use locking on Windows

This is all the easy cases, where there was already a separate lock file.

Annex/LockPool.hs

@@ -1,6 +1,6 @@
 {- git-annex lock pool
  -
- - Copyright 2012 Joey Hess <joey@kitenet.net>
+ - Copyright 2012, 2014 Joey Hess <joey@kitenet.net>
  -
  - Licensed under the GNU GPL version 3 or higher.
  -}
@@ -9,13 +9,16 @@
 
 module Annex.LockPool where
 
-import qualified Data.Map as M
-import System.Posix.Types (Fd)
-
 import Common.Annex
 import Annex
+import Types.LockPool
+
+import qualified Data.Map as M
+
 #ifndef mingw32_HOST_OS
 import Annex.Perms
+#else
+import Utility.WinLock
 #endif
 
 {- Create a specified lock file, and takes a shared lock. -}
@@ -26,31 +29,32 @@ lockFile file = go =<< fromPool file
 	go Nothing = do
 #ifndef mingw32_HOST_OS
 		mode <- annexFileMode
-		fd <- liftIO $ noUmask mode $
+		lockhandle <- liftIO $ noUmask mode $
 			openFd file ReadOnly (Just mode) defaultFileFlags
-		liftIO $ waitToSetLock fd (ReadLock, AbsoluteSeek, 0, 0)
+		liftIO $ waitToSetLock lockhandle (ReadLock, AbsoluteSeek, 0, 0)
 #else
-		liftIO $ writeFile file ""
-		let fd = 0
+		lockhandle <- liftIO $ waitToLock $ lockShared file
 #endif
-		changePool $ M.insert file fd
+		changePool $ M.insert file lockhandle
 
 unlockFile :: FilePath -> Annex ()
 unlockFile file = maybe noop go =<< fromPool file
   where
-	go fd = do
+	go lockhandle = do
 #ifndef mingw32_HOST_OS
-		liftIO $ closeFd fd
+		liftIO $ closeFd lockhandle
+#else
+		liftIO $ dropLock lockhandle
 #endif
 		changePool $ M.delete file
 
-getPool :: Annex (M.Map FilePath Fd)
+getPool :: Annex LockPool
 getPool = getState lockpool
 
-fromPool :: FilePath -> Annex (Maybe Fd)
+fromPool :: FilePath -> Annex (Maybe LockHandle)
 fromPool file = M.lookup file <$> getPool
 
-changePool :: (M.Map FilePath Fd -> M.Map FilePath Fd) -> Annex ()
+changePool :: (LockPool -> LockPool) -> Annex ()
 changePool a = do
 	m <- getPool
 	changeState $ \s -> s { lockpool = a m }