1 {-# OPTIONS_GHC -fno-implicit-prelude -#include "HsBase.h" #-}
6 -----------------------------------------------------------------------------
9 -- Copyright : (c) The University of Glasgow, 1994-2001
10 -- License : see libraries/base/LICENSE
12 -- Maintainer : libraries@haskell.org
13 -- Stability : internal
14 -- Portability : non-portable
16 -- This module defines the basic operations on I\/O \"handles\".
18 -----------------------------------------------------------------------------
22 withHandle, withHandle', withHandle_,
23 wantWritableHandle, wantReadableHandle, wantSeekableHandle,
25 newEmptyBuffer, allocateBuffer, readCharFromBuffer, writeCharIntoBuffer,
26 flushWriteBufferOnly, flushWriteBuffer, flushReadBuffer,
27 fillReadBuffer, fillReadBufferWithoutBlocking,
28 readRawBuffer, readRawBufferPtr,
29 writeRawBuffer, writeRawBufferPtr,
31 #ifndef mingw32_HOST_OS
35 ioe_closedHandle, ioe_EOF, ioe_notReadable, ioe_notWritable,
37 stdin, stdout, stderr,
38 IOMode(..), openFile, openBinaryFile, fdToHandle_stat, fdToHandle, fdToHandle',
39 hFileSize, hSetFileSize, hIsEOF, isEOF, hLookAhead, hSetBuffering, hSetBinaryMode,
40 hFlush, hDuplicate, hDuplicateTo,
44 HandlePosition, HandlePosn(..), hGetPosn, hSetPosn,
45 SeekMode(..), hSeek, hTell,
47 hIsOpen, hIsClosed, hIsReadable, hIsWritable, hGetBuffering, hIsSeekable,
48 hSetEcho, hGetEcho, hIsTerminalDevice,
63 import System.IO.Error
64 import System.Posix.Internals
65 import System.Posix.Types
71 import GHC.Read ( Read )
76 import GHC.Num ( Integer(..), Num(..) )
78 import GHC.Real ( toInteger )
79 #if defined(DEBUG_DUMP)
85 -- -----------------------------------------------------------------------------
88 -- hWaitForInput blocks (should use a timeout)
90 -- unbuffered hGetLine is a bit dodgy
92 -- hSetBuffering: can't change buffering on a stream,
93 -- when the read buffer is non-empty? (no way to flush the buffer)
95 -- ---------------------------------------------------------------------------
96 -- Are files opened by default in text or binary mode, if the user doesn't
99 dEFAULT_OPEN_IN_BINARY_MODE = False :: Bool
101 -- ---------------------------------------------------------------------------
102 -- Creating a new handle
104 newFileHandle :: FilePath -> (MVar Handle__ -> IO ()) -> Handle__ -> IO Handle
105 newFileHandle filepath finalizer hc = do
107 addMVarFinalizer m (finalizer m)
108 return (FileHandle filepath m)
110 -- ---------------------------------------------------------------------------
111 -- Working with Handles
114 In the concurrent world, handles are locked during use. This is done
115 by wrapping an MVar around the handle which acts as a mutex over
116 operations on the handle.
118 To avoid races, we use the following bracketing operations. The idea
119 is to obtain the lock, do some operation and replace the lock again,
120 whether the operation succeeded or failed. We also want to handle the
121 case where the thread receives an exception while processing the IO
122 operation: in these cases we also want to relinquish the lock.
124 There are three versions of @withHandle@: corresponding to the three
125 possible combinations of:
127 - the operation may side-effect the handle
128 - the operation may return a result
130 If the operation generates an error or an exception is raised, the
131 original handle is always replaced [ this is the case at the moment,
132 but we might want to revisit this in the future --SDM ].
135 {-# INLINE withHandle #-}
136 withHandle :: String -> Handle -> (Handle__ -> IO (Handle__,a)) -> IO a
137 withHandle fun h@(FileHandle _ m) act = withHandle' fun h m act
138 withHandle fun h@(DuplexHandle _ m _) act = withHandle' fun h m act
140 withHandle' :: String -> Handle -> MVar Handle__
141 -> (Handle__ -> IO (Handle__,a)) -> IO a
142 withHandle' fun h m act =
145 checkBufferInvariants h_
146 (h',v) <- catchException (act h_)
147 (\ err -> putMVar m h_ >>
149 IOException ex -> ioError (augmentIOError ex fun h)
151 checkBufferInvariants h'
155 {-# INLINE withHandle_ #-}
156 withHandle_ :: String -> Handle -> (Handle__ -> IO a) -> IO a
157 withHandle_ fun h@(FileHandle _ m) act = withHandle_' fun h m act
158 withHandle_ fun h@(DuplexHandle _ m _) act = withHandle_' fun h m act
160 withHandle_' :: String -> Handle -> MVar Handle__ -> (Handle__ -> IO a) -> IO a
161 withHandle_' fun h m act =
164 checkBufferInvariants h_
165 v <- catchException (act h_)
166 (\ err -> putMVar m h_ >>
168 IOException ex -> ioError (augmentIOError ex fun h)
170 checkBufferInvariants h_
174 withAllHandles__ :: String -> Handle -> (Handle__ -> IO Handle__) -> IO ()
175 withAllHandles__ fun h@(FileHandle _ m) act = withHandle__' fun h m act
176 withAllHandles__ fun h@(DuplexHandle _ r w) act = do
177 withHandle__' fun h r act
178 withHandle__' fun h w act
180 withHandle__' fun h m act =
183 checkBufferInvariants h_
184 h' <- catchException (act h_)
185 (\ err -> putMVar m h_ >>
187 IOException ex -> ioError (augmentIOError ex fun h)
189 checkBufferInvariants h'
193 augmentIOError (IOError _ iot _ str fp) fun h
194 = IOError (Just h) iot fun str filepath
197 | otherwise = case h of
198 FileHandle fp _ -> Just fp
199 DuplexHandle fp _ _ -> Just fp
201 -- ---------------------------------------------------------------------------
202 -- Wrapper for write operations.
204 wantWritableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
205 wantWritableHandle fun h@(FileHandle _ m) act
206 = wantWritableHandle' fun h m act
207 wantWritableHandle fun h@(DuplexHandle _ _ m) act
208 = wantWritableHandle' fun h m act
209 -- ToDo: in the Duplex case, we don't need to checkWritableHandle
212 :: String -> Handle -> MVar Handle__
213 -> (Handle__ -> IO a) -> IO a
214 wantWritableHandle' fun h m act
215 = withHandle_' fun h m (checkWritableHandle act)
217 checkWritableHandle act handle_
218 = case haType handle_ of
219 ClosedHandle -> ioe_closedHandle
220 SemiClosedHandle -> ioe_closedHandle
221 ReadHandle -> ioe_notWritable
222 ReadWriteHandle -> do
223 let ref = haBuffer handle_
226 if not (bufferIsWritable buf)
227 then do b <- flushReadBuffer (haFD handle_) buf
228 return b{ bufState=WriteBuffer }
230 writeIORef ref new_buf
232 _other -> act handle_
234 -- ---------------------------------------------------------------------------
235 -- Wrapper for read operations.
237 wantReadableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
238 wantReadableHandle fun h@(FileHandle _ m) act
239 = wantReadableHandle' fun h m act
240 wantReadableHandle fun h@(DuplexHandle _ m _) act
241 = wantReadableHandle' fun h m act
242 -- ToDo: in the Duplex case, we don't need to checkReadableHandle
245 :: String -> Handle -> MVar Handle__
246 -> (Handle__ -> IO a) -> IO a
247 wantReadableHandle' fun h m act
248 = withHandle_' fun h m (checkReadableHandle act)
250 checkReadableHandle act handle_ =
251 case haType handle_ of
252 ClosedHandle -> ioe_closedHandle
253 SemiClosedHandle -> ioe_closedHandle
254 AppendHandle -> ioe_notReadable
255 WriteHandle -> ioe_notReadable
256 ReadWriteHandle -> do
257 let ref = haBuffer handle_
259 when (bufferIsWritable buf) $ do
260 new_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
261 writeIORef ref new_buf{ bufState=ReadBuffer }
263 _other -> act handle_
265 -- ---------------------------------------------------------------------------
266 -- Wrapper for seek operations.
268 wantSeekableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
269 wantSeekableHandle fun h@(DuplexHandle _ _ _) _act =
270 ioException (IOError (Just h) IllegalOperation fun
271 "handle is not seekable" Nothing)
272 wantSeekableHandle fun h@(FileHandle _ m) act =
273 withHandle_' fun h m (checkSeekableHandle act)
275 checkSeekableHandle act handle_ =
276 case haType handle_ of
277 ClosedHandle -> ioe_closedHandle
278 SemiClosedHandle -> ioe_closedHandle
279 AppendHandle -> ioe_notSeekable
280 _ | haIsBin handle_ || tEXT_MODE_SEEK_ALLOWED -> act handle_
281 | otherwise -> ioe_notSeekable_notBin
283 -- -----------------------------------------------------------------------------
286 ioe_closedHandle, ioe_EOF,
287 ioe_notReadable, ioe_notWritable,
288 ioe_notSeekable, ioe_notSeekable_notBin :: IO a
290 ioe_closedHandle = ioException
291 (IOError Nothing IllegalOperation ""
292 "handle is closed" Nothing)
293 ioe_EOF = ioException
294 (IOError Nothing EOF "" "" Nothing)
295 ioe_notReadable = ioException
296 (IOError Nothing IllegalOperation ""
297 "handle is not open for reading" Nothing)
298 ioe_notWritable = ioException
299 (IOError Nothing IllegalOperation ""
300 "handle is not open for writing" Nothing)
301 ioe_notSeekable = ioException
302 (IOError Nothing IllegalOperation ""
303 "handle is not seekable" Nothing)
304 ioe_notSeekable_notBin = ioException
305 (IOError Nothing IllegalOperation ""
306 "seek operations on text-mode handles are not allowed on this platform"
309 ioe_finalizedHandle fp = throw (IOException
310 (IOError Nothing IllegalOperation ""
311 "handle is finalized" (Just fp)))
313 ioe_bufsiz :: Int -> IO a
314 ioe_bufsiz n = ioException
315 (IOError Nothing InvalidArgument "hSetBuffering"
316 ("illegal buffer size " ++ showsPrec 9 n []) Nothing)
317 -- 9 => should be parens'ified.
319 -- -----------------------------------------------------------------------------
322 -- For a duplex handle, we arrange that the read side points to the write side
323 -- (and hence keeps it alive if the read side is alive). This is done by
324 -- having the haOtherSide field of the read side point to the read side.
325 -- The finalizer is then placed on the write side, and the handle only gets
326 -- finalized once, when both sides are no longer required.
328 -- NOTE about finalized handles: It's possible that a handle can be
329 -- finalized and then we try to use it later, for example if the
330 -- handle is referenced from another finalizer, or from a thread that
331 -- has become unreferenced and then resurrected (arguably in the
332 -- latter case we shouldn't finalize the Handle...). Anyway,
333 -- we try to emit a helpful message which is better than nothing.
335 stdHandleFinalizer :: FilePath -> MVar Handle__ -> IO ()
336 stdHandleFinalizer fp m = do
338 flushWriteBufferOnly h_
339 putMVar m (ioe_finalizedHandle fp)
341 handleFinalizer :: FilePath -> MVar Handle__ -> IO ()
342 handleFinalizer fp m = do
343 handle_ <- takeMVar m
344 case haType handle_ of
345 ClosedHandle -> return ()
346 _ -> do flushWriteBufferOnly handle_ `catchException` \_ -> return ()
347 -- ignore errors and async exceptions, and close the
348 -- descriptor anyway...
349 hClose_handle_ handle_
351 putMVar m (ioe_finalizedHandle fp)
353 -- ---------------------------------------------------------------------------
354 -- Grimy buffer operations
357 checkBufferInvariants h_ = do
358 let ref = haBuffer h_
359 Buffer{ bufWPtr=w, bufRPtr=r, bufSize=size, bufState=state } <- readIORef ref
364 && ( r /= w || (r == 0 && w == 0) )
365 && ( state /= WriteBuffer || r == 0 )
366 && ( state /= WriteBuffer || w < size ) -- write buffer is never full
368 then error "buffer invariant violation"
371 checkBufferInvariants h_ = return ()
374 newEmptyBuffer :: RawBuffer -> BufferState -> Int -> Buffer
375 newEmptyBuffer b state size
376 = Buffer{ bufBuf=b, bufRPtr=0, bufWPtr=0, bufSize=size, bufState=state }
378 allocateBuffer :: Int -> BufferState -> IO Buffer
379 allocateBuffer sz@(I# size) state = IO $ \s ->
380 -- We sometimes need to pass the address of this buffer to
381 -- a "safe" foreign call, hence it must be immovable.
382 case newPinnedByteArray# size s of { (# s, b #) ->
383 (# s, newEmptyBuffer b state sz #) }
385 writeCharIntoBuffer :: RawBuffer -> Int -> Char -> IO Int
386 writeCharIntoBuffer slab (I# off) (C# c)
387 = IO $ \s -> case writeCharArray# slab off c s of
388 s -> (# s, I# (off +# 1#) #)
390 readCharFromBuffer :: RawBuffer -> Int -> IO (Char, Int)
391 readCharFromBuffer slab (I# off)
392 = IO $ \s -> case readCharArray# slab off s of
393 (# s, c #) -> (# s, (C# c, I# (off +# 1#)) #)
395 getBuffer :: FD -> BufferState -> IO (IORef Buffer, BufferMode)
396 getBuffer fd state = do
397 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE state
398 ioref <- newIORef buffer
402 | is_tty = LineBuffering
403 | otherwise = BlockBuffering Nothing
405 return (ioref, buffer_mode)
407 mkUnBuffer :: IO (IORef Buffer)
409 buffer <- allocateBuffer 1 ReadBuffer
412 -- flushWriteBufferOnly flushes the buffer iff it contains pending write data.
413 flushWriteBufferOnly :: Handle__ -> IO ()
414 flushWriteBufferOnly h_ = do
418 new_buf <- if bufferIsWritable buf
419 then flushWriteBuffer fd (haIsStream h_) buf
421 writeIORef ref new_buf
423 -- flushBuffer syncs the file with the buffer, including moving the
424 -- file pointer backwards in the case of a read buffer.
425 flushBuffer :: Handle__ -> IO ()
427 let ref = haBuffer h_
432 ReadBuffer -> flushReadBuffer (haFD h_) buf
433 WriteBuffer -> flushWriteBuffer (haFD h_) (haIsStream h_) buf
435 writeIORef ref flushed_buf
437 -- When flushing a read buffer, we seek backwards by the number of
438 -- characters in the buffer. The file descriptor must therefore be
439 -- seekable: attempting to flush the read buffer on an unseekable
440 -- handle is not allowed.
442 flushReadBuffer :: FD -> Buffer -> IO Buffer
443 flushReadBuffer fd buf
444 | bufferEmpty buf = return buf
446 let off = negate (bufWPtr buf - bufRPtr buf)
448 puts ("flushReadBuffer: new file offset = " ++ show off ++ "\n")
450 throwErrnoIfMinus1Retry "flushReadBuffer"
451 (c_lseek fd (fromIntegral off) sEEK_CUR)
452 return buf{ bufWPtr=0, bufRPtr=0 }
454 flushWriteBuffer :: FD -> Bool -> Buffer -> IO Buffer
455 flushWriteBuffer fd is_stream buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w } =
456 seq fd $ do -- strictness hack
459 puts ("flushWriteBuffer, fd=" ++ show fd ++ ", bytes=" ++ show bytes ++ "\n")
462 then return (buf{ bufRPtr=0, bufWPtr=0 })
464 res <- writeRawBuffer "flushWriteBuffer" fd is_stream b
465 (fromIntegral r) (fromIntegral bytes)
466 let res' = fromIntegral res
468 then flushWriteBuffer fd is_stream (buf{ bufRPtr = r + res' })
469 else return buf{ bufRPtr=0, bufWPtr=0 }
471 fillReadBuffer :: FD -> Bool -> Bool -> Buffer -> IO Buffer
472 fillReadBuffer fd is_line is_stream
473 buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w, bufSize=size } =
474 -- buffer better be empty:
475 assert (r == 0 && w == 0) $ do
476 fillReadBufferLoop fd is_line is_stream buf b w size
478 -- For a line buffer, we just get the first chunk of data to arrive,
479 -- and don't wait for the whole buffer to be full (but we *do* wait
480 -- until some data arrives). This isn't really line buffering, but it
481 -- appears to be what GHC has done for a long time, and I suspect it
482 -- is more useful than line buffering in most cases.
484 fillReadBufferLoop fd is_line is_stream buf b w size = do
486 if bytes == 0 -- buffer full?
487 then return buf{ bufRPtr=0, bufWPtr=w }
490 puts ("fillReadBufferLoop: bytes = " ++ show bytes ++ "\n")
492 res <- readRawBuffer "fillReadBuffer" fd is_stream b
493 (fromIntegral w) (fromIntegral bytes)
494 let res' = fromIntegral res
496 puts ("fillReadBufferLoop: res' = " ++ show res' ++ "\n")
501 else return buf{ bufRPtr=0, bufWPtr=w }
502 else if res' < bytes && not is_line
503 then fillReadBufferLoop fd is_line is_stream buf b (w+res') size
504 else return buf{ bufRPtr=0, bufWPtr=w+res' }
507 fillReadBufferWithoutBlocking :: FD -> Bool -> Buffer -> IO Buffer
508 fillReadBufferWithoutBlocking fd is_stream
509 buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w, bufSize=size } =
510 -- buffer better be empty:
511 assert (r == 0 && w == 0) $ do
513 puts ("fillReadBufferLoopNoBlock: bytes = " ++ show size ++ "\n")
515 res <- readRawBufferNoBlock "fillReadBuffer" fd is_stream b
516 0 (fromIntegral size)
517 let res' = fromIntegral res
519 puts ("fillReadBufferLoopNoBlock: res' = " ++ show res' ++ "\n")
521 return buf{ bufRPtr=0, bufWPtr=res' }
523 -- Low level routines for reading/writing to (raw)buffers:
525 #ifndef mingw32_HOST_OS
530 Unix has broken semantics when it comes to non-blocking I/O: you can
531 set the O_NONBLOCK flag on an FD, but it applies to the all other FDs
532 attached to the same underlying file, pipe or TTY; there's no way to
533 have private non-blocking behaviour for an FD. See bug #724.
535 We fix this by only setting O_NONBLOCK on FDs that we create; FDs that
536 come from external sources or are exposed externally are left in
537 blocking mode. This solution has some problems though. We can't
538 completely simulate a non-blocking read without O_NONBLOCK: several
539 cases are wrong here. The cases that are wrong:
541 * reading/writing to a blocking FD in non-threaded mode.
542 In threaded mode, we just make a safe call to read().
543 In non-threaded mode we call select() before attempting to read,
544 but that leaves a small race window where the data can be read
545 from the file descriptor before we issue our blocking read().
546 * readRawBufferNoBlock for a blocking FD
549 readRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
550 readRawBuffer loc fd is_nonblock buf off len
551 | is_nonblock = unsafe_read
552 | threaded = safe_read
553 | otherwise = do r <- throwErrnoIfMinus1 loc
554 (fdReady (fromIntegral fd) 0 0 False)
557 else do threadWaitRead (fromIntegral fd); unsafe_read
559 do_read call = throwErrnoIfMinus1RetryMayBlock loc call
560 (threadWaitRead (fromIntegral fd))
561 unsafe_read = do_read (read_rawBuffer fd buf off len)
562 safe_read = do_read (safe_read_rawBuffer fd buf off len)
564 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
565 readRawBufferPtr loc fd is_nonblock buf off len
566 | is_nonblock = unsafe_read
567 | threaded = safe_read
568 | otherwise = do r <- throwErrnoIfMinus1 loc
569 (fdReady (fromIntegral fd) 0 0 False)
572 else do threadWaitRead (fromIntegral fd); unsafe_read
574 do_read call = throwErrnoIfMinus1RetryMayBlock loc call
575 (threadWaitRead (fromIntegral fd))
576 unsafe_read = do_read (read_off fd buf off len)
577 safe_read = do_read (safe_read_off fd buf off len)
579 readRawBufferNoBlock :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
580 readRawBufferNoBlock loc fd is_nonblock buf off len
581 | is_nonblock = unsafe_read
582 | otherwise = do r <- fdReady (fromIntegral fd) 0 0 False
583 if r /= 0 then safe_read
585 -- XXX see note [nonblock]
587 do_read call = throwErrnoIfMinus1RetryOnBlock loc call (return 0)
588 unsafe_read = do_read (read_rawBuffer fd buf off len)
589 safe_read = do_read (safe_read_rawBuffer fd buf off len)
591 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
592 writeRawBuffer loc fd is_nonblock buf off len
593 | is_nonblock = unsafe_write
594 | threaded = safe_write
595 | otherwise = do r <- fdReady (fromIntegral fd) 1 0 False
598 else do threadWaitWrite (fromIntegral fd); unsafe_write
600 do_write call = throwErrnoIfMinus1RetryMayBlock loc call
601 (threadWaitWrite (fromIntegral fd))
602 unsafe_write = do_write (write_rawBuffer fd buf off len)
603 safe_write = do_write (safe_write_rawBuffer (fromIntegral fd) buf off len)
605 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
606 writeRawBufferPtr loc fd is_nonblock buf off len
607 | is_nonblock = unsafe_write
608 | threaded = safe_write
609 | otherwise = do r <- fdReady (fromIntegral fd) 1 0 False
612 else do threadWaitWrite (fromIntegral fd); unsafe_write
614 do_write call = throwErrnoIfMinus1RetryMayBlock loc call
615 (threadWaitWrite (fromIntegral fd))
616 unsafe_write = do_write (write_off fd buf off len)
617 safe_write = do_write (safe_write_off (fromIntegral fd) buf off len)
619 foreign import ccall unsafe "__hscore_PrelHandle_read"
620 read_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
622 foreign import ccall unsafe "__hscore_PrelHandle_read"
623 read_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
625 foreign import ccall unsafe "__hscore_PrelHandle_write"
626 write_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
628 foreign import ccall unsafe "__hscore_PrelHandle_write"
629 write_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
631 foreign import ccall safe "fdReady"
632 fdReady :: CInt -> CInt -> CInt -> Bool -> IO CInt
634 #else /* mingw32_HOST_OS.... */
636 readRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
637 readRawBuffer loc fd is_stream buf off len
638 | threaded = blockingReadRawBuffer loc fd is_stream buf off len
639 | otherwise = asyncReadRawBuffer loc fd is_stream buf off len
641 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
642 readRawBufferPtr loc fd is_stream buf off len
643 | threaded = blockingReadRawBufferPtr loc fd is_stream buf off len
644 | otherwise = asyncReadRawBufferPtr loc fd is_stream buf off len
646 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
647 writeRawBuffer loc fd is_stream buf off len
648 | threaded = blockingWriteRawBuffer loc fd is_stream buf off len
649 | otherwise = asyncWriteRawBuffer loc fd is_stream buf off len
651 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
652 writeRawBufferPtr loc fd is_stream buf off len
653 | threaded = blockingWriteRawBufferPtr loc fd is_stream buf off len
654 | otherwise = asyncWriteRawBufferPtr loc fd is_stream buf off len
656 -- ToDo: we don't have a non-blocking primitve read on Win32
657 readRawBufferNoBlock :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
658 readRawBufferNoBlock = readRawBuffer
660 -- Async versions of the read/write primitives, for the non-threaded RTS
662 asyncReadRawBuffer loc fd is_stream buf off len = do
663 (l, rc) <- asyncReadBA (fromIntegral fd) (if is_stream then 1 else 0)
664 (fromIntegral len) off buf
667 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
668 else return (fromIntegral l)
670 asyncReadRawBufferPtr loc fd is_stream buf off len = do
671 (l, rc) <- asyncRead (fromIntegral fd) (if is_stream then 1 else 0)
672 (fromIntegral len) (buf `plusPtr` off)
675 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
676 else return (fromIntegral l)
678 asyncWriteRawBuffer loc fd is_stream buf off len = do
679 (l, rc) <- asyncWriteBA (fromIntegral fd) (if is_stream then 1 else 0)
680 (fromIntegral len) off buf
683 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
684 else return (fromIntegral l)
686 asyncWriteRawBufferPtr loc fd is_stream buf off len = do
687 (l, rc) <- asyncWrite (fromIntegral fd) (if is_stream then 1 else 0)
688 (fromIntegral len) (buf `plusPtr` off)
691 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
692 else return (fromIntegral l)
694 -- Blocking versions of the read/write primitives, for the threaded RTS
696 blockingReadRawBuffer loc fd True buf off len =
697 throwErrnoIfMinus1Retry loc $
698 safe_recv_rawBuffer fd buf off len
699 blockingReadRawBuffer loc fd False buf off len =
700 throwErrnoIfMinus1Retry loc $
701 safe_read_rawBuffer fd buf off len
703 blockingReadRawBufferPtr loc fd True buf off len =
704 throwErrnoIfMinus1Retry loc $
705 safe_recv_off fd buf off len
706 blockingReadRawBufferPtr loc fd False buf off len =
707 throwErrnoIfMinus1Retry loc $
708 safe_read_off fd buf off len
710 blockingWriteRawBuffer loc fd True buf off len =
711 throwErrnoIfMinus1Retry loc $
712 safe_send_rawBuffer fd buf off len
713 blockingWriteRawBuffer loc fd False buf off len =
714 throwErrnoIfMinus1Retry loc $
715 safe_write_rawBuffer fd buf off len
717 blockingWriteRawBufferPtr loc fd True buf off len =
718 throwErrnoIfMinus1Retry loc $
719 safe_send_off fd buf off len
720 blockingWriteRawBufferPtr loc fd False buf off len =
721 throwErrnoIfMinus1Retry loc $
722 safe_write_off fd buf off len
724 -- NOTE: "safe" versions of the read/write calls for use by the threaded RTS.
725 -- These calls may block, but that's ok.
727 foreign import ccall safe "__hscore_PrelHandle_recv"
728 safe_recv_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
730 foreign import ccall safe "__hscore_PrelHandle_recv"
731 safe_recv_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
733 foreign import ccall safe "__hscore_PrelHandle_send"
734 safe_send_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
736 foreign import ccall safe "__hscore_PrelHandle_send"
737 safe_send_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
741 foreign import ccall "rtsSupportsBoundThreads" threaded :: Bool
743 foreign import ccall safe "__hscore_PrelHandle_read"
744 safe_read_rawBuffer :: FD -> RawBuffer -> Int -> CInt -> IO CInt
746 foreign import ccall safe "__hscore_PrelHandle_read"
747 safe_read_off :: FD -> Ptr CChar -> Int -> CInt -> IO CInt
749 foreign import ccall safe "__hscore_PrelHandle_write"
750 safe_write_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
752 foreign import ccall safe "__hscore_PrelHandle_write"
753 safe_write_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
755 -- ---------------------------------------------------------------------------
758 -- Three handles are allocated during program initialisation. The first
759 -- two manage input or output from the Haskell program's standard input
760 -- or output channel respectively. The third manages output to the
761 -- standard error channel. These handles are initially open.
767 -- | A handle managing input from the Haskell program's standard input channel.
769 stdin = unsafePerformIO $ do
770 -- ToDo: acquire lock
771 -- We don't set non-blocking mode on standard handles, because it may
772 -- confuse other applications attached to the same TTY/pipe
773 -- see Note [nonblock]
774 (buf, bmode) <- getBuffer fd_stdin ReadBuffer
775 mkStdHandle fd_stdin "<stdin>" ReadHandle buf bmode
777 -- | A handle managing output to the Haskell program's standard output channel.
779 stdout = unsafePerformIO $ do
780 -- ToDo: acquire lock
781 -- We don't set non-blocking mode on standard handles, because it may
782 -- confuse other applications attached to the same TTY/pipe
783 -- see Note [nonblock]
784 (buf, bmode) <- getBuffer fd_stdout WriteBuffer
785 mkStdHandle fd_stdout "<stdout>" WriteHandle buf bmode
787 -- | A handle managing output to the Haskell program's standard error channel.
789 stderr = unsafePerformIO $ do
790 -- ToDo: acquire lock
791 -- We don't set non-blocking mode on standard handles, because it may
792 -- confuse other applications attached to the same TTY/pipe
793 -- see Note [nonblock]
795 mkStdHandle fd_stderr "<stderr>" WriteHandle buf NoBuffering
797 -- ---------------------------------------------------------------------------
798 -- Opening and Closing Files
800 addFilePathToIOError fun fp (IOError h iot _ str _)
801 = IOError h iot fun str (Just fp)
803 -- | Computation 'openFile' @file mode@ allocates and returns a new, open
804 -- handle to manage the file @file@. It manages input if @mode@
805 -- is 'ReadMode', output if @mode@ is 'WriteMode' or 'AppendMode',
806 -- and both input and output if mode is 'ReadWriteMode'.
808 -- If the file does not exist and it is opened for output, it should be
809 -- created as a new file. If @mode@ is 'WriteMode' and the file
810 -- already exists, then it should be truncated to zero length.
811 -- Some operating systems delete empty files, so there is no guarantee
812 -- that the file will exist following an 'openFile' with @mode@
813 -- 'WriteMode' unless it is subsequently written to successfully.
814 -- The handle is positioned at the end of the file if @mode@ is
815 -- 'AppendMode', and otherwise at the beginning (in which case its
816 -- internal position is 0).
817 -- The initial buffer mode is implementation-dependent.
819 -- This operation may fail with:
821 -- * 'isAlreadyInUseError' if the file is already open and cannot be reopened;
823 -- * 'isDoesNotExistError' if the file does not exist; or
825 -- * 'isPermissionError' if the user does not have permission to open the file.
827 -- Note: if you will be working with files containing binary data, you'll want to
828 -- be using 'openBinaryFile'.
829 openFile :: FilePath -> IOMode -> IO Handle
832 (openFile' fp im dEFAULT_OPEN_IN_BINARY_MODE)
833 (\e -> ioError (addFilePathToIOError "openFile" fp e))
835 -- | Like 'openFile', but open the file in binary mode.
836 -- On Windows, reading a file in text mode (which is the default)
837 -- will translate CRLF to LF, and writing will translate LF to CRLF.
838 -- This is usually what you want with text files. With binary files
839 -- this is undesirable; also, as usual under Microsoft operating systems,
840 -- text mode treats control-Z as EOF. Binary mode turns off all special
841 -- treatment of end-of-line and end-of-file characters.
842 -- (See also 'hSetBinaryMode'.)
844 openBinaryFile :: FilePath -> IOMode -> IO Handle
845 openBinaryFile fp m =
847 (openFile' fp m True)
848 (\e -> ioError (addFilePathToIOError "openBinaryFile" fp e))
850 openFile' filepath mode binary =
851 withCString filepath $ \ f ->
854 oflags1 = case mode of
855 ReadMode -> read_flags
856 #ifdef mingw32_HOST_OS
857 WriteMode -> write_flags .|. o_TRUNC
859 WriteMode -> write_flags
861 ReadWriteMode -> rw_flags
862 AppendMode -> append_flags
868 oflags = oflags1 .|. binary_flags
871 -- the old implementation had a complicated series of three opens,
872 -- which is perhaps because we have to be careful not to open
873 -- directories. However, the man pages I've read say that open()
874 -- always returns EISDIR if the file is a directory and was opened
875 -- for writing, so I think we're ok with a single open() here...
876 fd <- throwErrnoIfMinus1Retry "openFile"
877 (c_open f (fromIntegral oflags) 0o666)
879 stat@(fd_type,_,_) <- fdStat fd
881 h <- fdToHandle_stat fd (Just stat) False filepath mode binary
882 `catchException` \e -> do c_close fd; throw e
883 -- NB. don't forget to close the FD if fdToHandle' fails, otherwise
885 -- ASSERT: if we just created the file, then fdToHandle' won't fail
886 -- (so we don't need to worry about removing the newly created file
887 -- in the event of an error).
889 #ifndef mingw32_HOST_OS
890 -- we want to truncate() if this is an open in WriteMode, but only
891 -- if the target is a RegularFile. ftruncate() fails on special files
893 if mode == WriteMode && fd_type == RegularFile
894 then throwErrnoIf (/=0) "openFile"
901 std_flags = o_NONBLOCK .|. o_NOCTTY
902 output_flags = std_flags .|. o_CREAT
903 read_flags = std_flags .|. o_RDONLY
904 write_flags = output_flags .|. o_WRONLY
905 rw_flags = output_flags .|. o_RDWR
906 append_flags = write_flags .|. o_APPEND
908 -- ---------------------------------------------------------------------------
911 fdToHandle_stat :: FD
912 -> Maybe (FDType, CDev, CIno)
919 fdToHandle_stat fd mb_stat is_socket filepath mode binary = do
920 -- turn on non-blocking mode
923 #ifdef mingw32_HOST_OS
924 -- On Windows, the is_stream flag indicates that the Handle is a socket
925 let is_stream = is_socket
927 -- On Unix, the is_stream flag indicates that the FD is non-blocking
931 let (ha_type, write) =
933 ReadMode -> ( ReadHandle, False )
934 WriteMode -> ( WriteHandle, True )
935 ReadWriteMode -> ( ReadWriteHandle, True )
936 AppendMode -> ( AppendHandle, True )
938 -- open() won't tell us if it was a directory if we only opened for
939 -- reading, so check again.
947 ioException (IOError Nothing InappropriateType "openFile"
948 "is a directory" Nothing)
950 -- regular files need to be locked
952 #ifndef mingw32_HOST_OS
953 r <- lockFile fd dev ino (fromBool write)
955 ioException (IOError Nothing ResourceBusy "openFile"
956 "file is locked" Nothing)
958 mkFileHandle fd is_stream filepath ha_type binary
961 -- only *Streams* can be DuplexHandles. Other read/write
962 -- Handles must share a buffer.
963 | ReadWriteHandle <- ha_type ->
964 mkDuplexHandle fd is_stream filepath binary
966 mkFileHandle fd is_stream filepath ha_type binary
969 mkFileHandle fd is_stream filepath ha_type binary
971 -- | Old API kept to avoid breaking clients
972 fdToHandle' :: FD -> Maybe FDType -> Bool -> FilePath -> IOMode -> Bool
974 fdToHandle' fd mb_type is_socket filepath mode binary
976 let mb_stat = case mb_type of
978 -- fdToHandle_stat will do the stat:
979 Just RegularFile -> Nothing
980 -- no stat required for streams etc.:
981 Just other -> Just (other,0,0)
982 fdToHandle_stat fd mb_stat is_socket filepath mode binary
984 fdToHandle :: FD -> IO Handle
987 let fd_str = "<file descriptor: " ++ show fd ++ ">"
988 fdToHandle_stat fd Nothing False{-XXX!-} fd_str mode True{-bin mode-}
991 #ifndef mingw32_HOST_OS
992 foreign import ccall unsafe "lockFile"
993 lockFile :: CInt -> CDev -> CIno -> CInt -> IO CInt
995 foreign import ccall unsafe "unlockFile"
996 unlockFile :: CInt -> IO CInt
999 mkStdHandle :: FD -> FilePath -> HandleType -> IORef Buffer -> BufferMode
1001 mkStdHandle fd filepath ha_type buf bmode = do
1002 spares <- newIORef BufferListNil
1003 newFileHandle filepath (stdHandleFinalizer filepath)
1004 (Handle__ { haFD = fd,
1006 haIsBin = dEFAULT_OPEN_IN_BINARY_MODE,
1007 haIsStream = False, -- means FD is blocking on Unix
1008 haBufferMode = bmode,
1011 haOtherSide = Nothing
1014 mkFileHandle :: FD -> Bool -> FilePath -> HandleType -> Bool -> IO Handle
1015 mkFileHandle fd is_stream filepath ha_type binary = do
1016 (buf, bmode) <- getBuffer fd (initBufferState ha_type)
1018 #ifdef mingw32_HOST_OS
1019 -- On Windows, if this is a read/write handle and we are in text mode,
1020 -- turn off buffering. We don't correctly handle the case of switching
1021 -- from read mode to write mode on a buffered text-mode handle, see bug
1023 bmode <- case ha_type of
1024 ReadWriteHandle | not binary -> return NoBuffering
1025 _other -> return bmode
1028 spares <- newIORef BufferListNil
1029 newFileHandle filepath (handleFinalizer filepath)
1030 (Handle__ { haFD = fd,
1033 haIsStream = is_stream,
1034 haBufferMode = bmode,
1037 haOtherSide = Nothing
1040 mkDuplexHandle :: FD -> Bool -> FilePath -> Bool -> IO Handle
1041 mkDuplexHandle fd is_stream filepath binary = do
1042 (w_buf, w_bmode) <- getBuffer fd WriteBuffer
1043 w_spares <- newIORef BufferListNil
1045 Handle__ { haFD = fd,
1046 haType = WriteHandle,
1048 haIsStream = is_stream,
1049 haBufferMode = w_bmode,
1051 haBuffers = w_spares,
1052 haOtherSide = Nothing
1054 write_side <- newMVar w_handle_
1056 (r_buf, r_bmode) <- getBuffer fd ReadBuffer
1057 r_spares <- newIORef BufferListNil
1059 Handle__ { haFD = fd,
1060 haType = ReadHandle,
1062 haIsStream = is_stream,
1063 haBufferMode = r_bmode,
1065 haBuffers = r_spares,
1066 haOtherSide = Just write_side
1068 read_side <- newMVar r_handle_
1070 addMVarFinalizer write_side (handleFinalizer filepath write_side)
1071 return (DuplexHandle filepath read_side write_side)
1074 initBufferState ReadHandle = ReadBuffer
1075 initBufferState _ = WriteBuffer
1077 -- ---------------------------------------------------------------------------
1080 -- | Computation 'hClose' @hdl@ makes handle @hdl@ closed. Before the
1081 -- computation finishes, if @hdl@ is writable its buffer is flushed as
1083 -- Performing 'hClose' on a handle that has already been closed has no effect;
1084 -- doing so is not an error. All other operations on a closed handle will fail.
1085 -- If 'hClose' fails for any reason, any further operations (apart from
1086 -- 'hClose') on the handle will still fail as if @hdl@ had been successfully
1089 hClose :: Handle -> IO ()
1090 hClose h@(FileHandle _ m) = do
1091 mb_exc <- hClose' h m
1093 Nothing -> return ()
1095 hClose h@(DuplexHandle _ r w) = do
1096 mb_exc1 <- hClose' h w
1097 mb_exc2 <- hClose' h r
1098 case (do mb_exc1; mb_exc2) of
1099 Nothing -> return ()
1102 hClose' h m = withHandle' "hClose" h m $ hClose_help
1104 -- hClose_help is also called by lazyRead (in PrelIO) when EOF is read
1105 -- or an IO error occurs on a lazy stream. The semi-closed Handle is
1106 -- then closed immediately. We have to be careful with DuplexHandles
1107 -- though: we have to leave the closing to the finalizer in that case,
1108 -- because the write side may still be in use.
1109 hClose_help :: Handle__ -> IO (Handle__, Maybe Exception)
1110 hClose_help handle_ =
1111 case haType handle_ of
1112 ClosedHandle -> return (handle_,Nothing)
1113 _ -> do flushWriteBufferOnly handle_ -- interruptible
1114 hClose_handle_ handle_
1116 hClose_handle_ handle_ = do
1117 let fd = haFD handle_
1119 -- close the file descriptor, but not when this is the read
1120 -- side of a duplex handle.
1121 -- If an exception is raised by the close(), we want to continue
1122 -- to close the handle and release the lock if it has one, then
1123 -- we return the exception to the caller of hClose_help which can
1124 -- raise it if necessary.
1126 case haOtherSide handle_ of
1128 throwErrnoIfMinus1Retry_ "hClose"
1129 #ifdef mingw32_HOST_OS
1130 (closeFd (haIsStream handle_) fd)
1136 `catchException` \e -> return (Just e)
1138 Just _ -> return Nothing
1140 -- free the spare buffers
1141 writeIORef (haBuffers handle_) BufferListNil
1142 writeIORef (haBuffer handle_) noBuffer
1144 #ifndef mingw32_HOST_OS
1149 -- we must set the fd to -1, because the finalizer is going
1150 -- to run eventually and try to close/unlock it.
1151 return (handle_{ haFD = -1,
1152 haType = ClosedHandle
1156 {-# NOINLINE noBuffer #-}
1157 noBuffer = unsafePerformIO $ allocateBuffer 1 ReadBuffer
1159 -----------------------------------------------------------------------------
1160 -- Detecting and changing the size of a file
1162 -- | For a handle @hdl@ which attached to a physical file,
1163 -- 'hFileSize' @hdl@ returns the size of that file in 8-bit bytes.
1165 hFileSize :: Handle -> IO Integer
1167 withHandle_ "hFileSize" handle $ \ handle_ -> do
1168 case haType handle_ of
1169 ClosedHandle -> ioe_closedHandle
1170 SemiClosedHandle -> ioe_closedHandle
1171 _ -> do flushWriteBufferOnly handle_
1172 r <- fdFileSize (haFD handle_)
1175 else ioException (IOError Nothing InappropriateType "hFileSize"
1176 "not a regular file" Nothing)
1179 -- | 'hSetFileSize' @hdl@ @size@ truncates the physical file with handle @hdl@ to @size@ bytes.
1181 hSetFileSize :: Handle -> Integer -> IO ()
1182 hSetFileSize handle size =
1183 withHandle_ "hSetFileSize" handle $ \ handle_ -> do
1184 case haType handle_ of
1185 ClosedHandle -> ioe_closedHandle
1186 SemiClosedHandle -> ioe_closedHandle
1187 _ -> do flushWriteBufferOnly handle_
1188 throwErrnoIf (/=0) "hSetFileSize"
1189 (c_ftruncate (haFD handle_) (fromIntegral size))
1192 -- ---------------------------------------------------------------------------
1193 -- Detecting the End of Input
1195 -- | For a readable handle @hdl@, 'hIsEOF' @hdl@ returns
1196 -- 'True' if no further input can be taken from @hdl@ or for a
1197 -- physical file, if the current I\/O position is equal to the length of
1198 -- the file. Otherwise, it returns 'False'.
1200 hIsEOF :: Handle -> IO Bool
1203 (do hLookAhead handle; return False)
1204 (\e -> if isEOFError e then return True else ioError e)
1206 -- | The computation 'isEOF' is identical to 'hIsEOF',
1207 -- except that it works only on 'stdin'.
1210 isEOF = hIsEOF stdin
1212 -- ---------------------------------------------------------------------------
1215 -- | Computation 'hLookAhead' returns the next character from the handle
1216 -- without removing it from the input buffer, blocking until a character
1219 -- This operation may fail with:
1221 -- * 'isEOFError' if the end of file has been reached.
1223 hLookAhead :: Handle -> IO Char
1224 hLookAhead handle = do
1225 wantReadableHandle "hLookAhead" handle $ \handle_ -> do
1226 let ref = haBuffer handle_
1228 is_line = haBufferMode handle_ == LineBuffering
1229 buf <- readIORef ref
1231 -- fill up the read buffer if necessary
1232 new_buf <- if bufferEmpty buf
1233 then fillReadBuffer fd True (haIsStream handle_) buf
1236 writeIORef ref new_buf
1238 (c,_) <- readCharFromBuffer (bufBuf buf) (bufRPtr buf)
1241 -- ---------------------------------------------------------------------------
1242 -- Buffering Operations
1244 -- Three kinds of buffering are supported: line-buffering,
1245 -- block-buffering or no-buffering. See GHC.IOBase for definition and
1246 -- further explanation of what the type represent.
1248 -- | Computation 'hSetBuffering' @hdl mode@ sets the mode of buffering for
1249 -- handle @hdl@ on subsequent reads and writes.
1251 -- If the buffer mode is changed from 'BlockBuffering' or
1252 -- 'LineBuffering' to 'NoBuffering', then
1254 -- * if @hdl@ is writable, the buffer is flushed as for 'hFlush';
1256 -- * if @hdl@ is not writable, the contents of the buffer is discarded.
1258 -- This operation may fail with:
1260 -- * 'isPermissionError' if the handle has already been used for reading
1261 -- or writing and the implementation does not allow the buffering mode
1264 hSetBuffering :: Handle -> BufferMode -> IO ()
1265 hSetBuffering handle mode =
1266 withAllHandles__ "hSetBuffering" handle $ \ handle_ -> do
1267 case haType handle_ of
1268 ClosedHandle -> ioe_closedHandle
1271 - we flush the old buffer regardless of whether
1272 the new buffer could fit the contents of the old buffer
1274 - allow a handle's buffering to change even if IO has
1275 occurred (ANSI C spec. does not allow this, nor did
1276 the previous implementation of IO.hSetBuffering).
1277 - a non-standard extension is to allow the buffering
1278 of semi-closed handles to change [sof 6/98]
1282 let state = initBufferState (haType handle_)
1285 -- we always have a 1-character read buffer for
1286 -- unbuffered handles: it's needed to
1287 -- support hLookAhead.
1288 NoBuffering -> allocateBuffer 1 ReadBuffer
1289 LineBuffering -> allocateBuffer dEFAULT_BUFFER_SIZE state
1290 BlockBuffering Nothing -> allocateBuffer dEFAULT_BUFFER_SIZE state
1291 BlockBuffering (Just n) | n <= 0 -> ioe_bufsiz n
1292 | otherwise -> allocateBuffer n state
1293 writeIORef (haBuffer handle_) new_buf
1295 -- for input terminals we need to put the terminal into
1296 -- cooked or raw mode depending on the type of buffering.
1297 is_tty <- fdIsTTY (haFD handle_)
1298 when (is_tty && isReadableHandleType (haType handle_)) $
1300 #ifndef mingw32_HOST_OS
1301 -- 'raw' mode under win32 is a bit too specialised (and troublesome
1302 -- for most common uses), so simply disable its use here.
1303 NoBuffering -> setCooked (haFD handle_) False
1305 NoBuffering -> return ()
1307 _ -> setCooked (haFD handle_) True
1309 -- throw away spare buffers, they might be the wrong size
1310 writeIORef (haBuffers handle_) BufferListNil
1312 return (handle_{ haBufferMode = mode })
1314 -- -----------------------------------------------------------------------------
1317 -- | The action 'hFlush' @hdl@ causes any items buffered for output
1318 -- in handle @hdl@ to be sent immediately to the operating system.
1320 -- This operation may fail with:
1322 -- * 'isFullError' if the device is full;
1324 -- * 'isPermissionError' if a system resource limit would be exceeded.
1325 -- It is unspecified whether the characters in the buffer are discarded
1326 -- or retained under these circumstances.
1328 hFlush :: Handle -> IO ()
1330 wantWritableHandle "hFlush" handle $ \ handle_ -> do
1331 buf <- readIORef (haBuffer handle_)
1332 if bufferIsWritable buf && not (bufferEmpty buf)
1333 then do flushed_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
1334 writeIORef (haBuffer handle_) flushed_buf
1338 -- -----------------------------------------------------------------------------
1339 -- Repositioning Handles
1341 data HandlePosn = HandlePosn Handle HandlePosition
1343 instance Eq HandlePosn where
1344 (HandlePosn h1 p1) == (HandlePosn h2 p2) = p1==p2 && h1==h2
1346 instance Show HandlePosn where
1347 showsPrec p (HandlePosn h pos) =
1348 showsPrec p h . showString " at position " . shows pos
1350 -- HandlePosition is the Haskell equivalent of POSIX' off_t.
1351 -- We represent it as an Integer on the Haskell side, but
1352 -- cheat slightly in that hGetPosn calls upon a C helper
1353 -- that reports the position back via (merely) an Int.
1354 type HandlePosition = Integer
1356 -- | Computation 'hGetPosn' @hdl@ returns the current I\/O position of
1357 -- @hdl@ as a value of the abstract type 'HandlePosn'.
1359 hGetPosn :: Handle -> IO HandlePosn
1360 hGetPosn handle = do
1361 posn <- hTell handle
1362 return (HandlePosn handle posn)
1364 -- | If a call to 'hGetPosn' @hdl@ returns a position @p@,
1365 -- then computation 'hSetPosn' @p@ sets the position of @hdl@
1366 -- to the position it held at the time of the call to 'hGetPosn'.
1368 -- This operation may fail with:
1370 -- * 'isPermissionError' if a system resource limit would be exceeded.
1372 hSetPosn :: HandlePosn -> IO ()
1373 hSetPosn (HandlePosn h i) = hSeek h AbsoluteSeek i
1375 -- ---------------------------------------------------------------------------
1378 -- | A mode that determines the effect of 'hSeek' @hdl mode i@, as follows:
1380 = AbsoluteSeek -- ^ the position of @hdl@ is set to @i@.
1381 | RelativeSeek -- ^ the position of @hdl@ is set to offset @i@
1382 -- from the current position.
1383 | SeekFromEnd -- ^ the position of @hdl@ is set to offset @i@
1384 -- from the end of the file.
1385 deriving (Eq, Ord, Ix, Enum, Read, Show)
1388 - when seeking using `SeekFromEnd', positive offsets (>=0) means
1389 seeking at or past EOF.
1391 - we possibly deviate from the report on the issue of seeking within
1392 the buffer and whether to flush it or not. The report isn't exactly
1396 -- | Computation 'hSeek' @hdl mode i@ sets the position of handle
1397 -- @hdl@ depending on @mode@.
1398 -- The offset @i@ is given in terms of 8-bit bytes.
1400 -- If @hdl@ is block- or line-buffered, then seeking to a position which is not
1401 -- in the current buffer will first cause any items in the output buffer to be
1402 -- written to the device, and then cause the input buffer to be discarded.
1403 -- Some handles may not be seekable (see 'hIsSeekable'), or only support a
1404 -- subset of the possible positioning operations (for instance, it may only
1405 -- be possible to seek to the end of a tape, or to a positive offset from
1406 -- the beginning or current position).
1407 -- It is not possible to set a negative I\/O position, or for
1408 -- a physical file, an I\/O position beyond the current end-of-file.
1410 -- This operation may fail with:
1412 -- * 'isPermissionError' if a system resource limit would be exceeded.
1414 hSeek :: Handle -> SeekMode -> Integer -> IO ()
1415 hSeek handle mode offset =
1416 wantSeekableHandle "hSeek" handle $ \ handle_ -> do
1418 puts ("hSeek " ++ show (mode,offset) ++ "\n")
1420 let ref = haBuffer handle_
1421 buf <- readIORef ref
1427 throwErrnoIfMinus1Retry_ "hSeek"
1428 (c_lseek (haFD handle_) (fromIntegral offset) whence)
1431 whence = case mode of
1432 AbsoluteSeek -> sEEK_SET
1433 RelativeSeek -> sEEK_CUR
1434 SeekFromEnd -> sEEK_END
1436 if bufferIsWritable buf
1437 then do new_buf <- flushWriteBuffer fd (haIsStream handle_) buf
1438 writeIORef ref new_buf
1442 if mode == RelativeSeek && offset >= 0 && offset < fromIntegral (w - r)
1443 then writeIORef ref buf{ bufRPtr = r + fromIntegral offset }
1446 new_buf <- flushReadBuffer (haFD handle_) buf
1447 writeIORef ref new_buf
1451 hTell :: Handle -> IO Integer
1453 wantSeekableHandle "hGetPosn" handle $ \ handle_ -> do
1455 #if defined(mingw32_HOST_OS)
1456 -- urgh, on Windows we have to worry about \n -> \r\n translation,
1457 -- so we can't easily calculate the file position using the
1458 -- current buffer size. Just flush instead.
1461 let fd = haFD handle_
1462 posn <- fromIntegral `liftM`
1463 throwErrnoIfMinus1Retry "hGetPosn"
1464 (c_lseek fd 0 sEEK_CUR)
1466 let ref = haBuffer handle_
1467 buf <- readIORef ref
1470 | bufferIsWritable buf = posn + fromIntegral (bufWPtr buf)
1471 | otherwise = posn - fromIntegral (bufWPtr buf - bufRPtr buf)
1473 puts ("\nhGetPosn: (fd, posn, real_posn) = " ++ show (fd, posn, real_posn) ++ "\n")
1474 puts (" (bufWPtr, bufRPtr) = " ++ show (bufWPtr buf, bufRPtr buf) ++ "\n")
1478 -- -----------------------------------------------------------------------------
1479 -- Handle Properties
1481 -- A number of operations return information about the properties of a
1482 -- handle. Each of these operations returns `True' if the handle has
1483 -- the specified property, and `False' otherwise.
1485 hIsOpen :: Handle -> IO Bool
1487 withHandle_ "hIsOpen" handle $ \ handle_ -> do
1488 case haType handle_ of
1489 ClosedHandle -> return False
1490 SemiClosedHandle -> return False
1493 hIsClosed :: Handle -> IO Bool
1495 withHandle_ "hIsClosed" handle $ \ handle_ -> do
1496 case haType handle_ of
1497 ClosedHandle -> return True
1500 {- not defined, nor exported, but mentioned
1501 here for documentation purposes:
1503 hSemiClosed :: Handle -> IO Bool
1507 return (not (ho || hc))
1510 hIsReadable :: Handle -> IO Bool
1511 hIsReadable (DuplexHandle _ _ _) = return True
1512 hIsReadable handle =
1513 withHandle_ "hIsReadable" handle $ \ handle_ -> do
1514 case haType handle_ of
1515 ClosedHandle -> ioe_closedHandle
1516 SemiClosedHandle -> ioe_closedHandle
1517 htype -> return (isReadableHandleType htype)
1519 hIsWritable :: Handle -> IO Bool
1520 hIsWritable (DuplexHandle _ _ _) = return True
1521 hIsWritable handle =
1522 withHandle_ "hIsWritable" handle $ \ handle_ -> do
1523 case haType handle_ of
1524 ClosedHandle -> ioe_closedHandle
1525 SemiClosedHandle -> ioe_closedHandle
1526 htype -> return (isWritableHandleType htype)
1528 -- | Computation 'hGetBuffering' @hdl@ returns the current buffering mode
1531 hGetBuffering :: Handle -> IO BufferMode
1532 hGetBuffering handle =
1533 withHandle_ "hGetBuffering" handle $ \ handle_ -> do
1534 case haType handle_ of
1535 ClosedHandle -> ioe_closedHandle
1537 -- We're being non-standard here, and allow the buffering
1538 -- of a semi-closed handle to be queried. -- sof 6/98
1539 return (haBufferMode handle_) -- could be stricter..
1541 hIsSeekable :: Handle -> IO Bool
1542 hIsSeekable handle =
1543 withHandle_ "hIsSeekable" handle $ \ handle_ -> do
1544 case haType handle_ of
1545 ClosedHandle -> ioe_closedHandle
1546 SemiClosedHandle -> ioe_closedHandle
1547 AppendHandle -> return False
1548 _ -> do t <- fdType (haFD handle_)
1549 return ((t == RegularFile || t == RawDevice)
1550 && (haIsBin handle_ || tEXT_MODE_SEEK_ALLOWED))
1552 -- -----------------------------------------------------------------------------
1553 -- Changing echo status (Non-standard GHC extensions)
1555 -- | Set the echoing status of a handle connected to a terminal.
1557 hSetEcho :: Handle -> Bool -> IO ()
1558 hSetEcho handle on = do
1559 isT <- hIsTerminalDevice handle
1563 withHandle_ "hSetEcho" handle $ \ handle_ -> do
1564 case haType handle_ of
1565 ClosedHandle -> ioe_closedHandle
1566 _ -> setEcho (haFD handle_) on
1568 -- | Get the echoing status of a handle connected to a terminal.
1570 hGetEcho :: Handle -> IO Bool
1571 hGetEcho handle = do
1572 isT <- hIsTerminalDevice handle
1576 withHandle_ "hGetEcho" handle $ \ handle_ -> do
1577 case haType handle_ of
1578 ClosedHandle -> ioe_closedHandle
1579 _ -> getEcho (haFD handle_)
1581 -- | Is the handle connected to a terminal?
1583 hIsTerminalDevice :: Handle -> IO Bool
1584 hIsTerminalDevice handle = do
1585 withHandle_ "hIsTerminalDevice" handle $ \ handle_ -> do
1586 case haType handle_ of
1587 ClosedHandle -> ioe_closedHandle
1588 _ -> fdIsTTY (haFD handle_)
1590 -- -----------------------------------------------------------------------------
1593 -- | Select binary mode ('True') or text mode ('False') on a open handle.
1594 -- (See also 'openBinaryFile'.)
1596 hSetBinaryMode :: Handle -> Bool -> IO ()
1597 hSetBinaryMode handle bin =
1598 withAllHandles__ "hSetBinaryMode" handle $ \ handle_ ->
1599 do throwErrnoIfMinus1_ "hSetBinaryMode"
1600 (setmode (haFD handle_) bin)
1601 return handle_{haIsBin=bin}
1603 foreign import ccall unsafe "__hscore_setmode"
1604 setmode :: CInt -> Bool -> IO CInt
1606 -- -----------------------------------------------------------------------------
1607 -- Duplicating a Handle
1609 -- | Returns a duplicate of the original handle, with its own buffer.
1610 -- The two Handles will share a file pointer, however. The original
1611 -- handle's buffer is flushed, including discarding any input data,
1612 -- before the handle is duplicated.
1614 hDuplicate :: Handle -> IO Handle
1615 hDuplicate h@(FileHandle path m) = do
1616 new_h_ <- withHandle' "hDuplicate" h m (dupHandle h Nothing)
1617 newFileHandle path (handleFinalizer path) new_h_
1618 hDuplicate h@(DuplexHandle path r w) = do
1619 new_w_ <- withHandle' "hDuplicate" h w (dupHandle h Nothing)
1620 new_w <- newMVar new_w_
1621 new_r_ <- withHandle' "hDuplicate" h r (dupHandle h (Just new_w))
1622 new_r <- newMVar new_r_
1623 addMVarFinalizer new_w (handleFinalizer path new_w)
1624 return (DuplexHandle path new_r new_w)
1626 dupHandle :: Handle -> Maybe (MVar Handle__) -> Handle__
1627 -> IO (Handle__, Handle__)
1628 dupHandle h other_side h_ = do
1629 -- flush the buffer first, so we don't have to copy its contents
1631 new_fd <- case other_side of
1632 Nothing -> throwErrnoIfMinus1 "dupHandle" $ c_dup (haFD h_)
1633 Just r -> withHandle_' "dupHandle" h r (return . haFD)
1634 dupHandle_ other_side h_ new_fd
1636 dupHandleTo other_side hto_ h_ = do
1638 -- Windows' dup2 does not return the new descriptor, unlike Unix
1639 throwErrnoIfMinus1 "dupHandleTo" $
1640 c_dup2 (haFD h_) (haFD hto_)
1641 dupHandle_ other_side h_ (haFD hto_)
1643 dupHandle_ :: Maybe (MVar Handle__) -> Handle__ -> FD
1644 -> IO (Handle__, Handle__)
1645 dupHandle_ other_side h_ new_fd = do
1646 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE (initBufferState (haType h_))
1647 ioref <- newIORef buffer
1648 ioref_buffers <- newIORef BufferListNil
1650 let new_handle_ = h_{ haFD = new_fd,
1652 haBuffers = ioref_buffers,
1653 haOtherSide = other_side }
1654 return (h_, new_handle_)
1656 -- -----------------------------------------------------------------------------
1657 -- Replacing a Handle
1660 Makes the second handle a duplicate of the first handle. The second
1661 handle will be closed first, if it is not already.
1663 This can be used to retarget the standard Handles, for example:
1665 > do h <- openFile "mystdout" WriteMode
1666 > hDuplicateTo h stdout
1669 hDuplicateTo :: Handle -> Handle -> IO ()
1670 hDuplicateTo h1@(FileHandle _ m1) h2@(FileHandle _ m2) = do
1671 withHandle__' "hDuplicateTo" h2 m2 $ \h2_ -> do
1672 _ <- hClose_help h2_
1673 withHandle' "hDuplicateTo" h1 m1 (dupHandleTo Nothing h2_)
1674 hDuplicateTo h1@(DuplexHandle _ r1 w1) h2@(DuplexHandle _ r2 w2) = do
1675 withHandle__' "hDuplicateTo" h2 w2 $ \w2_ -> do
1676 _ <- hClose_help w2_
1677 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo Nothing w2_)
1678 withHandle__' "hDuplicateTo" h2 r2 $ \r2_ -> do
1679 _ <- hClose_help r2_
1680 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo (Just w1) r2_)
1682 ioException (IOError (Just h1) IllegalOperation "hDuplicateTo"
1683 "handles are incompatible" Nothing)
1685 -- ---------------------------------------------------------------------------
1688 -- | 'hShow' is in the 'IO' monad, and gives more comprehensive output
1689 -- than the (pure) instance of 'Show' for 'Handle'.
1691 hShow :: Handle -> IO String
1692 hShow h@(FileHandle path _) = showHandle' path False h
1693 hShow h@(DuplexHandle path _ _) = showHandle' path True h
1695 showHandle' filepath is_duplex h =
1696 withHandle_ "showHandle" h $ \hdl_ ->
1698 showType | is_duplex = showString "duplex (read-write)"
1699 | otherwise = shows (haType hdl_)
1703 showHdl (haType hdl_)
1704 (showString "loc=" . showString filepath . showChar ',' .
1705 showString "type=" . showType . showChar ',' .
1706 showString "binary=" . shows (haIsBin hdl_) . showChar ',' .
1707 showString "buffering=" . showBufMode (unsafePerformIO (readIORef (haBuffer hdl_))) (haBufferMode hdl_) . showString "}" )
1711 showHdl :: HandleType -> ShowS -> ShowS
1714 ClosedHandle -> shows ht . showString "}"
1717 showBufMode :: Buffer -> BufferMode -> ShowS
1718 showBufMode buf bmo =
1720 NoBuffering -> showString "none"
1721 LineBuffering -> showString "line"
1722 BlockBuffering (Just n) -> showString "block " . showParen True (shows n)
1723 BlockBuffering Nothing -> showString "block " . showParen True (shows def)
1728 -- ---------------------------------------------------------------------------
1731 #if defined(DEBUG_DUMP)
1732 puts :: String -> IO ()
1733 puts s = do write_rawBuffer 1 (unsafeCoerce# (packCString# s)) 0 (fromIntegral (length s))
1737 -- -----------------------------------------------------------------------------
1740 throwErrnoIfMinus1RetryOnBlock :: String -> IO CInt -> IO CInt -> IO CInt
1741 throwErrnoIfMinus1RetryOnBlock loc f on_block =
1744 if (res :: CInt) == -1
1748 then throwErrnoIfMinus1RetryOnBlock loc f on_block
1749 else if err == eWOULDBLOCK || err == eAGAIN
1754 -- -----------------------------------------------------------------------------
1755 -- wrappers to platform-specific constants:
1757 foreign import ccall unsafe "__hscore_supportsTextMode"
1758 tEXT_MODE_SEEK_ALLOWED :: Bool
1760 foreign import ccall unsafe "__hscore_bufsiz" dEFAULT_BUFFER_SIZE :: Int
1761 foreign import ccall unsafe "__hscore_seek_cur" sEEK_CUR :: CInt
1762 foreign import ccall unsafe "__hscore_seek_set" sEEK_SET :: CInt
1763 foreign import ccall unsafe "__hscore_seek_end" sEEK_END :: CInt