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author | 2013-10-23 12:58:01 -0400 | |
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committer | 2013-10-23 13:00:45 -0400 | |
commit | b77b0848ee28093b63e3ab0d1ea494e430ffe58b (patch) | |
tree | 7bcc235a07319bb4461373b5d0656ddc90aad357 /Git/Repair.hs | |
parent | fb2ccfd60ff09c1b1d03838d42eba3c65fd7fb27 (diff) |
repair command: add handling of git-annex branch and index
Diffstat (limited to 'Git/Repair.hs')
-rw-r--r-- | Git/Repair.hs | 484 |
1 files changed, 484 insertions, 0 deletions
diff --git a/Git/Repair.hs b/Git/Repair.hs new file mode 100644 index 000000000..bb540fbd7 --- /dev/null +++ b/Git/Repair.hs @@ -0,0 +1,484 @@ +{- git repository recovery + - + - Copyright 2013 Joey Hess <joey@kitenet.net> + - + - Licensed under the GNU GPL version 3 or higher. + -} + +module Git.Repair ( + runRepair, + cleanCorruptObjects, + retrieveMissingObjects, + resetLocalBranches, + removeTrackingBranches, + rewriteIndex, + checkIndex, + emptyGoodCommits, +) where + +import Common +import Git +import Git.Command +import Git.Objects +import Git.Sha +import Git.Types +import Git.Fsck +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 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, removes all + - corrupt objects, and returns a list of missing objects, + - which need to be found elsewhere to finish recovery. + - + - Since git fsck may crash on corrupt objects, and so not + - report the full set of corrupt or missing objects, + - this removes corrupt objects, and re-runs fsck, until it + - stabalizes. + - + - To remove corrupt objects, unpack all packs, and remove the packs + - (to handle corrupt packs), and remove loose object files. + -} +cleanCorruptObjects :: FsckResults -> Repo -> IO MissingObjects +cleanCorruptObjects mmissing r = check mmissing + where + check Nothing = do + putStrLn "git fsck found a problem but no specific broken objects. Perhaps a corrupt pack file?" + ifM (explodePacks r) + ( retry S.empty + , return S.empty + ) + check (Just bad) + | S.null bad = return S.empty + | otherwise = do + putStrLn $ unwords + [ "git fsck found" + , show (S.size bad) + , "broken objects." + ] + exploded <- explodePacks r + removed <- removeLoose r bad + if exploded || removed + then retry bad + else return bad + retry oldbad = do + putStrLn "Re-running git fsck to see if it finds more problems." + v <- findBroken False r + case v of + Nothing -> error $ unwords + [ "git fsck found a problem, which was not corrected after removing" + , show (S.size oldbad) + , "corrupt objects." + ] + Just newbad -> do + removed <- removeLoose r newbad + let s = S.union oldbad newbad + if not removed || s == oldbad + then return s + else retry s + +removeLoose :: Repo -> MissingObjects -> IO Bool +removeLoose r s = do + let fs = map (looseObjectFile r) (S.toList s) + count <- length <$> filterM doesFileExist fs + if (count > 0) + then do + putStrLn $ unwords + [ "removing" + , show count + , "corrupt loose objects" + ] + mapM_ nukeFile fs + return True + else return False + +explodePacks :: Repo -> IO Bool +explodePacks r = do + packs <- listPackFiles r + if null packs + then return False + else do + putStrLn "Unpacking all pack files." + mapM_ go packs + return True + where + go packfile = do + -- May fail, if pack file is corrupt. + void $ tryIO $ + pipeWrite [Param "unpack-objects"] r $ \h -> + L.hPut h =<< L.readFile packfile + nukeFile packfile + nukeFile $ packIdxFile packfile + +{- Try to retrieve a set of missing objects, from the remotes of a + - repository. Returns any that could not be retreived. + -} +retrieveMissingObjects :: MissingObjects -> Repo -> IO MissingObjects +retrieveMissingObjects missing r + | S.null 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 stillmissing + then return stillmissing + else pullremotes tmpr (remotes r) fetchallrefs stillmissing + where + pullremotes _tmpr [] _ stillmissing = return stillmissing + pullremotes tmpr (rmt:rmts) fetchrefs s + | S.null s = return s + | otherwise = do + putStrLn $ "Trying to recover missing objects from remote " ++ repoDescribe rmt + ifM (fetchsome rmt fetchrefs tmpr) + ( do + void $ copyObjects tmpr r + stillmissing <- findMissing (S.toList s) r + pullremotes tmpr rmts fetchrefs stillmissing + , do + putStrLn $ unwords + [ "failed to fetch from remote" + , repoDescribe rmt + , "(will continue without it, but making this remote available may improve recovery)" + ] + pullremotes tmpr rmts fetchrefs s + ) + fetchsome rmt ps = runBool $ + [ Param "fetch" + , Param (repoLocation rmt) + , Params "--force --update-head-ok --quiet" + ] ++ ps + -- 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 object, 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` show 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 (show $ Ref.base b) + , Param (show c) + ] r + +{- To deal with missing objects that cannot be recovered, removes + - any remote tracking branches that reference them. Returns a list of + - all removed branches. + -} +removeTrackingBranches :: MissingObjects -> GoodCommits -> Repo -> IO ([Branch], GoodCommits) +removeTrackingBranches missing goodcommits r = + go [] goodcommits =<< filter istrackingbranch <$> getAllRefs r + where + istrackingbranch b = "refs/remotes/" `isPrefixOf` show b + go removed gcs [] = return (removed, gcs) + go removed gcs (b:bs) = do + (ok, gcs') <- verifyCommit missing gcs b r + if ok + then go removed gcs' bs + else do + nukeBranchRef b r + go (b:removed) gcs' bs + +{- Gets all refs, including ones that are corrupt. + - git show-ref does not output refs to commits that are directly + - corrupted, so it is not used. + -} +getAllRefs :: Repo -> IO [Ref] +getAllRefs r = do + packedrs <- mapMaybe parsePacked . lines + <$> catchDefaultIO "" (readFile $ packedRefsFile r) + loosers <- map toref <$> dirContentsRecursive refdir + return $ packedrs ++ loosers + where + refdir = localGitDir r </> "refs" + toref = Ref . relPathDirToFile (localGitDir r) + +packedRefsFile :: Repo -> FilePath +packedRefsFile r = localGitDir r </> "packed-refs" + +parsePacked :: String -> Maybe Ref +parsePacked l = case words l of + (sha:ref:[]) + | isJust (extractSha sha) -> Just $ Ref ref + _ -> Nothing + +{- git-branch -d cannot be used to remove a branch that is directly + - pointing to a corrupt commit. However, it's tried first. -} +nukeBranchRef :: Branch -> Repo -> IO () +nukeBranchRef b r = void $ usegit <||> byhand + where + usegit = runBool + [ Param "branch" + , Params "-r -d" + , Param $ show $ Ref.base b + ] r + byhand = do + nukeFile $ localGitDir r </> show b + whenM (doesFileExist packedrefs) $ + withTmpFile "packed-refs" $ \tmp h -> do + ls <- lines <$> readFile packedrefs + hPutStr h $ unlines $ + filter (not . skiprefline) ls + hClose h + renameFile tmp packedrefs + return True + skiprefline l = case parsePacked l of + Just packedref + | packedref == b -> True + _ -> False + packedrefs = packedRefsFile r + +{- 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 (show 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 tha 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 (show 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. -} +checkIndex :: MissingObjects -> Repo -> IO Bool +checkIndex missing r = do + (bad, _good, cleanup) <- partitionIndex missing r + if null bad + then cleanup + else do + void cleanup + return False + +partitionIndex :: MissingObjects -> Repo -> IO ([LsFiles.StagedDetails], [LsFiles.StagedDetails], IO Bool) +partitionIndex missing r = do + (indexcontents, cleanup) <- LsFiles.stagedDetails [repoPath r] r + let (bad, good) = partition ismissing indexcontents + return (bad, good, cleanup) + where + getblob (_file, Just sha, Just _mode) = Just sha + getblob _ = Nothing + ismissing = maybe False (`S.member` missing) . getblob + +{- Rewrites the index file, removing from it any files whose blobs are + - missing. Returns the list of affected files. -} +rewriteIndex :: MissingObjects -> Repo -> IO [FilePath] +rewriteIndex missing r + | repoIsLocalBare r = return [] + | otherwise = do + (bad, good, cleanup) <- partitionIndex missing r + unless (null bad) $ do + nukeFile (localGitDir r </> "index") + 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 + +{- Put it all together. -} +runRepair :: Bool -> Repo -> IO (Bool, MissingObjects) +runRepair forced g = do + putStrLn "Running git fsck ..." + fsckresult <- findBroken False g + missing <- cleanCorruptObjects fsckresult g + stillmissing <- retrieveMissingObjects missing g + if S.null stillmissing + then successfulfinish stillmissing + else do + putStrLn $ unwords + [ show (S.size stillmissing) + , "missing objects could not be recovered!" + ] + if forced + then do + (remotebranches, goodcommits) <- removeTrackingBranches stillmissing emptyGoodCommits g + unless (null remotebranches) $ + putStrLn $ unwords + [ "removed" + , show (length remotebranches) + , "remote tracking branches that referred to missing objects" + ] + (resetbranches, deletedbranches, _) <- resetLocalBranches stillmissing goodcommits g + displayList (map show resetbranches) + "Reset these local branches to old versions before the missing objects were committed:" + displayList (map show deletedbranches) + "Deleted these local branches, which could not be recovered due to missing objects:" + deindexedfiles <- rewriteIndex stillmissing 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." + if null resetbranches && null deletedbranches + then successfulfinish stillmissing + else do + unless (repoIsLocalBare g) $ do + mcurr <- Branch.currentUnsafe g + case mcurr of + Nothing -> return () + Just curr -> when (any (== curr) (resetbranches ++ deletedbranches)) $ do + putStrLn $ unwords + [ "You currently have" + , show 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, stillmissing) + else 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 re-run git-recover-repository." + putStrLn "If there are no clones of this repository, you can instead run git-recover-repository with the --force parameter to force recovery to a possibly usable state." + else putStrLn "To force a recovery to a usable state, run this command again with the --force parameter." + return (False, stillmissing) + where + successfulfinish stillmissing = do + mapM_ putStrLn + [ "Successfully recovered repository!" + , "You should run \"git fsck\" to make sure, but it looks like" + , "everything was recovered ok." + ] + return (True, stillmissing) |