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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 (
scanRecursive,
addSubDir,
removeSubDir,
waitChange,
) 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
data Kqueue = Kqueue Fd DirMap
{- Builds a map of directories in a tree, possibly pruning some.
- Opens each directory in the tree. -}
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
{- Adds a subdirectory (and all its subdirectories, unless pruned) to a
- directory map. -}
addSubDir :: DirMap -> FilePath -> (FilePath -> Bool) -> IO DirMap
addSubDir dirmap dir prune = M.union dirmap <$> scanRecursive dir prune
{- Removes a subdirectory (and all its subdirectories) from a directory map. -}
removeSubDir :: FilePath -> DirMap -> DirMap
removeSubDir dir = M.filter (not . dirContains dir)
foreign import ccall unsafe "libkqueue.h init_kqueue" c_init_kqueue
:: CInt -> Ptr Fd -> IO Fd
foreign import ccall unsafe "libkqueue.h waitchange_kqueue" c_waitchange_kqueue
:: Fd -> IO Fd
{- Initializes a Kqueue to watch a map of directories. -}
initKqueue :: DirMap -> IO Kqueue
initKqueue dirmap = withArrayLen (M.keys dirmap) $ \fdcnt c_fds ->
h <- c_init_kqueue (fromIntegral fdcnt) c_fds
return $ Kqueue h dirmap
{- Stops a Kqueue. Note: Does not directly close the Fds in the dirmap,
- so it can be reused. -}
stopKqueue :: Kqueue -> IO
stopKqueue (Kqueue h _) = closeFd h
{- Waits for a change on a Kqueue, and returns the directory
- or directories where a change took place.
-
- The kqueue interface does not tell what type of change took place in
- the directory; it could be an added file, a deleted file, a renamed
- file, a new subdirectory, or a deleted subdirectory, or a moved
- subdirectory.
-
- Note that if subdirectories have changed, the caller should re-run
- initKqueue to get them watched. -}
waitChange :: Kqueue -> IO [FilePath]
waitChange (Kqueue h dirmap) = do
changed <- c_waitchange_kqueue h
return $ M.lookup changed dirmap
|
