Avoid using deprecated flags
[packages/base.git] / GHC / Handle.hs
1 {-# OPTIONS_GHC -XNoImplicitPrelude -#include "HsBase.h" #-}
2 {-# OPTIONS_HADDOCK hide #-}
3
4 #undef DEBUG_DUMP
5 #undef DEBUG
6
7 -----------------------------------------------------------------------------
8 -- |
9 -- Module : GHC.Handle
10 -- Copyright : (c) The University of Glasgow, 1994-2001
11 -- License : see libraries/base/LICENSE
12 --
13 -- Maintainer : libraries@haskell.org
14 -- Stability : internal
15 -- Portability : non-portable
16 --
17 -- This module defines the basic operations on I\/O \"handles\".
18 --
19 -----------------------------------------------------------------------------
20
21 -- #hide
22 module GHC.Handle (
23 withHandle, withHandle', withHandle_,
24 wantWritableHandle, wantReadableHandle, wantSeekableHandle,
25
26 newEmptyBuffer, allocateBuffer, readCharFromBuffer, writeCharIntoBuffer,
27 flushWriteBufferOnly, flushWriteBuffer, flushReadBuffer,
28 fillReadBuffer, fillReadBufferWithoutBlocking,
29 readRawBuffer, readRawBufferPtr,
30 readRawBufferNoBlock, readRawBufferPtrNoBlock,
31 writeRawBuffer, writeRawBufferPtr,
32
33 #ifndef mingw32_HOST_OS
34 unlockFile,
35 #endif
36
37 ioe_closedHandle, ioe_EOF, ioe_notReadable, ioe_notWritable,
38
39 stdin, stdout, stderr,
40 IOMode(..), openFile, openBinaryFile, fdToHandle_stat, fdToHandle, fdToHandle',
41 hFileSize, hSetFileSize, hIsEOF, isEOF, hLookAhead, hSetBuffering, hSetBinaryMode,
42 hFlush, hDuplicate, hDuplicateTo,
43
44 hClose, hClose_help,
45
46 HandlePosition, HandlePosn(..), hGetPosn, hSetPosn,
47 SeekMode(..), hSeek, hTell,
48
49 hIsOpen, hIsClosed, hIsReadable, hIsWritable, hGetBuffering, hIsSeekable,
50 hSetEcho, hGetEcho, hIsTerminalDevice,
51
52 hShow,
53
54 #ifdef DEBUG_DUMP
55 puts,
56 #endif
57
58 ) where
59
60 import Control.Monad
61 import Data.Bits
62 import Data.Maybe
63 import Foreign
64 import Foreign.C
65 import System.IO.Error
66 import System.Posix.Internals
67 import System.Posix.Types
68
69 import GHC.Real
70
71 import GHC.Arr
72 import GHC.Base
73 import GHC.Read ( Read )
74 import GHC.List
75 import GHC.IOBase
76 import GHC.Exception
77 import GHC.Enum
78 import GHC.Num ( Integer(..), Num(..) )
79 import GHC.Show
80 import GHC.Real ( toInteger )
81 #if defined(DEBUG_DUMP)
82 import GHC.Pack
83 #endif
84
85 import GHC.Conc
86
87 -- -----------------------------------------------------------------------------
88 -- TODO:
89
90 -- hWaitForInput blocks (should use a timeout)
91
92 -- unbuffered hGetLine is a bit dodgy
93
94 -- hSetBuffering: can't change buffering on a stream,
95 -- when the read buffer is non-empty? (no way to flush the buffer)
96
97 -- ---------------------------------------------------------------------------
98 -- Are files opened by default in text or binary mode, if the user doesn't
99 -- specify?
100
101 dEFAULT_OPEN_IN_BINARY_MODE = False :: Bool
102
103 -- ---------------------------------------------------------------------------
104 -- Creating a new handle
105
106 newFileHandle :: FilePath -> (MVar Handle__ -> IO ()) -> Handle__ -> IO Handle
107 newFileHandle filepath finalizer hc = do
108 m <- newMVar hc
109 addMVarFinalizer m (finalizer m)
110 return (FileHandle filepath m)
111
112 -- ---------------------------------------------------------------------------
113 -- Working with Handles
114
115 {-
116 In the concurrent world, handles are locked during use. This is done
117 by wrapping an MVar around the handle which acts as a mutex over
118 operations on the handle.
119
120 To avoid races, we use the following bracketing operations. The idea
121 is to obtain the lock, do some operation and replace the lock again,
122 whether the operation succeeded or failed. We also want to handle the
123 case where the thread receives an exception while processing the IO
124 operation: in these cases we also want to relinquish the lock.
125
126 There are three versions of @withHandle@: corresponding to the three
127 possible combinations of:
128
129 - the operation may side-effect the handle
130 - the operation may return a result
131
132 If the operation generates an error or an exception is raised, the
133 original handle is always replaced [ this is the case at the moment,
134 but we might want to revisit this in the future --SDM ].
135 -}
136
137 {-# INLINE withHandle #-}
138 withHandle :: String -> Handle -> (Handle__ -> IO (Handle__,a)) -> IO a
139 withHandle fun h@(FileHandle _ m) act = withHandle' fun h m act
140 withHandle fun h@(DuplexHandle _ m _) act = withHandle' fun h m act
141
142 withHandle' :: String -> Handle -> MVar Handle__
143 -> (Handle__ -> IO (Handle__,a)) -> IO a
144 withHandle' fun h m act =
145 block $ do
146 h_ <- takeMVar m
147 checkBufferInvariants h_
148 (h',v) <- catchException (act h_)
149 (\ err -> putMVar m h_ >>
150 case err of
151 IOException ex -> ioError (augmentIOError ex fun h)
152 _ -> throw err)
153 checkBufferInvariants h'
154 putMVar m h'
155 return v
156
157 {-# INLINE withHandle_ #-}
158 withHandle_ :: String -> Handle -> (Handle__ -> IO a) -> IO a
159 withHandle_ fun h@(FileHandle _ m) act = withHandle_' fun h m act
160 withHandle_ fun h@(DuplexHandle _ m _) act = withHandle_' fun h m act
161
162 withHandle_' :: String -> Handle -> MVar Handle__ -> (Handle__ -> IO a) -> IO a
163 withHandle_' fun h m act =
164 block $ do
165 h_ <- takeMVar m
166 checkBufferInvariants h_
167 v <- catchException (act h_)
168 (\ err -> putMVar m h_ >>
169 case err of
170 IOException ex -> ioError (augmentIOError ex fun h)
171 _ -> throw err)
172 checkBufferInvariants h_
173 putMVar m h_
174 return v
175
176 withAllHandles__ :: String -> Handle -> (Handle__ -> IO Handle__) -> IO ()
177 withAllHandles__ fun h@(FileHandle _ m) act = withHandle__' fun h m act
178 withAllHandles__ fun h@(DuplexHandle _ r w) act = do
179 withHandle__' fun h r act
180 withHandle__' fun h w act
181
182 withHandle__' fun h m act =
183 block $ do
184 h_ <- takeMVar m
185 checkBufferInvariants h_
186 h' <- catchException (act h_)
187 (\ err -> putMVar m h_ >>
188 case err of
189 IOException ex -> ioError (augmentIOError ex fun h)
190 _ -> throw err)
191 checkBufferInvariants h'
192 putMVar m h'
193 return ()
194
195 augmentIOError (IOError _ iot _ str fp) fun h
196 = IOError (Just h) iot fun str filepath
197 where filepath
198 | Just _ <- fp = fp
199 | otherwise = case h of
200 FileHandle fp _ -> Just fp
201 DuplexHandle fp _ _ -> Just fp
202
203 -- ---------------------------------------------------------------------------
204 -- Wrapper for write operations.
205
206 wantWritableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
207 wantWritableHandle fun h@(FileHandle _ m) act
208 = wantWritableHandle' fun h m act
209 wantWritableHandle fun h@(DuplexHandle _ _ m) act
210 = wantWritableHandle' fun h m act
211 -- ToDo: in the Duplex case, we don't need to checkWritableHandle
212
213 wantWritableHandle'
214 :: String -> Handle -> MVar Handle__
215 -> (Handle__ -> IO a) -> IO a
216 wantWritableHandle' fun h m act
217 = withHandle_' fun h m (checkWritableHandle act)
218
219 checkWritableHandle act handle_
220 = case haType handle_ of
221 ClosedHandle -> ioe_closedHandle
222 SemiClosedHandle -> ioe_closedHandle
223 ReadHandle -> ioe_notWritable
224 ReadWriteHandle -> do
225 let ref = haBuffer handle_
226 buf <- readIORef ref
227 new_buf <-
228 if not (bufferIsWritable buf)
229 then do b <- flushReadBuffer (haFD handle_) buf
230 return b{ bufState=WriteBuffer }
231 else return buf
232 writeIORef ref new_buf
233 act handle_
234 _other -> act handle_
235
236 -- ---------------------------------------------------------------------------
237 -- Wrapper for read operations.
238
239 wantReadableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
240 wantReadableHandle fun h@(FileHandle _ m) act
241 = wantReadableHandle' fun h m act
242 wantReadableHandle fun h@(DuplexHandle _ m _) act
243 = wantReadableHandle' fun h m act
244 -- ToDo: in the Duplex case, we don't need to checkReadableHandle
245
246 wantReadableHandle'
247 :: String -> Handle -> MVar Handle__
248 -> (Handle__ -> IO a) -> IO a
249 wantReadableHandle' fun h m act
250 = withHandle_' fun h m (checkReadableHandle act)
251
252 checkReadableHandle act handle_ =
253 case haType handle_ of
254 ClosedHandle -> ioe_closedHandle
255 SemiClosedHandle -> ioe_closedHandle
256 AppendHandle -> ioe_notReadable
257 WriteHandle -> ioe_notReadable
258 ReadWriteHandle -> do
259 let ref = haBuffer handle_
260 buf <- readIORef ref
261 when (bufferIsWritable buf) $ do
262 new_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
263 writeIORef ref new_buf{ bufState=ReadBuffer }
264 act handle_
265 _other -> act handle_
266
267 -- ---------------------------------------------------------------------------
268 -- Wrapper for seek operations.
269
270 wantSeekableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
271 wantSeekableHandle fun h@(DuplexHandle _ _ _) _act =
272 ioException (IOError (Just h) IllegalOperation fun
273 "handle is not seekable" Nothing)
274 wantSeekableHandle fun h@(FileHandle _ m) act =
275 withHandle_' fun h m (checkSeekableHandle act)
276
277 checkSeekableHandle act handle_ =
278 case haType handle_ of
279 ClosedHandle -> ioe_closedHandle
280 SemiClosedHandle -> ioe_closedHandle
281 AppendHandle -> ioe_notSeekable
282 _ | haIsBin handle_ || tEXT_MODE_SEEK_ALLOWED -> act handle_
283 | otherwise -> ioe_notSeekable_notBin
284
285 -- -----------------------------------------------------------------------------
286 -- Handy IOErrors
287
288 ioe_closedHandle, ioe_EOF,
289 ioe_notReadable, ioe_notWritable,
290 ioe_notSeekable, ioe_notSeekable_notBin :: IO a
291
292 ioe_closedHandle = ioException
293 (IOError Nothing IllegalOperation ""
294 "handle is closed" Nothing)
295 ioe_EOF = ioException
296 (IOError Nothing EOF "" "" Nothing)
297 ioe_notReadable = ioException
298 (IOError Nothing IllegalOperation ""
299 "handle is not open for reading" Nothing)
300 ioe_notWritable = ioException
301 (IOError Nothing IllegalOperation ""
302 "handle is not open for writing" Nothing)
303 ioe_notSeekable = ioException
304 (IOError Nothing IllegalOperation ""
305 "handle is not seekable" Nothing)
306 ioe_notSeekable_notBin = ioException
307 (IOError Nothing IllegalOperation ""
308 "seek operations on text-mode handles are not allowed on this platform"
309 Nothing)
310
311 ioe_finalizedHandle fp = throw (IOException
312 (IOError Nothing IllegalOperation ""
313 "handle is finalized" (Just fp)))
314
315 ioe_bufsiz :: Int -> IO a
316 ioe_bufsiz n = ioException
317 (IOError Nothing InvalidArgument "hSetBuffering"
318 ("illegal buffer size " ++ showsPrec 9 n []) Nothing)
319 -- 9 => should be parens'ified.
320
321 -- -----------------------------------------------------------------------------
322 -- Handle Finalizers
323
324 -- For a duplex handle, we arrange that the read side points to the write side
325 -- (and hence keeps it alive if the read side is alive). This is done by
326 -- having the haOtherSide field of the read side point to the read side.
327 -- The finalizer is then placed on the write side, and the handle only gets
328 -- finalized once, when both sides are no longer required.
329
330 -- NOTE about finalized handles: It's possible that a handle can be
331 -- finalized and then we try to use it later, for example if the
332 -- handle is referenced from another finalizer, or from a thread that
333 -- has become unreferenced and then resurrected (arguably in the
334 -- latter case we shouldn't finalize the Handle...). Anyway,
335 -- we try to emit a helpful message which is better than nothing.
336
337 stdHandleFinalizer :: FilePath -> MVar Handle__ -> IO ()
338 stdHandleFinalizer fp m = do
339 h_ <- takeMVar m
340 flushWriteBufferOnly h_
341 putMVar m (ioe_finalizedHandle fp)
342
343 handleFinalizer :: FilePath -> MVar Handle__ -> IO ()
344 handleFinalizer fp m = do
345 handle_ <- takeMVar m
346 case haType handle_ of
347 ClosedHandle -> return ()
348 _ -> do flushWriteBufferOnly handle_ `catchException` \_ -> return ()
349 -- ignore errors and async exceptions, and close the
350 -- descriptor anyway...
351 hClose_handle_ handle_
352 return ()
353 putMVar m (ioe_finalizedHandle fp)
354
355 -- ---------------------------------------------------------------------------
356 -- Grimy buffer operations
357
358 #ifdef DEBUG
359 checkBufferInvariants h_ = do
360 let ref = haBuffer h_
361 Buffer{ bufWPtr=w, bufRPtr=r, bufSize=size, bufState=state } <- readIORef ref
362 if not (
363 size > 0
364 && r <= w
365 && w <= size
366 && ( r /= w || (r == 0 && w == 0) )
367 && ( state /= WriteBuffer || r == 0 )
368 && ( state /= WriteBuffer || w < size ) -- write buffer is never full
369 )
370 then error "buffer invariant violation"
371 else return ()
372 #else
373 checkBufferInvariants h_ = return ()
374 #endif
375
376 newEmptyBuffer :: RawBuffer -> BufferState -> Int -> Buffer
377 newEmptyBuffer b state size
378 = Buffer{ bufBuf=b, bufRPtr=0, bufWPtr=0, bufSize=size, bufState=state }
379
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 #) }
386
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#) #)
391
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#)) #)
396
397 getBuffer :: FD -> BufferState -> IO (IORef Buffer, BufferMode)
398 getBuffer fd state = do
399 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE state
400 ioref <- newIORef buffer
401 is_tty <- fdIsTTY fd
402
403 let buffer_mode
404 | is_tty = LineBuffering
405 | otherwise = BlockBuffering Nothing
406
407 return (ioref, buffer_mode)
408
409 mkUnBuffer :: IO (IORef Buffer)
410 mkUnBuffer = do
411 buffer <- allocateBuffer 1 ReadBuffer
412 newIORef buffer
413
414 -- flushWriteBufferOnly flushes the buffer iff it contains pending write data.
415 flushWriteBufferOnly :: Handle__ -> IO ()
416 flushWriteBufferOnly h_ = do
417 let fd = haFD h_
418 ref = haBuffer h_
419 buf <- readIORef ref
420 new_buf <- if bufferIsWritable buf
421 then flushWriteBuffer fd (haIsStream h_) buf
422 else return buf
423 writeIORef ref new_buf
424
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 ()
428 flushBuffer h_ = do
429 let ref = haBuffer h_
430 buf <- readIORef ref
431
432 flushed_buf <-
433 case bufState buf of
434 ReadBuffer -> flushReadBuffer (haFD h_) buf
435 WriteBuffer -> flushWriteBuffer (haFD h_) (haIsStream h_) buf
436
437 writeIORef ref flushed_buf
438
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.
443
444 flushReadBuffer :: FD -> Buffer -> IO Buffer
445 flushReadBuffer fd buf
446 | bufferEmpty buf = return buf
447 | otherwise = do
448 let off = negate (bufWPtr buf - bufRPtr buf)
449 # ifdef DEBUG_DUMP
450 puts ("flushReadBuffer: new file offset = " ++ show off ++ "\n")
451 # endif
452 throwErrnoIfMinus1Retry "flushReadBuffer"
453 (c_lseek fd (fromIntegral off) sEEK_CUR)
454 return buf{ bufWPtr=0, bufRPtr=0 }
455
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
459 let bytes = w - r
460 #ifdef DEBUG_DUMP
461 puts ("flushWriteBuffer, fd=" ++ show fd ++ ", bytes=" ++ show bytes ++ "\n")
462 #endif
463 if bytes == 0
464 then return (buf{ bufRPtr=0, bufWPtr=0 })
465 else do
466 res <- writeRawBuffer "flushWriteBuffer" fd is_stream b
467 (fromIntegral r) (fromIntegral bytes)
468 let res' = fromIntegral res
469 if res' < bytes
470 then flushWriteBuffer fd is_stream (buf{ bufRPtr = r + res' })
471 else return buf{ bufRPtr=0, bufWPtr=0 }
472
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
479
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.
485
486 fillReadBufferLoop fd is_line is_stream buf b w size = do
487 let bytes = size - w
488 if bytes == 0 -- buffer full?
489 then return buf{ bufRPtr=0, bufWPtr=w }
490 else do
491 #ifdef DEBUG_DUMP
492 puts ("fillReadBufferLoop: bytes = " ++ show bytes ++ "\n")
493 #endif
494 res <- readRawBuffer "fillReadBuffer" fd is_stream b
495 (fromIntegral w) (fromIntegral bytes)
496 let res' = fromIntegral res
497 #ifdef DEBUG_DUMP
498 puts ("fillReadBufferLoop: res' = " ++ show res' ++ "\n")
499 #endif
500 if res' == 0
501 then if w == 0
502 then ioe_EOF
503 else return buf{ bufRPtr=0, bufWPtr=w }
504 else if res' < bytes && not is_line
505 then fillReadBufferLoop fd is_line is_stream buf b (w+res') size
506 else return buf{ bufRPtr=0, bufWPtr=w+res' }
507
508
509 fillReadBufferWithoutBlocking :: FD -> Bool -> Buffer -> IO Buffer
510 fillReadBufferWithoutBlocking fd is_stream
511 buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w, bufSize=size } =
512 -- buffer better be empty:
513 assert (r == 0 && w == 0) $ do
514 #ifdef DEBUG_DUMP
515 puts ("fillReadBufferLoopNoBlock: bytes = " ++ show size ++ "\n")
516 #endif
517 res <- readRawBufferNoBlock "fillReadBuffer" fd is_stream b
518 0 (fromIntegral size)
519 let res' = fromIntegral res
520 #ifdef DEBUG_DUMP
521 puts ("fillReadBufferLoopNoBlock: res' = " ++ show res' ++ "\n")
522 #endif
523 return buf{ bufRPtr=0, bufWPtr=res' }
524
525 -- Low level routines for reading/writing to (raw)buffers:
526
527 #ifndef mingw32_HOST_OS
528
529 {-
530 NOTE [nonblock]:
531
532 Unix has broken semantics when it comes to non-blocking I/O: you can
533 set the O_NONBLOCK flag on an FD, but it applies to the all other FDs
534 attached to the same underlying file, pipe or TTY; there's no way to
535 have private non-blocking behaviour for an FD. See bug #724.
536
537 We fix this by only setting O_NONBLOCK on FDs that we create; FDs that
538 come from external sources or are exposed externally are left in
539 blocking mode. This solution has some problems though. We can't
540 completely simulate a non-blocking read without O_NONBLOCK: several
541 cases are wrong here. The cases that are wrong:
542
543 * reading/writing to a blocking FD in non-threaded mode.
544 In threaded mode, we just make a safe call to read().
545 In non-threaded mode we call select() before attempting to read,
546 but that leaves a small race window where the data can be read
547 from the file descriptor before we issue our blocking read().
548 * readRawBufferNoBlock for a blocking FD
549 -}
550
551 readRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
552 readRawBuffer loc fd is_nonblock buf off len
553 | is_nonblock = unsafe_read
554 | threaded = safe_read
555 | otherwise = do r <- throwErrnoIfMinus1 loc
556 (fdReady (fromIntegral fd) 0 0 False)
557 if r /= 0
558 then unsafe_read
559 else do threadWaitRead (fromIntegral fd); unsafe_read
560 where
561 do_read call = throwErrnoIfMinus1RetryMayBlock loc call
562 (threadWaitRead (fromIntegral fd))
563 unsafe_read = do_read (read_rawBuffer fd buf off len)
564 safe_read = do_read (safe_read_rawBuffer fd buf off len)
565
566 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
567 readRawBufferPtr loc fd is_nonblock buf off len
568 | is_nonblock = unsafe_read
569 | threaded = safe_read
570 | otherwise = do r <- throwErrnoIfMinus1 loc
571 (fdReady (fromIntegral fd) 0 0 False)
572 if r /= 0
573 then unsafe_read
574 else do threadWaitRead (fromIntegral fd); unsafe_read
575 where
576 do_read call = throwErrnoIfMinus1RetryMayBlock loc call
577 (threadWaitRead (fromIntegral fd))
578 unsafe_read = do_read (read_off fd buf off len)
579 safe_read = do_read (safe_read_off fd buf off len)
580
581 readRawBufferNoBlock :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
582 readRawBufferNoBlock loc fd is_nonblock buf off len
583 | is_nonblock = unsafe_read
584 | otherwise = do r <- fdReady (fromIntegral fd) 0 0 False
585 if r /= 0 then safe_read
586 else return 0
587 -- XXX see note [nonblock]
588 where
589 do_read call = throwErrnoIfMinus1RetryOnBlock loc call (return 0)
590 unsafe_read = do_read (read_rawBuffer fd buf off len)
591 safe_read = do_read (safe_read_rawBuffer fd buf off len)
592
593 readRawBufferPtrNoBlock :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
594 readRawBufferPtrNoBlock loc fd is_nonblock buf off len
595 | is_nonblock = unsafe_read
596 | otherwise = do r <- fdReady (fromIntegral fd) 0 0 False
597 if r /= 0 then safe_read
598 else return 0
599 -- XXX see note [nonblock]
600 where
601 do_read call = throwErrnoIfMinus1RetryOnBlock loc call (return 0)
602 unsafe_read = do_read (read_off fd buf off len)
603 safe_read = do_read (safe_read_off fd buf off len)
604
605 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
606 writeRawBuffer loc fd is_nonblock buf off len
607 | is_nonblock = unsafe_write
608 | threaded = safe_write
609 | otherwise = do r <- fdReady (fromIntegral fd) 1 0 False
610 if r /= 0
611 then safe_write
612 else do threadWaitWrite (fromIntegral fd); unsafe_write
613 where
614 do_write call = throwErrnoIfMinus1RetryMayBlock loc call
615 (threadWaitWrite (fromIntegral fd))
616 unsafe_write = do_write (write_rawBuffer fd buf off len)
617 safe_write = do_write (safe_write_rawBuffer (fromIntegral fd) buf off len)
618
619 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
620 writeRawBufferPtr loc fd is_nonblock buf off len
621 | is_nonblock = unsafe_write
622 | threaded = safe_write
623 | otherwise = do r <- fdReady (fromIntegral fd) 1 0 False
624 if r /= 0
625 then safe_write
626 else do threadWaitWrite (fromIntegral fd); unsafe_write
627 where
628 do_write call = throwErrnoIfMinus1RetryMayBlock loc call
629 (threadWaitWrite (fromIntegral fd))
630 unsafe_write = do_write (write_off fd buf off len)
631 safe_write = do_write (safe_write_off (fromIntegral fd) buf off len)
632
633 foreign import ccall unsafe "__hscore_PrelHandle_read"
634 read_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
635
636 foreign import ccall unsafe "__hscore_PrelHandle_read"
637 read_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
638
639 foreign import ccall unsafe "__hscore_PrelHandle_write"
640 write_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
641
642 foreign import ccall unsafe "__hscore_PrelHandle_write"
643 write_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
644
645 foreign import ccall safe "fdReady"
646 fdReady :: CInt -> CInt -> CInt -> Bool -> IO CInt
647
648 #else /* mingw32_HOST_OS.... */
649
650 readRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
651 readRawBuffer loc fd is_stream buf off len
652 | threaded = blockingReadRawBuffer loc fd is_stream buf off len
653 | otherwise = asyncReadRawBuffer loc fd is_stream buf off len
654
655 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
656 readRawBufferPtr loc fd is_stream buf off len
657 | threaded = blockingReadRawBufferPtr loc fd is_stream buf off len
658 | otherwise = asyncReadRawBufferPtr loc fd is_stream buf off len
659
660 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
661 writeRawBuffer loc fd is_stream buf off len
662 | threaded = blockingWriteRawBuffer loc fd is_stream buf off len
663 | otherwise = asyncWriteRawBuffer loc fd is_stream buf off len
664
665 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
666 writeRawBufferPtr loc fd is_stream buf off len
667 | threaded = blockingWriteRawBufferPtr loc fd is_stream buf off len
668 | otherwise = asyncWriteRawBufferPtr loc fd is_stream buf off len
669
670 -- ToDo: we don't have a non-blocking primitve read on Win32
671 readRawBufferNoBlock :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
672 readRawBufferNoBlock = readRawBuffer
673
674 readRawBufferPtrNoBlock :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
675 readRawBufferPtrNoBlock = readRawBufferPtr
676 -- Async versions of the read/write primitives, for the non-threaded RTS
677
678 asyncReadRawBuffer loc fd is_stream buf off len = do
679 (l, rc) <- asyncReadBA (fromIntegral fd) (if is_stream then 1 else 0)
680 (fromIntegral len) off buf
681 if l == (-1)
682 then
683 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
684 else return (fromIntegral l)
685
686 asyncReadRawBufferPtr loc fd is_stream buf off len = do
687 (l, rc) <- asyncRead (fromIntegral fd) (if is_stream then 1 else 0)
688 (fromIntegral len) (buf `plusPtr` off)
689 if l == (-1)
690 then
691 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
692 else return (fromIntegral l)
693
694 asyncWriteRawBuffer loc fd is_stream buf off len = do
695 (l, rc) <- asyncWriteBA (fromIntegral fd) (if is_stream then 1 else 0)
696 (fromIntegral len) off buf
697 if l == (-1)
698 then
699 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
700 else return (fromIntegral l)
701
702 asyncWriteRawBufferPtr loc fd is_stream buf off len = do
703 (l, rc) <- asyncWrite (fromIntegral fd) (if is_stream then 1 else 0)
704 (fromIntegral len) (buf `plusPtr` off)
705 if l == (-1)
706 then
707 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
708 else return (fromIntegral l)
709
710 -- Blocking versions of the read/write primitives, for the threaded RTS
711
712 blockingReadRawBuffer loc fd True buf off len =
713 throwErrnoIfMinus1Retry loc $
714 safe_recv_rawBuffer fd buf off len
715 blockingReadRawBuffer loc fd False buf off len =
716 throwErrnoIfMinus1Retry loc $
717 safe_read_rawBuffer fd buf off len
718
719 blockingReadRawBufferPtr loc fd True buf off len =
720 throwErrnoIfMinus1Retry loc $
721 safe_recv_off fd buf off len
722 blockingReadRawBufferPtr loc fd False buf off len =
723 throwErrnoIfMinus1Retry loc $
724 safe_read_off fd buf off len
725
726 blockingWriteRawBuffer loc fd True buf off len =
727 throwErrnoIfMinus1Retry loc $
728 safe_send_rawBuffer fd buf off len
729 blockingWriteRawBuffer loc fd False buf off len =
730 throwErrnoIfMinus1Retry loc $
731 safe_write_rawBuffer fd buf off len
732
733 blockingWriteRawBufferPtr loc fd True buf off len =
734 throwErrnoIfMinus1Retry loc $
735 safe_send_off fd buf off len
736 blockingWriteRawBufferPtr loc fd False buf off len =
737 throwErrnoIfMinus1Retry loc $
738 safe_write_off fd buf off len
739
740 -- NOTE: "safe" versions of the read/write calls for use by the threaded RTS.
741 -- These calls may block, but that's ok.
742
743 foreign import ccall safe "__hscore_PrelHandle_recv"
744 safe_recv_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
745
746 foreign import ccall safe "__hscore_PrelHandle_recv"
747 safe_recv_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
748
749 foreign import ccall safe "__hscore_PrelHandle_send"
750 safe_send_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
751
752 foreign import ccall safe "__hscore_PrelHandle_send"
753 safe_send_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
754
755 #endif
756
757 foreign import ccall "rtsSupportsBoundThreads" threaded :: Bool
758
759 foreign import ccall safe "__hscore_PrelHandle_read"
760 safe_read_rawBuffer :: FD -> RawBuffer -> Int -> CInt -> IO CInt
761
762 foreign import ccall safe "__hscore_PrelHandle_read"
763 safe_read_off :: FD -> Ptr CChar -> Int -> CInt -> IO CInt
764
765 foreign import ccall safe "__hscore_PrelHandle_write"
766 safe_write_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
767
768 foreign import ccall safe "__hscore_PrelHandle_write"
769 safe_write_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
770
771 -- ---------------------------------------------------------------------------
772 -- Standard Handles
773
774 -- Three handles are allocated during program initialisation. The first
775 -- two manage input or output from the Haskell program's standard input
776 -- or output channel respectively. The third manages output to the
777 -- standard error channel. These handles are initially open.
778
779 fd_stdin = 0 :: FD
780 fd_stdout = 1 :: FD
781 fd_stderr = 2 :: FD
782
783 -- | A handle managing input from the Haskell program's standard input channel.
784 stdin :: Handle
785 stdin = unsafePerformIO $ do
786 -- ToDo: acquire lock
787 -- We don't set non-blocking mode on standard handles, because it may
788 -- confuse other applications attached to the same TTY/pipe
789 -- see Note [nonblock]
790 (buf, bmode) <- getBuffer fd_stdin ReadBuffer
791 mkStdHandle fd_stdin "<stdin>" ReadHandle buf bmode
792
793 -- | A handle managing output to the Haskell program's standard output channel.
794 stdout :: Handle
795 stdout = unsafePerformIO $ do
796 -- ToDo: acquire lock
797 -- We don't set non-blocking mode on standard handles, because it may
798 -- confuse other applications attached to the same TTY/pipe
799 -- see Note [nonblock]
800 (buf, bmode) <- getBuffer fd_stdout WriteBuffer
801 mkStdHandle fd_stdout "<stdout>" WriteHandle buf bmode
802
803 -- | A handle managing output to the Haskell program's standard error channel.
804 stderr :: Handle
805 stderr = unsafePerformIO $ do
806 -- ToDo: acquire lock
807 -- We don't set non-blocking mode on standard handles, because it may
808 -- confuse other applications attached to the same TTY/pipe
809 -- see Note [nonblock]
810 buf <- mkUnBuffer
811 mkStdHandle fd_stderr "<stderr>" WriteHandle buf NoBuffering
812
813 -- ---------------------------------------------------------------------------
814 -- Opening and Closing Files
815
816 addFilePathToIOError fun fp (IOError h iot _ str _)
817 = IOError h iot fun str (Just fp)
818
819 -- | Computation 'openFile' @file mode@ allocates and returns a new, open
820 -- handle to manage the file @file@. It manages input if @mode@
821 -- is 'ReadMode', output if @mode@ is 'WriteMode' or 'AppendMode',
822 -- and both input and output if mode is 'ReadWriteMode'.
823 --
824 -- If the file does not exist and it is opened for output, it should be
825 -- created as a new file. If @mode@ is 'WriteMode' and the file
826 -- already exists, then it should be truncated to zero length.
827 -- Some operating systems delete empty files, so there is no guarantee
828 -- that the file will exist following an 'openFile' with @mode@
829 -- 'WriteMode' unless it is subsequently written to successfully.
830 -- The handle is positioned at the end of the file if @mode@ is
831 -- 'AppendMode', and otherwise at the beginning (in which case its
832 -- internal position is 0).
833 -- The initial buffer mode is implementation-dependent.
834 --
835 -- This operation may fail with:
836 --
837 -- * 'isAlreadyInUseError' if the file is already open and cannot be reopened;
838 --
839 -- * 'isDoesNotExistError' if the file does not exist; or
840 --
841 -- * 'isPermissionError' if the user does not have permission to open the file.
842 --
843 -- Note: if you will be working with files containing binary data, you'll want to
844 -- be using 'openBinaryFile'.
845 openFile :: FilePath -> IOMode -> IO Handle
846 openFile fp im =
847 catch
848 (openFile' fp im dEFAULT_OPEN_IN_BINARY_MODE)
849 (\e -> ioError (addFilePathToIOError "openFile" fp e))
850
851 -- | Like 'openFile', but open the file in binary mode.
852 -- On Windows, reading a file in text mode (which is the default)
853 -- will translate CRLF to LF, and writing will translate LF to CRLF.
854 -- This is usually what you want with text files. With binary files
855 -- this is undesirable; also, as usual under Microsoft operating systems,
856 -- text mode treats control-Z as EOF. Binary mode turns off all special
857 -- treatment of end-of-line and end-of-file characters.
858 -- (See also 'hSetBinaryMode'.)
859
860 openBinaryFile :: FilePath -> IOMode -> IO Handle
861 openBinaryFile fp m =
862 catch
863 (openFile' fp m True)
864 (\e -> ioError (addFilePathToIOError "openBinaryFile" fp e))
865
866 openFile' filepath mode binary =
867 withCString filepath $ \ f ->
868
869 let
870 oflags1 = case mode of
871 ReadMode -> read_flags
872 #ifdef mingw32_HOST_OS
873 WriteMode -> write_flags .|. o_TRUNC
874 #else
875 WriteMode -> write_flags
876 #endif
877 ReadWriteMode -> rw_flags
878 AppendMode -> append_flags
879
880 binary_flags
881 | binary = o_BINARY
882 | otherwise = 0
883
884 oflags = oflags1 .|. binary_flags
885 in do
886
887 -- the old implementation had a complicated series of three opens,
888 -- which is perhaps because we have to be careful not to open
889 -- directories. However, the man pages I've read say that open()
890 -- always returns EISDIR if the file is a directory and was opened
891 -- for writing, so I think we're ok with a single open() here...
892 fd <- throwErrnoIfMinus1Retry "openFile"
893 (c_open f (fromIntegral oflags) 0o666)
894
895 stat@(fd_type,_,_) <- fdStat fd
896
897 h <- fdToHandle_stat fd (Just stat) False filepath mode binary
898 `catchException` \e -> do c_close fd; throw e
899 -- NB. don't forget to close the FD if fdToHandle' fails, otherwise
900 -- this FD leaks.
901 -- ASSERT: if we just created the file, then fdToHandle' won't fail
902 -- (so we don't need to worry about removing the newly created file
903 -- in the event of an error).
904
905 #ifndef mingw32_HOST_OS
906 -- we want to truncate() if this is an open in WriteMode, but only
907 -- if the target is a RegularFile. ftruncate() fails on special files
908 -- like /dev/null.
909 if mode == WriteMode && fd_type == RegularFile
910 then throwErrnoIf (/=0) "openFile"
911 (c_ftruncate fd 0)
912 else return 0
913 #endif
914 return h
915
916
917 std_flags = o_NONBLOCK .|. o_NOCTTY
918 output_flags = std_flags .|. o_CREAT
919 read_flags = std_flags .|. o_RDONLY
920 write_flags = output_flags .|. o_WRONLY
921 rw_flags = output_flags .|. o_RDWR
922 append_flags = write_flags .|. o_APPEND
923
924 -- ---------------------------------------------------------------------------
925 -- fdToHandle
926
927 fdToHandle_stat :: FD
928 -> Maybe (FDType, CDev, CIno)
929 -> Bool
930 -> FilePath
931 -> IOMode
932 -> Bool
933 -> IO Handle
934
935 fdToHandle_stat fd mb_stat is_socket filepath mode binary = do
936
937 #ifdef mingw32_HOST_OS
938 -- On Windows, the is_socket flag indicates that the Handle is a socket
939 #else
940 -- On Unix, the is_socket flag indicates that the FD can be made non-blocking
941 let non_blocking = is_socket
942
943 when non_blocking $ setNonBlockingFD fd
944 -- turn on non-blocking mode
945 #endif
946
947 let (ha_type, write) =
948 case mode of
949 ReadMode -> ( ReadHandle, False )
950 WriteMode -> ( WriteHandle, True )
951 ReadWriteMode -> ( ReadWriteHandle, True )
952 AppendMode -> ( AppendHandle, True )
953
954 -- open() won't tell us if it was a directory if we only opened for
955 -- reading, so check again.
956 (fd_type,dev,ino) <-
957 case mb_stat of
958 Just x -> return x
959 Nothing -> fdStat fd
960
961 case fd_type of
962 Directory ->
963 ioException (IOError Nothing InappropriateType "openFile"
964 "is a directory" Nothing)
965
966 -- regular files need to be locked
967 RegularFile -> do
968 #ifndef mingw32_HOST_OS
969 r <- lockFile fd dev ino (fromBool write)
970 when (r == -1) $
971 ioException (IOError Nothing ResourceBusy "openFile"
972 "file is locked" Nothing)
973 #endif
974 mkFileHandle fd is_socket filepath ha_type binary
975
976 Stream
977 -- only *Streams* can be DuplexHandles. Other read/write
978 -- Handles must share a buffer.
979 | ReadWriteHandle <- ha_type ->
980 mkDuplexHandle fd is_socket filepath binary
981 | otherwise ->
982 mkFileHandle fd is_socket filepath ha_type binary
983
984 RawDevice ->
985 mkFileHandle fd is_socket filepath ha_type binary
986
987 -- | Old API kept to avoid breaking clients
988 fdToHandle' :: FD -> Maybe FDType -> Bool -> FilePath -> IOMode -> Bool
989 -> IO Handle
990 fdToHandle' fd mb_type is_socket filepath mode binary
991 = do
992 let mb_stat = case mb_type of
993 Nothing -> Nothing
994 -- fdToHandle_stat will do the stat:
995 Just RegularFile -> Nothing
996 -- no stat required for streams etc.:
997 Just other -> Just (other,0,0)
998 fdToHandle_stat fd mb_stat is_socket filepath mode binary
999
1000 fdToHandle :: FD -> IO Handle
1001 fdToHandle fd = do
1002 mode <- fdGetMode fd
1003 let fd_str = "<file descriptor: " ++ show fd ++ ">"
1004 fdToHandle_stat fd Nothing False fd_str mode True{-bin mode-}
1005 -- NB. the is_socket flag is False, meaning that:
1006 -- on Unix the file descriptor will *not* be put in non-blocking mode
1007 -- on Windows we're guessing this is not a socket (XXX)
1008
1009 #ifndef mingw32_HOST_OS
1010 foreign import ccall unsafe "lockFile"
1011 lockFile :: CInt -> CDev -> CIno -> CInt -> IO CInt
1012
1013 foreign import ccall unsafe "unlockFile"
1014 unlockFile :: CInt -> IO CInt
1015 #endif
1016
1017 mkStdHandle :: FD -> FilePath -> HandleType -> IORef Buffer -> BufferMode
1018 -> IO Handle
1019 mkStdHandle fd filepath ha_type buf bmode = do
1020 spares <- newIORef BufferListNil
1021 newFileHandle filepath (stdHandleFinalizer filepath)
1022 (Handle__ { haFD = fd,
1023 haType = ha_type,
1024 haIsBin = dEFAULT_OPEN_IN_BINARY_MODE,
1025 haIsStream = False, -- means FD is blocking on Unix
1026 haBufferMode = bmode,
1027 haBuffer = buf,
1028 haBuffers = spares,
1029 haOtherSide = Nothing
1030 })
1031
1032 mkFileHandle :: FD -> Bool -> FilePath -> HandleType -> Bool -> IO Handle
1033 mkFileHandle fd is_stream filepath ha_type binary = do
1034 (buf, bmode) <- getBuffer fd (initBufferState ha_type)
1035
1036 #ifdef mingw32_HOST_OS
1037 -- On Windows, if this is a read/write handle and we are in text mode,
1038 -- turn off buffering. We don't correctly handle the case of switching
1039 -- from read mode to write mode on a buffered text-mode handle, see bug
1040 -- \#679.
1041 bmode <- case ha_type of
1042 ReadWriteHandle | not binary -> return NoBuffering
1043 _other -> return bmode
1044 #endif
1045
1046 spares <- newIORef BufferListNil
1047 newFileHandle filepath (handleFinalizer filepath)
1048 (Handle__ { haFD = fd,
1049 haType = ha_type,
1050 haIsBin = binary,
1051 haIsStream = is_stream,
1052 haBufferMode = bmode,
1053 haBuffer = buf,
1054 haBuffers = spares,
1055 haOtherSide = Nothing
1056 })
1057
1058 mkDuplexHandle :: FD -> Bool -> FilePath -> Bool -> IO Handle
1059 mkDuplexHandle fd is_stream filepath binary = do
1060 (w_buf, w_bmode) <- getBuffer fd WriteBuffer
1061 w_spares <- newIORef BufferListNil
1062 let w_handle_ =
1063 Handle__ { haFD = fd,
1064 haType = WriteHandle,
1065 haIsBin = binary,
1066 haIsStream = is_stream,
1067 haBufferMode = w_bmode,
1068 haBuffer = w_buf,
1069 haBuffers = w_spares,
1070 haOtherSide = Nothing
1071 }
1072 write_side <- newMVar w_handle_
1073
1074 (r_buf, r_bmode) <- getBuffer fd ReadBuffer
1075 r_spares <- newIORef BufferListNil
1076 let r_handle_ =
1077 Handle__ { haFD = fd,
1078 haType = ReadHandle,
1079 haIsBin = binary,
1080 haIsStream = is_stream,
1081 haBufferMode = r_bmode,
1082 haBuffer = r_buf,
1083 haBuffers = r_spares,
1084 haOtherSide = Just write_side
1085 }
1086 read_side <- newMVar r_handle_
1087
1088 addMVarFinalizer write_side (handleFinalizer filepath write_side)
1089 return (DuplexHandle filepath read_side write_side)
1090
1091
1092 initBufferState ReadHandle = ReadBuffer
1093 initBufferState _ = WriteBuffer
1094
1095 -- ---------------------------------------------------------------------------
1096 -- Closing a handle
1097
1098 -- | Computation 'hClose' @hdl@ makes handle @hdl@ closed. Before the
1099 -- computation finishes, if @hdl@ is writable its buffer is flushed as
1100 -- for 'hFlush'.
1101 -- Performing 'hClose' on a handle that has already been closed has no effect;
1102 -- doing so is not an error. All other operations on a closed handle will fail.
1103 -- If 'hClose' fails for any reason, any further operations (apart from
1104 -- 'hClose') on the handle will still fail as if @hdl@ had been successfully
1105 -- closed.
1106
1107 hClose :: Handle -> IO ()
1108 hClose h@(FileHandle _ m) = do
1109 mb_exc <- hClose' h m
1110 case mb_exc of
1111 Nothing -> return ()
1112 Just e -> throwIO e
1113 hClose h@(DuplexHandle _ r w) = do
1114 mb_exc1 <- hClose' h w
1115 mb_exc2 <- hClose' h r
1116 case (do mb_exc1; mb_exc2) of
1117 Nothing -> return ()
1118 Just e -> throwIO e
1119
1120 hClose' h m = withHandle' "hClose" h m $ hClose_help
1121
1122 -- hClose_help is also called by lazyRead (in PrelIO) when EOF is read
1123 -- or an IO error occurs on a lazy stream. The semi-closed Handle is
1124 -- then closed immediately. We have to be careful with DuplexHandles
1125 -- though: we have to leave the closing to the finalizer in that case,
1126 -- because the write side may still be in use.
1127 hClose_help :: Handle__ -> IO (Handle__, Maybe Exception)
1128 hClose_help handle_ =
1129 case haType handle_ of
1130 ClosedHandle -> return (handle_,Nothing)
1131 _ -> do flushWriteBufferOnly handle_ -- interruptible
1132 hClose_handle_ handle_
1133
1134 hClose_handle_ handle_ = do
1135 let fd = haFD handle_
1136
1137 -- close the file descriptor, but not when this is the read
1138 -- side of a duplex handle.
1139 -- If an exception is raised by the close(), we want to continue
1140 -- to close the handle and release the lock if it has one, then
1141 -- we return the exception to the caller of hClose_help which can
1142 -- raise it if necessary.
1143 maybe_exception <-
1144 case haOtherSide handle_ of
1145 Nothing -> (do
1146 throwErrnoIfMinus1Retry_ "hClose"
1147 #ifdef mingw32_HOST_OS
1148 (closeFd (haIsStream handle_) fd)
1149 #else
1150 (c_close fd)
1151 #endif
1152 return Nothing
1153 )
1154 `catchException` \e -> return (Just e)
1155
1156 Just _ -> return Nothing
1157
1158 -- free the spare buffers
1159 writeIORef (haBuffers handle_) BufferListNil
1160 writeIORef (haBuffer handle_) noBuffer
1161
1162 #ifndef mingw32_HOST_OS
1163 -- unlock it
1164 unlockFile fd
1165 #endif
1166
1167 -- we must set the fd to -1, because the finalizer is going
1168 -- to run eventually and try to close/unlock it.
1169 return (handle_{ haFD = -1,
1170 haType = ClosedHandle
1171 },
1172 maybe_exception)
1173
1174 {-# NOINLINE noBuffer #-}
1175 noBuffer = unsafePerformIO $ allocateBuffer 1 ReadBuffer
1176
1177 -----------------------------------------------------------------------------
1178 -- Detecting and changing the size of a file
1179
1180 -- | For a handle @hdl@ which attached to a physical file,
1181 -- 'hFileSize' @hdl@ returns the size of that file in 8-bit bytes.
1182
1183 hFileSize :: Handle -> IO Integer
1184 hFileSize handle =
1185 withHandle_ "hFileSize" handle $ \ handle_ -> do
1186 case haType handle_ of
1187 ClosedHandle -> ioe_closedHandle
1188 SemiClosedHandle -> ioe_closedHandle
1189 _ -> do flushWriteBufferOnly handle_
1190 r <- fdFileSize (haFD handle_)
1191 if r /= -1
1192 then return r
1193 else ioException (IOError Nothing InappropriateType "hFileSize"
1194 "not a regular file" Nothing)
1195
1196
1197 -- | 'hSetFileSize' @hdl@ @size@ truncates the physical file with handle @hdl@ to @size@ bytes.
1198
1199 hSetFileSize :: Handle -> Integer -> IO ()
1200 hSetFileSize handle size =
1201 withHandle_ "hSetFileSize" handle $ \ handle_ -> do
1202 case haType handle_ of
1203 ClosedHandle -> ioe_closedHandle
1204 SemiClosedHandle -> ioe_closedHandle
1205 _ -> do flushWriteBufferOnly handle_
1206 throwErrnoIf (/=0) "hSetFileSize"
1207 (c_ftruncate (haFD handle_) (fromIntegral size))
1208 return ()
1209
1210 -- ---------------------------------------------------------------------------
1211 -- Detecting the End of Input
1212
1213 -- | For a readable handle @hdl@, 'hIsEOF' @hdl@ returns
1214 -- 'True' if no further input can be taken from @hdl@ or for a
1215 -- physical file, if the current I\/O position is equal to the length of
1216 -- the file. Otherwise, it returns 'False'.
1217 --
1218 -- NOTE: 'hIsEOF' may block, because it is the same as calling
1219 -- 'hLookAhead' and checking for an EOF exception.
1220
1221 hIsEOF :: Handle -> IO Bool
1222 hIsEOF handle =
1223 catch
1224 (do hLookAhead handle; return False)
1225 (\e -> if isEOFError e then return True else ioError e)
1226
1227 -- | The computation 'isEOF' is identical to 'hIsEOF',
1228 -- except that it works only on 'stdin'.
1229
1230 isEOF :: IO Bool
1231 isEOF = hIsEOF stdin
1232
1233 -- ---------------------------------------------------------------------------
1234 -- Looking ahead
1235
1236 -- | Computation 'hLookAhead' returns the next character from the handle
1237 -- without removing it from the input buffer, blocking until a character
1238 -- is available.
1239 --
1240 -- This operation may fail with:
1241 --
1242 -- * 'isEOFError' if the end of file has been reached.
1243
1244 hLookAhead :: Handle -> IO Char
1245 hLookAhead handle = do
1246 wantReadableHandle "hLookAhead" handle $ \handle_ -> do
1247 let ref = haBuffer handle_
1248 fd = haFD handle_
1249 is_line = haBufferMode handle_ == LineBuffering
1250 buf <- readIORef ref
1251
1252 -- fill up the read buffer if necessary
1253 new_buf <- if bufferEmpty buf
1254 then fillReadBuffer fd True (haIsStream handle_) buf
1255 else return buf
1256
1257 writeIORef ref new_buf
1258
1259 (c,_) <- readCharFromBuffer (bufBuf buf) (bufRPtr buf)
1260 return c
1261
1262 -- ---------------------------------------------------------------------------
1263 -- Buffering Operations
1264
1265 -- Three kinds of buffering are supported: line-buffering,
1266 -- block-buffering or no-buffering. See GHC.IOBase for definition and
1267 -- further explanation of what the type represent.
1268
1269 -- | Computation 'hSetBuffering' @hdl mode@ sets the mode of buffering for
1270 -- handle @hdl@ on subsequent reads and writes.
1271 --
1272 -- If the buffer mode is changed from 'BlockBuffering' or
1273 -- 'LineBuffering' to 'NoBuffering', then
1274 --
1275 -- * if @hdl@ is writable, the buffer is flushed as for 'hFlush';
1276 --
1277 -- * if @hdl@ is not writable, the contents of the buffer is discarded.
1278 --
1279 -- This operation may fail with:
1280 --
1281 -- * 'isPermissionError' if the handle has already been used for reading
1282 -- or writing and the implementation does not allow the buffering mode
1283 -- to be changed.
1284
1285 hSetBuffering :: Handle -> BufferMode -> IO ()
1286 hSetBuffering handle mode =
1287 withAllHandles__ "hSetBuffering" handle $ \ handle_ -> do
1288 case haType handle_ of
1289 ClosedHandle -> ioe_closedHandle
1290 _ -> do
1291 {- Note:
1292 - we flush the old buffer regardless of whether
1293 the new buffer could fit the contents of the old buffer
1294 or not.
1295 - allow a handle's buffering to change even if IO has
1296 occurred (ANSI C spec. does not allow this, nor did
1297 the previous implementation of IO.hSetBuffering).
1298 - a non-standard extension is to allow the buffering
1299 of semi-closed handles to change [sof 6/98]
1300 -}
1301 flushBuffer handle_
1302
1303 let state = initBufferState (haType handle_)
1304 new_buf <-
1305 case mode of
1306 -- we always have a 1-character read buffer for
1307 -- unbuffered handles: it's needed to
1308 -- support hLookAhead.
1309 NoBuffering -> allocateBuffer 1 ReadBuffer
1310 LineBuffering -> allocateBuffer dEFAULT_BUFFER_SIZE state
1311 BlockBuffering Nothing -> allocateBuffer dEFAULT_BUFFER_SIZE state
1312 BlockBuffering (Just n) | n <= 0 -> ioe_bufsiz n
1313 | otherwise -> allocateBuffer n state
1314 writeIORef (haBuffer handle_) new_buf
1315
1316 -- for input terminals we need to put the terminal into
1317 -- cooked or raw mode depending on the type of buffering.
1318 is_tty <- fdIsTTY (haFD handle_)
1319 when (is_tty && isReadableHandleType (haType handle_)) $
1320 case mode of
1321 #ifndef mingw32_HOST_OS
1322 -- 'raw' mode under win32 is a bit too specialised (and troublesome
1323 -- for most common uses), so simply disable its use here.
1324 NoBuffering -> setCooked (haFD handle_) False
1325 #else
1326 NoBuffering -> return ()
1327 #endif
1328 _ -> setCooked (haFD handle_) True
1329
1330 -- throw away spare buffers, they might be the wrong size
1331 writeIORef (haBuffers handle_) BufferListNil
1332
1333 return (handle_{ haBufferMode = mode })
1334
1335 -- -----------------------------------------------------------------------------
1336 -- hFlush
1337
1338 -- | The action 'hFlush' @hdl@ causes any items buffered for output
1339 -- in handle @hdl@ to be sent immediately to the operating system.
1340 --
1341 -- This operation may fail with:
1342 --
1343 -- * 'isFullError' if the device is full;
1344 --
1345 -- * 'isPermissionError' if a system resource limit would be exceeded.
1346 -- It is unspecified whether the characters in the buffer are discarded
1347 -- or retained under these circumstances.
1348
1349 hFlush :: Handle -> IO ()
1350 hFlush handle =
1351 wantWritableHandle "hFlush" handle $ \ handle_ -> do
1352 buf <- readIORef (haBuffer handle_)
1353 if bufferIsWritable buf && not (bufferEmpty buf)
1354 then do flushed_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
1355 writeIORef (haBuffer handle_) flushed_buf
1356 else return ()
1357
1358
1359 -- -----------------------------------------------------------------------------
1360 -- Repositioning Handles
1361
1362 data HandlePosn = HandlePosn Handle HandlePosition
1363
1364 instance Eq HandlePosn where
1365 (HandlePosn h1 p1) == (HandlePosn h2 p2) = p1==p2 && h1==h2
1366
1367 instance Show HandlePosn where
1368 showsPrec p (HandlePosn h pos) =
1369 showsPrec p h . showString " at position " . shows pos
1370
1371 -- HandlePosition is the Haskell equivalent of POSIX' off_t.
1372 -- We represent it as an Integer on the Haskell side, but
1373 -- cheat slightly in that hGetPosn calls upon a C helper
1374 -- that reports the position back via (merely) an Int.
1375 type HandlePosition = Integer
1376
1377 -- | Computation 'hGetPosn' @hdl@ returns the current I\/O position of
1378 -- @hdl@ as a value of the abstract type 'HandlePosn'.
1379
1380 hGetPosn :: Handle -> IO HandlePosn
1381 hGetPosn handle = do
1382 posn <- hTell handle
1383 return (HandlePosn handle posn)
1384
1385 -- | If a call to 'hGetPosn' @hdl@ returns a position @p@,
1386 -- then computation 'hSetPosn' @p@ sets the position of @hdl@
1387 -- to the position it held at the time of the call to 'hGetPosn'.
1388 --
1389 -- This operation may fail with:
1390 --
1391 -- * 'isPermissionError' if a system resource limit would be exceeded.
1392
1393 hSetPosn :: HandlePosn -> IO ()
1394 hSetPosn (HandlePosn h i) = hSeek h AbsoluteSeek i
1395
1396 -- ---------------------------------------------------------------------------
1397 -- hSeek
1398
1399 -- | A mode that determines the effect of 'hSeek' @hdl mode i@, as follows:
1400 data SeekMode
1401 = AbsoluteSeek -- ^ the position of @hdl@ is set to @i@.
1402 | RelativeSeek -- ^ the position of @hdl@ is set to offset @i@
1403 -- from the current position.
1404 | SeekFromEnd -- ^ the position of @hdl@ is set to offset @i@
1405 -- from the end of the file.
1406 deriving (Eq, Ord, Ix, Enum, Read, Show)
1407
1408 {- Note:
1409 - when seeking using `SeekFromEnd', positive offsets (>=0) means
1410 seeking at or past EOF.
1411
1412 - we possibly deviate from the report on the issue of seeking within
1413 the buffer and whether to flush it or not. The report isn't exactly
1414 clear here.
1415 -}
1416
1417 -- | Computation 'hSeek' @hdl mode i@ sets the position of handle
1418 -- @hdl@ depending on @mode@.
1419 -- The offset @i@ is given in terms of 8-bit bytes.
1420 --
1421 -- If @hdl@ is block- or line-buffered, then seeking to a position which is not
1422 -- in the current buffer will first cause any items in the output buffer to be
1423 -- written to the device, and then cause the input buffer to be discarded.
1424 -- Some handles may not be seekable (see 'hIsSeekable'), or only support a
1425 -- subset of the possible positioning operations (for instance, it may only
1426 -- be possible to seek to the end of a tape, or to a positive offset from
1427 -- the beginning or current position).
1428 -- It is not possible to set a negative I\/O position, or for
1429 -- a physical file, an I\/O position beyond the current end-of-file.
1430 --
1431 -- This operation may fail with:
1432 --
1433 -- * 'isPermissionError' if a system resource limit would be exceeded.
1434
1435 hSeek :: Handle -> SeekMode -> Integer -> IO ()
1436 hSeek handle mode offset =
1437 wantSeekableHandle "hSeek" handle $ \ handle_ -> do
1438 # ifdef DEBUG_DUMP
1439 puts ("hSeek " ++ show (mode,offset) ++ "\n")
1440 # endif
1441 let ref = haBuffer handle_
1442 buf <- readIORef ref
1443 let r = bufRPtr buf
1444 w = bufWPtr buf
1445 fd = haFD handle_
1446
1447 let do_seek =
1448 throwErrnoIfMinus1Retry_ "hSeek"
1449 (c_lseek (haFD handle_) (fromIntegral offset) whence)
1450
1451 whence :: CInt
1452 whence = case mode of
1453 AbsoluteSeek -> sEEK_SET
1454 RelativeSeek -> sEEK_CUR
1455 SeekFromEnd -> sEEK_END
1456
1457 if bufferIsWritable buf
1458 then do new_buf <- flushWriteBuffer fd (haIsStream handle_) buf
1459 writeIORef ref new_buf
1460 do_seek
1461 else do
1462
1463 if mode == RelativeSeek && offset >= 0 && offset < fromIntegral (w - r)
1464 then writeIORef ref buf{ bufRPtr = r + fromIntegral offset }
1465 else do
1466
1467 new_buf <- flushReadBuffer (haFD handle_) buf
1468 writeIORef ref new_buf
1469 do_seek
1470
1471
1472 hTell :: Handle -> IO Integer
1473 hTell handle =
1474 wantSeekableHandle "hGetPosn" handle $ \ handle_ -> do
1475
1476 #if defined(mingw32_HOST_OS)
1477 -- urgh, on Windows we have to worry about \n -> \r\n translation,
1478 -- so we can't easily calculate the file position using the
1479 -- current buffer size. Just flush instead.
1480 flushBuffer handle_
1481 #endif
1482 let fd = haFD handle_
1483 posn <- fromIntegral `liftM`
1484 throwErrnoIfMinus1Retry "hGetPosn"
1485 (c_lseek fd 0 sEEK_CUR)
1486
1487 let ref = haBuffer handle_
1488 buf <- readIORef ref
1489
1490 let real_posn
1491 | bufferIsWritable buf = posn + fromIntegral (bufWPtr buf)
1492 | otherwise = posn - fromIntegral (bufWPtr buf - bufRPtr buf)
1493 # ifdef DEBUG_DUMP
1494 puts ("\nhGetPosn: (fd, posn, real_posn) = " ++ show (fd, posn, real_posn) ++ "\n")
1495 puts (" (bufWPtr, bufRPtr) = " ++ show (bufWPtr buf, bufRPtr buf) ++ "\n")
1496 # endif
1497 return real_posn
1498
1499 -- -----------------------------------------------------------------------------
1500 -- Handle Properties
1501
1502 -- A number of operations return information about the properties of a
1503 -- handle. Each of these operations returns `True' if the handle has
1504 -- the specified property, and `False' otherwise.
1505
1506 hIsOpen :: Handle -> IO Bool
1507 hIsOpen handle =
1508 withHandle_ "hIsOpen" handle $ \ handle_ -> do
1509 case haType handle_ of
1510 ClosedHandle -> return False
1511 SemiClosedHandle -> return False
1512 _ -> return True
1513
1514 hIsClosed :: Handle -> IO Bool
1515 hIsClosed handle =
1516 withHandle_ "hIsClosed" handle $ \ handle_ -> do
1517 case haType handle_ of
1518 ClosedHandle -> return True
1519 _ -> return False
1520
1521 {- not defined, nor exported, but mentioned
1522 here for documentation purposes:
1523
1524 hSemiClosed :: Handle -> IO Bool
1525 hSemiClosed h = do
1526 ho <- hIsOpen h
1527 hc <- hIsClosed h
1528 return (not (ho || hc))
1529 -}
1530
1531 hIsReadable :: Handle -> IO Bool
1532 hIsReadable (DuplexHandle _ _ _) = return True
1533 hIsReadable handle =
1534 withHandle_ "hIsReadable" handle $ \ handle_ -> do
1535 case haType handle_ of
1536 ClosedHandle -> ioe_closedHandle
1537 SemiClosedHandle -> ioe_closedHandle
1538 htype -> return (isReadableHandleType htype)
1539
1540 hIsWritable :: Handle -> IO Bool
1541 hIsWritable (DuplexHandle _ _ _) = return True
1542 hIsWritable handle =
1543 withHandle_ "hIsWritable" handle $ \ handle_ -> do
1544 case haType handle_ of
1545 ClosedHandle -> ioe_closedHandle
1546 SemiClosedHandle -> ioe_closedHandle
1547 htype -> return (isWritableHandleType htype)
1548
1549 -- | Computation 'hGetBuffering' @hdl@ returns the current buffering mode
1550 -- for @hdl@.
1551
1552 hGetBuffering :: Handle -> IO BufferMode
1553 hGetBuffering handle =
1554 withHandle_ "hGetBuffering" handle $ \ handle_ -> do
1555 case haType handle_ of
1556 ClosedHandle -> ioe_closedHandle
1557 _ ->
1558 -- We're being non-standard here, and allow the buffering
1559 -- of a semi-closed handle to be queried. -- sof 6/98
1560 return (haBufferMode handle_) -- could be stricter..
1561
1562 hIsSeekable :: Handle -> IO Bool
1563 hIsSeekable handle =
1564 withHandle_ "hIsSeekable" handle $ \ handle_ -> do
1565 case haType handle_ of
1566 ClosedHandle -> ioe_closedHandle
1567 SemiClosedHandle -> ioe_closedHandle
1568 AppendHandle -> return False
1569 _ -> do t <- fdType (haFD handle_)
1570 return ((t == RegularFile || t == RawDevice)
1571 && (haIsBin handle_ || tEXT_MODE_SEEK_ALLOWED))
1572
1573 -- -----------------------------------------------------------------------------
1574 -- Changing echo status (Non-standard GHC extensions)
1575
1576 -- | Set the echoing status of a handle connected to a terminal.
1577
1578 hSetEcho :: Handle -> Bool -> IO ()
1579 hSetEcho handle on = do
1580 isT <- hIsTerminalDevice handle
1581 if not isT
1582 then return ()
1583 else
1584 withHandle_ "hSetEcho" handle $ \ handle_ -> do
1585 case haType handle_ of
1586 ClosedHandle -> ioe_closedHandle
1587 _ -> setEcho (haFD handle_) on
1588
1589 -- | Get the echoing status of a handle connected to a terminal.
1590
1591 hGetEcho :: Handle -> IO Bool
1592 hGetEcho handle = do
1593 isT <- hIsTerminalDevice handle
1594 if not isT
1595 then return False
1596 else
1597 withHandle_ "hGetEcho" handle $ \ handle_ -> do
1598 case haType handle_ of
1599 ClosedHandle -> ioe_closedHandle
1600 _ -> getEcho (haFD handle_)
1601
1602 -- | Is the handle connected to a terminal?
1603
1604 hIsTerminalDevice :: Handle -> IO Bool
1605 hIsTerminalDevice handle = do
1606 withHandle_ "hIsTerminalDevice" handle $ \ handle_ -> do
1607 case haType handle_ of
1608 ClosedHandle -> ioe_closedHandle
1609 _ -> fdIsTTY (haFD handle_)
1610
1611 -- -----------------------------------------------------------------------------
1612 -- hSetBinaryMode
1613
1614 -- | Select binary mode ('True') or text mode ('False') on a open handle.
1615 -- (See also 'openBinaryFile'.)
1616
1617 hSetBinaryMode :: Handle -> Bool -> IO ()
1618 hSetBinaryMode handle bin =
1619 withAllHandles__ "hSetBinaryMode" handle $ \ handle_ ->
1620 do throwErrnoIfMinus1_ "hSetBinaryMode"
1621 (setmode (haFD handle_) bin)
1622 return handle_{haIsBin=bin}
1623
1624 foreign import ccall unsafe "__hscore_setmode"
1625 setmode :: CInt -> Bool -> IO CInt
1626
1627 -- -----------------------------------------------------------------------------
1628 -- Duplicating a Handle
1629
1630 -- | Returns a duplicate of the original handle, with its own buffer.
1631 -- The two Handles will share a file pointer, however. The original
1632 -- handle's buffer is flushed, including discarding any input data,
1633 -- before the handle is duplicated.
1634
1635 hDuplicate :: Handle -> IO Handle
1636 hDuplicate h@(FileHandle path m) = do
1637 new_h_ <- withHandle' "hDuplicate" h m (dupHandle h Nothing)
1638 newFileHandle path (handleFinalizer path) new_h_
1639 hDuplicate h@(DuplexHandle path r w) = do
1640 new_w_ <- withHandle' "hDuplicate" h w (dupHandle h Nothing)
1641 new_w <- newMVar new_w_
1642 new_r_ <- withHandle' "hDuplicate" h r (dupHandle h (Just new_w))
1643 new_r <- newMVar new_r_
1644 addMVarFinalizer new_w (handleFinalizer path new_w)
1645 return (DuplexHandle path new_r new_w)
1646
1647 dupHandle :: Handle -> Maybe (MVar Handle__) -> Handle__
1648 -> IO (Handle__, Handle__)
1649 dupHandle h other_side h_ = do
1650 -- flush the buffer first, so we don't have to copy its contents
1651 flushBuffer h_
1652 new_fd <- case other_side of
1653 Nothing -> throwErrnoIfMinus1 "dupHandle" $ c_dup (haFD h_)
1654 Just r -> withHandle_' "dupHandle" h r (return . haFD)
1655 dupHandle_ other_side h_ new_fd
1656
1657 dupHandleTo other_side hto_ h_ = do
1658 flushBuffer h_
1659 -- Windows' dup2 does not return the new descriptor, unlike Unix
1660 throwErrnoIfMinus1 "dupHandleTo" $
1661 c_dup2 (haFD h_) (haFD hto_)
1662 dupHandle_ other_side h_ (haFD hto_)
1663
1664 dupHandle_ :: Maybe (MVar Handle__) -> Handle__ -> FD
1665 -> IO (Handle__, Handle__)
1666 dupHandle_ other_side h_ new_fd = do
1667 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE (initBufferState (haType h_))
1668 ioref <- newIORef buffer
1669 ioref_buffers <- newIORef BufferListNil
1670
1671 let new_handle_ = h_{ haFD = new_fd,
1672 haBuffer = ioref,
1673 haBuffers = ioref_buffers,
1674 haOtherSide = other_side }
1675 return (h_, new_handle_)
1676
1677 -- -----------------------------------------------------------------------------
1678 -- Replacing a Handle
1679
1680 {- |
1681 Makes the second handle a duplicate of the first handle. The second
1682 handle will be closed first, if it is not already.
1683
1684 This can be used to retarget the standard Handles, for example:
1685
1686 > do h <- openFile "mystdout" WriteMode
1687 > hDuplicateTo h stdout
1688 -}
1689
1690 hDuplicateTo :: Handle -> Handle -> IO ()
1691 hDuplicateTo h1@(FileHandle _ m1) h2@(FileHandle _ m2) = do
1692 withHandle__' "hDuplicateTo" h2 m2 $ \h2_ -> do
1693 _ <- hClose_help h2_
1694 withHandle' "hDuplicateTo" h1 m1 (dupHandleTo Nothing h2_)
1695 hDuplicateTo h1@(DuplexHandle _ r1 w1) h2@(DuplexHandle _ r2 w2) = do
1696 withHandle__' "hDuplicateTo" h2 w2 $ \w2_ -> do
1697 _ <- hClose_help w2_
1698 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo Nothing w2_)
1699 withHandle__' "hDuplicateTo" h2 r2 $ \r2_ -> do
1700 _ <- hClose_help r2_
1701 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo (Just w1) r2_)
1702 hDuplicateTo h1 _ =
1703 ioException (IOError (Just h1) IllegalOperation "hDuplicateTo"
1704 "handles are incompatible" Nothing)
1705
1706 -- ---------------------------------------------------------------------------
1707 -- showing Handles.
1708 --
1709 -- | 'hShow' is in the 'IO' monad, and gives more comprehensive output
1710 -- than the (pure) instance of 'Show' for 'Handle'.
1711
1712 hShow :: Handle -> IO String
1713 hShow h@(FileHandle path _) = showHandle' path False h
1714 hShow h@(DuplexHandle path _ _) = showHandle' path True h
1715
1716 showHandle' filepath is_duplex h =
1717 withHandle_ "showHandle" h $ \hdl_ ->
1718 let
1719 showType | is_duplex = showString "duplex (read-write)"
1720 | otherwise = shows (haType hdl_)
1721 in
1722 return
1723 (( showChar '{' .
1724 showHdl (haType hdl_)
1725 (showString "loc=" . showString filepath . showChar ',' .
1726 showString "type=" . showType . showChar ',' .
1727 showString "binary=" . shows (haIsBin hdl_) . showChar ',' .
1728 showString "buffering=" . showBufMode (unsafePerformIO (readIORef (haBuffer hdl_))) (haBufferMode hdl_) . showString "}" )
1729 ) "")
1730 where
1731
1732 showHdl :: HandleType -> ShowS -> ShowS
1733 showHdl ht cont =
1734 case ht of
1735 ClosedHandle -> shows ht . showString "}"
1736 _ -> cont
1737
1738 showBufMode :: Buffer -> BufferMode -> ShowS
1739 showBufMode buf bmo =
1740 case bmo of
1741 NoBuffering -> showString "none"
1742 LineBuffering -> showString "line"
1743 BlockBuffering (Just n) -> showString "block " . showParen True (shows n)
1744 BlockBuffering Nothing -> showString "block " . showParen True (shows def)
1745 where
1746 def :: Int
1747 def = bufSize buf
1748
1749 -- ---------------------------------------------------------------------------
1750 -- debugging
1751
1752 #if defined(DEBUG_DUMP)
1753 puts :: String -> IO ()
1754 puts s = do write_rawBuffer 1 (unsafeCoerce# (packCString# s)) 0 (fromIntegral (length s))
1755 return ()
1756 #endif
1757
1758 -- -----------------------------------------------------------------------------
1759 -- utils
1760
1761 throwErrnoIfMinus1RetryOnBlock :: String -> IO CInt -> IO CInt -> IO CInt
1762 throwErrnoIfMinus1RetryOnBlock loc f on_block =
1763 do
1764 res <- f
1765 if (res :: CInt) == -1
1766 then do
1767 err <- getErrno
1768 if err == eINTR
1769 then throwErrnoIfMinus1RetryOnBlock loc f on_block
1770 else if err == eWOULDBLOCK || err == eAGAIN
1771 then do on_block
1772 else throwErrno loc
1773 else return res
1774
1775 -- -----------------------------------------------------------------------------
1776 -- wrappers to platform-specific constants:
1777
1778 foreign import ccall unsafe "__hscore_supportsTextMode"
1779 tEXT_MODE_SEEK_ALLOWED :: Bool
1780
1781 foreign import ccall unsafe "__hscore_bufsiz" dEFAULT_BUFFER_SIZE :: Int
1782 foreign import ccall unsafe "__hscore_seek_cur" sEEK_CUR :: CInt
1783 foreign import ccall unsafe "__hscore_seek_set" sEEK_SET :: CInt
1784 foreign import ccall unsafe "__hscore_seek_end" sEEK_END :: CInt