c962edce3d1feab4f552fdbc06e435e6156479ce
[packages/base.git] / GHC / Handle.hs
1 {-# OPTIONS_GHC -XNoImplicitPrelude -#include "HsBase.h" #-}
2 {-# OPTIONS_GHC -fno-warn-unused-matches #-}
3 {-# OPTIONS_GHC -fno-warn-unused-binds #-}
4 {-# OPTIONS_HADDOCK hide #-}
5
6 #undef DEBUG_DUMP
7 #undef DEBUG
8
9 -----------------------------------------------------------------------------
10 -- |
11 -- Module : GHC.Handle
12 -- Copyright : (c) The University of Glasgow, 1994-2001
13 -- License : see libraries/base/LICENSE
14 --
15 -- Maintainer : libraries@haskell.org
16 -- Stability : internal
17 -- Portability : non-portable
18 --
19 -- This module defines the basic operations on I\/O \"handles\".
20 --
21 -----------------------------------------------------------------------------
22
23 -- #hide
24 module GHC.Handle (
25 withHandle, withHandle', withHandle_,
26 wantWritableHandle, wantReadableHandle, wantSeekableHandle,
27
28 newEmptyBuffer, allocateBuffer, readCharFromBuffer, writeCharIntoBuffer,
29 flushWriteBufferOnly, flushWriteBuffer, flushReadBuffer,
30 fillReadBuffer, fillReadBufferWithoutBlocking,
31 readRawBuffer, readRawBufferPtr,
32 readRawBufferNoBlock, readRawBufferPtrNoBlock,
33 writeRawBuffer, writeRawBufferPtr,
34
35 #ifndef mingw32_HOST_OS
36 unlockFile,
37 #endif
38
39 ioe_closedHandle, ioe_EOF, ioe_notReadable, ioe_notWritable,
40
41 stdin, stdout, stderr,
42 IOMode(..), openFile, openBinaryFile, fdToHandle_stat, fdToHandle, fdToHandle',
43 hFileSize, hSetFileSize, hIsEOF, isEOF, hLookAhead, hLookAhead', hSetBuffering, hSetBinaryMode,
44 hFlush, hDuplicate, hDuplicateTo,
45
46 hClose, hClose_help,
47
48 HandlePosition, HandlePosn(..), hGetPosn, hSetPosn,
49 SeekMode(..), hSeek, hTell,
50
51 hIsOpen, hIsClosed, hIsReadable, hIsWritable, hGetBuffering, hIsSeekable,
52 hSetEcho, hGetEcho, hIsTerminalDevice,
53
54 hShow,
55
56 #ifdef DEBUG_DUMP
57 puts,
58 #endif
59
60 ) where
61
62 import Control.Monad
63 import Data.Maybe
64 import Foreign
65 import Foreign.C
66 import System.IO.Error
67 import System.Posix.Internals
68 import System.Posix.Types
69
70 import GHC.Real
71
72 import GHC.Arr
73 import GHC.Base
74 import GHC.Read ( Read )
75 import GHC.List
76 import GHC.IOBase
77 import GHC.Exception
78 import GHC.Enum
79 import GHC.Num ( Integer, Num(..) )
80 import GHC.Show
81 #if defined(DEBUG_DUMP)
82 import GHC.Pack
83 #endif
84
85 import GHC.Conc
86
87 -- -----------------------------------------------------------------------------
88 -- TODO:
89
90 -- hWaitForInput blocks (should use a timeout)
91
92 -- unbuffered hGetLine is a bit dodgy
93
94 -- hSetBuffering: can't change buffering on a stream,
95 -- when the read buffer is non-empty? (no way to flush the buffer)
96
97 -- ---------------------------------------------------------------------------
98 -- Are files opened by default in text or binary mode, if the user doesn't
99 -- specify?
100
101 dEFAULT_OPEN_IN_BINARY_MODE :: Bool
102 dEFAULT_OPEN_IN_BINARY_MODE = False
103
104 -- ---------------------------------------------------------------------------
105 -- Creating a new handle
106
107 newFileHandle :: FilePath -> (MVar Handle__ -> IO ()) -> Handle__ -> IO Handle
108 newFileHandle filepath finalizer hc = do
109 m <- newMVar hc
110 addMVarFinalizer m (finalizer m)
111 return (FileHandle filepath m)
112
113 -- ---------------------------------------------------------------------------
114 -- Working with Handles
115
116 {-
117 In the concurrent world, handles are locked during use. This is done
118 by wrapping an MVar around the handle which acts as a mutex over
119 operations on the handle.
120
121 To avoid races, we use the following bracketing operations. The idea
122 is to obtain the lock, do some operation and replace the lock again,
123 whether the operation succeeded or failed. We also want to handle the
124 case where the thread receives an exception while processing the IO
125 operation: in these cases we also want to relinquish the lock.
126
127 There are three versions of @withHandle@: corresponding to the three
128 possible combinations of:
129
130 - the operation may side-effect the handle
131 - the operation may return a result
132
133 If the operation generates an error or an exception is raised, the
134 original handle is always replaced [ this is the case at the moment,
135 but we might want to revisit this in the future --SDM ].
136 -}
137
138 {-# INLINE withHandle #-}
139 withHandle :: String -> Handle -> (Handle__ -> IO (Handle__,a)) -> IO a
140 withHandle fun h@(FileHandle _ m) act = withHandle' fun h m act
141 withHandle fun h@(DuplexHandle _ m _) act = withHandle' fun h m act
142
143 withHandle' :: String -> Handle -> MVar Handle__
144 -> (Handle__ -> IO (Handle__,a)) -> IO a
145 withHandle' fun h m act =
146 block $ do
147 h_ <- takeMVar m
148 checkBufferInvariants h_
149 (h',v) <- (act h_ `catchAny` \err -> putMVar m h_ >> throw err)
150 `catchException` \ex -> ioError (augmentIOError ex fun h)
151 checkBufferInvariants h'
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 <- (act h_ `catchAny` \err -> putMVar m h_ >> throw err)
166 `catchException` \ex -> ioError (augmentIOError ex fun h)
167 checkBufferInvariants h_
168 putMVar m h_
169 return v
170
171 withAllHandles__ :: String -> Handle -> (Handle__ -> IO Handle__) -> IO ()
172 withAllHandles__ fun h@(FileHandle _ m) act = withHandle__' fun h m act
173 withAllHandles__ fun h@(DuplexHandle _ r w) act = do
174 withHandle__' fun h r act
175 withHandle__' fun h w act
176
177 withHandle__' :: String -> Handle -> MVar Handle__ -> (Handle__ -> IO Handle__)
178 -> IO ()
179 withHandle__' fun h m act =
180 block $ do
181 h_ <- takeMVar m
182 checkBufferInvariants h_
183 h' <- (act h_ `catchAny` \err -> putMVar m h_ >> throw err)
184 `catchException` \ex -> ioError (augmentIOError ex fun h)
185 checkBufferInvariants h'
186 putMVar m h'
187 return ()
188
189 augmentIOError :: IOException -> String -> Handle -> IOException
190 augmentIOError ioe@IOError{ ioe_filename = fp } fun h
191 = ioe { ioe_handle = Just h, ioe_location = fun, ioe_filename = filepath }
192 where filepath
193 | Just _ <- fp = fp
194 | otherwise = case h of
195 FileHandle path _ -> Just path
196 DuplexHandle path _ _ -> Just path
197
198 -- ---------------------------------------------------------------------------
199 -- Wrapper for write operations.
200
201 wantWritableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
202 wantWritableHandle fun h@(FileHandle _ m) act
203 = wantWritableHandle' fun h m act
204 wantWritableHandle fun h@(DuplexHandle _ _ m) act
205 = wantWritableHandle' fun h m act
206 -- ToDo: in the Duplex case, we don't need to checkWritableHandle
207
208 wantWritableHandle'
209 :: String -> Handle -> MVar Handle__
210 -> (Handle__ -> IO a) -> IO a
211 wantWritableHandle' fun h m act
212 = withHandle_' fun h m (checkWritableHandle act)
213
214 checkWritableHandle :: (Handle__ -> IO a) -> Handle__ -> IO a
215 checkWritableHandle act handle_
216 = case haType handle_ of
217 ClosedHandle -> ioe_closedHandle
218 SemiClosedHandle -> ioe_closedHandle
219 ReadHandle -> ioe_notWritable
220 ReadWriteHandle -> do
221 let ref = haBuffer handle_
222 buf <- readIORef ref
223 new_buf <-
224 if not (bufferIsWritable buf)
225 then do b <- flushReadBuffer (haFD handle_) buf
226 return b{ bufState=WriteBuffer }
227 else return buf
228 writeIORef ref new_buf
229 act handle_
230 _other -> act handle_
231
232 -- ---------------------------------------------------------------------------
233 -- Wrapper for read operations.
234
235 wantReadableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
236 wantReadableHandle fun h@(FileHandle _ m) act
237 = wantReadableHandle' fun h m act
238 wantReadableHandle fun h@(DuplexHandle _ m _) act
239 = wantReadableHandle' fun h m act
240 -- ToDo: in the Duplex case, we don't need to checkReadableHandle
241
242 wantReadableHandle'
243 :: String -> Handle -> MVar Handle__
244 -> (Handle__ -> IO a) -> IO a
245 wantReadableHandle' fun h m act
246 = withHandle_' fun h m (checkReadableHandle act)
247
248 checkReadableHandle :: (Handle__ -> IO a) -> Handle__ -> IO a
249 checkReadableHandle act handle_ =
250 case haType handle_ of
251 ClosedHandle -> ioe_closedHandle
252 SemiClosedHandle -> ioe_closedHandle
253 AppendHandle -> ioe_notReadable
254 WriteHandle -> ioe_notReadable
255 ReadWriteHandle -> do
256 let ref = haBuffer handle_
257 buf <- readIORef ref
258 when (bufferIsWritable buf) $ do
259 new_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
260 writeIORef ref new_buf{ bufState=ReadBuffer }
261 act handle_
262 _other -> act handle_
263
264 -- ---------------------------------------------------------------------------
265 -- Wrapper for seek operations.
266
267 wantSeekableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
268 wantSeekableHandle fun h@(DuplexHandle _ _ _) _act =
269 ioException (IOError (Just h) IllegalOperation fun
270 "handle is not seekable" Nothing Nothing)
271 wantSeekableHandle fun h@(FileHandle _ m) act =
272 withHandle_' fun h m (checkSeekableHandle act)
273
274 checkSeekableHandle :: (Handle__ -> IO a) -> Handle__ -> IO a
275 checkSeekableHandle act handle_ =
276 case haType handle_ of
277 ClosedHandle -> ioe_closedHandle
278 SemiClosedHandle -> ioe_closedHandle
279 AppendHandle -> ioe_notSeekable
280 _ | haIsBin handle_ || tEXT_MODE_SEEK_ALLOWED -> act handle_
281 | otherwise -> ioe_notSeekable_notBin
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 Nothing)
293 ioe_EOF = ioException
294 (IOError Nothing EOF "" "" Nothing Nothing)
295 ioe_notReadable = ioException
296 (IOError Nothing IllegalOperation ""
297 "handle is not open for reading" Nothing Nothing)
298 ioe_notWritable = ioException
299 (IOError Nothing IllegalOperation ""
300 "handle is not open for writing" Nothing Nothing)
301 ioe_notSeekable = ioException
302 (IOError Nothing IllegalOperation ""
303 "handle is not seekable" Nothing 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 Nothing)
308
309 ioe_finalizedHandle :: FilePath -> Handle__
310 ioe_finalizedHandle fp = throw
311 (IOError Nothing IllegalOperation ""
312 "handle is finalized" Nothing (Just fp))
313
314 ioe_bufsiz :: Int -> IO a
315 ioe_bufsiz n = ioException
316 (IOError Nothing InvalidArgument "hSetBuffering"
317 ("illegal buffer size " ++ showsPrec 9 n []) Nothing Nothing)
318 -- 9 => should be parens'ified.
319
320 -- -----------------------------------------------------------------------------
321 -- Handle Finalizers
322
323 -- For a duplex handle, we arrange that the read side points to the write side
324 -- (and hence keeps it alive if the read side is alive). This is done by
325 -- having the haOtherSide field of the read side point to the read side.
326 -- The finalizer is then placed on the write side, and the handle only gets
327 -- finalized once, when both sides are no longer required.
328
329 -- NOTE about finalized handles: It's possible that a handle can be
330 -- finalized and then we try to use it later, for example if the
331 -- handle is referenced from another finalizer, or from a thread that
332 -- has become unreferenced and then resurrected (arguably in the
333 -- latter case we shouldn't finalize the Handle...). Anyway,
334 -- we try to emit a helpful message which is better than nothing.
335
336 stdHandleFinalizer :: FilePath -> MVar Handle__ -> IO ()
337 stdHandleFinalizer fp m = do
338 h_ <- takeMVar m
339 flushWriteBufferOnly h_
340 putMVar m (ioe_finalizedHandle fp)
341
342 handleFinalizer :: FilePath -> MVar Handle__ -> IO ()
343 handleFinalizer fp m = do
344 handle_ <- takeMVar m
345 case haType handle_ of
346 ClosedHandle -> return ()
347 _ -> do flushWriteBufferOnly handle_ `catchAny` \_ -> return ()
348 -- ignore errors and async exceptions, and close the
349 -- descriptor anyway...
350 hClose_handle_ handle_
351 return ()
352 putMVar m (ioe_finalizedHandle fp)
353
354 -- ---------------------------------------------------------------------------
355 -- Grimy buffer operations
356
357 checkBufferInvariants :: Handle__ -> IO ()
358 #ifdef DEBUG
359 checkBufferInvariants h_ = do
360 let ref = haBuffer h_
361 Buffer{ bufWPtr=w, bufRPtr=r, bufSize=size, bufState=state } <- readIORef ref
362 if not (
363 size > 0
364 && r <= w
365 && w <= size
366 && ( r /= w || (r == 0 && w == 0) )
367 && ( state /= WriteBuffer || r == 0 )
368 && ( state /= WriteBuffer || w < size ) -- write buffer is never full
369 )
370 then error "buffer invariant violation"
371 else return ()
372 #else
373 checkBufferInvariants _ = return ()
374 #endif
375
376 newEmptyBuffer :: RawBuffer -> BufferState -> Int -> Buffer
377 newEmptyBuffer b state size
378 = Buffer{ bufBuf=b, bufRPtr=0, bufWPtr=0, bufSize=size, bufState=state }
379
380 allocateBuffer :: Int -> BufferState -> IO Buffer
381 allocateBuffer sz@(I# size) state = IO $ \s ->
382 -- We sometimes need to pass the address of this buffer to
383 -- a "safe" foreign call, hence it must be immovable.
384 case newPinnedByteArray# size s of { (# s', b #) ->
385 (# s', newEmptyBuffer b state sz #) }
386
387 writeCharIntoBuffer :: RawBuffer -> Int -> Char -> IO Int
388 writeCharIntoBuffer slab (I# off) (C# c)
389 = IO $ \s -> case writeCharArray# slab off c s of
390 s' -> (# s', I# (off +# 1#) #)
391
392 readCharFromBuffer :: RawBuffer -> Int -> IO (Char, Int)
393 readCharFromBuffer slab (I# off)
394 = IO $ \s -> case readCharArray# slab off s of
395 (# s', c #) -> (# s', (C# c, I# (off +# 1#)) #)
396
397 getBuffer :: FD -> BufferState -> IO (IORef Buffer, BufferMode)
398 getBuffer fd state = do
399 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE state
400 ioref <- newIORef buffer
401 is_tty <- fdIsTTY fd
402
403 let buffer_mode
404 | is_tty = LineBuffering
405 | otherwise = BlockBuffering Nothing
406
407 return (ioref, buffer_mode)
408
409 mkUnBuffer :: IO (IORef Buffer)
410 mkUnBuffer = do
411 buffer <- allocateBuffer 1 ReadBuffer
412 newIORef buffer
413
414 -- flushWriteBufferOnly flushes the buffer iff it contains pending write data.
415 flushWriteBufferOnly :: Handle__ -> IO ()
416 flushWriteBufferOnly h_ = do
417 let fd = haFD h_
418 ref = haBuffer h_
419 buf <- readIORef ref
420 new_buf <- if bufferIsWritable buf
421 then flushWriteBuffer fd (haIsStream h_) buf
422 else return buf
423 writeIORef ref new_buf
424
425 -- flushBuffer syncs the file with the buffer, including moving the
426 -- file pointer backwards in the case of a read buffer.
427 flushBuffer :: Handle__ -> IO ()
428 flushBuffer h_ = do
429 let ref = haBuffer h_
430 buf <- readIORef ref
431
432 flushed_buf <-
433 case bufState buf of
434 ReadBuffer -> flushReadBuffer (haFD h_) buf
435 WriteBuffer -> flushWriteBuffer (haFD h_) (haIsStream h_) buf
436
437 writeIORef ref flushed_buf
438
439 -- When flushing a read buffer, we seek backwards by the number of
440 -- characters in the buffer. The file descriptor must therefore be
441 -- seekable: attempting to flush the read buffer on an unseekable
442 -- handle is not allowed.
443
444 flushReadBuffer :: FD -> Buffer -> IO Buffer
445 flushReadBuffer fd buf
446 | bufferEmpty buf = return buf
447 | otherwise = do
448 let off = negate (bufWPtr buf - bufRPtr buf)
449 # ifdef DEBUG_DUMP
450 puts ("flushReadBuffer: new file offset = " ++ show off ++ "\n")
451 # endif
452 throwErrnoIfMinus1Retry "flushReadBuffer"
453 (c_lseek fd (fromIntegral off) sEEK_CUR)
454 return buf{ bufWPtr=0, bufRPtr=0 }
455
456 flushWriteBuffer :: FD -> Bool -> Buffer -> IO Buffer
457 flushWriteBuffer fd is_stream buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w } =
458 seq fd $ do -- strictness hack
459 let bytes = w - r
460 #ifdef DEBUG_DUMP
461 puts ("flushWriteBuffer, fd=" ++ show fd ++ ", bytes=" ++ show bytes ++ "\n")
462 #endif
463 if bytes == 0
464 then return (buf{ bufRPtr=0, bufWPtr=0 })
465 else do
466 res <- writeRawBuffer "flushWriteBuffer" fd is_stream b
467 (fromIntegral r) (fromIntegral bytes)
468 let res' = fromIntegral res
469 if res' < bytes
470 then flushWriteBuffer fd is_stream (buf{ bufRPtr = r + res' })
471 else return buf{ bufRPtr=0, bufWPtr=0 }
472
473 fillReadBuffer :: FD -> Bool -> Bool -> Buffer -> IO Buffer
474 fillReadBuffer fd is_line is_stream
475 buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w, bufSize=size } =
476 -- buffer better be empty:
477 assert (r == 0 && w == 0) $ do
478 fillReadBufferLoop fd is_line is_stream buf b w size
479
480 -- For a line buffer, we just get the first chunk of data to arrive,
481 -- and don't wait for the whole buffer to be full (but we *do* wait
482 -- until some data arrives). This isn't really line buffering, but it
483 -- appears to be what GHC has done for a long time, and I suspect it
484 -- is more useful than line buffering in most cases.
485
486 fillReadBufferLoop :: FD -> Bool -> Bool -> Buffer -> RawBuffer -> Int -> Int
487 -> IO Buffer
488 fillReadBufferLoop fd is_line is_stream buf b w size = do
489 let bytes = size - w
490 if bytes == 0 -- buffer full?
491 then return buf{ bufRPtr=0, bufWPtr=w }
492 else do
493 #ifdef DEBUG_DUMP
494 puts ("fillReadBufferLoop: bytes = " ++ show bytes ++ "\n")
495 #endif
496 res <- readRawBuffer "fillReadBuffer" fd is_stream b
497 (fromIntegral w) (fromIntegral bytes)
498 let res' = fromIntegral res
499 #ifdef DEBUG_DUMP
500 puts ("fillReadBufferLoop: res' = " ++ show res' ++ "\n")
501 #endif
502 if res' == 0
503 then if w == 0
504 then ioe_EOF
505 else return buf{ bufRPtr=0, bufWPtr=w }
506 else if res' < bytes && not is_line
507 then fillReadBufferLoop fd is_line is_stream buf b (w+res') size
508 else return buf{ bufRPtr=0, bufWPtr=w+res' }
509
510
511 fillReadBufferWithoutBlocking :: FD -> Bool -> Buffer -> IO Buffer
512 fillReadBufferWithoutBlocking fd is_stream
513 buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w, bufSize=size } =
514 -- buffer better be empty:
515 assert (r == 0 && w == 0) $ do
516 #ifdef DEBUG_DUMP
517 puts ("fillReadBufferLoopNoBlock: bytes = " ++ show size ++ "\n")
518 #endif
519 res <- readRawBufferNoBlock "fillReadBuffer" fd is_stream b
520 0 (fromIntegral size)
521 let res' = fromIntegral res
522 #ifdef DEBUG_DUMP
523 puts ("fillReadBufferLoopNoBlock: res' = " ++ show res' ++ "\n")
524 #endif
525 return buf{ bufRPtr=0, bufWPtr=res' }
526
527 -- Low level routines for reading/writing to (raw)buffers:
528
529 #ifndef mingw32_HOST_OS
530
531 {-
532 NOTE [nonblock]:
533
534 Unix has broken semantics when it comes to non-blocking I/O: you can
535 set the O_NONBLOCK flag on an FD, but it applies to the all other FDs
536 attached to the same underlying file, pipe or TTY; there's no way to
537 have private non-blocking behaviour for an FD. See bug #724.
538
539 We fix this by only setting O_NONBLOCK on FDs that we create; FDs that
540 come from external sources or are exposed externally are left in
541 blocking mode. This solution has some problems though. We can't
542 completely simulate a non-blocking read without O_NONBLOCK: several
543 cases are wrong here. The cases that are wrong:
544
545 * reading/writing to a blocking FD in non-threaded mode.
546 In threaded mode, we just make a safe call to read().
547 In non-threaded mode we call select() before attempting to read,
548 but that leaves a small race window where the data can be read
549 from the file descriptor before we issue our blocking read().
550 * readRawBufferNoBlock for a blocking FD
551
552 NOTE [2363]:
553
554 In the threaded RTS we could just make safe calls to read()/write()
555 for file descriptors in blocking mode without worrying about blocking
556 other threads, but the problem with this is that the thread will be
557 uninterruptible while it is blocked in the foreign call. See #2363.
558 So now we always call fdReady() before reading, and if fdReady
559 indicates that there's no data, we call threadWaitRead.
560
561 -}
562
563 readRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
564 readRawBuffer loc fd is_nonblock buf off len
565 | is_nonblock = unsafe_read -- unsafe is ok, it can't block
566 | otherwise = do r <- throwErrnoIfMinus1 loc
567 (unsafe_fdReady (fromIntegral fd) 0 0 0)
568 if r /= 0
569 then read
570 else do threadWaitRead (fromIntegral fd); read
571 where
572 do_read call = throwErrnoIfMinus1RetryMayBlock loc call
573 (threadWaitRead (fromIntegral fd))
574 read = if threaded then safe_read else unsafe_read
575 unsafe_read = do_read (read_rawBuffer fd buf off len)
576 safe_read = do_read (safe_read_rawBuffer fd buf off len)
577
578 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
579 readRawBufferPtr loc fd is_nonblock buf off len
580 | is_nonblock = unsafe_read -- unsafe is ok, it can't block
581 | otherwise = do r <- throwErrnoIfMinus1 loc
582 (unsafe_fdReady (fromIntegral fd) 0 0 0)
583 if r /= 0
584 then read
585 else do threadWaitRead (fromIntegral fd); read
586 where
587 do_read call = throwErrnoIfMinus1RetryMayBlock loc call
588 (threadWaitRead (fromIntegral fd))
589 read = if threaded then safe_read else unsafe_read
590 unsafe_read = do_read (read_off fd buf off len)
591 safe_read = do_read (safe_read_off fd buf off len)
592
593 readRawBufferNoBlock :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
594 readRawBufferNoBlock loc fd is_nonblock buf off len
595 | is_nonblock = unsafe_read -- unsafe is ok, it can't block
596 | otherwise = do r <- unsafe_fdReady (fromIntegral fd) 0 0 0
597 if r /= 0 then safe_read
598 else return 0
599 -- XXX see note [nonblock]
600 where
601 do_read call = throwErrnoIfMinus1RetryOnBlock loc call (return 0)
602 unsafe_read = do_read (read_rawBuffer fd buf off len)
603 safe_read = do_read (safe_read_rawBuffer fd buf off len)
604
605 readRawBufferPtrNoBlock :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
606 readRawBufferPtrNoBlock loc fd is_nonblock buf off len
607 | is_nonblock = unsafe_read -- unsafe is ok, it can't block
608 | otherwise = do r <- unsafe_fdReady (fromIntegral fd) 0 0 0
609 if r /= 0 then safe_read
610 else return 0
611 -- XXX see note [nonblock]
612 where
613 do_read call = throwErrnoIfMinus1RetryOnBlock loc call (return 0)
614 unsafe_read = do_read (read_off fd buf off len)
615 safe_read = do_read (safe_read_off fd buf off len)
616
617 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
618 writeRawBuffer loc fd is_nonblock buf off len
619 | is_nonblock = unsafe_write -- unsafe is ok, it can't block
620 | otherwise = do r <- unsafe_fdReady (fromIntegral fd) 1 0 0
621 if r /= 0
622 then write
623 else do threadWaitWrite (fromIntegral fd); write
624 where
625 do_write call = throwErrnoIfMinus1RetryMayBlock loc call
626 (threadWaitWrite (fromIntegral fd))
627 write = if threaded then safe_write else unsafe_write
628 unsafe_write = do_write (write_rawBuffer fd buf off len)
629 safe_write = do_write (safe_write_rawBuffer (fromIntegral fd) buf off len)
630
631 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
632 writeRawBufferPtr loc fd is_nonblock buf off len
633 | is_nonblock = unsafe_write -- unsafe is ok, it can't block
634 | otherwise = do r <- unsafe_fdReady (fromIntegral fd) 1 0 0
635 if r /= 0
636 then write
637 else do threadWaitWrite (fromIntegral fd); write
638 where
639 do_write call = throwErrnoIfMinus1RetryMayBlock loc call
640 (threadWaitWrite (fromIntegral fd))
641 write = if threaded then safe_write else unsafe_write
642 unsafe_write = do_write (write_off fd buf off len)
643 safe_write = do_write (safe_write_off (fromIntegral fd) buf off len)
644
645 foreign import ccall unsafe "__hscore_PrelHandle_read"
646 read_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
647
648 foreign import ccall unsafe "__hscore_PrelHandle_read"
649 read_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
650
651 foreign import ccall unsafe "__hscore_PrelHandle_write"
652 write_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
653
654 foreign import ccall unsafe "__hscore_PrelHandle_write"
655 write_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
656
657 foreign import ccall unsafe "fdReady"
658 unsafe_fdReady :: CInt -> CInt -> CInt -> CInt -> IO CInt
659
660 #else /* mingw32_HOST_OS.... */
661
662 readRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
663 readRawBuffer loc fd is_stream buf off len
664 | threaded = blockingReadRawBuffer loc fd is_stream buf off len
665 | otherwise = asyncReadRawBuffer loc fd is_stream buf off len
666
667 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
668 readRawBufferPtr loc fd is_stream buf off len
669 | threaded = blockingReadRawBufferPtr loc fd is_stream buf off len
670 | otherwise = asyncReadRawBufferPtr loc fd is_stream buf off len
671
672 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
673 writeRawBuffer loc fd is_stream buf off len
674 | threaded = blockingWriteRawBuffer loc fd is_stream buf off len
675 | otherwise = asyncWriteRawBuffer loc fd is_stream buf off len
676
677 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
678 writeRawBufferPtr loc fd is_stream buf off len
679 | threaded = blockingWriteRawBufferPtr loc fd is_stream buf off len
680 | otherwise = asyncWriteRawBufferPtr loc fd is_stream buf off len
681
682 -- ToDo: we don't have a non-blocking primitve read on Win32
683 readRawBufferNoBlock :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
684 readRawBufferNoBlock = readRawBuffer
685
686 readRawBufferPtrNoBlock :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
687 readRawBufferPtrNoBlock = readRawBufferPtr
688 -- Async versions of the read/write primitives, for the non-threaded RTS
689
690 asyncReadRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt
691 -> IO CInt
692 asyncReadRawBuffer loc fd is_stream buf off len = do
693 (l, rc) <- asyncReadBA (fromIntegral fd) (if is_stream then 1 else 0)
694 (fromIntegral len) off buf
695 if l == (-1)
696 then
697 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
698 else return (fromIntegral l)
699
700 asyncReadRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt
701 -> IO CInt
702 asyncReadRawBufferPtr loc fd is_stream buf off len = do
703 (l, rc) <- asyncRead (fromIntegral fd) (if is_stream then 1 else 0)
704 (fromIntegral len) (buf `plusPtr` off)
705 if l == (-1)
706 then
707 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
708 else return (fromIntegral l)
709
710 asyncWriteRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt
711 -> IO CInt
712 asyncWriteRawBuffer loc fd is_stream buf off len = do
713 (l, rc) <- asyncWriteBA (fromIntegral fd) (if is_stream then 1 else 0)
714 (fromIntegral len) off buf
715 if l == (-1)
716 then
717 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
718 else return (fromIntegral l)
719
720 asyncWriteRawBufferPtr :: String -> FD -> Bool -> CString -> Int -> CInt
721 -> IO CInt
722 asyncWriteRawBufferPtr loc fd is_stream buf off len = do
723 (l, rc) <- asyncWrite (fromIntegral fd) (if is_stream then 1 else 0)
724 (fromIntegral len) (buf `plusPtr` off)
725 if l == (-1)
726 then
727 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
728 else return (fromIntegral l)
729
730 -- Blocking versions of the read/write primitives, for the threaded RTS
731
732 blockingReadRawBuffer :: String -> CInt -> Bool -> RawBuffer -> Int -> CInt
733 -> IO CInt
734 blockingReadRawBuffer loc fd True buf off len =
735 throwErrnoIfMinus1Retry loc $
736 safe_recv_rawBuffer fd buf off len
737 blockingReadRawBuffer loc fd False buf off len =
738 throwErrnoIfMinus1Retry loc $
739 safe_read_rawBuffer fd buf off len
740
741 blockingReadRawBufferPtr :: String -> CInt -> Bool -> CString -> Int -> CInt
742 -> IO CInt
743 blockingReadRawBufferPtr loc fd True buf off len =
744 throwErrnoIfMinus1Retry loc $
745 safe_recv_off fd buf off len
746 blockingReadRawBufferPtr loc fd False buf off len =
747 throwErrnoIfMinus1Retry loc $
748 safe_read_off fd buf off len
749
750 blockingWriteRawBuffer :: String -> CInt -> Bool -> RawBuffer -> Int -> CInt
751 -> IO CInt
752 blockingWriteRawBuffer loc fd True buf off len =
753 throwErrnoIfMinus1Retry loc $
754 safe_send_rawBuffer fd buf off len
755 blockingWriteRawBuffer loc fd False buf off len =
756 throwErrnoIfMinus1Retry loc $
757 safe_write_rawBuffer fd buf off len
758
759 blockingWriteRawBufferPtr :: String -> CInt -> Bool -> CString -> Int -> CInt
760 -> IO CInt
761 blockingWriteRawBufferPtr loc fd True buf off len =
762 throwErrnoIfMinus1Retry loc $
763 safe_send_off fd buf off len
764 blockingWriteRawBufferPtr loc fd False buf off len =
765 throwErrnoIfMinus1Retry loc $
766 safe_write_off fd buf off len
767
768 -- NOTE: "safe" versions of the read/write calls for use by the threaded RTS.
769 -- These calls may block, but that's ok.
770
771 foreign import ccall safe "__hscore_PrelHandle_recv"
772 safe_recv_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
773
774 foreign import ccall safe "__hscore_PrelHandle_recv"
775 safe_recv_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
776
777 foreign import ccall safe "__hscore_PrelHandle_send"
778 safe_send_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
779
780 foreign import ccall safe "__hscore_PrelHandle_send"
781 safe_send_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
782
783 #endif
784
785 foreign import ccall "rtsSupportsBoundThreads" threaded :: Bool
786
787 foreign import ccall safe "__hscore_PrelHandle_read"
788 safe_read_rawBuffer :: FD -> RawBuffer -> Int -> CInt -> IO CInt
789
790 foreign import ccall safe "__hscore_PrelHandle_read"
791 safe_read_off :: FD -> Ptr CChar -> Int -> CInt -> IO CInt
792
793 foreign import ccall safe "__hscore_PrelHandle_write"
794 safe_write_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
795
796 foreign import ccall safe "__hscore_PrelHandle_write"
797 safe_write_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
798
799 -- ---------------------------------------------------------------------------
800 -- Standard Handles
801
802 -- Three handles are allocated during program initialisation. The first
803 -- two manage input or output from the Haskell program's standard input
804 -- or output channel respectively. The third manages output to the
805 -- standard error channel. These handles are initially open.
806
807 fd_stdin, fd_stdout, fd_stderr :: FD
808 fd_stdin = 0
809 fd_stdout = 1
810 fd_stderr = 2
811
812 -- | A handle managing input from the Haskell program's standard input channel.
813 stdin :: Handle
814 stdin = unsafePerformIO $ do
815 -- ToDo: acquire lock
816 -- We don't set non-blocking mode on standard handles, because it may
817 -- confuse other applications attached to the same TTY/pipe
818 -- see Note [nonblock]
819 (buf, bmode) <- getBuffer fd_stdin ReadBuffer
820 mkStdHandle fd_stdin "<stdin>" ReadHandle buf bmode
821
822 -- | A handle managing output to the Haskell program's standard output channel.
823 stdout :: Handle
824 stdout = unsafePerformIO $ do
825 -- ToDo: acquire lock
826 -- We don't set non-blocking mode on standard handles, because it may
827 -- confuse other applications attached to the same TTY/pipe
828 -- see Note [nonblock]
829 (buf, bmode) <- getBuffer fd_stdout WriteBuffer
830 mkStdHandle fd_stdout "<stdout>" WriteHandle buf bmode
831
832 -- | A handle managing output to the Haskell program's standard error channel.
833 stderr :: Handle
834 stderr = unsafePerformIO $ do
835 -- ToDo: acquire lock
836 -- We don't set non-blocking mode on standard handles, because it may
837 -- confuse other applications attached to the same TTY/pipe
838 -- see Note [nonblock]
839 buf <- mkUnBuffer
840 mkStdHandle fd_stderr "<stderr>" WriteHandle buf NoBuffering
841
842 -- ---------------------------------------------------------------------------
843 -- Opening and Closing Files
844
845 addFilePathToIOError :: String -> FilePath -> IOException -> IOException
846 addFilePathToIOError fun fp ioe
847 = ioe{ ioe_location = fun, ioe_filename = Just fp }
848
849 -- | Computation 'openFile' @file mode@ allocates and returns a new, open
850 -- handle to manage the file @file@. It manages input if @mode@
851 -- is 'ReadMode', output if @mode@ is 'WriteMode' or 'AppendMode',
852 -- and both input and output if mode is 'ReadWriteMode'.
853 --
854 -- If the file does not exist and it is opened for output, it should be
855 -- created as a new file. If @mode@ is 'WriteMode' and the file
856 -- already exists, then it should be truncated to zero length.
857 -- Some operating systems delete empty files, so there is no guarantee
858 -- that the file will exist following an 'openFile' with @mode@
859 -- 'WriteMode' unless it is subsequently written to successfully.
860 -- The handle is positioned at the end of the file if @mode@ is
861 -- 'AppendMode', and otherwise at the beginning (in which case its
862 -- internal position is 0).
863 -- The initial buffer mode is implementation-dependent.
864 --
865 -- This operation may fail with:
866 --
867 -- * 'isAlreadyInUseError' if the file is already open and cannot be reopened;
868 --
869 -- * 'isDoesNotExistError' if the file does not exist; or
870 --
871 -- * 'isPermissionError' if the user does not have permission to open the file.
872 --
873 -- Note: if you will be working with files containing binary data, you'll want to
874 -- be using 'openBinaryFile'.
875 openFile :: FilePath -> IOMode -> IO Handle
876 openFile fp im =
877 catch
878 (openFile' fp im dEFAULT_OPEN_IN_BINARY_MODE)
879 (\e -> ioError (addFilePathToIOError "openFile" fp e))
880
881 -- | Like 'openFile', but open the file in binary mode.
882 -- On Windows, reading a file in text mode (which is the default)
883 -- will translate CRLF to LF, and writing will translate LF to CRLF.
884 -- This is usually what you want with text files. With binary files
885 -- this is undesirable; also, as usual under Microsoft operating systems,
886 -- text mode treats control-Z as EOF. Binary mode turns off all special
887 -- treatment of end-of-line and end-of-file characters.
888 -- (See also 'hSetBinaryMode'.)
889
890 openBinaryFile :: FilePath -> IOMode -> IO Handle
891 openBinaryFile fp m =
892 catch
893 (openFile' fp m True)
894 (\e -> ioError (addFilePathToIOError "openBinaryFile" fp e))
895
896 openFile' :: String -> IOMode -> Bool -> IO Handle
897 openFile' filepath mode binary =
898 withCString filepath $ \ f ->
899
900 let
901 oflags1 = case mode of
902 ReadMode -> read_flags
903 #ifdef mingw32_HOST_OS
904 WriteMode -> write_flags .|. o_TRUNC
905 #else
906 WriteMode -> write_flags
907 #endif
908 ReadWriteMode -> rw_flags
909 AppendMode -> append_flags
910
911 binary_flags
912 | binary = o_BINARY
913 | otherwise = 0
914
915 oflags = oflags1 .|. binary_flags
916 in do
917
918 -- the old implementation had a complicated series of three opens,
919 -- which is perhaps because we have to be careful not to open
920 -- directories. However, the man pages I've read say that open()
921 -- always returns EISDIR if the file is a directory and was opened
922 -- for writing, so I think we're ok with a single open() here...
923 fd <- throwErrnoIfMinus1Retry "openFile"
924 (c_open f (fromIntegral oflags) 0o666)
925
926 stat@(fd_type,_,_) <- fdStat fd
927
928 h <- fdToHandle_stat fd (Just stat)
929 False -- set_non_blocking
930 True -- is_non_blocking
931 False -- is_socket
932 filepath mode binary
933 `catchAny` \e -> do c_close fd; throw e
934 -- NB. don't forget to close the FD if fdToHandle' fails, otherwise
935 -- this FD leaks.
936 -- ASSERT: if we just created the file, then fdToHandle' won't fail
937 -- (so we don't need to worry about removing the newly created file
938 -- in the event of an error).
939
940 #ifndef mingw32_HOST_OS
941 -- we want to truncate() if this is an open in WriteMode, but only
942 -- if the target is a RegularFile. ftruncate() fails on special files
943 -- like /dev/null.
944 if mode == WriteMode && fd_type == RegularFile
945 then throwErrnoIf (/=0) "openFile"
946 (c_ftruncate fd 0)
947 else return 0
948 #endif
949 return h
950
951
952 std_flags, output_flags, read_flags, write_flags, rw_flags,
953 append_flags :: CInt
954 std_flags = o_NONBLOCK .|. o_NOCTTY
955 output_flags = std_flags .|. o_CREAT
956 read_flags = std_flags .|. o_RDONLY
957 write_flags = output_flags .|. o_WRONLY
958 rw_flags = output_flags .|. o_RDWR
959 append_flags = write_flags .|. o_APPEND
960
961 -- ---------------------------------------------------------------------------
962 -- fdToHandle
963
964 fdToHandle_stat :: FD
965 -> Maybe (FDType, CDev, CIno)
966 -> Bool -- set_non_blocking
967 -> Bool -- is_non_blocking
968 -> Bool -- is_socket
969 -> FilePath
970 -> IOMode
971 -> Bool
972 -> IO Handle
973
974 fdToHandle_stat fd mb_stat set_non_blocking is_non_blocking is_socket
975 filepath mode binary = do
976
977 #ifdef mingw32_HOST_OS
978 -- On Windows, the is_stream flag indicates that the Handle is a socket
979 let is_stream = is_socket
980 #else
981 when set_non_blocking $ setNonBlockingFD fd
982 -- turn on non-blocking mode
983
984 -- On Unix, the is_stream flag indicates that the FD is in non-blocking mode
985 let is_stream = is_non_blocking || set_non_blocking
986 #endif
987
988 let (ha_type, write) =
989 case mode of
990 ReadMode -> ( ReadHandle, False )
991 WriteMode -> ( WriteHandle, True )
992 ReadWriteMode -> ( ReadWriteHandle, True )
993 AppendMode -> ( AppendHandle, True )
994
995 -- open() won't tell us if it was a directory if we only opened for
996 -- reading, so check again.
997 (fd_type,dev,ino) <-
998 case mb_stat of
999 Just x -> return x
1000 Nothing -> fdStat fd
1001
1002 case fd_type of
1003 Directory ->
1004 ioException (IOError Nothing InappropriateType "openFile"
1005 "is a directory" Nothing Nothing)
1006
1007 -- regular files need to be locked
1008 RegularFile -> do
1009 #ifndef mingw32_HOST_OS
1010 -- On Windows we use explicit exclusion via sopen() to implement
1011 -- this locking (see __hscore_open()); on Unix we have to
1012 -- implment it in the RTS.
1013 r <- lockFile fd dev ino (fromBool write)
1014 when (r == -1) $
1015 ioException (IOError Nothing ResourceBusy "openFile"
1016 "file is locked" Nothing Nothing)
1017 #endif
1018 mkFileHandle fd is_stream filepath ha_type binary
1019
1020 Stream
1021 -- only *Streams* can be DuplexHandles. Other read/write
1022 -- Handles must share a buffer.
1023 | ReadWriteHandle <- ha_type ->
1024 mkDuplexHandle fd is_stream filepath binary
1025 | otherwise ->
1026 mkFileHandle fd is_stream filepath ha_type binary
1027
1028 RawDevice ->
1029 mkFileHandle fd is_stream filepath ha_type binary
1030
1031 -- | Old API kept to avoid breaking clients
1032 fdToHandle' :: FD -> Maybe FDType -> Bool -> FilePath -> IOMode -> Bool
1033 -> IO Handle
1034 fdToHandle' fd mb_type is_socket filepath mode binary
1035 = do
1036 let mb_stat = case mb_type of
1037 Nothing -> Nothing
1038 -- fdToHandle_stat will do the stat:
1039 Just RegularFile -> Nothing
1040 -- no stat required for streams etc.:
1041 Just other -> Just (other,0,0)
1042 fdToHandle_stat fd mb_stat
1043 is_socket -- set_non_blocking
1044 False -- is_non_blocking
1045 is_socket -- is_socket
1046 filepath mode binary
1047
1048 fdToHandle :: FD -> IO Handle
1049 fdToHandle fd = do
1050 mode <- fdGetMode fd
1051 let fd_str = "<file descriptor: " ++ show fd ++ ">"
1052 fdToHandle_stat fd Nothing
1053 False -- set_non_blocking
1054 False -- is_non_blocking
1055 False -- is_socket (guess XXX)
1056 fd_str mode True{-bin mode-}
1057
1058 #ifndef mingw32_HOST_OS
1059 foreign import ccall unsafe "lockFile"
1060 lockFile :: CInt -> CDev -> CIno -> CInt -> IO CInt
1061
1062 foreign import ccall unsafe "unlockFile"
1063 unlockFile :: CInt -> IO CInt
1064 #endif
1065
1066 mkStdHandle :: FD -> FilePath -> HandleType -> IORef Buffer -> BufferMode
1067 -> IO Handle
1068 mkStdHandle fd filepath ha_type buf bmode = do
1069 spares <- newIORef BufferListNil
1070 newFileHandle filepath (stdHandleFinalizer filepath)
1071 (Handle__ { haFD = fd,
1072 haType = ha_type,
1073 haIsBin = dEFAULT_OPEN_IN_BINARY_MODE,
1074 haIsStream = False, -- means FD is blocking on Unix
1075 haBufferMode = bmode,
1076 haBuffer = buf,
1077 haBuffers = spares,
1078 haOtherSide = Nothing
1079 })
1080
1081 mkFileHandle :: FD -> Bool -> FilePath -> HandleType -> Bool -> IO Handle
1082 mkFileHandle fd is_stream filepath ha_type binary = do
1083 (buf, bmode) <- getBuffer fd (initBufferState ha_type)
1084
1085 #ifdef mingw32_HOST_OS
1086 -- On Windows, if this is a read/write handle and we are in text mode,
1087 -- turn off buffering. We don't correctly handle the case of switching
1088 -- from read mode to write mode on a buffered text-mode handle, see bug
1089 -- \#679.
1090 bmode2 <- case ha_type of
1091 ReadWriteHandle | not binary -> return NoBuffering
1092 _other -> return bmode
1093 #else
1094 let bmode2 = bmode
1095 #endif
1096
1097 spares <- newIORef BufferListNil
1098 newFileHandle filepath (handleFinalizer filepath)
1099 (Handle__ { haFD = fd,
1100 haType = ha_type,
1101 haIsBin = binary,
1102 haIsStream = is_stream,
1103 haBufferMode = bmode2,
1104 haBuffer = buf,
1105 haBuffers = spares,
1106 haOtherSide = Nothing
1107 })
1108
1109 mkDuplexHandle :: FD -> Bool -> FilePath -> Bool -> IO Handle
1110 mkDuplexHandle fd is_stream filepath binary = do
1111 (w_buf, w_bmode) <- getBuffer fd WriteBuffer
1112 w_spares <- newIORef BufferListNil
1113 let w_handle_ =
1114 Handle__ { haFD = fd,
1115 haType = WriteHandle,
1116 haIsBin = binary,
1117 haIsStream = is_stream,
1118 haBufferMode = w_bmode,
1119 haBuffer = w_buf,
1120 haBuffers = w_spares,
1121 haOtherSide = Nothing
1122 }
1123 write_side <- newMVar w_handle_
1124
1125 (r_buf, r_bmode) <- getBuffer fd ReadBuffer
1126 r_spares <- newIORef BufferListNil
1127 let r_handle_ =
1128 Handle__ { haFD = fd,
1129 haType = ReadHandle,
1130 haIsBin = binary,
1131 haIsStream = is_stream,
1132 haBufferMode = r_bmode,
1133 haBuffer = r_buf,
1134 haBuffers = r_spares,
1135 haOtherSide = Just write_side
1136 }
1137 read_side <- newMVar r_handle_
1138
1139 addMVarFinalizer write_side (handleFinalizer filepath write_side)
1140 return (DuplexHandle filepath read_side write_side)
1141
1142 initBufferState :: HandleType -> BufferState
1143 initBufferState ReadHandle = ReadBuffer
1144 initBufferState _ = WriteBuffer
1145
1146 -- ---------------------------------------------------------------------------
1147 -- Closing a handle
1148
1149 -- | Computation 'hClose' @hdl@ makes handle @hdl@ closed. Before the
1150 -- computation finishes, if @hdl@ is writable its buffer is flushed as
1151 -- for 'hFlush'.
1152 -- Performing 'hClose' on a handle that has already been closed has no effect;
1153 -- doing so is not an error. All other operations on a closed handle will fail.
1154 -- If 'hClose' fails for any reason, any further operations (apart from
1155 -- 'hClose') on the handle will still fail as if @hdl@ had been successfully
1156 -- closed.
1157
1158 hClose :: Handle -> IO ()
1159 hClose h@(FileHandle _ m) = do
1160 mb_exc <- hClose' h m
1161 case mb_exc of
1162 Nothing -> return ()
1163 Just e -> throwIO e
1164 hClose h@(DuplexHandle _ r w) = do
1165 mb_exc1 <- hClose' h w
1166 mb_exc2 <- hClose' h r
1167 case (do mb_exc1; mb_exc2) of
1168 Nothing -> return ()
1169 Just e -> throwIO e
1170
1171 hClose' :: Handle -> MVar Handle__ -> IO (Maybe SomeException)
1172 hClose' h m = withHandle' "hClose" h m $ hClose_help
1173
1174 -- hClose_help is also called by lazyRead (in PrelIO) when EOF is read
1175 -- or an IO error occurs on a lazy stream. The semi-closed Handle is
1176 -- then closed immediately. We have to be careful with DuplexHandles
1177 -- though: we have to leave the closing to the finalizer in that case,
1178 -- because the write side may still be in use.
1179 hClose_help :: Handle__ -> IO (Handle__, Maybe SomeException)
1180 hClose_help handle_ =
1181 case haType handle_ of
1182 ClosedHandle -> return (handle_,Nothing)
1183 _ -> do flushWriteBufferOnly handle_ -- interruptible
1184 hClose_handle_ handle_
1185
1186 hClose_handle_ :: Handle__ -> IO (Handle__, Maybe SomeException)
1187 hClose_handle_ handle_ = do
1188 let fd = haFD handle_
1189
1190 -- close the file descriptor, but not when this is the read
1191 -- side of a duplex handle.
1192 -- If an exception is raised by the close(), we want to continue
1193 -- to close the handle and release the lock if it has one, then
1194 -- we return the exception to the caller of hClose_help which can
1195 -- raise it if necessary.
1196 maybe_exception <-
1197 case haOtherSide handle_ of
1198 Nothing -> (do
1199 throwErrnoIfMinus1Retry_ "hClose"
1200 #ifdef mingw32_HOST_OS
1201 (closeFd (haIsStream handle_) fd)
1202 #else
1203 (c_close fd)
1204 #endif
1205 return Nothing
1206 )
1207 `catchException` \e -> return (Just e)
1208
1209 Just _ -> return Nothing
1210
1211 -- free the spare buffers
1212 writeIORef (haBuffers handle_) BufferListNil
1213 writeIORef (haBuffer handle_) noBuffer
1214
1215 #ifndef mingw32_HOST_OS
1216 -- unlock it
1217 unlockFile fd
1218 #endif
1219
1220 -- we must set the fd to -1, because the finalizer is going
1221 -- to run eventually and try to close/unlock it.
1222 return (handle_{ haFD = -1,
1223 haType = ClosedHandle
1224 },
1225 maybe_exception)
1226
1227 {-# NOINLINE noBuffer #-}
1228 noBuffer :: Buffer
1229 noBuffer = unsafePerformIO $ allocateBuffer 1 ReadBuffer
1230
1231 -----------------------------------------------------------------------------
1232 -- Detecting and changing the size of a file
1233
1234 -- | For a handle @hdl@ which attached to a physical file,
1235 -- 'hFileSize' @hdl@ returns the size of that file in 8-bit bytes.
1236
1237 hFileSize :: Handle -> IO Integer
1238 hFileSize handle =
1239 withHandle_ "hFileSize" handle $ \ handle_ -> do
1240 case haType handle_ of
1241 ClosedHandle -> ioe_closedHandle
1242 SemiClosedHandle -> ioe_closedHandle
1243 _ -> do flushWriteBufferOnly handle_
1244 r <- fdFileSize (haFD handle_)
1245 if r /= -1
1246 then return r
1247 else ioException (IOError Nothing InappropriateType "hFileSize"
1248 "not a regular file" Nothing Nothing)
1249
1250
1251 -- | 'hSetFileSize' @hdl@ @size@ truncates the physical file with handle @hdl@ to @size@ bytes.
1252
1253 hSetFileSize :: Handle -> Integer -> IO ()
1254 hSetFileSize handle size =
1255 withHandle_ "hSetFileSize" handle $ \ handle_ -> do
1256 case haType handle_ of
1257 ClosedHandle -> ioe_closedHandle
1258 SemiClosedHandle -> ioe_closedHandle
1259 _ -> do flushWriteBufferOnly handle_
1260 throwErrnoIf (/=0) "hSetFileSize"
1261 (c_ftruncate (haFD handle_) (fromIntegral size))
1262 return ()
1263
1264 -- ---------------------------------------------------------------------------
1265 -- Detecting the End of Input
1266
1267 -- | For a readable handle @hdl@, 'hIsEOF' @hdl@ returns
1268 -- 'True' if no further input can be taken from @hdl@ or for a
1269 -- physical file, if the current I\/O position is equal to the length of
1270 -- the file. Otherwise, it returns 'False'.
1271 --
1272 -- NOTE: 'hIsEOF' may block, because it is the same as calling
1273 -- 'hLookAhead' and checking for an EOF exception.
1274
1275 hIsEOF :: Handle -> IO Bool
1276 hIsEOF handle =
1277 catch
1278 (do hLookAhead handle; return False)
1279 (\e -> if isEOFError e then return True else ioError e)
1280
1281 -- | The computation 'isEOF' is identical to 'hIsEOF',
1282 -- except that it works only on 'stdin'.
1283
1284 isEOF :: IO Bool
1285 isEOF = hIsEOF stdin
1286
1287 -- ---------------------------------------------------------------------------
1288 -- Looking ahead
1289
1290 -- | Computation 'hLookAhead' returns the next character from the handle
1291 -- without removing it from the input buffer, blocking until a character
1292 -- is available.
1293 --
1294 -- This operation may fail with:
1295 --
1296 -- * 'isEOFError' if the end of file has been reached.
1297
1298 hLookAhead :: Handle -> IO Char
1299 hLookAhead handle =
1300 wantReadableHandle "hLookAhead" handle hLookAhead'
1301
1302 hLookAhead' :: Handle__ -> IO Char
1303 hLookAhead' handle_ = do
1304 let ref = haBuffer handle_
1305 fd = haFD handle_
1306 buf <- readIORef ref
1307
1308 -- fill up the read buffer if necessary
1309 new_buf <- if bufferEmpty buf
1310 then fillReadBuffer fd True (haIsStream handle_) buf
1311 else return buf
1312
1313 writeIORef ref new_buf
1314
1315 (c,_) <- readCharFromBuffer (bufBuf buf) (bufRPtr buf)
1316 return c
1317
1318 -- ---------------------------------------------------------------------------
1319 -- Buffering Operations
1320
1321 -- Three kinds of buffering are supported: line-buffering,
1322 -- block-buffering or no-buffering. See GHC.IOBase for definition and
1323 -- further explanation of what the type represent.
1324
1325 -- | Computation 'hSetBuffering' @hdl mode@ sets the mode of buffering for
1326 -- handle @hdl@ on subsequent reads and writes.
1327 --
1328 -- If the buffer mode is changed from 'BlockBuffering' or
1329 -- 'LineBuffering' to 'NoBuffering', then
1330 --
1331 -- * if @hdl@ is writable, the buffer is flushed as for 'hFlush';
1332 --
1333 -- * if @hdl@ is not writable, the contents of the buffer is discarded.
1334 --
1335 -- This operation may fail with:
1336 --
1337 -- * 'isPermissionError' if the handle has already been used for reading
1338 -- or writing and the implementation does not allow the buffering mode
1339 -- to be changed.
1340
1341 hSetBuffering :: Handle -> BufferMode -> IO ()
1342 hSetBuffering handle mode =
1343 withAllHandles__ "hSetBuffering" handle $ \ handle_ -> do
1344 case haType handle_ of
1345 ClosedHandle -> ioe_closedHandle
1346 _ -> do
1347 {- Note:
1348 - we flush the old buffer regardless of whether
1349 the new buffer could fit the contents of the old buffer
1350 or not.
1351 - allow a handle's buffering to change even if IO has
1352 occurred (ANSI C spec. does not allow this, nor did
1353 the previous implementation of IO.hSetBuffering).
1354 - a non-standard extension is to allow the buffering
1355 of semi-closed handles to change [sof 6/98]
1356 -}
1357 flushBuffer handle_
1358
1359 let state = initBufferState (haType handle_)
1360 new_buf <-
1361 case mode of
1362 -- we always have a 1-character read buffer for
1363 -- unbuffered handles: it's needed to
1364 -- support hLookAhead.
1365 NoBuffering -> allocateBuffer 1 ReadBuffer
1366 LineBuffering -> allocateBuffer dEFAULT_BUFFER_SIZE state
1367 BlockBuffering Nothing -> allocateBuffer dEFAULT_BUFFER_SIZE state
1368 BlockBuffering (Just n) | n <= 0 -> ioe_bufsiz n
1369 | otherwise -> allocateBuffer n state
1370 writeIORef (haBuffer handle_) new_buf
1371
1372 -- for input terminals we need to put the terminal into
1373 -- cooked or raw mode depending on the type of buffering.
1374 is_tty <- fdIsTTY (haFD handle_)
1375 when (is_tty && isReadableHandleType (haType handle_)) $
1376 case mode of
1377 #ifndef mingw32_HOST_OS
1378 -- 'raw' mode under win32 is a bit too specialised (and troublesome
1379 -- for most common uses), so simply disable its use here.
1380 NoBuffering -> setCooked (haFD handle_) False
1381 #else
1382 NoBuffering -> return ()
1383 #endif
1384 _ -> setCooked (haFD handle_) True
1385
1386 -- throw away spare buffers, they might be the wrong size
1387 writeIORef (haBuffers handle_) BufferListNil
1388
1389 return (handle_{ haBufferMode = mode })
1390
1391 -- -----------------------------------------------------------------------------
1392 -- hFlush
1393
1394 -- | The action 'hFlush' @hdl@ causes any items buffered for output
1395 -- in handle @hdl@ to be sent immediately to the operating system.
1396 --
1397 -- This operation may fail with:
1398 --
1399 -- * 'isFullError' if the device is full;
1400 --
1401 -- * 'isPermissionError' if a system resource limit would be exceeded.
1402 -- It is unspecified whether the characters in the buffer are discarded
1403 -- or retained under these circumstances.
1404
1405 hFlush :: Handle -> IO ()
1406 hFlush handle =
1407 wantWritableHandle "hFlush" handle $ \ handle_ -> do
1408 buf <- readIORef (haBuffer handle_)
1409 if bufferIsWritable buf && not (bufferEmpty buf)
1410 then do flushed_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
1411 writeIORef (haBuffer handle_) flushed_buf
1412 else return ()
1413
1414
1415 -- -----------------------------------------------------------------------------
1416 -- Repositioning Handles
1417
1418 data HandlePosn = HandlePosn Handle HandlePosition
1419
1420 instance Eq HandlePosn where
1421 (HandlePosn h1 p1) == (HandlePosn h2 p2) = p1==p2 && h1==h2
1422
1423 instance Show HandlePosn where
1424 showsPrec p (HandlePosn h pos) =
1425 showsPrec p h . showString " at position " . shows pos
1426
1427 -- HandlePosition is the Haskell equivalent of POSIX' off_t.
1428 -- We represent it as an Integer on the Haskell side, but
1429 -- cheat slightly in that hGetPosn calls upon a C helper
1430 -- that reports the position back via (merely) an Int.
1431 type HandlePosition = Integer
1432
1433 -- | Computation 'hGetPosn' @hdl@ returns the current I\/O position of
1434 -- @hdl@ as a value of the abstract type 'HandlePosn'.
1435
1436 hGetPosn :: Handle -> IO HandlePosn
1437 hGetPosn handle = do
1438 posn <- hTell handle
1439 return (HandlePosn handle posn)
1440
1441 -- | If a call to 'hGetPosn' @hdl@ returns a position @p@,
1442 -- then computation 'hSetPosn' @p@ sets the position of @hdl@
1443 -- to the position it held at the time of the call to 'hGetPosn'.
1444 --
1445 -- This operation may fail with:
1446 --
1447 -- * 'isPermissionError' if a system resource limit would be exceeded.
1448
1449 hSetPosn :: HandlePosn -> IO ()
1450 hSetPosn (HandlePosn h i) = hSeek h AbsoluteSeek i
1451
1452 -- ---------------------------------------------------------------------------
1453 -- hSeek
1454
1455 -- | A mode that determines the effect of 'hSeek' @hdl mode i@, as follows:
1456 data SeekMode
1457 = AbsoluteSeek -- ^ the position of @hdl@ is set to @i@.
1458 | RelativeSeek -- ^ the position of @hdl@ is set to offset @i@
1459 -- from the current position.
1460 | SeekFromEnd -- ^ the position of @hdl@ is set to offset @i@
1461 -- from the end of the file.
1462 deriving (Eq, Ord, Ix, Enum, Read, Show)
1463
1464 {- Note:
1465 - when seeking using `SeekFromEnd', positive offsets (>=0) means
1466 seeking at or past EOF.
1467
1468 - we possibly deviate from the report on the issue of seeking within
1469 the buffer and whether to flush it or not. The report isn't exactly
1470 clear here.
1471 -}
1472
1473 -- | Computation 'hSeek' @hdl mode i@ sets the position of handle
1474 -- @hdl@ depending on @mode@.
1475 -- The offset @i@ is given in terms of 8-bit bytes.
1476 --
1477 -- If @hdl@ is block- or line-buffered, then seeking to a position which is not
1478 -- in the current buffer will first cause any items in the output buffer to be
1479 -- written to the device, and then cause the input buffer to be discarded.
1480 -- Some handles may not be seekable (see 'hIsSeekable'), or only support a
1481 -- subset of the possible positioning operations (for instance, it may only
1482 -- be possible to seek to the end of a tape, or to a positive offset from
1483 -- the beginning or current position).
1484 -- It is not possible to set a negative I\/O position, or for
1485 -- a physical file, an I\/O position beyond the current end-of-file.
1486 --
1487 -- This operation may fail with:
1488 --
1489 -- * 'isPermissionError' if a system resource limit would be exceeded.
1490
1491 hSeek :: Handle -> SeekMode -> Integer -> IO ()
1492 hSeek handle mode offset =
1493 wantSeekableHandle "hSeek" handle $ \ handle_ -> do
1494 # ifdef DEBUG_DUMP
1495 puts ("hSeek " ++ show (mode,offset) ++ "\n")
1496 # endif
1497 let ref = haBuffer handle_
1498 buf <- readIORef ref
1499 let r = bufRPtr buf
1500 w = bufWPtr buf
1501 fd = haFD handle_
1502
1503 let do_seek =
1504 throwErrnoIfMinus1Retry_ "hSeek"
1505 (c_lseek (haFD handle_) (fromIntegral offset) whence)
1506
1507 whence :: CInt
1508 whence = case mode of
1509 AbsoluteSeek -> sEEK_SET
1510 RelativeSeek -> sEEK_CUR
1511 SeekFromEnd -> sEEK_END
1512
1513 if bufferIsWritable buf
1514 then do new_buf <- flushWriteBuffer fd (haIsStream handle_) buf
1515 writeIORef ref new_buf
1516 do_seek
1517 else do
1518
1519 if mode == RelativeSeek && offset >= 0 && offset < fromIntegral (w - r)
1520 then writeIORef ref buf{ bufRPtr = r + fromIntegral offset }
1521 else do
1522
1523 new_buf <- flushReadBuffer (haFD handle_) buf
1524 writeIORef ref new_buf
1525 do_seek
1526
1527
1528 hTell :: Handle -> IO Integer
1529 hTell handle =
1530 wantSeekableHandle "hGetPosn" handle $ \ handle_ -> do
1531
1532 #if defined(mingw32_HOST_OS)
1533 -- urgh, on Windows we have to worry about \n -> \r\n translation,
1534 -- so we can't easily calculate the file position using the
1535 -- current buffer size. Just flush instead.
1536 flushBuffer handle_
1537 #endif
1538 let fd = haFD handle_
1539 posn <- fromIntegral `liftM`
1540 throwErrnoIfMinus1Retry "hGetPosn"
1541 (c_lseek fd 0 sEEK_CUR)
1542
1543 let ref = haBuffer handle_
1544 buf <- readIORef ref
1545
1546 let real_posn
1547 | bufferIsWritable buf = posn + fromIntegral (bufWPtr buf)
1548 | otherwise = posn - fromIntegral (bufWPtr buf - bufRPtr buf)
1549 # ifdef DEBUG_DUMP
1550 puts ("\nhGetPosn: (fd, posn, real_posn) = " ++ show (fd, posn, real_posn) ++ "\n")
1551 puts (" (bufWPtr, bufRPtr) = " ++ show (bufWPtr buf, bufRPtr buf) ++ "\n")
1552 # endif
1553 return real_posn
1554
1555 -- -----------------------------------------------------------------------------
1556 -- Handle Properties
1557
1558 -- A number of operations return information about the properties of a
1559 -- handle. Each of these operations returns `True' if the handle has
1560 -- the specified property, and `False' otherwise.
1561
1562 hIsOpen :: Handle -> IO Bool
1563 hIsOpen handle =
1564 withHandle_ "hIsOpen" handle $ \ handle_ -> do
1565 case haType handle_ of
1566 ClosedHandle -> return False
1567 SemiClosedHandle -> return False
1568 _ -> return True
1569
1570 hIsClosed :: Handle -> IO Bool
1571 hIsClosed handle =
1572 withHandle_ "hIsClosed" handle $ \ handle_ -> do
1573 case haType handle_ of
1574 ClosedHandle -> return True
1575 _ -> return False
1576
1577 {- not defined, nor exported, but mentioned
1578 here for documentation purposes:
1579
1580 hSemiClosed :: Handle -> IO Bool
1581 hSemiClosed h = do
1582 ho <- hIsOpen h
1583 hc <- hIsClosed h
1584 return (not (ho || hc))
1585 -}
1586
1587 hIsReadable :: Handle -> IO Bool
1588 hIsReadable (DuplexHandle _ _ _) = return True
1589 hIsReadable handle =
1590 withHandle_ "hIsReadable" handle $ \ handle_ -> do
1591 case haType handle_ of
1592 ClosedHandle -> ioe_closedHandle
1593 SemiClosedHandle -> ioe_closedHandle
1594 htype -> return (isReadableHandleType htype)
1595
1596 hIsWritable :: Handle -> IO Bool
1597 hIsWritable (DuplexHandle _ _ _) = return True
1598 hIsWritable handle =
1599 withHandle_ "hIsWritable" handle $ \ handle_ -> do
1600 case haType handle_ of
1601 ClosedHandle -> ioe_closedHandle
1602 SemiClosedHandle -> ioe_closedHandle
1603 htype -> return (isWritableHandleType htype)
1604
1605 -- | Computation 'hGetBuffering' @hdl@ returns the current buffering mode
1606 -- for @hdl@.
1607
1608 hGetBuffering :: Handle -> IO BufferMode
1609 hGetBuffering handle =
1610 withHandle_ "hGetBuffering" handle $ \ handle_ -> do
1611 case haType handle_ of
1612 ClosedHandle -> ioe_closedHandle
1613 _ ->
1614 -- We're being non-standard here, and allow the buffering
1615 -- of a semi-closed handle to be queried. -- sof 6/98
1616 return (haBufferMode handle_) -- could be stricter..
1617
1618 hIsSeekable :: Handle -> IO Bool
1619 hIsSeekable handle =
1620 withHandle_ "hIsSeekable" handle $ \ handle_ -> do
1621 case haType handle_ of
1622 ClosedHandle -> ioe_closedHandle
1623 SemiClosedHandle -> ioe_closedHandle
1624 AppendHandle -> return False
1625 _ -> do t <- fdType (haFD handle_)
1626 return ((t == RegularFile || t == RawDevice)
1627 && (haIsBin handle_ || tEXT_MODE_SEEK_ALLOWED))
1628
1629 -- -----------------------------------------------------------------------------
1630 -- Changing echo status (Non-standard GHC extensions)
1631
1632 -- | Set the echoing status of a handle connected to a terminal.
1633
1634 hSetEcho :: Handle -> Bool -> IO ()
1635 hSetEcho handle on = do
1636 isT <- hIsTerminalDevice handle
1637 if not isT
1638 then return ()
1639 else
1640 withHandle_ "hSetEcho" handle $ \ handle_ -> do
1641 case haType handle_ of
1642 ClosedHandle -> ioe_closedHandle
1643 _ -> setEcho (haFD handle_) on
1644
1645 -- | Get the echoing status of a handle connected to a terminal.
1646
1647 hGetEcho :: Handle -> IO Bool
1648 hGetEcho handle = do
1649 isT <- hIsTerminalDevice handle
1650 if not isT
1651 then return False
1652 else
1653 withHandle_ "hGetEcho" handle $ \ handle_ -> do
1654 case haType handle_ of
1655 ClosedHandle -> ioe_closedHandle
1656 _ -> getEcho (haFD handle_)
1657
1658 -- | Is the handle connected to a terminal?
1659
1660 hIsTerminalDevice :: Handle -> IO Bool
1661 hIsTerminalDevice handle = do
1662 withHandle_ "hIsTerminalDevice" handle $ \ handle_ -> do
1663 case haType handle_ of
1664 ClosedHandle -> ioe_closedHandle
1665 _ -> fdIsTTY (haFD handle_)
1666
1667 -- -----------------------------------------------------------------------------
1668 -- hSetBinaryMode
1669
1670 -- | Select binary mode ('True') or text mode ('False') on a open handle.
1671 -- (See also 'openBinaryFile'.)
1672
1673 hSetBinaryMode :: Handle -> Bool -> IO ()
1674 hSetBinaryMode handle bin =
1675 withAllHandles__ "hSetBinaryMode" handle $ \ handle_ ->
1676 do throwErrnoIfMinus1_ "hSetBinaryMode"
1677 (setmode (haFD handle_) bin)
1678 return handle_{haIsBin=bin}
1679
1680 foreign import ccall unsafe "__hscore_setmode"
1681 setmode :: CInt -> Bool -> IO CInt
1682
1683 -- -----------------------------------------------------------------------------
1684 -- Duplicating a Handle
1685
1686 -- | Returns a duplicate of the original handle, with its own buffer.
1687 -- The two Handles will share a file pointer, however. The original
1688 -- handle's buffer is flushed, including discarding any input data,
1689 -- before the handle is duplicated.
1690
1691 hDuplicate :: Handle -> IO Handle
1692 hDuplicate h@(FileHandle path m) = do
1693 new_h_ <- withHandle' "hDuplicate" h m (dupHandle h Nothing)
1694 newFileHandle path (handleFinalizer path) new_h_
1695 hDuplicate h@(DuplexHandle path r w) = do
1696 new_w_ <- withHandle' "hDuplicate" h w (dupHandle h Nothing)
1697 new_w <- newMVar new_w_
1698 new_r_ <- withHandle' "hDuplicate" h r (dupHandle h (Just new_w))
1699 new_r <- newMVar new_r_
1700 addMVarFinalizer new_w (handleFinalizer path new_w)
1701 return (DuplexHandle path new_r new_w)
1702
1703 dupHandle :: Handle -> Maybe (MVar Handle__) -> Handle__
1704 -> IO (Handle__, Handle__)
1705 dupHandle h other_side h_ = do
1706 -- flush the buffer first, so we don't have to copy its contents
1707 flushBuffer h_
1708 new_fd <- case other_side of
1709 Nothing -> throwErrnoIfMinus1 "dupHandle" $ c_dup (haFD h_)
1710 Just r -> withHandle_' "dupHandle" h r (return . haFD)
1711 dupHandle_ other_side h_ new_fd
1712
1713 dupHandleTo :: Maybe (MVar Handle__) -> Handle__ -> Handle__
1714 -> IO (Handle__, Handle__)
1715 dupHandleTo other_side hto_ h_ = do
1716 flushBuffer h_
1717 -- Windows' dup2 does not return the new descriptor, unlike Unix
1718 throwErrnoIfMinus1 "dupHandleTo" $
1719 c_dup2 (haFD h_) (haFD hto_)
1720 dupHandle_ other_side h_ (haFD hto_)
1721
1722 dupHandle_ :: Maybe (MVar Handle__) -> Handle__ -> FD
1723 -> IO (Handle__, Handle__)
1724 dupHandle_ other_side h_ new_fd = do
1725 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE (initBufferState (haType h_))
1726 ioref <- newIORef buffer
1727 ioref_buffers <- newIORef BufferListNil
1728
1729 let new_handle_ = h_{ haFD = new_fd,
1730 haBuffer = ioref,
1731 haBuffers = ioref_buffers,
1732 haOtherSide = other_side }
1733 return (h_, new_handle_)
1734
1735 -- -----------------------------------------------------------------------------
1736 -- Replacing a Handle
1737
1738 {- |
1739 Makes the second handle a duplicate of the first handle. The second
1740 handle will be closed first, if it is not already.
1741
1742 This can be used to retarget the standard Handles, for example:
1743
1744 > do h <- openFile "mystdout" WriteMode
1745 > hDuplicateTo h stdout
1746 -}
1747
1748 hDuplicateTo :: Handle -> Handle -> IO ()
1749 hDuplicateTo h1@(FileHandle _ m1) h2@(FileHandle _ m2) = do
1750 withHandle__' "hDuplicateTo" h2 m2 $ \h2_ -> do
1751 _ <- hClose_help h2_
1752 withHandle' "hDuplicateTo" h1 m1 (dupHandleTo Nothing h2_)
1753 hDuplicateTo h1@(DuplexHandle _ r1 w1) h2@(DuplexHandle _ r2 w2) = do
1754 withHandle__' "hDuplicateTo" h2 w2 $ \w2_ -> do
1755 _ <- hClose_help w2_
1756 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo Nothing w2_)
1757 withHandle__' "hDuplicateTo" h2 r2 $ \r2_ -> do
1758 _ <- hClose_help r2_
1759 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo (Just w1) r2_)
1760 hDuplicateTo h1 _ =
1761 ioException (IOError (Just h1) IllegalOperation "hDuplicateTo"
1762 "handles are incompatible" Nothing Nothing)
1763
1764 -- ---------------------------------------------------------------------------
1765 -- showing Handles.
1766 --
1767 -- | 'hShow' is in the 'IO' monad, and gives more comprehensive output
1768 -- than the (pure) instance of 'Show' for 'Handle'.
1769
1770 hShow :: Handle -> IO String
1771 hShow h@(FileHandle path _) = showHandle' path False h
1772 hShow h@(DuplexHandle path _ _) = showHandle' path True h
1773
1774 showHandle' :: String -> Bool -> Handle -> IO String
1775 showHandle' filepath is_duplex h =
1776 withHandle_ "showHandle" h $ \hdl_ ->
1777 let
1778 showType | is_duplex = showString "duplex (read-write)"
1779 | otherwise = shows (haType hdl_)
1780 in
1781 return
1782 (( showChar '{' .
1783 showHdl (haType hdl_)
1784 (showString "loc=" . showString filepath . showChar ',' .
1785 showString "type=" . showType . showChar ',' .
1786 showString "binary=" . shows (haIsBin hdl_) . showChar ',' .
1787 showString "buffering=" . showBufMode (unsafePerformIO (readIORef (haBuffer hdl_))) (haBufferMode hdl_) . showString "}" )
1788 ) "")
1789 where
1790
1791 showHdl :: HandleType -> ShowS -> ShowS
1792 showHdl ht cont =
1793 case ht of
1794 ClosedHandle -> shows ht . showString "}"
1795 _ -> cont
1796
1797 showBufMode :: Buffer -> BufferMode -> ShowS
1798 showBufMode buf bmo =
1799 case bmo of
1800 NoBuffering -> showString "none"
1801 LineBuffering -> showString "line"
1802 BlockBuffering (Just n) -> showString "block " . showParen True (shows n)
1803 BlockBuffering Nothing -> showString "block " . showParen True (shows def)
1804 where
1805 def :: Int
1806 def = bufSize buf
1807
1808 -- ---------------------------------------------------------------------------
1809 -- debugging
1810
1811 #if defined(DEBUG_DUMP)
1812 puts :: String -> IO ()
1813 puts s = do write_rawBuffer 1 (unsafeCoerce# (packCString# s)) 0 (fromIntegral (length s))
1814 return ()
1815 #endif
1816
1817 -- -----------------------------------------------------------------------------
1818 -- utils
1819
1820 throwErrnoIfMinus1RetryOnBlock :: String -> IO CInt -> IO CInt -> IO CInt
1821 throwErrnoIfMinus1RetryOnBlock loc f on_block =
1822 do
1823 res <- f
1824 if (res :: CInt) == -1
1825 then do
1826 err <- getErrno
1827 if err == eINTR
1828 then throwErrnoIfMinus1RetryOnBlock loc f on_block
1829 else if err == eWOULDBLOCK || err == eAGAIN
1830 then do on_block
1831 else throwErrno loc
1832 else return res
1833
1834 -- -----------------------------------------------------------------------------
1835 -- wrappers to platform-specific constants:
1836
1837 foreign import ccall unsafe "__hscore_supportsTextMode"
1838 tEXT_MODE_SEEK_ALLOWED :: Bool
1839
1840 foreign import ccall unsafe "__hscore_bufsiz" dEFAULT_BUFFER_SIZE :: Int
1841 foreign import ccall unsafe "__hscore_seek_cur" sEEK_CUR :: CInt
1842 foreign import ccall unsafe "__hscore_seek_set" sEEK_SET :: CInt
1843 foreign import ccall unsafe "__hscore_seek_end" sEEK_END :: CInt