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 mkHandle FD.stdin "<stdin>" ReadHandle True (Just localeEncoding)
57 nativeNewlineMode{-translate newlines-}
58 (Just stdHandleFinalizer) Nothing
60 -- | A handle managing output to the Haskell program's standard output channel.
62 stdout = unsafePerformIO $ do
64 mkHandle FD.stdout "<stdout>" WriteHandle True (Just localeEncoding)
65 nativeNewlineMode{-translate newlines-}
66 (Just stdHandleFinalizer) Nothing
68 -- | A handle managing output to the Haskell program's standard error channel.
70 stderr = unsafePerformIO $ do
72 mkHandle FD.stderr "<stderr>" WriteHandle False{-stderr is unbuffered-}
74 nativeNewlineMode{-translate newlines-}
75 (Just stdHandleFinalizer) Nothing
77 stdHandleFinalizer :: FilePath -> MVar Handle__ -> IO ()
78 stdHandleFinalizer fp m = do
81 putMVar m (ioe_finalizedHandle fp)
83 -- ---------------------------------------------------------------------------
86 -- | The computation 'isEOF' is identical to 'hIsEOF',
87 -- except that it works only on 'stdin'.
92 -- ---------------------------------------------------------------------------
93 -- Opening and Closing Files
95 addFilePathToIOError :: String -> FilePath -> IOException -> IOException
96 addFilePathToIOError fun fp ioe
97 = ioe{ ioe_location = fun, ioe_filename = Just fp }
99 -- | Computation 'openFile' @file mode@ allocates and returns a new, open
100 -- handle to manage the file @file@. It manages input if @mode@
101 -- is 'ReadMode', output if @mode@ is 'WriteMode' or 'AppendMode',
102 -- and both input and output if mode is 'ReadWriteMode'.
104 -- If the file does not exist and it is opened for output, it should be
105 -- created as a new file. If @mode@ is 'WriteMode' and the file
106 -- already exists, then it should be truncated to zero length.
107 -- Some operating systems delete empty files, so there is no guarantee
108 -- that the file will exist following an 'openFile' with @mode@
109 -- 'WriteMode' unless it is subsequently written to successfully.
110 -- The handle is positioned at the end of the file if @mode@ is
111 -- 'AppendMode', and otherwise at the beginning (in which case its
112 -- internal position is 0).
113 -- The initial buffer mode is implementation-dependent.
115 -- This operation may fail with:
117 -- * 'isAlreadyInUseError' if the file is already open and cannot be reopened;
119 -- * 'isDoesNotExistError' if the file does not exist; or
121 -- * 'isPermissionError' if the user does not have permission to open the file.
123 -- Note: if you will be working with files containing binary data, you'll want to
124 -- be using 'openBinaryFile'.
125 openFile :: FilePath -> IOMode -> IO Handle
128 (openFile' fp im dEFAULT_OPEN_IN_BINARY_MODE)
129 (\e -> ioError (addFilePathToIOError "openFile" fp e))
131 -- | Like 'openFile', but open the file in binary mode.
132 -- On Windows, reading a file in text mode (which is the default)
133 -- will translate CRLF to LF, and writing will translate LF to CRLF.
134 -- This is usually what you want with text files. With binary files
135 -- this is undesirable; also, as usual under Microsoft operating systems,
136 -- text mode treats control-Z as EOF. Binary mode turns off all special
137 -- treatment of end-of-line and end-of-file characters.
138 -- (See also 'hSetBinaryMode'.)
140 openBinaryFile :: FilePath -> IOMode -> IO Handle
141 openBinaryFile fp m =
143 (openFile' fp m True)
144 (\e -> ioError (addFilePathToIOError "openBinaryFile" fp e))
146 openFile' :: String -> IOMode -> Bool -> IO Handle
147 openFile' filepath iomode binary = do
148 -- first open the file to get an FD
149 (fd, fd_type) <- FD.openFile filepath iomode
151 let mb_codec = if binary then Nothing else Just localeEncoding
153 -- then use it to make a Handle
154 mkHandleFromFD fd fd_type filepath iomode True{-non-blocking-} mb_codec
155 `onException` IODevice.close fd
156 -- NB. don't forget to close the FD if mkHandleFromFD fails, otherwise
158 -- ASSERT: if we just created the file, then fdToHandle' won't fail
159 -- (so we don't need to worry about removing the newly created file
160 -- in the event of an error).
163 -- ---------------------------------------------------------------------------
164 -- Converting file descriptors to Handles
169 -> FilePath -- a string describing this file descriptor (e.g. the filename)
171 -> Bool -- non_blocking (*sets* non-blocking mode on the FD)
172 -> Maybe TextEncoding
175 mkHandleFromFD fd0 fd_type filepath iomode set_non_blocking mb_codec
177 #ifndef mingw32_HOST_OS
178 -- turn on non-blocking mode
179 fd <- if set_non_blocking
180 then FD.setNonBlockingMode fd0 True
183 let _ = set_non_blocking -- warning suppression
187 let nl | isJust mb_codec = nativeNewlineMode
188 | otherwise = noNewlineTranslation
192 ioException (IOError Nothing InappropriateType "openFile"
193 "is a directory" Nothing Nothing)
196 -- only *Streams* can be DuplexHandles. Other read/write
197 -- Handles must share a buffer.
198 | ReadWriteMode <- iomode ->
199 mkDuplexHandle fd filepath mb_codec nl
203 mkFileHandle fd filepath iomode mb_codec nl
205 -- | Old API kept to avoid breaking clients
207 -> Maybe IODeviceType
208 -> Bool -- is_socket on Win, non-blocking on Unix
213 fdToHandle' fdint mb_type is_socket filepath iomode binary = do
214 let mb_stat = case mb_type of
216 -- mkFD will do the stat:
217 Just RegularFile -> Nothing
218 -- no stat required for streams etc.:
219 Just other -> Just (other,0,0)
220 (fd,fd_type) <- FD.mkFD (fromIntegral fdint) iomode mb_stat
223 mkHandleFromFD fd fd_type filepath iomode is_socket
224 (if binary then Nothing else Just localeEncoding)
227 -- | Turn an existing file descriptor into a Handle. This is used by
228 -- various external libraries to make Handles.
230 -- Makes a binary Handle. This is for historical reasons; it should
231 -- probably be a text Handle with the default encoding and newline
232 -- translation instead.
233 fdToHandle :: Posix.FD -> IO Handle
234 fdToHandle fdint = do
235 iomode <- Posix.fdGetMode (fromIntegral fdint)
236 (fd,fd_type) <- FD.mkFD (fromIntegral fdint) iomode Nothing
238 -- NB. the is_socket flag is False, meaning that:
239 -- on Windows we're guessing this is not a socket (XXX)
241 -- file descriptors that we get from external sources are
242 -- not put into non-blocking mode, becuase that would affect
243 -- other users of the file descriptor
244 let fd_str = "<file descriptor: " ++ show fd ++ ">"
245 mkHandleFromFD fd fd_type fd_str iomode False{-non-block-}
248 -- ---------------------------------------------------------------------------
249 -- Are files opened by default in text or binary mode, if the user doesn't
252 dEFAULT_OPEN_IN_BINARY_MODE :: Bool
253 dEFAULT_OPEN_IN_BINARY_MODE = False