1 {-# OPTIONS -fno-implicit-prelude #-}
6 -- -----------------------------------------------------------------------------
7 -- $Id: PrelHandle.hsc,v 1.10 2001/06/22 12:36:33 rrt 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,
21 ioe_closedHandle, ioe_EOF, ioe_notReadable, ioe_notWritable,
23 stdin, stdout, stderr,
24 IOMode(..), IOModeEx(..), openFile, openFileEx, openFd,
25 hClose, hFileSize, hIsEOF, isEOF, hLookAhead, hSetBuffering, hSetBinaryMode,
28 HandlePosn(..), hGetPosn, hSetPosn,
31 hIsOpen, hIsClosed, hIsReadable, hIsWritable, hGetBuffering, hIsSeekable,
32 hSetEcho, hGetEcho, hIsTerminalDevice,
33 ioeGetFileName, ioeGetErrorString, ioeGetHandle,
41 #include "cbits/HsStd.h"
47 import PrelMarshalUtils
56 import PrelRead ( Read )
59 import PrelMaybe ( Maybe(..) )
62 import PrelNum ( Integer(..), Num(..) )
64 import PrelReal ( toInteger )
68 -- -----------------------------------------------------------------------------
71 -- hWaitForInput blocks (should use a timeout)
73 -- unbuffered hGetLine is a bit dodgy
75 -- hSetBuffering: can't change buffering on a stream,
76 -- when the read buffer is non-empty? (no way to flush the buffer)
78 -- ---------------------------------------------------------------------------
79 -- Are files opened by default in text or binary mode, if the user doesn't
81 dEFAULT_OPEN_IN_BINARY_MODE :: Bool
82 dEFAULT_OPEN_IN_BINARY_MODE = False
84 -- Is seeking on text-mode handles allowed, or not?
85 tEXT_MODE_SEEK_ALLOWED :: Bool
86 #if defined(mingw32_TARGET_OS)
87 tEXT_MODE_SEEK_ALLOWED = False
89 tEXT_MODE_SEEK_ALLOWED = True
93 -- ---------------------------------------------------------------------------
94 -- Creating a new handle
96 newFileHandle :: (MVar Handle__ -> IO ()) -> Handle__ -> IO Handle
97 newFileHandle finalizer hc = do
99 addMVarFinalizer m (finalizer m)
100 return (FileHandle m)
102 -- ---------------------------------------------------------------------------
103 -- Working with Handles
106 In the concurrent world, handles are locked during use. This is done
107 by wrapping an MVar around the handle which acts as a mutex over
108 operations on the handle.
110 To avoid races, we use the following bracketing operations. The idea
111 is to obtain the lock, do some operation and replace the lock again,
112 whether the operation succeeded or failed. We also want to handle the
113 case where the thread receives an exception while processing the IO
114 operation: in these cases we also want to relinquish the lock.
116 There are three versions of @withHandle@: corresponding to the three
117 possible combinations of:
119 - the operation may side-effect the handle
120 - the operation may return a result
122 If the operation generates an error or an exception is raised, the
123 original handle is always replaced [ this is the case at the moment,
124 but we might want to revisit this in the future --SDM ].
127 {-# INLINE withHandle #-}
128 withHandle :: String -> Handle -> (Handle__ -> IO (Handle__,a)) -> IO a
129 withHandle fun h@(FileHandle m) act = withHandle' fun h m act
130 withHandle fun h@(DuplexHandle r w) act = do
131 withHandle' fun h r act
132 withHandle' fun h w act
134 withHandle' fun h m act =
137 checkBufferInvariants h_
138 (h',v) <- catchException (act h_)
139 (\ ex -> putMVar m h_ >> throw (augmentIOError ex fun h h_))
140 checkBufferInvariants h'
144 {-# INLINE withHandle_ #-}
145 withHandle_ :: String -> Handle -> (Handle__ -> IO a) -> IO a
146 withHandle_ fun h@(FileHandle m) act = withHandle_' fun h m act
147 withHandle_ fun h@(DuplexHandle m _) act = withHandle_' fun h m act
149 withHandle_' fun h m act =
152 checkBufferInvariants h_
153 v <- catchException (act h_)
154 (\ ex -> putMVar m h_ >> throw (augmentIOError ex fun h h_))
155 checkBufferInvariants h_
159 withAllHandles__ :: String -> Handle -> (Handle__ -> IO Handle__) -> IO ()
160 withAllHandles__ fun h@(FileHandle m) act = withHandle__' fun h m act
161 withAllHandles__ fun h@(DuplexHandle r w) act = do
162 withHandle__' fun h r act
163 withHandle__' fun h w act
165 withHandle__' fun h m act =
168 checkBufferInvariants h_
169 h' <- catchException (act h_)
170 (\ ex -> putMVar m h_ >> throw (augmentIOError ex fun h h_))
171 checkBufferInvariants h'
175 augmentIOError (IOException (IOError _ iot _ str fp)) fun h h_
176 = IOException (IOError (Just h) iot fun str filepath)
177 where filepath | Just _ <- fp = fp
178 | otherwise = Just (haFilePath h_)
179 augmentIOError other_exception _ _ _
182 -- ---------------------------------------------------------------------------
183 -- Wrapper for write operations.
185 wantWritableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
186 wantWritableHandle fun h@(FileHandle m) act
187 = wantWritableHandle' fun h m act
188 wantWritableHandle fun h@(DuplexHandle _ m) act
189 = wantWritableHandle' fun h m act
190 -- ToDo: in the Duplex case, we don't need to checkWritableHandle
193 :: String -> Handle -> MVar Handle__
194 -> (Handle__ -> IO a) -> IO a
195 wantWritableHandle' fun h m act
196 = withHandle_' fun h m (checkWritableHandle act)
198 checkWritableHandle act handle_
199 = case haType handle_ of
200 ClosedHandle -> ioe_closedHandle
201 SemiClosedHandle -> ioe_closedHandle
202 ReadHandle -> ioe_notWritable
203 ReadWriteHandle -> do
204 let ref = haBuffer handle_
207 if not (bufferIsWritable buf)
208 then do b <- flushReadBuffer (haFD handle_) buf
209 return b{ bufState=WriteBuffer }
211 writeIORef ref new_buf
213 _other -> act handle_
215 -- ---------------------------------------------------------------------------
216 -- Wrapper for read operations.
218 wantReadableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
219 wantReadableHandle fun h@(FileHandle m) act
220 = wantReadableHandle' fun h m act
221 wantReadableHandle fun h@(DuplexHandle m _) act
222 = wantReadableHandle' fun h m act
223 -- ToDo: in the Duplex case, we don't need to checkReadableHandle
226 :: String -> Handle -> MVar Handle__
227 -> (Handle__ -> IO a) -> IO a
228 wantReadableHandle' fun h m act
229 = withHandle_' fun h m (checkReadableHandle act)
231 checkReadableHandle act handle_ =
232 case haType handle_ of
233 ClosedHandle -> ioe_closedHandle
234 SemiClosedHandle -> ioe_closedHandle
235 AppendHandle -> ioe_notReadable
236 WriteHandle -> ioe_notReadable
237 ReadWriteHandle -> do
238 let ref = haBuffer handle_
240 when (bufferIsWritable buf) $ do
241 new_buf <- flushWriteBuffer (haFD handle_) buf
242 writeIORef ref new_buf{ bufState=ReadBuffer }
244 _other -> act handle_
246 -- ---------------------------------------------------------------------------
247 -- Wrapper for seek operations.
249 wantSeekableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
250 wantSeekableHandle fun h@(DuplexHandle _ _) _act =
251 ioException (IOError (Just h) IllegalOperation fun
252 "handle is not seekable" Nothing)
253 wantSeekableHandle fun h@(FileHandle m) act =
254 withHandle_' fun h m (checkSeekableHandle act)
256 checkSeekableHandle act handle_ =
257 case haType handle_ of
258 ClosedHandle -> ioe_closedHandle
259 SemiClosedHandle -> ioe_closedHandle
260 AppendHandle -> ioe_notSeekable
261 _ | haIsBin handle_ || tEXT_MODE_SEEK_ALLOWED -> act handle_
262 | otherwise -> ioe_notSeekable_notBin
264 -- -----------------------------------------------------------------------------
267 ioe_closedHandle, ioe_EOF,
268 ioe_notReadable, ioe_notWritable,
269 ioe_notSeekable, ioe_notSeekable_notBin :: IO a
271 ioe_closedHandle = ioException
272 (IOError Nothing IllegalOperation ""
273 "handle is closed" Nothing)
274 ioe_EOF = ioException
275 (IOError Nothing EOF "" "" Nothing)
276 ioe_notReadable = ioException
277 (IOError Nothing IllegalOperation ""
278 "handle is not open for reading" Nothing)
279 ioe_notWritable = ioException
280 (IOError Nothing IllegalOperation ""
281 "handle is not open for writing" Nothing)
282 ioe_notSeekable = ioException
283 (IOError Nothing IllegalOperation ""
284 "handle is not seekable" Nothing)
285 ioe_notSeekable_notBin = ioException
286 (IOError Nothing IllegalOperation ""
287 "seek operations on text-mode handles are not allowed on this platform"
290 ioe_bufsiz :: Int -> IO a
291 ioe_bufsiz n = ioException
292 (IOError Nothing InvalidArgument "hSetBuffering"
293 ("illegal buffer size " ++ showsPrec 9 n []) Nothing)
294 -- 9 => should be parens'ified.
296 -- -----------------------------------------------------------------------------
299 -- For a duplex handle, we arrange that the read side points to the write side
300 -- (and hence keeps it alive if the read side is alive). This is done by
301 -- having the haType field of the read side be ReadSideHandle with a pointer
302 -- to the write side. The finalizer is then placed on the write side, and
303 -- the handle only gets finalized once, when both sides are no longer
306 addFinalizer :: Handle -> IO ()
307 addFinalizer (FileHandle m) = addMVarFinalizer m (handleFinalizer m)
308 addFinalizer (DuplexHandle _ w) = addMVarFinalizer w (handleFinalizer w)
310 stdHandleFinalizer :: MVar Handle__ -> IO ()
311 stdHandleFinalizer m = do
313 flushWriteBufferOnly h_
315 handleFinalizer :: MVar Handle__ -> IO ()
316 handleFinalizer m = do
318 flushWriteBufferOnly h_
319 let fd = fromIntegral (haFD h_)
321 -- ToDo: closesocket() for a WINSOCK socket?
322 when (fd /= -1) (c_close fd >> return ())
325 -- ---------------------------------------------------------------------------
326 -- Grimy buffer operations
329 checkBufferInvariants h_ = do
330 let ref = haBuffer h_
331 Buffer{ bufWPtr=w, bufRPtr=r, bufSize=size, bufState=state } <- readIORef ref
336 && ( r /= w || (r == 0 && w == 0) )
337 && ( state /= WriteBuffer || r == 0 )
338 && ( state /= WriteBuffer || w < size ) -- write buffer is never full
340 then error "buffer invariant violation"
343 checkBufferInvariants h_ = return ()
346 newEmptyBuffer :: RawBuffer -> BufferState -> Int -> Buffer
347 newEmptyBuffer b state size
348 = Buffer{ bufBuf=b, bufRPtr=0, bufWPtr=0, bufSize=size, bufState=state }
350 allocateBuffer :: Int -> BufferState -> IO Buffer
351 allocateBuffer sz@(I## size) state = IO $ \s ->
352 case newByteArray## size s of { (## s, b ##) ->
353 (## s, newEmptyBuffer b state sz ##) }
355 writeCharIntoBuffer :: RawBuffer -> Int -> Char -> IO Int
356 writeCharIntoBuffer slab (I## off) (C## c)
357 = IO $ \s -> case writeCharArray## slab off c s of
358 s -> (## s, I## (off +## 1##) ##)
360 readCharFromBuffer :: RawBuffer -> Int -> IO (Char, Int)
361 readCharFromBuffer slab (I## off)
362 = IO $ \s -> case readCharArray## slab off s of
363 (## s, c ##) -> (## s, (C## c, I## (off +## 1##)) ##)
365 dEFAULT_BUFFER_SIZE = (#const BUFSIZ) :: Int
367 getBuffer :: FD -> BufferState -> IO (IORef Buffer, BufferMode)
368 getBuffer fd state = do
369 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE state
370 ioref <- newIORef buffer
374 | is_tty = LineBuffering
375 | otherwise = BlockBuffering Nothing
377 return (ioref, buffer_mode)
379 mkUnBuffer :: IO (IORef Buffer)
381 buffer <- allocateBuffer 1 ReadBuffer
384 -- flushWriteBufferOnly flushes the buffer iff it contains pending write data.
385 flushWriteBufferOnly :: Handle__ -> IO ()
386 flushWriteBufferOnly h_ = do
390 new_buf <- if bufferIsWritable buf
391 then flushWriteBuffer fd buf
393 writeIORef ref new_buf
395 -- flushBuffer syncs the file with the buffer, including moving the
396 -- file pointer backwards in the case of a read buffer.
397 flushBuffer :: Handle__ -> IO ()
399 let ref = haBuffer h_
404 ReadBuffer -> flushReadBuffer (haFD h_) buf
405 WriteBuffer -> flushWriteBuffer (haFD h_) buf
407 writeIORef ref flushed_buf
409 -- When flushing a read buffer, we seek backwards by the number of
410 -- characters in the buffer. The file descriptor must therefore be
411 -- seekable: attempting to flush the read buffer on an unseekable
412 -- handle is not allowed.
414 flushReadBuffer :: FD -> Buffer -> IO Buffer
415 flushReadBuffer fd buf
416 | bufferEmpty buf = return buf
418 let off = negate (bufWPtr buf - bufRPtr buf)
420 puts ("flushReadBuffer: new file offset = " ++ show off ++ "\n")
422 throwErrnoIfMinus1Retry "flushReadBuffer"
423 (c_lseek (fromIntegral fd) (fromIntegral off) (#const SEEK_CUR))
424 return buf{ bufWPtr=0, bufRPtr=0 }
426 flushWriteBuffer :: FD -> Buffer -> IO Buffer
427 flushWriteBuffer fd buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w } = do
430 puts ("flushWriteBuffer, fd=" ++ show fd ++ ", bytes=" ++ show bytes ++ "\n")
433 then return (buf{ bufRPtr=0, bufWPtr=0 })
435 res <- throwErrnoIfMinus1RetryMayBlock "flushWriteBuffer"
436 (write_off (fromIntegral fd) b (fromIntegral r)
437 (fromIntegral bytes))
439 let res' = fromIntegral res
441 then flushWriteBuffer fd (buf{ bufRPtr = r + res' })
442 else return buf{ bufRPtr=0, bufWPtr=0 }
444 foreign import "write_wrap" unsafe
445 write_off :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
447 int write_wrap(int fd, void *ptr, HsInt off, int size) \
448 { return write(fd, ptr + off, size); }
451 fillReadBuffer :: FD -> Bool -> Buffer -> IO Buffer
452 fillReadBuffer fd is_line
453 buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w, bufSize=size } =
454 -- buffer better be empty:
455 assert (r == 0 && w == 0) $ do
456 fillReadBufferLoop fd is_line buf b w size
458 -- For a line buffer, we just get the first chunk of data to arrive,
459 -- and don't wait for the whole buffer to be full (but we *do* wait
460 -- until some data arrives). This isn't really line buffering, but it
461 -- appears to be what GHC has done for a long time, and I suspect it
462 -- is more useful than line buffering in most cases.
464 fillReadBufferLoop fd is_line buf b w size = do
466 if bytes == 0 -- buffer full?
467 then return buf{ bufRPtr=0, bufWPtr=w }
470 puts ("fillReadBufferLoop: bytes = " ++ show bytes ++ "\n")
472 res <- throwErrnoIfMinus1RetryMayBlock "fillReadBuffer"
473 (read_off fd b (fromIntegral w) (fromIntegral bytes))
475 let res' = fromIntegral res
477 puts ("fillReadBufferLoop: res' = " ++ show res' ++ "\n")
482 else return buf{ bufRPtr=0, bufWPtr=w }
483 else if res' < bytes && not is_line
484 then fillReadBufferLoop fd is_line buf b (w+res') size
485 else return buf{ bufRPtr=0, bufWPtr=w+res' }
487 foreign import "read_wrap" unsafe
488 read_off :: FD -> RawBuffer -> Int -> CInt -> IO CInt
490 int read_wrap(int fd, void *ptr, HsInt off, int size) \
491 { return read(fd, ptr + off, size); }
493 -- ---------------------------------------------------------------------------
496 -- Three handles are allocated during program initialisation. The first
497 -- two manage input or output from the Haskell program's standard input
498 -- or output channel respectively. The third manages output to the
499 -- standard error channel. These handles are initially open.
506 stdin = unsafePerformIO $ do
507 -- ToDo: acquire lock
508 setNonBlockingFD fd_stdin
509 (buf, bmode) <- getBuffer fd_stdin ReadBuffer
510 spares <- newIORef BufferListNil
511 newFileHandle stdHandleFinalizer
512 (Handle__ { haFD = fd_stdin,
514 haIsBin = dEFAULT_OPEN_IN_BINARY_MODE,
515 haBufferMode = bmode,
516 haFilePath = "<stdin>",
522 stdout = unsafePerformIO $ do
523 -- ToDo: acquire lock
524 -- We don't set non-blocking mode on stdout or sterr, because
525 -- some shells don't recover properly.
526 -- setNonBlockingFD fd_stdout
527 (buf, bmode) <- getBuffer fd_stdout WriteBuffer
528 spares <- newIORef BufferListNil
529 newFileHandle stdHandleFinalizer
530 (Handle__ { haFD = fd_stdout,
531 haType = WriteHandle,
532 haIsBin = dEFAULT_OPEN_IN_BINARY_MODE,
533 haBufferMode = bmode,
534 haFilePath = "<stdout>",
540 stderr = unsafePerformIO $ do
541 -- ToDo: acquire lock
542 -- We don't set non-blocking mode on stdout or sterr, because
543 -- some shells don't recover properly.
544 -- setNonBlockingFD fd_stderr
546 spares <- newIORef BufferListNil
547 newFileHandle stdHandleFinalizer
548 (Handle__ { haFD = fd_stderr,
549 haType = WriteHandle,
550 haIsBin = dEFAULT_OPEN_IN_BINARY_MODE,
551 haBufferMode = NoBuffering,
552 haFilePath = "<stderr>",
557 -- ---------------------------------------------------------------------------
558 -- Opening and Closing Files
561 Computation `openFile file mode' allocates and returns a new, open
562 handle to manage the file `file'. It manages input if `mode'
563 is `ReadMode', output if `mode' is `WriteMode' or `AppendMode',
564 and both input and output if mode is `ReadWriteMode'.
566 If the file does not exist and it is opened for output, it should be
567 created as a new file. If `mode' is `WriteMode' and the file
568 already exists, then it should be truncated to zero length. The
569 handle is positioned at the end of the file if `mode' is
570 `AppendMode', and otherwise at the beginning (in which case its
571 internal position is 0).
573 Implementations should enforce, locally to the Haskell process,
574 multiple-reader single-writer locking on files, which is to say that
575 there may either be many handles on the same file which manage input,
576 or just one handle on the file which manages output. If any open or
577 semi-closed handle is managing a file for output, no new handle can be
578 allocated for that file. If any open or semi-closed handle is
579 managing a file for input, new handles can only be allocated if they
580 do not manage output.
582 Two files are the same if they have the same absolute name. An
583 implementation is free to impose stricter conditions.
586 data IOMode = ReadMode | WriteMode | AppendMode | ReadWriteMode
587 deriving (Eq, Ord, Ix, Enum, Read, Show)
592 deriving (Eq, Read, Show)
594 addFilePathToIOError fun fp (IOException (IOError h iot _ str _))
595 = IOException (IOError h iot fun str (Just fp))
596 addFilePathToIOError _ _ other_exception
599 openFile :: FilePath -> IOMode -> IO Handle
602 (openFile' fp (if dEFAULT_OPEN_IN_BINARY_MODE
605 (\e -> throw (addFilePathToIOError "openFile" fp e))
607 openFileEx :: FilePath -> IOModeEx -> IO Handle
611 (\e -> throw (addFilePathToIOError "openFileEx" fp e))
614 openFile' filepath ex_mode =
615 withCString filepath $ \ f ->
620 BinaryMode bmo -> (bmo, True)
621 TextMode tmo -> (tmo, False)
623 oflags1 = case mode of
624 ReadMode -> read_flags
625 WriteMode -> write_flags
626 ReadWriteMode -> rw_flags
627 AppendMode -> append_flags
635 oflags = oflags1 .|. binary_flags
638 -- the old implementation had a complicated series of three opens,
639 -- which is perhaps because we have to be careful not to open
640 -- directories. However, the man pages I've read say that open()
641 -- always returns EISDIR if the file is a directory and was opened
642 -- for writing, so I think we're ok with a single open() here...
643 fd <- fromIntegral `liftM`
644 throwErrnoIfMinus1Retry "openFile"
645 (c_open f (fromIntegral oflags) 0o666)
647 openFd fd filepath mode binary
650 std_flags = o_NONBLOCK .|. o_NOCTTY
651 output_flags = std_flags .|. o_CREAT
652 read_flags = std_flags .|. o_RDONLY
653 write_flags = output_flags .|. o_WRONLY .|. o_TRUNC
654 rw_flags = output_flags .|. o_RDWR
655 append_flags = output_flags .|. o_WRONLY .|. o_APPEND
657 -- ---------------------------------------------------------------------------
660 openFd :: FD -> FilePath -> IOMode -> Bool -> IO Handle
661 openFd fd filepath mode binary = do
662 -- turn on non-blocking mode
665 let (ha_type, write) =
667 ReadMode -> ( ReadHandle, False )
668 WriteMode -> ( WriteHandle, True )
669 ReadWriteMode -> ( ReadWriteHandle, True )
670 AppendMode -> ( AppendHandle, True )
672 -- open() won't tell us if it was a directory if we only opened for
673 -- reading, so check again.
677 ioException (IOError Nothing InappropriateType "openFile"
678 "is a directory" Nothing)
681 | ReadWriteHandle <- ha_type -> mkDuplexHandle fd filepath binary
682 | otherwise -> mkFileHandle fd filepath ha_type binary
684 -- regular files need to be locked
686 r <- lockFile (fromIntegral fd) (fromBool write) 1{-exclusive-}
688 ioException (IOError Nothing ResourceBusy "openFile"
689 "file is locked" Nothing)
690 mkFileHandle fd filepath ha_type binary
693 foreign import "lockFile" unsafe
694 lockFile :: CInt -> CInt -> CInt -> IO CInt
696 foreign import "unlockFile" unsafe
697 unlockFile :: CInt -> IO CInt
699 mkFileHandle :: FD -> FilePath -> HandleType -> Bool -> IO Handle
700 mkFileHandle fd filepath ha_type binary = do
701 (buf, bmode) <- getBuffer fd (initBufferState ha_type)
702 spares <- newIORef BufferListNil
703 newFileHandle handleFinalizer
704 (Handle__ { haFD = fd,
707 haBufferMode = bmode,
708 haFilePath = filepath,
713 mkDuplexHandle :: FD -> FilePath -> Bool -> IO Handle
714 mkDuplexHandle fd filepath binary = do
715 (w_buf, w_bmode) <- getBuffer fd WriteBuffer
716 w_spares <- newIORef BufferListNil
718 Handle__ { haFD = fd,
719 haType = WriteHandle,
721 haBufferMode = w_bmode,
722 haFilePath = filepath,
726 write_side <- newMVar w_handle_
728 (r_buf, r_bmode) <- getBuffer fd ReadBuffer
729 r_spares <- newIORef BufferListNil
731 Handle__ { haFD = fd,
732 haType = ReadSideHandle write_side,
734 haBufferMode = r_bmode,
735 haFilePath = filepath,
739 read_side <- newMVar r_handle_
741 addMVarFinalizer write_side (handleFinalizer write_side)
742 return (DuplexHandle read_side write_side)
745 initBufferState ReadHandle = ReadBuffer
746 initBufferState _ = WriteBuffer
748 -- ---------------------------------------------------------------------------
751 -- Computation `hClose hdl' makes handle `hdl' closed. Before the
752 -- computation finishes, any items buffered for output and not already
753 -- sent to the operating system are flushed as for `hFlush'.
755 -- For a duplex handle, we close&flush the write side, and just close
758 hClose :: Handle -> IO ()
759 hClose h@(FileHandle m) = hClose' h m
760 hClose h@(DuplexHandle r w) = do
762 withHandle__' "hClose" h r $ \ handle_ -> do
763 return handle_{ haFD = -1,
764 haType = ClosedHandle
768 withHandle__' "hClose" h m $ \ handle_ -> do
769 case haType handle_ of
770 ClosedHandle -> return handle_
772 let fd = fromIntegral (haFD handle_)
773 flushWriteBufferOnly handle_
774 throwErrnoIfMinus1Retry_ "hClose" (c_close fd)
776 -- free the spare buffers
777 writeIORef (haBuffers handle_) BufferListNil
782 -- we must set the fd to -1, because the finalizer is going
783 -- to run eventually and try to close/unlock it.
784 return (handle_{ haFD = -1,
785 haType = ClosedHandle
788 -----------------------------------------------------------------------------
789 -- Detecting the size of a file
791 -- For a handle `hdl' which attached to a physical file, `hFileSize
792 -- hdl' returns the size of `hdl' in terms of the number of items
793 -- which can be read from `hdl'.
795 hFileSize :: Handle -> IO Integer
797 withHandle_ "hFileSize" handle $ \ handle_ -> do
798 case haType handle_ of
799 ClosedHandle -> ioe_closedHandle
800 SemiClosedHandle -> ioe_closedHandle
801 _ -> do flushWriteBufferOnly handle_
802 r <- fdFileSize (haFD handle_)
805 else ioException (IOError Nothing InappropriateType "hFileSize"
806 "not a regular file" Nothing)
808 -- ---------------------------------------------------------------------------
809 -- Detecting the End of Input
811 -- For a readable handle `hdl', `hIsEOF hdl' returns
812 -- `True' if no further input can be taken from `hdl' or for a
813 -- physical file, if the current I/O position is equal to the length of
814 -- the file. Otherwise, it returns `False'.
816 hIsEOF :: Handle -> IO Bool
819 (do hLookAhead handle; return False)
820 (\e -> if isEOFError e then return True else throw e)
825 -- ---------------------------------------------------------------------------
828 -- hLookahead returns the next character from the handle without
829 -- removing it from the input buffer, blocking until a character is
832 hLookAhead :: Handle -> IO Char
833 hLookAhead handle = do
834 wantReadableHandle "hLookAhead" handle $ \handle_ -> do
835 let ref = haBuffer handle_
837 is_line = haBufferMode handle_ == LineBuffering
840 -- fill up the read buffer if necessary
841 new_buf <- if bufferEmpty buf
842 then fillReadBuffer fd is_line buf
845 writeIORef ref new_buf
847 (c,_) <- readCharFromBuffer (bufBuf buf) (bufRPtr buf)
850 -- ---------------------------------------------------------------------------
851 -- Buffering Operations
853 -- Three kinds of buffering are supported: line-buffering,
854 -- block-buffering or no-buffering. See PrelIOBase for definition and
855 -- further explanation of what the type represent.
857 -- Computation `hSetBuffering hdl mode' sets the mode of buffering for
858 -- handle hdl on subsequent reads and writes.
860 -- * If mode is LineBuffering, line-buffering should be enabled if possible.
862 -- * If mode is `BlockBuffering size', then block-buffering
863 -- should be enabled if possible. The size of the buffer is n items
864 -- if size is `Just n' and is otherwise implementation-dependent.
866 -- * If mode is NoBuffering, then buffering is disabled if possible.
868 -- If the buffer mode is changed from BlockBuffering or
869 -- LineBuffering to NoBuffering, then any items in the output
870 -- buffer are written to the device, and any items in the input buffer
871 -- are discarded. The default buffering mode when a handle is opened
872 -- is implementation-dependent and may depend on the object which is
873 -- attached to that handle.
875 hSetBuffering :: Handle -> BufferMode -> IO ()
876 hSetBuffering handle mode =
877 withAllHandles__ "hSetBuffering" handle $ \ handle_ -> do
878 case haType handle_ of
879 ClosedHandle -> ioe_closedHandle
882 - we flush the old buffer regardless of whether
883 the new buffer could fit the contents of the old buffer
885 - allow a handle's buffering to change even if IO has
886 occurred (ANSI C spec. does not allow this, nor did
887 the previous implementation of IO.hSetBuffering).
888 - a non-standard extension is to allow the buffering
889 of semi-closed handles to change [sof 6/98]
893 let state = initBufferState (haType handle_)
896 -- we always have a 1-character read buffer for
897 -- unbuffered handles: it's needed to
898 -- support hLookAhead.
899 NoBuffering -> allocateBuffer 1 ReadBuffer
900 LineBuffering -> allocateBuffer dEFAULT_BUFFER_SIZE state
901 BlockBuffering Nothing -> allocateBuffer dEFAULT_BUFFER_SIZE state
902 BlockBuffering (Just n) | n <= 0 -> ioe_bufsiz n
903 | otherwise -> allocateBuffer n state
904 writeIORef (haBuffer handle_) new_buf
906 -- for input terminals we need to put the terminal into
907 -- cooked or raw mode depending on the type of buffering.
908 is_tty <- fdIsTTY (haFD handle_)
909 when (is_tty && isReadableHandleType (haType handle_)) $
911 NoBuffering -> setCooked (haFD handle_) False
912 _ -> setCooked (haFD handle_) True
914 -- throw away spare buffers, they might be the wrong size
915 writeIORef (haBuffers handle_) BufferListNil
917 return (handle_{ haBufferMode = mode })
919 -- -----------------------------------------------------------------------------
922 -- The action `hFlush hdl' causes any items buffered for output
923 -- in handle `hdl' to be sent immediately to the operating
926 hFlush :: Handle -> IO ()
928 wantWritableHandle "hFlush" handle $ \ handle_ -> do
929 buf <- readIORef (haBuffer handle_)
930 if bufferIsWritable buf && not (bufferEmpty buf)
931 then do flushed_buf <- flushWriteBuffer (haFD handle_) buf
932 writeIORef (haBuffer handle_) flushed_buf
936 -- -----------------------------------------------------------------------------
937 -- Repositioning Handles
939 data HandlePosn = HandlePosn Handle HandlePosition
941 instance Eq HandlePosn where
942 (HandlePosn h1 p1) == (HandlePosn h2 p2) = p1==p2 && h1==h2
944 -- HandlePosition is the Haskell equivalent of POSIX' off_t.
945 -- We represent it as an Integer on the Haskell side, but
946 -- cheat slightly in that hGetPosn calls upon a C helper
947 -- that reports the position back via (merely) an Int.
948 type HandlePosition = Integer
950 -- Computation `hGetPosn hdl' returns the current I/O position of
951 -- `hdl' as an abstract position. Computation `hSetPosn p' sets the
952 -- position of `hdl' to a previously obtained position `p'.
954 hGetPosn :: Handle -> IO HandlePosn
956 wantSeekableHandle "hGetPosn" handle $ \ handle_ -> do
959 -- urgh, on Windows we have to worry about \n -> \r\n translation,
960 -- so we can't easily calculate the file position using the
961 -- current buffer size. Just flush instead.
964 let fd = fromIntegral (haFD handle_)
965 posn <- fromIntegral `liftM`
966 throwErrnoIfMinus1Retry "hGetPosn"
967 (c_lseek fd 0 (#const SEEK_CUR))
969 let ref = haBuffer handle_
973 | bufferIsWritable buf = posn + fromIntegral (bufWPtr buf)
974 | otherwise = posn - fromIntegral (bufWPtr buf - bufRPtr buf)
976 puts ("\nhGetPosn: (fd, posn, real_posn) = " ++ show (fd, posn, real_posn) ++ "\n")
977 puts (" (bufWPtr, bufRPtr) = " ++ show (bufWPtr buf, bufRPtr buf) ++ "\n")
979 return (HandlePosn handle real_posn)
982 hSetPosn :: HandlePosn -> IO ()
983 hSetPosn (HandlePosn h i) = hSeek h AbsoluteSeek i
985 -- ---------------------------------------------------------------------------
989 The action `hSeek hdl mode i' sets the position of handle
990 `hdl' depending on `mode'. If `mode' is
992 * AbsoluteSeek - The position of `hdl' is set to `i'.
993 * RelativeSeek - The position of `hdl' is set to offset `i' from
994 the current position.
995 * SeekFromEnd - The position of `hdl' is set to offset `i' from
998 Some handles may not be seekable (see `hIsSeekable'), or only
999 support a subset of the possible positioning operations (e.g. it may
1000 only be possible to seek to the end of a tape, or to a positive
1001 offset from the beginning or current position).
1003 It is not possible to set a negative I/O position, or for a physical
1004 file, an I/O position beyond the current end-of-file.
1007 - when seeking using `SeekFromEnd', positive offsets (>=0) means
1008 seeking at or past EOF.
1010 - we possibly deviate from the report on the issue of seeking within
1011 the buffer and whether to flush it or not. The report isn't exactly
1015 data SeekMode = AbsoluteSeek | RelativeSeek | SeekFromEnd
1016 deriving (Eq, Ord, Ix, Enum, Read, Show)
1018 hSeek :: Handle -> SeekMode -> Integer -> IO ()
1019 hSeek handle mode offset =
1020 wantSeekableHandle "hSeek" handle $ \ handle_ -> do
1022 puts ("hSeek " ++ show (mode,offset) ++ "\n")
1024 let ref = haBuffer handle_
1025 buf <- readIORef ref
1031 throwErrnoIfMinus1Retry_ "hSeek"
1032 (c_lseek (fromIntegral (haFD handle_)) (fromIntegral offset) whence)
1035 whence = case mode of
1036 AbsoluteSeek -> (#const SEEK_SET)
1037 RelativeSeek -> (#const SEEK_CUR)
1038 SeekFromEnd -> (#const SEEK_END)
1040 if bufferIsWritable buf
1041 then do new_buf <- flushWriteBuffer fd buf
1042 writeIORef ref new_buf
1046 if mode == RelativeSeek && offset >= 0 && offset < fromIntegral (w - r)
1047 then writeIORef ref buf{ bufRPtr = r + fromIntegral offset }
1050 new_buf <- flushReadBuffer (haFD handle_) buf
1051 writeIORef ref new_buf
1054 -- -----------------------------------------------------------------------------
1055 -- Handle Properties
1057 -- A number of operations return information about the properties of a
1058 -- handle. Each of these operations returns `True' if the handle has
1059 -- the specified property, and `False' otherwise.
1061 hIsOpen :: Handle -> IO Bool
1063 withHandle_ "hIsOpen" handle $ \ handle_ -> do
1064 case haType handle_ of
1065 ClosedHandle -> return False
1066 SemiClosedHandle -> return False
1069 hIsClosed :: Handle -> IO Bool
1071 withHandle_ "hIsClosed" handle $ \ handle_ -> do
1072 case haType handle_ of
1073 ClosedHandle -> return True
1076 {- not defined, nor exported, but mentioned
1077 here for documentation purposes:
1079 hSemiClosed :: Handle -> IO Bool
1083 return (not (ho || hc))
1086 hIsReadable :: Handle -> IO Bool
1087 hIsReadable (DuplexHandle _ _) = return True
1088 hIsReadable handle =
1089 withHandle_ "hIsReadable" handle $ \ handle_ -> do
1090 case haType handle_ of
1091 ClosedHandle -> ioe_closedHandle
1092 SemiClosedHandle -> ioe_closedHandle
1093 htype -> return (isReadableHandleType htype)
1095 hIsWritable :: Handle -> IO Bool
1096 hIsWritable (DuplexHandle _ _) = return False
1097 hIsWritable handle =
1098 withHandle_ "hIsWritable" handle $ \ handle_ -> do
1099 case haType handle_ of
1100 ClosedHandle -> ioe_closedHandle
1101 SemiClosedHandle -> ioe_closedHandle
1102 htype -> return (isWritableHandleType htype)
1104 -- Querying how a handle buffers its data:
1106 hGetBuffering :: Handle -> IO BufferMode
1107 hGetBuffering handle =
1108 withHandle_ "hGetBuffering" handle $ \ handle_ -> do
1109 case haType handle_ of
1110 ClosedHandle -> ioe_closedHandle
1112 -- We're being non-standard here, and allow the buffering
1113 -- of a semi-closed handle to be queried. -- sof 6/98
1114 return (haBufferMode handle_) -- could be stricter..
1116 hIsSeekable :: Handle -> IO Bool
1117 hIsSeekable handle =
1118 withHandle_ "hIsSeekable" handle $ \ handle_ -> do
1119 case haType handle_ of
1120 ClosedHandle -> ioe_closedHandle
1121 SemiClosedHandle -> ioe_closedHandle
1122 AppendHandle -> return False
1123 _ -> do t <- fdType (haFD handle_)
1124 return (t == RegularFile
1125 && (haIsBin handle_ || tEXT_MODE_SEEK_ALLOWED))
1127 -- -----------------------------------------------------------------------------
1128 -- Changing echo status
1130 -- Non-standard GHC extension is to allow the echoing status
1131 -- of a handles connected to terminals to be reconfigured:
1133 hSetEcho :: Handle -> Bool -> IO ()
1134 hSetEcho handle on = do
1135 isT <- hIsTerminalDevice handle
1139 withHandle_ "hSetEcho" handle $ \ handle_ -> do
1140 case haType handle_ of
1141 ClosedHandle -> ioe_closedHandle
1142 _ -> setEcho (haFD handle_) on
1144 hGetEcho :: Handle -> IO Bool
1145 hGetEcho handle = do
1146 isT <- hIsTerminalDevice handle
1150 withHandle_ "hGetEcho" handle $ \ handle_ -> do
1151 case haType handle_ of
1152 ClosedHandle -> ioe_closedHandle
1153 _ -> getEcho (haFD handle_)
1155 hIsTerminalDevice :: Handle -> IO Bool
1156 hIsTerminalDevice handle = do
1157 withHandle_ "hIsTerminalDevice" handle $ \ handle_ -> do
1158 case haType handle_ of
1159 ClosedHandle -> ioe_closedHandle
1160 _ -> fdIsTTY (haFD handle_)
1162 -- -----------------------------------------------------------------------------
1166 hSetBinaryMode handle bin =
1167 withHandle "hSetBinaryMode" handle $ \ handle_ ->
1168 do let flg | bin = (#const O_BINARY)
1169 | otherwise = (#const O_TEXT)
1170 throwErrnoIfMinus1_ "hSetBinaryMode"
1171 (setmode (fromIntegral (haFD handle_)) flg)
1172 return (handle_{haIsBin=bin}, ())
1174 foreign import "setmode" setmode :: CInt -> CInt -> IO CInt
1176 hSetBinaryMode handle bin =
1177 withHandle "hSetBinaryMode" handle $ \ handle_ ->
1178 return (handle_{haIsBin=bin}, ())
1181 -- -----------------------------------------------------------------------------
1184 -- These three functions are meant to get things out of an IOError.
1186 ioeGetFileName :: IOError -> Maybe FilePath
1187 ioeGetErrorString :: IOError -> String
1188 ioeGetHandle :: IOError -> Maybe Handle
1190 ioeGetHandle (IOException (IOError h _ _ _ _)) = h
1191 ioeGetHandle (UserError _) = Nothing
1192 ioeGetHandle _ = error "IO.ioeGetHandle: not an IO error"
1194 ioeGetErrorString (IOException (IOError _ iot _ _ _)) = show iot
1195 ioeGetErrorString (UserError str) = str
1196 ioeGetErrorString _ = error "IO.ioeGetErrorString: not an IO error"
1198 ioeGetFileName (IOException (IOError _ _ _ _ fn)) = fn
1199 ioeGetFileName (UserError _) = Nothing
1200 ioeGetFileName _ = error "IO.ioeGetFileName: not an IO error"
1202 -- ---------------------------------------------------------------------------
1206 puts :: String -> IO ()
1207 puts s = withCString s $ \cstr -> do c_write 1 cstr (fromIntegral (length s))