1 {-# OPTIONS -fno-implicit-prelude -#include "PrelIOUtils.h" #-}
6 -- -----------------------------------------------------------------------------
7 -- $Id: PrelHandle.hs,v 1.8 2001/12/27 11:30:10 sof Exp $
9 -- (c) The University of Glasgow, 1994-2001
11 -- This module defines the basic operations on I/O "handles".
14 withHandle, withHandle', withHandle_,
15 wantWritableHandle, wantReadableHandle, wantSeekableHandle,
17 newEmptyBuffer, allocateBuffer, readCharFromBuffer, writeCharIntoBuffer,
18 flushWriteBufferOnly, flushWriteBuffer, flushReadBuffer, fillReadBuffer,
19 read_off, read_off_ba,
20 write_off, write_off_ba,
22 ioe_closedHandle, ioe_EOF, ioe_notReadable, ioe_notWritable,
24 stdin, stdout, stderr,
25 IOMode(..), IOModeEx(..), openFile, openFileEx, openFd,
26 hFileSize, hIsEOF, isEOF, hLookAhead, hSetBuffering, hSetBinaryMode,
31 HandlePosn(..), hGetPosn, hSetPosn,
34 hIsOpen, hIsClosed, hIsReadable, hIsWritable, hGetBuffering, hIsSeekable,
35 hSetEcho, hGetEcho, hIsTerminalDevice,
36 ioeGetFileName, ioeGetErrorString, ioeGetHandle,
50 import PrelMarshalUtils
59 import PrelRead ( Read )
62 import PrelMaybe ( Maybe(..) )
65 import PrelNum ( Integer(..), Num(..) )
67 import PrelReal ( toInteger )
71 -- -----------------------------------------------------------------------------
74 -- hWaitForInput blocks (should use a timeout)
76 -- unbuffered hGetLine is a bit dodgy
78 -- hSetBuffering: can't change buffering on a stream,
79 -- when the read buffer is non-empty? (no way to flush the buffer)
81 -- ---------------------------------------------------------------------------
82 -- Are files opened by default in text or binary mode, if the user doesn't
84 dEFAULT_OPEN_IN_BINARY_MODE :: Bool
85 dEFAULT_OPEN_IN_BINARY_MODE = False
87 -- Is seeking on text-mode handles allowed, or not?
88 foreign import ccall "prel_supportsTextMode" unsafe tEXT_MODE_SEEK_ALLOWED :: Bool
90 -- ---------------------------------------------------------------------------
91 -- Creating a new handle
93 newFileHandle :: (MVar Handle__ -> IO ()) -> Handle__ -> IO Handle
94 newFileHandle finalizer hc = do
96 addMVarFinalizer m (finalizer m)
99 -- ---------------------------------------------------------------------------
100 -- Working with Handles
103 In the concurrent world, handles are locked during use. This is done
104 by wrapping an MVar around the handle which acts as a mutex over
105 operations on the handle.
107 To avoid races, we use the following bracketing operations. The idea
108 is to obtain the lock, do some operation and replace the lock again,
109 whether the operation succeeded or failed. We also want to handle the
110 case where the thread receives an exception while processing the IO
111 operation: in these cases we also want to relinquish the lock.
113 There are three versions of @withHandle@: corresponding to the three
114 possible combinations of:
116 - the operation may side-effect the handle
117 - the operation may return a result
119 If the operation generates an error or an exception is raised, the
120 original handle is always replaced [ this is the case at the moment,
121 but we might want to revisit this in the future --SDM ].
124 {-# INLINE withHandle #-}
125 withHandle :: String -> Handle -> (Handle__ -> IO (Handle__,a)) -> IO a
126 withHandle fun h@(FileHandle m) act = withHandle' fun h m act
127 withHandle fun h@(DuplexHandle m _) act = withHandle' fun h m act
129 withHandle' fun h m act =
132 checkBufferInvariants h_
133 (h',v) <- catchException (act h_)
134 (\ ex -> putMVar m h_ >> throw (augmentIOError ex fun h h_))
135 checkBufferInvariants h'
139 {-# INLINE withHandle_ #-}
140 withHandle_ :: String -> Handle -> (Handle__ -> IO a) -> IO a
141 withHandle_ fun h@(FileHandle m) act = withHandle_' fun h m act
142 withHandle_ fun h@(DuplexHandle m _) act = withHandle_' fun h m act
144 withHandle_' fun h m act =
147 checkBufferInvariants h_
148 v <- catchException (act h_)
149 (\ ex -> putMVar m h_ >> throw (augmentIOError ex fun h h_))
150 checkBufferInvariants h_
154 withAllHandles__ :: String -> Handle -> (Handle__ -> IO Handle__) -> IO ()
155 withAllHandles__ fun h@(FileHandle m) act = withHandle__' fun h m act
156 withAllHandles__ fun h@(DuplexHandle r w) act = do
157 withHandle__' fun h r act
158 withHandle__' fun h w act
160 withHandle__' fun h m act =
163 checkBufferInvariants h_
164 h' <- catchException (act h_)
165 (\ ex -> putMVar m h_ >> throw (augmentIOError ex fun h h_))
166 checkBufferInvariants h'
170 augmentIOError (IOException (IOError _ iot _ str fp)) fun h h_
171 = IOException (IOError (Just h) iot fun str filepath)
172 where filepath | Just _ <- fp = fp
173 | otherwise = Just (haFilePath h_)
174 augmentIOError other_exception _ _ _
177 -- ---------------------------------------------------------------------------
178 -- Wrapper for write operations.
180 wantWritableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
181 wantWritableHandle fun h@(FileHandle m) act
182 = wantWritableHandle' fun h m act
183 wantWritableHandle fun h@(DuplexHandle _ m) act
184 = wantWritableHandle' fun h m act
185 -- ToDo: in the Duplex case, we don't need to checkWritableHandle
188 :: String -> Handle -> MVar Handle__
189 -> (Handle__ -> IO a) -> IO a
190 wantWritableHandle' fun h m act
191 = withHandle_' fun h m (checkWritableHandle act)
193 checkWritableHandle act handle_
194 = case haType handle_ of
195 ClosedHandle -> ioe_closedHandle
196 SemiClosedHandle -> ioe_closedHandle
197 ReadHandle -> ioe_notWritable
198 ReadWriteHandle -> do
199 let ref = haBuffer handle_
202 if not (bufferIsWritable buf)
203 then do b <- flushReadBuffer (haFD handle_) buf
204 return b{ bufState=WriteBuffer }
206 writeIORef ref new_buf
208 _other -> act handle_
210 -- ---------------------------------------------------------------------------
211 -- Wrapper for read operations.
213 wantReadableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
214 wantReadableHandle fun h@(FileHandle m) act
215 = wantReadableHandle' fun h m act
216 wantReadableHandle fun h@(DuplexHandle m _) act
217 = wantReadableHandle' fun h m act
218 -- ToDo: in the Duplex case, we don't need to checkReadableHandle
221 :: String -> Handle -> MVar Handle__
222 -> (Handle__ -> IO a) -> IO a
223 wantReadableHandle' fun h m act
224 = withHandle_' fun h m (checkReadableHandle act)
226 checkReadableHandle act handle_ =
227 case haType handle_ of
228 ClosedHandle -> ioe_closedHandle
229 SemiClosedHandle -> ioe_closedHandle
230 AppendHandle -> ioe_notReadable
231 WriteHandle -> ioe_notReadable
232 ReadWriteHandle -> do
233 let ref = haBuffer handle_
235 when (bufferIsWritable buf) $ do
236 new_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
237 writeIORef ref new_buf{ bufState=ReadBuffer }
239 _other -> act handle_
241 -- ---------------------------------------------------------------------------
242 -- Wrapper for seek operations.
244 wantSeekableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
245 wantSeekableHandle fun h@(DuplexHandle _ _) _act =
246 ioException (IOError (Just h) IllegalOperation fun
247 "handle is not seekable" Nothing)
248 wantSeekableHandle fun h@(FileHandle m) act =
249 withHandle_' fun h m (checkSeekableHandle act)
251 checkSeekableHandle act handle_ =
252 case haType handle_ of
253 ClosedHandle -> ioe_closedHandle
254 SemiClosedHandle -> ioe_closedHandle
255 AppendHandle -> ioe_notSeekable
256 _ | haIsBin handle_ || tEXT_MODE_SEEK_ALLOWED -> act handle_
257 | otherwise -> ioe_notSeekable_notBin
259 -- -----------------------------------------------------------------------------
262 ioe_closedHandle, ioe_EOF,
263 ioe_notReadable, ioe_notWritable,
264 ioe_notSeekable, ioe_notSeekable_notBin :: IO a
266 ioe_closedHandle = ioException
267 (IOError Nothing IllegalOperation ""
268 "handle is closed" Nothing)
269 ioe_EOF = ioException
270 (IOError Nothing EOF "" "" Nothing)
271 ioe_notReadable = ioException
272 (IOError Nothing IllegalOperation ""
273 "handle is not open for reading" Nothing)
274 ioe_notWritable = ioException
275 (IOError Nothing IllegalOperation ""
276 "handle is not open for writing" Nothing)
277 ioe_notSeekable = ioException
278 (IOError Nothing IllegalOperation ""
279 "handle is not seekable" Nothing)
280 ioe_notSeekable_notBin = ioException
281 (IOError Nothing IllegalOperation ""
282 "seek operations on text-mode handles are not allowed on this platform"
285 ioe_bufsiz :: Int -> IO a
286 ioe_bufsiz n = ioException
287 (IOError Nothing InvalidArgument "hSetBuffering"
288 ("illegal buffer size " ++ showsPrec 9 n []) Nothing)
289 -- 9 => should be parens'ified.
291 -- -----------------------------------------------------------------------------
294 -- For a duplex handle, we arrange that the read side points to the write side
295 -- (and hence keeps it alive if the read side is alive). This is done by
296 -- having the haOtherSide field of the read side point to the read side.
297 -- The finalizer is then placed on the write side, and the handle only gets
298 -- finalized once, when both sides are no longer required.
300 stdHandleFinalizer :: MVar Handle__ -> IO ()
301 stdHandleFinalizer m = do
303 flushWriteBufferOnly h_
305 handleFinalizer :: MVar Handle__ -> IO ()
306 handleFinalizer m = do
308 flushWriteBufferOnly h_
309 let fd = fromIntegral (haFD h_)
312 #ifdef mingw32_TARGET_OS
313 (closeFd (haIsStream h_) fd >> return ())
315 (c_close fd >> return ())
319 -- ---------------------------------------------------------------------------
320 -- Grimy buffer operations
323 checkBufferInvariants h_ = do
324 let ref = haBuffer h_
325 Buffer{ bufWPtr=w, bufRPtr=r, bufSize=size, bufState=state } <- readIORef ref
330 && ( r /= w || (r == 0 && w == 0) )
331 && ( state /= WriteBuffer || r == 0 )
332 && ( state /= WriteBuffer || w < size ) -- write buffer is never full
334 then error "buffer invariant violation"
337 checkBufferInvariants h_ = return ()
340 newEmptyBuffer :: RawBuffer -> BufferState -> Int -> Buffer
341 newEmptyBuffer b state size
342 = Buffer{ bufBuf=b, bufRPtr=0, bufWPtr=0, bufSize=size, bufState=state }
344 allocateBuffer :: Int -> BufferState -> IO Buffer
345 allocateBuffer sz@(I# size) state = IO $ \s ->
346 case newByteArray# size s of { (# s, b #) ->
347 (# s, newEmptyBuffer b state sz #) }
349 writeCharIntoBuffer :: RawBuffer -> Int -> Char -> IO Int
350 writeCharIntoBuffer slab (I# off) (C# c)
351 = IO $ \s -> case writeCharArray# slab off c s of
352 s -> (# s, I# (off +# 1#) #)
354 readCharFromBuffer :: RawBuffer -> Int -> IO (Char, Int)
355 readCharFromBuffer slab (I# off)
356 = IO $ \s -> case readCharArray# slab off s of
357 (# s, c #) -> (# s, (C# c, I# (off +# 1#)) #)
359 getBuffer :: FD -> BufferState -> IO (IORef Buffer, BufferMode)
360 getBuffer fd state = do
361 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE state
362 ioref <- newIORef buffer
366 | is_tty = LineBuffering
367 | otherwise = BlockBuffering Nothing
369 return (ioref, buffer_mode)
371 mkUnBuffer :: IO (IORef Buffer)
373 buffer <- allocateBuffer 1 ReadBuffer
376 -- flushWriteBufferOnly flushes the buffer iff it contains pending write data.
377 flushWriteBufferOnly :: Handle__ -> IO ()
378 flushWriteBufferOnly h_ = do
382 new_buf <- if bufferIsWritable buf
383 then flushWriteBuffer fd (haIsStream h_) buf
385 writeIORef ref new_buf
387 -- flushBuffer syncs the file with the buffer, including moving the
388 -- file pointer backwards in the case of a read buffer.
389 flushBuffer :: Handle__ -> IO ()
391 let ref = haBuffer h_
396 ReadBuffer -> flushReadBuffer (haFD h_) buf
397 WriteBuffer -> flushWriteBuffer (haFD h_) (haIsStream h_) buf
399 writeIORef ref flushed_buf
401 -- When flushing a read buffer, we seek backwards by the number of
402 -- characters in the buffer. The file descriptor must therefore be
403 -- seekable: attempting to flush the read buffer on an unseekable
404 -- handle is not allowed.
406 flushReadBuffer :: FD -> Buffer -> IO Buffer
407 flushReadBuffer fd buf
408 | bufferEmpty buf = return buf
410 let off = negate (bufWPtr buf - bufRPtr buf)
412 puts ("flushReadBuffer: new file offset = " ++ show off ++ "\n")
414 throwErrnoIfMinus1Retry "flushReadBuffer"
415 (c_lseek (fromIntegral fd) (fromIntegral off) sEEK_CUR)
416 return buf{ bufWPtr=0, bufRPtr=0 }
418 flushWriteBuffer :: FD -> Bool -> Buffer -> IO Buffer
419 flushWriteBuffer fd is_stream buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w } = do
422 puts ("flushWriteBuffer, fd=" ++ show fd ++ ", bytes=" ++ show bytes ++ "\n")
425 then return (buf{ bufRPtr=0, bufWPtr=0 })
427 res <- throwErrnoIfMinus1RetryMayBlock "flushWriteBuffer"
428 (write_off_ba (fromIntegral fd) is_stream b (fromIntegral r)
429 (fromIntegral bytes))
431 let res' = fromIntegral res
433 then flushWriteBuffer fd is_stream (buf{ bufRPtr = r + res' })
434 else return buf{ bufRPtr=0, bufWPtr=0 }
436 foreign import "prel_PrelHandle_write" unsafe
437 write_off_ba :: CInt -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
439 foreign import "prel_PrelHandle_write" unsafe
440 write_off :: CInt -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
442 fillReadBuffer :: FD -> Bool -> Bool -> Buffer -> IO Buffer
443 fillReadBuffer fd is_line is_stream
444 buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w, bufSize=size } =
445 -- buffer better be empty:
446 assert (r == 0 && w == 0) $ do
447 fillReadBufferLoop fd is_line is_stream buf b w size
449 -- For a line buffer, we just get the first chunk of data to arrive,
450 -- and don't wait for the whole buffer to be full (but we *do* wait
451 -- until some data arrives). This isn't really line buffering, but it
452 -- appears to be what GHC has done for a long time, and I suspect it
453 -- is more useful than line buffering in most cases.
455 fillReadBufferLoop fd is_line is_stream buf b w size = do
457 if bytes == 0 -- buffer full?
458 then return buf{ bufRPtr=0, bufWPtr=w }
461 puts ("fillReadBufferLoop: bytes = " ++ show bytes ++ "\n")
463 res <- throwErrnoIfMinus1RetryMayBlock "fillReadBuffer"
464 (read_off_ba fd is_stream b (fromIntegral w) (fromIntegral bytes))
466 let res' = fromIntegral res
468 puts ("fillReadBufferLoop: res' = " ++ show res' ++ "\n")
473 else return buf{ bufRPtr=0, bufWPtr=w }
474 else if res' < bytes && not is_line
475 then fillReadBufferLoop fd is_line is_stream buf b (w+res') size
476 else return buf{ bufRPtr=0, bufWPtr=w+res' }
478 foreign import "prel_PrelHandle_read" unsafe
479 read_off_ba :: FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
481 foreign import "prel_PrelHandle_read" unsafe
482 read_off :: FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
484 -- ---------------------------------------------------------------------------
487 -- Three handles are allocated during program initialisation. The first
488 -- two manage input or output from the Haskell program's standard input
489 -- or output channel respectively. The third manages output to the
490 -- standard error channel. These handles are initially open.
497 stdin = unsafePerformIO $ do
498 -- ToDo: acquire lock
499 setNonBlockingFD fd_stdin
500 (buf, bmode) <- getBuffer fd_stdin ReadBuffer
501 mkStdHandle fd_stdin "<stdin>" ReadHandle buf bmode
504 stdout = unsafePerformIO $ do
505 -- ToDo: acquire lock
506 -- We don't set non-blocking mode on stdout or sterr, because
507 -- some shells don't recover properly.
508 -- setNonBlockingFD fd_stdout
509 (buf, bmode) <- getBuffer fd_stdout WriteBuffer
510 mkStdHandle fd_stdout "<stdout>" WriteHandle buf bmode
513 stderr = unsafePerformIO $ do
514 -- ToDo: acquire lock
515 -- We don't set non-blocking mode on stdout or sterr, because
516 -- some shells don't recover properly.
517 -- setNonBlockingFD fd_stderr
519 mkStdHandle fd_stderr "<stderr>" WriteHandle buf NoBuffering
521 -- ---------------------------------------------------------------------------
522 -- Opening and Closing Files
525 Computation `openFile file mode' allocates and returns a new, open
526 handle to manage the file `file'. It manages input if `mode'
527 is `ReadMode', output if `mode' is `WriteMode' or `AppendMode',
528 and both input and output if mode is `ReadWriteMode'.
530 If the file does not exist and it is opened for output, it should be
531 created as a new file. If `mode' is `WriteMode' and the file
532 already exists, then it should be truncated to zero length. The
533 handle is positioned at the end of the file if `mode' is
534 `AppendMode', and otherwise at the beginning (in which case its
535 internal position is 0).
537 Implementations should enforce, locally to the Haskell process,
538 multiple-reader single-writer locking on files, which is to say that
539 there may either be many handles on the same file which manage input,
540 or just one handle on the file which manages output. If any open or
541 semi-closed handle is managing a file for output, no new handle can be
542 allocated for that file. If any open or semi-closed handle is
543 managing a file for input, new handles can only be allocated if they
544 do not manage output.
546 Two files are the same if they have the same absolute name. An
547 implementation is free to impose stricter conditions.
550 data IOMode = ReadMode | WriteMode | AppendMode | ReadWriteMode
551 deriving (Eq, Ord, Ix, Enum, Read, Show)
556 deriving (Eq, Read, Show)
558 addFilePathToIOError fun fp (IOException (IOError h iot _ str _))
559 = IOException (IOError h iot fun str (Just fp))
560 addFilePathToIOError _ _ other_exception
563 openFile :: FilePath -> IOMode -> IO Handle
566 (openFile' fp (if dEFAULT_OPEN_IN_BINARY_MODE
569 (\e -> throw (addFilePathToIOError "openFile" fp e))
571 openFileEx :: FilePath -> IOModeEx -> IO Handle
575 (\e -> throw (addFilePathToIOError "openFileEx" fp e))
578 openFile' filepath ex_mode =
579 withCString filepath $ \ f ->
584 BinaryMode bmo -> (bmo, True)
585 TextMode tmo -> (tmo, False)
587 oflags1 = case mode of
588 ReadMode -> read_flags
589 WriteMode -> write_flags
590 ReadWriteMode -> rw_flags
591 AppendMode -> append_flags
593 truncate | WriteMode <- mode = True
597 | binary = o_BINARY -- is '0' if not supported.
600 oflags = oflags1 .|. binary_flags
603 -- the old implementation had a complicated series of three opens,
604 -- which is perhaps because we have to be careful not to open
605 -- directories. However, the man pages I've read say that open()
606 -- always returns EISDIR if the file is a directory and was opened
607 -- for writing, so I think we're ok with a single open() here...
608 fd <- fromIntegral `liftM`
609 throwErrnoIfMinus1Retry "openFile"
610 (c_open f (fromIntegral oflags) 0o666)
612 openFd fd Nothing filepath mode binary truncate
613 -- ASSERT: if we just created the file, then openFd won't fail
614 -- (so we don't need to worry about removing the newly created file
615 -- in the event of an error).
618 std_flags = o_NONBLOCK .|. o_NOCTTY
619 output_flags = std_flags .|. o_CREAT
620 read_flags = std_flags .|. o_RDONLY
621 write_flags = output_flags .|. o_WRONLY
622 rw_flags = output_flags .|. o_RDWR
623 append_flags = write_flags .|. o_APPEND
625 -- ---------------------------------------------------------------------------
628 openFd :: FD -> Maybe FDType -> FilePath -> IOMode -> Bool -> Bool -> IO Handle
629 openFd fd mb_fd_type filepath mode binary truncate = do
630 -- turn on non-blocking mode
633 let (ha_type, write) =
635 ReadMode -> ( ReadHandle, False )
636 WriteMode -> ( WriteHandle, True )
637 ReadWriteMode -> ( ReadWriteHandle, True )
638 AppendMode -> ( AppendHandle, True )
640 -- open() won't tell us if it was a directory if we only opened for
641 -- reading, so check again.
646 let is_stream = fd_type == Stream
649 ioException (IOError Nothing InappropriateType "openFile"
650 "is a directory" Nothing)
653 | ReadWriteHandle <- ha_type -> mkDuplexHandle fd is_stream filepath binary
654 | otherwise -> mkFileHandle fd is_stream filepath ha_type binary
656 -- regular files need to be locked
658 r <- lockFile (fromIntegral fd) (fromBool write) 1{-exclusive-}
660 ioException (IOError Nothing ResourceBusy "openFile"
661 "file is locked" Nothing)
663 -- truncate the file if necessary
664 when truncate (fileTruncate filepath)
666 mkFileHandle fd is_stream filepath ha_type binary
669 foreign import "lockFile" unsafe
670 lockFile :: CInt -> CInt -> CInt -> IO CInt
672 foreign import "unlockFile" unsafe
673 unlockFile :: CInt -> IO CInt
675 mkStdHandle :: FD -> FilePath -> HandleType -> IORef Buffer -> BufferMode
677 mkStdHandle fd filepath ha_type buf bmode = do
678 spares <- newIORef BufferListNil
679 newFileHandle stdHandleFinalizer
680 (Handle__ { haFD = fd,
682 haIsBin = dEFAULT_OPEN_IN_BINARY_MODE,
684 haBufferMode = bmode,
685 haFilePath = filepath,
688 haOtherSide = Nothing
691 mkFileHandle :: FD -> Bool -> FilePath -> HandleType -> Bool -> IO Handle
692 mkFileHandle fd is_stream filepath ha_type binary = do
693 (buf, bmode) <- getBuffer fd (initBufferState ha_type)
694 spares <- newIORef BufferListNil
695 newFileHandle handleFinalizer
696 (Handle__ { haFD = fd,
699 haIsStream = is_stream,
700 haBufferMode = bmode,
701 haFilePath = filepath,
704 haOtherSide = Nothing
707 mkDuplexHandle :: FD -> Bool -> FilePath -> Bool -> IO Handle
708 mkDuplexHandle fd is_stream filepath binary = do
709 (w_buf, w_bmode) <- getBuffer fd WriteBuffer
710 w_spares <- newIORef BufferListNil
712 Handle__ { haFD = fd,
713 haType = WriteHandle,
715 haIsStream = is_stream,
716 haBufferMode = w_bmode,
717 haFilePath = filepath,
719 haBuffers = w_spares,
720 haOtherSide = Nothing
722 write_side <- newMVar w_handle_
724 (r_buf, r_bmode) <- getBuffer fd ReadBuffer
725 r_spares <- newIORef BufferListNil
727 Handle__ { haFD = fd,
730 haIsStream = is_stream,
731 haBufferMode = r_bmode,
732 haFilePath = filepath,
734 haBuffers = r_spares,
735 haOtherSide = Just write_side
737 read_side <- newMVar r_handle_
739 addMVarFinalizer read_side (handleFinalizer read_side)
740 return (DuplexHandle read_side write_side)
743 initBufferState ReadHandle = ReadBuffer
744 initBufferState _ = WriteBuffer
746 -- ---------------------------------------------------------------------------
749 -- Computation `hClose hdl' makes handle `hdl' closed. Before the
750 -- computation finishes, any items buffered for output and not already
751 -- sent to the operating system are flushed as for `hFlush'.
753 -- For a duplex handle, we close&flush the write side, and just close
756 hClose :: Handle -> IO ()
757 hClose h@(FileHandle m) = hClose' h m
758 hClose h@(DuplexHandle r w) = hClose' h w >> hClose' h r
760 hClose' h m = withHandle__' "hClose" h m $ hClose_help
762 -- hClose_help is also called by lazyRead (in PrelIO) when EOF is read
763 -- or an IO error occurs on a lazy stream. The semi-closed Handle is
764 -- then closed immediately. We have to be careful with DuplexHandles
765 -- though: we have to leave the closing to the finalizer in that case,
766 -- because the write side may still be in use.
767 hClose_help handle_ =
768 case haType handle_ of
769 ClosedHandle -> return handle_
771 let fd = fromIntegral (haFD handle_)
772 flushWriteBufferOnly handle_
774 -- close the file descriptor, but not when this is the read side
775 -- of a duplex handle.
776 case haOtherSide handle_ of
777 Nothing -> throwErrnoIfMinus1Retry_ "hClose"
778 #ifdef mingw32_TARGET_OS
779 (closeFd (haIsStream handle_) fd)
785 -- free the spare buffers
786 writeIORef (haBuffers handle_) BufferListNil
791 -- we must set the fd to -1, because the finalizer is going
792 -- to run eventually and try to close/unlock it.
793 return (handle_{ haFD = -1,
794 haType = ClosedHandle
797 -----------------------------------------------------------------------------
798 -- Detecting the size of a file
800 -- For a handle `hdl' which attached to a physical file, `hFileSize
801 -- hdl' returns the size of `hdl' in terms of the number of items
802 -- which can be read from `hdl'.
804 hFileSize :: Handle -> IO Integer
806 withHandle_ "hFileSize" handle $ \ handle_ -> do
807 case haType handle_ of
808 ClosedHandle -> ioe_closedHandle
809 SemiClosedHandle -> ioe_closedHandle
810 _ -> do flushWriteBufferOnly handle_
811 r <- fdFileSize (haFD handle_)
814 else ioException (IOError Nothing InappropriateType "hFileSize"
815 "not a regular file" Nothing)
817 -- ---------------------------------------------------------------------------
818 -- Detecting the End of Input
820 -- For a readable handle `hdl', `hIsEOF hdl' returns
821 -- `True' if no further input can be taken from `hdl' or for a
822 -- physical file, if the current I/O position is equal to the length of
823 -- the file. Otherwise, it returns `False'.
825 hIsEOF :: Handle -> IO Bool
828 (do hLookAhead handle; return False)
829 (\e -> if isEOFError e then return True else throw e)
834 -- ---------------------------------------------------------------------------
837 -- hLookahead returns the next character from the handle without
838 -- removing it from the input buffer, blocking until a character is
841 hLookAhead :: Handle -> IO Char
842 hLookAhead handle = do
843 wantReadableHandle "hLookAhead" handle $ \handle_ -> do
844 let ref = haBuffer handle_
846 is_line = haBufferMode handle_ == LineBuffering
849 -- fill up the read buffer if necessary
850 new_buf <- if bufferEmpty buf
851 then fillReadBuffer fd is_line (haIsStream handle_) buf
854 writeIORef ref new_buf
856 (c,_) <- readCharFromBuffer (bufBuf buf) (bufRPtr buf)
859 -- ---------------------------------------------------------------------------
860 -- Buffering Operations
862 -- Three kinds of buffering are supported: line-buffering,
863 -- block-buffering or no-buffering. See PrelIOBase for definition and
864 -- further explanation of what the type represent.
866 -- Computation `hSetBuffering hdl mode' sets the mode of buffering for
867 -- handle hdl on subsequent reads and writes.
869 -- * If mode is LineBuffering, line-buffering should be enabled if possible.
871 -- * If mode is `BlockBuffering size', then block-buffering
872 -- should be enabled if possible. The size of the buffer is n items
873 -- if size is `Just n' and is otherwise implementation-dependent.
875 -- * If mode is NoBuffering, then buffering is disabled if possible.
877 -- If the buffer mode is changed from BlockBuffering or
878 -- LineBuffering to NoBuffering, then any items in the output
879 -- buffer are written to the device, and any items in the input buffer
880 -- are discarded. The default buffering mode when a handle is opened
881 -- is implementation-dependent and may depend on the object which is
882 -- attached to that handle.
884 hSetBuffering :: Handle -> BufferMode -> IO ()
885 hSetBuffering handle mode =
886 withAllHandles__ "hSetBuffering" handle $ \ handle_ -> do
887 case haType handle_ of
888 ClosedHandle -> ioe_closedHandle
891 - we flush the old buffer regardless of whether
892 the new buffer could fit the contents of the old buffer
894 - allow a handle's buffering to change even if IO has
895 occurred (ANSI C spec. does not allow this, nor did
896 the previous implementation of IO.hSetBuffering).
897 - a non-standard extension is to allow the buffering
898 of semi-closed handles to change [sof 6/98]
902 let state = initBufferState (haType handle_)
905 -- we always have a 1-character read buffer for
906 -- unbuffered handles: it's needed to
907 -- support hLookAhead.
908 NoBuffering -> allocateBuffer 1 ReadBuffer
909 LineBuffering -> allocateBuffer dEFAULT_BUFFER_SIZE state
910 BlockBuffering Nothing -> allocateBuffer dEFAULT_BUFFER_SIZE state
911 BlockBuffering (Just n) | n <= 0 -> ioe_bufsiz n
912 | otherwise -> allocateBuffer n state
913 writeIORef (haBuffer handle_) new_buf
915 -- for input terminals we need to put the terminal into
916 -- cooked or raw mode depending on the type of buffering.
917 is_tty <- fdIsTTY (haFD handle_)
918 when (is_tty && isReadableHandleType (haType handle_)) $
920 NoBuffering -> setCooked (haFD handle_) False
921 _ -> setCooked (haFD handle_) True
923 -- throw away spare buffers, they might be the wrong size
924 writeIORef (haBuffers handle_) BufferListNil
926 return (handle_{ haBufferMode = mode })
928 -- -----------------------------------------------------------------------------
931 -- The action `hFlush hdl' causes any items buffered for output
932 -- in handle `hdl' to be sent immediately to the operating
935 hFlush :: Handle -> IO ()
937 wantWritableHandle "hFlush" handle $ \ handle_ -> do
938 buf <- readIORef (haBuffer handle_)
939 if bufferIsWritable buf && not (bufferEmpty buf)
940 then do flushed_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
941 writeIORef (haBuffer handle_) flushed_buf
945 -- -----------------------------------------------------------------------------
946 -- Repositioning Handles
948 data HandlePosn = HandlePosn Handle HandlePosition
950 instance Eq HandlePosn where
951 (HandlePosn h1 p1) == (HandlePosn h2 p2) = p1==p2 && h1==h2
953 instance Show HandlePosn where
954 showsPrec p (HandlePosn h pos) =
955 showsPrec p h . showString " at position " . shows pos
957 -- HandlePosition is the Haskell equivalent of POSIX' off_t.
958 -- We represent it as an Integer on the Haskell side, but
959 -- cheat slightly in that hGetPosn calls upon a C helper
960 -- that reports the position back via (merely) an Int.
961 type HandlePosition = Integer
963 -- Computation `hGetPosn hdl' returns the current I/O position of
964 -- `hdl' as an abstract position. Computation `hSetPosn p' sets the
965 -- position of `hdl' to a previously obtained position `p'.
967 hGetPosn :: Handle -> IO HandlePosn
969 wantSeekableHandle "hGetPosn" handle $ \ handle_ -> do
971 #if defined(mingw32_TARGET_OS)
972 -- urgh, on Windows we have to worry about \n -> \r\n translation,
973 -- so we can't easily calculate the file position using the
974 -- current buffer size. Just flush instead.
977 let fd = fromIntegral (haFD handle_)
978 posn <- fromIntegral `liftM`
979 throwErrnoIfMinus1Retry "hGetPosn"
980 (c_lseek fd 0 sEEK_CUR)
982 let ref = haBuffer handle_
986 | bufferIsWritable buf = posn + fromIntegral (bufWPtr buf)
987 | otherwise = posn - fromIntegral (bufWPtr buf - bufRPtr buf)
989 puts ("\nhGetPosn: (fd, posn, real_posn) = " ++ show (fd, posn, real_posn) ++ "\n")
990 puts (" (bufWPtr, bufRPtr) = " ++ show (bufWPtr buf, bufRPtr buf) ++ "\n")
992 return (HandlePosn handle real_posn)
995 hSetPosn :: HandlePosn -> IO ()
996 hSetPosn (HandlePosn h i) = hSeek h AbsoluteSeek i
998 -- ---------------------------------------------------------------------------
1002 The action `hSeek hdl mode i' sets the position of handle
1003 `hdl' depending on `mode'. If `mode' is
1005 * AbsoluteSeek - The position of `hdl' is set to `i'.
1006 * RelativeSeek - The position of `hdl' is set to offset `i' from
1007 the current position.
1008 * SeekFromEnd - The position of `hdl' is set to offset `i' from
1009 the end of the file.
1011 Some handles may not be seekable (see `hIsSeekable'), or only
1012 support a subset of the possible positioning operations (e.g. it may
1013 only be possible to seek to the end of a tape, or to a positive
1014 offset from the beginning or current position).
1016 It is not possible to set a negative I/O position, or for a physical
1017 file, an I/O position beyond the current end-of-file.
1020 - when seeking using `SeekFromEnd', positive offsets (>=0) means
1021 seeking at or past EOF.
1023 - we possibly deviate from the report on the issue of seeking within
1024 the buffer and whether to flush it or not. The report isn't exactly
1028 data SeekMode = AbsoluteSeek | RelativeSeek | SeekFromEnd
1029 deriving (Eq, Ord, Ix, Enum, Read, Show)
1031 hSeek :: Handle -> SeekMode -> Integer -> IO ()
1032 hSeek handle mode offset =
1033 wantSeekableHandle "hSeek" handle $ \ handle_ -> do
1035 puts ("hSeek " ++ show (mode,offset) ++ "\n")
1037 let ref = haBuffer handle_
1038 buf <- readIORef ref
1044 throwErrnoIfMinus1Retry_ "hSeek"
1045 (c_lseek (fromIntegral (haFD handle_)) (fromIntegral offset) whence)
1048 whence = case mode of
1049 AbsoluteSeek -> sEEK_SET
1050 RelativeSeek -> sEEK_CUR
1051 SeekFromEnd -> sEEK_END
1053 if bufferIsWritable buf
1054 then do new_buf <- flushWriteBuffer fd (haIsStream handle_) buf
1055 writeIORef ref new_buf
1059 if mode == RelativeSeek && offset >= 0 && offset < fromIntegral (w - r)
1060 then writeIORef ref buf{ bufRPtr = r + fromIntegral offset }
1063 new_buf <- flushReadBuffer (haFD handle_) buf
1064 writeIORef ref new_buf
1067 -- -----------------------------------------------------------------------------
1068 -- Handle Properties
1070 -- A number of operations return information about the properties of a
1071 -- handle. Each of these operations returns `True' if the handle has
1072 -- the specified property, and `False' otherwise.
1074 hIsOpen :: Handle -> IO Bool
1076 withHandle_ "hIsOpen" handle $ \ handle_ -> do
1077 case haType handle_ of
1078 ClosedHandle -> return False
1079 SemiClosedHandle -> return False
1082 hIsClosed :: Handle -> IO Bool
1084 withHandle_ "hIsClosed" handle $ \ handle_ -> do
1085 case haType handle_ of
1086 ClosedHandle -> return True
1089 {- not defined, nor exported, but mentioned
1090 here for documentation purposes:
1092 hSemiClosed :: Handle -> IO Bool
1096 return (not (ho || hc))
1099 hIsReadable :: Handle -> IO Bool
1100 hIsReadable (DuplexHandle _ _) = return True
1101 hIsReadable handle =
1102 withHandle_ "hIsReadable" handle $ \ handle_ -> do
1103 case haType handle_ of
1104 ClosedHandle -> ioe_closedHandle
1105 SemiClosedHandle -> ioe_closedHandle
1106 htype -> return (isReadableHandleType htype)
1108 hIsWritable :: Handle -> IO Bool
1109 hIsWritable (DuplexHandle _ _) = return False
1110 hIsWritable handle =
1111 withHandle_ "hIsWritable" handle $ \ handle_ -> do
1112 case haType handle_ of
1113 ClosedHandle -> ioe_closedHandle
1114 SemiClosedHandle -> ioe_closedHandle
1115 htype -> return (isWritableHandleType htype)
1117 -- Querying how a handle buffers its data:
1119 hGetBuffering :: Handle -> IO BufferMode
1120 hGetBuffering handle =
1121 withHandle_ "hGetBuffering" handle $ \ handle_ -> do
1122 case haType handle_ of
1123 ClosedHandle -> ioe_closedHandle
1125 -- We're being non-standard here, and allow the buffering
1126 -- of a semi-closed handle to be queried. -- sof 6/98
1127 return (haBufferMode handle_) -- could be stricter..
1129 hIsSeekable :: Handle -> IO Bool
1130 hIsSeekable handle =
1131 withHandle_ "hIsSeekable" handle $ \ handle_ -> do
1132 case haType handle_ of
1133 ClosedHandle -> ioe_closedHandle
1134 SemiClosedHandle -> ioe_closedHandle
1135 AppendHandle -> return False
1136 _ -> do t <- fdType (haFD handle_)
1137 return (t == RegularFile
1138 && (haIsBin handle_ || tEXT_MODE_SEEK_ALLOWED))
1140 -- -----------------------------------------------------------------------------
1141 -- Changing echo status
1143 -- Non-standard GHC extension is to allow the echoing status
1144 -- of a handles connected to terminals to be reconfigured:
1146 hSetEcho :: Handle -> Bool -> IO ()
1147 hSetEcho handle on = do
1148 isT <- hIsTerminalDevice handle
1152 withHandle_ "hSetEcho" handle $ \ handle_ -> do
1153 case haType handle_ of
1154 ClosedHandle -> ioe_closedHandle
1155 _ -> setEcho (haFD handle_) on
1157 hGetEcho :: Handle -> IO Bool
1158 hGetEcho handle = do
1159 isT <- hIsTerminalDevice handle
1163 withHandle_ "hGetEcho" handle $ \ handle_ -> do
1164 case haType handle_ of
1165 ClosedHandle -> ioe_closedHandle
1166 _ -> getEcho (haFD handle_)
1168 hIsTerminalDevice :: Handle -> IO Bool
1169 hIsTerminalDevice handle = do
1170 withHandle_ "hIsTerminalDevice" handle $ \ handle_ -> do
1171 case haType handle_ of
1172 ClosedHandle -> ioe_closedHandle
1173 _ -> fdIsTTY (haFD handle_)
1175 -- -----------------------------------------------------------------------------
1177 hSetBinaryMode handle bin =
1178 withAllHandles__ "hSetBinaryMode" handle $ \ handle_ ->
1179 do throwErrnoIfMinus1_ "hSetBinaryMode"
1180 (setmode (fromIntegral (haFD handle_)) bin)
1181 return handle_{haIsBin=bin}
1183 foreign import "prel_setmode" setmode :: CInt -> Bool -> IO CInt
1185 -- -----------------------------------------------------------------------------
1188 -- These three functions are meant to get things out of an IOError.
1190 ioeGetFileName :: IOError -> Maybe FilePath
1191 ioeGetErrorString :: IOError -> String
1192 ioeGetHandle :: IOError -> Maybe Handle
1194 ioeGetHandle (IOException (IOError h _ _ _ _)) = h
1195 ioeGetHandle (UserError _) = Nothing
1196 ioeGetHandle _ = error "IO.ioeGetHandle: not an IO error"
1198 ioeGetErrorString (IOException (IOError _ iot _ _ _)) = show iot
1199 ioeGetErrorString (UserError str) = str
1200 ioeGetErrorString _ = error "IO.ioeGetErrorString: not an IO error"
1202 ioeGetFileName (IOException (IOError _ _ _ _ fn)) = fn
1203 ioeGetFileName (UserError _) = Nothing
1204 ioeGetFileName _ = error "IO.ioeGetFileName: not an IO error"
1206 -- ---------------------------------------------------------------------------
1210 puts :: String -> IO ()
1211 puts s = withCString s $ \cstr -> do write_off_ba 1 False cstr 0 (fromIntegral (length s))
1215 -- wrappers to platform-specific constants:
1216 foreign import ccall "prel_bufsiz" unsafe dEFAULT_BUFFER_SIZE :: Int
1217 foreign import ccall "prel_seek_cur" unsafe sEEK_CUR :: CInt
1218 foreign import ccall "prel_seek_set" unsafe sEEK_SET :: CInt
1219 foreign import ccall "prel_seek_end" unsafe sEEK_END :: CInt