{-# LANGUAGE Trustworthy #-} {-# LANGUAGE NoImplicitPrelude , RecordWildCards , BangPatterns , NondecreasingIndentation , RankNTypes #-} {-# OPTIONS_GHC -fno-warn-unused-matches #-} {-# OPTIONS_GHC -fno-warn-name-shadowing #-} {-# OPTIONS_HADDOCK hide #-} ----------------------------------------------------------------------------- -- | -- Module : GHC.IO.Handle.Internals -- Copyright : (c) The University of Glasgow, 1994-2001 -- License : see libraries/base/LICENSE -- -- Maintainer : libraries@haskell.org -- Stability : internal -- Portability : non-portable -- -- This module defines the basic operations on I\/O \"handles\". All -- of the operations defined here are independent of the underlying -- device. -- ----------------------------------------------------------------------------- module GHC.IO.Handle.Internals ( withHandle, withHandle', withHandle_, withHandle__', withHandle_', withAllHandles__, wantWritableHandle, wantReadableHandle, wantReadableHandle_, wantSeekableHandle, mkHandle, mkFileHandle, mkDuplexHandle, openTextEncoding, closeTextCodecs, initBufferState, dEFAULT_CHAR_BUFFER_SIZE, flushBuffer, flushWriteBuffer, flushCharReadBuffer, flushCharBuffer, flushByteReadBuffer, flushByteWriteBuffer, readTextDevice, writeCharBuffer, readTextDeviceNonBlocking, decodeByteBuf, augmentIOError, ioe_closedHandle, ioe_EOF, ioe_notReadable, ioe_notWritable, ioe_finalizedHandle, ioe_bufsiz, hClose_help, hLookAhead_, HandleFinalizer, handleFinalizer, debugIO, ) where import GHC.IO import GHC.IO.IOMode import GHC.IO.Encoding as Encoding import GHC.IO.Encoding.Types (CodeBuffer) import GHC.IO.Handle.Types import GHC.IO.Buffer import GHC.IO.BufferedIO (BufferedIO) import GHC.IO.Exception import GHC.IO.Device (IODevice, SeekMode(..)) import qualified GHC.IO.Device as IODevice import qualified GHC.IO.BufferedIO as Buffered import GHC.Conc.Sync import GHC.Real import GHC.Base import GHC.Exception import GHC.Num ( Num(..) ) import GHC.Show import GHC.IORef import GHC.MVar import Data.Typeable import Control.Monad import Data.Maybe import Foreign.Safe import System.Posix.Internals hiding (FD) import Foreign.C c_DEBUG_DUMP :: Bool c_DEBUG_DUMP = False -- --------------------------------------------------------------------------- -- Creating a new handle type HandleFinalizer = FilePath -> MVar Handle__ -> IO () newFileHandle :: FilePath -> Maybe HandleFinalizer -> Handle__ -> IO Handle newFileHandle filepath mb_finalizer hc = do m <- newMVar hc case mb_finalizer of Just finalizer -> addMVarFinalizer m (finalizer filepath m) Nothing -> return () return (FileHandle filepath m) -- --------------------------------------------------------------------------- -- Working with Handles {- In the concurrent world, handles are locked during use. This is done by wrapping an MVar around the handle which acts as a mutex over operations on the handle. To avoid races, we use the following bracketing operations. The idea is to obtain the lock, do some operation and replace the lock again, whether the operation succeeded or failed. We also want to handle the case where the thread receives an exception while processing the IO operation: in these cases we also want to relinquish the lock. There are three versions of @withHandle@: corresponding to the three possible combinations of: - the operation may side-effect the handle - the operation may return a result If the operation generates an error or an exception is raised, the original handle is always replaced. -} {-# INLINE withHandle #-} withHandle :: String -> Handle -> (Handle__ -> IO (Handle__,a)) -> IO a withHandle fun h@(FileHandle _ m) act = withHandle' fun h m act withHandle fun h@(DuplexHandle _ m _) act = withHandle' fun h m act withHandle' :: String -> Handle -> MVar Handle__ -> (Handle__ -> IO (Handle__,a)) -> IO a withHandle' fun h m act = mask_ $ do (h',v) <- do_operation fun h act m checkHandleInvariants h' putMVar m h' return v {-# INLINE withHandle_ #-} withHandle_ :: String -> Handle -> (Handle__ -> IO a) -> IO a withHandle_ fun h@(FileHandle _ m) act = withHandle_' fun h m act withHandle_ fun h@(DuplexHandle _ m _) act = withHandle_' fun h m act withHandle_' :: String -> Handle -> MVar Handle__ -> (Handle__ -> IO a) -> IO a withHandle_' fun h m act = withHandle' fun h m $ \h_ -> do a <- act h_ return (h_,a) withAllHandles__ :: String -> Handle -> (Handle__ -> IO Handle__) -> IO () withAllHandles__ fun h@(FileHandle _ m) act = withHandle__' fun h m act withAllHandles__ fun h@(DuplexHandle _ r w) act = do withHandle__' fun h r act withHandle__' fun h w act withHandle__' :: String -> Handle -> MVar Handle__ -> (Handle__ -> IO Handle__) -> IO () withHandle__' fun h m act = mask_ $ do h' <- do_operation fun h act m checkHandleInvariants h' putMVar m h' return () do_operation :: String -> Handle -> (Handle__ -> IO a) -> MVar Handle__ -> IO a do_operation fun h act m = do h_ <- takeMVar m checkHandleInvariants h_ act h_ `catchException` handler h_ where handler h_ e = do putMVar m h_ case () of _ | Just ioe <- fromException e -> ioError (augmentIOError ioe fun h) _ | Just async_ex <- fromException e -> do -- see Note [async] let _ = async_ex :: SomeAsyncException t <- myThreadId throwTo t e do_operation fun h act m _otherwise -> throwIO e -- Note [async] -- -- If an asynchronous exception is raised during an I/O operation, -- normally it is fine to just re-throw the exception synchronously. -- However, if we are inside an unsafePerformIO or an -- unsafeInterleaveIO, this would replace the enclosing thunk with the -- exception raised, which is wrong (#3997). We have to release the -- lock on the Handle, but what do we replace the thunk with? What -- should happen when the thunk is subsequently demanded again? -- -- The only sensible choice we have is to re-do the IO operation on -- resumption, but then we have to be careful in the IO library that -- this is always safe to do. In particular we should -- -- never perform any side-effects before an interruptible operation -- -- because the interruptible operation may raise an asynchronous -- exception, which may cause the operation and its side effects to be -- subsequently performed again. -- -- Re-doing the IO operation is achieved by: -- - using throwTo to re-throw the asynchronous exception asynchronously -- in the current thread -- - on resumption, it will be as if throwTo returns. In that case, we -- recursively invoke the original operation (see do_operation above). -- -- Interruptible operations in the I/O library are: -- - threadWaitRead/threadWaitWrite -- - fillReadBuffer/flushWriteBuffer -- - readTextDevice/writeTextDevice augmentIOError :: IOException -> String -> Handle -> IOException augmentIOError ioe@IOError{ ioe_filename = fp } fun h = ioe { ioe_handle = Just h, ioe_location = fun, ioe_filename = filepath } where filepath | Just _ <- fp = fp | otherwise = case h of FileHandle path _ -> Just path DuplexHandle path _ _ -> Just path -- --------------------------------------------------------------------------- -- Wrapper for write operations. wantWritableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a wantWritableHandle fun h@(FileHandle _ m) act = wantWritableHandle' fun h m act wantWritableHandle fun h@(DuplexHandle _ _ m) act = wantWritableHandle' fun h m act -- we know it's not a ReadHandle or ReadWriteHandle, but we have to -- check for ClosedHandle/SemiClosedHandle. (#4808) wantWritableHandle' :: String -> Handle -> MVar Handle__ -> (Handle__ -> IO a) -> IO a wantWritableHandle' fun h m act = withHandle_' fun h m (checkWritableHandle act) checkWritableHandle :: (Handle__ -> IO a) -> Handle__ -> IO a checkWritableHandle act h_@Handle__{..} = case haType of ClosedHandle -> ioe_closedHandle SemiClosedHandle -> ioe_closedHandle ReadHandle -> ioe_notWritable ReadWriteHandle -> do buf <- readIORef haCharBuffer when (not (isWriteBuffer buf)) $ do flushCharReadBuffer h_ flushByteReadBuffer h_ buf <- readIORef haCharBuffer writeIORef haCharBuffer buf{ bufState = WriteBuffer } buf <- readIORef haByteBuffer buf' <- Buffered.emptyWriteBuffer haDevice buf writeIORef haByteBuffer buf' act h_ _other -> act h_ -- --------------------------------------------------------------------------- -- Wrapper for read operations. wantReadableHandle :: String -> Handle -> (Handle__ -> IO (Handle__,a)) -> IO a wantReadableHandle fun h act = withHandle fun h (checkReadableHandle act) wantReadableHandle_ :: String -> Handle -> (Handle__ -> IO a) -> IO a wantReadableHandle_ fun h@(FileHandle _ m) act = wantReadableHandle' fun h m act wantReadableHandle_ fun h@(DuplexHandle _ m _) act = wantReadableHandle' fun h m act -- we know it's not a WriteHandle or ReadWriteHandle, but we have to -- check for ClosedHandle/SemiClosedHandle. (#4808) wantReadableHandle' :: String -> Handle -> MVar Handle__ -> (Handle__ -> IO a) -> IO a wantReadableHandle' fun h m act = withHandle_' fun h m (checkReadableHandle act) checkReadableHandle :: (Handle__ -> IO a) -> Handle__ -> IO a checkReadableHandle act h_@Handle__{..} = case haType of ClosedHandle -> ioe_closedHandle SemiClosedHandle -> ioe_closedHandle AppendHandle -> ioe_notReadable WriteHandle -> ioe_notReadable ReadWriteHandle -> do -- a read/write handle and we want to read from it. We must -- flush all buffered write data first. bbuf <- readIORef haByteBuffer when (isWriteBuffer bbuf) $ do when (not (isEmptyBuffer bbuf)) $ flushByteWriteBuffer h_ cbuf' <- readIORef haCharBuffer writeIORef haCharBuffer cbuf'{ bufState = ReadBuffer } bbuf <- readIORef haByteBuffer writeIORef haByteBuffer bbuf{ bufState = ReadBuffer } act h_ _other -> act h_ -- --------------------------------------------------------------------------- -- Wrapper for seek operations. wantSeekableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a wantSeekableHandle fun h@(DuplexHandle _ _ _) _act = ioException (IOError (Just h) IllegalOperation fun "handle is not seekable" Nothing Nothing) wantSeekableHandle fun h@(FileHandle _ m) act = withHandle_' fun h m (checkSeekableHandle act) checkSeekableHandle :: (Handle__ -> IO a) -> Handle__ -> IO a checkSeekableHandle act handle_@Handle__{haDevice=dev} = case haType handle_ of ClosedHandle -> ioe_closedHandle SemiClosedHandle -> ioe_closedHandle AppendHandle -> ioe_notSeekable _ -> do b <- IODevice.isSeekable dev if b then act handle_ else ioe_notSeekable -- ----------------------------------------------------------------------------- -- Handy IOErrors ioe_closedHandle, ioe_EOF, ioe_notReadable, ioe_notWritable, ioe_cannotFlushNotSeekable, ioe_notSeekable :: IO a ioe_closedHandle = ioException (IOError Nothing IllegalOperation "" "handle is closed" Nothing Nothing) ioe_EOF = ioException (IOError Nothing EOF "" "" Nothing Nothing) ioe_notReadable = ioException (IOError Nothing IllegalOperation "" "handle is not open for reading" Nothing Nothing) ioe_notWritable = ioException (IOError Nothing IllegalOperation "" "handle is not open for writing" Nothing Nothing) ioe_notSeekable = ioException (IOError Nothing IllegalOperation "" "handle is not seekable" Nothing Nothing) ioe_cannotFlushNotSeekable = ioException (IOError Nothing IllegalOperation "" "cannot flush the read buffer: underlying device is not seekable" Nothing Nothing) ioe_finalizedHandle :: FilePath -> Handle__ ioe_finalizedHandle fp = throw (IOError Nothing IllegalOperation "" "handle is finalized" Nothing (Just fp)) ioe_bufsiz :: Int -> IO a ioe_bufsiz n = ioException (IOError Nothing InvalidArgument "hSetBuffering" ("illegal buffer size " ++ showsPrec 9 n []) Nothing Nothing) -- 9 => should be parens'ified. -- --------------------------------------------------------------------------- -- Wrapper for Handle encoding/decoding. -- The interface for TextEncoding changed so that a TextEncoding doesn't raise -- an exception if it encounters an invalid sequnce. Furthermore, encoding -- returns a reason as to why encoding stopped, letting us know if it was due -- to input/output underflow or an invalid sequence. -- -- This code adapts this elaborated interface back to the original TextEncoding -- interface. -- -- FIXME: it is possible that Handle code using the haDecoder/haEncoder fields -- could be made clearer by using the 'encode' interface directly. I have not -- looked into this. streamEncode :: BufferCodec from to state -> Buffer from -> Buffer to -> IO (Buffer from, Buffer to) streamEncode codec from to = fmap (\(_, from', to') -> (from', to')) $ recoveringEncode codec from to -- | Just like 'encode', but interleaves calls to 'encode' with calls to 'recover' in order to make as much progress as possible recoveringEncode :: BufferCodec from to state -> CodeBuffer from to recoveringEncode codec from to = go from to where go from to = do (why, from', to') <- encode codec from to -- When we are dealing with Handles, we don't care about input/output -- underflow particularly, and we want to delay errors about invalid -- sequences as far as possible. case why of InvalidSequence | bufL from == bufL from' -> do -- NB: it is OK to call recover here. Because we saw InvalidSequence, by the invariants -- on "encode" it must be the case that there is at least one elements available in the output -- buffer. Furthermore, clearly there is at least one element in the input buffer since we found -- something invalid there! (from', to') <- recover codec from' to' go from' to' _ -> return (why, from', to') -- ----------------------------------------------------------------------------- -- Handle Finalizers -- For a duplex handle, we arrange that the read side points to the write side -- (and hence keeps it alive if the read side is alive). This is done by -- having the haOtherSide field of the read side point to the read side. -- The finalizer is then placed on the write side, and the handle only gets -- finalized once, when both sides are no longer required. -- NOTE about finalized handles: It's possible that a handle can be -- finalized and then we try to use it later, for example if the -- handle is referenced from another finalizer, or from a thread that -- has become unreferenced and then resurrected (arguably in the -- latter case we shouldn't finalize the Handle...). Anyway, -- we try to emit a helpful message which is better than nothing. -- -- [later; 8/2010] However, a program like this can yield a strange -- error message: -- -- main = writeFile "out" loop -- loop = let x = x in x -- -- because the main thread and the Handle are both unreachable at the -- same time, the Handle may get finalized before the main thread -- receives the NonTermination exception, and the exception handler -- will then report an error. We'd rather this was not an error and -- the program just prints "<<loop>>". handleFinalizer :: FilePath -> MVar Handle__ -> IO () handleFinalizer fp m = do handle_ <- takeMVar m (handle_', _) <- hClose_help handle_ putMVar m handle_' return () -- --------------------------------------------------------------------------- -- Allocating buffers -- using an 8k char buffer instead of 32k improved performance for a -- basic "cat" program by ~30% for me. --SDM dEFAULT_CHAR_BUFFER_SIZE :: Int dEFAULT_CHAR_BUFFER_SIZE = 2048 -- 8k/sizeof(HsChar) getCharBuffer :: IODevice dev => dev -> BufferState -> IO (IORef CharBuffer, BufferMode) getCharBuffer dev state = do buffer <- newCharBuffer dEFAULT_CHAR_BUFFER_SIZE state ioref <- newIORef buffer is_tty <- IODevice.isTerminal dev let buffer_mode | is_tty = LineBuffering | otherwise = BlockBuffering Nothing return (ioref, buffer_mode) mkUnBuffer :: BufferState -> IO (IORef CharBuffer, BufferMode) mkUnBuffer state = do buffer <- newCharBuffer dEFAULT_CHAR_BUFFER_SIZE state -- See [note Buffer Sizing], GHC.IO.Handle.Types ref <- newIORef buffer return (ref, NoBuffering) -- ----------------------------------------------------------------------------- -- Flushing buffers -- | syncs the file with the buffer, including moving the -- file pointer backwards in the case of a read buffer. This can fail -- on a non-seekable read Handle. flushBuffer :: Handle__ -> IO () flushBuffer h_@Handle__{..} = do buf <- readIORef haCharBuffer case bufState buf of ReadBuffer -> do flushCharReadBuffer h_ flushByteReadBuffer h_ WriteBuffer -> do flushByteWriteBuffer h_ -- | flushes the Char buffer only. Works on all Handles. flushCharBuffer :: Handle__ -> IO () flushCharBuffer h_@Handle__{..} = do cbuf <- readIORef haCharBuffer case bufState cbuf of ReadBuffer -> do flushCharReadBuffer h_ WriteBuffer -> when (not (isEmptyBuffer cbuf)) $ error "internal IO library error: Char buffer non-empty" -- ----------------------------------------------------------------------------- -- Writing data (flushing write buffers) -- flushWriteBuffer flushes the buffer iff it contains pending write -- data. Flushes both the Char and the byte buffer, leaving both -- empty. flushWriteBuffer :: Handle__ -> IO () flushWriteBuffer h_@Handle__{..} = do buf <- readIORef haByteBuffer when (isWriteBuffer buf) $ flushByteWriteBuffer h_ flushByteWriteBuffer :: Handle__ -> IO () flushByteWriteBuffer h_@Handle__{..} = do bbuf <- readIORef haByteBuffer when (not (isEmptyBuffer bbuf)) $ do bbuf' <- Buffered.flushWriteBuffer haDevice bbuf writeIORef haByteBuffer bbuf' -- write the contents of the CharBuffer to the Handle__. -- The data will be encoded and pushed to the byte buffer, -- flushing if the buffer becomes full. writeCharBuffer :: Handle__ -> CharBuffer -> IO () writeCharBuffer h_@Handle__{..} !cbuf = do -- bbuf <- readIORef haByteBuffer debugIO ("writeCharBuffer: cbuf=" ++ summaryBuffer cbuf ++ " bbuf=" ++ summaryBuffer bbuf) (cbuf',bbuf') <- case haEncoder of Nothing -> latin1_encode cbuf bbuf Just encoder -> (streamEncode encoder) cbuf bbuf debugIO ("writeCharBuffer after encoding: cbuf=" ++ summaryBuffer cbuf' ++ " bbuf=" ++ summaryBuffer bbuf') -- flush if the write buffer is full if isFullBuffer bbuf' -- or we made no progress || not (isEmptyBuffer cbuf') && bufL cbuf' == bufL cbuf -- or the byte buffer has more elements than the user wanted buffered || (case haBufferMode of BlockBuffering (Just s) -> bufferElems bbuf' >= s NoBuffering -> True _other -> False) then do bbuf'' <- Buffered.flushWriteBuffer haDevice bbuf' writeIORef haByteBuffer bbuf'' else writeIORef haByteBuffer bbuf' if not (isEmptyBuffer cbuf') then writeCharBuffer h_ cbuf' else return () -- ----------------------------------------------------------------------------- -- Flushing read buffers -- It is always possible to flush the Char buffer back to the byte buffer. flushCharReadBuffer :: Handle__ -> IO () flushCharReadBuffer Handle__{..} = do cbuf <- readIORef haCharBuffer if isWriteBuffer cbuf || isEmptyBuffer cbuf then return () else do -- haLastDecode is the byte buffer just before we did our last batch of -- decoding. We're going to re-decode the bytes up to the current char, -- to find out where we should revert the byte buffer to. (codec_state, bbuf0) <- readIORef haLastDecode cbuf0 <- readIORef haCharBuffer writeIORef haCharBuffer cbuf0{ bufL=0, bufR=0 } -- if we haven't used any characters from the char buffer, then just -- re-install the old byte buffer. if bufL cbuf0 == 0 then do writeIORef haByteBuffer bbuf0 return () else do case haDecoder of Nothing -> do writeIORef haByteBuffer bbuf0 { bufL = bufL bbuf0 + bufL cbuf0 } -- no decoder: the number of bytes to decode is the same as the -- number of chars we have used up. Just decoder -> do debugIO ("flushCharReadBuffer re-decode, bbuf=" ++ summaryBuffer bbuf0 ++ " cbuf=" ++ summaryBuffer cbuf0) -- restore the codec state setState decoder codec_state (bbuf1,cbuf1) <- (streamEncode decoder) bbuf0 cbuf0{ bufL=0, bufR=0, bufSize = bufL cbuf0 } debugIO ("finished, bbuf=" ++ summaryBuffer bbuf1 ++ " cbuf=" ++ summaryBuffer cbuf1) writeIORef haByteBuffer bbuf1 -- When flushing the byte read buffer, we seek backwards by the number -- of characters in the buffer. The file descriptor must therefore be -- seekable: attempting to flush the read buffer on an unseekable -- handle is not allowed. flushByteReadBuffer :: Handle__ -> IO () flushByteReadBuffer h_@Handle__{..} = do bbuf <- readIORef haByteBuffer if isEmptyBuffer bbuf then return () else do seekable <- IODevice.isSeekable haDevice when (not seekable) $ ioe_cannotFlushNotSeekable let seek = negate (bufR bbuf - bufL bbuf) debugIO ("flushByteReadBuffer: new file offset = " ++ show seek) IODevice.seek haDevice RelativeSeek (fromIntegral seek) writeIORef haByteBuffer bbuf{ bufL=0, bufR=0 } -- ---------------------------------------------------------------------------- -- Making Handles mkHandle :: (IODevice dev, BufferedIO dev, Typeable dev) => dev -> FilePath -> HandleType -> Bool -- buffered? -> Maybe TextEncoding -> NewlineMode -> Maybe HandleFinalizer -> Maybe (MVar Handle__) -> IO Handle mkHandle dev filepath ha_type buffered mb_codec nl finalizer other_side = do openTextEncoding mb_codec ha_type $ \ mb_encoder mb_decoder -> do let buf_state = initBufferState ha_type bbuf <- Buffered.newBuffer dev buf_state bbufref <- newIORef bbuf last_decode <- newIORef (error "codec_state", bbuf) (cbufref,bmode) <- if buffered then getCharBuffer dev buf_state else mkUnBuffer buf_state spares <- newIORef BufferListNil newFileHandle filepath finalizer (Handle__ { haDevice = dev, haType = ha_type, haBufferMode = bmode, haByteBuffer = bbufref, haLastDecode = last_decode, haCharBuffer = cbufref, haBuffers = spares, haEncoder = mb_encoder, haDecoder = mb_decoder, haCodec = mb_codec, haInputNL = inputNL nl, haOutputNL = outputNL nl, haOtherSide = other_side }) -- | makes a new 'Handle' mkFileHandle :: (IODevice dev, BufferedIO dev, Typeable dev) => dev -- ^ the underlying IO device, which must support -- 'IODevice', 'BufferedIO' and 'Typeable' -> FilePath -- ^ a string describing the 'Handle', e.g. the file -- path for a file. Used in error messages. -> IOMode -- The mode in which the 'Handle' is to be used -> Maybe TextEncoding -- Create the 'Handle' with no text encoding? -> NewlineMode -- Translate newlines? -> IO Handle mkFileHandle dev filepath iomode mb_codec tr_newlines = do mkHandle dev filepath (ioModeToHandleType iomode) True{-buffered-} mb_codec tr_newlines (Just handleFinalizer) Nothing{-other_side-} -- | like 'mkFileHandle', except that a 'Handle' is created with two -- independent buffers, one for reading and one for writing. Used for -- full-duplex streams, such as network sockets. mkDuplexHandle :: (IODevice dev, BufferedIO dev, Typeable dev) => dev -> FilePath -> Maybe TextEncoding -> NewlineMode -> IO Handle mkDuplexHandle dev filepath mb_codec tr_newlines = do write_side@(FileHandle _ write_m) <- mkHandle dev filepath WriteHandle True mb_codec tr_newlines (Just handleFinalizer) Nothing -- no othersie read_side@(FileHandle _ read_m) <- mkHandle dev filepath ReadHandle True mb_codec tr_newlines Nothing -- no finalizer (Just write_m) return (DuplexHandle filepath read_m write_m) ioModeToHandleType :: IOMode -> HandleType ioModeToHandleType ReadMode = ReadHandle ioModeToHandleType WriteMode = WriteHandle ioModeToHandleType ReadWriteMode = ReadWriteHandle ioModeToHandleType AppendMode = AppendHandle initBufferState :: HandleType -> BufferState initBufferState ReadHandle = ReadBuffer initBufferState _ = WriteBuffer openTextEncoding :: Maybe TextEncoding -> HandleType -> (forall es ds . Maybe (TextEncoder es) -> Maybe (TextDecoder ds) -> IO a) -> IO a openTextEncoding Nothing ha_type cont = cont Nothing Nothing openTextEncoding (Just TextEncoding{..}) ha_type cont = do mb_decoder <- if isReadableHandleType ha_type then do decoder <- mkTextDecoder return (Just decoder) else return Nothing mb_encoder <- if isWritableHandleType ha_type then do encoder <- mkTextEncoder return (Just encoder) else return Nothing cont mb_encoder mb_decoder closeTextCodecs :: Handle__ -> IO () closeTextCodecs Handle__{..} = do case haDecoder of Nothing -> return (); Just d -> Encoding.close d case haEncoder of Nothing -> return (); Just d -> Encoding.close d -- --------------------------------------------------------------------------- -- closing Handles -- hClose_help is also called by lazyRead (in GHC.IO.Handle.Text) when -- EOF is read or an IO error occurs on a lazy stream. The -- semi-closed Handle is then closed immediately. We have to be -- careful with DuplexHandles though: we have to leave the closing to -- the finalizer in that case, because the write side may still be in -- use. hClose_help :: Handle__ -> IO (Handle__, Maybe SomeException) hClose_help handle_ = case haType handle_ of ClosedHandle -> return (handle_,Nothing) _ -> do mb_exc1 <- trymaybe $ flushWriteBuffer handle_ -- interruptible -- it is important that hClose doesn't fail and -- leave the Handle open (#3128), so we catch -- exceptions when flushing the buffer. (h_, mb_exc2) <- hClose_handle_ handle_ return (h_, if isJust mb_exc1 then mb_exc1 else mb_exc2) trymaybe :: IO () -> IO (Maybe SomeException) trymaybe io = (do io; return Nothing) `catchException` \e -> return (Just e) hClose_handle_ :: Handle__ -> IO (Handle__, Maybe SomeException) hClose_handle_ h_@Handle__{..} = do -- close the file descriptor, but not when this is the read -- side of a duplex handle. -- If an exception is raised by the close(), we want to continue -- to close the handle and release the lock if it has one, then -- we return the exception to the caller of hClose_help which can -- raise it if necessary. maybe_exception <- case haOtherSide of Nothing -> trymaybe $ IODevice.close haDevice Just _ -> return Nothing -- free the spare buffers writeIORef haBuffers BufferListNil writeIORef haCharBuffer noCharBuffer writeIORef haByteBuffer noByteBuffer -- release our encoder/decoder closeTextCodecs h_ -- we must set the fd to -1, because the finalizer is going -- to run eventually and try to close/unlock it. -- ToDo: necessary? the handle will be marked ClosedHandle -- XXX GHC won't let us use record update here, hence wildcards return (Handle__{ haType = ClosedHandle, .. }, maybe_exception) {-# NOINLINE noCharBuffer #-} noCharBuffer :: CharBuffer noCharBuffer = unsafePerformIO $ newCharBuffer 1 ReadBuffer {-# NOINLINE noByteBuffer #-} noByteBuffer :: Buffer Word8 noByteBuffer = unsafePerformIO $ newByteBuffer 1 ReadBuffer -- --------------------------------------------------------------------------- -- Looking ahead hLookAhead_ :: Handle__ -> IO Char hLookAhead_ handle_@Handle__{..} = do buf <- readIORef haCharBuffer -- fill up the read buffer if necessary new_buf <- if isEmptyBuffer buf then readTextDevice handle_ buf else return buf writeIORef haCharBuffer new_buf peekCharBuf (bufRaw buf) (bufL buf) -- --------------------------------------------------------------------------- -- debugging debugIO :: String -> IO () debugIO s | c_DEBUG_DUMP = do _ <- withCStringLen (s ++ "\n") $ \(p, len) -> c_write 1 (castPtr p) (fromIntegral len) return () | otherwise = return () -- ---------------------------------------------------------------------------- -- Text input/output -- Read characters into the provided buffer. Return when any -- characters are available; raise an exception if the end of -- file is reached. -- -- In uses of readTextDevice within base, the input buffer is either: -- * empty -- * or contains a single \r (when doing newline translation) -- -- The input character buffer must have a capacity at least 1 greater -- than the number of elements it currently contains. -- -- Users of this function expect that the buffer returned contains -- at least 1 more character than the input buffer. readTextDevice :: Handle__ -> CharBuffer -> IO CharBuffer readTextDevice h_@Handle__{..} cbuf = do -- bbuf0 <- readIORef haByteBuffer debugIO ("readTextDevice: cbuf=" ++ summaryBuffer cbuf ++ " bbuf=" ++ summaryBuffer bbuf0) bbuf1 <- if not (isEmptyBuffer bbuf0) then return bbuf0 else do (r,bbuf1) <- Buffered.fillReadBuffer haDevice bbuf0 if r == 0 then ioe_EOF else do -- raise EOF return bbuf1 debugIO ("readTextDevice after reading: bbuf=" ++ summaryBuffer bbuf1) (bbuf2,cbuf') <- case haDecoder of Nothing -> do writeIORef haLastDecode (error "codec_state", bbuf1) latin1_decode bbuf1 cbuf Just decoder -> do state <- getState decoder writeIORef haLastDecode (state, bbuf1) (streamEncode decoder) bbuf1 cbuf debugIO ("readTextDevice after decoding: cbuf=" ++ summaryBuffer cbuf' ++ " bbuf=" ++ summaryBuffer bbuf2) -- We can't return from readTextDevice without reading at least a single extra character, -- so check that we have managed to achieve that writeIORef haByteBuffer bbuf2 if bufR cbuf' == bufR cbuf -- we need more bytes to make a Char. NB: bbuf2 may be empty (even though bbuf1 wasn't) when we -- are using an encoding that can skip bytes without outputting characters, such as UTF8//IGNORE then readTextDevice' h_ bbuf2 cbuf else return cbuf' -- we have an incomplete byte sequence at the end of the buffer: try to -- read more bytes. readTextDevice' :: Handle__ -> Buffer Word8 -> CharBuffer -> IO CharBuffer readTextDevice' h_@Handle__{..} bbuf0 cbuf0 = do -- -- copy the partial sequence to the beginning of the buffer, so we have -- room to read more bytes. bbuf1 <- slideContents bbuf0 -- readTextDevice only calls us if we got some bytes but not some characters. -- This can't occur if haDecoder is Nothing because latin1_decode accepts all bytes. let Just decoder = haDecoder (r,bbuf2) <- Buffered.fillReadBuffer haDevice bbuf1 if r == 0 then do -- bbuf2 can be empty here when we encounter an invalid byte sequence at the end of the input -- with a //IGNORE codec which consumes bytes without outputting characters if isEmptyBuffer bbuf2 then ioe_EOF else do (bbuf3, cbuf1) <- recover decoder bbuf2 cbuf0 debugIO ("readTextDevice' after recovery: bbuf=" ++ summaryBuffer bbuf3 ++ ", cbuf=" ++ summaryBuffer cbuf1) writeIORef haByteBuffer bbuf3 -- We should recursively invoke readTextDevice after recovery, -- if recovery did not add at least one new character to the buffer: -- 1. If we were using IgnoreCodingFailure it might be the case that -- cbuf1 is the same length as cbuf0 and we need to raise ioe_EOF -- 2. If we were using TransliterateCodingFailure we might have *mutated* -- the byte buffer without changing the pointers into either buffer. -- We need to try and decode it again - it might just go through this time. if bufR cbuf1 == bufR cbuf0 then readTextDevice h_ cbuf1 else return cbuf1 else do debugIO ("readTextDevice' after reading: bbuf=" ++ summaryBuffer bbuf2) (bbuf3,cbuf1) <- do state <- getState decoder writeIORef haLastDecode (state, bbuf2) (streamEncode decoder) bbuf2 cbuf0 debugIO ("readTextDevice' after decoding: cbuf=" ++ summaryBuffer cbuf1 ++ " bbuf=" ++ summaryBuffer bbuf3) writeIORef haByteBuffer bbuf3 if bufR cbuf0 == bufR cbuf1 then readTextDevice' h_ bbuf3 cbuf1 else return cbuf1 -- Read characters into the provided buffer. Do not block; -- return zero characters instead. Raises an exception on end-of-file. readTextDeviceNonBlocking :: Handle__ -> CharBuffer -> IO CharBuffer readTextDeviceNonBlocking h_@Handle__{..} cbuf = do -- bbuf0 <- readIORef haByteBuffer when (isEmptyBuffer bbuf0) $ do (r,bbuf1) <- Buffered.fillReadBuffer0 haDevice bbuf0 if isNothing r then ioe_EOF else do -- raise EOF writeIORef haByteBuffer bbuf1 decodeByteBuf h_ cbuf -- Decode bytes from the byte buffer into the supplied CharBuffer. decodeByteBuf :: Handle__ -> CharBuffer -> IO CharBuffer decodeByteBuf h_@Handle__{..} cbuf = do -- bbuf0 <- readIORef haByteBuffer (bbuf2,cbuf') <- case haDecoder of Nothing -> do writeIORef haLastDecode (error "codec_state", bbuf0) latin1_decode bbuf0 cbuf Just decoder -> do state <- getState decoder writeIORef haLastDecode (state, bbuf0) (streamEncode decoder) bbuf0 cbuf writeIORef haByteBuffer bbuf2 return cbuf'