    {-# OPTIONS_GHC -fno-implicit-prelude #-}

    -----------------------------------------------------------------------------
    -- |
    -- Module      :  System.Posix.Internals
    -- Copyright   :  (c) The University of Glasgow, 1992-2002
    -- License     :  see libraries/base/LICENSE
    --
    -- Maintainer  :  cvs-ghc@haskell.org
    -- Stability   :  internal
    -- Portability :  non-portable (requires POSIX)
    --
    -- POSIX support layer for the standard libraries.
    -- This library is built on *every* platform, including Win32.
    --
    -- Non-posix compliant in order to support the following features:
    --	* S_ISSOCK (no sockets in POSIX)
    --
    -----------------------------------------------------------------------------

    -- #hide
    module System.Posix.Internals where

    #include "HsBaseConfig.h"

    import Control.Monad
    import System.Posix.Types

    import Foreign
    import Foreign.C

    import Data.Bits
    import Data.Maybe

    #if __GLASGOW_HASKELL__
    import GHC.Base
    import GHC.Num
    import GHC.Real
    import GHC.IOBase
    #elif __HUGS__
    import Hugs.Prelude (IOException(..), IOErrorType(..))
    import Hugs.IO (IOMode(..))
    #else
    import System.IO
    #endif

    #ifdef __HUGS__
    {-# CFILES cbits/PrelIOUtils.c cbits/dirUtils.c cbits/consUtils.c #-}
    #endif

    -- ---------------------------------------------------------------------------
    -- Types

    type CDir       = ()
    type CDirent    = ()
    type CFLock     = ()
    type CGroup     = ()
    type CLconv     = ()
    type CPasswd    = ()
    type CSigaction = ()
    type CSigset    = ()
    type CStat      = ()
    type CTermios   = ()
    type CTm	= ()
    type CTms	= ()
    type CUtimbuf   = ()
    type CUtsname   = ()

    #ifndef __GLASGOW_HASKELL__
    type FD = CInt
    #endif

    -- ---------------------------------------------------------------------------
    -- stat()-related stuff

    fdFileSize :: FD -> IO Integer
    fdFileSize fd =
      allocaBytes sizeof_stat $ \ p_stat -> do
        throwErrnoIfMinus1Retry "fileSize" $
    	c_fstat fd p_stat
        c_mode <- st_mode p_stat :: IO CMode
        if not (s_isreg c_mode)
    	then return (-1)
    	else do
        c_size <- st_size p_stat
        return (fromIntegral c_size)

    data FDType  = Directory | Stream | RegularFile | RawDevice
    	       deriving (Eq)

    fileType :: FilePath -> IO FDType
    fileType file =
      allocaBytes sizeof_stat $ \ p_stat -> do
      withCString file $ \p_file -> do
        throwErrnoIfMinus1Retry "fileType" $
          c_stat p_file p_stat
        statGetType p_stat

    -- NOTE: On Win32 platforms, this will only work with file descriptors
    -- referring to file handles. i.e., it'll fail for socket FDs.
    fdStat :: FD -> IO (FDType, CDev, CIno)
    fdStat fd =
      allocaBytes sizeof_stat $ \ p_stat -> do
        throwErrnoIfMinus1Retry "fdType" $
    	c_fstat fd p_stat
        ty <- statGetType p_stat
        dev <- st_dev p_stat
        ino <- st_ino p_stat
        return (ty,dev,ino)

    fdType :: FD -> IO FDType
    fdType fd = do (ty,_,_) <- fdStat fd; return ty

    statGetType p_stat = do
      c_mode <- st_mode p_stat :: IO CMode
      case () of
          _ | s_isdir c_mode    	-> return Directory
            | s_isfifo c_mode || s_issock c_mode || s_ischr  c_mode
    			  	-> return Stream
    	| s_isreg c_mode	-> return RegularFile
    	 -- Q: map char devices to RawDevice too?
    	| s_isblk c_mode        -> return RawDevice
    	| otherwise		-> ioError ioe_unknownfiletype

    ioe_unknownfiletype = IOError Nothing UnsupportedOperation "fdType"
    			"unknown file type" Nothing

    #if __GLASGOW_HASKELL__ && (defined(mingw32_HOST_OS) || defined(__MINGW32__))
    closeFd :: Bool -> CInt -> IO CInt
    closeFd isStream fd
      | isStream  = c_closesocket fd
      | otherwise = c_close fd

    foreign import stdcall unsafe "HsBase.h closesocket"
       c_closesocket :: CInt -> IO CInt
    #endif

    fdGetMode :: FD -> IO IOMode
    fdGetMode fd = do
    #if defined(mingw32_HOST_OS) || defined(__MINGW32__)
        -- We don't have a way of finding out which flags are set on FDs
        -- on Windows, so make a handle that thinks that anything goes.
        let flags = o_RDWR
    #else
        flags <- throwErrnoIfMinus1Retry "fdGetMode"
    		(c_fcntl_read fd const_f_getfl)
    #endif
        let
           wH  = (flags .&. o_WRONLY) /= 0
           aH  = (flags .&. o_APPEND) /= 0
           rwH = (flags .&. o_RDWR) /= 0

           mode
    	 | wH && aH  = AppendMode
    	 | wH        = WriteMode
    	 | rwH       = ReadWriteMode
    	 | otherwise = ReadMode

        return mode

    -- ---------------------------------------------------------------------------
    -- Terminal-related stuff

    fdIsTTY :: FD -> IO Bool
    fdIsTTY fd = c_isatty fd >>= return.toBool

    #if defined(HTYPE_TCFLAG_T)

    setEcho :: FD -> Bool -> IO ()
    setEcho fd on = do
      tcSetAttr fd $ \ p_tios -> do
        c_lflag <- c_lflag p_tios :: IO CTcflag
        let new_c_lflag
    	 | on        = c_lflag .|. fromIntegral const_echo
    	 | otherwise = c_lflag .&. complement (fromIntegral const_echo)
        poke_c_lflag p_tios (new_c_lflag :: CTcflag)

    getEcho :: FD -> IO Bool
    getEcho fd = do
      tcSetAttr fd $ \ p_tios -> do
        c_lflag <- c_lflag p_tios :: IO CTcflag
        return ((c_lflag .&. fromIntegral const_echo) /= 0)

    setCooked :: FD -> Bool -> IO ()
    setCooked fd cooked =
      tcSetAttr fd $ \ p_tios -> do

        -- turn on/off ICANON
        c_lflag <- c_lflag p_tios :: IO CTcflag
        let new_c_lflag | cooked    = c_lflag .|. (fromIntegral const_icanon)
    	            | otherwise = c_lflag .&. complement (fromIntegral const_icanon)
        poke_c_lflag p_tios (new_c_lflag :: CTcflag)

        -- set VMIN & VTIME to 1/0 respectively
        when (not cooked) $ do
                c_cc <- ptr_c_cc p_tios
    	    let vmin  = (c_cc `plusPtr` (fromIntegral const_vmin))  :: Ptr Word8
    		vtime = (c_cc `plusPtr` (fromIntegral const_vtime)) :: Ptr Word8
    	    poke vmin  1
    	    poke vtime 0

    tcSetAttr :: FD -> (Ptr CTermios -> IO a) -> IO a
    tcSetAttr fd fun = do
         allocaBytes sizeof_termios  $ \p_tios -> do
    	throwErrnoIfMinus1Retry "tcSetAttr"
    	   (c_tcgetattr fd p_tios)

    #ifdef __GLASGOW_HASKELL__
    	-- Save a copy of termios, if this is a standard file descriptor.
    	-- These terminal settings are restored in hs_exit().
    	when (fd <= 2) $ do
    	  p <- get_saved_termios fd
    	  when (p == nullPtr) $ do
    	     saved_tios <- mallocBytes sizeof_termios
    	     copyBytes saved_tios p_tios sizeof_termios
    	     set_saved_termios fd saved_tios
    #endif

    	-- tcsetattr() when invoked by a background process causes the process
    	-- to be sent SIGTTOU regardless of whether the process has TOSTOP set
    	-- in its terminal flags (try it...).  This function provides a
    	-- wrapper which temporarily blocks SIGTTOU around the call, making it
    	-- transparent.
    	allocaBytes sizeof_sigset_t $ \ p_sigset -> do
    	allocaBytes sizeof_sigset_t $ \ p_old_sigset -> do
    	     c_sigemptyset p_sigset
    	     c_sigaddset   p_sigset const_sigttou
    	     c_sigprocmask const_sig_block p_sigset p_old_sigset
    	     r <- fun p_tios  -- do the business
    	     throwErrnoIfMinus1Retry_ "tcSetAttr" $
    		 c_tcsetattr fd const_tcsanow p_tios
    	     c_sigprocmask const_sig_setmask p_old_sigset nullPtr
    	     return r

    #ifdef __GLASGOW_HASKELL__
    foreign import ccall unsafe "HsBase.h __hscore_get_saved_termios"
       get_saved_termios :: CInt -> IO (Ptr CTermios)

    foreign import ccall unsafe "HsBase.h __hscore_set_saved_termios"
       set_saved_termios :: CInt -> (Ptr CTermios) -> IO ()
    #endif

    #else

    -- 'raw' mode for Win32 means turn off 'line input' (=> buffering and
    -- character translation for the console.) The Win32 API for doing
    -- this is GetConsoleMode(), which also requires echoing to be disabled
    -- when turning off 'line input' processing. Notice that turning off
    -- 'line input' implies enter/return is reported as '\r' (and it won't
    -- report that character until another character is input..odd.) This
    -- latter feature doesn't sit too well with IO actions like IO.hGetLine..
    -- consider yourself warned.
    setCooked :: FD -> Bool -> IO ()
    setCooked fd cooked = do
      x <- set_console_buffering fd (if cooked then 1 else 0)
      if (x /= 0)
       then ioError (ioe_unk_error "setCooked" "failed to set buffering")
       else return ()

    ioe_unk_error loc msg
     = IOError Nothing OtherError loc msg Nothing

    -- Note: echoing goes hand in hand with enabling 'line input' / raw-ness
    -- for Win32 consoles, hence setEcho ends up being the inverse of setCooked.
    setEcho :: FD -> Bool -> IO ()
    setEcho fd on = do
      x <- set_console_echo fd (if on then 1 else 0)
      if (x /= 0)
       then ioError (ioe_unk_error "setEcho" "failed to set echoing")
       else return ()

    getEcho :: FD -> IO Bool
    getEcho fd = do
      r <- get_console_echo fd
      if (r == (-1))
       then ioError (ioe_unk_error "getEcho" "failed to get echoing")
       else return (r == 1)

    foreign import ccall unsafe "consUtils.h set_console_buffering__"
       set_console_buffering :: CInt -> CInt -> IO CInt

    foreign import ccall unsafe "consUtils.h set_console_echo__"
       set_console_echo :: CInt -> CInt -> IO CInt

    foreign import ccall unsafe "consUtils.h get_console_echo__"
       get_console_echo :: CInt -> IO CInt

    #endif

    -- ---------------------------------------------------------------------------
    -- Turning on non-blocking for a file descriptor

    #if !defined(mingw32_HOST_OS) && !defined(__MINGW32__)

    setNonBlockingFD fd = do
      flags <- throwErrnoIfMinus1Retry "setNonBlockingFD"
    		 (c_fcntl_read fd const_f_getfl)
      -- An error when setting O_NONBLOCK isn't fatal: on some systems
      -- there are certain file handles on which this will fail (eg. /dev/null
      -- on FreeBSD) so we throw away the return code from fcntl_write.
      unless (testBit flags (fromIntegral o_NONBLOCK)) $ do
        c_fcntl_write fd const_f_setfl (fromIntegral (flags .|. o_NONBLOCK))
        return ()
    #else

    -- bogus defns for win32
    setNonBlockingFD fd = return ()

    #endif

    -- -----------------------------------------------------------------------------
    -- foreign imports

    foreign import ccall unsafe "HsBase.h access"
       c_access :: CString -> CInt -> IO CInt

    foreign import ccall unsafe "HsBase.h chmod"
       c_chmod :: CString -> CMode -> IO CInt

    foreign import ccall unsafe "HsBase.h chdir"
       c_chdir :: CString -> IO CInt

    foreign import ccall unsafe "HsBase.h close"
       c_close :: CInt -> IO CInt

    foreign import ccall unsafe "HsBase.h closedir"
       c_closedir :: Ptr CDir -> IO CInt

    foreign import ccall unsafe "HsBase.h creat"
       c_creat :: CString -> CMode -> IO CInt

    foreign import ccall unsafe "HsBase.h dup"
       c_dup :: CInt -> IO CInt

    foreign import ccall unsafe "HsBase.h dup2"
       c_dup2 :: CInt -> CInt -> IO CInt

    foreign import ccall unsafe "HsBase.h __hscore_fstat"
       c_fstat :: CInt -> Ptr CStat -> IO CInt

    foreign import ccall unsafe "HsBase.h getcwd"
       c_getcwd   :: Ptr CChar -> CSize -> IO (Ptr CChar)

    foreign import ccall unsafe "HsBase.h isatty"
       c_isatty :: CInt -> IO CInt

    #if defined(mingw32_HOST_OS) || defined(__MINGW32__)
    foreign import ccall unsafe "HsBase.h __hscore_lseek"
       c_lseek :: CInt -> Int64 -> CInt -> IO Int64
    #else
    foreign import ccall unsafe "HsBase.h __hscore_lseek"
       c_lseek :: CInt -> COff -> CInt -> IO COff
    #endif

    foreign import ccall unsafe "HsBase.h __hscore_lstat"
       lstat :: CString -> Ptr CStat -> IO CInt

    foreign import ccall unsafe "HsBase.h __hscore_open"
       c_open :: CString -> CInt -> CMode -> IO CInt

    foreign import ccall unsafe "HsBase.h opendir"
       c_opendir :: CString  -> IO (Ptr CDir)

    foreign import ccall unsafe "HsBase.h __hscore_mkdir"
       mkdir :: CString -> CInt -> IO CInt

    foreign import ccall unsafe "HsBase.h read"
       c_read :: CInt -> Ptr CChar -> CSize -> IO CSsize

    foreign import ccall unsafe "dirUtils.h __hscore_renameFile"
       c_rename :: CString -> CString -> IO CInt

    foreign import ccall unsafe "HsBase.h rewinddir"
       c_rewinddir :: Ptr CDir -> IO ()

    foreign import ccall unsafe "HsBase.h rmdir"
       c_rmdir :: CString -> IO CInt

    foreign import ccall unsafe "HsBase.h __hscore_stat"
       c_stat :: CString -> Ptr CStat -> IO CInt

    foreign import ccall unsafe "HsBase.h umask"
       c_umask :: CMode -> IO CMode

    foreign import ccall unsafe "HsBase.h write"
       c_write :: CInt -> Ptr CChar -> CSize -> IO CSsize

    foreign import ccall unsafe "HsBase.h __hscore_ftruncate"
       c_ftruncate :: CInt -> COff -> IO CInt

    foreign import ccall unsafe "HsBase.h unlink"
       c_unlink :: CString -> IO CInt

    foreign import ccall unsafe "HsBase.h getpid"
       c_getpid :: IO CPid

    #if !defined(mingw32_HOST_OS) && !defined(__MINGW32__)
    foreign import ccall unsafe "HsBase.h fcntl"
       c_fcntl_read  :: CInt -> CInt -> IO CInt

    foreign import ccall unsafe "HsBase.h fcntl"
       c_fcntl_write :: CInt -> CInt -> CLong -> IO CInt

    foreign import ccall unsafe "HsBase.h fcntl"
       c_fcntl_lock  :: CInt -> CInt -> Ptr CFLock -> IO CInt

    foreign import ccall unsafe "HsBase.h fork"
       c_fork :: IO CPid

    foreign import ccall unsafe "HsBase.h link"
       c_link :: CString -> CString -> IO CInt

    foreign import ccall unsafe "HsBase.h mkfifo"
       c_mkfifo :: CString -> CMode -> IO CInt

    foreign import ccall unsafe "HsBase.h pipe"
       c_pipe :: Ptr CInt -> IO CInt

    foreign import ccall unsafe "HsBase.h __hscore_sigemptyset"
       c_sigemptyset :: Ptr CSigset -> IO CInt

    foreign import ccall unsafe "HsBase.h __hscore_sigaddset"
       c_sigaddset :: Ptr CSigset -> CInt -> IO CInt

    foreign import ccall unsafe "HsBase.h sigprocmask"
       c_sigprocmask :: CInt -> Ptr CSigset -> Ptr CSigset -> IO CInt

    foreign import ccall unsafe "HsBase.h tcgetattr"
       c_tcgetattr :: CInt -> Ptr CTermios -> IO CInt

    foreign import ccall unsafe "HsBase.h tcsetattr"
       c_tcsetattr :: CInt -> CInt -> Ptr CTermios -> IO CInt

    foreign import ccall unsafe "HsBase.h utime"
       c_utime :: CString -> Ptr CUtimbuf -> IO CInt

    foreign import ccall unsafe "HsBase.h waitpid"
       c_waitpid :: CPid -> Ptr CInt -> CInt -> IO CPid
    #endif

    -- traversing directories
    foreign import ccall unsafe "dirUtils.h __hscore_readdir"
      readdir  :: Ptr CDir -> Ptr (Ptr CDirent) -> IO CInt

    foreign import ccall unsafe "HsBase.h __hscore_free_dirent"
      freeDirEnt  :: Ptr CDirent -> IO ()

    foreign import ccall unsafe "HsBase.h __hscore_end_of_dir"
      end_of_dir :: CInt

    foreign import ccall unsafe "HsBase.h __hscore_d_name"
      d_name :: Ptr CDirent -> IO CString

    -- POSIX flags only:
    foreign import ccall unsafe "HsBase.h __hscore_o_rdonly" o_RDONLY :: CInt
    foreign import ccall unsafe "HsBase.h __hscore_o_wronly" o_WRONLY :: CInt
    foreign import ccall unsafe "HsBase.h __hscore_o_rdwr"   o_RDWR   :: CInt
    foreign import ccall unsafe "HsBase.h __hscore_o_append" o_APPEND :: CInt
    foreign import ccall unsafe "HsBase.h __hscore_o_creat"  o_CREAT  :: CInt
    foreign import ccall unsafe "HsBase.h __hscore_o_excl"   o_EXCL   :: CInt
    foreign import ccall unsafe "HsBase.h __hscore_o_trunc"  o_TRUNC  :: CInt

    -- non-POSIX flags.
    foreign import ccall unsafe "HsBase.h __hscore_o_noctty"   o_NOCTTY   :: CInt
    foreign import ccall unsafe "HsBase.h __hscore_o_nonblock" o_NONBLOCK :: CInt
    foreign import ccall unsafe "HsBase.h __hscore_o_binary"   o_BINARY   :: CInt

    foreign import ccall unsafe "HsBase.h __hscore_s_isreg"  c_s_isreg  :: CMode -> CInt
    foreign import ccall unsafe "HsBase.h __hscore_s_ischr"  c_s_ischr  :: CMode -> CInt
    foreign import ccall unsafe "HsBase.h __hscore_s_isblk"  c_s_isblk  :: CMode -> CInt
    foreign import ccall unsafe "HsBase.h __hscore_s_isdir"  c_s_isdir  :: CMode -> CInt
    foreign import ccall unsafe "HsBase.h __hscore_s_isfifo" c_s_isfifo :: CMode -> CInt

    s_isreg  :: CMode -> Bool
    s_isreg cm = c_s_isreg cm /= 0
    s_ischr  :: CMode -> Bool
    s_ischr cm = c_s_ischr cm /= 0
    s_isblk  :: CMode -> Bool
    s_isblk cm = c_s_isblk cm /= 0
    s_isdir  :: CMode -> Bool
    s_isdir cm = c_s_isdir cm /= 0
    s_isfifo :: CMode -> Bool
    s_isfifo cm = c_s_isfifo cm /= 0

    foreign import ccall unsafe "HsBase.h __hscore_sizeof_stat" sizeof_stat :: Int
    foreign import ccall unsafe "HsBase.h __hscore_st_mtime" st_mtime :: Ptr CStat -> IO CTime
    #ifdef mingw32_HOST_OS
    foreign import ccall unsafe "HsBase.h __hscore_st_size" st_size :: Ptr CStat -> IO Int64
    #else
    foreign import ccall unsafe "HsBase.h __hscore_st_size" st_size :: Ptr CStat -> IO COff
    #endif
    foreign import ccall unsafe "HsBase.h __hscore_st_mode" st_mode :: Ptr CStat -> IO CMode
    foreign import ccall unsafe "HsBase.h __hscore_st_dev" st_dev :: Ptr CStat -> IO CDev
    foreign import ccall unsafe "HsBase.h __hscore_st_ino" st_ino :: Ptr CStat -> IO CIno

    foreign import ccall unsafe "HsBase.h __hscore_echo"         const_echo :: CInt
    foreign import ccall unsafe "HsBase.h __hscore_tcsanow"      const_tcsanow :: CInt
    foreign import ccall unsafe "HsBase.h __hscore_icanon"       const_icanon :: CInt
    foreign import ccall unsafe "HsBase.h __hscore_vmin"         const_vmin   :: CInt
    foreign import ccall unsafe "HsBase.h __hscore_vtime"        const_vtime  :: CInt
    foreign import ccall unsafe "HsBase.h __hscore_sigttou"      const_sigttou :: CInt
    foreign import ccall unsafe "HsBase.h __hscore_sig_block"    const_sig_block :: CInt
    foreign import ccall unsafe "HsBase.h __hscore_sig_setmask"  const_sig_setmask :: CInt
    foreign import ccall unsafe "HsBase.h __hscore_f_getfl"      const_f_getfl :: CInt
    foreign import ccall unsafe "HsBase.h __hscore_f_setfl"      const_f_setfl :: CInt

    #if defined(HTYPE_TCFLAG_T)
    foreign import ccall unsafe "HsBase.h __hscore_sizeof_termios"  sizeof_termios :: Int
    foreign import ccall unsafe "HsBase.h __hscore_sizeof_sigset_t" sizeof_sigset_t :: Int

    foreign import ccall unsafe "HsBase.h __hscore_lflag" c_lflag :: Ptr CTermios -> IO CTcflag
    foreign import ccall unsafe "HsBase.h __hscore_poke_lflag" poke_c_lflag :: Ptr CTermios -> CTcflag -> IO ()
    foreign import ccall unsafe "HsBase.h __hscore_ptr_c_cc" ptr_c_cc  :: Ptr CTermios -> IO (Ptr Word8)
    #endif

    #if !defined(mingw32_HOST_OS) && !defined(__MINGW32__)
    foreign import ccall unsafe "HsBase.h __hscore_s_issock" c_s_issock :: CMode -> CInt
    s_issock :: CMode -> Bool
    s_issock cmode = c_s_issock cmode /= 0
    #else
    s_issock :: CMode -> Bool
    s_issock cmode = False
    #endif