1 {-# OPTIONS_GHC -fno-implicit-prelude -#include "HsBase.h" #-}
2 {-# OPTIONS_HADDOCK hide #-}
7 -----------------------------------------------------------------------------
10 -- Copyright : (c) The University of Glasgow, 1994-2001
11 -- License : see libraries/base/LICENSE
13 -- Maintainer : libraries@haskell.org
14 -- Stability : internal
15 -- Portability : non-portable
17 -- This module defines the basic operations on I\/O \"handles\".
19 -----------------------------------------------------------------------------
23 withHandle, withHandle', withHandle_,
24 wantWritableHandle, wantReadableHandle, wantSeekableHandle,
26 newEmptyBuffer, allocateBuffer, readCharFromBuffer, writeCharIntoBuffer,
27 flushWriteBufferOnly, flushWriteBuffer, flushReadBuffer,
28 fillReadBuffer, fillReadBufferWithoutBlocking,
29 readRawBuffer, readRawBufferPtr,
30 readRawBufferNoBlock, readRawBufferPtrNoBlock,
31 writeRawBuffer, writeRawBufferPtr,
33 #ifndef mingw32_HOST_OS
37 ioe_closedHandle, ioe_EOF, ioe_notReadable, ioe_notWritable,
39 stdin, stdout, stderr,
40 IOMode(..), openFile, openBinaryFile, fdToHandle_stat, fdToHandle, fdToHandle',
41 hFileSize, hSetFileSize, hIsEOF, isEOF, hLookAhead, hSetBuffering, hSetBinaryMode,
42 hFlush, hDuplicate, hDuplicateTo,
46 HandlePosition, HandlePosn(..), hGetPosn, hSetPosn,
47 SeekMode(..), hSeek, hTell,
49 hIsOpen, hIsClosed, hIsReadable, hIsWritable, hGetBuffering, hIsSeekable,
50 hSetEcho, hGetEcho, hIsTerminalDevice,
65 import System.IO.Error
66 import System.Posix.Internals
67 import System.Posix.Types
73 import GHC.Read ( Read )
78 import GHC.Num ( Integer(..), Num(..) )
80 import GHC.Real ( toInteger )
81 #if defined(DEBUG_DUMP)
87 -- -----------------------------------------------------------------------------
90 -- hWaitForInput blocks (should use a timeout)
92 -- unbuffered hGetLine is a bit dodgy
94 -- hSetBuffering: can't change buffering on a stream,
95 -- when the read buffer is non-empty? (no way to flush the buffer)
97 -- ---------------------------------------------------------------------------
98 -- Are files opened by default in text or binary mode, if the user doesn't
101 dEFAULT_OPEN_IN_BINARY_MODE = False :: Bool
103 -- ---------------------------------------------------------------------------
104 -- Creating a new handle
106 newFileHandle :: FilePath -> (MVar Handle__ -> IO ()) -> Handle__ -> IO Handle
107 newFileHandle filepath finalizer hc = do
109 addMVarFinalizer m (finalizer m)
110 return (FileHandle filepath m)
112 -- ---------------------------------------------------------------------------
113 -- Working with Handles
116 In the concurrent world, handles are locked during use. This is done
117 by wrapping an MVar around the handle which acts as a mutex over
118 operations on the handle.
120 To avoid races, we use the following bracketing operations. The idea
121 is to obtain the lock, do some operation and replace the lock again,
122 whether the operation succeeded or failed. We also want to handle the
123 case where the thread receives an exception while processing the IO
124 operation: in these cases we also want to relinquish the lock.
126 There are three versions of @withHandle@: corresponding to the three
127 possible combinations of:
129 - the operation may side-effect the handle
130 - the operation may return a result
132 If the operation generates an error or an exception is raised, the
133 original handle is always replaced [ this is the case at the moment,
134 but we might want to revisit this in the future --SDM ].
137 {-# INLINE withHandle #-}
138 withHandle :: String -> Handle -> (Handle__ -> IO (Handle__,a)) -> IO a
139 withHandle fun h@(FileHandle _ m) act = withHandle' fun h m act
140 withHandle fun h@(DuplexHandle _ m _) act = withHandle' fun h m act
142 withHandle' :: String -> Handle -> MVar Handle__
143 -> (Handle__ -> IO (Handle__,a)) -> IO a
144 withHandle' fun h m act =
147 checkBufferInvariants h_
148 (h',v) <- catchException (act h_)
149 (\ err -> putMVar m h_ >>
151 IOException ex -> ioError (augmentIOError ex fun h)
153 checkBufferInvariants h'
157 {-# INLINE withHandle_ #-}
158 withHandle_ :: String -> Handle -> (Handle__ -> IO a) -> IO a
159 withHandle_ fun h@(FileHandle _ m) act = withHandle_' fun h m act
160 withHandle_ fun h@(DuplexHandle _ m _) act = withHandle_' fun h m act
162 withHandle_' :: String -> Handle -> MVar Handle__ -> (Handle__ -> IO a) -> IO a
163 withHandle_' fun h m act =
166 checkBufferInvariants h_
167 v <- catchException (act h_)
168 (\ err -> putMVar m h_ >>
170 IOException ex -> ioError (augmentIOError ex fun h)
172 checkBufferInvariants h_
176 withAllHandles__ :: String -> Handle -> (Handle__ -> IO Handle__) -> IO ()
177 withAllHandles__ fun h@(FileHandle _ m) act = withHandle__' fun h m act
178 withAllHandles__ fun h@(DuplexHandle _ r w) act = do
179 withHandle__' fun h r act
180 withHandle__' fun h w act
182 withHandle__' fun h m act =
185 checkBufferInvariants h_
186 h' <- catchException (act h_)
187 (\ err -> putMVar m h_ >>
189 IOException ex -> ioError (augmentIOError ex fun h)
191 checkBufferInvariants h'
195 augmentIOError (IOError _ iot _ str fp) fun h
196 = IOError (Just h) iot fun str filepath
199 | otherwise = case h of
200 FileHandle fp _ -> Just fp
201 DuplexHandle fp _ _ -> Just fp
203 -- ---------------------------------------------------------------------------
204 -- Wrapper for write operations.
206 wantWritableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
207 wantWritableHandle fun h@(FileHandle _ m) act
208 = wantWritableHandle' fun h m act
209 wantWritableHandle fun h@(DuplexHandle _ _ m) act
210 = wantWritableHandle' fun h m act
211 -- ToDo: in the Duplex case, we don't need to checkWritableHandle
214 :: String -> Handle -> MVar Handle__
215 -> (Handle__ -> IO a) -> IO a
216 wantWritableHandle' fun h m act
217 = withHandle_' fun h m (checkWritableHandle act)
219 checkWritableHandle act handle_
220 = case haType handle_ of
221 ClosedHandle -> ioe_closedHandle
222 SemiClosedHandle -> ioe_closedHandle
223 ReadHandle -> ioe_notWritable
224 ReadWriteHandle -> do
225 let ref = haBuffer handle_
228 if not (bufferIsWritable buf)
229 then do b <- flushReadBuffer (haFD handle_) buf
230 return b{ bufState=WriteBuffer }
232 writeIORef ref new_buf
234 _other -> act handle_
236 -- ---------------------------------------------------------------------------
237 -- Wrapper for read operations.
239 wantReadableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
240 wantReadableHandle fun h@(FileHandle _ m) act
241 = wantReadableHandle' fun h m act
242 wantReadableHandle fun h@(DuplexHandle _ m _) act
243 = wantReadableHandle' fun h m act
244 -- ToDo: in the Duplex case, we don't need to checkReadableHandle
247 :: String -> Handle -> MVar Handle__
248 -> (Handle__ -> IO a) -> IO a
249 wantReadableHandle' fun h m act
250 = withHandle_' fun h m (checkReadableHandle act)
252 checkReadableHandle act handle_ =
253 case haType handle_ of
254 ClosedHandle -> ioe_closedHandle
255 SemiClosedHandle -> ioe_closedHandle
256 AppendHandle -> ioe_notReadable
257 WriteHandle -> ioe_notReadable
258 ReadWriteHandle -> do
259 let ref = haBuffer handle_
261 when (bufferIsWritable buf) $ do
262 new_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
263 writeIORef ref new_buf{ bufState=ReadBuffer }
265 _other -> act handle_
267 -- ---------------------------------------------------------------------------
268 -- Wrapper for seek operations.
270 wantSeekableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
271 wantSeekableHandle fun h@(DuplexHandle _ _ _) _act =
272 ioException (IOError (Just h) IllegalOperation fun
273 "handle is not seekable" Nothing)
274 wantSeekableHandle fun h@(FileHandle _ m) act =
275 withHandle_' fun h m (checkSeekableHandle act)
277 checkSeekableHandle act handle_ =
278 case haType handle_ of
279 ClosedHandle -> ioe_closedHandle
280 SemiClosedHandle -> ioe_closedHandle
281 AppendHandle -> ioe_notSeekable
282 _ | haIsBin handle_ || tEXT_MODE_SEEK_ALLOWED -> act handle_
283 | otherwise -> ioe_notSeekable_notBin
285 -- -----------------------------------------------------------------------------
288 ioe_closedHandle, ioe_EOF,
289 ioe_notReadable, ioe_notWritable,
290 ioe_notSeekable, ioe_notSeekable_notBin :: IO a
292 ioe_closedHandle = ioException
293 (IOError Nothing IllegalOperation ""
294 "handle is closed" Nothing)
295 ioe_EOF = ioException
296 (IOError Nothing EOF "" "" Nothing)
297 ioe_notReadable = ioException
298 (IOError Nothing IllegalOperation ""
299 "handle is not open for reading" Nothing)
300 ioe_notWritable = ioException
301 (IOError Nothing IllegalOperation ""
302 "handle is not open for writing" Nothing)
303 ioe_notSeekable = ioException
304 (IOError Nothing IllegalOperation ""
305 "handle is not seekable" Nothing)
306 ioe_notSeekable_notBin = ioException
307 (IOError Nothing IllegalOperation ""
308 "seek operations on text-mode handles are not allowed on this platform"
311 ioe_finalizedHandle fp = throw (IOException
312 (IOError Nothing IllegalOperation ""
313 "handle is finalized" (Just fp)))
315 ioe_bufsiz :: Int -> IO a
316 ioe_bufsiz n = ioException
317 (IOError Nothing InvalidArgument "hSetBuffering"
318 ("illegal buffer size " ++ showsPrec 9 n []) Nothing)
319 -- 9 => should be parens'ified.
321 -- -----------------------------------------------------------------------------
324 -- For a duplex handle, we arrange that the read side points to the write side
325 -- (and hence keeps it alive if the read side is alive). This is done by
326 -- having the haOtherSide field of the read side point to the read side.
327 -- The finalizer is then placed on the write side, and the handle only gets
328 -- finalized once, when both sides are no longer required.
330 -- NOTE about finalized handles: It's possible that a handle can be
331 -- finalized and then we try to use it later, for example if the
332 -- handle is referenced from another finalizer, or from a thread that
333 -- has become unreferenced and then resurrected (arguably in the
334 -- latter case we shouldn't finalize the Handle...). Anyway,
335 -- we try to emit a helpful message which is better than nothing.
337 stdHandleFinalizer :: FilePath -> MVar Handle__ -> IO ()
338 stdHandleFinalizer fp m = do
340 flushWriteBufferOnly h_
341 putMVar m (ioe_finalizedHandle fp)
343 handleFinalizer :: FilePath -> MVar Handle__ -> IO ()
344 handleFinalizer fp m = do
345 handle_ <- takeMVar m
346 case haType handle_ of
347 ClosedHandle -> return ()
348 _ -> do flushWriteBufferOnly handle_ `catchException` \_ -> return ()
349 -- ignore errors and async exceptions, and close the
350 -- descriptor anyway...
351 hClose_handle_ handle_
353 putMVar m (ioe_finalizedHandle fp)
355 -- ---------------------------------------------------------------------------
356 -- Grimy buffer operations
359 checkBufferInvariants h_ = do
360 let ref = haBuffer h_
361 Buffer{ bufWPtr=w, bufRPtr=r, bufSize=size, bufState=state } <- readIORef ref
366 && ( r /= w || (r == 0 && w == 0) )
367 && ( state /= WriteBuffer || r == 0 )
368 && ( state /= WriteBuffer || w < size ) -- write buffer is never full
370 then error "buffer invariant violation"
373 checkBufferInvariants h_ = return ()
376 newEmptyBuffer :: RawBuffer -> BufferState -> Int -> Buffer
377 newEmptyBuffer b state size
378 = Buffer{ bufBuf=b, bufRPtr=0, bufWPtr=0, bufSize=size, bufState=state }
380 allocateBuffer :: Int -> BufferState -> IO Buffer
381 allocateBuffer sz@(I# size) state = IO $ \s ->
382 -- We sometimes need to pass the address of this buffer to
383 -- a "safe" foreign call, hence it must be immovable.
384 case newPinnedByteArray# size s of { (# s, b #) ->
385 (# s, newEmptyBuffer b state sz #) }
387 writeCharIntoBuffer :: RawBuffer -> Int -> Char -> IO Int
388 writeCharIntoBuffer slab (I# off) (C# c)
389 = IO $ \s -> case writeCharArray# slab off c s of
390 s -> (# s, I# (off +# 1#) #)
392 readCharFromBuffer :: RawBuffer -> Int -> IO (Char, Int)
393 readCharFromBuffer slab (I# off)
394 = IO $ \s -> case readCharArray# slab off s of
395 (# s, c #) -> (# s, (C# c, I# (off +# 1#)) #)
397 getBuffer :: FD -> BufferState -> IO (IORef Buffer, BufferMode)
398 getBuffer fd state = do
399 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE state
400 ioref <- newIORef buffer
404 | is_tty = LineBuffering
405 | otherwise = BlockBuffering Nothing
407 return (ioref, buffer_mode)
409 mkUnBuffer :: IO (IORef Buffer)
411 buffer <- allocateBuffer 1 ReadBuffer
414 -- flushWriteBufferOnly flushes the buffer iff it contains pending write data.
415 flushWriteBufferOnly :: Handle__ -> IO ()
416 flushWriteBufferOnly h_ = do
420 new_buf <- if bufferIsWritable buf
421 then flushWriteBuffer fd (haIsStream h_) buf
423 writeIORef ref new_buf
425 -- flushBuffer syncs the file with the buffer, including moving the
426 -- file pointer backwards in the case of a read buffer.
427 flushBuffer :: Handle__ -> IO ()
429 let ref = haBuffer h_
434 ReadBuffer -> flushReadBuffer (haFD h_) buf
435 WriteBuffer -> flushWriteBuffer (haFD h_) (haIsStream h_) buf
437 writeIORef ref flushed_buf
439 -- When flushing a read buffer, we seek backwards by the number of
440 -- characters in the buffer. The file descriptor must therefore be
441 -- seekable: attempting to flush the read buffer on an unseekable
442 -- handle is not allowed.
444 flushReadBuffer :: FD -> Buffer -> IO Buffer
445 flushReadBuffer fd buf
446 | bufferEmpty buf = return buf
448 let off = negate (bufWPtr buf - bufRPtr buf)
450 puts ("flushReadBuffer: new file offset = " ++ show off ++ "\n")
452 throwErrnoIfMinus1Retry "flushReadBuffer"
453 (c_lseek fd (fromIntegral off) sEEK_CUR)
454 return buf{ bufWPtr=0, bufRPtr=0 }
456 flushWriteBuffer :: FD -> Bool -> Buffer -> IO Buffer
457 flushWriteBuffer fd is_stream buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w } =
458 seq fd $ do -- strictness hack
461 puts ("flushWriteBuffer, fd=" ++ show fd ++ ", bytes=" ++ show bytes ++ "\n")
464 then return (buf{ bufRPtr=0, bufWPtr=0 })
466 res <- writeRawBuffer "flushWriteBuffer" fd is_stream b
467 (fromIntegral r) (fromIntegral bytes)
468 let res' = fromIntegral res
470 then flushWriteBuffer fd is_stream (buf{ bufRPtr = r + res' })
471 else return buf{ bufRPtr=0, bufWPtr=0 }
473 fillReadBuffer :: FD -> Bool -> Bool -> Buffer -> IO Buffer
474 fillReadBuffer fd is_line is_stream
475 buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w, bufSize=size } =
476 -- buffer better be empty:
477 assert (r == 0 && w == 0) $ do
478 fillReadBufferLoop fd is_line is_stream buf b w size
480 -- For a line buffer, we just get the first chunk of data to arrive,
481 -- and don't wait for the whole buffer to be full (but we *do* wait
482 -- until some data arrives). This isn't really line buffering, but it
483 -- appears to be what GHC has done for a long time, and I suspect it
484 -- is more useful than line buffering in most cases.
486 fillReadBufferLoop fd is_line is_stream buf b w size = do
488 if bytes == 0 -- buffer full?
489 then return buf{ bufRPtr=0, bufWPtr=w }
492 puts ("fillReadBufferLoop: bytes = " ++ show bytes ++ "\n")
494 res <- readRawBuffer "fillReadBuffer" fd is_stream b
495 (fromIntegral w) (fromIntegral bytes)
496 let res' = fromIntegral res
498 puts ("fillReadBufferLoop: res' = " ++ show res' ++ "\n")
503 else return buf{ bufRPtr=0, bufWPtr=w }
504 else if res' < bytes && not is_line
505 then fillReadBufferLoop fd is_line is_stream buf b (w+res') size
506 else return buf{ bufRPtr=0, bufWPtr=w+res' }
509 fillReadBufferWithoutBlocking :: FD -> Bool -> Buffer -> IO Buffer
510 fillReadBufferWithoutBlocking fd is_stream
511 buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w, bufSize=size } =
512 -- buffer better be empty:
513 assert (r == 0 && w == 0) $ do
515 puts ("fillReadBufferLoopNoBlock: bytes = " ++ show size ++ "\n")
517 res <- readRawBufferNoBlock "fillReadBuffer" fd is_stream b
518 0 (fromIntegral size)
519 let res' = fromIntegral res
521 puts ("fillReadBufferLoopNoBlock: res' = " ++ show res' ++ "\n")
523 return buf{ bufRPtr=0, bufWPtr=res' }
525 -- Low level routines for reading/writing to (raw)buffers:
527 #ifndef mingw32_HOST_OS
532 Unix has broken semantics when it comes to non-blocking I/O: you can
533 set the O_NONBLOCK flag on an FD, but it applies to the all other FDs
534 attached to the same underlying file, pipe or TTY; there's no way to
535 have private non-blocking behaviour for an FD. See bug #724.
537 We fix this by only setting O_NONBLOCK on FDs that we create; FDs that
538 come from external sources or are exposed externally are left in
539 blocking mode. This solution has some problems though. We can't
540 completely simulate a non-blocking read without O_NONBLOCK: several
541 cases are wrong here. The cases that are wrong:
543 * reading/writing to a blocking FD in non-threaded mode.
544 In threaded mode, we just make a safe call to read().
545 In non-threaded mode we call select() before attempting to read,
546 but that leaves a small race window where the data can be read
547 from the file descriptor before we issue our blocking read().
548 * readRawBufferNoBlock for a blocking FD
551 readRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
552 readRawBuffer loc fd is_nonblock buf off len
553 | is_nonblock = unsafe_read
554 | threaded = safe_read
555 | otherwise = do r <- throwErrnoIfMinus1 loc
556 (fdReady (fromIntegral fd) 0 0 False)
559 else do threadWaitRead (fromIntegral fd); unsafe_read
561 do_read call = throwErrnoIfMinus1RetryMayBlock loc call
562 (threadWaitRead (fromIntegral fd))
563 unsafe_read = do_read (read_rawBuffer fd buf off len)
564 safe_read = do_read (safe_read_rawBuffer fd buf off len)
566 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
567 readRawBufferPtr loc fd is_nonblock buf off len
568 | is_nonblock = unsafe_read
569 | threaded = safe_read
570 | otherwise = do r <- throwErrnoIfMinus1 loc
571 (fdReady (fromIntegral fd) 0 0 False)
574 else do threadWaitRead (fromIntegral fd); unsafe_read
576 do_read call = throwErrnoIfMinus1RetryMayBlock loc call
577 (threadWaitRead (fromIntegral fd))
578 unsafe_read = do_read (read_off fd buf off len)
579 safe_read = do_read (safe_read_off fd buf off len)
581 readRawBufferNoBlock :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
582 readRawBufferNoBlock loc fd is_nonblock buf off len
583 | is_nonblock = unsafe_read
584 | otherwise = do r <- fdReady (fromIntegral fd) 0 0 False
585 if r /= 0 then safe_read
587 -- XXX see note [nonblock]
589 do_read call = throwErrnoIfMinus1RetryOnBlock loc call (return 0)
590 unsafe_read = do_read (read_rawBuffer fd buf off len)
591 safe_read = do_read (safe_read_rawBuffer fd buf off len)
593 readRawBufferPtrNoBlock :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
594 readRawBufferPtrNoBlock loc fd is_nonblock buf off len
595 | is_nonblock = unsafe_read
596 | otherwise = do r <- fdReady (fromIntegral fd) 0 0 False
597 if r /= 0 then safe_read
599 -- XXX see note [nonblock]
601 do_read call = throwErrnoIfMinus1RetryOnBlock loc call (return 0)
602 unsafe_read = do_read (read_off fd buf off len)
603 safe_read = do_read (safe_read_off fd buf off len)
605 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
606 writeRawBuffer loc fd is_nonblock buf off len
607 | is_nonblock = unsafe_write
608 | threaded = safe_write
609 | otherwise = do r <- fdReady (fromIntegral fd) 1 0 False
612 else do threadWaitWrite (fromIntegral fd); unsafe_write
614 do_write call = throwErrnoIfMinus1RetryMayBlock loc call
615 (threadWaitWrite (fromIntegral fd))
616 unsafe_write = do_write (write_rawBuffer fd buf off len)
617 safe_write = do_write (safe_write_rawBuffer (fromIntegral fd) buf off len)
619 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
620 writeRawBufferPtr loc fd is_nonblock buf off len
621 | is_nonblock = unsafe_write
622 | threaded = safe_write
623 | otherwise = do r <- fdReady (fromIntegral fd) 1 0 False
626 else do threadWaitWrite (fromIntegral fd); unsafe_write
628 do_write call = throwErrnoIfMinus1RetryMayBlock loc call
629 (threadWaitWrite (fromIntegral fd))
630 unsafe_write = do_write (write_off fd buf off len)
631 safe_write = do_write (safe_write_off (fromIntegral fd) buf off len)
633 foreign import ccall unsafe "__hscore_PrelHandle_read"
634 read_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
636 foreign import ccall unsafe "__hscore_PrelHandle_read"
637 read_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
639 foreign import ccall unsafe "__hscore_PrelHandle_write"
640 write_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
642 foreign import ccall unsafe "__hscore_PrelHandle_write"
643 write_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
645 foreign import ccall safe "fdReady"
646 fdReady :: CInt -> CInt -> CInt -> Bool -> IO CInt
648 #else /* mingw32_HOST_OS.... */
650 readRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
651 readRawBuffer loc fd is_stream buf off len
652 | threaded = blockingReadRawBuffer loc fd is_stream buf off len
653 | otherwise = asyncReadRawBuffer loc fd is_stream buf off len
655 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
656 readRawBufferPtr loc fd is_stream buf off len
657 | threaded = blockingReadRawBufferPtr loc fd is_stream buf off len
658 | otherwise = asyncReadRawBufferPtr loc fd is_stream buf off len
660 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
661 writeRawBuffer loc fd is_stream buf off len
662 | threaded = blockingWriteRawBuffer loc fd is_stream buf off len
663 | otherwise = asyncWriteRawBuffer loc fd is_stream buf off len
665 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
666 writeRawBufferPtr loc fd is_stream buf off len
667 | threaded = blockingWriteRawBufferPtr loc fd is_stream buf off len
668 | otherwise = asyncWriteRawBufferPtr loc fd is_stream buf off len
670 -- ToDo: we don't have a non-blocking primitve read on Win32
671 readRawBufferNoBlock :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
672 readRawBufferNoBlock = readRawBuffer
674 readRawBufferPtrNoBlock :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
675 readRawBufferPtrNoBlock = readRawBufferPtr
676 -- Async versions of the read/write primitives, for the non-threaded RTS
678 asyncReadRawBuffer loc fd is_stream buf off len = do
679 (l, rc) <- asyncReadBA (fromIntegral fd) (if is_stream then 1 else 0)
680 (fromIntegral len) off buf
683 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
684 else return (fromIntegral l)
686 asyncReadRawBufferPtr loc fd is_stream buf off len = do
687 (l, rc) <- asyncRead (fromIntegral fd) (if is_stream then 1 else 0)
688 (fromIntegral len) (buf `plusPtr` off)
691 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
692 else return (fromIntegral l)
694 asyncWriteRawBuffer loc fd is_stream buf off len = do
695 (l, rc) <- asyncWriteBA (fromIntegral fd) (if is_stream then 1 else 0)
696 (fromIntegral len) off buf
699 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
700 else return (fromIntegral l)
702 asyncWriteRawBufferPtr loc fd is_stream buf off len = do
703 (l, rc) <- asyncWrite (fromIntegral fd) (if is_stream then 1 else 0)
704 (fromIntegral len) (buf `plusPtr` off)
707 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
708 else return (fromIntegral l)
710 -- Blocking versions of the read/write primitives, for the threaded RTS
712 blockingReadRawBuffer loc fd True buf off len =
713 throwErrnoIfMinus1Retry loc $
714 safe_recv_rawBuffer fd buf off len
715 blockingReadRawBuffer loc fd False buf off len =
716 throwErrnoIfMinus1Retry loc $
717 safe_read_rawBuffer fd buf off len
719 blockingReadRawBufferPtr loc fd True buf off len =
720 throwErrnoIfMinus1Retry loc $
721 safe_recv_off fd buf off len
722 blockingReadRawBufferPtr loc fd False buf off len =
723 throwErrnoIfMinus1Retry loc $
724 safe_read_off fd buf off len
726 blockingWriteRawBuffer loc fd True buf off len =
727 throwErrnoIfMinus1Retry loc $
728 safe_send_rawBuffer fd buf off len
729 blockingWriteRawBuffer loc fd False buf off len =
730 throwErrnoIfMinus1Retry loc $
731 safe_write_rawBuffer fd buf off len
733 blockingWriteRawBufferPtr loc fd True buf off len =
734 throwErrnoIfMinus1Retry loc $
735 safe_send_off fd buf off len
736 blockingWriteRawBufferPtr loc fd False buf off len =
737 throwErrnoIfMinus1Retry loc $
738 safe_write_off fd buf off len
740 -- NOTE: "safe" versions of the read/write calls for use by the threaded RTS.
741 -- These calls may block, but that's ok.
743 foreign import ccall safe "__hscore_PrelHandle_recv"
744 safe_recv_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
746 foreign import ccall safe "__hscore_PrelHandle_recv"
747 safe_recv_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
749 foreign import ccall safe "__hscore_PrelHandle_send"
750 safe_send_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
752 foreign import ccall safe "__hscore_PrelHandle_send"
753 safe_send_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
757 foreign import ccall "rtsSupportsBoundThreads" threaded :: Bool
759 foreign import ccall safe "__hscore_PrelHandle_read"
760 safe_read_rawBuffer :: FD -> RawBuffer -> Int -> CInt -> IO CInt
762 foreign import ccall safe "__hscore_PrelHandle_read"
763 safe_read_off :: FD -> Ptr CChar -> Int -> CInt -> IO CInt
765 foreign import ccall safe "__hscore_PrelHandle_write"
766 safe_write_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
768 foreign import ccall safe "__hscore_PrelHandle_write"
769 safe_write_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
771 -- ---------------------------------------------------------------------------
774 -- Three handles are allocated during program initialisation. The first
775 -- two manage input or output from the Haskell program's standard input
776 -- or output channel respectively. The third manages output to the
777 -- standard error channel. These handles are initially open.
783 -- | A handle managing input from the Haskell program's standard input channel.
785 stdin = unsafePerformIO $ do
786 -- ToDo: acquire lock
787 -- We don't set non-blocking mode on standard handles, because it may
788 -- confuse other applications attached to the same TTY/pipe
789 -- see Note [nonblock]
790 (buf, bmode) <- getBuffer fd_stdin ReadBuffer
791 mkStdHandle fd_stdin "<stdin>" ReadHandle buf bmode
793 -- | A handle managing output to the Haskell program's standard output channel.
795 stdout = unsafePerformIO $ do
796 -- ToDo: acquire lock
797 -- We don't set non-blocking mode on standard handles, because it may
798 -- confuse other applications attached to the same TTY/pipe
799 -- see Note [nonblock]
800 (buf, bmode) <- getBuffer fd_stdout WriteBuffer
801 mkStdHandle fd_stdout "<stdout>" WriteHandle buf bmode
803 -- | A handle managing output to the Haskell program's standard error channel.
805 stderr = unsafePerformIO $ do
806 -- ToDo: acquire lock
807 -- We don't set non-blocking mode on standard handles, because it may
808 -- confuse other applications attached to the same TTY/pipe
809 -- see Note [nonblock]
811 mkStdHandle fd_stderr "<stderr>" WriteHandle buf NoBuffering
813 -- ---------------------------------------------------------------------------
814 -- Opening and Closing Files
816 addFilePathToIOError fun fp (IOError h iot _ str _)
817 = IOError h iot fun str (Just fp)
819 -- | Computation 'openFile' @file mode@ allocates and returns a new, open
820 -- handle to manage the file @file@. It manages input if @mode@
821 -- is 'ReadMode', output if @mode@ is 'WriteMode' or 'AppendMode',
822 -- and both input and output if mode is 'ReadWriteMode'.
824 -- If the file does not exist and it is opened for output, it should be
825 -- created as a new file. If @mode@ is 'WriteMode' and the file
826 -- already exists, then it should be truncated to zero length.
827 -- Some operating systems delete empty files, so there is no guarantee
828 -- that the file will exist following an 'openFile' with @mode@
829 -- 'WriteMode' unless it is subsequently written to successfully.
830 -- The handle is positioned at the end of the file if @mode@ is
831 -- 'AppendMode', and otherwise at the beginning (in which case its
832 -- internal position is 0).
833 -- The initial buffer mode is implementation-dependent.
835 -- This operation may fail with:
837 -- * 'isAlreadyInUseError' if the file is already open and cannot be reopened;
839 -- * 'isDoesNotExistError' if the file does not exist; or
841 -- * 'isPermissionError' if the user does not have permission to open the file.
843 -- Note: if you will be working with files containing binary data, you'll want to
844 -- be using 'openBinaryFile'.
845 openFile :: FilePath -> IOMode -> IO Handle
848 (openFile' fp im dEFAULT_OPEN_IN_BINARY_MODE)
849 (\e -> ioError (addFilePathToIOError "openFile" fp e))
851 -- | Like 'openFile', but open the file in binary mode.
852 -- On Windows, reading a file in text mode (which is the default)
853 -- will translate CRLF to LF, and writing will translate LF to CRLF.
854 -- This is usually what you want with text files. With binary files
855 -- this is undesirable; also, as usual under Microsoft operating systems,
856 -- text mode treats control-Z as EOF. Binary mode turns off all special
857 -- treatment of end-of-line and end-of-file characters.
858 -- (See also 'hSetBinaryMode'.)
860 openBinaryFile :: FilePath -> IOMode -> IO Handle
861 openBinaryFile fp m =
863 (openFile' fp m True)
864 (\e -> ioError (addFilePathToIOError "openBinaryFile" fp e))
866 openFile' filepath mode binary =
867 withCString filepath $ \ f ->
870 oflags1 = case mode of
871 ReadMode -> read_flags
872 #ifdef mingw32_HOST_OS
873 WriteMode -> write_flags .|. o_TRUNC
875 WriteMode -> write_flags
877 ReadWriteMode -> rw_flags
878 AppendMode -> append_flags
884 oflags = oflags1 .|. binary_flags
887 -- the old implementation had a complicated series of three opens,
888 -- which is perhaps because we have to be careful not to open
889 -- directories. However, the man pages I've read say that open()
890 -- always returns EISDIR if the file is a directory and was opened
891 -- for writing, so I think we're ok with a single open() here...
892 fd <- throwErrnoIfMinus1Retry "openFile"
893 (c_open f (fromIntegral oflags) 0o666)
895 stat@(fd_type,_,_) <- fdStat fd
897 h <- fdToHandle_stat fd (Just stat) False filepath mode binary
898 `catchException` \e -> do c_close fd; throw e
899 -- NB. don't forget to close the FD if fdToHandle' fails, otherwise
901 -- ASSERT: if we just created the file, then fdToHandle' won't fail
902 -- (so we don't need to worry about removing the newly created file
903 -- in the event of an error).
905 #ifndef mingw32_HOST_OS
906 -- we want to truncate() if this is an open in WriteMode, but only
907 -- if the target is a RegularFile. ftruncate() fails on special files
909 if mode == WriteMode && fd_type == RegularFile
910 then throwErrnoIf (/=0) "openFile"
917 std_flags = o_NONBLOCK .|. o_NOCTTY
918 output_flags = std_flags .|. o_CREAT
919 read_flags = std_flags .|. o_RDONLY
920 write_flags = output_flags .|. o_WRONLY
921 rw_flags = output_flags .|. o_RDWR
922 append_flags = write_flags .|. o_APPEND
924 -- ---------------------------------------------------------------------------
927 fdToHandle_stat :: FD
928 -> Maybe (FDType, CDev, CIno)
935 fdToHandle_stat fd mb_stat is_socket filepath mode binary = do
936 -- turn on non-blocking mode
939 #ifdef mingw32_HOST_OS
940 -- On Windows, the is_stream flag indicates that the Handle is a socket
941 let is_stream = is_socket
943 -- On Unix, the is_stream flag indicates that the FD is non-blocking
947 let (ha_type, write) =
949 ReadMode -> ( ReadHandle, False )
950 WriteMode -> ( WriteHandle, True )
951 ReadWriteMode -> ( ReadWriteHandle, True )
952 AppendMode -> ( AppendHandle, True )
954 -- open() won't tell us if it was a directory if we only opened for
955 -- reading, so check again.
963 ioException (IOError Nothing InappropriateType "openFile"
964 "is a directory" Nothing)
966 -- regular files need to be locked
968 #ifndef mingw32_HOST_OS
969 r <- lockFile fd dev ino (fromBool write)
971 ioException (IOError Nothing ResourceBusy "openFile"
972 "file is locked" Nothing)
974 mkFileHandle fd is_stream filepath ha_type binary
977 -- only *Streams* can be DuplexHandles. Other read/write
978 -- Handles must share a buffer.
979 | ReadWriteHandle <- ha_type ->
980 mkDuplexHandle fd is_stream filepath binary
982 mkFileHandle fd is_stream filepath ha_type binary
985 mkFileHandle fd is_stream filepath ha_type binary
987 -- | Old API kept to avoid breaking clients
988 fdToHandle' :: FD -> Maybe FDType -> Bool -> FilePath -> IOMode -> Bool
990 fdToHandle' fd mb_type is_socket filepath mode binary
992 let mb_stat = case mb_type of
994 -- fdToHandle_stat will do the stat:
995 Just RegularFile -> Nothing
996 -- no stat required for streams etc.:
997 Just other -> Just (other,0,0)
998 fdToHandle_stat fd mb_stat is_socket filepath mode binary
1000 fdToHandle :: FD -> IO Handle
1002 mode <- fdGetMode fd
1003 let fd_str = "<file descriptor: " ++ show fd ++ ">"
1004 fdToHandle_stat fd Nothing False{-XXX!-} fd_str mode True{-bin mode-}
1007 #ifndef mingw32_HOST_OS
1008 foreign import ccall unsafe "lockFile"
1009 lockFile :: CInt -> CDev -> CIno -> CInt -> IO CInt
1011 foreign import ccall unsafe "unlockFile"
1012 unlockFile :: CInt -> IO CInt
1015 mkStdHandle :: FD -> FilePath -> HandleType -> IORef Buffer -> BufferMode
1017 mkStdHandle fd filepath ha_type buf bmode = do
1018 spares <- newIORef BufferListNil
1019 newFileHandle filepath (stdHandleFinalizer filepath)
1020 (Handle__ { haFD = fd,
1022 haIsBin = dEFAULT_OPEN_IN_BINARY_MODE,
1023 haIsStream = False, -- means FD is blocking on Unix
1024 haBufferMode = bmode,
1027 haOtherSide = Nothing
1030 mkFileHandle :: FD -> Bool -> FilePath -> HandleType -> Bool -> IO Handle
1031 mkFileHandle fd is_stream filepath ha_type binary = do
1032 (buf, bmode) <- getBuffer fd (initBufferState ha_type)
1034 #ifdef mingw32_HOST_OS
1035 -- On Windows, if this is a read/write handle and we are in text mode,
1036 -- turn off buffering. We don't correctly handle the case of switching
1037 -- from read mode to write mode on a buffered text-mode handle, see bug
1039 bmode <- case ha_type of
1040 ReadWriteHandle | not binary -> return NoBuffering
1041 _other -> return bmode
1044 spares <- newIORef BufferListNil
1045 newFileHandle filepath (handleFinalizer filepath)
1046 (Handle__ { haFD = fd,
1049 haIsStream = is_stream,
1050 haBufferMode = bmode,
1053 haOtherSide = Nothing
1056 mkDuplexHandle :: FD -> Bool -> FilePath -> Bool -> IO Handle
1057 mkDuplexHandle fd is_stream filepath binary = do
1058 (w_buf, w_bmode) <- getBuffer fd WriteBuffer
1059 w_spares <- newIORef BufferListNil
1061 Handle__ { haFD = fd,
1062 haType = WriteHandle,
1064 haIsStream = is_stream,
1065 haBufferMode = w_bmode,
1067 haBuffers = w_spares,
1068 haOtherSide = Nothing
1070 write_side <- newMVar w_handle_
1072 (r_buf, r_bmode) <- getBuffer fd ReadBuffer
1073 r_spares <- newIORef BufferListNil
1075 Handle__ { haFD = fd,
1076 haType = ReadHandle,
1078 haIsStream = is_stream,
1079 haBufferMode = r_bmode,
1081 haBuffers = r_spares,
1082 haOtherSide = Just write_side
1084 read_side <- newMVar r_handle_
1086 addMVarFinalizer write_side (handleFinalizer filepath write_side)
1087 return (DuplexHandle filepath read_side write_side)
1090 initBufferState ReadHandle = ReadBuffer
1091 initBufferState _ = WriteBuffer
1093 -- ---------------------------------------------------------------------------
1096 -- | Computation 'hClose' @hdl@ makes handle @hdl@ closed. Before the
1097 -- computation finishes, if @hdl@ is writable its buffer is flushed as
1099 -- Performing 'hClose' on a handle that has already been closed has no effect;
1100 -- doing so is not an error. All other operations on a closed handle will fail.
1101 -- If 'hClose' fails for any reason, any further operations (apart from
1102 -- 'hClose') on the handle will still fail as if @hdl@ had been successfully
1105 hClose :: Handle -> IO ()
1106 hClose h@(FileHandle _ m) = do
1107 mb_exc <- hClose' h m
1109 Nothing -> return ()
1111 hClose h@(DuplexHandle _ r w) = do
1112 mb_exc1 <- hClose' h w
1113 mb_exc2 <- hClose' h r
1114 case (do mb_exc1; mb_exc2) of
1115 Nothing -> return ()
1118 hClose' h m = withHandle' "hClose" h m $ hClose_help
1120 -- hClose_help is also called by lazyRead (in PrelIO) when EOF is read
1121 -- or an IO error occurs on a lazy stream. The semi-closed Handle is
1122 -- then closed immediately. We have to be careful with DuplexHandles
1123 -- though: we have to leave the closing to the finalizer in that case,
1124 -- because the write side may still be in use.
1125 hClose_help :: Handle__ -> IO (Handle__, Maybe Exception)
1126 hClose_help handle_ =
1127 case haType handle_ of
1128 ClosedHandle -> return (handle_,Nothing)
1129 _ -> do flushWriteBufferOnly handle_ -- interruptible
1130 hClose_handle_ handle_
1132 hClose_handle_ handle_ = do
1133 let fd = haFD handle_
1135 -- close the file descriptor, but not when this is the read
1136 -- side of a duplex handle.
1137 -- If an exception is raised by the close(), we want to continue
1138 -- to close the handle and release the lock if it has one, then
1139 -- we return the exception to the caller of hClose_help which can
1140 -- raise it if necessary.
1142 case haOtherSide handle_ of
1144 throwErrnoIfMinus1Retry_ "hClose"
1145 #ifdef mingw32_HOST_OS
1146 (closeFd (haIsStream handle_) fd)
1152 `catchException` \e -> return (Just e)
1154 Just _ -> return Nothing
1156 -- free the spare buffers
1157 writeIORef (haBuffers handle_) BufferListNil
1158 writeIORef (haBuffer handle_) noBuffer
1160 #ifndef mingw32_HOST_OS
1165 -- we must set the fd to -1, because the finalizer is going
1166 -- to run eventually and try to close/unlock it.
1167 return (handle_{ haFD = -1,
1168 haType = ClosedHandle
1172 {-# NOINLINE noBuffer #-}
1173 noBuffer = unsafePerformIO $ allocateBuffer 1 ReadBuffer
1175 -----------------------------------------------------------------------------
1176 -- Detecting and changing the size of a file
1178 -- | For a handle @hdl@ which attached to a physical file,
1179 -- 'hFileSize' @hdl@ returns the size of that file in 8-bit bytes.
1181 hFileSize :: Handle -> IO Integer
1183 withHandle_ "hFileSize" handle $ \ handle_ -> do
1184 case haType handle_ of
1185 ClosedHandle -> ioe_closedHandle
1186 SemiClosedHandle -> ioe_closedHandle
1187 _ -> do flushWriteBufferOnly handle_
1188 r <- fdFileSize (haFD handle_)
1191 else ioException (IOError Nothing InappropriateType "hFileSize"
1192 "not a regular file" Nothing)
1195 -- | 'hSetFileSize' @hdl@ @size@ truncates the physical file with handle @hdl@ to @size@ bytes.
1197 hSetFileSize :: Handle -> Integer -> IO ()
1198 hSetFileSize handle size =
1199 withHandle_ "hSetFileSize" handle $ \ handle_ -> do
1200 case haType handle_ of
1201 ClosedHandle -> ioe_closedHandle
1202 SemiClosedHandle -> ioe_closedHandle
1203 _ -> do flushWriteBufferOnly handle_
1204 throwErrnoIf (/=0) "hSetFileSize"
1205 (c_ftruncate (haFD handle_) (fromIntegral size))
1208 -- ---------------------------------------------------------------------------
1209 -- Detecting the End of Input
1211 -- | For a readable handle @hdl@, 'hIsEOF' @hdl@ returns
1212 -- 'True' if no further input can be taken from @hdl@ or for a
1213 -- physical file, if the current I\/O position is equal to the length of
1214 -- the file. Otherwise, it returns 'False'.
1216 -- NOTE: 'hIsEOF' may block, because it is the same as calling
1217 -- 'hLookAhead' and checking for an EOF exception.
1219 hIsEOF :: Handle -> IO Bool
1222 (do hLookAhead handle; return False)
1223 (\e -> if isEOFError e then return True else ioError e)
1225 -- | The computation 'isEOF' is identical to 'hIsEOF',
1226 -- except that it works only on 'stdin'.
1229 isEOF = hIsEOF stdin
1231 -- ---------------------------------------------------------------------------
1234 -- | Computation 'hLookAhead' returns the next character from the handle
1235 -- without removing it from the input buffer, blocking until a character
1238 -- This operation may fail with:
1240 -- * 'isEOFError' if the end of file has been reached.
1242 hLookAhead :: Handle -> IO Char
1243 hLookAhead handle = do
1244 wantReadableHandle "hLookAhead" handle $ \handle_ -> do
1245 let ref = haBuffer handle_
1247 is_line = haBufferMode handle_ == LineBuffering
1248 buf <- readIORef ref
1250 -- fill up the read buffer if necessary
1251 new_buf <- if bufferEmpty buf
1252 then fillReadBuffer fd True (haIsStream handle_) buf
1255 writeIORef ref new_buf
1257 (c,_) <- readCharFromBuffer (bufBuf buf) (bufRPtr buf)
1260 -- ---------------------------------------------------------------------------
1261 -- Buffering Operations
1263 -- Three kinds of buffering are supported: line-buffering,
1264 -- block-buffering or no-buffering. See GHC.IOBase for definition and
1265 -- further explanation of what the type represent.
1267 -- | Computation 'hSetBuffering' @hdl mode@ sets the mode of buffering for
1268 -- handle @hdl@ on subsequent reads and writes.
1270 -- If the buffer mode is changed from 'BlockBuffering' or
1271 -- 'LineBuffering' to 'NoBuffering', then
1273 -- * if @hdl@ is writable, the buffer is flushed as for 'hFlush';
1275 -- * if @hdl@ is not writable, the contents of the buffer is discarded.
1277 -- This operation may fail with:
1279 -- * 'isPermissionError' if the handle has already been used for reading
1280 -- or writing and the implementation does not allow the buffering mode
1283 hSetBuffering :: Handle -> BufferMode -> IO ()
1284 hSetBuffering handle mode =
1285 withAllHandles__ "hSetBuffering" handle $ \ handle_ -> do
1286 case haType handle_ of
1287 ClosedHandle -> ioe_closedHandle
1290 - we flush the old buffer regardless of whether
1291 the new buffer could fit the contents of the old buffer
1293 - allow a handle's buffering to change even if IO has
1294 occurred (ANSI C spec. does not allow this, nor did
1295 the previous implementation of IO.hSetBuffering).
1296 - a non-standard extension is to allow the buffering
1297 of semi-closed handles to change [sof 6/98]
1301 let state = initBufferState (haType handle_)
1304 -- we always have a 1-character read buffer for
1305 -- unbuffered handles: it's needed to
1306 -- support hLookAhead.
1307 NoBuffering -> allocateBuffer 1 ReadBuffer
1308 LineBuffering -> allocateBuffer dEFAULT_BUFFER_SIZE state
1309 BlockBuffering Nothing -> allocateBuffer dEFAULT_BUFFER_SIZE state
1310 BlockBuffering (Just n) | n <= 0 -> ioe_bufsiz n
1311 | otherwise -> allocateBuffer n state
1312 writeIORef (haBuffer handle_) new_buf
1314 -- for input terminals we need to put the terminal into
1315 -- cooked or raw mode depending on the type of buffering.
1316 is_tty <- fdIsTTY (haFD handle_)
1317 when (is_tty && isReadableHandleType (haType handle_)) $
1319 #ifndef mingw32_HOST_OS
1320 -- 'raw' mode under win32 is a bit too specialised (and troublesome
1321 -- for most common uses), so simply disable its use here.
1322 NoBuffering -> setCooked (haFD handle_) False
1324 NoBuffering -> return ()
1326 _ -> setCooked (haFD handle_) True
1328 -- throw away spare buffers, they might be the wrong size
1329 writeIORef (haBuffers handle_) BufferListNil
1331 return (handle_{ haBufferMode = mode })
1333 -- -----------------------------------------------------------------------------
1336 -- | The action 'hFlush' @hdl@ causes any items buffered for output
1337 -- in handle @hdl@ to be sent immediately to the operating system.
1339 -- This operation may fail with:
1341 -- * 'isFullError' if the device is full;
1343 -- * 'isPermissionError' if a system resource limit would be exceeded.
1344 -- It is unspecified whether the characters in the buffer are discarded
1345 -- or retained under these circumstances.
1347 hFlush :: Handle -> IO ()
1349 wantWritableHandle "hFlush" handle $ \ handle_ -> do
1350 buf <- readIORef (haBuffer handle_)
1351 if bufferIsWritable buf && not (bufferEmpty buf)
1352 then do flushed_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
1353 writeIORef (haBuffer handle_) flushed_buf
1357 -- -----------------------------------------------------------------------------
1358 -- Repositioning Handles
1360 data HandlePosn = HandlePosn Handle HandlePosition
1362 instance Eq HandlePosn where
1363 (HandlePosn h1 p1) == (HandlePosn h2 p2) = p1==p2 && h1==h2
1365 instance Show HandlePosn where
1366 showsPrec p (HandlePosn h pos) =
1367 showsPrec p h . showString " at position " . shows pos
1369 -- HandlePosition is the Haskell equivalent of POSIX' off_t.
1370 -- We represent it as an Integer on the Haskell side, but
1371 -- cheat slightly in that hGetPosn calls upon a C helper
1372 -- that reports the position back via (merely) an Int.
1373 type HandlePosition = Integer
1375 -- | Computation 'hGetPosn' @hdl@ returns the current I\/O position of
1376 -- @hdl@ as a value of the abstract type 'HandlePosn'.
1378 hGetPosn :: Handle -> IO HandlePosn
1379 hGetPosn handle = do
1380 posn <- hTell handle
1381 return (HandlePosn handle posn)
1383 -- | If a call to 'hGetPosn' @hdl@ returns a position @p@,
1384 -- then computation 'hSetPosn' @p@ sets the position of @hdl@
1385 -- to the position it held at the time of the call to 'hGetPosn'.
1387 -- This operation may fail with:
1389 -- * 'isPermissionError' if a system resource limit would be exceeded.
1391 hSetPosn :: HandlePosn -> IO ()
1392 hSetPosn (HandlePosn h i) = hSeek h AbsoluteSeek i
1394 -- ---------------------------------------------------------------------------
1397 -- | A mode that determines the effect of 'hSeek' @hdl mode i@, as follows:
1399 = AbsoluteSeek -- ^ the position of @hdl@ is set to @i@.
1400 | RelativeSeek -- ^ the position of @hdl@ is set to offset @i@
1401 -- from the current position.
1402 | SeekFromEnd -- ^ the position of @hdl@ is set to offset @i@
1403 -- from the end of the file.
1404 deriving (Eq, Ord, Ix, Enum, Read, Show)
1407 - when seeking using `SeekFromEnd', positive offsets (>=0) means
1408 seeking at or past EOF.
1410 - we possibly deviate from the report on the issue of seeking within
1411 the buffer and whether to flush it or not. The report isn't exactly
1415 -- | Computation 'hSeek' @hdl mode i@ sets the position of handle
1416 -- @hdl@ depending on @mode@.
1417 -- The offset @i@ is given in terms of 8-bit bytes.
1419 -- If @hdl@ is block- or line-buffered, then seeking to a position which is not
1420 -- in the current buffer will first cause any items in the output buffer to be
1421 -- written to the device, and then cause the input buffer to be discarded.
1422 -- Some handles may not be seekable (see 'hIsSeekable'), or only support a
1423 -- subset of the possible positioning operations (for instance, it may only
1424 -- be possible to seek to the end of a tape, or to a positive offset from
1425 -- the beginning or current position).
1426 -- It is not possible to set a negative I\/O position, or for
1427 -- a physical file, an I\/O position beyond the current end-of-file.
1429 -- This operation may fail with:
1431 -- * 'isPermissionError' if a system resource limit would be exceeded.
1433 hSeek :: Handle -> SeekMode -> Integer -> IO ()
1434 hSeek handle mode offset =
1435 wantSeekableHandle "hSeek" handle $ \ handle_ -> do
1437 puts ("hSeek " ++ show (mode,offset) ++ "\n")
1439 let ref = haBuffer handle_
1440 buf <- readIORef ref
1446 throwErrnoIfMinus1Retry_ "hSeek"
1447 (c_lseek (haFD handle_) (fromIntegral offset) whence)
1450 whence = case mode of
1451 AbsoluteSeek -> sEEK_SET
1452 RelativeSeek -> sEEK_CUR
1453 SeekFromEnd -> sEEK_END
1455 if bufferIsWritable buf
1456 then do new_buf <- flushWriteBuffer fd (haIsStream handle_) buf
1457 writeIORef ref new_buf
1461 if mode == RelativeSeek && offset >= 0 && offset < fromIntegral (w - r)
1462 then writeIORef ref buf{ bufRPtr = r + fromIntegral offset }
1465 new_buf <- flushReadBuffer (haFD handle_) buf
1466 writeIORef ref new_buf
1470 hTell :: Handle -> IO Integer
1472 wantSeekableHandle "hGetPosn" handle $ \ handle_ -> do
1474 #if defined(mingw32_HOST_OS)
1475 -- urgh, on Windows we have to worry about \n -> \r\n translation,
1476 -- so we can't easily calculate the file position using the
1477 -- current buffer size. Just flush instead.
1480 let fd = haFD handle_
1481 posn <- fromIntegral `liftM`
1482 throwErrnoIfMinus1Retry "hGetPosn"
1483 (c_lseek fd 0 sEEK_CUR)
1485 let ref = haBuffer handle_
1486 buf <- readIORef ref
1489 | bufferIsWritable buf = posn + fromIntegral (bufWPtr buf)
1490 | otherwise = posn - fromIntegral (bufWPtr buf - bufRPtr buf)
1492 puts ("\nhGetPosn: (fd, posn, real_posn) = " ++ show (fd, posn, real_posn) ++ "\n")
1493 puts (" (bufWPtr, bufRPtr) = " ++ show (bufWPtr buf, bufRPtr buf) ++ "\n")
1497 -- -----------------------------------------------------------------------------
1498 -- Handle Properties
1500 -- A number of operations return information about the properties of a
1501 -- handle. Each of these operations returns `True' if the handle has
1502 -- the specified property, and `False' otherwise.
1504 hIsOpen :: Handle -> IO Bool
1506 withHandle_ "hIsOpen" handle $ \ handle_ -> do
1507 case haType handle_ of
1508 ClosedHandle -> return False
1509 SemiClosedHandle -> return False
1512 hIsClosed :: Handle -> IO Bool
1514 withHandle_ "hIsClosed" handle $ \ handle_ -> do
1515 case haType handle_ of
1516 ClosedHandle -> return True
1519 {- not defined, nor exported, but mentioned
1520 here for documentation purposes:
1522 hSemiClosed :: Handle -> IO Bool
1526 return (not (ho || hc))
1529 hIsReadable :: Handle -> IO Bool
1530 hIsReadable (DuplexHandle _ _ _) = return True
1531 hIsReadable handle =
1532 withHandle_ "hIsReadable" handle $ \ handle_ -> do
1533 case haType handle_ of
1534 ClosedHandle -> ioe_closedHandle
1535 SemiClosedHandle -> ioe_closedHandle
1536 htype -> return (isReadableHandleType htype)
1538 hIsWritable :: Handle -> IO Bool
1539 hIsWritable (DuplexHandle _ _ _) = return True
1540 hIsWritable handle =
1541 withHandle_ "hIsWritable" handle $ \ handle_ -> do
1542 case haType handle_ of
1543 ClosedHandle -> ioe_closedHandle
1544 SemiClosedHandle -> ioe_closedHandle
1545 htype -> return (isWritableHandleType htype)
1547 -- | Computation 'hGetBuffering' @hdl@ returns the current buffering mode
1550 hGetBuffering :: Handle -> IO BufferMode
1551 hGetBuffering handle =
1552 withHandle_ "hGetBuffering" handle $ \ handle_ -> do
1553 case haType handle_ of
1554 ClosedHandle -> ioe_closedHandle
1556 -- We're being non-standard here, and allow the buffering
1557 -- of a semi-closed handle to be queried. -- sof 6/98
1558 return (haBufferMode handle_) -- could be stricter..
1560 hIsSeekable :: Handle -> IO Bool
1561 hIsSeekable handle =
1562 withHandle_ "hIsSeekable" handle $ \ handle_ -> do
1563 case haType handle_ of
1564 ClosedHandle -> ioe_closedHandle
1565 SemiClosedHandle -> ioe_closedHandle
1566 AppendHandle -> return False
1567 _ -> do t <- fdType (haFD handle_)
1568 return ((t == RegularFile || t == RawDevice)
1569 && (haIsBin handle_ || tEXT_MODE_SEEK_ALLOWED))
1571 -- -----------------------------------------------------------------------------
1572 -- Changing echo status (Non-standard GHC extensions)
1574 -- | Set the echoing status of a handle connected to a terminal.
1576 hSetEcho :: Handle -> Bool -> IO ()
1577 hSetEcho handle on = do
1578 isT <- hIsTerminalDevice handle
1582 withHandle_ "hSetEcho" handle $ \ handle_ -> do
1583 case haType handle_ of
1584 ClosedHandle -> ioe_closedHandle
1585 _ -> setEcho (haFD handle_) on
1587 -- | Get the echoing status of a handle connected to a terminal.
1589 hGetEcho :: Handle -> IO Bool
1590 hGetEcho handle = do
1591 isT <- hIsTerminalDevice handle
1595 withHandle_ "hGetEcho" handle $ \ handle_ -> do
1596 case haType handle_ of
1597 ClosedHandle -> ioe_closedHandle
1598 _ -> getEcho (haFD handle_)
1600 -- | Is the handle connected to a terminal?
1602 hIsTerminalDevice :: Handle -> IO Bool
1603 hIsTerminalDevice handle = do
1604 withHandle_ "hIsTerminalDevice" handle $ \ handle_ -> do
1605 case haType handle_ of
1606 ClosedHandle -> ioe_closedHandle
1607 _ -> fdIsTTY (haFD handle_)
1609 -- -----------------------------------------------------------------------------
1612 -- | Select binary mode ('True') or text mode ('False') on a open handle.
1613 -- (See also 'openBinaryFile'.)
1615 hSetBinaryMode :: Handle -> Bool -> IO ()
1616 hSetBinaryMode handle bin =
1617 withAllHandles__ "hSetBinaryMode" handle $ \ handle_ ->
1618 do throwErrnoIfMinus1_ "hSetBinaryMode"
1619 (setmode (haFD handle_) bin)
1620 return handle_{haIsBin=bin}
1622 foreign import ccall unsafe "__hscore_setmode"
1623 setmode :: CInt -> Bool -> IO CInt
1625 -- -----------------------------------------------------------------------------
1626 -- Duplicating a Handle
1628 -- | Returns a duplicate of the original handle, with its own buffer.
1629 -- The two Handles will share a file pointer, however. The original
1630 -- handle's buffer is flushed, including discarding any input data,
1631 -- before the handle is duplicated.
1633 hDuplicate :: Handle -> IO Handle
1634 hDuplicate h@(FileHandle path m) = do
1635 new_h_ <- withHandle' "hDuplicate" h m (dupHandle h Nothing)
1636 newFileHandle path (handleFinalizer path) new_h_
1637 hDuplicate h@(DuplexHandle path r w) = do
1638 new_w_ <- withHandle' "hDuplicate" h w (dupHandle h Nothing)
1639 new_w <- newMVar new_w_
1640 new_r_ <- withHandle' "hDuplicate" h r (dupHandle h (Just new_w))
1641 new_r <- newMVar new_r_
1642 addMVarFinalizer new_w (handleFinalizer path new_w)
1643 return (DuplexHandle path new_r new_w)
1645 dupHandle :: Handle -> Maybe (MVar Handle__) -> Handle__
1646 -> IO (Handle__, Handle__)
1647 dupHandle h other_side h_ = do
1648 -- flush the buffer first, so we don't have to copy its contents
1650 new_fd <- case other_side of
1651 Nothing -> throwErrnoIfMinus1 "dupHandle" $ c_dup (haFD h_)
1652 Just r -> withHandle_' "dupHandle" h r (return . haFD)
1653 dupHandle_ other_side h_ new_fd
1655 dupHandleTo other_side hto_ h_ = do
1657 -- Windows' dup2 does not return the new descriptor, unlike Unix
1658 throwErrnoIfMinus1 "dupHandleTo" $
1659 c_dup2 (haFD h_) (haFD hto_)
1660 dupHandle_ other_side h_ (haFD hto_)
1662 dupHandle_ :: Maybe (MVar Handle__) -> Handle__ -> FD
1663 -> IO (Handle__, Handle__)
1664 dupHandle_ other_side h_ new_fd = do
1665 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE (initBufferState (haType h_))
1666 ioref <- newIORef buffer
1667 ioref_buffers <- newIORef BufferListNil
1669 let new_handle_ = h_{ haFD = new_fd,
1671 haBuffers = ioref_buffers,
1672 haOtherSide = other_side }
1673 return (h_, new_handle_)
1675 -- -----------------------------------------------------------------------------
1676 -- Replacing a Handle
1679 Makes the second handle a duplicate of the first handle. The second
1680 handle will be closed first, if it is not already.
1682 This can be used to retarget the standard Handles, for example:
1684 > do h <- openFile "mystdout" WriteMode
1685 > hDuplicateTo h stdout
1688 hDuplicateTo :: Handle -> Handle -> IO ()
1689 hDuplicateTo h1@(FileHandle _ m1) h2@(FileHandle _ m2) = do
1690 withHandle__' "hDuplicateTo" h2 m2 $ \h2_ -> do
1691 _ <- hClose_help h2_
1692 withHandle' "hDuplicateTo" h1 m1 (dupHandleTo Nothing h2_)
1693 hDuplicateTo h1@(DuplexHandle _ r1 w1) h2@(DuplexHandle _ r2 w2) = do
1694 withHandle__' "hDuplicateTo" h2 w2 $ \w2_ -> do
1695 _ <- hClose_help w2_
1696 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo Nothing w2_)
1697 withHandle__' "hDuplicateTo" h2 r2 $ \r2_ -> do
1698 _ <- hClose_help r2_
1699 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo (Just w1) r2_)
1701 ioException (IOError (Just h1) IllegalOperation "hDuplicateTo"
1702 "handles are incompatible" Nothing)
1704 -- ---------------------------------------------------------------------------
1707 -- | 'hShow' is in the 'IO' monad, and gives more comprehensive output
1708 -- than the (pure) instance of 'Show' for 'Handle'.
1710 hShow :: Handle -> IO String
1711 hShow h@(FileHandle path _) = showHandle' path False h
1712 hShow h@(DuplexHandle path _ _) = showHandle' path True h
1714 showHandle' filepath is_duplex h =
1715 withHandle_ "showHandle" h $ \hdl_ ->
1717 showType | is_duplex = showString "duplex (read-write)"
1718 | otherwise = shows (haType hdl_)
1722 showHdl (haType hdl_)
1723 (showString "loc=" . showString filepath . showChar ',' .
1724 showString "type=" . showType . showChar ',' .
1725 showString "binary=" . shows (haIsBin hdl_) . showChar ',' .
1726 showString "buffering=" . showBufMode (unsafePerformIO (readIORef (haBuffer hdl_))) (haBufferMode hdl_) . showString "}" )
1730 showHdl :: HandleType -> ShowS -> ShowS
1733 ClosedHandle -> shows ht . showString "}"
1736 showBufMode :: Buffer -> BufferMode -> ShowS
1737 showBufMode buf bmo =
1739 NoBuffering -> showString "none"
1740 LineBuffering -> showString "line"
1741 BlockBuffering (Just n) -> showString "block " . showParen True (shows n)
1742 BlockBuffering Nothing -> showString "block " . showParen True (shows def)
1747 -- ---------------------------------------------------------------------------
1750 #if defined(DEBUG_DUMP)
1751 puts :: String -> IO ()
1752 puts s = do write_rawBuffer 1 (unsafeCoerce# (packCString# s)) 0 (fromIntegral (length s))
1756 -- -----------------------------------------------------------------------------
1759 throwErrnoIfMinus1RetryOnBlock :: String -> IO CInt -> IO CInt -> IO CInt
1760 throwErrnoIfMinus1RetryOnBlock loc f on_block =
1763 if (res :: CInt) == -1
1767 then throwErrnoIfMinus1RetryOnBlock loc f on_block
1768 else if err == eWOULDBLOCK || err == eAGAIN
1773 -- -----------------------------------------------------------------------------
1774 -- wrappers to platform-specific constants:
1776 foreign import ccall unsafe "__hscore_supportsTextMode"
1777 tEXT_MODE_SEEK_ALLOWED :: Bool
1779 foreign import ccall unsafe "__hscore_bufsiz" dEFAULT_BUFFER_SIZE :: Int
1780 foreign import ccall unsafe "__hscore_seek_cur" sEEK_CUR :: CInt
1781 foreign import ccall unsafe "__hscore_seek_set" sEEK_SET :: CInt
1782 foreign import ccall unsafe "__hscore_seek_end" sEEK_END :: CInt