1 {-# OPTIONS_GHC -fno-implicit-prelude -#include "HsBase.h" #-}
6 -----------------------------------------------------------------------------
9 -- Copyright : (c) The University of Glasgow, 1994-2001
10 -- License : see libraries/base/LICENSE
12 -- Maintainer : libraries@haskell.org
13 -- Stability : internal
14 -- Portability : non-portable
16 -- This module defines the basic operations on I\/O \"handles\".
18 -----------------------------------------------------------------------------
22 withHandle, withHandle', withHandle_,
23 wantWritableHandle, wantReadableHandle, wantSeekableHandle,
25 newEmptyBuffer, allocateBuffer, readCharFromBuffer, writeCharIntoBuffer,
26 flushWriteBufferOnly, flushWriteBuffer, flushReadBuffer,
27 fillReadBuffer, fillReadBufferWithoutBlocking,
28 readRawBuffer, readRawBufferPtr,
29 writeRawBuffer, writeRawBufferPtr,
31 #ifndef mingw32_HOST_OS
35 ioe_closedHandle, ioe_EOF, ioe_notReadable, ioe_notWritable,
37 stdin, stdout, stderr,
38 IOMode(..), openFile, openBinaryFile, openTempFile, openBinaryTempFile, openFd, fdToHandle,
39 hFileSize, hSetFileSize, hIsEOF, isEOF, hLookAhead, hSetBuffering, hSetBinaryMode,
40 hFlush, hDuplicate, hDuplicateTo,
44 HandlePosition, HandlePosn(..), hGetPosn, hSetPosn,
45 SeekMode(..), hSeek, hTell,
47 hIsOpen, hIsClosed, hIsReadable, hIsWritable, hGetBuffering, hIsSeekable,
48 hSetEcho, hGetEcho, hIsTerminalDevice,
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 = throwErrnoIfMinus1RetryMayBlock 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
601 if r /= 0 then safe_write
604 do_write call = throwErrnoIfMinus1RetryMayBlock loc call
605 (threadWaitWrite (fromIntegral fd))
606 unsafe_write = do_write (write_rawBuffer fd buf off len)
607 safe_write = do_write (safe_write_rawBuffer (fromIntegral fd) buf off len)
609 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
610 writeRawBufferPtr loc fd is_nonblock buf off len
611 | is_nonblock = unsafe_write
612 | threaded = safe_write
613 | otherwise = do r <- fdReady (fromIntegral fd) 1 0 False
614 if r /= 0 then safe_write
617 do_write call = throwErrnoIfMinus1RetryMayBlock loc call
618 (threadWaitWrite (fromIntegral fd))
619 unsafe_write = do_write (write_off fd buf off len)
620 safe_write = do_write (safe_write_off (fromIntegral fd) buf off len)
622 foreign import ccall unsafe "__hscore_PrelHandle_read"
623 read_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
625 foreign import ccall unsafe "__hscore_PrelHandle_read"
626 read_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
628 foreign import ccall unsafe "__hscore_PrelHandle_write"
629 write_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
631 foreign import ccall unsafe "__hscore_PrelHandle_write"
632 write_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
634 foreign import ccall safe "fdReady"
635 fdReady :: CInt -> CInt -> CInt -> Bool -> IO CInt
637 #else /* mingw32_HOST_OS.... */
639 readRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
640 readRawBuffer loc fd is_stream buf off len
641 | threaded = blockingReadRawBuffer loc fd is_stream buf off len
642 | otherwise = asyncReadRawBuffer loc fd is_stream buf off len
644 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
645 readRawBufferPtr loc fd is_stream buf off len
646 | threaded = blockingReadRawBufferPtr loc fd is_stream buf off len
647 | otherwise = asyncReadRawBufferPtr loc fd is_stream buf off len
649 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
650 writeRawBuffer loc fd is_stream buf off len
651 | threaded = blockingWriteRawBuffer loc fd is_stream buf off len
652 | otherwise = asyncWriteRawBuffer loc fd is_stream buf off len
654 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
655 writeRawBufferPtr loc fd is_stream buf off len
656 | threaded = blockingWriteRawBufferPtr loc fd is_stream buf off len
657 | otherwise = asyncWriteRawBufferPtr loc fd is_stream buf off len
659 -- ToDo: we don't have a non-blocking primitve read on Win32
660 readRawBufferNoBlock :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
661 readRawBufferNoBlock = readRawBuffer
663 -- Async versions of the read/write primitives, for the non-threaded RTS
665 asyncReadRawBuffer loc fd is_stream buf off len = do
666 (l, rc) <- asyncReadBA (fromIntegral fd) (if is_stream then 1 else 0)
667 (fromIntegral len) off buf
670 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
671 else return (fromIntegral l)
673 asyncReadRawBufferPtr loc fd is_stream buf off len = do
674 (l, rc) <- asyncRead (fromIntegral fd) (if is_stream then 1 else 0)
675 (fromIntegral len) (buf `plusPtr` off)
678 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
679 else return (fromIntegral l)
681 asyncWriteRawBuffer loc fd is_stream buf off len = do
682 (l, rc) <- asyncWriteBA (fromIntegral fd) (if is_stream then 1 else 0)
683 (fromIntegral len) off buf
686 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
687 else return (fromIntegral l)
689 asyncWriteRawBufferPtr loc fd is_stream buf off len = do
690 (l, rc) <- asyncWrite (fromIntegral fd) (if is_stream then 1 else 0)
691 (fromIntegral len) (buf `plusPtr` off)
694 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
695 else return (fromIntegral l)
697 -- Blocking versions of the read/write primitives, for the threaded RTS
699 blockingReadRawBuffer loc fd True buf off len =
700 throwErrnoIfMinus1Retry loc $
701 safe_recv_rawBuffer fd buf off len
702 blockingReadRawBuffer loc fd False buf off len =
703 throwErrnoIfMinus1Retry loc $
704 safe_read_rawBuffer fd buf off len
706 blockingReadRawBufferPtr loc fd True buf off len =
707 throwErrnoIfMinus1Retry loc $
708 safe_recv_off fd buf off len
709 blockingReadRawBufferPtr loc fd False buf off len =
710 throwErrnoIfMinus1Retry loc $
711 safe_read_off fd buf off len
713 blockingWriteRawBuffer loc fd True buf off len =
714 throwErrnoIfMinus1Retry loc $
715 safe_send_rawBuffer fd buf off len
716 blockingWriteRawBuffer loc fd False buf off len =
717 throwErrnoIfMinus1Retry loc $
718 safe_write_rawBuffer fd buf off len
720 blockingWriteRawBufferPtr loc fd True buf off len =
721 throwErrnoIfMinus1Retry loc $
722 safe_send_off fd buf off len
723 blockingWriteRawBufferPtr loc fd False buf off len =
724 throwErrnoIfMinus1Retry loc $
725 safe_write_off fd buf off len
727 -- NOTE: "safe" versions of the read/write calls for use by the threaded RTS.
728 -- These calls may block, but that's ok.
730 foreign import ccall safe "__hscore_PrelHandle_recv"
731 safe_recv_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
733 foreign import ccall safe "__hscore_PrelHandle_recv"
734 safe_recv_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
736 foreign import ccall safe "__hscore_PrelHandle_send"
737 safe_send_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
739 foreign import ccall safe "__hscore_PrelHandle_send"
740 safe_send_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
744 foreign import ccall "rtsSupportsBoundThreads" threaded :: Bool
746 foreign import ccall safe "__hscore_PrelHandle_read"
747 safe_read_rawBuffer :: FD -> RawBuffer -> Int -> CInt -> IO CInt
749 foreign import ccall safe "__hscore_PrelHandle_read"
750 safe_read_off :: FD -> Ptr CChar -> Int -> CInt -> IO CInt
752 foreign import ccall safe "__hscore_PrelHandle_write"
753 safe_write_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
755 foreign import ccall safe "__hscore_PrelHandle_write"
756 safe_write_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
758 -- ---------------------------------------------------------------------------
761 -- Three handles are allocated during program initialisation. The first
762 -- two manage input or output from the Haskell program's standard input
763 -- or output channel respectively. The third manages output to the
764 -- standard error channel. These handles are initially open.
770 -- | A handle managing input from the Haskell program's standard input channel.
772 stdin = unsafePerformIO $ do
773 -- ToDo: acquire lock
774 -- We don't set non-blocking mode on standard handles, because it may
775 -- confuse other applications attached to the same TTY/pipe
776 -- see Note [nonblock]
777 (buf, bmode) <- getBuffer fd_stdin ReadBuffer
778 mkStdHandle fd_stdin "<stdin>" ReadHandle buf bmode
780 -- | A handle managing output to the Haskell program's standard output channel.
782 stdout = unsafePerformIO $ do
783 -- ToDo: acquire lock
784 -- We don't set non-blocking mode on standard handles, because it may
785 -- confuse other applications attached to the same TTY/pipe
786 -- see Note [nonblock]
787 (buf, bmode) <- getBuffer fd_stdout WriteBuffer
788 mkStdHandle fd_stdout "<stdout>" WriteHandle buf bmode
790 -- | A handle managing output to the Haskell program's standard error channel.
792 stderr = unsafePerformIO $ do
793 -- ToDo: acquire lock
794 -- We don't set non-blocking mode on standard handles, because it may
795 -- confuse other applications attached to the same TTY/pipe
796 -- see Note [nonblock]
798 mkStdHandle fd_stderr "<stderr>" WriteHandle buf NoBuffering
800 -- ---------------------------------------------------------------------------
801 -- Opening and Closing Files
803 addFilePathToIOError fun fp (IOError h iot _ str _)
804 = IOError h iot fun str (Just fp)
806 -- | Computation 'openFile' @file mode@ allocates and returns a new, open
807 -- handle to manage the file @file@. It manages input if @mode@
808 -- is 'ReadMode', output if @mode@ is 'WriteMode' or 'AppendMode',
809 -- and both input and output if mode is 'ReadWriteMode'.
811 -- If the file does not exist and it is opened for output, it should be
812 -- created as a new file. If @mode@ is 'WriteMode' and the file
813 -- already exists, then it should be truncated to zero length.
814 -- Some operating systems delete empty files, so there is no guarantee
815 -- that the file will exist following an 'openFile' with @mode@
816 -- 'WriteMode' unless it is subsequently written to successfully.
817 -- The handle is positioned at the end of the file if @mode@ is
818 -- 'AppendMode', and otherwise at the beginning (in which case its
819 -- internal position is 0).
820 -- The initial buffer mode is implementation-dependent.
822 -- This operation may fail with:
824 -- * 'isAlreadyInUseError' if the file is already open and cannot be reopened;
826 -- * 'isDoesNotExistError' if the file does not exist; or
828 -- * 'isPermissionError' if the user does not have permission to open the file.
830 -- Note: if you will be working with files containing binary data, you'll want to
831 -- be using 'openBinaryFile'.
832 openFile :: FilePath -> IOMode -> IO Handle
835 (openFile' fp im dEFAULT_OPEN_IN_BINARY_MODE)
836 (\e -> ioError (addFilePathToIOError "openFile" fp e))
838 -- | Like 'openFile', but open the file in binary mode.
839 -- On Windows, reading a file in text mode (which is the default)
840 -- will translate CRLF to LF, and writing will translate LF to CRLF.
841 -- This is usually what you want with text files. With binary files
842 -- this is undesirable; also, as usual under Microsoft operating systems,
843 -- text mode treats control-Z as EOF. Binary mode turns off all special
844 -- treatment of end-of-line and end-of-file characters.
845 -- (See also 'hSetBinaryMode'.)
847 openBinaryFile :: FilePath -> IOMode -> IO Handle
848 openBinaryFile fp m =
850 (openFile' fp m True)
851 (\e -> ioError (addFilePathToIOError "openBinaryFile" fp e))
853 openFile' filepath mode binary =
854 withCString filepath $ \ f ->
857 oflags1 = case mode of
858 ReadMode -> read_flags
859 #ifdef mingw32_HOST_OS
860 WriteMode -> write_flags .|. o_TRUNC
862 WriteMode -> write_flags
864 ReadWriteMode -> rw_flags
865 AppendMode -> append_flags
871 oflags = oflags1 .|. binary_flags
874 -- the old implementation had a complicated series of three opens,
875 -- which is perhaps because we have to be careful not to open
876 -- directories. However, the man pages I've read say that open()
877 -- always returns EISDIR if the file is a directory and was opened
878 -- for writing, so I think we're ok with a single open() here...
879 fd <- throwErrnoIfMinus1Retry "openFile"
880 (c_open f (fromIntegral oflags) 0o666)
884 h <- openFd fd (Just fd_type) False filepath mode binary
885 `catchException` \e -> do c_close fd; throw e
886 -- NB. don't forget to close the FD if openFd fails, otherwise
888 -- ASSERT: if we just created the file, then openFd won't fail
889 -- (so we don't need to worry about removing the newly created file
890 -- in the event of an error).
892 #ifndef mingw32_HOST_OS
893 -- we want to truncate() if this is an open in WriteMode, but only
894 -- if the target is a RegularFile. ftruncate() fails on special files
896 if mode == WriteMode && fd_type == RegularFile
897 then throwErrnoIf (/=0) "openFile"
904 -- | The function creates a temporary file in ReadWrite mode.
905 -- The created file isn\'t deleted automatically, so you need to delete it manually.
906 openTempFile :: FilePath -- ^ Directory in which to create the file
907 -> String -- ^ File name template. If the template is \"foo.ext\" then
908 -- the create file will be \"fooXXX.ext\" where XXX is some
910 -> IO (FilePath, Handle)
911 openTempFile tmp_dir template = openTempFile' "openTempFile" tmp_dir template dEFAULT_OPEN_IN_BINARY_MODE
913 -- | Like 'openTempFile', but opens the file in binary mode. See 'openBinaryFile' for more comments.
914 openBinaryTempFile :: FilePath -> String -> IO (FilePath, Handle)
915 openBinaryTempFile tmp_dir template = openTempFile' "openBinaryTempFile" tmp_dir template True
917 openTempFile' :: String -> FilePath -> String -> Bool -> IO (FilePath, Handle)
918 openTempFile' loc tmp_dir template binary = do
922 (prefix,suffix) = break (=='.') template
924 oflags1 = rw_flags .|. o_EXCL
930 oflags = oflags1 .|. binary_flags
933 fd <- withCString filepath $ \ f ->
934 c_open f oflags 0o666
939 then findTempName (x+1)
940 else ioError (errnoToIOError loc errno Nothing (Just tmp_dir))
942 h <- openFd fd Nothing False filepath ReadWriteMode True
943 `catchException` \e -> do c_close fd; throw e
946 filename = prefix ++ show x ++ suffix
947 filepath = tmp_dir ++ [pathSeparator] ++ filename
949 pathSeparator :: Char
950 #ifdef mingw32_HOST_OS
956 std_flags = o_NONBLOCK .|. o_NOCTTY
957 output_flags = std_flags .|. o_CREAT
958 read_flags = std_flags .|. o_RDONLY
959 write_flags = output_flags .|. o_WRONLY
960 rw_flags = output_flags .|. o_RDWR
961 append_flags = write_flags .|. o_APPEND
963 -- ---------------------------------------------------------------------------
966 openFd :: FD -> Maybe FDType -> Bool -> FilePath -> IOMode -> Bool -> IO Handle
967 openFd fd mb_fd_type is_socket filepath mode binary = do
968 -- turn on non-blocking mode
971 #ifdef mingw32_HOST_OS
972 -- On Windows, the is_stream flag indicates that the Handle is a socket
973 let is_stream = is_socket
975 -- On Unix, the is_stream flag indicates that the FD is non-blocking
979 let (ha_type, write) =
981 ReadMode -> ( ReadHandle, False )
982 WriteMode -> ( WriteHandle, True )
983 ReadWriteMode -> ( ReadWriteHandle, True )
984 AppendMode -> ( AppendHandle, True )
986 -- open() won't tell us if it was a directory if we only opened for
987 -- reading, so check again.
995 ioException (IOError Nothing InappropriateType "openFile"
996 "is a directory" Nothing)
998 -- regular files need to be locked
1000 #ifndef mingw32_HOST_OS
1001 r <- lockFile fd (fromBool write) 1{-exclusive-}
1003 ioException (IOError Nothing ResourceBusy "openFile"
1004 "file is locked" Nothing)
1006 mkFileHandle fd is_stream filepath ha_type binary
1009 -- only *Streams* can be DuplexHandles. Other read/write
1010 -- Handles must share a buffer.
1011 | ReadWriteHandle <- ha_type ->
1012 mkDuplexHandle fd is_stream filepath binary
1014 mkFileHandle fd is_stream filepath ha_type binary
1017 mkFileHandle fd is_stream filepath ha_type binary
1019 fdToHandle :: FD -> IO Handle
1021 mode <- fdGetMode fd
1022 let fd_str = "<file descriptor: " ++ show fd ++ ">"
1023 openFd fd Nothing False{-XXX!-} fd_str mode True{-bin mode-}
1026 #ifndef mingw32_HOST_OS
1027 foreign import ccall unsafe "lockFile"
1028 lockFile :: CInt -> CInt -> CInt -> IO CInt
1030 foreign import ccall unsafe "unlockFile"
1031 unlockFile :: CInt -> IO CInt
1034 mkStdHandle :: FD -> FilePath -> HandleType -> IORef Buffer -> BufferMode
1036 mkStdHandle fd filepath ha_type buf bmode = do
1037 spares <- newIORef BufferListNil
1038 newFileHandle filepath (stdHandleFinalizer filepath)
1039 (Handle__ { haFD = fd,
1041 haIsBin = dEFAULT_OPEN_IN_BINARY_MODE,
1042 haIsStream = False, -- means FD is blocking on Unix
1043 haBufferMode = bmode,
1046 haOtherSide = Nothing
1049 mkFileHandle :: FD -> Bool -> FilePath -> HandleType -> Bool -> IO Handle
1050 mkFileHandle fd is_stream filepath ha_type binary = do
1051 (buf, bmode) <- getBuffer fd (initBufferState ha_type)
1053 #ifdef mingw32_HOST_OS
1054 -- On Windows, if this is a read/write handle and we are in text mode,
1055 -- turn off buffering. We don't correctly handle the case of switching
1056 -- from read mode to write mode on a buffered text-mode handle, see bug
1058 bmode <- case ha_type of
1059 ReadWriteHandle | not binary -> return NoBuffering
1060 _other -> return bmode
1063 spares <- newIORef BufferListNil
1064 newFileHandle filepath (handleFinalizer filepath)
1065 (Handle__ { haFD = fd,
1068 haIsStream = is_stream,
1069 haBufferMode = bmode,
1072 haOtherSide = Nothing
1075 mkDuplexHandle :: FD -> Bool -> FilePath -> Bool -> IO Handle
1076 mkDuplexHandle fd is_stream filepath binary = do
1077 (w_buf, w_bmode) <- getBuffer fd WriteBuffer
1078 w_spares <- newIORef BufferListNil
1080 Handle__ { haFD = fd,
1081 haType = WriteHandle,
1083 haIsStream = is_stream,
1084 haBufferMode = w_bmode,
1086 haBuffers = w_spares,
1087 haOtherSide = Nothing
1089 write_side <- newMVar w_handle_
1091 (r_buf, r_bmode) <- getBuffer fd ReadBuffer
1092 r_spares <- newIORef BufferListNil
1094 Handle__ { haFD = fd,
1095 haType = ReadHandle,
1097 haIsStream = is_stream,
1098 haBufferMode = r_bmode,
1100 haBuffers = r_spares,
1101 haOtherSide = Just write_side
1103 read_side <- newMVar r_handle_
1105 addMVarFinalizer write_side (handleFinalizer filepath write_side)
1106 return (DuplexHandle filepath read_side write_side)
1109 initBufferState ReadHandle = ReadBuffer
1110 initBufferState _ = WriteBuffer
1112 -- ---------------------------------------------------------------------------
1115 -- | Computation 'hClose' @hdl@ makes handle @hdl@ closed. Before the
1116 -- computation finishes, if @hdl@ is writable its buffer is flushed as
1118 -- Performing 'hClose' on a handle that has already been closed has no effect;
1119 -- doing so not an error. All other operations on a closed handle will fail.
1120 -- If 'hClose' fails for any reason, any further operations (apart from
1121 -- 'hClose') on the handle will still fail as if @hdl@ had been successfully
1124 hClose :: Handle -> IO ()
1125 hClose h@(FileHandle _ m) = hClose' h m
1126 hClose h@(DuplexHandle _ r w) = hClose' h w >> hClose' h r
1128 hClose' h m = withHandle__' "hClose" h m $ hClose_help
1130 -- hClose_help is also called by lazyRead (in PrelIO) when EOF is read
1131 -- or an IO error occurs on a lazy stream. The semi-closed Handle is
1132 -- then closed immediately. We have to be careful with DuplexHandles
1133 -- though: we have to leave the closing to the finalizer in that case,
1134 -- because the write side may still be in use.
1135 hClose_help :: Handle__ -> IO Handle__
1136 hClose_help handle_ =
1137 case haType handle_ of
1138 ClosedHandle -> return handle_
1139 _ -> do flushWriteBufferOnly handle_ -- interruptible
1140 hClose_handle_ handle_
1142 hClose_handle_ handle_ = do
1143 let fd = haFD handle_
1145 -- close the file descriptor, but not when this is the read
1146 -- side of a duplex handle.
1147 case haOtherSide handle_ of
1149 throwErrnoIfMinus1Retry_ "hClose"
1150 #ifdef mingw32_HOST_OS
1151 (closeFd (haIsStream handle_) fd)
1157 -- free the spare buffers
1158 writeIORef (haBuffers handle_) BufferListNil
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
1171 -----------------------------------------------------------------------------
1172 -- Detecting and changing the size of a file
1174 -- | For a handle @hdl@ which attached to a physical file,
1175 -- 'hFileSize' @hdl@ returns the size of that file in 8-bit bytes.
1177 hFileSize :: Handle -> IO Integer
1179 withHandle_ "hFileSize" handle $ \ handle_ -> do
1180 case haType handle_ of
1181 ClosedHandle -> ioe_closedHandle
1182 SemiClosedHandle -> ioe_closedHandle
1183 _ -> do flushWriteBufferOnly handle_
1184 r <- fdFileSize (haFD handle_)
1187 else ioException (IOError Nothing InappropriateType "hFileSize"
1188 "not a regular file" Nothing)
1191 -- | 'hSetFileSize' @hdl@ @size@ truncates the physical file with handle @hdl@ to @size@ bytes.
1193 hSetFileSize :: Handle -> Integer -> IO ()
1194 hSetFileSize handle size =
1195 withHandle_ "hSetFileSize" handle $ \ handle_ -> do
1196 case haType handle_ of
1197 ClosedHandle -> ioe_closedHandle
1198 SemiClosedHandle -> ioe_closedHandle
1199 _ -> do flushWriteBufferOnly handle_
1200 throwErrnoIf (/=0) "hSetFileSize"
1201 (c_ftruncate (haFD handle_) (fromIntegral size))
1204 -- ---------------------------------------------------------------------------
1205 -- Detecting the End of Input
1207 -- | For a readable handle @hdl@, 'hIsEOF' @hdl@ returns
1208 -- 'True' if no further input can be taken from @hdl@ or for a
1209 -- physical file, if the current I\/O position is equal to the length of
1210 -- the file. Otherwise, it returns 'False'.
1212 hIsEOF :: Handle -> IO Bool
1215 (do hLookAhead handle; return False)
1216 (\e -> if isEOFError e then return True else ioError e)
1218 -- | The computation 'isEOF' is identical to 'hIsEOF',
1219 -- except that it works only on 'stdin'.
1222 isEOF = hIsEOF stdin
1224 -- ---------------------------------------------------------------------------
1227 -- | Computation 'hLookAhead' returns the next character from the handle
1228 -- without removing it from the input buffer, blocking until a character
1231 -- This operation may fail with:
1233 -- * 'isEOFError' if the end of file has been reached.
1235 hLookAhead :: Handle -> IO Char
1236 hLookAhead handle = do
1237 wantReadableHandle "hLookAhead" handle $ \handle_ -> do
1238 let ref = haBuffer handle_
1240 is_line = haBufferMode handle_ == LineBuffering
1241 buf <- readIORef ref
1243 -- fill up the read buffer if necessary
1244 new_buf <- if bufferEmpty buf
1245 then fillReadBuffer fd True (haIsStream handle_) buf
1248 writeIORef ref new_buf
1250 (c,_) <- readCharFromBuffer (bufBuf buf) (bufRPtr buf)
1253 -- ---------------------------------------------------------------------------
1254 -- Buffering Operations
1256 -- Three kinds of buffering are supported: line-buffering,
1257 -- block-buffering or no-buffering. See GHC.IOBase for definition and
1258 -- further explanation of what the type represent.
1260 -- | Computation 'hSetBuffering' @hdl mode@ sets the mode of buffering for
1261 -- handle @hdl@ on subsequent reads and writes.
1263 -- If the buffer mode is changed from 'BlockBuffering' or
1264 -- 'LineBuffering' to 'NoBuffering', then
1266 -- * if @hdl@ is writable, the buffer is flushed as for 'hFlush';
1268 -- * if @hdl@ is not writable, the contents of the buffer is discarded.
1270 -- This operation may fail with:
1272 -- * 'isPermissionError' if the handle has already been used for reading
1273 -- or writing and the implementation does not allow the buffering mode
1276 hSetBuffering :: Handle -> BufferMode -> IO ()
1277 hSetBuffering handle mode =
1278 withAllHandles__ "hSetBuffering" handle $ \ handle_ -> do
1279 case haType handle_ of
1280 ClosedHandle -> ioe_closedHandle
1283 - we flush the old buffer regardless of whether
1284 the new buffer could fit the contents of the old buffer
1286 - allow a handle's buffering to change even if IO has
1287 occurred (ANSI C spec. does not allow this, nor did
1288 the previous implementation of IO.hSetBuffering).
1289 - a non-standard extension is to allow the buffering
1290 of semi-closed handles to change [sof 6/98]
1294 let state = initBufferState (haType handle_)
1297 -- we always have a 1-character read buffer for
1298 -- unbuffered handles: it's needed to
1299 -- support hLookAhead.
1300 NoBuffering -> allocateBuffer 1 ReadBuffer
1301 LineBuffering -> allocateBuffer dEFAULT_BUFFER_SIZE state
1302 BlockBuffering Nothing -> allocateBuffer dEFAULT_BUFFER_SIZE state
1303 BlockBuffering (Just n) | n <= 0 -> ioe_bufsiz n
1304 | otherwise -> allocateBuffer n state
1305 writeIORef (haBuffer handle_) new_buf
1307 -- for input terminals we need to put the terminal into
1308 -- cooked or raw mode depending on the type of buffering.
1309 is_tty <- fdIsTTY (haFD handle_)
1310 when (is_tty && isReadableHandleType (haType handle_)) $
1312 #ifndef mingw32_HOST_OS
1313 -- 'raw' mode under win32 is a bit too specialised (and troublesome
1314 -- for most common uses), so simply disable its use here.
1315 NoBuffering -> setCooked (haFD handle_) False
1317 NoBuffering -> return ()
1319 _ -> setCooked (haFD handle_) True
1321 -- throw away spare buffers, they might be the wrong size
1322 writeIORef (haBuffers handle_) BufferListNil
1324 return (handle_{ haBufferMode = mode })
1326 -- -----------------------------------------------------------------------------
1329 -- | The action 'hFlush' @hdl@ causes any items buffered for output
1330 -- in handle @hdl@ to be sent immediately to the operating system.
1332 -- This operation may fail with:
1334 -- * 'isFullError' if the device is full;
1336 -- * 'isPermissionError' if a system resource limit would be exceeded.
1337 -- It is unspecified whether the characters in the buffer are discarded
1338 -- or retained under these circumstances.
1340 hFlush :: Handle -> IO ()
1342 wantWritableHandle "hFlush" handle $ \ handle_ -> do
1343 buf <- readIORef (haBuffer handle_)
1344 if bufferIsWritable buf && not (bufferEmpty buf)
1345 then do flushed_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
1346 writeIORef (haBuffer handle_) flushed_buf
1350 -- -----------------------------------------------------------------------------
1351 -- Repositioning Handles
1353 data HandlePosn = HandlePosn Handle HandlePosition
1355 instance Eq HandlePosn where
1356 (HandlePosn h1 p1) == (HandlePosn h2 p2) = p1==p2 && h1==h2
1358 instance Show HandlePosn where
1359 showsPrec p (HandlePosn h pos) =
1360 showsPrec p h . showString " at position " . shows pos
1362 -- HandlePosition is the Haskell equivalent of POSIX' off_t.
1363 -- We represent it as an Integer on the Haskell side, but
1364 -- cheat slightly in that hGetPosn calls upon a C helper
1365 -- that reports the position back via (merely) an Int.
1366 type HandlePosition = Integer
1368 -- | Computation 'hGetPosn' @hdl@ returns the current I\/O position of
1369 -- @hdl@ as a value of the abstract type 'HandlePosn'.
1371 hGetPosn :: Handle -> IO HandlePosn
1372 hGetPosn handle = do
1373 posn <- hTell handle
1374 return (HandlePosn handle posn)
1376 -- | If a call to 'hGetPosn' @hdl@ returns a position @p@,
1377 -- then computation 'hSetPosn' @p@ sets the position of @hdl@
1378 -- to the position it held at the time of the call to 'hGetPosn'.
1380 -- This operation may fail with:
1382 -- * 'isPermissionError' if a system resource limit would be exceeded.
1384 hSetPosn :: HandlePosn -> IO ()
1385 hSetPosn (HandlePosn h i) = hSeek h AbsoluteSeek i
1387 -- ---------------------------------------------------------------------------
1390 -- | A mode that determines the effect of 'hSeek' @hdl mode i@, as follows:
1392 = AbsoluteSeek -- ^ the position of @hdl@ is set to @i@.
1393 | RelativeSeek -- ^ the position of @hdl@ is set to offset @i@
1394 -- from the current position.
1395 | SeekFromEnd -- ^ the position of @hdl@ is set to offset @i@
1396 -- from the end of the file.
1397 deriving (Eq, Ord, Ix, Enum, Read, Show)
1400 - when seeking using `SeekFromEnd', positive offsets (>=0) means
1401 seeking at or past EOF.
1403 - we possibly deviate from the report on the issue of seeking within
1404 the buffer and whether to flush it or not. The report isn't exactly
1408 -- | Computation 'hSeek' @hdl mode i@ sets the position of handle
1409 -- @hdl@ depending on @mode@.
1410 -- The offset @i@ is given in terms of 8-bit bytes.
1412 -- If @hdl@ is block- or line-buffered, then seeking to a position which is not
1413 -- in the current buffer will first cause any items in the output buffer to be
1414 -- written to the device, and then cause the input buffer to be discarded.
1415 -- Some handles may not be seekable (see 'hIsSeekable'), or only support a
1416 -- subset of the possible positioning operations (for instance, it may only
1417 -- be possible to seek to the end of a tape, or to a positive offset from
1418 -- the beginning or current position).
1419 -- It is not possible to set a negative I\/O position, or for
1420 -- a physical file, an I\/O position beyond the current end-of-file.
1422 -- This operation may fail with:
1424 -- * 'isPermissionError' if a system resource limit would be exceeded.
1426 hSeek :: Handle -> SeekMode -> Integer -> IO ()
1427 hSeek handle mode offset =
1428 wantSeekableHandle "hSeek" handle $ \ handle_ -> do
1430 puts ("hSeek " ++ show (mode,offset) ++ "\n")
1432 let ref = haBuffer handle_
1433 buf <- readIORef ref
1439 throwErrnoIfMinus1Retry_ "hSeek"
1440 (c_lseek (haFD handle_) (fromIntegral offset) whence)
1443 whence = case mode of
1444 AbsoluteSeek -> sEEK_SET
1445 RelativeSeek -> sEEK_CUR
1446 SeekFromEnd -> sEEK_END
1448 if bufferIsWritable buf
1449 then do new_buf <- flushWriteBuffer fd (haIsStream handle_) buf
1450 writeIORef ref new_buf
1454 if mode == RelativeSeek && offset >= 0 && offset < fromIntegral (w - r)
1455 then writeIORef ref buf{ bufRPtr = r + fromIntegral offset }
1458 new_buf <- flushReadBuffer (haFD handle_) buf
1459 writeIORef ref new_buf
1463 hTell :: Handle -> IO Integer
1465 wantSeekableHandle "hGetPosn" handle $ \ handle_ -> do
1467 #if defined(mingw32_HOST_OS)
1468 -- urgh, on Windows we have to worry about \n -> \r\n translation,
1469 -- so we can't easily calculate the file position using the
1470 -- current buffer size. Just flush instead.
1473 let fd = haFD handle_
1474 posn <- fromIntegral `liftM`
1475 throwErrnoIfMinus1Retry "hGetPosn"
1476 (c_lseek fd 0 sEEK_CUR)
1478 let ref = haBuffer handle_
1479 buf <- readIORef ref
1482 | bufferIsWritable buf = posn + fromIntegral (bufWPtr buf)
1483 | otherwise = posn - fromIntegral (bufWPtr buf - bufRPtr buf)
1485 puts ("\nhGetPosn: (fd, posn, real_posn) = " ++ show (fd, posn, real_posn) ++ "\n")
1486 puts (" (bufWPtr, bufRPtr) = " ++ show (bufWPtr buf, bufRPtr buf) ++ "\n")
1490 -- -----------------------------------------------------------------------------
1491 -- Handle Properties
1493 -- A number of operations return information about the properties of a
1494 -- handle. Each of these operations returns `True' if the handle has
1495 -- the specified property, and `False' otherwise.
1497 hIsOpen :: Handle -> IO Bool
1499 withHandle_ "hIsOpen" handle $ \ handle_ -> do
1500 case haType handle_ of
1501 ClosedHandle -> return False
1502 SemiClosedHandle -> return False
1505 hIsClosed :: Handle -> IO Bool
1507 withHandle_ "hIsClosed" handle $ \ handle_ -> do
1508 case haType handle_ of
1509 ClosedHandle -> return True
1512 {- not defined, nor exported, but mentioned
1513 here for documentation purposes:
1515 hSemiClosed :: Handle -> IO Bool
1519 return (not (ho || hc))
1522 hIsReadable :: Handle -> IO Bool
1523 hIsReadable (DuplexHandle _ _ _) = return True
1524 hIsReadable handle =
1525 withHandle_ "hIsReadable" handle $ \ handle_ -> do
1526 case haType handle_ of
1527 ClosedHandle -> ioe_closedHandle
1528 SemiClosedHandle -> ioe_closedHandle
1529 htype -> return (isReadableHandleType htype)
1531 hIsWritable :: Handle -> IO Bool
1532 hIsWritable (DuplexHandle _ _ _) = return True
1533 hIsWritable handle =
1534 withHandle_ "hIsWritable" handle $ \ handle_ -> do
1535 case haType handle_ of
1536 ClosedHandle -> ioe_closedHandle
1537 SemiClosedHandle -> ioe_closedHandle
1538 htype -> return (isWritableHandleType htype)
1540 -- | Computation 'hGetBuffering' @hdl@ returns the current buffering mode
1543 hGetBuffering :: Handle -> IO BufferMode
1544 hGetBuffering handle =
1545 withHandle_ "hGetBuffering" handle $ \ handle_ -> do
1546 case haType handle_ of
1547 ClosedHandle -> ioe_closedHandle
1549 -- We're being non-standard here, and allow the buffering
1550 -- of a semi-closed handle to be queried. -- sof 6/98
1551 return (haBufferMode handle_) -- could be stricter..
1553 hIsSeekable :: Handle -> IO Bool
1554 hIsSeekable handle =
1555 withHandle_ "hIsSeekable" handle $ \ handle_ -> do
1556 case haType handle_ of
1557 ClosedHandle -> ioe_closedHandle
1558 SemiClosedHandle -> ioe_closedHandle
1559 AppendHandle -> return False
1560 _ -> do t <- fdType (haFD handle_)
1561 return ((t == RegularFile || t == RawDevice)
1562 && (haIsBin handle_ || tEXT_MODE_SEEK_ALLOWED))
1564 -- -----------------------------------------------------------------------------
1565 -- Changing echo status (Non-standard GHC extensions)
1567 -- | Set the echoing status of a handle connected to a terminal.
1569 hSetEcho :: Handle -> Bool -> IO ()
1570 hSetEcho handle on = do
1571 isT <- hIsTerminalDevice handle
1575 withHandle_ "hSetEcho" handle $ \ handle_ -> do
1576 case haType handle_ of
1577 ClosedHandle -> ioe_closedHandle
1578 _ -> setEcho (haFD handle_) on
1580 -- | Get the echoing status of a handle connected to a terminal.
1582 hGetEcho :: Handle -> IO Bool
1583 hGetEcho handle = do
1584 isT <- hIsTerminalDevice handle
1588 withHandle_ "hGetEcho" handle $ \ handle_ -> do
1589 case haType handle_ of
1590 ClosedHandle -> ioe_closedHandle
1591 _ -> getEcho (haFD handle_)
1593 -- | Is the handle connected to a terminal?
1595 hIsTerminalDevice :: Handle -> IO Bool
1596 hIsTerminalDevice handle = do
1597 withHandle_ "hIsTerminalDevice" handle $ \ handle_ -> do
1598 case haType handle_ of
1599 ClosedHandle -> ioe_closedHandle
1600 _ -> fdIsTTY (haFD handle_)
1602 -- -----------------------------------------------------------------------------
1605 -- | Select binary mode ('True') or text mode ('False') on a open handle.
1606 -- (See also 'openBinaryFile'.)
1608 hSetBinaryMode :: Handle -> Bool -> IO ()
1609 hSetBinaryMode handle bin =
1610 withAllHandles__ "hSetBinaryMode" handle $ \ handle_ ->
1611 do throwErrnoIfMinus1_ "hSetBinaryMode"
1612 (setmode (haFD handle_) bin)
1613 return handle_{haIsBin=bin}
1615 foreign import ccall unsafe "__hscore_setmode"
1616 setmode :: CInt -> Bool -> IO CInt
1618 -- -----------------------------------------------------------------------------
1619 -- Duplicating a Handle
1621 -- | Returns a duplicate of the original handle, with its own buffer.
1622 -- The two Handles will share a file pointer, however. The original
1623 -- handle's buffer is flushed, including discarding any input data,
1624 -- before the handle is duplicated.
1626 hDuplicate :: Handle -> IO Handle
1627 hDuplicate h@(FileHandle path m) = do
1628 new_h_ <- withHandle' "hDuplicate" h m (dupHandle h Nothing)
1629 newFileHandle path (handleFinalizer path) new_h_
1630 hDuplicate h@(DuplexHandle path r w) = do
1631 new_w_ <- withHandle' "hDuplicate" h w (dupHandle h Nothing)
1632 new_w <- newMVar new_w_
1633 new_r_ <- withHandle' "hDuplicate" h r (dupHandle h (Just new_w))
1634 new_r <- newMVar new_r_
1635 addMVarFinalizer new_w (handleFinalizer path new_w)
1636 return (DuplexHandle path new_r new_w)
1638 dupHandle :: Handle -> Maybe (MVar Handle__) -> Handle__
1639 -> IO (Handle__, Handle__)
1640 dupHandle h other_side h_ = do
1641 -- flush the buffer first, so we don't have to copy its contents
1643 new_fd <- case other_side of
1644 Nothing -> throwErrnoIfMinus1 "dupHandle" $ c_dup (haFD h_)
1645 Just r -> withHandle_' "dupHandle" h r (return . haFD)
1646 dupHandle_ other_side h_ new_fd
1648 dupHandleTo other_side hto_ h_ = do
1650 -- Windows' dup2 does not return the new descriptor, unlike Unix
1651 throwErrnoIfMinus1 "dupHandleTo" $
1652 c_dup2 (haFD h_) (haFD hto_)
1653 dupHandle_ other_side h_ (haFD hto_)
1655 dupHandle_ :: Maybe (MVar Handle__) -> Handle__ -> FD
1656 -> IO (Handle__, Handle__)
1657 dupHandle_ other_side h_ new_fd = do
1658 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE (initBufferState (haType h_))
1659 ioref <- newIORef buffer
1660 ioref_buffers <- newIORef BufferListNil
1662 let new_handle_ = h_{ haFD = new_fd,
1664 haBuffers = ioref_buffers,
1665 haOtherSide = other_side }
1666 return (h_, new_handle_)
1668 -- -----------------------------------------------------------------------------
1669 -- Replacing a Handle
1672 Makes the second handle a duplicate of the first handle. The second
1673 handle will be closed first, if it is not already.
1675 This can be used to retarget the standard Handles, for example:
1677 > do h <- openFile "mystdout" WriteMode
1678 > hDuplicateTo h stdout
1681 hDuplicateTo :: Handle -> Handle -> IO ()
1682 hDuplicateTo h1@(FileHandle _ m1) h2@(FileHandle _ m2) = do
1683 withHandle__' "hDuplicateTo" h2 m2 $ \h2_ -> do
1684 _ <- hClose_help h2_
1685 withHandle' "hDuplicateTo" h1 m1 (dupHandleTo Nothing h2_)
1686 hDuplicateTo h1@(DuplexHandle _ r1 w1) h2@(DuplexHandle _ r2 w2) = do
1687 withHandle__' "hDuplicateTo" h2 w2 $ \w2_ -> do
1688 _ <- hClose_help w2_
1689 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo Nothing w2_)
1690 withHandle__' "hDuplicateTo" h2 r2 $ \r2_ -> do
1691 _ <- hClose_help r2_
1692 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo (Just w1) r2_)
1694 ioException (IOError (Just h1) IllegalOperation "hDuplicateTo"
1695 "handles are incompatible" Nothing)
1697 -- ---------------------------------------------------------------------------
1700 -- | 'hShow' is in the 'IO' monad, and gives more comprehensive output
1701 -- than the (pure) instance of 'Show' for 'Handle'.
1703 hShow :: Handle -> IO String
1704 hShow h@(FileHandle path _) = showHandle' path False h
1705 hShow h@(DuplexHandle path _ _) = showHandle' path True h
1707 showHandle' filepath is_duplex h =
1708 withHandle_ "showHandle" h $ \hdl_ ->
1710 showType | is_duplex = showString "duplex (read-write)"
1711 | otherwise = shows (haType hdl_)
1715 showHdl (haType hdl_)
1716 (showString "loc=" . showString filepath . showChar ',' .
1717 showString "type=" . showType . showChar ',' .
1718 showString "binary=" . shows (haIsBin hdl_) . showChar ',' .
1719 showString "buffering=" . showBufMode (unsafePerformIO (readIORef (haBuffer hdl_))) (haBufferMode hdl_) . showString "}" )
1723 showHdl :: HandleType -> ShowS -> ShowS
1726 ClosedHandle -> shows ht . showString "}"
1729 showBufMode :: Buffer -> BufferMode -> ShowS
1730 showBufMode buf bmo =
1732 NoBuffering -> showString "none"
1733 LineBuffering -> showString "line"
1734 BlockBuffering (Just n) -> showString "block " . showParen True (shows n)
1735 BlockBuffering Nothing -> showString "block " . showParen True (shows def)
1740 -- ---------------------------------------------------------------------------
1743 #if defined(DEBUG_DUMP)
1744 puts :: String -> IO ()
1745 puts s = do write_rawBuffer 1 (unsafeCoerce# (packCString# s)) 0 (fromIntegral (length s))
1749 -- -----------------------------------------------------------------------------
1752 throwErrnoIfMinus1RetryOnBlock :: String -> IO CInt -> IO CInt -> IO CInt
1753 throwErrnoIfMinus1RetryOnBlock loc f on_block =
1756 if (res :: CInt) == -1
1760 then throwErrnoIfMinus1RetryOnBlock loc f on_block
1761 else if err == eWOULDBLOCK || err == eAGAIN
1766 -- -----------------------------------------------------------------------------
1767 -- wrappers to platform-specific constants:
1769 foreign import ccall unsafe "__hscore_supportsTextMode"
1770 tEXT_MODE_SEEK_ALLOWED :: Bool
1772 foreign import ccall unsafe "__hscore_bufsiz" dEFAULT_BUFFER_SIZE :: Int
1773 foreign import ccall unsafe "__hscore_seek_cur" sEEK_CUR :: CInt
1774 foreign import ccall unsafe "__hscore_seek_set" sEEK_SET :: CInt
1775 foreign import ccall unsafe "__hscore_seek_end" sEEK_END :: CInt