filemanip/System/FilePath/Manip.hs

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{-# OPTIONS_GHC -fglasgow-exts #-}
module System.FilePath.Manip (
Modifiable(..)
, renameWith
, modifyWith
, modifyWithBackup
, modifyInPlace
) where
import Control.Exception (bracket, bracket_, handle, throwIO)
import Control.Monad (liftM)
import Data.Bits ((.&.))
import System.Directory (removeFile)
import System.IO (Handle, IOMode(..), hClose, hGetContents, hPutStr, openFile)
import System.Posix.Files (fileMode, getFileStatus, rename, setFileMode)
import System.Posix.Temp (mkstemp)
import Data.ByteString.Base (ByteString, LazyByteString)
import qualified Data.ByteString.Char8 as B
import qualified Data.ByteString.Lazy.Char8 as L
renameWith :: (FilePath -> FilePath) -> FilePath -> IO ()
renameWith f path = rename path (f path)
class Modifiable a where
pipeline :: (a -> a) -> Handle -> Handle -> IO ()
instance Modifiable ByteString where
pipeline f ih oh = B.hGetContents ih >>= return . f >>= B.hPut oh
instance Modifiable LazyByteString where
pipeline f ih oh = L.hGetContents ih >>= return . f >>= L.hPut oh
instance Modifiable String where
pipeline f ih oh = hGetContents ih >>= return . f >>= hPutStr oh
modifyInPlace :: Modifiable a => (a -> a) -> FilePath -> IO ()
modifyInPlace = modifyWith (flip rename)
modifyWithBackup :: Modifiable a => (FilePath -> FilePath)
-> (a -> a)
-> FilePath
-> IO ()
modifyWithBackup f = modifyWith backup
where backup path tmpPath = renameWith f path >> rename tmpPath path
modifyWith :: Modifiable a => (FilePath -> FilePath -> IO ())
-> (a -> a)
-> FilePath
-> IO ()
modifyWith after transform path =
bracket (openFile path ReadMode) hClose $ \ih -> do
(tmpPath, oh) <- mkstemp (path ++ "XXXXXX")
let ignore = return ()
nukeTmp = handle (const ignore) (removeFile tmpPath)
handle (\e -> nukeTmp >> throwIO e) $ do
bracket_ ignore (hClose oh) $
pipeline transform ih oh
handle (const nukeTmp) $ do
mode <- fileMode `liftM` getFileStatus path
setFileMode tmpPath (mode .&. 0777)
after path tmpPath