module PrelHandle where
import PrelBase
-import PrelArr ( newVar, readVar, writeVar, ByteArray )
+import PrelAddr ( Addr, nullAddr )
+import PrelArr ( newVar, readVar, writeVar, ByteArray(..) )
import PrelRead ( Read )
import PrelList ( span )
import PrelIOBase
-import PrelException ( throw, ioError, catchException )
+import PrelException
import PrelMaybe ( Maybe(..) )
+import PrelEnum
+import PrelNum
+import PrelShow
import PrelAddr ( Addr, nullAddr )
-import PrelBounded () -- get at Bounded Int instance.
import PrelNum ( toInteger, toBig )
+import PrelPack ( packString )
import PrelWeak ( addForeignFinalizer )
+import Ix
+
#if __CONCURRENT_HASKELL__
import PrelConc
#endif
-import Ix
#ifndef __PARALLEL_HASKELL__
import PrelForeign ( makeForeignObj )
#endif /* ndef(__HUGS__) */
#ifdef __HUGS__
-#define cat2(x,y) x/**/y
+#define cat2(x,y) x##y
#define CCALL(fun) cat2(prim_,fun)
#define __CONCURRENT_HASKELL__
#define stToIO id
\begin{code}
{-# INLINE newHandle #-}
{-# INLINE withHandle #-}
-{-# INLINE writeHandle #-}
newHandle :: Handle__ -> IO Handle
-withHandle :: Handle -> (Handle__ -> IO a) -> IO a
-writeHandle :: Handle -> Handle__ -> IO ()
#if defined(__CONCURRENT_HASKELL__)
-- Use MVars for concurrent Haskell
newHandle hc = newMVar hc >>= \ h ->
return (Handle h)
+#else
+
+-- Use ordinary MutableVars for non-concurrent Haskell
+newHandle hc = stToIO (newVar hc >>= \ h ->
+ return (Handle h))
+#endif
+\end{code}
- -- withHandle grabs the handle lock, performs
- -- some operation over it, making sure that we
- -- unlock & reset the handle state should an
- -- exception occur while performing said op.
+%*********************************************************
+%* *
+\subsection{@withHandle@ operations}
+%* *
+%*********************************************************
+
+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
+orignal handle is always replaced [ this is the case at the moment,
+but we might want to revisit this in the future --SDM ].
+
+\begin{code}
+#ifdef __CONCURRENT_HASKELL__
+withHandle :: Handle -> (Handle__ -> IO (Handle__,a)) -> IO a
withHandle (Handle h) act = do
h_ <- takeMVar h
+ (h',v) <- catchException (act h_) (\ ex -> putMVar h h_ >> throw ex)
+ putMVar h h'
+ return v
+
+withHandle_ :: Handle -> (Handle__ -> IO a) -> IO a
+withHandle_ (Handle h) act = do
+ h_ <- takeMVar h
v <- catchException (act h_) (\ ex -> putMVar h h_ >> throw ex)
+ putMVar h h_
return v
-writeHandle (Handle h) hc = putMVar h hc
-#else
-
--- Use ordinary MutableVars for non-concurrent Haskell
-newHandle hc = stToIO (newVar hc >>= \ h ->
- return (Handle h))
+withHandle__ :: Handle -> (Handle__ -> IO Handle__) -> IO ()
+withHandle__ (Handle h) act = do
+ h_ <- takeMVar h
+ h' <- catchException (act h_) (\ ex -> putMVar h h_ >> throw ex)
+ putMVar h h'
+ return ()
+#else
-- of questionable value to install this exception
-- handler, but let's do it in the non-concurrent
-- case too, for now.
v <- catchException (act h_) (\ ex -> stToIO (writeVar h h_) >> throw ex)
return v
-writeHandle (Handle h) hc = stToIO (writeVar h hc)
#endif
\end{code}
hClose :: Handle -> IO ()
hClose handle =
- withHandle handle $ \ handle_ -> do
+ withHandle__ handle $ \ handle_ -> do
case haType__ handle_ of
- ErrorHandle theError -> do
- writeHandle handle handle_
- ioError theError
- ClosedHandle -> do
- writeHandle handle handle_
- ioe_closedHandle "hClose" handle
+ ErrorHandle theError -> ioError theError
+ ClosedHandle -> return handle_
_ -> do
rc <- CCALL(closeFile) (haFO__ handle_) (1::Int){-flush if you can-} -- ConcHask: SAFE, won't block
{- We explicitly close a file object so that we can be told
FileObject with a NULL as part of closeFile())
-}
if rc == (0::Int)
- then
- writeHandle handle (handle_{ haType__ = ClosedHandle,
- haFO__ = nullFile__ })
- else do
- writeHandle handle handle_
- constructErrorAndFail "hClose"
+ then return (handle_{ haType__ = ClosedHandle,
+ haFO__ = nullFile__ })
+ else constructErrorAndFail "hClose"
\end{code}
\begin{code}
hFileSize :: Handle -> IO Integer
hFileSize handle =
- withHandle handle $ \ handle_ -> do
+ withHandle_ handle $ \ handle_ -> do
case haType__ handle_ of
- ErrorHandle theError -> do
- writeHandle handle handle_
- ioError theError
- ClosedHandle -> do
- writeHandle handle handle_
- ioe_closedHandle "hFileSize" handle
- SemiClosedHandle -> do
- writeHandle handle handle_
- ioe_closedHandle "hFileSize" handle
+ ErrorHandle theError -> ioError theError
+ ClosedHandle -> ioe_closedHandle "hFileSize" handle
+ SemiClosedHandle -> ioe_closedHandle "hFileSize" handle
#ifdef __HUGS__
_ -> do
mem <- primNewByteArray sizeof_int64
rc <- CCALL(fileSize_int64) (haFO__ handle_) mem -- ConcHask: SAFE, won't block
- writeHandle handle handle_
if rc == 0 then do
result <- primReadInt64Array mem 0
return (primInt64ToInteger result)
case int2Integer# hack# of
(# s, d #) -> do
rc <- CCALL(fileSize) (haFO__ handle_) d -- ConcHask: SAFE, won't block
- writeHandle handle handle_
if rc == (0::Int) then
return (J# s d)
else
wantReadableHandle "hIsEOF" handle $ \ handle_ -> do
let fo = haFO__ handle_
rc <- mayBlock fo (CCALL(fileEOF) fo) -- ConcHask: UNSAFE, may block
- writeHandle handle handle_
case rc of
0 -> return False
1 -> return True
"hSetBuffering"
("illegal buffer size " ++ showsPrec 9 n [])) -- 9 => should be parens'ified.
_ ->
- withHandle handle $ \ handle_ -> do
+ withHandle__ handle $ \ handle_ -> do
case haType__ handle_ of
- ErrorHandle theError -> do
- writeHandle handle handle_
- ioError theError
- ClosedHandle -> do
- writeHandle handle handle_
- ioe_closedHandle "hSetBuffering" handle
+ ErrorHandle theError -> ioError theError
+ ClosedHandle -> ioe_closedHandle "hSetBuffering" handle
_ -> do
{- Note:
- we flush the old buffer regardless of whether
rc <- mayBlock fo (CCALL(setBuffering) fo bsize) -- ConcHask: UNSAFE, may block
if rc == 0
then do
- writeHandle handle (handle_{ haBufferMode__ = mode })
+ return (handle_{ haBufferMode__ = mode })
else do
-- Note: failure to change the buffer size will cause old buffer to be flushed.
- writeHandle handle handle_
constructErrorAndFail "hSetBuffering"
where
bsize :: Int
wantWriteableHandle "hFlush" handle $ \ handle_ -> do
let fo = haFO__ handle_
rc <- mayBlock fo (CCALL(flushFile) fo) -- ConcHask: UNSAFE, may block
- writeHandle handle handle_
if rc == 0 then
return ()
else
hGetPosn handle =
wantSeekableHandle "hGetPosn" handle $ \ handle_ -> do
posn <- CCALL(getFilePosn) (haFO__ handle_) -- ConcHask: SAFE, won't block
- writeHandle handle handle_
- if posn /= -1 then
+ if posn /= -1 then do
return (HandlePosn handle posn)
else
constructErrorAndFail "hGetPosn"
wantSeekableHandle "hSetPosn" handle $ \ handle_ -> do -- not as silly as it looks: the handle may have been closed in the meantime.
let fo = haFO__ handle_
rc <- mayBlock fo (CCALL(setFilePosn) fo posn) -- ConcHask: UNSAFE, may block
- writeHandle handle handle_
- if rc == 0 then
+ if rc == 0 then do
return ()
else
constructErrorAndFail "hSetPosn"
let fo = haFO__ handle_
rc <- mayBlock fo (CCALL(seekFile) fo whence (I# s#) d#) -- ConcHask: UNSAFE, may block
#endif
- writeHandle handle handle_
- if rc == 0 then
+ if rc == 0 then do
return ()
else
constructErrorAndFail "hSeek"
\begin{code}
hIsOpen :: Handle -> IO Bool
hIsOpen handle =
- withHandle handle $ \ handle_ -> do
+ withHandle_ handle $ \ handle_ -> do
case haType__ handle_ of
- ErrorHandle theError -> do
- writeHandle handle handle_
- ioError theError
- ClosedHandle -> do
- writeHandle handle handle_
- return False
- SemiClosedHandle -> do
- writeHandle handle handle_
- return False
- _ -> do
- writeHandle handle handle_
- return True
+ ErrorHandle theError -> ioError theError
+ ClosedHandle -> return False
+ SemiClosedHandle -> return False
+ _ -> return True
hIsClosed :: Handle -> IO Bool
hIsClosed handle =
- withHandle handle $ \ handle_ -> do
+ withHandle_ handle $ \ handle_ -> do
case haType__ handle_ of
- ErrorHandle theError -> do
- writeHandle handle handle_
- ioError theError
- ClosedHandle -> do
- writeHandle handle handle_
- return True
- _ -> do
- writeHandle handle handle_
- return False
+ ErrorHandle theError -> ioError theError
+ ClosedHandle -> return True
+ _ -> return False
{- not defined, nor exported, but mentioned
here for documentation purposes:
hIsReadable :: Handle -> IO Bool
hIsReadable handle =
- withHandle handle $ \ handle_ -> do
+ withHandle_ handle $ \ handle_ -> do
case haType__ handle_ of
- ErrorHandle theError -> do
- writeHandle handle handle_
- ioError theError
- ClosedHandle -> do
- writeHandle handle handle_
- ioe_closedHandle "hIsReadable" handle
- SemiClosedHandle -> do
- writeHandle handle handle_
- ioe_closedHandle "hIsReadable" handle
- htype -> do
- writeHandle handle handle_
- return (isReadable htype)
+ ErrorHandle theError -> ioError theError
+ ClosedHandle -> ioe_closedHandle "hIsReadable" handle
+ SemiClosedHandle -> ioe_closedHandle "hIsReadable" handle
+ htype -> return (isReadable htype)
where
isReadable ReadHandle = True
isReadable ReadWriteHandle = True
hIsWritable :: Handle -> IO Bool
hIsWritable handle =
- withHandle handle $ \ handle_ -> do
+ withHandle_ handle $ \ handle_ -> do
case haType__ handle_ of
- ErrorHandle theError -> do
- writeHandle handle handle_
- ioError theError
- ClosedHandle -> do
- writeHandle handle handle_
- ioe_closedHandle "hIsWritable" handle
- SemiClosedHandle -> do
- writeHandle handle handle_
- ioe_closedHandle "hIsWritable" handle
- htype -> do
- writeHandle handle handle_
- return (isWritable htype)
+ ErrorHandle theError -> ioError theError
+ ClosedHandle -> ioe_closedHandle "hIsWritable" handle
+ SemiClosedHandle -> ioe_closedHandle "hIsWritable" handle
+ htype -> return (isWritable htype)
where
isWritable AppendHandle = True
isWritable WriteHandle = True
\begin{code}
hGetBuffering :: Handle -> IO BufferMode
hGetBuffering handle =
- withHandle handle $ \ handle_ -> do
+ withHandle_ handle $ \ handle_ -> do
case haType__ handle_ of
- ErrorHandle theError -> do
- writeHandle handle handle_
- ioError theError
- ClosedHandle -> do
- writeHandle handle handle_
- ioe_closedHandle "hGetBuffering" handle
- _ -> do
+ ErrorHandle theError -> ioError theError
+ ClosedHandle -> ioe_closedHandle "hGetBuffering" handle
+ _ ->
{-
We're being non-standard here, and allow the buffering
of a semi-closed handle to be queried. -- sof 6/98
-}
- let v = haBufferMode__ handle_
- writeHandle handle handle_
- return v -- could be stricter..
-
+ return (haBufferMode__ handle_) -- could be stricter..
\end{code}
\begin{code}
hIsSeekable :: Handle -> IO Bool
hIsSeekable handle =
- withHandle handle $ \ handle_ -> do
+ withHandle_ handle $ \ handle_ -> do
case haType__ handle_ of
- ErrorHandle theError -> do
- writeHandle handle handle_
- ioError theError
- ClosedHandle -> do
- writeHandle handle handle_
- ioe_closedHandle "hIsSeekable" handle
- SemiClosedHandle -> do
- writeHandle handle handle_
- ioe_closedHandle "hIsSeekable" handle
- AppendHandle -> do
- writeHandle handle handle_
- return False
+ ErrorHandle theError -> ioError theError
+ ClosedHandle -> ioe_closedHandle "hIsSeekable" handle
+ SemiClosedHandle -> ioe_closedHandle "hIsSeekable" handle
+ AppendHandle -> return False
_ -> do
rc <- CCALL(seekFileP) (haFO__ handle_) -- ConcHask: SAFE, won't block
- writeHandle handle handle_
case (rc::Int) of
0 -> return False
1 -> return True
if not isT
then return ()
else
- withHandle handle $ \ handle_ -> do
+ withHandle_ handle $ \ handle_ -> do
case haType__ handle_ of
- ErrorHandle theError -> do
- writeHandle handle handle_
- ioError theError
- ClosedHandle -> do
- writeHandle handle handle_
- ioe_closedHandle "hSetEcho" handle
+ ErrorHandle theError -> ioError theError
+ ClosedHandle -> ioe_closedHandle "hSetEcho" handle
_ -> do
rc <- CCALL(setTerminalEcho) (haFO__ handle_) ((if on then 1 else 0)::Int) -- ConcHask: SAFE, won't block
- writeHandle handle handle_
if rc /= ((-1)::Int)
then return ()
else constructErrorAndFail "hSetEcho"
if not isT
then return False
else
- withHandle handle $ \ handle_ -> do
+ withHandle_ handle $ \ handle_ -> do
case haType__ handle_ of
- ErrorHandle theError -> do
- writeHandle handle handle_
- ioError theError
- ClosedHandle -> do
- writeHandle handle handle_
- ioe_closedHandle "hGetEcho" handle
+ ErrorHandle theError -> ioError theError
+ ClosedHandle -> ioe_closedHandle "hGetEcho" handle
_ -> do
rc <- CCALL(getTerminalEcho) (haFO__ handle_) -- ConcHask: SAFE, won't block
- writeHandle handle handle_
case (rc::Int) of
1 -> return True
0 -> return False
hIsTerminalDevice :: Handle -> IO Bool
hIsTerminalDevice handle = do
- withHandle handle $ \ handle_ -> do
- case haType__ handle_ of
- ErrorHandle theError -> do
- writeHandle handle handle_
- ioError theError
- ClosedHandle -> do
- writeHandle handle handle_
- ioe_closedHandle "hIsTerminalDevice" handle
+ withHandle_ handle $ \ handle_ -> do
+ case haType__ handle_ of
+ ErrorHandle theError -> ioError theError
+ ClosedHandle -> ioe_closedHandle "hIsTerminalDevice" handle
_ -> do
rc <- CCALL(isTerminalDevice) (haFO__ handle_) -- ConcHask: SAFE, won't block
- writeHandle handle handle_
case (rc::Int) of
1 -> return True
0 -> return False
hConnectTo hW hR = hConnectHdl_ hW hR 0{-connect regardless-}
hConnectHdl_ :: Handle -> Handle -> Int -> IO ()
-hConnectHdl_ hW hR is_tty =
- wantRWHandle "hConnectTo" hW $ \ hW_ -> do
+hConnectHdl_ hW hR is_tty =
+ wantRWHandle "hConnectTo" hW $ \ hW_ ->
wantRWHandle "hConnectTo" hR $ \ hR_ -> do
CCALL(setConnectedTo) (haFO__ hR_) (haFO__ hW_) is_tty -- ConcHask: SAFE, won't block
- writeHandle hR hR_
- writeHandle hW hW_
#ifndef __PARALLEL_HASKELL__
#define FILE_OBJECT ForeignObj
hUngetChar handle c =
wantReadableHandle "hLookAhead" handle $ \ handle_ -> do
rc <- CCALL(ungetChar) (haFO__ handle_) c -- ConcHask: SAFE, won't block
- writeHandle handle handle_
if rc == ((-1)::Int)
then constructErrorAndFail "hUngetChar"
else return ()
then do
hClose handle
constructErrorAndFail "slurpFile"
- else
- withHandle handle $ \ handle_ -> do
- let fo = haFO__ handle_
- rc <- mayBlock fo (CCALL(readChunk) fo chunk sz_i) -- ConcHask: UNSAFE, may block.
- writeHandle handle handle_
+ else do
+ rc <- withHandle_ handle ( \ handle_ -> do
+ let fo = haFO__ handle_
+ mayBlock fo (CCALL(readChunk) fo chunk sz_i) -- ConcHask: UNSAFE, may block.
+ )
hClose handle
if rc < (0::Int)
then constructErrorAndFail "slurpFile"
#else
rc <- mayBlock fo (CCALL(readChunk) fo buf sz) -- ConcHask: UNSAFE, may block.
#endif
- writeHandle handle handle_
if rc >= (0::Int)
then return rc
else constructErrorAndFail "hFillBufBA"
wantReadableHandle "hFillBuf" handle $ \ handle_ -> do
let fo = haFO__ handle_
rc <- mayBlock fo (CCALL(readChunk) fo buf sz) -- ConcHask: UNSAFE, may block.
- writeHandle handle handle_
if rc >= 0
then return rc
else constructErrorAndFail "hFillBuf"
wantWriteableHandle "hPutBuf" handle $ \ handle_ -> do
let fo = haFO__ handle_
rc <- mayBlock fo (CCALL(writeBuf) fo buf len) -- ConcHask: UNSAFE, may block.
- writeHandle handle handle_
if rc == (0::Int)
then return ()
else constructErrorAndFail "hPutBuf"
wantWriteableHandle "hPutBufBA" handle $ \ handle_ -> do
let fo = haFO__ handle_
rc <- mayBlock fo (CCALL(writeBufBA) fo buf len) -- ConcHask: UNSAFE, may block.
- writeHandle handle handle_
if rc == (0::Int)
then return ()
else constructErrorAndFail "hPutBuf"
\begin{code}
getHandleFd :: Handle -> IO Int
-getHandleFd handle = do
- withHandle handle $ \ handle_ -> do
+getHandleFd handle =
+ withHandle_ handle $ \ handle_ -> do
case (haType__ handle_) of
- ErrorHandle theError -> do
- writeHandle handle handle_
- ioError theError
- ClosedHandle -> do
- writeHandle handle handle_
- ioe_closedHandle "getHandleFd" handle
+ ErrorHandle theError -> ioError theError
+ ClosedHandle -> ioe_closedHandle "getHandleFd" handle
_ -> do
fd <- CCALL(getFileFd) (haFO__ handle_)
- writeHandle handle handle_
return fd
\end{code}
\end{code}
+'Top-level' IO actions want to catch exceptions (e.g., forkIO and
+PrelMain.mainIO) and report them - topHandler is the exception
+handler they should use for this:
+
+\begin{code}
+-- make sure we handle errors while reporting the error!
+-- (e.g. evaluating the string passed to 'error' might generate
+-- another error, etc.)
+topHandler :: Bool -> Exception -> IO ()
+topHandler bombOut err = catchException (real_handler bombOut err) (topHandler bombOut)
+
+real_handler :: Bool -> Exception -> IO ()
+real_handler bombOut ex =
+ case ex of
+ AsyncException StackOverflow -> reportStackOverflow bombOut
+ ErrorCall s -> reportError bombOut s
+ other -> reportError bombOut (showsPrec 0 other "\n")
+
+reportStackOverflow :: Bool -> IO ()
+reportStackOverflow bombOut = do
+ (hFlush stdout) `catchException` (\ _ -> return ())
+ callStackOverflowHook
+ if bombOut then
+ stg_exit 2
+ else
+ return ()
+
+reportError :: Bool -> String -> IO ()
+reportError bombOut str = do
+ (hFlush stdout) `catchException` (\ _ -> return ())
+ let bs@(ByteArray (_,len) _) = packString str
+ writeErrString addrOf_ErrorHdrHook bs len
+ if bombOut then
+ stg_exit 1
+ else
+ return ()
+
+foreign label "ErrorHdrHook"
+ addrOf_ErrorHdrHook :: Addr
+
+foreign import ccall "writeErrString__"
+ writeErrString :: Addr -> ByteArray Int -> Int -> IO ()
+
+foreign import ccall "stackOverflow"
+ callStackOverflowHook :: IO ()
+
+foreign import ccall "stg_exit"
+ stg_exit :: Int -> IO ()
+\end{code}
+
+
A number of operations want to get at a readable or writeable handle, and fail
if it isn't:
\begin{code}
wantReadableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
wantReadableHandle fun handle act =
- withHandle handle $ \ handle_ -> do
+ withHandle_ handle $ \ handle_ -> do
case haType__ handle_ of
- ErrorHandle theError -> do
- writeHandle handle handle_
- ioError theError
- ClosedHandle -> do
- writeHandle handle handle_
- ioe_closedHandle fun handle
- SemiClosedHandle -> do
- writeHandle handle handle_
- ioe_closedHandle fun handle
- AppendHandle -> do
- writeHandle handle handle_
- ioError not_readable_error
- WriteHandle -> do
- writeHandle handle handle_
- ioError not_readable_error
- _ -> act handle_
+ ErrorHandle theError -> ioError theError
+ ClosedHandle -> ioe_closedHandle fun handle
+ SemiClosedHandle -> ioe_closedHandle fun handle
+ AppendHandle -> ioError not_readable_error
+ WriteHandle -> ioError not_readable_error
+ _ -> act handle_
where
not_readable_error =
IOError (Just handle) IllegalOperation fun
wantWriteableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
wantWriteableHandle fun handle act =
- withHandle handle $ \ handle_ -> do
+ withHandle_ handle $ \ handle_ -> do
case haType__ handle_ of
- ErrorHandle theError -> do
- writeHandle handle handle_
- ioError theError
- ClosedHandle -> do
- writeHandle handle handle_
- ioe_closedHandle fun handle
- SemiClosedHandle -> do
- writeHandle handle handle_
- ioe_closedHandle fun handle
- ReadHandle -> do
- writeHandle handle handle_
- ioError not_writeable_error
- _ -> act handle_
+ ErrorHandle theError -> ioError theError
+ ClosedHandle -> ioe_closedHandle fun handle
+ SemiClosedHandle -> ioe_closedHandle fun handle
+ ReadHandle -> ioError not_writeable_error
+ _ -> act handle_
where
not_writeable_error =
IOError (Just handle) IllegalOperation fun
wantRWHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
wantRWHandle fun handle act =
- withHandle handle $ \ handle_ -> do
+ withHandle_ handle $ \ handle_ -> do
case haType__ handle_ of
- ErrorHandle theError -> do
- writeHandle handle handle_
- ioError theError
- ClosedHandle -> do
- writeHandle handle handle_
- ioe_closedHandle fun handle
- SemiClosedHandle -> do
- writeHandle handle handle_
- ioe_closedHandle fun handle
- _ -> act handle_
+ ErrorHandle theError -> ioError theError
+ ClosedHandle -> ioe_closedHandle fun handle
+ SemiClosedHandle -> ioe_closedHandle fun handle
+ _ -> act handle_
where
not_rw_error =
IOError (Just handle) IllegalOperation fun
wantSeekableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
wantSeekableHandle fun handle act =
- withHandle handle $ \ handle_ -> do
+ withHandle_ handle $ \ handle_ -> do
case haType__ handle_ of
- ErrorHandle theError -> do
- writeHandle handle handle_
- ioError theError
- ClosedHandle -> do
- writeHandle handle handle_
- ioe_closedHandle fun handle
- SemiClosedHandle -> do
- writeHandle handle handle_
- ioe_closedHandle fun handle
- AppendHandle -> do
- writeHandle handle handle_
- ioError not_seekable_error
- _ -> act handle_
+ ErrorHandle theError -> ioError theError
+ ClosedHandle -> ioe_closedHandle fun handle
+ SemiClosedHandle -> ioe_closedHandle fun handle
+ AppendHandle -> ioError not_seekable_error
+ _ -> act handle_
where
not_seekable_error =
IOError (Just handle)
projects / ghc-hetmet.git / blobdiff