Remove Control.Parallel*, now in package parallel
[packages/random.git] / GHC / Handle.hs
1 {-# OPTIONS_GHC -fno-implicit-prelude -#include "HsBase.h" #-}
2
3 #undef DEBUG_DUMP
4 #undef DEBUG
5
6 -----------------------------------------------------------------------------
7 -- |
8 -- Module : GHC.Handle
9 -- Copyright : (c) The University of Glasgow, 1994-2001
10 -- License : see libraries/base/LICENSE
11 --
12 -- Maintainer : libraries@haskell.org
13 -- Stability : internal
14 -- Portability : non-portable
15 --
16 -- This module defines the basic operations on I\/O \"handles\".
17 --
18 -----------------------------------------------------------------------------
19
20 -- #hide
21 module GHC.Handle (
22 withHandle, withHandle', withHandle_,
23 wantWritableHandle, wantReadableHandle, wantSeekableHandle,
24
25 newEmptyBuffer, allocateBuffer, readCharFromBuffer, writeCharIntoBuffer,
26 flushWriteBufferOnly, flushWriteBuffer, flushReadBuffer,
27 fillReadBuffer, fillReadBufferWithoutBlocking,
28 readRawBuffer, readRawBufferPtr,
29 writeRawBuffer, writeRawBufferPtr,
30
31 #ifndef mingw32_HOST_OS
32 unlockFile,
33 #endif
34
35 ioe_closedHandle, ioe_EOF, ioe_notReadable, ioe_notWritable,
36
37 stdin, stdout, stderr,
38 IOMode(..), openFile, openBinaryFile, openTempFile, openBinaryTempFile, openFd, fdToHandle,
39 hFileSize, hSetFileSize, hIsEOF, isEOF, hLookAhead, hSetBuffering, hSetBinaryMode,
40 hFlush, hDuplicate, hDuplicateTo,
41
42 hClose, hClose_help,
43
44 HandlePosition, HandlePosn(..), hGetPosn, hSetPosn,
45 SeekMode(..), hSeek, hTell,
46
47 hIsOpen, hIsClosed, hIsReadable, hIsWritable, hGetBuffering, hIsSeekable,
48 hSetEcho, hGetEcho, hIsTerminalDevice,
49
50 hShow,
51
52 #ifdef DEBUG_DUMP
53 puts,
54 #endif
55
56 ) where
57
58 import System.Directory.Internals
59 import Control.Monad
60 import Data.Bits
61 import Data.Maybe
62 import Foreign
63 import Foreign.C
64 import System.IO.Error
65 import System.Posix.Internals
66
67 import GHC.Real
68
69 import GHC.Arr
70 import GHC.Base
71 import GHC.Read ( Read )
72 import GHC.List
73 import GHC.IOBase
74 import GHC.Exception
75 import GHC.Enum
76 import GHC.Num ( Integer(..), Num(..) )
77 import GHC.Show
78 import GHC.Real ( toInteger )
79 #if defined(DEBUG_DUMP)
80 import GHC.Pack
81 #endif
82
83 import GHC.Conc
84
85 -- -----------------------------------------------------------------------------
86 -- TODO:
87
88 -- hWaitForInput blocks (should use a timeout)
89
90 -- unbuffered hGetLine is a bit dodgy
91
92 -- hSetBuffering: can't change buffering on a stream,
93 -- when the read buffer is non-empty? (no way to flush the buffer)
94
95 -- ---------------------------------------------------------------------------
96 -- Are files opened by default in text or binary mode, if the user doesn't
97 -- specify?
98
99 dEFAULT_OPEN_IN_BINARY_MODE = False :: Bool
100
101 -- ---------------------------------------------------------------------------
102 -- Creating a new handle
103
104 newFileHandle :: FilePath -> (MVar Handle__ -> IO ()) -> Handle__ -> IO Handle
105 newFileHandle filepath finalizer hc = do
106 m <- newMVar hc
107 addMVarFinalizer m (finalizer m)
108 return (FileHandle filepath m)
109
110 -- ---------------------------------------------------------------------------
111 -- Working with Handles
112
113 {-
114 In the concurrent world, handles are locked during use. This is done
115 by wrapping an MVar around the handle which acts as a mutex over
116 operations on the handle.
117
118 To avoid races, we use the following bracketing operations. The idea
119 is to obtain the lock, do some operation and replace the lock again,
120 whether the operation succeeded or failed. We also want to handle the
121 case where the thread receives an exception while processing the IO
122 operation: in these cases we also want to relinquish the lock.
123
124 There are three versions of @withHandle@: corresponding to the three
125 possible combinations of:
126
127 - the operation may side-effect the handle
128 - the operation may return a result
129
130 If the operation generates an error or an exception is raised, the
131 original handle is always replaced [ this is the case at the moment,
132 but we might want to revisit this in the future --SDM ].
133 -}
134
135 {-# INLINE withHandle #-}
136 withHandle :: String -> Handle -> (Handle__ -> IO (Handle__,a)) -> IO a
137 withHandle fun h@(FileHandle _ m) act = withHandle' fun h m act
138 withHandle fun h@(DuplexHandle _ m _) act = withHandle' fun h m act
139
140 withHandle' :: String -> Handle -> MVar Handle__
141 -> (Handle__ -> IO (Handle__,a)) -> IO a
142 withHandle' fun h m act =
143 block $ do
144 h_ <- takeMVar m
145 checkBufferInvariants h_
146 (h',v) <- catchException (act h_)
147 (\ err -> putMVar m h_ >>
148 case err of
149 IOException ex -> ioError (augmentIOError ex fun h)
150 _ -> throw err)
151 checkBufferInvariants h'
152 putMVar m h'
153 return v
154
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
159
160 withHandle_' :: String -> Handle -> MVar Handle__ -> (Handle__ -> IO a) -> IO a
161 withHandle_' fun h m act =
162 block $ do
163 h_ <- takeMVar m
164 checkBufferInvariants h_
165 v <- catchException (act h_)
166 (\ err -> putMVar m h_ >>
167 case err of
168 IOException ex -> ioError (augmentIOError ex fun h)
169 _ -> throw err)
170 checkBufferInvariants h_
171 putMVar m h_
172 return v
173
174 withAllHandles__ :: String -> Handle -> (Handle__ -> IO Handle__) -> IO ()
175 withAllHandles__ fun h@(FileHandle _ m) act = withHandle__' fun h m act
176 withAllHandles__ fun h@(DuplexHandle _ r w) act = do
177 withHandle__' fun h r act
178 withHandle__' fun h w act
179
180 withHandle__' fun h m act =
181 block $ do
182 h_ <- takeMVar m
183 checkBufferInvariants h_
184 h' <- catchException (act h_)
185 (\ err -> putMVar m h_ >>
186 case err of
187 IOException ex -> ioError (augmentIOError ex fun h)
188 _ -> throw err)
189 checkBufferInvariants h'
190 putMVar m h'
191 return ()
192
193 augmentIOError (IOError _ iot _ str fp) fun h
194 = IOError (Just h) iot fun str filepath
195 where filepath
196 | Just _ <- fp = fp
197 | otherwise = case h of
198 FileHandle fp _ -> Just fp
199 DuplexHandle fp _ _ -> Just fp
200
201 -- ---------------------------------------------------------------------------
202 -- Wrapper for write operations.
203
204 wantWritableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
205 wantWritableHandle fun h@(FileHandle _ m) act
206 = wantWritableHandle' fun h m act
207 wantWritableHandle fun h@(DuplexHandle _ _ m) act
208 = wantWritableHandle' fun h m act
209 -- ToDo: in the Duplex case, we don't need to checkWritableHandle
210
211 wantWritableHandle'
212 :: String -> Handle -> MVar Handle__
213 -> (Handle__ -> IO a) -> IO a
214 wantWritableHandle' fun h m act
215 = withHandle_' fun h m (checkWritableHandle act)
216
217 checkWritableHandle act handle_
218 = case haType handle_ of
219 ClosedHandle -> ioe_closedHandle
220 SemiClosedHandle -> ioe_closedHandle
221 ReadHandle -> ioe_notWritable
222 ReadWriteHandle -> do
223 let ref = haBuffer handle_
224 buf <- readIORef ref
225 new_buf <-
226 if not (bufferIsWritable buf)
227 then do b <- flushReadBuffer (haFD handle_) buf
228 return b{ bufState=WriteBuffer }
229 else return buf
230 writeIORef ref new_buf
231 act handle_
232 _other -> act handle_
233
234 -- ---------------------------------------------------------------------------
235 -- Wrapper for read operations.
236
237 wantReadableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
238 wantReadableHandle fun h@(FileHandle _ m) act
239 = wantReadableHandle' fun h m act
240 wantReadableHandle fun h@(DuplexHandle _ m _) act
241 = wantReadableHandle' fun h m act
242 -- ToDo: in the Duplex case, we don't need to checkReadableHandle
243
244 wantReadableHandle'
245 :: String -> Handle -> MVar Handle__
246 -> (Handle__ -> IO a) -> IO a
247 wantReadableHandle' fun h m act
248 = withHandle_' fun h m (checkReadableHandle act)
249
250 checkReadableHandle act handle_ =
251 case haType handle_ of
252 ClosedHandle -> ioe_closedHandle
253 SemiClosedHandle -> ioe_closedHandle
254 AppendHandle -> ioe_notReadable
255 WriteHandle -> ioe_notReadable
256 ReadWriteHandle -> do
257 let ref = haBuffer handle_
258 buf <- readIORef ref
259 when (bufferIsWritable buf) $ do
260 new_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
261 writeIORef ref new_buf{ bufState=ReadBuffer }
262 act handle_
263 _other -> act handle_
264
265 -- ---------------------------------------------------------------------------
266 -- Wrapper for seek operations.
267
268 wantSeekableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
269 wantSeekableHandle fun h@(DuplexHandle _ _ _) _act =
270 ioException (IOError (Just h) IllegalOperation fun
271 "handle is not seekable" Nothing)
272 wantSeekableHandle fun h@(FileHandle _ m) act =
273 withHandle_' fun h m (checkSeekableHandle act)
274
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
282
283 -- -----------------------------------------------------------------------------
284 -- Handy IOErrors
285
286 ioe_closedHandle, ioe_EOF,
287 ioe_notReadable, ioe_notWritable,
288 ioe_notSeekable, ioe_notSeekable_notBin :: IO a
289
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"
307 Nothing)
308
309 ioe_finalizedHandle fp = throw (IOException
310 (IOError Nothing IllegalOperation ""
311 "handle is finalized" (Just fp)))
312
313 ioe_bufsiz :: Int -> IO a
314 ioe_bufsiz n = ioException
315 (IOError Nothing InvalidArgument "hSetBuffering"
316 ("illegal buffer size " ++ showsPrec 9 n []) Nothing)
317 -- 9 => should be parens'ified.
318
319 -- -----------------------------------------------------------------------------
320 -- Handle Finalizers
321
322 -- For a duplex handle, we arrange that the read side points to the write side
323 -- (and hence keeps it alive if the read side is alive). This is done by
324 -- having the haOtherSide field of the read side point to the read side.
325 -- The finalizer is then placed on the write side, and the handle only gets
326 -- finalized once, when both sides are no longer required.
327
328 -- NOTE about finalized handles: It's possible that a handle can be
329 -- finalized and then we try to use it later, for example if the
330 -- handle is referenced from another finalizer, or from a thread that
331 -- has become unreferenced and then resurrected (arguably in the
332 -- latter case we shouldn't finalize the Handle...). Anyway,
333 -- we try to emit a helpful message which is better than nothing.
334
335 stdHandleFinalizer :: FilePath -> MVar Handle__ -> IO ()
336 stdHandleFinalizer fp m = do
337 h_ <- takeMVar m
338 flushWriteBufferOnly h_
339 putMVar m (ioe_finalizedHandle fp)
340
341 handleFinalizer :: FilePath -> MVar Handle__ -> IO ()
342 handleFinalizer fp m = do
343 handle_ <- takeMVar m
344 case haType handle_ of
345 ClosedHandle -> return ()
346 _ -> do flushWriteBufferOnly handle_ `catchException` \_ -> return ()
347 -- ignore errors and async exceptions, and close the
348 -- descriptor anyway...
349 hClose_handle_ handle_
350 return ()
351 putMVar m (ioe_finalizedHandle fp)
352
353 -- ---------------------------------------------------------------------------
354 -- Grimy buffer operations
355
356 #ifdef DEBUG
357 checkBufferInvariants h_ = do
358 let ref = haBuffer h_
359 Buffer{ bufWPtr=w, bufRPtr=r, bufSize=size, bufState=state } <- readIORef ref
360 if not (
361 size > 0
362 && r <= w
363 && w <= size
364 && ( r /= w || (r == 0 && w == 0) )
365 && ( state /= WriteBuffer || r == 0 )
366 && ( state /= WriteBuffer || w < size ) -- write buffer is never full
367 )
368 then error "buffer invariant violation"
369 else return ()
370 #else
371 checkBufferInvariants h_ = return ()
372 #endif
373
374 newEmptyBuffer :: RawBuffer -> BufferState -> Int -> Buffer
375 newEmptyBuffer b state size
376 = Buffer{ bufBuf=b, bufRPtr=0, bufWPtr=0, bufSize=size, bufState=state }
377
378 allocateBuffer :: Int -> BufferState -> IO Buffer
379 allocateBuffer sz@(I# size) state = IO $ \s ->
380 #ifdef mingw32_HOST_OS
381 -- To implement asynchronous I/O under Win32, we have to pass
382 -- buffer references to external threads that handles the
383 -- filling/emptying of their contents. Hence, the buffer cannot
384 -- be moved around by the GC.
385 case newPinnedByteArray# size s of { (# s, b #) ->
386 #else
387 case newByteArray# size s of { (# s, b #) ->
388 #endif
389 (# s, newEmptyBuffer b state sz #) }
390
391 writeCharIntoBuffer :: RawBuffer -> Int -> Char -> IO Int
392 writeCharIntoBuffer slab (I# off) (C# c)
393 = IO $ \s -> case writeCharArray# slab off c s of
394 s -> (# s, I# (off +# 1#) #)
395
396 readCharFromBuffer :: RawBuffer -> Int -> IO (Char, Int)
397 readCharFromBuffer slab (I# off)
398 = IO $ \s -> case readCharArray# slab off s of
399 (# s, c #) -> (# s, (C# c, I# (off +# 1#)) #)
400
401 getBuffer :: FD -> BufferState -> IO (IORef Buffer, BufferMode)
402 getBuffer fd state = do
403 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE state
404 ioref <- newIORef buffer
405 is_tty <- fdIsTTY fd
406
407 let buffer_mode
408 | is_tty = LineBuffering
409 | otherwise = BlockBuffering Nothing
410
411 return (ioref, buffer_mode)
412
413 mkUnBuffer :: IO (IORef Buffer)
414 mkUnBuffer = do
415 buffer <- allocateBuffer 1 ReadBuffer
416 newIORef buffer
417
418 -- flushWriteBufferOnly flushes the buffer iff it contains pending write data.
419 flushWriteBufferOnly :: Handle__ -> IO ()
420 flushWriteBufferOnly h_ = do
421 let fd = haFD h_
422 ref = haBuffer h_
423 buf <- readIORef ref
424 new_buf <- if bufferIsWritable buf
425 then flushWriteBuffer fd (haIsStream h_) buf
426 else return buf
427 writeIORef ref new_buf
428
429 -- flushBuffer syncs the file with the buffer, including moving the
430 -- file pointer backwards in the case of a read buffer.
431 flushBuffer :: Handle__ -> IO ()
432 flushBuffer h_ = do
433 let ref = haBuffer h_
434 buf <- readIORef ref
435
436 flushed_buf <-
437 case bufState buf of
438 ReadBuffer -> flushReadBuffer (haFD h_) buf
439 WriteBuffer -> flushWriteBuffer (haFD h_) (haIsStream h_) buf
440
441 writeIORef ref flushed_buf
442
443 -- When flushing a read buffer, we seek backwards by the number of
444 -- characters in the buffer. The file descriptor must therefore be
445 -- seekable: attempting to flush the read buffer on an unseekable
446 -- handle is not allowed.
447
448 flushReadBuffer :: FD -> Buffer -> IO Buffer
449 flushReadBuffer fd buf
450 | bufferEmpty buf = return buf
451 | otherwise = do
452 let off = negate (bufWPtr buf - bufRPtr buf)
453 # ifdef DEBUG_DUMP
454 puts ("flushReadBuffer: new file offset = " ++ show off ++ "\n")
455 # endif
456 throwErrnoIfMinus1Retry "flushReadBuffer"
457 (c_lseek fd (fromIntegral off) sEEK_CUR)
458 return buf{ bufWPtr=0, bufRPtr=0 }
459
460 flushWriteBuffer :: FD -> Bool -> Buffer -> IO Buffer
461 flushWriteBuffer fd is_stream buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w } =
462 seq fd $ do -- strictness hack
463 let bytes = w - r
464 #ifdef DEBUG_DUMP
465 puts ("flushWriteBuffer, fd=" ++ show fd ++ ", bytes=" ++ show bytes ++ "\n")
466 #endif
467 if bytes == 0
468 then return (buf{ bufRPtr=0, bufWPtr=0 })
469 else do
470 res <- writeRawBuffer "flushWriteBuffer" fd is_stream b
471 (fromIntegral r) (fromIntegral bytes)
472 let res' = fromIntegral res
473 if res' < bytes
474 then flushWriteBuffer fd is_stream (buf{ bufRPtr = r + res' })
475 else return buf{ bufRPtr=0, bufWPtr=0 }
476
477 fillReadBuffer :: FD -> Bool -> Bool -> Buffer -> IO Buffer
478 fillReadBuffer fd is_line is_stream
479 buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w, bufSize=size } =
480 -- buffer better be empty:
481 assert (r == 0 && w == 0) $ do
482 fillReadBufferLoop fd is_line is_stream buf b w size
483
484 -- For a line buffer, we just get the first chunk of data to arrive,
485 -- and don't wait for the whole buffer to be full (but we *do* wait
486 -- until some data arrives). This isn't really line buffering, but it
487 -- appears to be what GHC has done for a long time, and I suspect it
488 -- is more useful than line buffering in most cases.
489
490 fillReadBufferLoop fd is_line is_stream buf b w size = do
491 let bytes = size - w
492 if bytes == 0 -- buffer full?
493 then return buf{ bufRPtr=0, bufWPtr=w }
494 else do
495 #ifdef DEBUG_DUMP
496 puts ("fillReadBufferLoop: bytes = " ++ show bytes ++ "\n")
497 #endif
498 res <- readRawBuffer "fillReadBuffer" fd is_stream b
499 (fromIntegral w) (fromIntegral bytes)
500 let res' = fromIntegral res
501 #ifdef DEBUG_DUMP
502 puts ("fillReadBufferLoop: res' = " ++ show res' ++ "\n")
503 #endif
504 if res' == 0
505 then if w == 0
506 then ioe_EOF
507 else return buf{ bufRPtr=0, bufWPtr=w }
508 else if res' < bytes && not is_line
509 then fillReadBufferLoop fd is_line is_stream buf b (w+res') size
510 else return buf{ bufRPtr=0, bufWPtr=w+res' }
511
512
513 fillReadBufferWithoutBlocking :: FD -> Bool -> Buffer -> IO Buffer
514 fillReadBufferWithoutBlocking fd is_stream
515 buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w, bufSize=size } =
516 -- buffer better be empty:
517 assert (r == 0 && w == 0) $ do
518 #ifdef DEBUG_DUMP
519 puts ("fillReadBufferLoopNoBlock: bytes = " ++ show size ++ "\n")
520 #endif
521 res <- readRawBufferNoBlock "fillReadBuffer" fd is_stream b
522 0 (fromIntegral size)
523 let res' = fromIntegral res
524 #ifdef DEBUG_DUMP
525 puts ("fillReadBufferLoopNoBlock: res' = " ++ show res' ++ "\n")
526 #endif
527 return buf{ bufRPtr=0, bufWPtr=res' }
528
529 -- Low level routines for reading/writing to (raw)buffers:
530
531 #ifndef mingw32_HOST_OS
532
533 {-
534 NOTE [nonblock]:
535
536 Unix has broken semantics when it comes to non-blocking I/O: you can
537 set the O_NONBLOCK flag on an FD, but it applies to the all other FDs
538 attached to the same underlying file, pipe or TTY; there's no way to
539 have private non-blocking behaviour for an FD. See bug #724.
540
541 We fix this by only setting O_NONBLOCK on FDs that we create; FDs that
542 come from external sources or are exposed externally are left in
543 blocking mode. This solution has some problems though. We can't
544 completely simulate a non-blocking read without O_NONBLOCK: several
545 cases are wrong here. The cases that are wrong:
546
547 * reading/writing to a blocking FD in non-threaded mode.
548 In threaded mode, we just make a safe call to read().
549 In non-threaded mode we call select() before attempting to read,
550 but that leaves a small race window where the data can be read
551 from the file descriptor before we issue our blocking read().
552 * readRawBufferNoBlock for a blocking FD
553 -}
554
555 readRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
556 readRawBuffer loc fd is_nonblock buf off len
557 | is_nonblock = unsafe_read
558 | threaded = safe_read
559 | otherwise = do r <- throwErrnoIfMinus1 loc
560 (fdReady (fromIntegral fd) 0 0 False)
561 if r /= 0
562 then unsafe_read
563 else do threadWaitRead (fromIntegral fd); unsafe_read
564 where
565 do_read call = throwErrnoIfMinus1RetryMayBlock loc call
566 (threadWaitRead (fromIntegral fd))
567 unsafe_read = do_read (read_rawBuffer fd buf off len)
568 safe_read = do_read (safe_read_rawBuffer fd buf off len)
569
570 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
571 readRawBufferPtr loc fd is_nonblock buf off len
572 | is_nonblock = unsafe_read
573 | threaded = safe_read
574 | otherwise = do r <- throwErrnoIfMinus1 loc
575 (fdReady (fromIntegral fd) 0 0 False)
576 if r /= 0
577 then unsafe_read
578 else do threadWaitRead (fromIntegral fd); unsafe_read
579 where
580 do_read call = throwErrnoIfMinus1RetryMayBlock loc call
581 (threadWaitRead (fromIntegral fd))
582 unsafe_read = do_read (read_off fd buf off len)
583 safe_read = do_read (safe_read_off fd buf off len)
584
585 readRawBufferNoBlock :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
586 readRawBufferNoBlock loc fd is_nonblock buf off len
587 | is_nonblock = unsafe_read
588 | otherwise = do r <- fdReady (fromIntegral fd) 0 0 False
589 if r /= 0 then safe_read
590 else return 0
591 -- XXX see note [nonblock]
592 where
593 do_read call = throwErrnoIfMinus1RetryMayBlock loc call (return 0)
594 unsafe_read = do_read (read_rawBuffer fd buf off len)
595 safe_read = do_read (safe_read_rawBuffer fd buf off len)
596
597 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
598 writeRawBuffer loc fd is_nonblock buf off len
599 | is_nonblock = unsafe_write
600 | threaded = safe_write
601 | otherwise = do r <- fdReady (fromIntegral fd) 1 0 False
602 if r /= 0 then safe_write
603 else return 0
604 where
605 do_write call = throwErrnoIfMinus1RetryMayBlock loc call
606 (threadWaitWrite (fromIntegral fd))
607 unsafe_write = do_write (write_rawBuffer fd buf off len)
608 safe_write = do_write (safe_write_rawBuffer (fromIntegral fd) buf off len)
609
610 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
611 writeRawBufferPtr loc fd is_nonblock buf off len
612 | is_nonblock = unsafe_write
613 | threaded = safe_write
614 | otherwise = do r <- fdReady (fromIntegral fd) 1 0 False
615 if r /= 0 then safe_write
616 else return 0
617 where
618 do_write call = throwErrnoIfMinus1RetryMayBlock loc call
619 (threadWaitWrite (fromIntegral fd))
620 unsafe_write = do_write (write_off fd buf off len)
621 safe_write = do_write (safe_write_off (fromIntegral fd) buf off len)
622
623 foreign import ccall unsafe "__hscore_PrelHandle_read"
624 read_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
625
626 foreign import ccall unsafe "__hscore_PrelHandle_read"
627 read_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
628
629 foreign import ccall unsafe "__hscore_PrelHandle_write"
630 write_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
631
632 foreign import ccall unsafe "__hscore_PrelHandle_write"
633 write_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
634
635 foreign import ccall safe "fdReady"
636 fdReady :: CInt -> CInt -> CInt -> Bool -> IO CInt
637
638 #else /* mingw32_HOST_OS.... */
639
640 readRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
641 readRawBuffer loc fd is_stream buf off len
642 | threaded = blockingReadRawBuffer loc fd is_stream buf off len
643 | otherwise = asyncReadRawBuffer loc fd is_stream buf off len
644
645 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
646 readRawBufferPtr loc fd is_stream buf off len
647 | threaded = blockingReadRawBufferPtr loc fd is_stream buf off len
648 | otherwise = asyncReadRawBufferPtr loc fd is_stream buf off len
649
650 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
651 writeRawBuffer loc fd is_stream buf off len
652 | threaded = blockingWriteRawBuffer loc fd is_stream buf off len
653 | otherwise = asyncWriteRawBuffer loc fd is_stream buf off len
654
655 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
656 writeRawBufferPtr loc fd is_stream buf off len
657 | threaded = blockingWriteRawBufferPtr loc fd is_stream buf off len
658 | otherwise = asyncWriteRawBufferPtr loc fd is_stream buf off len
659
660 -- ToDo: we don't have a non-blocking primitve read on Win32
661 readRawBufferNoBlock :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
662 readRawBufferNoBlock = readRawBuffer
663
664 -- Async versions of the read/write primitives, for the non-threaded RTS
665
666 asyncReadRawBuffer loc fd is_stream buf off len = do
667 (l, rc) <- asyncReadBA (fromIntegral fd) (if is_stream then 1 else 0)
668 (fromIntegral len) off buf
669 if l == (-1)
670 then
671 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
672 else return (fromIntegral l)
673
674 asyncReadRawBufferPtr loc fd is_stream buf off len = do
675 (l, rc) <- asyncRead (fromIntegral fd) (if is_stream then 1 else 0)
676 (fromIntegral len) (buf `plusPtr` off)
677 if l == (-1)
678 then
679 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
680 else return (fromIntegral l)
681
682 asyncWriteRawBuffer loc fd is_stream buf off len = do
683 (l, rc) <- asyncWriteBA (fromIntegral fd) (if is_stream then 1 else 0)
684 (fromIntegral len) off buf
685 if l == (-1)
686 then
687 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
688 else return (fromIntegral l)
689
690 asyncWriteRawBufferPtr loc fd is_stream buf off len = do
691 (l, rc) <- asyncWrite (fromIntegral fd) (if is_stream then 1 else 0)
692 (fromIntegral len) (buf `plusPtr` off)
693 if l == (-1)
694 then
695 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
696 else return (fromIntegral l)
697
698 -- Blocking versions of the read/write primitives, for the threaded RTS
699
700 blockingReadRawBuffer loc fd True buf off len =
701 throwErrnoIfMinus1Retry loc $
702 safe_recv_rawBuffer fd buf off len
703 blockingReadRawBuffer loc fd False buf off len =
704 throwErrnoIfMinus1Retry loc $
705 safe_read_rawBuffer fd buf off len
706
707 blockingReadRawBufferPtr loc fd True buf off len =
708 throwErrnoIfMinus1Retry loc $
709 safe_recv_off fd buf off len
710 blockingReadRawBufferPtr loc fd False buf off len =
711 throwErrnoIfMinus1Retry loc $
712 safe_read_off fd buf off len
713
714 blockingWriteRawBuffer loc fd True buf off len =
715 throwErrnoIfMinus1Retry loc $
716 safe_send_rawBuffer fd buf off len
717 blockingWriteRawBuffer loc fd False buf off len =
718 throwErrnoIfMinus1Retry loc $
719 safe_write_rawBuffer fd buf off len
720
721 blockingWriteRawBufferPtr loc fd True buf off len =
722 throwErrnoIfMinus1Retry loc $
723 safe_send_off fd buf off len
724 blockingWriteRawBufferPtr loc fd False buf off len =
725 throwErrnoIfMinus1Retry loc $
726 safe_write_off fd buf off len
727
728 -- NOTE: "safe" versions of the read/write calls for use by the threaded RTS.
729 -- These calls may block, but that's ok.
730
731 foreign import ccall safe "__hscore_PrelHandle_recv"
732 safe_recv_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
733
734 foreign import ccall safe "__hscore_PrelHandle_recv"
735 safe_recv_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
736
737 foreign import ccall safe "__hscore_PrelHandle_send"
738 safe_send_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
739
740 foreign import ccall safe "__hscore_PrelHandle_send"
741 safe_send_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
742
743 #endif
744
745 foreign import ccall "rtsSupportsBoundThreads" threaded :: Bool
746
747 foreign import ccall safe "__hscore_PrelHandle_read"
748 safe_read_rawBuffer :: FD -> RawBuffer -> Int -> CInt -> IO CInt
749
750 foreign import ccall safe "__hscore_PrelHandle_read"
751 safe_read_off :: FD -> Ptr CChar -> Int -> CInt -> IO CInt
752
753 foreign import ccall safe "__hscore_PrelHandle_write"
754 safe_write_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
755
756 foreign import ccall safe "__hscore_PrelHandle_write"
757 safe_write_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
758
759 -- ---------------------------------------------------------------------------
760 -- Standard Handles
761
762 -- Three handles are allocated during program initialisation. The first
763 -- two manage input or output from the Haskell program's standard input
764 -- or output channel respectively. The third manages output to the
765 -- standard error channel. These handles are initially open.
766
767 fd_stdin = 0 :: FD
768 fd_stdout = 1 :: FD
769 fd_stderr = 2 :: FD
770
771 -- | A handle managing input from the Haskell program's standard input channel.
772 stdin :: Handle
773 stdin = unsafePerformIO $ do
774 -- ToDo: acquire lock
775 -- We don't set non-blocking mode on standard handles, because it may
776 -- confuse other applications attached to the same TTY/pipe
777 -- see Note [nonblock]
778 (buf, bmode) <- getBuffer fd_stdin ReadBuffer
779 mkStdHandle fd_stdin "<stdin>" ReadHandle buf bmode
780
781 -- | A handle managing output to the Haskell program's standard output channel.
782 stdout :: Handle
783 stdout = unsafePerformIO $ do
784 -- ToDo: acquire lock
785 -- We don't set non-blocking mode on standard handles, because it may
786 -- confuse other applications attached to the same TTY/pipe
787 -- see Note [nonblock]
788 (buf, bmode) <- getBuffer fd_stdout WriteBuffer
789 mkStdHandle fd_stdout "<stdout>" WriteHandle buf bmode
790
791 -- | A handle managing output to the Haskell program's standard error channel.
792 stderr :: Handle
793 stderr = unsafePerformIO $ do
794 -- ToDo: acquire lock
795 -- We don't set non-blocking mode on standard handles, because it may
796 -- confuse other applications attached to the same TTY/pipe
797 -- see Note [nonblock]
798 buf <- mkUnBuffer
799 mkStdHandle fd_stderr "<stderr>" WriteHandle buf NoBuffering
800
801 -- ---------------------------------------------------------------------------
802 -- Opening and Closing Files
803
804 addFilePathToIOError fun fp (IOError h iot _ str _)
805 = IOError h iot fun str (Just fp)
806
807 -- | Computation 'openFile' @file mode@ allocates and returns a new, open
808 -- handle to manage the file @file@. It manages input if @mode@
809 -- is 'ReadMode', output if @mode@ is 'WriteMode' or 'AppendMode',
810 -- and both input and output if mode is 'ReadWriteMode'.
811 --
812 -- If the file does not exist and it is opened for output, it should be
813 -- created as a new file. If @mode@ is 'WriteMode' and the file
814 -- already exists, then it should be truncated to zero length.
815 -- Some operating systems delete empty files, so there is no guarantee
816 -- that the file will exist following an 'openFile' with @mode@
817 -- 'WriteMode' unless it is subsequently written to successfully.
818 -- The handle is positioned at the end of the file if @mode@ is
819 -- 'AppendMode', and otherwise at the beginning (in which case its
820 -- internal position is 0).
821 -- The initial buffer mode is implementation-dependent.
822 --
823 -- This operation may fail with:
824 --
825 -- * 'isAlreadyInUseError' if the file is already open and cannot be reopened;
826 --
827 -- * 'isDoesNotExistError' if the file does not exist; or
828 --
829 -- * 'isPermissionError' if the user does not have permission to open the file.
830 --
831 -- Note: if you will be working with files containing binary data, you'll want to
832 -- be using 'openBinaryFile'.
833 openFile :: FilePath -> IOMode -> IO Handle
834 openFile fp im =
835 catch
836 (openFile' fp im dEFAULT_OPEN_IN_BINARY_MODE)
837 (\e -> ioError (addFilePathToIOError "openFile" fp e))
838
839 -- | Like 'openFile', but open the file in binary mode.
840 -- On Windows, reading a file in text mode (which is the default)
841 -- will translate CRLF to LF, and writing will translate LF to CRLF.
842 -- This is usually what you want with text files. With binary files
843 -- this is undesirable; also, as usual under Microsoft operating systems,
844 -- text mode treats control-Z as EOF. Binary mode turns off all special
845 -- treatment of end-of-line and end-of-file characters.
846 -- (See also 'hSetBinaryMode'.)
847
848 openBinaryFile :: FilePath -> IOMode -> IO Handle
849 openBinaryFile fp m =
850 catch
851 (openFile' fp m True)
852 (\e -> ioError (addFilePathToIOError "openBinaryFile" fp e))
853
854 openFile' filepath mode binary =
855 withCString filepath $ \ f ->
856
857 let
858 oflags1 = case mode of
859 ReadMode -> read_flags
860 #ifdef mingw32_HOST_OS
861 WriteMode -> write_flags .|. o_TRUNC
862 #else
863 WriteMode -> write_flags
864 #endif
865 ReadWriteMode -> rw_flags
866 AppendMode -> append_flags
867
868 binary_flags
869 | binary = o_BINARY
870 | otherwise = 0
871
872 oflags = oflags1 .|. binary_flags
873 in do
874
875 -- the old implementation had a complicated series of three opens,
876 -- which is perhaps because we have to be careful not to open
877 -- directories. However, the man pages I've read say that open()
878 -- always returns EISDIR if the file is a directory and was opened
879 -- for writing, so I think we're ok with a single open() here...
880 fd <- throwErrnoIfMinus1Retry "openFile"
881 (c_open f (fromIntegral oflags) 0o666)
882
883 fd_type <- fdType fd
884
885 h <- openFd fd (Just fd_type) False filepath mode binary
886 `catchException` \e -> do c_close fd; throw e
887 -- NB. don't forget to close the FD if openFd fails, otherwise
888 -- this FD leaks.
889 -- ASSERT: if we just created the file, then openFd won't fail
890 -- (so we don't need to worry about removing the newly created file
891 -- in the event of an error).
892
893 #ifndef mingw32_HOST_OS
894 -- we want to truncate() if this is an open in WriteMode, but only
895 -- if the target is a RegularFile. ftruncate() fails on special files
896 -- like /dev/null.
897 if mode == WriteMode && fd_type == RegularFile
898 then throwErrnoIf (/=0) "openFile"
899 (c_ftruncate fd 0)
900 else return 0
901 #endif
902 return h
903
904
905 -- | The function creates a temporary file in ReadWrite mode.
906 -- The created file isn\'t deleted automatically, so you need to delete it manually.
907 openTempFile :: FilePath -- ^ Directory in which to create the file
908 -> String -- ^ File name template. If the template is \"foo.ext\" then
909 -- the create file will be \"fooXXX.ext\" where XXX is some
910 -- random number.
911 -> IO (FilePath, Handle)
912 openTempFile tmp_dir template = openTempFile' "openTempFile" tmp_dir template dEFAULT_OPEN_IN_BINARY_MODE
913
914 -- | Like 'openTempFile', but opens the file in binary mode. See 'openBinaryFile' for more comments.
915 openBinaryTempFile :: FilePath -> String -> IO (FilePath, Handle)
916 openBinaryTempFile tmp_dir template = openTempFile' "openBinaryTempFile" tmp_dir template True
917
918 openTempFile' :: String -> FilePath -> String -> Bool -> IO (FilePath, Handle)
919 openTempFile' loc tmp_dir template binary = do
920 pid <- c_getpid
921 findTempName pid
922 where
923 (prefix,suffix) = break (=='.') template
924
925 oflags1 = rw_flags .|. o_EXCL
926
927 binary_flags
928 | binary = o_BINARY
929 | otherwise = 0
930
931 oflags = oflags1 .|. binary_flags
932
933 findTempName x = do
934 fd <- withCString filepath $ \ f ->
935 c_open f oflags 0o666
936 if fd < 0
937 then do
938 errno <- getErrno
939 if errno == eEXIST
940 then findTempName (x+1)
941 else ioError (errnoToIOError loc errno Nothing (Just tmp_dir))
942 else do
943 h <- openFd fd Nothing False filepath ReadWriteMode True
944 `catchException` \e -> do c_close fd; throw e
945 return (filepath, h)
946 where
947 filename = prefix ++ show x ++ suffix
948 filepath = tmp_dir `joinFileName` filename
949
950
951 std_flags = o_NONBLOCK .|. o_NOCTTY
952 output_flags = std_flags .|. o_CREAT
953 read_flags = std_flags .|. o_RDONLY
954 write_flags = output_flags .|. o_WRONLY
955 rw_flags = output_flags .|. o_RDWR
956 append_flags = write_flags .|. o_APPEND
957
958 -- ---------------------------------------------------------------------------
959 -- openFd
960
961 openFd :: FD -> Maybe FDType -> Bool -> FilePath -> IOMode -> Bool -> IO Handle
962 openFd fd mb_fd_type is_socket filepath mode binary = do
963 -- turn on non-blocking mode
964 setNonBlockingFD fd
965
966 #ifdef mingw32_HOST_OS
967 -- On Windows, the is_stream flag indicates that the Handle is a socket
968 let is_stream = is_socket
969 #else
970 -- On Unix, the is_stream flag indicates that the FD is non-blocking
971 let is_stream = True
972 #endif
973
974 let (ha_type, write) =
975 case mode of
976 ReadMode -> ( ReadHandle, False )
977 WriteMode -> ( WriteHandle, True )
978 ReadWriteMode -> ( ReadWriteHandle, True )
979 AppendMode -> ( AppendHandle, True )
980
981 -- open() won't tell us if it was a directory if we only opened for
982 -- reading, so check again.
983 fd_type <-
984 case mb_fd_type of
985 Just x -> return x
986 Nothing -> fdType fd
987
988 case fd_type of
989 Directory ->
990 ioException (IOError Nothing InappropriateType "openFile"
991 "is a directory" Nothing)
992
993 -- regular files need to be locked
994 RegularFile -> do
995 #ifndef mingw32_HOST_OS
996 r <- lockFile fd (fromBool write) 1{-exclusive-}
997 when (r == -1) $
998 ioException (IOError Nothing ResourceBusy "openFile"
999 "file is locked" Nothing)
1000 #endif
1001 mkFileHandle fd is_stream filepath ha_type binary
1002
1003 Stream
1004 -- only *Streams* can be DuplexHandles. Other read/write
1005 -- Handles must share a buffer.
1006 | ReadWriteHandle <- ha_type ->
1007 mkDuplexHandle fd is_stream filepath binary
1008 | otherwise ->
1009 mkFileHandle fd is_stream filepath ha_type binary
1010
1011 RawDevice ->
1012 mkFileHandle fd is_stream filepath ha_type binary
1013
1014 fdToHandle :: FD -> IO Handle
1015 fdToHandle fd = do
1016 mode <- fdGetMode fd
1017 let fd_str = "<file descriptor: " ++ show fd ++ ">"
1018 openFd fd Nothing False{-XXX!-} fd_str mode True{-bin mode-}
1019
1020
1021 #ifndef mingw32_HOST_OS
1022 foreign import ccall unsafe "lockFile"
1023 lockFile :: CInt -> CInt -> CInt -> IO CInt
1024
1025 foreign import ccall unsafe "unlockFile"
1026 unlockFile :: CInt -> IO CInt
1027 #endif
1028
1029 mkStdHandle :: FD -> FilePath -> HandleType -> IORef Buffer -> BufferMode
1030 -> IO Handle
1031 mkStdHandle fd filepath ha_type buf bmode = do
1032 spares <- newIORef BufferListNil
1033 newFileHandle filepath (stdHandleFinalizer filepath)
1034 (Handle__ { haFD = fd,
1035 haType = ha_type,
1036 haIsBin = dEFAULT_OPEN_IN_BINARY_MODE,
1037 haIsStream = False, -- means FD is blocking on Unix
1038 haBufferMode = bmode,
1039 haBuffer = buf,
1040 haBuffers = spares,
1041 haOtherSide = Nothing
1042 })
1043
1044 mkFileHandle :: FD -> Bool -> FilePath -> HandleType -> Bool -> IO Handle
1045 mkFileHandle fd is_stream filepath ha_type binary = do
1046 (buf, bmode) <- getBuffer fd (initBufferState ha_type)
1047
1048 #ifdef mingw32_HOST_OS
1049 -- On Windows, if this is a read/write handle and we are in text mode,
1050 -- turn off buffering. We don't correctly handle the case of switching
1051 -- from read mode to write mode on a buffered text-mode handle, see bug
1052 -- \#679.
1053 bmode <- case ha_type of
1054 ReadWriteHandle | not binary -> return NoBuffering
1055 _other -> return bmode
1056 #endif
1057
1058 spares <- newIORef BufferListNil
1059 newFileHandle filepath (handleFinalizer filepath)
1060 (Handle__ { haFD = fd,
1061 haType = ha_type,
1062 haIsBin = binary,
1063 haIsStream = is_stream,
1064 haBufferMode = bmode,
1065 haBuffer = buf,
1066 haBuffers = spares,
1067 haOtherSide = Nothing
1068 })
1069
1070 mkDuplexHandle :: FD -> Bool -> FilePath -> Bool -> IO Handle
1071 mkDuplexHandle fd is_stream filepath binary = do
1072 (w_buf, w_bmode) <- getBuffer fd WriteBuffer
1073 w_spares <- newIORef BufferListNil
1074 let w_handle_ =
1075 Handle__ { haFD = fd,
1076 haType = WriteHandle,
1077 haIsBin = binary,
1078 haIsStream = is_stream,
1079 haBufferMode = w_bmode,
1080 haBuffer = w_buf,
1081 haBuffers = w_spares,
1082 haOtherSide = Nothing
1083 }
1084 write_side <- newMVar w_handle_
1085
1086 (r_buf, r_bmode) <- getBuffer fd ReadBuffer
1087 r_spares <- newIORef BufferListNil
1088 let r_handle_ =
1089 Handle__ { haFD = fd,
1090 haType = ReadHandle,
1091 haIsBin = binary,
1092 haIsStream = is_stream,
1093 haBufferMode = r_bmode,
1094 haBuffer = r_buf,
1095 haBuffers = r_spares,
1096 haOtherSide = Just write_side
1097 }
1098 read_side <- newMVar r_handle_
1099
1100 addMVarFinalizer write_side (handleFinalizer filepath write_side)
1101 return (DuplexHandle filepath read_side write_side)
1102
1103
1104 initBufferState ReadHandle = ReadBuffer
1105 initBufferState _ = WriteBuffer
1106
1107 -- ---------------------------------------------------------------------------
1108 -- Closing a handle
1109
1110 -- | Computation 'hClose' @hdl@ makes handle @hdl@ closed. Before the
1111 -- computation finishes, if @hdl@ is writable its buffer is flushed as
1112 -- for 'hFlush'.
1113 -- Performing 'hClose' on a handle that has already been closed has no effect;
1114 -- doing so not an error. All other operations on a closed handle will fail.
1115 -- If 'hClose' fails for any reason, any further operations (apart from
1116 -- 'hClose') on the handle will still fail as if @hdl@ had been successfully
1117 -- closed.
1118
1119 hClose :: Handle -> IO ()
1120 hClose h@(FileHandle _ m) = hClose' h m
1121 hClose h@(DuplexHandle _ r w) = hClose' h w >> hClose' h r
1122
1123 hClose' h m = withHandle__' "hClose" h m $ hClose_help
1124
1125 -- hClose_help is also called by lazyRead (in PrelIO) when EOF is read
1126 -- or an IO error occurs on a lazy stream. The semi-closed Handle is
1127 -- then closed immediately. We have to be careful with DuplexHandles
1128 -- though: we have to leave the closing to the finalizer in that case,
1129 -- because the write side may still be in use.
1130 hClose_help :: Handle__ -> IO Handle__
1131 hClose_help handle_ =
1132 case haType handle_ of
1133 ClosedHandle -> return handle_
1134 _ -> do flushWriteBufferOnly handle_ -- interruptible
1135 hClose_handle_ handle_
1136
1137 hClose_handle_ handle_ = do
1138 let fd = haFD handle_
1139
1140 -- close the file descriptor, but not when this is the read
1141 -- side of a duplex handle.
1142 case haOtherSide handle_ of
1143 Nothing ->
1144 throwErrnoIfMinus1Retry_ "hClose"
1145 #ifdef mingw32_HOST_OS
1146 (closeFd (haIsStream handle_) fd)
1147 #else
1148 (c_close fd)
1149 #endif
1150 Just _ -> return ()
1151
1152 -- free the spare buffers
1153 writeIORef (haBuffers handle_) BufferListNil
1154
1155 #ifndef mingw32_HOST_OS
1156 -- unlock it
1157 unlockFile fd
1158 #endif
1159
1160 -- we must set the fd to -1, because the finalizer is going
1161 -- to run eventually and try to close/unlock it.
1162 return (handle_{ haFD = -1,
1163 haType = ClosedHandle
1164 })
1165
1166 -----------------------------------------------------------------------------
1167 -- Detecting and changing the size of a file
1168
1169 -- | For a handle @hdl@ which attached to a physical file,
1170 -- 'hFileSize' @hdl@ returns the size of that file in 8-bit bytes.
1171
1172 hFileSize :: Handle -> IO Integer
1173 hFileSize handle =
1174 withHandle_ "hFileSize" handle $ \ handle_ -> do
1175 case haType handle_ of
1176 ClosedHandle -> ioe_closedHandle
1177 SemiClosedHandle -> ioe_closedHandle
1178 _ -> do flushWriteBufferOnly handle_
1179 r <- fdFileSize (haFD handle_)
1180 if r /= -1
1181 then return r
1182 else ioException (IOError Nothing InappropriateType "hFileSize"
1183 "not a regular file" Nothing)
1184
1185
1186 -- | 'hSetFileSize' @hdl@ @size@ truncates the physical file with handle @hdl@ to @size@ bytes.
1187
1188 hSetFileSize :: Handle -> Integer -> IO ()
1189 hSetFileSize handle size =
1190 withHandle_ "hSetFileSize" handle $ \ handle_ -> do
1191 case haType handle_ of
1192 ClosedHandle -> ioe_closedHandle
1193 SemiClosedHandle -> ioe_closedHandle
1194 _ -> do flushWriteBufferOnly handle_
1195 throwErrnoIf (/=0) "hSetFileSize"
1196 (c_ftruncate (haFD handle_) (fromIntegral size))
1197 return ()
1198
1199 -- ---------------------------------------------------------------------------
1200 -- Detecting the End of Input
1201
1202 -- | For a readable handle @hdl@, 'hIsEOF' @hdl@ returns
1203 -- 'True' if no further input can be taken from @hdl@ or for a
1204 -- physical file, if the current I\/O position is equal to the length of
1205 -- the file. Otherwise, it returns 'False'.
1206
1207 hIsEOF :: Handle -> IO Bool
1208 hIsEOF handle =
1209 catch
1210 (do hLookAhead handle; return False)
1211 (\e -> if isEOFError e then return True else ioError e)
1212
1213 -- | The computation 'isEOF' is identical to 'hIsEOF',
1214 -- except that it works only on 'stdin'.
1215
1216 isEOF :: IO Bool
1217 isEOF = hIsEOF stdin
1218
1219 -- ---------------------------------------------------------------------------
1220 -- Looking ahead
1221
1222 -- | Computation 'hLookAhead' returns the next character from the handle
1223 -- without removing it from the input buffer, blocking until a character
1224 -- is available.
1225 --
1226 -- This operation may fail with:
1227 --
1228 -- * 'isEOFError' if the end of file has been reached.
1229
1230 hLookAhead :: Handle -> IO Char
1231 hLookAhead handle = do
1232 wantReadableHandle "hLookAhead" handle $ \handle_ -> do
1233 let ref = haBuffer handle_
1234 fd = haFD handle_
1235 is_line = haBufferMode handle_ == LineBuffering
1236 buf <- readIORef ref
1237
1238 -- fill up the read buffer if necessary
1239 new_buf <- if bufferEmpty buf
1240 then fillReadBuffer fd True (haIsStream handle_) buf
1241 else return buf
1242
1243 writeIORef ref new_buf
1244
1245 (c,_) <- readCharFromBuffer (bufBuf buf) (bufRPtr buf)
1246 return c
1247
1248 -- ---------------------------------------------------------------------------
1249 -- Buffering Operations
1250
1251 -- Three kinds of buffering are supported: line-buffering,
1252 -- block-buffering or no-buffering. See GHC.IOBase for definition and
1253 -- further explanation of what the type represent.
1254
1255 -- | Computation 'hSetBuffering' @hdl mode@ sets the mode of buffering for
1256 -- handle @hdl@ on subsequent reads and writes.
1257 --
1258 -- If the buffer mode is changed from 'BlockBuffering' or
1259 -- 'LineBuffering' to 'NoBuffering', then
1260 --
1261 -- * if @hdl@ is writable, the buffer is flushed as for 'hFlush';
1262 --
1263 -- * if @hdl@ is not writable, the contents of the buffer is discarded.
1264 --
1265 -- This operation may fail with:
1266 --
1267 -- * 'isPermissionError' if the handle has already been used for reading
1268 -- or writing and the implementation does not allow the buffering mode
1269 -- to be changed.
1270
1271 hSetBuffering :: Handle -> BufferMode -> IO ()
1272 hSetBuffering handle mode =
1273 withAllHandles__ "hSetBuffering" handle $ \ handle_ -> do
1274 case haType handle_ of
1275 ClosedHandle -> ioe_closedHandle
1276 _ -> do
1277 {- Note:
1278 - we flush the old buffer regardless of whether
1279 the new buffer could fit the contents of the old buffer
1280 or not.
1281 - allow a handle's buffering to change even if IO has
1282 occurred (ANSI C spec. does not allow this, nor did
1283 the previous implementation of IO.hSetBuffering).
1284 - a non-standard extension is to allow the buffering
1285 of semi-closed handles to change [sof 6/98]
1286 -}
1287 flushBuffer handle_
1288
1289 let state = initBufferState (haType handle_)
1290 new_buf <-
1291 case mode of
1292 -- we always have a 1-character read buffer for
1293 -- unbuffered handles: it's needed to
1294 -- support hLookAhead.
1295 NoBuffering -> allocateBuffer 1 ReadBuffer
1296 LineBuffering -> allocateBuffer dEFAULT_BUFFER_SIZE state
1297 BlockBuffering Nothing -> allocateBuffer dEFAULT_BUFFER_SIZE state
1298 BlockBuffering (Just n) | n <= 0 -> ioe_bufsiz n
1299 | otherwise -> allocateBuffer n state
1300 writeIORef (haBuffer handle_) new_buf
1301
1302 -- for input terminals we need to put the terminal into
1303 -- cooked or raw mode depending on the type of buffering.
1304 is_tty <- fdIsTTY (haFD handle_)
1305 when (is_tty && isReadableHandleType (haType handle_)) $
1306 case mode of
1307 #ifndef mingw32_HOST_OS
1308 -- 'raw' mode under win32 is a bit too specialised (and troublesome
1309 -- for most common uses), so simply disable its use here.
1310 NoBuffering -> setCooked (haFD handle_) False
1311 #else
1312 NoBuffering -> return ()
1313 #endif
1314 _ -> setCooked (haFD handle_) True
1315
1316 -- throw away spare buffers, they might be the wrong size
1317 writeIORef (haBuffers handle_) BufferListNil
1318
1319 return (handle_{ haBufferMode = mode })
1320
1321 -- -----------------------------------------------------------------------------
1322 -- hFlush
1323
1324 -- | The action 'hFlush' @hdl@ causes any items buffered for output
1325 -- in handle @hdl@ to be sent immediately to the operating system.
1326 --
1327 -- This operation may fail with:
1328 --
1329 -- * 'isFullError' if the device is full;
1330 --
1331 -- * 'isPermissionError' if a system resource limit would be exceeded.
1332 -- It is unspecified whether the characters in the buffer are discarded
1333 -- or retained under these circumstances.
1334
1335 hFlush :: Handle -> IO ()
1336 hFlush handle =
1337 wantWritableHandle "hFlush" handle $ \ handle_ -> do
1338 buf <- readIORef (haBuffer handle_)
1339 if bufferIsWritable buf && not (bufferEmpty buf)
1340 then do flushed_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
1341 writeIORef (haBuffer handle_) flushed_buf
1342 else return ()
1343
1344
1345 -- -----------------------------------------------------------------------------
1346 -- Repositioning Handles
1347
1348 data HandlePosn = HandlePosn Handle HandlePosition
1349
1350 instance Eq HandlePosn where
1351 (HandlePosn h1 p1) == (HandlePosn h2 p2) = p1==p2 && h1==h2
1352
1353 instance Show HandlePosn where
1354 showsPrec p (HandlePosn h pos) =
1355 showsPrec p h . showString " at position " . shows pos
1356
1357 -- HandlePosition is the Haskell equivalent of POSIX' off_t.
1358 -- We represent it as an Integer on the Haskell side, but
1359 -- cheat slightly in that hGetPosn calls upon a C helper
1360 -- that reports the position back via (merely) an Int.
1361 type HandlePosition = Integer
1362
1363 -- | Computation 'hGetPosn' @hdl@ returns the current I\/O position of
1364 -- @hdl@ as a value of the abstract type 'HandlePosn'.
1365
1366 hGetPosn :: Handle -> IO HandlePosn
1367 hGetPosn handle = do
1368 posn <- hTell handle
1369 return (HandlePosn handle posn)
1370
1371 -- | If a call to 'hGetPosn' @hdl@ returns a position @p@,
1372 -- then computation 'hSetPosn' @p@ sets the position of @hdl@
1373 -- to the position it held at the time of the call to 'hGetPosn'.
1374 --
1375 -- This operation may fail with:
1376 --
1377 -- * 'isPermissionError' if a system resource limit would be exceeded.
1378
1379 hSetPosn :: HandlePosn -> IO ()
1380 hSetPosn (HandlePosn h i) = hSeek h AbsoluteSeek i
1381
1382 -- ---------------------------------------------------------------------------
1383 -- hSeek
1384
1385 -- | A mode that determines the effect of 'hSeek' @hdl mode i@, as follows:
1386 data SeekMode
1387 = AbsoluteSeek -- ^ the position of @hdl@ is set to @i@.
1388 | RelativeSeek -- ^ the position of @hdl@ is set to offset @i@
1389 -- from the current position.
1390 | SeekFromEnd -- ^ the position of @hdl@ is set to offset @i@
1391 -- from the end of the file.
1392 deriving (Eq, Ord, Ix, Enum, Read, Show)
1393
1394 {- Note:
1395 - when seeking using `SeekFromEnd', positive offsets (>=0) means
1396 seeking at or past EOF.
1397
1398 - we possibly deviate from the report on the issue of seeking within
1399 the buffer and whether to flush it or not. The report isn't exactly
1400 clear here.
1401 -}
1402
1403 -- | Computation 'hSeek' @hdl mode i@ sets the position of handle
1404 -- @hdl@ depending on @mode@.
1405 -- The offset @i@ is given in terms of 8-bit bytes.
1406 --
1407 -- If @hdl@ is block- or line-buffered, then seeking to a position which is not
1408 -- in the current buffer will first cause any items in the output buffer to be
1409 -- written to the device, and then cause the input buffer to be discarded.
1410 -- Some handles may not be seekable (see 'hIsSeekable'), or only support a
1411 -- subset of the possible positioning operations (for instance, it may only
1412 -- be possible to seek to the end of a tape, or to a positive offset from
1413 -- the beginning or current position).
1414 -- It is not possible to set a negative I\/O position, or for
1415 -- a physical file, an I\/O position beyond the current end-of-file.
1416 --
1417 -- This operation may fail with:
1418 --
1419 -- * 'isPermissionError' if a system resource limit would be exceeded.
1420
1421 hSeek :: Handle -> SeekMode -> Integer -> IO ()
1422 hSeek handle mode offset =
1423 wantSeekableHandle "hSeek" handle $ \ handle_ -> do
1424 # ifdef DEBUG_DUMP
1425 puts ("hSeek " ++ show (mode,offset) ++ "\n")
1426 # endif
1427 let ref = haBuffer handle_
1428 buf <- readIORef ref
1429 let r = bufRPtr buf
1430 w = bufWPtr buf
1431 fd = haFD handle_
1432
1433 let do_seek =
1434 throwErrnoIfMinus1Retry_ "hSeek"
1435 (c_lseek (haFD handle_) (fromIntegral offset) whence)
1436
1437 whence :: CInt
1438 whence = case mode of
1439 AbsoluteSeek -> sEEK_SET
1440 RelativeSeek -> sEEK_CUR
1441 SeekFromEnd -> sEEK_END
1442
1443 if bufferIsWritable buf
1444 then do new_buf <- flushWriteBuffer fd (haIsStream handle_) buf
1445 writeIORef ref new_buf
1446 do_seek
1447 else do
1448
1449 if mode == RelativeSeek && offset >= 0 && offset < fromIntegral (w - r)
1450 then writeIORef ref buf{ bufRPtr = r + fromIntegral offset }
1451 else do
1452
1453 new_buf <- flushReadBuffer (haFD handle_) buf
1454 writeIORef ref new_buf
1455 do_seek
1456
1457
1458 hTell :: Handle -> IO Integer
1459 hTell handle =
1460 wantSeekableHandle "hGetPosn" handle $ \ handle_ -> do
1461
1462 #if defined(mingw32_HOST_OS)
1463 -- urgh, on Windows we have to worry about \n -> \r\n translation,
1464 -- so we can't easily calculate the file position using the
1465 -- current buffer size. Just flush instead.
1466 flushBuffer handle_
1467 #endif
1468 let fd = haFD handle_
1469 posn <- fromIntegral `liftM`
1470 throwErrnoIfMinus1Retry "hGetPosn"
1471 (c_lseek fd 0 sEEK_CUR)
1472
1473 let ref = haBuffer handle_
1474 buf <- readIORef ref
1475
1476 let real_posn
1477 | bufferIsWritable buf = posn + fromIntegral (bufWPtr buf)
1478 | otherwise = posn - fromIntegral (bufWPtr buf - bufRPtr buf)
1479 # ifdef DEBUG_DUMP
1480 puts ("\nhGetPosn: (fd, posn, real_posn) = " ++ show (fd, posn, real_posn) ++ "\n")
1481 puts (" (bufWPtr, bufRPtr) = " ++ show (bufWPtr buf, bufRPtr buf) ++ "\n")
1482 # endif
1483 return real_posn
1484
1485 -- -----------------------------------------------------------------------------
1486 -- Handle Properties
1487
1488 -- A number of operations return information about the properties of a
1489 -- handle. Each of these operations returns `True' if the handle has
1490 -- the specified property, and `False' otherwise.
1491
1492 hIsOpen :: Handle -> IO Bool
1493 hIsOpen handle =
1494 withHandle_ "hIsOpen" handle $ \ handle_ -> do
1495 case haType handle_ of
1496 ClosedHandle -> return False
1497 SemiClosedHandle -> return False
1498 _ -> return True
1499
1500 hIsClosed :: Handle -> IO Bool
1501 hIsClosed handle =
1502 withHandle_ "hIsClosed" handle $ \ handle_ -> do
1503 case haType handle_ of
1504 ClosedHandle -> return True
1505 _ -> return False
1506
1507 {- not defined, nor exported, but mentioned
1508 here for documentation purposes:
1509
1510 hSemiClosed :: Handle -> IO Bool
1511 hSemiClosed h = do
1512 ho <- hIsOpen h
1513 hc <- hIsClosed h
1514 return (not (ho || hc))
1515 -}
1516
1517 hIsReadable :: Handle -> IO Bool
1518 hIsReadable (DuplexHandle _ _ _) = return True
1519 hIsReadable handle =
1520 withHandle_ "hIsReadable" handle $ \ handle_ -> do
1521 case haType handle_ of
1522 ClosedHandle -> ioe_closedHandle
1523 SemiClosedHandle -> ioe_closedHandle
1524 htype -> return (isReadableHandleType htype)
1525
1526 hIsWritable :: Handle -> IO Bool
1527 hIsWritable (DuplexHandle _ _ _) = return True
1528 hIsWritable handle =
1529 withHandle_ "hIsWritable" handle $ \ handle_ -> do
1530 case haType handle_ of
1531 ClosedHandle -> ioe_closedHandle
1532 SemiClosedHandle -> ioe_closedHandle
1533 htype -> return (isWritableHandleType htype)
1534
1535 -- | Computation 'hGetBuffering' @hdl@ returns the current buffering mode
1536 -- for @hdl@.
1537
1538 hGetBuffering :: Handle -> IO BufferMode
1539 hGetBuffering handle =
1540 withHandle_ "hGetBuffering" handle $ \ handle_ -> do
1541 case haType handle_ of
1542 ClosedHandle -> ioe_closedHandle
1543 _ ->
1544 -- We're being non-standard here, and allow the buffering
1545 -- of a semi-closed handle to be queried. -- sof 6/98
1546 return (haBufferMode handle_) -- could be stricter..
1547
1548 hIsSeekable :: Handle -> IO Bool
1549 hIsSeekable handle =
1550 withHandle_ "hIsSeekable" handle $ \ handle_ -> do
1551 case haType handle_ of
1552 ClosedHandle -> ioe_closedHandle
1553 SemiClosedHandle -> ioe_closedHandle
1554 AppendHandle -> return False
1555 _ -> do t <- fdType (haFD handle_)
1556 return ((t == RegularFile || t == RawDevice)
1557 && (haIsBin handle_ || tEXT_MODE_SEEK_ALLOWED))
1558
1559 -- -----------------------------------------------------------------------------
1560 -- Changing echo status (Non-standard GHC extensions)
1561
1562 -- | Set the echoing status of a handle connected to a terminal.
1563
1564 hSetEcho :: Handle -> Bool -> IO ()
1565 hSetEcho handle on = do
1566 isT <- hIsTerminalDevice handle
1567 if not isT
1568 then return ()
1569 else
1570 withHandle_ "hSetEcho" handle $ \ handle_ -> do
1571 case haType handle_ of
1572 ClosedHandle -> ioe_closedHandle
1573 _ -> setEcho (haFD handle_) on
1574
1575 -- | Get the echoing status of a handle connected to a terminal.
1576
1577 hGetEcho :: Handle -> IO Bool
1578 hGetEcho handle = do
1579 isT <- hIsTerminalDevice handle
1580 if not isT
1581 then return False
1582 else
1583 withHandle_ "hGetEcho" handle $ \ handle_ -> do
1584 case haType handle_ of
1585 ClosedHandle -> ioe_closedHandle
1586 _ -> getEcho (haFD handle_)
1587
1588 -- | Is the handle connected to a terminal?
1589
1590 hIsTerminalDevice :: Handle -> IO Bool
1591 hIsTerminalDevice handle = do
1592 withHandle_ "hIsTerminalDevice" handle $ \ handle_ -> do
1593 case haType handle_ of
1594 ClosedHandle -> ioe_closedHandle
1595 _ -> fdIsTTY (haFD handle_)
1596
1597 -- -----------------------------------------------------------------------------
1598 -- hSetBinaryMode
1599
1600 -- | Select binary mode ('True') or text mode ('False') on a open handle.
1601 -- (See also 'openBinaryFile'.)
1602
1603 hSetBinaryMode :: Handle -> Bool -> IO ()
1604 hSetBinaryMode handle bin =
1605 withAllHandles__ "hSetBinaryMode" handle $ \ handle_ ->
1606 do throwErrnoIfMinus1_ "hSetBinaryMode"
1607 (setmode (haFD handle_) bin)
1608 return handle_{haIsBin=bin}
1609
1610 foreign import ccall unsafe "__hscore_setmode"
1611 setmode :: CInt -> Bool -> IO CInt
1612
1613 -- -----------------------------------------------------------------------------
1614 -- Duplicating a Handle
1615
1616 -- | Returns a duplicate of the original handle, with its own buffer.
1617 -- The two Handles will share a file pointer, however. The original
1618 -- handle's buffer is flushed, including discarding any input data,
1619 -- before the handle is duplicated.
1620
1621 hDuplicate :: Handle -> IO Handle
1622 hDuplicate h@(FileHandle path m) = do
1623 new_h_ <- withHandle' "hDuplicate" h m (dupHandle h Nothing)
1624 newFileHandle path (handleFinalizer path) new_h_
1625 hDuplicate h@(DuplexHandle path r w) = do
1626 new_w_ <- withHandle' "hDuplicate" h w (dupHandle h Nothing)
1627 new_w <- newMVar new_w_
1628 new_r_ <- withHandle' "hDuplicate" h r (dupHandle h (Just new_w))
1629 new_r <- newMVar new_r_
1630 addMVarFinalizer new_w (handleFinalizer path new_w)
1631 return (DuplexHandle path new_r new_w)
1632
1633 dupHandle :: Handle -> Maybe (MVar Handle__) -> Handle__
1634 -> IO (Handle__, Handle__)
1635 dupHandle h other_side h_ = do
1636 -- flush the buffer first, so we don't have to copy its contents
1637 flushBuffer h_
1638 new_fd <- case other_side of
1639 Nothing -> throwErrnoIfMinus1 "dupHandle" $ c_dup (haFD h_)
1640 Just r -> withHandle_' "dupHandle" h r (return . haFD)
1641 dupHandle_ other_side h_ new_fd
1642
1643 dupHandleTo other_side hto_ h_ = do
1644 flushBuffer h_
1645 -- Windows' dup2 does not return the new descriptor, unlike Unix
1646 throwErrnoIfMinus1 "dupHandleTo" $
1647 c_dup2 (haFD h_) (haFD hto_)
1648 dupHandle_ other_side h_ (haFD hto_)
1649
1650 dupHandle_ :: Maybe (MVar Handle__) -> Handle__ -> FD
1651 -> IO (Handle__, Handle__)
1652 dupHandle_ other_side h_ new_fd = do
1653 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE (initBufferState (haType h_))
1654 ioref <- newIORef buffer
1655 ioref_buffers <- newIORef BufferListNil
1656
1657 let new_handle_ = h_{ haFD = new_fd,
1658 haBuffer = ioref,
1659 haBuffers = ioref_buffers,
1660 haOtherSide = other_side }
1661 return (h_, new_handle_)
1662
1663 -- -----------------------------------------------------------------------------
1664 -- Replacing a Handle
1665
1666 {- |
1667 Makes the second handle a duplicate of the first handle. The second
1668 handle will be closed first, if it is not already.
1669
1670 This can be used to retarget the standard Handles, for example:
1671
1672 > do h <- openFile "mystdout" WriteMode
1673 > hDuplicateTo h stdout
1674 -}
1675
1676 hDuplicateTo :: Handle -> Handle -> IO ()
1677 hDuplicateTo h1@(FileHandle _ m1) h2@(FileHandle _ m2) = do
1678 withHandle__' "hDuplicateTo" h2 m2 $ \h2_ -> do
1679 _ <- hClose_help h2_
1680 withHandle' "hDuplicateTo" h1 m1 (dupHandleTo Nothing h2_)
1681 hDuplicateTo h1@(DuplexHandle _ r1 w1) h2@(DuplexHandle _ r2 w2) = do
1682 withHandle__' "hDuplicateTo" h2 w2 $ \w2_ -> do
1683 _ <- hClose_help w2_
1684 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo Nothing w2_)
1685 withHandle__' "hDuplicateTo" h2 r2 $ \r2_ -> do
1686 _ <- hClose_help r2_
1687 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo (Just w1) r2_)
1688 hDuplicateTo h1 _ =
1689 ioException (IOError (Just h1) IllegalOperation "hDuplicateTo"
1690 "handles are incompatible" Nothing)
1691
1692 -- ---------------------------------------------------------------------------
1693 -- showing Handles.
1694 --
1695 -- | 'hShow' is in the 'IO' monad, and gives more comprehensive output
1696 -- than the (pure) instance of 'Show' for 'Handle'.
1697
1698 hShow :: Handle -> IO String
1699 hShow h@(FileHandle path _) = showHandle' path False h
1700 hShow h@(DuplexHandle path _ _) = showHandle' path True h
1701
1702 showHandle' filepath is_duplex h =
1703 withHandle_ "showHandle" h $ \hdl_ ->
1704 let
1705 showType | is_duplex = showString "duplex (read-write)"
1706 | otherwise = shows (haType hdl_)
1707 in
1708 return
1709 (( showChar '{' .
1710 showHdl (haType hdl_)
1711 (showString "loc=" . showString filepath . showChar ',' .
1712 showString "type=" . showType . showChar ',' .
1713 showString "binary=" . shows (haIsBin hdl_) . showChar ',' .
1714 showString "buffering=" . showBufMode (unsafePerformIO (readIORef (haBuffer hdl_))) (haBufferMode hdl_) . showString "}" )
1715 ) "")
1716 where
1717
1718 showHdl :: HandleType -> ShowS -> ShowS
1719 showHdl ht cont =
1720 case ht of
1721 ClosedHandle -> shows ht . showString "}"
1722 _ -> cont
1723
1724 showBufMode :: Buffer -> BufferMode -> ShowS
1725 showBufMode buf bmo =
1726 case bmo of
1727 NoBuffering -> showString "none"
1728 LineBuffering -> showString "line"
1729 BlockBuffering (Just n) -> showString "block " . showParen True (shows n)
1730 BlockBuffering Nothing -> showString "block " . showParen True (shows def)
1731 where
1732 def :: Int
1733 def = bufSize buf
1734
1735 -- ---------------------------------------------------------------------------
1736 -- debugging
1737
1738 #if defined(DEBUG_DUMP)
1739 puts :: String -> IO ()
1740 puts s = do write_rawBuffer 1 (unsafeCoerce# (packCString# s)) 0 (fromIntegral (length s))
1741 return ()
1742 #endif
1743
1744 -- -----------------------------------------------------------------------------
1745 -- utils
1746
1747 throwErrnoIfMinus1RetryOnBlock :: String -> IO CInt -> IO CInt -> IO CInt
1748 throwErrnoIfMinus1RetryOnBlock loc f on_block =
1749 do
1750 res <- f
1751 if (res :: CInt) == -1
1752 then do
1753 err <- getErrno
1754 if err == eINTR
1755 then throwErrnoIfMinus1RetryOnBlock loc f on_block
1756 else if err == eWOULDBLOCK || err == eAGAIN
1757 then do on_block
1758 else throwErrno loc
1759 else return res
1760
1761 -- -----------------------------------------------------------------------------
1762 -- wrappers to platform-specific constants:
1763
1764 foreign import ccall unsafe "__hscore_supportsTextMode"
1765 tEXT_MODE_SEEK_ALLOWED :: Bool
1766
1767 foreign import ccall unsafe "__hscore_bufsiz" dEFAULT_BUFFER_SIZE :: Int
1768 foreign import ccall unsafe "__hscore_seek_cur" sEEK_CUR :: CInt
1769 foreign import ccall unsafe "__hscore_seek_set" sEEK_SET :: CInt
1770 foreign import ccall unsafe "__hscore_seek_end" sEEK_END :: CInt