Fix FD changes on Windows
[ghc.git] / libraries / base / 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_' fun h m act =
161 block $ do
162 h_ <- takeMVar m
163 checkBufferInvariants h_
164 v <- catchException (act h_)
165 (\ err -> putMVar m h_ >>
166 case err of
167 IOException ex -> ioError (augmentIOError ex fun h)
168 _ -> throw err)
169 checkBufferInvariants h_
170 putMVar m h_
171 return v
172
173 withAllHandles__ :: String -> Handle -> (Handle__ -> IO Handle__) -> IO ()
174 withAllHandles__ fun h@(FileHandle _ m) act = withHandle__' fun h m act
175 withAllHandles__ fun h@(DuplexHandle _ r w) act = do
176 withHandle__' fun h r act
177 withHandle__' fun h w act
178
179 withHandle__' fun h m act =
180 block $ do
181 h_ <- takeMVar m
182 checkBufferInvariants h_
183 h' <- catchException (act h_)
184 (\ err -> putMVar m h_ >>
185 case err of
186 IOException ex -> ioError (augmentIOError ex fun h)
187 _ -> throw err)
188 checkBufferInvariants h'
189 putMVar m h'
190 return ()
191
192 augmentIOError (IOError _ iot _ str fp) fun h
193 = IOError (Just h) iot fun str filepath
194 where filepath
195 | Just _ <- fp = fp
196 | otherwise = case h of
197 FileHandle fp _ -> Just fp
198 DuplexHandle fp _ _ -> Just fp
199
200 -- ---------------------------------------------------------------------------
201 -- Wrapper for write operations.
202
203 wantWritableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
204 wantWritableHandle fun h@(FileHandle _ m) act
205 = wantWritableHandle' fun h m act
206 wantWritableHandle fun h@(DuplexHandle _ _ m) act
207 = wantWritableHandle' fun h m act
208 -- ToDo: in the Duplex case, we don't need to checkWritableHandle
209
210 wantWritableHandle'
211 :: String -> Handle -> MVar Handle__
212 -> (Handle__ -> IO a) -> IO a
213 wantWritableHandle' fun h m act
214 = withHandle_' fun h m (checkWritableHandle act)
215
216 checkWritableHandle act handle_
217 = case haType handle_ of
218 ClosedHandle -> ioe_closedHandle
219 SemiClosedHandle -> ioe_closedHandle
220 ReadHandle -> ioe_notWritable
221 ReadWriteHandle -> do
222 let ref = haBuffer handle_
223 buf <- readIORef ref
224 new_buf <-
225 if not (bufferIsWritable buf)
226 then do b <- flushReadBuffer (haFD handle_) buf
227 return b{ bufState=WriteBuffer }
228 else return buf
229 writeIORef ref new_buf
230 act handle_
231 _other -> act handle_
232
233 -- ---------------------------------------------------------------------------
234 -- Wrapper for read operations.
235
236 wantReadableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
237 wantReadableHandle fun h@(FileHandle _ m) act
238 = wantReadableHandle' fun h m act
239 wantReadableHandle fun h@(DuplexHandle _ m _) act
240 = wantReadableHandle' fun h m act
241 -- ToDo: in the Duplex case, we don't need to checkReadableHandle
242
243 wantReadableHandle'
244 :: String -> Handle -> MVar Handle__
245 -> (Handle__ -> IO a) -> IO a
246 wantReadableHandle' fun h m act
247 = withHandle_' fun h m (checkReadableHandle act)
248
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)
271 wantSeekableHandle fun h@(FileHandle _ m) act =
272 withHandle_' fun h m (checkSeekableHandle act)
273
274 checkSeekableHandle act handle_ =
275 case haType handle_ of
276 ClosedHandle -> ioe_closedHandle
277 SemiClosedHandle -> ioe_closedHandle
278 AppendHandle -> ioe_notSeekable
279 _ | haIsBin handle_ || tEXT_MODE_SEEK_ALLOWED -> act handle_
280 | otherwise -> ioe_notSeekable_notBin
281
282 -- -----------------------------------------------------------------------------
283 -- Handy IOErrors
284
285 ioe_closedHandle, ioe_EOF,
286 ioe_notReadable, ioe_notWritable,
287 ioe_notSeekable, ioe_notSeekable_notBin :: IO a
288
289 ioe_closedHandle = ioException
290 (IOError Nothing IllegalOperation ""
291 "handle is closed" Nothing)
292 ioe_EOF = ioException
293 (IOError Nothing EOF "" "" Nothing)
294 ioe_notReadable = ioException
295 (IOError Nothing IllegalOperation ""
296 "handle is not open for reading" Nothing)
297 ioe_notWritable = ioException
298 (IOError Nothing IllegalOperation ""
299 "handle is not open for writing" Nothing)
300 ioe_notSeekable = ioException
301 (IOError Nothing IllegalOperation ""
302 "handle is not seekable" Nothing)
303 ioe_notSeekable_notBin = ioException
304 (IOError Nothing IllegalOperation ""
305 "seek operations on text-mode handles are not allowed on this platform"
306 Nothing)
307
308 ioe_finalizedHandle fp = throw (IOException
309 (IOError Nothing IllegalOperation ""
310 "handle is finalized" (Just fp)))
311
312 ioe_bufsiz :: Int -> IO a
313 ioe_bufsiz n = ioException
314 (IOError Nothing InvalidArgument "hSetBuffering"
315 ("illegal buffer size " ++ showsPrec 9 n []) Nothing)
316 -- 9 => should be parens'ified.
317
318 -- -----------------------------------------------------------------------------
319 -- Handle Finalizers
320
321 -- For a duplex handle, we arrange that the read side points to the write side
322 -- (and hence keeps it alive if the read side is alive). This is done by
323 -- having the haOtherSide field of the read side point to the read side.
324 -- The finalizer is then placed on the write side, and the handle only gets
325 -- finalized once, when both sides are no longer required.
326
327 -- NOTE about finalized handles: It's possible that a handle can be
328 -- finalized and then we try to use it later, for example if the
329 -- handle is referenced from another finalizer, or from a thread that
330 -- has become unreferenced and then resurrected (arguably in the
331 -- latter case we shouldn't finalize the Handle...). Anyway,
332 -- we try to emit a helpful message which is better than nothing.
333
334 stdHandleFinalizer :: FilePath -> MVar Handle__ -> IO ()
335 stdHandleFinalizer fp m = do
336 h_ <- takeMVar m
337 flushWriteBufferOnly h_
338 putMVar m (ioe_finalizedHandle fp)
339
340 handleFinalizer :: FilePath -> MVar Handle__ -> IO ()
341 handleFinalizer fp m = do
342 handle_ <- takeMVar m
343 case haType handle_ of
344 ClosedHandle -> return ()
345 _ -> do flushWriteBufferOnly handle_ `catchException` \_ -> return ()
346 -- ignore errors and async exceptions, and close the
347 -- descriptor anyway...
348 hClose_handle_ handle_
349 return ()
350 putMVar m (ioe_finalizedHandle fp)
351
352 -- ---------------------------------------------------------------------------
353 -- Grimy buffer operations
354
355 #ifdef DEBUG
356 checkBufferInvariants h_ = do
357 let ref = haBuffer h_
358 Buffer{ bufWPtr=w, bufRPtr=r, bufSize=size, bufState=state } <- readIORef ref
359 if not (
360 size > 0
361 && r <= w
362 && w <= size
363 && ( r /= w || (r == 0 && w == 0) )
364 && ( state /= WriteBuffer || r == 0 )
365 && ( state /= WriteBuffer || w < size ) -- write buffer is never full
366 )
367 then error "buffer invariant violation"
368 else return ()
369 #else
370 checkBufferInvariants h_ = return ()
371 #endif
372
373 newEmptyBuffer :: RawBuffer -> BufferState -> Int -> Buffer
374 newEmptyBuffer b state size
375 = Buffer{ bufBuf=b, bufRPtr=0, bufWPtr=0, bufSize=size, bufState=state }
376
377 allocateBuffer :: Int -> BufferState -> IO Buffer
378 allocateBuffer sz@(I# size) state = IO $ \s ->
379 #ifdef mingw32_HOST_OS
380 -- To implement asynchronous I/O under Win32, we have to pass
381 -- buffer references to external threads that handles the
382 -- filling/emptying of their contents. Hence, the buffer cannot
383 -- be moved around by the GC.
384 case newPinnedByteArray# size s of { (# s, b #) ->
385 #else
386 case newByteArray# size s of { (# s, b #) ->
387 #endif
388 (# s, newEmptyBuffer b state sz #) }
389
390 writeCharIntoBuffer :: RawBuffer -> Int -> Char -> IO Int
391 writeCharIntoBuffer slab (I# off) (C# c)
392 = IO $ \s -> case writeCharArray# slab off c s of
393 s -> (# s, I# (off +# 1#) #)
394
395 readCharFromBuffer :: RawBuffer -> Int -> IO (Char, Int)
396 readCharFromBuffer slab (I# off)
397 = IO $ \s -> case readCharArray# slab off s of
398 (# s, c #) -> (# s, (C# c, I# (off +# 1#)) #)
399
400 getBuffer :: FD -> BufferState -> IO (IORef Buffer, BufferMode)
401 getBuffer fd state = do
402 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE state
403 ioref <- newIORef buffer
404 is_tty <- fdIsTTY fd
405
406 let buffer_mode
407 | is_tty = LineBuffering
408 | otherwise = BlockBuffering Nothing
409
410 return (ioref, buffer_mode)
411
412 mkUnBuffer :: IO (IORef Buffer)
413 mkUnBuffer = do
414 buffer <- allocateBuffer 1 ReadBuffer
415 newIORef buffer
416
417 -- flushWriteBufferOnly flushes the buffer iff it contains pending write data.
418 flushWriteBufferOnly :: Handle__ -> IO ()
419 flushWriteBufferOnly h_ = do
420 let fd = haFD h_
421 ref = haBuffer h_
422 buf <- readIORef ref
423 new_buf <- if bufferIsWritable buf
424 then flushWriteBuffer fd (haIsStream h_) buf
425 else return buf
426 writeIORef ref new_buf
427
428 -- flushBuffer syncs the file with the buffer, including moving the
429 -- file pointer backwards in the case of a read buffer.
430 flushBuffer :: Handle__ -> IO ()
431 flushBuffer h_ = do
432 let ref = haBuffer h_
433 buf <- readIORef ref
434
435 flushed_buf <-
436 case bufState buf of
437 ReadBuffer -> flushReadBuffer (haFD h_) buf
438 WriteBuffer -> flushWriteBuffer (haFD h_) (haIsStream h_) buf
439
440 writeIORef ref flushed_buf
441
442 -- When flushing a read buffer, we seek backwards by the number of
443 -- characters in the buffer. The file descriptor must therefore be
444 -- seekable: attempting to flush the read buffer on an unseekable
445 -- handle is not allowed.
446
447 flushReadBuffer :: FD -> Buffer -> IO Buffer
448 flushReadBuffer fd buf
449 | bufferEmpty buf = return buf
450 | otherwise = do
451 let off = negate (bufWPtr buf - bufRPtr buf)
452 # ifdef DEBUG_DUMP
453 puts ("flushReadBuffer: new file offset = " ++ show off ++ "\n")
454 # endif
455 throwErrnoIfMinus1Retry "flushReadBuffer"
456 (c_lseek fd (fromIntegral off) sEEK_CUR)
457 return buf{ bufWPtr=0, bufRPtr=0 }
458
459 flushWriteBuffer :: FD -> Bool -> Buffer -> IO Buffer
460 flushWriteBuffer fd is_stream buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w } =
461 seq fd $ do -- strictness hack
462 let bytes = w - r
463 #ifdef DEBUG_DUMP
464 puts ("flushWriteBuffer, fd=" ++ show fd ++ ", bytes=" ++ show bytes ++ "\n")
465 #endif
466 if bytes == 0
467 then return (buf{ bufRPtr=0, bufWPtr=0 })
468 else do
469 res <- writeRawBuffer "flushWriteBuffer" fd is_stream b
470 (fromIntegral r) (fromIntegral bytes)
471 let res' = fromIntegral res
472 if res' < bytes
473 then flushWriteBuffer fd is_stream (buf{ bufRPtr = r + res' })
474 else return buf{ bufRPtr=0, bufWPtr=0 }
475
476 fillReadBuffer :: FD -> Bool -> Bool -> Buffer -> IO Buffer
477 fillReadBuffer fd is_line is_stream
478 buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w, bufSize=size } =
479 -- buffer better be empty:
480 assert (r == 0 && w == 0) $ do
481 fillReadBufferLoop fd is_line is_stream buf b w size
482
483 -- For a line buffer, we just get the first chunk of data to arrive,
484 -- and don't wait for the whole buffer to be full (but we *do* wait
485 -- until some data arrives). This isn't really line buffering, but it
486 -- appears to be what GHC has done for a long time, and I suspect it
487 -- is more useful than line buffering in most cases.
488
489 fillReadBufferLoop fd is_line is_stream buf b w size = do
490 let bytes = size - w
491 if bytes == 0 -- buffer full?
492 then return buf{ bufRPtr=0, bufWPtr=w }
493 else do
494 #ifdef DEBUG_DUMP
495 puts ("fillReadBufferLoop: bytes = " ++ show bytes ++ "\n")
496 #endif
497 res <- readRawBuffer "fillReadBuffer" fd is_stream b
498 (fromIntegral w) (fromIntegral bytes)
499 let res' = fromIntegral res
500 #ifdef DEBUG_DUMP
501 puts ("fillReadBufferLoop: res' = " ++ show res' ++ "\n")
502 #endif
503 if res' == 0
504 then if w == 0
505 then ioe_EOF
506 else return buf{ bufRPtr=0, bufWPtr=w }
507 else if res' < bytes && not is_line
508 then fillReadBufferLoop fd is_line is_stream buf b (w+res') size
509 else return buf{ bufRPtr=0, bufWPtr=w+res' }
510
511
512 fillReadBufferWithoutBlocking :: FD -> Bool -> Buffer -> IO Buffer
513 fillReadBufferWithoutBlocking fd is_stream
514 buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w, bufSize=size } =
515 -- buffer better be empty:
516 assert (r == 0 && w == 0) $ do
517 #ifdef DEBUG_DUMP
518 puts ("fillReadBufferLoopNoBlock: bytes = " ++ show size ++ "\n")
519 #endif
520 res <- readRawBufferNoBlock "fillReadBuffer" fd is_stream b
521 0 (fromIntegral size)
522 let res' = fromIntegral res
523 #ifdef DEBUG_DUMP
524 puts ("fillReadBufferLoopNoBlock: res' = " ++ show res' ++ "\n")
525 #endif
526 return buf{ bufRPtr=0, bufWPtr=res' }
527
528 -- Low level routines for reading/writing to (raw)buffers:
529
530 #ifndef mingw32_HOST_OS
531 readRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
532 readRawBuffer loc fd is_stream buf off len =
533 throwErrnoIfMinus1RetryMayBlock loc
534 (read_rawBuffer fd buf off len)
535 (threadWaitRead (fromIntegral fd))
536
537 readRawBufferNoBlock :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
538 readRawBufferNoBlock loc fd is_stream buf off len =
539 throwErrnoIfMinus1RetryOnBlock loc
540 (read_rawBuffer fd buf off len)
541 (return 0)
542
543 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
544 readRawBufferPtr loc fd is_stream buf off len =
545 throwErrnoIfMinus1RetryMayBlock loc
546 (read_off fd buf off len)
547 (threadWaitRead (fromIntegral fd))
548
549 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
550 writeRawBuffer loc fd is_stream buf off len =
551 throwErrnoIfMinus1RetryMayBlock loc
552 (write_rawBuffer fd buf off len)
553 (threadWaitWrite (fromIntegral fd))
554
555 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
556 writeRawBufferPtr loc fd is_stream buf off len =
557 throwErrnoIfMinus1RetryMayBlock loc
558 (write_off fd buf off len)
559 (threadWaitWrite (fromIntegral fd))
560
561 foreign import ccall unsafe "__hscore_PrelHandle_read"
562 read_rawBuffer :: FD -> RawBuffer -> Int -> CInt -> IO CInt
563
564 foreign import ccall unsafe "__hscore_PrelHandle_read"
565 read_off :: FD -> Ptr CChar -> Int -> CInt -> IO CInt
566
567 foreign import ccall unsafe "__hscore_PrelHandle_write"
568 write_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
569
570 foreign import ccall unsafe "__hscore_PrelHandle_write"
571 write_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
572
573 #else /* mingw32_HOST_OS.... */
574
575 readRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
576 readRawBuffer loc fd is_stream buf off len
577 | threaded = blockingReadRawBuffer loc fd is_stream buf off len
578 | otherwise = asyncReadRawBuffer loc fd is_stream buf off len
579
580 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
581 readRawBufferPtr loc fd is_stream buf off len
582 | threaded = blockingReadRawBufferPtr loc fd is_stream buf off len
583 | otherwise = asyncReadRawBufferPtr loc fd is_stream buf off len
584
585 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
586 writeRawBuffer loc fd is_stream buf off len
587 | threaded = blockingWriteRawBuffer loc fd is_stream buf off len
588 | otherwise = asyncWriteRawBuffer loc fd is_stream buf off len
589
590 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
591 writeRawBufferPtr loc fd is_stream buf off len
592 | threaded = blockingWriteRawBufferPtr loc fd is_stream buf off len
593 | otherwise = asyncWriteRawBufferPtr loc fd is_stream buf off len
594
595 -- ToDo: we don't have a non-blocking primitve read on Win32
596 readRawBufferNoBlock :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
597 readRawBufferNoBlock = readRawBuffer
598
599 -- Async versions of the read/write primitives, for the non-threaded RTS
600
601 asyncReadRawBuffer loc fd is_stream buf off len = do
602 (l, rc) <- asyncReadBA (fromIntegral fd) (if is_stream then 1 else 0)
603 (fromIntegral len) off buf
604 if l == (-1)
605 then
606 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
607 else return (fromIntegral l)
608
609 asyncReadRawBufferPtr loc fd is_stream buf off len = do
610 (l, rc) <- asyncRead (fromIntegral fd) (if is_stream then 1 else 0)
611 (fromIntegral len) (buf `plusPtr` off)
612 if l == (-1)
613 then
614 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
615 else return (fromIntegral l)
616
617 asyncWriteRawBuffer loc fd is_stream buf off len = do
618 (l, rc) <- asyncWriteBA (fromIntegral fd) (if is_stream then 1 else 0)
619 (fromIntegral len) off buf
620 if l == (-1)
621 then
622 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
623 else return (fromIntegral l)
624
625 asyncWriteRawBufferPtr loc fd is_stream buf off len = do
626 (l, rc) <- asyncWrite (fromIntegral fd) (if is_stream then 1 else 0)
627 (fromIntegral len) (buf `plusPtr` off)
628 if l == (-1)
629 then
630 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
631 else return (fromIntegral l)
632
633 -- Blocking versions of the read/write primitives, for the threaded RTS
634
635 blockingReadRawBuffer loc fd True buf off len =
636 throwErrnoIfMinus1Retry loc $
637 recv_rawBuffer fd buf off len
638 blockingReadRawBuffer loc fd False buf off len =
639 throwErrnoIfMinus1Retry loc $
640 read_rawBuffer fd buf off len
641
642 blockingReadRawBufferPtr loc fd True buf off len =
643 throwErrnoIfMinus1Retry loc $
644 recv_off fd buf off len
645 blockingReadRawBufferPtr loc fd False buf off len =
646 throwErrnoIfMinus1Retry loc $
647 read_off fd buf off len
648
649 blockingWriteRawBuffer loc fd True buf off len =
650 throwErrnoIfMinus1Retry loc $
651 send_rawBuffer fd buf off len
652 blockingWriteRawBuffer loc fd False buf off len =
653 throwErrnoIfMinus1Retry loc $
654 write_rawBuffer fd buf off len
655
656 blockingWriteRawBufferPtr loc fd True buf off len =
657 throwErrnoIfMinus1Retry loc $
658 send_off fd buf off len
659 blockingWriteRawBufferPtr loc fd False buf off len =
660 throwErrnoIfMinus1Retry loc $
661 write_off fd buf off len
662
663 -- NOTE: "safe" versions of the read/write calls for use by the threaded RTS.
664 -- These calls may block, but that's ok.
665
666 foreign import ccall safe "__hscore_PrelHandle_read"
667 read_rawBuffer :: FD -> RawBuffer -> Int -> CInt -> IO CInt
668
669 foreign import ccall safe "__hscore_PrelHandle_read"
670 read_off :: FD -> Ptr CChar -> Int -> CInt -> IO CInt
671
672 foreign import ccall safe "__hscore_PrelHandle_write"
673 write_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
674
675 foreign import ccall safe "__hscore_PrelHandle_write"
676 write_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
677
678 foreign import ccall safe "__hscore_PrelHandle_recv"
679 recv_rawBuffer :: FD -> RawBuffer -> Int -> CInt -> IO CInt
680
681 foreign import ccall safe "__hscore_PrelHandle_recv"
682 recv_off :: FD -> Ptr CChar -> Int -> CInt -> IO CInt
683
684 foreign import ccall safe "__hscore_PrelHandle_send"
685 send_rawBuffer :: CInt -> RawBuffer -> Int -> CInt -> IO CInt
686
687 foreign import ccall safe "__hscore_PrelHandle_send"
688 send_off :: CInt -> Ptr CChar -> Int -> CInt -> IO CInt
689
690 foreign import ccall "rtsSupportsBoundThreads" threaded :: Bool
691 #endif
692
693 -- ---------------------------------------------------------------------------
694 -- Standard Handles
695
696 -- Three handles are allocated during program initialisation. The first
697 -- two manage input or output from the Haskell program's standard input
698 -- or output channel respectively. The third manages output to the
699 -- standard error channel. These handles are initially open.
700
701 fd_stdin = 0 :: FD
702 fd_stdout = 1 :: FD
703 fd_stderr = 2 :: FD
704
705 -- | A handle managing input from the Haskell program's standard input channel.
706 stdin :: Handle
707 stdin = unsafePerformIO $ do
708 -- ToDo: acquire lock
709 setNonBlockingFD fd_stdin
710 (buf, bmode) <- getBuffer fd_stdin ReadBuffer
711 mkStdHandle fd_stdin "<stdin>" ReadHandle buf bmode
712
713 -- | A handle managing output to the Haskell program's standard output channel.
714 stdout :: Handle
715 stdout = unsafePerformIO $ do
716 -- ToDo: acquire lock
717 -- We don't set non-blocking mode on stdout or sterr, because
718 -- some shells don't recover properly.
719 -- setNonBlockingFD fd_stdout
720 (buf, bmode) <- getBuffer fd_stdout WriteBuffer
721 mkStdHandle fd_stdout "<stdout>" WriteHandle buf bmode
722
723 -- | A handle managing output to the Haskell program's standard error channel.
724 stderr :: Handle
725 stderr = unsafePerformIO $ do
726 -- ToDo: acquire lock
727 -- We don't set non-blocking mode on stdout or sterr, because
728 -- some shells don't recover properly.
729 -- setNonBlockingFD fd_stderr
730 buf <- mkUnBuffer
731 mkStdHandle fd_stderr "<stderr>" WriteHandle buf NoBuffering
732
733 -- ---------------------------------------------------------------------------
734 -- Opening and Closing Files
735
736 addFilePathToIOError fun fp (IOError h iot _ str _)
737 = IOError h iot fun str (Just fp)
738
739 -- | Computation 'openFile' @file mode@ allocates and returns a new, open
740 -- handle to manage the file @file@. It manages input if @mode@
741 -- is 'ReadMode', output if @mode@ is 'WriteMode' or 'AppendMode',
742 -- and both input and output if mode is 'ReadWriteMode'.
743 --
744 -- If the file does not exist and it is opened for output, it should be
745 -- created as a new file. If @mode@ is 'WriteMode' and the file
746 -- already exists, then it should be truncated to zero length.
747 -- Some operating systems delete empty files, so there is no guarantee
748 -- that the file will exist following an 'openFile' with @mode@
749 -- 'WriteMode' unless it is subsequently written to successfully.
750 -- The handle is positioned at the end of the file if @mode@ is
751 -- 'AppendMode', and otherwise at the beginning (in which case its
752 -- internal position is 0).
753 -- The initial buffer mode is implementation-dependent.
754 --
755 -- This operation may fail with:
756 --
757 -- * 'isAlreadyInUseError' if the file is already open and cannot be reopened;
758 --
759 -- * 'isDoesNotExistError' if the file does not exist; or
760 --
761 -- * 'isPermissionError' if the user does not have permission to open the file.
762 --
763 -- Note: if you will be working with files containing binary data, you'll want to
764 -- be using 'openBinaryFile'.
765 openFile :: FilePath -> IOMode -> IO Handle
766 openFile fp im =
767 catch
768 (openFile' fp im dEFAULT_OPEN_IN_BINARY_MODE)
769 (\e -> ioError (addFilePathToIOError "openFile" fp e))
770
771 -- | Like 'openFile', but open the file in binary mode.
772 -- On Windows, reading a file in text mode (which is the default)
773 -- will translate CRLF to LF, and writing will translate LF to CRLF.
774 -- This is usually what you want with text files. With binary files
775 -- this is undesirable; also, as usual under Microsoft operating systems,
776 -- text mode treats control-Z as EOF. Binary mode turns off all special
777 -- treatment of end-of-line and end-of-file characters.
778 -- (See also 'hSetBinaryMode'.)
779
780 openBinaryFile :: FilePath -> IOMode -> IO Handle
781 openBinaryFile fp m =
782 catch
783 (openFile' fp m True)
784 (\e -> ioError (addFilePathToIOError "openBinaryFile" fp e))
785
786 openFile' filepath mode binary =
787 withCString filepath $ \ f ->
788
789 let
790 oflags1 = case mode of
791 ReadMode -> read_flags
792 #ifdef mingw32_HOST_OS
793 WriteMode -> write_flags .|. o_TRUNC
794 #else
795 WriteMode -> write_flags
796 #endif
797 ReadWriteMode -> rw_flags
798 AppendMode -> append_flags
799
800 binary_flags
801 | binary = o_BINARY
802 | otherwise = 0
803
804 oflags = oflags1 .|. binary_flags
805 in do
806
807 -- the old implementation had a complicated series of three opens,
808 -- which is perhaps because we have to be careful not to open
809 -- directories. However, the man pages I've read say that open()
810 -- always returns EISDIR if the file is a directory and was opened
811 -- for writing, so I think we're ok with a single open() here...
812 fd <- throwErrnoIfMinus1Retry "openFile"
813 (c_open f (fromIntegral oflags) 0o666)
814
815 fd_type <- fdType fd
816
817 h <- openFd fd (Just fd_type) False filepath mode binary
818 `catchException` \e -> do c_close fd; throw e
819 -- NB. don't forget to close the FD if openFd fails, otherwise
820 -- this FD leaks.
821 -- ASSERT: if we just created the file, then openFd won't fail
822 -- (so we don't need to worry about removing the newly created file
823 -- in the event of an error).
824
825 #ifndef mingw32_HOST_OS
826 -- we want to truncate() if this is an open in WriteMode, but only
827 -- if the target is a RegularFile. ftruncate() fails on special files
828 -- like /dev/null.
829 if mode == WriteMode && fd_type == RegularFile
830 then throwErrnoIf (/=0) "openFile"
831 (c_ftruncate fd 0)
832 else return 0
833 #endif
834 return h
835
836
837 -- | The function creates a temporary file in ReadWrite mode.
838 -- The created file isn\'t deleted automatically, so you need to delete it manually.
839 openTempFile :: FilePath -- ^ Directory in which to create the file
840 -> String -- ^ File name template. If the template is \"foo.ext\" then
841 -- the create file will be \"fooXXX.ext\" where XXX is some
842 -- random number.
843 -> IO (FilePath, Handle)
844 openTempFile tmp_dir template = openTempFile' "openTempFile" tmp_dir template dEFAULT_OPEN_IN_BINARY_MODE
845
846 -- | Like 'openTempFile', but opens the file in binary mode. See 'openBinaryFile' for more comments.
847 openBinaryTempFile :: FilePath -> String -> IO (FilePath, Handle)
848 openBinaryTempFile tmp_dir template = openTempFile' "openBinaryTempFile" tmp_dir template True
849
850 openTempFile' :: String -> FilePath -> String -> Bool -> IO (FilePath, Handle)
851 openTempFile' loc tmp_dir template binary = do
852 pid <- c_getpid
853 findTempName pid
854 where
855 (prefix,suffix) = break (=='.') template
856
857 oflags1 = rw_flags .|. o_EXCL
858
859 binary_flags
860 | binary = o_BINARY
861 | otherwise = 0
862
863 oflags = oflags1 .|. binary_flags
864
865 findTempName x = do
866 fd <- withCString filepath $ \ f ->
867 c_open f oflags 0o666
868 if fd < 0
869 then do
870 errno <- getErrno
871 if errno == eEXIST
872 then findTempName (x+1)
873 else ioError (errnoToIOError loc errno Nothing (Just tmp_dir))
874 else do
875 h <- openFd fd Nothing False filepath ReadWriteMode True
876 `catchException` \e -> do c_close fd; throw e
877 return (filepath, h)
878 where
879 filename = prefix ++ show x ++ suffix
880 filepath = tmp_dir `joinFileName` filename
881
882
883 std_flags = o_NONBLOCK .|. o_NOCTTY
884 output_flags = std_flags .|. o_CREAT
885 read_flags = std_flags .|. o_RDONLY
886 write_flags = output_flags .|. o_WRONLY
887 rw_flags = output_flags .|. o_RDWR
888 append_flags = write_flags .|. o_APPEND
889
890 -- ---------------------------------------------------------------------------
891 -- openFd
892
893 openFd :: FD -> Maybe FDType -> Bool -> FilePath -> IOMode -> Bool -> IO Handle
894 openFd fd mb_fd_type is_socket filepath mode binary = do
895 -- turn on non-blocking mode
896 setNonBlockingFD fd
897
898 let (ha_type, write) =
899 case mode of
900 ReadMode -> ( ReadHandle, False )
901 WriteMode -> ( WriteHandle, True )
902 ReadWriteMode -> ( ReadWriteHandle, True )
903 AppendMode -> ( AppendHandle, True )
904
905 -- open() won't tell us if it was a directory if we only opened for
906 -- reading, so check again.
907 fd_type <-
908 case mb_fd_type of
909 Just x -> return x
910 Nothing -> fdType fd
911
912 case fd_type of
913 Directory ->
914 ioException (IOError Nothing InappropriateType "openFile"
915 "is a directory" Nothing)
916
917 -- regular files need to be locked
918 RegularFile -> do
919 #ifndef mingw32_HOST_OS
920 r <- lockFile fd (fromBool write) 1{-exclusive-}
921 when (r == -1) $
922 ioException (IOError Nothing ResourceBusy "openFile"
923 "file is locked" Nothing)
924 #endif
925 mkFileHandle fd is_socket filepath ha_type binary
926
927 Stream
928 -- only *Streams* can be DuplexHandles. Other read/write
929 -- Handles must share a buffer.
930 | ReadWriteHandle <- ha_type ->
931 mkDuplexHandle fd is_socket filepath binary
932 | otherwise ->
933 mkFileHandle fd is_socket filepath ha_type binary
934
935 RawDevice ->
936 mkFileHandle fd is_socket filepath ha_type binary
937
938 fdToHandle :: FD -> IO Handle
939 fdToHandle fd = do
940 mode <- fdGetMode fd
941 let fd_str = "<file descriptor: " ++ show fd ++ ">"
942 openFd fd Nothing False{-XXX!-} fd_str mode True{-bin mode-}
943
944
945 #ifndef mingw32_HOST_OS
946 foreign import ccall unsafe "lockFile"
947 lockFile :: CInt -> CInt -> CInt -> IO CInt
948
949 foreign import ccall unsafe "unlockFile"
950 unlockFile :: CInt -> IO CInt
951 #endif
952
953 mkStdHandle :: FD -> FilePath -> HandleType -> IORef Buffer -> BufferMode
954 -> IO Handle
955 mkStdHandle fd filepath ha_type buf bmode = do
956 spares <- newIORef BufferListNil
957 newFileHandle filepath (stdHandleFinalizer filepath)
958 (Handle__ { haFD = fd,
959 haType = ha_type,
960 haIsBin = dEFAULT_OPEN_IN_BINARY_MODE,
961 haIsStream = False,
962 haBufferMode = bmode,
963 haBuffer = buf,
964 haBuffers = spares,
965 haOtherSide = Nothing
966 })
967
968 mkFileHandle :: FD -> Bool -> FilePath -> HandleType -> Bool -> IO Handle
969 mkFileHandle fd is_stream filepath ha_type binary = do
970 (buf, bmode) <- getBuffer fd (initBufferState ha_type)
971
972 #ifdef mingw32_HOST_OS
973 -- On Windows, if this is a read/write handle and we are in text mode,
974 -- turn off buffering. We don't correctly handle the case of switching
975 -- from read mode to write mode on a buffered text-mode handle, see bug
976 -- \#679.
977 bmode <- case ha_type of
978 ReadWriteHandle | not binary -> return NoBuffering
979 _other -> return bmode
980 #endif
981
982 spares <- newIORef BufferListNil
983 newFileHandle filepath (handleFinalizer filepath)
984 (Handle__ { haFD = fd,
985 haType = ha_type,
986 haIsBin = binary,
987 haIsStream = is_stream,
988 haBufferMode = bmode,
989 haBuffer = buf,
990 haBuffers = spares,
991 haOtherSide = Nothing
992 })
993
994 mkDuplexHandle :: FD -> Bool -> FilePath -> Bool -> IO Handle
995 mkDuplexHandle fd is_stream filepath binary = do
996 (w_buf, w_bmode) <- getBuffer fd WriteBuffer
997 w_spares <- newIORef BufferListNil
998 let w_handle_ =
999 Handle__ { haFD = fd,
1000 haType = WriteHandle,
1001 haIsBin = binary,
1002 haIsStream = is_stream,
1003 haBufferMode = w_bmode,
1004 haBuffer = w_buf,
1005 haBuffers = w_spares,
1006 haOtherSide = Nothing
1007 }
1008 write_side <- newMVar w_handle_
1009
1010 (r_buf, r_bmode) <- getBuffer fd ReadBuffer
1011 r_spares <- newIORef BufferListNil
1012 let r_handle_ =
1013 Handle__ { haFD = fd,
1014 haType = ReadHandle,
1015 haIsBin = binary,
1016 haIsStream = is_stream,
1017 haBufferMode = r_bmode,
1018 haBuffer = r_buf,
1019 haBuffers = r_spares,
1020 haOtherSide = Just write_side
1021 }
1022 read_side <- newMVar r_handle_
1023
1024 addMVarFinalizer write_side (handleFinalizer filepath write_side)
1025 return (DuplexHandle filepath read_side write_side)
1026
1027
1028 initBufferState ReadHandle = ReadBuffer
1029 initBufferState _ = WriteBuffer
1030
1031 -- ---------------------------------------------------------------------------
1032 -- Closing a handle
1033
1034 -- | Computation 'hClose' @hdl@ makes handle @hdl@ closed. Before the
1035 -- computation finishes, if @hdl@ is writable its buffer is flushed as
1036 -- for 'hFlush'.
1037 -- Performing 'hClose' on a handle that has already been closed has no effect;
1038 -- doing so not an error. All other operations on a closed handle will fail.
1039 -- If 'hClose' fails for any reason, any further operations (apart from
1040 -- 'hClose') on the handle will still fail as if @hdl@ had been successfully
1041 -- closed.
1042
1043 hClose :: Handle -> IO ()
1044 hClose h@(FileHandle _ m) = hClose' h m
1045 hClose h@(DuplexHandle _ r w) = hClose' h w >> hClose' h r
1046
1047 hClose' h m = withHandle__' "hClose" h m $ hClose_help
1048
1049 -- hClose_help is also called by lazyRead (in PrelIO) when EOF is read
1050 -- or an IO error occurs on a lazy stream. The semi-closed Handle is
1051 -- then closed immediately. We have to be careful with DuplexHandles
1052 -- though: we have to leave the closing to the finalizer in that case,
1053 -- because the write side may still be in use.
1054 hClose_help :: Handle__ -> IO Handle__
1055 hClose_help handle_ =
1056 case haType handle_ of
1057 ClosedHandle -> return handle_
1058 _ -> do flushWriteBufferOnly handle_ -- interruptible
1059 hClose_handle_ handle_
1060
1061 hClose_handle_ handle_ = do
1062 let fd = haFD handle_
1063
1064 -- close the file descriptor, but not when this is the read
1065 -- side of a duplex handle.
1066 case haOtherSide handle_ of
1067 Nothing ->
1068 throwErrnoIfMinus1Retry_ "hClose"
1069 #ifdef mingw32_HOST_OS
1070 (closeFd (haIsStream handle_) fd)
1071 #else
1072 (c_close fd)
1073 #endif
1074 Just _ -> return ()
1075
1076 -- free the spare buffers
1077 writeIORef (haBuffers handle_) BufferListNil
1078
1079 #ifndef mingw32_HOST_OS
1080 -- unlock it
1081 unlockFile fd
1082 #endif
1083
1084 -- we must set the fd to -1, because the finalizer is going
1085 -- to run eventually and try to close/unlock it.
1086 return (handle_{ haFD = -1,
1087 haType = ClosedHandle
1088 })
1089
1090 -----------------------------------------------------------------------------
1091 -- Detecting and changing the size of a file
1092
1093 -- | For a handle @hdl@ which attached to a physical file,
1094 -- 'hFileSize' @hdl@ returns the size of that file in 8-bit bytes.
1095
1096 hFileSize :: Handle -> IO Integer
1097 hFileSize handle =
1098 withHandle_ "hFileSize" handle $ \ handle_ -> do
1099 case haType handle_ of
1100 ClosedHandle -> ioe_closedHandle
1101 SemiClosedHandle -> ioe_closedHandle
1102 _ -> do flushWriteBufferOnly handle_
1103 r <- fdFileSize (haFD handle_)
1104 if r /= -1
1105 then return r
1106 else ioException (IOError Nothing InappropriateType "hFileSize"
1107 "not a regular file" Nothing)
1108
1109
1110 -- | 'hSetFileSize' @hdl@ @size@ truncates the physical file with handle @hdl@ to @size@ bytes.
1111
1112 hSetFileSize :: Handle -> Integer -> IO ()
1113 hSetFileSize handle size =
1114 withHandle_ "hSetFileSize" handle $ \ handle_ -> do
1115 case haType handle_ of
1116 ClosedHandle -> ioe_closedHandle
1117 SemiClosedHandle -> ioe_closedHandle
1118 _ -> do flushWriteBufferOnly handle_
1119 throwErrnoIf (/=0) "hSetFileSize"
1120 (c_ftruncate (haFD handle_) (fromIntegral size))
1121 return ()
1122
1123 -- ---------------------------------------------------------------------------
1124 -- Detecting the End of Input
1125
1126 -- | For a readable handle @hdl@, 'hIsEOF' @hdl@ returns
1127 -- 'True' if no further input can be taken from @hdl@ or for a
1128 -- physical file, if the current I\/O position is equal to the length of
1129 -- the file. Otherwise, it returns 'False'.
1130
1131 hIsEOF :: Handle -> IO Bool
1132 hIsEOF handle =
1133 catch
1134 (do hLookAhead handle; return False)
1135 (\e -> if isEOFError e then return True else ioError e)
1136
1137 -- | The computation 'isEOF' is identical to 'hIsEOF',
1138 -- except that it works only on 'stdin'.
1139
1140 isEOF :: IO Bool
1141 isEOF = hIsEOF stdin
1142
1143 -- ---------------------------------------------------------------------------
1144 -- Looking ahead
1145
1146 -- | Computation 'hLookAhead' returns the next character from the handle
1147 -- without removing it from the input buffer, blocking until a character
1148 -- is available.
1149 --
1150 -- This operation may fail with:
1151 --
1152 -- * 'isEOFError' if the end of file has been reached.
1153
1154 hLookAhead :: Handle -> IO Char
1155 hLookAhead handle = do
1156 wantReadableHandle "hLookAhead" handle $ \handle_ -> do
1157 let ref = haBuffer handle_
1158 fd = haFD handle_
1159 is_line = haBufferMode handle_ == LineBuffering
1160 buf <- readIORef ref
1161
1162 -- fill up the read buffer if necessary
1163 new_buf <- if bufferEmpty buf
1164 then fillReadBuffer fd True (haIsStream handle_) buf
1165 else return buf
1166
1167 writeIORef ref new_buf
1168
1169 (c,_) <- readCharFromBuffer (bufBuf buf) (bufRPtr buf)
1170 return c
1171
1172 -- ---------------------------------------------------------------------------
1173 -- Buffering Operations
1174
1175 -- Three kinds of buffering are supported: line-buffering,
1176 -- block-buffering or no-buffering. See GHC.IOBase for definition and
1177 -- further explanation of what the type represent.
1178
1179 -- | Computation 'hSetBuffering' @hdl mode@ sets the mode of buffering for
1180 -- handle @hdl@ on subsequent reads and writes.
1181 --
1182 -- If the buffer mode is changed from 'BlockBuffering' or
1183 -- 'LineBuffering' to 'NoBuffering', then
1184 --
1185 -- * if @hdl@ is writable, the buffer is flushed as for 'hFlush';
1186 --
1187 -- * if @hdl@ is not writable, the contents of the buffer is discarded.
1188 --
1189 -- This operation may fail with:
1190 --
1191 -- * 'isPermissionError' if the handle has already been used for reading
1192 -- or writing and the implementation does not allow the buffering mode
1193 -- to be changed.
1194
1195 hSetBuffering :: Handle -> BufferMode -> IO ()
1196 hSetBuffering handle mode =
1197 withAllHandles__ "hSetBuffering" handle $ \ handle_ -> do
1198 case haType handle_ of
1199 ClosedHandle -> ioe_closedHandle
1200 _ -> do
1201 {- Note:
1202 - we flush the old buffer regardless of whether
1203 the new buffer could fit the contents of the old buffer
1204 or not.
1205 - allow a handle's buffering to change even if IO has
1206 occurred (ANSI C spec. does not allow this, nor did
1207 the previous implementation of IO.hSetBuffering).
1208 - a non-standard extension is to allow the buffering
1209 of semi-closed handles to change [sof 6/98]
1210 -}
1211 flushBuffer handle_
1212
1213 let state = initBufferState (haType handle_)
1214 new_buf <-
1215 case mode of
1216 -- we always have a 1-character read buffer for
1217 -- unbuffered handles: it's needed to
1218 -- support hLookAhead.
1219 NoBuffering -> allocateBuffer 1 ReadBuffer
1220 LineBuffering -> allocateBuffer dEFAULT_BUFFER_SIZE state
1221 BlockBuffering Nothing -> allocateBuffer dEFAULT_BUFFER_SIZE state
1222 BlockBuffering (Just n) | n <= 0 -> ioe_bufsiz n
1223 | otherwise -> allocateBuffer n state
1224 writeIORef (haBuffer handle_) new_buf
1225
1226 -- for input terminals we need to put the terminal into
1227 -- cooked or raw mode depending on the type of buffering.
1228 is_tty <- fdIsTTY (haFD handle_)
1229 when (is_tty && isReadableHandleType (haType handle_)) $
1230 case mode of
1231 #ifndef mingw32_HOST_OS
1232 -- 'raw' mode under win32 is a bit too specialised (and troublesome
1233 -- for most common uses), so simply disable its use here.
1234 NoBuffering -> setCooked (haFD handle_) False
1235 #else
1236 NoBuffering -> return ()
1237 #endif
1238 _ -> setCooked (haFD handle_) True
1239
1240 -- throw away spare buffers, they might be the wrong size
1241 writeIORef (haBuffers handle_) BufferListNil
1242
1243 return (handle_{ haBufferMode = mode })
1244
1245 -- -----------------------------------------------------------------------------
1246 -- hFlush
1247
1248 -- | The action 'hFlush' @hdl@ causes any items buffered for output
1249 -- in handle @hdl@ to be sent immediately to the operating system.
1250 --
1251 -- This operation may fail with:
1252 --
1253 -- * 'isFullError' if the device is full;
1254 --
1255 -- * 'isPermissionError' if a system resource limit would be exceeded.
1256 -- It is unspecified whether the characters in the buffer are discarded
1257 -- or retained under these circumstances.
1258
1259 hFlush :: Handle -> IO ()
1260 hFlush handle =
1261 wantWritableHandle "hFlush" handle $ \ handle_ -> do
1262 buf <- readIORef (haBuffer handle_)
1263 if bufferIsWritable buf && not (bufferEmpty buf)
1264 then do flushed_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
1265 writeIORef (haBuffer handle_) flushed_buf
1266 else return ()
1267
1268
1269 -- -----------------------------------------------------------------------------
1270 -- Repositioning Handles
1271
1272 data HandlePosn = HandlePosn Handle HandlePosition
1273
1274 instance Eq HandlePosn where
1275 (HandlePosn h1 p1) == (HandlePosn h2 p2) = p1==p2 && h1==h2
1276
1277 instance Show HandlePosn where
1278 showsPrec p (HandlePosn h pos) =
1279 showsPrec p h . showString " at position " . shows pos
1280
1281 -- HandlePosition is the Haskell equivalent of POSIX' off_t.
1282 -- We represent it as an Integer on the Haskell side, but
1283 -- cheat slightly in that hGetPosn calls upon a C helper
1284 -- that reports the position back via (merely) an Int.
1285 type HandlePosition = Integer
1286
1287 -- | Computation 'hGetPosn' @hdl@ returns the current I\/O position of
1288 -- @hdl@ as a value of the abstract type 'HandlePosn'.
1289
1290 hGetPosn :: Handle -> IO HandlePosn
1291 hGetPosn handle = do
1292 posn <- hTell handle
1293 return (HandlePosn handle posn)
1294
1295 -- | If a call to 'hGetPosn' @hdl@ returns a position @p@,
1296 -- then computation 'hSetPosn' @p@ sets the position of @hdl@
1297 -- to the position it held at the time of the call to 'hGetPosn'.
1298 --
1299 -- This operation may fail with:
1300 --
1301 -- * 'isPermissionError' if a system resource limit would be exceeded.
1302
1303 hSetPosn :: HandlePosn -> IO ()
1304 hSetPosn (HandlePosn h i) = hSeek h AbsoluteSeek i
1305
1306 -- ---------------------------------------------------------------------------
1307 -- hSeek
1308
1309 -- | A mode that determines the effect of 'hSeek' @hdl mode i@, as follows:
1310 data SeekMode
1311 = AbsoluteSeek -- ^ the position of @hdl@ is set to @i@.
1312 | RelativeSeek -- ^ the position of @hdl@ is set to offset @i@
1313 -- from the current position.
1314 | SeekFromEnd -- ^ the position of @hdl@ is set to offset @i@
1315 -- from the end of the file.
1316 deriving (Eq, Ord, Ix, Enum, Read, Show)
1317
1318 {- Note:
1319 - when seeking using `SeekFromEnd', positive offsets (>=0) means
1320 seeking at or past EOF.
1321
1322 - we possibly deviate from the report on the issue of seeking within
1323 the buffer and whether to flush it or not. The report isn't exactly
1324 clear here.
1325 -}
1326
1327 -- | Computation 'hSeek' @hdl mode i@ sets the position of handle
1328 -- @hdl@ depending on @mode@.
1329 -- The offset @i@ is given in terms of 8-bit bytes.
1330 --
1331 -- If @hdl@ is block- or line-buffered, then seeking to a position which is not
1332 -- in the current buffer will first cause any items in the output buffer to be
1333 -- written to the device, and then cause the input buffer to be discarded.
1334 -- Some handles may not be seekable (see 'hIsSeekable'), or only support a
1335 -- subset of the possible positioning operations (for instance, it may only
1336 -- be possible to seek to the end of a tape, or to a positive offset from
1337 -- the beginning or current position).
1338 -- It is not possible to set a negative I\/O position, or for
1339 -- a physical file, an I\/O position beyond the current end-of-file.
1340 --
1341 -- This operation may fail with:
1342 --
1343 -- * 'isPermissionError' if a system resource limit would be exceeded.
1344
1345 hSeek :: Handle -> SeekMode -> Integer -> IO ()
1346 hSeek handle mode offset =
1347 wantSeekableHandle "hSeek" handle $ \ handle_ -> do
1348 # ifdef DEBUG_DUMP
1349 puts ("hSeek " ++ show (mode,offset) ++ "\n")
1350 # endif
1351 let ref = haBuffer handle_
1352 buf <- readIORef ref
1353 let r = bufRPtr buf
1354 w = bufWPtr buf
1355 fd = haFD handle_
1356
1357 let do_seek =
1358 throwErrnoIfMinus1Retry_ "hSeek"
1359 (c_lseek (haFD handle_) (fromIntegral offset) whence)
1360
1361 whence :: CInt
1362 whence = case mode of
1363 AbsoluteSeek -> sEEK_SET
1364 RelativeSeek -> sEEK_CUR
1365 SeekFromEnd -> sEEK_END
1366
1367 if bufferIsWritable buf
1368 then do new_buf <- flushWriteBuffer fd (haIsStream handle_) buf
1369 writeIORef ref new_buf
1370 do_seek
1371 else do
1372
1373 if mode == RelativeSeek && offset >= 0 && offset < fromIntegral (w - r)
1374 then writeIORef ref buf{ bufRPtr = r + fromIntegral offset }
1375 else do
1376
1377 new_buf <- flushReadBuffer (haFD handle_) buf
1378 writeIORef ref new_buf
1379 do_seek
1380
1381
1382 hTell :: Handle -> IO Integer
1383 hTell handle =
1384 wantSeekableHandle "hGetPosn" handle $ \ handle_ -> do
1385
1386 #if defined(mingw32_HOST_OS)
1387 -- urgh, on Windows we have to worry about \n -> \r\n translation,
1388 -- so we can't easily calculate the file position using the
1389 -- current buffer size. Just flush instead.
1390 flushBuffer handle_
1391 #endif
1392 let fd = haFD handle_
1393 posn <- fromIntegral `liftM`
1394 throwErrnoIfMinus1Retry "hGetPosn"
1395 (c_lseek fd 0 sEEK_CUR)
1396
1397 let ref = haBuffer handle_
1398 buf <- readIORef ref
1399
1400 let real_posn
1401 | bufferIsWritable buf = posn + fromIntegral (bufWPtr buf)
1402 | otherwise = posn - fromIntegral (bufWPtr buf - bufRPtr buf)
1403 # ifdef DEBUG_DUMP
1404 puts ("\nhGetPosn: (fd, posn, real_posn) = " ++ show (fd, posn, real_posn) ++ "\n")
1405 puts (" (bufWPtr, bufRPtr) = " ++ show (bufWPtr buf, bufRPtr buf) ++ "\n")
1406 # endif
1407 return real_posn
1408
1409 -- -----------------------------------------------------------------------------
1410 -- Handle Properties
1411
1412 -- A number of operations return information about the properties of a
1413 -- handle. Each of these operations returns `True' if the handle has
1414 -- the specified property, and `False' otherwise.
1415
1416 hIsOpen :: Handle -> IO Bool
1417 hIsOpen handle =
1418 withHandle_ "hIsOpen" handle $ \ handle_ -> do
1419 case haType handle_ of
1420 ClosedHandle -> return False
1421 SemiClosedHandle -> return False
1422 _ -> return True
1423
1424 hIsClosed :: Handle -> IO Bool
1425 hIsClosed handle =
1426 withHandle_ "hIsClosed" handle $ \ handle_ -> do
1427 case haType handle_ of
1428 ClosedHandle -> return True
1429 _ -> return False
1430
1431 {- not defined, nor exported, but mentioned
1432 here for documentation purposes:
1433
1434 hSemiClosed :: Handle -> IO Bool
1435 hSemiClosed h = do
1436 ho <- hIsOpen h
1437 hc <- hIsClosed h
1438 return (not (ho || hc))
1439 -}
1440
1441 hIsReadable :: Handle -> IO Bool
1442 hIsReadable (DuplexHandle _ _ _) = return True
1443 hIsReadable handle =
1444 withHandle_ "hIsReadable" handle $ \ handle_ -> do
1445 case haType handle_ of
1446 ClosedHandle -> ioe_closedHandle
1447 SemiClosedHandle -> ioe_closedHandle
1448 htype -> return (isReadableHandleType htype)
1449
1450 hIsWritable :: Handle -> IO Bool
1451 hIsWritable (DuplexHandle _ _ _) = return True
1452 hIsWritable handle =
1453 withHandle_ "hIsWritable" handle $ \ handle_ -> do
1454 case haType handle_ of
1455 ClosedHandle -> ioe_closedHandle
1456 SemiClosedHandle -> ioe_closedHandle
1457 htype -> return (isWritableHandleType htype)
1458
1459 -- | Computation 'hGetBuffering' @hdl@ returns the current buffering mode
1460 -- for @hdl@.
1461
1462 hGetBuffering :: Handle -> IO BufferMode
1463 hGetBuffering handle =
1464 withHandle_ "hGetBuffering" handle $ \ handle_ -> do
1465 case haType handle_ of
1466 ClosedHandle -> ioe_closedHandle
1467 _ ->
1468 -- We're being non-standard here, and allow the buffering
1469 -- of a semi-closed handle to be queried. -- sof 6/98
1470 return (haBufferMode handle_) -- could be stricter..
1471
1472 hIsSeekable :: Handle -> IO Bool
1473 hIsSeekable handle =
1474 withHandle_ "hIsSeekable" handle $ \ handle_ -> do
1475 case haType handle_ of
1476 ClosedHandle -> ioe_closedHandle
1477 SemiClosedHandle -> ioe_closedHandle
1478 AppendHandle -> return False
1479 _ -> do t <- fdType (haFD handle_)
1480 return ((t == RegularFile || t == RawDevice)
1481 && (haIsBin handle_ || tEXT_MODE_SEEK_ALLOWED))
1482
1483 -- -----------------------------------------------------------------------------
1484 -- Changing echo status (Non-standard GHC extensions)
1485
1486 -- | Set the echoing status of a handle connected to a terminal.
1487
1488 hSetEcho :: Handle -> Bool -> IO ()
1489 hSetEcho handle on = do
1490 isT <- hIsTerminalDevice handle
1491 if not isT
1492 then return ()
1493 else
1494 withHandle_ "hSetEcho" handle $ \ handle_ -> do
1495 case haType handle_ of
1496 ClosedHandle -> ioe_closedHandle
1497 _ -> setEcho (haFD handle_) on
1498
1499 -- | Get the echoing status of a handle connected to a terminal.
1500
1501 hGetEcho :: Handle -> IO Bool
1502 hGetEcho handle = do
1503 isT <- hIsTerminalDevice handle
1504 if not isT
1505 then return False
1506 else
1507 withHandle_ "hGetEcho" handle $ \ handle_ -> do
1508 case haType handle_ of
1509 ClosedHandle -> ioe_closedHandle
1510 _ -> getEcho (haFD handle_)
1511
1512 -- | Is the handle connected to a terminal?
1513
1514 hIsTerminalDevice :: Handle -> IO Bool
1515 hIsTerminalDevice handle = do
1516 withHandle_ "hIsTerminalDevice" handle $ \ handle_ -> do
1517 case haType handle_ of
1518 ClosedHandle -> ioe_closedHandle
1519 _ -> fdIsTTY (haFD handle_)
1520
1521 -- -----------------------------------------------------------------------------
1522 -- hSetBinaryMode
1523
1524 -- | Select binary mode ('True') or text mode ('False') on a open handle.
1525 -- (See also 'openBinaryFile'.)
1526
1527 hSetBinaryMode :: Handle -> Bool -> IO ()
1528 hSetBinaryMode handle bin =
1529 withAllHandles__ "hSetBinaryMode" handle $ \ handle_ ->
1530 do throwErrnoIfMinus1_ "hSetBinaryMode"
1531 (setmode (haFD handle_) bin)
1532 return handle_{haIsBin=bin}
1533
1534 foreign import ccall unsafe "__hscore_setmode"
1535 setmode :: CInt -> Bool -> IO CInt
1536
1537 -- -----------------------------------------------------------------------------
1538 -- Duplicating a Handle
1539
1540 -- | Returns a duplicate of the original handle, with its own buffer.
1541 -- The two Handles will share a file pointer, however. The original
1542 -- handle's buffer is flushed, including discarding any input data,
1543 -- before the handle is duplicated.
1544
1545 hDuplicate :: Handle -> IO Handle
1546 hDuplicate h@(FileHandle path m) = do
1547 new_h_ <- withHandle' "hDuplicate" h m (dupHandle Nothing)
1548 newFileHandle path (handleFinalizer path) new_h_
1549 hDuplicate h@(DuplexHandle path r w) = do
1550 new_w_ <- withHandle' "hDuplicate" h w (dupHandle Nothing)
1551 new_w <- newMVar new_w_
1552 new_r_ <- withHandle' "hDuplicate" h r (dupHandle (Just new_w))
1553 new_r <- newMVar new_r_
1554 addMVarFinalizer new_w (handleFinalizer path new_w)
1555 return (DuplexHandle path new_r new_w)
1556
1557 dupHandle other_side h_ = do
1558 -- flush the buffer first, so we don't have to copy its contents
1559 flushBuffer h_
1560 new_fd <- throwErrnoIfMinus1 "dupHandle" $
1561 c_dup (haFD h_)
1562 dupHandle_ other_side h_ new_fd
1563
1564 dupHandleTo other_side hto_ h_ = do
1565 flushBuffer h_
1566 -- Windows' dup2 does not return the new descriptor, unlike Unix
1567 throwErrnoIfMinus1 "dupHandleTo" $
1568 c_dup2 (haFD h_) (haFD hto_)
1569 dupHandle_ other_side h_ (haFD hto_)
1570
1571 dupHandle_ :: Maybe (MVar Handle__) -> Handle__ -> FD
1572 -> IO (Handle__, Handle__)
1573 dupHandle_ other_side h_ new_fd = do
1574 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE (initBufferState (haType h_))
1575 ioref <- newIORef buffer
1576 ioref_buffers <- newIORef BufferListNil
1577
1578 let new_handle_ = h_{ haFD = new_fd,
1579 haBuffer = ioref,
1580 haBuffers = ioref_buffers,
1581 haOtherSide = other_side }
1582 return (h_, new_handle_)
1583
1584 -- -----------------------------------------------------------------------------
1585 -- Replacing a Handle
1586
1587 {- |
1588 Makes the second handle a duplicate of the first handle. The second
1589 handle will be closed first, if it is not already.
1590
1591 This can be used to retarget the standard Handles, for example:
1592
1593 > do h <- openFile "mystdout" WriteMode
1594 > hDuplicateTo h stdout
1595 -}
1596
1597 hDuplicateTo :: Handle -> Handle -> IO ()
1598 hDuplicateTo h1@(FileHandle _ m1) h2@(FileHandle _ m2) = do
1599 withHandle__' "hDuplicateTo" h2 m2 $ \h2_ -> do
1600 _ <- hClose_help h2_
1601 withHandle' "hDuplicateTo" h1 m1 (dupHandleTo Nothing h2_)
1602 hDuplicateTo h1@(DuplexHandle _ r1 w1) h2@(DuplexHandle _ r2 w2) = do
1603 withHandle__' "hDuplicateTo" h2 w2 $ \w2_ -> do
1604 _ <- hClose_help w2_
1605 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo Nothing w2_)
1606 withHandle__' "hDuplicateTo" h2 r2 $ \r2_ -> do
1607 _ <- hClose_help r2_
1608 withHandle' "hDuplicateTo" h1 r1 (dupHandleTo (Just w1) r2_)
1609 hDuplicateTo h1 _ =
1610 ioException (IOError (Just h1) IllegalOperation "hDuplicateTo"
1611 "handles are incompatible" Nothing)
1612
1613 -- ---------------------------------------------------------------------------
1614 -- showing Handles.
1615 --
1616 -- | 'hShow' is in the 'IO' monad, and gives more comprehensive output
1617 -- than the (pure) instance of 'Show' for 'Handle'.
1618
1619 hShow :: Handle -> IO String
1620 hShow h@(FileHandle path _) = showHandle' path False h
1621 hShow h@(DuplexHandle path _ _) = showHandle' path True h
1622
1623 showHandle' filepath is_duplex h =
1624 withHandle_ "showHandle" h $ \hdl_ ->
1625 let
1626 showType | is_duplex = showString "duplex (read-write)"
1627 | otherwise = shows (haType hdl_)
1628 in
1629 return
1630 (( showChar '{' .
1631 showHdl (haType hdl_)
1632 (showString "loc=" . showString filepath . showChar ',' .
1633 showString "type=" . showType . showChar ',' .
1634 showString "binary=" . shows (haIsBin hdl_) . showChar ',' .
1635 showString "buffering=" . showBufMode (unsafePerformIO (readIORef (haBuffer hdl_))) (haBufferMode hdl_) . showString "}" )
1636 ) "")
1637 where
1638
1639 showHdl :: HandleType -> ShowS -> ShowS
1640 showHdl ht cont =
1641 case ht of
1642 ClosedHandle -> shows ht . showString "}"
1643 _ -> cont
1644
1645 showBufMode :: Buffer -> BufferMode -> ShowS
1646 showBufMode buf bmo =
1647 case bmo of
1648 NoBuffering -> showString "none"
1649 LineBuffering -> showString "line"
1650 BlockBuffering (Just n) -> showString "block " . showParen True (shows n)
1651 BlockBuffering Nothing -> showString "block " . showParen True (shows def)
1652 where
1653 def :: Int
1654 def = bufSize buf
1655
1656 -- ---------------------------------------------------------------------------
1657 -- debugging
1658
1659 #if defined(DEBUG_DUMP)
1660 puts :: String -> IO ()
1661 puts s = do write_rawBuffer 1 (unsafeCoerce# (packCString# s)) 0 (fromIntegral (length s))
1662 return ()
1663 #endif
1664
1665 -- -----------------------------------------------------------------------------
1666 -- utils
1667
1668 throwErrnoIfMinus1RetryOnBlock :: String -> IO CInt -> IO CInt -> IO CInt
1669 throwErrnoIfMinus1RetryOnBlock loc f on_block =
1670 do
1671 res <- f
1672 if (res :: CInt) == -1
1673 then do
1674 err <- getErrno
1675 if err == eINTR
1676 then throwErrnoIfMinus1RetryOnBlock loc f on_block
1677 else if err == eWOULDBLOCK || err == eAGAIN
1678 then do on_block
1679 else throwErrno loc
1680 else return res
1681
1682 -- -----------------------------------------------------------------------------
1683 -- wrappers to platform-specific constants:
1684
1685 foreign import ccall unsafe "__hscore_supportsTextMode"
1686 tEXT_MODE_SEEK_ALLOWED :: Bool
1687
1688 foreign import ccall unsafe "__hscore_bufsiz" dEFAULT_BUFFER_SIZE :: Int
1689 foreign import ccall unsafe "__hscore_seek_cur" sEEK_CUR :: CInt
1690 foreign import ccall unsafe "__hscore_seek_set" sEEK_SET :: CInt
1691 foreign import ccall unsafe "__hscore_seek_end" sEEK_END :: CInt