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Diffstat (limited to 'Utility/Directory/Stream.hs')
-rw-r--r-- | Utility/Directory/Stream.hs | 113 |
1 files changed, 113 insertions, 0 deletions
diff --git a/Utility/Directory/Stream.hs b/Utility/Directory/Stream.hs new file mode 100644 index 000000000..ac62263a8 --- /dev/null +++ b/Utility/Directory/Stream.hs @@ -0,0 +1,113 @@ +{- streaming directory traversal + - + - Copyright 2011-2014 Joey Hess <id@joeyh.name> + - + - License: BSD-2-clause + -} + +{-# LANGUAGE CPP #-} +{-# OPTIONS_GHC -fno-warn-tabs #-} + +module Utility.Directory.Stream where + +import Control.Monad +import System.FilePath +import Control.Concurrent +import Data.Maybe +import Prelude + +#ifdef mingw32_HOST_OS +import qualified System.Win32 as Win32 +#else +import qualified System.Posix as Posix +#endif + +import Utility.Directory +import Utility.Exception + +#ifndef mingw32_HOST_OS +data DirectoryHandle = DirectoryHandle IsOpen Posix.DirStream +#else +data DirectoryHandle = DirectoryHandle IsOpen Win32.HANDLE Win32.FindData (MVar ()) +#endif + +type IsOpen = MVar () -- full when the handle is open + +openDirectory :: FilePath -> IO DirectoryHandle +openDirectory path = do +#ifndef mingw32_HOST_OS + dirp <- Posix.openDirStream path + isopen <- newMVar () + return (DirectoryHandle isopen dirp) +#else + (h, fdat) <- Win32.findFirstFile (path </> "*") + -- Indicate that the fdat contains a filename that readDirectory + -- has not yet returned, by making the MVar be full. + -- (There's always at least a "." entry.) + alreadyhave <- newMVar () + isopen <- newMVar () + return (DirectoryHandle isopen h fdat alreadyhave) +#endif + +closeDirectory :: DirectoryHandle -> IO () +#ifndef mingw32_HOST_OS +closeDirectory (DirectoryHandle isopen dirp) = + whenOpen isopen $ + Posix.closeDirStream dirp +#else +closeDirectory (DirectoryHandle isopen h _ alreadyhave) = + whenOpen isopen $ do + _ <- tryTakeMVar alreadyhave + Win32.findClose h +#endif + where + whenOpen :: IsOpen -> IO () -> IO () + whenOpen mv f = do + v <- tryTakeMVar mv + when (isJust v) f + +{- |Reads the next entry from the handle. Once the end of the directory +is reached, returns Nothing and automatically closes the handle. +-} +readDirectory :: DirectoryHandle -> IO (Maybe FilePath) +#ifndef mingw32_HOST_OS +readDirectory hdl@(DirectoryHandle _ dirp) = do + e <- Posix.readDirStream dirp + if null e + then do + closeDirectory hdl + return Nothing + else return (Just e) +#else +readDirectory hdl@(DirectoryHandle _ h fdat mv) = do + -- If the MVar is full, then the filename in fdat has + -- not yet been returned. Otherwise, need to find the next + -- file. + r <- tryTakeMVar mv + case r of + Just () -> getfn + Nothing -> do + more <- Win32.findNextFile h fdat + if more + then getfn + else do + closeDirectory hdl + return Nothing + where + getfn = do + filename <- Win32.getFindDataFileName fdat + return (Just filename) +#endif + +-- True only when directory exists and contains nothing. +-- Throws exception if directory does not exist. +isDirectoryEmpty :: FilePath -> IO Bool +isDirectoryEmpty d = bracket (openDirectory d) closeDirectory check + where + check h = do + v <- readDirectory h + case v of + Nothing -> return True + Just f + | not (dirCruft f) -> return False + | otherwise -> check h |