git-annex/Git/Fsck.hs
2014-01-21 13:22:48 -04:00

94 lines
2.7 KiB
Haskell

{- 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,
isMissing,
knownMissing,
) where
import Common
import Git
import Git.Command
import Git.Sha
import Utility.Batch
import qualified Git.Version
import qualified Data.Set as S
type MissingObjects = S.Set Sha
data FsckResults = FsckFoundMissing MissingObjects | FsckFailed
deriving (Show)
{- 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
supportsNoDangling <- (>= Git.Version.normalize "1.7.10")
<$> Git.Version.installed
let (command, params) = ("git", fsckParams supportsNoDangling r)
(command', params') <- if batchmode
then toBatchCommand (command, params)
else return (command, params)
(output, fsckok) <- processTranscript command' (toCommand params') Nothing
let objs = findShas supportsNoDangling output
badobjs <- findMissing objs r
if S.null badobjs && not fsckok
then return FsckFailed
else return $ FsckFoundMissing badobjs
foundBroken :: FsckResults -> Bool
foundBroken FsckFailed = True
foundBroken (FsckFoundMissing s) = not (S.null s)
knownMissing :: FsckResults -> MissingObjects
knownMissing FsckFailed = S.empty
knownMissing (FsckFoundMissing s) = 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.
-}
findMissing :: [Sha] -> Repo -> IO MissingObjects
findMissing objs r = S.fromList <$> filterM (`isMissing` r) objs
isMissing :: Sha -> Repo -> IO Bool
isMissing s r = either (const True) (const False) <$> tryIO dump
where
dump = runQuiet
[ Param "show"
, Param (show s)
] r
findShas :: Bool -> String -> [Sha]
findShas supportsNoDangling = catMaybes . map extractSha . concat . map words . filter wanted . lines
where
wanted l
| supportsNoDangling = True
| otherwise = not ("dangling " `isPrefixOf` l)
fsckParams :: Bool -> Repo -> [CommandParam]
fsckParams supportsNoDangling = gitCommandLine $ map Param $ catMaybes
[ Just "fsck"
, if supportsNoDangling
then Just "--no-dangling"
else Nothing
, Just "--no-reflogs"
]