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+{- git fsck interface
+ -
+ - Copyright 2013 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Git.Fsck (
+ FsckResults,
+ MissingObjects,
+ findBroken,
+ foundBroken,
+ findMissing,
+) where
+
+import Common
+import Git
+import Git.Command
+import Git.Sha
+import Utility.Batch
+
+import qualified Data.Set as S
+
+type MissingObjects = S.Set Sha
+
+{- If fsck succeeded, Just a set of missing objects it found.
+ - If it failed, Nothing. -}
+type FsckResults = Maybe MissingObjects
+
+{- Runs fsck to find some of the broken objects in the repository.
+ - May not find all broken objects, if fsck fails on bad data in some of
+ - the broken objects it does find.
+ -
+ - Strategy: Rather than parsing fsck's current specific output,
+ - look for anything in its output (both stdout and stderr) that appears
+ - to be a git sha. Not all such shas are of broken objects, so ask git
+ - to try to cat the object, and see if it fails.
+ -}
+findBroken :: Bool -> Repo -> IO FsckResults
+findBroken batchmode r = do
+ (output, fsckok) <- processTranscript command' (toCommand params') Nothing
+ let objs = findShas output
+ badobjs <- findMissing objs r
+ if S.null badobjs && not fsckok
+ then return Nothing
+ else return $ Just badobjs
+ where
+ (command, params) = ("git", fsckParams r)
+ (command', params')
+ | batchmode = toBatchCommand (command, params)
+ | otherwise = (command, params)
+
+foundBroken :: FsckResults -> Bool
+foundBroken Nothing = True
+foundBroken (Just s) = not (S.null s)
+
+{- Finds objects that are missing from the git repsitory, or are corrupt.
+ -
+ - This does not use git cat-file --batch, because catting a corrupt
+ - object can cause it to crash, or to report incorrect size information.a
+ -}
+findMissing :: [Sha] -> Repo -> IO MissingObjects
+findMissing objs r = S.fromList <$> filterM (not <$$> present) objs
+ where
+ present o = either (const False) (const True) <$> tryIO (dump o)
+ dump o = runQuiet
+ [ Param "show"
+ , Param (show o)
+ ] r
+
+findShas :: String -> [Sha]
+findShas = catMaybes . map extractSha . concat . map words . lines
+
+fsckParams :: Repo -> [CommandParam]
+fsckParams = gitCommandLine $
+ [ Param "fsck"
+ , Param "--no-dangling"
+ , Param "--no-reflogs"
+ ]