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, fdToHandle', 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,
63 import System.IO.Error
64 import System.Posix.Internals
70 import GHC.Read ( Read )
75 import GHC.Num ( Integer(..), Num(..) )
77 import GHC.Real ( toInteger )
78 #if defined(DEBUG_DUMP)
84 -- -----------------------------------------------------------------------------
87 -- hWaitForInput blocks (should use a timeout)
89 -- unbuffered hGetLine is a bit dodgy
91 -- hSetBuffering: can't change buffering on a stream,
92 -- when the read buffer is non-empty? (no way to flush the buffer)
94 -- ---------------------------------------------------------------------------
95 -- Are files opened by default in text or binary mode, if the user doesn't
98 dEFAULT_OPEN_IN_BINARY_MODE = False :: Bool
100 -- ---------------------------------------------------------------------------
101 -- Creating a new handle
103 newFileHandle :: FilePath -> (MVar Handle__ -> IO ()) -> Handle__ -> IO Handle
104 newFileHandle filepath finalizer hc = do
106 addMVarFinalizer m (finalizer m)
107 return (FileHandle filepath m)
109 -- ---------------------------------------------------------------------------
110 -- Working with Handles
113 In the concurrent world, handles are locked during use. This is done
114 by wrapping an MVar around the handle which acts as a mutex over
115 operations on the handle.
117 To avoid races, we use the following bracketing operations. The idea
118 is to obtain the lock, do some operation and replace the lock again,
119 whether the operation succeeded or failed. We also want to handle the
120 case where the thread receives an exception while processing the IO
121 operation: in these cases we also want to relinquish the lock.
123 There are three versions of @withHandle@: corresponding to the three
124 possible combinations of:
126 - the operation may side-effect the handle
127 - the operation may return a result
129 If the operation generates an error or an exception is raised, the
130 original handle is always replaced [ this is the case at the moment,
131 but we might want to revisit this in the future --SDM ].
134 {-# INLINE withHandle #-}
135 withHandle :: String -> Handle -> (Handle__ -> IO (Handle__,a)) -> IO a
136 withHandle fun h@(FileHandle _ m) act = withHandle' fun h m act
137 withHandle fun h@(DuplexHandle _ m _) act = withHandle' fun h m act
139 withHandle' :: String -> Handle -> MVar Handle__
140 -> (Handle__ -> IO (Handle__,a)) -> IO a
141 withHandle' fun h m act =
144 checkBufferInvariants h_
145 (h',v) <- catchException (act h_)
146 (\ err -> putMVar m h_ >>
148 IOException ex -> ioError (augmentIOError ex fun h)
150 checkBufferInvariants h'
154 {-# INLINE withHandle_ #-}
155 withHandle_ :: String -> Handle -> (Handle__ -> IO a) -> IO a
156 withHandle_ fun h@(FileHandle _ m) act = withHandle_' fun h m act
157 withHandle_ fun h@(DuplexHandle _ m _) act = withHandle_' fun h m act
159 withHandle_' :: String -> Handle -> MVar Handle__ -> (Handle__ -> IO a) -> IO a
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 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" 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
535 Unix has broken semantics when it comes to non-blocking I/O: you can
536 set the O_NONBLOCK flag on an FD, but it applies to the all other FDs
537 attached to the same underlying file, pipe or TTY; there's no way to
538 have private non-blocking behaviour for an FD. See bug #724.
540 We fix this by only setting O_NONBLOCK on FDs that we create; FDs that
541 come from external sources or are exposed externally are left in
542 blocking mode. This solution has some problems though. We can't
543 completely simulate a non-blocking read without O_NONBLOCK: several
544 cases are wrong here. The cases that are wrong:
546 * reading/writing to a blocking FD in non-threaded mode.
547 In threaded mode, we just make a safe call to read().
548 In non-threaded mode we call select() before attempting to read,
549 but that leaves a small race window where the data can be read
550 from the file descriptor before we issue our blocking read().
551 * readRawBufferNoBlock for a blocking FD
554 readRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
555 readRawBuffer loc fd is_nonblock buf off len
556 | is_nonblock = unsafe_read
557 | threaded = safe_read
558 | otherwise = do r <- throwErrnoIfMinus1 loc
559 (fdReady (fromIntegral fd) 0 0 False)
562 else do threadWaitRead (fromIntegral fd); unsafe_read
564 do_read call = throwErrnoIfMinus1RetryMayBlock loc call
565 (threadWaitRead (fromIntegral fd))
566 unsafe_read = do_read (read_rawBuffer fd buf off len)
567 safe_read = do_read (safe_read_rawBuffer fd buf off len)
569 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
570 readRawBufferPtr loc fd is_nonblock buf off len
571 | is_nonblock = unsafe_read
572 | threaded = safe_read
573 | otherwise = do r <- throwErrnoIfMinus1 loc
574 (fdReady (fromIntegral fd) 0 0 False)
577 else do threadWaitRead (fromIntegral fd); unsafe_read
579 do_read call = throwErrnoIfMinus1RetryMayBlock loc call
580 (threadWaitRead (fromIntegral fd))
581 unsafe_read = do_read (read_off fd buf off len)
582 safe_read = do_read (safe_read_off fd buf off len)
584 readRawBufferNoBlock :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
585 readRawBufferNoBlock loc fd is_nonblock buf off len
586 | is_nonblock = unsafe_read
587 | otherwise = do r <- fdReady (fromIntegral fd) 0 0 False
588 if r /= 0 then safe_read
590 -- XXX see note [nonblock]
592 do_read call = throwErrnoIfMinus1RetryOnBlock loc call (return 0)
593 unsafe_read = do_read (read_rawBuffer fd buf off len)
594 safe_read = do_read (safe_read_rawBuffer fd buf off len)
596 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
597 writeRawBuffer loc fd is_nonblock buf off len
598 | is_nonblock = unsafe_write
599 | threaded = safe_write
600 | otherwise = do r <- fdReady (fromIntegral fd) 1 0 False
603 else do threadWaitWrite (fromIntegral fd); unsafe_write
605 do_write call = throwErrnoIfMinus1RetryMayBlock loc call
606 (threadWaitWrite (fromIntegral fd))
607 unsafe_write = do_write (write_rawBuffer fd buf off len)
608 safe_write = do_write (safe_write_rawBuffer (fromIntegral fd) buf off len)
610 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
611 writeRawBufferPtr loc fd is_nonblock buf off len
612 | is_nonblock = unsafe_write
613 | threaded = safe_write
614 | otherwise = do r <- fdReady (fromIntegral fd) 1 0 False
617 else do threadWaitWrite (fromIntegral fd); unsafe_write
619 do_write call = throwErrnoIfMinus1RetryMayBlock loc call
620 (threadWaitWrite (fromIntegral fd))
621 unsafe_write = do_write (write_off fd buf off len)
622 safe_write = do_write (safe_write_off (fromIntegral fd) buf off len)
624 foreign import ccall unsafe "__hscore_PrelHandle_read"
625 read_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
627 foreign import ccall unsafe "__hscore_PrelHandle_read"
628 read_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
630 foreign import ccall unsafe "__hscore_PrelHandle_write"
631 write_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
633 foreign import ccall unsafe "__hscore_PrelHandle_write"
634 write_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
636 foreign import ccall safe "fdReady"
637 fdReady :: CInt -> CInt -> CInt -> Bool -> IO CInt
639 #else /* mingw32_HOST_OS.... */
641 readRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
642 readRawBuffer loc fd is_stream buf off len
643 | threaded = blockingReadRawBuffer loc fd is_stream buf off len
644 | otherwise = asyncReadRawBuffer loc fd is_stream buf off len
646 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
647 readRawBufferPtr loc fd is_stream buf off len
648 | threaded = blockingReadRawBufferPtr loc fd is_stream buf off len
649 | otherwise = asyncReadRawBufferPtr loc fd is_stream buf off len
651 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
652 writeRawBuffer loc fd is_stream buf off len
653 | threaded = blockingWriteRawBuffer loc fd is_stream buf off len
654 | otherwise = asyncWriteRawBuffer loc fd is_stream buf off len
656 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
657 writeRawBufferPtr loc fd is_stream buf off len
658 | threaded = blockingWriteRawBufferPtr loc fd is_stream buf off len
659 | otherwise = asyncWriteRawBufferPtr loc fd is_stream buf off len
661 -- ToDo: we don't have a non-blocking primitve read on Win32
662 readRawBufferNoBlock :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
663 readRawBufferNoBlock = readRawBuffer
665 -- Async versions of the read/write primitives, for the non-threaded RTS
667 asyncReadRawBuffer loc fd is_stream buf off len = do
668 (l, rc) <- asyncReadBA (fromIntegral fd) (if is_stream then 1 else 0)
669 (fromIntegral len) off buf
672 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
673 else return (fromIntegral l)
675 asyncReadRawBufferPtr loc fd is_stream buf off len = do
676 (l, rc) <- asyncRead (fromIntegral fd) (if is_stream then 1 else 0)
677 (fromIntegral len) (buf `plusPtr` off)
680 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
681 else return (fromIntegral l)
683 asyncWriteRawBuffer loc fd is_stream buf off len = do
684 (l, rc) <- asyncWriteBA (fromIntegral fd) (if is_stream then 1 else 0)
685 (fromIntegral len) off buf
688 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
689 else return (fromIntegral l)
691 asyncWriteRawBufferPtr loc fd is_stream buf off len = do
692 (l, rc) <- asyncWrite (fromIntegral fd) (if is_stream then 1 else 0)
693 (fromIntegral len) (buf `plusPtr` off)
696 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
697 else return (fromIntegral l)
699 -- Blocking versions of the read/write primitives, for the threaded RTS
701 blockingReadRawBuffer loc fd True buf off len =
702 throwErrnoIfMinus1Retry loc $
703 safe_recv_rawBuffer fd buf off len
704 blockingReadRawBuffer loc fd False buf off len =
705 throwErrnoIfMinus1Retry loc $
706 safe_read_rawBuffer fd buf off len
708 blockingReadRawBufferPtr loc fd True buf off len =
709 throwErrnoIfMinus1Retry loc $
710 safe_recv_off fd buf off len
711 blockingReadRawBufferPtr loc fd False buf off len =
712 throwErrnoIfMinus1Retry loc $
713 safe_read_off fd buf off len
715 blockingWriteRawBuffer loc fd True buf off len =
716 throwErrnoIfMinus1Retry loc $
717 safe_send_rawBuffer fd buf off len
718 blockingWriteRawBuffer loc fd False buf off len =
719 throwErrnoIfMinus1Retry loc $
720 safe_write_rawBuffer fd buf off len
722 blockingWriteRawBufferPtr loc fd True buf off len =
723 throwErrnoIfMinus1Retry loc $
724 safe_send_off fd buf off len
725 blockingWriteRawBufferPtr loc fd False buf off len =
726 throwErrnoIfMinus1Retry loc $
727 safe_write_off fd buf off len
729 -- NOTE: "safe" versions of the read/write calls for use by the threaded RTS.
730 -- These calls may block, but that's ok.
732 foreign import ccall safe "__hscore_PrelHandle_recv"
733 safe_recv_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
735 foreign import ccall safe "__hscore_PrelHandle_recv"
736 safe_recv_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
738 foreign import ccall safe "__hscore_PrelHandle_send"
739 safe_send_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
741 foreign import ccall safe "__hscore_PrelHandle_send"
742 safe_send_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
746 foreign import ccall "rtsSupportsBoundThreads" threaded :: Bool
748 foreign import ccall safe "__hscore_PrelHandle_read"
749 safe_read_rawBuffer :: FD -> RawBuffer -> Int -> CInt -> IO CInt
751 foreign import ccall safe "__hscore_PrelHandle_read"
752 safe_read_off :: FD -> Ptr CChar -> Int -> CInt -> IO CInt
754 foreign import ccall safe "__hscore_PrelHandle_write"
755 safe_write_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
757 foreign import ccall safe "__hscore_PrelHandle_write"
758 safe_write_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
760 -- ---------------------------------------------------------------------------
763 -- Three handles are allocated during program initialisation. The first
764 -- two manage input or output from the Haskell program's standard input
765 -- or output channel respectively. The third manages output to the
766 -- standard error channel. These handles are initially open.
772 -- | A handle managing input from the Haskell program's standard input channel.
774 stdin = unsafePerformIO $ do
775 -- ToDo: acquire lock
776 -- We don't set non-blocking mode on standard handles, because it may
777 -- confuse other applications attached to the same TTY/pipe
778 -- see Note [nonblock]
779 (buf, bmode) <- getBuffer fd_stdin ReadBuffer
780 mkStdHandle fd_stdin "<stdin>" ReadHandle buf bmode
782 -- | A handle managing output to the Haskell program's standard output channel.
784 stdout = unsafePerformIO $ do
785 -- ToDo: acquire lock
786 -- We don't set non-blocking mode on standard handles, because it may
787 -- confuse other applications attached to the same TTY/pipe
788 -- see Note [nonblock]
789 (buf, bmode) <- getBuffer fd_stdout WriteBuffer
790 mkStdHandle fd_stdout "<stdout>" WriteHandle buf bmode
792 -- | A handle managing output to the Haskell program's standard error channel.
794 stderr = unsafePerformIO $ do
795 -- ToDo: acquire lock
796 -- We don't set non-blocking mode on standard handles, because it may
797 -- confuse other applications attached to the same TTY/pipe
798 -- see Note [nonblock]
800 mkStdHandle fd_stderr "<stderr>" WriteHandle buf NoBuffering
802 -- ---------------------------------------------------------------------------
803 -- Opening and Closing Files
805 addFilePathToIOError fun fp (IOError h iot _ str _)
806 = IOError h iot fun str (Just fp)
808 -- | Computation 'openFile' @file mode@ allocates and returns a new, open
809 -- handle to manage the file @file@. It manages input if @mode@
810 -- is 'ReadMode', output if @mode@ is 'WriteMode' or 'AppendMode',
811 -- and both input and output if mode is 'ReadWriteMode'.
813 -- If the file does not exist and it is opened for output, it should be
814 -- created as a new file. If @mode@ is 'WriteMode' and the file
815 -- already exists, then it should be truncated to zero length.
816 -- Some operating systems delete empty files, so there is no guarantee
817 -- that the file will exist following an 'openFile' with @mode@
818 -- 'WriteMode' unless it is subsequently written to successfully.
819 -- The handle is positioned at the end of the file if @mode@ is
820 -- 'AppendMode', and otherwise at the beginning (in which case its
821 -- internal position is 0).
822 -- The initial buffer mode is implementation-dependent.
824 -- This operation may fail with:
826 -- * 'isAlreadyInUseError' if the file is already open and cannot be reopened;
828 -- * 'isDoesNotExistError' if the file does not exist; or
830 -- * 'isPermissionError' if the user does not have permission to open the file.
832 -- Note: if you will be working with files containing binary data, you'll want to
833 -- be using 'openBinaryFile'.
834 openFile :: FilePath -> IOMode -> IO Handle
837 (openFile' fp im dEFAULT_OPEN_IN_BINARY_MODE)
838 (\e -> ioError (addFilePathToIOError "openFile" fp e))
840 -- | Like 'openFile', but open the file in binary mode.
841 -- On Windows, reading a file in text mode (which is the default)
842 -- will translate CRLF to LF, and writing will translate LF to CRLF.
843 -- This is usually what you want with text files. With binary files
844 -- this is undesirable; also, as usual under Microsoft operating systems,
845 -- text mode treats control-Z as EOF. Binary mode turns off all special
846 -- treatment of end-of-line and end-of-file characters.
847 -- (See also 'hSetBinaryMode'.)
849 openBinaryFile :: FilePath -> IOMode -> IO Handle
850 openBinaryFile fp m =
852 (openFile' fp m True)
853 (\e -> ioError (addFilePathToIOError "openBinaryFile" fp e))
855 openFile' filepath mode binary =
856 withCString filepath $ \ f ->
859 oflags1 = case mode of
860 ReadMode -> read_flags
861 #ifdef mingw32_HOST_OS
862 WriteMode -> write_flags .|. o_TRUNC
864 WriteMode -> write_flags
866 ReadWriteMode -> rw_flags
867 AppendMode -> append_flags
873 oflags = oflags1 .|. binary_flags
876 -- the old implementation had a complicated series of three opens,
877 -- which is perhaps because we have to be careful not to open
878 -- directories. However, the man pages I've read say that open()
879 -- always returns EISDIR if the file is a directory and was opened
880 -- for writing, so I think we're ok with a single open() here...
881 fd <- throwErrnoIfMinus1Retry "openFile"
882 (c_open f (fromIntegral oflags) 0o666)
886 h <- fdToHandle' fd (Just fd_type) False filepath mode binary
887 `catchException` \e -> do c_close fd; throw e
888 -- NB. don't forget to close the FD if fdToHandle' fails, otherwise
890 -- ASSERT: if we just created the file, then fdToHandle' won't fail
891 -- (so we don't need to worry about removing the newly created file
892 -- in the event of an error).
894 #ifndef mingw32_HOST_OS
895 -- we want to truncate() if this is an open in WriteMode, but only
896 -- if the target is a RegularFile. ftruncate() fails on special files
898 if mode == WriteMode && fd_type == RegularFile
899 then throwErrnoIf (/=0) "openFile"
906 std_flags = o_NONBLOCK .|. o_NOCTTY
907 output_flags = std_flags .|. o_CREAT
908 read_flags = std_flags .|. o_RDONLY
909 write_flags = output_flags .|. o_WRONLY
910 rw_flags = output_flags .|. o_RDWR
911 append_flags = write_flags .|. o_APPEND
913 -- ---------------------------------------------------------------------------
916 fdToHandle' :: FD -> Maybe FDType -> Bool -> FilePath -> IOMode -> Bool -> IO Handle
917 fdToHandle' fd mb_fd_type is_socket filepath mode binary = do
918 -- turn on non-blocking mode
921 #ifdef mingw32_HOST_OS
922 -- On Windows, the is_stream flag indicates that the Handle is a socket
923 let is_stream = is_socket
925 -- On Unix, the is_stream flag indicates that the FD is non-blocking
929 let (ha_type, write) =
931 ReadMode -> ( ReadHandle, False )
932 WriteMode -> ( WriteHandle, True )
933 ReadWriteMode -> ( ReadWriteHandle, True )
934 AppendMode -> ( AppendHandle, True )
936 -- open() won't tell us if it was a directory if we only opened for
937 -- reading, so check again.
945 ioException (IOError Nothing InappropriateType "openFile"
946 "is a directory" Nothing)
948 -- regular files need to be locked
950 #ifndef mingw32_HOST_OS
951 r <- lockFile fd (fromBool write) 1{-exclusive-}
953 ioException (IOError Nothing ResourceBusy "openFile"
954 "file is locked" Nothing)
956 mkFileHandle fd is_stream filepath ha_type binary
959 -- only *Streams* can be DuplexHandles. Other read/write
960 -- Handles must share a buffer.
961 | ReadWriteHandle <- ha_type ->
962 mkDuplexHandle fd is_stream filepath binary
964 mkFileHandle fd is_stream filepath ha_type binary
967 mkFileHandle fd is_stream filepath ha_type binary
969 fdToHandle :: FD -> IO Handle
972 let fd_str = "<file descriptor: " ++ show fd ++ ">"
973 fdToHandle' fd Nothing False{-XXX!-} fd_str mode True{-bin mode-}
976 #ifndef mingw32_HOST_OS
977 foreign import ccall unsafe "lockFile"
978 lockFile :: CInt -> CInt -> CInt -> IO CInt
980 foreign import ccall unsafe "unlockFile"
981 unlockFile :: CInt -> IO CInt
984 mkStdHandle :: FD -> FilePath -> HandleType -> IORef Buffer -> BufferMode
986 mkStdHandle fd filepath ha_type buf bmode = do
987 spares <- newIORef BufferListNil
988 newFileHandle filepath (stdHandleFinalizer filepath)
989 (Handle__ { haFD = fd,
991 haIsBin = dEFAULT_OPEN_IN_BINARY_MODE,
992 haIsStream = False, -- means FD is blocking on Unix
993 haBufferMode = bmode,
996 haOtherSide = Nothing
999 mkFileHandle :: FD -> Bool -> FilePath -> HandleType -> Bool -> IO Handle
1000 mkFileHandle fd is_stream filepath ha_type binary = do
1001 (buf, bmode) <- getBuffer fd (initBufferState ha_type)
1003 #ifdef mingw32_HOST_OS
1004 -- On Windows, if this is a read/write handle and we are in text mode,
1005 -- turn off buffering. We don't correctly handle the case of switching
1006 -- from read mode to write mode on a buffered text-mode handle, see bug
1008 bmode <- case ha_type of
1009 ReadWriteHandle | not binary -> return NoBuffering
1010 _other -> return bmode
1013 spares <- newIORef BufferListNil
1014 newFileHandle filepath (handleFinalizer filepath)
1015 (Handle__ { haFD = fd,
1018 haIsStream = is_stream,
1019 haBufferMode = bmode,
1022 haOtherSide = Nothing
1025 mkDuplexHandle :: FD -> Bool -> FilePath -> Bool -> IO Handle
1026 mkDuplexHandle fd is_stream filepath binary = do
1027 (w_buf, w_bmode) <- getBuffer fd WriteBuffer
1028 w_spares <- newIORef BufferListNil
1030 Handle__ { haFD = fd,
1031 haType = WriteHandle,
1033 haIsStream = is_stream,
1034 haBufferMode = w_bmode,
1036 haBuffers = w_spares,
1037 haOtherSide = Nothing
1039 write_side <- newMVar w_handle_
1041 (r_buf, r_bmode) <- getBuffer fd ReadBuffer
1042 r_spares <- newIORef BufferListNil
1044 Handle__ { haFD = fd,
1045 haType = ReadHandle,
1047 haIsStream = is_stream,
1048 haBufferMode = r_bmode,
1050 haBuffers = r_spares,
1051 haOtherSide = Just write_side
1053 read_side <- newMVar r_handle_
1055 addMVarFinalizer write_side (handleFinalizer filepath write_side)
1056 return (DuplexHandle filepath read_side write_side)
1059 initBufferState ReadHandle = ReadBuffer
1060 initBufferState _ = WriteBuffer
1062 -- ---------------------------------------------------------------------------
1065 -- | Computation 'hClose' @hdl@ makes handle @hdl@ closed. Before the
1066 -- computation finishes, if @hdl@ is writable its buffer is flushed as
1068 -- Performing 'hClose' on a handle that has already been closed has no effect;
1069 -- doing so not an error. All other operations on a closed handle will fail.
1070 -- If 'hClose' fails for any reason, any further operations (apart from
1071 -- 'hClose') on the handle will still fail as if @hdl@ had been successfully
1074 hClose :: Handle -> IO ()
1075 hClose h@(FileHandle _ m) = hClose' h m
1076 hClose h@(DuplexHandle _ r w) = hClose' h w >> hClose' h r
1078 hClose' h m = withHandle__' "hClose" h m $ hClose_help
1080 -- hClose_help is also called by lazyRead (in PrelIO) when EOF is read
1081 -- or an IO error occurs on a lazy stream. The semi-closed Handle is
1082 -- then closed immediately. We have to be careful with DuplexHandles
1083 -- though: we have to leave the closing to the finalizer in that case,
1084 -- because the write side may still be in use.
1085 hClose_help :: Handle__ -> IO Handle__
1086 hClose_help handle_ =
1087 case haType handle_ of
1088 ClosedHandle -> return handle_
1089 _ -> do flushWriteBufferOnly handle_ -- interruptible
1090 hClose_handle_ handle_
1092 hClose_handle_ handle_ = do
1093 let fd = haFD handle_
1095 -- close the file descriptor, but not when this is the read
1096 -- side of a duplex handle.
1097 case haOtherSide handle_ of
1099 throwErrnoIfMinus1Retry_ "hClose"
1100 #ifdef mingw32_HOST_OS
1101 (closeFd (haIsStream handle_) fd)
1107 -- free the spare buffers
1108 writeIORef (haBuffers handle_) BufferListNil
1109 writeIORef (haBuffer handle_) noBuffer
1111 #ifndef mingw32_HOST_OS
1116 -- we must set the fd to -1, because the finalizer is going
1117 -- to run eventually and try to close/unlock it.
1118 return (handle_{ haFD = -1,
1119 haType = ClosedHandle
1122 {-# NOINLINE noBuffer #-}
1123 noBuffer = unsafePerformIO $ allocateBuffer 1 ReadBuffer
1125 -----------------------------------------------------------------------------
1126 -- Detecting and changing the size of a file
1128 -- | For a handle @hdl@ which attached to a physical file,
1129 -- 'hFileSize' @hdl@ returns the size of that file in 8-bit bytes.
1131 hFileSize :: Handle -> IO Integer
1133 withHandle_ "hFileSize" handle $ \ handle_ -> do
1134 case haType handle_ of
1135 ClosedHandle -> ioe_closedHandle
1136 SemiClosedHandle -> ioe_closedHandle
1137 _ -> do flushWriteBufferOnly handle_
1138 r <- fdFileSize (haFD handle_)
1141 else ioException (IOError Nothing InappropriateType "hFileSize"
1142 "not a regular file" Nothing)
1145 -- | 'hSetFileSize' @hdl@ @size@ truncates the physical file with handle @hdl@ to @size@ bytes.
1147 hSetFileSize :: Handle -> Integer -> IO ()
1148 hSetFileSize handle size =
1149 withHandle_ "hSetFileSize" handle $ \ handle_ -> do
1150 case haType handle_ of
1151 ClosedHandle -> ioe_closedHandle
1152 SemiClosedHandle -> ioe_closedHandle
1153 _ -> do flushWriteBufferOnly handle_
1154 throwErrnoIf (/=0) "hSetFileSize"
1155 (c_ftruncate (haFD handle_) (fromIntegral size))
1158 -- ---------------------------------------------------------------------------
1159 -- Detecting the End of Input
1161 -- | For a readable handle @hdl@, 'hIsEOF' @hdl@ returns
1162 -- 'True' if no further input can be taken from @hdl@ or for a
1163 -- physical file, if the current I\/O position is equal to the length of
1164 -- the file. Otherwise, it returns 'False'.
1166 hIsEOF :: Handle -> IO Bool
1169 (do hLookAhead handle; return False)
1170 (\e -> if isEOFError e then return True else ioError e)
1172 -- | The computation 'isEOF' is identical to 'hIsEOF',
1173 -- except that it works only on 'stdin'.
1176 isEOF = hIsEOF stdin
1178 -- ---------------------------------------------------------------------------
1181 -- | Computation 'hLookAhead' returns the next character from the handle
1182 -- without removing it from the input buffer, blocking until a character
1185 -- This operation may fail with:
1187 -- * 'isEOFError' if the end of file has been reached.
1189 hLookAhead :: Handle -> IO Char
1190 hLookAhead handle = do
1191 wantReadableHandle "hLookAhead" handle $ \handle_ -> do
1192 let ref = haBuffer handle_
1194 is_line = haBufferMode handle_ == LineBuffering
1195 buf <- readIORef ref
1197 -- fill up the read buffer if necessary
1198 new_buf <- if bufferEmpty buf
1199 then fillReadBuffer fd True (haIsStream handle_) buf
1202 writeIORef ref new_buf
1204 (c,_) <- readCharFromBuffer (bufBuf buf) (bufRPtr buf)
1207 -- ---------------------------------------------------------------------------
1208 -- Buffering Operations
1210 -- Three kinds of buffering are supported: line-buffering,
1211 -- block-buffering or no-buffering. See GHC.IOBase for definition and
1212 -- further explanation of what the type represent.
1214 -- | Computation 'hSetBuffering' @hdl mode@ sets the mode of buffering for
1215 -- handle @hdl@ on subsequent reads and writes.
1217 -- If the buffer mode is changed from 'BlockBuffering' or
1218 -- 'LineBuffering' to 'NoBuffering', then
1220 -- * if @hdl@ is writable, the buffer is flushed as for 'hFlush';
1222 -- * if @hdl@ is not writable, the contents of the buffer is discarded.
1224 -- This operation may fail with:
1226 -- * 'isPermissionError' if the handle has already been used for reading
1227 -- or writing and the implementation does not allow the buffering mode
1230 hSetBuffering :: Handle -> BufferMode -> IO ()
1231 hSetBuffering handle mode =
1232 withAllHandles__ "hSetBuffering" handle $ \ handle_ -> do
1233 case haType handle_ of
1234 ClosedHandle -> ioe_closedHandle
1237 - we flush the old buffer regardless of whether
1238 the new buffer could fit the contents of the old buffer
1240 - allow a handle's buffering to change even if IO has
1241 occurred (ANSI C spec. does not allow this, nor did
1242 the previous implementation of IO.hSetBuffering).
1243 - a non-standard extension is to allow the buffering
1244 of semi-closed handles to change [sof 6/98]
1248 let state = initBufferState (haType handle_)
1251 -- we always have a 1-character read buffer for
1252 -- unbuffered handles: it's needed to
1253 -- support hLookAhead.
1254 NoBuffering -> allocateBuffer 1 ReadBuffer
1255 LineBuffering -> allocateBuffer dEFAULT_BUFFER_SIZE state
1256 BlockBuffering Nothing -> allocateBuffer dEFAULT_BUFFER_SIZE state
1257 BlockBuffering (Just n) | n <= 0 -> ioe_bufsiz n
1258 | otherwise -> allocateBuffer n state
1259 writeIORef (haBuffer handle_) new_buf
1261 -- for input terminals we need to put the terminal into
1262 -- cooked or raw mode depending on the type of buffering.
1263 is_tty <- fdIsTTY (haFD handle_)
1264 when (is_tty && isReadableHandleType (haType handle_)) $
1266 #ifndef mingw32_HOST_OS
1267 -- 'raw' mode under win32 is a bit too specialised (and troublesome
1268 -- for most common uses), so simply disable its use here.
1269 NoBuffering -> setCooked (haFD handle_) False
1271 NoBuffering -> return ()
1273 _ -> setCooked (haFD handle_) True
1275 -- throw away spare buffers, they might be the wrong size
1276 writeIORef (haBuffers handle_) BufferListNil
1278 return (handle_{ haBufferMode = mode })
1280 -- -----------------------------------------------------------------------------
1283 -- | The action 'hFlush' @hdl@ causes any items buffered for output
1284 -- in handle @hdl@ to be sent immediately to the operating system.
1286 -- This operation may fail with:
1288 -- * 'isFullError' if the device is full;
1290 -- * 'isPermissionError' if a system resource limit would be exceeded.
1291 -- It is unspecified whether the characters in the buffer are discarded
1292 -- or retained under these circumstances.
1294 hFlush :: Handle -> IO ()
1296 wantWritableHandle "hFlush" handle $ \ handle_ -> do
1297 buf <- readIORef (haBuffer handle_)
1298 if bufferIsWritable buf && not (bufferEmpty buf)
1299 then do flushed_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
1300 writeIORef (haBuffer handle_) flushed_buf
1304 -- -----------------------------------------------------------------------------
1305 -- Repositioning Handles
1307 data HandlePosn = HandlePosn Handle HandlePosition
1309 instance Eq HandlePosn where
1310 (HandlePosn h1 p1) == (HandlePosn h2 p2) = p1==p2 && h1==h2
1312 instance Show HandlePosn where
1313 showsPrec p (HandlePosn h pos) =
1314 showsPrec p h . showString " at position " . shows pos
1316 -- HandlePosition is the Haskell equivalent of POSIX' off_t.
1317 -- We represent it as an Integer on the Haskell side, but
1318 -- cheat slightly in that hGetPosn calls upon a C helper
1319 -- that reports the position back via (merely) an Int.
1320 type HandlePosition = Integer
1322 -- | Computation 'hGetPosn' @hdl@ returns the current I\/O position of
1323 -- @hdl@ as a value of the abstract type 'HandlePosn'.
1325 hGetPosn :: Handle -> IO HandlePosn
1326 hGetPosn handle = do
1327 posn <- hTell handle
1328 return (HandlePosn handle posn)
1330 -- | If a call to 'hGetPosn' @hdl@ returns a position @p@,
1331 -- then computation 'hSetPosn' @p@ sets the position of @hdl@
1332 -- to the position it held at the time of the call to 'hGetPosn'.
1334 -- This operation may fail with:
1336 -- * 'isPermissionError' if a system resource limit would be exceeded.
1338 hSetPosn :: HandlePosn -> IO ()
1339 hSetPosn (HandlePosn h i) = hSeek h AbsoluteSeek i
1341 -- ---------------------------------------------------------------------------
1344 -- | A mode that determines the effect of 'hSeek' @hdl mode i@, as follows:
1346 = AbsoluteSeek -- ^ the position of @hdl@ is set to @i@.
1347 | RelativeSeek -- ^ the position of @hdl@ is set to offset @i@
1348 -- from the current position.
1349 | SeekFromEnd -- ^ the position of @hdl@ is set to offset @i@
1350 -- from the end of the file.
1351 deriving (Eq, Ord, Ix, Enum, Read, Show)
1354 - when seeking using `SeekFromEnd', positive offsets (>=0) means
1355 seeking at or past EOF.
1357 - we possibly deviate from the report on the issue of seeking within
1358 the buffer and whether to flush it or not. The report isn't exactly
1362 -- | Computation 'hSeek' @hdl mode i@ sets the position of handle
1363 -- @hdl@ depending on @mode@.
1364 -- The offset @i@ is given in terms of 8-bit bytes.
1366 -- If @hdl@ is block- or line-buffered, then seeking to a position which is not
1367 -- in the current buffer will first cause any items in the output buffer to be
1368 -- written to the device, and then cause the input buffer to be discarded.
1369 -- Some handles may not be seekable (see 'hIsSeekable'), or only support a
1370 -- subset of the possible positioning operations (for instance, it may only
1371 -- be possible to seek to the end of a tape, or to a positive offset from
1372 -- the beginning or current position).
1373 -- It is not possible to set a negative I\/O position, or for
1374 -- a physical file, an I\/O position beyond the current end-of-file.
1376 -- This operation may fail with:
1378 -- * 'isPermissionError' if a system resource limit would be exceeded.
1380 hSeek :: Handle -> SeekMode -> Integer -> IO ()
1381 hSeek handle mode offset =
1382 wantSeekableHandle "hSeek" handle $ \ handle_ -> do
1384 puts ("hSeek " ++ show (mode,offset) ++ "\n")
1386 let ref = haBuffer handle_
1387 buf <- readIORef ref
1393 throwErrnoIfMinus1Retry_ "hSeek"
1394 (c_lseek (haFD handle_) (fromIntegral offset) whence)
1397 whence = case mode of
1398 AbsoluteSeek -> sEEK_SET
1399 RelativeSeek -> sEEK_CUR
1400 SeekFromEnd -> sEEK_END
1402 if bufferIsWritable buf
1403 then do new_buf <- flushWriteBuffer fd (haIsStream handle_) buf
1404 writeIORef ref new_buf
1408 if mode == RelativeSeek && offset >= 0 && offset < fromIntegral (w - r)
1409 then writeIORef ref buf{ bufRPtr = r + fromIntegral offset }
1412 new_buf <- flushReadBuffer (haFD handle_) buf
1413 writeIORef ref new_buf
1417 hTell :: Handle -> IO Integer
1419 wantSeekableHandle "hGetPosn" handle $ \ handle_ -> do
1421 #if defined(mingw32_HOST_OS)
1422 -- urgh, on Windows we have to worry about \n -> \r\n translation,
1423 -- so we can't easily calculate the file position using the
1424 -- current buffer size. Just flush instead.
1427 let fd = haFD handle_
1428 posn <- fromIntegral `liftM`
1429 throwErrnoIfMinus1Retry "hGetPosn"
1430 (c_lseek fd 0 sEEK_CUR)
1432 let ref = haBuffer handle_
1433 buf <- readIORef ref
1436 | bufferIsWritable buf = posn + fromIntegral (bufWPtr buf)
1437 | otherwise = posn - fromIntegral (bufWPtr buf - bufRPtr buf)
1439 puts ("\nhGetPosn: (fd, posn, real_posn) = " ++ show (fd, posn, real_posn) ++ "\n")
1440 puts (" (bufWPtr, bufRPtr) = " ++ show (bufWPtr buf, bufRPtr buf) ++ "\n")
1444 -- -----------------------------------------------------------------------------
1445 -- Handle Properties
1447 -- A number of operations return information about the properties of a
1448 -- handle. Each of these operations returns `True' if the handle has
1449 -- the specified property, and `False' otherwise.
1451 hIsOpen :: Handle -> IO Bool
1453 withHandle_ "hIsOpen" handle $ \ handle_ -> do
1454 case haType handle_ of
1455 ClosedHandle -> return False
1456 SemiClosedHandle -> return False
1459 hIsClosed :: Handle -> IO Bool
1461 withHandle_ "hIsClosed" handle $ \ handle_ -> do
1462 case haType handle_ of
1463 ClosedHandle -> return True
1466 {- not defined, nor exported, but mentioned
1467 here for documentation purposes:
1469 hSemiClosed :: Handle -> IO Bool
1473 return (not (ho || hc))
1476 hIsReadable :: Handle -> IO Bool
1477 hIsReadable (DuplexHandle _ _ _) = return True
1478 hIsReadable handle =
1479 withHandle_ "hIsReadable" handle $ \ handle_ -> do
1480 case haType handle_ of
1481 ClosedHandle -> ioe_closedHandle
1482 SemiClosedHandle -> ioe_closedHandle
1483 htype -> return (isReadableHandleType htype)
1485 hIsWritable :: Handle -> IO Bool
1486 hIsWritable (DuplexHandle _ _ _) = return True
1487 hIsWritable handle =
1488 withHandle_ "hIsWritable" handle $ \ handle_ -> do
1489 case haType handle_ of
1490 ClosedHandle -> ioe_closedHandle
1491 SemiClosedHandle -> ioe_closedHandle
1492 htype -> return (isWritableHandleType htype)
1494 -- | Computation 'hGetBuffering' @hdl@ returns the current buffering mode
1497 hGetBuffering :: Handle -> IO BufferMode
1498 hGetBuffering handle =
1499 withHandle_ "hGetBuffering" handle $ \ handle_ -> do
1500 case haType handle_ of
1501 ClosedHandle -> ioe_closedHandle
1503 -- We're being non-standard here, and allow the buffering
1504 -- of a semi-closed handle to be queried. -- sof 6/98
1505 return (haBufferMode handle_) -- could be stricter..
1507 hIsSeekable :: Handle -> IO Bool
1508 hIsSeekable handle =
1509 withHandle_ "hIsSeekable" handle $ \ handle_ -> do
1510 case haType handle_ of
1511 ClosedHandle -> ioe_closedHandle
1512 SemiClosedHandle -> ioe_closedHandle
1513 AppendHandle -> return False
1514 _ -> do t <- fdType (haFD handle_)
1515 return ((t == RegularFile || t == RawDevice)
1516 && (haIsBin handle_ || tEXT_MODE_SEEK_ALLOWED))
1518 -- -----------------------------------------------------------------------------
1519 -- Changing echo status (Non-standard GHC extensions)
1521 -- | Set the echoing status of a handle connected to a terminal.
1523 hSetEcho :: Handle -> Bool -> IO ()
1524 hSetEcho handle on = do
1525 isT <- hIsTerminalDevice handle
1529 withHandle_ "hSetEcho" handle $ \ handle_ -> do
1530 case haType handle_ of
1531 ClosedHandle -> ioe_closedHandle
1532 _ -> setEcho (haFD handle_) on
1534 -- | Get the echoing status of a handle connected to a terminal.
1536 hGetEcho :: Handle -> IO Bool
1537 hGetEcho handle = do
1538 isT <- hIsTerminalDevice handle
1542 withHandle_ "hGetEcho" handle $ \ handle_ -> do
1543 case haType handle_ of
1544 ClosedHandle -> ioe_closedHandle
1545 _ -> getEcho (haFD handle_)
1547 -- | Is the handle connected to a terminal?
1549 hIsTerminalDevice :: Handle -> IO Bool
1550 hIsTerminalDevice handle = do
1551 withHandle_ "hIsTerminalDevice" handle $ \ handle_ -> do
1552 case haType handle_ of
1553 ClosedHandle -> ioe_closedHandle
1554 _ -> fdIsTTY (haFD handle_)
1556 -- -----------------------------------------------------------------------------
1559 -- | Select binary mode ('True') or text mode ('False') on a open handle.
1560 -- (See also 'openBinaryFile'.)
1562 hSetBinaryMode :: Handle -> Bool -> IO ()
1563 hSetBinaryMode handle bin =
1564 withAllHandles__ "hSetBinaryMode" handle $ \ handle_ ->
1565 do throwErrnoIfMinus1_ "hSetBinaryMode"
1566 (setmode (haFD handle_) bin)
1567 return handle_{haIsBin=bin}
1569 foreign import ccall unsafe "__hscore_setmode"
1570 setmode :: CInt -> Bool -> IO CInt
1572 -- -----------------------------------------------------------------------------
1573 -- Duplicating a Handle
1575 -- | Returns a duplicate of the original handle, with its own buffer.
1576 -- The two Handles will share a file pointer, however. The original
1577 -- handle's buffer is flushed, including discarding any input data,
1578 -- before the handle is duplicated.
1580 hDuplicate :: Handle -> IO Handle
1581 hDuplicate h@(FileHandle path m) = do
1582 new_h_ <- withHandle' "hDuplicate" h m (dupHandle h Nothing)
1583 newFileHandle path (handleFinalizer path) new_h_
1584 hDuplicate h@(DuplexHandle path r w) = do
1585 new_w_ <- withHandle' "hDuplicate" h w (dupHandle h Nothing)
1586 new_w <- newMVar new_w_
1587 new_r_ <- withHandle' "hDuplicate" h r (dupHandle h (Just new_w))
1588 new_r <- newMVar new_r_
1589 addMVarFinalizer new_w (handleFinalizer path new_w)
1590 return (DuplexHandle path new_r new_w)
1592 dupHandle :: Handle -> Maybe (MVar Handle__) -> Handle__
1593 -> IO (Handle__, Handle__)
1594 dupHandle h other_side h_ = do
1595 -- flush the buffer first, so we don't have to copy its contents
1597 new_fd <- case other_side of
1598 Nothing -> throwErrnoIfMinus1 "dupHandle" $ c_dup (haFD h_)
1599 Just r -> withHandle_' "dupHandle" h r (return . haFD)
1600 dupHandle_ other_side h_ new_fd
1602 dupHandleTo other_side hto_ h_ = do
1604 -- Windows' dup2 does not return the new descriptor, unlike Unix
1605 throwErrnoIfMinus1 "dupHandleTo" $
1606 c_dup2 (haFD h_) (haFD hto_)
1607 dupHandle_ other_side h_ (haFD hto_)
1609 dupHandle_ :: Maybe (MVar Handle__) -> Handle__ -> FD
1610 -> IO (Handle__, Handle__)
1611 dupHandle_ other_side h_ new_fd = do
1612 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE (initBufferState (haType h_))
1613 ioref <- newIORef buffer
1614 ioref_buffers <- newIORef BufferListNil
1616 let new_handle_ = h_{ haFD = new_fd,
1618 haBuffers = ioref_buffers,
1619 haOtherSide = other_side }
1620 return (h_, new_handle_)
1622 -- -----------------------------------------------------------------------------
1623 -- Replacing a Handle
1626 Makes the second handle a duplicate of the first handle. The second
1627 handle will be closed first, if it is not already.
1629 This can be used to retarget the standard Handles, for example:
1631 > do h <- openFile "mystdout" WriteMode
1632 > hDuplicateTo h stdout
1635 hDuplicateTo :: Handle -> Handle -> IO ()
1636 hDuplicateTo h1@(FileHandle _ m1) h2@(FileHandle _ m2) = do
1637 withHandle__' "hDuplicateTo" h2 m2 $ \h2_ -> do
1638 _ <- hClose_help h2_
1639 withHandle' "hDuplicateTo" h1 m1 (dupHandleTo Nothing h2_)
1640 hDuplicateTo h1@(DuplexHandle _ r1 w1) h2@(DuplexHandle _ r2 w2) = do
1641 withHandle__' "hDuplicateTo" h2 w2 $ \w2_ -> do
1642 _ <- hClose_help w2_
1643 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo Nothing w2_)
1644 withHandle__' "hDuplicateTo" h2 r2 $ \r2_ -> do
1645 _ <- hClose_help r2_
1646 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo (Just w1) r2_)
1648 ioException (IOError (Just h1) IllegalOperation "hDuplicateTo"
1649 "handles are incompatible" Nothing)
1651 -- ---------------------------------------------------------------------------
1654 -- | 'hShow' is in the 'IO' monad, and gives more comprehensive output
1655 -- than the (pure) instance of 'Show' for 'Handle'.
1657 hShow :: Handle -> IO String
1658 hShow h@(FileHandle path _) = showHandle' path False h
1659 hShow h@(DuplexHandle path _ _) = showHandle' path True h
1661 showHandle' filepath is_duplex h =
1662 withHandle_ "showHandle" h $ \hdl_ ->
1664 showType | is_duplex = showString "duplex (read-write)"
1665 | otherwise = shows (haType hdl_)
1669 showHdl (haType hdl_)
1670 (showString "loc=" . showString filepath . showChar ',' .
1671 showString "type=" . showType . showChar ',' .
1672 showString "binary=" . shows (haIsBin hdl_) . showChar ',' .
1673 showString "buffering=" . showBufMode (unsafePerformIO (readIORef (haBuffer hdl_))) (haBufferMode hdl_) . showString "}" )
1677 showHdl :: HandleType -> ShowS -> ShowS
1680 ClosedHandle -> shows ht . showString "}"
1683 showBufMode :: Buffer -> BufferMode -> ShowS
1684 showBufMode buf bmo =
1686 NoBuffering -> showString "none"
1687 LineBuffering -> showString "line"
1688 BlockBuffering (Just n) -> showString "block " . showParen True (shows n)
1689 BlockBuffering Nothing -> showString "block " . showParen True (shows def)
1694 -- ---------------------------------------------------------------------------
1697 #if defined(DEBUG_DUMP)
1698 puts :: String -> IO ()
1699 puts s = do write_rawBuffer 1 (unsafeCoerce# (packCString# s)) 0 (fromIntegral (length s))
1703 -- -----------------------------------------------------------------------------
1706 throwErrnoIfMinus1RetryOnBlock :: String -> IO CInt -> IO CInt -> IO CInt
1707 throwErrnoIfMinus1RetryOnBlock loc f on_block =
1710 if (res :: CInt) == -1
1714 then throwErrnoIfMinus1RetryOnBlock loc f on_block
1715 else if err == eWOULDBLOCK || err == eAGAIN
1720 -- -----------------------------------------------------------------------------
1721 -- wrappers to platform-specific constants:
1723 foreign import ccall unsafe "__hscore_supportsTextMode"
1724 tEXT_MODE_SEEK_ALLOWED :: Bool
1726 foreign import ccall unsafe "__hscore_bufsiz" dEFAULT_BUFFER_SIZE :: Int
1727 foreign import ccall unsafe "__hscore_seek_cur" sEEK_CUR :: CInt
1728 foreign import ccall unsafe "__hscore_seek_set" sEEK_SET :: CInt
1729 foreign import ccall unsafe "__hscore_seek_end" sEEK_END :: CInt