fsck improvements

* fsck: Check if annex.numcopies is satisfied.
* fsck: Verify the sha1 of files when the SHA1 backend is used.
* fsck: Verify the size of files when the WORM backend is used.
* fsck: Allow specifying individual files to fsk if fscking everything
  is not desired.
* fsck: Fix bug, introduced in 0.04, in detection of unused data.

Backend/WORM.hs

@@ -10,14 +10,22 @@ module Backend.WORM (backend) where
 import Control.Monad.State
 import System.FilePath
 import System.Posix.Files
+import System.Posix.Types
+import System.Directory
+import Data.String.Utils
 
 import qualified Backend.File
 import TypeInternals
+import Locations
+import qualified Annex
+import Core
+import Messages
 
 backend :: Backend
 backend = Backend.File.backend {
 	name = "WORM",
-	getKey = keyValue
+	getKey = keyValue,
+	fsckKey = Backend.File.checkKey checkKeySize
 }
 
 -- The key is formed from the file size, modification time, and the
@@ -36,3 +44,27 @@ keyValue file = do
 			(show $ fileSize stat)
 		base = takeFileName file
 		sep = ":"
+
+{- Extracts the file size from a key. -}
+keySize :: Key -> FileOffset
+keySize key = read $ section !! 2
+	where
+		section = split ":" (keyName key)
+
+{- The size of the data for a key is checked against the size encoded in
+ - the key. Note that the modification time is not checked. -}
+checkKeySize :: Key -> Annex Bool
+checkKeySize key = do
+	g <- Annex.gitRepo
+	let file = annexLocation g key
+	present <- liftIO $ doesFileExist file
+	if (not present)
+		then return True
+		else do
+			s <- liftIO $ getFileStatus file
+			if (fileSize s == keySize key)
+				then return True
+				else do
+					dest <- moveBad key
+					showNote $ "bad file size (moved to "++dest++")"
+					return False