1 {-# OPTIONS_GHC -XNoImplicitPrelude -#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 )
76 import GHC.Exception ( throw )
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_ `catchAny` \_ -> 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
552 In the threaded RTS we could just make safe calls to read()/write()
553 for file descriptors in blocking mode without worrying about blocking
554 other threads, but the problem with this is that the thread will be
555 uninterruptible while it is blocked in the foreign call. See #2363.
556 So now we always call fdReady() before reading, and if fdReady
557 indicates that there's no data, we call threadWaitRead.
561 readRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
562 readRawBuffer loc fd is_nonblock buf off len
563 | is_nonblock = unsafe_read -- unsafe is ok, it can't block
564 | otherwise = do r <- throwErrnoIfMinus1 loc
565 (unsafe_fdReady (fromIntegral fd) 0 0 0)
568 else do threadWaitRead (fromIntegral fd); read
570 do_read call = throwErrnoIfMinus1RetryMayBlock loc call
571 (threadWaitRead (fromIntegral fd))
572 read = if threaded then safe_read else unsafe_read
573 unsafe_read = do_read (read_rawBuffer fd buf off len)
574 safe_read = do_read (safe_read_rawBuffer fd buf off len)
576 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
577 readRawBufferPtr loc fd is_nonblock buf off len
578 | is_nonblock = unsafe_read -- unsafe is ok, it can't block
579 | otherwise = do r <- throwErrnoIfMinus1 loc
580 (unsafe_fdReady (fromIntegral fd) 0 0 0)
583 else do threadWaitRead (fromIntegral fd); read
585 do_read call = throwErrnoIfMinus1RetryMayBlock loc call
586 (threadWaitRead (fromIntegral fd))
587 read = if threaded then safe_read else unsafe_read
588 unsafe_read = do_read (read_off fd buf off len)
589 safe_read = do_read (safe_read_off fd buf off len)
591 readRawBufferNoBlock :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
592 readRawBufferNoBlock loc fd is_nonblock buf off len
593 | is_nonblock = unsafe_read -- unsafe is ok, it can't block
594 | otherwise = do r <- unsafe_fdReady (fromIntegral fd) 0 0 0
595 if r /= 0 then safe_read
597 -- XXX see note [nonblock]
599 do_read call = throwErrnoIfMinus1RetryOnBlock loc call (return 0)
600 unsafe_read = do_read (read_rawBuffer fd buf off len)
601 safe_read = do_read (safe_read_rawBuffer fd buf off len)
603 readRawBufferPtrNoBlock :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
604 readRawBufferPtrNoBlock loc fd is_nonblock buf off len
605 | is_nonblock = unsafe_read -- unsafe is ok, it can't block
606 | otherwise = do r <- unsafe_fdReady (fromIntegral fd) 0 0 0
607 if r /= 0 then safe_read
609 -- XXX see note [nonblock]
611 do_read call = throwErrnoIfMinus1RetryOnBlock loc call (return 0)
612 unsafe_read = do_read (read_off fd buf off len)
613 safe_read = do_read (safe_read_off fd buf off len)
615 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
616 writeRawBuffer loc fd is_nonblock buf off len
617 | is_nonblock = unsafe_write -- unsafe is ok, it can't block
618 | otherwise = do r <- unsafe_fdReady (fromIntegral fd) 1 0 0
621 else do threadWaitWrite (fromIntegral fd); write
623 do_write call = throwErrnoIfMinus1RetryMayBlock loc call
624 (threadWaitWrite (fromIntegral fd))
625 write = if threaded then safe_write else unsafe_write
626 unsafe_write = do_write (write_rawBuffer fd buf off len)
627 safe_write = do_write (safe_write_rawBuffer (fromIntegral fd) buf off len)
629 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
630 writeRawBufferPtr loc fd is_nonblock buf off len
631 | is_nonblock = unsafe_write -- unsafe is ok, it can't block
632 | otherwise = do r <- unsafe_fdReady (fromIntegral fd) 1 0 0
635 else do threadWaitWrite (fromIntegral fd); write
637 do_write call = throwErrnoIfMinus1RetryMayBlock loc call
638 (threadWaitWrite (fromIntegral fd))
639 write = if threaded then safe_write else unsafe_write
640 unsafe_write = do_write (write_off fd buf off len)
641 safe_write = do_write (safe_write_off (fromIntegral fd) buf off len)
643 foreign import ccall unsafe "__hscore_PrelHandle_read"
644 read_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
646 foreign import ccall unsafe "__hscore_PrelHandle_read"
647 read_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
649 foreign import ccall unsafe "__hscore_PrelHandle_write"
650 write_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
652 foreign import ccall unsafe "__hscore_PrelHandle_write"
653 write_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
655 foreign import ccall unsafe "fdReady"
656 unsafe_fdReady :: CInt -> CInt -> CInt -> CInt -> IO CInt
658 #else /* mingw32_HOST_OS.... */
660 readRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
661 readRawBuffer loc fd is_stream buf off len
662 | threaded = blockingReadRawBuffer loc fd is_stream buf off len
663 | otherwise = asyncReadRawBuffer loc fd is_stream buf off len
665 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
666 readRawBufferPtr loc fd is_stream buf off len
667 | threaded = blockingReadRawBufferPtr loc fd is_stream buf off len
668 | otherwise = asyncReadRawBufferPtr loc fd is_stream buf off len
670 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
671 writeRawBuffer loc fd is_stream buf off len
672 | threaded = blockingWriteRawBuffer loc fd is_stream buf off len
673 | otherwise = asyncWriteRawBuffer loc fd is_stream buf off len
675 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
676 writeRawBufferPtr loc fd is_stream buf off len
677 | threaded = blockingWriteRawBufferPtr loc fd is_stream buf off len
678 | otherwise = asyncWriteRawBufferPtr loc fd is_stream buf off len
680 -- ToDo: we don't have a non-blocking primitve read on Win32
681 readRawBufferNoBlock :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
682 readRawBufferNoBlock = readRawBuffer
684 readRawBufferPtrNoBlock :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
685 readRawBufferPtrNoBlock = readRawBufferPtr
686 -- Async versions of the read/write primitives, for the non-threaded RTS
688 asyncReadRawBuffer loc fd is_stream buf off len = do
689 (l, rc) <- asyncReadBA (fromIntegral fd) (if is_stream then 1 else 0)
690 (fromIntegral len) off buf
693 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
694 else return (fromIntegral l)
696 asyncReadRawBufferPtr loc fd is_stream buf off len = do
697 (l, rc) <- asyncRead (fromIntegral fd) (if is_stream then 1 else 0)
698 (fromIntegral len) (buf `plusPtr` off)
701 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
702 else return (fromIntegral l)
704 asyncWriteRawBuffer loc fd is_stream buf off len = do
705 (l, rc) <- asyncWriteBA (fromIntegral fd) (if is_stream then 1 else 0)
706 (fromIntegral len) off buf
709 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
710 else return (fromIntegral l)
712 asyncWriteRawBufferPtr loc fd is_stream buf off len = do
713 (l, rc) <- asyncWrite (fromIntegral fd) (if is_stream then 1 else 0)
714 (fromIntegral len) (buf `plusPtr` off)
717 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
718 else return (fromIntegral l)
720 -- Blocking versions of the read/write primitives, for the threaded RTS
722 blockingReadRawBuffer loc fd True buf off len =
723 throwErrnoIfMinus1Retry loc $
724 safe_recv_rawBuffer fd buf off len
725 blockingReadRawBuffer loc fd False buf off len =
726 throwErrnoIfMinus1Retry loc $
727 safe_read_rawBuffer fd buf off len
729 blockingReadRawBufferPtr loc fd True buf off len =
730 throwErrnoIfMinus1Retry loc $
731 safe_recv_off fd buf off len
732 blockingReadRawBufferPtr loc fd False buf off len =
733 throwErrnoIfMinus1Retry loc $
734 safe_read_off fd buf off len
736 blockingWriteRawBuffer loc fd True buf off len =
737 throwErrnoIfMinus1Retry loc $
738 safe_send_rawBuffer fd buf off len
739 blockingWriteRawBuffer loc fd False buf off len =
740 throwErrnoIfMinus1Retry loc $
741 safe_write_rawBuffer fd buf off len
743 blockingWriteRawBufferPtr loc fd True buf off len =
744 throwErrnoIfMinus1Retry loc $
745 safe_send_off fd buf off len
746 blockingWriteRawBufferPtr loc fd False buf off len =
747 throwErrnoIfMinus1Retry loc $
748 safe_write_off fd buf off len
750 -- NOTE: "safe" versions of the read/write calls for use by the threaded RTS.
751 -- These calls may block, but that's ok.
753 foreign import ccall safe "__hscore_PrelHandle_recv"
754 safe_recv_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
756 foreign import ccall safe "__hscore_PrelHandle_recv"
757 safe_recv_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
759 foreign import ccall safe "__hscore_PrelHandle_send"
760 safe_send_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
762 foreign import ccall safe "__hscore_PrelHandle_send"
763 safe_send_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
767 foreign import ccall "rtsSupportsBoundThreads" threaded :: Bool
769 foreign import ccall safe "__hscore_PrelHandle_read"
770 safe_read_rawBuffer :: FD -> RawBuffer -> Int -> CInt -> IO CInt
772 foreign import ccall safe "__hscore_PrelHandle_read"
773 safe_read_off :: FD -> Ptr CChar -> Int -> CInt -> IO CInt
775 foreign import ccall safe "__hscore_PrelHandle_write"
776 safe_write_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
778 foreign import ccall safe "__hscore_PrelHandle_write"
779 safe_write_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
781 -- ---------------------------------------------------------------------------
784 -- Three handles are allocated during program initialisation. The first
785 -- two manage input or output from the Haskell program's standard input
786 -- or output channel respectively. The third manages output to the
787 -- standard error channel. These handles are initially open.
793 -- | A handle managing input from the Haskell program's standard input channel.
795 stdin = 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_stdin ReadBuffer
801 mkStdHandle fd_stdin "<stdin>" ReadHandle buf bmode
803 -- | A handle managing output to the Haskell program's standard output channel.
805 stdout = 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]
810 (buf, bmode) <- getBuffer fd_stdout WriteBuffer
811 mkStdHandle fd_stdout "<stdout>" WriteHandle buf bmode
813 -- | A handle managing output to the Haskell program's standard error channel.
815 stderr = unsafePerformIO $ do
816 -- ToDo: acquire lock
817 -- We don't set non-blocking mode on standard handles, because it may
818 -- confuse other applications attached to the same TTY/pipe
819 -- see Note [nonblock]
821 mkStdHandle fd_stderr "<stderr>" WriteHandle buf NoBuffering
823 -- ---------------------------------------------------------------------------
824 -- Opening and Closing Files
826 addFilePathToIOError fun fp (IOError h iot _ str _)
827 = IOError h iot fun str (Just fp)
829 -- | Computation 'openFile' @file mode@ allocates and returns a new, open
830 -- handle to manage the file @file@. It manages input if @mode@
831 -- is 'ReadMode', output if @mode@ is 'WriteMode' or 'AppendMode',
832 -- and both input and output if mode is 'ReadWriteMode'.
834 -- If the file does not exist and it is opened for output, it should be
835 -- created as a new file. If @mode@ is 'WriteMode' and the file
836 -- already exists, then it should be truncated to zero length.
837 -- Some operating systems delete empty files, so there is no guarantee
838 -- that the file will exist following an 'openFile' with @mode@
839 -- 'WriteMode' unless it is subsequently written to successfully.
840 -- The handle is positioned at the end of the file if @mode@ is
841 -- 'AppendMode', and otherwise at the beginning (in which case its
842 -- internal position is 0).
843 -- The initial buffer mode is implementation-dependent.
845 -- This operation may fail with:
847 -- * 'isAlreadyInUseError' if the file is already open and cannot be reopened;
849 -- * 'isDoesNotExistError' if the file does not exist; or
851 -- * 'isPermissionError' if the user does not have permission to open the file.
853 -- Note: if you will be working with files containing binary data, you'll want to
854 -- be using 'openBinaryFile'.
855 openFile :: FilePath -> IOMode -> IO Handle
858 (openFile' fp im dEFAULT_OPEN_IN_BINARY_MODE)
859 (\e -> ioError (addFilePathToIOError "openFile" fp e))
861 -- | Like 'openFile', but open the file in binary mode.
862 -- On Windows, reading a file in text mode (which is the default)
863 -- will translate CRLF to LF, and writing will translate LF to CRLF.
864 -- This is usually what you want with text files. With binary files
865 -- this is undesirable; also, as usual under Microsoft operating systems,
866 -- text mode treats control-Z as EOF. Binary mode turns off all special
867 -- treatment of end-of-line and end-of-file characters.
868 -- (See also 'hSetBinaryMode'.)
870 openBinaryFile :: FilePath -> IOMode -> IO Handle
871 openBinaryFile fp m =
873 (openFile' fp m True)
874 (\e -> ioError (addFilePathToIOError "openBinaryFile" fp e))
876 openFile' filepath mode binary =
877 withCString filepath $ \ f ->
880 oflags1 = case mode of
881 ReadMode -> read_flags
882 #ifdef mingw32_HOST_OS
883 WriteMode -> write_flags .|. o_TRUNC
885 WriteMode -> write_flags
887 ReadWriteMode -> rw_flags
888 AppendMode -> append_flags
894 oflags = oflags1 .|. binary_flags
897 -- the old implementation had a complicated series of three opens,
898 -- which is perhaps because we have to be careful not to open
899 -- directories. However, the man pages I've read say that open()
900 -- always returns EISDIR if the file is a directory and was opened
901 -- for writing, so I think we're ok with a single open() here...
902 fd <- throwErrnoIfMinus1Retry "openFile"
903 (c_open f (fromIntegral oflags) 0o666)
905 stat@(fd_type,_,_) <- fdStat fd
907 h <- fdToHandle_stat fd (Just stat) False filepath mode binary
908 `catchAny` \e -> do c_close fd; throw e
909 -- NB. don't forget to close the FD if fdToHandle' fails, otherwise
911 -- ASSERT: if we just created the file, then fdToHandle' won't fail
912 -- (so we don't need to worry about removing the newly created file
913 -- in the event of an error).
915 #ifndef mingw32_HOST_OS
916 -- we want to truncate() if this is an open in WriteMode, but only
917 -- if the target is a RegularFile. ftruncate() fails on special files
919 if mode == WriteMode && fd_type == RegularFile
920 then throwErrnoIf (/=0) "openFile"
927 std_flags = o_NONBLOCK .|. o_NOCTTY
928 output_flags = std_flags .|. o_CREAT
929 read_flags = std_flags .|. o_RDONLY
930 write_flags = output_flags .|. o_WRONLY
931 rw_flags = output_flags .|. o_RDWR
932 append_flags = write_flags .|. o_APPEND
934 -- ---------------------------------------------------------------------------
937 fdToHandle_stat :: FD
938 -> Maybe (FDType, CDev, CIno)
945 fdToHandle_stat fd mb_stat is_socket filepath mode binary = do
947 #ifdef mingw32_HOST_OS
948 -- On Windows, the is_socket flag indicates that the Handle is a socket
950 -- On Unix, the is_socket flag indicates that the FD can be made non-blocking
951 let non_blocking = is_socket
953 when non_blocking $ setNonBlockingFD fd
954 -- turn on non-blocking mode
957 let (ha_type, write) =
959 ReadMode -> ( ReadHandle, False )
960 WriteMode -> ( WriteHandle, True )
961 ReadWriteMode -> ( ReadWriteHandle, True )
962 AppendMode -> ( AppendHandle, True )
964 -- open() won't tell us if it was a directory if we only opened for
965 -- reading, so check again.
973 ioException (IOError Nothing InappropriateType "openFile"
974 "is a directory" Nothing)
976 -- regular files need to be locked
978 #ifndef mingw32_HOST_OS
979 -- On Windows we use explicit exclusion via sopen() to implement
980 -- this locking (see __hscore_open()); on Unix we have to
981 -- implment it in the RTS.
982 r <- lockFile fd dev ino (fromBool write)
984 ioException (IOError Nothing ResourceBusy "openFile"
985 "file is locked" Nothing)
987 mkFileHandle fd is_socket filepath ha_type binary
990 -- only *Streams* can be DuplexHandles. Other read/write
991 -- Handles must share a buffer.
992 | ReadWriteHandle <- ha_type ->
993 mkDuplexHandle fd is_socket filepath binary
995 mkFileHandle fd is_socket filepath ha_type binary
998 mkFileHandle fd is_socket filepath ha_type binary
1000 -- | Old API kept to avoid breaking clients
1001 fdToHandle' :: FD -> Maybe FDType -> Bool -> FilePath -> IOMode -> Bool
1003 fdToHandle' fd mb_type is_socket filepath mode binary
1005 let mb_stat = case mb_type of
1007 -- fdToHandle_stat will do the stat:
1008 Just RegularFile -> Nothing
1009 -- no stat required for streams etc.:
1010 Just other -> Just (other,0,0)
1011 fdToHandle_stat fd mb_stat is_socket filepath mode binary
1013 fdToHandle :: FD -> IO Handle
1015 mode <- fdGetMode fd
1016 let fd_str = "<file descriptor: " ++ show fd ++ ">"
1017 fdToHandle_stat fd Nothing False fd_str mode True{-bin mode-}
1018 -- NB. the is_socket flag is False, meaning that:
1019 -- on Unix the file descriptor will *not* be put in non-blocking mode
1020 -- on Windows we're guessing this is not a socket (XXX)
1022 #ifndef mingw32_HOST_OS
1023 foreign import ccall unsafe "lockFile"
1024 lockFile :: CInt -> CDev -> CIno -> CInt -> IO CInt
1026 foreign import ccall unsafe "unlockFile"
1027 unlockFile :: CInt -> IO CInt
1030 mkStdHandle :: FD -> FilePath -> HandleType -> IORef Buffer -> BufferMode
1032 mkStdHandle fd filepath ha_type buf bmode = do
1033 spares <- newIORef BufferListNil
1034 newFileHandle filepath (stdHandleFinalizer filepath)
1035 (Handle__ { haFD = fd,
1037 haIsBin = dEFAULT_OPEN_IN_BINARY_MODE,
1038 haIsStream = False, -- means FD is blocking on Unix
1039 haBufferMode = bmode,
1042 haOtherSide = Nothing
1045 mkFileHandle :: FD -> Bool -> FilePath -> HandleType -> Bool -> IO Handle
1046 mkFileHandle fd is_stream filepath ha_type binary = do
1047 (buf, bmode) <- getBuffer fd (initBufferState ha_type)
1049 #ifdef mingw32_HOST_OS
1050 -- On Windows, if this is a read/write handle and we are in text mode,
1051 -- turn off buffering. We don't correctly handle the case of switching
1052 -- from read mode to write mode on a buffered text-mode handle, see bug
1054 bmode <- case ha_type of
1055 ReadWriteHandle | not binary -> return NoBuffering
1056 _other -> return bmode
1059 spares <- newIORef BufferListNil
1060 newFileHandle filepath (handleFinalizer filepath)
1061 (Handle__ { haFD = fd,
1064 haIsStream = is_stream,
1065 haBufferMode = bmode,
1068 haOtherSide = Nothing
1071 mkDuplexHandle :: FD -> Bool -> FilePath -> Bool -> IO Handle
1072 mkDuplexHandle fd is_stream filepath binary = do
1073 (w_buf, w_bmode) <- getBuffer fd WriteBuffer
1074 w_spares <- newIORef BufferListNil
1076 Handle__ { haFD = fd,
1077 haType = WriteHandle,
1079 haIsStream = is_stream,
1080 haBufferMode = w_bmode,
1082 haBuffers = w_spares,
1083 haOtherSide = Nothing
1085 write_side <- newMVar w_handle_
1087 (r_buf, r_bmode) <- getBuffer fd ReadBuffer
1088 r_spares <- newIORef BufferListNil
1090 Handle__ { haFD = fd,
1091 haType = ReadHandle,
1093 haIsStream = is_stream,
1094 haBufferMode = r_bmode,
1096 haBuffers = r_spares,
1097 haOtherSide = Just write_side
1099 read_side <- newMVar r_handle_
1101 addMVarFinalizer write_side (handleFinalizer filepath write_side)
1102 return (DuplexHandle filepath read_side write_side)
1105 initBufferState ReadHandle = ReadBuffer
1106 initBufferState _ = WriteBuffer
1108 -- ---------------------------------------------------------------------------
1111 -- | Computation 'hClose' @hdl@ makes handle @hdl@ closed. Before the
1112 -- computation finishes, if @hdl@ is writable its buffer is flushed as
1114 -- Performing 'hClose' on a handle that has already been closed has no effect;
1115 -- doing so is not an error. All other operations on a closed handle will fail.
1116 -- If 'hClose' fails for any reason, any further operations (apart from
1117 -- 'hClose') on the handle will still fail as if @hdl@ had been successfully
1120 hClose :: Handle -> IO ()
1121 hClose h@(FileHandle _ m) = do
1122 mb_exc <- hClose' h m
1124 Nothing -> return ()
1126 hClose h@(DuplexHandle _ r w) = do
1127 mb_exc1 <- hClose' h w
1128 mb_exc2 <- hClose' h r
1129 case (do mb_exc1; mb_exc2) of
1130 Nothing -> return ()
1133 hClose' h m = withHandle' "hClose" h m $ hClose_help
1135 -- hClose_help is also called by lazyRead (in PrelIO) when EOF is read
1136 -- or an IO error occurs on a lazy stream. The semi-closed Handle is
1137 -- then closed immediately. We have to be careful with DuplexHandles
1138 -- though: we have to leave the closing to the finalizer in that case,
1139 -- because the write side may still be in use.
1140 hClose_help :: Handle__ -> IO (Handle__, Maybe Exception)
1141 hClose_help handle_ =
1142 case haType handle_ of
1143 ClosedHandle -> return (handle_,Nothing)
1144 _ -> do flushWriteBufferOnly handle_ -- interruptible
1145 hClose_handle_ handle_
1147 hClose_handle_ :: Handle__ -> IO (Handle__, Maybe Exception)
1148 hClose_handle_ handle_ = do
1149 let fd = haFD handle_
1151 -- close the file descriptor, but not when this is the read
1152 -- side of a duplex handle.
1153 -- If an exception is raised by the close(), we want to continue
1154 -- to close the handle and release the lock if it has one, then
1155 -- we return the exception to the caller of hClose_help which can
1156 -- raise it if necessary.
1158 case haOtherSide handle_ of
1160 throwErrnoIfMinus1Retry_ "hClose"
1161 #ifdef mingw32_HOST_OS
1162 (closeFd (haIsStream handle_) fd)
1168 `catchException` \e -> return (Just e)
1170 Just _ -> return Nothing
1172 -- free the spare buffers
1173 writeIORef (haBuffers handle_) BufferListNil
1174 writeIORef (haBuffer handle_) noBuffer
1176 #ifndef mingw32_HOST_OS
1181 -- we must set the fd to -1, because the finalizer is going
1182 -- to run eventually and try to close/unlock it.
1183 return (handle_{ haFD = -1,
1184 haType = ClosedHandle
1188 {-# NOINLINE noBuffer #-}
1189 noBuffer = unsafePerformIO $ allocateBuffer 1 ReadBuffer
1191 -----------------------------------------------------------------------------
1192 -- Detecting and changing the size of a file
1194 -- | For a handle @hdl@ which attached to a physical file,
1195 -- 'hFileSize' @hdl@ returns the size of that file in 8-bit bytes.
1197 hFileSize :: Handle -> IO Integer
1199 withHandle_ "hFileSize" handle $ \ handle_ -> do
1200 case haType handle_ of
1201 ClosedHandle -> ioe_closedHandle
1202 SemiClosedHandle -> ioe_closedHandle
1203 _ -> do flushWriteBufferOnly handle_
1204 r <- fdFileSize (haFD handle_)
1207 else ioException (IOError Nothing InappropriateType "hFileSize"
1208 "not a regular file" Nothing)
1211 -- | 'hSetFileSize' @hdl@ @size@ truncates the physical file with handle @hdl@ to @size@ bytes.
1213 hSetFileSize :: Handle -> Integer -> IO ()
1214 hSetFileSize handle size =
1215 withHandle_ "hSetFileSize" handle $ \ handle_ -> do
1216 case haType handle_ of
1217 ClosedHandle -> ioe_closedHandle
1218 SemiClosedHandle -> ioe_closedHandle
1219 _ -> do flushWriteBufferOnly handle_
1220 throwErrnoIf (/=0) "hSetFileSize"
1221 (c_ftruncate (haFD handle_) (fromIntegral size))
1224 -- ---------------------------------------------------------------------------
1225 -- Detecting the End of Input
1227 -- | For a readable handle @hdl@, 'hIsEOF' @hdl@ returns
1228 -- 'True' if no further input can be taken from @hdl@ or for a
1229 -- physical file, if the current I\/O position is equal to the length of
1230 -- the file. Otherwise, it returns 'False'.
1232 -- NOTE: 'hIsEOF' may block, because it is the same as calling
1233 -- 'hLookAhead' and checking for an EOF exception.
1235 hIsEOF :: Handle -> IO Bool
1238 (do hLookAhead handle; return False)
1239 (\e -> if isEOFError e then return True else ioError e)
1241 -- | The computation 'isEOF' is identical to 'hIsEOF',
1242 -- except that it works only on 'stdin'.
1245 isEOF = hIsEOF stdin
1247 -- ---------------------------------------------------------------------------
1250 -- | Computation 'hLookAhead' returns the next character from the handle
1251 -- without removing it from the input buffer, blocking until a character
1254 -- This operation may fail with:
1256 -- * 'isEOFError' if the end of file has been reached.
1258 hLookAhead :: Handle -> IO Char
1259 hLookAhead handle = do
1260 wantReadableHandle "hLookAhead" handle $ \handle_ -> do
1261 let ref = haBuffer handle_
1263 is_line = haBufferMode handle_ == LineBuffering
1264 buf <- readIORef ref
1266 -- fill up the read buffer if necessary
1267 new_buf <- if bufferEmpty buf
1268 then fillReadBuffer fd True (haIsStream handle_) buf
1271 writeIORef ref new_buf
1273 (c,_) <- readCharFromBuffer (bufBuf buf) (bufRPtr buf)
1276 -- ---------------------------------------------------------------------------
1277 -- Buffering Operations
1279 -- Three kinds of buffering are supported: line-buffering,
1280 -- block-buffering or no-buffering. See GHC.IOBase for definition and
1281 -- further explanation of what the type represent.
1283 -- | Computation 'hSetBuffering' @hdl mode@ sets the mode of buffering for
1284 -- handle @hdl@ on subsequent reads and writes.
1286 -- If the buffer mode is changed from 'BlockBuffering' or
1287 -- 'LineBuffering' to 'NoBuffering', then
1289 -- * if @hdl@ is writable, the buffer is flushed as for 'hFlush';
1291 -- * if @hdl@ is not writable, the contents of the buffer is discarded.
1293 -- This operation may fail with:
1295 -- * 'isPermissionError' if the handle has already been used for reading
1296 -- or writing and the implementation does not allow the buffering mode
1299 hSetBuffering :: Handle -> BufferMode -> IO ()
1300 hSetBuffering handle mode =
1301 withAllHandles__ "hSetBuffering" handle $ \ handle_ -> do
1302 case haType handle_ of
1303 ClosedHandle -> ioe_closedHandle
1306 - we flush the old buffer regardless of whether
1307 the new buffer could fit the contents of the old buffer
1309 - allow a handle's buffering to change even if IO has
1310 occurred (ANSI C spec. does not allow this, nor did
1311 the previous implementation of IO.hSetBuffering).
1312 - a non-standard extension is to allow the buffering
1313 of semi-closed handles to change [sof 6/98]
1317 let state = initBufferState (haType handle_)
1320 -- we always have a 1-character read buffer for
1321 -- unbuffered handles: it's needed to
1322 -- support hLookAhead.
1323 NoBuffering -> allocateBuffer 1 ReadBuffer
1324 LineBuffering -> allocateBuffer dEFAULT_BUFFER_SIZE state
1325 BlockBuffering Nothing -> allocateBuffer dEFAULT_BUFFER_SIZE state
1326 BlockBuffering (Just n) | n <= 0 -> ioe_bufsiz n
1327 | otherwise -> allocateBuffer n state
1328 writeIORef (haBuffer handle_) new_buf
1330 -- for input terminals we need to put the terminal into
1331 -- cooked or raw mode depending on the type of buffering.
1332 is_tty <- fdIsTTY (haFD handle_)
1333 when (is_tty && isReadableHandleType (haType handle_)) $
1335 #ifndef mingw32_HOST_OS
1336 -- 'raw' mode under win32 is a bit too specialised (and troublesome
1337 -- for most common uses), so simply disable its use here.
1338 NoBuffering -> setCooked (haFD handle_) False
1340 NoBuffering -> return ()
1342 _ -> setCooked (haFD handle_) True
1344 -- throw away spare buffers, they might be the wrong size
1345 writeIORef (haBuffers handle_) BufferListNil
1347 return (handle_{ haBufferMode = mode })
1349 -- -----------------------------------------------------------------------------
1352 -- | The action 'hFlush' @hdl@ causes any items buffered for output
1353 -- in handle @hdl@ to be sent immediately to the operating system.
1355 -- This operation may fail with:
1357 -- * 'isFullError' if the device is full;
1359 -- * 'isPermissionError' if a system resource limit would be exceeded.
1360 -- It is unspecified whether the characters in the buffer are discarded
1361 -- or retained under these circumstances.
1363 hFlush :: Handle -> IO ()
1365 wantWritableHandle "hFlush" handle $ \ handle_ -> do
1366 buf <- readIORef (haBuffer handle_)
1367 if bufferIsWritable buf && not (bufferEmpty buf)
1368 then do flushed_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
1369 writeIORef (haBuffer handle_) flushed_buf
1373 -- -----------------------------------------------------------------------------
1374 -- Repositioning Handles
1376 data HandlePosn = HandlePosn Handle HandlePosition
1378 instance Eq HandlePosn where
1379 (HandlePosn h1 p1) == (HandlePosn h2 p2) = p1==p2 && h1==h2
1381 instance Show HandlePosn where
1382 showsPrec p (HandlePosn h pos) =
1383 showsPrec p h . showString " at position " . shows pos
1385 -- HandlePosition is the Haskell equivalent of POSIX' off_t.
1386 -- We represent it as an Integer on the Haskell side, but
1387 -- cheat slightly in that hGetPosn calls upon a C helper
1388 -- that reports the position back via (merely) an Int.
1389 type HandlePosition = Integer
1391 -- | Computation 'hGetPosn' @hdl@ returns the current I\/O position of
1392 -- @hdl@ as a value of the abstract type 'HandlePosn'.
1394 hGetPosn :: Handle -> IO HandlePosn
1395 hGetPosn handle = do
1396 posn <- hTell handle
1397 return (HandlePosn handle posn)
1399 -- | If a call to 'hGetPosn' @hdl@ returns a position @p@,
1400 -- then computation 'hSetPosn' @p@ sets the position of @hdl@
1401 -- to the position it held at the time of the call to 'hGetPosn'.
1403 -- This operation may fail with:
1405 -- * 'isPermissionError' if a system resource limit would be exceeded.
1407 hSetPosn :: HandlePosn -> IO ()
1408 hSetPosn (HandlePosn h i) = hSeek h AbsoluteSeek i
1410 -- ---------------------------------------------------------------------------
1413 -- | A mode that determines the effect of 'hSeek' @hdl mode i@, as follows:
1415 = AbsoluteSeek -- ^ the position of @hdl@ is set to @i@.
1416 | RelativeSeek -- ^ the position of @hdl@ is set to offset @i@
1417 -- from the current position.
1418 | SeekFromEnd -- ^ the position of @hdl@ is set to offset @i@
1419 -- from the end of the file.
1420 deriving (Eq, Ord, Ix, Enum, Read, Show)
1423 - when seeking using `SeekFromEnd', positive offsets (>=0) means
1424 seeking at or past EOF.
1426 - we possibly deviate from the report on the issue of seeking within
1427 the buffer and whether to flush it or not. The report isn't exactly
1431 -- | Computation 'hSeek' @hdl mode i@ sets the position of handle
1432 -- @hdl@ depending on @mode@.
1433 -- The offset @i@ is given in terms of 8-bit bytes.
1435 -- If @hdl@ is block- or line-buffered, then seeking to a position which is not
1436 -- in the current buffer will first cause any items in the output buffer to be
1437 -- written to the device, and then cause the input buffer to be discarded.
1438 -- Some handles may not be seekable (see 'hIsSeekable'), or only support a
1439 -- subset of the possible positioning operations (for instance, it may only
1440 -- be possible to seek to the end of a tape, or to a positive offset from
1441 -- the beginning or current position).
1442 -- It is not possible to set a negative I\/O position, or for
1443 -- a physical file, an I\/O position beyond the current end-of-file.
1445 -- This operation may fail with:
1447 -- * 'isPermissionError' if a system resource limit would be exceeded.
1449 hSeek :: Handle -> SeekMode -> Integer -> IO ()
1450 hSeek handle mode offset =
1451 wantSeekableHandle "hSeek" handle $ \ handle_ -> do
1453 puts ("hSeek " ++ show (mode,offset) ++ "\n")
1455 let ref = haBuffer handle_
1456 buf <- readIORef ref
1462 throwErrnoIfMinus1Retry_ "hSeek"
1463 (c_lseek (haFD handle_) (fromIntegral offset) whence)
1466 whence = case mode of
1467 AbsoluteSeek -> sEEK_SET
1468 RelativeSeek -> sEEK_CUR
1469 SeekFromEnd -> sEEK_END
1471 if bufferIsWritable buf
1472 then do new_buf <- flushWriteBuffer fd (haIsStream handle_) buf
1473 writeIORef ref new_buf
1477 if mode == RelativeSeek && offset >= 0 && offset < fromIntegral (w - r)
1478 then writeIORef ref buf{ bufRPtr = r + fromIntegral offset }
1481 new_buf <- flushReadBuffer (haFD handle_) buf
1482 writeIORef ref new_buf
1486 hTell :: Handle -> IO Integer
1488 wantSeekableHandle "hGetPosn" handle $ \ handle_ -> do
1490 #if defined(mingw32_HOST_OS)
1491 -- urgh, on Windows we have to worry about \n -> \r\n translation,
1492 -- so we can't easily calculate the file position using the
1493 -- current buffer size. Just flush instead.
1496 let fd = haFD handle_
1497 posn <- fromIntegral `liftM`
1498 throwErrnoIfMinus1Retry "hGetPosn"
1499 (c_lseek fd 0 sEEK_CUR)
1501 let ref = haBuffer handle_
1502 buf <- readIORef ref
1505 | bufferIsWritable buf = posn + fromIntegral (bufWPtr buf)
1506 | otherwise = posn - fromIntegral (bufWPtr buf - bufRPtr buf)
1508 puts ("\nhGetPosn: (fd, posn, real_posn) = " ++ show (fd, posn, real_posn) ++ "\n")
1509 puts (" (bufWPtr, bufRPtr) = " ++ show (bufWPtr buf, bufRPtr buf) ++ "\n")
1513 -- -----------------------------------------------------------------------------
1514 -- Handle Properties
1516 -- A number of operations return information about the properties of a
1517 -- handle. Each of these operations returns `True' if the handle has
1518 -- the specified property, and `False' otherwise.
1520 hIsOpen :: Handle -> IO Bool
1522 withHandle_ "hIsOpen" handle $ \ handle_ -> do
1523 case haType handle_ of
1524 ClosedHandle -> return False
1525 SemiClosedHandle -> return False
1528 hIsClosed :: Handle -> IO Bool
1530 withHandle_ "hIsClosed" handle $ \ handle_ -> do
1531 case haType handle_ of
1532 ClosedHandle -> return True
1535 {- not defined, nor exported, but mentioned
1536 here for documentation purposes:
1538 hSemiClosed :: Handle -> IO Bool
1542 return (not (ho || hc))
1545 hIsReadable :: Handle -> IO Bool
1546 hIsReadable (DuplexHandle _ _ _) = return True
1547 hIsReadable handle =
1548 withHandle_ "hIsReadable" handle $ \ handle_ -> do
1549 case haType handle_ of
1550 ClosedHandle -> ioe_closedHandle
1551 SemiClosedHandle -> ioe_closedHandle
1552 htype -> return (isReadableHandleType htype)
1554 hIsWritable :: Handle -> IO Bool
1555 hIsWritable (DuplexHandle _ _ _) = return True
1556 hIsWritable handle =
1557 withHandle_ "hIsWritable" handle $ \ handle_ -> do
1558 case haType handle_ of
1559 ClosedHandle -> ioe_closedHandle
1560 SemiClosedHandle -> ioe_closedHandle
1561 htype -> return (isWritableHandleType htype)
1563 -- | Computation 'hGetBuffering' @hdl@ returns the current buffering mode
1566 hGetBuffering :: Handle -> IO BufferMode
1567 hGetBuffering handle =
1568 withHandle_ "hGetBuffering" handle $ \ handle_ -> do
1569 case haType handle_ of
1570 ClosedHandle -> ioe_closedHandle
1572 -- We're being non-standard here, and allow the buffering
1573 -- of a semi-closed handle to be queried. -- sof 6/98
1574 return (haBufferMode handle_) -- could be stricter..
1576 hIsSeekable :: Handle -> IO Bool
1577 hIsSeekable handle =
1578 withHandle_ "hIsSeekable" handle $ \ handle_ -> do
1579 case haType handle_ of
1580 ClosedHandle -> ioe_closedHandle
1581 SemiClosedHandle -> ioe_closedHandle
1582 AppendHandle -> return False
1583 _ -> do t <- fdType (haFD handle_)
1584 return ((t == RegularFile || t == RawDevice)
1585 && (haIsBin handle_ || tEXT_MODE_SEEK_ALLOWED))
1587 -- -----------------------------------------------------------------------------
1588 -- Changing echo status (Non-standard GHC extensions)
1590 -- | Set the echoing status of a handle connected to a terminal.
1592 hSetEcho :: Handle -> Bool -> IO ()
1593 hSetEcho handle on = do
1594 isT <- hIsTerminalDevice handle
1598 withHandle_ "hSetEcho" handle $ \ handle_ -> do
1599 case haType handle_ of
1600 ClosedHandle -> ioe_closedHandle
1601 _ -> setEcho (haFD handle_) on
1603 -- | Get the echoing status of a handle connected to a terminal.
1605 hGetEcho :: Handle -> IO Bool
1606 hGetEcho handle = do
1607 isT <- hIsTerminalDevice handle
1611 withHandle_ "hGetEcho" handle $ \ handle_ -> do
1612 case haType handle_ of
1613 ClosedHandle -> ioe_closedHandle
1614 _ -> getEcho (haFD handle_)
1616 -- | Is the handle connected to a terminal?
1618 hIsTerminalDevice :: Handle -> IO Bool
1619 hIsTerminalDevice handle = do
1620 withHandle_ "hIsTerminalDevice" handle $ \ handle_ -> do
1621 case haType handle_ of
1622 ClosedHandle -> ioe_closedHandle
1623 _ -> fdIsTTY (haFD handle_)
1625 -- -----------------------------------------------------------------------------
1628 -- | Select binary mode ('True') or text mode ('False') on a open handle.
1629 -- (See also 'openBinaryFile'.)
1631 hSetBinaryMode :: Handle -> Bool -> IO ()
1632 hSetBinaryMode handle bin =
1633 withAllHandles__ "hSetBinaryMode" handle $ \ handle_ ->
1634 do throwErrnoIfMinus1_ "hSetBinaryMode"
1635 (setmode (haFD handle_) bin)
1636 return handle_{haIsBin=bin}
1638 foreign import ccall unsafe "__hscore_setmode"
1639 setmode :: CInt -> Bool -> IO CInt
1641 -- -----------------------------------------------------------------------------
1642 -- Duplicating a Handle
1644 -- | Returns a duplicate of the original handle, with its own buffer.
1645 -- The two Handles will share a file pointer, however. The original
1646 -- handle's buffer is flushed, including discarding any input data,
1647 -- before the handle is duplicated.
1649 hDuplicate :: Handle -> IO Handle
1650 hDuplicate h@(FileHandle path m) = do
1651 new_h_ <- withHandle' "hDuplicate" h m (dupHandle h Nothing)
1652 newFileHandle path (handleFinalizer path) new_h_
1653 hDuplicate h@(DuplexHandle path r w) = do
1654 new_w_ <- withHandle' "hDuplicate" h w (dupHandle h Nothing)
1655 new_w <- newMVar new_w_
1656 new_r_ <- withHandle' "hDuplicate" h r (dupHandle h (Just new_w))
1657 new_r <- newMVar new_r_
1658 addMVarFinalizer new_w (handleFinalizer path new_w)
1659 return (DuplexHandle path new_r new_w)
1661 dupHandle :: Handle -> Maybe (MVar Handle__) -> Handle__
1662 -> IO (Handle__, Handle__)
1663 dupHandle h other_side h_ = do
1664 -- flush the buffer first, so we don't have to copy its contents
1666 new_fd <- case other_side of
1667 Nothing -> throwErrnoIfMinus1 "dupHandle" $ c_dup (haFD h_)
1668 Just r -> withHandle_' "dupHandle" h r (return . haFD)
1669 dupHandle_ other_side h_ new_fd
1671 dupHandleTo other_side hto_ h_ = do
1673 -- Windows' dup2 does not return the new descriptor, unlike Unix
1674 throwErrnoIfMinus1 "dupHandleTo" $
1675 c_dup2 (haFD h_) (haFD hto_)
1676 dupHandle_ other_side h_ (haFD hto_)
1678 dupHandle_ :: Maybe (MVar Handle__) -> Handle__ -> FD
1679 -> IO (Handle__, Handle__)
1680 dupHandle_ other_side h_ new_fd = do
1681 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE (initBufferState (haType h_))
1682 ioref <- newIORef buffer
1683 ioref_buffers <- newIORef BufferListNil
1685 let new_handle_ = h_{ haFD = new_fd,
1687 haBuffers = ioref_buffers,
1688 haOtherSide = other_side }
1689 return (h_, new_handle_)
1691 -- -----------------------------------------------------------------------------
1692 -- Replacing a Handle
1695 Makes the second handle a duplicate of the first handle. The second
1696 handle will be closed first, if it is not already.
1698 This can be used to retarget the standard Handles, for example:
1700 > do h <- openFile "mystdout" WriteMode
1701 > hDuplicateTo h stdout
1704 hDuplicateTo :: Handle -> Handle -> IO ()
1705 hDuplicateTo h1@(FileHandle _ m1) h2@(FileHandle _ m2) = do
1706 withHandle__' "hDuplicateTo" h2 m2 $ \h2_ -> do
1707 _ <- hClose_help h2_
1708 withHandle' "hDuplicateTo" h1 m1 (dupHandleTo Nothing h2_)
1709 hDuplicateTo h1@(DuplexHandle _ r1 w1) h2@(DuplexHandle _ r2 w2) = do
1710 withHandle__' "hDuplicateTo" h2 w2 $ \w2_ -> do
1711 _ <- hClose_help w2_
1712 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo Nothing w2_)
1713 withHandle__' "hDuplicateTo" h2 r2 $ \r2_ -> do
1714 _ <- hClose_help r2_
1715 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo (Just w1) r2_)
1717 ioException (IOError (Just h1) IllegalOperation "hDuplicateTo"
1718 "handles are incompatible" Nothing)
1720 -- ---------------------------------------------------------------------------
1723 -- | 'hShow' is in the 'IO' monad, and gives more comprehensive output
1724 -- than the (pure) instance of 'Show' for 'Handle'.
1726 hShow :: Handle -> IO String
1727 hShow h@(FileHandle path _) = showHandle' path False h
1728 hShow h@(DuplexHandle path _ _) = showHandle' path True h
1730 showHandle' filepath is_duplex h =
1731 withHandle_ "showHandle" h $ \hdl_ ->
1733 showType | is_duplex = showString "duplex (read-write)"
1734 | otherwise = shows (haType hdl_)
1738 showHdl (haType hdl_)
1739 (showString "loc=" . showString filepath . showChar ',' .
1740 showString "type=" . showType . showChar ',' .
1741 showString "binary=" . shows (haIsBin hdl_) . showChar ',' .
1742 showString "buffering=" . showBufMode (unsafePerformIO (readIORef (haBuffer hdl_))) (haBufferMode hdl_) . showString "}" )
1746 showHdl :: HandleType -> ShowS -> ShowS
1749 ClosedHandle -> shows ht . showString "}"
1752 showBufMode :: Buffer -> BufferMode -> ShowS
1753 showBufMode buf bmo =
1755 NoBuffering -> showString "none"
1756 LineBuffering -> showString "line"
1757 BlockBuffering (Just n) -> showString "block " . showParen True (shows n)
1758 BlockBuffering Nothing -> showString "block " . showParen True (shows def)
1763 -- ---------------------------------------------------------------------------
1766 #if defined(DEBUG_DUMP)
1767 puts :: String -> IO ()
1768 puts s = do write_rawBuffer 1 (unsafeCoerce# (packCString# s)) 0 (fromIntegral (length s))
1772 -- -----------------------------------------------------------------------------
1775 throwErrnoIfMinus1RetryOnBlock :: String -> IO CInt -> IO CInt -> IO CInt
1776 throwErrnoIfMinus1RetryOnBlock loc f on_block =
1779 if (res :: CInt) == -1
1783 then throwErrnoIfMinus1RetryOnBlock loc f on_block
1784 else if err == eWOULDBLOCK || err == eAGAIN
1789 -- -----------------------------------------------------------------------------
1790 -- wrappers to platform-specific constants:
1792 foreign import ccall unsafe "__hscore_supportsTextMode"
1793 tEXT_MODE_SEEK_ALLOWED :: Bool
1795 foreign import ccall unsafe "__hscore_bufsiz" dEFAULT_BUFFER_SIZE :: Int
1796 foreign import ccall unsafe "__hscore_seek_cur" sEEK_CUR :: CInt
1797 foreign import ccall unsafe "__hscore_seek_set" sEEK_SET :: CInt
1798 foreign import ccall unsafe "__hscore_seek_end" sEEK_END :: CInt