1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
|
{- 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
{- 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 waitchange" c_waitchange
:: Ptr Fd -> IO Fd
{- Waits for a change in a map of directories, and returns the directory
- where the 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 will want to
- update the map before calling this again. -}
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
|
