recurse dirTree and open the directories for kqueue to watch

Utility/Kqueue.hs

@@ -7,7 +7,10 @@
 
 {-# LANGUAGE ForeignFunctionInterface #-}
 
-module Utility.Kqueue ( waitChange ) where
+module Utility.Kqueue (
+	waitChange,
+	scanRecursive
+) where
 
 import Common
 
@@ -16,16 +19,26 @@ import Foreign.C.Types
 import Foreign.C.Error
 import Foreign.Ptr
 import Foreign.Marshal
+import qualified Data.Map as M
+
+type DirMap = M.Map Fd FilePath
 
 foreign import ccall unsafe "libkqueue.h waitchange" c_waitchange
 	:: Ptr Fd -> IO Fd
 
-waitChange :: [Fd] -> IO (Maybe Fd)
-waitChange fds = withArray fds $ \c_fds -> do
-	ret <- c_waitchange c_fds
+waitChange :: DirMap -> IO (Maybe FilePath)
+waitChange dirmap = withArray (M.keys dirmap) $ \c_fds -> do
+	changed <- c_waitchange c_fds
 	ifM (safeErrno <$> getErrno)
-		( return $ Just ret
+		( return $ M.lookup changed dirmap
 		, return Nothing
 		)
 	where
 		safeErrno (Errno v) = v == 0
+
+scanRecursive :: FilePath -> (FilePath -> Bool) -> IO DirMap
+scanRecursive dir prune = M.fromList <$> (mapM opendir =<< dirTree dir prune)
+	where
+		opendir d = (,)
+			<$> openFd d ReadOnly Nothing defaultFileFlags
+			<*> pure d