assistant: Notice on startup when the index file is corrupt, and auto-repair.

Assistant/Threads/SanityChecker.hs

@@ -25,8 +25,10 @@ import Utility.Batch
 import Utility.NotificationBroadcaster
 import Config
 import Utility.HumanTime
+import Git.Repair
 
 import Data.Time.Clock.POSIX
+import qualified Data.Set as S
 
 {- This thread runs once at startup, and most other threads wait for it
  - to finish. (However, the webapp thread does not, to prevent the UI
@@ -36,6 +38,16 @@ sanityCheckerStartupThread startupdelay = namedThreadUnchecked "SanityCheckerSta
 	{- Stale git locks can prevent commits from happening, etc. -}
 	void $ repairStaleGitLocks =<< liftAnnex gitRepo
 
+	{- A corrupt index file can prevent the assistant from working at
+	 - all, so detect and repair. -}
+	unlessM (liftAnnex $ inRepo $ checkIndex S.empty) $ do
+		debug ["corrupt index found at startup; removing"]
+		liftAnnex $ inRepo nukeIndex
+		{- Normally the startup scan avoids re-staging files,
+		 - but with the index deleted, everything needs to be
+		 - restaged. -}
+		modifyDaemonStatus_ $ \s -> s { forceRestage = True }
+
 	{- If there's a startup delay, it's done here. -}
 	liftIO $ maybe noop (threadDelaySeconds . Seconds . fromIntegral . durationSeconds) startupdelay