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.

Command/Fsck.hs

@@ -13,9 +13,10 @@ import Command
 import Types
 import Core
 import Messages
+import qualified Command.FsckFile
 
 seek :: [SubCmdSeek]
-seek = [withNothing start]
+seek = [withNothing start, withAll withFilesInGit Command.FsckFile.start]
 
 {- Checks the whole annex for problems. -}
 start :: SubCmdStart
@@ -26,11 +27,9 @@ start = do
 perform :: SubCmdPerform
 perform = do
 	ok <- checkUnused
-	if (ok)
+	if ok
 		then return $ Just $ return True
-		else do
-			showLongNote "Possible problems detected."
-			return Nothing
+		else return Nothing
 
 checkUnused :: Annex Bool
 checkUnused = do

Command/FsckFile.hs

@@ -0,0 +1,33 @@
+{- git-annex command
+ -
+ - Copyright 2010 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Command.FsckFile where
+
+import Command
+import qualified Backend
+import Types
+import Messages
+
+seek :: [SubCmdSeek]
+seek = [withFilesInGit start]
+
+{- Checks a file's backend data for problems. -}
+start :: SubCmdStartString
+start file = isAnnexed file $ \(key, backend) -> do
+	inbackend <- Backend.hasKey key
+	if (not inbackend)
+		then return Nothing
+		else do
+			showStart "fsck" file
+			return $ Just $ perform key backend
+
+perform :: Key -> Backend -> SubCmdPerform
+perform key backend = do
+	success <- Backend.fsckKey backend key
+	if (success)
+		then return $ Just $ return True
+		else return Nothing