1 {-# OPTIONS_GHC -fno-implicit-prelude -#include "HsBase.h" #-}
6 -----------------------------------------------------------------------------
9 -- Copyright : (c) The University of Glasgow, 1994-2001
10 -- License : see libraries/base/LICENSE
12 -- Maintainer : libraries@haskell.org
13 -- Stability : internal
14 -- Portability : non-portable
16 -- This module defines the basic operations on I\/O \"handles\".
18 -----------------------------------------------------------------------------
22 withHandle, withHandle', withHandle_,
23 wantWritableHandle, wantReadableHandle, wantSeekableHandle,
25 newEmptyBuffer, allocateBuffer, readCharFromBuffer, writeCharIntoBuffer,
26 flushWriteBufferOnly, flushWriteBuffer, flushReadBuffer,
27 fillReadBuffer, fillReadBufferWithoutBlocking,
28 readRawBuffer, readRawBufferPtr,
29 writeRawBuffer, writeRawBufferPtr,
31 #ifndef mingw32_HOST_OS
35 ioe_closedHandle, ioe_EOF, ioe_notReadable, ioe_notWritable,
37 stdin, stdout, stderr,
38 IOMode(..), openFile, openBinaryFile, fdToHandle', fdToHandle,
39 hFileSize, hSetFileSize, hIsEOF, isEOF, hLookAhead, hSetBuffering, hSetBinaryMode,
40 hFlush, hDuplicate, hDuplicateTo,
44 HandlePosition, HandlePosn(..), hGetPosn, hSetPosn,
45 SeekMode(..), hSeek, hTell,
47 hIsOpen, hIsClosed, hIsReadable, hIsWritable, hGetBuffering, hIsSeekable,
48 hSetEcho, hGetEcho, hIsTerminalDevice,
63 import System.IO.Error
64 import System.Posix.Internals
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' 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 -- ---------------------------------------------------------------------------
912 -> Maybe (FDType, CDev, CIno)
919 fdToHandle' 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 fdToHandle :: FD -> IO Handle
974 let fd_str = "<file descriptor: " ++ show fd ++ ">"
975 fdToHandle' fd Nothing False{-XXX!-} fd_str mode True{-bin mode-}
978 #ifndef mingw32_HOST_OS
979 foreign import ccall unsafe "lockFile"
980 lockFile :: CInt -> CDev -> CIno -> CInt -> IO CInt
982 foreign import ccall unsafe "unlockFile"
983 unlockFile :: CInt -> IO CInt
986 mkStdHandle :: FD -> FilePath -> HandleType -> IORef Buffer -> BufferMode
988 mkStdHandle fd filepath ha_type buf bmode = do
989 spares <- newIORef BufferListNil
990 newFileHandle filepath (stdHandleFinalizer filepath)
991 (Handle__ { haFD = fd,
993 haIsBin = dEFAULT_OPEN_IN_BINARY_MODE,
994 haIsStream = False, -- means FD is blocking on Unix
995 haBufferMode = bmode,
998 haOtherSide = Nothing
1001 mkFileHandle :: FD -> Bool -> FilePath -> HandleType -> Bool -> IO Handle
1002 mkFileHandle fd is_stream filepath ha_type binary = do
1003 (buf, bmode) <- getBuffer fd (initBufferState ha_type)
1005 #ifdef mingw32_HOST_OS
1006 -- On Windows, if this is a read/write handle and we are in text mode,
1007 -- turn off buffering. We don't correctly handle the case of switching
1008 -- from read mode to write mode on a buffered text-mode handle, see bug
1010 bmode <- case ha_type of
1011 ReadWriteHandle | not binary -> return NoBuffering
1012 _other -> return bmode
1015 spares <- newIORef BufferListNil
1016 newFileHandle filepath (handleFinalizer filepath)
1017 (Handle__ { haFD = fd,
1020 haIsStream = is_stream,
1021 haBufferMode = bmode,
1024 haOtherSide = Nothing
1027 mkDuplexHandle :: FD -> Bool -> FilePath -> Bool -> IO Handle
1028 mkDuplexHandle fd is_stream filepath binary = do
1029 (w_buf, w_bmode) <- getBuffer fd WriteBuffer
1030 w_spares <- newIORef BufferListNil
1032 Handle__ { haFD = fd,
1033 haType = WriteHandle,
1035 haIsStream = is_stream,
1036 haBufferMode = w_bmode,
1038 haBuffers = w_spares,
1039 haOtherSide = Nothing
1041 write_side <- newMVar w_handle_
1043 (r_buf, r_bmode) <- getBuffer fd ReadBuffer
1044 r_spares <- newIORef BufferListNil
1046 Handle__ { haFD = fd,
1047 haType = ReadHandle,
1049 haIsStream = is_stream,
1050 haBufferMode = r_bmode,
1052 haBuffers = r_spares,
1053 haOtherSide = Just write_side
1055 read_side <- newMVar r_handle_
1057 addMVarFinalizer write_side (handleFinalizer filepath write_side)
1058 return (DuplexHandle filepath read_side write_side)
1061 initBufferState ReadHandle = ReadBuffer
1062 initBufferState _ = WriteBuffer
1064 -- ---------------------------------------------------------------------------
1067 -- | Computation 'hClose' @hdl@ makes handle @hdl@ closed. Before the
1068 -- computation finishes, if @hdl@ is writable its buffer is flushed as
1070 -- Performing 'hClose' on a handle that has already been closed has no effect;
1071 -- doing so is not an error. All other operations on a closed handle will fail.
1072 -- If 'hClose' fails for any reason, any further operations (apart from
1073 -- 'hClose') on the handle will still fail as if @hdl@ had been successfully
1076 hClose :: Handle -> IO ()
1077 hClose h@(FileHandle _ m) = do
1078 mb_exc <- hClose' h m
1080 Nothing -> return ()
1082 hClose h@(DuplexHandle _ r w) = do
1083 mb_exc1 <- hClose' h w
1084 mb_exc2 <- hClose' h r
1085 case (do mb_exc1; mb_exc2) of
1086 Nothing -> return ()
1089 hClose' h m = withHandle' "hClose" h m $ hClose_help
1091 -- hClose_help is also called by lazyRead (in PrelIO) when EOF is read
1092 -- or an IO error occurs on a lazy stream. The semi-closed Handle is
1093 -- then closed immediately. We have to be careful with DuplexHandles
1094 -- though: we have to leave the closing to the finalizer in that case,
1095 -- because the write side may still be in use.
1096 hClose_help :: Handle__ -> IO (Handle__, Maybe Exception)
1097 hClose_help handle_ =
1098 case haType handle_ of
1099 ClosedHandle -> return (handle_,Nothing)
1100 _ -> do flushWriteBufferOnly handle_ -- interruptible
1101 hClose_handle_ handle_
1103 hClose_handle_ handle_ = do
1104 let fd = haFD handle_
1106 -- close the file descriptor, but not when this is the read
1107 -- side of a duplex handle.
1108 -- If an exception is raised by the close(), we want to continue
1109 -- to close the handle and release the lock if it has one, then
1110 -- we return the exception to the caller of hClose_help which can
1111 -- raise it if necessary.
1113 case haOtherSide handle_ of
1115 throwErrnoIfMinus1Retry_ "hClose"
1116 #ifdef mingw32_HOST_OS
1117 (closeFd (haIsStream handle_) fd)
1123 `catchException` \e -> return (Just e)
1125 Just _ -> return Nothing
1127 -- free the spare buffers
1128 writeIORef (haBuffers handle_) BufferListNil
1129 writeIORef (haBuffer handle_) noBuffer
1131 #ifndef mingw32_HOST_OS
1136 -- we must set the fd to -1, because the finalizer is going
1137 -- to run eventually and try to close/unlock it.
1138 return (handle_{ haFD = -1,
1139 haType = ClosedHandle
1143 {-# NOINLINE noBuffer #-}
1144 noBuffer = unsafePerformIO $ allocateBuffer 1 ReadBuffer
1146 -----------------------------------------------------------------------------
1147 -- Detecting and changing the size of a file
1149 -- | For a handle @hdl@ which attached to a physical file,
1150 -- 'hFileSize' @hdl@ returns the size of that file in 8-bit bytes.
1152 hFileSize :: Handle -> IO Integer
1154 withHandle_ "hFileSize" handle $ \ handle_ -> do
1155 case haType handle_ of
1156 ClosedHandle -> ioe_closedHandle
1157 SemiClosedHandle -> ioe_closedHandle
1158 _ -> do flushWriteBufferOnly handle_
1159 r <- fdFileSize (haFD handle_)
1162 else ioException (IOError Nothing InappropriateType "hFileSize"
1163 "not a regular file" Nothing)
1166 -- | 'hSetFileSize' @hdl@ @size@ truncates the physical file with handle @hdl@ to @size@ bytes.
1168 hSetFileSize :: Handle -> Integer -> IO ()
1169 hSetFileSize handle size =
1170 withHandle_ "hSetFileSize" handle $ \ handle_ -> do
1171 case haType handle_ of
1172 ClosedHandle -> ioe_closedHandle
1173 SemiClosedHandle -> ioe_closedHandle
1174 _ -> do flushWriteBufferOnly handle_
1175 throwErrnoIf (/=0) "hSetFileSize"
1176 (c_ftruncate (haFD handle_) (fromIntegral size))
1179 -- ---------------------------------------------------------------------------
1180 -- Detecting the End of Input
1182 -- | For a readable handle @hdl@, 'hIsEOF' @hdl@ returns
1183 -- 'True' if no further input can be taken from @hdl@ or for a
1184 -- physical file, if the current I\/O position is equal to the length of
1185 -- the file. Otherwise, it returns 'False'.
1187 hIsEOF :: Handle -> IO Bool
1190 (do hLookAhead handle; return False)
1191 (\e -> if isEOFError e then return True else ioError e)
1193 -- | The computation 'isEOF' is identical to 'hIsEOF',
1194 -- except that it works only on 'stdin'.
1197 isEOF = hIsEOF stdin
1199 -- ---------------------------------------------------------------------------
1202 -- | Computation 'hLookAhead' returns the next character from the handle
1203 -- without removing it from the input buffer, blocking until a character
1206 -- This operation may fail with:
1208 -- * 'isEOFError' if the end of file has been reached.
1210 hLookAhead :: Handle -> IO Char
1211 hLookAhead handle = do
1212 wantReadableHandle "hLookAhead" handle $ \handle_ -> do
1213 let ref = haBuffer handle_
1215 is_line = haBufferMode handle_ == LineBuffering
1216 buf <- readIORef ref
1218 -- fill up the read buffer if necessary
1219 new_buf <- if bufferEmpty buf
1220 then fillReadBuffer fd True (haIsStream handle_) buf
1223 writeIORef ref new_buf
1225 (c,_) <- readCharFromBuffer (bufBuf buf) (bufRPtr buf)
1228 -- ---------------------------------------------------------------------------
1229 -- Buffering Operations
1231 -- Three kinds of buffering are supported: line-buffering,
1232 -- block-buffering or no-buffering. See GHC.IOBase for definition and
1233 -- further explanation of what the type represent.
1235 -- | Computation 'hSetBuffering' @hdl mode@ sets the mode of buffering for
1236 -- handle @hdl@ on subsequent reads and writes.
1238 -- If the buffer mode is changed from 'BlockBuffering' or
1239 -- 'LineBuffering' to 'NoBuffering', then
1241 -- * if @hdl@ is writable, the buffer is flushed as for 'hFlush';
1243 -- * if @hdl@ is not writable, the contents of the buffer is discarded.
1245 -- This operation may fail with:
1247 -- * 'isPermissionError' if the handle has already been used for reading
1248 -- or writing and the implementation does not allow the buffering mode
1251 hSetBuffering :: Handle -> BufferMode -> IO ()
1252 hSetBuffering handle mode =
1253 withAllHandles__ "hSetBuffering" handle $ \ handle_ -> do
1254 case haType handle_ of
1255 ClosedHandle -> ioe_closedHandle
1258 - we flush the old buffer regardless of whether
1259 the new buffer could fit the contents of the old buffer
1261 - allow a handle's buffering to change even if IO has
1262 occurred (ANSI C spec. does not allow this, nor did
1263 the previous implementation of IO.hSetBuffering).
1264 - a non-standard extension is to allow the buffering
1265 of semi-closed handles to change [sof 6/98]
1269 let state = initBufferState (haType handle_)
1272 -- we always have a 1-character read buffer for
1273 -- unbuffered handles: it's needed to
1274 -- support hLookAhead.
1275 NoBuffering -> allocateBuffer 1 ReadBuffer
1276 LineBuffering -> allocateBuffer dEFAULT_BUFFER_SIZE state
1277 BlockBuffering Nothing -> allocateBuffer dEFAULT_BUFFER_SIZE state
1278 BlockBuffering (Just n) | n <= 0 -> ioe_bufsiz n
1279 | otherwise -> allocateBuffer n state
1280 writeIORef (haBuffer handle_) new_buf
1282 -- for input terminals we need to put the terminal into
1283 -- cooked or raw mode depending on the type of buffering.
1284 is_tty <- fdIsTTY (haFD handle_)
1285 when (is_tty && isReadableHandleType (haType handle_)) $
1287 #ifndef mingw32_HOST_OS
1288 -- 'raw' mode under win32 is a bit too specialised (and troublesome
1289 -- for most common uses), so simply disable its use here.
1290 NoBuffering -> setCooked (haFD handle_) False
1292 NoBuffering -> return ()
1294 _ -> setCooked (haFD handle_) True
1296 -- throw away spare buffers, they might be the wrong size
1297 writeIORef (haBuffers handle_) BufferListNil
1299 return (handle_{ haBufferMode = mode })
1301 -- -----------------------------------------------------------------------------
1304 -- | The action 'hFlush' @hdl@ causes any items buffered for output
1305 -- in handle @hdl@ to be sent immediately to the operating system.
1307 -- This operation may fail with:
1309 -- * 'isFullError' if the device is full;
1311 -- * 'isPermissionError' if a system resource limit would be exceeded.
1312 -- It is unspecified whether the characters in the buffer are discarded
1313 -- or retained under these circumstances.
1315 hFlush :: Handle -> IO ()
1317 wantWritableHandle "hFlush" handle $ \ handle_ -> do
1318 buf <- readIORef (haBuffer handle_)
1319 if bufferIsWritable buf && not (bufferEmpty buf)
1320 then do flushed_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
1321 writeIORef (haBuffer handle_) flushed_buf
1325 -- -----------------------------------------------------------------------------
1326 -- Repositioning Handles
1328 data HandlePosn = HandlePosn Handle HandlePosition
1330 instance Eq HandlePosn where
1331 (HandlePosn h1 p1) == (HandlePosn h2 p2) = p1==p2 && h1==h2
1333 instance Show HandlePosn where
1334 showsPrec p (HandlePosn h pos) =
1335 showsPrec p h . showString " at position " . shows pos
1337 -- HandlePosition is the Haskell equivalent of POSIX' off_t.
1338 -- We represent it as an Integer on the Haskell side, but
1339 -- cheat slightly in that hGetPosn calls upon a C helper
1340 -- that reports the position back via (merely) an Int.
1341 type HandlePosition = Integer
1343 -- | Computation 'hGetPosn' @hdl@ returns the current I\/O position of
1344 -- @hdl@ as a value of the abstract type 'HandlePosn'.
1346 hGetPosn :: Handle -> IO HandlePosn
1347 hGetPosn handle = do
1348 posn <- hTell handle
1349 return (HandlePosn handle posn)
1351 -- | If a call to 'hGetPosn' @hdl@ returns a position @p@,
1352 -- then computation 'hSetPosn' @p@ sets the position of @hdl@
1353 -- to the position it held at the time of the call to 'hGetPosn'.
1355 -- This operation may fail with:
1357 -- * 'isPermissionError' if a system resource limit would be exceeded.
1359 hSetPosn :: HandlePosn -> IO ()
1360 hSetPosn (HandlePosn h i) = hSeek h AbsoluteSeek i
1362 -- ---------------------------------------------------------------------------
1365 -- | A mode that determines the effect of 'hSeek' @hdl mode i@, as follows:
1367 = AbsoluteSeek -- ^ the position of @hdl@ is set to @i@.
1368 | RelativeSeek -- ^ the position of @hdl@ is set to offset @i@
1369 -- from the current position.
1370 | SeekFromEnd -- ^ the position of @hdl@ is set to offset @i@
1371 -- from the end of the file.
1372 deriving (Eq, Ord, Ix, Enum, Read, Show)
1375 - when seeking using `SeekFromEnd', positive offsets (>=0) means
1376 seeking at or past EOF.
1378 - we possibly deviate from the report on the issue of seeking within
1379 the buffer and whether to flush it or not. The report isn't exactly
1383 -- | Computation 'hSeek' @hdl mode i@ sets the position of handle
1384 -- @hdl@ depending on @mode@.
1385 -- The offset @i@ is given in terms of 8-bit bytes.
1387 -- If @hdl@ is block- or line-buffered, then seeking to a position which is not
1388 -- in the current buffer will first cause any items in the output buffer to be
1389 -- written to the device, and then cause the input buffer to be discarded.
1390 -- Some handles may not be seekable (see 'hIsSeekable'), or only support a
1391 -- subset of the possible positioning operations (for instance, it may only
1392 -- be possible to seek to the end of a tape, or to a positive offset from
1393 -- the beginning or current position).
1394 -- It is not possible to set a negative I\/O position, or for
1395 -- a physical file, an I\/O position beyond the current end-of-file.
1397 -- This operation may fail with:
1399 -- * 'isPermissionError' if a system resource limit would be exceeded.
1401 hSeek :: Handle -> SeekMode -> Integer -> IO ()
1402 hSeek handle mode offset =
1403 wantSeekableHandle "hSeek" handle $ \ handle_ -> do
1405 puts ("hSeek " ++ show (mode,offset) ++ "\n")
1407 let ref = haBuffer handle_
1408 buf <- readIORef ref
1414 throwErrnoIfMinus1Retry_ "hSeek"
1415 (c_lseek (haFD handle_) (fromIntegral offset) whence)
1418 whence = case mode of
1419 AbsoluteSeek -> sEEK_SET
1420 RelativeSeek -> sEEK_CUR
1421 SeekFromEnd -> sEEK_END
1423 if bufferIsWritable buf
1424 then do new_buf <- flushWriteBuffer fd (haIsStream handle_) buf
1425 writeIORef ref new_buf
1429 if mode == RelativeSeek && offset >= 0 && offset < fromIntegral (w - r)
1430 then writeIORef ref buf{ bufRPtr = r + fromIntegral offset }
1433 new_buf <- flushReadBuffer (haFD handle_) buf
1434 writeIORef ref new_buf
1438 hTell :: Handle -> IO Integer
1440 wantSeekableHandle "hGetPosn" handle $ \ handle_ -> do
1442 #if defined(mingw32_HOST_OS)
1443 -- urgh, on Windows we have to worry about \n -> \r\n translation,
1444 -- so we can't easily calculate the file position using the
1445 -- current buffer size. Just flush instead.
1448 let fd = haFD handle_
1449 posn <- fromIntegral `liftM`
1450 throwErrnoIfMinus1Retry "hGetPosn"
1451 (c_lseek fd 0 sEEK_CUR)
1453 let ref = haBuffer handle_
1454 buf <- readIORef ref
1457 | bufferIsWritable buf = posn + fromIntegral (bufWPtr buf)
1458 | otherwise = posn - fromIntegral (bufWPtr buf - bufRPtr buf)
1460 puts ("\nhGetPosn: (fd, posn, real_posn) = " ++ show (fd, posn, real_posn) ++ "\n")
1461 puts (" (bufWPtr, bufRPtr) = " ++ show (bufWPtr buf, bufRPtr buf) ++ "\n")
1465 -- -----------------------------------------------------------------------------
1466 -- Handle Properties
1468 -- A number of operations return information about the properties of a
1469 -- handle. Each of these operations returns `True' if the handle has
1470 -- the specified property, and `False' otherwise.
1472 hIsOpen :: Handle -> IO Bool
1474 withHandle_ "hIsOpen" handle $ \ handle_ -> do
1475 case haType handle_ of
1476 ClosedHandle -> return False
1477 SemiClosedHandle -> return False
1480 hIsClosed :: Handle -> IO Bool
1482 withHandle_ "hIsClosed" handle $ \ handle_ -> do
1483 case haType handle_ of
1484 ClosedHandle -> return True
1487 {- not defined, nor exported, but mentioned
1488 here for documentation purposes:
1490 hSemiClosed :: Handle -> IO Bool
1494 return (not (ho || hc))
1497 hIsReadable :: Handle -> IO Bool
1498 hIsReadable (DuplexHandle _ _ _) = return True
1499 hIsReadable handle =
1500 withHandle_ "hIsReadable" handle $ \ handle_ -> do
1501 case haType handle_ of
1502 ClosedHandle -> ioe_closedHandle
1503 SemiClosedHandle -> ioe_closedHandle
1504 htype -> return (isReadableHandleType htype)
1506 hIsWritable :: Handle -> IO Bool
1507 hIsWritable (DuplexHandle _ _ _) = return True
1508 hIsWritable handle =
1509 withHandle_ "hIsWritable" handle $ \ handle_ -> do
1510 case haType handle_ of
1511 ClosedHandle -> ioe_closedHandle
1512 SemiClosedHandle -> ioe_closedHandle
1513 htype -> return (isWritableHandleType htype)
1515 -- | Computation 'hGetBuffering' @hdl@ returns the current buffering mode
1518 hGetBuffering :: Handle -> IO BufferMode
1519 hGetBuffering handle =
1520 withHandle_ "hGetBuffering" handle $ \ handle_ -> do
1521 case haType handle_ of
1522 ClosedHandle -> ioe_closedHandle
1524 -- We're being non-standard here, and allow the buffering
1525 -- of a semi-closed handle to be queried. -- sof 6/98
1526 return (haBufferMode handle_) -- could be stricter..
1528 hIsSeekable :: Handle -> IO Bool
1529 hIsSeekable handle =
1530 withHandle_ "hIsSeekable" handle $ \ handle_ -> do
1531 case haType handle_ of
1532 ClosedHandle -> ioe_closedHandle
1533 SemiClosedHandle -> ioe_closedHandle
1534 AppendHandle -> return False
1535 _ -> do t <- fdType (haFD handle_)
1536 return ((t == RegularFile || t == RawDevice)
1537 && (haIsBin handle_ || tEXT_MODE_SEEK_ALLOWED))
1539 -- -----------------------------------------------------------------------------
1540 -- Changing echo status (Non-standard GHC extensions)
1542 -- | Set the echoing status of a handle connected to a terminal.
1544 hSetEcho :: Handle -> Bool -> IO ()
1545 hSetEcho handle on = do
1546 isT <- hIsTerminalDevice handle
1550 withHandle_ "hSetEcho" handle $ \ handle_ -> do
1551 case haType handle_ of
1552 ClosedHandle -> ioe_closedHandle
1553 _ -> setEcho (haFD handle_) on
1555 -- | Get the echoing status of a handle connected to a terminal.
1557 hGetEcho :: Handle -> IO Bool
1558 hGetEcho handle = do
1559 isT <- hIsTerminalDevice handle
1563 withHandle_ "hGetEcho" handle $ \ handle_ -> do
1564 case haType handle_ of
1565 ClosedHandle -> ioe_closedHandle
1566 _ -> getEcho (haFD handle_)
1568 -- | Is the handle connected to a terminal?
1570 hIsTerminalDevice :: Handle -> IO Bool
1571 hIsTerminalDevice handle = do
1572 withHandle_ "hIsTerminalDevice" handle $ \ handle_ -> do
1573 case haType handle_ of
1574 ClosedHandle -> ioe_closedHandle
1575 _ -> fdIsTTY (haFD handle_)
1577 -- -----------------------------------------------------------------------------
1580 -- | Select binary mode ('True') or text mode ('False') on a open handle.
1581 -- (See also 'openBinaryFile'.)
1583 hSetBinaryMode :: Handle -> Bool -> IO ()
1584 hSetBinaryMode handle bin =
1585 withAllHandles__ "hSetBinaryMode" handle $ \ handle_ ->
1586 do throwErrnoIfMinus1_ "hSetBinaryMode"
1587 (setmode (haFD handle_) bin)
1588 return handle_{haIsBin=bin}
1590 foreign import ccall unsafe "__hscore_setmode"
1591 setmode :: CInt -> Bool -> IO CInt
1593 -- -----------------------------------------------------------------------------
1594 -- Duplicating a Handle
1596 -- | Returns a duplicate of the original handle, with its own buffer.
1597 -- The two Handles will share a file pointer, however. The original
1598 -- handle's buffer is flushed, including discarding any input data,
1599 -- before the handle is duplicated.
1601 hDuplicate :: Handle -> IO Handle
1602 hDuplicate h@(FileHandle path m) = do
1603 new_h_ <- withHandle' "hDuplicate" h m (dupHandle h Nothing)
1604 newFileHandle path (handleFinalizer path) new_h_
1605 hDuplicate h@(DuplexHandle path r w) = do
1606 new_w_ <- withHandle' "hDuplicate" h w (dupHandle h Nothing)
1607 new_w <- newMVar new_w_
1608 new_r_ <- withHandle' "hDuplicate" h r (dupHandle h (Just new_w))
1609 new_r <- newMVar new_r_
1610 addMVarFinalizer new_w (handleFinalizer path new_w)
1611 return (DuplexHandle path new_r new_w)
1613 dupHandle :: Handle -> Maybe (MVar Handle__) -> Handle__
1614 -> IO (Handle__, Handle__)
1615 dupHandle h other_side h_ = do
1616 -- flush the buffer first, so we don't have to copy its contents
1618 new_fd <- case other_side of
1619 Nothing -> throwErrnoIfMinus1 "dupHandle" $ c_dup (haFD h_)
1620 Just r -> withHandle_' "dupHandle" h r (return . haFD)
1621 dupHandle_ other_side h_ new_fd
1623 dupHandleTo other_side hto_ h_ = do
1625 -- Windows' dup2 does not return the new descriptor, unlike Unix
1626 throwErrnoIfMinus1 "dupHandleTo" $
1627 c_dup2 (haFD h_) (haFD hto_)
1628 dupHandle_ other_side h_ (haFD hto_)
1630 dupHandle_ :: Maybe (MVar Handle__) -> Handle__ -> FD
1631 -> IO (Handle__, Handle__)
1632 dupHandle_ other_side h_ new_fd = do
1633 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE (initBufferState (haType h_))
1634 ioref <- newIORef buffer
1635 ioref_buffers <- newIORef BufferListNil
1637 let new_handle_ = h_{ haFD = new_fd,
1639 haBuffers = ioref_buffers,
1640 haOtherSide = other_side }
1641 return (h_, new_handle_)
1643 -- -----------------------------------------------------------------------------
1644 -- Replacing a Handle
1647 Makes the second handle a duplicate of the first handle. The second
1648 handle will be closed first, if it is not already.
1650 This can be used to retarget the standard Handles, for example:
1652 > do h <- openFile "mystdout" WriteMode
1653 > hDuplicateTo h stdout
1656 hDuplicateTo :: Handle -> Handle -> IO ()
1657 hDuplicateTo h1@(FileHandle _ m1) h2@(FileHandle _ m2) = do
1658 withHandle__' "hDuplicateTo" h2 m2 $ \h2_ -> do
1659 _ <- hClose_help h2_
1660 withHandle' "hDuplicateTo" h1 m1 (dupHandleTo Nothing h2_)
1661 hDuplicateTo h1@(DuplexHandle _ r1 w1) h2@(DuplexHandle _ r2 w2) = do
1662 withHandle__' "hDuplicateTo" h2 w2 $ \w2_ -> do
1663 _ <- hClose_help w2_
1664 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo Nothing w2_)
1665 withHandle__' "hDuplicateTo" h2 r2 $ \r2_ -> do
1666 _ <- hClose_help r2_
1667 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo (Just w1) r2_)
1669 ioException (IOError (Just h1) IllegalOperation "hDuplicateTo"
1670 "handles are incompatible" Nothing)
1672 -- ---------------------------------------------------------------------------
1675 -- | 'hShow' is in the 'IO' monad, and gives more comprehensive output
1676 -- than the (pure) instance of 'Show' for 'Handle'.
1678 hShow :: Handle -> IO String
1679 hShow h@(FileHandle path _) = showHandle' path False h
1680 hShow h@(DuplexHandle path _ _) = showHandle' path True h
1682 showHandle' filepath is_duplex h =
1683 withHandle_ "showHandle" h $ \hdl_ ->
1685 showType | is_duplex = showString "duplex (read-write)"
1686 | otherwise = shows (haType hdl_)
1690 showHdl (haType hdl_)
1691 (showString "loc=" . showString filepath . showChar ',' .
1692 showString "type=" . showType . showChar ',' .
1693 showString "binary=" . shows (haIsBin hdl_) . showChar ',' .
1694 showString "buffering=" . showBufMode (unsafePerformIO (readIORef (haBuffer hdl_))) (haBufferMode hdl_) . showString "}" )
1698 showHdl :: HandleType -> ShowS -> ShowS
1701 ClosedHandle -> shows ht . showString "}"
1704 showBufMode :: Buffer -> BufferMode -> ShowS
1705 showBufMode buf bmo =
1707 NoBuffering -> showString "none"
1708 LineBuffering -> showString "line"
1709 BlockBuffering (Just n) -> showString "block " . showParen True (shows n)
1710 BlockBuffering Nothing -> showString "block " . showParen True (shows def)
1715 -- ---------------------------------------------------------------------------
1718 #if defined(DEBUG_DUMP)
1719 puts :: String -> IO ()
1720 puts s = do write_rawBuffer 1 (unsafeCoerce# (packCString# s)) 0 (fromIntegral (length s))
1724 -- -----------------------------------------------------------------------------
1727 throwErrnoIfMinus1RetryOnBlock :: String -> IO CInt -> IO CInt -> IO CInt
1728 throwErrnoIfMinus1RetryOnBlock loc f on_block =
1731 if (res :: CInt) == -1
1735 then throwErrnoIfMinus1RetryOnBlock loc f on_block
1736 else if err == eWOULDBLOCK || err == eAGAIN
1741 -- -----------------------------------------------------------------------------
1742 -- wrappers to platform-specific constants:
1744 foreign import ccall unsafe "__hscore_supportsTextMode"
1745 tEXT_MODE_SEEK_ALLOWED :: Bool
1747 foreign import ccall unsafe "__hscore_bufsiz" dEFAULT_BUFFER_SIZE :: Int
1748 foreign import ccall unsafe "__hscore_seek_cur" sEEK_CUR :: CInt
1749 foreign import ccall unsafe "__hscore_seek_set" sEEK_SET :: CInt
1750 foreign import ccall unsafe "__hscore_seek_end" sEEK_END :: CInt