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,
64 import System.IO.Error
65 import System.Posix.Internals
66 import System.Posix.Types
72 import GHC.Read ( Read )
77 import GHC.Num ( Integer(..), Num(..) )
79 #if defined(DEBUG_DUMP)
85 -- -----------------------------------------------------------------------------
88 -- hWaitForInput blocks (should use a timeout)
90 -- unbuffered hGetLine is a bit dodgy
92 -- hSetBuffering: can't change buffering on a stream,
93 -- when the read buffer is non-empty? (no way to flush the buffer)
95 -- ---------------------------------------------------------------------------
96 -- Are files opened by default in text or binary mode, if the user doesn't
99 dEFAULT_OPEN_IN_BINARY_MODE = False :: Bool
101 -- ---------------------------------------------------------------------------
102 -- Creating a new handle
104 newFileHandle :: FilePath -> (MVar Handle__ -> IO ()) -> Handle__ -> IO Handle
105 newFileHandle filepath finalizer hc = do
107 addMVarFinalizer m (finalizer m)
108 return (FileHandle filepath m)
110 -- ---------------------------------------------------------------------------
111 -- Working with Handles
114 In the concurrent world, handles are locked during use. This is done
115 by wrapping an MVar around the handle which acts as a mutex over
116 operations on the handle.
118 To avoid races, we use the following bracketing operations. The idea
119 is to obtain the lock, do some operation and replace the lock again,
120 whether the operation succeeded or failed. We also want to handle the
121 case where the thread receives an exception while processing the IO
122 operation: in these cases we also want to relinquish the lock.
124 There are three versions of @withHandle@: corresponding to the three
125 possible combinations of:
127 - the operation may side-effect the handle
128 - the operation may return a result
130 If the operation generates an error or an exception is raised, the
131 original handle is always replaced [ this is the case at the moment,
132 but we might want to revisit this in the future --SDM ].
135 {-# INLINE withHandle #-}
136 withHandle :: String -> Handle -> (Handle__ -> IO (Handle__,a)) -> IO a
137 withHandle fun h@(FileHandle _ m) act = withHandle' fun h m act
138 withHandle fun h@(DuplexHandle _ m _) act = withHandle' fun h m act
140 withHandle' :: String -> Handle -> MVar Handle__
141 -> (Handle__ -> IO (Handle__,a)) -> IO a
142 withHandle' fun h m act =
145 checkBufferInvariants h_
146 (h',v) <- (act h_ `catchAny` \err -> putMVar m h_ >> throw err)
147 `catchException` \ex -> ioError (augmentIOError ex fun h)
148 checkBufferInvariants h'
152 {-# INLINE withHandle_ #-}
153 withHandle_ :: String -> Handle -> (Handle__ -> IO a) -> IO a
154 withHandle_ fun h@(FileHandle _ m) act = withHandle_' fun h m act
155 withHandle_ fun h@(DuplexHandle _ m _) act = withHandle_' fun h m act
157 withHandle_' :: String -> Handle -> MVar Handle__ -> (Handle__ -> IO a) -> IO a
158 withHandle_' fun h m act =
161 checkBufferInvariants h_
162 v <- (act h_ `catchAny` \err -> putMVar m h_ >> throw err)
163 `catchException` \ex -> ioError (augmentIOError ex fun h)
164 checkBufferInvariants h_
168 withAllHandles__ :: String -> Handle -> (Handle__ -> IO Handle__) -> IO ()
169 withAllHandles__ fun h@(FileHandle _ m) act = withHandle__' fun h m act
170 withAllHandles__ fun h@(DuplexHandle _ r w) act = do
171 withHandle__' fun h r act
172 withHandle__' fun h w act
174 withHandle__' fun h m act =
177 checkBufferInvariants h_
178 h' <- (act h_ `catchAny` \err -> putMVar m h_ >> throw err)
179 `catchException` \ex -> ioError (augmentIOError ex fun h)
180 checkBufferInvariants h'
184 augmentIOError (IOError _ iot _ str fp) fun h
185 = IOError (Just h) iot fun str filepath
188 | otherwise = case h of
189 FileHandle fp _ -> Just fp
190 DuplexHandle fp _ _ -> Just fp
192 -- ---------------------------------------------------------------------------
193 -- Wrapper for write operations.
195 wantWritableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
196 wantWritableHandle fun h@(FileHandle _ m) act
197 = wantWritableHandle' fun h m act
198 wantWritableHandle fun h@(DuplexHandle _ _ m) act
199 = wantWritableHandle' fun h m act
200 -- ToDo: in the Duplex case, we don't need to checkWritableHandle
203 :: String -> Handle -> MVar Handle__
204 -> (Handle__ -> IO a) -> IO a
205 wantWritableHandle' fun h m act
206 = withHandle_' fun h m (checkWritableHandle act)
208 checkWritableHandle act handle_
209 = case haType handle_ of
210 ClosedHandle -> ioe_closedHandle
211 SemiClosedHandle -> ioe_closedHandle
212 ReadHandle -> ioe_notWritable
213 ReadWriteHandle -> do
214 let ref = haBuffer handle_
217 if not (bufferIsWritable buf)
218 then do b <- flushReadBuffer (haFD handle_) buf
219 return b{ bufState=WriteBuffer }
221 writeIORef ref new_buf
223 _other -> act handle_
225 -- ---------------------------------------------------------------------------
226 -- Wrapper for read operations.
228 wantReadableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
229 wantReadableHandle fun h@(FileHandle _ m) act
230 = wantReadableHandle' fun h m act
231 wantReadableHandle fun h@(DuplexHandle _ m _) act
232 = wantReadableHandle' fun h m act
233 -- ToDo: in the Duplex case, we don't need to checkReadableHandle
236 :: String -> Handle -> MVar Handle__
237 -> (Handle__ -> IO a) -> IO a
238 wantReadableHandle' fun h m act
239 = withHandle_' fun h m (checkReadableHandle act)
241 checkReadableHandle act handle_ =
242 case haType handle_ of
243 ClosedHandle -> ioe_closedHandle
244 SemiClosedHandle -> ioe_closedHandle
245 AppendHandle -> ioe_notReadable
246 WriteHandle -> ioe_notReadable
247 ReadWriteHandle -> do
248 let ref = haBuffer handle_
250 when (bufferIsWritable buf) $ do
251 new_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
252 writeIORef ref new_buf{ bufState=ReadBuffer }
254 _other -> act handle_
256 -- ---------------------------------------------------------------------------
257 -- Wrapper for seek operations.
259 wantSeekableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
260 wantSeekableHandle fun h@(DuplexHandle _ _ _) _act =
261 ioException (IOError (Just h) IllegalOperation fun
262 "handle is not seekable" Nothing)
263 wantSeekableHandle fun h@(FileHandle _ m) act =
264 withHandle_' fun h m (checkSeekableHandle act)
266 checkSeekableHandle act handle_ =
267 case haType handle_ of
268 ClosedHandle -> ioe_closedHandle
269 SemiClosedHandle -> ioe_closedHandle
270 AppendHandle -> ioe_notSeekable
271 _ | haIsBin handle_ || tEXT_MODE_SEEK_ALLOWED -> act handle_
272 | otherwise -> ioe_notSeekable_notBin
274 -- -----------------------------------------------------------------------------
277 ioe_closedHandle, ioe_EOF,
278 ioe_notReadable, ioe_notWritable,
279 ioe_notSeekable, ioe_notSeekable_notBin :: IO a
281 ioe_closedHandle = ioException
282 (IOError Nothing IllegalOperation ""
283 "handle is closed" Nothing)
284 ioe_EOF = ioException
285 (IOError Nothing EOF "" "" Nothing)
286 ioe_notReadable = ioException
287 (IOError Nothing IllegalOperation ""
288 "handle is not open for reading" Nothing)
289 ioe_notWritable = ioException
290 (IOError Nothing IllegalOperation ""
291 "handle is not open for writing" Nothing)
292 ioe_notSeekable = ioException
293 (IOError Nothing IllegalOperation ""
294 "handle is not seekable" Nothing)
295 ioe_notSeekable_notBin = ioException
296 (IOError Nothing IllegalOperation ""
297 "seek operations on text-mode handles are not allowed on this platform"
300 ioe_finalizedHandle fp = throw
301 (IOError Nothing IllegalOperation ""
302 "handle is finalized" (Just fp))
304 ioe_bufsiz :: Int -> IO a
305 ioe_bufsiz n = ioException
306 (IOError Nothing InvalidArgument "hSetBuffering"
307 ("illegal buffer size " ++ showsPrec 9 n []) Nothing)
308 -- 9 => should be parens'ified.
310 -- -----------------------------------------------------------------------------
313 -- For a duplex handle, we arrange that the read side points to the write side
314 -- (and hence keeps it alive if the read side is alive). This is done by
315 -- having the haOtherSide field of the read side point to the read side.
316 -- The finalizer is then placed on the write side, and the handle only gets
317 -- finalized once, when both sides are no longer required.
319 -- NOTE about finalized handles: It's possible that a handle can be
320 -- finalized and then we try to use it later, for example if the
321 -- handle is referenced from another finalizer, or from a thread that
322 -- has become unreferenced and then resurrected (arguably in the
323 -- latter case we shouldn't finalize the Handle...). Anyway,
324 -- we try to emit a helpful message which is better than nothing.
326 stdHandleFinalizer :: FilePath -> MVar Handle__ -> IO ()
327 stdHandleFinalizer fp m = do
329 flushWriteBufferOnly h_
330 putMVar m (ioe_finalizedHandle fp)
332 handleFinalizer :: FilePath -> MVar Handle__ -> IO ()
333 handleFinalizer fp m = do
334 handle_ <- takeMVar m
335 case haType handle_ of
336 ClosedHandle -> return ()
337 _ -> do flushWriteBufferOnly handle_ `catchAny` \_ -> return ()
338 -- ignore errors and async exceptions, and close the
339 -- descriptor anyway...
340 hClose_handle_ handle_
342 putMVar m (ioe_finalizedHandle fp)
344 -- ---------------------------------------------------------------------------
345 -- Grimy buffer operations
348 checkBufferInvariants h_ = do
349 let ref = haBuffer h_
350 Buffer{ bufWPtr=w, bufRPtr=r, bufSize=size, bufState=state } <- readIORef ref
355 && ( r /= w || (r == 0 && w == 0) )
356 && ( state /= WriteBuffer || r == 0 )
357 && ( state /= WriteBuffer || w < size ) -- write buffer is never full
359 then error "buffer invariant violation"
362 checkBufferInvariants h_ = return ()
365 newEmptyBuffer :: RawBuffer -> BufferState -> Int -> Buffer
366 newEmptyBuffer b state size
367 = Buffer{ bufBuf=b, bufRPtr=0, bufWPtr=0, bufSize=size, bufState=state }
369 allocateBuffer :: Int -> BufferState -> IO Buffer
370 allocateBuffer sz@(I# size) state = IO $ \s ->
371 -- We sometimes need to pass the address of this buffer to
372 -- a "safe" foreign call, hence it must be immovable.
373 case newPinnedByteArray# size s of { (# s, b #) ->
374 (# s, newEmptyBuffer b state sz #) }
376 writeCharIntoBuffer :: RawBuffer -> Int -> Char -> IO Int
377 writeCharIntoBuffer slab (I# off) (C# c)
378 = IO $ \s -> case writeCharArray# slab off c s of
379 s -> (# s, I# (off +# 1#) #)
381 readCharFromBuffer :: RawBuffer -> Int -> IO (Char, Int)
382 readCharFromBuffer slab (I# off)
383 = IO $ \s -> case readCharArray# slab off s of
384 (# s, c #) -> (# s, (C# c, I# (off +# 1#)) #)
386 getBuffer :: FD -> BufferState -> IO (IORef Buffer, BufferMode)
387 getBuffer fd state = do
388 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE state
389 ioref <- newIORef buffer
393 | is_tty = LineBuffering
394 | otherwise = BlockBuffering Nothing
396 return (ioref, buffer_mode)
398 mkUnBuffer :: IO (IORef Buffer)
400 buffer <- allocateBuffer 1 ReadBuffer
403 -- flushWriteBufferOnly flushes the buffer iff it contains pending write data.
404 flushWriteBufferOnly :: Handle__ -> IO ()
405 flushWriteBufferOnly h_ = do
409 new_buf <- if bufferIsWritable buf
410 then flushWriteBuffer fd (haIsStream h_) buf
412 writeIORef ref new_buf
414 -- flushBuffer syncs the file with the buffer, including moving the
415 -- file pointer backwards in the case of a read buffer.
416 flushBuffer :: Handle__ -> IO ()
418 let ref = haBuffer h_
423 ReadBuffer -> flushReadBuffer (haFD h_) buf
424 WriteBuffer -> flushWriteBuffer (haFD h_) (haIsStream h_) buf
426 writeIORef ref flushed_buf
428 -- When flushing a read buffer, we seek backwards by the number of
429 -- characters in the buffer. The file descriptor must therefore be
430 -- seekable: attempting to flush the read buffer on an unseekable
431 -- handle is not allowed.
433 flushReadBuffer :: FD -> Buffer -> IO Buffer
434 flushReadBuffer fd buf
435 | bufferEmpty buf = return buf
437 let off = negate (bufWPtr buf - bufRPtr buf)
439 puts ("flushReadBuffer: new file offset = " ++ show off ++ "\n")
441 throwErrnoIfMinus1Retry "flushReadBuffer"
442 (c_lseek fd (fromIntegral off) sEEK_CUR)
443 return buf{ bufWPtr=0, bufRPtr=0 }
445 flushWriteBuffer :: FD -> Bool -> Buffer -> IO Buffer
446 flushWriteBuffer fd is_stream buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w } =
447 seq fd $ do -- strictness hack
450 puts ("flushWriteBuffer, fd=" ++ show fd ++ ", bytes=" ++ show bytes ++ "\n")
453 then return (buf{ bufRPtr=0, bufWPtr=0 })
455 res <- writeRawBuffer "flushWriteBuffer" fd is_stream b
456 (fromIntegral r) (fromIntegral bytes)
457 let res' = fromIntegral res
459 then flushWriteBuffer fd is_stream (buf{ bufRPtr = r + res' })
460 else return buf{ bufRPtr=0, bufWPtr=0 }
462 fillReadBuffer :: FD -> Bool -> Bool -> Buffer -> IO Buffer
463 fillReadBuffer fd is_line is_stream
464 buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w, bufSize=size } =
465 -- buffer better be empty:
466 assert (r == 0 && w == 0) $ do
467 fillReadBufferLoop fd is_line is_stream buf b w size
469 -- For a line buffer, we just get the first chunk of data to arrive,
470 -- and don't wait for the whole buffer to be full (but we *do* wait
471 -- until some data arrives). This isn't really line buffering, but it
472 -- appears to be what GHC has done for a long time, and I suspect it
473 -- is more useful than line buffering in most cases.
475 fillReadBufferLoop fd is_line is_stream buf b w size = do
477 if bytes == 0 -- buffer full?
478 then return buf{ bufRPtr=0, bufWPtr=w }
481 puts ("fillReadBufferLoop: bytes = " ++ show bytes ++ "\n")
483 res <- readRawBuffer "fillReadBuffer" fd is_stream b
484 (fromIntegral w) (fromIntegral bytes)
485 let res' = fromIntegral res
487 puts ("fillReadBufferLoop: res' = " ++ show res' ++ "\n")
492 else return buf{ bufRPtr=0, bufWPtr=w }
493 else if res' < bytes && not is_line
494 then fillReadBufferLoop fd is_line is_stream buf b (w+res') size
495 else return buf{ bufRPtr=0, bufWPtr=w+res' }
498 fillReadBufferWithoutBlocking :: FD -> Bool -> Buffer -> IO Buffer
499 fillReadBufferWithoutBlocking fd is_stream
500 buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w, bufSize=size } =
501 -- buffer better be empty:
502 assert (r == 0 && w == 0) $ do
504 puts ("fillReadBufferLoopNoBlock: bytes = " ++ show size ++ "\n")
506 res <- readRawBufferNoBlock "fillReadBuffer" fd is_stream b
507 0 (fromIntegral size)
508 let res' = fromIntegral res
510 puts ("fillReadBufferLoopNoBlock: res' = " ++ show res' ++ "\n")
512 return buf{ bufRPtr=0, bufWPtr=res' }
514 -- Low level routines for reading/writing to (raw)buffers:
516 #ifndef mingw32_HOST_OS
521 Unix has broken semantics when it comes to non-blocking I/O: you can
522 set the O_NONBLOCK flag on an FD, but it applies to the all other FDs
523 attached to the same underlying file, pipe or TTY; there's no way to
524 have private non-blocking behaviour for an FD. See bug #724.
526 We fix this by only setting O_NONBLOCK on FDs that we create; FDs that
527 come from external sources or are exposed externally are left in
528 blocking mode. This solution has some problems though. We can't
529 completely simulate a non-blocking read without O_NONBLOCK: several
530 cases are wrong here. The cases that are wrong:
532 * reading/writing to a blocking FD in non-threaded mode.
533 In threaded mode, we just make a safe call to read().
534 In non-threaded mode we call select() before attempting to read,
535 but that leaves a small race window where the data can be read
536 from the file descriptor before we issue our blocking read().
537 * readRawBufferNoBlock for a blocking FD
541 In the threaded RTS we could just make safe calls to read()/write()
542 for file descriptors in blocking mode without worrying about blocking
543 other threads, but the problem with this is that the thread will be
544 uninterruptible while it is blocked in the foreign call. See #2363.
545 So now we always call fdReady() before reading, and if fdReady
546 indicates that there's no data, we call threadWaitRead.
550 readRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
551 readRawBuffer loc fd is_nonblock buf off len
552 | is_nonblock = unsafe_read -- unsafe is ok, it can't block
553 | otherwise = do r <- throwErrnoIfMinus1 loc
554 (unsafe_fdReady (fromIntegral fd) 0 0 0)
557 else do threadWaitRead (fromIntegral fd); read
559 do_read call = throwErrnoIfMinus1RetryMayBlock loc call
560 (threadWaitRead (fromIntegral fd))
561 read = if threaded then safe_read else unsafe_read
562 unsafe_read = do_read (read_rawBuffer fd buf off len)
563 safe_read = do_read (safe_read_rawBuffer fd buf off len)
565 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
566 readRawBufferPtr loc fd is_nonblock buf off len
567 | is_nonblock = unsafe_read -- unsafe is ok, it can't block
568 | otherwise = do r <- throwErrnoIfMinus1 loc
569 (unsafe_fdReady (fromIntegral fd) 0 0 0)
572 else do threadWaitRead (fromIntegral fd); read
574 do_read call = throwErrnoIfMinus1RetryMayBlock loc call
575 (threadWaitRead (fromIntegral fd))
576 read = if threaded then safe_read else unsafe_read
577 unsafe_read = do_read (read_off fd buf off len)
578 safe_read = do_read (safe_read_off fd buf off len)
580 readRawBufferNoBlock :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
581 readRawBufferNoBlock loc fd is_nonblock buf off len
582 | is_nonblock = unsafe_read -- unsafe is ok, it can't block
583 | otherwise = do r <- unsafe_fdReady (fromIntegral fd) 0 0 0
584 if r /= 0 then safe_read
586 -- XXX see note [nonblock]
588 do_read call = throwErrnoIfMinus1RetryOnBlock loc call (return 0)
589 unsafe_read = do_read (read_rawBuffer fd buf off len)
590 safe_read = do_read (safe_read_rawBuffer fd buf off len)
592 readRawBufferPtrNoBlock :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
593 readRawBufferPtrNoBlock loc fd is_nonblock buf off len
594 | is_nonblock = unsafe_read -- unsafe is ok, it can't block
595 | otherwise = do r <- unsafe_fdReady (fromIntegral fd) 0 0 0
596 if r /= 0 then safe_read
598 -- XXX see note [nonblock]
600 do_read call = throwErrnoIfMinus1RetryOnBlock loc call (return 0)
601 unsafe_read = do_read (read_off fd buf off len)
602 safe_read = do_read (safe_read_off fd buf off len)
604 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
605 writeRawBuffer loc fd is_nonblock buf off len
606 | is_nonblock = unsafe_write -- unsafe is ok, it can't block
607 | otherwise = do r <- unsafe_fdReady (fromIntegral fd) 1 0 0
610 else do threadWaitWrite (fromIntegral fd); write
612 do_write call = throwErrnoIfMinus1RetryMayBlock loc call
613 (threadWaitWrite (fromIntegral fd))
614 write = if threaded then safe_write else unsafe_write
615 unsafe_write = do_write (write_rawBuffer fd buf off len)
616 safe_write = do_write (safe_write_rawBuffer (fromIntegral fd) buf off len)
618 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
619 writeRawBufferPtr loc fd is_nonblock buf off len
620 | is_nonblock = unsafe_write -- unsafe is ok, it can't block
621 | otherwise = do r <- unsafe_fdReady (fromIntegral fd) 1 0 0
624 else do threadWaitWrite (fromIntegral fd); write
626 do_write call = throwErrnoIfMinus1RetryMayBlock loc call
627 (threadWaitWrite (fromIntegral fd))
628 write = if threaded then safe_write else unsafe_write
629 unsafe_write = do_write (write_off fd buf off len)
630 safe_write = do_write (safe_write_off (fromIntegral fd) buf off len)
632 foreign import ccall unsafe "__hscore_PrelHandle_read"
633 read_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
635 foreign import ccall unsafe "__hscore_PrelHandle_read"
636 read_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
638 foreign import ccall unsafe "__hscore_PrelHandle_write"
639 write_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
641 foreign import ccall unsafe "__hscore_PrelHandle_write"
642 write_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
644 foreign import ccall unsafe "fdReady"
645 unsafe_fdReady :: CInt -> CInt -> CInt -> CInt -> IO CInt
647 #else /* mingw32_HOST_OS.... */
649 readRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
650 readRawBuffer loc fd is_stream buf off len
651 | threaded = blockingReadRawBuffer loc fd is_stream buf off len
652 | otherwise = asyncReadRawBuffer loc fd is_stream buf off len
654 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
655 readRawBufferPtr loc fd is_stream buf off len
656 | threaded = blockingReadRawBufferPtr loc fd is_stream buf off len
657 | otherwise = asyncReadRawBufferPtr loc fd is_stream buf off len
659 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
660 writeRawBuffer loc fd is_stream buf off len
661 | threaded = blockingWriteRawBuffer loc fd is_stream buf off len
662 | otherwise = asyncWriteRawBuffer loc fd is_stream buf off len
664 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
665 writeRawBufferPtr loc fd is_stream buf off len
666 | threaded = blockingWriteRawBufferPtr loc fd is_stream buf off len
667 | otherwise = asyncWriteRawBufferPtr loc fd is_stream buf off len
669 -- ToDo: we don't have a non-blocking primitve read on Win32
670 readRawBufferNoBlock :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
671 readRawBufferNoBlock = readRawBuffer
673 readRawBufferPtrNoBlock :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
674 readRawBufferPtrNoBlock = readRawBufferPtr
675 -- Async versions of the read/write primitives, for the non-threaded RTS
677 asyncReadRawBuffer loc fd is_stream buf off len = do
678 (l, rc) <- asyncReadBA (fromIntegral fd) (if is_stream then 1 else 0)
679 (fromIntegral len) off buf
682 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
683 else return (fromIntegral l)
685 asyncReadRawBufferPtr loc fd is_stream buf off len = do
686 (l, rc) <- asyncRead (fromIntegral fd) (if is_stream then 1 else 0)
687 (fromIntegral len) (buf `plusPtr` off)
690 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
691 else return (fromIntegral l)
693 asyncWriteRawBuffer loc fd is_stream buf off len = do
694 (l, rc) <- asyncWriteBA (fromIntegral fd) (if is_stream then 1 else 0)
695 (fromIntegral len) off buf
698 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
699 else return (fromIntegral l)
701 asyncWriteRawBufferPtr loc fd is_stream buf off len = do
702 (l, rc) <- asyncWrite (fromIntegral fd) (if is_stream then 1 else 0)
703 (fromIntegral len) (buf `plusPtr` off)
706 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
707 else return (fromIntegral l)
709 -- Blocking versions of the read/write primitives, for the threaded RTS
711 blockingReadRawBuffer loc fd True buf off len =
712 throwErrnoIfMinus1Retry loc $
713 safe_recv_rawBuffer fd buf off len
714 blockingReadRawBuffer loc fd False buf off len =
715 throwErrnoIfMinus1Retry loc $
716 safe_read_rawBuffer fd buf off len
718 blockingReadRawBufferPtr loc fd True buf off len =
719 throwErrnoIfMinus1Retry loc $
720 safe_recv_off fd buf off len
721 blockingReadRawBufferPtr loc fd False buf off len =
722 throwErrnoIfMinus1Retry loc $
723 safe_read_off fd buf off len
725 blockingWriteRawBuffer loc fd True buf off len =
726 throwErrnoIfMinus1Retry loc $
727 safe_send_rawBuffer fd buf off len
728 blockingWriteRawBuffer loc fd False buf off len =
729 throwErrnoIfMinus1Retry loc $
730 safe_write_rawBuffer fd buf off len
732 blockingWriteRawBufferPtr loc fd True buf off len =
733 throwErrnoIfMinus1Retry loc $
734 safe_send_off fd buf off len
735 blockingWriteRawBufferPtr loc fd False buf off len =
736 throwErrnoIfMinus1Retry loc $
737 safe_write_off fd buf off len
739 -- NOTE: "safe" versions of the read/write calls for use by the threaded RTS.
740 -- These calls may block, but that's ok.
742 foreign import ccall safe "__hscore_PrelHandle_recv"
743 safe_recv_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
745 foreign import ccall safe "__hscore_PrelHandle_recv"
746 safe_recv_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
748 foreign import ccall safe "__hscore_PrelHandle_send"
749 safe_send_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
751 foreign import ccall safe "__hscore_PrelHandle_send"
752 safe_send_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
756 foreign import ccall "rtsSupportsBoundThreads" threaded :: Bool
758 foreign import ccall safe "__hscore_PrelHandle_read"
759 safe_read_rawBuffer :: FD -> RawBuffer -> Int -> CInt -> IO CInt
761 foreign import ccall safe "__hscore_PrelHandle_read"
762 safe_read_off :: FD -> Ptr CChar -> Int -> CInt -> IO CInt
764 foreign import ccall safe "__hscore_PrelHandle_write"
765 safe_write_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
767 foreign import ccall safe "__hscore_PrelHandle_write"
768 safe_write_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
770 -- ---------------------------------------------------------------------------
773 -- Three handles are allocated during program initialisation. The first
774 -- two manage input or output from the Haskell program's standard input
775 -- or output channel respectively. The third manages output to the
776 -- standard error channel. These handles are initially open.
782 -- | A handle managing input from the Haskell program's standard input channel.
784 stdin = unsafePerformIO $ do
785 -- ToDo: acquire lock
786 -- We don't set non-blocking mode on standard handles, because it may
787 -- confuse other applications attached to the same TTY/pipe
788 -- see Note [nonblock]
789 (buf, bmode) <- getBuffer fd_stdin ReadBuffer
790 mkStdHandle fd_stdin "<stdin>" ReadHandle buf bmode
792 -- | A handle managing output to the Haskell program's standard output channel.
794 stdout = unsafePerformIO $ do
795 -- ToDo: acquire lock
796 -- We don't set non-blocking mode on standard handles, because it may
797 -- confuse other applications attached to the same TTY/pipe
798 -- see Note [nonblock]
799 (buf, bmode) <- getBuffer fd_stdout WriteBuffer
800 mkStdHandle fd_stdout "<stdout>" WriteHandle buf bmode
802 -- | A handle managing output to the Haskell program's standard error channel.
804 stderr = unsafePerformIO $ do
805 -- ToDo: acquire lock
806 -- We don't set non-blocking mode on standard handles, because it may
807 -- confuse other applications attached to the same TTY/pipe
808 -- see Note [nonblock]
810 mkStdHandle fd_stderr "<stderr>" WriteHandle buf NoBuffering
812 -- ---------------------------------------------------------------------------
813 -- Opening and Closing Files
815 addFilePathToIOError fun fp (IOError h iot _ str _)
816 = IOError h iot fun str (Just fp)
818 -- | Computation 'openFile' @file mode@ allocates and returns a new, open
819 -- handle to manage the file @file@. It manages input if @mode@
820 -- is 'ReadMode', output if @mode@ is 'WriteMode' or 'AppendMode',
821 -- and both input and output if mode is 'ReadWriteMode'.
823 -- If the file does not exist and it is opened for output, it should be
824 -- created as a new file. If @mode@ is 'WriteMode' and the file
825 -- already exists, then it should be truncated to zero length.
826 -- Some operating systems delete empty files, so there is no guarantee
827 -- that the file will exist following an 'openFile' with @mode@
828 -- 'WriteMode' unless it is subsequently written to successfully.
829 -- The handle is positioned at the end of the file if @mode@ is
830 -- 'AppendMode', and otherwise at the beginning (in which case its
831 -- internal position is 0).
832 -- The initial buffer mode is implementation-dependent.
834 -- This operation may fail with:
836 -- * 'isAlreadyInUseError' if the file is already open and cannot be reopened;
838 -- * 'isDoesNotExistError' if the file does not exist; or
840 -- * 'isPermissionError' if the user does not have permission to open the file.
842 -- Note: if you will be working with files containing binary data, you'll want to
843 -- be using 'openBinaryFile'.
844 openFile :: FilePath -> IOMode -> IO Handle
847 (openFile' fp im dEFAULT_OPEN_IN_BINARY_MODE)
848 (\e -> ioError (addFilePathToIOError "openFile" fp e))
850 -- | Like 'openFile', but open the file in binary mode.
851 -- On Windows, reading a file in text mode (which is the default)
852 -- will translate CRLF to LF, and writing will translate LF to CRLF.
853 -- This is usually what you want with text files. With binary files
854 -- this is undesirable; also, as usual under Microsoft operating systems,
855 -- text mode treats control-Z as EOF. Binary mode turns off all special
856 -- treatment of end-of-line and end-of-file characters.
857 -- (See also 'hSetBinaryMode'.)
859 openBinaryFile :: FilePath -> IOMode -> IO Handle
860 openBinaryFile fp m =
862 (openFile' fp m True)
863 (\e -> ioError (addFilePathToIOError "openBinaryFile" fp e))
865 openFile' filepath mode binary =
866 withCString filepath $ \ f ->
869 oflags1 = case mode of
870 ReadMode -> read_flags
871 #ifdef mingw32_HOST_OS
872 WriteMode -> write_flags .|. o_TRUNC
874 WriteMode -> write_flags
876 ReadWriteMode -> rw_flags
877 AppendMode -> append_flags
883 oflags = oflags1 .|. binary_flags
886 -- the old implementation had a complicated series of three opens,
887 -- which is perhaps because we have to be careful not to open
888 -- directories. However, the man pages I've read say that open()
889 -- always returns EISDIR if the file is a directory and was opened
890 -- for writing, so I think we're ok with a single open() here...
891 fd <- throwErrnoIfMinus1Retry "openFile"
892 (c_open f (fromIntegral oflags) 0o666)
894 stat@(fd_type,_,_) <- fdStat fd
896 h <- fdToHandle_stat fd (Just stat) False filepath mode binary
897 `catchAny` \e -> do c_close fd; throw e
898 -- NB. don't forget to close the FD if fdToHandle' fails, otherwise
900 -- ASSERT: if we just created the file, then fdToHandle' won't fail
901 -- (so we don't need to worry about removing the newly created file
902 -- in the event of an error).
904 #ifndef mingw32_HOST_OS
905 -- we want to truncate() if this is an open in WriteMode, but only
906 -- if the target is a RegularFile. ftruncate() fails on special files
908 if mode == WriteMode && fd_type == RegularFile
909 then throwErrnoIf (/=0) "openFile"
916 std_flags = o_NONBLOCK .|. o_NOCTTY
917 output_flags = std_flags .|. o_CREAT
918 read_flags = std_flags .|. o_RDONLY
919 write_flags = output_flags .|. o_WRONLY
920 rw_flags = output_flags .|. o_RDWR
921 append_flags = write_flags .|. o_APPEND
923 -- ---------------------------------------------------------------------------
926 fdToHandle_stat :: FD
927 -> Maybe (FDType, CDev, CIno)
934 fdToHandle_stat fd mb_stat is_socket filepath mode binary = do
936 #ifdef mingw32_HOST_OS
937 -- On Windows, the is_socket flag indicates that the Handle is a socket
939 -- On Unix, the is_socket flag indicates that the FD can be made non-blocking
940 let non_blocking = is_socket
942 when non_blocking $ setNonBlockingFD fd
943 -- turn on non-blocking mode
946 let (ha_type, write) =
948 ReadMode -> ( ReadHandle, False )
949 WriteMode -> ( WriteHandle, True )
950 ReadWriteMode -> ( ReadWriteHandle, True )
951 AppendMode -> ( AppendHandle, True )
953 -- open() won't tell us if it was a directory if we only opened for
954 -- reading, so check again.
962 ioException (IOError Nothing InappropriateType "openFile"
963 "is a directory" Nothing)
965 -- regular files need to be locked
967 #ifndef mingw32_HOST_OS
968 -- On Windows we use explicit exclusion via sopen() to implement
969 -- this locking (see __hscore_open()); on Unix we have to
970 -- implment it in the RTS.
971 r <- lockFile fd dev ino (fromBool write)
973 ioException (IOError Nothing ResourceBusy "openFile"
974 "file is locked" Nothing)
976 mkFileHandle fd is_socket filepath ha_type binary
979 -- only *Streams* can be DuplexHandles. Other read/write
980 -- Handles must share a buffer.
981 | ReadWriteHandle <- ha_type ->
982 mkDuplexHandle fd is_socket filepath binary
984 mkFileHandle fd is_socket filepath ha_type binary
987 mkFileHandle fd is_socket filepath ha_type binary
989 -- | Old API kept to avoid breaking clients
990 fdToHandle' :: FD -> Maybe FDType -> Bool -> FilePath -> IOMode -> Bool
992 fdToHandle' fd mb_type is_socket filepath mode binary
994 let mb_stat = case mb_type of
996 -- fdToHandle_stat will do the stat:
997 Just RegularFile -> Nothing
998 -- no stat required for streams etc.:
999 Just other -> Just (other,0,0)
1000 fdToHandle_stat fd mb_stat is_socket filepath mode binary
1002 fdToHandle :: FD -> IO Handle
1004 mode <- fdGetMode fd
1005 let fd_str = "<file descriptor: " ++ show fd ++ ">"
1006 fdToHandle_stat fd Nothing False fd_str mode True{-bin mode-}
1007 -- NB. the is_socket flag is False, meaning that:
1008 -- on Unix the file descriptor will *not* be put in non-blocking mode
1009 -- on Windows we're guessing this is not a socket (XXX)
1011 #ifndef mingw32_HOST_OS
1012 foreign import ccall unsafe "lockFile"
1013 lockFile :: CInt -> CDev -> CIno -> CInt -> IO CInt
1015 foreign import ccall unsafe "unlockFile"
1016 unlockFile :: CInt -> IO CInt
1019 mkStdHandle :: FD -> FilePath -> HandleType -> IORef Buffer -> BufferMode
1021 mkStdHandle fd filepath ha_type buf bmode = do
1022 spares <- newIORef BufferListNil
1023 newFileHandle filepath (stdHandleFinalizer filepath)
1024 (Handle__ { haFD = fd,
1026 haIsBin = dEFAULT_OPEN_IN_BINARY_MODE,
1027 haIsStream = False, -- means FD is blocking on Unix
1028 haBufferMode = bmode,
1031 haOtherSide = Nothing
1034 mkFileHandle :: FD -> Bool -> FilePath -> HandleType -> Bool -> IO Handle
1035 mkFileHandle fd is_stream filepath ha_type binary = do
1036 (buf, bmode) <- getBuffer fd (initBufferState ha_type)
1038 #ifdef mingw32_HOST_OS
1039 -- On Windows, if this is a read/write handle and we are in text mode,
1040 -- turn off buffering. We don't correctly handle the case of switching
1041 -- from read mode to write mode on a buffered text-mode handle, see bug
1043 bmode <- case ha_type of
1044 ReadWriteHandle | not binary -> return NoBuffering
1045 _other -> return bmode
1048 spares <- newIORef BufferListNil
1049 newFileHandle filepath (handleFinalizer filepath)
1050 (Handle__ { haFD = fd,
1053 haIsStream = is_stream,
1054 haBufferMode = bmode,
1057 haOtherSide = Nothing
1060 mkDuplexHandle :: FD -> Bool -> FilePath -> Bool -> IO Handle
1061 mkDuplexHandle fd is_stream filepath binary = do
1062 (w_buf, w_bmode) <- getBuffer fd WriteBuffer
1063 w_spares <- newIORef BufferListNil
1065 Handle__ { haFD = fd,
1066 haType = WriteHandle,
1068 haIsStream = is_stream,
1069 haBufferMode = w_bmode,
1071 haBuffers = w_spares,
1072 haOtherSide = Nothing
1074 write_side <- newMVar w_handle_
1076 (r_buf, r_bmode) <- getBuffer fd ReadBuffer
1077 r_spares <- newIORef BufferListNil
1079 Handle__ { haFD = fd,
1080 haType = ReadHandle,
1082 haIsStream = is_stream,
1083 haBufferMode = r_bmode,
1085 haBuffers = r_spares,
1086 haOtherSide = Just write_side
1088 read_side <- newMVar r_handle_
1090 addMVarFinalizer write_side (handleFinalizer filepath write_side)
1091 return (DuplexHandle filepath read_side write_side)
1094 initBufferState ReadHandle = ReadBuffer
1095 initBufferState _ = WriteBuffer
1097 -- ---------------------------------------------------------------------------
1100 -- | Computation 'hClose' @hdl@ makes handle @hdl@ closed. Before the
1101 -- computation finishes, if @hdl@ is writable its buffer is flushed as
1103 -- Performing 'hClose' on a handle that has already been closed has no effect;
1104 -- doing so is not an error. All other operations on a closed handle will fail.
1105 -- If 'hClose' fails for any reason, any further operations (apart from
1106 -- 'hClose') on the handle will still fail as if @hdl@ had been successfully
1109 hClose :: Handle -> IO ()
1110 hClose h@(FileHandle _ m) = do
1111 mb_exc <- hClose' h m
1113 Nothing -> return ()
1115 hClose h@(DuplexHandle _ r w) = do
1116 mb_exc1 <- hClose' h w
1117 mb_exc2 <- hClose' h r
1118 case (do mb_exc1; mb_exc2) of
1119 Nothing -> return ()
1122 hClose' h m = withHandle' "hClose" h m $ hClose_help
1124 -- hClose_help is also called by lazyRead (in PrelIO) when EOF is read
1125 -- or an IO error occurs on a lazy stream. The semi-closed Handle is
1126 -- then closed immediately. We have to be careful with DuplexHandles
1127 -- though: we have to leave the closing to the finalizer in that case,
1128 -- because the write side may still be in use.
1129 hClose_help :: Handle__ -> IO (Handle__, Maybe SomeException)
1130 hClose_help handle_ =
1131 case haType handle_ of
1132 ClosedHandle -> return (handle_,Nothing)
1133 _ -> do flushWriteBufferOnly handle_ -- interruptible
1134 hClose_handle_ handle_
1136 hClose_handle_ :: Handle__ -> IO (Handle__, Maybe SomeException)
1137 hClose_handle_ handle_ = do
1138 let fd = haFD handle_
1140 -- close the file descriptor, but not when this is the read
1141 -- side of a duplex handle.
1142 -- If an exception is raised by the close(), we want to continue
1143 -- to close the handle and release the lock if it has one, then
1144 -- we return the exception to the caller of hClose_help which can
1145 -- raise it if necessary.
1147 case haOtherSide handle_ of
1149 throwErrnoIfMinus1Retry_ "hClose"
1150 #ifdef mingw32_HOST_OS
1151 (closeFd (haIsStream handle_) fd)
1157 `catchException` \e -> return (Just e)
1159 Just _ -> return Nothing
1161 -- free the spare buffers
1162 writeIORef (haBuffers handle_) BufferListNil
1163 writeIORef (haBuffer handle_) noBuffer
1165 #ifndef mingw32_HOST_OS
1170 -- we must set the fd to -1, because the finalizer is going
1171 -- to run eventually and try to close/unlock it.
1172 return (handle_{ haFD = -1,
1173 haType = ClosedHandle
1177 {-# NOINLINE noBuffer #-}
1178 noBuffer = unsafePerformIO $ allocateBuffer 1 ReadBuffer
1180 -----------------------------------------------------------------------------
1181 -- Detecting and changing the size of a file
1183 -- | For a handle @hdl@ which attached to a physical file,
1184 -- 'hFileSize' @hdl@ returns the size of that file in 8-bit bytes.
1186 hFileSize :: Handle -> IO Integer
1188 withHandle_ "hFileSize" handle $ \ handle_ -> do
1189 case haType handle_ of
1190 ClosedHandle -> ioe_closedHandle
1191 SemiClosedHandle -> ioe_closedHandle
1192 _ -> do flushWriteBufferOnly handle_
1193 r <- fdFileSize (haFD handle_)
1196 else ioException (IOError Nothing InappropriateType "hFileSize"
1197 "not a regular file" Nothing)
1200 -- | 'hSetFileSize' @hdl@ @size@ truncates the physical file with handle @hdl@ to @size@ bytes.
1202 hSetFileSize :: Handle -> Integer -> IO ()
1203 hSetFileSize handle size =
1204 withHandle_ "hSetFileSize" handle $ \ handle_ -> do
1205 case haType handle_ of
1206 ClosedHandle -> ioe_closedHandle
1207 SemiClosedHandle -> ioe_closedHandle
1208 _ -> do flushWriteBufferOnly handle_
1209 throwErrnoIf (/=0) "hSetFileSize"
1210 (c_ftruncate (haFD handle_) (fromIntegral size))
1213 -- ---------------------------------------------------------------------------
1214 -- Detecting the End of Input
1216 -- | For a readable handle @hdl@, 'hIsEOF' @hdl@ returns
1217 -- 'True' if no further input can be taken from @hdl@ or for a
1218 -- physical file, if the current I\/O position is equal to the length of
1219 -- the file. Otherwise, it returns 'False'.
1221 -- NOTE: 'hIsEOF' may block, because it is the same as calling
1222 -- 'hLookAhead' and checking for an EOF exception.
1224 hIsEOF :: Handle -> IO Bool
1227 (do hLookAhead handle; return False)
1228 (\e -> if isEOFError e then return True else ioError e)
1230 -- | The computation 'isEOF' is identical to 'hIsEOF',
1231 -- except that it works only on 'stdin'.
1234 isEOF = hIsEOF stdin
1236 -- ---------------------------------------------------------------------------
1239 -- | Computation 'hLookAhead' returns the next character from the handle
1240 -- without removing it from the input buffer, blocking until a character
1243 -- This operation may fail with:
1245 -- * 'isEOFError' if the end of file has been reached.
1247 hLookAhead :: Handle -> IO Char
1248 hLookAhead handle = do
1249 wantReadableHandle "hLookAhead" handle $ \handle_ -> do
1250 let ref = haBuffer handle_
1252 is_line = haBufferMode handle_ == LineBuffering
1253 buf <- readIORef ref
1255 -- fill up the read buffer if necessary
1256 new_buf <- if bufferEmpty buf
1257 then fillReadBuffer fd True (haIsStream handle_) buf
1260 writeIORef ref new_buf
1262 (c,_) <- readCharFromBuffer (bufBuf buf) (bufRPtr buf)
1265 -- ---------------------------------------------------------------------------
1266 -- Buffering Operations
1268 -- Three kinds of buffering are supported: line-buffering,
1269 -- block-buffering or no-buffering. See GHC.IOBase for definition and
1270 -- further explanation of what the type represent.
1272 -- | Computation 'hSetBuffering' @hdl mode@ sets the mode of buffering for
1273 -- handle @hdl@ on subsequent reads and writes.
1275 -- If the buffer mode is changed from 'BlockBuffering' or
1276 -- 'LineBuffering' to 'NoBuffering', then
1278 -- * if @hdl@ is writable, the buffer is flushed as for 'hFlush';
1280 -- * if @hdl@ is not writable, the contents of the buffer is discarded.
1282 -- This operation may fail with:
1284 -- * 'isPermissionError' if the handle has already been used for reading
1285 -- or writing and the implementation does not allow the buffering mode
1288 hSetBuffering :: Handle -> BufferMode -> IO ()
1289 hSetBuffering handle mode =
1290 withAllHandles__ "hSetBuffering" handle $ \ handle_ -> do
1291 case haType handle_ of
1292 ClosedHandle -> ioe_closedHandle
1295 - we flush the old buffer regardless of whether
1296 the new buffer could fit the contents of the old buffer
1298 - allow a handle's buffering to change even if IO has
1299 occurred (ANSI C spec. does not allow this, nor did
1300 the previous implementation of IO.hSetBuffering).
1301 - a non-standard extension is to allow the buffering
1302 of semi-closed handles to change [sof 6/98]
1306 let state = initBufferState (haType handle_)
1309 -- we always have a 1-character read buffer for
1310 -- unbuffered handles: it's needed to
1311 -- support hLookAhead.
1312 NoBuffering -> allocateBuffer 1 ReadBuffer
1313 LineBuffering -> allocateBuffer dEFAULT_BUFFER_SIZE state
1314 BlockBuffering Nothing -> allocateBuffer dEFAULT_BUFFER_SIZE state
1315 BlockBuffering (Just n) | n <= 0 -> ioe_bufsiz n
1316 | otherwise -> allocateBuffer n state
1317 writeIORef (haBuffer handle_) new_buf
1319 -- for input terminals we need to put the terminal into
1320 -- cooked or raw mode depending on the type of buffering.
1321 is_tty <- fdIsTTY (haFD handle_)
1322 when (is_tty && isReadableHandleType (haType handle_)) $
1324 #ifndef mingw32_HOST_OS
1325 -- 'raw' mode under win32 is a bit too specialised (and troublesome
1326 -- for most common uses), so simply disable its use here.
1327 NoBuffering -> setCooked (haFD handle_) False
1329 NoBuffering -> return ()
1331 _ -> setCooked (haFD handle_) True
1333 -- throw away spare buffers, they might be the wrong size
1334 writeIORef (haBuffers handle_) BufferListNil
1336 return (handle_{ haBufferMode = mode })
1338 -- -----------------------------------------------------------------------------
1341 -- | The action 'hFlush' @hdl@ causes any items buffered for output
1342 -- in handle @hdl@ to be sent immediately to the operating system.
1344 -- This operation may fail with:
1346 -- * 'isFullError' if the device is full;
1348 -- * 'isPermissionError' if a system resource limit would be exceeded.
1349 -- It is unspecified whether the characters in the buffer are discarded
1350 -- or retained under these circumstances.
1352 hFlush :: Handle -> IO ()
1354 wantWritableHandle "hFlush" handle $ \ handle_ -> do
1355 buf <- readIORef (haBuffer handle_)
1356 if bufferIsWritable buf && not (bufferEmpty buf)
1357 then do flushed_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
1358 writeIORef (haBuffer handle_) flushed_buf
1362 -- -----------------------------------------------------------------------------
1363 -- Repositioning Handles
1365 data HandlePosn = HandlePosn Handle HandlePosition
1367 instance Eq HandlePosn where
1368 (HandlePosn h1 p1) == (HandlePosn h2 p2) = p1==p2 && h1==h2
1370 instance Show HandlePosn where
1371 showsPrec p (HandlePosn h pos) =
1372 showsPrec p h . showString " at position " . shows pos
1374 -- HandlePosition is the Haskell equivalent of POSIX' off_t.
1375 -- We represent it as an Integer on the Haskell side, but
1376 -- cheat slightly in that hGetPosn calls upon a C helper
1377 -- that reports the position back via (merely) an Int.
1378 type HandlePosition = Integer
1380 -- | Computation 'hGetPosn' @hdl@ returns the current I\/O position of
1381 -- @hdl@ as a value of the abstract type 'HandlePosn'.
1383 hGetPosn :: Handle -> IO HandlePosn
1384 hGetPosn handle = do
1385 posn <- hTell handle
1386 return (HandlePosn handle posn)
1388 -- | If a call to 'hGetPosn' @hdl@ returns a position @p@,
1389 -- then computation 'hSetPosn' @p@ sets the position of @hdl@
1390 -- to the position it held at the time of the call to 'hGetPosn'.
1392 -- This operation may fail with:
1394 -- * 'isPermissionError' if a system resource limit would be exceeded.
1396 hSetPosn :: HandlePosn -> IO ()
1397 hSetPosn (HandlePosn h i) = hSeek h AbsoluteSeek i
1399 -- ---------------------------------------------------------------------------
1402 -- | A mode that determines the effect of 'hSeek' @hdl mode i@, as follows:
1404 = AbsoluteSeek -- ^ the position of @hdl@ is set to @i@.
1405 | RelativeSeek -- ^ the position of @hdl@ is set to offset @i@
1406 -- from the current position.
1407 | SeekFromEnd -- ^ the position of @hdl@ is set to offset @i@
1408 -- from the end of the file.
1409 deriving (Eq, Ord, Ix, Enum, Read, Show)
1412 - when seeking using `SeekFromEnd', positive offsets (>=0) means
1413 seeking at or past EOF.
1415 - we possibly deviate from the report on the issue of seeking within
1416 the buffer and whether to flush it or not. The report isn't exactly
1420 -- | Computation 'hSeek' @hdl mode i@ sets the position of handle
1421 -- @hdl@ depending on @mode@.
1422 -- The offset @i@ is given in terms of 8-bit bytes.
1424 -- If @hdl@ is block- or line-buffered, then seeking to a position which is not
1425 -- in the current buffer will first cause any items in the output buffer to be
1426 -- written to the device, and then cause the input buffer to be discarded.
1427 -- Some handles may not be seekable (see 'hIsSeekable'), or only support a
1428 -- subset of the possible positioning operations (for instance, it may only
1429 -- be possible to seek to the end of a tape, or to a positive offset from
1430 -- the beginning or current position).
1431 -- It is not possible to set a negative I\/O position, or for
1432 -- a physical file, an I\/O position beyond the current end-of-file.
1434 -- This operation may fail with:
1436 -- * 'isPermissionError' if a system resource limit would be exceeded.
1438 hSeek :: Handle -> SeekMode -> Integer -> IO ()
1439 hSeek handle mode offset =
1440 wantSeekableHandle "hSeek" handle $ \ handle_ -> do
1442 puts ("hSeek " ++ show (mode,offset) ++ "\n")
1444 let ref = haBuffer handle_
1445 buf <- readIORef ref
1451 throwErrnoIfMinus1Retry_ "hSeek"
1452 (c_lseek (haFD handle_) (fromIntegral offset) whence)
1455 whence = case mode of
1456 AbsoluteSeek -> sEEK_SET
1457 RelativeSeek -> sEEK_CUR
1458 SeekFromEnd -> sEEK_END
1460 if bufferIsWritable buf
1461 then do new_buf <- flushWriteBuffer fd (haIsStream handle_) buf
1462 writeIORef ref new_buf
1466 if mode == RelativeSeek && offset >= 0 && offset < fromIntegral (w - r)
1467 then writeIORef ref buf{ bufRPtr = r + fromIntegral offset }
1470 new_buf <- flushReadBuffer (haFD handle_) buf
1471 writeIORef ref new_buf
1475 hTell :: Handle -> IO Integer
1477 wantSeekableHandle "hGetPosn" handle $ \ handle_ -> do
1479 #if defined(mingw32_HOST_OS)
1480 -- urgh, on Windows we have to worry about \n -> \r\n translation,
1481 -- so we can't easily calculate the file position using the
1482 -- current buffer size. Just flush instead.
1485 let fd = haFD handle_
1486 posn <- fromIntegral `liftM`
1487 throwErrnoIfMinus1Retry "hGetPosn"
1488 (c_lseek fd 0 sEEK_CUR)
1490 let ref = haBuffer handle_
1491 buf <- readIORef ref
1494 | bufferIsWritable buf = posn + fromIntegral (bufWPtr buf)
1495 | otherwise = posn - fromIntegral (bufWPtr buf - bufRPtr buf)
1497 puts ("\nhGetPosn: (fd, posn, real_posn) = " ++ show (fd, posn, real_posn) ++ "\n")
1498 puts (" (bufWPtr, bufRPtr) = " ++ show (bufWPtr buf, bufRPtr buf) ++ "\n")
1502 -- -----------------------------------------------------------------------------
1503 -- Handle Properties
1505 -- A number of operations return information about the properties of a
1506 -- handle. Each of these operations returns `True' if the handle has
1507 -- the specified property, and `False' otherwise.
1509 hIsOpen :: Handle -> IO Bool
1511 withHandle_ "hIsOpen" handle $ \ handle_ -> do
1512 case haType handle_ of
1513 ClosedHandle -> return False
1514 SemiClosedHandle -> return False
1517 hIsClosed :: Handle -> IO Bool
1519 withHandle_ "hIsClosed" handle $ \ handle_ -> do
1520 case haType handle_ of
1521 ClosedHandle -> return True
1524 {- not defined, nor exported, but mentioned
1525 here for documentation purposes:
1527 hSemiClosed :: Handle -> IO Bool
1531 return (not (ho || hc))
1534 hIsReadable :: Handle -> IO Bool
1535 hIsReadable (DuplexHandle _ _ _) = return True
1536 hIsReadable handle =
1537 withHandle_ "hIsReadable" handle $ \ handle_ -> do
1538 case haType handle_ of
1539 ClosedHandle -> ioe_closedHandle
1540 SemiClosedHandle -> ioe_closedHandle
1541 htype -> return (isReadableHandleType htype)
1543 hIsWritable :: Handle -> IO Bool
1544 hIsWritable (DuplexHandle _ _ _) = return True
1545 hIsWritable handle =
1546 withHandle_ "hIsWritable" handle $ \ handle_ -> do
1547 case haType handle_ of
1548 ClosedHandle -> ioe_closedHandle
1549 SemiClosedHandle -> ioe_closedHandle
1550 htype -> return (isWritableHandleType htype)
1552 -- | Computation 'hGetBuffering' @hdl@ returns the current buffering mode
1555 hGetBuffering :: Handle -> IO BufferMode
1556 hGetBuffering handle =
1557 withHandle_ "hGetBuffering" handle $ \ handle_ -> do
1558 case haType handle_ of
1559 ClosedHandle -> ioe_closedHandle
1561 -- We're being non-standard here, and allow the buffering
1562 -- of a semi-closed handle to be queried. -- sof 6/98
1563 return (haBufferMode handle_) -- could be stricter..
1565 hIsSeekable :: Handle -> IO Bool
1566 hIsSeekable handle =
1567 withHandle_ "hIsSeekable" handle $ \ handle_ -> do
1568 case haType handle_ of
1569 ClosedHandle -> ioe_closedHandle
1570 SemiClosedHandle -> ioe_closedHandle
1571 AppendHandle -> return False
1572 _ -> do t <- fdType (haFD handle_)
1573 return ((t == RegularFile || t == RawDevice)
1574 && (haIsBin handle_ || tEXT_MODE_SEEK_ALLOWED))
1576 -- -----------------------------------------------------------------------------
1577 -- Changing echo status (Non-standard GHC extensions)
1579 -- | Set the echoing status of a handle connected to a terminal.
1581 hSetEcho :: Handle -> Bool -> IO ()
1582 hSetEcho handle on = do
1583 isT <- hIsTerminalDevice handle
1587 withHandle_ "hSetEcho" handle $ \ handle_ -> do
1588 case haType handle_ of
1589 ClosedHandle -> ioe_closedHandle
1590 _ -> setEcho (haFD handle_) on
1592 -- | Get the echoing status of a handle connected to a terminal.
1594 hGetEcho :: Handle -> IO Bool
1595 hGetEcho handle = do
1596 isT <- hIsTerminalDevice handle
1600 withHandle_ "hGetEcho" handle $ \ handle_ -> do
1601 case haType handle_ of
1602 ClosedHandle -> ioe_closedHandle
1603 _ -> getEcho (haFD handle_)
1605 -- | Is the handle connected to a terminal?
1607 hIsTerminalDevice :: Handle -> IO Bool
1608 hIsTerminalDevice handle = do
1609 withHandle_ "hIsTerminalDevice" handle $ \ handle_ -> do
1610 case haType handle_ of
1611 ClosedHandle -> ioe_closedHandle
1612 _ -> fdIsTTY (haFD handle_)
1614 -- -----------------------------------------------------------------------------
1617 -- | Select binary mode ('True') or text mode ('False') on a open handle.
1618 -- (See also 'openBinaryFile'.)
1620 hSetBinaryMode :: Handle -> Bool -> IO ()
1621 hSetBinaryMode handle bin =
1622 withAllHandles__ "hSetBinaryMode" handle $ \ handle_ ->
1623 do throwErrnoIfMinus1_ "hSetBinaryMode"
1624 (setmode (haFD handle_) bin)
1625 return handle_{haIsBin=bin}
1627 foreign import ccall unsafe "__hscore_setmode"
1628 setmode :: CInt -> Bool -> IO CInt
1630 -- -----------------------------------------------------------------------------
1631 -- Duplicating a Handle
1633 -- | Returns a duplicate of the original handle, with its own buffer.
1634 -- The two Handles will share a file pointer, however. The original
1635 -- handle's buffer is flushed, including discarding any input data,
1636 -- before the handle is duplicated.
1638 hDuplicate :: Handle -> IO Handle
1639 hDuplicate h@(FileHandle path m) = do
1640 new_h_ <- withHandle' "hDuplicate" h m (dupHandle h Nothing)
1641 newFileHandle path (handleFinalizer path) new_h_
1642 hDuplicate h@(DuplexHandle path r w) = do
1643 new_w_ <- withHandle' "hDuplicate" h w (dupHandle h Nothing)
1644 new_w <- newMVar new_w_
1645 new_r_ <- withHandle' "hDuplicate" h r (dupHandle h (Just new_w))
1646 new_r <- newMVar new_r_
1647 addMVarFinalizer new_w (handleFinalizer path new_w)
1648 return (DuplexHandle path new_r new_w)
1650 dupHandle :: Handle -> Maybe (MVar Handle__) -> Handle__
1651 -> IO (Handle__, Handle__)
1652 dupHandle h other_side h_ = do
1653 -- flush the buffer first, so we don't have to copy its contents
1655 new_fd <- case other_side of
1656 Nothing -> throwErrnoIfMinus1 "dupHandle" $ c_dup (haFD h_)
1657 Just r -> withHandle_' "dupHandle" h r (return . haFD)
1658 dupHandle_ other_side h_ new_fd
1660 dupHandleTo other_side hto_ h_ = do
1662 -- Windows' dup2 does not return the new descriptor, unlike Unix
1663 throwErrnoIfMinus1 "dupHandleTo" $
1664 c_dup2 (haFD h_) (haFD hto_)
1665 dupHandle_ other_side h_ (haFD hto_)
1667 dupHandle_ :: Maybe (MVar Handle__) -> Handle__ -> FD
1668 -> IO (Handle__, Handle__)
1669 dupHandle_ other_side h_ new_fd = do
1670 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE (initBufferState (haType h_))
1671 ioref <- newIORef buffer
1672 ioref_buffers <- newIORef BufferListNil
1674 let new_handle_ = h_{ haFD = new_fd,
1676 haBuffers = ioref_buffers,
1677 haOtherSide = other_side }
1678 return (h_, new_handle_)
1680 -- -----------------------------------------------------------------------------
1681 -- Replacing a Handle
1684 Makes the second handle a duplicate of the first handle. The second
1685 handle will be closed first, if it is not already.
1687 This can be used to retarget the standard Handles, for example:
1689 > do h <- openFile "mystdout" WriteMode
1690 > hDuplicateTo h stdout
1693 hDuplicateTo :: Handle -> Handle -> IO ()
1694 hDuplicateTo h1@(FileHandle _ m1) h2@(FileHandle _ m2) = do
1695 withHandle__' "hDuplicateTo" h2 m2 $ \h2_ -> do
1696 _ <- hClose_help h2_
1697 withHandle' "hDuplicateTo" h1 m1 (dupHandleTo Nothing h2_)
1698 hDuplicateTo h1@(DuplexHandle _ r1 w1) h2@(DuplexHandle _ r2 w2) = do
1699 withHandle__' "hDuplicateTo" h2 w2 $ \w2_ -> do
1700 _ <- hClose_help w2_
1701 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo Nothing w2_)
1702 withHandle__' "hDuplicateTo" h2 r2 $ \r2_ -> do
1703 _ <- hClose_help r2_
1704 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo (Just w1) r2_)
1706 ioException (IOError (Just h1) IllegalOperation "hDuplicateTo"
1707 "handles are incompatible" Nothing)
1709 -- ---------------------------------------------------------------------------
1712 -- | 'hShow' is in the 'IO' monad, and gives more comprehensive output
1713 -- than the (pure) instance of 'Show' for 'Handle'.
1715 hShow :: Handle -> IO String
1716 hShow h@(FileHandle path _) = showHandle' path False h
1717 hShow h@(DuplexHandle path _ _) = showHandle' path True h
1719 showHandle' filepath is_duplex h =
1720 withHandle_ "showHandle" h $ \hdl_ ->
1722 showType | is_duplex = showString "duplex (read-write)"
1723 | otherwise = shows (haType hdl_)
1727 showHdl (haType hdl_)
1728 (showString "loc=" . showString filepath . showChar ',' .
1729 showString "type=" . showType . showChar ',' .
1730 showString "binary=" . shows (haIsBin hdl_) . showChar ',' .
1731 showString "buffering=" . showBufMode (unsafePerformIO (readIORef (haBuffer hdl_))) (haBufferMode hdl_) . showString "}" )
1735 showHdl :: HandleType -> ShowS -> ShowS
1738 ClosedHandle -> shows ht . showString "}"
1741 showBufMode :: Buffer -> BufferMode -> ShowS
1742 showBufMode buf bmo =
1744 NoBuffering -> showString "none"
1745 LineBuffering -> showString "line"
1746 BlockBuffering (Just n) -> showString "block " . showParen True (shows n)
1747 BlockBuffering Nothing -> showString "block " . showParen True (shows def)
1752 -- ---------------------------------------------------------------------------
1755 #if defined(DEBUG_DUMP)
1756 puts :: String -> IO ()
1757 puts s = do write_rawBuffer 1 (unsafeCoerce# (packCString# s)) 0 (fromIntegral (length s))
1761 -- -----------------------------------------------------------------------------
1764 throwErrnoIfMinus1RetryOnBlock :: String -> IO CInt -> IO CInt -> IO CInt
1765 throwErrnoIfMinus1RetryOnBlock loc f on_block =
1768 if (res :: CInt) == -1
1772 then throwErrnoIfMinus1RetryOnBlock loc f on_block
1773 else if err == eWOULDBLOCK || err == eAGAIN
1778 -- -----------------------------------------------------------------------------
1779 -- wrappers to platform-specific constants:
1781 foreign import ccall unsafe "__hscore_supportsTextMode"
1782 tEXT_MODE_SEEK_ALLOWED :: Bool
1784 foreign import ccall unsafe "__hscore_bufsiz" dEFAULT_BUFFER_SIZE :: Int
1785 foreign import ccall unsafe "__hscore_seek_cur" sEEK_CUR :: CInt
1786 foreign import ccall unsafe "__hscore_seek_set" sEEK_SET :: CInt
1787 foreign import ccall unsafe "__hscore_seek_end" sEEK_END :: CInt