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 -----------------------------------------------------------------------------
21 withHandle, withHandle', withHandle_,
22 wantWritableHandle, wantReadableHandle, wantSeekableHandle,
24 newEmptyBuffer, allocateBuffer, readCharFromBuffer, writeCharIntoBuffer,
25 flushWriteBufferOnly, flushWriteBuffer, flushReadBuffer,
26 fillReadBuffer, fillReadBufferWithoutBlocking,
27 readRawBuffer, readRawBufferPtr,
28 writeRawBuffer, writeRawBufferPtr,
30 #ifndef mingw32_TARGET_OS
34 ioe_closedHandle, ioe_EOF, ioe_notReadable, ioe_notWritable,
36 stdin, stdout, stderr,
37 IOMode(..), openFile, openBinaryFile, openTempFile, openBinaryTempFile, openFd, fdToHandle,
38 hFileSize, hSetFileSize, hIsEOF, isEOF, hLookAhead, hSetBuffering, hSetBinaryMode,
39 hFlush, hDuplicate, hDuplicateTo,
43 HandlePosition, HandlePosn(..), hGetPosn, hSetPosn,
44 SeekMode(..), hSeek, hTell,
46 hIsOpen, hIsClosed, hIsReadable, hIsWritable, hGetBuffering, hIsSeekable,
47 hSetEcho, hGetEcho, hIsTerminalDevice,
57 #include "ghcconfig.h"
64 import System.IO.Error
65 import System.Posix.Internals
66 import System.FilePath
72 import GHC.Read ( Read )
77 import GHC.Num ( Integer(..), Num(..) )
79 import GHC.Real ( toInteger )
83 -- -----------------------------------------------------------------------------
86 -- hWaitForInput blocks (should use a timeout)
88 -- unbuffered hGetLine is a bit dodgy
90 -- hSetBuffering: can't change buffering on a stream,
91 -- when the read buffer is non-empty? (no way to flush the buffer)
93 -- ---------------------------------------------------------------------------
94 -- Are files opened by default in text or binary mode, if the user doesn't
97 dEFAULT_OPEN_IN_BINARY_MODE = False :: Bool
99 -- ---------------------------------------------------------------------------
100 -- Creating a new handle
102 newFileHandle :: FilePath -> (MVar Handle__ -> IO ()) -> Handle__ -> IO Handle
103 newFileHandle filepath finalizer hc = do
105 addMVarFinalizer m (finalizer m)
106 return (FileHandle filepath m)
108 -- ---------------------------------------------------------------------------
109 -- Working with Handles
112 In the concurrent world, handles are locked during use. This is done
113 by wrapping an MVar around the handle which acts as a mutex over
114 operations on the handle.
116 To avoid races, we use the following bracketing operations. The idea
117 is to obtain the lock, do some operation and replace the lock again,
118 whether the operation succeeded or failed. We also want to handle the
119 case where the thread receives an exception while processing the IO
120 operation: in these cases we also want to relinquish the lock.
122 There are three versions of @withHandle@: corresponding to the three
123 possible combinations of:
125 - the operation may side-effect the handle
126 - the operation may return a result
128 If the operation generates an error or an exception is raised, the
129 original handle is always replaced [ this is the case at the moment,
130 but we might want to revisit this in the future --SDM ].
133 {-# INLINE withHandle #-}
134 withHandle :: String -> Handle -> (Handle__ -> IO (Handle__,a)) -> IO a
135 withHandle fun h@(FileHandle _ m) act = withHandle' fun h m act
136 withHandle fun h@(DuplexHandle _ m _) act = withHandle' fun h m act
138 withHandle' :: String -> Handle -> MVar Handle__
139 -> (Handle__ -> IO (Handle__,a)) -> IO a
140 withHandle' fun h m act =
143 checkBufferInvariants h_
144 (h',v) <- catchException (act h_)
145 (\ err -> putMVar m h_ >>
147 IOException ex -> ioError (augmentIOError ex fun h)
149 checkBufferInvariants h'
153 {-# INLINE withHandle_ #-}
154 withHandle_ :: String -> Handle -> (Handle__ -> IO a) -> IO a
155 withHandle_ fun h@(FileHandle _ m) act = withHandle_' fun h m act
156 withHandle_ fun h@(DuplexHandle _ m _) act = withHandle_' fun h m act
158 withHandle_' fun h m act =
161 checkBufferInvariants h_
162 v <- catchException (act h_)
163 (\ err -> putMVar m h_ >>
165 IOException ex -> ioError (augmentIOError ex fun h)
167 checkBufferInvariants h_
171 withAllHandles__ :: String -> Handle -> (Handle__ -> IO Handle__) -> IO ()
172 withAllHandles__ fun h@(FileHandle _ m) act = withHandle__' fun h m act
173 withAllHandles__ fun h@(DuplexHandle _ r w) act = do
174 withHandle__' fun h r act
175 withHandle__' fun h w act
177 withHandle__' fun h m act =
180 checkBufferInvariants h_
181 h' <- catchException (act h_)
182 (\ err -> putMVar m h_ >>
184 IOException ex -> ioError (augmentIOError ex fun h)
186 checkBufferInvariants h'
190 augmentIOError (IOError _ iot _ str fp) fun h
191 = IOError (Just h) iot fun str filepath
194 | otherwise = case h of
195 FileHandle fp _ -> Just fp
196 DuplexHandle fp _ _ -> Just fp
198 -- ---------------------------------------------------------------------------
199 -- Wrapper for write operations.
201 wantWritableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
202 wantWritableHandle fun h@(FileHandle _ m) act
203 = wantWritableHandle' fun h m act
204 wantWritableHandle fun h@(DuplexHandle _ _ m) act
205 = wantWritableHandle' fun h m act
206 -- ToDo: in the Duplex case, we don't need to checkWritableHandle
209 :: String -> Handle -> MVar Handle__
210 -> (Handle__ -> IO a) -> IO a
211 wantWritableHandle' fun h m act
212 = withHandle_' fun h m (checkWritableHandle act)
214 checkWritableHandle act handle_
215 = case haType handle_ of
216 ClosedHandle -> ioe_closedHandle
217 SemiClosedHandle -> ioe_closedHandle
218 ReadHandle -> ioe_notWritable
219 ReadWriteHandle -> do
220 let ref = haBuffer handle_
223 if not (bufferIsWritable buf)
224 then do b <- flushReadBuffer (haFD handle_) buf
225 return b{ bufState=WriteBuffer }
227 writeIORef ref new_buf
229 _other -> act handle_
231 -- ---------------------------------------------------------------------------
232 -- Wrapper for read operations.
234 wantReadableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
235 wantReadableHandle fun h@(FileHandle _ m) act
236 = wantReadableHandle' fun h m act
237 wantReadableHandle fun h@(DuplexHandle _ m _) act
238 = wantReadableHandle' fun h m act
239 -- ToDo: in the Duplex case, we don't need to checkReadableHandle
242 :: String -> Handle -> MVar Handle__
243 -> (Handle__ -> IO a) -> IO a
244 wantReadableHandle' fun h m act
245 = withHandle_' fun h m (checkReadableHandle act)
247 checkReadableHandle act handle_ =
248 case haType handle_ of
249 ClosedHandle -> ioe_closedHandle
250 SemiClosedHandle -> ioe_closedHandle
251 AppendHandle -> ioe_notReadable
252 WriteHandle -> ioe_notReadable
253 ReadWriteHandle -> do
254 let ref = haBuffer handle_
256 when (bufferIsWritable buf) $ do
257 new_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
258 writeIORef ref new_buf{ bufState=ReadBuffer }
260 _other -> act handle_
262 -- ---------------------------------------------------------------------------
263 -- Wrapper for seek operations.
265 wantSeekableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
266 wantSeekableHandle fun h@(DuplexHandle _ _ _) _act =
267 ioException (IOError (Just h) IllegalOperation fun
268 "handle is not seekable" Nothing)
269 wantSeekableHandle fun h@(FileHandle _ m) act =
270 withHandle_' fun h m (checkSeekableHandle act)
272 checkSeekableHandle act handle_ =
273 case haType handle_ of
274 ClosedHandle -> ioe_closedHandle
275 SemiClosedHandle -> ioe_closedHandle
276 AppendHandle -> ioe_notSeekable
277 _ | haIsBin handle_ || tEXT_MODE_SEEK_ALLOWED -> act handle_
278 | otherwise -> ioe_notSeekable_notBin
280 -- -----------------------------------------------------------------------------
283 ioe_closedHandle, ioe_EOF,
284 ioe_notReadable, ioe_notWritable,
285 ioe_notSeekable, ioe_notSeekable_notBin :: IO a
287 ioe_closedHandle = ioException
288 (IOError Nothing IllegalOperation ""
289 "handle is closed" Nothing)
290 ioe_EOF = ioException
291 (IOError Nothing EOF "" "" Nothing)
292 ioe_notReadable = ioException
293 (IOError Nothing IllegalOperation ""
294 "handle is not open for reading" Nothing)
295 ioe_notWritable = ioException
296 (IOError Nothing IllegalOperation ""
297 "handle is not open for writing" Nothing)
298 ioe_notSeekable = ioException
299 (IOError Nothing IllegalOperation ""
300 "handle is not seekable" Nothing)
301 ioe_notSeekable_notBin = ioException
302 (IOError Nothing IllegalOperation ""
303 "seek operations on text-mode handles are not allowed on this platform"
306 ioe_finalizedHandle fp = throw (IOException
307 (IOError Nothing IllegalOperation ""
308 "handle is finalized" (Just fp)))
310 ioe_bufsiz :: Int -> IO a
311 ioe_bufsiz n = ioException
312 (IOError Nothing InvalidArgument "hSetBuffering"
313 ("illegal buffer size " ++ showsPrec 9 n []) Nothing)
314 -- 9 => should be parens'ified.
316 -- -----------------------------------------------------------------------------
319 -- For a duplex handle, we arrange that the read side points to the write side
320 -- (and hence keeps it alive if the read side is alive). This is done by
321 -- having the haOtherSide field of the read side point to the read side.
322 -- The finalizer is then placed on the write side, and the handle only gets
323 -- finalized once, when both sides are no longer required.
325 -- NOTE about finalized handles: It's possible that a handle can be
326 -- finalized and then we try to use it later, for example if the
327 -- handle is referenced from another finalizer, or from a thread that
328 -- has become unreferenced and then resurrected (arguably in the
329 -- latter case we shouldn't finalize the Handle...). Anyway,
330 -- we try to emit a helpful message which is better than nothing.
332 stdHandleFinalizer :: FilePath -> MVar Handle__ -> IO ()
333 stdHandleFinalizer fp m = do
335 flushWriteBufferOnly h_
336 putMVar m (ioe_finalizedHandle fp)
338 handleFinalizer :: FilePath -> MVar Handle__ -> IO ()
339 handleFinalizer fp m = do
340 handle_ <- takeMVar m
341 case haType handle_ of
342 ClosedHandle -> return ()
343 _ -> do flushWriteBufferOnly handle_ `catchException` \_ -> return ()
344 -- ignore errors and async exceptions, and close the
345 -- descriptor anyway...
346 hClose_handle_ handle_
348 putMVar m (ioe_finalizedHandle fp)
350 -- ---------------------------------------------------------------------------
351 -- Grimy buffer operations
354 checkBufferInvariants h_ = do
355 let ref = haBuffer h_
356 Buffer{ bufWPtr=w, bufRPtr=r, bufSize=size, bufState=state } <- readIORef ref
361 && ( r /= w || (r == 0 && w == 0) )
362 && ( state /= WriteBuffer || r == 0 )
363 && ( state /= WriteBuffer || w < size ) -- write buffer is never full
365 then error "buffer invariant violation"
368 checkBufferInvariants h_ = return ()
371 newEmptyBuffer :: RawBuffer -> BufferState -> Int -> Buffer
372 newEmptyBuffer b state size
373 = Buffer{ bufBuf=b, bufRPtr=0, bufWPtr=0, bufSize=size, bufState=state }
375 allocateBuffer :: Int -> BufferState -> IO Buffer
376 allocateBuffer sz@(I# size) state = IO $ \s ->
377 #ifdef mingw32_TARGET_OS
378 -- To implement asynchronous I/O under Win32, we have to pass
379 -- buffer references to external threads that handles the
380 -- filling/emptying of their contents. Hence, the buffer cannot
381 -- be moved around by the GC.
382 case newPinnedByteArray# size s of { (# s, b #) ->
384 case newByteArray# size s of { (# s, b #) ->
386 (# s, newEmptyBuffer b state sz #) }
388 writeCharIntoBuffer :: RawBuffer -> Int -> Char -> IO Int
389 writeCharIntoBuffer slab (I# off) (C# c)
390 = IO $ \s -> case writeCharArray# slab off c s of
391 s -> (# s, I# (off +# 1#) #)
393 readCharFromBuffer :: RawBuffer -> Int -> IO (Char, Int)
394 readCharFromBuffer slab (I# off)
395 = IO $ \s -> case readCharArray# slab off s of
396 (# s, c #) -> (# s, (C# c, I# (off +# 1#)) #)
398 getBuffer :: FD -> BufferState -> IO (IORef Buffer, BufferMode)
399 getBuffer fd state = do
400 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE state
401 ioref <- newIORef buffer
405 | is_tty = LineBuffering
406 | otherwise = BlockBuffering Nothing
408 return (ioref, buffer_mode)
410 mkUnBuffer :: IO (IORef Buffer)
412 buffer <- allocateBuffer 1 ReadBuffer
415 -- flushWriteBufferOnly flushes the buffer iff it contains pending write data.
416 flushWriteBufferOnly :: Handle__ -> IO ()
417 flushWriteBufferOnly h_ = do
421 new_buf <- if bufferIsWritable buf
422 then flushWriteBuffer fd (haIsStream h_) buf
424 writeIORef ref new_buf
426 -- flushBuffer syncs the file with the buffer, including moving the
427 -- file pointer backwards in the case of a read buffer.
428 flushBuffer :: Handle__ -> IO ()
430 let ref = haBuffer h_
435 ReadBuffer -> flushReadBuffer (haFD h_) buf
436 WriteBuffer -> flushWriteBuffer (haFD h_) (haIsStream h_) buf
438 writeIORef ref flushed_buf
440 -- When flushing a read buffer, we seek backwards by the number of
441 -- characters in the buffer. The file descriptor must therefore be
442 -- seekable: attempting to flush the read buffer on an unseekable
443 -- handle is not allowed.
445 flushReadBuffer :: FD -> Buffer -> IO Buffer
446 flushReadBuffer fd buf
447 | bufferEmpty buf = return buf
449 let off = negate (bufWPtr buf - bufRPtr buf)
451 puts ("flushReadBuffer: new file offset = " ++ show off ++ "\n")
453 throwErrnoIfMinus1Retry "flushReadBuffer"
454 (c_lseek (fromIntegral fd) (fromIntegral off) sEEK_CUR)
455 return buf{ bufWPtr=0, bufRPtr=0 }
457 flushWriteBuffer :: FD -> Bool -> Buffer -> IO Buffer
458 flushWriteBuffer fd is_stream buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w } =
459 seq fd $ do -- strictness hack
462 puts ("flushWriteBuffer, fd=" ++ show fd ++ ", bytes=" ++ show bytes ++ "\n")
465 then return (buf{ bufRPtr=0, bufWPtr=0 })
467 res <- writeRawBuffer "flushWriteBuffer" (fromIntegral fd) is_stream b
468 (fromIntegral r) (fromIntegral bytes)
469 let res' = fromIntegral res
471 then flushWriteBuffer fd is_stream (buf{ bufRPtr = r + res' })
472 else return buf{ bufRPtr=0, bufWPtr=0 }
474 fillReadBuffer :: FD -> Bool -> Bool -> Buffer -> IO Buffer
475 fillReadBuffer fd is_line is_stream
476 buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w, bufSize=size } =
477 -- buffer better be empty:
478 assert (r == 0 && w == 0) $ do
479 fillReadBufferLoop fd is_line is_stream buf b w size
481 -- For a line buffer, we just get the first chunk of data to arrive,
482 -- and don't wait for the whole buffer to be full (but we *do* wait
483 -- until some data arrives). This isn't really line buffering, but it
484 -- appears to be what GHC has done for a long time, and I suspect it
485 -- is more useful than line buffering in most cases.
487 fillReadBufferLoop fd is_line is_stream buf b w size = do
489 if bytes == 0 -- buffer full?
490 then return buf{ bufRPtr=0, bufWPtr=w }
493 puts ("fillReadBufferLoop: bytes = " ++ show bytes ++ "\n")
495 res <- readRawBuffer "fillReadBuffer" fd is_stream b
496 (fromIntegral w) (fromIntegral bytes)
497 let res' = fromIntegral res
499 puts ("fillReadBufferLoop: res' = " ++ show res' ++ "\n")
504 else return buf{ bufRPtr=0, bufWPtr=w }
505 else if res' < bytes && not is_line
506 then fillReadBufferLoop fd is_line is_stream buf b (w+res') size
507 else return buf{ bufRPtr=0, bufWPtr=w+res' }
510 fillReadBufferWithoutBlocking :: FD -> Bool -> Buffer -> IO Buffer
511 fillReadBufferWithoutBlocking fd is_stream
512 buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w, bufSize=size } =
513 -- buffer better be empty:
514 assert (r == 0 && w == 0) $ do
516 puts ("fillReadBufferLoopNoBlock: bytes = " ++ show bytes ++ "\n")
518 res <- readRawBufferNoBlock "fillReadBuffer" fd is_stream b
519 0 (fromIntegral size)
520 let res' = fromIntegral res
522 puts ("fillReadBufferLoopNoBlock: res' = " ++ show res' ++ "\n")
524 return buf{ bufRPtr=0, bufWPtr=res' }
526 -- Low level routines for reading/writing to (raw)buffers:
528 #ifndef mingw32_TARGET_OS
529 readRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
530 readRawBuffer loc fd is_stream buf off len =
531 throwErrnoIfMinus1RetryMayBlock loc
532 (read_rawBuffer fd buf off len)
533 (threadWaitRead (fromIntegral fd))
535 readRawBufferNoBlock :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
536 readRawBufferNoBlock loc fd is_stream buf off len =
537 throwErrnoIfMinus1RetryOnBlock loc
538 (read_rawBuffer fd buf off len)
541 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
542 readRawBufferPtr loc fd is_stream buf off len =
543 throwErrnoIfMinus1RetryMayBlock loc
544 (read_off fd buf off len)
545 (threadWaitRead (fromIntegral fd))
547 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
548 writeRawBuffer loc fd is_stream buf off len =
549 throwErrnoIfMinus1RetryMayBlock loc
550 (write_rawBuffer (fromIntegral fd) buf off len)
551 (threadWaitWrite (fromIntegral fd))
553 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
554 writeRawBufferPtr loc fd is_stream buf off len =
555 throwErrnoIfMinus1RetryMayBlock loc
556 (write_off (fromIntegral fd) buf off len)
557 (threadWaitWrite (fromIntegral fd))
559 foreign import ccall unsafe "__hscore_PrelHandle_read"
560 read_rawBuffer :: FD -> RawBuffer -> Int -> CInt -> IO CInt
562 foreign import ccall unsafe "__hscore_PrelHandle_read"
563 read_off :: FD -> Ptr CChar -> Int -> CInt -> IO CInt
565 foreign import ccall unsafe "__hscore_PrelHandle_write"
566 write_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
568 foreign import ccall unsafe "__hscore_PrelHandle_write"
569 write_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
571 #else /* mingw32_TARGET_OS.... */
573 readRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
574 readRawBuffer loc fd is_stream buf off len
575 | threaded = blockingReadRawBuffer loc fd is_stream buf off len
576 | otherwise = asyncReadRawBuffer loc fd is_stream buf off len
578 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
579 readRawBufferPtr loc fd is_stream buf off len
580 | threaded = blockingReadRawBufferPtr loc fd is_stream buf off len
581 | otherwise = asyncReadRawBufferPtr loc fd is_stream buf off len
583 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
584 writeRawBuffer loc fd is_stream buf off len
585 | threaded = blockingWriteRawBuffer loc fd is_stream buf off len
586 | otherwise = asyncWriteRawBuffer loc fd is_stream buf off len
588 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
589 writeRawBufferPtr loc fd is_stream buf off len
590 | threaded = blockingWriteRawBufferPtr loc fd is_stream buf off len
591 | otherwise = asyncWriteRawBufferPtr loc fd is_stream buf off len
593 -- ToDo: we don't have a non-blocking primitve read on Win32
594 readRawBufferNoBlock :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
595 readRawBufferNoBlock = readRawBufferNoBlock
597 -- Async versions of the read/write primitives, for the non-threaded RTS
599 asyncReadRawBuffer loc fd is_stream buf off len = do
600 (l, rc) <- asyncReadBA fd (if is_stream then 1 else 0)
601 (fromIntegral len) off buf
604 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
605 else return (fromIntegral l)
607 asyncReadRawBufferPtr loc fd is_stream buf off len = do
608 (l, rc) <- asyncRead fd (if is_stream then 1 else 0)
609 (fromIntegral len) (buf `plusPtr` off)
612 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
613 else return (fromIntegral l)
615 asyncWriteRawBuffer loc fd is_stream buf off len = do
616 (l, rc) <- asyncWriteBA fd (if is_stream then 1 else 0)
617 (fromIntegral len) off buf
620 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
621 else return (fromIntegral l)
623 asyncWriteRawBufferPtr loc fd is_stream buf off len = do
624 (l, rc) <- asyncWrite fd (if is_stream then 1 else 0)
625 (fromIntegral len) (buf `plusPtr` off)
628 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
629 else return (fromIntegral l)
631 -- Blocking versions of the read/write primitives, for the threaded RTS
633 blockingReadRawBuffer loc fd True buf off len =
634 throwErrnoIfMinus1Retry loc $
635 recv_rawBuffer fd buf off len
636 blockingReadRawBuffer loc fd False buf off len =
637 throwErrnoIfMinus1Retry loc $
638 read_rawBuffer fd buf off len
640 blockingReadRawBufferPtr loc fd True buf off len =
641 throwErrnoIfMinus1Retry loc $
642 recv_off fd buf off len
643 blockingReadRawBufferPtr loc fd False buf off len =
644 throwErrnoIfMinus1Retry loc $
645 read_off fd buf off len
647 blockingWriteRawBuffer loc fd True buf off len =
648 throwErrnoIfMinus1Retry loc $
649 send_rawBuffer (fromIntegral fd) buf off len
650 blockingWriteRawBuffer loc fd False buf off len =
651 throwErrnoIfMinus1Retry loc $
652 write_rawBuffer (fromIntegral fd) buf off len
654 blockingWriteRawBufferPtr loc fd True buf off len =
655 throwErrnoIfMinus1Retry loc $
656 send_off (fromIntegral fd) buf off len
657 blockingWriteRawBufferPtr loc fd False buf off len =
658 throwErrnoIfMinus1Retry loc $
659 write_off (fromIntegral fd) buf off len
661 -- NOTE: "safe" versions of the read/write calls for use by the threaded RTS.
662 -- These calls may block, but that's ok.
664 foreign import ccall safe "__hscore_PrelHandle_read"
665 read_rawBuffer :: FD -> RawBuffer -> Int -> CInt -> IO CInt
667 foreign import ccall safe "__hscore_PrelHandle_read"
668 read_off :: FD -> Ptr CChar -> Int -> CInt -> IO CInt
670 foreign import ccall safe "__hscore_PrelHandle_write"
671 write_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
673 foreign import ccall safe "__hscore_PrelHandle_write"
674 write_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
676 foreign import ccall safe "__hscore_PrelHandle_recv"
677 recv_rawBuffer :: FD -> RawBuffer -> Int -> CInt -> IO CInt
679 foreign import ccall safe "__hscore_PrelHandle_recv"
680 recv_off :: FD -> Ptr CChar -> Int -> CInt -> IO CInt
682 foreign import ccall safe "__hscore_PrelHandle_send"
683 send_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
685 foreign import ccall safe "__hscore_PrelHandle_send"
686 send_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
688 foreign import ccall "rtsSupportsBoundThreads" threaded :: Bool
691 -- ---------------------------------------------------------------------------
694 -- Three handles are allocated during program initialisation. The first
695 -- two manage input or output from the Haskell program's standard input
696 -- or output channel respectively. The third manages output to the
697 -- standard error channel. These handles are initially open.
703 -- | A handle managing input from the Haskell program's standard input channel.
705 stdin = unsafePerformIO $ do
706 -- ToDo: acquire lock
707 setNonBlockingFD fd_stdin
708 (buf, bmode) <- getBuffer fd_stdin ReadBuffer
709 mkStdHandle fd_stdin "<stdin>" ReadHandle buf bmode
711 -- | A handle managing output to the Haskell program's standard output channel.
713 stdout = unsafePerformIO $ do
714 -- ToDo: acquire lock
715 -- We don't set non-blocking mode on stdout or sterr, because
716 -- some shells don't recover properly.
717 -- setNonBlockingFD fd_stdout
718 (buf, bmode) <- getBuffer fd_stdout WriteBuffer
719 mkStdHandle fd_stdout "<stdout>" WriteHandle buf bmode
721 -- | A handle managing output to the Haskell program's standard error channel.
723 stderr = unsafePerformIO $ do
724 -- ToDo: acquire lock
725 -- We don't set non-blocking mode on stdout or sterr, because
726 -- some shells don't recover properly.
727 -- setNonBlockingFD fd_stderr
729 mkStdHandle fd_stderr "<stderr>" WriteHandle buf NoBuffering
731 -- ---------------------------------------------------------------------------
732 -- Opening and Closing Files
734 addFilePathToIOError fun fp (IOError h iot _ str _)
735 = IOError h iot fun str (Just fp)
737 -- | Computation 'openFile' @file mode@ allocates and returns a new, open
738 -- handle to manage the file @file@. It manages input if @mode@
739 -- is 'ReadMode', output if @mode@ is 'WriteMode' or 'AppendMode',
740 -- and both input and output if mode is 'ReadWriteMode'.
742 -- If the file does not exist and it is opened for output, it should be
743 -- created as a new file. If @mode@ is 'WriteMode' and the file
744 -- already exists, then it should be truncated to zero length.
745 -- Some operating systems delete empty files, so there is no guarantee
746 -- that the file will exist following an 'openFile' with @mode@
747 -- 'WriteMode' unless it is subsequently written to successfully.
748 -- The handle is positioned at the end of the file if @mode@ is
749 -- 'AppendMode', and otherwise at the beginning (in which case its
750 -- internal position is 0).
751 -- The initial buffer mode is implementation-dependent.
753 -- This operation may fail with:
755 -- * 'isAlreadyInUseError' if the file is already open and cannot be reopened;
757 -- * 'isDoesNotExistError' if the file does not exist; or
759 -- * 'isPermissionError' if the user does not have permission to open the file.
761 -- Note: if you will be working with files containing binary data, you'll want to
762 -- be using 'openBinaryFile'.
763 openFile :: FilePath -> IOMode -> IO Handle
766 (openFile' fp im dEFAULT_OPEN_IN_BINARY_MODE)
767 (\e -> ioError (addFilePathToIOError "openFile" fp e))
769 -- | Like 'openFile', but open the file in binary mode.
770 -- On Windows, reading a file in text mode (which is the default)
771 -- will translate CRLF to LF, and writing will translate LF to CRLF.
772 -- This is usually what you want with text files. With binary files
773 -- this is undesirable; also, as usual under Microsoft operating systems,
774 -- text mode treats control-Z as EOF. Binary mode turns off all special
775 -- treatment of end-of-line and end-of-file characters.
776 -- (See also 'hSetBinaryMode'.)
778 openBinaryFile :: FilePath -> IOMode -> IO Handle
779 openBinaryFile fp m =
781 (openFile' fp m True)
782 (\e -> ioError (addFilePathToIOError "openBinaryFile" fp e))
784 openFile' filepath mode binary =
785 withCString filepath $ \ f ->
788 oflags1 = case mode of
789 ReadMode -> read_flags
790 #ifdef mingw32_TARGET_OS
791 WriteMode -> write_flags .|. o_TRUNC
793 WriteMode -> write_flags
795 ReadWriteMode -> rw_flags
796 AppendMode -> append_flags
802 oflags = oflags1 .|. binary_flags
805 -- the old implementation had a complicated series of three opens,
806 -- which is perhaps because we have to be careful not to open
807 -- directories. However, the man pages I've read say that open()
808 -- always returns EISDIR if the file is a directory and was opened
809 -- for writing, so I think we're ok with a single open() here...
810 fd <- fromIntegral `liftM`
811 throwErrnoIfMinus1Retry "openFile"
812 (c_open f (fromIntegral oflags) 0o666)
814 h <- openFd fd Nothing False filepath mode binary
815 `catchException` \e -> do c_close (fromIntegral fd); throw e
816 -- NB. don't forget to close the FD if openFd fails, otherwise
818 -- ASSERT: if we just created the file, then openFd won't fail
819 -- (so we don't need to worry about removing the newly created file
820 -- in the event of an error).
821 #ifndef mingw32_TARGET_OS
823 then throwErrnoIf (/=0) "openFile"
824 (c_ftruncate (fromIntegral fd) 0)
830 -- | The function creates a temporary file in ReadWrite mode.
831 -- The created file isn\'t deleted automatically, so you need to delete it manually.
832 openTempFile :: FilePath -- ^ Directory in which to create the file
833 -> String -- ^ File name template. If the template is \"foo.ext\" then
834 -- the create file will be \"fooXXX.ext\" where XXX is some
836 -> IO (FilePath, Handle)
837 openTempFile tmp_dir template = openTempFile' "openTempFile" tmp_dir template dEFAULT_OPEN_IN_BINARY_MODE
839 -- | Like 'openTempFile', but opens the file in binary mode. See 'openBinaryFile' for more comments.
840 openBinaryTempFile :: FilePath -> String -> IO (FilePath, Handle)
841 openBinaryTempFile tmp_dir template = openTempFile' "openBinaryTempFile" tmp_dir template True
843 openTempFile' :: String -> FilePath -> String -> Bool -> IO (FilePath, Handle)
844 openTempFile' loc tmp_dir template binary = do
848 (prefix,suffix) = break (=='.') template
850 oflags1 = rw_flags .|. o_EXCL
856 oflags = oflags1 .|. binary_flags
859 fd <- withCString filepath $ \ f ->
860 c_open f oflags 0o666
865 then findTempName (x+1)
866 else ioError (errnoToIOError loc errno Nothing (Just tmp_dir))
868 h <- openFd (fromIntegral fd) Nothing False filepath ReadWriteMode True
869 `catchException` \e -> do c_close (fromIntegral fd); throw e
872 filename = prefix ++ show x ++ suffix
873 filepath = tmp_dir `joinFileName` filename
876 std_flags = o_NONBLOCK .|. o_NOCTTY
877 output_flags = std_flags .|. o_CREAT
878 read_flags = std_flags .|. o_RDONLY
879 write_flags = output_flags .|. o_WRONLY
880 rw_flags = output_flags .|. o_RDWR
881 append_flags = write_flags .|. o_APPEND
883 -- ---------------------------------------------------------------------------
886 openFd :: FD -> Maybe FDType -> Bool -> FilePath -> IOMode -> Bool -> IO Handle
887 openFd fd mb_fd_type is_socket filepath mode binary = do
888 -- turn on non-blocking mode
891 let (ha_type, write) =
893 ReadMode -> ( ReadHandle, False )
894 WriteMode -> ( WriteHandle, True )
895 ReadWriteMode -> ( ReadWriteHandle, True )
896 AppendMode -> ( AppendHandle, True )
898 -- open() won't tell us if it was a directory if we only opened for
899 -- reading, so check again.
907 ioException (IOError Nothing InappropriateType "openFile"
908 "is a directory" Nothing)
911 | ReadWriteHandle <- ha_type -> mkDuplexHandle fd is_socket filepath binary
912 | otherwise -> mkFileHandle fd is_socket filepath ha_type binary
914 -- regular files need to be locked
916 #ifndef mingw32_TARGET_OS
917 r <- lockFile (fromIntegral fd) (fromBool write) 1{-exclusive-}
919 ioException (IOError Nothing ResourceBusy "openFile"
920 "file is locked" Nothing)
922 mkFileHandle fd is_socket filepath ha_type binary
925 fdToHandle :: FD -> IO Handle
928 let fd_str = "<file descriptor: " ++ show fd ++ ">"
929 openFd fd Nothing False{-XXX!-} fd_str mode True{-bin mode-}
932 #ifndef mingw32_TARGET_OS
933 foreign import ccall unsafe "lockFile"
934 lockFile :: CInt -> CInt -> CInt -> IO CInt
936 foreign import ccall unsafe "unlockFile"
937 unlockFile :: CInt -> IO CInt
940 mkStdHandle :: FD -> FilePath -> HandleType -> IORef Buffer -> BufferMode
942 mkStdHandle fd filepath ha_type buf bmode = do
943 spares <- newIORef BufferListNil
944 newFileHandle filepath (stdHandleFinalizer filepath)
945 (Handle__ { haFD = fd,
947 haIsBin = dEFAULT_OPEN_IN_BINARY_MODE,
949 haBufferMode = bmode,
952 haOtherSide = Nothing
955 mkFileHandle :: FD -> Bool -> FilePath -> HandleType -> Bool -> IO Handle
956 mkFileHandle fd is_stream filepath ha_type binary = do
957 (buf, bmode) <- getBuffer fd (initBufferState ha_type)
958 spares <- newIORef BufferListNil
959 newFileHandle filepath (handleFinalizer filepath)
960 (Handle__ { haFD = fd,
963 haIsStream = is_stream,
964 haBufferMode = bmode,
967 haOtherSide = Nothing
970 mkDuplexHandle :: FD -> Bool -> FilePath -> Bool -> IO Handle
971 mkDuplexHandle fd is_stream filepath binary = do
972 (w_buf, w_bmode) <- getBuffer fd WriteBuffer
973 w_spares <- newIORef BufferListNil
975 Handle__ { haFD = fd,
976 haType = WriteHandle,
978 haIsStream = is_stream,
979 haBufferMode = w_bmode,
981 haBuffers = w_spares,
982 haOtherSide = Nothing
984 write_side <- newMVar w_handle_
986 (r_buf, r_bmode) <- getBuffer fd ReadBuffer
987 r_spares <- newIORef BufferListNil
989 Handle__ { haFD = fd,
992 haIsStream = is_stream,
993 haBufferMode = r_bmode,
995 haBuffers = r_spares,
996 haOtherSide = Just write_side
998 read_side <- newMVar r_handle_
1000 addMVarFinalizer write_side (handleFinalizer filepath write_side)
1001 return (DuplexHandle filepath read_side write_side)
1004 initBufferState ReadHandle = ReadBuffer
1005 initBufferState _ = WriteBuffer
1007 -- ---------------------------------------------------------------------------
1010 -- | Computation 'hClose' @hdl@ makes handle @hdl@ closed. Before the
1011 -- computation finishes, if @hdl@ is writable its buffer is flushed as
1013 -- Performing 'hClose' on a handle that has already been closed has no effect;
1014 -- doing so not an error. All other operations on a closed handle will fail.
1015 -- If 'hClose' fails for any reason, any further operations (apart from
1016 -- 'hClose') on the handle will still fail as if @hdl@ had been successfully
1019 hClose :: Handle -> IO ()
1020 hClose h@(FileHandle _ m) = hClose' h m
1021 hClose h@(DuplexHandle _ r w) = hClose' h w >> hClose' h r
1023 hClose' h m = withHandle__' "hClose" h m $ hClose_help
1025 -- hClose_help is also called by lazyRead (in PrelIO) when EOF is read
1026 -- or an IO error occurs on a lazy stream. The semi-closed Handle is
1027 -- then closed immediately. We have to be careful with DuplexHandles
1028 -- though: we have to leave the closing to the finalizer in that case,
1029 -- because the write side may still be in use.
1030 hClose_help :: Handle__ -> IO Handle__
1031 hClose_help handle_ =
1032 case haType handle_ of
1033 ClosedHandle -> return handle_
1034 _ -> do flushWriteBufferOnly handle_ -- interruptible
1035 hClose_handle_ handle_
1037 hClose_handle_ handle_ = do
1038 let fd = haFD handle_
1039 c_fd = fromIntegral fd
1041 -- close the file descriptor, but not when this is the read
1042 -- side of a duplex handle, and not when this is one of the
1043 -- std file handles.
1044 case haOtherSide handle_ of
1046 when (fd /= fd_stdin && fd /= fd_stdout && fd /= fd_stderr) $
1047 throwErrnoIfMinus1Retry_ "hClose"
1048 #ifdef mingw32_TARGET_OS
1049 (closeFd (haIsStream handle_) c_fd)
1055 -- free the spare buffers
1056 writeIORef (haBuffers handle_) BufferListNil
1058 #ifndef mingw32_TARGET_OS
1063 -- we must set the fd to -1, because the finalizer is going
1064 -- to run eventually and try to close/unlock it.
1065 return (handle_{ haFD = -1,
1066 haType = ClosedHandle
1069 -----------------------------------------------------------------------------
1070 -- Detecting and changing the size of a file
1072 -- | For a handle @hdl@ which attached to a physical file,
1073 -- 'hFileSize' @hdl@ returns the size of that file in 8-bit bytes.
1075 hFileSize :: Handle -> IO Integer
1077 withHandle_ "hFileSize" handle $ \ handle_ -> do
1078 case haType handle_ of
1079 ClosedHandle -> ioe_closedHandle
1080 SemiClosedHandle -> ioe_closedHandle
1081 _ -> do flushWriteBufferOnly handle_
1082 r <- fdFileSize (haFD handle_)
1085 else ioException (IOError Nothing InappropriateType "hFileSize"
1086 "not a regular file" Nothing)
1089 -- | 'hSetFileSize' @hdl@ @size@ truncates the physical file with handle @hdl@ to @size@ bytes.
1091 hSetFileSize :: Handle -> Integer -> IO ()
1092 hSetFileSize handle size =
1093 withHandle_ "hSetFileSize" handle $ \ handle_ -> do
1094 case haType handle_ of
1095 ClosedHandle -> ioe_closedHandle
1096 SemiClosedHandle -> ioe_closedHandle
1097 _ -> do flushWriteBufferOnly handle_
1098 throwErrnoIf (/=0) "hSetFileSize"
1099 (c_ftruncate (fromIntegral (haFD handle_)) (fromIntegral size))
1102 -- ---------------------------------------------------------------------------
1103 -- Detecting the End of Input
1105 -- | For a readable handle @hdl@, 'hIsEOF' @hdl@ returns
1106 -- 'True' if no further input can be taken from @hdl@ or for a
1107 -- physical file, if the current I\/O position is equal to the length of
1108 -- the file. Otherwise, it returns 'False'.
1110 hIsEOF :: Handle -> IO Bool
1113 (do hLookAhead handle; return False)
1114 (\e -> if isEOFError e then return True else ioError e)
1116 -- | The computation 'isEOF' is identical to 'hIsEOF',
1117 -- except that it works only on 'stdin'.
1120 isEOF = hIsEOF stdin
1122 -- ---------------------------------------------------------------------------
1125 -- | Computation 'hLookAhead' returns the next character from the handle
1126 -- without removing it from the input buffer, blocking until a character
1129 -- This operation may fail with:
1131 -- * 'isEOFError' if the end of file has been reached.
1133 hLookAhead :: Handle -> IO Char
1134 hLookAhead handle = do
1135 wantReadableHandle "hLookAhead" handle $ \handle_ -> do
1136 let ref = haBuffer handle_
1138 is_line = haBufferMode handle_ == LineBuffering
1139 buf <- readIORef ref
1141 -- fill up the read buffer if necessary
1142 new_buf <- if bufferEmpty buf
1143 then fillReadBuffer fd is_line (haIsStream handle_) buf
1146 writeIORef ref new_buf
1148 (c,_) <- readCharFromBuffer (bufBuf buf) (bufRPtr buf)
1151 -- ---------------------------------------------------------------------------
1152 -- Buffering Operations
1154 -- Three kinds of buffering are supported: line-buffering,
1155 -- block-buffering or no-buffering. See GHC.IOBase for definition and
1156 -- further explanation of what the type represent.
1158 -- | Computation 'hSetBuffering' @hdl mode@ sets the mode of buffering for
1159 -- handle @hdl@ on subsequent reads and writes.
1161 -- If the buffer mode is changed from 'BlockBuffering' or
1162 -- 'LineBuffering' to 'NoBuffering', then
1164 -- * if @hdl@ is writable, the buffer is flushed as for 'hFlush';
1166 -- * if @hdl@ is not writable, the contents of the buffer is discarded.
1168 -- This operation may fail with:
1170 -- * 'isPermissionError' if the handle has already been used for reading
1171 -- or writing and the implementation does not allow the buffering mode
1174 hSetBuffering :: Handle -> BufferMode -> IO ()
1175 hSetBuffering handle mode =
1176 withAllHandles__ "hSetBuffering" handle $ \ handle_ -> do
1177 case haType handle_ of
1178 ClosedHandle -> ioe_closedHandle
1181 - we flush the old buffer regardless of whether
1182 the new buffer could fit the contents of the old buffer
1184 - allow a handle's buffering to change even if IO has
1185 occurred (ANSI C spec. does not allow this, nor did
1186 the previous implementation of IO.hSetBuffering).
1187 - a non-standard extension is to allow the buffering
1188 of semi-closed handles to change [sof 6/98]
1192 let state = initBufferState (haType handle_)
1195 -- we always have a 1-character read buffer for
1196 -- unbuffered handles: it's needed to
1197 -- support hLookAhead.
1198 NoBuffering -> allocateBuffer 1 ReadBuffer
1199 LineBuffering -> allocateBuffer dEFAULT_BUFFER_SIZE state
1200 BlockBuffering Nothing -> allocateBuffer dEFAULT_BUFFER_SIZE state
1201 BlockBuffering (Just n) | n <= 0 -> ioe_bufsiz n
1202 | otherwise -> allocateBuffer n state
1203 writeIORef (haBuffer handle_) new_buf
1205 -- for input terminals we need to put the terminal into
1206 -- cooked or raw mode depending on the type of buffering.
1207 is_tty <- fdIsTTY (haFD handle_)
1208 when (is_tty && isReadableHandleType (haType handle_)) $
1210 #ifndef mingw32_TARGET_OS
1211 -- 'raw' mode under win32 is a bit too specialised (and troublesome
1212 -- for most common uses), so simply disable its use here.
1213 NoBuffering -> setCooked (haFD handle_) False
1215 _ -> setCooked (haFD handle_) True
1217 -- throw away spare buffers, they might be the wrong size
1218 writeIORef (haBuffers handle_) BufferListNil
1220 return (handle_{ haBufferMode = mode })
1222 -- -----------------------------------------------------------------------------
1225 -- | The action 'hFlush' @hdl@ causes any items buffered for output
1226 -- in handle @hdl@ to be sent immediately to the operating system.
1228 -- This operation may fail with:
1230 -- * 'isFullError' if the device is full;
1232 -- * 'isPermissionError' if a system resource limit would be exceeded.
1233 -- It is unspecified whether the characters in the buffer are discarded
1234 -- or retained under these circumstances.
1236 hFlush :: Handle -> IO ()
1238 wantWritableHandle "hFlush" handle $ \ handle_ -> do
1239 buf <- readIORef (haBuffer handle_)
1240 if bufferIsWritable buf && not (bufferEmpty buf)
1241 then do flushed_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
1242 writeIORef (haBuffer handle_) flushed_buf
1246 -- -----------------------------------------------------------------------------
1247 -- Repositioning Handles
1249 data HandlePosn = HandlePosn Handle HandlePosition
1251 instance Eq HandlePosn where
1252 (HandlePosn h1 p1) == (HandlePosn h2 p2) = p1==p2 && h1==h2
1254 instance Show HandlePosn where
1255 showsPrec p (HandlePosn h pos) =
1256 showsPrec p h . showString " at position " . shows pos
1258 -- HandlePosition is the Haskell equivalent of POSIX' off_t.
1259 -- We represent it as an Integer on the Haskell side, but
1260 -- cheat slightly in that hGetPosn calls upon a C helper
1261 -- that reports the position back via (merely) an Int.
1262 type HandlePosition = Integer
1264 -- | Computation 'hGetPosn' @hdl@ returns the current I\/O position of
1265 -- @hdl@ as a value of the abstract type 'HandlePosn'.
1267 hGetPosn :: Handle -> IO HandlePosn
1268 hGetPosn handle = do
1269 posn <- hTell handle
1270 return (HandlePosn handle posn)
1272 -- | If a call to 'hGetPosn' @hdl@ returns a position @p@,
1273 -- then computation 'hSetPosn' @p@ sets the position of @hdl@
1274 -- to the position it held at the time of the call to 'hGetPosn'.
1276 -- This operation may fail with:
1278 -- * 'isPermissionError' if a system resource limit would be exceeded.
1280 hSetPosn :: HandlePosn -> IO ()
1281 hSetPosn (HandlePosn h i) = hSeek h AbsoluteSeek i
1283 -- ---------------------------------------------------------------------------
1286 -- | A mode that determines the effect of 'hSeek' @hdl mode i@, as follows:
1288 = AbsoluteSeek -- ^ the position of @hdl@ is set to @i@.
1289 | RelativeSeek -- ^ the position of @hdl@ is set to offset @i@
1290 -- from the current position.
1291 | SeekFromEnd -- ^ the position of @hdl@ is set to offset @i@
1292 -- from the end of the file.
1293 deriving (Eq, Ord, Ix, Enum, Read, Show)
1296 - when seeking using `SeekFromEnd', positive offsets (>=0) means
1297 seeking at or past EOF.
1299 - we possibly deviate from the report on the issue of seeking within
1300 the buffer and whether to flush it or not. The report isn't exactly
1304 -- | Computation 'hSeek' @hdl mode i@ sets the position of handle
1305 -- @hdl@ depending on @mode@.
1306 -- The offset @i@ is given in terms of 8-bit bytes.
1308 -- If @hdl@ is block- or line-buffered, then seeking to a position which is not
1309 -- in the current buffer will first cause any items in the output buffer to be
1310 -- written to the device, and then cause the input buffer to be discarded.
1311 -- Some handles may not be seekable (see 'hIsSeekable'), or only support a
1312 -- subset of the possible positioning operations (for instance, it may only
1313 -- be possible to seek to the end of a tape, or to a positive offset from
1314 -- the beginning or current position).
1315 -- It is not possible to set a negative I\/O position, or for
1316 -- a physical file, an I\/O position beyond the current end-of-file.
1318 -- This operation may fail with:
1320 -- * 'isPermissionError' if a system resource limit would be exceeded.
1322 hSeek :: Handle -> SeekMode -> Integer -> IO ()
1323 hSeek handle mode offset =
1324 wantSeekableHandle "hSeek" handle $ \ handle_ -> do
1326 puts ("hSeek " ++ show (mode,offset) ++ "\n")
1328 let ref = haBuffer handle_
1329 buf <- readIORef ref
1335 throwErrnoIfMinus1Retry_ "hSeek"
1336 (c_lseek (fromIntegral (haFD handle_)) (fromIntegral offset) whence)
1339 whence = case mode of
1340 AbsoluteSeek -> sEEK_SET
1341 RelativeSeek -> sEEK_CUR
1342 SeekFromEnd -> sEEK_END
1344 if bufferIsWritable buf
1345 then do new_buf <- flushWriteBuffer fd (haIsStream handle_) buf
1346 writeIORef ref new_buf
1350 if mode == RelativeSeek && offset >= 0 && offset < fromIntegral (w - r)
1351 then writeIORef ref buf{ bufRPtr = r + fromIntegral offset }
1354 new_buf <- flushReadBuffer (haFD handle_) buf
1355 writeIORef ref new_buf
1359 hTell :: Handle -> IO Integer
1361 wantSeekableHandle "hGetPosn" handle $ \ handle_ -> do
1363 #if defined(mingw32_TARGET_OS)
1364 -- urgh, on Windows we have to worry about \n -> \r\n translation,
1365 -- so we can't easily calculate the file position using the
1366 -- current buffer size. Just flush instead.
1369 let fd = fromIntegral (haFD handle_)
1370 posn <- fromIntegral `liftM`
1371 throwErrnoIfMinus1Retry "hGetPosn"
1372 (c_lseek fd 0 sEEK_CUR)
1374 let ref = haBuffer handle_
1375 buf <- readIORef ref
1378 | bufferIsWritable buf = posn + fromIntegral (bufWPtr buf)
1379 | otherwise = posn - fromIntegral (bufWPtr buf - bufRPtr buf)
1381 puts ("\nhGetPosn: (fd, posn, real_posn) = " ++ show (fd, posn, real_posn) ++ "\n")
1382 puts (" (bufWPtr, bufRPtr) = " ++ show (bufWPtr buf, bufRPtr buf) ++ "\n")
1386 -- -----------------------------------------------------------------------------
1387 -- Handle Properties
1389 -- A number of operations return information about the properties of a
1390 -- handle. Each of these operations returns `True' if the handle has
1391 -- the specified property, and `False' otherwise.
1393 hIsOpen :: Handle -> IO Bool
1395 withHandle_ "hIsOpen" handle $ \ handle_ -> do
1396 case haType handle_ of
1397 ClosedHandle -> return False
1398 SemiClosedHandle -> return False
1401 hIsClosed :: Handle -> IO Bool
1403 withHandle_ "hIsClosed" handle $ \ handle_ -> do
1404 case haType handle_ of
1405 ClosedHandle -> return True
1408 {- not defined, nor exported, but mentioned
1409 here for documentation purposes:
1411 hSemiClosed :: Handle -> IO Bool
1415 return (not (ho || hc))
1418 hIsReadable :: Handle -> IO Bool
1419 hIsReadable (DuplexHandle _ _ _) = return True
1420 hIsReadable handle =
1421 withHandle_ "hIsReadable" handle $ \ handle_ -> do
1422 case haType handle_ of
1423 ClosedHandle -> ioe_closedHandle
1424 SemiClosedHandle -> ioe_closedHandle
1425 htype -> return (isReadableHandleType htype)
1427 hIsWritable :: Handle -> IO Bool
1428 hIsWritable (DuplexHandle _ _ _) = return True
1429 hIsWritable handle =
1430 withHandle_ "hIsWritable" handle $ \ handle_ -> do
1431 case haType handle_ of
1432 ClosedHandle -> ioe_closedHandle
1433 SemiClosedHandle -> ioe_closedHandle
1434 htype -> return (isWritableHandleType htype)
1436 -- | Computation 'hGetBuffering' @hdl@ returns the current buffering mode
1439 hGetBuffering :: Handle -> IO BufferMode
1440 hGetBuffering handle =
1441 withHandle_ "hGetBuffering" handle $ \ handle_ -> do
1442 case haType handle_ of
1443 ClosedHandle -> ioe_closedHandle
1445 -- We're being non-standard here, and allow the buffering
1446 -- of a semi-closed handle to be queried. -- sof 6/98
1447 return (haBufferMode handle_) -- could be stricter..
1449 hIsSeekable :: Handle -> IO Bool
1450 hIsSeekable handle =
1451 withHandle_ "hIsSeekable" handle $ \ handle_ -> do
1452 case haType handle_ of
1453 ClosedHandle -> ioe_closedHandle
1454 SemiClosedHandle -> ioe_closedHandle
1455 AppendHandle -> return False
1456 _ -> do t <- fdType (haFD handle_)
1457 return (t == RegularFile
1459 || tEXT_MODE_SEEK_ALLOWED))
1461 -- -----------------------------------------------------------------------------
1462 -- Changing echo status (Non-standard GHC extensions)
1464 -- | Set the echoing status of a handle connected to a terminal.
1466 hSetEcho :: Handle -> Bool -> IO ()
1467 hSetEcho handle on = do
1468 isT <- hIsTerminalDevice handle
1472 withHandle_ "hSetEcho" handle $ \ handle_ -> do
1473 case haType handle_ of
1474 ClosedHandle -> ioe_closedHandle
1475 _ -> setEcho (haFD handle_) on
1477 -- | Get the echoing status of a handle connected to a terminal.
1479 hGetEcho :: Handle -> IO Bool
1480 hGetEcho handle = do
1481 isT <- hIsTerminalDevice handle
1485 withHandle_ "hGetEcho" handle $ \ handle_ -> do
1486 case haType handle_ of
1487 ClosedHandle -> ioe_closedHandle
1488 _ -> getEcho (haFD handle_)
1490 -- | Is the handle connected to a terminal?
1492 hIsTerminalDevice :: Handle -> IO Bool
1493 hIsTerminalDevice handle = do
1494 withHandle_ "hIsTerminalDevice" handle $ \ handle_ -> do
1495 case haType handle_ of
1496 ClosedHandle -> ioe_closedHandle
1497 _ -> fdIsTTY (haFD handle_)
1499 -- -----------------------------------------------------------------------------
1502 -- | Select binary mode ('True') or text mode ('False') on a open handle.
1503 -- (See also 'openBinaryFile'.)
1505 hSetBinaryMode :: Handle -> Bool -> IO ()
1506 hSetBinaryMode handle bin =
1507 withAllHandles__ "hSetBinaryMode" handle $ \ handle_ ->
1508 do throwErrnoIfMinus1_ "hSetBinaryMode"
1509 (setmode (fromIntegral (haFD handle_)) bin)
1510 return handle_{haIsBin=bin}
1512 foreign import ccall unsafe "__hscore_setmode"
1513 setmode :: CInt -> Bool -> IO CInt
1515 -- -----------------------------------------------------------------------------
1516 -- Duplicating a Handle
1518 -- |Returns a duplicate of the original handle, with its own buffer
1519 -- and file pointer. The original handle's buffer is flushed, including
1520 -- discarding any input data, before the handle is duplicated.
1522 hDuplicate :: Handle -> IO Handle
1523 hDuplicate h@(FileHandle path m) = do
1524 new_h_ <- withHandle' "hDuplicate" h m (dupHandle_ Nothing)
1525 newFileHandle path (handleFinalizer path) new_h_
1526 hDuplicate h@(DuplexHandle path r w) = do
1527 new_w_ <- withHandle' "hDuplicate" h w (dupHandle_ Nothing)
1528 new_w <- newMVar new_w_
1529 new_r_ <- withHandle' "hDuplicate" h r (dupHandle_ (Just new_w))
1530 new_r <- newMVar new_r_
1531 addMVarFinalizer new_w (handleFinalizer path new_w)
1532 return (DuplexHandle path new_r new_w)
1534 dupHandle_ other_side h_ = do
1535 -- flush the buffer first, so we don't have to copy its contents
1537 new_fd <- c_dup (fromIntegral (haFD h_))
1538 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE (initBufferState (haType h_))
1539 ioref <- newIORef buffer
1540 ioref_buffers <- newIORef BufferListNil
1542 let new_handle_ = h_{ haFD = fromIntegral new_fd,
1544 haBuffers = ioref_buffers,
1545 haOtherSide = other_side }
1546 return (h_, new_handle_)
1548 -- -----------------------------------------------------------------------------
1549 -- Replacing a Handle
1552 Makes the second handle a duplicate of the first handle. The second
1553 handle will be closed first, if it is not already.
1555 This can be used to retarget the standard Handles, for example:
1557 > do h <- openFile "mystdout" WriteMode
1558 > hDuplicateTo h stdout
1561 hDuplicateTo :: Handle -> Handle -> IO ()
1562 hDuplicateTo h1@(FileHandle _ m1) h2@(FileHandle _ m2) = do
1563 withHandle__' "hDuplicateTo" h2 m2 $ \h2_ -> do
1564 _ <- hClose_help h2_
1565 withHandle' "hDuplicateTo" h1 m1 (dupHandle_ Nothing)
1566 hDuplicateTo h1@(DuplexHandle _ r1 w1) h2@(DuplexHandle _ r2 w2) = do
1567 withHandle__' "hDuplicateTo" h2 w2 $ \w2_ -> do
1568 _ <- hClose_help w2_
1569 withHandle' "hDuplicateTo" h1 r1 (dupHandle_ Nothing)
1570 withHandle__' "hDuplicateTo" h2 r2 $ \r2_ -> do
1571 _ <- hClose_help r2_
1572 withHandle' "hDuplicateTo" h1 r1 (dupHandle_ (Just w1))
1574 ioException (IOError (Just h1) IllegalOperation "hDuplicateTo"
1575 "handles are incompatible" Nothing)
1577 -- ---------------------------------------------------------------------------
1580 -- | 'hShow' is in the 'IO' monad, and gives more comprehensive output
1581 -- than the (pure) instance of 'Show' for 'Handle'.
1583 hShow :: Handle -> IO String
1584 hShow h@(FileHandle path _) = showHandle' path False h
1585 hShow h@(DuplexHandle path _ _) = showHandle' path True h
1587 showHandle' filepath is_duplex h =
1588 withHandle_ "showHandle" h $ \hdl_ ->
1590 showType | is_duplex = showString "duplex (read-write)"
1591 | otherwise = shows (haType hdl_)
1595 showHdl (haType hdl_)
1596 (showString "loc=" . showString filepath . showChar ',' .
1597 showString "type=" . showType . showChar ',' .
1598 showString "binary=" . shows (haIsBin hdl_) . showChar ',' .
1599 showString "buffering=" . showBufMode (unsafePerformIO (readIORef (haBuffer hdl_))) (haBufferMode hdl_) . showString "}" )
1603 showHdl :: HandleType -> ShowS -> ShowS
1606 ClosedHandle -> shows ht . showString "}"
1609 showBufMode :: Buffer -> BufferMode -> ShowS
1610 showBufMode buf bmo =
1612 NoBuffering -> showString "none"
1613 LineBuffering -> showString "line"
1614 BlockBuffering (Just n) -> showString "block " . showParen True (shows n)
1615 BlockBuffering Nothing -> showString "block " . showParen True (shows def)
1620 -- ---------------------------------------------------------------------------
1624 puts :: String -> IO ()
1625 puts s = withCString s $ \cstr -> do write_rawBuffer 1 False cstr 0 (fromIntegral (length s))
1629 -- -----------------------------------------------------------------------------
1632 throwErrnoIfMinus1RetryOnBlock :: String -> IO CInt -> IO CInt -> IO CInt
1633 throwErrnoIfMinus1RetryOnBlock loc f on_block =
1636 if (res :: CInt) == -1
1640 then throwErrnoIfMinus1RetryOnBlock loc f on_block
1641 else if err == eWOULDBLOCK || err == eAGAIN
1646 -- -----------------------------------------------------------------------------
1647 -- wrappers to platform-specific constants:
1649 foreign import ccall unsafe "__hscore_supportsTextMode"
1650 tEXT_MODE_SEEK_ALLOWED :: Bool
1652 foreign import ccall unsafe "__hscore_bufsiz" dEFAULT_BUFFER_SIZE :: Int
1653 foreign import ccall unsafe "__hscore_seek_cur" sEEK_CUR :: CInt
1654 foreign import ccall unsafe "__hscore_seek_set" sEEK_SET :: CInt
1655 foreign import ccall unsafe "__hscore_seek_end" sEEK_END :: CInt