{-# OPTIONS_HADDOCK hide #-}

module System.Posix.Handle.Internals (
    withHandleFd
  ) where

#ifdef __GLASGOW_HASKELL__
#if __GLASGOW_HASKELL__ >= 611
import GHC.IO.Exception (IOErrorType(..))
import GHC.IO.FD (fdFD)
import Data.Dynamic (cast)
import System.IO.Error
import GHC.IO.Handle.Types (Handle__(..))
import GHC.IO.Handle.Internals (withHandle_)
#else
import GHC.IOBase (haFD)
import GHC.Handle (withHandle_)
#endif
#endif

import System.IO
import System.Posix.Types

withHandleFd :: String -> Handle -> (Fd -> IO a) -> IO a

#ifdef __GLASGOW_HASKELL__
#if __GLASGOW_HASKELL__ >= 611
withHandleFd s h f = withHandle_ s h $ \(Handle__{haDevice=dev}) ->
    case cast dev of
      Nothing -> ioError (ioeSetErrorString (mkIOError IllegalOperation
                                             s (Just h) Nothing)
                          "handle is not a file descriptor")
      Just fd -> f (Fd (fromIntegral (fdFD fd)))
#else
withHandleFd s h f = withHandle_ s h $ \h_ ->
    f (Fd (fromIntegral (haFD h_)))
#endif
#endif