1 {-# OPTIONS_GHC -XNoImplicitPrelude #-}
2 -----------------------------------------------------------------------------
4 -- Module : GHC.IO.Handle.FD
5 -- Copyright : (c) The University of Glasgow, 1994-2008
6 -- License : see libraries/base/LICENSE
8 -- Maintainer : libraries@haskell.org
9 -- Stability : internal
10 -- Portability : non-portable
12 -- Handle operations implemented by file descriptors (FDs)
14 -----------------------------------------------------------------------------
16 module GHC.IO.Handle.FD (
17 stdin, stdout, stderr,
18 openFile, openBinaryFile,
19 mkHandleFromFD, fdToHandle, fdToHandle',
28 -- import Control.Monad
29 import Foreign.C.Types
32 import GHC.IO.Encoding
33 -- import GHC.IO.Exception
34 import GHC.IO.Device as IODevice
35 import GHC.IO.Exception
38 import GHC.IO.Handle.Types
39 import GHC.IO.Handle.Internals
40 import GHC.IO.FD (FD(..))
41 import qualified GHC.IO.FD as FD
42 import qualified System.Posix.Internals as Posix
44 -- ---------------------------------------------------------------------------
47 -- Three handles are allocated during program initialisation. The first
48 -- two manage input or output from the Haskell program's standard input
49 -- or output channel respectively. The third manages output to the
50 -- standard error channel. These handles are initially open.
52 -- | A handle managing input from the Haskell program's standard input channel.
54 {-# NOINLINE stdin #-}
55 stdin = unsafePerformIO $ do
57 setBinaryMode FD.stdin
58 mkHandle FD.stdin "<stdin>" ReadHandle True (Just localeEncoding)
59 nativeNewlineMode{-translate newlines-}
60 (Just stdHandleFinalizer) Nothing
62 -- | A handle managing output to the Haskell program's standard output channel.
64 {-# NOINLINE stdout #-}
65 stdout = unsafePerformIO $ do
67 setBinaryMode FD.stdout
68 mkHandle FD.stdout "<stdout>" WriteHandle True (Just localeEncoding)
69 nativeNewlineMode{-translate newlines-}
70 (Just stdHandleFinalizer) Nothing
72 -- | A handle managing output to the Haskell program's standard error channel.
74 {-# NOINLINE stderr #-}
75 stderr = unsafePerformIO $ do
77 setBinaryMode FD.stderr
78 mkHandle FD.stderr "<stderr>" WriteHandle False{-stderr is unbuffered-}
80 nativeNewlineMode{-translate newlines-}
81 (Just stdHandleFinalizer) Nothing
83 stdHandleFinalizer :: FilePath -> MVar Handle__ -> IO ()
84 stdHandleFinalizer fp m = do
87 putMVar m (ioe_finalizedHandle fp)
89 -- We have to put the FDs into binary mode on Windows to avoid the newline
90 -- translation that the CRT IO library does.
91 setBinaryMode :: FD -> IO ()
92 #ifdef mingw32_HOST_OS
93 setBinaryMode fd = do _ <- setmode (fdFD fd) True
96 setBinaryMode _ = return ()
99 #ifdef mingw32_HOST_OS
100 foreign import ccall unsafe "__hscore_setmode"
101 setmode :: CInt -> Bool -> IO CInt
104 -- ---------------------------------------------------------------------------
107 -- | The computation 'isEOF' is identical to 'hIsEOF',
108 -- except that it works only on 'stdin'.
113 -- ---------------------------------------------------------------------------
114 -- Opening and Closing Files
116 addFilePathToIOError :: String -> FilePath -> IOException -> IOException
117 addFilePathToIOError fun fp ioe
118 = ioe{ ioe_location = fun, ioe_filename = Just fp }
120 -- | Computation 'openFile' @file mode@ allocates and returns a new, open
121 -- handle to manage the file @file@. It manages input if @mode@
122 -- is 'ReadMode', output if @mode@ is 'WriteMode' or 'AppendMode',
123 -- and both input and output if mode is 'ReadWriteMode'.
125 -- If the file does not exist and it is opened for output, it should be
126 -- created as a new file. If @mode@ is 'WriteMode' and the file
127 -- already exists, then it should be truncated to zero length.
128 -- Some operating systems delete empty files, so there is no guarantee
129 -- that the file will exist following an 'openFile' with @mode@
130 -- 'WriteMode' unless it is subsequently written to successfully.
131 -- The handle is positioned at the end of the file if @mode@ is
132 -- 'AppendMode', and otherwise at the beginning (in which case its
133 -- internal position is 0).
134 -- The initial buffer mode is implementation-dependent.
136 -- This operation may fail with:
138 -- * 'isAlreadyInUseError' if the file is already open and cannot be reopened;
140 -- * 'isDoesNotExistError' if the file does not exist; or
142 -- * 'isPermissionError' if the user does not have permission to open the file.
144 -- Note: if you will be working with files containing binary data, you'll want to
145 -- be using 'openBinaryFile'.
146 openFile :: FilePath -> IOMode -> IO Handle
149 (openFile' fp im dEFAULT_OPEN_IN_BINARY_MODE)
150 (\e -> ioError (addFilePathToIOError "openFile" fp e))
152 -- | Like 'openFile', but open the file in binary mode.
153 -- On Windows, reading a file in text mode (which is the default)
154 -- will translate CRLF to LF, and writing will translate LF to CRLF.
155 -- This is usually what you want with text files. With binary files
156 -- this is undesirable; also, as usual under Microsoft operating systems,
157 -- text mode treats control-Z as EOF. Binary mode turns off all special
158 -- treatment of end-of-line and end-of-file characters.
159 -- (See also 'hSetBinaryMode'.)
161 openBinaryFile :: FilePath -> IOMode -> IO Handle
162 openBinaryFile fp m =
164 (openFile' fp m True)
165 (\e -> ioError (addFilePathToIOError "openBinaryFile" fp e))
167 openFile' :: String -> IOMode -> Bool -> IO Handle
168 openFile' filepath iomode binary = do
169 -- first open the file to get an FD
170 (fd, fd_type) <- FD.openFile filepath iomode
172 let mb_codec = if binary then Nothing else Just localeEncoding
174 -- then use it to make a Handle
175 mkHandleFromFD fd fd_type filepath iomode True{-non-blocking-} mb_codec
176 `onException` IODevice.close fd
177 -- NB. don't forget to close the FD if mkHandleFromFD fails, otherwise
179 -- ASSERT: if we just created the file, then fdToHandle' won't fail
180 -- (so we don't need to worry about removing the newly created file
181 -- in the event of an error).
184 -- ---------------------------------------------------------------------------
185 -- Converting file descriptors to Handles
190 -> FilePath -- a string describing this file descriptor (e.g. the filename)
192 -> Bool -- non_blocking (*sets* non-blocking mode on the FD)
193 -> Maybe TextEncoding
196 mkHandleFromFD fd0 fd_type filepath iomode set_non_blocking mb_codec
198 #ifndef mingw32_HOST_OS
199 -- turn on non-blocking mode
200 fd <- if set_non_blocking
201 then FD.setNonBlockingMode fd0 True
204 let _ = set_non_blocking -- warning suppression
208 let nl | isJust mb_codec = nativeNewlineMode
209 | otherwise = noNewlineTranslation
213 ioException (IOError Nothing InappropriateType "openFile"
214 "is a directory" Nothing Nothing)
217 -- only *Streams* can be DuplexHandles. Other read/write
218 -- Handles must share a buffer.
219 | ReadWriteMode <- iomode ->
220 mkDuplexHandle fd filepath mb_codec nl
224 mkFileHandle fd filepath iomode mb_codec nl
226 -- | Old API kept to avoid breaking clients
228 -> Maybe IODeviceType
229 -> Bool -- is_socket on Win, non-blocking on Unix
234 fdToHandle' fdint mb_type is_socket filepath iomode binary = do
235 let mb_stat = case mb_type of
237 -- mkFD will do the stat:
238 Just RegularFile -> Nothing
239 -- no stat required for streams etc.:
240 Just other -> Just (other,0,0)
241 (fd,fd_type) <- FD.mkFD (fromIntegral fdint) iomode mb_stat
244 mkHandleFromFD fd fd_type filepath iomode is_socket
245 (if binary then Nothing else Just localeEncoding)
248 -- | Turn an existing file descriptor into a Handle. This is used by
249 -- various external libraries to make Handles.
251 -- Makes a binary Handle. This is for historical reasons; it should
252 -- probably be a text Handle with the default encoding and newline
253 -- translation instead.
254 fdToHandle :: Posix.FD -> IO Handle
255 fdToHandle fdint = do
256 iomode <- Posix.fdGetMode (fromIntegral fdint)
257 (fd,fd_type) <- FD.mkFD (fromIntegral fdint) iomode Nothing
259 -- NB. the is_socket flag is False, meaning that:
260 -- on Windows we're guessing this is not a socket (XXX)
262 -- file descriptors that we get from external sources are
263 -- not put into non-blocking mode, becuase that would affect
264 -- other users of the file descriptor
265 let fd_str = "<file descriptor: " ++ show fd ++ ">"
266 mkHandleFromFD fd fd_type fd_str iomode False{-non-block-}
269 -- ---------------------------------------------------------------------------
270 -- Are files opened by default in text or binary mode, if the user doesn't
273 dEFAULT_OPEN_IN_BINARY_MODE :: Bool
274 dEFAULT_OPEN_IN_BINARY_MODE = False