{-# LANGUAGE Trustworthy #-}{-# LANGUAGE NoImplicitPrelude
 , RecordWildCards
 , BangPatterns
 , NondecreasingIndentation
 , RankNTypes
 #-}{-# OPTIONS_GHC -Wno-unused-matches #-}{-# OPTIONS_GHC -Wno-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.-------------------------------------------------------------------------------moduleGHC.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_semiclosedHandle ,ioe_EOF ,ioe_notReadable ,ioe_notWritable ,ioe_finalizedHandle ,ioe_bufsiz ,hClose_help ,hLookAhead_ ,HandleFinalizer ,handleFinalizer ,debugIO ,)whereimportGHC.IO importGHC.IO.IOMode importGHC.IO.Encoding asEncodingimportGHC.IO.Encoding.Types (CodeBuffer )importGHC.IO.Handle.Types importGHC.IO.Buffer importGHC.IO.BufferedIO (BufferedIO )importGHC.IO.Exception importGHC.IO.Device (IODevice ,SeekMode (..))importqualifiedGHC.IO.Device asIODeviceimportqualifiedGHC.IO.BufferedIO asBufferedimportGHC.Conc.Sync importGHC.Real importGHC.Base importGHC.Exception importGHC.Num (Num (..))importGHC.Show importGHC.IORef importGHC.MVar importData.Typeable importData.Maybe importForeign importSystem.Posix.Internals hiding(FD )importForeign.C c_DEBUG_DUMP::Boolc_DEBUG_DUMP =False-- ----------------------------------------------------------------------------- Creating a new handletypeHandleFinalizer =FilePath ->MVar Handle__ ->IO()newFileHandle::FilePath ->Maybe HandleFinalizer ->Handle__ ->IOHandle newFileHandle filepath mb_finalizer hc =dom <-newMVar hc casemb_finalizer ofJust 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.
-}{-# INLINEwithHandle#-}withHandle::String ->Handle ->(Handle__ ->IO(Handle__ ,a ))->IOa withHandle fun h @(FileHandle _m )act =withHandle' fun h m act withHandlefun h @(DuplexHandle _m _)act =withHandle' fun h m act withHandle'::String ->Handle ->MVar Handle__ ->(Handle__ ->IO(Handle__ ,a ))->IOa withHandle' fun h m act =mask_ $ do(h' ,v )<-do_operation fun h act m checkHandleInvariants h' putMVar m h' return v {-# INLINEwithHandle_#-}withHandle_::String ->Handle ->(Handle__ ->IOa )->IOa 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__ ->IOa )->IOa withHandle_' fun h m act =withHandle' fun h m $ \h_ ->doa <-act h_ return (h_ ,a )withAllHandles__::String ->Handle ->(Handle__ ->IOHandle__ )->IO()withAllHandles__ fun h @(FileHandle _m )act =withHandle__' fun h m act withAllHandles__fun h @(DuplexHandle _r w )act =dowithHandle__' fun h r act withHandle__' fun h w act withHandle__'::String ->Handle ->MVar Handle__ ->(Handle__ ->IOHandle__ )->IO()withHandle__' fun h m act =mask_ $ doh' <-do_operation fun h act m checkHandleInvariants h' putMVar m h' return ()do_operation::String ->Handle ->(Handle__ ->IOa )->MVar Handle__ ->IOa do_operation fun h act m =doh_ <-takeMVar m checkHandleInvariants h_ act h_ `catchException `handler h_ wherehandler h_ e =doputMVar 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/writeTextDeviceaugmentIOError::IOException ->String ->Handle ->IOException augmentIOError ioe @IOError {ioe_filename=fp }fun h =ioe {ioe_handle=Just h ,ioe_location=fun ,ioe_filename=filepath }wherefilepath |Just _<-fp =fp |otherwise =caseh ofFileHandle path _->Just path DuplexHandle path __->Just path -- ----------------------------------------------------------------------------- Wrapper for write operations.wantWritableHandle::String ->Handle ->(Handle__ ->IOa )->IOa wantWritableHandle fun h @(FileHandle _m )act =wantWritableHandle' fun h m act wantWritableHandlefun 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__ ->IOa )->IOa wantWritableHandle' fun h m act =withHandle_' fun h m (checkWritableHandle act )checkWritableHandle::(Handle__ ->IOa )->Handle__ ->IOa checkWritableHandle act h_ @Handle__ {..}=casehaType ofClosedHandle ->ioe_closedHandle SemiClosedHandle ->ioe_semiclosedHandle ReadHandle ->ioe_notWritable ReadWriteHandle ->dobuf <-readIORef haCharBuffer when (not(isWriteBuffer buf ))$ doflushCharReadBuffer 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 ))->IOa wantReadableHandle fun h act =withHandle fun h (checkReadableHandle act )wantReadableHandle_::String ->Handle ->(Handle__ ->IOa )->IOa 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__ ->IOa )->IOa wantReadableHandle' fun h m act =withHandle_' fun h m (checkReadableHandle act )checkReadableHandle::(Handle__ ->IOa )->Handle__ ->IOa checkReadableHandle act h_ @Handle__ {..}=casehaType ofClosedHandle ->ioe_closedHandle SemiClosedHandle ->ioe_semiclosedHandle 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 )$ dowhen (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__ ->IOa )->IOa wantSeekableHandle fun h @(DuplexHandle ___)_act =ioException (IOError (Just h )IllegalOperation fun "handle is not seekable"Nothing Nothing )wantSeekableHandlefun h @(FileHandle _m )act =withHandle_' fun h m (checkSeekableHandle act )checkSeekableHandle::(Handle__ ->IOa )->Handle__ ->IOa checkSeekableHandle act handle_ @Handle__ {haDevice=dev }=casehaTypehandle_ ofClosedHandle ->ioe_closedHandle SemiClosedHandle ->ioe_semiclosedHandle AppendHandle ->ioe_notSeekable _->dob <-IODevice.isSeekable dev ifb thenact handle_ elseioe_notSeekable -- ------------------------------------------------------------------------------- Handy IOErrorsioe_closedHandle,ioe_semiclosedHandle,ioe_EOF,ioe_notReadable,ioe_notWritable,ioe_cannotFlushNotSeekable,ioe_notSeekable::IOa ioe_closedHandle =ioException (IOError Nothing IllegalOperation """handle is closed"Nothing Nothing )ioe_semiclosedHandle =ioException (IOError Nothing IllegalOperation """handle is semi-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->IOa ioe_bufsiz n =ioException (IOError Nothing InvalidArgument "hSetBuffering"("illegal buffer size "++ showsPrec 9n [])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 possiblerecoveringEncode::BufferCodec from to state ->CodeBuffer from to recoveringEncode codec from to =go from to wherego from to =do(why ,from' ,to' )<-encodecodec 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.casewhy ofInvalidSequence |bufLfrom ==bufLfrom' ->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' )<-recovercodec 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 =dohandle_ <-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. --SDMdEFAULT_CHAR_BUFFER_SIZE::IntdEFAULT_CHAR_BUFFER_SIZE =2048-- 8k/sizeof(HsChar)getCharBuffer::IODevice dev =>dev ->BufferState ->IO(IORef CharBuffer ,BufferMode )getCharBuffer dev state =dobuffer <-newCharBuffer dEFAULT_CHAR_BUFFER_SIZE state ioref <-newIORef buffer is_tty <-IODevice.isTerminal dev letbuffer_mode |is_tty =LineBuffering |otherwise =BlockBuffering Nothing return (ioref ,buffer_mode )mkUnBuffer::BufferState ->IO(IORef CharBuffer ,BufferMode )mkUnBuffer state =dobuffer <-newCharBuffer dEFAULT_CHAR_BUFFER_SIZE state -- See [note Buffer Sizing], GHC.IO.Handle.Typesref <-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__ {..}=dobuf <-readIORef haCharBuffer casebufStatebuf ofReadBuffer ->doflushCharReadBuffer h_ flushByteReadBuffer h_ WriteBuffer ->doflushByteWriteBuffer h_ -- | flushes the Char buffer only. Works on all Handles.flushCharBuffer::Handle__ ->IO()flushCharBuffer h_ @Handle__ {..}=docbuf <-readIORef haCharBuffer casebufStatecbuf ofReadBuffer ->doflushCharReadBuffer h_ WriteBuffer ->-- Nothing to do here. Char buffer on a write Handle is always empty-- between Handle operations.-- See [note Buffer Flushing], GHC.IO.Handle.Types.when (not(isEmptyBuffer cbuf ))$ error "internal IO library error: Char buffer non-empty"-- ------------------------------------------------------------------------------- Writing data (flushing write buffers)-- flushWriteBuffer flushes the byte buffer iff it contains pending write-- data. Because the Char buffer on a write Handle is always empty between-- Handle operations (see [note Buffer Flushing], GHC.IO.Handle.Types),-- both buffers are empty after this.flushWriteBuffer::Handle__ ->IO()flushWriteBuffer h_ @Handle__ {..}=dobuf <-readIORef haByteBuffer when (isWriteBuffer buf )$ flushByteWriteBuffer h_ flushByteWriteBuffer::Handle__ ->IO()flushByteWriteBuffer h_ @Handle__ {..}=dobbuf <-readIORef haByteBuffer when (not(isEmptyBuffer bbuf ))$ dobbuf' <-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' )<-casehaEncoder ofNothing ->latin1_encode cbuf bbuf Just encoder ->(streamEncode encoder )cbuf bbuf debugIO ("writeCharBuffer after encoding: cbuf="++ summaryBuffer cbuf' ++ " bbuf="++ summaryBuffer bbuf' )-- flush the byte buffer if it is fullifisFullBuffer bbuf' -- or we made no progress||not(isEmptyBuffer cbuf' )&&bufLcbuf' ==bufLcbuf -- or the byte buffer has more elements than the user wanted buffered||(casehaBufferMode ofBlockBuffering (Just s )->bufferElems bbuf' >=s NoBuffering ->True_other ->False)thendobbuf'' <-Buffered.flushWriteBuffer haDevice bbuf' writeIORef haByteBuffer bbuf'' elsewriteIORef haByteBuffer bbuf' ifnot(isEmptyBuffer cbuf' )thenwriteCharBuffer h_ cbuf' elsereturn ()-- ------------------------------------------------------------------------------- Flushing read buffers-- It is always possible to flush the Char buffer back to the byte buffer.flushCharReadBuffer::Handle__ ->IO()flushCharReadBuffer Handle__ {..}=docbuf <-readIORef haCharBuffer ifisWriteBuffer cbuf ||isEmptyBuffer cbuf thenreturn ()elsedo-- 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.ifbufLcbuf0 ==0thendowriteIORef haByteBuffer bbuf0 return ()elsedocasehaDecoder ofNothing ->dowriteIORef haByteBuffer bbuf0 {bufL=bufLbbuf0 + bufLcbuf0 }-- no decoder: the number of bytes to decode is the same as the-- number of chars we have used up.Just decoder ->dodebugIO ("flushCharReadBuffer re-decode, bbuf="++ summaryBuffer bbuf0 ++ " cbuf="++ summaryBuffer cbuf0 )-- restore the codec statesetStatedecoder codec_state (bbuf1 ,cbuf1 )<-(streamEncode decoder )bbuf0 cbuf0 {bufL=0,bufR=0,bufSize=bufLcbuf0 }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__ {..}=dobbuf <-readIORef haByteBuffer ifisEmptyBuffer bbuf thenreturn ()elsedoseekable <-IODevice.isSeekable haDevice when (notseekable )$ ioe_cannotFlushNotSeekable letseek =negate (bufRbbuf -bufLbbuf )debugIO ("flushByteReadBuffer: new file offset = "++ show seek )IODevice.seek haDevice RelativeSeek (fromIntegral seek )writeIORef haByteBuffer bbuf {bufL=0,bufR=0}-- ------------------------------------------------------------------------------ Making HandlesmkHandle::(IODevice dev ,BufferedIO dev ,Typeable dev )=>dev ->FilePath ->HandleType ->Bool-- buffered?->Maybe TextEncoding ->NewlineMode ->Maybe HandleFinalizer ->Maybe (MVar Handle__ )->IOHandle mkHandle dev filepath ha_type buffered mb_codec nl finalizer other_side =doopenTextEncoding mb_codec ha_type $ \mb_encoder mb_decoder ->doletbuf_state =initBufferState ha_type bbuf <-Buffered.newBuffer dev buf_state bbufref <-newIORef bbuf last_decode <-newIORef (errorWithoutStackTrace "codec_state",bbuf )(cbufref ,bmode )<-ifbuffered thengetCharBuffer dev buf_state elsemkUnBuffer 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=inputNLnl ,haOutputNL=outputNLnl ,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?->IOHandle mkFileHandle dev filepath iomode mb_codec tr_newlines =domkHandle 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 ->IOHandle mkDuplexHandle dev filepath mb_codec tr_newlines =dowrite_side @(FileHandle _write_m )<-mkHandle dev filepath WriteHandle Truemb_codec tr_newlines (Just handleFinalizer )Nothing -- no othersieread_side @(FileHandle _read_m )<-mkHandle dev filepath ReadHandle Truemb_codec tr_newlines Nothing -- no finalizer(Just write_m )return (DuplexHandle filepath read_m write_m )ioModeToHandleType::IOMode ->HandleType ioModeToHandleType ReadMode =ReadHandle ioModeToHandleTypeWriteMode =WriteHandle ioModeToHandleTypeReadWriteMode =ReadWriteHandle ioModeToHandleTypeAppendMode =AppendHandle initBufferState::HandleType ->BufferState initBufferState ReadHandle =ReadBuffer initBufferState_=WriteBuffer openTextEncoding::Maybe TextEncoding ->HandleType ->(foralles ds .Maybe (TextEncoder es )->Maybe (TextDecoder ds )->IOa )->IOa openTextEncoding Nothing ha_type cont =cont Nothing Nothing openTextEncoding(Just TextEncoding {..})ha_type cont =domb_decoder <-ifisReadableHandleType ha_type thendodecoder <-mkTextDecoder return (Just decoder )elsereturn Nothing mb_encoder <-ifisWritableHandleType ha_type thendoencoder <-mkTextEncoder return (Just encoder )elsereturn Nothing cont mb_encoder mb_decoder closeTextCodecs::Handle__ ->IO()closeTextCodecs Handle__ {..}=docasehaDecoder ofNothing ->return ();Just d ->Encoding.closed casehaEncoder ofNothing ->return ();Just d ->Encoding.closed -- ----------------------------------------------------------------------------- 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_ =casehaTypehandle_ ofClosedHandle ->return (handle_ ,Nothing )_->domb_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_ ,ifisJust mb_exc1 thenmb_exc1 elsemb_exc2 )trymaybe::IO()->IO(Maybe SomeException )trymaybe io =(doio ;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 <-casehaOtherSide ofNothing ->trymaybe $ IODevice.close haDevice Just _->return Nothing -- free the spare bufferswriteIORef haBuffers BufferListNil writeIORef haCharBuffer noCharBuffer writeIORef haByteBuffer noByteBuffer -- release our encoder/decodercloseTextCodecs 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 wildcardsreturn (Handle__ {haType=ClosedHandle ,..},maybe_exception ){-# NOINLINEnoCharBuffer#-}noCharBuffer::CharBuffer noCharBuffer =unsafePerformIO $ newCharBuffer 1ReadBuffer {-# NOINLINEnoByteBuffer#-}noByteBuffer::Buffer Word8 noByteBuffer =unsafePerformIO $ newByteBuffer 1ReadBuffer -- ----------------------------------------------------------------------------- Looking aheadhLookAhead_::Handle__ ->IOCharhLookAhead_ handle_ @Handle__ {..}=dobuf <-readIORef haCharBuffer -- fill up the read buffer if necessarynew_buf <-ifisEmptyBuffer buf thenreadTextDevice handle_ buf elsereturn buf writeIORef haCharBuffer new_buf peekCharBuf (bufRawbuf )(bufLbuf )-- ----------------------------------------------------------------------------- debuggingdebugIO::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 ->IOCharBuffer readTextDevice h_ @Handle__ {..}cbuf =do--bbuf0 <-readIORef haByteBuffer debugIO ("readTextDevice: cbuf="++ summaryBuffer cbuf ++ " bbuf="++ summaryBuffer bbuf0 )bbuf1 <-ifnot(isEmptyBuffer bbuf0 )thenreturn bbuf0 elsedo(r ,bbuf1 )<-Buffered.fillReadBuffer haDevice bbuf0 ifr ==0thenioe_EOF elsedo-- raise EOFreturn bbuf1 debugIO ("readTextDevice after reading: bbuf="++ summaryBuffer bbuf1 )(bbuf2 ,cbuf' )<-casehaDecoder ofNothing ->dowriteIORef haLastDecode (errorWithoutStackTrace "codec_state",bbuf1 )latin1_decode bbuf1 cbuf Just decoder ->dostate <-getStatedecoder 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 thatwriteIORef haByteBuffer bbuf2 ifbufRcbuf' ==bufRcbuf -- 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//IGNOREthenreadTextDevice' h_ bbuf2 cbuf elsereturn cbuf' -- we have an incomplete byte sequence at the end of the buffer: try to-- read more bytes.readTextDevice'::Handle__ ->Buffer Word8 ->CharBuffer ->IOCharBuffer 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.letJust decoder =haDecoder (r ,bbuf2 )<-Buffered.fillReadBuffer haDevice bbuf1 ifr ==0thendo-- 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 charactersifisEmptyBuffer bbuf2 thenioe_EOF elsedo(bbuf3 ,cbuf1 )<-recoverdecoder 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.ifbufRcbuf1 ==bufRcbuf0 thenreadTextDevice h_ cbuf1 elsereturn cbuf1 elsedodebugIO ("readTextDevice' after reading: bbuf="++ summaryBuffer bbuf2 )(bbuf3 ,cbuf1 )<-dostate <-getStatedecoder writeIORef haLastDecode (state ,bbuf2 )(streamEncode decoder )bbuf2 cbuf0 debugIO ("readTextDevice' after decoding: cbuf="++ summaryBuffer cbuf1 ++ " bbuf="++ summaryBuffer bbuf3 )writeIORef haByteBuffer bbuf3 ifbufRcbuf0 ==bufRcbuf1 thenreadTextDevice' h_ bbuf3 cbuf1 elsereturn cbuf1 -- Read characters into the provided buffer. Do not block;-- return zero characters instead. Raises an exception on end-of-file.readTextDeviceNonBlocking::Handle__ ->CharBuffer ->IOCharBuffer readTextDeviceNonBlocking h_ @Handle__ {..}cbuf =do--bbuf0 <-readIORef haByteBuffer when (isEmptyBuffer bbuf0 )$ do(r ,bbuf1 )<-Buffered.fillReadBuffer0 haDevice bbuf0 ifisNothing r thenioe_EOF elsedo-- raise EOFwriteIORef haByteBuffer bbuf1 decodeByteBuf h_ cbuf -- Decode bytes from the byte buffer into the supplied CharBuffer.decodeByteBuf::Handle__ ->CharBuffer ->IOCharBuffer decodeByteBuf h_ @Handle__ {..}cbuf =do--bbuf0 <-readIORef haByteBuffer (bbuf2 ,cbuf' )<-casehaDecoder ofNothing ->dowriteIORef haLastDecode (errorWithoutStackTrace "codec_state",bbuf0 )latin1_decode bbuf0 cbuf Just decoder ->dostate <-getStatedecoder writeIORef haLastDecode (state ,bbuf0 )(streamEncode decoder )bbuf0 cbuf writeIORef haByteBuffer bbuf2 return cbuf'