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, 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 :: Bool
100 dEFAULT_OPEN_IN_BINARY_MODE = False
102 -- ---------------------------------------------------------------------------
103 -- Creating a new handle
105 newFileHandle :: FilePath -> (MVar Handle__ -> IO ()) -> Handle__ -> IO Handle
106 newFileHandle filepath finalizer hc = do
108 addMVarFinalizer m (finalizer m)
109 return (FileHandle filepath m)
111 -- ---------------------------------------------------------------------------
112 -- Working with Handles
115 In the concurrent world, handles are locked during use. This is done
116 by wrapping an MVar around the handle which acts as a mutex over
117 operations on the handle.
119 To avoid races, we use the following bracketing operations. The idea
120 is to obtain the lock, do some operation and replace the lock again,
121 whether the operation succeeded or failed. We also want to handle the
122 case where the thread receives an exception while processing the IO
123 operation: in these cases we also want to relinquish the lock.
125 There are three versions of @withHandle@: corresponding to the three
126 possible combinations of:
128 - the operation may side-effect the handle
129 - the operation may return a result
131 If the operation generates an error or an exception is raised, the
132 original handle is always replaced [ this is the case at the moment,
133 but we might want to revisit this in the future --SDM ].
136 {-# INLINE withHandle #-}
137 withHandle :: String -> Handle -> (Handle__ -> IO (Handle__,a)) -> IO a
138 withHandle fun h@(FileHandle _ m) act = withHandle' fun h m act
139 withHandle fun h@(DuplexHandle _ m _) act = withHandle' fun h m act
141 withHandle' :: String -> Handle -> MVar Handle__
142 -> (Handle__ -> IO (Handle__,a)) -> IO a
143 withHandle' fun h m act =
146 checkBufferInvariants h_
147 (h',v) <- (act h_ `catchAny` \err -> putMVar m h_ >> throw err)
148 `catchException` \ex -> ioError (augmentIOError ex fun h)
149 checkBufferInvariants h'
153 {-# INLINE withHandle_ #-}
154 withHandle_ :: String -> Handle -> (Handle__ -> IO a) -> IO a
155 withHandle_ fun h@(FileHandle _ m) act = withHandle_' fun h m act
156 withHandle_ fun h@(DuplexHandle _ m _) act = withHandle_' fun h m act
158 withHandle_' :: String -> Handle -> MVar Handle__ -> (Handle__ -> IO a) -> IO a
159 withHandle_' fun h m act =
162 checkBufferInvariants h_
163 v <- (act h_ `catchAny` \err -> putMVar m h_ >> throw err)
164 `catchException` \ex -> ioError (augmentIOError ex fun h)
165 checkBufferInvariants h_
169 withAllHandles__ :: String -> Handle -> (Handle__ -> IO Handle__) -> IO ()
170 withAllHandles__ fun h@(FileHandle _ m) act = withHandle__' fun h m act
171 withAllHandles__ fun h@(DuplexHandle _ r w) act = do
172 withHandle__' fun h r act
173 withHandle__' fun h w act
175 withHandle__' :: String -> Handle -> MVar Handle__ -> (Handle__ -> IO Handle__)
177 withHandle__' fun h m act =
180 checkBufferInvariants h_
181 h' <- (act h_ `catchAny` \err -> putMVar m h_ >> throw err)
182 `catchException` \ex -> ioError (augmentIOError ex fun h)
183 checkBufferInvariants h'
187 augmentIOError :: IOException -> String -> Handle -> IOException
188 augmentIOError (IOError _ iot _ str fp) fun h
189 = IOError (Just h) iot fun str filepath
192 | otherwise = case h of
193 FileHandle path _ -> Just path
194 DuplexHandle path _ _ -> Just path
196 -- ---------------------------------------------------------------------------
197 -- Wrapper for write operations.
199 wantWritableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
200 wantWritableHandle fun h@(FileHandle _ m) act
201 = wantWritableHandle' fun h m act
202 wantWritableHandle fun h@(DuplexHandle _ _ m) act
203 = wantWritableHandle' fun h m act
204 -- ToDo: in the Duplex case, we don't need to checkWritableHandle
207 :: String -> Handle -> MVar Handle__
208 -> (Handle__ -> IO a) -> IO a
209 wantWritableHandle' fun h m act
210 = withHandle_' fun h m (checkWritableHandle act)
212 checkWritableHandle :: (Handle__ -> IO a) -> Handle__ -> IO a
213 checkWritableHandle act handle_
214 = case haType handle_ of
215 ClosedHandle -> ioe_closedHandle
216 SemiClosedHandle -> ioe_closedHandle
217 ReadHandle -> ioe_notWritable
218 ReadWriteHandle -> do
219 let ref = haBuffer handle_
222 if not (bufferIsWritable buf)
223 then do b <- flushReadBuffer (haFD handle_) buf
224 return b{ bufState=WriteBuffer }
226 writeIORef ref new_buf
228 _other -> act handle_
230 -- ---------------------------------------------------------------------------
231 -- Wrapper for read operations.
233 wantReadableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
234 wantReadableHandle fun h@(FileHandle _ m) act
235 = wantReadableHandle' fun h m act
236 wantReadableHandle fun h@(DuplexHandle _ m _) act
237 = wantReadableHandle' fun h m act
238 -- ToDo: in the Duplex case, we don't need to checkReadableHandle
241 :: String -> Handle -> MVar Handle__
242 -> (Handle__ -> IO a) -> IO a
243 wantReadableHandle' fun h m act
244 = withHandle_' fun h m (checkReadableHandle act)
246 checkReadableHandle :: (Handle__ -> IO a) -> Handle__ -> IO a
247 checkReadableHandle act handle_ =
248 case haType handle_ of
249 ClosedHandle -> ioe_closedHandle
250 SemiClosedHandle -> ioe_closedHandle
251 AppendHandle -> ioe_notReadable
252 WriteHandle -> ioe_notReadable
253 ReadWriteHandle -> do
254 let ref = haBuffer handle_
256 when (bufferIsWritable buf) $ do
257 new_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
258 writeIORef ref new_buf{ bufState=ReadBuffer }
260 _other -> act handle_
262 -- ---------------------------------------------------------------------------
263 -- Wrapper for seek operations.
265 wantSeekableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
266 wantSeekableHandle fun h@(DuplexHandle _ _ _) _act =
267 ioException (IOError (Just h) IllegalOperation fun
268 "handle is not seekable" Nothing)
269 wantSeekableHandle fun h@(FileHandle _ m) act =
270 withHandle_' fun h m (checkSeekableHandle act)
272 checkSeekableHandle :: (Handle__ -> IO a) -> Handle__ -> IO a
273 checkSeekableHandle act handle_ =
274 case haType handle_ of
275 ClosedHandle -> ioe_closedHandle
276 SemiClosedHandle -> ioe_closedHandle
277 AppendHandle -> ioe_notSeekable
278 _ | haIsBin handle_ || tEXT_MODE_SEEK_ALLOWED -> act handle_
279 | otherwise -> ioe_notSeekable_notBin
281 -- -----------------------------------------------------------------------------
284 ioe_closedHandle, ioe_EOF,
285 ioe_notReadable, ioe_notWritable,
286 ioe_notSeekable, ioe_notSeekable_notBin :: IO a
288 ioe_closedHandle = ioException
289 (IOError Nothing IllegalOperation ""
290 "handle is closed" Nothing)
291 ioe_EOF = ioException
292 (IOError Nothing EOF "" "" Nothing)
293 ioe_notReadable = ioException
294 (IOError Nothing IllegalOperation ""
295 "handle is not open for reading" Nothing)
296 ioe_notWritable = ioException
297 (IOError Nothing IllegalOperation ""
298 "handle is not open for writing" Nothing)
299 ioe_notSeekable = ioException
300 (IOError Nothing IllegalOperation ""
301 "handle is not seekable" Nothing)
302 ioe_notSeekable_notBin = ioException
303 (IOError Nothing IllegalOperation ""
304 "seek operations on text-mode handles are not allowed on this platform"
307 ioe_finalizedHandle :: FilePath -> Handle__
308 ioe_finalizedHandle fp = throw
309 (IOError Nothing IllegalOperation ""
310 "handle is finalized" (Just fp))
312 ioe_bufsiz :: Int -> IO a
313 ioe_bufsiz n = ioException
314 (IOError Nothing InvalidArgument "hSetBuffering"
315 ("illegal buffer size " ++ showsPrec 9 n []) Nothing)
316 -- 9 => should be parens'ified.
318 -- -----------------------------------------------------------------------------
321 -- For a duplex handle, we arrange that the read side points to the write side
322 -- (and hence keeps it alive if the read side is alive). This is done by
323 -- having the haOtherSide field of the read side point to the read side.
324 -- The finalizer is then placed on the write side, and the handle only gets
325 -- finalized once, when both sides are no longer required.
327 -- NOTE about finalized handles: It's possible that a handle can be
328 -- finalized and then we try to use it later, for example if the
329 -- handle is referenced from another finalizer, or from a thread that
330 -- has become unreferenced and then resurrected (arguably in the
331 -- latter case we shouldn't finalize the Handle...). Anyway,
332 -- we try to emit a helpful message which is better than nothing.
334 stdHandleFinalizer :: FilePath -> MVar Handle__ -> IO ()
335 stdHandleFinalizer fp m = do
337 flushWriteBufferOnly h_
338 putMVar m (ioe_finalizedHandle fp)
340 handleFinalizer :: FilePath -> MVar Handle__ -> IO ()
341 handleFinalizer fp m = do
342 handle_ <- takeMVar m
343 case haType handle_ of
344 ClosedHandle -> return ()
345 _ -> do flushWriteBufferOnly handle_ `catchAny` \_ -> return ()
346 -- ignore errors and async exceptions, and close the
347 -- descriptor anyway...
348 hClose_handle_ handle_
350 putMVar m (ioe_finalizedHandle fp)
352 -- ---------------------------------------------------------------------------
353 -- Grimy buffer operations
355 checkBufferInvariants :: Handle__ -> IO ()
357 checkBufferInvariants h_ = do
358 let ref = haBuffer h_
359 Buffer{ bufWPtr=w, bufRPtr=r, bufSize=size, bufState=state } <- readIORef ref
364 && ( r /= w || (r == 0 && w == 0) )
365 && ( state /= WriteBuffer || r == 0 )
366 && ( state /= WriteBuffer || w < size ) -- write buffer is never full
368 then error "buffer invariant violation"
371 checkBufferInvariants _ = return ()
374 newEmptyBuffer :: RawBuffer -> BufferState -> Int -> Buffer
375 newEmptyBuffer b state size
376 = Buffer{ bufBuf=b, bufRPtr=0, bufWPtr=0, bufSize=size, bufState=state }
378 allocateBuffer :: Int -> BufferState -> IO Buffer
379 allocateBuffer sz@(I# size) state = IO $ \s ->
380 -- We sometimes need to pass the address of this buffer to
381 -- a "safe" foreign call, hence it must be immovable.
382 case newPinnedByteArray# size s of { (# s', b #) ->
383 (# s', newEmptyBuffer b state sz #) }
385 writeCharIntoBuffer :: RawBuffer -> Int -> Char -> IO Int
386 writeCharIntoBuffer slab (I# off) (C# c)
387 = IO $ \s -> case writeCharArray# slab off c s of
388 s' -> (# s', I# (off +# 1#) #)
390 readCharFromBuffer :: RawBuffer -> Int -> IO (Char, Int)
391 readCharFromBuffer slab (I# off)
392 = IO $ \s -> case readCharArray# slab off s of
393 (# s', c #) -> (# s', (C# c, I# (off +# 1#)) #)
395 getBuffer :: FD -> BufferState -> IO (IORef Buffer, BufferMode)
396 getBuffer fd state = do
397 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE state
398 ioref <- newIORef buffer
402 | is_tty = LineBuffering
403 | otherwise = BlockBuffering Nothing
405 return (ioref, buffer_mode)
407 mkUnBuffer :: IO (IORef Buffer)
409 buffer <- allocateBuffer 1 ReadBuffer
412 -- flushWriteBufferOnly flushes the buffer iff it contains pending write data.
413 flushWriteBufferOnly :: Handle__ -> IO ()
414 flushWriteBufferOnly h_ = do
418 new_buf <- if bufferIsWritable buf
419 then flushWriteBuffer fd (haIsStream h_) buf
421 writeIORef ref new_buf
423 -- flushBuffer syncs the file with the buffer, including moving the
424 -- file pointer backwards in the case of a read buffer.
425 flushBuffer :: Handle__ -> IO ()
427 let ref = haBuffer h_
432 ReadBuffer -> flushReadBuffer (haFD h_) buf
433 WriteBuffer -> flushWriteBuffer (haFD h_) (haIsStream h_) buf
435 writeIORef ref flushed_buf
437 -- When flushing a read buffer, we seek backwards by the number of
438 -- characters in the buffer. The file descriptor must therefore be
439 -- seekable: attempting to flush the read buffer on an unseekable
440 -- handle is not allowed.
442 flushReadBuffer :: FD -> Buffer -> IO Buffer
443 flushReadBuffer fd buf
444 | bufferEmpty buf = return buf
446 let off = negate (bufWPtr buf - bufRPtr buf)
448 puts ("flushReadBuffer: new file offset = " ++ show off ++ "\n")
450 throwErrnoIfMinus1Retry "flushReadBuffer"
451 (c_lseek fd (fromIntegral off) sEEK_CUR)
452 return buf{ bufWPtr=0, bufRPtr=0 }
454 flushWriteBuffer :: FD -> Bool -> Buffer -> IO Buffer
455 flushWriteBuffer fd is_stream buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w } =
456 seq fd $ do -- strictness hack
459 puts ("flushWriteBuffer, fd=" ++ show fd ++ ", bytes=" ++ show bytes ++ "\n")
462 then return (buf{ bufRPtr=0, bufWPtr=0 })
464 res <- writeRawBuffer "flushWriteBuffer" fd is_stream b
465 (fromIntegral r) (fromIntegral bytes)
466 let res' = fromIntegral res
468 then flushWriteBuffer fd is_stream (buf{ bufRPtr = r + res' })
469 else return buf{ bufRPtr=0, bufWPtr=0 }
471 fillReadBuffer :: FD -> Bool -> Bool -> Buffer -> IO Buffer
472 fillReadBuffer fd is_line is_stream
473 buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w, bufSize=size } =
474 -- buffer better be empty:
475 assert (r == 0 && w == 0) $ do
476 fillReadBufferLoop fd is_line is_stream buf b w size
478 -- For a line buffer, we just get the first chunk of data to arrive,
479 -- and don't wait for the whole buffer to be full (but we *do* wait
480 -- until some data arrives). This isn't really line buffering, but it
481 -- appears to be what GHC has done for a long time, and I suspect it
482 -- is more useful than line buffering in most cases.
484 fillReadBufferLoop :: FD -> Bool -> Bool -> Buffer -> RawBuffer -> Int -> Int
486 fillReadBufferLoop fd is_line is_stream buf b w size = do
488 if bytes == 0 -- buffer full?
489 then return buf{ bufRPtr=0, bufWPtr=w }
492 puts ("fillReadBufferLoop: bytes = " ++ show bytes ++ "\n")
494 res <- readRawBuffer "fillReadBuffer" fd is_stream b
495 (fromIntegral w) (fromIntegral bytes)
496 let res' = fromIntegral res
498 puts ("fillReadBufferLoop: res' = " ++ show res' ++ "\n")
503 else return buf{ bufRPtr=0, bufWPtr=w }
504 else if res' < bytes && not is_line
505 then fillReadBufferLoop fd is_line is_stream buf b (w+res') size
506 else return buf{ bufRPtr=0, bufWPtr=w+res' }
509 fillReadBufferWithoutBlocking :: FD -> Bool -> Buffer -> IO Buffer
510 fillReadBufferWithoutBlocking fd is_stream
511 buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w, bufSize=size } =
512 -- buffer better be empty:
513 assert (r == 0 && w == 0) $ do
515 puts ("fillReadBufferLoopNoBlock: bytes = " ++ show size ++ "\n")
517 res <- readRawBufferNoBlock "fillReadBuffer" fd is_stream b
518 0 (fromIntegral size)
519 let res' = fromIntegral res
521 puts ("fillReadBufferLoopNoBlock: res' = " ++ show res' ++ "\n")
523 return buf{ bufRPtr=0, bufWPtr=res' }
525 -- Low level routines for reading/writing to (raw)buffers:
527 #ifndef mingw32_HOST_OS
532 Unix has broken semantics when it comes to non-blocking I/O: you can
533 set the O_NONBLOCK flag on an FD, but it applies to the all other FDs
534 attached to the same underlying file, pipe or TTY; there's no way to
535 have private non-blocking behaviour for an FD. See bug #724.
537 We fix this by only setting O_NONBLOCK on FDs that we create; FDs that
538 come from external sources or are exposed externally are left in
539 blocking mode. This solution has some problems though. We can't
540 completely simulate a non-blocking read without O_NONBLOCK: several
541 cases are wrong here. The cases that are wrong:
543 * reading/writing to a blocking FD in non-threaded mode.
544 In threaded mode, we just make a safe call to read().
545 In non-threaded mode we call select() before attempting to read,
546 but that leaves a small race window where the data can be read
547 from the file descriptor before we issue our blocking read().
548 * readRawBufferNoBlock for a blocking FD
552 In the threaded RTS we could just make safe calls to read()/write()
553 for file descriptors in blocking mode without worrying about blocking
554 other threads, but the problem with this is that the thread will be
555 uninterruptible while it is blocked in the foreign call. See #2363.
556 So now we always call fdReady() before reading, and if fdReady
557 indicates that there's no data, we call threadWaitRead.
561 readRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
562 readRawBuffer loc fd is_nonblock buf off len
563 | is_nonblock = unsafe_read -- unsafe is ok, it can't block
564 | otherwise = do r <- throwErrnoIfMinus1 loc
565 (unsafe_fdReady (fromIntegral fd) 0 0 0)
568 else do threadWaitRead (fromIntegral fd); read
570 do_read call = throwErrnoIfMinus1RetryMayBlock loc call
571 (threadWaitRead (fromIntegral fd))
572 read = if threaded then safe_read else unsafe_read
573 unsafe_read = do_read (read_rawBuffer fd buf off len)
574 safe_read = do_read (safe_read_rawBuffer fd buf off len)
576 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
577 readRawBufferPtr loc fd is_nonblock buf off len
578 | is_nonblock = unsafe_read -- unsafe is ok, it can't block
579 | otherwise = do r <- throwErrnoIfMinus1 loc
580 (unsafe_fdReady (fromIntegral fd) 0 0 0)
583 else do threadWaitRead (fromIntegral fd); read
585 do_read call = throwErrnoIfMinus1RetryMayBlock loc call
586 (threadWaitRead (fromIntegral fd))
587 read = if threaded then safe_read else unsafe_read
588 unsafe_read = do_read (read_off fd buf off len)
589 safe_read = do_read (safe_read_off fd buf off len)
591 readRawBufferNoBlock :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
592 readRawBufferNoBlock loc fd is_nonblock buf off len
593 | is_nonblock = unsafe_read -- unsafe is ok, it can't block
594 | otherwise = do r <- unsafe_fdReady (fromIntegral fd) 0 0 0
595 if r /= 0 then safe_read
597 -- XXX see note [nonblock]
599 do_read call = throwErrnoIfMinus1RetryOnBlock loc call (return 0)
600 unsafe_read = do_read (read_rawBuffer fd buf off len)
601 safe_read = do_read (safe_read_rawBuffer fd buf off len)
603 readRawBufferPtrNoBlock :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
604 readRawBufferPtrNoBlock loc fd is_nonblock buf off len
605 | is_nonblock = unsafe_read -- unsafe is ok, it can't block
606 | otherwise = do r <- unsafe_fdReady (fromIntegral fd) 0 0 0
607 if r /= 0 then safe_read
609 -- XXX see note [nonblock]
611 do_read call = throwErrnoIfMinus1RetryOnBlock loc call (return 0)
612 unsafe_read = do_read (read_off fd buf off len)
613 safe_read = do_read (safe_read_off fd buf off len)
615 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
616 writeRawBuffer loc fd is_nonblock buf off len
617 | is_nonblock = unsafe_write -- unsafe is ok, it can't block
618 | otherwise = do r <- unsafe_fdReady (fromIntegral fd) 1 0 0
621 else do threadWaitWrite (fromIntegral fd); write
623 do_write call = throwErrnoIfMinus1RetryMayBlock loc call
624 (threadWaitWrite (fromIntegral fd))
625 write = if threaded then safe_write else unsafe_write
626 unsafe_write = do_write (write_rawBuffer fd buf off len)
627 safe_write = do_write (safe_write_rawBuffer (fromIntegral fd) buf off len)
629 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
630 writeRawBufferPtr loc fd is_nonblock buf off len
631 | is_nonblock = unsafe_write -- unsafe is ok, it can't block
632 | otherwise = do r <- unsafe_fdReady (fromIntegral fd) 1 0 0
635 else do threadWaitWrite (fromIntegral fd); write
637 do_write call = throwErrnoIfMinus1RetryMayBlock loc call
638 (threadWaitWrite (fromIntegral fd))
639 write = if threaded then safe_write else unsafe_write
640 unsafe_write = do_write (write_off fd buf off len)
641 safe_write = do_write (safe_write_off (fromIntegral fd) buf off len)
643 foreign import ccall unsafe "__hscore_PrelHandle_read"
644 read_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
646 foreign import ccall unsafe "__hscore_PrelHandle_read"
647 read_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
649 foreign import ccall unsafe "__hscore_PrelHandle_write"
650 write_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
652 foreign import ccall unsafe "__hscore_PrelHandle_write"
653 write_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
655 foreign import ccall unsafe "fdReady"
656 unsafe_fdReady :: CInt -> CInt -> CInt -> CInt -> IO CInt
658 #else /* mingw32_HOST_OS.... */
660 readRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
661 readRawBuffer loc fd is_stream buf off len
662 | threaded = blockingReadRawBuffer loc fd is_stream buf off len
663 | otherwise = asyncReadRawBuffer loc fd is_stream buf off len
665 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
666 readRawBufferPtr loc fd is_stream buf off len
667 | threaded = blockingReadRawBufferPtr loc fd is_stream buf off len
668 | otherwise = asyncReadRawBufferPtr loc fd is_stream buf off len
670 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
671 writeRawBuffer loc fd is_stream buf off len
672 | threaded = blockingWriteRawBuffer loc fd is_stream buf off len
673 | otherwise = asyncWriteRawBuffer loc fd is_stream buf off len
675 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
676 writeRawBufferPtr loc fd is_stream buf off len
677 | threaded = blockingWriteRawBufferPtr loc fd is_stream buf off len
678 | otherwise = asyncWriteRawBufferPtr loc fd is_stream buf off len
680 -- ToDo: we don't have a non-blocking primitve read on Win32
681 readRawBufferNoBlock :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
682 readRawBufferNoBlock = readRawBuffer
684 readRawBufferPtrNoBlock :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
685 readRawBufferPtrNoBlock = readRawBufferPtr
686 -- Async versions of the read/write primitives, for the non-threaded RTS
688 asyncReadRawBuffer loc fd is_stream buf off len = do
689 (l, rc) <- asyncReadBA (fromIntegral fd) (if is_stream then 1 else 0)
690 (fromIntegral len) off buf
693 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
694 else return (fromIntegral l)
696 asyncReadRawBufferPtr loc fd is_stream buf off len = do
697 (l, rc) <- asyncRead (fromIntegral fd) (if is_stream then 1 else 0)
698 (fromIntegral len) (buf `plusPtr` off)
701 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
702 else return (fromIntegral l)
704 asyncWriteRawBuffer loc fd is_stream buf off len = do
705 (l, rc) <- asyncWriteBA (fromIntegral fd) (if is_stream then 1 else 0)
706 (fromIntegral len) off buf
709 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
710 else return (fromIntegral l)
712 asyncWriteRawBufferPtr loc fd is_stream buf off len = do
713 (l, rc) <- asyncWrite (fromIntegral fd) (if is_stream then 1 else 0)
714 (fromIntegral len) (buf `plusPtr` off)
717 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
718 else return (fromIntegral l)
720 -- Blocking versions of the read/write primitives, for the threaded RTS
722 blockingReadRawBuffer loc fd True buf off len =
723 throwErrnoIfMinus1Retry loc $
724 safe_recv_rawBuffer fd buf off len
725 blockingReadRawBuffer loc fd False buf off len =
726 throwErrnoIfMinus1Retry loc $
727 safe_read_rawBuffer fd buf off len
729 blockingReadRawBufferPtr loc fd True buf off len =
730 throwErrnoIfMinus1Retry loc $
731 safe_recv_off fd buf off len
732 blockingReadRawBufferPtr loc fd False buf off len =
733 throwErrnoIfMinus1Retry loc $
734 safe_read_off fd buf off len
736 blockingWriteRawBuffer loc fd True buf off len =
737 throwErrnoIfMinus1Retry loc $
738 safe_send_rawBuffer fd buf off len
739 blockingWriteRawBuffer loc fd False buf off len =
740 throwErrnoIfMinus1Retry loc $
741 safe_write_rawBuffer fd buf off len
743 blockingWriteRawBufferPtr loc fd True buf off len =
744 throwErrnoIfMinus1Retry loc $
745 safe_send_off fd buf off len
746 blockingWriteRawBufferPtr loc fd False buf off len =
747 throwErrnoIfMinus1Retry loc $
748 safe_write_off fd buf off len
750 -- NOTE: "safe" versions of the read/write calls for use by the threaded RTS.
751 -- These calls may block, but that's ok.
753 foreign import ccall safe "__hscore_PrelHandle_recv"
754 safe_recv_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
756 foreign import ccall safe "__hscore_PrelHandle_recv"
757 safe_recv_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
759 foreign import ccall safe "__hscore_PrelHandle_send"
760 safe_send_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
762 foreign import ccall safe "__hscore_PrelHandle_send"
763 safe_send_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
767 foreign import ccall "rtsSupportsBoundThreads" threaded :: Bool
769 foreign import ccall safe "__hscore_PrelHandle_read"
770 safe_read_rawBuffer :: FD -> RawBuffer -> Int -> CInt -> IO CInt
772 foreign import ccall safe "__hscore_PrelHandle_read"
773 safe_read_off :: FD -> Ptr CChar -> Int -> CInt -> IO CInt
775 foreign import ccall safe "__hscore_PrelHandle_write"
776 safe_write_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
778 foreign import ccall safe "__hscore_PrelHandle_write"
779 safe_write_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
781 -- ---------------------------------------------------------------------------
784 -- Three handles are allocated during program initialisation. The first
785 -- two manage input or output from the Haskell program's standard input
786 -- or output channel respectively. The third manages output to the
787 -- standard error channel. These handles are initially open.
789 fd_stdin, fd_stdout, fd_stderr :: FD
794 -- | A handle managing input from the Haskell program's standard input channel.
796 stdin = 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_stdin ReadBuffer
802 mkStdHandle fd_stdin "<stdin>" ReadHandle buf bmode
804 -- | A handle managing output to the Haskell program's standard output channel.
806 stdout = 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]
811 (buf, bmode) <- getBuffer fd_stdout WriteBuffer
812 mkStdHandle fd_stdout "<stdout>" WriteHandle buf bmode
814 -- | A handle managing output to the Haskell program's standard error channel.
816 stderr = unsafePerformIO $ do
817 -- ToDo: acquire lock
818 -- We don't set non-blocking mode on standard handles, because it may
819 -- confuse other applications attached to the same TTY/pipe
820 -- see Note [nonblock]
822 mkStdHandle fd_stderr "<stderr>" WriteHandle buf NoBuffering
824 -- ---------------------------------------------------------------------------
825 -- Opening and Closing Files
827 addFilePathToIOError :: String -> FilePath -> IOException -> IOException
828 addFilePathToIOError fun fp (IOError h iot _ str _)
829 = IOError h iot fun str (Just fp)
831 -- | Computation 'openFile' @file mode@ allocates and returns a new, open
832 -- handle to manage the file @file@. It manages input if @mode@
833 -- is 'ReadMode', output if @mode@ is 'WriteMode' or 'AppendMode',
834 -- and both input and output if mode is 'ReadWriteMode'.
836 -- If the file does not exist and it is opened for output, it should be
837 -- created as a new file. If @mode@ is 'WriteMode' and the file
838 -- already exists, then it should be truncated to zero length.
839 -- Some operating systems delete empty files, so there is no guarantee
840 -- that the file will exist following an 'openFile' with @mode@
841 -- 'WriteMode' unless it is subsequently written to successfully.
842 -- The handle is positioned at the end of the file if @mode@ is
843 -- 'AppendMode', and otherwise at the beginning (in which case its
844 -- internal position is 0).
845 -- The initial buffer mode is implementation-dependent.
847 -- This operation may fail with:
849 -- * 'isAlreadyInUseError' if the file is already open and cannot be reopened;
851 -- * 'isDoesNotExistError' if the file does not exist; or
853 -- * 'isPermissionError' if the user does not have permission to open the file.
855 -- Note: if you will be working with files containing binary data, you'll want to
856 -- be using 'openBinaryFile'.
857 openFile :: FilePath -> IOMode -> IO Handle
860 (openFile' fp im dEFAULT_OPEN_IN_BINARY_MODE)
861 (\e -> ioError (addFilePathToIOError "openFile" fp e))
863 -- | Like 'openFile', but open the file in binary mode.
864 -- On Windows, reading a file in text mode (which is the default)
865 -- will translate CRLF to LF, and writing will translate LF to CRLF.
866 -- This is usually what you want with text files. With binary files
867 -- this is undesirable; also, as usual under Microsoft operating systems,
868 -- text mode treats control-Z as EOF. Binary mode turns off all special
869 -- treatment of end-of-line and end-of-file characters.
870 -- (See also 'hSetBinaryMode'.)
872 openBinaryFile :: FilePath -> IOMode -> IO Handle
873 openBinaryFile fp m =
875 (openFile' fp m True)
876 (\e -> ioError (addFilePathToIOError "openBinaryFile" fp e))
878 openFile' :: String -> IOMode -> Bool -> IO Handle
879 openFile' filepath mode binary =
880 withCString filepath $ \ f ->
883 oflags1 = case mode of
884 ReadMode -> read_flags
885 #ifdef mingw32_HOST_OS
886 WriteMode -> write_flags .|. o_TRUNC
888 WriteMode -> write_flags
890 ReadWriteMode -> rw_flags
891 AppendMode -> append_flags
897 oflags = oflags1 .|. binary_flags
900 -- the old implementation had a complicated series of three opens,
901 -- which is perhaps because we have to be careful not to open
902 -- directories. However, the man pages I've read say that open()
903 -- always returns EISDIR if the file is a directory and was opened
904 -- for writing, so I think we're ok with a single open() here...
905 fd <- throwErrnoIfMinus1Retry "openFile"
906 (c_open f (fromIntegral oflags) 0o666)
908 stat@(fd_type,_,_) <- fdStat fd
910 h <- fdToHandle_stat fd (Just stat) False filepath mode binary
911 `catchAny` \e -> do c_close fd; throw e
912 -- NB. don't forget to close the FD if fdToHandle' fails, otherwise
914 -- ASSERT: if we just created the file, then fdToHandle' won't fail
915 -- (so we don't need to worry about removing the newly created file
916 -- in the event of an error).
918 #ifndef mingw32_HOST_OS
919 -- we want to truncate() if this is an open in WriteMode, but only
920 -- if the target is a RegularFile. ftruncate() fails on special files
922 if mode == WriteMode && fd_type == RegularFile
923 then throwErrnoIf (/=0) "openFile"
930 std_flags, output_flags, read_flags, write_flags, rw_flags,
932 std_flags = o_NONBLOCK .|. o_NOCTTY
933 output_flags = std_flags .|. o_CREAT
934 read_flags = std_flags .|. o_RDONLY
935 write_flags = output_flags .|. o_WRONLY
936 rw_flags = output_flags .|. o_RDWR
937 append_flags = write_flags .|. o_APPEND
939 -- ---------------------------------------------------------------------------
942 fdToHandle_stat :: FD
943 -> Maybe (FDType, CDev, CIno)
950 fdToHandle_stat fd mb_stat is_socket filepath mode binary = do
952 #ifdef mingw32_HOST_OS
953 -- On Windows, the is_socket flag indicates that the Handle is a socket
955 -- On Unix, the is_socket flag indicates that the FD can be made non-blocking
956 let non_blocking = is_socket
958 when non_blocking $ setNonBlockingFD fd
959 -- turn on non-blocking mode
962 let (ha_type, write) =
964 ReadMode -> ( ReadHandle, False )
965 WriteMode -> ( WriteHandle, True )
966 ReadWriteMode -> ( ReadWriteHandle, True )
967 AppendMode -> ( AppendHandle, True )
969 -- open() won't tell us if it was a directory if we only opened for
970 -- reading, so check again.
978 ioException (IOError Nothing InappropriateType "openFile"
979 "is a directory" Nothing)
981 -- regular files need to be locked
983 #ifndef mingw32_HOST_OS
984 -- On Windows we use explicit exclusion via sopen() to implement
985 -- this locking (see __hscore_open()); on Unix we have to
986 -- implment it in the RTS.
987 r <- lockFile fd dev ino (fromBool write)
989 ioException (IOError Nothing ResourceBusy "openFile"
990 "file is locked" Nothing)
992 mkFileHandle fd is_socket filepath ha_type binary
995 -- only *Streams* can be DuplexHandles. Other read/write
996 -- Handles must share a buffer.
997 | ReadWriteHandle <- ha_type ->
998 mkDuplexHandle fd is_socket filepath binary
1000 mkFileHandle fd is_socket filepath ha_type binary
1003 mkFileHandle fd is_socket filepath ha_type binary
1005 -- | Old API kept to avoid breaking clients
1006 fdToHandle' :: FD -> Maybe FDType -> Bool -> FilePath -> IOMode -> Bool
1008 fdToHandle' fd mb_type is_socket filepath mode binary
1010 let mb_stat = case mb_type of
1012 -- fdToHandle_stat will do the stat:
1013 Just RegularFile -> Nothing
1014 -- no stat required for streams etc.:
1015 Just other -> Just (other,0,0)
1016 fdToHandle_stat fd mb_stat is_socket filepath mode binary
1018 fdToHandle :: FD -> IO Handle
1020 mode <- fdGetMode fd
1021 let fd_str = "<file descriptor: " ++ show fd ++ ">"
1022 fdToHandle_stat fd Nothing False fd_str mode True{-bin mode-}
1023 -- NB. the is_socket flag is False, meaning that:
1024 -- on Unix the file descriptor will *not* be put in non-blocking mode
1025 -- on Windows we're guessing this is not a socket (XXX)
1027 #ifndef mingw32_HOST_OS
1028 foreign import ccall unsafe "lockFile"
1029 lockFile :: CInt -> CDev -> CIno -> CInt -> IO CInt
1031 foreign import ccall unsafe "unlockFile"
1032 unlockFile :: CInt -> IO CInt
1035 mkStdHandle :: FD -> FilePath -> HandleType -> IORef Buffer -> BufferMode
1037 mkStdHandle fd filepath ha_type buf bmode = do
1038 spares <- newIORef BufferListNil
1039 newFileHandle filepath (stdHandleFinalizer filepath)
1040 (Handle__ { haFD = fd,
1042 haIsBin = dEFAULT_OPEN_IN_BINARY_MODE,
1043 haIsStream = False, -- means FD is blocking on Unix
1044 haBufferMode = bmode,
1047 haOtherSide = Nothing
1050 mkFileHandle :: FD -> Bool -> FilePath -> HandleType -> Bool -> IO Handle
1051 mkFileHandle fd is_stream filepath ha_type binary = do
1052 (buf, bmode) <- getBuffer fd (initBufferState ha_type)
1054 #ifdef mingw32_HOST_OS
1055 -- On Windows, if this is a read/write handle and we are in text mode,
1056 -- turn off buffering. We don't correctly handle the case of switching
1057 -- from read mode to write mode on a buffered text-mode handle, see bug
1059 bmode <- case ha_type of
1060 ReadWriteHandle | not binary -> return NoBuffering
1061 _other -> return bmode
1064 spares <- newIORef BufferListNil
1065 newFileHandle filepath (handleFinalizer filepath)
1066 (Handle__ { haFD = fd,
1069 haIsStream = is_stream,
1070 haBufferMode = bmode,
1073 haOtherSide = Nothing
1076 mkDuplexHandle :: FD -> Bool -> FilePath -> Bool -> IO Handle
1077 mkDuplexHandle fd is_stream filepath binary = do
1078 (w_buf, w_bmode) <- getBuffer fd WriteBuffer
1079 w_spares <- newIORef BufferListNil
1081 Handle__ { haFD = fd,
1082 haType = WriteHandle,
1084 haIsStream = is_stream,
1085 haBufferMode = w_bmode,
1087 haBuffers = w_spares,
1088 haOtherSide = Nothing
1090 write_side <- newMVar w_handle_
1092 (r_buf, r_bmode) <- getBuffer fd ReadBuffer
1093 r_spares <- newIORef BufferListNil
1095 Handle__ { haFD = fd,
1096 haType = ReadHandle,
1098 haIsStream = is_stream,
1099 haBufferMode = r_bmode,
1101 haBuffers = r_spares,
1102 haOtherSide = Just write_side
1104 read_side <- newMVar r_handle_
1106 addMVarFinalizer write_side (handleFinalizer filepath write_side)
1107 return (DuplexHandle filepath read_side write_side)
1109 initBufferState :: HandleType -> BufferState
1110 initBufferState ReadHandle = ReadBuffer
1111 initBufferState _ = WriteBuffer
1113 -- ---------------------------------------------------------------------------
1116 -- | Computation 'hClose' @hdl@ makes handle @hdl@ closed. Before the
1117 -- computation finishes, if @hdl@ is writable its buffer is flushed as
1119 -- Performing 'hClose' on a handle that has already been closed has no effect;
1120 -- doing so is not an error. All other operations on a closed handle will fail.
1121 -- If 'hClose' fails for any reason, any further operations (apart from
1122 -- 'hClose') on the handle will still fail as if @hdl@ had been successfully
1125 hClose :: Handle -> IO ()
1126 hClose h@(FileHandle _ m) = do
1127 mb_exc <- hClose' h m
1129 Nothing -> return ()
1131 hClose h@(DuplexHandle _ r w) = do
1132 mb_exc1 <- hClose' h w
1133 mb_exc2 <- hClose' h r
1134 case (do mb_exc1; mb_exc2) of
1135 Nothing -> return ()
1138 hClose' :: Handle -> MVar Handle__ -> IO (Maybe SomeException)
1139 hClose' h m = withHandle' "hClose" h m $ hClose_help
1141 -- hClose_help is also called by lazyRead (in PrelIO) when EOF is read
1142 -- or an IO error occurs on a lazy stream. The semi-closed Handle is
1143 -- then closed immediately. We have to be careful with DuplexHandles
1144 -- though: we have to leave the closing to the finalizer in that case,
1145 -- because the write side may still be in use.
1146 hClose_help :: Handle__ -> IO (Handle__, Maybe SomeException)
1147 hClose_help handle_ =
1148 case haType handle_ of
1149 ClosedHandle -> return (handle_,Nothing)
1150 _ -> do flushWriteBufferOnly handle_ -- interruptible
1151 hClose_handle_ handle_
1153 hClose_handle_ :: Handle__ -> IO (Handle__, Maybe SomeException)
1154 hClose_handle_ handle_ = do
1155 let fd = haFD handle_
1157 -- close the file descriptor, but not when this is the read
1158 -- side of a duplex handle.
1159 -- If an exception is raised by the close(), we want to continue
1160 -- to close the handle and release the lock if it has one, then
1161 -- we return the exception to the caller of hClose_help which can
1162 -- raise it if necessary.
1164 case haOtherSide handle_ of
1166 throwErrnoIfMinus1Retry_ "hClose"
1167 #ifdef mingw32_HOST_OS
1168 (closeFd (haIsStream handle_) fd)
1174 `catchException` \e -> return (Just e)
1176 Just _ -> return Nothing
1178 -- free the spare buffers
1179 writeIORef (haBuffers handle_) BufferListNil
1180 writeIORef (haBuffer handle_) noBuffer
1182 #ifndef mingw32_HOST_OS
1187 -- we must set the fd to -1, because the finalizer is going
1188 -- to run eventually and try to close/unlock it.
1189 return (handle_{ haFD = -1,
1190 haType = ClosedHandle
1194 {-# NOINLINE noBuffer #-}
1196 noBuffer = unsafePerformIO $ allocateBuffer 1 ReadBuffer
1198 -----------------------------------------------------------------------------
1199 -- Detecting and changing the size of a file
1201 -- | For a handle @hdl@ which attached to a physical file,
1202 -- 'hFileSize' @hdl@ returns the size of that file in 8-bit bytes.
1204 hFileSize :: Handle -> IO Integer
1206 withHandle_ "hFileSize" handle $ \ handle_ -> do
1207 case haType handle_ of
1208 ClosedHandle -> ioe_closedHandle
1209 SemiClosedHandle -> ioe_closedHandle
1210 _ -> do flushWriteBufferOnly handle_
1211 r <- fdFileSize (haFD handle_)
1214 else ioException (IOError Nothing InappropriateType "hFileSize"
1215 "not a regular file" Nothing)
1218 -- | 'hSetFileSize' @hdl@ @size@ truncates the physical file with handle @hdl@ to @size@ bytes.
1220 hSetFileSize :: Handle -> Integer -> IO ()
1221 hSetFileSize handle size =
1222 withHandle_ "hSetFileSize" handle $ \ handle_ -> do
1223 case haType handle_ of
1224 ClosedHandle -> ioe_closedHandle
1225 SemiClosedHandle -> ioe_closedHandle
1226 _ -> do flushWriteBufferOnly handle_
1227 throwErrnoIf (/=0) "hSetFileSize"
1228 (c_ftruncate (haFD handle_) (fromIntegral size))
1231 -- ---------------------------------------------------------------------------
1232 -- Detecting the End of Input
1234 -- | For a readable handle @hdl@, 'hIsEOF' @hdl@ returns
1235 -- 'True' if no further input can be taken from @hdl@ or for a
1236 -- physical file, if the current I\/O position is equal to the length of
1237 -- the file. Otherwise, it returns 'False'.
1239 -- NOTE: 'hIsEOF' may block, because it is the same as calling
1240 -- 'hLookAhead' and checking for an EOF exception.
1242 hIsEOF :: Handle -> IO Bool
1245 (do hLookAhead handle; return False)
1246 (\e -> if isEOFError e then return True else ioError e)
1248 -- | The computation 'isEOF' is identical to 'hIsEOF',
1249 -- except that it works only on 'stdin'.
1252 isEOF = hIsEOF stdin
1254 -- ---------------------------------------------------------------------------
1257 -- | Computation 'hLookAhead' returns the next character from the handle
1258 -- without removing it from the input buffer, blocking until a character
1261 -- This operation may fail with:
1263 -- * 'isEOFError' if the end of file has been reached.
1265 hLookAhead :: Handle -> IO Char
1267 wantReadableHandle "hLookAhead" handle hLookAhead'
1269 hLookAhead' :: Handle__ -> IO Char
1270 hLookAhead' handle_ = do
1271 let ref = haBuffer handle_
1273 buf <- readIORef ref
1275 -- fill up the read buffer if necessary
1276 new_buf <- if bufferEmpty buf
1277 then fillReadBuffer fd True (haIsStream handle_) buf
1280 writeIORef ref new_buf
1282 (c,_) <- readCharFromBuffer (bufBuf buf) (bufRPtr buf)
1285 -- ---------------------------------------------------------------------------
1286 -- Buffering Operations
1288 -- Three kinds of buffering are supported: line-buffering,
1289 -- block-buffering or no-buffering. See GHC.IOBase for definition and
1290 -- further explanation of what the type represent.
1292 -- | Computation 'hSetBuffering' @hdl mode@ sets the mode of buffering for
1293 -- handle @hdl@ on subsequent reads and writes.
1295 -- If the buffer mode is changed from 'BlockBuffering' or
1296 -- 'LineBuffering' to 'NoBuffering', then
1298 -- * if @hdl@ is writable, the buffer is flushed as for 'hFlush';
1300 -- * if @hdl@ is not writable, the contents of the buffer is discarded.
1302 -- This operation may fail with:
1304 -- * 'isPermissionError' if the handle has already been used for reading
1305 -- or writing and the implementation does not allow the buffering mode
1308 hSetBuffering :: Handle -> BufferMode -> IO ()
1309 hSetBuffering handle mode =
1310 withAllHandles__ "hSetBuffering" handle $ \ handle_ -> do
1311 case haType handle_ of
1312 ClosedHandle -> ioe_closedHandle
1315 - we flush the old buffer regardless of whether
1316 the new buffer could fit the contents of the old buffer
1318 - allow a handle's buffering to change even if IO has
1319 occurred (ANSI C spec. does not allow this, nor did
1320 the previous implementation of IO.hSetBuffering).
1321 - a non-standard extension is to allow the buffering
1322 of semi-closed handles to change [sof 6/98]
1326 let state = initBufferState (haType handle_)
1329 -- we always have a 1-character read buffer for
1330 -- unbuffered handles: it's needed to
1331 -- support hLookAhead.
1332 NoBuffering -> allocateBuffer 1 ReadBuffer
1333 LineBuffering -> allocateBuffer dEFAULT_BUFFER_SIZE state
1334 BlockBuffering Nothing -> allocateBuffer dEFAULT_BUFFER_SIZE state
1335 BlockBuffering (Just n) | n <= 0 -> ioe_bufsiz n
1336 | otherwise -> allocateBuffer n state
1337 writeIORef (haBuffer handle_) new_buf
1339 -- for input terminals we need to put the terminal into
1340 -- cooked or raw mode depending on the type of buffering.
1341 is_tty <- fdIsTTY (haFD handle_)
1342 when (is_tty && isReadableHandleType (haType handle_)) $
1344 #ifndef mingw32_HOST_OS
1345 -- 'raw' mode under win32 is a bit too specialised (and troublesome
1346 -- for most common uses), so simply disable its use here.
1347 NoBuffering -> setCooked (haFD handle_) False
1349 NoBuffering -> return ()
1351 _ -> setCooked (haFD handle_) True
1353 -- throw away spare buffers, they might be the wrong size
1354 writeIORef (haBuffers handle_) BufferListNil
1356 return (handle_{ haBufferMode = mode })
1358 -- -----------------------------------------------------------------------------
1361 -- | The action 'hFlush' @hdl@ causes any items buffered for output
1362 -- in handle @hdl@ to be sent immediately to the operating system.
1364 -- This operation may fail with:
1366 -- * 'isFullError' if the device is full;
1368 -- * 'isPermissionError' if a system resource limit would be exceeded.
1369 -- It is unspecified whether the characters in the buffer are discarded
1370 -- or retained under these circumstances.
1372 hFlush :: Handle -> IO ()
1374 wantWritableHandle "hFlush" handle $ \ handle_ -> do
1375 buf <- readIORef (haBuffer handle_)
1376 if bufferIsWritable buf && not (bufferEmpty buf)
1377 then do flushed_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
1378 writeIORef (haBuffer handle_) flushed_buf
1382 -- -----------------------------------------------------------------------------
1383 -- Repositioning Handles
1385 data HandlePosn = HandlePosn Handle HandlePosition
1387 instance Eq HandlePosn where
1388 (HandlePosn h1 p1) == (HandlePosn h2 p2) = p1==p2 && h1==h2
1390 instance Show HandlePosn where
1391 showsPrec p (HandlePosn h pos) =
1392 showsPrec p h . showString " at position " . shows pos
1394 -- HandlePosition is the Haskell equivalent of POSIX' off_t.
1395 -- We represent it as an Integer on the Haskell side, but
1396 -- cheat slightly in that hGetPosn calls upon a C helper
1397 -- that reports the position back via (merely) an Int.
1398 type HandlePosition = Integer
1400 -- | Computation 'hGetPosn' @hdl@ returns the current I\/O position of
1401 -- @hdl@ as a value of the abstract type 'HandlePosn'.
1403 hGetPosn :: Handle -> IO HandlePosn
1404 hGetPosn handle = do
1405 posn <- hTell handle
1406 return (HandlePosn handle posn)
1408 -- | If a call to 'hGetPosn' @hdl@ returns a position @p@,
1409 -- then computation 'hSetPosn' @p@ sets the position of @hdl@
1410 -- to the position it held at the time of the call to 'hGetPosn'.
1412 -- This operation may fail with:
1414 -- * 'isPermissionError' if a system resource limit would be exceeded.
1416 hSetPosn :: HandlePosn -> IO ()
1417 hSetPosn (HandlePosn h i) = hSeek h AbsoluteSeek i
1419 -- ---------------------------------------------------------------------------
1422 -- | A mode that determines the effect of 'hSeek' @hdl mode i@, as follows:
1424 = AbsoluteSeek -- ^ the position of @hdl@ is set to @i@.
1425 | RelativeSeek -- ^ the position of @hdl@ is set to offset @i@
1426 -- from the current position.
1427 | SeekFromEnd -- ^ the position of @hdl@ is set to offset @i@
1428 -- from the end of the file.
1429 deriving (Eq, Ord, Ix, Enum, Read, Show)
1432 - when seeking using `SeekFromEnd', positive offsets (>=0) means
1433 seeking at or past EOF.
1435 - we possibly deviate from the report on the issue of seeking within
1436 the buffer and whether to flush it or not. The report isn't exactly
1440 -- | Computation 'hSeek' @hdl mode i@ sets the position of handle
1441 -- @hdl@ depending on @mode@.
1442 -- The offset @i@ is given in terms of 8-bit bytes.
1444 -- If @hdl@ is block- or line-buffered, then seeking to a position which is not
1445 -- in the current buffer will first cause any items in the output buffer to be
1446 -- written to the device, and then cause the input buffer to be discarded.
1447 -- Some handles may not be seekable (see 'hIsSeekable'), or only support a
1448 -- subset of the possible positioning operations (for instance, it may only
1449 -- be possible to seek to the end of a tape, or to a positive offset from
1450 -- the beginning or current position).
1451 -- It is not possible to set a negative I\/O position, or for
1452 -- a physical file, an I\/O position beyond the current end-of-file.
1454 -- This operation may fail with:
1456 -- * 'isPermissionError' if a system resource limit would be exceeded.
1458 hSeek :: Handle -> SeekMode -> Integer -> IO ()
1459 hSeek handle mode offset =
1460 wantSeekableHandle "hSeek" handle $ \ handle_ -> do
1462 puts ("hSeek " ++ show (mode,offset) ++ "\n")
1464 let ref = haBuffer handle_
1465 buf <- readIORef ref
1471 throwErrnoIfMinus1Retry_ "hSeek"
1472 (c_lseek (haFD handle_) (fromIntegral offset) whence)
1475 whence = case mode of
1476 AbsoluteSeek -> sEEK_SET
1477 RelativeSeek -> sEEK_CUR
1478 SeekFromEnd -> sEEK_END
1480 if bufferIsWritable buf
1481 then do new_buf <- flushWriteBuffer fd (haIsStream handle_) buf
1482 writeIORef ref new_buf
1486 if mode == RelativeSeek && offset >= 0 && offset < fromIntegral (w - r)
1487 then writeIORef ref buf{ bufRPtr = r + fromIntegral offset }
1490 new_buf <- flushReadBuffer (haFD handle_) buf
1491 writeIORef ref new_buf
1495 hTell :: Handle -> IO Integer
1497 wantSeekableHandle "hGetPosn" handle $ \ handle_ -> do
1499 #if defined(mingw32_HOST_OS)
1500 -- urgh, on Windows we have to worry about \n -> \r\n translation,
1501 -- so we can't easily calculate the file position using the
1502 -- current buffer size. Just flush instead.
1505 let fd = haFD handle_
1506 posn <- fromIntegral `liftM`
1507 throwErrnoIfMinus1Retry "hGetPosn"
1508 (c_lseek fd 0 sEEK_CUR)
1510 let ref = haBuffer handle_
1511 buf <- readIORef ref
1514 | bufferIsWritable buf = posn + fromIntegral (bufWPtr buf)
1515 | otherwise = posn - fromIntegral (bufWPtr buf - bufRPtr buf)
1517 puts ("\nhGetPosn: (fd, posn, real_posn) = " ++ show (fd, posn, real_posn) ++ "\n")
1518 puts (" (bufWPtr, bufRPtr) = " ++ show (bufWPtr buf, bufRPtr buf) ++ "\n")
1522 -- -----------------------------------------------------------------------------
1523 -- Handle Properties
1525 -- A number of operations return information about the properties of a
1526 -- handle. Each of these operations returns `True' if the handle has
1527 -- the specified property, and `False' otherwise.
1529 hIsOpen :: Handle -> IO Bool
1531 withHandle_ "hIsOpen" handle $ \ handle_ -> do
1532 case haType handle_ of
1533 ClosedHandle -> return False
1534 SemiClosedHandle -> return False
1537 hIsClosed :: Handle -> IO Bool
1539 withHandle_ "hIsClosed" handle $ \ handle_ -> do
1540 case haType handle_ of
1541 ClosedHandle -> return True
1544 {- not defined, nor exported, but mentioned
1545 here for documentation purposes:
1547 hSemiClosed :: Handle -> IO Bool
1551 return (not (ho || hc))
1554 hIsReadable :: Handle -> IO Bool
1555 hIsReadable (DuplexHandle _ _ _) = return True
1556 hIsReadable handle =
1557 withHandle_ "hIsReadable" handle $ \ handle_ -> do
1558 case haType handle_ of
1559 ClosedHandle -> ioe_closedHandle
1560 SemiClosedHandle -> ioe_closedHandle
1561 htype -> return (isReadableHandleType htype)
1563 hIsWritable :: Handle -> IO Bool
1564 hIsWritable (DuplexHandle _ _ _) = return True
1565 hIsWritable handle =
1566 withHandle_ "hIsWritable" handle $ \ handle_ -> do
1567 case haType handle_ of
1568 ClosedHandle -> ioe_closedHandle
1569 SemiClosedHandle -> ioe_closedHandle
1570 htype -> return (isWritableHandleType htype)
1572 -- | Computation 'hGetBuffering' @hdl@ returns the current buffering mode
1575 hGetBuffering :: Handle -> IO BufferMode
1576 hGetBuffering handle =
1577 withHandle_ "hGetBuffering" handle $ \ handle_ -> do
1578 case haType handle_ of
1579 ClosedHandle -> ioe_closedHandle
1581 -- We're being non-standard here, and allow the buffering
1582 -- of a semi-closed handle to be queried. -- sof 6/98
1583 return (haBufferMode handle_) -- could be stricter..
1585 hIsSeekable :: Handle -> IO Bool
1586 hIsSeekable handle =
1587 withHandle_ "hIsSeekable" handle $ \ handle_ -> do
1588 case haType handle_ of
1589 ClosedHandle -> ioe_closedHandle
1590 SemiClosedHandle -> ioe_closedHandle
1591 AppendHandle -> return False
1592 _ -> do t <- fdType (haFD handle_)
1593 return ((t == RegularFile || t == RawDevice)
1594 && (haIsBin handle_ || tEXT_MODE_SEEK_ALLOWED))
1596 -- -----------------------------------------------------------------------------
1597 -- Changing echo status (Non-standard GHC extensions)
1599 -- | Set the echoing status of a handle connected to a terminal.
1601 hSetEcho :: Handle -> Bool -> IO ()
1602 hSetEcho handle on = do
1603 isT <- hIsTerminalDevice handle
1607 withHandle_ "hSetEcho" handle $ \ handle_ -> do
1608 case haType handle_ of
1609 ClosedHandle -> ioe_closedHandle
1610 _ -> setEcho (haFD handle_) on
1612 -- | Get the echoing status of a handle connected to a terminal.
1614 hGetEcho :: Handle -> IO Bool
1615 hGetEcho handle = do
1616 isT <- hIsTerminalDevice handle
1620 withHandle_ "hGetEcho" handle $ \ handle_ -> do
1621 case haType handle_ of
1622 ClosedHandle -> ioe_closedHandle
1623 _ -> getEcho (haFD handle_)
1625 -- | Is the handle connected to a terminal?
1627 hIsTerminalDevice :: Handle -> IO Bool
1628 hIsTerminalDevice handle = do
1629 withHandle_ "hIsTerminalDevice" handle $ \ handle_ -> do
1630 case haType handle_ of
1631 ClosedHandle -> ioe_closedHandle
1632 _ -> fdIsTTY (haFD handle_)
1634 -- -----------------------------------------------------------------------------
1637 -- | Select binary mode ('True') or text mode ('False') on a open handle.
1638 -- (See also 'openBinaryFile'.)
1640 hSetBinaryMode :: Handle -> Bool -> IO ()
1641 hSetBinaryMode handle bin =
1642 withAllHandles__ "hSetBinaryMode" handle $ \ handle_ ->
1643 do throwErrnoIfMinus1_ "hSetBinaryMode"
1644 (setmode (haFD handle_) bin)
1645 return handle_{haIsBin=bin}
1647 foreign import ccall unsafe "__hscore_setmode"
1648 setmode :: CInt -> Bool -> IO CInt
1650 -- -----------------------------------------------------------------------------
1651 -- Duplicating a Handle
1653 -- | Returns a duplicate of the original handle, with its own buffer.
1654 -- The two Handles will share a file pointer, however. The original
1655 -- handle's buffer is flushed, including discarding any input data,
1656 -- before the handle is duplicated.
1658 hDuplicate :: Handle -> IO Handle
1659 hDuplicate h@(FileHandle path m) = do
1660 new_h_ <- withHandle' "hDuplicate" h m (dupHandle h Nothing)
1661 newFileHandle path (handleFinalizer path) new_h_
1662 hDuplicate h@(DuplexHandle path r w) = do
1663 new_w_ <- withHandle' "hDuplicate" h w (dupHandle h Nothing)
1664 new_w <- newMVar new_w_
1665 new_r_ <- withHandle' "hDuplicate" h r (dupHandle h (Just new_w))
1666 new_r <- newMVar new_r_
1667 addMVarFinalizer new_w (handleFinalizer path new_w)
1668 return (DuplexHandle path new_r new_w)
1670 dupHandle :: Handle -> Maybe (MVar Handle__) -> Handle__
1671 -> IO (Handle__, Handle__)
1672 dupHandle h other_side h_ = do
1673 -- flush the buffer first, so we don't have to copy its contents
1675 new_fd <- case other_side of
1676 Nothing -> throwErrnoIfMinus1 "dupHandle" $ c_dup (haFD h_)
1677 Just r -> withHandle_' "dupHandle" h r (return . haFD)
1678 dupHandle_ other_side h_ new_fd
1680 dupHandleTo :: Maybe (MVar Handle__) -> Handle__ -> Handle__
1681 -> IO (Handle__, Handle__)
1682 dupHandleTo other_side hto_ h_ = do
1684 -- Windows' dup2 does not return the new descriptor, unlike Unix
1685 throwErrnoIfMinus1 "dupHandleTo" $
1686 c_dup2 (haFD h_) (haFD hto_)
1687 dupHandle_ other_side h_ (haFD hto_)
1689 dupHandle_ :: Maybe (MVar Handle__) -> Handle__ -> FD
1690 -> IO (Handle__, Handle__)
1691 dupHandle_ other_side h_ new_fd = do
1692 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE (initBufferState (haType h_))
1693 ioref <- newIORef buffer
1694 ioref_buffers <- newIORef BufferListNil
1696 let new_handle_ = h_{ haFD = new_fd,
1698 haBuffers = ioref_buffers,
1699 haOtherSide = other_side }
1700 return (h_, new_handle_)
1702 -- -----------------------------------------------------------------------------
1703 -- Replacing a Handle
1706 Makes the second handle a duplicate of the first handle. The second
1707 handle will be closed first, if it is not already.
1709 This can be used to retarget the standard Handles, for example:
1711 > do h <- openFile "mystdout" WriteMode
1712 > hDuplicateTo h stdout
1715 hDuplicateTo :: Handle -> Handle -> IO ()
1716 hDuplicateTo h1@(FileHandle _ m1) h2@(FileHandle _ m2) = do
1717 withHandle__' "hDuplicateTo" h2 m2 $ \h2_ -> do
1718 _ <- hClose_help h2_
1719 withHandle' "hDuplicateTo" h1 m1 (dupHandleTo Nothing h2_)
1720 hDuplicateTo h1@(DuplexHandle _ r1 w1) h2@(DuplexHandle _ r2 w2) = do
1721 withHandle__' "hDuplicateTo" h2 w2 $ \w2_ -> do
1722 _ <- hClose_help w2_
1723 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo Nothing w2_)
1724 withHandle__' "hDuplicateTo" h2 r2 $ \r2_ -> do
1725 _ <- hClose_help r2_
1726 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo (Just w1) r2_)
1728 ioException (IOError (Just h1) IllegalOperation "hDuplicateTo"
1729 "handles are incompatible" Nothing)
1731 -- ---------------------------------------------------------------------------
1734 -- | 'hShow' is in the 'IO' monad, and gives more comprehensive output
1735 -- than the (pure) instance of 'Show' for 'Handle'.
1737 hShow :: Handle -> IO String
1738 hShow h@(FileHandle path _) = showHandle' path False h
1739 hShow h@(DuplexHandle path _ _) = showHandle' path True h
1741 showHandle' :: String -> Bool -> Handle -> IO String
1742 showHandle' filepath is_duplex h =
1743 withHandle_ "showHandle" h $ \hdl_ ->
1745 showType | is_duplex = showString "duplex (read-write)"
1746 | otherwise = shows (haType hdl_)
1750 showHdl (haType hdl_)
1751 (showString "loc=" . showString filepath . showChar ',' .
1752 showString "type=" . showType . showChar ',' .
1753 showString "binary=" . shows (haIsBin hdl_) . showChar ',' .
1754 showString "buffering=" . showBufMode (unsafePerformIO (readIORef (haBuffer hdl_))) (haBufferMode hdl_) . showString "}" )
1758 showHdl :: HandleType -> ShowS -> ShowS
1761 ClosedHandle -> shows ht . showString "}"
1764 showBufMode :: Buffer -> BufferMode -> ShowS
1765 showBufMode buf bmo =
1767 NoBuffering -> showString "none"
1768 LineBuffering -> showString "line"
1769 BlockBuffering (Just n) -> showString "block " . showParen True (shows n)
1770 BlockBuffering Nothing -> showString "block " . showParen True (shows def)
1775 -- ---------------------------------------------------------------------------
1778 #if defined(DEBUG_DUMP)
1779 puts :: String -> IO ()
1780 puts s = do write_rawBuffer 1 (unsafeCoerce# (packCString# s)) 0 (fromIntegral (length s))
1784 -- -----------------------------------------------------------------------------
1787 throwErrnoIfMinus1RetryOnBlock :: String -> IO CInt -> IO CInt -> IO CInt
1788 throwErrnoIfMinus1RetryOnBlock loc f on_block =
1791 if (res :: CInt) == -1
1795 then throwErrnoIfMinus1RetryOnBlock loc f on_block
1796 else if err == eWOULDBLOCK || err == eAGAIN
1801 -- -----------------------------------------------------------------------------
1802 -- wrappers to platform-specific constants:
1804 foreign import ccall unsafe "__hscore_supportsTextMode"
1805 tEXT_MODE_SEEK_ALLOWED :: Bool
1807 foreign import ccall unsafe "__hscore_bufsiz" dEFAULT_BUFFER_SIZE :: Int
1808 foreign import ccall unsafe "__hscore_seek_cur" sEEK_CUR :: CInt
1809 foreign import ccall unsafe "__hscore_seek_set" sEEK_SET :: CInt
1810 foreign import ccall unsafe "__hscore_seek_end" sEEK_END :: CInt