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
88 ClosedHandle -> return ()
89 _other -> closeTextCodecs h_
90 putMVar m (ioe_finalizedHandle fp)
92 -- We have to put the FDs into binary mode on Windows to avoid the newline
93 -- translation that the CRT IO library does.
94 setBinaryMode :: FD -> IO ()
95 #ifdef mingw32_HOST_OS
96 setBinaryMode fd = do _ <- setmode (fdFD fd) True
99 setBinaryMode _ = return ()
102 #ifdef mingw32_HOST_OS
103 foreign import ccall unsafe "__hscore_setmode"
104 setmode :: CInt -> Bool -> IO CInt
107 -- ---------------------------------------------------------------------------
110 -- | The computation 'isEOF' is identical to 'hIsEOF',
111 -- except that it works only on 'stdin'.
116 -- ---------------------------------------------------------------------------
117 -- Opening and Closing Files
119 addFilePathToIOError :: String -> FilePath -> IOException -> IOException
120 addFilePathToIOError fun fp ioe
121 = ioe{ ioe_location = fun, ioe_filename = Just fp }
123 -- | Computation 'openFile' @file mode@ allocates and returns a new, open
124 -- handle to manage the file @file@. It manages input if @mode@
125 -- is 'ReadMode', output if @mode@ is 'WriteMode' or 'AppendMode',
126 -- and both input and output if mode is 'ReadWriteMode'.
128 -- If the file does not exist and it is opened for output, it should be
129 -- created as a new file. If @mode@ is 'WriteMode' and the file
130 -- already exists, then it should be truncated to zero length.
131 -- Some operating systems delete empty files, so there is no guarantee
132 -- that the file will exist following an 'openFile' with @mode@
133 -- 'WriteMode' unless it is subsequently written to successfully.
134 -- The handle is positioned at the end of the file if @mode@ is
135 -- 'AppendMode', and otherwise at the beginning (in which case its
136 -- internal position is 0).
137 -- The initial buffer mode is implementation-dependent.
139 -- This operation may fail with:
141 -- * 'isAlreadyInUseError' if the file is already open and cannot be reopened;
143 -- * 'isDoesNotExistError' if the file does not exist; or
145 -- * 'isPermissionError' if the user does not have permission to open the file.
147 -- Note: if you will be working with files containing binary data, you'll want to
148 -- be using 'openBinaryFile'.
149 openFile :: FilePath -> IOMode -> IO Handle
152 (openFile' fp im dEFAULT_OPEN_IN_BINARY_MODE)
153 (\e -> ioError (addFilePathToIOError "openFile" fp e))
155 -- | Like 'openFile', but open the file in binary mode.
156 -- On Windows, reading a file in text mode (which is the default)
157 -- will translate CRLF to LF, and writing will translate LF to CRLF.
158 -- This is usually what you want with text files. With binary files
159 -- this is undesirable; also, as usual under Microsoft operating systems,
160 -- text mode treats control-Z as EOF. Binary mode turns off all special
161 -- treatment of end-of-line and end-of-file characters.
162 -- (See also 'hSetBinaryMode'.)
164 openBinaryFile :: FilePath -> IOMode -> IO Handle
165 openBinaryFile fp m =
167 (openFile' fp m True)
168 (\e -> ioError (addFilePathToIOError "openBinaryFile" fp e))
170 openFile' :: String -> IOMode -> Bool -> IO Handle
171 openFile' filepath iomode binary = do
172 -- first open the file to get an FD
173 (fd, fd_type) <- FD.openFile filepath iomode
175 let mb_codec = if binary then Nothing else Just localeEncoding
177 -- then use it to make a Handle
178 mkHandleFromFD fd fd_type filepath iomode True{-non-blocking-} mb_codec
179 `onException` IODevice.close fd
180 -- NB. don't forget to close the FD if mkHandleFromFD fails, otherwise
182 -- ASSERT: if we just created the file, then fdToHandle' won't fail
183 -- (so we don't need to worry about removing the newly created file
184 -- in the event of an error).
187 -- ---------------------------------------------------------------------------
188 -- Converting file descriptors to Handles
193 -> FilePath -- a string describing this file descriptor (e.g. the filename)
195 -> Bool -- non_blocking (*sets* non-blocking mode on the FD)
196 -> Maybe TextEncoding
199 mkHandleFromFD fd0 fd_type filepath iomode set_non_blocking mb_codec
201 #ifndef mingw32_HOST_OS
202 -- turn on non-blocking mode
203 fd <- if set_non_blocking
204 then FD.setNonBlockingMode fd0 True
207 let _ = set_non_blocking -- warning suppression
211 let nl | isJust mb_codec = nativeNewlineMode
212 | otherwise = noNewlineTranslation
216 ioException (IOError Nothing InappropriateType "openFile"
217 "is a directory" Nothing Nothing)
220 -- only *Streams* can be DuplexHandles. Other read/write
221 -- Handles must share a buffer.
222 | ReadWriteMode <- iomode ->
223 mkDuplexHandle fd filepath mb_codec nl
227 mkFileHandle fd filepath iomode mb_codec nl
229 -- | Old API kept to avoid breaking clients
231 -> Maybe IODeviceType
232 -> Bool -- is_socket on Win, non-blocking on Unix
237 fdToHandle' fdint mb_type is_socket filepath iomode binary = do
238 let mb_stat = case mb_type of
240 -- mkFD will do the stat:
241 Just RegularFile -> Nothing
242 -- no stat required for streams etc.:
243 Just other -> Just (other,0,0)
244 (fd,fd_type) <- FD.mkFD (fromIntegral fdint) iomode mb_stat
247 mkHandleFromFD fd fd_type filepath iomode is_socket
248 (if binary then Nothing else Just localeEncoding)
251 -- | Turn an existing file descriptor into a Handle. This is used by
252 -- various external libraries to make Handles.
254 -- Makes a binary Handle. This is for historical reasons; it should
255 -- probably be a text Handle with the default encoding and newline
256 -- translation instead.
257 fdToHandle :: Posix.FD -> IO Handle
258 fdToHandle fdint = do
259 iomode <- Posix.fdGetMode (fromIntegral fdint)
260 (fd,fd_type) <- FD.mkFD (fromIntegral fdint) iomode Nothing
262 -- NB. the is_socket flag is False, meaning that:
263 -- on Windows we're guessing this is not a socket (XXX)
265 -- file descriptors that we get from external sources are
266 -- not put into non-blocking mode, becuase that would affect
267 -- other users of the file descriptor
268 let fd_str = "<file descriptor: " ++ show fd ++ ">"
269 mkHandleFromFD fd fd_type fd_str iomode False{-non-block-}
272 -- ---------------------------------------------------------------------------
273 -- Are files opened by default in text or binary mode, if the user doesn't
276 dEFAULT_OPEN_IN_BINARY_MODE :: Bool
277 dEFAULT_OPEN_IN_BINARY_MODE = False