try again at forcing file read while hashing

Backend/Hash.hs

@@ -5,7 +5,7 @@
  - Licensed under the GNU GPL version 3 or higher.
  -}
 
-{-# LANGUAGE CPP #-}
+{-# LANGUAGE CPP, BangPatterns #-}
 
 module Backend.Hash (
 	backends,
@@ -170,7 +170,12 @@ hashFile hash file filesize = go hash
 	go (SHA3Hash hashsize) = use (sha3Hasher hashsize)
 	go (SkeinHash hashsize) = use (skeinHasher hashsize)
 	
-	use hasher = liftIO $ hasher <$> L.readFile file
+	use hasher = liftIO $ do
+		hdl <- openBinaryFile file ReadMode
+		b <- L.hGetContents hdl
+		let !hsh = hasher b
+		hClose hdl
+		return hsh
 	
 	usehasher hashsize = case shaHasher hashsize filesize of
 		Left sha -> use sha