From e81a7e4b7c8df2cae5670a9bcf3c90c2bd8fcfa7 Mon Sep 17 00:00:00 2001
From: j <0x006A@0x2620.org>
Date: Thu, 28 May 2009 19:00:30 +0200
Subject: [PATCH] add oshash

---
 oxlib/file.py | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/oxlib/file.py b/oxlib/file.py
index 0d34729..0396959 100644
--- a/oxlib/file.py
+++ b/oxlib/file.py
@@ -1,8 +1,12 @@
 # -*- coding: utf-8 -*-
 # vi:si:et:sw=4:sts=4:ts=4
 # GPL 2008
+from __future__ import division
 import os
 import hashlib
+import sys
+import struct 
+
 
 def sha1sum(filename):
     sha1 = hashlib.sha1()
@@ -14,4 +18,39 @@ def sha1sum(filename):
     file.close()
     return sha1.hexdigest()
 
+'''
+    os hash - http://trac.opensubtitles.org/projects/opensubtitles/wiki/HashSourceCodes
+'''
+def oshash(filename): 
+    try: 
+        longlongformat = 'q'  # long long 
+        bytesize = struct.calcsize(longlongformat) 
+            
+        f = open(filename, "rb") 
+            
+        filesize = os.path.getsize(filename) 
+        hash = filesize 
+            
+        if filesize < 65536: 
+           return "SizeError" 
+         
+        for x in range(int(65536/bytesize)): 
+            buffer = f.read(bytesize) 
+            (l_value,)= struct.unpack(longlongformat, buffer)  
+            hash += l_value 
+            hash = hash & 0xFFFFFFFFFFFFFFFF #to remain as 64bit number  
+                 
+
+        f.seek(max(0,filesize-65536),0) 
+        for x in range(int(65536/bytesize)): 
+            buffer = f.read(bytesize) 
+            (l_value,)= struct.unpack(longlongformat, buffer)  
+            hash += l_value 
+            hash = hash & 0xFFFFFFFFFFFFFFFF 
+         
+        f.close() 
+        returnedhash =  "%016x" % hash 
+        return returnedhash 
+    except(IOError): 
+        return "IOError"