <> version then raise (Version_mismatch fname);
+        expect ic fname fmt;                      (* field 3 *)
+        expect ic fname (string_of_int version);  (* field 4 *)
+        let checksum' = input_binary_int ic in    (* field 5 *)
+        let marshalled' = HExtlib.input_all ic in (* field 6 *)
+        if checksum' <> Hashtbl.hash marshalled' then
+          raise (Corrupt_file fname);
+        Marshal.from_string marshalled' 0
+      with End_of_file -> raise (Corrupt_file fname))
+    ()
+