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{- BSD kqueue file modification notification interface
-
- Copyright 2012 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
{-# LANGUAGE ForeignFunctionInterface #-}
module Utility.Kqueue (
waitChange,
scanRecursive
) where
import Common
import System.Posix.Types
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 :: DirMap -> IO (Maybe FilePath)
waitChange dirmap = withArray (M.keys dirmap) $ \c_fds -> do
changed <- c_waitchange c_fds
ifM (safeErrno <$> getErrno)
( 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
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