Partially improve the cabalisation
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Don Stewart
278
System/MkTemp.hs
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278
System/MkTemp.hs
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{-# OPTIONS -cpp -fffi -fglasgow-exts #-}
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--
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-- glaexts for I# ops
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--
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-- Copyright (c) 2004-5 Don Stewart - http://www.cse.unsw.edu.au/~dons
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--
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-- This library is free software; you can redistribute it and/or
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-- modify it under the terms of the GNU Lesser General Public
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-- License as published by the Free Software Foundation; either
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-- version 2.1 of the License, or (at your option) any later version.
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--
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-- This library is distributed in the hope that it will be useful,
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-- but WITHOUT ANY WARRANTY; without even the implied warranty of
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-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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-- Lesser General Public License for more details.
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--
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-- You should have received a copy of the GNU Lesser General Public
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-- License along with this library; if not, write to the Free Software
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-- Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
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-- USA
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--
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--
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-- A Haskell reimplementation of the C mktemp/mkstemp/mkstemps library
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-- based on the algorithms in:
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-- > $ OpenBSD: mktemp.c,v 1.17 2003/06/02 20:18:37 millert Exp $
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-- which are available under the BSD license.
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--
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module System.MkTemp (
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mktemp, -- :: FilePath -> IO Maybe FilePath
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mkstemp, -- :: FilePath -> IO Maybe (FilePath, Handle)
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mkstemps, -- :: FilePath -> Int -> IO Maybe (FilePath,Handle)
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mkdtemp, -- :: FilePath -> IO Maybe FilePath
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) where
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import Data.List
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import Data.Char ( chr, ord, isDigit )
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import Control.Monad ( liftM )
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import Control.Exception ( handleJust )
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import System.Directory ( doesDirectoryExist, doesFileExist, createDirectory )
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import System.IO
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#ifndef __MINGW32__
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import System.IO.Error ( isAlreadyExistsError )
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#else
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import System.IO.Error ( isAlreadyExistsError, isAlreadyInUseError, isPermissionError )
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#endif
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import GHC.IOBase ( IOException(IOError),
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Exception(IOException),
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IOErrorType(AlreadyExists) )
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#ifndef __MINGW32__
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import qualified System.Posix.Internals ( c_getpid )
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#endif
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#ifdef HAVE_ARC4RANDOM
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import GHC.Base hiding ( ord, chr )
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import GHC.Int
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#else
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import System.Random ( getStdRandom, Random(randomR) )
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#endif
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------------------------------------------------------------------------
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mkstemps :: FilePath -> Int -> IO (Maybe (FilePath,Handle))
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mkstemp :: FilePath -> IO (Maybe (FilePath,Handle))
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mktemp :: FilePath -> IO (Maybe FilePath)
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mkdtemp :: FilePath -> IO (Maybe FilePath)
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mkstemps path slen = gettemp path True False slen
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mkstemp path = gettemp path True False 0
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mktemp path = do v <- gettemp path False False 0
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return $ case v of Just (path',_) -> Just path'; _ -> Nothing
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mkdtemp path = do v <- gettemp path False True 0
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return $ case v of Just (path',_) -> Just path'; _ -> Nothing
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------------------------------------------------------------------------
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gettemp :: FilePath -> Bool -> Bool -> Int -> IO (Maybe (FilePath, Handle))
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gettemp [] _ _ _ = return Nothing
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gettemp _ True True _ = return Nothing
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gettemp path doopen domkdir slen = do
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--
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-- firstly, break up the path and extract the template
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--
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let (pref,tmpl,suff) = let (r,s) = splitAt (length path - slen) path
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(p,t) = break (== 'X') r
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in (p,t,s)
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--
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-- an error if there is only a suffix, it seems
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--
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if null pref && null tmpl then return Nothing else do {
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--
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-- replace end of template with process id, and rest with randomness
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--
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;pid <- liftM show $ getProcessID
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;let (rest, xs) = merge tmpl pid
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;as <- randomise rest
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;let tmpl' = as ++ xs
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path' = pref ++ tmpl' ++ suff
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--
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-- just check if we can get at the directory we might need
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--
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;dir_ok <- if doopen || domkdir
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then let d = reverse $ dropWhile (/= '/') $ reverse path'
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in doesDirectoryExist d
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else return True
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;if not dir_ok then return Nothing else do {
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--
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-- We need a function for looking for appropriate temp files
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--
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;let fn p
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| doopen = handleJust isInUse (\_ -> return Nothing) $
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do h <- open0600 p ; return $ Just h
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| domkdir = handleJust alreadyExists (\_ -> return Nothing) $
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do mkdir0700 p ; return $ Just undefined
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| otherwise = do b <- doesFileExist p
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return $ if b then Nothing else Just undefined
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--
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-- now, try to create the tmp file, permute if we can't
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-- once we've tried all permutations, give up
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--
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;let tryIt p t i =
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do v <- fn p
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case v of Just h -> return $ Just (p,h) -- it worked
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Nothing -> let (i',t') = tweak i t
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in if null t'
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then return Nothing -- no more
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else tryIt (pref++t'++suff) t' i'
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;tryIt path' tmpl' 0
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}}
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--
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-- Replace X's with pid digits. Complete rewrite
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--
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merge :: String -> String -> (String,String)
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merge t [] = (t ,[])
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merge [] _ = ([] ,[])
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merge (_:ts) (p:ps) = (ts',p:ps')
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where (ts',ps') = merge ts ps
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--
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-- And replace remaining X's with random chars
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-- randomR is pretty slow, oh well.
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--
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randomise :: String -> IO String
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randomise [] = return []
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randomise ('X':xs) = do p <- getRandom ()
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let c = chr $! if p < 26
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then p + (ord 'A')
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else (p - 26) + (ord 'a')
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xs' <- randomise xs
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return (c : xs')
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randomise s = return s
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--
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-- "tricky little algorithm for backward compatibility"
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-- could do with a Haskellish rewrite
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--
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tweak :: Int -> String -> (Int,String)
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tweak i s
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| i > length s - 1 = (i,[]) -- no more
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| s !! i == 'Z' = if i == length s - 1
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then (i,[]) -- no more
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else let s' = splice (i+1) 'a'
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in tweak (i+1) s' -- loop
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| otherwise = let c = s !! i in case () of {_
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| isDigit c -> (i, splice i 'a' )
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| c == 'z' -> (i, splice i 'A' )
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| otherwise -> let c' = chr $ (ord c) + 1 in (i,splice i c')
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}
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where
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splice j c = let (a,b) = splitAt j s in a ++ [c] ++ tail b
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-- ---------------------------------------------------------------------
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alreadyExists :: Exception -> Maybe Exception
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alreadyExists e@(IOException ioe)
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| isAlreadyExistsError ioe = Just e
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| otherwise = Nothing
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alreadyExists _ = Nothing
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isInUse :: Exception -> Maybe ()
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#ifndef __MINGW32__
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isInUse (IOException ioe)
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| isAlreadyExistsError ioe = Just ()
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| otherwise = Nothing
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isInUse _ = Nothing
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#else
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isInUse (IOException ioe)
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| isAlreadyInUseError ioe = Just ()
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| isPermissionError ioe = Just ()
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| isAlreadyExistsError ioe = Just () -- we throw this
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| otherwise = Nothing
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isInUse _ = Nothing
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#endif
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-- ---------------------------------------------------------------------
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-- Create a file mode 0600 if possible
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--
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-- N.B. race condition between testing existence and opening
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-- But we can live with that to avoid a posix dependency, right?
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--
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open0600 :: FilePath -> IO Handle
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open0600 f = do
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b <- doesFileExist f
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if b then ioError err -- race
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else openFile f ReadWriteMode
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where
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err = IOError Nothing AlreadyExists "open0600" "already exists" Nothing
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{-
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-- open(path, O_CREAT|O_EXCL|O_RDWR, 0600)
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--
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open0600 f = do
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openFd f ReadWrite (Just o600) excl >>= fdToHandle
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where
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o600 = ownerReadMode `unionFileModes` ownerWriteMode
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excl = defaultFileFlags { exclusive = True }
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-}
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--
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-- create a directory mode 0700 if possible
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--
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mkdir0700 :: FilePath -> IO ()
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mkdir0700 dir = createDirectory dir
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{-
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System.Posix.Directory.createDirectory dir ownerModes
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-}
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-- | getProcessId, stolen from GHC (main/SysTools.lhs)
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--
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#ifdef __MINGW32__
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-- relies on Int == Int32 on Windows
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foreign import ccall unsafe "_getpid" getProcessID' :: IO Int
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getProcessID :: IO Int
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getProcessID = liftM abs getProcessID'
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#else
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getProcessID :: IO Int
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#ifdef CYGWIN
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getProcessID = System.Posix.Internals.c_getpid >>= return . abs . fromIntegral
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#else
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getProcessID = System.Posix.Internals.c_getpid >>= return . fromIntegral
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#endif
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#endif
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-- ---------------------------------------------------------------------
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-- | Use a variety of random functions, if you like.
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--
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getRandom :: () -> IO Int
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#ifndef HAVE_ARC4RANDOM
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getRandom _ = getStdRandom (randomR (0,51))
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#else
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--
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-- OpenBSD: "The arc4random() function provides a high quality 32-bit
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-- pseudo-random number very quickly. arc4random() seeds itself on a
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-- regular basis from the kernel strong random number subsystem
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-- described in random(4)." Also, it is a bit faster than getStdRandom
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--
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getRandom _ = do
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(I32# i) <- c_arc4random
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return (I# (word2Int# ((int2Word# i `and#` int2Word# 0xffff#)
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`remWord#` int2Word# 52#)))
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foreign import ccall unsafe "stdlib.h arc4random" c_arc4random :: IO Int32
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#endif
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