1 {-# OPTIONS_GHC -XNoImplicitPrelude -#include "HsBase.h" #-}
2 {-# OPTIONS_GHC -fno-warn-unused-matches #-}
3 {-# OPTIONS_GHC -fno-warn-unused-binds #-}
4 {-# OPTIONS_HADDOCK hide #-}
9 -----------------------------------------------------------------------------
11 -- Module : GHC.Handle
12 -- Copyright : (c) The University of Glasgow, 1994-2001
13 -- License : see libraries/base/LICENSE
15 -- Maintainer : libraries@haskell.org
16 -- Stability : internal
17 -- Portability : non-portable
19 -- This module defines the basic operations on I\/O \"handles\".
21 -----------------------------------------------------------------------------
25 withHandle, withHandle', withHandle_,
26 wantWritableHandle, wantReadableHandle, wantSeekableHandle,
28 newEmptyBuffer, allocateBuffer, readCharFromBuffer, writeCharIntoBuffer,
29 flushWriteBufferOnly, flushWriteBuffer, flushReadBuffer,
30 fillReadBuffer, fillReadBufferWithoutBlocking,
31 readRawBuffer, readRawBufferPtr,
32 readRawBufferNoBlock, readRawBufferPtrNoBlock,
33 writeRawBuffer, writeRawBufferPtr,
35 #ifndef mingw32_HOST_OS
39 ioe_closedHandle, ioe_EOF, ioe_notReadable, ioe_notWritable,
41 stdin, stdout, stderr,
42 IOMode(..), openFile, openBinaryFile, fdToHandle_stat, fdToHandle, fdToHandle',
43 hFileSize, hSetFileSize, hIsEOF, isEOF, hLookAhead, hLookAhead', hSetBuffering, hSetBinaryMode,
44 hFlush, hDuplicate, hDuplicateTo,
48 HandlePosition, HandlePosn(..), hGetPosn, hSetPosn,
49 SeekMode(..), hSeek, hTell,
51 hIsOpen, hIsClosed, hIsReadable, hIsWritable, hGetBuffering, hIsSeekable,
52 hSetEcho, hGetEcho, hIsTerminalDevice,
66 import System.IO.Error
67 import System.Posix.Internals
68 import System.Posix.Types
74 import GHC.Read ( Read )
79 import GHC.Num ( Integer, Num(..) )
81 #if defined(DEBUG_DUMP)
87 -- -----------------------------------------------------------------------------
90 -- hWaitForInput blocks (should use a timeout)
92 -- unbuffered hGetLine is a bit dodgy
94 -- hSetBuffering: can't change buffering on a stream,
95 -- when the read buffer is non-empty? (no way to flush the buffer)
97 -- ---------------------------------------------------------------------------
98 -- Are files opened by default in text or binary mode, if the user doesn't
101 dEFAULT_OPEN_IN_BINARY_MODE :: Bool
102 dEFAULT_OPEN_IN_BINARY_MODE = False
104 -- ---------------------------------------------------------------------------
105 -- Creating a new handle
107 newFileHandle :: FilePath -> (MVar Handle__ -> IO ()) -> Handle__ -> IO Handle
108 newFileHandle filepath finalizer hc = do
110 addMVarFinalizer m (finalizer m)
111 return (FileHandle filepath m)
113 -- ---------------------------------------------------------------------------
114 -- Working with Handles
117 In the concurrent world, handles are locked during use. This is done
118 by wrapping an MVar around the handle which acts as a mutex over
119 operations on the handle.
121 To avoid races, we use the following bracketing operations. The idea
122 is to obtain the lock, do some operation and replace the lock again,
123 whether the operation succeeded or failed. We also want to handle the
124 case where the thread receives an exception while processing the IO
125 operation: in these cases we also want to relinquish the lock.
127 There are three versions of @withHandle@: corresponding to the three
128 possible combinations of:
130 - the operation may side-effect the handle
131 - the operation may return a result
133 If the operation generates an error or an exception is raised, the
134 original handle is always replaced [ this is the case at the moment,
135 but we might want to revisit this in the future --SDM ].
138 {-# INLINE withHandle #-}
139 withHandle :: String -> Handle -> (Handle__ -> IO (Handle__,a)) -> IO a
140 withHandle fun h@(FileHandle _ m) act = withHandle' fun h m act
141 withHandle fun h@(DuplexHandle _ m _) act = withHandle' fun h m act
143 withHandle' :: String -> Handle -> MVar Handle__
144 -> (Handle__ -> IO (Handle__,a)) -> IO a
145 withHandle' fun h m act =
148 checkBufferInvariants h_
149 (h',v) <- (act h_ `catchAny` \err -> putMVar m h_ >> throw err)
150 `catchException` \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 <- (act h_ `catchAny` \err -> putMVar m h_ >> throw err)
166 `catchException` \ex -> ioError (augmentIOError ex fun h)
167 checkBufferInvariants h_
171 withAllHandles__ :: String -> Handle -> (Handle__ -> IO Handle__) -> IO ()
172 withAllHandles__ fun h@(FileHandle _ m) act = withHandle__' fun h m act
173 withAllHandles__ fun h@(DuplexHandle _ r w) act = do
174 withHandle__' fun h r act
175 withHandle__' fun h w act
177 withHandle__' :: String -> Handle -> MVar Handle__ -> (Handle__ -> IO Handle__)
179 withHandle__' fun h m act =
182 checkBufferInvariants h_
183 h' <- (act h_ `catchAny` \err -> putMVar m h_ >> throw err)
184 `catchException` \ex -> ioError (augmentIOError ex fun h)
185 checkBufferInvariants h'
189 augmentIOError :: IOException -> String -> Handle -> IOException
190 augmentIOError (IOError _ iot _ str fp) fun h
191 = IOError (Just h) iot fun str filepath
194 | otherwise = case h of
195 FileHandle path _ -> Just path
196 DuplexHandle path _ _ -> Just path
198 -- ---------------------------------------------------------------------------
199 -- Wrapper for write operations.
201 wantWritableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
202 wantWritableHandle fun h@(FileHandle _ m) act
203 = wantWritableHandle' fun h m act
204 wantWritableHandle fun h@(DuplexHandle _ _ m) act
205 = wantWritableHandle' fun h m act
206 -- ToDo: in the Duplex case, we don't need to checkWritableHandle
209 :: String -> Handle -> MVar Handle__
210 -> (Handle__ -> IO a) -> IO a
211 wantWritableHandle' fun h m act
212 = withHandle_' fun h m (checkWritableHandle act)
214 checkWritableHandle :: (Handle__ -> IO a) -> Handle__ -> IO a
215 checkWritableHandle act handle_
216 = case haType handle_ of
217 ClosedHandle -> ioe_closedHandle
218 SemiClosedHandle -> ioe_closedHandle
219 ReadHandle -> ioe_notWritable
220 ReadWriteHandle -> do
221 let ref = haBuffer handle_
224 if not (bufferIsWritable buf)
225 then do b <- flushReadBuffer (haFD handle_) buf
226 return b{ bufState=WriteBuffer }
228 writeIORef ref new_buf
230 _other -> act handle_
232 -- ---------------------------------------------------------------------------
233 -- Wrapper for read operations.
235 wantReadableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
236 wantReadableHandle fun h@(FileHandle _ m) act
237 = wantReadableHandle' fun h m act
238 wantReadableHandle fun h@(DuplexHandle _ m _) act
239 = wantReadableHandle' fun h m act
240 -- ToDo: in the Duplex case, we don't need to checkReadableHandle
243 :: String -> Handle -> MVar Handle__
244 -> (Handle__ -> IO a) -> IO a
245 wantReadableHandle' fun h m act
246 = withHandle_' fun h m (checkReadableHandle act)
248 checkReadableHandle :: (Handle__ -> IO a) -> Handle__ -> IO a
249 checkReadableHandle act handle_ =
250 case haType handle_ of
251 ClosedHandle -> ioe_closedHandle
252 SemiClosedHandle -> ioe_closedHandle
253 AppendHandle -> ioe_notReadable
254 WriteHandle -> ioe_notReadable
255 ReadWriteHandle -> do
256 let ref = haBuffer handle_
258 when (bufferIsWritable buf) $ do
259 new_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
260 writeIORef ref new_buf{ bufState=ReadBuffer }
262 _other -> act handle_
264 -- ---------------------------------------------------------------------------
265 -- Wrapper for seek operations.
267 wantSeekableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
268 wantSeekableHandle fun h@(DuplexHandle _ _ _) _act =
269 ioException (IOError (Just h) IllegalOperation fun
270 "handle is not seekable" Nothing)
271 wantSeekableHandle fun h@(FileHandle _ m) act =
272 withHandle_' fun h m (checkSeekableHandle act)
274 checkSeekableHandle :: (Handle__ -> IO a) -> Handle__ -> IO a
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 :: FilePath -> Handle__
310 ioe_finalizedHandle fp = throw
311 (IOError Nothing IllegalOperation ""
312 "handle is finalized" (Just fp))
314 ioe_bufsiz :: Int -> IO a
315 ioe_bufsiz n = ioException
316 (IOError Nothing InvalidArgument "hSetBuffering"
317 ("illegal buffer size " ++ showsPrec 9 n []) Nothing)
318 -- 9 => should be parens'ified.
320 -- -----------------------------------------------------------------------------
323 -- For a duplex handle, we arrange that the read side points to the write side
324 -- (and hence keeps it alive if the read side is alive). This is done by
325 -- having the haOtherSide field of the read side point to the read side.
326 -- The finalizer is then placed on the write side, and the handle only gets
327 -- finalized once, when both sides are no longer required.
329 -- NOTE about finalized handles: It's possible that a handle can be
330 -- finalized and then we try to use it later, for example if the
331 -- handle is referenced from another finalizer, or from a thread that
332 -- has become unreferenced and then resurrected (arguably in the
333 -- latter case we shouldn't finalize the Handle...). Anyway,
334 -- we try to emit a helpful message which is better than nothing.
336 stdHandleFinalizer :: FilePath -> MVar Handle__ -> IO ()
337 stdHandleFinalizer fp m = do
339 flushWriteBufferOnly h_
340 putMVar m (ioe_finalizedHandle fp)
342 handleFinalizer :: FilePath -> MVar Handle__ -> IO ()
343 handleFinalizer fp m = do
344 handle_ <- takeMVar m
345 case haType handle_ of
346 ClosedHandle -> return ()
347 _ -> do flushWriteBufferOnly handle_ `catchAny` \_ -> return ()
348 -- ignore errors and async exceptions, and close the
349 -- descriptor anyway...
350 hClose_handle_ handle_
352 putMVar m (ioe_finalizedHandle fp)
354 -- ---------------------------------------------------------------------------
355 -- Grimy buffer operations
357 checkBufferInvariants :: Handle__ -> IO ()
359 checkBufferInvariants h_ = do
360 let ref = haBuffer h_
361 Buffer{ bufWPtr=w, bufRPtr=r, bufSize=size, bufState=state } <- readIORef ref
366 && ( r /= w || (r == 0 && w == 0) )
367 && ( state /= WriteBuffer || r == 0 )
368 && ( state /= WriteBuffer || w < size ) -- write buffer is never full
370 then error "buffer invariant violation"
373 checkBufferInvariants _ = return ()
376 newEmptyBuffer :: RawBuffer -> BufferState -> Int -> Buffer
377 newEmptyBuffer b state size
378 = Buffer{ bufBuf=b, bufRPtr=0, bufWPtr=0, bufSize=size, bufState=state }
380 allocateBuffer :: Int -> BufferState -> IO Buffer
381 allocateBuffer sz@(I# size) state = IO $ \s ->
382 -- We sometimes need to pass the address of this buffer to
383 -- a "safe" foreign call, hence it must be immovable.
384 case newPinnedByteArray# size s of { (# s', b #) ->
385 (# s', newEmptyBuffer b state sz #) }
387 writeCharIntoBuffer :: RawBuffer -> Int -> Char -> IO Int
388 writeCharIntoBuffer slab (I# off) (C# c)
389 = IO $ \s -> case writeCharArray# slab off c s of
390 s' -> (# s', I# (off +# 1#) #)
392 readCharFromBuffer :: RawBuffer -> Int -> IO (Char, Int)
393 readCharFromBuffer slab (I# off)
394 = IO $ \s -> case readCharArray# slab off s of
395 (# s', c #) -> (# s', (C# c, I# (off +# 1#)) #)
397 getBuffer :: FD -> BufferState -> IO (IORef Buffer, BufferMode)
398 getBuffer fd state = do
399 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE state
400 ioref <- newIORef buffer
404 | is_tty = LineBuffering
405 | otherwise = BlockBuffering Nothing
407 return (ioref, buffer_mode)
409 mkUnBuffer :: IO (IORef Buffer)
411 buffer <- allocateBuffer 1 ReadBuffer
414 -- flushWriteBufferOnly flushes the buffer iff it contains pending write data.
415 flushWriteBufferOnly :: Handle__ -> IO ()
416 flushWriteBufferOnly h_ = do
420 new_buf <- if bufferIsWritable buf
421 then flushWriteBuffer fd (haIsStream h_) buf
423 writeIORef ref new_buf
425 -- flushBuffer syncs the file with the buffer, including moving the
426 -- file pointer backwards in the case of a read buffer.
427 flushBuffer :: Handle__ -> IO ()
429 let ref = haBuffer h_
434 ReadBuffer -> flushReadBuffer (haFD h_) buf
435 WriteBuffer -> flushWriteBuffer (haFD h_) (haIsStream h_) buf
437 writeIORef ref flushed_buf
439 -- When flushing a read buffer, we seek backwards by the number of
440 -- characters in the buffer. The file descriptor must therefore be
441 -- seekable: attempting to flush the read buffer on an unseekable
442 -- handle is not allowed.
444 flushReadBuffer :: FD -> Buffer -> IO Buffer
445 flushReadBuffer fd buf
446 | bufferEmpty buf = return buf
448 let off = negate (bufWPtr buf - bufRPtr buf)
450 puts ("flushReadBuffer: new file offset = " ++ show off ++ "\n")
452 throwErrnoIfMinus1Retry "flushReadBuffer"
453 (c_lseek fd (fromIntegral off) sEEK_CUR)
454 return buf{ bufWPtr=0, bufRPtr=0 }
456 flushWriteBuffer :: FD -> Bool -> Buffer -> IO Buffer
457 flushWriteBuffer fd is_stream buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w } =
458 seq fd $ do -- strictness hack
461 puts ("flushWriteBuffer, fd=" ++ show fd ++ ", bytes=" ++ show bytes ++ "\n")
464 then return (buf{ bufRPtr=0, bufWPtr=0 })
466 res <- writeRawBuffer "flushWriteBuffer" fd is_stream b
467 (fromIntegral r) (fromIntegral bytes)
468 let res' = fromIntegral res
470 then flushWriteBuffer fd is_stream (buf{ bufRPtr = r + res' })
471 else return buf{ bufRPtr=0, bufWPtr=0 }
473 fillReadBuffer :: FD -> Bool -> Bool -> Buffer -> IO Buffer
474 fillReadBuffer fd is_line is_stream
475 buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w, bufSize=size } =
476 -- buffer better be empty:
477 assert (r == 0 && w == 0) $ do
478 fillReadBufferLoop fd is_line is_stream buf b w size
480 -- For a line buffer, we just get the first chunk of data to arrive,
481 -- and don't wait for the whole buffer to be full (but we *do* wait
482 -- until some data arrives). This isn't really line buffering, but it
483 -- appears to be what GHC has done for a long time, and I suspect it
484 -- is more useful than line buffering in most cases.
486 fillReadBufferLoop :: FD -> Bool -> Bool -> Buffer -> RawBuffer -> Int -> Int
488 fillReadBufferLoop fd is_line is_stream buf b w size = do
490 if bytes == 0 -- buffer full?
491 then return buf{ bufRPtr=0, bufWPtr=w }
494 puts ("fillReadBufferLoop: bytes = " ++ show bytes ++ "\n")
496 res <- readRawBuffer "fillReadBuffer" fd is_stream b
497 (fromIntegral w) (fromIntegral bytes)
498 let res' = fromIntegral res
500 puts ("fillReadBufferLoop: res' = " ++ show res' ++ "\n")
505 else return buf{ bufRPtr=0, bufWPtr=w }
506 else if res' < bytes && not is_line
507 then fillReadBufferLoop fd is_line is_stream buf b (w+res') size
508 else return buf{ bufRPtr=0, bufWPtr=w+res' }
511 fillReadBufferWithoutBlocking :: FD -> Bool -> Buffer -> IO Buffer
512 fillReadBufferWithoutBlocking fd is_stream
513 buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w, bufSize=size } =
514 -- buffer better be empty:
515 assert (r == 0 && w == 0) $ do
517 puts ("fillReadBufferLoopNoBlock: bytes = " ++ show size ++ "\n")
519 res <- readRawBufferNoBlock "fillReadBuffer" fd is_stream b
520 0 (fromIntegral size)
521 let res' = fromIntegral res
523 puts ("fillReadBufferLoopNoBlock: res' = " ++ show res' ++ "\n")
525 return buf{ bufRPtr=0, bufWPtr=res' }
527 -- Low level routines for reading/writing to (raw)buffers:
529 #ifndef mingw32_HOST_OS
534 Unix has broken semantics when it comes to non-blocking I/O: you can
535 set the O_NONBLOCK flag on an FD, but it applies to the all other FDs
536 attached to the same underlying file, pipe or TTY; there's no way to
537 have private non-blocking behaviour for an FD. See bug #724.
539 We fix this by only setting O_NONBLOCK on FDs that we create; FDs that
540 come from external sources or are exposed externally are left in
541 blocking mode. This solution has some problems though. We can't
542 completely simulate a non-blocking read without O_NONBLOCK: several
543 cases are wrong here. The cases that are wrong:
545 * reading/writing to a blocking FD in non-threaded mode.
546 In threaded mode, we just make a safe call to read().
547 In non-threaded mode we call select() before attempting to read,
548 but that leaves a small race window where the data can be read
549 from the file descriptor before we issue our blocking read().
550 * readRawBufferNoBlock for a blocking FD
554 In the threaded RTS we could just make safe calls to read()/write()
555 for file descriptors in blocking mode without worrying about blocking
556 other threads, but the problem with this is that the thread will be
557 uninterruptible while it is blocked in the foreign call. See #2363.
558 So now we always call fdReady() before reading, and if fdReady
559 indicates that there's no data, we call threadWaitRead.
563 readRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
564 readRawBuffer loc fd is_nonblock buf off len
565 | is_nonblock = unsafe_read -- unsafe is ok, it can't block
566 | otherwise = do r <- throwErrnoIfMinus1 loc
567 (unsafe_fdReady (fromIntegral fd) 0 0 0)
570 else do threadWaitRead (fromIntegral fd); read
572 do_read call = throwErrnoIfMinus1RetryMayBlock loc call
573 (threadWaitRead (fromIntegral fd))
574 read = if threaded then safe_read else unsafe_read
575 unsafe_read = do_read (read_rawBuffer fd buf off len)
576 safe_read = do_read (safe_read_rawBuffer fd buf off len)
578 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
579 readRawBufferPtr loc fd is_nonblock buf off len
580 | is_nonblock = unsafe_read -- unsafe is ok, it can't block
581 | otherwise = do r <- throwErrnoIfMinus1 loc
582 (unsafe_fdReady (fromIntegral fd) 0 0 0)
585 else do threadWaitRead (fromIntegral fd); read
587 do_read call = throwErrnoIfMinus1RetryMayBlock loc call
588 (threadWaitRead (fromIntegral fd))
589 read = if threaded then safe_read else unsafe_read
590 unsafe_read = do_read (read_off fd buf off len)
591 safe_read = do_read (safe_read_off fd buf off len)
593 readRawBufferNoBlock :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
594 readRawBufferNoBlock loc fd is_nonblock buf off len
595 | is_nonblock = unsafe_read -- unsafe is ok, it can't block
596 | otherwise = do r <- unsafe_fdReady (fromIntegral fd) 0 0 0
597 if r /= 0 then safe_read
599 -- XXX see note [nonblock]
601 do_read call = throwErrnoIfMinus1RetryOnBlock loc call (return 0)
602 unsafe_read = do_read (read_rawBuffer fd buf off len)
603 safe_read = do_read (safe_read_rawBuffer fd buf off len)
605 readRawBufferPtrNoBlock :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
606 readRawBufferPtrNoBlock loc fd is_nonblock buf off len
607 | is_nonblock = unsafe_read -- unsafe is ok, it can't block
608 | otherwise = do r <- unsafe_fdReady (fromIntegral fd) 0 0 0
609 if r /= 0 then safe_read
611 -- XXX see note [nonblock]
613 do_read call = throwErrnoIfMinus1RetryOnBlock loc call (return 0)
614 unsafe_read = do_read (read_off fd buf off len)
615 safe_read = do_read (safe_read_off fd buf off len)
617 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
618 writeRawBuffer loc fd is_nonblock buf off len
619 | is_nonblock = unsafe_write -- unsafe is ok, it can't block
620 | otherwise = do r <- unsafe_fdReady (fromIntegral fd) 1 0 0
623 else do threadWaitWrite (fromIntegral fd); write
625 do_write call = throwErrnoIfMinus1RetryMayBlock loc call
626 (threadWaitWrite (fromIntegral fd))
627 write = if threaded then safe_write else unsafe_write
628 unsafe_write = do_write (write_rawBuffer fd buf off len)
629 safe_write = do_write (safe_write_rawBuffer (fromIntegral fd) buf off len)
631 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
632 writeRawBufferPtr loc fd is_nonblock buf off len
633 | is_nonblock = unsafe_write -- unsafe is ok, it can't block
634 | otherwise = do r <- unsafe_fdReady (fromIntegral fd) 1 0 0
637 else do threadWaitWrite (fromIntegral fd); write
639 do_write call = throwErrnoIfMinus1RetryMayBlock loc call
640 (threadWaitWrite (fromIntegral fd))
641 write = if threaded then safe_write else unsafe_write
642 unsafe_write = do_write (write_off fd buf off len)
643 safe_write = do_write (safe_write_off (fromIntegral fd) buf off len)
645 foreign import ccall unsafe "__hscore_PrelHandle_read"
646 read_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
648 foreign import ccall unsafe "__hscore_PrelHandle_read"
649 read_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
651 foreign import ccall unsafe "__hscore_PrelHandle_write"
652 write_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
654 foreign import ccall unsafe "__hscore_PrelHandle_write"
655 write_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
657 foreign import ccall unsafe "fdReady"
658 unsafe_fdReady :: CInt -> CInt -> CInt -> CInt -> IO CInt
660 #else /* mingw32_HOST_OS.... */
662 readRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
663 readRawBuffer loc fd is_stream buf off len
664 | threaded = blockingReadRawBuffer loc fd is_stream buf off len
665 | otherwise = asyncReadRawBuffer loc fd is_stream buf off len
667 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
668 readRawBufferPtr loc fd is_stream buf off len
669 | threaded = blockingReadRawBufferPtr loc fd is_stream buf off len
670 | otherwise = asyncReadRawBufferPtr loc fd is_stream buf off len
672 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
673 writeRawBuffer loc fd is_stream buf off len
674 | threaded = blockingWriteRawBuffer loc fd is_stream buf off len
675 | otherwise = asyncWriteRawBuffer loc fd is_stream buf off len
677 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
678 writeRawBufferPtr loc fd is_stream buf off len
679 | threaded = blockingWriteRawBufferPtr loc fd is_stream buf off len
680 | otherwise = asyncWriteRawBufferPtr loc fd is_stream buf off len
682 -- ToDo: we don't have a non-blocking primitve read on Win32
683 readRawBufferNoBlock :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
684 readRawBufferNoBlock = readRawBuffer
686 readRawBufferPtrNoBlock :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
687 readRawBufferPtrNoBlock = readRawBufferPtr
688 -- Async versions of the read/write primitives, for the non-threaded RTS
690 asyncReadRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt
692 asyncReadRawBuffer loc fd is_stream buf off len = do
693 (l, rc) <- asyncReadBA (fromIntegral fd) (if is_stream then 1 else 0)
694 (fromIntegral len) off buf
697 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
698 else return (fromIntegral l)
700 asyncReadRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt
702 asyncReadRawBufferPtr loc fd is_stream buf off len = do
703 (l, rc) <- asyncRead (fromIntegral fd) (if is_stream then 1 else 0)
704 (fromIntegral len) (buf `plusPtr` off)
707 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
708 else return (fromIntegral l)
710 asyncWriteRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt
712 asyncWriteRawBuffer loc fd is_stream buf off len = do
713 (l, rc) <- asyncWriteBA (fromIntegral fd) (if is_stream then 1 else 0)
714 (fromIntegral len) off buf
717 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
718 else return (fromIntegral l)
720 asyncWriteRawBufferPtr :: String -> FD -> Bool -> CString -> Int -> CInt
722 asyncWriteRawBufferPtr loc fd is_stream buf off len = do
723 (l, rc) <- asyncWrite (fromIntegral fd) (if is_stream then 1 else 0)
724 (fromIntegral len) (buf `plusPtr` off)
727 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
728 else return (fromIntegral l)
730 -- Blocking versions of the read/write primitives, for the threaded RTS
732 blockingReadRawBuffer :: String -> CInt -> Bool -> RawBuffer -> Int -> CInt
734 blockingReadRawBuffer loc fd True buf off len =
735 throwErrnoIfMinus1Retry loc $
736 safe_recv_rawBuffer fd buf off len
737 blockingReadRawBuffer loc fd False buf off len =
738 throwErrnoIfMinus1Retry loc $
739 safe_read_rawBuffer fd buf off len
741 blockingReadRawBufferPtr :: String -> CInt -> Bool -> CString -> Int -> CInt
743 blockingReadRawBufferPtr loc fd True buf off len =
744 throwErrnoIfMinus1Retry loc $
745 safe_recv_off fd buf off len
746 blockingReadRawBufferPtr loc fd False buf off len =
747 throwErrnoIfMinus1Retry loc $
748 safe_read_off fd buf off len
750 blockingWriteRawBuffer :: String -> CInt -> Bool -> RawBuffer -> Int -> CInt
752 blockingWriteRawBuffer loc fd True buf off len =
753 throwErrnoIfMinus1Retry loc $
754 safe_send_rawBuffer fd buf off len
755 blockingWriteRawBuffer loc fd False buf off len =
756 throwErrnoIfMinus1Retry loc $
757 safe_write_rawBuffer fd buf off len
759 blockingWriteRawBufferPtr :: String -> CInt -> Bool -> CString -> Int -> CInt
761 blockingWriteRawBufferPtr loc fd True buf off len =
762 throwErrnoIfMinus1Retry loc $
763 safe_send_off fd buf off len
764 blockingWriteRawBufferPtr loc fd False buf off len =
765 throwErrnoIfMinus1Retry loc $
766 safe_write_off fd buf off len
768 -- NOTE: "safe" versions of the read/write calls for use by the threaded RTS.
769 -- These calls may block, but that's ok.
771 foreign import ccall safe "__hscore_PrelHandle_recv"
772 safe_recv_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
774 foreign import ccall safe "__hscore_PrelHandle_recv"
775 safe_recv_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
777 foreign import ccall safe "__hscore_PrelHandle_send"
778 safe_send_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
780 foreign import ccall safe "__hscore_PrelHandle_send"
781 safe_send_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
785 foreign import ccall "rtsSupportsBoundThreads" threaded :: Bool
787 foreign import ccall safe "__hscore_PrelHandle_read"
788 safe_read_rawBuffer :: FD -> RawBuffer -> Int -> CInt -> IO CInt
790 foreign import ccall safe "__hscore_PrelHandle_read"
791 safe_read_off :: FD -> Ptr CChar -> Int -> CInt -> IO CInt
793 foreign import ccall safe "__hscore_PrelHandle_write"
794 safe_write_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
796 foreign import ccall safe "__hscore_PrelHandle_write"
797 safe_write_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
799 -- ---------------------------------------------------------------------------
802 -- Three handles are allocated during program initialisation. The first
803 -- two manage input or output from the Haskell program's standard input
804 -- or output channel respectively. The third manages output to the
805 -- standard error channel. These handles are initially open.
807 fd_stdin, fd_stdout, fd_stderr :: FD
812 -- | A handle managing input from the Haskell program's standard input channel.
814 stdin = unsafePerformIO $ do
815 -- ToDo: acquire lock
816 -- We don't set non-blocking mode on standard handles, because it may
817 -- confuse other applications attached to the same TTY/pipe
818 -- see Note [nonblock]
819 (buf, bmode) <- getBuffer fd_stdin ReadBuffer
820 mkStdHandle fd_stdin "<stdin>" ReadHandle buf bmode
822 -- | A handle managing output to the Haskell program's standard output channel.
824 stdout = unsafePerformIO $ do
825 -- ToDo: acquire lock
826 -- We don't set non-blocking mode on standard handles, because it may
827 -- confuse other applications attached to the same TTY/pipe
828 -- see Note [nonblock]
829 (buf, bmode) <- getBuffer fd_stdout WriteBuffer
830 mkStdHandle fd_stdout "<stdout>" WriteHandle buf bmode
832 -- | A handle managing output to the Haskell program's standard error channel.
834 stderr = unsafePerformIO $ do
835 -- ToDo: acquire lock
836 -- We don't set non-blocking mode on standard handles, because it may
837 -- confuse other applications attached to the same TTY/pipe
838 -- see Note [nonblock]
840 mkStdHandle fd_stderr "<stderr>" WriteHandle buf NoBuffering
842 -- ---------------------------------------------------------------------------
843 -- Opening and Closing Files
845 addFilePathToIOError :: String -> FilePath -> IOException -> IOException
846 addFilePathToIOError fun fp (IOError h iot _ str _)
847 = IOError h iot fun str (Just fp)
849 -- | Computation 'openFile' @file mode@ allocates and returns a new, open
850 -- handle to manage the file @file@. It manages input if @mode@
851 -- is 'ReadMode', output if @mode@ is 'WriteMode' or 'AppendMode',
852 -- and both input and output if mode is 'ReadWriteMode'.
854 -- If the file does not exist and it is opened for output, it should be
855 -- created as a new file. If @mode@ is 'WriteMode' and the file
856 -- already exists, then it should be truncated to zero length.
857 -- Some operating systems delete empty files, so there is no guarantee
858 -- that the file will exist following an 'openFile' with @mode@
859 -- 'WriteMode' unless it is subsequently written to successfully.
860 -- The handle is positioned at the end of the file if @mode@ is
861 -- 'AppendMode', and otherwise at the beginning (in which case its
862 -- internal position is 0).
863 -- The initial buffer mode is implementation-dependent.
865 -- This operation may fail with:
867 -- * 'isAlreadyInUseError' if the file is already open and cannot be reopened;
869 -- * 'isDoesNotExistError' if the file does not exist; or
871 -- * 'isPermissionError' if the user does not have permission to open the file.
873 -- Note: if you will be working with files containing binary data, you'll want to
874 -- be using 'openBinaryFile'.
875 openFile :: FilePath -> IOMode -> IO Handle
878 (openFile' fp im dEFAULT_OPEN_IN_BINARY_MODE)
879 (\e -> ioError (addFilePathToIOError "openFile" fp e))
881 -- | Like 'openFile', but open the file in binary mode.
882 -- On Windows, reading a file in text mode (which is the default)
883 -- will translate CRLF to LF, and writing will translate LF to CRLF.
884 -- This is usually what you want with text files. With binary files
885 -- this is undesirable; also, as usual under Microsoft operating systems,
886 -- text mode treats control-Z as EOF. Binary mode turns off all special
887 -- treatment of end-of-line and end-of-file characters.
888 -- (See also 'hSetBinaryMode'.)
890 openBinaryFile :: FilePath -> IOMode -> IO Handle
891 openBinaryFile fp m =
893 (openFile' fp m True)
894 (\e -> ioError (addFilePathToIOError "openBinaryFile" fp e))
896 openFile' :: String -> IOMode -> Bool -> IO Handle
897 openFile' filepath mode binary =
898 withCString filepath $ \ f ->
901 oflags1 = case mode of
902 ReadMode -> read_flags
903 #ifdef mingw32_HOST_OS
904 WriteMode -> write_flags .|. o_TRUNC
906 WriteMode -> write_flags
908 ReadWriteMode -> rw_flags
909 AppendMode -> append_flags
915 oflags = oflags1 .|. binary_flags
918 -- the old implementation had a complicated series of three opens,
919 -- which is perhaps because we have to be careful not to open
920 -- directories. However, the man pages I've read say that open()
921 -- always returns EISDIR if the file is a directory and was opened
922 -- for writing, so I think we're ok with a single open() here...
923 fd <- throwErrnoIfMinus1Retry "openFile"
924 (c_open f (fromIntegral oflags) 0o666)
926 stat@(fd_type,_,_) <- fdStat fd
928 h <- fdToHandle_stat fd (Just stat) False filepath mode binary
929 `catchAny` \e -> do c_close fd; throw e
930 -- NB. don't forget to close the FD if fdToHandle' fails, otherwise
932 -- ASSERT: if we just created the file, then fdToHandle' won't fail
933 -- (so we don't need to worry about removing the newly created file
934 -- in the event of an error).
936 #ifndef mingw32_HOST_OS
937 -- we want to truncate() if this is an open in WriteMode, but only
938 -- if the target is a RegularFile. ftruncate() fails on special files
940 if mode == WriteMode && fd_type == RegularFile
941 then throwErrnoIf (/=0) "openFile"
948 std_flags, output_flags, read_flags, write_flags, rw_flags,
950 std_flags = o_NONBLOCK .|. o_NOCTTY
951 output_flags = std_flags .|. o_CREAT
952 read_flags = std_flags .|. o_RDONLY
953 write_flags = output_flags .|. o_WRONLY
954 rw_flags = output_flags .|. o_RDWR
955 append_flags = write_flags .|. o_APPEND
957 -- ---------------------------------------------------------------------------
960 fdToHandle_stat :: FD
961 -> Maybe (FDType, CDev, CIno)
968 fdToHandle_stat fd mb_stat is_socket filepath mode binary = do
970 #ifdef mingw32_HOST_OS
971 -- On Windows, the is_socket flag indicates that the Handle is a socket
973 -- On Unix, the is_socket flag indicates that the FD can be made non-blocking
974 let non_blocking = is_socket
976 when non_blocking $ setNonBlockingFD fd
977 -- turn on non-blocking mode
980 let (ha_type, write) =
982 ReadMode -> ( ReadHandle, False )
983 WriteMode -> ( WriteHandle, True )
984 ReadWriteMode -> ( ReadWriteHandle, True )
985 AppendMode -> ( AppendHandle, True )
987 -- open() won't tell us if it was a directory if we only opened for
988 -- reading, so check again.
996 ioException (IOError Nothing InappropriateType "openFile"
997 "is a directory" Nothing)
999 -- regular files need to be locked
1001 #ifndef mingw32_HOST_OS
1002 -- On Windows we use explicit exclusion via sopen() to implement
1003 -- this locking (see __hscore_open()); on Unix we have to
1004 -- implment it in the RTS.
1005 r <- lockFile fd dev ino (fromBool write)
1007 ioException (IOError Nothing ResourceBusy "openFile"
1008 "file is locked" Nothing)
1010 mkFileHandle fd is_socket filepath ha_type binary
1013 -- only *Streams* can be DuplexHandles. Other read/write
1014 -- Handles must share a buffer.
1015 | ReadWriteHandle <- ha_type ->
1016 mkDuplexHandle fd is_socket filepath binary
1018 mkFileHandle fd is_socket filepath ha_type binary
1021 mkFileHandle fd is_socket filepath ha_type binary
1023 -- | Old API kept to avoid breaking clients
1024 fdToHandle' :: FD -> Maybe FDType -> Bool -> FilePath -> IOMode -> Bool
1026 fdToHandle' fd mb_type is_socket filepath mode binary
1028 let mb_stat = case mb_type of
1030 -- fdToHandle_stat will do the stat:
1031 Just RegularFile -> Nothing
1032 -- no stat required for streams etc.:
1033 Just other -> Just (other,0,0)
1034 fdToHandle_stat fd mb_stat is_socket filepath mode binary
1036 fdToHandle :: FD -> IO Handle
1038 mode <- fdGetMode fd
1039 let fd_str = "<file descriptor: " ++ show fd ++ ">"
1040 fdToHandle_stat fd Nothing False fd_str mode True{-bin mode-}
1041 -- NB. the is_socket flag is False, meaning that:
1042 -- on Unix the file descriptor will *not* be put in non-blocking mode
1043 -- on Windows we're guessing this is not a socket (XXX)
1045 #ifndef mingw32_HOST_OS
1046 foreign import ccall unsafe "lockFile"
1047 lockFile :: CInt -> CDev -> CIno -> CInt -> IO CInt
1049 foreign import ccall unsafe "unlockFile"
1050 unlockFile :: CInt -> IO CInt
1053 mkStdHandle :: FD -> FilePath -> HandleType -> IORef Buffer -> BufferMode
1055 mkStdHandle fd filepath ha_type buf bmode = do
1056 spares <- newIORef BufferListNil
1057 newFileHandle filepath (stdHandleFinalizer filepath)
1058 (Handle__ { haFD = fd,
1060 haIsBin = dEFAULT_OPEN_IN_BINARY_MODE,
1061 haIsStream = False, -- means FD is blocking on Unix
1062 haBufferMode = bmode,
1065 haOtherSide = Nothing
1068 mkFileHandle :: FD -> Bool -> FilePath -> HandleType -> Bool -> IO Handle
1069 mkFileHandle fd is_stream filepath ha_type binary = do
1070 (buf, bmode) <- getBuffer fd (initBufferState ha_type)
1072 #ifdef mingw32_HOST_OS
1073 -- On Windows, if this is a read/write handle and we are in text mode,
1074 -- turn off buffering. We don't correctly handle the case of switching
1075 -- from read mode to write mode on a buffered text-mode handle, see bug
1077 bmode2 <- case ha_type of
1078 ReadWriteHandle | not binary -> return NoBuffering
1079 _other -> return bmode
1084 spares <- newIORef BufferListNil
1085 newFileHandle filepath (handleFinalizer filepath)
1086 (Handle__ { haFD = fd,
1089 haIsStream = is_stream,
1090 haBufferMode = bmode2,
1093 haOtherSide = Nothing
1096 mkDuplexHandle :: FD -> Bool -> FilePath -> Bool -> IO Handle
1097 mkDuplexHandle fd is_stream filepath binary = do
1098 (w_buf, w_bmode) <- getBuffer fd WriteBuffer
1099 w_spares <- newIORef BufferListNil
1101 Handle__ { haFD = fd,
1102 haType = WriteHandle,
1104 haIsStream = is_stream,
1105 haBufferMode = w_bmode,
1107 haBuffers = w_spares,
1108 haOtherSide = Nothing
1110 write_side <- newMVar w_handle_
1112 (r_buf, r_bmode) <- getBuffer fd ReadBuffer
1113 r_spares <- newIORef BufferListNil
1115 Handle__ { haFD = fd,
1116 haType = ReadHandle,
1118 haIsStream = is_stream,
1119 haBufferMode = r_bmode,
1121 haBuffers = r_spares,
1122 haOtherSide = Just write_side
1124 read_side <- newMVar r_handle_
1126 addMVarFinalizer write_side (handleFinalizer filepath write_side)
1127 return (DuplexHandle filepath read_side write_side)
1129 initBufferState :: HandleType -> BufferState
1130 initBufferState ReadHandle = ReadBuffer
1131 initBufferState _ = WriteBuffer
1133 -- ---------------------------------------------------------------------------
1136 -- | Computation 'hClose' @hdl@ makes handle @hdl@ closed. Before the
1137 -- computation finishes, if @hdl@ is writable its buffer is flushed as
1139 -- Performing 'hClose' on a handle that has already been closed has no effect;
1140 -- doing so is not an error. All other operations on a closed handle will fail.
1141 -- If 'hClose' fails for any reason, any further operations (apart from
1142 -- 'hClose') on the handle will still fail as if @hdl@ had been successfully
1145 hClose :: Handle -> IO ()
1146 hClose h@(FileHandle _ m) = do
1147 mb_exc <- hClose' h m
1149 Nothing -> return ()
1151 hClose h@(DuplexHandle _ r w) = do
1152 mb_exc1 <- hClose' h w
1153 mb_exc2 <- hClose' h r
1154 case (do mb_exc1; mb_exc2) of
1155 Nothing -> return ()
1158 hClose' :: Handle -> MVar Handle__ -> IO (Maybe SomeException)
1159 hClose' h m = withHandle' "hClose" h m $ hClose_help
1161 -- hClose_help is also called by lazyRead (in PrelIO) when EOF is read
1162 -- or an IO error occurs on a lazy stream. The semi-closed Handle is
1163 -- then closed immediately. We have to be careful with DuplexHandles
1164 -- though: we have to leave the closing to the finalizer in that case,
1165 -- because the write side may still be in use.
1166 hClose_help :: Handle__ -> IO (Handle__, Maybe SomeException)
1167 hClose_help handle_ =
1168 case haType handle_ of
1169 ClosedHandle -> return (handle_,Nothing)
1170 _ -> do flushWriteBufferOnly handle_ -- interruptible
1171 hClose_handle_ handle_
1173 hClose_handle_ :: Handle__ -> IO (Handle__, Maybe SomeException)
1174 hClose_handle_ handle_ = do
1175 let fd = haFD handle_
1177 -- close the file descriptor, but not when this is the read
1178 -- side of a duplex handle.
1179 -- If an exception is raised by the close(), we want to continue
1180 -- to close the handle and release the lock if it has one, then
1181 -- we return the exception to the caller of hClose_help which can
1182 -- raise it if necessary.
1184 case haOtherSide handle_ of
1186 throwErrnoIfMinus1Retry_ "hClose"
1187 #ifdef mingw32_HOST_OS
1188 (closeFd (haIsStream handle_) fd)
1194 `catchException` \e -> return (Just e)
1196 Just _ -> return Nothing
1198 -- free the spare buffers
1199 writeIORef (haBuffers handle_) BufferListNil
1200 writeIORef (haBuffer handle_) noBuffer
1202 #ifndef mingw32_HOST_OS
1207 -- we must set the fd to -1, because the finalizer is going
1208 -- to run eventually and try to close/unlock it.
1209 return (handle_{ haFD = -1,
1210 haType = ClosedHandle
1214 {-# NOINLINE noBuffer #-}
1216 noBuffer = unsafePerformIO $ allocateBuffer 1 ReadBuffer
1218 -----------------------------------------------------------------------------
1219 -- Detecting and changing the size of a file
1221 -- | For a handle @hdl@ which attached to a physical file,
1222 -- 'hFileSize' @hdl@ returns the size of that file in 8-bit bytes.
1224 hFileSize :: Handle -> IO Integer
1226 withHandle_ "hFileSize" handle $ \ handle_ -> do
1227 case haType handle_ of
1228 ClosedHandle -> ioe_closedHandle
1229 SemiClosedHandle -> ioe_closedHandle
1230 _ -> do flushWriteBufferOnly handle_
1231 r <- fdFileSize (haFD handle_)
1234 else ioException (IOError Nothing InappropriateType "hFileSize"
1235 "not a regular file" Nothing)
1238 -- | 'hSetFileSize' @hdl@ @size@ truncates the physical file with handle @hdl@ to @size@ bytes.
1240 hSetFileSize :: Handle -> Integer -> IO ()
1241 hSetFileSize handle size =
1242 withHandle_ "hSetFileSize" handle $ \ handle_ -> do
1243 case haType handle_ of
1244 ClosedHandle -> ioe_closedHandle
1245 SemiClosedHandle -> ioe_closedHandle
1246 _ -> do flushWriteBufferOnly handle_
1247 throwErrnoIf (/=0) "hSetFileSize"
1248 (c_ftruncate (haFD handle_) (fromIntegral size))
1251 -- ---------------------------------------------------------------------------
1252 -- Detecting the End of Input
1254 -- | For a readable handle @hdl@, 'hIsEOF' @hdl@ returns
1255 -- 'True' if no further input can be taken from @hdl@ or for a
1256 -- physical file, if the current I\/O position is equal to the length of
1257 -- the file. Otherwise, it returns 'False'.
1259 -- NOTE: 'hIsEOF' may block, because it is the same as calling
1260 -- 'hLookAhead' and checking for an EOF exception.
1262 hIsEOF :: Handle -> IO Bool
1265 (do hLookAhead handle; return False)
1266 (\e -> if isEOFError e then return True else ioError e)
1268 -- | The computation 'isEOF' is identical to 'hIsEOF',
1269 -- except that it works only on 'stdin'.
1272 isEOF = hIsEOF stdin
1274 -- ---------------------------------------------------------------------------
1277 -- | Computation 'hLookAhead' returns the next character from the handle
1278 -- without removing it from the input buffer, blocking until a character
1281 -- This operation may fail with:
1283 -- * 'isEOFError' if the end of file has been reached.
1285 hLookAhead :: Handle -> IO Char
1287 wantReadableHandle "hLookAhead" handle hLookAhead'
1289 hLookAhead' :: Handle__ -> IO Char
1290 hLookAhead' handle_ = do
1291 let ref = haBuffer handle_
1293 buf <- readIORef ref
1295 -- fill up the read buffer if necessary
1296 new_buf <- if bufferEmpty buf
1297 then fillReadBuffer fd True (haIsStream handle_) buf
1300 writeIORef ref new_buf
1302 (c,_) <- readCharFromBuffer (bufBuf buf) (bufRPtr buf)
1305 -- ---------------------------------------------------------------------------
1306 -- Buffering Operations
1308 -- Three kinds of buffering are supported: line-buffering,
1309 -- block-buffering or no-buffering. See GHC.IOBase for definition and
1310 -- further explanation of what the type represent.
1312 -- | Computation 'hSetBuffering' @hdl mode@ sets the mode of buffering for
1313 -- handle @hdl@ on subsequent reads and writes.
1315 -- If the buffer mode is changed from 'BlockBuffering' or
1316 -- 'LineBuffering' to 'NoBuffering', then
1318 -- * if @hdl@ is writable, the buffer is flushed as for 'hFlush';
1320 -- * if @hdl@ is not writable, the contents of the buffer is discarded.
1322 -- This operation may fail with:
1324 -- * 'isPermissionError' if the handle has already been used for reading
1325 -- or writing and the implementation does not allow the buffering mode
1328 hSetBuffering :: Handle -> BufferMode -> IO ()
1329 hSetBuffering handle mode =
1330 withAllHandles__ "hSetBuffering" handle $ \ handle_ -> do
1331 case haType handle_ of
1332 ClosedHandle -> ioe_closedHandle
1335 - we flush the old buffer regardless of whether
1336 the new buffer could fit the contents of the old buffer
1338 - allow a handle's buffering to change even if IO has
1339 occurred (ANSI C spec. does not allow this, nor did
1340 the previous implementation of IO.hSetBuffering).
1341 - a non-standard extension is to allow the buffering
1342 of semi-closed handles to change [sof 6/98]
1346 let state = initBufferState (haType handle_)
1349 -- we always have a 1-character read buffer for
1350 -- unbuffered handles: it's needed to
1351 -- support hLookAhead.
1352 NoBuffering -> allocateBuffer 1 ReadBuffer
1353 LineBuffering -> allocateBuffer dEFAULT_BUFFER_SIZE state
1354 BlockBuffering Nothing -> allocateBuffer dEFAULT_BUFFER_SIZE state
1355 BlockBuffering (Just n) | n <= 0 -> ioe_bufsiz n
1356 | otherwise -> allocateBuffer n state
1357 writeIORef (haBuffer handle_) new_buf
1359 -- for input terminals we need to put the terminal into
1360 -- cooked or raw mode depending on the type of buffering.
1361 is_tty <- fdIsTTY (haFD handle_)
1362 when (is_tty && isReadableHandleType (haType handle_)) $
1364 #ifndef mingw32_HOST_OS
1365 -- 'raw' mode under win32 is a bit too specialised (and troublesome
1366 -- for most common uses), so simply disable its use here.
1367 NoBuffering -> setCooked (haFD handle_) False
1369 NoBuffering -> return ()
1371 _ -> setCooked (haFD handle_) True
1373 -- throw away spare buffers, they might be the wrong size
1374 writeIORef (haBuffers handle_) BufferListNil
1376 return (handle_{ haBufferMode = mode })
1378 -- -----------------------------------------------------------------------------
1381 -- | The action 'hFlush' @hdl@ causes any items buffered for output
1382 -- in handle @hdl@ to be sent immediately to the operating system.
1384 -- This operation may fail with:
1386 -- * 'isFullError' if the device is full;
1388 -- * 'isPermissionError' if a system resource limit would be exceeded.
1389 -- It is unspecified whether the characters in the buffer are discarded
1390 -- or retained under these circumstances.
1392 hFlush :: Handle -> IO ()
1394 wantWritableHandle "hFlush" handle $ \ handle_ -> do
1395 buf <- readIORef (haBuffer handle_)
1396 if bufferIsWritable buf && not (bufferEmpty buf)
1397 then do flushed_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
1398 writeIORef (haBuffer handle_) flushed_buf
1402 -- -----------------------------------------------------------------------------
1403 -- Repositioning Handles
1405 data HandlePosn = HandlePosn Handle HandlePosition
1407 instance Eq HandlePosn where
1408 (HandlePosn h1 p1) == (HandlePosn h2 p2) = p1==p2 && h1==h2
1410 instance Show HandlePosn where
1411 showsPrec p (HandlePosn h pos) =
1412 showsPrec p h . showString " at position " . shows pos
1414 -- HandlePosition is the Haskell equivalent of POSIX' off_t.
1415 -- We represent it as an Integer on the Haskell side, but
1416 -- cheat slightly in that hGetPosn calls upon a C helper
1417 -- that reports the position back via (merely) an Int.
1418 type HandlePosition = Integer
1420 -- | Computation 'hGetPosn' @hdl@ returns the current I\/O position of
1421 -- @hdl@ as a value of the abstract type 'HandlePosn'.
1423 hGetPosn :: Handle -> IO HandlePosn
1424 hGetPosn handle = do
1425 posn <- hTell handle
1426 return (HandlePosn handle posn)
1428 -- | If a call to 'hGetPosn' @hdl@ returns a position @p@,
1429 -- then computation 'hSetPosn' @p@ sets the position of @hdl@
1430 -- to the position it held at the time of the call to 'hGetPosn'.
1432 -- This operation may fail with:
1434 -- * 'isPermissionError' if a system resource limit would be exceeded.
1436 hSetPosn :: HandlePosn -> IO ()
1437 hSetPosn (HandlePosn h i) = hSeek h AbsoluteSeek i
1439 -- ---------------------------------------------------------------------------
1442 -- | A mode that determines the effect of 'hSeek' @hdl mode i@, as follows:
1444 = AbsoluteSeek -- ^ the position of @hdl@ is set to @i@.
1445 | RelativeSeek -- ^ the position of @hdl@ is set to offset @i@
1446 -- from the current position.
1447 | SeekFromEnd -- ^ the position of @hdl@ is set to offset @i@
1448 -- from the end of the file.
1449 deriving (Eq, Ord, Ix, Enum, Read, Show)
1452 - when seeking using `SeekFromEnd', positive offsets (>=0) means
1453 seeking at or past EOF.
1455 - we possibly deviate from the report on the issue of seeking within
1456 the buffer and whether to flush it or not. The report isn't exactly
1460 -- | Computation 'hSeek' @hdl mode i@ sets the position of handle
1461 -- @hdl@ depending on @mode@.
1462 -- The offset @i@ is given in terms of 8-bit bytes.
1464 -- If @hdl@ is block- or line-buffered, then seeking to a position which is not
1465 -- in the current buffer will first cause any items in the output buffer to be
1466 -- written to the device, and then cause the input buffer to be discarded.
1467 -- Some handles may not be seekable (see 'hIsSeekable'), or only support a
1468 -- subset of the possible positioning operations (for instance, it may only
1469 -- be possible to seek to the end of a tape, or to a positive offset from
1470 -- the beginning or current position).
1471 -- It is not possible to set a negative I\/O position, or for
1472 -- a physical file, an I\/O position beyond the current end-of-file.
1474 -- This operation may fail with:
1476 -- * 'isPermissionError' if a system resource limit would be exceeded.
1478 hSeek :: Handle -> SeekMode -> Integer -> IO ()
1479 hSeek handle mode offset =
1480 wantSeekableHandle "hSeek" handle $ \ handle_ -> do
1482 puts ("hSeek " ++ show (mode,offset) ++ "\n")
1484 let ref = haBuffer handle_
1485 buf <- readIORef ref
1491 throwErrnoIfMinus1Retry_ "hSeek"
1492 (c_lseek (haFD handle_) (fromIntegral offset) whence)
1495 whence = case mode of
1496 AbsoluteSeek -> sEEK_SET
1497 RelativeSeek -> sEEK_CUR
1498 SeekFromEnd -> sEEK_END
1500 if bufferIsWritable buf
1501 then do new_buf <- flushWriteBuffer fd (haIsStream handle_) buf
1502 writeIORef ref new_buf
1506 if mode == RelativeSeek && offset >= 0 && offset < fromIntegral (w - r)
1507 then writeIORef ref buf{ bufRPtr = r + fromIntegral offset }
1510 new_buf <- flushReadBuffer (haFD handle_) buf
1511 writeIORef ref new_buf
1515 hTell :: Handle -> IO Integer
1517 wantSeekableHandle "hGetPosn" handle $ \ handle_ -> do
1519 #if defined(mingw32_HOST_OS)
1520 -- urgh, on Windows we have to worry about \n -> \r\n translation,
1521 -- so we can't easily calculate the file position using the
1522 -- current buffer size. Just flush instead.
1525 let fd = haFD handle_
1526 posn <- fromIntegral `liftM`
1527 throwErrnoIfMinus1Retry "hGetPosn"
1528 (c_lseek fd 0 sEEK_CUR)
1530 let ref = haBuffer handle_
1531 buf <- readIORef ref
1534 | bufferIsWritable buf = posn + fromIntegral (bufWPtr buf)
1535 | otherwise = posn - fromIntegral (bufWPtr buf - bufRPtr buf)
1537 puts ("\nhGetPosn: (fd, posn, real_posn) = " ++ show (fd, posn, real_posn) ++ "\n")
1538 puts (" (bufWPtr, bufRPtr) = " ++ show (bufWPtr buf, bufRPtr buf) ++ "\n")
1542 -- -----------------------------------------------------------------------------
1543 -- Handle Properties
1545 -- A number of operations return information about the properties of a
1546 -- handle. Each of these operations returns `True' if the handle has
1547 -- the specified property, and `False' otherwise.
1549 hIsOpen :: Handle -> IO Bool
1551 withHandle_ "hIsOpen" handle $ \ handle_ -> do
1552 case haType handle_ of
1553 ClosedHandle -> return False
1554 SemiClosedHandle -> return False
1557 hIsClosed :: Handle -> IO Bool
1559 withHandle_ "hIsClosed" handle $ \ handle_ -> do
1560 case haType handle_ of
1561 ClosedHandle -> return True
1564 {- not defined, nor exported, but mentioned
1565 here for documentation purposes:
1567 hSemiClosed :: Handle -> IO Bool
1571 return (not (ho || hc))
1574 hIsReadable :: Handle -> IO Bool
1575 hIsReadable (DuplexHandle _ _ _) = return True
1576 hIsReadable handle =
1577 withHandle_ "hIsReadable" handle $ \ handle_ -> do
1578 case haType handle_ of
1579 ClosedHandle -> ioe_closedHandle
1580 SemiClosedHandle -> ioe_closedHandle
1581 htype -> return (isReadableHandleType htype)
1583 hIsWritable :: Handle -> IO Bool
1584 hIsWritable (DuplexHandle _ _ _) = return True
1585 hIsWritable handle =
1586 withHandle_ "hIsWritable" handle $ \ handle_ -> do
1587 case haType handle_ of
1588 ClosedHandle -> ioe_closedHandle
1589 SemiClosedHandle -> ioe_closedHandle
1590 htype -> return (isWritableHandleType htype)
1592 -- | Computation 'hGetBuffering' @hdl@ returns the current buffering mode
1595 hGetBuffering :: Handle -> IO BufferMode
1596 hGetBuffering handle =
1597 withHandle_ "hGetBuffering" handle $ \ handle_ -> do
1598 case haType handle_ of
1599 ClosedHandle -> ioe_closedHandle
1601 -- We're being non-standard here, and allow the buffering
1602 -- of a semi-closed handle to be queried. -- sof 6/98
1603 return (haBufferMode handle_) -- could be stricter..
1605 hIsSeekable :: Handle -> IO Bool
1606 hIsSeekable handle =
1607 withHandle_ "hIsSeekable" handle $ \ handle_ -> do
1608 case haType handle_ of
1609 ClosedHandle -> ioe_closedHandle
1610 SemiClosedHandle -> ioe_closedHandle
1611 AppendHandle -> return False
1612 _ -> do t <- fdType (haFD handle_)
1613 return ((t == RegularFile || t == RawDevice)
1614 && (haIsBin handle_ || tEXT_MODE_SEEK_ALLOWED))
1616 -- -----------------------------------------------------------------------------
1617 -- Changing echo status (Non-standard GHC extensions)
1619 -- | Set the echoing status of a handle connected to a terminal.
1621 hSetEcho :: Handle -> Bool -> IO ()
1622 hSetEcho handle on = do
1623 isT <- hIsTerminalDevice handle
1627 withHandle_ "hSetEcho" handle $ \ handle_ -> do
1628 case haType handle_ of
1629 ClosedHandle -> ioe_closedHandle
1630 _ -> setEcho (haFD handle_) on
1632 -- | Get the echoing status of a handle connected to a terminal.
1634 hGetEcho :: Handle -> IO Bool
1635 hGetEcho handle = do
1636 isT <- hIsTerminalDevice handle
1640 withHandle_ "hGetEcho" handle $ \ handle_ -> do
1641 case haType handle_ of
1642 ClosedHandle -> ioe_closedHandle
1643 _ -> getEcho (haFD handle_)
1645 -- | Is the handle connected to a terminal?
1647 hIsTerminalDevice :: Handle -> IO Bool
1648 hIsTerminalDevice handle = do
1649 withHandle_ "hIsTerminalDevice" handle $ \ handle_ -> do
1650 case haType handle_ of
1651 ClosedHandle -> ioe_closedHandle
1652 _ -> fdIsTTY (haFD handle_)
1654 -- -----------------------------------------------------------------------------
1657 -- | Select binary mode ('True') or text mode ('False') on a open handle.
1658 -- (See also 'openBinaryFile'.)
1660 hSetBinaryMode :: Handle -> Bool -> IO ()
1661 hSetBinaryMode handle bin =
1662 withAllHandles__ "hSetBinaryMode" handle $ \ handle_ ->
1663 do throwErrnoIfMinus1_ "hSetBinaryMode"
1664 (setmode (haFD handle_) bin)
1665 return handle_{haIsBin=bin}
1667 foreign import ccall unsafe "__hscore_setmode"
1668 setmode :: CInt -> Bool -> IO CInt
1670 -- -----------------------------------------------------------------------------
1671 -- Duplicating a Handle
1673 -- | Returns a duplicate of the original handle, with its own buffer.
1674 -- The two Handles will share a file pointer, however. The original
1675 -- handle's buffer is flushed, including discarding any input data,
1676 -- before the handle is duplicated.
1678 hDuplicate :: Handle -> IO Handle
1679 hDuplicate h@(FileHandle path m) = do
1680 new_h_ <- withHandle' "hDuplicate" h m (dupHandle h Nothing)
1681 newFileHandle path (handleFinalizer path) new_h_
1682 hDuplicate h@(DuplexHandle path r w) = do
1683 new_w_ <- withHandle' "hDuplicate" h w (dupHandle h Nothing)
1684 new_w <- newMVar new_w_
1685 new_r_ <- withHandle' "hDuplicate" h r (dupHandle h (Just new_w))
1686 new_r <- newMVar new_r_
1687 addMVarFinalizer new_w (handleFinalizer path new_w)
1688 return (DuplexHandle path new_r new_w)
1690 dupHandle :: Handle -> Maybe (MVar Handle__) -> Handle__
1691 -> IO (Handle__, Handle__)
1692 dupHandle h other_side h_ = do
1693 -- flush the buffer first, so we don't have to copy its contents
1695 new_fd <- case other_side of
1696 Nothing -> throwErrnoIfMinus1 "dupHandle" $ c_dup (haFD h_)
1697 Just r -> withHandle_' "dupHandle" h r (return . haFD)
1698 dupHandle_ other_side h_ new_fd
1700 dupHandleTo :: Maybe (MVar Handle__) -> Handle__ -> Handle__
1701 -> IO (Handle__, Handle__)
1702 dupHandleTo other_side hto_ h_ = do
1704 -- Windows' dup2 does not return the new descriptor, unlike Unix
1705 throwErrnoIfMinus1 "dupHandleTo" $
1706 c_dup2 (haFD h_) (haFD hto_)
1707 dupHandle_ other_side h_ (haFD hto_)
1709 dupHandle_ :: Maybe (MVar Handle__) -> Handle__ -> FD
1710 -> IO (Handle__, Handle__)
1711 dupHandle_ other_side h_ new_fd = do
1712 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE (initBufferState (haType h_))
1713 ioref <- newIORef buffer
1714 ioref_buffers <- newIORef BufferListNil
1716 let new_handle_ = h_{ haFD = new_fd,
1718 haBuffers = ioref_buffers,
1719 haOtherSide = other_side }
1720 return (h_, new_handle_)
1722 -- -----------------------------------------------------------------------------
1723 -- Replacing a Handle
1726 Makes the second handle a duplicate of the first handle. The second
1727 handle will be closed first, if it is not already.
1729 This can be used to retarget the standard Handles, for example:
1731 > do h <- openFile "mystdout" WriteMode
1732 > hDuplicateTo h stdout
1735 hDuplicateTo :: Handle -> Handle -> IO ()
1736 hDuplicateTo h1@(FileHandle _ m1) h2@(FileHandle _ m2) = do
1737 withHandle__' "hDuplicateTo" h2 m2 $ \h2_ -> do
1738 _ <- hClose_help h2_
1739 withHandle' "hDuplicateTo" h1 m1 (dupHandleTo Nothing h2_)
1740 hDuplicateTo h1@(DuplexHandle _ r1 w1) h2@(DuplexHandle _ r2 w2) = do
1741 withHandle__' "hDuplicateTo" h2 w2 $ \w2_ -> do
1742 _ <- hClose_help w2_
1743 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo Nothing w2_)
1744 withHandle__' "hDuplicateTo" h2 r2 $ \r2_ -> do
1745 _ <- hClose_help r2_
1746 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo (Just w1) r2_)
1748 ioException (IOError (Just h1) IllegalOperation "hDuplicateTo"
1749 "handles are incompatible" Nothing)
1751 -- ---------------------------------------------------------------------------
1754 -- | 'hShow' is in the 'IO' monad, and gives more comprehensive output
1755 -- than the (pure) instance of 'Show' for 'Handle'.
1757 hShow :: Handle -> IO String
1758 hShow h@(FileHandle path _) = showHandle' path False h
1759 hShow h@(DuplexHandle path _ _) = showHandle' path True h
1761 showHandle' :: String -> Bool -> Handle -> IO String
1762 showHandle' filepath is_duplex h =
1763 withHandle_ "showHandle" h $ \hdl_ ->
1765 showType | is_duplex = showString "duplex (read-write)"
1766 | otherwise = shows (haType hdl_)
1770 showHdl (haType hdl_)
1771 (showString "loc=" . showString filepath . showChar ',' .
1772 showString "type=" . showType . showChar ',' .
1773 showString "binary=" . shows (haIsBin hdl_) . showChar ',' .
1774 showString "buffering=" . showBufMode (unsafePerformIO (readIORef (haBuffer hdl_))) (haBufferMode hdl_) . showString "}" )
1778 showHdl :: HandleType -> ShowS -> ShowS
1781 ClosedHandle -> shows ht . showString "}"
1784 showBufMode :: Buffer -> BufferMode -> ShowS
1785 showBufMode buf bmo =
1787 NoBuffering -> showString "none"
1788 LineBuffering -> showString "line"
1789 BlockBuffering (Just n) -> showString "block " . showParen True (shows n)
1790 BlockBuffering Nothing -> showString "block " . showParen True (shows def)
1795 -- ---------------------------------------------------------------------------
1798 #if defined(DEBUG_DUMP)
1799 puts :: String -> IO ()
1800 puts s = do write_rawBuffer 1 (unsafeCoerce# (packCString# s)) 0 (fromIntegral (length s))
1804 -- -----------------------------------------------------------------------------
1807 throwErrnoIfMinus1RetryOnBlock :: String -> IO CInt -> IO CInt -> IO CInt
1808 throwErrnoIfMinus1RetryOnBlock loc f on_block =
1811 if (res :: CInt) == -1
1815 then throwErrnoIfMinus1RetryOnBlock loc f on_block
1816 else if err == eWOULDBLOCK || err == eAGAIN
1821 -- -----------------------------------------------------------------------------
1822 -- wrappers to platform-specific constants:
1824 foreign import ccall unsafe "__hscore_supportsTextMode"
1825 tEXT_MODE_SEEK_ALLOWED :: Bool
1827 foreign import ccall unsafe "__hscore_bufsiz" dEFAULT_BUFFER_SIZE :: Int
1828 foreign import ccall unsafe "__hscore_seek_cur" sEEK_CUR :: CInt
1829 foreign import ccall unsafe "__hscore_seek_set" sEEK_SET :: CInt
1830 foreign import ccall unsafe "__hscore_seek_end" sEEK_END :: CInt