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',
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 stdin = unsafePerformIO $ do
56 setBinaryMode FD.stdin
57 mkHandle FD.stdin "<stdin>" ReadHandle True (Just localeEncoding)
58 nativeNewlineMode{-translate newlines-}
59 (Just stdHandleFinalizer) Nothing
61 -- | A handle managing output to the Haskell program's standard output channel.
63 stdout = unsafePerformIO $ do
65 setBinaryMode FD.stdout
66 mkHandle FD.stdout "<stdout>" WriteHandle True (Just localeEncoding)
67 nativeNewlineMode{-translate newlines-}
68 (Just stdHandleFinalizer) Nothing
70 -- | A handle managing output to the Haskell program's standard error channel.
72 stderr = unsafePerformIO $ do
74 setBinaryMode FD.stderr
75 mkHandle FD.stderr "<stderr>" WriteHandle False{-stderr is unbuffered-}
77 nativeNewlineMode{-translate newlines-}
78 (Just stdHandleFinalizer) Nothing
80 stdHandleFinalizer :: FilePath -> MVar Handle__ -> IO ()
81 stdHandleFinalizer fp m = do
84 putMVar m (ioe_finalizedHandle fp)
86 -- We have to put the FDs into binary mode on Windows to avoid the newline
87 -- translation that the CRT IO library does.
88 setBinaryMode :: FD -> IO ()
89 #ifdef mingw32_HOST_OS
90 setBinaryMode fd = do setmode (fdFD fd) True; return ()
92 setBinaryMode _ = return ()
95 #ifdef mingw32_HOST_OS
96 foreign import ccall unsafe "__hscore_setmode"
97 setmode :: CInt -> Bool -> IO CInt
100 -- ---------------------------------------------------------------------------
103 -- | The computation 'isEOF' is identical to 'hIsEOF',
104 -- except that it works only on 'stdin'.
109 -- ---------------------------------------------------------------------------
110 -- Opening and Closing Files
112 addFilePathToIOError :: String -> FilePath -> IOException -> IOException
113 addFilePathToIOError fun fp ioe
114 = ioe{ ioe_location = fun, ioe_filename = Just fp }
116 -- | Computation 'openFile' @file mode@ allocates and returns a new, open
117 -- handle to manage the file @file@. It manages input if @mode@
118 -- is 'ReadMode', output if @mode@ is 'WriteMode' or 'AppendMode',
119 -- and both input and output if mode is 'ReadWriteMode'.
121 -- If the file does not exist and it is opened for output, it should be
122 -- created as a new file. If @mode@ is 'WriteMode' and the file
123 -- already exists, then it should be truncated to zero length.
124 -- Some operating systems delete empty files, so there is no guarantee
125 -- that the file will exist following an 'openFile' with @mode@
126 -- 'WriteMode' unless it is subsequently written to successfully.
127 -- The handle is positioned at the end of the file if @mode@ is
128 -- 'AppendMode', and otherwise at the beginning (in which case its
129 -- internal position is 0).
130 -- The initial buffer mode is implementation-dependent.
132 -- This operation may fail with:
134 -- * 'isAlreadyInUseError' if the file is already open and cannot be reopened;
136 -- * 'isDoesNotExistError' if the file does not exist; or
138 -- * 'isPermissionError' if the user does not have permission to open the file.
140 -- Note: if you will be working with files containing binary data, you'll want to
141 -- be using 'openBinaryFile'.
142 openFile :: FilePath -> IOMode -> IO Handle
145 (openFile' fp im dEFAULT_OPEN_IN_BINARY_MODE)
146 (\e -> ioError (addFilePathToIOError "openFile" fp e))
148 -- | Like 'openFile', but open the file in binary mode.
149 -- On Windows, reading a file in text mode (which is the default)
150 -- will translate CRLF to LF, and writing will translate LF to CRLF.
151 -- This is usually what you want with text files. With binary files
152 -- this is undesirable; also, as usual under Microsoft operating systems,
153 -- text mode treats control-Z as EOF. Binary mode turns off all special
154 -- treatment of end-of-line and end-of-file characters.
155 -- (See also 'hSetBinaryMode'.)
157 openBinaryFile :: FilePath -> IOMode -> IO Handle
158 openBinaryFile fp m =
160 (openFile' fp m True)
161 (\e -> ioError (addFilePathToIOError "openBinaryFile" fp e))
163 openFile' :: String -> IOMode -> Bool -> IO Handle
164 openFile' filepath iomode binary = do
165 -- first open the file to get an FD
166 (fd, fd_type) <- FD.openFile filepath iomode
168 let mb_codec = if binary then Nothing else Just localeEncoding
170 -- then use it to make a Handle
171 mkHandleFromFD fd fd_type filepath iomode True{-non-blocking-} mb_codec
172 `onException` IODevice.close fd
173 -- NB. don't forget to close the FD if mkHandleFromFD fails, otherwise
175 -- ASSERT: if we just created the file, then fdToHandle' won't fail
176 -- (so we don't need to worry about removing the newly created file
177 -- in the event of an error).
180 -- ---------------------------------------------------------------------------
181 -- Converting file descriptors to Handles
186 -> FilePath -- a string describing this file descriptor (e.g. the filename)
188 -> Bool -- non_blocking (*sets* non-blocking mode on the FD)
189 -> Maybe TextEncoding
192 mkHandleFromFD fd0 fd_type filepath iomode set_non_blocking mb_codec
194 #ifndef mingw32_HOST_OS
195 -- turn on non-blocking mode
196 fd <- if set_non_blocking
197 then FD.setNonBlockingMode fd0 True
200 let _ = set_non_blocking -- warning suppression
204 let nl | isJust mb_codec = nativeNewlineMode
205 | otherwise = noNewlineTranslation
209 ioException (IOError Nothing InappropriateType "openFile"
210 "is a directory" Nothing Nothing)
213 -- only *Streams* can be DuplexHandles. Other read/write
214 -- Handles must share a buffer.
215 | ReadWriteMode <- iomode ->
216 mkDuplexHandle fd filepath mb_codec nl
220 mkFileHandle fd filepath iomode mb_codec nl
222 -- | Old API kept to avoid breaking clients
224 -> Maybe IODeviceType
225 -> Bool -- is_socket on Win, non-blocking on Unix
230 fdToHandle' fdint mb_type is_socket filepath iomode binary = do
231 let mb_stat = case mb_type of
233 -- mkFD will do the stat:
234 Just RegularFile -> Nothing
235 -- no stat required for streams etc.:
236 Just other -> Just (other,0,0)
237 (fd,fd_type) <- FD.mkFD (fromIntegral fdint) iomode mb_stat
240 mkHandleFromFD fd fd_type filepath iomode is_socket
241 (if binary then Nothing else Just localeEncoding)
244 -- | Turn an existing file descriptor into a Handle. This is used by
245 -- various external libraries to make Handles.
247 -- Makes a binary Handle. This is for historical reasons; it should
248 -- probably be a text Handle with the default encoding and newline
249 -- translation instead.
250 fdToHandle :: Posix.FD -> IO Handle
251 fdToHandle fdint = do
252 iomode <- Posix.fdGetMode (fromIntegral fdint)
253 (fd,fd_type) <- FD.mkFD (fromIntegral fdint) iomode Nothing
255 -- NB. the is_socket flag is False, meaning that:
256 -- on Windows we're guessing this is not a socket (XXX)
258 -- file descriptors that we get from external sources are
259 -- not put into non-blocking mode, becuase that would affect
260 -- other users of the file descriptor
261 let fd_str = "<file descriptor: " ++ show fd ++ ">"
262 mkHandleFromFD fd fd_type fd_str iomode False{-non-block-}
265 -- ---------------------------------------------------------------------------
266 -- Are files opened by default in text or binary mode, if the user doesn't
269 dEFAULT_OPEN_IN_BINARY_MODE :: Bool
270 dEFAULT_OPEN_IN_BINARY_MODE = False