1 {-# OPTIONS_GHC -fno-implicit-prelude -#include "HsBase.h" #-}
6 -----------------------------------------------------------------------------
9 -- Copyright : (c) The University of Glasgow, 1994-2001
10 -- License : see libraries/base/LICENSE
12 -- Maintainer : libraries@haskell.org
13 -- Stability : internal
14 -- Portability : non-portable
16 -- This module defines the basic operations on I\/O \"handles\".
18 -----------------------------------------------------------------------------
22 withHandle, withHandle', withHandle_,
23 wantWritableHandle, wantReadableHandle, wantSeekableHandle,
25 newEmptyBuffer, allocateBuffer, readCharFromBuffer, writeCharIntoBuffer,
26 flushWriteBufferOnly, flushWriteBuffer, flushReadBuffer,
27 fillReadBuffer, fillReadBufferWithoutBlocking,
28 readRawBuffer, readRawBufferPtr,
29 writeRawBuffer, writeRawBufferPtr,
31 #ifndef mingw32_HOST_OS
35 ioe_closedHandle, ioe_EOF, ioe_notReadable, ioe_notWritable,
37 stdin, stdout, stderr,
38 IOMode(..), openFile, openBinaryFile, openTempFile, openBinaryTempFile, openFd, fdToHandle,
39 hFileSize, hSetFileSize, hIsEOF, isEOF, hLookAhead, hSetBuffering, hSetBinaryMode,
40 hFlush, hDuplicate, hDuplicateTo,
44 HandlePosition, HandlePosn(..), hGetPosn, hSetPosn,
45 SeekMode(..), hSeek, hTell,
47 hIsOpen, hIsClosed, hIsReadable, hIsWritable, hGetBuffering, hIsSeekable,
48 hSetEcho, hGetEcho, hIsTerminalDevice,
58 import System.Directory.Internals
64 import System.IO.Error
65 import System.Posix.Internals
71 import GHC.Read ( Read )
76 import GHC.Num ( Integer(..), Num(..) )
78 import GHC.Real ( toInteger )
79 #if defined(DEBUG_DUMP)
85 -- -----------------------------------------------------------------------------
88 -- hWaitForInput blocks (should use a timeout)
90 -- unbuffered hGetLine is a bit dodgy
92 -- hSetBuffering: can't change buffering on a stream,
93 -- when the read buffer is non-empty? (no way to flush the buffer)
95 -- ---------------------------------------------------------------------------
96 -- Are files opened by default in text or binary mode, if the user doesn't
99 dEFAULT_OPEN_IN_BINARY_MODE = False :: Bool
101 -- ---------------------------------------------------------------------------
102 -- Creating a new handle
104 newFileHandle :: FilePath -> (MVar Handle__ -> IO ()) -> Handle__ -> IO Handle
105 newFileHandle filepath finalizer hc = do
107 addMVarFinalizer m (finalizer m)
108 return (FileHandle filepath m)
110 -- ---------------------------------------------------------------------------
111 -- Working with Handles
114 In the concurrent world, handles are locked during use. This is done
115 by wrapping an MVar around the handle which acts as a mutex over
116 operations on the handle.
118 To avoid races, we use the following bracketing operations. The idea
119 is to obtain the lock, do some operation and replace the lock again,
120 whether the operation succeeded or failed. We also want to handle the
121 case where the thread receives an exception while processing the IO
122 operation: in these cases we also want to relinquish the lock.
124 There are three versions of @withHandle@: corresponding to the three
125 possible combinations of:
127 - the operation may side-effect the handle
128 - the operation may return a result
130 If the operation generates an error or an exception is raised, the
131 original handle is always replaced [ this is the case at the moment,
132 but we might want to revisit this in the future --SDM ].
135 {-# INLINE withHandle #-}
136 withHandle :: String -> Handle -> (Handle__ -> IO (Handle__,a)) -> IO a
137 withHandle fun h@(FileHandle _ m) act = withHandle' fun h m act
138 withHandle fun h@(DuplexHandle _ m _) act = withHandle' fun h m act
140 withHandle' :: String -> Handle -> MVar Handle__
141 -> (Handle__ -> IO (Handle__,a)) -> IO a
142 withHandle' fun h m act =
145 checkBufferInvariants h_
146 (h',v) <- catchException (act h_)
147 (\ err -> putMVar m h_ >>
149 IOException ex -> ioError (augmentIOError ex fun h)
151 checkBufferInvariants h'
155 {-# INLINE withHandle_ #-}
156 withHandle_ :: String -> Handle -> (Handle__ -> IO a) -> IO a
157 withHandle_ fun h@(FileHandle _ m) act = withHandle_' fun h m act
158 withHandle_ fun h@(DuplexHandle _ m _) act = withHandle_' fun h m act
160 withHandle_' fun h m act =
163 checkBufferInvariants h_
164 v <- catchException (act h_)
165 (\ err -> putMVar m h_ >>
167 IOException ex -> ioError (augmentIOError ex fun h)
169 checkBufferInvariants h_
173 withAllHandles__ :: String -> Handle -> (Handle__ -> IO Handle__) -> IO ()
174 withAllHandles__ fun h@(FileHandle _ m) act = withHandle__' fun h m act
175 withAllHandles__ fun h@(DuplexHandle _ r w) act = do
176 withHandle__' fun h r act
177 withHandle__' fun h w act
179 withHandle__' fun h m act =
182 checkBufferInvariants h_
183 h' <- catchException (act h_)
184 (\ err -> putMVar m h_ >>
186 IOException ex -> ioError (augmentIOError ex fun h)
188 checkBufferInvariants h'
192 augmentIOError (IOError _ iot _ str fp) fun h
193 = IOError (Just h) iot fun str filepath
196 | otherwise = case h of
197 FileHandle fp _ -> Just fp
198 DuplexHandle fp _ _ -> Just fp
200 -- ---------------------------------------------------------------------------
201 -- Wrapper for write operations.
203 wantWritableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
204 wantWritableHandle fun h@(FileHandle _ m) act
205 = wantWritableHandle' fun h m act
206 wantWritableHandle fun h@(DuplexHandle _ _ m) act
207 = wantWritableHandle' fun h m act
208 -- ToDo: in the Duplex case, we don't need to checkWritableHandle
211 :: String -> Handle -> MVar Handle__
212 -> (Handle__ -> IO a) -> IO a
213 wantWritableHandle' fun h m act
214 = withHandle_' fun h m (checkWritableHandle act)
216 checkWritableHandle act handle_
217 = case haType handle_ of
218 ClosedHandle -> ioe_closedHandle
219 SemiClosedHandle -> ioe_closedHandle
220 ReadHandle -> ioe_notWritable
221 ReadWriteHandle -> do
222 let ref = haBuffer handle_
225 if not (bufferIsWritable buf)
226 then do b <- flushReadBuffer (haFD handle_) buf
227 return b{ bufState=WriteBuffer }
229 writeIORef ref new_buf
231 _other -> act handle_
233 -- ---------------------------------------------------------------------------
234 -- Wrapper for read operations.
236 wantReadableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
237 wantReadableHandle fun h@(FileHandle _ m) act
238 = wantReadableHandle' fun h m act
239 wantReadableHandle fun h@(DuplexHandle _ m _) act
240 = wantReadableHandle' fun h m act
241 -- ToDo: in the Duplex case, we don't need to checkReadableHandle
244 :: String -> Handle -> MVar Handle__
245 -> (Handle__ -> IO a) -> IO a
246 wantReadableHandle' fun h m act
247 = withHandle_' fun h m (checkReadableHandle act)
249 checkReadableHandle act handle_ =
250 case haType handle_ of
251 ClosedHandle -> ioe_closedHandle
252 SemiClosedHandle -> ioe_closedHandle
253 AppendHandle -> ioe_notReadable
254 WriteHandle -> ioe_notReadable
255 ReadWriteHandle -> do
256 let ref = haBuffer handle_
258 when (bufferIsWritable buf) $ do
259 new_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
260 writeIORef ref new_buf{ bufState=ReadBuffer }
262 _other -> act handle_
264 -- ---------------------------------------------------------------------------
265 -- Wrapper for seek operations.
267 wantSeekableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
268 wantSeekableHandle fun h@(DuplexHandle _ _ _) _act =
269 ioException (IOError (Just h) IllegalOperation fun
270 "handle is not seekable" Nothing)
271 wantSeekableHandle fun h@(FileHandle _ m) act =
272 withHandle_' fun h m (checkSeekableHandle act)
274 checkSeekableHandle act handle_ =
275 case haType handle_ of
276 ClosedHandle -> ioe_closedHandle
277 SemiClosedHandle -> ioe_closedHandle
278 AppendHandle -> ioe_notSeekable
279 _ | haIsBin handle_ || tEXT_MODE_SEEK_ALLOWED -> act handle_
280 | otherwise -> ioe_notSeekable_notBin
282 -- -----------------------------------------------------------------------------
285 ioe_closedHandle, ioe_EOF,
286 ioe_notReadable, ioe_notWritable,
287 ioe_notSeekable, ioe_notSeekable_notBin :: IO a
289 ioe_closedHandle = ioException
290 (IOError Nothing IllegalOperation ""
291 "handle is closed" Nothing)
292 ioe_EOF = ioException
293 (IOError Nothing EOF "" "" Nothing)
294 ioe_notReadable = ioException
295 (IOError Nothing IllegalOperation ""
296 "handle is not open for reading" Nothing)
297 ioe_notWritable = ioException
298 (IOError Nothing IllegalOperation ""
299 "handle is not open for writing" Nothing)
300 ioe_notSeekable = ioException
301 (IOError Nothing IllegalOperation ""
302 "handle is not seekable" Nothing)
303 ioe_notSeekable_notBin = ioException
304 (IOError Nothing IllegalOperation ""
305 "seek operations on text-mode handles are not allowed on this platform"
308 ioe_finalizedHandle fp = throw (IOException
309 (IOError Nothing IllegalOperation ""
310 "handle is finalized" (Just fp)))
312 ioe_bufsiz :: Int -> IO a
313 ioe_bufsiz n = ioException
314 (IOError Nothing InvalidArgument "hSetBuffering"
315 ("illegal buffer size " ++ showsPrec 9 n []) Nothing)
316 -- 9 => should be parens'ified.
318 -- -----------------------------------------------------------------------------
321 -- For a duplex handle, we arrange that the read side points to the write side
322 -- (and hence keeps it alive if the read side is alive). This is done by
323 -- having the haOtherSide field of the read side point to the read side.
324 -- The finalizer is then placed on the write side, and the handle only gets
325 -- finalized once, when both sides are no longer required.
327 -- NOTE about finalized handles: It's possible that a handle can be
328 -- finalized and then we try to use it later, for example if the
329 -- handle is referenced from another finalizer, or from a thread that
330 -- has become unreferenced and then resurrected (arguably in the
331 -- latter case we shouldn't finalize the Handle...). Anyway,
332 -- we try to emit a helpful message which is better than nothing.
334 stdHandleFinalizer :: FilePath -> MVar Handle__ -> IO ()
335 stdHandleFinalizer fp m = do
337 flushWriteBufferOnly h_
338 putMVar m (ioe_finalizedHandle fp)
340 handleFinalizer :: FilePath -> MVar Handle__ -> IO ()
341 handleFinalizer fp m = do
342 handle_ <- takeMVar m
343 case haType handle_ of
344 ClosedHandle -> return ()
345 _ -> do flushWriteBufferOnly handle_ `catchException` \_ -> return ()
346 -- ignore errors and async exceptions, and close the
347 -- descriptor anyway...
348 hClose_handle_ handle_
350 putMVar m (ioe_finalizedHandle fp)
352 -- ---------------------------------------------------------------------------
353 -- Grimy buffer operations
356 checkBufferInvariants h_ = do
357 let ref = haBuffer h_
358 Buffer{ bufWPtr=w, bufRPtr=r, bufSize=size, bufState=state } <- readIORef ref
363 && ( r /= w || (r == 0 && w == 0) )
364 && ( state /= WriteBuffer || r == 0 )
365 && ( state /= WriteBuffer || w < size ) -- write buffer is never full
367 then error "buffer invariant violation"
370 checkBufferInvariants h_ = return ()
373 newEmptyBuffer :: RawBuffer -> BufferState -> Int -> Buffer
374 newEmptyBuffer b state size
375 = Buffer{ bufBuf=b, bufRPtr=0, bufWPtr=0, bufSize=size, bufState=state }
377 allocateBuffer :: Int -> BufferState -> IO Buffer
378 allocateBuffer sz@(I# size) state = IO $ \s ->
379 #ifdef mingw32_HOST_OS
380 -- To implement asynchronous I/O under Win32, we have to pass
381 -- buffer references to external threads that handles the
382 -- filling/emptying of their contents. Hence, the buffer cannot
383 -- be moved around by the GC.
384 case newPinnedByteArray# size s of { (# s, b #) ->
386 case newByteArray# size s of { (# s, b #) ->
388 (# s, newEmptyBuffer b state sz #) }
390 writeCharIntoBuffer :: RawBuffer -> Int -> Char -> IO Int
391 writeCharIntoBuffer slab (I# off) (C# c)
392 = IO $ \s -> case writeCharArray# slab off c s of
393 s -> (# s, I# (off +# 1#) #)
395 readCharFromBuffer :: RawBuffer -> Int -> IO (Char, Int)
396 readCharFromBuffer slab (I# off)
397 = IO $ \s -> case readCharArray# slab off s of
398 (# s, c #) -> (# s, (C# c, I# (off +# 1#)) #)
400 getBuffer :: FD -> BufferState -> IO (IORef Buffer, BufferMode)
401 getBuffer fd state = do
402 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE state
403 ioref <- newIORef buffer
407 | is_tty = LineBuffering
408 | otherwise = BlockBuffering Nothing
410 return (ioref, buffer_mode)
412 mkUnBuffer :: IO (IORef Buffer)
414 buffer <- allocateBuffer 1 ReadBuffer
417 -- flushWriteBufferOnly flushes the buffer iff it contains pending write data.
418 flushWriteBufferOnly :: Handle__ -> IO ()
419 flushWriteBufferOnly h_ = do
423 new_buf <- if bufferIsWritable buf
424 then flushWriteBuffer fd (haIsStream h_) buf
426 writeIORef ref new_buf
428 -- flushBuffer syncs the file with the buffer, including moving the
429 -- file pointer backwards in the case of a read buffer.
430 flushBuffer :: Handle__ -> IO ()
432 let ref = haBuffer h_
437 ReadBuffer -> flushReadBuffer (haFD h_) buf
438 WriteBuffer -> flushWriteBuffer (haFD h_) (haIsStream h_) buf
440 writeIORef ref flushed_buf
442 -- When flushing a read buffer, we seek backwards by the number of
443 -- characters in the buffer. The file descriptor must therefore be
444 -- seekable: attempting to flush the read buffer on an unseekable
445 -- handle is not allowed.
447 flushReadBuffer :: FD -> Buffer -> IO Buffer
448 flushReadBuffer fd buf
449 | bufferEmpty buf = return buf
451 let off = negate (bufWPtr buf - bufRPtr buf)
453 puts ("flushReadBuffer: new file offset = " ++ show off ++ "\n")
455 throwErrnoIfMinus1Retry "flushReadBuffer"
456 (c_lseek (fromIntegral fd) (fromIntegral off) sEEK_CUR)
457 return buf{ bufWPtr=0, bufRPtr=0 }
459 flushWriteBuffer :: FD -> Bool -> Buffer -> IO Buffer
460 flushWriteBuffer fd is_stream buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w } =
461 seq fd $ do -- strictness hack
464 puts ("flushWriteBuffer, fd=" ++ show fd ++ ", bytes=" ++ show bytes ++ "\n")
467 then return (buf{ bufRPtr=0, bufWPtr=0 })
469 res <- writeRawBuffer "flushWriteBuffer" (fromIntegral fd) is_stream b
470 (fromIntegral r) (fromIntegral bytes)
471 let res' = fromIntegral res
473 then flushWriteBuffer fd is_stream (buf{ bufRPtr = r + res' })
474 else return buf{ bufRPtr=0, bufWPtr=0 }
476 fillReadBuffer :: FD -> Bool -> Bool -> Buffer -> IO Buffer
477 fillReadBuffer fd is_line is_stream
478 buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w, bufSize=size } =
479 -- buffer better be empty:
480 assert (r == 0 && w == 0) $ do
481 fillReadBufferLoop fd is_line is_stream buf b w size
483 -- For a line buffer, we just get the first chunk of data to arrive,
484 -- and don't wait for the whole buffer to be full (but we *do* wait
485 -- until some data arrives). This isn't really line buffering, but it
486 -- appears to be what GHC has done for a long time, and I suspect it
487 -- is more useful than line buffering in most cases.
489 fillReadBufferLoop fd is_line is_stream buf b w size = do
491 if bytes == 0 -- buffer full?
492 then return buf{ bufRPtr=0, bufWPtr=w }
495 puts ("fillReadBufferLoop: bytes = " ++ show bytes ++ "\n")
497 res <- readRawBuffer "fillReadBuffer" fd is_stream b
498 (fromIntegral w) (fromIntegral bytes)
499 let res' = fromIntegral res
501 puts ("fillReadBufferLoop: res' = " ++ show res' ++ "\n")
506 else return buf{ bufRPtr=0, bufWPtr=w }
507 else if res' < bytes && not is_line
508 then fillReadBufferLoop fd is_line is_stream buf b (w+res') size
509 else return buf{ bufRPtr=0, bufWPtr=w+res' }
512 fillReadBufferWithoutBlocking :: FD -> Bool -> Buffer -> IO Buffer
513 fillReadBufferWithoutBlocking fd is_stream
514 buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w, bufSize=size } =
515 -- buffer better be empty:
516 assert (r == 0 && w == 0) $ do
518 puts ("fillReadBufferLoopNoBlock: bytes = " ++ show size ++ "\n")
520 res <- readRawBufferNoBlock "fillReadBuffer" fd is_stream b
521 0 (fromIntegral size)
522 let res' = fromIntegral res
524 puts ("fillReadBufferLoopNoBlock: res' = " ++ show res' ++ "\n")
526 return buf{ bufRPtr=0, bufWPtr=res' }
528 -- Low level routines for reading/writing to (raw)buffers:
530 #ifndef mingw32_HOST_OS
531 readRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
532 readRawBuffer loc fd is_stream buf off len =
533 throwErrnoIfMinus1RetryMayBlock loc
534 (read_rawBuffer fd buf off len)
535 (threadWaitRead (fromIntegral fd))
537 readRawBufferNoBlock :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
538 readRawBufferNoBlock loc fd is_stream buf off len =
539 throwErrnoIfMinus1RetryOnBlock loc
540 (read_rawBuffer fd buf off len)
543 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
544 readRawBufferPtr loc fd is_stream buf off len =
545 throwErrnoIfMinus1RetryMayBlock loc
546 (read_off fd buf off len)
547 (threadWaitRead (fromIntegral fd))
549 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
550 writeRawBuffer loc fd is_stream buf off len =
551 throwErrnoIfMinus1RetryMayBlock loc
552 (write_rawBuffer (fromIntegral fd) buf off len)
553 (threadWaitWrite (fromIntegral fd))
555 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
556 writeRawBufferPtr loc fd is_stream buf off len =
557 throwErrnoIfMinus1RetryMayBlock loc
558 (write_off (fromIntegral fd) buf off len)
559 (threadWaitWrite (fromIntegral fd))
561 foreign import ccall unsafe "__hscore_PrelHandle_read"
562 read_rawBuffer :: FD -> RawBuffer -> Int -> CInt -> IO CInt
564 foreign import ccall unsafe "__hscore_PrelHandle_read"
565 read_off :: FD -> Ptr CChar -> Int -> CInt -> IO CInt
567 foreign import ccall unsafe "__hscore_PrelHandle_write"
568 write_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
570 foreign import ccall unsafe "__hscore_PrelHandle_write"
571 write_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
573 #else /* mingw32_HOST_OS.... */
575 readRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
576 readRawBuffer loc fd is_stream buf off len
577 | threaded = blockingReadRawBuffer loc fd is_stream buf off len
578 | otherwise = asyncReadRawBuffer loc fd is_stream buf off len
580 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
581 readRawBufferPtr loc fd is_stream buf off len
582 | threaded = blockingReadRawBufferPtr loc fd is_stream buf off len
583 | otherwise = asyncReadRawBufferPtr loc fd is_stream buf off len
585 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
586 writeRawBuffer loc fd is_stream buf off len
587 | threaded = blockingWriteRawBuffer loc fd is_stream buf off len
588 | otherwise = asyncWriteRawBuffer loc fd is_stream buf off len
590 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
591 writeRawBufferPtr loc fd is_stream buf off len
592 | threaded = blockingWriteRawBufferPtr loc fd is_stream buf off len
593 | otherwise = asyncWriteRawBufferPtr loc fd is_stream buf off len
595 -- ToDo: we don't have a non-blocking primitve read on Win32
596 readRawBufferNoBlock :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
597 readRawBufferNoBlock = readRawBuffer
599 -- Async versions of the read/write primitives, for the non-threaded RTS
601 asyncReadRawBuffer loc fd is_stream buf off len = do
602 (l, rc) <- asyncReadBA fd (if is_stream then 1 else 0)
603 (fromIntegral len) off buf
606 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
607 else return (fromIntegral l)
609 asyncReadRawBufferPtr loc fd is_stream buf off len = do
610 (l, rc) <- asyncRead fd (if is_stream then 1 else 0)
611 (fromIntegral len) (buf `plusPtr` off)
614 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
615 else return (fromIntegral l)
617 asyncWriteRawBuffer loc fd is_stream buf off len = do
618 (l, rc) <- asyncWriteBA fd (if is_stream then 1 else 0)
619 (fromIntegral len) off buf
622 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
623 else return (fromIntegral l)
625 asyncWriteRawBufferPtr loc fd is_stream buf off len = do
626 (l, rc) <- asyncWrite fd (if is_stream then 1 else 0)
627 (fromIntegral len) (buf `plusPtr` off)
630 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
631 else return (fromIntegral l)
633 -- Blocking versions of the read/write primitives, for the threaded RTS
635 blockingReadRawBuffer loc fd True buf off len =
636 throwErrnoIfMinus1Retry loc $
637 recv_rawBuffer fd buf off len
638 blockingReadRawBuffer loc fd False buf off len =
639 throwErrnoIfMinus1Retry loc $
640 read_rawBuffer fd buf off len
642 blockingReadRawBufferPtr loc fd True buf off len =
643 throwErrnoIfMinus1Retry loc $
644 recv_off fd buf off len
645 blockingReadRawBufferPtr loc fd False buf off len =
646 throwErrnoIfMinus1Retry loc $
647 read_off fd buf off len
649 blockingWriteRawBuffer loc fd True buf off len =
650 throwErrnoIfMinus1Retry loc $
651 send_rawBuffer (fromIntegral fd) buf off len
652 blockingWriteRawBuffer loc fd False buf off len =
653 throwErrnoIfMinus1Retry loc $
654 write_rawBuffer (fromIntegral fd) buf off len
656 blockingWriteRawBufferPtr loc fd True buf off len =
657 throwErrnoIfMinus1Retry loc $
658 send_off (fromIntegral fd) buf off len
659 blockingWriteRawBufferPtr loc fd False buf off len =
660 throwErrnoIfMinus1Retry loc $
661 write_off (fromIntegral fd) buf off len
663 -- NOTE: "safe" versions of the read/write calls for use by the threaded RTS.
664 -- These calls may block, but that's ok.
666 foreign import ccall safe "__hscore_PrelHandle_read"
667 read_rawBuffer :: FD -> RawBuffer -> Int -> CInt -> IO CInt
669 foreign import ccall safe "__hscore_PrelHandle_read"
670 read_off :: FD -> Ptr CChar -> Int -> CInt -> IO CInt
672 foreign import ccall safe "__hscore_PrelHandle_write"
673 write_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
675 foreign import ccall safe "__hscore_PrelHandle_write"
676 write_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
678 foreign import ccall safe "__hscore_PrelHandle_recv"
679 recv_rawBuffer :: FD -> RawBuffer -> Int -> CInt -> IO CInt
681 foreign import ccall safe "__hscore_PrelHandle_recv"
682 recv_off :: FD -> Ptr CChar -> Int -> CInt -> IO CInt
684 foreign import ccall safe "__hscore_PrelHandle_send"
685 send_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
687 foreign import ccall safe "__hscore_PrelHandle_send"
688 send_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
690 foreign import ccall "rtsSupportsBoundThreads" threaded :: Bool
693 -- ---------------------------------------------------------------------------
696 -- Three handles are allocated during program initialisation. The first
697 -- two manage input or output from the Haskell program's standard input
698 -- or output channel respectively. The third manages output to the
699 -- standard error channel. These handles are initially open.
705 -- | A handle managing input from the Haskell program's standard input channel.
707 stdin = unsafePerformIO $ do
708 -- ToDo: acquire lock
709 setNonBlockingFD fd_stdin
710 (buf, bmode) <- getBuffer fd_stdin ReadBuffer
711 mkStdHandle fd_stdin "<stdin>" ReadHandle buf bmode
713 -- | A handle managing output to the Haskell program's standard output channel.
715 stdout = unsafePerformIO $ do
716 -- ToDo: acquire lock
717 -- We don't set non-blocking mode on stdout or sterr, because
718 -- some shells don't recover properly.
719 -- setNonBlockingFD fd_stdout
720 (buf, bmode) <- getBuffer fd_stdout WriteBuffer
721 mkStdHandle fd_stdout "<stdout>" WriteHandle buf bmode
723 -- | A handle managing output to the Haskell program's standard error channel.
725 stderr = unsafePerformIO $ do
726 -- ToDo: acquire lock
727 -- We don't set non-blocking mode on stdout or sterr, because
728 -- some shells don't recover properly.
729 -- setNonBlockingFD fd_stderr
731 mkStdHandle fd_stderr "<stderr>" WriteHandle buf NoBuffering
733 -- ---------------------------------------------------------------------------
734 -- Opening and Closing Files
736 addFilePathToIOError fun fp (IOError h iot _ str _)
737 = IOError h iot fun str (Just fp)
739 -- | Computation 'openFile' @file mode@ allocates and returns a new, open
740 -- handle to manage the file @file@. It manages input if @mode@
741 -- is 'ReadMode', output if @mode@ is 'WriteMode' or 'AppendMode',
742 -- and both input and output if mode is 'ReadWriteMode'.
744 -- If the file does not exist and it is opened for output, it should be
745 -- created as a new file. If @mode@ is 'WriteMode' and the file
746 -- already exists, then it should be truncated to zero length.
747 -- Some operating systems delete empty files, so there is no guarantee
748 -- that the file will exist following an 'openFile' with @mode@
749 -- 'WriteMode' unless it is subsequently written to successfully.
750 -- The handle is positioned at the end of the file if @mode@ is
751 -- 'AppendMode', and otherwise at the beginning (in which case its
752 -- internal position is 0).
753 -- The initial buffer mode is implementation-dependent.
755 -- This operation may fail with:
757 -- * 'isAlreadyInUseError' if the file is already open and cannot be reopened;
759 -- * 'isDoesNotExistError' if the file does not exist; or
761 -- * 'isPermissionError' if the user does not have permission to open the file.
763 -- Note: if you will be working with files containing binary data, you'll want to
764 -- be using 'openBinaryFile'.
765 openFile :: FilePath -> IOMode -> IO Handle
768 (openFile' fp im dEFAULT_OPEN_IN_BINARY_MODE)
769 (\e -> ioError (addFilePathToIOError "openFile" fp e))
771 -- | Like 'openFile', but open the file in binary mode.
772 -- On Windows, reading a file in text mode (which is the default)
773 -- will translate CRLF to LF, and writing will translate LF to CRLF.
774 -- This is usually what you want with text files. With binary files
775 -- this is undesirable; also, as usual under Microsoft operating systems,
776 -- text mode treats control-Z as EOF. Binary mode turns off all special
777 -- treatment of end-of-line and end-of-file characters.
778 -- (See also 'hSetBinaryMode'.)
780 openBinaryFile :: FilePath -> IOMode -> IO Handle
781 openBinaryFile fp m =
783 (openFile' fp m True)
784 (\e -> ioError (addFilePathToIOError "openBinaryFile" fp e))
786 openFile' filepath mode binary =
787 withCString filepath $ \ f ->
790 oflags1 = case mode of
791 ReadMode -> read_flags
792 #ifdef mingw32_HOST_OS
793 WriteMode -> write_flags .|. o_TRUNC
795 WriteMode -> write_flags
797 ReadWriteMode -> rw_flags
798 AppendMode -> append_flags
804 oflags = oflags1 .|. binary_flags
807 -- the old implementation had a complicated series of three opens,
808 -- which is perhaps because we have to be careful not to open
809 -- directories. However, the man pages I've read say that open()
810 -- always returns EISDIR if the file is a directory and was opened
811 -- for writing, so I think we're ok with a single open() here...
812 fd <- fromIntegral `liftM`
813 throwErrnoIfMinus1Retry "openFile"
814 (c_open f (fromIntegral oflags) 0o666)
818 h <- openFd fd (Just fd_type) False filepath mode binary
819 `catchException` \e -> do c_close (fromIntegral fd); throw e
820 -- NB. don't forget to close the FD if openFd fails, otherwise
822 -- ASSERT: if we just created the file, then openFd won't fail
823 -- (so we don't need to worry about removing the newly created file
824 -- in the event of an error).
826 #ifndef mingw32_HOST_OS
827 -- we want to truncate() if this is an open in WriteMode, but only
828 -- if the target is a RegularFile. ftruncate() fails on special files
830 if mode == WriteMode && fd_type == RegularFile
831 then throwErrnoIf (/=0) "openFile"
832 (c_ftruncate (fromIntegral fd) 0)
838 -- | The function creates a temporary file in ReadWrite mode.
839 -- The created file isn\'t deleted automatically, so you need to delete it manually.
840 openTempFile :: FilePath -- ^ Directory in which to create the file
841 -> String -- ^ File name template. If the template is \"foo.ext\" then
842 -- the create file will be \"fooXXX.ext\" where XXX is some
844 -> IO (FilePath, Handle)
845 openTempFile tmp_dir template = openTempFile' "openTempFile" tmp_dir template dEFAULT_OPEN_IN_BINARY_MODE
847 -- | Like 'openTempFile', but opens the file in binary mode. See 'openBinaryFile' for more comments.
848 openBinaryTempFile :: FilePath -> String -> IO (FilePath, Handle)
849 openBinaryTempFile tmp_dir template = openTempFile' "openBinaryTempFile" tmp_dir template True
851 openTempFile' :: String -> FilePath -> String -> Bool -> IO (FilePath, Handle)
852 openTempFile' loc tmp_dir template binary = do
856 (prefix,suffix) = break (=='.') template
858 oflags1 = rw_flags .|. o_EXCL
864 oflags = oflags1 .|. binary_flags
867 fd <- withCString filepath $ \ f ->
868 c_open f oflags 0o666
873 then findTempName (x+1)
874 else ioError (errnoToIOError loc errno Nothing (Just tmp_dir))
876 h <- openFd (fromIntegral fd) Nothing False filepath ReadWriteMode True
877 `catchException` \e -> do c_close (fromIntegral fd); throw e
880 filename = prefix ++ show x ++ suffix
881 filepath = tmp_dir `joinFileName` filename
884 std_flags = o_NONBLOCK .|. o_NOCTTY
885 output_flags = std_flags .|. o_CREAT
886 read_flags = std_flags .|. o_RDONLY
887 write_flags = output_flags .|. o_WRONLY
888 rw_flags = output_flags .|. o_RDWR
889 append_flags = write_flags .|. o_APPEND
891 -- ---------------------------------------------------------------------------
894 openFd :: FD -> Maybe FDType -> Bool -> FilePath -> IOMode -> Bool -> IO Handle
895 openFd fd mb_fd_type is_socket filepath mode binary = do
896 -- turn on non-blocking mode
899 let (ha_type, write) =
901 ReadMode -> ( ReadHandle, False )
902 WriteMode -> ( WriteHandle, True )
903 ReadWriteMode -> ( ReadWriteHandle, True )
904 AppendMode -> ( AppendHandle, True )
906 -- open() won't tell us if it was a directory if we only opened for
907 -- reading, so check again.
915 ioException (IOError Nothing InappropriateType "openFile"
916 "is a directory" Nothing)
918 -- regular files need to be locked
920 #ifndef mingw32_HOST_OS
921 r <- lockFile (fromIntegral fd) (fromBool write) 1{-exclusive-}
923 ioException (IOError Nothing ResourceBusy "openFile"
924 "file is locked" Nothing)
926 mkFileHandle fd is_socket filepath ha_type binary
929 -- only *Streams* can be DuplexHandles. Other read/write
930 -- Handles must share a buffer.
931 | ReadWriteHandle <- ha_type ->
932 mkDuplexHandle fd is_socket filepath binary
934 mkFileHandle fd is_socket filepath ha_type binary
937 mkFileHandle fd is_socket filepath ha_type binary
939 fdToHandle :: FD -> IO Handle
942 let fd_str = "<file descriptor: " ++ show fd ++ ">"
943 openFd fd Nothing False{-XXX!-} fd_str mode True{-bin mode-}
946 #ifndef mingw32_HOST_OS
947 foreign import ccall unsafe "lockFile"
948 lockFile :: CInt -> CInt -> CInt -> IO CInt
950 foreign import ccall unsafe "unlockFile"
951 unlockFile :: CInt -> IO CInt
954 mkStdHandle :: FD -> FilePath -> HandleType -> IORef Buffer -> BufferMode
956 mkStdHandle fd filepath ha_type buf bmode = do
957 spares <- newIORef BufferListNil
958 newFileHandle filepath (stdHandleFinalizer filepath)
959 (Handle__ { haFD = fd,
961 haIsBin = dEFAULT_OPEN_IN_BINARY_MODE,
963 haBufferMode = bmode,
966 haOtherSide = Nothing
969 mkFileHandle :: FD -> Bool -> FilePath -> HandleType -> Bool -> IO Handle
970 mkFileHandle fd is_stream filepath ha_type binary = do
971 (buf, bmode) <- getBuffer fd (initBufferState ha_type)
973 #ifdef mingw32_HOST_OS
974 -- On Windows, if this is a read/write handle and we are in text mode,
975 -- turn off buffering. We don't correctly handle the case of switching
976 -- from read mode to write mode on a buffered text-mode handle, see bug
978 bmode <- case ha_type of
979 ReadWriteHandle | not binary -> return NoBuffering
980 _other -> return bmode
983 spares <- newIORef BufferListNil
984 newFileHandle filepath (handleFinalizer filepath)
985 (Handle__ { haFD = fd,
988 haIsStream = is_stream,
989 haBufferMode = bmode,
992 haOtherSide = Nothing
995 mkDuplexHandle :: FD -> Bool -> FilePath -> Bool -> IO Handle
996 mkDuplexHandle fd is_stream filepath binary = do
997 (w_buf, w_bmode) <- getBuffer fd WriteBuffer
998 w_spares <- newIORef BufferListNil
1000 Handle__ { haFD = fd,
1001 haType = WriteHandle,
1003 haIsStream = is_stream,
1004 haBufferMode = w_bmode,
1006 haBuffers = w_spares,
1007 haOtherSide = Nothing
1009 write_side <- newMVar w_handle_
1011 (r_buf, r_bmode) <- getBuffer fd ReadBuffer
1012 r_spares <- newIORef BufferListNil
1014 Handle__ { haFD = fd,
1015 haType = ReadHandle,
1017 haIsStream = is_stream,
1018 haBufferMode = r_bmode,
1020 haBuffers = r_spares,
1021 haOtherSide = Just write_side
1023 read_side <- newMVar r_handle_
1025 addMVarFinalizer write_side (handleFinalizer filepath write_side)
1026 return (DuplexHandle filepath read_side write_side)
1029 initBufferState ReadHandle = ReadBuffer
1030 initBufferState _ = WriteBuffer
1032 -- ---------------------------------------------------------------------------
1035 -- | Computation 'hClose' @hdl@ makes handle @hdl@ closed. Before the
1036 -- computation finishes, if @hdl@ is writable its buffer is flushed as
1038 -- Performing 'hClose' on a handle that has already been closed has no effect;
1039 -- doing so not an error. All other operations on a closed handle will fail.
1040 -- If 'hClose' fails for any reason, any further operations (apart from
1041 -- 'hClose') on the handle will still fail as if @hdl@ had been successfully
1044 hClose :: Handle -> IO ()
1045 hClose h@(FileHandle _ m) = hClose' h m
1046 hClose h@(DuplexHandle _ r w) = hClose' h w >> hClose' h r
1048 hClose' h m = withHandle__' "hClose" h m $ hClose_help
1050 -- hClose_help is also called by lazyRead (in PrelIO) when EOF is read
1051 -- or an IO error occurs on a lazy stream. The semi-closed Handle is
1052 -- then closed immediately. We have to be careful with DuplexHandles
1053 -- though: we have to leave the closing to the finalizer in that case,
1054 -- because the write side may still be in use.
1055 hClose_help :: Handle__ -> IO Handle__
1056 hClose_help handle_ =
1057 case haType handle_ of
1058 ClosedHandle -> return handle_
1059 _ -> do flushWriteBufferOnly handle_ -- interruptible
1060 hClose_handle_ handle_
1062 hClose_handle_ handle_ = do
1063 let fd = haFD handle_
1064 c_fd = fromIntegral fd
1066 -- close the file descriptor, but not when this is the read
1067 -- side of a duplex handle.
1068 case haOtherSide handle_ of
1070 throwErrnoIfMinus1Retry_ "hClose"
1071 #ifdef mingw32_HOST_OS
1072 (closeFd (haIsStream handle_) c_fd)
1078 -- free the spare buffers
1079 writeIORef (haBuffers handle_) BufferListNil
1081 #ifndef mingw32_HOST_OS
1086 -- we must set the fd to -1, because the finalizer is going
1087 -- to run eventually and try to close/unlock it.
1088 return (handle_{ haFD = -1,
1089 haType = ClosedHandle
1092 -----------------------------------------------------------------------------
1093 -- Detecting and changing the size of a file
1095 -- | For a handle @hdl@ which attached to a physical file,
1096 -- 'hFileSize' @hdl@ returns the size of that file in 8-bit bytes.
1098 hFileSize :: Handle -> IO Integer
1100 withHandle_ "hFileSize" handle $ \ handle_ -> do
1101 case haType handle_ of
1102 ClosedHandle -> ioe_closedHandle
1103 SemiClosedHandle -> ioe_closedHandle
1104 _ -> do flushWriteBufferOnly handle_
1105 r <- fdFileSize (haFD handle_)
1108 else ioException (IOError Nothing InappropriateType "hFileSize"
1109 "not a regular file" Nothing)
1112 -- | 'hSetFileSize' @hdl@ @size@ truncates the physical file with handle @hdl@ to @size@ bytes.
1114 hSetFileSize :: Handle -> Integer -> IO ()
1115 hSetFileSize handle size =
1116 withHandle_ "hSetFileSize" handle $ \ handle_ -> do
1117 case haType handle_ of
1118 ClosedHandle -> ioe_closedHandle
1119 SemiClosedHandle -> ioe_closedHandle
1120 _ -> do flushWriteBufferOnly handle_
1121 throwErrnoIf (/=0) "hSetFileSize"
1122 (c_ftruncate (fromIntegral (haFD handle_)) (fromIntegral size))
1125 -- ---------------------------------------------------------------------------
1126 -- Detecting the End of Input
1128 -- | For a readable handle @hdl@, 'hIsEOF' @hdl@ returns
1129 -- 'True' if no further input can be taken from @hdl@ or for a
1130 -- physical file, if the current I\/O position is equal to the length of
1131 -- the file. Otherwise, it returns 'False'.
1133 hIsEOF :: Handle -> IO Bool
1136 (do hLookAhead handle; return False)
1137 (\e -> if isEOFError e then return True else ioError e)
1139 -- | The computation 'isEOF' is identical to 'hIsEOF',
1140 -- except that it works only on 'stdin'.
1143 isEOF = hIsEOF stdin
1145 -- ---------------------------------------------------------------------------
1148 -- | Computation 'hLookAhead' returns the next character from the handle
1149 -- without removing it from the input buffer, blocking until a character
1152 -- This operation may fail with:
1154 -- * 'isEOFError' if the end of file has been reached.
1156 hLookAhead :: Handle -> IO Char
1157 hLookAhead handle = do
1158 wantReadableHandle "hLookAhead" handle $ \handle_ -> do
1159 let ref = haBuffer handle_
1161 is_line = haBufferMode handle_ == LineBuffering
1162 buf <- readIORef ref
1164 -- fill up the read buffer if necessary
1165 new_buf <- if bufferEmpty buf
1166 then fillReadBuffer fd True (haIsStream handle_) buf
1169 writeIORef ref new_buf
1171 (c,_) <- readCharFromBuffer (bufBuf buf) (bufRPtr buf)
1174 -- ---------------------------------------------------------------------------
1175 -- Buffering Operations
1177 -- Three kinds of buffering are supported: line-buffering,
1178 -- block-buffering or no-buffering. See GHC.IOBase for definition and
1179 -- further explanation of what the type represent.
1181 -- | Computation 'hSetBuffering' @hdl mode@ sets the mode of buffering for
1182 -- handle @hdl@ on subsequent reads and writes.
1184 -- If the buffer mode is changed from 'BlockBuffering' or
1185 -- 'LineBuffering' to 'NoBuffering', then
1187 -- * if @hdl@ is writable, the buffer is flushed as for 'hFlush';
1189 -- * if @hdl@ is not writable, the contents of the buffer is discarded.
1191 -- This operation may fail with:
1193 -- * 'isPermissionError' if the handle has already been used for reading
1194 -- or writing and the implementation does not allow the buffering mode
1197 hSetBuffering :: Handle -> BufferMode -> IO ()
1198 hSetBuffering handle mode =
1199 withAllHandles__ "hSetBuffering" handle $ \ handle_ -> do
1200 case haType handle_ of
1201 ClosedHandle -> ioe_closedHandle
1204 - we flush the old buffer regardless of whether
1205 the new buffer could fit the contents of the old buffer
1207 - allow a handle's buffering to change even if IO has
1208 occurred (ANSI C spec. does not allow this, nor did
1209 the previous implementation of IO.hSetBuffering).
1210 - a non-standard extension is to allow the buffering
1211 of semi-closed handles to change [sof 6/98]
1215 let state = initBufferState (haType handle_)
1218 -- we always have a 1-character read buffer for
1219 -- unbuffered handles: it's needed to
1220 -- support hLookAhead.
1221 NoBuffering -> allocateBuffer 1 ReadBuffer
1222 LineBuffering -> allocateBuffer dEFAULT_BUFFER_SIZE state
1223 BlockBuffering Nothing -> allocateBuffer dEFAULT_BUFFER_SIZE state
1224 BlockBuffering (Just n) | n <= 0 -> ioe_bufsiz n
1225 | otherwise -> allocateBuffer n state
1226 writeIORef (haBuffer handle_) new_buf
1228 -- for input terminals we need to put the terminal into
1229 -- cooked or raw mode depending on the type of buffering.
1230 is_tty <- fdIsTTY (haFD handle_)
1231 when (is_tty && isReadableHandleType (haType handle_)) $
1233 #ifndef mingw32_HOST_OS
1234 -- 'raw' mode under win32 is a bit too specialised (and troublesome
1235 -- for most common uses), so simply disable its use here.
1236 NoBuffering -> setCooked (haFD handle_) False
1238 NoBuffering -> return ()
1240 _ -> setCooked (haFD handle_) True
1242 -- throw away spare buffers, they might be the wrong size
1243 writeIORef (haBuffers handle_) BufferListNil
1245 return (handle_{ haBufferMode = mode })
1247 -- -----------------------------------------------------------------------------
1250 -- | The action 'hFlush' @hdl@ causes any items buffered for output
1251 -- in handle @hdl@ to be sent immediately to the operating system.
1253 -- This operation may fail with:
1255 -- * 'isFullError' if the device is full;
1257 -- * 'isPermissionError' if a system resource limit would be exceeded.
1258 -- It is unspecified whether the characters in the buffer are discarded
1259 -- or retained under these circumstances.
1261 hFlush :: Handle -> IO ()
1263 wantWritableHandle "hFlush" handle $ \ handle_ -> do
1264 buf <- readIORef (haBuffer handle_)
1265 if bufferIsWritable buf && not (bufferEmpty buf)
1266 then do flushed_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
1267 writeIORef (haBuffer handle_) flushed_buf
1271 -- -----------------------------------------------------------------------------
1272 -- Repositioning Handles
1274 data HandlePosn = HandlePosn Handle HandlePosition
1276 instance Eq HandlePosn where
1277 (HandlePosn h1 p1) == (HandlePosn h2 p2) = p1==p2 && h1==h2
1279 instance Show HandlePosn where
1280 showsPrec p (HandlePosn h pos) =
1281 showsPrec p h . showString " at position " . shows pos
1283 -- HandlePosition is the Haskell equivalent of POSIX' off_t.
1284 -- We represent it as an Integer on the Haskell side, but
1285 -- cheat slightly in that hGetPosn calls upon a C helper
1286 -- that reports the position back via (merely) an Int.
1287 type HandlePosition = Integer
1289 -- | Computation 'hGetPosn' @hdl@ returns the current I\/O position of
1290 -- @hdl@ as a value of the abstract type 'HandlePosn'.
1292 hGetPosn :: Handle -> IO HandlePosn
1293 hGetPosn handle = do
1294 posn <- hTell handle
1295 return (HandlePosn handle posn)
1297 -- | If a call to 'hGetPosn' @hdl@ returns a position @p@,
1298 -- then computation 'hSetPosn' @p@ sets the position of @hdl@
1299 -- to the position it held at the time of the call to 'hGetPosn'.
1301 -- This operation may fail with:
1303 -- * 'isPermissionError' if a system resource limit would be exceeded.
1305 hSetPosn :: HandlePosn -> IO ()
1306 hSetPosn (HandlePosn h i) = hSeek h AbsoluteSeek i
1308 -- ---------------------------------------------------------------------------
1311 -- | A mode that determines the effect of 'hSeek' @hdl mode i@, as follows:
1313 = AbsoluteSeek -- ^ the position of @hdl@ is set to @i@.
1314 | RelativeSeek -- ^ the position of @hdl@ is set to offset @i@
1315 -- from the current position.
1316 | SeekFromEnd -- ^ the position of @hdl@ is set to offset @i@
1317 -- from the end of the file.
1318 deriving (Eq, Ord, Ix, Enum, Read, Show)
1321 - when seeking using `SeekFromEnd', positive offsets (>=0) means
1322 seeking at or past EOF.
1324 - we possibly deviate from the report on the issue of seeking within
1325 the buffer and whether to flush it or not. The report isn't exactly
1329 -- | Computation 'hSeek' @hdl mode i@ sets the position of handle
1330 -- @hdl@ depending on @mode@.
1331 -- The offset @i@ is given in terms of 8-bit bytes.
1333 -- If @hdl@ is block- or line-buffered, then seeking to a position which is not
1334 -- in the current buffer will first cause any items in the output buffer to be
1335 -- written to the device, and then cause the input buffer to be discarded.
1336 -- Some handles may not be seekable (see 'hIsSeekable'), or only support a
1337 -- subset of the possible positioning operations (for instance, it may only
1338 -- be possible to seek to the end of a tape, or to a positive offset from
1339 -- the beginning or current position).
1340 -- It is not possible to set a negative I\/O position, or for
1341 -- a physical file, an I\/O position beyond the current end-of-file.
1343 -- This operation may fail with:
1345 -- * 'isPermissionError' if a system resource limit would be exceeded.
1347 hSeek :: Handle -> SeekMode -> Integer -> IO ()
1348 hSeek handle mode offset =
1349 wantSeekableHandle "hSeek" handle $ \ handle_ -> do
1351 puts ("hSeek " ++ show (mode,offset) ++ "\n")
1353 let ref = haBuffer handle_
1354 buf <- readIORef ref
1360 throwErrnoIfMinus1Retry_ "hSeek"
1361 (c_lseek (fromIntegral (haFD handle_)) (fromIntegral offset) whence)
1364 whence = case mode of
1365 AbsoluteSeek -> sEEK_SET
1366 RelativeSeek -> sEEK_CUR
1367 SeekFromEnd -> sEEK_END
1369 if bufferIsWritable buf
1370 then do new_buf <- flushWriteBuffer fd (haIsStream handle_) buf
1371 writeIORef ref new_buf
1375 if mode == RelativeSeek && offset >= 0 && offset < fromIntegral (w - r)
1376 then writeIORef ref buf{ bufRPtr = r + fromIntegral offset }
1379 new_buf <- flushReadBuffer (haFD handle_) buf
1380 writeIORef ref new_buf
1384 hTell :: Handle -> IO Integer
1386 wantSeekableHandle "hGetPosn" handle $ \ handle_ -> do
1388 #if defined(mingw32_HOST_OS)
1389 -- urgh, on Windows we have to worry about \n -> \r\n translation,
1390 -- so we can't easily calculate the file position using the
1391 -- current buffer size. Just flush instead.
1394 let fd = fromIntegral (haFD handle_)
1395 posn <- fromIntegral `liftM`
1396 throwErrnoIfMinus1Retry "hGetPosn"
1397 (c_lseek fd 0 sEEK_CUR)
1399 let ref = haBuffer handle_
1400 buf <- readIORef ref
1403 | bufferIsWritable buf = posn + fromIntegral (bufWPtr buf)
1404 | otherwise = posn - fromIntegral (bufWPtr buf - bufRPtr buf)
1406 puts ("\nhGetPosn: (fd, posn, real_posn) = " ++ show (fd, posn, real_posn) ++ "\n")
1407 puts (" (bufWPtr, bufRPtr) = " ++ show (bufWPtr buf, bufRPtr buf) ++ "\n")
1411 -- -----------------------------------------------------------------------------
1412 -- Handle Properties
1414 -- A number of operations return information about the properties of a
1415 -- handle. Each of these operations returns `True' if the handle has
1416 -- the specified property, and `False' otherwise.
1418 hIsOpen :: Handle -> IO Bool
1420 withHandle_ "hIsOpen" handle $ \ handle_ -> do
1421 case haType handle_ of
1422 ClosedHandle -> return False
1423 SemiClosedHandle -> return False
1426 hIsClosed :: Handle -> IO Bool
1428 withHandle_ "hIsClosed" handle $ \ handle_ -> do
1429 case haType handle_ of
1430 ClosedHandle -> return True
1433 {- not defined, nor exported, but mentioned
1434 here for documentation purposes:
1436 hSemiClosed :: Handle -> IO Bool
1440 return (not (ho || hc))
1443 hIsReadable :: Handle -> IO Bool
1444 hIsReadable (DuplexHandle _ _ _) = return True
1445 hIsReadable handle =
1446 withHandle_ "hIsReadable" handle $ \ handle_ -> do
1447 case haType handle_ of
1448 ClosedHandle -> ioe_closedHandle
1449 SemiClosedHandle -> ioe_closedHandle
1450 htype -> return (isReadableHandleType htype)
1452 hIsWritable :: Handle -> IO Bool
1453 hIsWritable (DuplexHandle _ _ _) = return True
1454 hIsWritable handle =
1455 withHandle_ "hIsWritable" handle $ \ handle_ -> do
1456 case haType handle_ of
1457 ClosedHandle -> ioe_closedHandle
1458 SemiClosedHandle -> ioe_closedHandle
1459 htype -> return (isWritableHandleType htype)
1461 -- | Computation 'hGetBuffering' @hdl@ returns the current buffering mode
1464 hGetBuffering :: Handle -> IO BufferMode
1465 hGetBuffering handle =
1466 withHandle_ "hGetBuffering" handle $ \ handle_ -> do
1467 case haType handle_ of
1468 ClosedHandle -> ioe_closedHandle
1470 -- We're being non-standard here, and allow the buffering
1471 -- of a semi-closed handle to be queried. -- sof 6/98
1472 return (haBufferMode handle_) -- could be stricter..
1474 hIsSeekable :: Handle -> IO Bool
1475 hIsSeekable handle =
1476 withHandle_ "hIsSeekable" handle $ \ handle_ -> do
1477 case haType handle_ of
1478 ClosedHandle -> ioe_closedHandle
1479 SemiClosedHandle -> ioe_closedHandle
1480 AppendHandle -> return False
1481 _ -> do t <- fdType (haFD handle_)
1482 return ((t == RegularFile || t == RawDevice)
1483 && (haIsBin handle_ || tEXT_MODE_SEEK_ALLOWED))
1485 -- -----------------------------------------------------------------------------
1486 -- Changing echo status (Non-standard GHC extensions)
1488 -- | Set the echoing status of a handle connected to a terminal.
1490 hSetEcho :: Handle -> Bool -> IO ()
1491 hSetEcho handle on = do
1492 isT <- hIsTerminalDevice handle
1496 withHandle_ "hSetEcho" handle $ \ handle_ -> do
1497 case haType handle_ of
1498 ClosedHandle -> ioe_closedHandle
1499 _ -> setEcho (haFD handle_) on
1501 -- | Get the echoing status of a handle connected to a terminal.
1503 hGetEcho :: Handle -> IO Bool
1504 hGetEcho handle = do
1505 isT <- hIsTerminalDevice handle
1509 withHandle_ "hGetEcho" handle $ \ handle_ -> do
1510 case haType handle_ of
1511 ClosedHandle -> ioe_closedHandle
1512 _ -> getEcho (haFD handle_)
1514 -- | Is the handle connected to a terminal?
1516 hIsTerminalDevice :: Handle -> IO Bool
1517 hIsTerminalDevice handle = do
1518 withHandle_ "hIsTerminalDevice" handle $ \ handle_ -> do
1519 case haType handle_ of
1520 ClosedHandle -> ioe_closedHandle
1521 _ -> fdIsTTY (haFD handle_)
1523 -- -----------------------------------------------------------------------------
1526 -- | Select binary mode ('True') or text mode ('False') on a open handle.
1527 -- (See also 'openBinaryFile'.)
1529 hSetBinaryMode :: Handle -> Bool -> IO ()
1530 hSetBinaryMode handle bin =
1531 withAllHandles__ "hSetBinaryMode" handle $ \ handle_ ->
1532 do throwErrnoIfMinus1_ "hSetBinaryMode"
1533 (setmode (fromIntegral (haFD handle_)) bin)
1534 return handle_{haIsBin=bin}
1536 foreign import ccall unsafe "__hscore_setmode"
1537 setmode :: CInt -> Bool -> IO CInt
1539 -- -----------------------------------------------------------------------------
1540 -- Duplicating a Handle
1542 -- | Returns a duplicate of the original handle, with its own buffer.
1543 -- The two Handles will share a file pointer, however. The original
1544 -- handle's buffer is flushed, including discarding any input data,
1545 -- before the handle is duplicated.
1547 hDuplicate :: Handle -> IO Handle
1548 hDuplicate h@(FileHandle path m) = do
1549 new_h_ <- withHandle' "hDuplicate" h m (dupHandle Nothing)
1550 newFileHandle path (handleFinalizer path) new_h_
1551 hDuplicate h@(DuplexHandle path r w) = do
1552 new_w_ <- withHandle' "hDuplicate" h w (dupHandle Nothing)
1553 new_w <- newMVar new_w_
1554 new_r_ <- withHandle' "hDuplicate" h r (dupHandle (Just new_w))
1555 new_r <- newMVar new_r_
1556 addMVarFinalizer new_w (handleFinalizer path new_w)
1557 return (DuplexHandle path new_r new_w)
1559 dupHandle other_side h_ = do
1560 -- flush the buffer first, so we don't have to copy its contents
1562 new_fd <- throwErrnoIfMinus1 "dupHandle" $
1563 c_dup (fromIntegral (haFD h_))
1564 dupHandle_ other_side h_ new_fd
1566 dupHandleTo other_side hto_ h_ = do
1568 -- Windows' dup2 does not return the new descriptor, unlike Unix
1569 throwErrnoIfMinus1 "dupHandleTo" $
1570 c_dup2 (fromIntegral (haFD h_)) (fromIntegral (haFD hto_))
1571 dupHandle_ other_side h_ (haFD hto_)
1573 dupHandle_ other_side h_ new_fd = do
1574 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE (initBufferState (haType h_))
1575 ioref <- newIORef buffer
1576 ioref_buffers <- newIORef BufferListNil
1578 let new_handle_ = h_{ haFD = fromIntegral new_fd,
1580 haBuffers = ioref_buffers,
1581 haOtherSide = other_side }
1582 return (h_, new_handle_)
1584 -- -----------------------------------------------------------------------------
1585 -- Replacing a Handle
1588 Makes the second handle a duplicate of the first handle. The second
1589 handle will be closed first, if it is not already.
1591 This can be used to retarget the standard Handles, for example:
1593 > do h <- openFile "mystdout" WriteMode
1594 > hDuplicateTo h stdout
1597 hDuplicateTo :: Handle -> Handle -> IO ()
1598 hDuplicateTo h1@(FileHandle _ m1) h2@(FileHandle _ m2) = do
1599 withHandle__' "hDuplicateTo" h2 m2 $ \h2_ -> do
1600 _ <- hClose_help h2_
1601 withHandle' "hDuplicateTo" h1 m1 (dupHandleTo Nothing h2_)
1602 hDuplicateTo h1@(DuplexHandle _ r1 w1) h2@(DuplexHandle _ r2 w2) = do
1603 withHandle__' "hDuplicateTo" h2 w2 $ \w2_ -> do
1604 _ <- hClose_help w2_
1605 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo Nothing w2_)
1606 withHandle__' "hDuplicateTo" h2 r2 $ \r2_ -> do
1607 _ <- hClose_help r2_
1608 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo (Just w1) r2_)
1610 ioException (IOError (Just h1) IllegalOperation "hDuplicateTo"
1611 "handles are incompatible" Nothing)
1613 -- ---------------------------------------------------------------------------
1616 -- | 'hShow' is in the 'IO' monad, and gives more comprehensive output
1617 -- than the (pure) instance of 'Show' for 'Handle'.
1619 hShow :: Handle -> IO String
1620 hShow h@(FileHandle path _) = showHandle' path False h
1621 hShow h@(DuplexHandle path _ _) = showHandle' path True h
1623 showHandle' filepath is_duplex h =
1624 withHandle_ "showHandle" h $ \hdl_ ->
1626 showType | is_duplex = showString "duplex (read-write)"
1627 | otherwise = shows (haType hdl_)
1631 showHdl (haType hdl_)
1632 (showString "loc=" . showString filepath . showChar ',' .
1633 showString "type=" . showType . showChar ',' .
1634 showString "binary=" . shows (haIsBin hdl_) . showChar ',' .
1635 showString "buffering=" . showBufMode (unsafePerformIO (readIORef (haBuffer hdl_))) (haBufferMode hdl_) . showString "}" )
1639 showHdl :: HandleType -> ShowS -> ShowS
1642 ClosedHandle -> shows ht . showString "}"
1645 showBufMode :: Buffer -> BufferMode -> ShowS
1646 showBufMode buf bmo =
1648 NoBuffering -> showString "none"
1649 LineBuffering -> showString "line"
1650 BlockBuffering (Just n) -> showString "block " . showParen True (shows n)
1651 BlockBuffering Nothing -> showString "block " . showParen True (shows def)
1656 -- ---------------------------------------------------------------------------
1659 #if defined(DEBUG_DUMP)
1660 puts :: String -> IO ()
1661 puts s = do write_rawBuffer 1 (unsafeCoerce# (packCString# s)) 0 (fromIntegral (length s))
1665 -- -----------------------------------------------------------------------------
1668 throwErrnoIfMinus1RetryOnBlock :: String -> IO CInt -> IO CInt -> IO CInt
1669 throwErrnoIfMinus1RetryOnBlock loc f on_block =
1672 if (res :: CInt) == -1
1676 then throwErrnoIfMinus1RetryOnBlock loc f on_block
1677 else if err == eWOULDBLOCK || err == eAGAIN
1682 -- -----------------------------------------------------------------------------
1683 -- wrappers to platform-specific constants:
1685 foreign import ccall unsafe "__hscore_supportsTextMode"
1686 tEXT_MODE_SEEK_ALLOWED :: Bool
1688 foreign import ccall unsafe "__hscore_bufsiz" dEFAULT_BUFFER_SIZE :: Int
1689 foreign import ccall unsafe "__hscore_seek_cur" sEEK_CUR :: CInt
1690 foreign import ccall unsafe "__hscore_seek_set" sEEK_SET :: CInt
1691 foreign import ccall unsafe "__hscore_seek_end" sEEK_END :: CInt