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 = readRawBufferNoBlock
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
940 ioException (IOError Nothing UnsupportedOperation "openFd"
941 "unknown file type" Nothing)
943 fdToHandle :: FD -> IO Handle
946 let fd_str = "<file descriptor: " ++ show fd ++ ">"
947 openFd fd Nothing False{-XXX!-} fd_str mode True{-bin mode-}
950 #ifndef mingw32_HOST_OS
951 foreign import ccall unsafe "lockFile"
952 lockFile :: CInt -> CInt -> CInt -> IO CInt
954 foreign import ccall unsafe "unlockFile"
955 unlockFile :: CInt -> IO CInt
958 mkStdHandle :: FD -> FilePath -> HandleType -> IORef Buffer -> BufferMode
960 mkStdHandle fd filepath ha_type buf bmode = do
961 spares <- newIORef BufferListNil
962 newFileHandle filepath (stdHandleFinalizer filepath)
963 (Handle__ { haFD = fd,
965 haIsBin = dEFAULT_OPEN_IN_BINARY_MODE,
967 haBufferMode = bmode,
970 haOtherSide = Nothing
973 mkFileHandle :: FD -> Bool -> FilePath -> HandleType -> Bool -> IO Handle
974 mkFileHandle fd is_stream filepath ha_type binary = do
975 (buf, bmode) <- getBuffer fd (initBufferState ha_type)
977 #ifdef mingw32_HOST_OS
978 -- On Windows, if this is a read/write handle and we are in text mode,
979 -- turn off buffering. We don't correctly handle the case of switching
980 -- from read mode to write mode on a buffered text-mode handle, see bug
982 bmode <- case ha_type of
983 ReadWriteHandle | not binary -> return NoBuffering
984 _other -> return bmode
987 spares <- newIORef BufferListNil
988 newFileHandle filepath (handleFinalizer filepath)
989 (Handle__ { haFD = fd,
992 haIsStream = is_stream,
993 haBufferMode = bmode,
996 haOtherSide = Nothing
999 mkDuplexHandle :: FD -> Bool -> FilePath -> Bool -> IO Handle
1000 mkDuplexHandle fd is_stream filepath binary = do
1001 (w_buf, w_bmode) <- getBuffer fd WriteBuffer
1002 w_spares <- newIORef BufferListNil
1004 Handle__ { haFD = fd,
1005 haType = WriteHandle,
1007 haIsStream = is_stream,
1008 haBufferMode = w_bmode,
1010 haBuffers = w_spares,
1011 haOtherSide = Nothing
1013 write_side <- newMVar w_handle_
1015 (r_buf, r_bmode) <- getBuffer fd ReadBuffer
1016 r_spares <- newIORef BufferListNil
1018 Handle__ { haFD = fd,
1019 haType = ReadHandle,
1021 haIsStream = is_stream,
1022 haBufferMode = r_bmode,
1024 haBuffers = r_spares,
1025 haOtherSide = Just write_side
1027 read_side <- newMVar r_handle_
1029 addMVarFinalizer write_side (handleFinalizer filepath write_side)
1030 return (DuplexHandle filepath read_side write_side)
1033 initBufferState ReadHandle = ReadBuffer
1034 initBufferState _ = WriteBuffer
1036 -- ---------------------------------------------------------------------------
1039 -- | Computation 'hClose' @hdl@ makes handle @hdl@ closed. Before the
1040 -- computation finishes, if @hdl@ is writable its buffer is flushed as
1042 -- Performing 'hClose' on a handle that has already been closed has no effect;
1043 -- doing so not an error. All other operations on a closed handle will fail.
1044 -- If 'hClose' fails for any reason, any further operations (apart from
1045 -- 'hClose') on the handle will still fail as if @hdl@ had been successfully
1048 hClose :: Handle -> IO ()
1049 hClose h@(FileHandle _ m) = hClose' h m
1050 hClose h@(DuplexHandle _ r w) = hClose' h w >> hClose' h r
1052 hClose' h m = withHandle__' "hClose" h m $ hClose_help
1054 -- hClose_help is also called by lazyRead (in PrelIO) when EOF is read
1055 -- or an IO error occurs on a lazy stream. The semi-closed Handle is
1056 -- then closed immediately. We have to be careful with DuplexHandles
1057 -- though: we have to leave the closing to the finalizer in that case,
1058 -- because the write side may still be in use.
1059 hClose_help :: Handle__ -> IO Handle__
1060 hClose_help handle_ =
1061 case haType handle_ of
1062 ClosedHandle -> return handle_
1063 _ -> do flushWriteBufferOnly handle_ -- interruptible
1064 hClose_handle_ handle_
1066 hClose_handle_ handle_ = do
1067 let fd = haFD handle_
1068 c_fd = fromIntegral fd
1070 -- close the file descriptor, but not when this is the read
1071 -- side of a duplex handle.
1072 case haOtherSide handle_ of
1074 throwErrnoIfMinus1Retry_ "hClose"
1075 #ifdef mingw32_HOST_OS
1076 (closeFd (haIsStream handle_) c_fd)
1082 -- free the spare buffers
1083 writeIORef (haBuffers handle_) BufferListNil
1085 #ifndef mingw32_HOST_OS
1090 -- we must set the fd to -1, because the finalizer is going
1091 -- to run eventually and try to close/unlock it.
1092 return (handle_{ haFD = -1,
1093 haType = ClosedHandle
1096 -----------------------------------------------------------------------------
1097 -- Detecting and changing the size of a file
1099 -- | For a handle @hdl@ which attached to a physical file,
1100 -- 'hFileSize' @hdl@ returns the size of that file in 8-bit bytes.
1102 hFileSize :: Handle -> IO Integer
1104 withHandle_ "hFileSize" handle $ \ handle_ -> do
1105 case haType handle_ of
1106 ClosedHandle -> ioe_closedHandle
1107 SemiClosedHandle -> ioe_closedHandle
1108 _ -> do flushWriteBufferOnly handle_
1109 r <- fdFileSize (haFD handle_)
1112 else ioException (IOError Nothing InappropriateType "hFileSize"
1113 "not a regular file" Nothing)
1116 -- | 'hSetFileSize' @hdl@ @size@ truncates the physical file with handle @hdl@ to @size@ bytes.
1118 hSetFileSize :: Handle -> Integer -> IO ()
1119 hSetFileSize handle size =
1120 withHandle_ "hSetFileSize" handle $ \ handle_ -> do
1121 case haType handle_ of
1122 ClosedHandle -> ioe_closedHandle
1123 SemiClosedHandle -> ioe_closedHandle
1124 _ -> do flushWriteBufferOnly handle_
1125 throwErrnoIf (/=0) "hSetFileSize"
1126 (c_ftruncate (fromIntegral (haFD handle_)) (fromIntegral size))
1129 -- ---------------------------------------------------------------------------
1130 -- Detecting the End of Input
1132 -- | For a readable handle @hdl@, 'hIsEOF' @hdl@ returns
1133 -- 'True' if no further input can be taken from @hdl@ or for a
1134 -- physical file, if the current I\/O position is equal to the length of
1135 -- the file. Otherwise, it returns 'False'.
1137 hIsEOF :: Handle -> IO Bool
1140 (do hLookAhead handle; return False)
1141 (\e -> if isEOFError e then return True else ioError e)
1143 -- | The computation 'isEOF' is identical to 'hIsEOF',
1144 -- except that it works only on 'stdin'.
1147 isEOF = hIsEOF stdin
1149 -- ---------------------------------------------------------------------------
1152 -- | Computation 'hLookAhead' returns the next character from the handle
1153 -- without removing it from the input buffer, blocking until a character
1156 -- This operation may fail with:
1158 -- * 'isEOFError' if the end of file has been reached.
1160 hLookAhead :: Handle -> IO Char
1161 hLookAhead handle = do
1162 wantReadableHandle "hLookAhead" handle $ \handle_ -> do
1163 let ref = haBuffer handle_
1165 is_line = haBufferMode handle_ == LineBuffering
1166 buf <- readIORef ref
1168 -- fill up the read buffer if necessary
1169 new_buf <- if bufferEmpty buf
1170 then fillReadBuffer fd True (haIsStream handle_) buf
1173 writeIORef ref new_buf
1175 (c,_) <- readCharFromBuffer (bufBuf buf) (bufRPtr buf)
1178 -- ---------------------------------------------------------------------------
1179 -- Buffering Operations
1181 -- Three kinds of buffering are supported: line-buffering,
1182 -- block-buffering or no-buffering. See GHC.IOBase for definition and
1183 -- further explanation of what the type represent.
1185 -- | Computation 'hSetBuffering' @hdl mode@ sets the mode of buffering for
1186 -- handle @hdl@ on subsequent reads and writes.
1188 -- If the buffer mode is changed from 'BlockBuffering' or
1189 -- 'LineBuffering' to 'NoBuffering', then
1191 -- * if @hdl@ is writable, the buffer is flushed as for 'hFlush';
1193 -- * if @hdl@ is not writable, the contents of the buffer is discarded.
1195 -- This operation may fail with:
1197 -- * 'isPermissionError' if the handle has already been used for reading
1198 -- or writing and the implementation does not allow the buffering mode
1201 hSetBuffering :: Handle -> BufferMode -> IO ()
1202 hSetBuffering handle mode =
1203 withAllHandles__ "hSetBuffering" handle $ \ handle_ -> do
1204 case haType handle_ of
1205 ClosedHandle -> ioe_closedHandle
1208 - we flush the old buffer regardless of whether
1209 the new buffer could fit the contents of the old buffer
1211 - allow a handle's buffering to change even if IO has
1212 occurred (ANSI C spec. does not allow this, nor did
1213 the previous implementation of IO.hSetBuffering).
1214 - a non-standard extension is to allow the buffering
1215 of semi-closed handles to change [sof 6/98]
1219 let state = initBufferState (haType handle_)
1222 -- we always have a 1-character read buffer for
1223 -- unbuffered handles: it's needed to
1224 -- support hLookAhead.
1225 NoBuffering -> allocateBuffer 1 ReadBuffer
1226 LineBuffering -> allocateBuffer dEFAULT_BUFFER_SIZE state
1227 BlockBuffering Nothing -> allocateBuffer dEFAULT_BUFFER_SIZE state
1228 BlockBuffering (Just n) | n <= 0 -> ioe_bufsiz n
1229 | otherwise -> allocateBuffer n state
1230 writeIORef (haBuffer handle_) new_buf
1232 -- for input terminals we need to put the terminal into
1233 -- cooked or raw mode depending on the type of buffering.
1234 is_tty <- fdIsTTY (haFD handle_)
1235 when (is_tty && isReadableHandleType (haType handle_)) $
1237 #ifndef mingw32_HOST_OS
1238 -- 'raw' mode under win32 is a bit too specialised (and troublesome
1239 -- for most common uses), so simply disable its use here.
1240 NoBuffering -> setCooked (haFD handle_) False
1242 NoBuffering -> return ()
1244 _ -> setCooked (haFD handle_) True
1246 -- throw away spare buffers, they might be the wrong size
1247 writeIORef (haBuffers handle_) BufferListNil
1249 return (handle_{ haBufferMode = mode })
1251 -- -----------------------------------------------------------------------------
1254 -- | The action 'hFlush' @hdl@ causes any items buffered for output
1255 -- in handle @hdl@ to be sent immediately to the operating system.
1257 -- This operation may fail with:
1259 -- * 'isFullError' if the device is full;
1261 -- * 'isPermissionError' if a system resource limit would be exceeded.
1262 -- It is unspecified whether the characters in the buffer are discarded
1263 -- or retained under these circumstances.
1265 hFlush :: Handle -> IO ()
1267 wantWritableHandle "hFlush" handle $ \ handle_ -> do
1268 buf <- readIORef (haBuffer handle_)
1269 if bufferIsWritable buf && not (bufferEmpty buf)
1270 then do flushed_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
1271 writeIORef (haBuffer handle_) flushed_buf
1275 -- -----------------------------------------------------------------------------
1276 -- Repositioning Handles
1278 data HandlePosn = HandlePosn Handle HandlePosition
1280 instance Eq HandlePosn where
1281 (HandlePosn h1 p1) == (HandlePosn h2 p2) = p1==p2 && h1==h2
1283 instance Show HandlePosn where
1284 showsPrec p (HandlePosn h pos) =
1285 showsPrec p h . showString " at position " . shows pos
1287 -- HandlePosition is the Haskell equivalent of POSIX' off_t.
1288 -- We represent it as an Integer on the Haskell side, but
1289 -- cheat slightly in that hGetPosn calls upon a C helper
1290 -- that reports the position back via (merely) an Int.
1291 type HandlePosition = Integer
1293 -- | Computation 'hGetPosn' @hdl@ returns the current I\/O position of
1294 -- @hdl@ as a value of the abstract type 'HandlePosn'.
1296 hGetPosn :: Handle -> IO HandlePosn
1297 hGetPosn handle = do
1298 posn <- hTell handle
1299 return (HandlePosn handle posn)
1301 -- | If a call to 'hGetPosn' @hdl@ returns a position @p@,
1302 -- then computation 'hSetPosn' @p@ sets the position of @hdl@
1303 -- to the position it held at the time of the call to 'hGetPosn'.
1305 -- This operation may fail with:
1307 -- * 'isPermissionError' if a system resource limit would be exceeded.
1309 hSetPosn :: HandlePosn -> IO ()
1310 hSetPosn (HandlePosn h i) = hSeek h AbsoluteSeek i
1312 -- ---------------------------------------------------------------------------
1315 -- | A mode that determines the effect of 'hSeek' @hdl mode i@, as follows:
1317 = AbsoluteSeek -- ^ the position of @hdl@ is set to @i@.
1318 | RelativeSeek -- ^ the position of @hdl@ is set to offset @i@
1319 -- from the current position.
1320 | SeekFromEnd -- ^ the position of @hdl@ is set to offset @i@
1321 -- from the end of the file.
1322 deriving (Eq, Ord, Ix, Enum, Read, Show)
1325 - when seeking using `SeekFromEnd', positive offsets (>=0) means
1326 seeking at or past EOF.
1328 - we possibly deviate from the report on the issue of seeking within
1329 the buffer and whether to flush it or not. The report isn't exactly
1333 -- | Computation 'hSeek' @hdl mode i@ sets the position of handle
1334 -- @hdl@ depending on @mode@.
1335 -- The offset @i@ is given in terms of 8-bit bytes.
1337 -- If @hdl@ is block- or line-buffered, then seeking to a position which is not
1338 -- in the current buffer will first cause any items in the output buffer to be
1339 -- written to the device, and then cause the input buffer to be discarded.
1340 -- Some handles may not be seekable (see 'hIsSeekable'), or only support a
1341 -- subset of the possible positioning operations (for instance, it may only
1342 -- be possible to seek to the end of a tape, or to a positive offset from
1343 -- the beginning or current position).
1344 -- It is not possible to set a negative I\/O position, or for
1345 -- a physical file, an I\/O position beyond the current end-of-file.
1347 -- This operation may fail with:
1349 -- * 'isPermissionError' if a system resource limit would be exceeded.
1351 hSeek :: Handle -> SeekMode -> Integer -> IO ()
1352 hSeek handle mode offset =
1353 wantSeekableHandle "hSeek" handle $ \ handle_ -> do
1355 puts ("hSeek " ++ show (mode,offset) ++ "\n")
1357 let ref = haBuffer handle_
1358 buf <- readIORef ref
1364 throwErrnoIfMinus1Retry_ "hSeek"
1365 (c_lseek (fromIntegral (haFD handle_)) (fromIntegral offset) whence)
1368 whence = case mode of
1369 AbsoluteSeek -> sEEK_SET
1370 RelativeSeek -> sEEK_CUR
1371 SeekFromEnd -> sEEK_END
1373 if bufferIsWritable buf
1374 then do new_buf <- flushWriteBuffer fd (haIsStream handle_) buf
1375 writeIORef ref new_buf
1379 if mode == RelativeSeek && offset >= 0 && offset < fromIntegral (w - r)
1380 then writeIORef ref buf{ bufRPtr = r + fromIntegral offset }
1383 new_buf <- flushReadBuffer (haFD handle_) buf
1384 writeIORef ref new_buf
1388 hTell :: Handle -> IO Integer
1390 wantSeekableHandle "hGetPosn" handle $ \ handle_ -> do
1392 #if defined(mingw32_HOST_OS)
1393 -- urgh, on Windows we have to worry about \n -> \r\n translation,
1394 -- so we can't easily calculate the file position using the
1395 -- current buffer size. Just flush instead.
1398 let fd = fromIntegral (haFD handle_)
1399 posn <- fromIntegral `liftM`
1400 throwErrnoIfMinus1Retry "hGetPosn"
1401 (c_lseek fd 0 sEEK_CUR)
1403 let ref = haBuffer handle_
1404 buf <- readIORef ref
1407 | bufferIsWritable buf = posn + fromIntegral (bufWPtr buf)
1408 | otherwise = posn - fromIntegral (bufWPtr buf - bufRPtr buf)
1410 puts ("\nhGetPosn: (fd, posn, real_posn) = " ++ show (fd, posn, real_posn) ++ "\n")
1411 puts (" (bufWPtr, bufRPtr) = " ++ show (bufWPtr buf, bufRPtr buf) ++ "\n")
1415 -- -----------------------------------------------------------------------------
1416 -- Handle Properties
1418 -- A number of operations return information about the properties of a
1419 -- handle. Each of these operations returns `True' if the handle has
1420 -- the specified property, and `False' otherwise.
1422 hIsOpen :: Handle -> IO Bool
1424 withHandle_ "hIsOpen" handle $ \ handle_ -> do
1425 case haType handle_ of
1426 ClosedHandle -> return False
1427 SemiClosedHandle -> return False
1430 hIsClosed :: Handle -> IO Bool
1432 withHandle_ "hIsClosed" handle $ \ handle_ -> do
1433 case haType handle_ of
1434 ClosedHandle -> return True
1437 {- not defined, nor exported, but mentioned
1438 here for documentation purposes:
1440 hSemiClosed :: Handle -> IO Bool
1444 return (not (ho || hc))
1447 hIsReadable :: Handle -> IO Bool
1448 hIsReadable (DuplexHandle _ _ _) = return True
1449 hIsReadable handle =
1450 withHandle_ "hIsReadable" handle $ \ handle_ -> do
1451 case haType handle_ of
1452 ClosedHandle -> ioe_closedHandle
1453 SemiClosedHandle -> ioe_closedHandle
1454 htype -> return (isReadableHandleType htype)
1456 hIsWritable :: Handle -> IO Bool
1457 hIsWritable (DuplexHandle _ _ _) = return True
1458 hIsWritable handle =
1459 withHandle_ "hIsWritable" handle $ \ handle_ -> do
1460 case haType handle_ of
1461 ClosedHandle -> ioe_closedHandle
1462 SemiClosedHandle -> ioe_closedHandle
1463 htype -> return (isWritableHandleType htype)
1465 -- | Computation 'hGetBuffering' @hdl@ returns the current buffering mode
1468 hGetBuffering :: Handle -> IO BufferMode
1469 hGetBuffering handle =
1470 withHandle_ "hGetBuffering" handle $ \ handle_ -> do
1471 case haType handle_ of
1472 ClosedHandle -> ioe_closedHandle
1474 -- We're being non-standard here, and allow the buffering
1475 -- of a semi-closed handle to be queried. -- sof 6/98
1476 return (haBufferMode handle_) -- could be stricter..
1478 hIsSeekable :: Handle -> IO Bool
1479 hIsSeekable handle =
1480 withHandle_ "hIsSeekable" handle $ \ handle_ -> do
1481 case haType handle_ of
1482 ClosedHandle -> ioe_closedHandle
1483 SemiClosedHandle -> ioe_closedHandle
1484 AppendHandle -> return False
1485 _ -> do t <- fdType (haFD handle_)
1486 return ((t == RegularFile || t == RawDevice)
1487 && (haIsBin handle_ || tEXT_MODE_SEEK_ALLOWED))
1489 -- -----------------------------------------------------------------------------
1490 -- Changing echo status (Non-standard GHC extensions)
1492 -- | Set the echoing status of a handle connected to a terminal.
1494 hSetEcho :: Handle -> Bool -> IO ()
1495 hSetEcho handle on = do
1496 isT <- hIsTerminalDevice handle
1500 withHandle_ "hSetEcho" handle $ \ handle_ -> do
1501 case haType handle_ of
1502 ClosedHandle -> ioe_closedHandle
1503 _ -> setEcho (haFD handle_) on
1505 -- | Get the echoing status of a handle connected to a terminal.
1507 hGetEcho :: Handle -> IO Bool
1508 hGetEcho handle = do
1509 isT <- hIsTerminalDevice handle
1513 withHandle_ "hGetEcho" handle $ \ handle_ -> do
1514 case haType handle_ of
1515 ClosedHandle -> ioe_closedHandle
1516 _ -> getEcho (haFD handle_)
1518 -- | Is the handle connected to a terminal?
1520 hIsTerminalDevice :: Handle -> IO Bool
1521 hIsTerminalDevice handle = do
1522 withHandle_ "hIsTerminalDevice" handle $ \ handle_ -> do
1523 case haType handle_ of
1524 ClosedHandle -> ioe_closedHandle
1525 _ -> fdIsTTY (haFD handle_)
1527 -- -----------------------------------------------------------------------------
1530 -- | Select binary mode ('True') or text mode ('False') on a open handle.
1531 -- (See also 'openBinaryFile'.)
1533 hSetBinaryMode :: Handle -> Bool -> IO ()
1534 hSetBinaryMode handle bin =
1535 withAllHandles__ "hSetBinaryMode" handle $ \ handle_ ->
1536 do throwErrnoIfMinus1_ "hSetBinaryMode"
1537 (setmode (fromIntegral (haFD handle_)) bin)
1538 return handle_{haIsBin=bin}
1540 foreign import ccall unsafe "__hscore_setmode"
1541 setmode :: CInt -> Bool -> IO CInt
1543 -- -----------------------------------------------------------------------------
1544 -- Duplicating a Handle
1546 -- | Returns a duplicate of the original handle, with its own buffer.
1547 -- The two Handles will share a file pointer, however. The original
1548 -- handle's buffer is flushed, including discarding any input data,
1549 -- before the handle is duplicated.
1551 hDuplicate :: Handle -> IO Handle
1552 hDuplicate h@(FileHandle path m) = do
1553 new_h_ <- withHandle' "hDuplicate" h m (dupHandle Nothing)
1554 newFileHandle path (handleFinalizer path) new_h_
1555 hDuplicate h@(DuplexHandle path r w) = do
1556 new_w_ <- withHandle' "hDuplicate" h w (dupHandle Nothing)
1557 new_w <- newMVar new_w_
1558 new_r_ <- withHandle' "hDuplicate" h r (dupHandle (Just new_w))
1559 new_r <- newMVar new_r_
1560 addMVarFinalizer new_w (handleFinalizer path new_w)
1561 return (DuplexHandle path new_r new_w)
1563 dupHandle other_side h_ = do
1564 -- flush the buffer first, so we don't have to copy its contents
1566 new_fd <- throwErrnoIfMinus1 "dupHandle" $
1567 c_dup (fromIntegral (haFD h_))
1568 dupHandle_ other_side h_ new_fd
1570 dupHandleTo other_side hto_ h_ = do
1572 new_fd <- throwErrnoIfMinus1 "dupHandleTo" $
1573 c_dup2 (fromIntegral (haFD h_)) (fromIntegral (haFD hto_))
1574 dupHandle_ other_side h_ new_fd
1576 dupHandle_ other_side h_ new_fd = do
1577 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE (initBufferState (haType h_))
1578 ioref <- newIORef buffer
1579 ioref_buffers <- newIORef BufferListNil
1581 let new_handle_ = h_{ haFD = fromIntegral new_fd,
1583 haBuffers = ioref_buffers,
1584 haOtherSide = other_side }
1585 return (h_, new_handle_)
1587 -- -----------------------------------------------------------------------------
1588 -- Replacing a Handle
1591 Makes the second handle a duplicate of the first handle. The second
1592 handle will be closed first, if it is not already.
1594 This can be used to retarget the standard Handles, for example:
1596 > do h <- openFile "mystdout" WriteMode
1597 > hDuplicateTo h stdout
1600 hDuplicateTo :: Handle -> Handle -> IO ()
1601 hDuplicateTo h1@(FileHandle _ m1) h2@(FileHandle _ m2) = do
1602 withHandle__' "hDuplicateTo" h2 m2 $ \h2_ -> do
1603 _ <- hClose_help h2_
1604 withHandle' "hDuplicateTo" h1 m1 (dupHandleTo Nothing h2_)
1605 hDuplicateTo h1@(DuplexHandle _ r1 w1) h2@(DuplexHandle _ r2 w2) = do
1606 withHandle__' "hDuplicateTo" h2 w2 $ \w2_ -> do
1607 _ <- hClose_help w2_
1608 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo Nothing w2_)
1609 withHandle__' "hDuplicateTo" h2 r2 $ \r2_ -> do
1610 _ <- hClose_help r2_
1611 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo (Just w1) r2_)
1613 ioException (IOError (Just h1) IllegalOperation "hDuplicateTo"
1614 "handles are incompatible" Nothing)
1616 -- ---------------------------------------------------------------------------
1619 -- | 'hShow' is in the 'IO' monad, and gives more comprehensive output
1620 -- than the (pure) instance of 'Show' for 'Handle'.
1622 hShow :: Handle -> IO String
1623 hShow h@(FileHandle path _) = showHandle' path False h
1624 hShow h@(DuplexHandle path _ _) = showHandle' path True h
1626 showHandle' filepath is_duplex h =
1627 withHandle_ "showHandle" h $ \hdl_ ->
1629 showType | is_duplex = showString "duplex (read-write)"
1630 | otherwise = shows (haType hdl_)
1634 showHdl (haType hdl_)
1635 (showString "loc=" . showString filepath . showChar ',' .
1636 showString "type=" . showType . showChar ',' .
1637 showString "binary=" . shows (haIsBin hdl_) . showChar ',' .
1638 showString "buffering=" . showBufMode (unsafePerformIO (readIORef (haBuffer hdl_))) (haBufferMode hdl_) . showString "}" )
1642 showHdl :: HandleType -> ShowS -> ShowS
1645 ClosedHandle -> shows ht . showString "}"
1648 showBufMode :: Buffer -> BufferMode -> ShowS
1649 showBufMode buf bmo =
1651 NoBuffering -> showString "none"
1652 LineBuffering -> showString "line"
1653 BlockBuffering (Just n) -> showString "block " . showParen True (shows n)
1654 BlockBuffering Nothing -> showString "block " . showParen True (shows def)
1659 -- ---------------------------------------------------------------------------
1662 #if defined(DEBUG_DUMP)
1663 puts :: String -> IO ()
1664 puts s = do write_rawBuffer 1 (unsafeCoerce# (packCString# s)) 0 (fromIntegral (length s))
1668 -- -----------------------------------------------------------------------------
1671 throwErrnoIfMinus1RetryOnBlock :: String -> IO CInt -> IO CInt -> IO CInt
1672 throwErrnoIfMinus1RetryOnBlock loc f on_block =
1675 if (res :: CInt) == -1
1679 then throwErrnoIfMinus1RetryOnBlock loc f on_block
1680 else if err == eWOULDBLOCK || err == eAGAIN
1685 -- -----------------------------------------------------------------------------
1686 -- wrappers to platform-specific constants:
1688 foreign import ccall unsafe "__hscore_supportsTextMode"
1689 tEXT_MODE_SEEK_ALLOWED :: Bool
1691 foreign import ccall unsafe "__hscore_bufsiz" dEFAULT_BUFFER_SIZE :: Int
1692 foreign import ccall unsafe "__hscore_seek_cur" sEEK_CUR :: CInt
1693 foreign import ccall unsafe "__hscore_seek_set" sEEK_SET :: CInt
1694 foreign import ccall unsafe "__hscore_seek_end" sEEK_END :: CInt