git-annex/Git/Repair.hs
Joey Hess 965e106f24 made parentDir return a Maybe FilePath; removed most uses of it
parentDir is less safe than takeDirectory, especially when working
with relative FilePaths. It's really only useful in loops that
want to terminate at /

This commit was sponsored by Audric SCHILTKNECHT.
2015-01-06 18:55:56 -04:00

612 lines
21 KiB
Haskell

{- git repository recovery
-
- Copyright 2013-2014 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Git.Repair (
runRepair,
runRepairOf,
removeBadBranches,
successfulRepair,
cleanCorruptObjects,
retrieveMissingObjects,
resetLocalBranches,
checkIndex,
checkIndexFast,
missingIndex,
emptyGoodCommits,
isTrackingBranch,
) where
import Common
import Git
import Git.Command
import Git.Objects
import Git.Sha
import Git.Types
import Git.Fsck
import Git.Index
import qualified Git.Config as Config
import qualified Git.Construct as Construct
import qualified Git.LsTree as LsTree
import qualified Git.LsFiles as LsFiles
import qualified Git.Ref as Ref
import qualified Git.RefLog as RefLog
import qualified Git.UpdateIndex as UpdateIndex
import qualified Git.Branch as Branch
import Utility.Tmp
import Utility.Rsync
import Utility.FileMode
import qualified Data.Set as S
import qualified Data.ByteString.Lazy as L
import Data.Tuple.Utils
{- Given a set of bad objects found by git fsck, which may not
- be complete, finds and removes all corrupt objects. -}
cleanCorruptObjects :: FsckResults -> Repo -> IO ()
cleanCorruptObjects fsckresults r = do
void $ explodePacks r
mapM_ removeLoose (S.toList $ knownMissing fsckresults)
mapM_ removeBad =<< listLooseObjectShas r
where
removeLoose s = nukeFile (looseObjectFile r s)
removeBad s = do
void $ tryIO $ allowRead $ looseObjectFile r s
whenM (isMissing s r) $
removeLoose s
{- Explodes all pack files, and deletes them.
-
- First moves all pack files to a temp dir, before unpacking them each in
- turn.
-
- This is because unpack-objects will not unpack a pack file if it's in the
- git repo.
-
- Also, this prevents unpack-objects from possibly looking at corrupt
- pack files to see if they contain an object, while unpacking a
- non-corrupt pack file.
-}
explodePacks :: Repo -> IO Bool
explodePacks r = go =<< listPackFiles r
where
go [] = return False
go packs = withTmpDir "packs" $ \tmpdir -> do
putStrLn "Unpacking all pack files."
forM_ packs $ \packfile -> do
moveFile packfile (tmpdir </> takeFileName packfile)
nukeFile $ packIdxFile packfile
forM_ packs $ \packfile -> do
let tmp = tmpdir </> takeFileName packfile
allowRead tmp
-- May fail, if pack file is corrupt.
void $ tryIO $
pipeWrite [Param "unpack-objects", Param "-r"] r $ \h ->
L.hPut h =<< L.readFile tmp
return True
{- Try to retrieve a set of missing objects, from the remotes of a
- repository. Returns any that could not be retreived.
-
- If another clone of the repository exists locally, which might not be a
- remote of the repo being repaired, its path can be passed as a reference
- repository.
-}
retrieveMissingObjects :: FsckResults -> Maybe FilePath -> Repo -> IO FsckResults
retrieveMissingObjects missing referencerepo r
| not (foundBroken missing) = return missing
| otherwise = withTmpDir "tmprepo" $ \tmpdir -> do
unlessM (boolSystem "git" [Params "init", File tmpdir]) $
error $ "failed to create temp repository in " ++ tmpdir
tmpr <- Config.read =<< Construct.fromAbsPath tmpdir
stillmissing <- pullremotes tmpr (remotes r) fetchrefstags missing
if S.null (knownMissing stillmissing)
then return stillmissing
else pullremotes tmpr (remotes r) fetchallrefs stillmissing
where
pullremotes tmpr [] fetchrefs stillmissing = case referencerepo of
Nothing -> return stillmissing
Just p -> ifM (fetchfrom p fetchrefs tmpr)
( do
void $ explodePacks tmpr
void $ copyObjects tmpr r
case stillmissing of
FsckFailed -> return $ FsckFailed
FsckFoundMissing s t -> FsckFoundMissing
<$> findMissing (S.toList s) r
<*> pure t
, return stillmissing
)
pullremotes tmpr (rmt:rmts) fetchrefs ms
| not (foundBroken ms) = return ms
| otherwise = do
putStrLn $ "Trying to recover missing objects from remote " ++ repoDescribe rmt ++ "."
ifM (fetchfrom (repoLocation rmt) fetchrefs tmpr)
( do
void $ explodePacks tmpr
void $ copyObjects tmpr r
case ms of
FsckFailed -> pullremotes tmpr rmts fetchrefs ms
FsckFoundMissing s t -> do
stillmissing <- findMissing (S.toList s) r
pullremotes tmpr rmts fetchrefs (FsckFoundMissing stillmissing t)
, pullremotes tmpr rmts fetchrefs ms
)
fetchfrom fetchurl ps fetchr = runBool ps' fetchr'
where
ps' =
[ Param "fetch"
, Param fetchurl
, Params "--force --update-head-ok --quiet"
] ++ ps
fetchr' = fetchr { gitGlobalOpts = gitGlobalOpts fetchr ++ nogc }
nogc = [ Param "-c", Param "gc.auto=0" ]
-- fetch refs and tags
fetchrefstags = [ Param "+refs/heads/*:refs/heads/*", Param "--tags"]
-- Fetch all available refs (more likely to fail,
-- as the remote may have refs it refuses to send).
fetchallrefs = [ Param "+*:*" ]
{- Copies all objects from the src repository to the dest repository.
- This is done using rsync, so it copies all missing objects, and all
- objects they rely on. -}
copyObjects :: Repo -> Repo -> IO Bool
copyObjects srcr destr = rsync
[ Param "-qr"
, File $ addTrailingPathSeparator $ objectsDir srcr
, File $ addTrailingPathSeparator $ objectsDir destr
]
{- To deal with missing objects that cannot be recovered, resets any
- local branches to point to an old commit before the missing
- objects. Returns all branches that were changed, and deleted.
-}
resetLocalBranches :: MissingObjects -> GoodCommits -> Repo -> IO ([Branch], [Branch], GoodCommits)
resetLocalBranches missing goodcommits r =
go [] [] goodcommits =<< filter islocalbranch <$> getAllRefs r
where
islocalbranch b = "refs/heads/" `isPrefixOf` fromRef b
go changed deleted gcs [] = return (changed, deleted, gcs)
go changed deleted gcs (b:bs) = do
(mc, gcs') <- findUncorruptedCommit missing gcs b r
case mc of
Just c
| c == b -> go changed deleted gcs' bs
| otherwise -> do
reset b c
go (b:changed) deleted gcs' bs
Nothing -> do
nukeBranchRef b r
go changed (b:deleted) gcs' bs
reset b c = do
nukeBranchRef b r
void $ runBool
[ Param "branch"
, Param (fromRef $ Ref.base b)
, Param (fromRef c)
] r
isTrackingBranch :: Ref -> Bool
isTrackingBranch b = "refs/remotes/" `isPrefixOf` fromRef b
{- To deal with missing objects that cannot be recovered, removes
- any branches (filtered by a predicate) that reference them
- Returns a list of all removed branches.
-}
removeBadBranches :: (Ref -> Bool) -> Repo -> IO [Branch]
removeBadBranches removablebranch r = fst <$> removeBadBranches' removablebranch S.empty emptyGoodCommits r
removeBadBranches' :: (Ref -> Bool) -> MissingObjects -> GoodCommits -> Repo -> IO ([Branch], GoodCommits)
removeBadBranches' removablebranch missing goodcommits r =
go [] goodcommits =<< filter removablebranch <$> getAllRefs r
where
go removed gcs [] = return (removed, gcs)
go removed gcs (b:bs) = do
(ok, gcs') <- verifyCommit missing gcs b r
if ok
then go removed gcs' bs
else do
nukeBranchRef b r
go (b:removed) gcs' bs
badBranches :: MissingObjects -> Repo -> IO [Branch]
badBranches missing r = filterM isbad =<< getAllRefs r
where
isbad b = not . fst <$> verifyCommit missing emptyGoodCommits b r
{- Gets all refs, including ones that are corrupt.
- git show-ref does not output refs to commits that are directly
- corrupted, so it is not used.
-
- Relies on packed refs being exploded before it's called.
-}
getAllRefs :: Repo -> IO [Ref]
getAllRefs r = map toref <$> dirContentsRecursive refdir
where
refdir = localGitDir r </> "refs"
toref = Ref . relPathDirToFile (localGitDir r)
explodePackedRefsFile :: Repo -> IO ()
explodePackedRefsFile r = do
let f = packedRefsFile r
whenM (doesFileExist f) $ do
rs <- mapMaybe parsePacked . lines
<$> catchDefaultIO "" (safeReadFile f)
forM_ rs makeref
nukeFile f
where
makeref (sha, ref) = do
let dest = localGitDir r </> fromRef ref
createDirectoryIfMissing True (takeDirectory dest)
unlessM (doesFileExist dest) $
writeFile dest (fromRef sha)
packedRefsFile :: Repo -> FilePath
packedRefsFile r = localGitDir r </> "packed-refs"
parsePacked :: String -> Maybe (Sha, Ref)
parsePacked l = case words l of
(sha:ref:[])
| isJust (extractSha sha) && Ref.legal True ref ->
Just (Ref sha, Ref ref)
_ -> Nothing
{- git-branch -d cannot be used to remove a branch that is directly
- pointing to a corrupt commit. -}
nukeBranchRef :: Branch -> Repo -> IO ()
nukeBranchRef b r = nukeFile $ localGitDir r </> fromRef b
{- Finds the most recent commit to a branch that does not need any
- of the missing objects. If the input branch is good as-is, returns it.
- Otherwise, tries to traverse the commits in the branch to find one
- that is ok. That might fail, if one of them is corrupt, or if an object
- at the root of the branch is missing. Finally, looks for an old version
- of the branch from the reflog.
-}
findUncorruptedCommit :: MissingObjects -> GoodCommits -> Branch -> Repo -> IO (Maybe Sha, GoodCommits)
findUncorruptedCommit missing goodcommits branch r = do
(ok, goodcommits') <- verifyCommit missing goodcommits branch r
if ok
then return (Just branch, goodcommits')
else do
(ls, cleanup) <- pipeNullSplit
[ Param "log"
, Param "-z"
, Param "--format=%H"
, Param (fromRef branch)
] r
let branchshas = catMaybes $ map extractSha ls
reflogshas <- RefLog.get branch r
-- XXX Could try a bit harder here, and look
-- for uncorrupted old commits in branches in the
-- reflog.
cleanup `after` findfirst goodcommits (branchshas ++ reflogshas)
where
findfirst gcs [] = return (Nothing, gcs)
findfirst gcs (c:cs) = do
(ok, gcs') <- verifyCommit missing gcs c r
if ok
then return (Just c, gcs')
else findfirst gcs' cs
{- Verifies that none of the missing objects in the set are used by
- the commit. Also adds to a set of commit shas that have been verified to
- be good, which can be passed into subsequent calls to avoid
- redundant work when eg, chasing down branches to find the first
- uncorrupted commit. -}
verifyCommit :: MissingObjects -> GoodCommits -> Sha -> Repo -> IO (Bool, GoodCommits)
verifyCommit missing goodcommits commit r
| checkGoodCommit commit goodcommits = return (True, goodcommits)
| otherwise = do
(ls, cleanup) <- pipeNullSplit
[ Param "log"
, Param "-z"
, Param "--format=%H %T"
, Param (fromRef commit)
] r
let committrees = map parse ls
if any isNothing committrees || null committrees
then do
void cleanup
return (False, goodcommits)
else do
let cts = catMaybes committrees
ifM (cleanup <&&> check cts)
( return (True, addGoodCommits (map fst cts) goodcommits)
, return (False, goodcommits)
)
where
parse l = case words l of
(commitsha:treesha:[]) -> (,)
<$> extractSha commitsha
<*> extractSha treesha
_ -> Nothing
check [] = return True
check ((c, t):rest)
| checkGoodCommit c goodcommits = return True
| otherwise = verifyTree missing t r <&&> check rest
{- Verifies that a tree is good, including all trees and blobs
- referenced by it. -}
verifyTree :: MissingObjects -> Sha -> Repo -> IO Bool
verifyTree missing treesha r
| S.member treesha missing = return False
| otherwise = do
(ls, cleanup) <- pipeNullSplit (LsTree.lsTreeParams treesha) r
let objshas = map (extractSha . LsTree.sha . LsTree.parseLsTree) ls
if any isNothing objshas || any (`S.member` missing) (catMaybes objshas)
then do
void cleanup
return False
-- as long as ls-tree succeeded, we're good
else cleanup
{- Checks that the index file only refers to objects that are not missing,
- and is not itself corrupt. Note that a missing index file is not
- considered a problem (repo may be new). -}
checkIndex :: Repo -> IO Bool
checkIndex r = do
(bad, _good, cleanup) <- partitionIndex r
if null bad
then cleanup
else do
void cleanup
return False
{- Does not check every object the index refers to, but only that the index
- itself is not corrupt. -}
checkIndexFast :: Repo -> IO Bool
checkIndexFast r = do
(indexcontents, cleanup) <- LsFiles.stagedDetails [repoPath r] r
length indexcontents `seq` cleanup
missingIndex :: Repo -> IO Bool
missingIndex r = not <$> doesFileExist (localGitDir r </> "index")
{- Finds missing and ok files staged in the index. -}
partitionIndex :: Repo -> IO ([LsFiles.StagedDetails], [LsFiles.StagedDetails], IO Bool)
partitionIndex r = do
(indexcontents, cleanup) <- LsFiles.stagedDetails [repoPath r] r
l <- forM indexcontents $ \i -> case i of
(_file, Just sha, Just _mode) -> (,) <$> isMissing sha r <*> pure i
_ -> pure (False, i)
let (bad, good) = partition fst l
return (map snd bad, map snd good, cleanup)
{- Rewrites the index file, removing from it any files whose blobs are
- missing. Returns the list of affected files. -}
rewriteIndex :: Repo -> IO [FilePath]
rewriteIndex r
| repoIsLocalBare r = return []
| otherwise = do
(bad, good, cleanup) <- partitionIndex r
unless (null bad) $ do
nukeFile (indexFile r)
UpdateIndex.streamUpdateIndex r
=<< (catMaybes <$> mapM reinject good)
void cleanup
return $ map fst3 bad
where
reinject (file, Just sha, Just mode) = case toBlobType mode of
Nothing -> return Nothing
Just blobtype -> Just <$>
UpdateIndex.stageFile sha blobtype file r
reinject _ = return Nothing
newtype GoodCommits = GoodCommits (S.Set Sha)
emptyGoodCommits :: GoodCommits
emptyGoodCommits = GoodCommits S.empty
checkGoodCommit :: Sha -> GoodCommits -> Bool
checkGoodCommit sha (GoodCommits s) = S.member sha s
addGoodCommits :: [Sha] -> GoodCommits -> GoodCommits
addGoodCommits shas (GoodCommits s) = GoodCommits $
S.union s (S.fromList shas)
displayList :: [String] -> String -> IO ()
displayList items header
| null items = return ()
| otherwise = do
putStrLn header
putStr $ unlines $ map (\i -> "\t" ++ i) truncateditems
where
numitems = length items
truncateditems
| numitems > 10 = take 10 items ++ ["(and " ++ show (numitems - 10) ++ " more)"]
| otherwise = items
{- Fix problems that would prevent repair from working at all
-
- A missing or corrupt .git/HEAD makes git not treat the repository as a
- git repo. If there is a git repo in a parent directory, it may move up
- the tree and use that one instead. So, cannot use `git show-ref HEAD` to
- test it.
-
- Explode the packed refs file, to simplify dealing with refs, and because
- fsck can complain about bad refs in it.
-}
preRepair :: Repo -> IO ()
preRepair g = do
unlessM (validhead <$> catchDefaultIO "" (safeReadFile headfile)) $ do
nukeFile headfile
writeFile headfile "ref: refs/heads/master"
explodePackedRefsFile g
unless (repoIsLocalBare g) $ do
let f = indexFile g
void $ tryIO $ allowWrite f
where
headfile = localGitDir g </> "HEAD"
validhead s = "ref: refs/" `isPrefixOf` s || isJust (extractSha s)
{- Put it all together. -}
runRepair :: (Ref -> Bool) -> Bool -> Repo -> IO (Bool, [Branch])
runRepair removablebranch forced g = do
preRepair g
putStrLn "Running git fsck ..."
fsckresult <- findBroken False g
if foundBroken fsckresult
then runRepair' removablebranch fsckresult forced Nothing g
else do
bad <- badBranches S.empty g
if null bad
then do
putStrLn "No problems found."
return (True, [])
else runRepair' removablebranch fsckresult forced Nothing g
runRepairOf :: FsckResults -> (Ref -> Bool) -> Bool -> Maybe FilePath -> Repo -> IO (Bool, [Branch])
runRepairOf fsckresult removablebranch forced referencerepo g = do
preRepair g
runRepair' removablebranch fsckresult forced referencerepo g
runRepair' :: (Ref -> Bool) -> FsckResults -> Bool -> Maybe FilePath -> Repo -> IO (Bool, [Branch])
runRepair' removablebranch fsckresult forced referencerepo g = do
cleanCorruptObjects fsckresult g
missing <- findBroken False g
stillmissing <- retrieveMissingObjects missing referencerepo g
case stillmissing of
FsckFoundMissing s t
| S.null s -> if repoIsLocalBare g
then checkbadbranches s
else ifM (checkIndex g)
( checkbadbranches s
, do
putStrLn "No missing objects found, but the index file is corrupt!"
if forced
then corruptedindex
else needforce
)
| otherwise -> if forced
then ifM (checkIndex g)
( forcerepair s t
, corruptedindex
)
else do
putStrLn $ unwords
[ show (S.size s)
, "missing objects could not be recovered!"
]
unsuccessfulfinish
FsckFailed
| forced -> ifM (pure (repoIsLocalBare g) <||> checkIndex g)
( do
cleanCorruptObjects FsckFailed g
stillmissing' <- findBroken False g
case stillmissing' of
FsckFailed -> return (False, [])
FsckFoundMissing s t -> forcerepair s t
, corruptedindex
)
| otherwise -> unsuccessfulfinish
where
repairbranches missing = do
(removedbranches, goodcommits) <- removeBadBranches' removablebranch missing emptyGoodCommits g
let remotebranches = filter isTrackingBranch removedbranches
unless (null remotebranches) $
putStrLn $ unwords
[ "Removed"
, show (length remotebranches)
, "remote tracking branches that referred to missing objects."
]
(resetbranches, deletedbranches, _) <- resetLocalBranches missing goodcommits g
displayList (map fromRef resetbranches)
"Reset these local branches to old versions before the missing objects were committed:"
displayList (map fromRef deletedbranches)
"Deleted these local branches, which could not be recovered due to missing objects:"
return (resetbranches ++ deletedbranches)
checkbadbranches missing = do
bad <- badBranches missing g
case (null bad, forced) of
(True, _) -> successfulfinish []
(False, False) -> do
displayList (map fromRef bad)
"Some git branches refer to missing objects:"
unsuccessfulfinish
(False, True) -> successfulfinish =<< repairbranches missing
forcerepair missing fscktruncated = do
modifiedbranches <- repairbranches missing
deindexedfiles <- rewriteIndex g
displayList deindexedfiles
"Removed these missing files from the index. You should look at what files are present in your working tree and git add them back to the index when appropriate."
-- When the fsck results were truncated, try
-- fscking again, and as long as different
-- missing objects are found, continue
-- the repair process.
if fscktruncated
then do
fsckresult' <- findBroken False g
case fsckresult' of
FsckFailed -> do
putStrLn "git fsck is failing"
return (False, modifiedbranches)
FsckFoundMissing s _
| S.null s -> successfulfinish modifiedbranches
| S.null (s `S.difference` missing) -> do
putStrLn $ unwords
[ show (S.size s)
, "missing objects could not be recovered!"
]
return (False, modifiedbranches)
| otherwise -> do
(ok, modifiedbranches') <- runRepairOf fsckresult' removablebranch forced referencerepo g
return (ok, modifiedbranches++modifiedbranches')
else successfulfinish modifiedbranches
corruptedindex = do
nukeFile (indexFile g)
-- The corrupted index can prevent fsck from finding other
-- problems, so re-run repair.
fsckresult' <- findBroken False g
result <- runRepairOf fsckresult' removablebranch forced referencerepo g
putStrLn "Removed the corrupted index file. You should look at what files are present in your working tree and git add them back to the index when appropriate."
return result
successfulfinish modifiedbranches
| null modifiedbranches = do
mapM_ putStrLn
[ "Successfully recovered repository!"
, "You should run \"git fsck\" to make sure, but it looks like everything was recovered ok."
]
return (True, modifiedbranches)
| otherwise = do
unless (repoIsLocalBare g) $ do
mcurr <- Branch.currentUnsafe g
case mcurr of
Nothing -> return ()
Just curr -> when (any (== curr) modifiedbranches) $ do
putStrLn $ unwords
[ "You currently have"
, fromRef curr
, "checked out. You may have staged changes in the index that can be committed to recover the lost state of this branch!"
]
putStrLn "Successfully recovered repository!"
putStrLn "Please carefully check that the changes mentioned above are ok.."
return (True, modifiedbranches)
unsuccessfulfinish = do
if repoIsLocalBare g
then do
putStrLn "If you have a clone of this bare repository, you should add it as a remote of this repository, and retry."
putStrLn "If there are no clones of this repository, you can instead retry with the --force parameter to force recovery to a possibly usable state."
return (False, [])
else needforce
needforce = do
putStrLn "To force a recovery to a usable state, retry with the --force parameter."
return (False, [])
successfulRepair :: (Bool, [Branch]) -> Bool
successfulRepair = fst
safeReadFile :: FilePath -> IO String
safeReadFile f = do
allowRead f
readFileStrictAnyEncoding f