1 {-# OPTIONS_GHC -XNoImplicitPrelude -#include "HsBase.h" #-}
2 {-# OPTIONS_GHC -fno-warn-unused-matches #-}
3 {-# OPTIONS_GHC -fno-warn-unused-binds #-}
4 {-# OPTIONS_GHC -fno-warn-name-shadowing #-}
5 {-# OPTIONS_GHC -XRecordWildCards #-}
6 {-# OPTIONS_HADDOCK hide #-}
10 -----------------------------------------------------------------------------
12 -- Module : GHC.IO.Handle.Internals
13 -- Copyright : (c) The University of Glasgow, 1994-2001
14 -- License : see libraries/base/LICENSE
16 -- Maintainer : libraries@haskell.org
17 -- Stability : internal
18 -- Portability : non-portable
20 -- This module defines the basic operations on I\/O \"handles\". All
21 -- of the operations defined here are independent of the underlying
24 -----------------------------------------------------------------------------
27 module GHC.IO.Handle.Internals (
28 withHandle, withHandle', withHandle_,
29 withHandle__', withHandle_', withAllHandles__,
30 wantWritableHandle, wantReadableHandle, wantReadableHandle_,
33 mkHandle, mkFileHandle, mkDuplexHandle,
34 openTextEncoding, initBufferState,
35 dEFAULT_CHAR_BUFFER_SIZE,
37 flushBuffer, flushWriteBuffer, flushWriteBuffer_, flushCharReadBuffer,
38 flushCharBuffer, flushByteReadBuffer,
40 readTextDevice, writeTextDevice, readTextDeviceNonBlocking,
43 ioe_closedHandle, ioe_EOF, ioe_notReadable, ioe_notWritable,
44 ioe_finalizedHandle, ioe_bufsiz,
46 hClose_help, hLookAhead_,
48 HandleFinalizer, handleFinalizer,
55 import GHC.IO.Encoding
56 import GHC.IO.Handle.Types
58 import GHC.IO.BufferedIO (BufferedIO)
59 import GHC.IO.Exception
60 import GHC.IO.Device (IODevice, SeekMode(..))
61 import qualified GHC.IO.Device as IODevice
62 import qualified GHC.IO.BufferedIO as Buffered
67 import GHC.Num ( Num(..) )
75 -- import System.IO.Error
76 import System.Posix.Internals hiding (FD)
82 -- ---------------------------------------------------------------------------
83 -- Creating a new handle
85 type HandleFinalizer = FilePath -> MVar Handle__ -> IO ()
87 newFileHandle :: FilePath -> Maybe HandleFinalizer -> Handle__ -> IO Handle
88 newFileHandle filepath mb_finalizer hc = do
91 Just finalizer -> addMVarFinalizer m (finalizer filepath m)
93 return (FileHandle filepath m)
95 -- ---------------------------------------------------------------------------
96 -- Working with Handles
99 In the concurrent world, handles are locked during use. This is done
100 by wrapping an MVar around the handle which acts as a mutex over
101 operations on the handle.
103 To avoid races, we use the following bracketing operations. The idea
104 is to obtain the lock, do some operation and replace the lock again,
105 whether the operation succeeded or failed. We also want to handle the
106 case where the thread receives an exception while processing the IO
107 operation: in these cases we also want to relinquish the lock.
109 There are three versions of @withHandle@: corresponding to the three
110 possible combinations of:
112 - the operation may side-effect the handle
113 - the operation may return a result
115 If the operation generates an error or an exception is raised, the
116 original handle is always replaced.
119 {-# INLINE withHandle #-}
120 withHandle :: String -> Handle -> (Handle__ -> IO (Handle__,a)) -> IO a
121 withHandle fun h@(FileHandle _ m) act = withHandle' fun h m act
122 withHandle fun h@(DuplexHandle _ m _) act = withHandle' fun h m act
124 withHandle' :: String -> Handle -> MVar Handle__
125 -> (Handle__ -> IO (Handle__,a)) -> IO a
126 withHandle' fun h m act =
129 checkHandleInvariants h_
130 (h',v) <- (act h_ `catchAny` \err -> putMVar m h_ >> throw err)
131 `catchException` \ex -> ioError (augmentIOError ex fun h)
132 checkHandleInvariants h'
136 {-# INLINE withHandle_ #-}
137 withHandle_ :: String -> Handle -> (Handle__ -> IO a) -> IO a
138 withHandle_ fun h@(FileHandle _ m) act = withHandle_' fun h m act
139 withHandle_ fun h@(DuplexHandle _ m _) act = withHandle_' fun h m act
141 withHandle_' :: String -> Handle -> MVar Handle__ -> (Handle__ -> IO a) -> IO a
142 withHandle_' fun h m act =
145 checkHandleInvariants h_
146 v <- (act h_ `catchAny` \err -> putMVar m h_ >> throw err)
147 `catchException` \ex -> ioError (augmentIOError ex fun h)
148 checkHandleInvariants h_
152 withAllHandles__ :: String -> Handle -> (Handle__ -> IO Handle__) -> IO ()
153 withAllHandles__ fun h@(FileHandle _ m) act = withHandle__' fun h m act
154 withAllHandles__ fun h@(DuplexHandle _ r w) act = do
155 withHandle__' fun h r act
156 withHandle__' fun h w act
158 withHandle__' :: String -> Handle -> MVar Handle__ -> (Handle__ -> IO Handle__)
160 withHandle__' fun h m act =
163 checkHandleInvariants h_
164 h' <- (act h_ `catchAny` \err -> putMVar m h_ >> throw err)
165 `catchException` \ex -> ioError (augmentIOError ex fun h)
166 checkHandleInvariants h'
170 augmentIOError :: IOException -> String -> Handle -> IOException
171 augmentIOError ioe@IOError{ ioe_filename = fp } fun h
172 = ioe { ioe_handle = Just h, ioe_location = fun, ioe_filename = filepath }
175 | otherwise = case h of
176 FileHandle path _ -> Just path
177 DuplexHandle path _ _ -> Just path
179 -- ---------------------------------------------------------------------------
180 -- Wrapper for write operations.
182 wantWritableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
183 wantWritableHandle fun h@(FileHandle _ m) act
184 = wantWritableHandle' fun h m act
185 wantWritableHandle fun h@(DuplexHandle _ _ m) act
186 = withHandle_' fun h m act
189 :: String -> Handle -> MVar Handle__
190 -> (Handle__ -> IO a) -> IO a
191 wantWritableHandle' fun h m act
192 = withHandle_' fun h m (checkWritableHandle act)
194 checkWritableHandle :: (Handle__ -> IO a) -> Handle__ -> IO a
195 checkWritableHandle act h_@Handle__{..}
197 ClosedHandle -> ioe_closedHandle
198 SemiClosedHandle -> ioe_closedHandle
199 ReadHandle -> ioe_notWritable
200 ReadWriteHandle -> do
201 buf <- readIORef haCharBuffer
202 when (not (isWriteBuffer buf)) $ do
203 flushCharReadBuffer h_
204 flushByteReadBuffer h_
205 buf <- readIORef haCharBuffer
206 writeIORef haCharBuffer buf{ bufState = WriteBuffer }
207 buf <- readIORef haByteBuffer
208 writeIORef haByteBuffer buf{ bufState = WriteBuffer }
212 -- ---------------------------------------------------------------------------
213 -- Wrapper for read operations.
215 wantReadableHandle :: String -> Handle -> (Handle__ -> IO (Handle__,a)) -> IO a
216 wantReadableHandle fun h act = withHandle fun h (checkReadableHandle act)
218 wantReadableHandle_ :: String -> Handle -> (Handle__ -> IO a) -> IO a
219 wantReadableHandle_ fun h@(FileHandle _ m) act
220 = wantReadableHandle' fun h m act
221 wantReadableHandle_ fun h@(DuplexHandle _ m _) act
222 = withHandle_' fun h m act
225 :: String -> Handle -> MVar Handle__
226 -> (Handle__ -> IO a) -> IO a
227 wantReadableHandle' fun h m act
228 = withHandle_' fun h m (checkReadableHandle act)
230 checkReadableHandle :: (Handle__ -> IO a) -> Handle__ -> IO a
231 checkReadableHandle act h_@Handle__{..} =
233 ClosedHandle -> ioe_closedHandle
234 SemiClosedHandle -> ioe_closedHandle
235 AppendHandle -> ioe_notReadable
236 WriteHandle -> ioe_notReadable
237 ReadWriteHandle -> do
238 -- a read/write handle and we want to read from it. We must
239 -- flush all buffered write data first.
240 cbuf <- readIORef haCharBuffer
241 when (isWriteBuffer cbuf) $ do
242 cbuf' <- flushWriteBuffer_ h_ cbuf
243 writeIORef haCharBuffer cbuf'{ bufState = ReadBuffer }
244 bbuf <- readIORef haByteBuffer
245 writeIORef haByteBuffer bbuf{ bufState = ReadBuffer }
249 -- ---------------------------------------------------------------------------
250 -- Wrapper for seek operations.
252 wantSeekableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
253 wantSeekableHandle fun h@(DuplexHandle _ _ _) _act =
254 ioException (IOError (Just h) IllegalOperation fun
255 "handle is not seekable" Nothing Nothing)
256 wantSeekableHandle fun h@(FileHandle _ m) act =
257 withHandle_' fun h m (checkSeekableHandle act)
259 checkSeekableHandle :: (Handle__ -> IO a) -> Handle__ -> IO a
260 checkSeekableHandle act handle_@Handle__{haDevice=dev} =
261 case haType handle_ of
262 ClosedHandle -> ioe_closedHandle
263 SemiClosedHandle -> ioe_closedHandle
264 AppendHandle -> ioe_notSeekable
265 _ -> do b <- IODevice.isSeekable dev
266 if b then act handle_
269 -- -----------------------------------------------------------------------------
272 ioe_closedHandle, ioe_EOF,
273 ioe_notReadable, ioe_notWritable, ioe_cannotFlushTextRead,
274 ioe_notSeekable, ioe_notSeekable_notBin, ioe_invalidCharacter :: IO a
276 ioe_closedHandle = ioException
277 (IOError Nothing IllegalOperation ""
278 "handle is closed" Nothing Nothing)
279 ioe_EOF = ioException
280 (IOError Nothing EOF "" "" Nothing Nothing)
281 ioe_notReadable = ioException
282 (IOError Nothing IllegalOperation ""
283 "handle is not open for reading" Nothing Nothing)
284 ioe_notWritable = ioException
285 (IOError Nothing IllegalOperation ""
286 "handle is not open for writing" Nothing Nothing)
287 ioe_notSeekable = ioException
288 (IOError Nothing IllegalOperation ""
289 "handle is not seekable" Nothing Nothing)
290 ioe_notSeekable_notBin = ioException
291 (IOError Nothing IllegalOperation ""
292 "seek operations on text-mode handles are not allowed on this platform"
294 ioe_cannotFlushTextRead = ioException
295 (IOError Nothing IllegalOperation ""
296 "cannot flush the read buffer of a text-mode handle"
298 ioe_invalidCharacter = ioException
299 (IOError Nothing InvalidArgument ""
300 ("invalid byte sequence for this encoding") Nothing Nothing)
302 ioe_finalizedHandle :: FilePath -> Handle__
303 ioe_finalizedHandle fp = throw
304 (IOError Nothing IllegalOperation ""
305 "handle is finalized" Nothing (Just fp))
307 ioe_bufsiz :: Int -> IO a
308 ioe_bufsiz n = ioException
309 (IOError Nothing InvalidArgument "hSetBuffering"
310 ("illegal buffer size " ++ showsPrec 9 n []) Nothing Nothing)
311 -- 9 => should be parens'ified.
313 -- -----------------------------------------------------------------------------
316 -- For a duplex handle, we arrange that the read side points to the write side
317 -- (and hence keeps it alive if the read side is alive). This is done by
318 -- having the haOtherSide field of the read side point to the read side.
319 -- The finalizer is then placed on the write side, and the handle only gets
320 -- finalized once, when both sides are no longer required.
322 -- NOTE about finalized handles: It's possible that a handle can be
323 -- finalized and then we try to use it later, for example if the
324 -- handle is referenced from another finalizer, or from a thread that
325 -- has become unreferenced and then resurrected (arguably in the
326 -- latter case we shouldn't finalize the Handle...). Anyway,
327 -- we try to emit a helpful message which is better than nothing.
329 handleFinalizer :: FilePath -> MVar Handle__ -> IO ()
330 handleFinalizer fp m = do
331 handle_ <- takeMVar m
332 case haType handle_ of
333 ClosedHandle -> return ()
334 _ -> do flushWriteBuffer handle_ `catchAny` \_ -> return ()
335 -- ignore errors and async exceptions, and close the
336 -- descriptor anyway...
337 hClose_handle_ handle_
339 putMVar m (ioe_finalizedHandle fp)
341 -- ---------------------------------------------------------------------------
342 -- Allocating buffers
344 -- using an 8k char buffer instead of 32k improved performance for a
345 -- basic "cat" program by ~30% for me. --SDM
346 dEFAULT_CHAR_BUFFER_SIZE :: Int
347 dEFAULT_CHAR_BUFFER_SIZE = dEFAULT_BUFFER_SIZE `div` 4
349 getCharBuffer :: IODevice dev => dev -> BufferState
350 -> IO (IORef CharBuffer, BufferMode)
351 getCharBuffer dev state = do
352 buffer <- newCharBuffer dEFAULT_CHAR_BUFFER_SIZE state
353 ioref <- newIORef buffer
354 is_tty <- IODevice.isTerminal dev
357 | is_tty = LineBuffering
358 | otherwise = BlockBuffering Nothing
360 return (ioref, buffer_mode)
362 mkUnBuffer :: BufferState -> IO (IORef CharBuffer, BufferMode)
363 mkUnBuffer state = do
364 buffer <- case state of -- See [note Buffer Sizing], GHC.IO.Handle.Types
365 ReadBuffer -> newCharBuffer dEFAULT_CHAR_BUFFER_SIZE state
366 WriteBuffer -> newCharBuffer 1 state
367 ref <- newIORef buffer
368 return (ref, NoBuffering)
370 -- -----------------------------------------------------------------------------
373 -- | syncs the file with the buffer, including moving the
374 -- file pointer backwards in the case of a read buffer. This can fail
375 -- on a non-seekable read Handle.
376 flushBuffer :: Handle__ -> IO ()
377 flushBuffer h_@Handle__{..} = do
378 buf <- readIORef haCharBuffer
381 flushCharReadBuffer h_
382 flushByteReadBuffer h_
384 buf' <- flushWriteBuffer_ h_ buf
385 writeIORef haCharBuffer buf'
387 -- | flushes at least the Char buffer, and the byte buffer for a write
388 -- Handle. Works on all Handles.
389 flushCharBuffer :: Handle__ -> IO ()
390 flushCharBuffer h_@Handle__{..} = do
391 buf <- readIORef haCharBuffer
394 flushCharReadBuffer h_
396 buf' <- flushWriteBuffer_ h_ buf
397 writeIORef haCharBuffer buf'
399 -- -----------------------------------------------------------------------------
400 -- Writing data (flushing write buffers)
402 -- flushWriteBuffer flushes the buffer iff it contains pending write
403 -- data. Flushes both the Char and the byte buffer, leaving both
405 flushWriteBuffer :: Handle__ -> IO ()
406 flushWriteBuffer h_@Handle__{..} = do
407 buf <- readIORef haCharBuffer
409 then do buf' <- flushWriteBuffer_ h_ buf
410 writeIORef haCharBuffer buf'
413 flushWriteBuffer_ :: Handle__ -> CharBuffer -> IO CharBuffer
414 flushWriteBuffer_ h_@Handle__{..} cbuf = do
415 bbuf <- readIORef haByteBuffer
416 if not (isEmptyBuffer cbuf) || not (isEmptyBuffer bbuf)
417 then do writeTextDevice h_ cbuf
418 return cbuf{ bufL=0, bufR=0 }
421 -- -----------------------------------------------------------------------------
422 -- Flushing read buffers
424 -- It is always possible to flush the Char buffer back to the byte buffer.
425 flushCharReadBuffer :: Handle__ -> IO ()
426 flushCharReadBuffer Handle__{..} = do
427 cbuf <- readIORef haCharBuffer
428 if isWriteBuffer cbuf || isEmptyBuffer cbuf then return () else do
430 -- haLastDecode is the byte buffer just before we did our last batch of
431 -- decoding. We're going to re-decode the bytes up to the current char,
432 -- to find out where we should revert the byte buffer to.
433 (codec_state, bbuf0) <- readIORef haLastDecode
435 cbuf0 <- readIORef haCharBuffer
436 writeIORef haCharBuffer cbuf0{ bufL=0, bufR=0 }
438 -- if we haven't used any characters from the char buffer, then just
439 -- re-install the old byte buffer.
441 then do writeIORef haByteBuffer bbuf0
447 writeIORef haByteBuffer bbuf0 { bufL = bufL bbuf0 + bufL cbuf0 }
448 -- no decoder: the number of bytes to decode is the same as the
449 -- number of chars we have used up.
452 debugIO ("flushCharReadBuffer re-decode, bbuf=" ++ summaryBuffer bbuf0 ++
453 " cbuf=" ++ summaryBuffer cbuf0)
455 -- restore the codec state
456 setState decoder codec_state
458 (bbuf1,cbuf1) <- (encode decoder) bbuf0
459 cbuf0{ bufL=0, bufR=0, bufSize = bufL cbuf0 }
461 debugIO ("finished, bbuf=" ++ summaryBuffer bbuf1 ++
462 " cbuf=" ++ summaryBuffer cbuf1)
464 writeIORef haByteBuffer bbuf1
467 -- When flushing the byte read buffer, we seek backwards by the number
468 -- of characters in the buffer. The file descriptor must therefore be
469 -- seekable: attempting to flush the read buffer on an unseekable
470 -- handle is not allowed.
472 flushByteReadBuffer :: Handle__ -> IO ()
473 flushByteReadBuffer h_@Handle__{..} = do
474 bbuf <- readIORef haByteBuffer
476 if isEmptyBuffer bbuf then return () else do
478 seekable <- IODevice.isSeekable haDevice
479 when (not seekable) $ ioe_cannotFlushTextRead
481 let seek = negate (bufR bbuf - bufL bbuf)
483 debugIO ("flushByteReadBuffer: new file offset = " ++ show seek)
484 IODevice.seek haDevice RelativeSeek (fromIntegral seek)
486 writeIORef haByteBuffer bbuf{ bufL=0, bufR=0 }
488 -- ----------------------------------------------------------------------------
491 mkHandle :: (IODevice dev, BufferedIO dev, Typeable dev) => dev
495 -> Maybe TextEncoding
497 -> Maybe HandleFinalizer
498 -> Maybe (MVar Handle__)
501 mkHandle dev filepath ha_type buffered mb_codec nl finalizer other_side = do
502 openTextEncoding mb_codec ha_type $ \ mb_encoder mb_decoder -> do
504 let buf_state = initBufferState ha_type
505 bbuf <- Buffered.newBuffer dev buf_state
506 bbufref <- newIORef bbuf
507 last_decode <- newIORef (error "codec_state", bbuf)
510 if buffered then getCharBuffer dev buf_state
511 else mkUnBuffer buf_state
513 spares <- newIORef BufferListNil
514 newFileHandle filepath finalizer
515 (Handle__ { haDevice = dev,
517 haBufferMode = bmode,
518 haByteBuffer = bbufref,
519 haLastDecode = last_decode,
520 haCharBuffer = cbufref,
522 haEncoder = mb_encoder,
523 haDecoder = mb_decoder,
524 haInputNL = inputNL nl,
525 haOutputNL = outputNL nl,
526 haOtherSide = other_side
529 -- | makes a new 'Handle'
530 mkFileHandle :: (IODevice dev, BufferedIO dev, Typeable dev)
531 => dev -- ^ the underlying IO device, which must support
532 -- 'IODevice', 'BufferedIO' and 'Typeable'
534 -- ^ a string describing the 'Handle', e.g. the file
535 -- path for a file. Used in error messages.
537 -- The mode in which the 'Handle' is to be used
538 -> Maybe TextEncoding
539 -- Create the 'Handle' with no text encoding?
541 -- Translate newlines?
543 mkFileHandle dev filepath iomode mb_codec tr_newlines = do
544 mkHandle dev filepath (ioModeToHandleType iomode) True{-buffered-} mb_codec
546 (Just handleFinalizer) Nothing{-other_side-}
548 -- | like 'mkFileHandle', except that a 'Handle' is created with two
549 -- independent buffers, one for reading and one for writing. Used for
550 -- full-dupliex streams, such as network sockets.
551 mkDuplexHandle :: (IODevice dev, BufferedIO dev, Typeable dev) => dev
552 -> FilePath -> Maybe TextEncoding -> NewlineMode -> IO Handle
553 mkDuplexHandle dev filepath mb_codec tr_newlines = do
555 write_side@(FileHandle _ write_m) <-
556 mkHandle dev filepath WriteHandle True mb_codec
558 (Just handleFinalizer)
559 Nothing -- no othersie
561 read_side@(FileHandle _ read_m) <-
562 mkHandle dev filepath ReadHandle True mb_codec
564 Nothing -- no finalizer
567 return (DuplexHandle filepath read_m write_m)
569 ioModeToHandleType :: IOMode -> HandleType
570 ioModeToHandleType ReadMode = ReadHandle
571 ioModeToHandleType WriteMode = WriteHandle
572 ioModeToHandleType ReadWriteMode = ReadWriteHandle
573 ioModeToHandleType AppendMode = AppendHandle
575 initBufferState :: HandleType -> BufferState
576 initBufferState ReadHandle = ReadBuffer
577 initBufferState _ = WriteBuffer
580 :: Maybe TextEncoding
582 -> (forall es ds . Maybe (TextEncoder es) -> Maybe (TextDecoder ds) -> IO a)
585 openTextEncoding Nothing ha_type cont = cont Nothing Nothing
586 openTextEncoding (Just TextEncoding{..}) ha_type cont = do
587 mb_decoder <- if isReadableHandleType ha_type then do
588 decoder <- mkTextDecoder
589 return (Just decoder)
592 mb_encoder <- if isWritableHandleType ha_type then do
593 encoder <- mkTextEncoder
594 return (Just encoder)
597 cont mb_encoder mb_decoder
599 -- ---------------------------------------------------------------------------
602 -- hClose_help is also called by lazyRead (in GHC.IO.Handle.Text) when
603 -- EOF is read or an IO error occurs on a lazy stream. The
604 -- semi-closed Handle is then closed immediately. We have to be
605 -- careful with DuplexHandles though: we have to leave the closing to
606 -- the finalizer in that case, because the write side may still be in
608 hClose_help :: Handle__ -> IO (Handle__, Maybe SomeException)
609 hClose_help handle_ =
610 case haType handle_ of
611 ClosedHandle -> return (handle_,Nothing)
612 _ -> do mb_exc1 <- trymaybe $ flushWriteBuffer handle_ -- interruptible
613 -- it is important that hClose doesn't fail and
614 -- leave the Handle open (#3128), so we catch
615 -- exceptions when flushing the buffer.
616 (h_, mb_exc2) <- hClose_handle_ handle_
617 return (h_, if isJust mb_exc1 then mb_exc1 else mb_exc2)
620 trymaybe :: IO () -> IO (Maybe SomeException)
621 trymaybe io = (do io; return Nothing) `catchException` \e -> return (Just e)
623 hClose_handle_ :: Handle__ -> IO (Handle__, Maybe SomeException)
624 hClose_handle_ Handle__{..} = do
626 -- close the file descriptor, but not when this is the read
627 -- side of a duplex handle.
628 -- If an exception is raised by the close(), we want to continue
629 -- to close the handle and release the lock if it has one, then
630 -- we return the exception to the caller of hClose_help which can
631 -- raise it if necessary.
634 Nothing -> trymaybe $ IODevice.close haDevice
635 Just _ -> return Nothing
637 -- free the spare buffers
638 writeIORef haBuffers BufferListNil
639 writeIORef haCharBuffer noCharBuffer
640 writeIORef haByteBuffer noByteBuffer
642 -- release our encoder/decoder
643 case haDecoder of Nothing -> return (); Just d -> close d
644 case haEncoder of Nothing -> return (); Just d -> close d
646 -- we must set the fd to -1, because the finalizer is going
647 -- to run eventually and try to close/unlock it.
648 -- ToDo: necessary? the handle will be marked ClosedHandle
649 -- XXX GHC won't let us use record update here, hence wildcards
650 return (Handle__{ haType = ClosedHandle, .. }, maybe_exception)
652 {-# NOINLINE noCharBuffer #-}
653 noCharBuffer :: CharBuffer
654 noCharBuffer = unsafePerformIO $ newCharBuffer 1 ReadBuffer
656 {-# NOINLINE noByteBuffer #-}
657 noByteBuffer :: Buffer Word8
658 noByteBuffer = unsafePerformIO $ newByteBuffer 1 ReadBuffer
660 -- ---------------------------------------------------------------------------
663 hLookAhead_ :: Handle__ -> IO Char
664 hLookAhead_ handle_@Handle__{..} = do
665 buf <- readIORef haCharBuffer
667 -- fill up the read buffer if necessary
668 new_buf <- if isEmptyBuffer buf
669 then readTextDevice handle_ buf
671 writeIORef haCharBuffer new_buf
673 peekCharBuf (bufRaw buf) (bufL buf)
675 -- ---------------------------------------------------------------------------
678 debugIO :: String -> IO ()
679 #if defined(DEBUG_DUMP)
681 withCStringLen (s++"\n") $ \(p,len) -> c_write 1 p (fromIntegral len)
684 debugIO s = return ()
687 -- ----------------------------------------------------------------------------
690 -- Write the contents of the supplied Char buffer to the device, return
691 -- only when all the data has been written.
692 writeTextDevice :: Handle__ -> CharBuffer -> IO ()
693 writeTextDevice h_@Handle__{..} cbuf = do
695 bbuf <- readIORef haByteBuffer
697 debugIO ("writeTextDevice: cbuf=" ++ summaryBuffer cbuf ++
698 " bbuf=" ++ summaryBuffer bbuf)
700 (cbuf',bbuf') <- case haEncoder of
701 Nothing -> latin1_encode cbuf bbuf
702 Just encoder -> (encode encoder) cbuf bbuf
704 debugIO ("writeTextDevice after encoding: cbuf=" ++ summaryBuffer cbuf' ++
705 " bbuf=" ++ summaryBuffer bbuf')
707 Buffered.flushWriteBuffer haDevice bbuf'
708 writeIORef haByteBuffer bbuf{bufL=0,bufR=0}
709 if not (isEmptyBuffer cbuf')
710 then writeTextDevice h_ cbuf'
713 -- Read characters into the provided buffer. Return when any
714 -- characters are available; raise an exception if the end of
716 readTextDevice :: Handle__ -> CharBuffer -> IO CharBuffer
717 readTextDevice h_@Handle__{..} cbuf = do
719 bbuf0 <- readIORef haByteBuffer
721 debugIO ("readTextDevice: cbuf=" ++ summaryBuffer cbuf ++
722 " bbuf=" ++ summaryBuffer bbuf0)
724 bbuf1 <- if not (isEmptyBuffer bbuf0)
727 (r,bbuf1) <- Buffered.fillReadBuffer haDevice bbuf0
728 if r == 0 then ioe_EOF else do -- raise EOF
731 debugIO ("readTextDevice after reading: bbuf=" ++ summaryBuffer bbuf1)
736 writeIORef haLastDecode (error "codec_state", bbuf1)
737 latin1_decode bbuf1 cbuf
739 state <- getState decoder
740 writeIORef haLastDecode (state, bbuf1)
741 (encode decoder) bbuf1 cbuf
743 debugIO ("readTextDevice after decoding: cbuf=" ++ summaryBuffer cbuf' ++
744 " bbuf=" ++ summaryBuffer bbuf2)
746 writeIORef haByteBuffer bbuf2
747 if bufR cbuf' == bufR cbuf -- no new characters
748 then readTextDevice' h_ bbuf2 cbuf -- we need more bytes to make a Char
751 -- we have an incomplete byte sequence at the end of the buffer: try to
753 readTextDevice' :: Handle__ -> Buffer Word8 -> CharBuffer -> IO CharBuffer
754 readTextDevice' h_@Handle__{..} bbuf0 cbuf = do
756 -- copy the partial sequence to the beginning of the buffer, so we have
757 -- room to read more bytes.
758 bbuf1 <- slideContents bbuf0
760 bbuf2 <- do (r,bbuf2) <- Buffered.fillReadBuffer haDevice bbuf1
762 then ioe_invalidCharacter
765 debugIO ("readTextDevice after reading: bbuf=" ++ summaryBuffer bbuf2)
770 writeIORef haLastDecode (error "codec_state", bbuf2)
771 latin1_decode bbuf2 cbuf
773 state <- getState decoder
774 writeIORef haLastDecode (state, bbuf2)
775 (encode decoder) bbuf2 cbuf
777 debugIO ("readTextDevice after decoding: cbuf=" ++ summaryBuffer cbuf' ++
778 " bbuf=" ++ summaryBuffer bbuf3)
780 writeIORef haByteBuffer bbuf3
781 if bufR cbuf == bufR cbuf'
782 then readTextDevice' h_ bbuf3 cbuf'
785 -- Read characters into the provided buffer. Do not block;
786 -- return zero characters instead. Raises an exception on end-of-file.
787 readTextDeviceNonBlocking :: Handle__ -> CharBuffer -> IO CharBuffer
788 readTextDeviceNonBlocking h_@Handle__{..} cbuf = do
790 bbuf0 <- readIORef haByteBuffer
791 bbuf1 <- if not (isEmptyBuffer bbuf0)
794 (r,bbuf1) <- Buffered.fillReadBuffer haDevice bbuf0
795 if r == 0 then ioe_EOF else do -- raise EOF
798 (bbuf2,cbuf') <- case haDecoder of
799 Nothing -> latin1_decode bbuf1 cbuf
800 Just decoder -> (encode decoder) bbuf1 cbuf
802 writeIORef haByteBuffer bbuf2