git-repair (1.20131122) unstable; urgency=low

  * Added test mode, which can be used to randomly corrupt test
    repositories, in reproducible ways, which allows easy
    corruption-driven-development.
  * Improve repair code in the case where the index file is corrupt,
    and this hides other problems.
  * Write a dummy .git/HEAD if the file is missing or corrupt, as
    git otherwise will not treat the repository as a git repo.
  * Improve fsck code to find badly corrupted objects that crash git fsck
    before it can complain about them.
  * Fixed crashes on bad file encodings.
  * Can now run 10000 tests (git-repair --test -n 10000 --force)
    with 0 failures.

# imported from the archive

1 files changed, 79 insertions, 0 deletions

diff --git a/Git/Fsck.hs b/Git/Fsck.hs
new file mode 100644
index 0000000..8bfddb4
--- /dev/null
+++ b/Git/Fsck.hs
@@ -0,0 +1,79 @@
+{- 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"
+	]