more lock file refactoring

Annex/Content.hs

@@ -101,18 +101,16 @@ inAnnexSafe key = inAnnex' (fromMaybe False) (Just False) go key
 		=<< contentLockFile key
 
 #ifndef mingw32_HOST_OS
-	checkindirect f = liftIO $ openforlock f >>= check is_missing
+	checkindirect f = liftIO $ openExistingLockFile f >>= check is_missing
 	{- In direct mode, the content file must exist, but
 	 - the lock file often generally won't exist unless a removal is in
 	 - process. This does not create the lock file, it only checks for
 	 - it. -}
 	checkdirect contentfile lockfile = liftIO $
 		ifM (doesFileExist contentfile)
-			( openforlock lockfile >>= check is_unlocked
+			( openExistingLockFile lockfile >>= check is_unlocked
 			, return is_missing
 			)
-	openforlock f = catchMaybeIO $
-		openFd f ReadOnly Nothing defaultFileFlags
 	check _ (Just h) = do
 		v <- getLock h (ReadLock, AbsoluteSeek, 0, 0)
 		closeFd h
@@ -180,7 +178,7 @@ lockContent key a = do
 	opencontentforlock f = catchMaybeIO $ ifM (doesFileExist f)
 		( withModifiedFileMode f
 			(`unionFileModes` ownerWriteMode)
-			(createLockFie Nothing f)
+			(createLockFile Nothing f)
 		, createLockFile Nothing f
 		)
 	dolock Nothing = return Nothing

Logs/Transfer.hs

@@ -17,9 +17,7 @@ import Utility.Metered
 import Utility.Percentage
 import Utility.QuickCheck
 import Utility.PID
-#ifdef mingw32_HOST_OS
-import Utility.WinLock
-#endif
+import Utility.LockFile
 
 import Data.Time.Clock
 import Data.Time.Clock.POSIX
@@ -131,9 +129,7 @@ checkTransfer :: Transfer -> Annex (Maybe TransferInfo)
 checkTransfer t = do
 	tfile <- fromRepo $ transferFile t
 #ifndef mingw32_HOST_OS
-	mode <- annexFileMode
-	mfd <- liftIO $ catchMaybeIO $
-		openFd (transferLockFile tfile) ReadOnly (Just mode) defaultFileFlags
+	mfd <- liftIO $ openExistingLockFile (transferLockFile tfile)
 	case mfd of
 		Nothing -> return Nothing -- failed to open file; not running
 		Just fd -> do

Utility/LockFile/Posix.hs

@@ -6,13 +6,16 @@
  -}
 
 module Utility.LockFile.Posix (
+	LockHandle,
 	lockShared,
 	lockExclusive,
 	dropLock,
 	createLockFile,
-	LockHandle
+	openExistingLockFile,
 ) where
 
+import Utility.Exception
+
 import System.IO
 import System.Posix
 
@@ -35,11 +38,18 @@ lock lockreq mode lockfile = do
 	waitToSetLock l (lockreq, AbsoluteSeek, 0, 0)
 	return (LockHandle l)
 
--- Create and opens lock file, does not lock it.
--- Close on exec flag is set so child processes do not inherit the lock.
+-- Create and opens lock file; does not lock it.
 createLockFile :: Maybe FileMode -> LockFile -> IO Fd
-createLockFile mode lockfile = do
-	l <- openFd lockfile ReadWrite mode defaultFileFlags
+createLockFile = openLockFile ReadWrite
+
+-- Opens an existing lock file; does not lock it or create it.
+openExistingLockFile :: LockFile -> IO (Maybe Fd)
+openExistingLockFile = catchMaybeIO . openLockFile ReadOnly Nothing
+
+-- Close on exec flag is set so child processes do not inherit the lock.
+openLockFile :: OpenMode -> Maybe FileMode -> LockFile -> IO Fd
+openLockFile openmode filemode lockfile = do
+	l <- openFd lockfile openmode filemode defaultFileFlags
 	setFdOption l CloseOnExec True
 	return l