1 {-# OPTIONS_GHC -fno-implicit-prelude -#include "HsBase.h" #-}
6 -----------------------------------------------------------------------------
9 -- Copyright : (c) The University of Glasgow, 1994-2001
10 -- License : see libraries/base/LICENSE
12 -- Maintainer : libraries@haskell.org
13 -- Stability : internal
14 -- Portability : non-portable
16 -- This module defines the basic operations on I\/O \"handles\".
18 -----------------------------------------------------------------------------
22 withHandle, withHandle', withHandle_,
23 wantWritableHandle, wantReadableHandle, wantSeekableHandle,
25 newEmptyBuffer, allocateBuffer, readCharFromBuffer, writeCharIntoBuffer,
26 flushWriteBufferOnly, flushWriteBuffer, flushReadBuffer,
27 fillReadBuffer, fillReadBufferWithoutBlocking,
28 readRawBuffer, readRawBufferPtr,
29 writeRawBuffer, writeRawBufferPtr,
31 #ifndef mingw32_HOST_OS
35 ioe_closedHandle, ioe_EOF, ioe_notReadable, ioe_notWritable,
37 stdin, stdout, stderr,
38 IOMode(..), openFile, openBinaryFile, openTempFile, openBinaryTempFile, openFd, fdToHandle,
39 hFileSize, hSetFileSize, hIsEOF, isEOF, hLookAhead, hSetBuffering, hSetBinaryMode,
40 hFlush, hDuplicate, hDuplicateTo,
44 HandlePosition, HandlePosn(..), hGetPosn, hSetPosn,
45 SeekMode(..), hSeek, hTell,
47 hIsOpen, hIsClosed, hIsReadable, hIsWritable, hGetBuffering, hIsSeekable,
48 hSetEcho, hGetEcho, hIsTerminalDevice,
58 import System.Directory.Internals
64 import System.IO.Error
65 import System.Posix.Internals
71 import GHC.Read ( Read )
76 import GHC.Num ( Integer(..), Num(..) )
78 import GHC.Real ( toInteger )
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) <- catchException (act h_)
147 (\ err -> putMVar m h_ >>
149 IOException ex -> ioError (augmentIOError ex fun h)
151 checkBufferInvariants h'
155 {-# INLINE withHandle_ #-}
156 withHandle_ :: String -> Handle -> (Handle__ -> IO a) -> IO a
157 withHandle_ fun h@(FileHandle _ m) act = withHandle_' fun h m act
158 withHandle_ fun h@(DuplexHandle _ m _) act = withHandle_' fun h m act
160 withHandle_' :: String -> Handle -> MVar Handle__ -> (Handle__ -> IO a) -> IO a
161 withHandle_' fun h m act =
164 checkBufferInvariants h_
165 v <- catchException (act h_)
166 (\ err -> putMVar m h_ >>
168 IOException ex -> ioError (augmentIOError ex fun h)
170 checkBufferInvariants h_
174 withAllHandles__ :: String -> Handle -> (Handle__ -> IO Handle__) -> IO ()
175 withAllHandles__ fun h@(FileHandle _ m) act = withHandle__' fun h m act
176 withAllHandles__ fun h@(DuplexHandle _ r w) act = do
177 withHandle__' fun h r act
178 withHandle__' fun h w act
180 withHandle__' fun h m act =
183 checkBufferInvariants h_
184 h' <- catchException (act h_)
185 (\ err -> putMVar m h_ >>
187 IOException ex -> ioError (augmentIOError ex fun h)
189 checkBufferInvariants h'
193 augmentIOError (IOError _ iot _ str fp) fun h
194 = IOError (Just h) iot fun str filepath
197 | otherwise = case h of
198 FileHandle fp _ -> Just fp
199 DuplexHandle fp _ _ -> Just fp
201 -- ---------------------------------------------------------------------------
202 -- Wrapper for write operations.
204 wantWritableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
205 wantWritableHandle fun h@(FileHandle _ m) act
206 = wantWritableHandle' fun h m act
207 wantWritableHandle fun h@(DuplexHandle _ _ m) act
208 = wantWritableHandle' fun h m act
209 -- ToDo: in the Duplex case, we don't need to checkWritableHandle
212 :: String -> Handle -> MVar Handle__
213 -> (Handle__ -> IO a) -> IO a
214 wantWritableHandle' fun h m act
215 = withHandle_' fun h m (checkWritableHandle act)
217 checkWritableHandle act handle_
218 = case haType handle_ of
219 ClosedHandle -> ioe_closedHandle
220 SemiClosedHandle -> ioe_closedHandle
221 ReadHandle -> ioe_notWritable
222 ReadWriteHandle -> do
223 let ref = haBuffer handle_
226 if not (bufferIsWritable buf)
227 then do b <- flushReadBuffer (haFD handle_) buf
228 return b{ bufState=WriteBuffer }
230 writeIORef ref new_buf
232 _other -> act handle_
234 -- ---------------------------------------------------------------------------
235 -- Wrapper for read operations.
237 wantReadableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
238 wantReadableHandle fun h@(FileHandle _ m) act
239 = wantReadableHandle' fun h m act
240 wantReadableHandle fun h@(DuplexHandle _ m _) act
241 = wantReadableHandle' fun h m act
242 -- ToDo: in the Duplex case, we don't need to checkReadableHandle
245 :: String -> Handle -> MVar Handle__
246 -> (Handle__ -> IO a) -> IO a
247 wantReadableHandle' fun h m act
248 = withHandle_' fun h m (checkReadableHandle act)
250 checkReadableHandle act handle_ =
251 case haType handle_ of
252 ClosedHandle -> ioe_closedHandle
253 SemiClosedHandle -> ioe_closedHandle
254 AppendHandle -> ioe_notReadable
255 WriteHandle -> ioe_notReadable
256 ReadWriteHandle -> do
257 let ref = haBuffer handle_
259 when (bufferIsWritable buf) $ do
260 new_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
261 writeIORef ref new_buf{ bufState=ReadBuffer }
263 _other -> act handle_
265 -- ---------------------------------------------------------------------------
266 -- Wrapper for seek operations.
268 wantSeekableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
269 wantSeekableHandle fun h@(DuplexHandle _ _ _) _act =
270 ioException (IOError (Just h) IllegalOperation fun
271 "handle is not seekable" Nothing)
272 wantSeekableHandle fun h@(FileHandle _ m) act =
273 withHandle_' fun h m (checkSeekableHandle act)
275 checkSeekableHandle act handle_ =
276 case haType handle_ of
277 ClosedHandle -> ioe_closedHandle
278 SemiClosedHandle -> ioe_closedHandle
279 AppendHandle -> ioe_notSeekable
280 _ | haIsBin handle_ || tEXT_MODE_SEEK_ALLOWED -> act handle_
281 | otherwise -> ioe_notSeekable_notBin
283 -- -----------------------------------------------------------------------------
286 ioe_closedHandle, ioe_EOF,
287 ioe_notReadable, ioe_notWritable,
288 ioe_notSeekable, ioe_notSeekable_notBin :: IO a
290 ioe_closedHandle = ioException
291 (IOError Nothing IllegalOperation ""
292 "handle is closed" Nothing)
293 ioe_EOF = ioException
294 (IOError Nothing EOF "" "" Nothing)
295 ioe_notReadable = ioException
296 (IOError Nothing IllegalOperation ""
297 "handle is not open for reading" Nothing)
298 ioe_notWritable = ioException
299 (IOError Nothing IllegalOperation ""
300 "handle is not open for writing" Nothing)
301 ioe_notSeekable = ioException
302 (IOError Nothing IllegalOperation ""
303 "handle is not seekable" Nothing)
304 ioe_notSeekable_notBin = ioException
305 (IOError Nothing IllegalOperation ""
306 "seek operations on text-mode handles are not allowed on this platform"
309 ioe_finalizedHandle fp = throw (IOException
310 (IOError Nothing IllegalOperation ""
311 "handle is finalized" (Just fp)))
313 ioe_bufsiz :: Int -> IO a
314 ioe_bufsiz n = ioException
315 (IOError Nothing InvalidArgument "hSetBuffering"
316 ("illegal buffer size " ++ showsPrec 9 n []) Nothing)
317 -- 9 => should be parens'ified.
319 -- -----------------------------------------------------------------------------
322 -- For a duplex handle, we arrange that the read side points to the write side
323 -- (and hence keeps it alive if the read side is alive). This is done by
324 -- having the haOtherSide field of the read side point to the read side.
325 -- The finalizer is then placed on the write side, and the handle only gets
326 -- finalized once, when both sides are no longer required.
328 -- NOTE about finalized handles: It's possible that a handle can be
329 -- finalized and then we try to use it later, for example if the
330 -- handle is referenced from another finalizer, or from a thread that
331 -- has become unreferenced and then resurrected (arguably in the
332 -- latter case we shouldn't finalize the Handle...). Anyway,
333 -- we try to emit a helpful message which is better than nothing.
335 stdHandleFinalizer :: FilePath -> MVar Handle__ -> IO ()
336 stdHandleFinalizer fp m = do
338 flushWriteBufferOnly h_
339 putMVar m (ioe_finalizedHandle fp)
341 handleFinalizer :: FilePath -> MVar Handle__ -> IO ()
342 handleFinalizer fp m = do
343 handle_ <- takeMVar m
344 case haType handle_ of
345 ClosedHandle -> return ()
346 _ -> do flushWriteBufferOnly handle_ `catchException` \_ -> return ()
347 -- ignore errors and async exceptions, and close the
348 -- descriptor anyway...
349 hClose_handle_ handle_
351 putMVar m (ioe_finalizedHandle fp)
353 -- ---------------------------------------------------------------------------
354 -- Grimy buffer operations
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 h_ = 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 #ifdef mingw32_HOST_OS
381 -- To implement asynchronous I/O under Win32, we have to pass
382 -- buffer references to external threads that handles the
383 -- filling/emptying of their contents. Hence, the buffer cannot
384 -- be moved around by the GC.
385 case newPinnedByteArray# size s of { (# s, b #) ->
387 case newByteArray# size s of { (# s, b #) ->
389 (# s, newEmptyBuffer b state sz #) }
391 writeCharIntoBuffer :: RawBuffer -> Int -> Char -> IO Int
392 writeCharIntoBuffer slab (I# off) (C# c)
393 = IO $ \s -> case writeCharArray# slab off c s of
394 s -> (# s, I# (off +# 1#) #)
396 readCharFromBuffer :: RawBuffer -> Int -> IO (Char, Int)
397 readCharFromBuffer slab (I# off)
398 = IO $ \s -> case readCharArray# slab off s of
399 (# s, c #) -> (# s, (C# c, I# (off +# 1#)) #)
401 getBuffer :: FD -> BufferState -> IO (IORef Buffer, BufferMode)
402 getBuffer fd state = do
403 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE state
404 ioref <- newIORef buffer
408 | is_tty = LineBuffering
409 | otherwise = BlockBuffering Nothing
411 return (ioref, buffer_mode)
413 mkUnBuffer :: IO (IORef Buffer)
415 buffer <- allocateBuffer 1 ReadBuffer
418 -- flushWriteBufferOnly flushes the buffer iff it contains pending write data.
419 flushWriteBufferOnly :: Handle__ -> IO ()
420 flushWriteBufferOnly h_ = do
424 new_buf <- if bufferIsWritable buf
425 then flushWriteBuffer fd (haIsStream h_) buf
427 writeIORef ref new_buf
429 -- flushBuffer syncs the file with the buffer, including moving the
430 -- file pointer backwards in the case of a read buffer.
431 flushBuffer :: Handle__ -> IO ()
433 let ref = haBuffer h_
438 ReadBuffer -> flushReadBuffer (haFD h_) buf
439 WriteBuffer -> flushWriteBuffer (haFD h_) (haIsStream h_) buf
441 writeIORef ref flushed_buf
443 -- When flushing a read buffer, we seek backwards by the number of
444 -- characters in the buffer. The file descriptor must therefore be
445 -- seekable: attempting to flush the read buffer on an unseekable
446 -- handle is not allowed.
448 flushReadBuffer :: FD -> Buffer -> IO Buffer
449 flushReadBuffer fd buf
450 | bufferEmpty buf = return buf
452 let off = negate (bufWPtr buf - bufRPtr buf)
454 puts ("flushReadBuffer: new file offset = " ++ show off ++ "\n")
456 throwErrnoIfMinus1Retry "flushReadBuffer"
457 (c_lseek fd (fromIntegral off) sEEK_CUR)
458 return buf{ bufWPtr=0, bufRPtr=0 }
460 flushWriteBuffer :: FD -> Bool -> Buffer -> IO Buffer
461 flushWriteBuffer fd is_stream buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w } =
462 seq fd $ do -- strictness hack
465 puts ("flushWriteBuffer, fd=" ++ show fd ++ ", bytes=" ++ show bytes ++ "\n")
468 then return (buf{ bufRPtr=0, bufWPtr=0 })
470 res <- writeRawBuffer "flushWriteBuffer" fd is_stream b
471 (fromIntegral r) (fromIntegral bytes)
472 let res' = fromIntegral res
474 then flushWriteBuffer fd is_stream (buf{ bufRPtr = r + res' })
475 else return buf{ bufRPtr=0, bufWPtr=0 }
477 fillReadBuffer :: FD -> Bool -> Bool -> Buffer -> IO Buffer
478 fillReadBuffer fd is_line is_stream
479 buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w, bufSize=size } =
480 -- buffer better be empty:
481 assert (r == 0 && w == 0) $ do
482 fillReadBufferLoop fd is_line is_stream buf b w size
484 -- For a line buffer, we just get the first chunk of data to arrive,
485 -- and don't wait for the whole buffer to be full (but we *do* wait
486 -- until some data arrives). This isn't really line buffering, but it
487 -- appears to be what GHC has done for a long time, and I suspect it
488 -- is more useful than line buffering in most cases.
490 fillReadBufferLoop fd is_line is_stream buf b w size = do
492 if bytes == 0 -- buffer full?
493 then return buf{ bufRPtr=0, bufWPtr=w }
496 puts ("fillReadBufferLoop: bytes = " ++ show bytes ++ "\n")
498 res <- readRawBuffer "fillReadBuffer" fd is_stream b
499 (fromIntegral w) (fromIntegral bytes)
500 let res' = fromIntegral res
502 puts ("fillReadBufferLoop: res' = " ++ show res' ++ "\n")
507 else return buf{ bufRPtr=0, bufWPtr=w }
508 else if res' < bytes && not is_line
509 then fillReadBufferLoop fd is_line is_stream buf b (w+res') size
510 else return buf{ bufRPtr=0, bufWPtr=w+res' }
513 fillReadBufferWithoutBlocking :: FD -> Bool -> Buffer -> IO Buffer
514 fillReadBufferWithoutBlocking fd is_stream
515 buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w, bufSize=size } =
516 -- buffer better be empty:
517 assert (r == 0 && w == 0) $ do
519 puts ("fillReadBufferLoopNoBlock: bytes = " ++ show size ++ "\n")
521 res <- readRawBufferNoBlock "fillReadBuffer" fd is_stream b
522 0 (fromIntegral size)
523 let res' = fromIntegral res
525 puts ("fillReadBufferLoopNoBlock: res' = " ++ show res' ++ "\n")
527 return buf{ bufRPtr=0, bufWPtr=res' }
529 -- Low level routines for reading/writing to (raw)buffers:
531 #ifndef mingw32_HOST_OS
536 Unix has broken semantics when it comes to non-blocking I/O: you can
537 set the O_NONBLOCK flag on an FD, but it applies to the all other FDs
538 attached to the same underlying file, pipe or TTY; there's no way to
539 have private non-blocking behaviour for an FD. See bug #724.
541 We fix this by only setting O_NONBLOCK on FDs that we create; FDs that
542 come from external sources or are exposed externally are left in
543 blocking mode. This solution has some problems though. We can't
544 completely simulate a non-blocking read without O_NONBLOCK: several
545 cases are wrong here. The cases that are wrong:
547 * reading/writing to a blocking FD in non-threaded mode.
548 In threaded mode, we just make a safe call to read().
549 In non-threaded mode we call select() before attempting to read,
550 but that leaves a small race window where the data can be read
551 from the file descriptor before we issue our blocking read().
552 * readRawBufferNoBlock for a blocking FD
555 readRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
556 readRawBuffer loc fd is_nonblock buf off len
557 | is_nonblock = unsafe_read
558 | threaded = safe_read
559 | otherwise = do r <- throwErrnoIfMinus1 loc
560 (fdReady (fromIntegral fd) 0 0 False)
563 else do threadWaitRead (fromIntegral fd); unsafe_read
565 do_read call = throwErrnoIfMinus1RetryMayBlock loc call
566 (threadWaitRead (fromIntegral fd))
567 unsafe_read = do_read (read_rawBuffer fd buf off len)
568 safe_read = do_read (safe_read_rawBuffer fd buf off len)
570 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
571 readRawBufferPtr loc fd is_nonblock buf off len
572 | is_nonblock = unsafe_read
573 | threaded = safe_read
574 | otherwise = do r <- throwErrnoIfMinus1 loc
575 (fdReady (fromIntegral fd) 0 0 False)
578 else do threadWaitRead (fromIntegral fd); unsafe_read
580 do_read call = throwErrnoIfMinus1RetryMayBlock loc call
581 (threadWaitRead (fromIntegral fd))
582 unsafe_read = do_read (read_off fd buf off len)
583 safe_read = do_read (safe_read_off fd buf off len)
585 readRawBufferNoBlock :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
586 readRawBufferNoBlock loc fd is_nonblock buf off len
587 | is_nonblock = unsafe_read
588 | otherwise = do r <- fdReady (fromIntegral fd) 0 0 False
589 if r /= 0 then safe_read
591 -- XXX see note [nonblock]
593 do_read call = throwErrnoIfMinus1RetryMayBlock loc call (return 0)
594 unsafe_read = do_read (read_rawBuffer fd buf off len)
595 safe_read = do_read (safe_read_rawBuffer fd buf off len)
597 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
598 writeRawBuffer loc fd is_nonblock buf off len
599 | is_nonblock = unsafe_write
600 | threaded = safe_write
601 | otherwise = do r <- fdReady (fromIntegral fd) 1 0 False
602 if r /= 0 then safe_write
605 do_write call = throwErrnoIfMinus1RetryMayBlock loc call
606 (threadWaitWrite (fromIntegral fd))
607 unsafe_write = do_write (write_rawBuffer fd buf off len)
608 safe_write = do_write (safe_write_rawBuffer (fromIntegral fd) buf off len)
610 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
611 writeRawBufferPtr loc fd is_nonblock buf off len
612 | is_nonblock = unsafe_write
613 | threaded = safe_write
614 | otherwise = do r <- fdReady (fromIntegral fd) 1 0 False
615 if r /= 0 then safe_write
618 do_write call = throwErrnoIfMinus1RetryMayBlock loc call
619 (threadWaitWrite (fromIntegral fd))
620 unsafe_write = do_write (write_off fd buf off len)
621 safe_write = do_write (safe_write_off (fromIntegral fd) buf off len)
623 foreign import ccall unsafe "__hscore_PrelHandle_read"
624 read_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
626 foreign import ccall unsafe "__hscore_PrelHandle_read"
627 read_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
629 foreign import ccall unsafe "__hscore_PrelHandle_write"
630 write_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
632 foreign import ccall unsafe "__hscore_PrelHandle_write"
633 write_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
635 foreign import ccall safe "fdReady"
636 fdReady :: CInt -> CInt -> CInt -> Bool -> IO CInt
638 #else /* mingw32_HOST_OS.... */
640 readRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
641 readRawBuffer loc fd is_stream buf off len
642 | threaded = blockingReadRawBuffer loc fd is_stream buf off len
643 | otherwise = asyncReadRawBuffer loc fd is_stream buf off len
645 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
646 readRawBufferPtr loc fd is_stream buf off len
647 | threaded = blockingReadRawBufferPtr loc fd is_stream buf off len
648 | otherwise = asyncReadRawBufferPtr loc fd is_stream buf off len
650 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
651 writeRawBuffer loc fd is_stream buf off len
652 | threaded = blockingWriteRawBuffer loc fd is_stream buf off len
653 | otherwise = asyncWriteRawBuffer loc fd is_stream buf off len
655 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
656 writeRawBufferPtr loc fd is_stream buf off len
657 | threaded = blockingWriteRawBufferPtr loc fd is_stream buf off len
658 | otherwise = asyncWriteRawBufferPtr loc fd is_stream buf off len
660 -- ToDo: we don't have a non-blocking primitve read on Win32
661 readRawBufferNoBlock :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
662 readRawBufferNoBlock = readRawBuffer
664 -- Async versions of the read/write primitives, for the non-threaded RTS
666 asyncReadRawBuffer loc fd is_stream buf off len = do
667 (l, rc) <- asyncReadBA (fromIntegral fd) (if is_stream then 1 else 0)
668 (fromIntegral len) off buf
671 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
672 else return (fromIntegral l)
674 asyncReadRawBufferPtr loc fd is_stream buf off len = do
675 (l, rc) <- asyncRead (fromIntegral fd) (if is_stream then 1 else 0)
676 (fromIntegral len) (buf `plusPtr` off)
679 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
680 else return (fromIntegral l)
682 asyncWriteRawBuffer loc fd is_stream buf off len = do
683 (l, rc) <- asyncWriteBA (fromIntegral fd) (if is_stream then 1 else 0)
684 (fromIntegral len) off buf
687 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
688 else return (fromIntegral l)
690 asyncWriteRawBufferPtr loc fd is_stream buf off len = do
691 (l, rc) <- asyncWrite (fromIntegral fd) (if is_stream then 1 else 0)
692 (fromIntegral len) (buf `plusPtr` off)
695 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
696 else return (fromIntegral l)
698 -- Blocking versions of the read/write primitives, for the threaded RTS
700 blockingReadRawBuffer loc fd True buf off len =
701 throwErrnoIfMinus1Retry loc $
702 safe_recv_rawBuffer fd buf off len
703 blockingReadRawBuffer loc fd False buf off len =
704 throwErrnoIfMinus1Retry loc $
705 safe_read_rawBuffer fd buf off len
707 blockingReadRawBufferPtr loc fd True buf off len =
708 throwErrnoIfMinus1Retry loc $
709 safe_recv_off fd buf off len
710 blockingReadRawBufferPtr loc fd False buf off len =
711 throwErrnoIfMinus1Retry loc $
712 safe_read_off fd buf off len
714 blockingWriteRawBuffer loc fd True buf off len =
715 throwErrnoIfMinus1Retry loc $
716 safe_send_rawBuffer fd buf off len
717 blockingWriteRawBuffer loc fd False buf off len =
718 throwErrnoIfMinus1Retry loc $
719 safe_write_rawBuffer fd buf off len
721 blockingWriteRawBufferPtr loc fd True buf off len =
722 throwErrnoIfMinus1Retry loc $
723 safe_send_off fd buf off len
724 blockingWriteRawBufferPtr loc fd False buf off len =
725 throwErrnoIfMinus1Retry loc $
726 safe_write_off fd buf off len
728 -- NOTE: "safe" versions of the read/write calls for use by the threaded RTS.
729 -- These calls may block, but that's ok.
731 foreign import ccall safe "__hscore_PrelHandle_recv"
732 safe_recv_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
734 foreign import ccall safe "__hscore_PrelHandle_recv"
735 safe_recv_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
737 foreign import ccall safe "__hscore_PrelHandle_send"
738 safe_send_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
740 foreign import ccall safe "__hscore_PrelHandle_send"
741 safe_send_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
745 foreign import ccall "rtsSupportsBoundThreads" threaded :: Bool
747 foreign import ccall safe "__hscore_PrelHandle_read"
748 safe_read_rawBuffer :: FD -> RawBuffer -> Int -> CInt -> IO CInt
750 foreign import ccall safe "__hscore_PrelHandle_read"
751 safe_read_off :: FD -> Ptr CChar -> Int -> CInt -> IO CInt
753 foreign import ccall safe "__hscore_PrelHandle_write"
754 safe_write_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
756 foreign import ccall safe "__hscore_PrelHandle_write"
757 safe_write_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
759 -- ---------------------------------------------------------------------------
762 -- Three handles are allocated during program initialisation. The first
763 -- two manage input or output from the Haskell program's standard input
764 -- or output channel respectively. The third manages output to the
765 -- standard error channel. These handles are initially open.
771 -- | A handle managing input from the Haskell program's standard input channel.
773 stdin = unsafePerformIO $ do
774 -- ToDo: acquire lock
775 -- We don't set non-blocking mode on standard handles, because it may
776 -- confuse other applications attached to the same TTY/pipe
777 -- see Note [nonblock]
778 (buf, bmode) <- getBuffer fd_stdin ReadBuffer
779 mkStdHandle fd_stdin "<stdin>" ReadHandle buf bmode
781 -- | A handle managing output to the Haskell program's standard output channel.
783 stdout = unsafePerformIO $ do
784 -- ToDo: acquire lock
785 -- We don't set non-blocking mode on standard handles, because it may
786 -- confuse other applications attached to the same TTY/pipe
787 -- see Note [nonblock]
788 (buf, bmode) <- getBuffer fd_stdout WriteBuffer
789 mkStdHandle fd_stdout "<stdout>" WriteHandle buf bmode
791 -- | A handle managing output to the Haskell program's standard error channel.
793 stderr = unsafePerformIO $ do
794 -- ToDo: acquire lock
795 -- We don't set non-blocking mode on standard handles, because it may
796 -- confuse other applications attached to the same TTY/pipe
797 -- see Note [nonblock]
799 mkStdHandle fd_stderr "<stderr>" WriteHandle buf NoBuffering
801 -- ---------------------------------------------------------------------------
802 -- Opening and Closing Files
804 addFilePathToIOError fun fp (IOError h iot _ str _)
805 = IOError h iot fun str (Just fp)
807 -- | Computation 'openFile' @file mode@ allocates and returns a new, open
808 -- handle to manage the file @file@. It manages input if @mode@
809 -- is 'ReadMode', output if @mode@ is 'WriteMode' or 'AppendMode',
810 -- and both input and output if mode is 'ReadWriteMode'.
812 -- If the file does not exist and it is opened for output, it should be
813 -- created as a new file. If @mode@ is 'WriteMode' and the file
814 -- already exists, then it should be truncated to zero length.
815 -- Some operating systems delete empty files, so there is no guarantee
816 -- that the file will exist following an 'openFile' with @mode@
817 -- 'WriteMode' unless it is subsequently written to successfully.
818 -- The handle is positioned at the end of the file if @mode@ is
819 -- 'AppendMode', and otherwise at the beginning (in which case its
820 -- internal position is 0).
821 -- The initial buffer mode is implementation-dependent.
823 -- This operation may fail with:
825 -- * 'isAlreadyInUseError' if the file is already open and cannot be reopened;
827 -- * 'isDoesNotExistError' if the file does not exist; or
829 -- * 'isPermissionError' if the user does not have permission to open the file.
831 -- Note: if you will be working with files containing binary data, you'll want to
832 -- be using 'openBinaryFile'.
833 openFile :: FilePath -> IOMode -> IO Handle
836 (openFile' fp im dEFAULT_OPEN_IN_BINARY_MODE)
837 (\e -> ioError (addFilePathToIOError "openFile" fp e))
839 -- | Like 'openFile', but open the file in binary mode.
840 -- On Windows, reading a file in text mode (which is the default)
841 -- will translate CRLF to LF, and writing will translate LF to CRLF.
842 -- This is usually what you want with text files. With binary files
843 -- this is undesirable; also, as usual under Microsoft operating systems,
844 -- text mode treats control-Z as EOF. Binary mode turns off all special
845 -- treatment of end-of-line and end-of-file characters.
846 -- (See also 'hSetBinaryMode'.)
848 openBinaryFile :: FilePath -> IOMode -> IO Handle
849 openBinaryFile fp m =
851 (openFile' fp m True)
852 (\e -> ioError (addFilePathToIOError "openBinaryFile" fp e))
854 openFile' filepath mode binary =
855 withCString filepath $ \ f ->
858 oflags1 = case mode of
859 ReadMode -> read_flags
860 #ifdef mingw32_HOST_OS
861 WriteMode -> write_flags .|. o_TRUNC
863 WriteMode -> write_flags
865 ReadWriteMode -> rw_flags
866 AppendMode -> append_flags
872 oflags = oflags1 .|. binary_flags
875 -- the old implementation had a complicated series of three opens,
876 -- which is perhaps because we have to be careful not to open
877 -- directories. However, the man pages I've read say that open()
878 -- always returns EISDIR if the file is a directory and was opened
879 -- for writing, so I think we're ok with a single open() here...
880 fd <- throwErrnoIfMinus1Retry "openFile"
881 (c_open f (fromIntegral oflags) 0o666)
885 h <- openFd fd (Just fd_type) False filepath mode binary
886 `catchException` \e -> do c_close fd; throw e
887 -- NB. don't forget to close the FD if openFd fails, otherwise
889 -- ASSERT: if we just created the file, then openFd won't fail
890 -- (so we don't need to worry about removing the newly created file
891 -- in the event of an error).
893 #ifndef mingw32_HOST_OS
894 -- we want to truncate() if this is an open in WriteMode, but only
895 -- if the target is a RegularFile. ftruncate() fails on special files
897 if mode == WriteMode && fd_type == RegularFile
898 then throwErrnoIf (/=0) "openFile"
905 -- | The function creates a temporary file in ReadWrite mode.
906 -- The created file isn\'t deleted automatically, so you need to delete it manually.
907 openTempFile :: FilePath -- ^ Directory in which to create the file
908 -> String -- ^ File name template. If the template is \"foo.ext\" then
909 -- the create file will be \"fooXXX.ext\" where XXX is some
911 -> IO (FilePath, Handle)
912 openTempFile tmp_dir template = openTempFile' "openTempFile" tmp_dir template dEFAULT_OPEN_IN_BINARY_MODE
914 -- | Like 'openTempFile', but opens the file in binary mode. See 'openBinaryFile' for more comments.
915 openBinaryTempFile :: FilePath -> String -> IO (FilePath, Handle)
916 openBinaryTempFile tmp_dir template = openTempFile' "openBinaryTempFile" tmp_dir template True
918 openTempFile' :: String -> FilePath -> String -> Bool -> IO (FilePath, Handle)
919 openTempFile' loc tmp_dir template binary = do
923 (prefix,suffix) = break (=='.') template
925 oflags1 = rw_flags .|. o_EXCL
931 oflags = oflags1 .|. binary_flags
934 fd <- withCString filepath $ \ f ->
935 c_open f oflags 0o666
940 then findTempName (x+1)
941 else ioError (errnoToIOError loc errno Nothing (Just tmp_dir))
943 h <- openFd fd Nothing False filepath ReadWriteMode True
944 `catchException` \e -> do c_close fd; throw e
947 filename = prefix ++ show x ++ suffix
948 filepath = tmp_dir `joinFileName` filename
951 std_flags = o_NONBLOCK .|. o_NOCTTY
952 output_flags = std_flags .|. o_CREAT
953 read_flags = std_flags .|. o_RDONLY
954 write_flags = output_flags .|. o_WRONLY
955 rw_flags = output_flags .|. o_RDWR
956 append_flags = write_flags .|. o_APPEND
958 -- ---------------------------------------------------------------------------
961 openFd :: FD -> Maybe FDType -> Bool -> FilePath -> IOMode -> Bool -> IO Handle
962 openFd fd mb_fd_type is_socket filepath mode binary = do
963 -- turn on non-blocking mode
966 #ifdef mingw32_HOST_OS
967 -- On Windows, the is_stream flag indicates that the Handle is a socket
968 let is_stream = is_socket
970 -- On Unix, the is_stream flag indicates that the FD is non-blocking
974 let (ha_type, write) =
976 ReadMode -> ( ReadHandle, False )
977 WriteMode -> ( WriteHandle, True )
978 ReadWriteMode -> ( ReadWriteHandle, True )
979 AppendMode -> ( AppendHandle, True )
981 -- open() won't tell us if it was a directory if we only opened for
982 -- reading, so check again.
990 ioException (IOError Nothing InappropriateType "openFile"
991 "is a directory" Nothing)
993 -- regular files need to be locked
995 #ifndef mingw32_HOST_OS
996 r <- lockFile fd (fromBool write) 1{-exclusive-}
998 ioException (IOError Nothing ResourceBusy "openFile"
999 "file is locked" Nothing)
1001 mkFileHandle fd is_stream filepath ha_type binary
1004 -- only *Streams* can be DuplexHandles. Other read/write
1005 -- Handles must share a buffer.
1006 | ReadWriteHandle <- ha_type ->
1007 mkDuplexHandle fd is_stream filepath binary
1009 mkFileHandle fd is_stream filepath ha_type binary
1012 mkFileHandle fd is_stream filepath ha_type binary
1014 fdToHandle :: FD -> IO Handle
1016 mode <- fdGetMode fd
1017 let fd_str = "<file descriptor: " ++ show fd ++ ">"
1018 openFd fd Nothing False{-XXX!-} fd_str mode True{-bin mode-}
1021 #ifndef mingw32_HOST_OS
1022 foreign import ccall unsafe "lockFile"
1023 lockFile :: CInt -> CInt -> CInt -> IO CInt
1025 foreign import ccall unsafe "unlockFile"
1026 unlockFile :: CInt -> IO CInt
1029 mkStdHandle :: FD -> FilePath -> HandleType -> IORef Buffer -> BufferMode
1031 mkStdHandle fd filepath ha_type buf bmode = do
1032 spares <- newIORef BufferListNil
1033 newFileHandle filepath (stdHandleFinalizer filepath)
1034 (Handle__ { haFD = fd,
1036 haIsBin = dEFAULT_OPEN_IN_BINARY_MODE,
1037 haIsStream = False, -- means FD is blocking on Unix
1038 haBufferMode = bmode,
1041 haOtherSide = Nothing
1044 mkFileHandle :: FD -> Bool -> FilePath -> HandleType -> Bool -> IO Handle
1045 mkFileHandle fd is_stream filepath ha_type binary = do
1046 (buf, bmode) <- getBuffer fd (initBufferState ha_type)
1048 #ifdef mingw32_HOST_OS
1049 -- On Windows, if this is a read/write handle and we are in text mode,
1050 -- turn off buffering. We don't correctly handle the case of switching
1051 -- from read mode to write mode on a buffered text-mode handle, see bug
1053 bmode <- case ha_type of
1054 ReadWriteHandle | not binary -> return NoBuffering
1055 _other -> return bmode
1058 spares <- newIORef BufferListNil
1059 newFileHandle filepath (handleFinalizer filepath)
1060 (Handle__ { haFD = fd,
1063 haIsStream = is_stream,
1064 haBufferMode = bmode,
1067 haOtherSide = Nothing
1070 mkDuplexHandle :: FD -> Bool -> FilePath -> Bool -> IO Handle
1071 mkDuplexHandle fd is_stream filepath binary = do
1072 (w_buf, w_bmode) <- getBuffer fd WriteBuffer
1073 w_spares <- newIORef BufferListNil
1075 Handle__ { haFD = fd,
1076 haType = WriteHandle,
1078 haIsStream = is_stream,
1079 haBufferMode = w_bmode,
1081 haBuffers = w_spares,
1082 haOtherSide = Nothing
1084 write_side <- newMVar w_handle_
1086 (r_buf, r_bmode) <- getBuffer fd ReadBuffer
1087 r_spares <- newIORef BufferListNil
1089 Handle__ { haFD = fd,
1090 haType = ReadHandle,
1092 haIsStream = is_stream,
1093 haBufferMode = r_bmode,
1095 haBuffers = r_spares,
1096 haOtherSide = Just write_side
1098 read_side <- newMVar r_handle_
1100 addMVarFinalizer write_side (handleFinalizer filepath write_side)
1101 return (DuplexHandle filepath read_side write_side)
1104 initBufferState ReadHandle = ReadBuffer
1105 initBufferState _ = WriteBuffer
1107 -- ---------------------------------------------------------------------------
1110 -- | Computation 'hClose' @hdl@ makes handle @hdl@ closed. Before the
1111 -- computation finishes, if @hdl@ is writable its buffer is flushed as
1113 -- Performing 'hClose' on a handle that has already been closed has no effect;
1114 -- doing so not an error. All other operations on a closed handle will fail.
1115 -- If 'hClose' fails for any reason, any further operations (apart from
1116 -- 'hClose') on the handle will still fail as if @hdl@ had been successfully
1119 hClose :: Handle -> IO ()
1120 hClose h@(FileHandle _ m) = hClose' h m
1121 hClose h@(DuplexHandle _ r w) = hClose' h w >> hClose' h r
1123 hClose' h m = withHandle__' "hClose" h m $ hClose_help
1125 -- hClose_help is also called by lazyRead (in PrelIO) when EOF is read
1126 -- or an IO error occurs on a lazy stream. The semi-closed Handle is
1127 -- then closed immediately. We have to be careful with DuplexHandles
1128 -- though: we have to leave the closing to the finalizer in that case,
1129 -- because the write side may still be in use.
1130 hClose_help :: Handle__ -> IO Handle__
1131 hClose_help handle_ =
1132 case haType handle_ of
1133 ClosedHandle -> return handle_
1134 _ -> do flushWriteBufferOnly handle_ -- interruptible
1135 hClose_handle_ handle_
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 case haOtherSide handle_ of
1144 throwErrnoIfMinus1Retry_ "hClose"
1145 #ifdef mingw32_HOST_OS
1146 (closeFd (haIsStream handle_) fd)
1152 -- free the spare buffers
1153 writeIORef (haBuffers handle_) BufferListNil
1155 #ifndef mingw32_HOST_OS
1160 -- we must set the fd to -1, because the finalizer is going
1161 -- to run eventually and try to close/unlock it.
1162 return (handle_{ haFD = -1,
1163 haType = ClosedHandle
1166 -----------------------------------------------------------------------------
1167 -- Detecting and changing the size of a file
1169 -- | For a handle @hdl@ which attached to a physical file,
1170 -- 'hFileSize' @hdl@ returns the size of that file in 8-bit bytes.
1172 hFileSize :: Handle -> IO Integer
1174 withHandle_ "hFileSize" handle $ \ handle_ -> do
1175 case haType handle_ of
1176 ClosedHandle -> ioe_closedHandle
1177 SemiClosedHandle -> ioe_closedHandle
1178 _ -> do flushWriteBufferOnly handle_
1179 r <- fdFileSize (haFD handle_)
1182 else ioException (IOError Nothing InappropriateType "hFileSize"
1183 "not a regular file" Nothing)
1186 -- | 'hSetFileSize' @hdl@ @size@ truncates the physical file with handle @hdl@ to @size@ bytes.
1188 hSetFileSize :: Handle -> Integer -> IO ()
1189 hSetFileSize handle size =
1190 withHandle_ "hSetFileSize" handle $ \ handle_ -> do
1191 case haType handle_ of
1192 ClosedHandle -> ioe_closedHandle
1193 SemiClosedHandle -> ioe_closedHandle
1194 _ -> do flushWriteBufferOnly handle_
1195 throwErrnoIf (/=0) "hSetFileSize"
1196 (c_ftruncate (haFD handle_) (fromIntegral size))
1199 -- ---------------------------------------------------------------------------
1200 -- Detecting the End of Input
1202 -- | For a readable handle @hdl@, 'hIsEOF' @hdl@ returns
1203 -- 'True' if no further input can be taken from @hdl@ or for a
1204 -- physical file, if the current I\/O position is equal to the length of
1205 -- the file. Otherwise, it returns 'False'.
1207 hIsEOF :: Handle -> IO Bool
1210 (do hLookAhead handle; return False)
1211 (\e -> if isEOFError e then return True else ioError e)
1213 -- | The computation 'isEOF' is identical to 'hIsEOF',
1214 -- except that it works only on 'stdin'.
1217 isEOF = hIsEOF stdin
1219 -- ---------------------------------------------------------------------------
1222 -- | Computation 'hLookAhead' returns the next character from the handle
1223 -- without removing it from the input buffer, blocking until a character
1226 -- This operation may fail with:
1228 -- * 'isEOFError' if the end of file has been reached.
1230 hLookAhead :: Handle -> IO Char
1231 hLookAhead handle = do
1232 wantReadableHandle "hLookAhead" handle $ \handle_ -> do
1233 let ref = haBuffer handle_
1235 is_line = haBufferMode handle_ == LineBuffering
1236 buf <- readIORef ref
1238 -- fill up the read buffer if necessary
1239 new_buf <- if bufferEmpty buf
1240 then fillReadBuffer fd True (haIsStream handle_) buf
1243 writeIORef ref new_buf
1245 (c,_) <- readCharFromBuffer (bufBuf buf) (bufRPtr buf)
1248 -- ---------------------------------------------------------------------------
1249 -- Buffering Operations
1251 -- Three kinds of buffering are supported: line-buffering,
1252 -- block-buffering or no-buffering. See GHC.IOBase for definition and
1253 -- further explanation of what the type represent.
1255 -- | Computation 'hSetBuffering' @hdl mode@ sets the mode of buffering for
1256 -- handle @hdl@ on subsequent reads and writes.
1258 -- If the buffer mode is changed from 'BlockBuffering' or
1259 -- 'LineBuffering' to 'NoBuffering', then
1261 -- * if @hdl@ is writable, the buffer is flushed as for 'hFlush';
1263 -- * if @hdl@ is not writable, the contents of the buffer is discarded.
1265 -- This operation may fail with:
1267 -- * 'isPermissionError' if the handle has already been used for reading
1268 -- or writing and the implementation does not allow the buffering mode
1271 hSetBuffering :: Handle -> BufferMode -> IO ()
1272 hSetBuffering handle mode =
1273 withAllHandles__ "hSetBuffering" handle $ \ handle_ -> do
1274 case haType handle_ of
1275 ClosedHandle -> ioe_closedHandle
1278 - we flush the old buffer regardless of whether
1279 the new buffer could fit the contents of the old buffer
1281 - allow a handle's buffering to change even if IO has
1282 occurred (ANSI C spec. does not allow this, nor did
1283 the previous implementation of IO.hSetBuffering).
1284 - a non-standard extension is to allow the buffering
1285 of semi-closed handles to change [sof 6/98]
1289 let state = initBufferState (haType handle_)
1292 -- we always have a 1-character read buffer for
1293 -- unbuffered handles: it's needed to
1294 -- support hLookAhead.
1295 NoBuffering -> allocateBuffer 1 ReadBuffer
1296 LineBuffering -> allocateBuffer dEFAULT_BUFFER_SIZE state
1297 BlockBuffering Nothing -> allocateBuffer dEFAULT_BUFFER_SIZE state
1298 BlockBuffering (Just n) | n <= 0 -> ioe_bufsiz n
1299 | otherwise -> allocateBuffer n state
1300 writeIORef (haBuffer handle_) new_buf
1302 -- for input terminals we need to put the terminal into
1303 -- cooked or raw mode depending on the type of buffering.
1304 is_tty <- fdIsTTY (haFD handle_)
1305 when (is_tty && isReadableHandleType (haType handle_)) $
1307 #ifndef mingw32_HOST_OS
1308 -- 'raw' mode under win32 is a bit too specialised (and troublesome
1309 -- for most common uses), so simply disable its use here.
1310 NoBuffering -> setCooked (haFD handle_) False
1312 NoBuffering -> return ()
1314 _ -> setCooked (haFD handle_) True
1316 -- throw away spare buffers, they might be the wrong size
1317 writeIORef (haBuffers handle_) BufferListNil
1319 return (handle_{ haBufferMode = mode })
1321 -- -----------------------------------------------------------------------------
1324 -- | The action 'hFlush' @hdl@ causes any items buffered for output
1325 -- in handle @hdl@ to be sent immediately to the operating system.
1327 -- This operation may fail with:
1329 -- * 'isFullError' if the device is full;
1331 -- * 'isPermissionError' if a system resource limit would be exceeded.
1332 -- It is unspecified whether the characters in the buffer are discarded
1333 -- or retained under these circumstances.
1335 hFlush :: Handle -> IO ()
1337 wantWritableHandle "hFlush" handle $ \ handle_ -> do
1338 buf <- readIORef (haBuffer handle_)
1339 if bufferIsWritable buf && not (bufferEmpty buf)
1340 then do flushed_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
1341 writeIORef (haBuffer handle_) flushed_buf
1345 -- -----------------------------------------------------------------------------
1346 -- Repositioning Handles
1348 data HandlePosn = HandlePosn Handle HandlePosition
1350 instance Eq HandlePosn where
1351 (HandlePosn h1 p1) == (HandlePosn h2 p2) = p1==p2 && h1==h2
1353 instance Show HandlePosn where
1354 showsPrec p (HandlePosn h pos) =
1355 showsPrec p h . showString " at position " . shows pos
1357 -- HandlePosition is the Haskell equivalent of POSIX' off_t.
1358 -- We represent it as an Integer on the Haskell side, but
1359 -- cheat slightly in that hGetPosn calls upon a C helper
1360 -- that reports the position back via (merely) an Int.
1361 type HandlePosition = Integer
1363 -- | Computation 'hGetPosn' @hdl@ returns the current I\/O position of
1364 -- @hdl@ as a value of the abstract type 'HandlePosn'.
1366 hGetPosn :: Handle -> IO HandlePosn
1367 hGetPosn handle = do
1368 posn <- hTell handle
1369 return (HandlePosn handle posn)
1371 -- | If a call to 'hGetPosn' @hdl@ returns a position @p@,
1372 -- then computation 'hSetPosn' @p@ sets the position of @hdl@
1373 -- to the position it held at the time of the call to 'hGetPosn'.
1375 -- This operation may fail with:
1377 -- * 'isPermissionError' if a system resource limit would be exceeded.
1379 hSetPosn :: HandlePosn -> IO ()
1380 hSetPosn (HandlePosn h i) = hSeek h AbsoluteSeek i
1382 -- ---------------------------------------------------------------------------
1385 -- | A mode that determines the effect of 'hSeek' @hdl mode i@, as follows:
1387 = AbsoluteSeek -- ^ the position of @hdl@ is set to @i@.
1388 | RelativeSeek -- ^ the position of @hdl@ is set to offset @i@
1389 -- from the current position.
1390 | SeekFromEnd -- ^ the position of @hdl@ is set to offset @i@
1391 -- from the end of the file.
1392 deriving (Eq, Ord, Ix, Enum, Read, Show)
1395 - when seeking using `SeekFromEnd', positive offsets (>=0) means
1396 seeking at or past EOF.
1398 - we possibly deviate from the report on the issue of seeking within
1399 the buffer and whether to flush it or not. The report isn't exactly
1403 -- | Computation 'hSeek' @hdl mode i@ sets the position of handle
1404 -- @hdl@ depending on @mode@.
1405 -- The offset @i@ is given in terms of 8-bit bytes.
1407 -- If @hdl@ is block- or line-buffered, then seeking to a position which is not
1408 -- in the current buffer will first cause any items in the output buffer to be
1409 -- written to the device, and then cause the input buffer to be discarded.
1410 -- Some handles may not be seekable (see 'hIsSeekable'), or only support a
1411 -- subset of the possible positioning operations (for instance, it may only
1412 -- be possible to seek to the end of a tape, or to a positive offset from
1413 -- the beginning or current position).
1414 -- It is not possible to set a negative I\/O position, or for
1415 -- a physical file, an I\/O position beyond the current end-of-file.
1417 -- This operation may fail with:
1419 -- * 'isPermissionError' if a system resource limit would be exceeded.
1421 hSeek :: Handle -> SeekMode -> Integer -> IO ()
1422 hSeek handle mode offset =
1423 wantSeekableHandle "hSeek" handle $ \ handle_ -> do
1425 puts ("hSeek " ++ show (mode,offset) ++ "\n")
1427 let ref = haBuffer handle_
1428 buf <- readIORef ref
1434 throwErrnoIfMinus1Retry_ "hSeek"
1435 (c_lseek (haFD handle_) (fromIntegral offset) whence)
1438 whence = case mode of
1439 AbsoluteSeek -> sEEK_SET
1440 RelativeSeek -> sEEK_CUR
1441 SeekFromEnd -> sEEK_END
1443 if bufferIsWritable buf
1444 then do new_buf <- flushWriteBuffer fd (haIsStream handle_) buf
1445 writeIORef ref new_buf
1449 if mode == RelativeSeek && offset >= 0 && offset < fromIntegral (w - r)
1450 then writeIORef ref buf{ bufRPtr = r + fromIntegral offset }
1453 new_buf <- flushReadBuffer (haFD handle_) buf
1454 writeIORef ref new_buf
1458 hTell :: Handle -> IO Integer
1460 wantSeekableHandle "hGetPosn" handle $ \ handle_ -> do
1462 #if defined(mingw32_HOST_OS)
1463 -- urgh, on Windows we have to worry about \n -> \r\n translation,
1464 -- so we can't easily calculate the file position using the
1465 -- current buffer size. Just flush instead.
1468 let fd = haFD handle_
1469 posn <- fromIntegral `liftM`
1470 throwErrnoIfMinus1Retry "hGetPosn"
1471 (c_lseek fd 0 sEEK_CUR)
1473 let ref = haBuffer handle_
1474 buf <- readIORef ref
1477 | bufferIsWritable buf = posn + fromIntegral (bufWPtr buf)
1478 | otherwise = posn - fromIntegral (bufWPtr buf - bufRPtr buf)
1480 puts ("\nhGetPosn: (fd, posn, real_posn) = " ++ show (fd, posn, real_posn) ++ "\n")
1481 puts (" (bufWPtr, bufRPtr) = " ++ show (bufWPtr buf, bufRPtr buf) ++ "\n")
1485 -- -----------------------------------------------------------------------------
1486 -- Handle Properties
1488 -- A number of operations return information about the properties of a
1489 -- handle. Each of these operations returns `True' if the handle has
1490 -- the specified property, and `False' otherwise.
1492 hIsOpen :: Handle -> IO Bool
1494 withHandle_ "hIsOpen" handle $ \ handle_ -> do
1495 case haType handle_ of
1496 ClosedHandle -> return False
1497 SemiClosedHandle -> return False
1500 hIsClosed :: Handle -> IO Bool
1502 withHandle_ "hIsClosed" handle $ \ handle_ -> do
1503 case haType handle_ of
1504 ClosedHandle -> return True
1507 {- not defined, nor exported, but mentioned
1508 here for documentation purposes:
1510 hSemiClosed :: Handle -> IO Bool
1514 return (not (ho || hc))
1517 hIsReadable :: Handle -> IO Bool
1518 hIsReadable (DuplexHandle _ _ _) = return True
1519 hIsReadable handle =
1520 withHandle_ "hIsReadable" handle $ \ handle_ -> do
1521 case haType handle_ of
1522 ClosedHandle -> ioe_closedHandle
1523 SemiClosedHandle -> ioe_closedHandle
1524 htype -> return (isReadableHandleType htype)
1526 hIsWritable :: Handle -> IO Bool
1527 hIsWritable (DuplexHandle _ _ _) = return True
1528 hIsWritable handle =
1529 withHandle_ "hIsWritable" handle $ \ handle_ -> do
1530 case haType handle_ of
1531 ClosedHandle -> ioe_closedHandle
1532 SemiClosedHandle -> ioe_closedHandle
1533 htype -> return (isWritableHandleType htype)
1535 -- | Computation 'hGetBuffering' @hdl@ returns the current buffering mode
1538 hGetBuffering :: Handle -> IO BufferMode
1539 hGetBuffering handle =
1540 withHandle_ "hGetBuffering" handle $ \ handle_ -> do
1541 case haType handle_ of
1542 ClosedHandle -> ioe_closedHandle
1544 -- We're being non-standard here, and allow the buffering
1545 -- of a semi-closed handle to be queried. -- sof 6/98
1546 return (haBufferMode handle_) -- could be stricter..
1548 hIsSeekable :: Handle -> IO Bool
1549 hIsSeekable handle =
1550 withHandle_ "hIsSeekable" handle $ \ handle_ -> do
1551 case haType handle_ of
1552 ClosedHandle -> ioe_closedHandle
1553 SemiClosedHandle -> ioe_closedHandle
1554 AppendHandle -> return False
1555 _ -> do t <- fdType (haFD handle_)
1556 return ((t == RegularFile || t == RawDevice)
1557 && (haIsBin handle_ || tEXT_MODE_SEEK_ALLOWED))
1559 -- -----------------------------------------------------------------------------
1560 -- Changing echo status (Non-standard GHC extensions)
1562 -- | Set the echoing status of a handle connected to a terminal.
1564 hSetEcho :: Handle -> Bool -> IO ()
1565 hSetEcho handle on = do
1566 isT <- hIsTerminalDevice handle
1570 withHandle_ "hSetEcho" handle $ \ handle_ -> do
1571 case haType handle_ of
1572 ClosedHandle -> ioe_closedHandle
1573 _ -> setEcho (haFD handle_) on
1575 -- | Get the echoing status of a handle connected to a terminal.
1577 hGetEcho :: Handle -> IO Bool
1578 hGetEcho handle = do
1579 isT <- hIsTerminalDevice handle
1583 withHandle_ "hGetEcho" handle $ \ handle_ -> do
1584 case haType handle_ of
1585 ClosedHandle -> ioe_closedHandle
1586 _ -> getEcho (haFD handle_)
1588 -- | Is the handle connected to a terminal?
1590 hIsTerminalDevice :: Handle -> IO Bool
1591 hIsTerminalDevice handle = do
1592 withHandle_ "hIsTerminalDevice" handle $ \ handle_ -> do
1593 case haType handle_ of
1594 ClosedHandle -> ioe_closedHandle
1595 _ -> fdIsTTY (haFD handle_)
1597 -- -----------------------------------------------------------------------------
1600 -- | Select binary mode ('True') or text mode ('False') on a open handle.
1601 -- (See also 'openBinaryFile'.)
1603 hSetBinaryMode :: Handle -> Bool -> IO ()
1604 hSetBinaryMode handle bin =
1605 withAllHandles__ "hSetBinaryMode" handle $ \ handle_ ->
1606 do throwErrnoIfMinus1_ "hSetBinaryMode"
1607 (setmode (haFD handle_) bin)
1608 return handle_{haIsBin=bin}
1610 foreign import ccall unsafe "__hscore_setmode"
1611 setmode :: CInt -> Bool -> IO CInt
1613 -- -----------------------------------------------------------------------------
1614 -- Duplicating a Handle
1616 -- | Returns a duplicate of the original handle, with its own buffer.
1617 -- The two Handles will share a file pointer, however. The original
1618 -- handle's buffer is flushed, including discarding any input data,
1619 -- before the handle is duplicated.
1621 hDuplicate :: Handle -> IO Handle
1622 hDuplicate h@(FileHandle path m) = do
1623 new_h_ <- withHandle' "hDuplicate" h m (dupHandle h Nothing)
1624 newFileHandle path (handleFinalizer path) new_h_
1625 hDuplicate h@(DuplexHandle path r w) = do
1626 new_w_ <- withHandle' "hDuplicate" h w (dupHandle h Nothing)
1627 new_w <- newMVar new_w_
1628 new_r_ <- withHandle' "hDuplicate" h r (dupHandle h (Just new_w))
1629 new_r <- newMVar new_r_
1630 addMVarFinalizer new_w (handleFinalizer path new_w)
1631 return (DuplexHandle path new_r new_w)
1633 dupHandle :: Handle -> Maybe (MVar Handle__) -> Handle__
1634 -> IO (Handle__, Handle__)
1635 dupHandle h other_side h_ = do
1636 -- flush the buffer first, so we don't have to copy its contents
1638 new_fd <- case other_side of
1639 Nothing -> throwErrnoIfMinus1 "dupHandle" $ c_dup (haFD h_)
1640 Just r -> withHandle_' "dupHandle" h r (return . haFD)
1641 dupHandle_ other_side h_ new_fd
1643 dupHandleTo other_side hto_ h_ = do
1645 -- Windows' dup2 does not return the new descriptor, unlike Unix
1646 throwErrnoIfMinus1 "dupHandleTo" $
1647 c_dup2 (haFD h_) (haFD hto_)
1648 dupHandle_ other_side h_ (haFD hto_)
1650 dupHandle_ :: Maybe (MVar Handle__) -> Handle__ -> FD
1651 -> IO (Handle__, Handle__)
1652 dupHandle_ other_side h_ new_fd = do
1653 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE (initBufferState (haType h_))
1654 ioref <- newIORef buffer
1655 ioref_buffers <- newIORef BufferListNil
1657 let new_handle_ = h_{ haFD = new_fd,
1659 haBuffers = ioref_buffers,
1660 haOtherSide = other_side }
1661 return (h_, new_handle_)
1663 -- -----------------------------------------------------------------------------
1664 -- Replacing a Handle
1667 Makes the second handle a duplicate of the first handle. The second
1668 handle will be closed first, if it is not already.
1670 This can be used to retarget the standard Handles, for example:
1672 > do h <- openFile "mystdout" WriteMode
1673 > hDuplicateTo h stdout
1676 hDuplicateTo :: Handle -> Handle -> IO ()
1677 hDuplicateTo h1@(FileHandle _ m1) h2@(FileHandle _ m2) = do
1678 withHandle__' "hDuplicateTo" h2 m2 $ \h2_ -> do
1679 _ <- hClose_help h2_
1680 withHandle' "hDuplicateTo" h1 m1 (dupHandleTo Nothing h2_)
1681 hDuplicateTo h1@(DuplexHandle _ r1 w1) h2@(DuplexHandle _ r2 w2) = do
1682 withHandle__' "hDuplicateTo" h2 w2 $ \w2_ -> do
1683 _ <- hClose_help w2_
1684 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo Nothing w2_)
1685 withHandle__' "hDuplicateTo" h2 r2 $ \r2_ -> do
1686 _ <- hClose_help r2_
1687 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo (Just w1) r2_)
1689 ioException (IOError (Just h1) IllegalOperation "hDuplicateTo"
1690 "handles are incompatible" Nothing)
1692 -- ---------------------------------------------------------------------------
1695 -- | 'hShow' is in the 'IO' monad, and gives more comprehensive output
1696 -- than the (pure) instance of 'Show' for 'Handle'.
1698 hShow :: Handle -> IO String
1699 hShow h@(FileHandle path _) = showHandle' path False h
1700 hShow h@(DuplexHandle path _ _) = showHandle' path True h
1702 showHandle' filepath is_duplex h =
1703 withHandle_ "showHandle" h $ \hdl_ ->
1705 showType | is_duplex = showString "duplex (read-write)"
1706 | otherwise = shows (haType hdl_)
1710 showHdl (haType hdl_)
1711 (showString "loc=" . showString filepath . showChar ',' .
1712 showString "type=" . showType . showChar ',' .
1713 showString "binary=" . shows (haIsBin hdl_) . showChar ',' .
1714 showString "buffering=" . showBufMode (unsafePerformIO (readIORef (haBuffer hdl_))) (haBufferMode hdl_) . showString "}" )
1718 showHdl :: HandleType -> ShowS -> ShowS
1721 ClosedHandle -> shows ht . showString "}"
1724 showBufMode :: Buffer -> BufferMode -> ShowS
1725 showBufMode buf bmo =
1727 NoBuffering -> showString "none"
1728 LineBuffering -> showString "line"
1729 BlockBuffering (Just n) -> showString "block " . showParen True (shows n)
1730 BlockBuffering Nothing -> showString "block " . showParen True (shows def)
1735 -- ---------------------------------------------------------------------------
1738 #if defined(DEBUG_DUMP)
1739 puts :: String -> IO ()
1740 puts s = do write_rawBuffer 1 (unsafeCoerce# (packCString# s)) 0 (fromIntegral (length s))
1744 -- -----------------------------------------------------------------------------
1747 throwErrnoIfMinus1RetryOnBlock :: String -> IO CInt -> IO CInt -> IO CInt
1748 throwErrnoIfMinus1RetryOnBlock loc f on_block =
1751 if (res :: CInt) == -1
1755 then throwErrnoIfMinus1RetryOnBlock loc f on_block
1756 else if err == eWOULDBLOCK || err == eAGAIN
1761 -- -----------------------------------------------------------------------------
1762 -- wrappers to platform-specific constants:
1764 foreign import ccall unsafe "__hscore_supportsTextMode"
1765 tEXT_MODE_SEEK_ALLOWED :: Bool
1767 foreign import ccall unsafe "__hscore_bufsiz" dEFAULT_BUFFER_SIZE :: Int
1768 foreign import ccall unsafe "__hscore_seek_cur" sEEK_CUR :: CInt
1769 foreign import ccall unsafe "__hscore_seek_set" sEEK_SET :: CInt
1770 foreign import ccall unsafe "__hscore_seek_end" sEEK_END :: CInt