1 {-# OPTIONS_GHC -XNoImplicitPrelude -#include "HsBase.h" #-}
2 {-# OPTIONS_HADDOCK hide #-}
7 -----------------------------------------------------------------------------
10 -- Copyright : (c) The University of Glasgow, 1994-2001
11 -- License : see libraries/base/LICENSE
13 -- Maintainer : libraries@haskell.org
14 -- Stability : internal
15 -- Portability : non-portable
17 -- This module defines the basic operations on I\/O \"handles\".
19 -----------------------------------------------------------------------------
23 withHandle, withHandle', withHandle_,
24 wantWritableHandle, wantReadableHandle, wantSeekableHandle,
26 newEmptyBuffer, allocateBuffer, readCharFromBuffer, writeCharIntoBuffer,
27 flushWriteBufferOnly, flushWriteBuffer, flushReadBuffer,
28 fillReadBuffer, fillReadBufferWithoutBlocking,
29 readRawBuffer, readRawBufferPtr,
30 readRawBufferNoBlock, readRawBufferPtrNoBlock,
31 writeRawBuffer, writeRawBufferPtr,
33 #ifndef mingw32_HOST_OS
37 ioe_closedHandle, ioe_EOF, ioe_notReadable, ioe_notWritable,
39 stdin, stdout, stderr,
40 IOMode(..), openFile, openBinaryFile, fdToHandle_stat, fdToHandle, fdToHandle',
41 hFileSize, hSetFileSize, hIsEOF, isEOF, hLookAhead, hSetBuffering, hSetBinaryMode,
42 hFlush, hDuplicate, hDuplicateTo,
46 HandlePosition, HandlePosn(..), hGetPosn, hSetPosn,
47 SeekMode(..), hSeek, hTell,
49 hIsOpen, hIsClosed, hIsReadable, hIsWritable, hGetBuffering, hIsSeekable,
50 hSetEcho, hGetEcho, hIsTerminalDevice,
65 import System.IO.Error
66 import System.Posix.Internals
67 import System.Posix.Types
73 import GHC.Read ( Read )
78 import GHC.Num ( Integer(..), Num(..) )
80 import GHC.Real ( toInteger )
81 #if defined(DEBUG_DUMP)
87 -- -----------------------------------------------------------------------------
90 -- hWaitForInput blocks (should use a timeout)
92 -- unbuffered hGetLine is a bit dodgy
94 -- hSetBuffering: can't change buffering on a stream,
95 -- when the read buffer is non-empty? (no way to flush the buffer)
97 -- ---------------------------------------------------------------------------
98 -- Are files opened by default in text or binary mode, if the user doesn't
101 dEFAULT_OPEN_IN_BINARY_MODE = False :: Bool
103 -- ---------------------------------------------------------------------------
104 -- Creating a new handle
106 newFileHandle :: FilePath -> (MVar Handle__ -> IO ()) -> Handle__ -> IO Handle
107 newFileHandle filepath finalizer hc = do
109 addMVarFinalizer m (finalizer m)
110 return (FileHandle filepath m)
112 -- ---------------------------------------------------------------------------
113 -- Working with Handles
116 In the concurrent world, handles are locked during use. This is done
117 by wrapping an MVar around the handle which acts as a mutex over
118 operations on the handle.
120 To avoid races, we use the following bracketing operations. The idea
121 is to obtain the lock, do some operation and replace the lock again,
122 whether the operation succeeded or failed. We also want to handle the
123 case where the thread receives an exception while processing the IO
124 operation: in these cases we also want to relinquish the lock.
126 There are three versions of @withHandle@: corresponding to the three
127 possible combinations of:
129 - the operation may side-effect the handle
130 - the operation may return a result
132 If the operation generates an error or an exception is raised, the
133 original handle is always replaced [ this is the case at the moment,
134 but we might want to revisit this in the future --SDM ].
137 {-# INLINE withHandle #-}
138 withHandle :: String -> Handle -> (Handle__ -> IO (Handle__,a)) -> IO a
139 withHandle fun h@(FileHandle _ m) act = withHandle' fun h m act
140 withHandle fun h@(DuplexHandle _ m _) act = withHandle' fun h m act
142 withHandle' :: String -> Handle -> MVar Handle__
143 -> (Handle__ -> IO (Handle__,a)) -> IO a
144 withHandle' fun h m act =
147 checkBufferInvariants h_
148 (h',v) <- (act h_ `catchAny` \err -> putMVar m h_ >> throw err)
149 `catchException` \ex -> ioError (augmentIOError ex fun h)
150 checkBufferInvariants h'
154 {-# INLINE withHandle_ #-}
155 withHandle_ :: String -> Handle -> (Handle__ -> IO a) -> IO a
156 withHandle_ fun h@(FileHandle _ m) act = withHandle_' fun h m act
157 withHandle_ fun h@(DuplexHandle _ m _) act = withHandle_' fun h m act
159 withHandle_' :: String -> Handle -> MVar Handle__ -> (Handle__ -> IO a) -> IO a
160 withHandle_' fun h m act =
163 checkBufferInvariants h_
164 v <- (act h_ `catchAny` \err -> putMVar m h_ >> throw err)
165 `catchException` \ex -> ioError (augmentIOError ex fun h)
166 checkBufferInvariants h_
170 withAllHandles__ :: String -> Handle -> (Handle__ -> IO Handle__) -> IO ()
171 withAllHandles__ fun h@(FileHandle _ m) act = withHandle__' fun h m act
172 withAllHandles__ fun h@(DuplexHandle _ r w) act = do
173 withHandle__' fun h r act
174 withHandle__' fun h w act
176 withHandle__' fun h m act =
179 checkBufferInvariants h_
180 h' <- (act h_ `catchAny` \err -> putMVar m h_ >> throw err)
181 `catchException` \ex -> ioError (augmentIOError ex fun h)
182 checkBufferInvariants h'
186 augmentIOError (IOError _ iot _ str fp) fun h
187 = IOError (Just h) iot fun str filepath
190 | otherwise = case h of
191 FileHandle fp _ -> Just fp
192 DuplexHandle fp _ _ -> Just fp
194 -- ---------------------------------------------------------------------------
195 -- Wrapper for write operations.
197 wantWritableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
198 wantWritableHandle fun h@(FileHandle _ m) act
199 = wantWritableHandle' fun h m act
200 wantWritableHandle fun h@(DuplexHandle _ _ m) act
201 = wantWritableHandle' fun h m act
202 -- ToDo: in the Duplex case, we don't need to checkWritableHandle
205 :: String -> Handle -> MVar Handle__
206 -> (Handle__ -> IO a) -> IO a
207 wantWritableHandle' fun h m act
208 = withHandle_' fun h m (checkWritableHandle act)
210 checkWritableHandle act handle_
211 = case haType handle_ of
212 ClosedHandle -> ioe_closedHandle
213 SemiClosedHandle -> ioe_closedHandle
214 ReadHandle -> ioe_notWritable
215 ReadWriteHandle -> do
216 let ref = haBuffer handle_
219 if not (bufferIsWritable buf)
220 then do b <- flushReadBuffer (haFD handle_) buf
221 return b{ bufState=WriteBuffer }
223 writeIORef ref new_buf
225 _other -> act handle_
227 -- ---------------------------------------------------------------------------
228 -- Wrapper for read operations.
230 wantReadableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
231 wantReadableHandle fun h@(FileHandle _ m) act
232 = wantReadableHandle' fun h m act
233 wantReadableHandle fun h@(DuplexHandle _ m _) act
234 = wantReadableHandle' fun h m act
235 -- ToDo: in the Duplex case, we don't need to checkReadableHandle
238 :: String -> Handle -> MVar Handle__
239 -> (Handle__ -> IO a) -> IO a
240 wantReadableHandle' fun h m act
241 = withHandle_' fun h m (checkReadableHandle act)
243 checkReadableHandle act handle_ =
244 case haType handle_ of
245 ClosedHandle -> ioe_closedHandle
246 SemiClosedHandle -> ioe_closedHandle
247 AppendHandle -> ioe_notReadable
248 WriteHandle -> ioe_notReadable
249 ReadWriteHandle -> do
250 let ref = haBuffer handle_
252 when (bufferIsWritable buf) $ do
253 new_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
254 writeIORef ref new_buf{ bufState=ReadBuffer }
256 _other -> act handle_
258 -- ---------------------------------------------------------------------------
259 -- Wrapper for seek operations.
261 wantSeekableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
262 wantSeekableHandle fun h@(DuplexHandle _ _ _) _act =
263 ioException (IOError (Just h) IllegalOperation fun
264 "handle is not seekable" Nothing)
265 wantSeekableHandle fun h@(FileHandle _ m) act =
266 withHandle_' fun h m (checkSeekableHandle act)
268 checkSeekableHandle act handle_ =
269 case haType handle_ of
270 ClosedHandle -> ioe_closedHandle
271 SemiClosedHandle -> ioe_closedHandle
272 AppendHandle -> ioe_notSeekable
273 _ | haIsBin handle_ || tEXT_MODE_SEEK_ALLOWED -> act handle_
274 | otherwise -> ioe_notSeekable_notBin
276 -- -----------------------------------------------------------------------------
279 ioe_closedHandle, ioe_EOF,
280 ioe_notReadable, ioe_notWritable,
281 ioe_notSeekable, ioe_notSeekable_notBin :: IO a
283 ioe_closedHandle = ioException
284 (IOError Nothing IllegalOperation ""
285 "handle is closed" Nothing)
286 ioe_EOF = ioException
287 (IOError Nothing EOF "" "" Nothing)
288 ioe_notReadable = ioException
289 (IOError Nothing IllegalOperation ""
290 "handle is not open for reading" Nothing)
291 ioe_notWritable = ioException
292 (IOError Nothing IllegalOperation ""
293 "handle is not open for writing" Nothing)
294 ioe_notSeekable = ioException
295 (IOError Nothing IllegalOperation ""
296 "handle is not seekable" Nothing)
297 ioe_notSeekable_notBin = ioException
298 (IOError Nothing IllegalOperation ""
299 "seek operations on text-mode handles are not allowed on this platform"
302 ioe_finalizedHandle fp = throw
303 (IOError Nothing IllegalOperation ""
304 "handle is finalized" (Just fp))
306 ioe_bufsiz :: Int -> IO a
307 ioe_bufsiz n = ioException
308 (IOError Nothing InvalidArgument "hSetBuffering"
309 ("illegal buffer size " ++ showsPrec 9 n []) Nothing)
310 -- 9 => should be parens'ified.
312 -- -----------------------------------------------------------------------------
315 -- For a duplex handle, we arrange that the read side points to the write side
316 -- (and hence keeps it alive if the read side is alive). This is done by
317 -- having the haOtherSide field of the read side point to the read side.
318 -- The finalizer is then placed on the write side, and the handle only gets
319 -- finalized once, when both sides are no longer required.
321 -- NOTE about finalized handles: It's possible that a handle can be
322 -- finalized and then we try to use it later, for example if the
323 -- handle is referenced from another finalizer, or from a thread that
324 -- has become unreferenced and then resurrected (arguably in the
325 -- latter case we shouldn't finalize the Handle...). Anyway,
326 -- we try to emit a helpful message which is better than nothing.
328 stdHandleFinalizer :: FilePath -> MVar Handle__ -> IO ()
329 stdHandleFinalizer fp m = do
331 flushWriteBufferOnly h_
332 putMVar m (ioe_finalizedHandle fp)
334 handleFinalizer :: FilePath -> MVar Handle__ -> IO ()
335 handleFinalizer fp m = do
336 handle_ <- takeMVar m
337 case haType handle_ of
338 ClosedHandle -> return ()
339 _ -> do flushWriteBufferOnly handle_ `catchAny` \_ -> return ()
340 -- ignore errors and async exceptions, and close the
341 -- descriptor anyway...
342 hClose_handle_ handle_
344 putMVar m (ioe_finalizedHandle fp)
346 -- ---------------------------------------------------------------------------
347 -- Grimy buffer operations
350 checkBufferInvariants h_ = do
351 let ref = haBuffer h_
352 Buffer{ bufWPtr=w, bufRPtr=r, bufSize=size, bufState=state } <- readIORef ref
357 && ( r /= w || (r == 0 && w == 0) )
358 && ( state /= WriteBuffer || r == 0 )
359 && ( state /= WriteBuffer || w < size ) -- write buffer is never full
361 then error "buffer invariant violation"
364 checkBufferInvariants h_ = return ()
367 newEmptyBuffer :: RawBuffer -> BufferState -> Int -> Buffer
368 newEmptyBuffer b state size
369 = Buffer{ bufBuf=b, bufRPtr=0, bufWPtr=0, bufSize=size, bufState=state }
371 allocateBuffer :: Int -> BufferState -> IO Buffer
372 allocateBuffer sz@(I# size) state = IO $ \s ->
373 -- We sometimes need to pass the address of this buffer to
374 -- a "safe" foreign call, hence it must be immovable.
375 case newPinnedByteArray# size s of { (# s, b #) ->
376 (# s, newEmptyBuffer b state sz #) }
378 writeCharIntoBuffer :: RawBuffer -> Int -> Char -> IO Int
379 writeCharIntoBuffer slab (I# off) (C# c)
380 = IO $ \s -> case writeCharArray# slab off c s of
381 s -> (# s, I# (off +# 1#) #)
383 readCharFromBuffer :: RawBuffer -> Int -> IO (Char, Int)
384 readCharFromBuffer slab (I# off)
385 = IO $ \s -> case readCharArray# slab off s of
386 (# s, c #) -> (# s, (C# c, I# (off +# 1#)) #)
388 getBuffer :: FD -> BufferState -> IO (IORef Buffer, BufferMode)
389 getBuffer fd state = do
390 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE state
391 ioref <- newIORef buffer
395 | is_tty = LineBuffering
396 | otherwise = BlockBuffering Nothing
398 return (ioref, buffer_mode)
400 mkUnBuffer :: IO (IORef Buffer)
402 buffer <- allocateBuffer 1 ReadBuffer
405 -- flushWriteBufferOnly flushes the buffer iff it contains pending write data.
406 flushWriteBufferOnly :: Handle__ -> IO ()
407 flushWriteBufferOnly h_ = do
411 new_buf <- if bufferIsWritable buf
412 then flushWriteBuffer fd (haIsStream h_) buf
414 writeIORef ref new_buf
416 -- flushBuffer syncs the file with the buffer, including moving the
417 -- file pointer backwards in the case of a read buffer.
418 flushBuffer :: Handle__ -> IO ()
420 let ref = haBuffer h_
425 ReadBuffer -> flushReadBuffer (haFD h_) buf
426 WriteBuffer -> flushWriteBuffer (haFD h_) (haIsStream h_) buf
428 writeIORef ref flushed_buf
430 -- When flushing a read buffer, we seek backwards by the number of
431 -- characters in the buffer. The file descriptor must therefore be
432 -- seekable: attempting to flush the read buffer on an unseekable
433 -- handle is not allowed.
435 flushReadBuffer :: FD -> Buffer -> IO Buffer
436 flushReadBuffer fd buf
437 | bufferEmpty buf = return buf
439 let off = negate (bufWPtr buf - bufRPtr buf)
441 puts ("flushReadBuffer: new file offset = " ++ show off ++ "\n")
443 throwErrnoIfMinus1Retry "flushReadBuffer"
444 (c_lseek fd (fromIntegral off) sEEK_CUR)
445 return buf{ bufWPtr=0, bufRPtr=0 }
447 flushWriteBuffer :: FD -> Bool -> Buffer -> IO Buffer
448 flushWriteBuffer fd is_stream buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w } =
449 seq fd $ do -- strictness hack
452 puts ("flushWriteBuffer, fd=" ++ show fd ++ ", bytes=" ++ show bytes ++ "\n")
455 then return (buf{ bufRPtr=0, bufWPtr=0 })
457 res <- writeRawBuffer "flushWriteBuffer" fd is_stream b
458 (fromIntegral r) (fromIntegral bytes)
459 let res' = fromIntegral res
461 then flushWriteBuffer fd is_stream (buf{ bufRPtr = r + res' })
462 else return buf{ bufRPtr=0, bufWPtr=0 }
464 fillReadBuffer :: FD -> Bool -> Bool -> Buffer -> IO Buffer
465 fillReadBuffer fd is_line is_stream
466 buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w, bufSize=size } =
467 -- buffer better be empty:
468 assert (r == 0 && w == 0) $ do
469 fillReadBufferLoop fd is_line is_stream buf b w size
471 -- For a line buffer, we just get the first chunk of data to arrive,
472 -- and don't wait for the whole buffer to be full (but we *do* wait
473 -- until some data arrives). This isn't really line buffering, but it
474 -- appears to be what GHC has done for a long time, and I suspect it
475 -- is more useful than line buffering in most cases.
477 fillReadBufferLoop fd is_line is_stream buf b w size = do
479 if bytes == 0 -- buffer full?
480 then return buf{ bufRPtr=0, bufWPtr=w }
483 puts ("fillReadBufferLoop: bytes = " ++ show bytes ++ "\n")
485 res <- readRawBuffer "fillReadBuffer" fd is_stream b
486 (fromIntegral w) (fromIntegral bytes)
487 let res' = fromIntegral res
489 puts ("fillReadBufferLoop: res' = " ++ show res' ++ "\n")
494 else return buf{ bufRPtr=0, bufWPtr=w }
495 else if res' < bytes && not is_line
496 then fillReadBufferLoop fd is_line is_stream buf b (w+res') size
497 else return buf{ bufRPtr=0, bufWPtr=w+res' }
500 fillReadBufferWithoutBlocking :: FD -> Bool -> Buffer -> IO Buffer
501 fillReadBufferWithoutBlocking fd is_stream
502 buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w, bufSize=size } =
503 -- buffer better be empty:
504 assert (r == 0 && w == 0) $ do
506 puts ("fillReadBufferLoopNoBlock: bytes = " ++ show size ++ "\n")
508 res <- readRawBufferNoBlock "fillReadBuffer" fd is_stream b
509 0 (fromIntegral size)
510 let res' = fromIntegral res
512 puts ("fillReadBufferLoopNoBlock: res' = " ++ show res' ++ "\n")
514 return buf{ bufRPtr=0, bufWPtr=res' }
516 -- Low level routines for reading/writing to (raw)buffers:
518 #ifndef mingw32_HOST_OS
523 Unix has broken semantics when it comes to non-blocking I/O: you can
524 set the O_NONBLOCK flag on an FD, but it applies to the all other FDs
525 attached to the same underlying file, pipe or TTY; there's no way to
526 have private non-blocking behaviour for an FD. See bug #724.
528 We fix this by only setting O_NONBLOCK on FDs that we create; FDs that
529 come from external sources or are exposed externally are left in
530 blocking mode. This solution has some problems though. We can't
531 completely simulate a non-blocking read without O_NONBLOCK: several
532 cases are wrong here. The cases that are wrong:
534 * reading/writing to a blocking FD in non-threaded mode.
535 In threaded mode, we just make a safe call to read().
536 In non-threaded mode we call select() before attempting to read,
537 but that leaves a small race window where the data can be read
538 from the file descriptor before we issue our blocking read().
539 * readRawBufferNoBlock for a blocking FD
543 In the threaded RTS we could just make safe calls to read()/write()
544 for file descriptors in blocking mode without worrying about blocking
545 other threads, but the problem with this is that the thread will be
546 uninterruptible while it is blocked in the foreign call. See #2363.
547 So now we always call fdReady() before reading, and if fdReady
548 indicates that there's no data, we call threadWaitRead.
552 readRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
553 readRawBuffer loc fd is_nonblock buf off len
554 | is_nonblock = unsafe_read -- unsafe is ok, it can't block
555 | otherwise = do r <- throwErrnoIfMinus1 loc
556 (unsafe_fdReady (fromIntegral fd) 0 0 0)
559 else do threadWaitRead (fromIntegral fd); read
561 do_read call = throwErrnoIfMinus1RetryMayBlock loc call
562 (threadWaitRead (fromIntegral fd))
563 read = if threaded then safe_read else unsafe_read
564 unsafe_read = do_read (read_rawBuffer fd buf off len)
565 safe_read = do_read (safe_read_rawBuffer fd buf off len)
567 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
568 readRawBufferPtr loc fd is_nonblock buf off len
569 | is_nonblock = unsafe_read -- unsafe is ok, it can't block
570 | otherwise = do r <- throwErrnoIfMinus1 loc
571 (unsafe_fdReady (fromIntegral fd) 0 0 0)
574 else do threadWaitRead (fromIntegral fd); read
576 do_read call = throwErrnoIfMinus1RetryMayBlock loc call
577 (threadWaitRead (fromIntegral fd))
578 read = if threaded then safe_read else unsafe_read
579 unsafe_read = do_read (read_off fd buf off len)
580 safe_read = do_read (safe_read_off fd buf off len)
582 readRawBufferNoBlock :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
583 readRawBufferNoBlock loc fd is_nonblock buf off len
584 | is_nonblock = unsafe_read -- unsafe is ok, it can't block
585 | otherwise = do r <- unsafe_fdReady (fromIntegral fd) 0 0 0
586 if r /= 0 then safe_read
588 -- XXX see note [nonblock]
590 do_read call = throwErrnoIfMinus1RetryOnBlock loc call (return 0)
591 unsafe_read = do_read (read_rawBuffer fd buf off len)
592 safe_read = do_read (safe_read_rawBuffer fd buf off len)
594 readRawBufferPtrNoBlock :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
595 readRawBufferPtrNoBlock loc fd is_nonblock buf off len
596 | is_nonblock = unsafe_read -- unsafe is ok, it can't block
597 | otherwise = do r <- unsafe_fdReady (fromIntegral fd) 0 0 0
598 if r /= 0 then safe_read
600 -- XXX see note [nonblock]
602 do_read call = throwErrnoIfMinus1RetryOnBlock loc call (return 0)
603 unsafe_read = do_read (read_off fd buf off len)
604 safe_read = do_read (safe_read_off fd buf off len)
606 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
607 writeRawBuffer loc fd is_nonblock buf off len
608 | is_nonblock = unsafe_write -- unsafe is ok, it can't block
609 | otherwise = do r <- unsafe_fdReady (fromIntegral fd) 1 0 0
612 else do threadWaitWrite (fromIntegral fd); write
614 do_write call = throwErrnoIfMinus1RetryMayBlock loc call
615 (threadWaitWrite (fromIntegral fd))
616 write = if threaded then safe_write else unsafe_write
617 unsafe_write = do_write (write_rawBuffer fd buf off len)
618 safe_write = do_write (safe_write_rawBuffer (fromIntegral fd) buf off len)
620 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
621 writeRawBufferPtr loc fd is_nonblock buf off len
622 | is_nonblock = unsafe_write -- unsafe is ok, it can't block
623 | otherwise = do r <- unsafe_fdReady (fromIntegral fd) 1 0 0
626 else do threadWaitWrite (fromIntegral fd); write
628 do_write call = throwErrnoIfMinus1RetryMayBlock loc call
629 (threadWaitWrite (fromIntegral fd))
630 write = if threaded then safe_write else unsafe_write
631 unsafe_write = do_write (write_off fd buf off len)
632 safe_write = do_write (safe_write_off (fromIntegral fd) buf off len)
634 foreign import ccall unsafe "__hscore_PrelHandle_read"
635 read_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
637 foreign import ccall unsafe "__hscore_PrelHandle_read"
638 read_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
640 foreign import ccall unsafe "__hscore_PrelHandle_write"
641 write_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
643 foreign import ccall unsafe "__hscore_PrelHandle_write"
644 write_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
646 foreign import ccall unsafe "fdReady"
647 unsafe_fdReady :: CInt -> CInt -> CInt -> CInt -> IO CInt
649 #else /* mingw32_HOST_OS.... */
651 readRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
652 readRawBuffer loc fd is_stream buf off len
653 | threaded = blockingReadRawBuffer loc fd is_stream buf off len
654 | otherwise = asyncReadRawBuffer loc fd is_stream buf off len
656 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
657 readRawBufferPtr loc fd is_stream buf off len
658 | threaded = blockingReadRawBufferPtr loc fd is_stream buf off len
659 | otherwise = asyncReadRawBufferPtr loc fd is_stream buf off len
661 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
662 writeRawBuffer loc fd is_stream buf off len
663 | threaded = blockingWriteRawBuffer loc fd is_stream buf off len
664 | otherwise = asyncWriteRawBuffer loc fd is_stream buf off len
666 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
667 writeRawBufferPtr loc fd is_stream buf off len
668 | threaded = blockingWriteRawBufferPtr loc fd is_stream buf off len
669 | otherwise = asyncWriteRawBufferPtr loc fd is_stream buf off len
671 -- ToDo: we don't have a non-blocking primitve read on Win32
672 readRawBufferNoBlock :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
673 readRawBufferNoBlock = readRawBuffer
675 readRawBufferPtrNoBlock :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
676 readRawBufferPtrNoBlock = readRawBufferPtr
677 -- Async versions of the read/write primitives, for the non-threaded RTS
679 asyncReadRawBuffer loc fd is_stream buf off len = do
680 (l, rc) <- asyncReadBA (fromIntegral fd) (if is_stream then 1 else 0)
681 (fromIntegral len) off buf
684 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
685 else return (fromIntegral l)
687 asyncReadRawBufferPtr loc fd is_stream buf off len = do
688 (l, rc) <- asyncRead (fromIntegral fd) (if is_stream then 1 else 0)
689 (fromIntegral len) (buf `plusPtr` off)
692 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
693 else return (fromIntegral l)
695 asyncWriteRawBuffer loc fd is_stream buf off len = do
696 (l, rc) <- asyncWriteBA (fromIntegral fd) (if is_stream then 1 else 0)
697 (fromIntegral len) off buf
700 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
701 else return (fromIntegral l)
703 asyncWriteRawBufferPtr loc fd is_stream buf off len = do
704 (l, rc) <- asyncWrite (fromIntegral fd) (if is_stream then 1 else 0)
705 (fromIntegral len) (buf `plusPtr` off)
708 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
709 else return (fromIntegral l)
711 -- Blocking versions of the read/write primitives, for the threaded RTS
713 blockingReadRawBuffer loc fd True buf off len =
714 throwErrnoIfMinus1Retry loc $
715 safe_recv_rawBuffer fd buf off len
716 blockingReadRawBuffer loc fd False buf off len =
717 throwErrnoIfMinus1Retry loc $
718 safe_read_rawBuffer fd buf off len
720 blockingReadRawBufferPtr loc fd True buf off len =
721 throwErrnoIfMinus1Retry loc $
722 safe_recv_off fd buf off len
723 blockingReadRawBufferPtr loc fd False buf off len =
724 throwErrnoIfMinus1Retry loc $
725 safe_read_off fd buf off len
727 blockingWriteRawBuffer loc fd True buf off len =
728 throwErrnoIfMinus1Retry loc $
729 safe_send_rawBuffer fd buf off len
730 blockingWriteRawBuffer loc fd False buf off len =
731 throwErrnoIfMinus1Retry loc $
732 safe_write_rawBuffer fd buf off len
734 blockingWriteRawBufferPtr loc fd True buf off len =
735 throwErrnoIfMinus1Retry loc $
736 safe_send_off fd buf off len
737 blockingWriteRawBufferPtr loc fd False buf off len =
738 throwErrnoIfMinus1Retry loc $
739 safe_write_off fd buf off len
741 -- NOTE: "safe" versions of the read/write calls for use by the threaded RTS.
742 -- These calls may block, but that's ok.
744 foreign import ccall safe "__hscore_PrelHandle_recv"
745 safe_recv_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
747 foreign import ccall safe "__hscore_PrelHandle_recv"
748 safe_recv_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
750 foreign import ccall safe "__hscore_PrelHandle_send"
751 safe_send_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
753 foreign import ccall safe "__hscore_PrelHandle_send"
754 safe_send_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
758 foreign import ccall "rtsSupportsBoundThreads" threaded :: Bool
760 foreign import ccall safe "__hscore_PrelHandle_read"
761 safe_read_rawBuffer :: FD -> RawBuffer -> Int -> CInt -> IO CInt
763 foreign import ccall safe "__hscore_PrelHandle_read"
764 safe_read_off :: FD -> Ptr CChar -> Int -> CInt -> IO CInt
766 foreign import ccall safe "__hscore_PrelHandle_write"
767 safe_write_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
769 foreign import ccall safe "__hscore_PrelHandle_write"
770 safe_write_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
772 -- ---------------------------------------------------------------------------
775 -- Three handles are allocated during program initialisation. The first
776 -- two manage input or output from the Haskell program's standard input
777 -- or output channel respectively. The third manages output to the
778 -- standard error channel. These handles are initially open.
784 -- | A handle managing input from the Haskell program's standard input channel.
786 stdin = unsafePerformIO $ do
787 -- ToDo: acquire lock
788 -- We don't set non-blocking mode on standard handles, because it may
789 -- confuse other applications attached to the same TTY/pipe
790 -- see Note [nonblock]
791 (buf, bmode) <- getBuffer fd_stdin ReadBuffer
792 mkStdHandle fd_stdin "<stdin>" ReadHandle buf bmode
794 -- | A handle managing output to the Haskell program's standard output channel.
796 stdout = unsafePerformIO $ do
797 -- ToDo: acquire lock
798 -- We don't set non-blocking mode on standard handles, because it may
799 -- confuse other applications attached to the same TTY/pipe
800 -- see Note [nonblock]
801 (buf, bmode) <- getBuffer fd_stdout WriteBuffer
802 mkStdHandle fd_stdout "<stdout>" WriteHandle buf bmode
804 -- | A handle managing output to the Haskell program's standard error channel.
806 stderr = unsafePerformIO $ do
807 -- ToDo: acquire lock
808 -- We don't set non-blocking mode on standard handles, because it may
809 -- confuse other applications attached to the same TTY/pipe
810 -- see Note [nonblock]
812 mkStdHandle fd_stderr "<stderr>" WriteHandle buf NoBuffering
814 -- ---------------------------------------------------------------------------
815 -- Opening and Closing Files
817 addFilePathToIOError fun fp (IOError h iot _ str _)
818 = IOError h iot fun str (Just fp)
820 -- | Computation 'openFile' @file mode@ allocates and returns a new, open
821 -- handle to manage the file @file@. It manages input if @mode@
822 -- is 'ReadMode', output if @mode@ is 'WriteMode' or 'AppendMode',
823 -- and both input and output if mode is 'ReadWriteMode'.
825 -- If the file does not exist and it is opened for output, it should be
826 -- created as a new file. If @mode@ is 'WriteMode' and the file
827 -- already exists, then it should be truncated to zero length.
828 -- Some operating systems delete empty files, so there is no guarantee
829 -- that the file will exist following an 'openFile' with @mode@
830 -- 'WriteMode' unless it is subsequently written to successfully.
831 -- The handle is positioned at the end of the file if @mode@ is
832 -- 'AppendMode', and otherwise at the beginning (in which case its
833 -- internal position is 0).
834 -- The initial buffer mode is implementation-dependent.
836 -- This operation may fail with:
838 -- * 'isAlreadyInUseError' if the file is already open and cannot be reopened;
840 -- * 'isDoesNotExistError' if the file does not exist; or
842 -- * 'isPermissionError' if the user does not have permission to open the file.
844 -- Note: if you will be working with files containing binary data, you'll want to
845 -- be using 'openBinaryFile'.
846 openFile :: FilePath -> IOMode -> IO Handle
849 (openFile' fp im dEFAULT_OPEN_IN_BINARY_MODE)
850 (\e -> ioError (addFilePathToIOError "openFile" fp e))
852 -- | Like 'openFile', but open the file in binary mode.
853 -- On Windows, reading a file in text mode (which is the default)
854 -- will translate CRLF to LF, and writing will translate LF to CRLF.
855 -- This is usually what you want with text files. With binary files
856 -- this is undesirable; also, as usual under Microsoft operating systems,
857 -- text mode treats control-Z as EOF. Binary mode turns off all special
858 -- treatment of end-of-line and end-of-file characters.
859 -- (See also 'hSetBinaryMode'.)
861 openBinaryFile :: FilePath -> IOMode -> IO Handle
862 openBinaryFile fp m =
864 (openFile' fp m True)
865 (\e -> ioError (addFilePathToIOError "openBinaryFile" fp e))
867 openFile' filepath mode binary =
868 withCString filepath $ \ f ->
871 oflags1 = case mode of
872 ReadMode -> read_flags
873 #ifdef mingw32_HOST_OS
874 WriteMode -> write_flags .|. o_TRUNC
876 WriteMode -> write_flags
878 ReadWriteMode -> rw_flags
879 AppendMode -> append_flags
885 oflags = oflags1 .|. binary_flags
888 -- the old implementation had a complicated series of three opens,
889 -- which is perhaps because we have to be careful not to open
890 -- directories. However, the man pages I've read say that open()
891 -- always returns EISDIR if the file is a directory and was opened
892 -- for writing, so I think we're ok with a single open() here...
893 fd <- throwErrnoIfMinus1Retry "openFile"
894 (c_open f (fromIntegral oflags) 0o666)
896 stat@(fd_type,_,_) <- fdStat fd
898 h <- fdToHandle_stat fd (Just stat) False filepath mode binary
899 `catchAny` \e -> do c_close fd; throw e
900 -- NB. don't forget to close the FD if fdToHandle' fails, otherwise
902 -- ASSERT: if we just created the file, then fdToHandle' won't fail
903 -- (so we don't need to worry about removing the newly created file
904 -- in the event of an error).
906 #ifndef mingw32_HOST_OS
907 -- we want to truncate() if this is an open in WriteMode, but only
908 -- if the target is a RegularFile. ftruncate() fails on special files
910 if mode == WriteMode && fd_type == RegularFile
911 then throwErrnoIf (/=0) "openFile"
918 std_flags = o_NONBLOCK .|. o_NOCTTY
919 output_flags = std_flags .|. o_CREAT
920 read_flags = std_flags .|. o_RDONLY
921 write_flags = output_flags .|. o_WRONLY
922 rw_flags = output_flags .|. o_RDWR
923 append_flags = write_flags .|. o_APPEND
925 -- ---------------------------------------------------------------------------
928 fdToHandle_stat :: FD
929 -> Maybe (FDType, CDev, CIno)
936 fdToHandle_stat fd mb_stat is_socket filepath mode binary = do
938 #ifdef mingw32_HOST_OS
939 -- On Windows, the is_socket flag indicates that the Handle is a socket
941 -- On Unix, the is_socket flag indicates that the FD can be made non-blocking
942 let non_blocking = is_socket
944 when non_blocking $ setNonBlockingFD fd
945 -- turn on non-blocking mode
948 let (ha_type, write) =
950 ReadMode -> ( ReadHandle, False )
951 WriteMode -> ( WriteHandle, True )
952 ReadWriteMode -> ( ReadWriteHandle, True )
953 AppendMode -> ( AppendHandle, True )
955 -- open() won't tell us if it was a directory if we only opened for
956 -- reading, so check again.
964 ioException (IOError Nothing InappropriateType "openFile"
965 "is a directory" Nothing)
967 -- regular files need to be locked
969 #ifndef mingw32_HOST_OS
970 -- On Windows we use explicit exclusion via sopen() to implement
971 -- this locking (see __hscore_open()); on Unix we have to
972 -- implment it in the RTS.
973 r <- lockFile fd dev ino (fromBool write)
975 ioException (IOError Nothing ResourceBusy "openFile"
976 "file is locked" Nothing)
978 mkFileHandle fd is_socket filepath ha_type binary
981 -- only *Streams* can be DuplexHandles. Other read/write
982 -- Handles must share a buffer.
983 | ReadWriteHandle <- ha_type ->
984 mkDuplexHandle fd is_socket filepath binary
986 mkFileHandle fd is_socket filepath ha_type binary
989 mkFileHandle fd is_socket filepath ha_type binary
991 -- | Old API kept to avoid breaking clients
992 fdToHandle' :: FD -> Maybe FDType -> Bool -> FilePath -> IOMode -> Bool
994 fdToHandle' fd mb_type is_socket filepath mode binary
996 let mb_stat = case mb_type of
998 -- fdToHandle_stat will do the stat:
999 Just RegularFile -> Nothing
1000 -- no stat required for streams etc.:
1001 Just other -> Just (other,0,0)
1002 fdToHandle_stat fd mb_stat is_socket filepath mode binary
1004 fdToHandle :: FD -> IO Handle
1006 mode <- fdGetMode fd
1007 let fd_str = "<file descriptor: " ++ show fd ++ ">"
1008 fdToHandle_stat fd Nothing False fd_str mode True{-bin mode-}
1009 -- NB. the is_socket flag is False, meaning that:
1010 -- on Unix the file descriptor will *not* be put in non-blocking mode
1011 -- on Windows we're guessing this is not a socket (XXX)
1013 #ifndef mingw32_HOST_OS
1014 foreign import ccall unsafe "lockFile"
1015 lockFile :: CInt -> CDev -> CIno -> CInt -> IO CInt
1017 foreign import ccall unsafe "unlockFile"
1018 unlockFile :: CInt -> IO CInt
1021 mkStdHandle :: FD -> FilePath -> HandleType -> IORef Buffer -> BufferMode
1023 mkStdHandle fd filepath ha_type buf bmode = do
1024 spares <- newIORef BufferListNil
1025 newFileHandle filepath (stdHandleFinalizer filepath)
1026 (Handle__ { haFD = fd,
1028 haIsBin = dEFAULT_OPEN_IN_BINARY_MODE,
1029 haIsStream = False, -- means FD is blocking on Unix
1030 haBufferMode = bmode,
1033 haOtherSide = Nothing
1036 mkFileHandle :: FD -> Bool -> FilePath -> HandleType -> Bool -> IO Handle
1037 mkFileHandle fd is_stream filepath ha_type binary = do
1038 (buf, bmode) <- getBuffer fd (initBufferState ha_type)
1040 #ifdef mingw32_HOST_OS
1041 -- On Windows, if this is a read/write handle and we are in text mode,
1042 -- turn off buffering. We don't correctly handle the case of switching
1043 -- from read mode to write mode on a buffered text-mode handle, see bug
1045 bmode <- case ha_type of
1046 ReadWriteHandle | not binary -> return NoBuffering
1047 _other -> return bmode
1050 spares <- newIORef BufferListNil
1051 newFileHandle filepath (handleFinalizer filepath)
1052 (Handle__ { haFD = fd,
1055 haIsStream = is_stream,
1056 haBufferMode = bmode,
1059 haOtherSide = Nothing
1062 mkDuplexHandle :: FD -> Bool -> FilePath -> Bool -> IO Handle
1063 mkDuplexHandle fd is_stream filepath binary = do
1064 (w_buf, w_bmode) <- getBuffer fd WriteBuffer
1065 w_spares <- newIORef BufferListNil
1067 Handle__ { haFD = fd,
1068 haType = WriteHandle,
1070 haIsStream = is_stream,
1071 haBufferMode = w_bmode,
1073 haBuffers = w_spares,
1074 haOtherSide = Nothing
1076 write_side <- newMVar w_handle_
1078 (r_buf, r_bmode) <- getBuffer fd ReadBuffer
1079 r_spares <- newIORef BufferListNil
1081 Handle__ { haFD = fd,
1082 haType = ReadHandle,
1084 haIsStream = is_stream,
1085 haBufferMode = r_bmode,
1087 haBuffers = r_spares,
1088 haOtherSide = Just write_side
1090 read_side <- newMVar r_handle_
1092 addMVarFinalizer write_side (handleFinalizer filepath write_side)
1093 return (DuplexHandle filepath read_side write_side)
1096 initBufferState ReadHandle = ReadBuffer
1097 initBufferState _ = WriteBuffer
1099 -- ---------------------------------------------------------------------------
1102 -- | Computation 'hClose' @hdl@ makes handle @hdl@ closed. Before the
1103 -- computation finishes, if @hdl@ is writable its buffer is flushed as
1105 -- Performing 'hClose' on a handle that has already been closed has no effect;
1106 -- doing so is not an error. All other operations on a closed handle will fail.
1107 -- If 'hClose' fails for any reason, any further operations (apart from
1108 -- 'hClose') on the handle will still fail as if @hdl@ had been successfully
1111 hClose :: Handle -> IO ()
1112 hClose h@(FileHandle _ m) = do
1113 mb_exc <- hClose' h m
1115 Nothing -> return ()
1117 hClose h@(DuplexHandle _ r w) = do
1118 mb_exc1 <- hClose' h w
1119 mb_exc2 <- hClose' h r
1120 case (do mb_exc1; mb_exc2) of
1121 Nothing -> return ()
1124 hClose' h m = withHandle' "hClose" h m $ hClose_help
1126 -- hClose_help is also called by lazyRead (in PrelIO) when EOF is read
1127 -- or an IO error occurs on a lazy stream. The semi-closed Handle is
1128 -- then closed immediately. We have to be careful with DuplexHandles
1129 -- though: we have to leave the closing to the finalizer in that case,
1130 -- because the write side may still be in use.
1131 hClose_help :: Handle__ -> IO (Handle__, Maybe SomeException)
1132 hClose_help handle_ =
1133 case haType handle_ of
1134 ClosedHandle -> return (handle_,Nothing)
1135 _ -> do flushWriteBufferOnly handle_ -- interruptible
1136 hClose_handle_ handle_
1138 hClose_handle_ :: Handle__ -> IO (Handle__, Maybe SomeException)
1139 hClose_handle_ handle_ = do
1140 let fd = haFD handle_
1142 -- close the file descriptor, but not when this is the read
1143 -- side of a duplex handle.
1144 -- If an exception is raised by the close(), we want to continue
1145 -- to close the handle and release the lock if it has one, then
1146 -- we return the exception to the caller of hClose_help which can
1147 -- raise it if necessary.
1149 case haOtherSide handle_ of
1151 throwErrnoIfMinus1Retry_ "hClose"
1152 #ifdef mingw32_HOST_OS
1153 (closeFd (haIsStream handle_) fd)
1159 `catchException` \e -> return (Just e)
1161 Just _ -> return Nothing
1163 -- free the spare buffers
1164 writeIORef (haBuffers handle_) BufferListNil
1165 writeIORef (haBuffer handle_) noBuffer
1167 #ifndef mingw32_HOST_OS
1172 -- we must set the fd to -1, because the finalizer is going
1173 -- to run eventually and try to close/unlock it.
1174 return (handle_{ haFD = -1,
1175 haType = ClosedHandle
1179 {-# NOINLINE noBuffer #-}
1180 noBuffer = unsafePerformIO $ allocateBuffer 1 ReadBuffer
1182 -----------------------------------------------------------------------------
1183 -- Detecting and changing the size of a file
1185 -- | For a handle @hdl@ which attached to a physical file,
1186 -- 'hFileSize' @hdl@ returns the size of that file in 8-bit bytes.
1188 hFileSize :: Handle -> IO Integer
1190 withHandle_ "hFileSize" handle $ \ handle_ -> do
1191 case haType handle_ of
1192 ClosedHandle -> ioe_closedHandle
1193 SemiClosedHandle -> ioe_closedHandle
1194 _ -> do flushWriteBufferOnly handle_
1195 r <- fdFileSize (haFD handle_)
1198 else ioException (IOError Nothing InappropriateType "hFileSize"
1199 "not a regular file" Nothing)
1202 -- | 'hSetFileSize' @hdl@ @size@ truncates the physical file with handle @hdl@ to @size@ bytes.
1204 hSetFileSize :: Handle -> Integer -> IO ()
1205 hSetFileSize handle size =
1206 withHandle_ "hSetFileSize" handle $ \ handle_ -> do
1207 case haType handle_ of
1208 ClosedHandle -> ioe_closedHandle
1209 SemiClosedHandle -> ioe_closedHandle
1210 _ -> do flushWriteBufferOnly handle_
1211 throwErrnoIf (/=0) "hSetFileSize"
1212 (c_ftruncate (haFD handle_) (fromIntegral size))
1215 -- ---------------------------------------------------------------------------
1216 -- Detecting the End of Input
1218 -- | For a readable handle @hdl@, 'hIsEOF' @hdl@ returns
1219 -- 'True' if no further input can be taken from @hdl@ or for a
1220 -- physical file, if the current I\/O position is equal to the length of
1221 -- the file. Otherwise, it returns 'False'.
1223 -- NOTE: 'hIsEOF' may block, because it is the same as calling
1224 -- 'hLookAhead' and checking for an EOF exception.
1226 hIsEOF :: Handle -> IO Bool
1229 (do hLookAhead handle; return False)
1230 (\e -> if isEOFError e then return True else ioError e)
1232 -- | The computation 'isEOF' is identical to 'hIsEOF',
1233 -- except that it works only on 'stdin'.
1236 isEOF = hIsEOF stdin
1238 -- ---------------------------------------------------------------------------
1241 -- | Computation 'hLookAhead' returns the next character from the handle
1242 -- without removing it from the input buffer, blocking until a character
1245 -- This operation may fail with:
1247 -- * 'isEOFError' if the end of file has been reached.
1249 hLookAhead :: Handle -> IO Char
1250 hLookAhead handle = do
1251 wantReadableHandle "hLookAhead" handle $ \handle_ -> do
1252 let ref = haBuffer handle_
1254 is_line = haBufferMode handle_ == LineBuffering
1255 buf <- readIORef ref
1257 -- fill up the read buffer if necessary
1258 new_buf <- if bufferEmpty buf
1259 then fillReadBuffer fd True (haIsStream handle_) buf
1262 writeIORef ref new_buf
1264 (c,_) <- readCharFromBuffer (bufBuf buf) (bufRPtr buf)
1267 -- ---------------------------------------------------------------------------
1268 -- Buffering Operations
1270 -- Three kinds of buffering are supported: line-buffering,
1271 -- block-buffering or no-buffering. See GHC.IOBase for definition and
1272 -- further explanation of what the type represent.
1274 -- | Computation 'hSetBuffering' @hdl mode@ sets the mode of buffering for
1275 -- handle @hdl@ on subsequent reads and writes.
1277 -- If the buffer mode is changed from 'BlockBuffering' or
1278 -- 'LineBuffering' to 'NoBuffering', then
1280 -- * if @hdl@ is writable, the buffer is flushed as for 'hFlush';
1282 -- * if @hdl@ is not writable, the contents of the buffer is discarded.
1284 -- This operation may fail with:
1286 -- * 'isPermissionError' if the handle has already been used for reading
1287 -- or writing and the implementation does not allow the buffering mode
1290 hSetBuffering :: Handle -> BufferMode -> IO ()
1291 hSetBuffering handle mode =
1292 withAllHandles__ "hSetBuffering" handle $ \ handle_ -> do
1293 case haType handle_ of
1294 ClosedHandle -> ioe_closedHandle
1297 - we flush the old buffer regardless of whether
1298 the new buffer could fit the contents of the old buffer
1300 - allow a handle's buffering to change even if IO has
1301 occurred (ANSI C spec. does not allow this, nor did
1302 the previous implementation of IO.hSetBuffering).
1303 - a non-standard extension is to allow the buffering
1304 of semi-closed handles to change [sof 6/98]
1308 let state = initBufferState (haType handle_)
1311 -- we always have a 1-character read buffer for
1312 -- unbuffered handles: it's needed to
1313 -- support hLookAhead.
1314 NoBuffering -> allocateBuffer 1 ReadBuffer
1315 LineBuffering -> allocateBuffer dEFAULT_BUFFER_SIZE state
1316 BlockBuffering Nothing -> allocateBuffer dEFAULT_BUFFER_SIZE state
1317 BlockBuffering (Just n) | n <= 0 -> ioe_bufsiz n
1318 | otherwise -> allocateBuffer n state
1319 writeIORef (haBuffer handle_) new_buf
1321 -- for input terminals we need to put the terminal into
1322 -- cooked or raw mode depending on the type of buffering.
1323 is_tty <- fdIsTTY (haFD handle_)
1324 when (is_tty && isReadableHandleType (haType handle_)) $
1326 #ifndef mingw32_HOST_OS
1327 -- 'raw' mode under win32 is a bit too specialised (and troublesome
1328 -- for most common uses), so simply disable its use here.
1329 NoBuffering -> setCooked (haFD handle_) False
1331 NoBuffering -> return ()
1333 _ -> setCooked (haFD handle_) True
1335 -- throw away spare buffers, they might be the wrong size
1336 writeIORef (haBuffers handle_) BufferListNil
1338 return (handle_{ haBufferMode = mode })
1340 -- -----------------------------------------------------------------------------
1343 -- | The action 'hFlush' @hdl@ causes any items buffered for output
1344 -- in handle @hdl@ to be sent immediately to the operating system.
1346 -- This operation may fail with:
1348 -- * 'isFullError' if the device is full;
1350 -- * 'isPermissionError' if a system resource limit would be exceeded.
1351 -- It is unspecified whether the characters in the buffer are discarded
1352 -- or retained under these circumstances.
1354 hFlush :: Handle -> IO ()
1356 wantWritableHandle "hFlush" handle $ \ handle_ -> do
1357 buf <- readIORef (haBuffer handle_)
1358 if bufferIsWritable buf && not (bufferEmpty buf)
1359 then do flushed_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
1360 writeIORef (haBuffer handle_) flushed_buf
1364 -- -----------------------------------------------------------------------------
1365 -- Repositioning Handles
1367 data HandlePosn = HandlePosn Handle HandlePosition
1369 instance Eq HandlePosn where
1370 (HandlePosn h1 p1) == (HandlePosn h2 p2) = p1==p2 && h1==h2
1372 instance Show HandlePosn where
1373 showsPrec p (HandlePosn h pos) =
1374 showsPrec p h . showString " at position " . shows pos
1376 -- HandlePosition is the Haskell equivalent of POSIX' off_t.
1377 -- We represent it as an Integer on the Haskell side, but
1378 -- cheat slightly in that hGetPosn calls upon a C helper
1379 -- that reports the position back via (merely) an Int.
1380 type HandlePosition = Integer
1382 -- | Computation 'hGetPosn' @hdl@ returns the current I\/O position of
1383 -- @hdl@ as a value of the abstract type 'HandlePosn'.
1385 hGetPosn :: Handle -> IO HandlePosn
1386 hGetPosn handle = do
1387 posn <- hTell handle
1388 return (HandlePosn handle posn)
1390 -- | If a call to 'hGetPosn' @hdl@ returns a position @p@,
1391 -- then computation 'hSetPosn' @p@ sets the position of @hdl@
1392 -- to the position it held at the time of the call to 'hGetPosn'.
1394 -- This operation may fail with:
1396 -- * 'isPermissionError' if a system resource limit would be exceeded.
1398 hSetPosn :: HandlePosn -> IO ()
1399 hSetPosn (HandlePosn h i) = hSeek h AbsoluteSeek i
1401 -- ---------------------------------------------------------------------------
1404 -- | A mode that determines the effect of 'hSeek' @hdl mode i@, as follows:
1406 = AbsoluteSeek -- ^ the position of @hdl@ is set to @i@.
1407 | RelativeSeek -- ^ the position of @hdl@ is set to offset @i@
1408 -- from the current position.
1409 | SeekFromEnd -- ^ the position of @hdl@ is set to offset @i@
1410 -- from the end of the file.
1411 deriving (Eq, Ord, Ix, Enum, Read, Show)
1414 - when seeking using `SeekFromEnd', positive offsets (>=0) means
1415 seeking at or past EOF.
1417 - we possibly deviate from the report on the issue of seeking within
1418 the buffer and whether to flush it or not. The report isn't exactly
1422 -- | Computation 'hSeek' @hdl mode i@ sets the position of handle
1423 -- @hdl@ depending on @mode@.
1424 -- The offset @i@ is given in terms of 8-bit bytes.
1426 -- If @hdl@ is block- or line-buffered, then seeking to a position which is not
1427 -- in the current buffer will first cause any items in the output buffer to be
1428 -- written to the device, and then cause the input buffer to be discarded.
1429 -- Some handles may not be seekable (see 'hIsSeekable'), or only support a
1430 -- subset of the possible positioning operations (for instance, it may only
1431 -- be possible to seek to the end of a tape, or to a positive offset from
1432 -- the beginning or current position).
1433 -- It is not possible to set a negative I\/O position, or for
1434 -- a physical file, an I\/O position beyond the current end-of-file.
1436 -- This operation may fail with:
1438 -- * 'isPermissionError' if a system resource limit would be exceeded.
1440 hSeek :: Handle -> SeekMode -> Integer -> IO ()
1441 hSeek handle mode offset =
1442 wantSeekableHandle "hSeek" handle $ \ handle_ -> do
1444 puts ("hSeek " ++ show (mode,offset) ++ "\n")
1446 let ref = haBuffer handle_
1447 buf <- readIORef ref
1453 throwErrnoIfMinus1Retry_ "hSeek"
1454 (c_lseek (haFD handle_) (fromIntegral offset) whence)
1457 whence = case mode of
1458 AbsoluteSeek -> sEEK_SET
1459 RelativeSeek -> sEEK_CUR
1460 SeekFromEnd -> sEEK_END
1462 if bufferIsWritable buf
1463 then do new_buf <- flushWriteBuffer fd (haIsStream handle_) buf
1464 writeIORef ref new_buf
1468 if mode == RelativeSeek && offset >= 0 && offset < fromIntegral (w - r)
1469 then writeIORef ref buf{ bufRPtr = r + fromIntegral offset }
1472 new_buf <- flushReadBuffer (haFD handle_) buf
1473 writeIORef ref new_buf
1477 hTell :: Handle -> IO Integer
1479 wantSeekableHandle "hGetPosn" handle $ \ handle_ -> do
1481 #if defined(mingw32_HOST_OS)
1482 -- urgh, on Windows we have to worry about \n -> \r\n translation,
1483 -- so we can't easily calculate the file position using the
1484 -- current buffer size. Just flush instead.
1487 let fd = haFD handle_
1488 posn <- fromIntegral `liftM`
1489 throwErrnoIfMinus1Retry "hGetPosn"
1490 (c_lseek fd 0 sEEK_CUR)
1492 let ref = haBuffer handle_
1493 buf <- readIORef ref
1496 | bufferIsWritable buf = posn + fromIntegral (bufWPtr buf)
1497 | otherwise = posn - fromIntegral (bufWPtr buf - bufRPtr buf)
1499 puts ("\nhGetPosn: (fd, posn, real_posn) = " ++ show (fd, posn, real_posn) ++ "\n")
1500 puts (" (bufWPtr, bufRPtr) = " ++ show (bufWPtr buf, bufRPtr buf) ++ "\n")
1504 -- -----------------------------------------------------------------------------
1505 -- Handle Properties
1507 -- A number of operations return information about the properties of a
1508 -- handle. Each of these operations returns `True' if the handle has
1509 -- the specified property, and `False' otherwise.
1511 hIsOpen :: Handle -> IO Bool
1513 withHandle_ "hIsOpen" handle $ \ handle_ -> do
1514 case haType handle_ of
1515 ClosedHandle -> return False
1516 SemiClosedHandle -> return False
1519 hIsClosed :: Handle -> IO Bool
1521 withHandle_ "hIsClosed" handle $ \ handle_ -> do
1522 case haType handle_ of
1523 ClosedHandle -> return True
1526 {- not defined, nor exported, but mentioned
1527 here for documentation purposes:
1529 hSemiClosed :: Handle -> IO Bool
1533 return (not (ho || hc))
1536 hIsReadable :: Handle -> IO Bool
1537 hIsReadable (DuplexHandle _ _ _) = return True
1538 hIsReadable handle =
1539 withHandle_ "hIsReadable" handle $ \ handle_ -> do
1540 case haType handle_ of
1541 ClosedHandle -> ioe_closedHandle
1542 SemiClosedHandle -> ioe_closedHandle
1543 htype -> return (isReadableHandleType htype)
1545 hIsWritable :: Handle -> IO Bool
1546 hIsWritable (DuplexHandle _ _ _) = return True
1547 hIsWritable handle =
1548 withHandle_ "hIsWritable" handle $ \ handle_ -> do
1549 case haType handle_ of
1550 ClosedHandle -> ioe_closedHandle
1551 SemiClosedHandle -> ioe_closedHandle
1552 htype -> return (isWritableHandleType htype)
1554 -- | Computation 'hGetBuffering' @hdl@ returns the current buffering mode
1557 hGetBuffering :: Handle -> IO BufferMode
1558 hGetBuffering handle =
1559 withHandle_ "hGetBuffering" handle $ \ handle_ -> do
1560 case haType handle_ of
1561 ClosedHandle -> ioe_closedHandle
1563 -- We're being non-standard here, and allow the buffering
1564 -- of a semi-closed handle to be queried. -- sof 6/98
1565 return (haBufferMode handle_) -- could be stricter..
1567 hIsSeekable :: Handle -> IO Bool
1568 hIsSeekable handle =
1569 withHandle_ "hIsSeekable" handle $ \ handle_ -> do
1570 case haType handle_ of
1571 ClosedHandle -> ioe_closedHandle
1572 SemiClosedHandle -> ioe_closedHandle
1573 AppendHandle -> return False
1574 _ -> do t <- fdType (haFD handle_)
1575 return ((t == RegularFile || t == RawDevice)
1576 && (haIsBin handle_ || tEXT_MODE_SEEK_ALLOWED))
1578 -- -----------------------------------------------------------------------------
1579 -- Changing echo status (Non-standard GHC extensions)
1581 -- | Set the echoing status of a handle connected to a terminal.
1583 hSetEcho :: Handle -> Bool -> IO ()
1584 hSetEcho handle on = do
1585 isT <- hIsTerminalDevice handle
1589 withHandle_ "hSetEcho" handle $ \ handle_ -> do
1590 case haType handle_ of
1591 ClosedHandle -> ioe_closedHandle
1592 _ -> setEcho (haFD handle_) on
1594 -- | Get the echoing status of a handle connected to a terminal.
1596 hGetEcho :: Handle -> IO Bool
1597 hGetEcho handle = do
1598 isT <- hIsTerminalDevice handle
1602 withHandle_ "hGetEcho" handle $ \ handle_ -> do
1603 case haType handle_ of
1604 ClosedHandle -> ioe_closedHandle
1605 _ -> getEcho (haFD handle_)
1607 -- | Is the handle connected to a terminal?
1609 hIsTerminalDevice :: Handle -> IO Bool
1610 hIsTerminalDevice handle = do
1611 withHandle_ "hIsTerminalDevice" handle $ \ handle_ -> do
1612 case haType handle_ of
1613 ClosedHandle -> ioe_closedHandle
1614 _ -> fdIsTTY (haFD handle_)
1616 -- -----------------------------------------------------------------------------
1619 -- | Select binary mode ('True') or text mode ('False') on a open handle.
1620 -- (See also 'openBinaryFile'.)
1622 hSetBinaryMode :: Handle -> Bool -> IO ()
1623 hSetBinaryMode handle bin =
1624 withAllHandles__ "hSetBinaryMode" handle $ \ handle_ ->
1625 do throwErrnoIfMinus1_ "hSetBinaryMode"
1626 (setmode (haFD handle_) bin)
1627 return handle_{haIsBin=bin}
1629 foreign import ccall unsafe "__hscore_setmode"
1630 setmode :: CInt -> Bool -> IO CInt
1632 -- -----------------------------------------------------------------------------
1633 -- Duplicating a Handle
1635 -- | Returns a duplicate of the original handle, with its own buffer.
1636 -- The two Handles will share a file pointer, however. The original
1637 -- handle's buffer is flushed, including discarding any input data,
1638 -- before the handle is duplicated.
1640 hDuplicate :: Handle -> IO Handle
1641 hDuplicate h@(FileHandle path m) = do
1642 new_h_ <- withHandle' "hDuplicate" h m (dupHandle h Nothing)
1643 newFileHandle path (handleFinalizer path) new_h_
1644 hDuplicate h@(DuplexHandle path r w) = do
1645 new_w_ <- withHandle' "hDuplicate" h w (dupHandle h Nothing)
1646 new_w <- newMVar new_w_
1647 new_r_ <- withHandle' "hDuplicate" h r (dupHandle h (Just new_w))
1648 new_r <- newMVar new_r_
1649 addMVarFinalizer new_w (handleFinalizer path new_w)
1650 return (DuplexHandle path new_r new_w)
1652 dupHandle :: Handle -> Maybe (MVar Handle__) -> Handle__
1653 -> IO (Handle__, Handle__)
1654 dupHandle h other_side h_ = do
1655 -- flush the buffer first, so we don't have to copy its contents
1657 new_fd <- case other_side of
1658 Nothing -> throwErrnoIfMinus1 "dupHandle" $ c_dup (haFD h_)
1659 Just r -> withHandle_' "dupHandle" h r (return . haFD)
1660 dupHandle_ other_side h_ new_fd
1662 dupHandleTo other_side hto_ h_ = do
1664 -- Windows' dup2 does not return the new descriptor, unlike Unix
1665 throwErrnoIfMinus1 "dupHandleTo" $
1666 c_dup2 (haFD h_) (haFD hto_)
1667 dupHandle_ other_side h_ (haFD hto_)
1669 dupHandle_ :: Maybe (MVar Handle__) -> Handle__ -> FD
1670 -> IO (Handle__, Handle__)
1671 dupHandle_ other_side h_ new_fd = do
1672 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE (initBufferState (haType h_))
1673 ioref <- newIORef buffer
1674 ioref_buffers <- newIORef BufferListNil
1676 let new_handle_ = h_{ haFD = new_fd,
1678 haBuffers = ioref_buffers,
1679 haOtherSide = other_side }
1680 return (h_, new_handle_)
1682 -- -----------------------------------------------------------------------------
1683 -- Replacing a Handle
1686 Makes the second handle a duplicate of the first handle. The second
1687 handle will be closed first, if it is not already.
1689 This can be used to retarget the standard Handles, for example:
1691 > do h <- openFile "mystdout" WriteMode
1692 > hDuplicateTo h stdout
1695 hDuplicateTo :: Handle -> Handle -> IO ()
1696 hDuplicateTo h1@(FileHandle _ m1) h2@(FileHandle _ m2) = do
1697 withHandle__' "hDuplicateTo" h2 m2 $ \h2_ -> do
1698 _ <- hClose_help h2_
1699 withHandle' "hDuplicateTo" h1 m1 (dupHandleTo Nothing h2_)
1700 hDuplicateTo h1@(DuplexHandle _ r1 w1) h2@(DuplexHandle _ r2 w2) = do
1701 withHandle__' "hDuplicateTo" h2 w2 $ \w2_ -> do
1702 _ <- hClose_help w2_
1703 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo Nothing w2_)
1704 withHandle__' "hDuplicateTo" h2 r2 $ \r2_ -> do
1705 _ <- hClose_help r2_
1706 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo (Just w1) r2_)
1708 ioException (IOError (Just h1) IllegalOperation "hDuplicateTo"
1709 "handles are incompatible" Nothing)
1711 -- ---------------------------------------------------------------------------
1714 -- | 'hShow' is in the 'IO' monad, and gives more comprehensive output
1715 -- than the (pure) instance of 'Show' for 'Handle'.
1717 hShow :: Handle -> IO String
1718 hShow h@(FileHandle path _) = showHandle' path False h
1719 hShow h@(DuplexHandle path _ _) = showHandle' path True h
1721 showHandle' filepath is_duplex h =
1722 withHandle_ "showHandle" h $ \hdl_ ->
1724 showType | is_duplex = showString "duplex (read-write)"
1725 | otherwise = shows (haType hdl_)
1729 showHdl (haType hdl_)
1730 (showString "loc=" . showString filepath . showChar ',' .
1731 showString "type=" . showType . showChar ',' .
1732 showString "binary=" . shows (haIsBin hdl_) . showChar ',' .
1733 showString "buffering=" . showBufMode (unsafePerformIO (readIORef (haBuffer hdl_))) (haBufferMode hdl_) . showString "}" )
1737 showHdl :: HandleType -> ShowS -> ShowS
1740 ClosedHandle -> shows ht . showString "}"
1743 showBufMode :: Buffer -> BufferMode -> ShowS
1744 showBufMode buf bmo =
1746 NoBuffering -> showString "none"
1747 LineBuffering -> showString "line"
1748 BlockBuffering (Just n) -> showString "block " . showParen True (shows n)
1749 BlockBuffering Nothing -> showString "block " . showParen True (shows def)
1754 -- ---------------------------------------------------------------------------
1757 #if defined(DEBUG_DUMP)
1758 puts :: String -> IO ()
1759 puts s = do write_rawBuffer 1 (unsafeCoerce# (packCString# s)) 0 (fromIntegral (length s))
1763 -- -----------------------------------------------------------------------------
1766 throwErrnoIfMinus1RetryOnBlock :: String -> IO CInt -> IO CInt -> IO CInt
1767 throwErrnoIfMinus1RetryOnBlock loc f on_block =
1770 if (res :: CInt) == -1
1774 then throwErrnoIfMinus1RetryOnBlock loc f on_block
1775 else if err == eWOULDBLOCK || err == eAGAIN
1780 -- -----------------------------------------------------------------------------
1781 -- wrappers to platform-specific constants:
1783 foreign import ccall unsafe "__hscore_supportsTextMode"
1784 tEXT_MODE_SEEK_ALLOWED :: Bool
1786 foreign import ccall unsafe "__hscore_bufsiz" dEFAULT_BUFFER_SIZE :: Int
1787 foreign import ccall unsafe "__hscore_seek_cur" sEEK_CUR :: CInt
1788 foreign import ccall unsafe "__hscore_seek_set" sEEK_SET :: CInt
1789 foreign import ccall unsafe "__hscore_seek_end" sEEK_END :: CInt