FIX: #724 (tee complains if used in a process started by ghc)
[packages/old-locale.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 unsafe_read = throwErrnoIfMinus1RetryMayBlock loc
566 (read_rawBuffer fd buf off len)
567 (threadWaitRead (fromIntegral fd))
568 safe_read = throwErrnoIfMinus1Retry loc
569 (safe_read_rawBuffer fd buf off len)
570
571 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
572 readRawBufferPtr loc fd is_nonblock buf off len
573 | is_nonblock = unsafe_read
574 | threaded = safe_read
575 | otherwise = do r <- throwErrnoIfMinus1 loc
576 (fdReady (fromIntegral fd) 0 0 False)
577 if r /= 0
578 then unsafe_read
579 else do threadWaitRead (fromIntegral fd); unsafe_read
580 where
581 unsafe_read = throwErrnoIfMinus1RetryMayBlock loc
582 (read_off fd buf off len)
583 (threadWaitRead (fromIntegral fd))
584 safe_read = throwErrnoIfMinus1Retry loc
585 (safe_read_off fd buf off len)
586
587 readRawBufferNoBlock :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
588 readRawBufferNoBlock loc fd is_nonblock buf off len
589 | is_nonblock = unsafe_read
590 | otherwise = do r <- fdReady (fromIntegral fd) 0 0 False
591 if r /= 0 then safe_read
592 else return 0
593 -- XXX see note [nonblock]
594 where
595 unsafe_read = throwErrnoIfMinus1RetryOnBlock loc
596 (read_rawBuffer fd buf off len)
597 (return 0)
598 safe_read = throwErrnoIfMinus1Retry loc
599 (safe_read_rawBuffer fd buf off len)
600
601 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
602 writeRawBuffer loc fd is_nonblock buf off len
603 | is_nonblock = unsafe_write
604 | threaded = safe_write
605 | otherwise = do r <- fdReady (fromIntegral fd) 1 0 False
606 if r /= 0 then safe_write
607 else return 0
608 where
609 unsafe_write = throwErrnoIfMinus1RetryMayBlock loc
610 (write_rawBuffer fd buf off len)
611 (threadWaitWrite (fromIntegral fd))
612 safe_write = throwErrnoIfMinus1Retry loc
613 (safe_write_rawBuffer (fromIntegral fd) buf off len)
614
615 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
616 writeRawBufferPtr loc fd is_nonblock buf off len
617 | is_nonblock = unsafe_write
618 | threaded = safe_write
619 | otherwise = do r <- fdReady (fromIntegral fd) 1 0 False
620 if r /= 0 then safe_write
621 else return 0
622 where
623 unsafe_write = throwErrnoIfMinus1RetryMayBlock loc
624 (write_off fd buf off len)
625 (threadWaitWrite (fromIntegral fd))
626 safe_write = throwErrnoIfMinus1Retry loc
627 (safe_write_off (fromIntegral fd) buf off len)
628
629 foreign import ccall unsafe "__hscore_PrelHandle_read"
630 read_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
631
632 foreign import ccall unsafe "__hscore_PrelHandle_read"
633 read_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
634
635 foreign import ccall unsafe "__hscore_PrelHandle_write"
636 write_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
637
638 foreign import ccall unsafe "__hscore_PrelHandle_write"
639 write_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
640
641 foreign import ccall safe "fdReady"
642 fdReady :: CInt -> CInt -> CInt -> Bool -> IO CInt
643
644 #else /* mingw32_HOST_OS.... */
645
646 readRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
647 readRawBuffer loc fd is_stream buf off len
648 | threaded = blockingReadRawBuffer loc fd is_stream buf off len
649 | otherwise = asyncReadRawBuffer loc fd is_stream buf off len
650
651 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
652 readRawBufferPtr loc fd is_stream buf off len
653 | threaded = blockingReadRawBufferPtr loc fd is_stream buf off len
654 | otherwise = asyncReadRawBufferPtr loc fd is_stream buf off len
655
656 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
657 writeRawBuffer loc fd is_stream buf off len
658 | threaded = blockingWriteRawBuffer loc fd is_stream buf off len
659 | otherwise = asyncWriteRawBuffer loc fd is_stream buf off len
660
661 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
662 writeRawBufferPtr loc fd is_stream buf off len
663 | threaded = blockingWriteRawBufferPtr loc fd is_stream buf off len
664 | otherwise = asyncWriteRawBufferPtr loc fd is_stream buf off len
665
666 -- ToDo: we don't have a non-blocking primitve read on Win32
667 readRawBufferNoBlock :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
668 readRawBufferNoBlock = readRawBuffer
669
670 -- Async versions of the read/write primitives, for the non-threaded RTS
671
672 asyncReadRawBuffer loc fd is_stream buf off len = do
673 (l, rc) <- asyncReadBA (fromIntegral fd) (if is_stream then 1 else 0)
674 (fromIntegral len) off buf
675 if l == (-1)
676 then
677 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
678 else return (fromIntegral l)
679
680 asyncReadRawBufferPtr loc fd is_stream buf off len = do
681 (l, rc) <- asyncRead (fromIntegral fd) (if is_stream then 1 else 0)
682 (fromIntegral len) (buf `plusPtr` off)
683 if l == (-1)
684 then
685 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
686 else return (fromIntegral l)
687
688 asyncWriteRawBuffer loc fd is_stream buf off len = do
689 (l, rc) <- asyncWriteBA (fromIntegral fd) (if is_stream then 1 else 0)
690 (fromIntegral len) off buf
691 if l == (-1)
692 then
693 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
694 else return (fromIntegral l)
695
696 asyncWriteRawBufferPtr loc fd is_stream buf off len = do
697 (l, rc) <- asyncWrite (fromIntegral fd) (if is_stream then 1 else 0)
698 (fromIntegral len) (buf `plusPtr` off)
699 if l == (-1)
700 then
701 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
702 else return (fromIntegral l)
703
704 -- Blocking versions of the read/write primitives, for the threaded RTS
705
706 blockingReadRawBuffer loc fd True buf off len =
707 throwErrnoIfMinus1Retry loc $
708 safe_recv_rawBuffer fd buf off len
709 blockingReadRawBuffer loc fd False buf off len =
710 throwErrnoIfMinus1Retry loc $
711 safe_read_rawBuffer fd buf off len
712
713 blockingReadRawBufferPtr loc fd True buf off len =
714 throwErrnoIfMinus1Retry loc $
715 safe_recv_off fd buf off len
716 blockingReadRawBufferPtr loc fd False buf off len =
717 throwErrnoIfMinus1Retry loc $
718 safe_read_off fd buf off len
719
720 blockingWriteRawBuffer loc fd True buf off len =
721 throwErrnoIfMinus1Retry loc $
722 safe_send_rawBuffer fd buf off len
723 blockingWriteRawBuffer loc fd False buf off len =
724 throwErrnoIfMinus1Retry loc $
725 safe_write_rawBuffer fd buf off len
726
727 blockingWriteRawBufferPtr loc fd True buf off len =
728 throwErrnoIfMinus1Retry loc $
729 safe_send_off fd buf off len
730 blockingWriteRawBufferPtr loc fd False buf off len =
731 throwErrnoIfMinus1Retry loc $
732 safe_write_off fd buf off len
733
734 -- NOTE: "safe" versions of the read/write calls for use by the threaded RTS.
735 -- These calls may block, but that's ok.
736
737 foreign import ccall safe "__hscore_PrelHandle_recv"
738 safe_recv_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
739
740 foreign import ccall safe "__hscore_PrelHandle_recv"
741 safe_recv_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
742
743 foreign import ccall safe "__hscore_PrelHandle_send"
744 safe_send_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
745
746 foreign import ccall safe "__hscore_PrelHandle_send"
747 safe_send_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
748
749 #endif
750
751 foreign import ccall "rtsSupportsBoundThreads" threaded :: Bool
752
753 foreign import ccall safe "__hscore_PrelHandle_read"
754 safe_read_rawBuffer :: FD -> RawBuffer -> Int -> CInt -> IO CInt
755
756 foreign import ccall safe "__hscore_PrelHandle_read"
757 safe_read_off :: FD -> Ptr CChar -> Int -> CInt -> IO CInt
758
759 foreign import ccall safe "__hscore_PrelHandle_write"
760 safe_write_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
761
762 foreign import ccall safe "__hscore_PrelHandle_write"
763 safe_write_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
764
765 -- ---------------------------------------------------------------------------
766 -- Standard Handles
767
768 -- Three handles are allocated during program initialisation. The first
769 -- two manage input or output from the Haskell program's standard input
770 -- or output channel respectively. The third manages output to the
771 -- standard error channel. These handles are initially open.
772
773 fd_stdin = 0 :: FD
774 fd_stdout = 1 :: FD
775 fd_stderr = 2 :: FD
776
777 -- | A handle managing input from the Haskell program's standard input channel.
778 stdin :: Handle
779 stdin = unsafePerformIO $ do
780 -- ToDo: acquire lock
781 -- We don't set non-blocking mode on standard handles, because it may
782 -- confuse other applications attached to the same TTY/pipe
783 -- see Note [nonblock]
784 (buf, bmode) <- getBuffer fd_stdin ReadBuffer
785 mkStdHandle fd_stdin "<stdin>" ReadHandle buf bmode
786
787 -- | A handle managing output to the Haskell program's standard output channel.
788 stdout :: Handle
789 stdout = unsafePerformIO $ do
790 -- ToDo: acquire lock
791 -- We don't set non-blocking mode on standard handles, because it may
792 -- confuse other applications attached to the same TTY/pipe
793 -- see Note [nonblock]
794 (buf, bmode) <- getBuffer fd_stdout WriteBuffer
795 mkStdHandle fd_stdout "<stdout>" WriteHandle buf bmode
796
797 -- | A handle managing output to the Haskell program's standard error channel.
798 stderr :: Handle
799 stderr = unsafePerformIO $ do
800 -- ToDo: acquire lock
801 -- We don't set non-blocking mode on standard handles, because it may
802 -- confuse other applications attached to the same TTY/pipe
803 -- see Note [nonblock]
804 buf <- mkUnBuffer
805 mkStdHandle fd_stderr "<stderr>" WriteHandle buf NoBuffering
806
807 -- ---------------------------------------------------------------------------
808 -- Opening and Closing Files
809
810 addFilePathToIOError fun fp (IOError h iot _ str _)
811 = IOError h iot fun str (Just fp)
812
813 -- | Computation 'openFile' @file mode@ allocates and returns a new, open
814 -- handle to manage the file @file@. It manages input if @mode@
815 -- is 'ReadMode', output if @mode@ is 'WriteMode' or 'AppendMode',
816 -- and both input and output if mode is 'ReadWriteMode'.
817 --
818 -- If the file does not exist and it is opened for output, it should be
819 -- created as a new file. If @mode@ is 'WriteMode' and the file
820 -- already exists, then it should be truncated to zero length.
821 -- Some operating systems delete empty files, so there is no guarantee
822 -- that the file will exist following an 'openFile' with @mode@
823 -- 'WriteMode' unless it is subsequently written to successfully.
824 -- The handle is positioned at the end of the file if @mode@ is
825 -- 'AppendMode', and otherwise at the beginning (in which case its
826 -- internal position is 0).
827 -- The initial buffer mode is implementation-dependent.
828 --
829 -- This operation may fail with:
830 --
831 -- * 'isAlreadyInUseError' if the file is already open and cannot be reopened;
832 --
833 -- * 'isDoesNotExistError' if the file does not exist; or
834 --
835 -- * 'isPermissionError' if the user does not have permission to open the file.
836 --
837 -- Note: if you will be working with files containing binary data, you'll want to
838 -- be using 'openBinaryFile'.
839 openFile :: FilePath -> IOMode -> IO Handle
840 openFile fp im =
841 catch
842 (openFile' fp im dEFAULT_OPEN_IN_BINARY_MODE)
843 (\e -> ioError (addFilePathToIOError "openFile" fp e))
844
845 -- | Like 'openFile', but open the file in binary mode.
846 -- On Windows, reading a file in text mode (which is the default)
847 -- will translate CRLF to LF, and writing will translate LF to CRLF.
848 -- This is usually what you want with text files. With binary files
849 -- this is undesirable; also, as usual under Microsoft operating systems,
850 -- text mode treats control-Z as EOF. Binary mode turns off all special
851 -- treatment of end-of-line and end-of-file characters.
852 -- (See also 'hSetBinaryMode'.)
853
854 openBinaryFile :: FilePath -> IOMode -> IO Handle
855 openBinaryFile fp m =
856 catch
857 (openFile' fp m True)
858 (\e -> ioError (addFilePathToIOError "openBinaryFile" fp e))
859
860 openFile' filepath mode binary =
861 withCString filepath $ \ f ->
862
863 let
864 oflags1 = case mode of
865 ReadMode -> read_flags
866 #ifdef mingw32_HOST_OS
867 WriteMode -> write_flags .|. o_TRUNC
868 #else
869 WriteMode -> write_flags
870 #endif
871 ReadWriteMode -> rw_flags
872 AppendMode -> append_flags
873
874 binary_flags
875 | binary = o_BINARY
876 | otherwise = 0
877
878 oflags = oflags1 .|. binary_flags
879 in do
880
881 -- the old implementation had a complicated series of three opens,
882 -- which is perhaps because we have to be careful not to open
883 -- directories. However, the man pages I've read say that open()
884 -- always returns EISDIR if the file is a directory and was opened
885 -- for writing, so I think we're ok with a single open() here...
886 fd <- throwErrnoIfMinus1Retry "openFile"
887 (c_open f (fromIntegral oflags) 0o666)
888
889 fd_type <- fdType fd
890
891 h <- openFd fd (Just fd_type) False filepath mode binary
892 `catchException` \e -> do c_close fd; throw e
893 -- NB. don't forget to close the FD if openFd fails, otherwise
894 -- this FD leaks.
895 -- ASSERT: if we just created the file, then openFd won't fail
896 -- (so we don't need to worry about removing the newly created file
897 -- in the event of an error).
898
899 #ifndef mingw32_HOST_OS
900 -- we want to truncate() if this is an open in WriteMode, but only
901 -- if the target is a RegularFile. ftruncate() fails on special files
902 -- like /dev/null.
903 if mode == WriteMode && fd_type == RegularFile
904 then throwErrnoIf (/=0) "openFile"
905 (c_ftruncate fd 0)
906 else return 0
907 #endif
908 return h
909
910
911 -- | The function creates a temporary file in ReadWrite mode.
912 -- The created file isn\'t deleted automatically, so you need to delete it manually.
913 openTempFile :: FilePath -- ^ Directory in which to create the file
914 -> String -- ^ File name template. If the template is \"foo.ext\" then
915 -- the create file will be \"fooXXX.ext\" where XXX is some
916 -- random number.
917 -> IO (FilePath, Handle)
918 openTempFile tmp_dir template = openTempFile' "openTempFile" tmp_dir template dEFAULT_OPEN_IN_BINARY_MODE
919
920 -- | Like 'openTempFile', but opens the file in binary mode. See 'openBinaryFile' for more comments.
921 openBinaryTempFile :: FilePath -> String -> IO (FilePath, Handle)
922 openBinaryTempFile tmp_dir template = openTempFile' "openBinaryTempFile" tmp_dir template True
923
924 openTempFile' :: String -> FilePath -> String -> Bool -> IO (FilePath, Handle)
925 openTempFile' loc tmp_dir template binary = do
926 pid <- c_getpid
927 findTempName pid
928 where
929 (prefix,suffix) = break (=='.') template
930
931 oflags1 = rw_flags .|. o_EXCL
932
933 binary_flags
934 | binary = o_BINARY
935 | otherwise = 0
936
937 oflags = oflags1 .|. binary_flags
938
939 findTempName x = do
940 fd <- withCString filepath $ \ f ->
941 c_open f oflags 0o666
942 if fd < 0
943 then do
944 errno <- getErrno
945 if errno == eEXIST
946 then findTempName (x+1)
947 else ioError (errnoToIOError loc errno Nothing (Just tmp_dir))
948 else do
949 h <- openFd fd Nothing False filepath ReadWriteMode True
950 `catchException` \e -> do c_close fd; throw e
951 return (filepath, h)
952 where
953 filename = prefix ++ show x ++ suffix
954 filepath = tmp_dir `joinFileName` filename
955
956
957 std_flags = o_NONBLOCK .|. o_NOCTTY
958 output_flags = std_flags .|. o_CREAT
959 read_flags = std_flags .|. o_RDONLY
960 write_flags = output_flags .|. o_WRONLY
961 rw_flags = output_flags .|. o_RDWR
962 append_flags = write_flags .|. o_APPEND
963
964 -- ---------------------------------------------------------------------------
965 -- openFd
966
967 openFd :: FD -> Maybe FDType -> Bool -> FilePath -> IOMode -> Bool -> IO Handle
968 openFd fd mb_fd_type is_socket filepath mode binary = do
969 -- turn on non-blocking mode
970 setNonBlockingFD fd
971
972 #ifdef mingw32_HOST_OS
973 -- On Windows, the is_stream flag indicates that the Handle is a socket
974 let is_stream = is_socket
975 #else
976 -- On Unix, the is_stream flag indicates that the FD is non-blocking
977 let is_stream = True
978 #endif
979
980 let (ha_type, write) =
981 case mode of
982 ReadMode -> ( ReadHandle, False )
983 WriteMode -> ( WriteHandle, True )
984 ReadWriteMode -> ( ReadWriteHandle, True )
985 AppendMode -> ( AppendHandle, True )
986
987 -- open() won't tell us if it was a directory if we only opened for
988 -- reading, so check again.
989 fd_type <-
990 case mb_fd_type of
991 Just x -> return x
992 Nothing -> fdType fd
993
994 case fd_type of
995 Directory ->
996 ioException (IOError Nothing InappropriateType "openFile"
997 "is a directory" Nothing)
998
999 -- regular files need to be locked
1000 RegularFile -> do
1001 #ifndef mingw32_HOST_OS
1002 r <- lockFile fd (fromBool write) 1{-exclusive-}
1003 when (r == -1) $
1004 ioException (IOError Nothing ResourceBusy "openFile"
1005 "file is locked" Nothing)
1006 #endif
1007 mkFileHandle fd is_stream filepath ha_type binary
1008
1009 Stream
1010 -- only *Streams* can be DuplexHandles. Other read/write
1011 -- Handles must share a buffer.
1012 | ReadWriteHandle <- ha_type ->
1013 mkDuplexHandle fd is_stream filepath binary
1014 | otherwise ->
1015 mkFileHandle fd is_stream filepath ha_type binary
1016
1017 RawDevice ->
1018 mkFileHandle fd is_stream filepath ha_type binary
1019
1020 fdToHandle :: FD -> IO Handle
1021 fdToHandle fd = do
1022 mode <- fdGetMode fd
1023 let fd_str = "<file descriptor: " ++ show fd ++ ">"
1024 openFd fd Nothing False{-XXX!-} fd_str mode True{-bin mode-}
1025
1026
1027 #ifndef mingw32_HOST_OS
1028 foreign import ccall unsafe "lockFile"
1029 lockFile :: CInt -> CInt -> CInt -> IO CInt
1030
1031 foreign import ccall unsafe "unlockFile"
1032 unlockFile :: CInt -> IO CInt
1033 #endif
1034
1035 mkStdHandle :: FD -> FilePath -> HandleType -> IORef Buffer -> BufferMode
1036 -> IO Handle
1037 mkStdHandle fd filepath ha_type buf bmode = do
1038 spares <- newIORef BufferListNil
1039 newFileHandle filepath (stdHandleFinalizer filepath)
1040 (Handle__ { haFD = fd,
1041 haType = ha_type,
1042 haIsBin = dEFAULT_OPEN_IN_BINARY_MODE,
1043 haIsStream = False, -- means FD is blocking on Unix
1044 haBufferMode = bmode,
1045 haBuffer = buf,
1046 haBuffers = spares,
1047 haOtherSide = Nothing
1048 })
1049
1050 mkFileHandle :: FD -> Bool -> FilePath -> HandleType -> Bool -> IO Handle
1051 mkFileHandle fd is_stream filepath ha_type binary = do
1052 (buf, bmode) <- getBuffer fd (initBufferState ha_type)
1053
1054 #ifdef mingw32_HOST_OS
1055 -- On Windows, if this is a read/write handle and we are in text mode,
1056 -- turn off buffering. We don't correctly handle the case of switching
1057 -- from read mode to write mode on a buffered text-mode handle, see bug
1058 -- \#679.
1059 bmode <- case ha_type of
1060 ReadWriteHandle | not binary -> return NoBuffering
1061 _other -> return bmode
1062 #endif
1063
1064 spares <- newIORef BufferListNil
1065 newFileHandle filepath (handleFinalizer filepath)
1066 (Handle__ { haFD = fd,
1067 haType = ha_type,
1068 haIsBin = binary,
1069 haIsStream = is_stream,
1070 haBufferMode = bmode,
1071 haBuffer = buf,
1072 haBuffers = spares,
1073 haOtherSide = Nothing
1074 })
1075
1076 mkDuplexHandle :: FD -> Bool -> FilePath -> Bool -> IO Handle
1077 mkDuplexHandle fd is_stream filepath binary = do
1078 (w_buf, w_bmode) <- getBuffer fd WriteBuffer
1079 w_spares <- newIORef BufferListNil
1080 let w_handle_ =
1081 Handle__ { haFD = fd,
1082 haType = WriteHandle,
1083 haIsBin = binary,
1084 haIsStream = is_stream,
1085 haBufferMode = w_bmode,
1086 haBuffer = w_buf,
1087 haBuffers = w_spares,
1088 haOtherSide = Nothing
1089 }
1090 write_side <- newMVar w_handle_
1091
1092 (r_buf, r_bmode) <- getBuffer fd ReadBuffer
1093 r_spares <- newIORef BufferListNil
1094 let r_handle_ =
1095 Handle__ { haFD = fd,
1096 haType = ReadHandle,
1097 haIsBin = binary,
1098 haIsStream = is_stream,
1099 haBufferMode = r_bmode,
1100 haBuffer = r_buf,
1101 haBuffers = r_spares,
1102 haOtherSide = Just write_side
1103 }
1104 read_side <- newMVar r_handle_
1105
1106 addMVarFinalizer write_side (handleFinalizer filepath write_side)
1107 return (DuplexHandle filepath read_side write_side)
1108
1109
1110 initBufferState ReadHandle = ReadBuffer
1111 initBufferState _ = WriteBuffer
1112
1113 -- ---------------------------------------------------------------------------
1114 -- Closing a handle
1115
1116 -- | Computation 'hClose' @hdl@ makes handle @hdl@ closed. Before the
1117 -- computation finishes, if @hdl@ is writable its buffer is flushed as
1118 -- for 'hFlush'.
1119 -- Performing 'hClose' on a handle that has already been closed has no effect;
1120 -- doing so not an error. All other operations on a closed handle will fail.
1121 -- If 'hClose' fails for any reason, any further operations (apart from
1122 -- 'hClose') on the handle will still fail as if @hdl@ had been successfully
1123 -- closed.
1124
1125 hClose :: Handle -> IO ()
1126 hClose h@(FileHandle _ m) = hClose' h m
1127 hClose h@(DuplexHandle _ r w) = hClose' h w >> hClose' h r
1128
1129 hClose' h m = withHandle__' "hClose" h m $ hClose_help
1130
1131 -- hClose_help is also called by lazyRead (in PrelIO) when EOF is read
1132 -- or an IO error occurs on a lazy stream. The semi-closed Handle is
1133 -- then closed immediately. We have to be careful with DuplexHandles
1134 -- though: we have to leave the closing to the finalizer in that case,
1135 -- because the write side may still be in use.
1136 hClose_help :: Handle__ -> IO Handle__
1137 hClose_help handle_ =
1138 case haType handle_ of
1139 ClosedHandle -> return handle_
1140 _ -> do flushWriteBufferOnly handle_ -- interruptible
1141 hClose_handle_ handle_
1142
1143 hClose_handle_ handle_ = do
1144 let fd = haFD handle_
1145
1146 -- close the file descriptor, but not when this is the read
1147 -- side of a duplex handle.
1148 case haOtherSide handle_ of
1149 Nothing ->
1150 throwErrnoIfMinus1Retry_ "hClose"
1151 #ifdef mingw32_HOST_OS
1152 (closeFd (haIsStream handle_) fd)
1153 #else
1154 (c_close fd)
1155 #endif
1156 Just _ -> return ()
1157
1158 -- free the spare buffers
1159 writeIORef (haBuffers handle_) BufferListNil
1160
1161 #ifndef mingw32_HOST_OS
1162 -- unlock it
1163 unlockFile fd
1164 #endif
1165
1166 -- we must set the fd to -1, because the finalizer is going
1167 -- to run eventually and try to close/unlock it.
1168 return (handle_{ haFD = -1,
1169 haType = ClosedHandle
1170 })
1171
1172 -----------------------------------------------------------------------------
1173 -- Detecting and changing the size of a file
1174
1175 -- | For a handle @hdl@ which attached to a physical file,
1176 -- 'hFileSize' @hdl@ returns the size of that file in 8-bit bytes.
1177
1178 hFileSize :: Handle -> IO Integer
1179 hFileSize handle =
1180 withHandle_ "hFileSize" handle $ \ handle_ -> do
1181 case haType handle_ of
1182 ClosedHandle -> ioe_closedHandle
1183 SemiClosedHandle -> ioe_closedHandle
1184 _ -> do flushWriteBufferOnly handle_
1185 r <- fdFileSize (haFD handle_)
1186 if r /= -1
1187 then return r
1188 else ioException (IOError Nothing InappropriateType "hFileSize"
1189 "not a regular file" Nothing)
1190
1191
1192 -- | 'hSetFileSize' @hdl@ @size@ truncates the physical file with handle @hdl@ to @size@ bytes.
1193
1194 hSetFileSize :: Handle -> Integer -> IO ()
1195 hSetFileSize handle size =
1196 withHandle_ "hSetFileSize" handle $ \ handle_ -> do
1197 case haType handle_ of
1198 ClosedHandle -> ioe_closedHandle
1199 SemiClosedHandle -> ioe_closedHandle
1200 _ -> do flushWriteBufferOnly handle_
1201 throwErrnoIf (/=0) "hSetFileSize"
1202 (c_ftruncate (haFD handle_) (fromIntegral size))
1203 return ()
1204
1205 -- ---------------------------------------------------------------------------
1206 -- Detecting the End of Input
1207
1208 -- | For a readable handle @hdl@, 'hIsEOF' @hdl@ returns
1209 -- 'True' if no further input can be taken from @hdl@ or for a
1210 -- physical file, if the current I\/O position is equal to the length of
1211 -- the file. Otherwise, it returns 'False'.
1212
1213 hIsEOF :: Handle -> IO Bool
1214 hIsEOF handle =
1215 catch
1216 (do hLookAhead handle; return False)
1217 (\e -> if isEOFError e then return True else ioError e)
1218
1219 -- | The computation 'isEOF' is identical to 'hIsEOF',
1220 -- except that it works only on 'stdin'.
1221
1222 isEOF :: IO Bool
1223 isEOF = hIsEOF stdin
1224
1225 -- ---------------------------------------------------------------------------
1226 -- Looking ahead
1227
1228 -- | Computation 'hLookAhead' returns the next character from the handle
1229 -- without removing it from the input buffer, blocking until a character
1230 -- is available.
1231 --
1232 -- This operation may fail with:
1233 --
1234 -- * 'isEOFError' if the end of file has been reached.
1235
1236 hLookAhead :: Handle -> IO Char
1237 hLookAhead handle = do
1238 wantReadableHandle "hLookAhead" handle $ \handle_ -> do
1239 let ref = haBuffer handle_
1240 fd = haFD handle_
1241 is_line = haBufferMode handle_ == LineBuffering
1242 buf <- readIORef ref
1243
1244 -- fill up the read buffer if necessary
1245 new_buf <- if bufferEmpty buf
1246 then fillReadBuffer fd True (haIsStream handle_) buf
1247 else return buf
1248
1249 writeIORef ref new_buf
1250
1251 (c,_) <- readCharFromBuffer (bufBuf buf) (bufRPtr buf)
1252 return c
1253
1254 -- ---------------------------------------------------------------------------
1255 -- Buffering Operations
1256
1257 -- Three kinds of buffering are supported: line-buffering,
1258 -- block-buffering or no-buffering. See GHC.IOBase for definition and
1259 -- further explanation of what the type represent.
1260
1261 -- | Computation 'hSetBuffering' @hdl mode@ sets the mode of buffering for
1262 -- handle @hdl@ on subsequent reads and writes.
1263 --
1264 -- If the buffer mode is changed from 'BlockBuffering' or
1265 -- 'LineBuffering' to 'NoBuffering', then
1266 --
1267 -- * if @hdl@ is writable, the buffer is flushed as for 'hFlush';
1268 --
1269 -- * if @hdl@ is not writable, the contents of the buffer is discarded.
1270 --
1271 -- This operation may fail with:
1272 --
1273 -- * 'isPermissionError' if the handle has already been used for reading
1274 -- or writing and the implementation does not allow the buffering mode
1275 -- to be changed.
1276
1277 hSetBuffering :: Handle -> BufferMode -> IO ()
1278 hSetBuffering handle mode =
1279 withAllHandles__ "hSetBuffering" handle $ \ handle_ -> do
1280 case haType handle_ of
1281 ClosedHandle -> ioe_closedHandle
1282 _ -> do
1283 {- Note:
1284 - we flush the old buffer regardless of whether
1285 the new buffer could fit the contents of the old buffer
1286 or not.
1287 - allow a handle's buffering to change even if IO has
1288 occurred (ANSI C spec. does not allow this, nor did
1289 the previous implementation of IO.hSetBuffering).
1290 - a non-standard extension is to allow the buffering
1291 of semi-closed handles to change [sof 6/98]
1292 -}
1293 flushBuffer handle_
1294
1295 let state = initBufferState (haType handle_)
1296 new_buf <-
1297 case mode of
1298 -- we always have a 1-character read buffer for
1299 -- unbuffered handles: it's needed to
1300 -- support hLookAhead.
1301 NoBuffering -> allocateBuffer 1 ReadBuffer
1302 LineBuffering -> allocateBuffer dEFAULT_BUFFER_SIZE state
1303 BlockBuffering Nothing -> allocateBuffer dEFAULT_BUFFER_SIZE state
1304 BlockBuffering (Just n) | n <= 0 -> ioe_bufsiz n
1305 | otherwise -> allocateBuffer n state
1306 writeIORef (haBuffer handle_) new_buf
1307
1308 -- for input terminals we need to put the terminal into
1309 -- cooked or raw mode depending on the type of buffering.
1310 is_tty <- fdIsTTY (haFD handle_)
1311 when (is_tty && isReadableHandleType (haType handle_)) $
1312 case mode of
1313 #ifndef mingw32_HOST_OS
1314 -- 'raw' mode under win32 is a bit too specialised (and troublesome
1315 -- for most common uses), so simply disable its use here.
1316 NoBuffering -> setCooked (haFD handle_) False
1317 #else
1318 NoBuffering -> return ()
1319 #endif
1320 _ -> setCooked (haFD handle_) True
1321
1322 -- throw away spare buffers, they might be the wrong size
1323 writeIORef (haBuffers handle_) BufferListNil
1324
1325 return (handle_{ haBufferMode = mode })
1326
1327 -- -----------------------------------------------------------------------------
1328 -- hFlush
1329
1330 -- | The action 'hFlush' @hdl@ causes any items buffered for output
1331 -- in handle @hdl@ to be sent immediately to the operating system.
1332 --
1333 -- This operation may fail with:
1334 --
1335 -- * 'isFullError' if the device is full;
1336 --
1337 -- * 'isPermissionError' if a system resource limit would be exceeded.
1338 -- It is unspecified whether the characters in the buffer are discarded
1339 -- or retained under these circumstances.
1340
1341 hFlush :: Handle -> IO ()
1342 hFlush handle =
1343 wantWritableHandle "hFlush" handle $ \ handle_ -> do
1344 buf <- readIORef (haBuffer handle_)
1345 if bufferIsWritable buf && not (bufferEmpty buf)
1346 then do flushed_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
1347 writeIORef (haBuffer handle_) flushed_buf
1348 else return ()
1349
1350
1351 -- -----------------------------------------------------------------------------
1352 -- Repositioning Handles
1353
1354 data HandlePosn = HandlePosn Handle HandlePosition
1355
1356 instance Eq HandlePosn where
1357 (HandlePosn h1 p1) == (HandlePosn h2 p2) = p1==p2 && h1==h2
1358
1359 instance Show HandlePosn where
1360 showsPrec p (HandlePosn h pos) =
1361 showsPrec p h . showString " at position " . shows pos
1362
1363 -- HandlePosition is the Haskell equivalent of POSIX' off_t.
1364 -- We represent it as an Integer on the Haskell side, but
1365 -- cheat slightly in that hGetPosn calls upon a C helper
1366 -- that reports the position back via (merely) an Int.
1367 type HandlePosition = Integer
1368
1369 -- | Computation 'hGetPosn' @hdl@ returns the current I\/O position of
1370 -- @hdl@ as a value of the abstract type 'HandlePosn'.
1371
1372 hGetPosn :: Handle -> IO HandlePosn
1373 hGetPosn handle = do
1374 posn <- hTell handle
1375 return (HandlePosn handle posn)
1376
1377 -- | If a call to 'hGetPosn' @hdl@ returns a position @p@,
1378 -- then computation 'hSetPosn' @p@ sets the position of @hdl@
1379 -- to the position it held at the time of the call to 'hGetPosn'.
1380 --
1381 -- This operation may fail with:
1382 --
1383 -- * 'isPermissionError' if a system resource limit would be exceeded.
1384
1385 hSetPosn :: HandlePosn -> IO ()
1386 hSetPosn (HandlePosn h i) = hSeek h AbsoluteSeek i
1387
1388 -- ---------------------------------------------------------------------------
1389 -- hSeek
1390
1391 -- | A mode that determines the effect of 'hSeek' @hdl mode i@, as follows:
1392 data SeekMode
1393 = AbsoluteSeek -- ^ the position of @hdl@ is set to @i@.
1394 | RelativeSeek -- ^ the position of @hdl@ is set to offset @i@
1395 -- from the current position.
1396 | SeekFromEnd -- ^ the position of @hdl@ is set to offset @i@
1397 -- from the end of the file.
1398 deriving (Eq, Ord, Ix, Enum, Read, Show)
1399
1400 {- Note:
1401 - when seeking using `SeekFromEnd', positive offsets (>=0) means
1402 seeking at or past EOF.
1403
1404 - we possibly deviate from the report on the issue of seeking within
1405 the buffer and whether to flush it or not. The report isn't exactly
1406 clear here.
1407 -}
1408
1409 -- | Computation 'hSeek' @hdl mode i@ sets the position of handle
1410 -- @hdl@ depending on @mode@.
1411 -- The offset @i@ is given in terms of 8-bit bytes.
1412 --
1413 -- If @hdl@ is block- or line-buffered, then seeking to a position which is not
1414 -- in the current buffer will first cause any items in the output buffer to be
1415 -- written to the device, and then cause the input buffer to be discarded.
1416 -- Some handles may not be seekable (see 'hIsSeekable'), or only support a
1417 -- subset of the possible positioning operations (for instance, it may only
1418 -- be possible to seek to the end of a tape, or to a positive offset from
1419 -- the beginning or current position).
1420 -- It is not possible to set a negative I\/O position, or for
1421 -- a physical file, an I\/O position beyond the current end-of-file.
1422 --
1423 -- This operation may fail with:
1424 --
1425 -- * 'isPermissionError' if a system resource limit would be exceeded.
1426
1427 hSeek :: Handle -> SeekMode -> Integer -> IO ()
1428 hSeek handle mode offset =
1429 wantSeekableHandle "hSeek" handle $ \ handle_ -> do
1430 # ifdef DEBUG_DUMP
1431 puts ("hSeek " ++ show (mode,offset) ++ "\n")
1432 # endif
1433 let ref = haBuffer handle_
1434 buf <- readIORef ref
1435 let r = bufRPtr buf
1436 w = bufWPtr buf
1437 fd = haFD handle_
1438
1439 let do_seek =
1440 throwErrnoIfMinus1Retry_ "hSeek"
1441 (c_lseek (haFD handle_) (fromIntegral offset) whence)
1442
1443 whence :: CInt
1444 whence = case mode of
1445 AbsoluteSeek -> sEEK_SET
1446 RelativeSeek -> sEEK_CUR
1447 SeekFromEnd -> sEEK_END
1448
1449 if bufferIsWritable buf
1450 then do new_buf <- flushWriteBuffer fd (haIsStream handle_) buf
1451 writeIORef ref new_buf
1452 do_seek
1453 else do
1454
1455 if mode == RelativeSeek && offset >= 0 && offset < fromIntegral (w - r)
1456 then writeIORef ref buf{ bufRPtr = r + fromIntegral offset }
1457 else do
1458
1459 new_buf <- flushReadBuffer (haFD handle_) buf
1460 writeIORef ref new_buf
1461 do_seek
1462
1463
1464 hTell :: Handle -> IO Integer
1465 hTell handle =
1466 wantSeekableHandle "hGetPosn" handle $ \ handle_ -> do
1467
1468 #if defined(mingw32_HOST_OS)
1469 -- urgh, on Windows we have to worry about \n -> \r\n translation,
1470 -- so we can't easily calculate the file position using the
1471 -- current buffer size. Just flush instead.
1472 flushBuffer handle_
1473 #endif
1474 let fd = haFD handle_
1475 posn <- fromIntegral `liftM`
1476 throwErrnoIfMinus1Retry "hGetPosn"
1477 (c_lseek fd 0 sEEK_CUR)
1478
1479 let ref = haBuffer handle_
1480 buf <- readIORef ref
1481
1482 let real_posn
1483 | bufferIsWritable buf = posn + fromIntegral (bufWPtr buf)
1484 | otherwise = posn - fromIntegral (bufWPtr buf - bufRPtr buf)
1485 # ifdef DEBUG_DUMP
1486 puts ("\nhGetPosn: (fd, posn, real_posn) = " ++ show (fd, posn, real_posn) ++ "\n")
1487 puts (" (bufWPtr, bufRPtr) = " ++ show (bufWPtr buf, bufRPtr buf) ++ "\n")
1488 # endif
1489 return real_posn
1490
1491 -- -----------------------------------------------------------------------------
1492 -- Handle Properties
1493
1494 -- A number of operations return information about the properties of a
1495 -- handle. Each of these operations returns `True' if the handle has
1496 -- the specified property, and `False' otherwise.
1497
1498 hIsOpen :: Handle -> IO Bool
1499 hIsOpen handle =
1500 withHandle_ "hIsOpen" handle $ \ handle_ -> do
1501 case haType handle_ of
1502 ClosedHandle -> return False
1503 SemiClosedHandle -> return False
1504 _ -> return True
1505
1506 hIsClosed :: Handle -> IO Bool
1507 hIsClosed handle =
1508 withHandle_ "hIsClosed" handle $ \ handle_ -> do
1509 case haType handle_ of
1510 ClosedHandle -> return True
1511 _ -> return False
1512
1513 {- not defined, nor exported, but mentioned
1514 here for documentation purposes:
1515
1516 hSemiClosed :: Handle -> IO Bool
1517 hSemiClosed h = do
1518 ho <- hIsOpen h
1519 hc <- hIsClosed h
1520 return (not (ho || hc))
1521 -}
1522
1523 hIsReadable :: Handle -> IO Bool
1524 hIsReadable (DuplexHandle _ _ _) = return True
1525 hIsReadable handle =
1526 withHandle_ "hIsReadable" handle $ \ handle_ -> do
1527 case haType handle_ of
1528 ClosedHandle -> ioe_closedHandle
1529 SemiClosedHandle -> ioe_closedHandle
1530 htype -> return (isReadableHandleType htype)
1531
1532 hIsWritable :: Handle -> IO Bool
1533 hIsWritable (DuplexHandle _ _ _) = return True
1534 hIsWritable handle =
1535 withHandle_ "hIsWritable" handle $ \ handle_ -> do
1536 case haType handle_ of
1537 ClosedHandle -> ioe_closedHandle
1538 SemiClosedHandle -> ioe_closedHandle
1539 htype -> return (isWritableHandleType htype)
1540
1541 -- | Computation 'hGetBuffering' @hdl@ returns the current buffering mode
1542 -- for @hdl@.
1543
1544 hGetBuffering :: Handle -> IO BufferMode
1545 hGetBuffering handle =
1546 withHandle_ "hGetBuffering" handle $ \ handle_ -> do
1547 case haType handle_ of
1548 ClosedHandle -> ioe_closedHandle
1549 _ ->
1550 -- We're being non-standard here, and allow the buffering
1551 -- of a semi-closed handle to be queried. -- sof 6/98
1552 return (haBufferMode handle_) -- could be stricter..
1553
1554 hIsSeekable :: Handle -> IO Bool
1555 hIsSeekable handle =
1556 withHandle_ "hIsSeekable" handle $ \ handle_ -> do
1557 case haType handle_ of
1558 ClosedHandle -> ioe_closedHandle
1559 SemiClosedHandle -> ioe_closedHandle
1560 AppendHandle -> return False
1561 _ -> do t <- fdType (haFD handle_)
1562 return ((t == RegularFile || t == RawDevice)
1563 && (haIsBin handle_ || tEXT_MODE_SEEK_ALLOWED))
1564
1565 -- -----------------------------------------------------------------------------
1566 -- Changing echo status (Non-standard GHC extensions)
1567
1568 -- | Set the echoing status of a handle connected to a terminal.
1569
1570 hSetEcho :: Handle -> Bool -> IO ()
1571 hSetEcho handle on = do
1572 isT <- hIsTerminalDevice handle
1573 if not isT
1574 then return ()
1575 else
1576 withHandle_ "hSetEcho" handle $ \ handle_ -> do
1577 case haType handle_ of
1578 ClosedHandle -> ioe_closedHandle
1579 _ -> setEcho (haFD handle_) on
1580
1581 -- | Get the echoing status of a handle connected to a terminal.
1582
1583 hGetEcho :: Handle -> IO Bool
1584 hGetEcho handle = do
1585 isT <- hIsTerminalDevice handle
1586 if not isT
1587 then return False
1588 else
1589 withHandle_ "hGetEcho" handle $ \ handle_ -> do
1590 case haType handle_ of
1591 ClosedHandle -> ioe_closedHandle
1592 _ -> getEcho (haFD handle_)
1593
1594 -- | Is the handle connected to a terminal?
1595
1596 hIsTerminalDevice :: Handle -> IO Bool
1597 hIsTerminalDevice handle = do
1598 withHandle_ "hIsTerminalDevice" handle $ \ handle_ -> do
1599 case haType handle_ of
1600 ClosedHandle -> ioe_closedHandle
1601 _ -> fdIsTTY (haFD handle_)
1602
1603 -- -----------------------------------------------------------------------------
1604 -- hSetBinaryMode
1605
1606 -- | Select binary mode ('True') or text mode ('False') on a open handle.
1607 -- (See also 'openBinaryFile'.)
1608
1609 hSetBinaryMode :: Handle -> Bool -> IO ()
1610 hSetBinaryMode handle bin =
1611 withAllHandles__ "hSetBinaryMode" handle $ \ handle_ ->
1612 do throwErrnoIfMinus1_ "hSetBinaryMode"
1613 (setmode (haFD handle_) bin)
1614 return handle_{haIsBin=bin}
1615
1616 foreign import ccall unsafe "__hscore_setmode"
1617 setmode :: CInt -> Bool -> IO CInt
1618
1619 -- -----------------------------------------------------------------------------
1620 -- Duplicating a Handle
1621
1622 -- | Returns a duplicate of the original handle, with its own buffer.
1623 -- The two Handles will share a file pointer, however. The original
1624 -- handle's buffer is flushed, including discarding any input data,
1625 -- before the handle is duplicated.
1626
1627 hDuplicate :: Handle -> IO Handle
1628 hDuplicate h@(FileHandle path m) = do
1629 new_h_ <- withHandle' "hDuplicate" h m (dupHandle h Nothing)
1630 newFileHandle path (handleFinalizer path) new_h_
1631 hDuplicate h@(DuplexHandle path r w) = do
1632 new_w_ <- withHandle' "hDuplicate" h w (dupHandle h Nothing)
1633 new_w <- newMVar new_w_
1634 new_r_ <- withHandle' "hDuplicate" h r (dupHandle h (Just new_w))
1635 new_r <- newMVar new_r_
1636 addMVarFinalizer new_w (handleFinalizer path new_w)
1637 return (DuplexHandle path new_r new_w)
1638
1639 dupHandle :: Handle -> Maybe (MVar Handle__) -> Handle__
1640 -> IO (Handle__, Handle__)
1641 dupHandle h other_side h_ = do
1642 -- flush the buffer first, so we don't have to copy its contents
1643 flushBuffer h_
1644 new_fd <- case other_side of
1645 Nothing -> throwErrnoIfMinus1 "dupHandle" $ c_dup (haFD h_)
1646 Just r -> withHandle_' "dupHandle" h r (return . haFD)
1647 dupHandle_ other_side h_ new_fd
1648
1649 dupHandleTo other_side hto_ h_ = do
1650 flushBuffer h_
1651 -- Windows' dup2 does not return the new descriptor, unlike Unix
1652 throwErrnoIfMinus1 "dupHandleTo" $
1653 c_dup2 (haFD h_) (haFD hto_)
1654 dupHandle_ other_side h_ (haFD hto_)
1655
1656 dupHandle_ :: Maybe (MVar Handle__) -> Handle__ -> FD
1657 -> IO (Handle__, Handle__)
1658 dupHandle_ other_side h_ new_fd = do
1659 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE (initBufferState (haType h_))
1660 ioref <- newIORef buffer
1661 ioref_buffers <- newIORef BufferListNil
1662
1663 let new_handle_ = h_{ haFD = new_fd,
1664 haBuffer = ioref,
1665 haBuffers = ioref_buffers,
1666 haOtherSide = other_side }
1667 return (h_, new_handle_)
1668
1669 -- -----------------------------------------------------------------------------
1670 -- Replacing a Handle
1671
1672 {- |
1673 Makes the second handle a duplicate of the first handle. The second
1674 handle will be closed first, if it is not already.
1675
1676 This can be used to retarget the standard Handles, for example:
1677
1678 > do h <- openFile "mystdout" WriteMode
1679 > hDuplicateTo h stdout
1680 -}
1681
1682 hDuplicateTo :: Handle -> Handle -> IO ()
1683 hDuplicateTo h1@(FileHandle _ m1) h2@(FileHandle _ m2) = do
1684 withHandle__' "hDuplicateTo" h2 m2 $ \h2_ -> do
1685 _ <- hClose_help h2_
1686 withHandle' "hDuplicateTo" h1 m1 (dupHandleTo Nothing h2_)
1687 hDuplicateTo h1@(DuplexHandle _ r1 w1) h2@(DuplexHandle _ r2 w2) = do
1688 withHandle__' "hDuplicateTo" h2 w2 $ \w2_ -> do
1689 _ <- hClose_help w2_
1690 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo Nothing w2_)
1691 withHandle__' "hDuplicateTo" h2 r2 $ \r2_ -> do
1692 _ <- hClose_help r2_
1693 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo (Just w1) r2_)
1694 hDuplicateTo h1 _ =
1695 ioException (IOError (Just h1) IllegalOperation "hDuplicateTo"
1696 "handles are incompatible" Nothing)
1697
1698 -- ---------------------------------------------------------------------------
1699 -- showing Handles.
1700 --
1701 -- | 'hShow' is in the 'IO' monad, and gives more comprehensive output
1702 -- than the (pure) instance of 'Show' for 'Handle'.
1703
1704 hShow :: Handle -> IO String
1705 hShow h@(FileHandle path _) = showHandle' path False h
1706 hShow h@(DuplexHandle path _ _) = showHandle' path True h
1707
1708 showHandle' filepath is_duplex h =
1709 withHandle_ "showHandle" h $ \hdl_ ->
1710 let
1711 showType | is_duplex = showString "duplex (read-write)"
1712 | otherwise = shows (haType hdl_)
1713 in
1714 return
1715 (( showChar '{' .
1716 showHdl (haType hdl_)
1717 (showString "loc=" . showString filepath . showChar ',' .
1718 showString "type=" . showType . showChar ',' .
1719 showString "binary=" . shows (haIsBin hdl_) . showChar ',' .
1720 showString "buffering=" . showBufMode (unsafePerformIO (readIORef (haBuffer hdl_))) (haBufferMode hdl_) . showString "}" )
1721 ) "")
1722 where
1723
1724 showHdl :: HandleType -> ShowS -> ShowS
1725 showHdl ht cont =
1726 case ht of
1727 ClosedHandle -> shows ht . showString "}"
1728 _ -> cont
1729
1730 showBufMode :: Buffer -> BufferMode -> ShowS
1731 showBufMode buf bmo =
1732 case bmo of
1733 NoBuffering -> showString "none"
1734 LineBuffering -> showString "line"
1735 BlockBuffering (Just n) -> showString "block " . showParen True (shows n)
1736 BlockBuffering Nothing -> showString "block " . showParen True (shows def)
1737 where
1738 def :: Int
1739 def = bufSize buf
1740
1741 -- ---------------------------------------------------------------------------
1742 -- debugging
1743
1744 #if defined(DEBUG_DUMP)
1745 puts :: String -> IO ()
1746 puts s = do write_rawBuffer 1 (unsafeCoerce# (packCString# s)) 0 (fromIntegral (length s))
1747 return ()
1748 #endif
1749
1750 -- -----------------------------------------------------------------------------
1751 -- utils
1752
1753 throwErrnoIfMinus1RetryOnBlock :: String -> IO CInt -> IO CInt -> IO CInt
1754 throwErrnoIfMinus1RetryOnBlock loc f on_block =
1755 do
1756 res <- f
1757 if (res :: CInt) == -1
1758 then do
1759 err <- getErrno
1760 if err == eINTR
1761 then throwErrnoIfMinus1RetryOnBlock loc f on_block
1762 else if err == eWOULDBLOCK || err == eAGAIN
1763 then do on_block
1764 else throwErrno loc
1765 else return res
1766
1767 -- -----------------------------------------------------------------------------
1768 -- wrappers to platform-specific constants:
1769
1770 foreign import ccall unsafe "__hscore_supportsTextMode"
1771 tEXT_MODE_SEEK_ALLOWED :: Bool
1772
1773 foreign import ccall unsafe "__hscore_bufsiz" dEFAULT_BUFFER_SIZE :: Int
1774 foreign import ccall unsafe "__hscore_seek_cur" sEEK_CUR :: CInt
1775 foreign import ccall unsafe "__hscore_seek_set" sEEK_SET :: CInt
1776 foreign import ccall unsafe "__hscore_seek_end" sEEK_END :: CInt