generic SHA size support

Backend/SHA.hs

@@ -0,0 +1,71 @@
+{- git-annex SHA abstract backend
+ -
+ - Copyright 2011 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Backend.SHA (genBackend) where
+
+import Control.Monad.State
+import Data.String.Utils
+import System.Cmd.Utils
+import System.IO
+import System.Directory
+
+import qualified Backend.File
+import BackendTypes
+import Messages
+import qualified Annex
+import Locations
+import Content
+import Types
+import Utility
+
+type SHASize = Int
+
+-- Constructor for Backends using a given SHASize.
+genBackend :: SHASize -> Backend Annex
+genBackend size = Backend.File.backend 
+	{ name = shaName size
+	, getKey = keyValue size
+	, fsckKey = Backend.File.checkKey $ checkKeyChecksum size
+	}
+
+shaName :: SHASize -> String
+shaName size = "SHA" ++ show size
+
+shaN :: SHASize -> FilePath -> Annex String
+shaN size file = do
+	showNote "checksum..."
+	liftIO $ pOpen ReadFromPipe command (toCommand [File file]) $ \h -> do
+		line <- hGetLine h
+		let bits = split " " line
+		if null bits
+			then error $ command ++ " parse error"
+			else return $ head bits
+	where
+		command = "sha" ++ (show size) ++ "sum"
+
+-- A key is a checksum of its contents.
+keyValue :: SHASize -> FilePath -> Annex (Maybe Key)
+keyValue size file = do
+	s <- shaN size file	
+	return $ Just $ Key (shaName size, s)
+
+-- A key's checksum is checked during fsck.
+checkKeyChecksum :: SHASize -> Key -> Annex Bool
+checkKeyChecksum size key = do
+	g <- Annex.gitRepo
+	let file = gitAnnexLocation g key
+	present <- liftIO $ doesFileExist file
+	if not present
+		then return True
+		else do
+			s <- shaN size file
+			if s == keyName key
+				then return True
+				else do
+					dest <- moveBad key
+					warning $ "Bad file content; moved to " ++ filePathToString dest
+					return False

Backend/SHA1.hs

@@ -1,63 +1,14 @@
 {- git-annex "SHA1" backend
  -
- - Copyright 2010 Joey Hess <joey@kitenet.net>
+ - Copyright 2011 Joey Hess <joey@kitenet.net>
  -
  - Licensed under the GNU GPL version 3 or higher.
  -}
 
 module Backend.SHA1 (backend) where
 
-import Control.Monad.State
-import Data.String.Utils
-import System.Cmd.Utils
-import System.IO
-import System.Directory
-
-import qualified Backend.File
-import BackendTypes
-import Messages
-import qualified Annex
-import Locations
-import Content
 import Types
-import Utility
+import Backend.SHA
 
 backend :: Backend Annex
-backend = Backend.File.backend {
-	name = "SHA1",
-	getKey = keyValue,
-	fsckKey = Backend.File.checkKey checkKeySHA1
-}
-
-sha1 :: FilePath -> Annex String
-sha1 file = do
-	showNote "checksum..."
-	liftIO $ pOpen ReadFromPipe "sha1sum" (toCommand [File file]) $ \h -> do
-		line <- hGetLine h
-		let bits = split " " line
-		if null bits
-			then error "sha1sum parse error"
-			else return $ head bits
-
--- A key is a sha1 of its contents.
-keyValue :: FilePath -> Annex (Maybe Key)
-keyValue file = do
-	s <- sha1 file	
-	return $ Just  $ Key (name backend, s)
-
--- A key's sha1 is checked during fsck.
-checkKeySHA1 :: Key -> Annex Bool
-checkKeySHA1 key = do
-	g <- Annex.gitRepo
-	let file = gitAnnexLocation g key
-	present <- liftIO $ doesFileExist file
-	if not present
-		then return True
-		else do
-			s <- sha1 file
-			if s == keyName key
-				then return True
-				else do
-					dest <- moveBad key
-					warning $ "Bad file content; moved to " ++ filePathToString dest
-					return False
+backend = genBackend 1