content: {-# LANGUAGE Trustworthy #-}
  {-# LANGUAGE CPP, NoImplicitPrelude #-}
  
  -----------------------------------------------------------------------------
  -- |
  -- Module      :  GHC.IO.Handle.FD
  -- Copyright   :  (c) The University of Glasgow, 1994-2008
  -- License     :  see libraries/base/LICENSE
  --
  -- Maintainer  :  libraries@haskell.org
  -- Stability   :  internal
  -- Portability :  non-portable
  --
  -- Handle operations implemented by file descriptors (FDs)
  --
  -----------------------------------------------------------------------------
  
  module GHC.IO.Handle.FD (
    stdin, stdout, stderr,
    openFile, openBinaryFile, openFileBlocking,
    mkHandleFromFD, fdToHandle, fdToHandle'
   ) where
  
  import GHC.Base
  import GHC.Show
  import Data.Maybe
  import Data.Typeable
  import Foreign.C.Types
  import GHC.MVar
  import GHC.IO
  import GHC.IO.Encoding
  import GHC.IO.Device as IODevice
  import GHC.IO.Exception
  import GHC.IO.IOMode
  import GHC.IO.Handle.Types
  import GHC.IO.Handle.Internals
  import qualified GHC.IO.FD as FD
  import qualified System.Posix.Types as Posix
  import qualified System.Posix.Internals as Posix
  import Java.Exception hiding (IOException)
  
  -- ---------------------------------------------------------------------------
  -- Standard Handles
  
  -- Three handles are allocated during program initialisation.  The first
  -- two manage input or output from the Haskell program's standard input
  -- or output channel respectively.  The third manages output to the
  -- standard error channel. These handles are initially open.
  
  -- | A handle managing input from the Haskell program's standard input channel.
  stdin :: Handle
  {-# NOINLINE stdin #-}
  stdin = unsafePerformIO $ do
     -- ToDo: acquire lock
     setBinaryMode FD.stdin
     enc <- getLocaleEncoding
     mkHandle FD.stdin "<stdin>" ReadHandle Nothing
                  (Just enc)
                  nativeNewlineMode{-translate newlines-}
                  (Just stdHandleFinalizer) Nothing
  
  -- | A handle managing output to the Haskell program's standard output channel.
  stdout :: Handle
  {-# NOINLINE stdout #-}
  stdout = unsafePerformIO $ do
     -- ToDo: acquire lock
     setBinaryMode FD.stdout
     enc <- getLocaleEncoding
     mkHandle FD.stdout "<stdout>" WriteHandle (Just LineBuffering)
                  (Just enc)
                  nativeNewlineMode{-translate newlines-}
                  (Just stdHandleFinalizer) Nothing
  
  -- | A handle managing output to the Haskell program's standard error channel.
  stderr :: Handle
  {-# NOINLINE stderr #-}
  stderr = unsafePerformIO $ do
      -- ToDo: acquire lock
     setBinaryMode FD.stderr
     enc <- getLocaleEncoding
     mkHandle FD.stderr "<stderr>" WriteHandle (Just NoBuffering){-stderr is unbuffered-}
                  (Just enc)
                  nativeNewlineMode{-translate newlines-}
                  (Just stdHandleFinalizer) Nothing
  
  stdHandleFinalizer :: FilePath -> MVar Handle__ -> IO ()
  stdHandleFinalizer fp m = do
    h_ <- takeMVar m
    flushWriteBuffer h_
    case haType h_ of
        ClosedHandle -> return ()
        _other       -> closeTextCodecs h_
    putMVar m (ioe_finalizedHandle fp)
  
  -- We have to put the FDs into binary mode on Windows to avoid the newline
  -- translation that the CRT IO library does.
  setBinaryMode :: FD.FD -> IO ()
  setBinaryMode _ = return ()
  
  -- ---------------------------------------------------------------------------
  
  -- ---------------------------------------------------------------------------
  -- Opening and Closing Files
  
  addFilePathToIOError :: String -> FilePath -> IOException -> IOException
  addFilePathToIOError fun fp ioe
    = ioe{ ioe_location = fun, ioe_filename = Just fp }
  
  -- | Computation 'openFile' @file mode@ allocates and returns a new, open
  -- handle to manage the file @file@.  It manages input if @mode@
  -- is 'ReadMode', output if @mode@ is 'WriteMode' or 'AppendMode',
  -- and both input and output if mode is 'ReadWriteMode'.
  --
  -- If the file does not exist and it is opened for output, it should be
  -- created as a new file.  If @mode@ is 'WriteMode' and the file
  -- already exists, then it should be truncated to zero length.
  -- Some operating systems delete empty files, so there is no guarantee
  -- that the file will exist following an 'openFile' with @mode@
  -- 'WriteMode' unless it is subsequently written to successfully.
  -- The handle is positioned at the end of the file if @mode@ is
  -- 'AppendMode', and otherwise at the beginning (in which case its
  -- internal position is 0).
  -- The initial buffer mode is implementation-dependent.
  --
  -- This operation may fail with:
  --
  --  * 'isAlreadyInUseError' if the file is already open and cannot be reopened;
  --
  --  * 'isDoesNotExistError' if the file does not exist; or
  --
  --  * 'isPermissionError' if the user does not have permission to open the file.
  --
  -- Note: if you will be working with files containing binary data, you'll want to
  -- be using 'openBinaryFile'.
  openFile :: FilePath -> IOMode -> IO Handle
  openFile fp im =
    catchJavaIOError
      (openFile' fp im dEFAULT_OPEN_IN_BINARY_MODE True)
      (\e -> ioError (addFilePathToIOError "openFile" fp e))
  
  -- | Like 'openFile', but opens the file in ordinary blocking mode.
  -- This can be useful for opening a FIFO for reading: if we open in
  -- non-blocking mode then the open will fail if there are no writers,
  -- whereas a blocking open will block until a writer appears.
  --
  -- @since 4.4.0.0
  openFileBlocking :: FilePath -> IOMode -> IO Handle
  openFileBlocking fp im =
    catchException
      (openFile' fp im dEFAULT_OPEN_IN_BINARY_MODE False)
      (\e -> ioError (addFilePathToIOError "openFile" fp e))
  
  -- | Like 'openFile', but open the file in binary mode.
  -- On Windows, reading a file in text mode (which is the default)
  -- will translate CRLF to LF, and writing will translate LF to CRLF.
  -- This is usually what you want with text files.  With binary files
  -- this is undesirable; also, as usual under Microsoft operating systems,
  -- text mode treats control-Z as EOF.  Binary mode turns off all special
  -- treatment of end-of-line and end-of-file characters.
  -- (See also 'hSetBinaryMode'.)
  
  openBinaryFile :: FilePath -> IOMode -> IO Handle
  openBinaryFile fp m =
    catchException
      (openFile' fp m True True)
      (\e -> ioError (addFilePathToIOError "openBinaryFile" fp e))
  
  openFile' :: String -> IOMode -> Bool -> Bool -> IO Handle
  openFile' filepath iomode binary non_blocking = do
    -- first open the file to get an FD
    (fd, fd_type) <- FD.openFile filepath iomode non_blocking
  
    mb_codec <- if binary then return Nothing else fmap Just getLocaleEncoding
  
    -- then use it to make a Handle
    mkHandleFromFD fd fd_type filepath iomode
                     False {- do not *set* non-blocking mode -}
                     mb_codec
              `onException` IODevice.close fd
          -- NB. don't forget to close the FD if mkHandleFromFD fails, otherwise
          -- this FD leaks.
          -- ASSERT: if we just created the file, then fdToHandle' won't fail
          -- (so we don't need to worry about removing the newly created file
          --  in the event of an error).
  
  
  -- ---------------------------------------------------------------------------
  -- Converting file descriptors to Handles
  
  mkHandleFromFD
     :: FD.FD
     -> IODeviceType
     -> FilePath  -- a string describing this file descriptor (e.g. the filename)
     -> IOMode
     -> Bool      --  *set* non-blocking mode on the FD
     -> Maybe TextEncoding
     -> IO Handle
  
  mkHandleFromFD fd0 fd_type filepath iomode set_non_blocking mb_codec
    = do
      -- turn on non-blocking mode
      fd <- if set_non_blocking
               then FD.setNonBlockingMode fd0 True
               else return fd0
  
      let nl | isJust mb_codec = nativeNewlineMode
             | otherwise       = noNewlineTranslation
  
      case fd_type of
          Directory ->
             ioException (IOError Nothing InappropriateType "openFile"
                             "is a directory" Nothing Nothing)
  
          Stream
             -- only *Streams* can be DuplexHandles.  Other read/write
             -- Handles must share a buffer.
             | ReadWriteMode <- iomode ->
                  mkDuplexHandle fd filepath mb_codec nl
  
  
          _other ->
             mkFileHandle fd filepath iomode mb_codec nl
  
  -- | Old API kept to avoid breaking clients
  fdToHandle' :: Posix.Channel
              -> Maybe IODeviceType
              -> Bool -- is_socket on Win, non-blocking on Unix
              -> Maybe FilePath
              -> IOMode
              -> Bool -- binary
              -> IO Handle
  fdToHandle' fdint mb_type is_socket mFilepath iomode binary = do
    let mb_stat = case mb_type of
                          Nothing          -> Nothing
                            -- mkFD will do the stat:
                          Just RegularFile -> Nothing
                            -- no stat required for streams etc.:
                          Just other       -> Just (other, error "fdToHandle: Bad fd.")
    mPath <- case mFilepath of
      Just path -> do
        f <- Posix.getPath path
        return $ Just f
      Nothing -> return Nothing
    (fd,fd_type) <- FD.mkFD fdint mPath iomode mb_stat is_socket
    enc <- if binary then return Nothing else fmap Just getLocaleEncoding
    mkHandleFromFD fd fd_type (fromMaybe "" mFilepath) iomode is_socket enc
  
  
  -- | Turn an existing file descriptor into a Handle.  This is used by
  -- various external libraries to make Handles.
  --
  -- Makes a binary Handle.  This is for historical reasons; it should
  -- probably be a text Handle with the default encoding and newline
  -- translation instead.
  fdToHandle :: Posix.Channel -> IO Handle
  fdToHandle fdint = do
     iomode <- Posix.fdGetMode fdint
     (fd,fd_type) <- FD.mkFD fdint Nothing iomode Nothing False
     let fd_str = "<file descriptor: " ++ show fd ++ ">"
     mkHandleFromFD fd fd_type fd_str iomode False{-non-block-} Nothing -- bin mode
  
  -- ---------------------------------------------------------------------------
  -- Are files opened by default in text or binary mode, if the user doesn't
  -- specify?
  
  dEFAULT_OPEN_IN_BINARY_MODE :: Bool
  dEFAULT_OPEN_IN_BINARY_MODE = False
  