[project @ 2003-12-22 12:41:52 by simonmar]
[ghc.git] / libraries / base / GHC / Handle.hs
1 {-# OPTIONS -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 module GHC.Handle (
21 withHandle, withHandle', withHandle_,
22 wantWritableHandle, wantReadableHandle, wantSeekableHandle,
23
24 newEmptyBuffer, allocateBuffer, readCharFromBuffer, writeCharIntoBuffer,
25 flushWriteBufferOnly, flushWriteBuffer, flushReadBuffer,
26 fillReadBuffer, fillReadBufferWithoutBlocking,
27 readRawBuffer, readRawBufferPtr,
28 writeRawBuffer, writeRawBufferPtr,
29 unlockFile,
30
31 {- ought to be unnecessary, but just in case.. -}
32 write_off, write_rawBuffer,
33 read_off, read_rawBuffer,
34
35 ioe_closedHandle, ioe_EOF, ioe_notReadable, ioe_notWritable,
36
37 stdin, stdout, stderr,
38 IOMode(..), openFile, openBinaryFile, openFd, fdToHandle,
39 hFileSize, 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 #include "config.h"
59
60 import Control.Monad
61 import Data.Bits
62 import Data.Maybe
63 import Foreign
64 import Foreign.C
65 import System.IO.Error
66 import System.Posix.Internals
67
68 import GHC.Real
69
70 import GHC.Arr
71 import GHC.Base
72 import GHC.Read ( Read )
73 import GHC.List
74 import GHC.IOBase
75 import GHC.Exception
76 import GHC.Enum
77 import GHC.Num ( Integer(..), Num(..) )
78 import GHC.Show
79 import GHC.Real ( toInteger )
80
81 import GHC.Conc
82
83 -- -----------------------------------------------------------------------------
84 -- TODO:
85
86 -- hWaitForInput blocks (should use a timeout)
87
88 -- unbuffered hGetLine is a bit dodgy
89
90 -- hSetBuffering: can't change buffering on a stream,
91 -- when the read buffer is non-empty? (no way to flush the buffer)
92
93 -- ---------------------------------------------------------------------------
94 -- Are files opened by default in text or binary mode, if the user doesn't
95 -- specify?
96
97 dEFAULT_OPEN_IN_BINARY_MODE = False :: Bool
98
99 -- ---------------------------------------------------------------------------
100 -- Creating a new handle
101
102 newFileHandle :: FilePath -> (MVar Handle__ -> IO ()) -> Handle__ -> IO Handle
103 newFileHandle filepath finalizer hc = do
104 m <- newMVar hc
105 addMVarFinalizer m (finalizer m)
106 return (FileHandle filepath m)
107
108 -- ---------------------------------------------------------------------------
109 -- Working with Handles
110
111 {-
112 In the concurrent world, handles are locked during use. This is done
113 by wrapping an MVar around the handle which acts as a mutex over
114 operations on the handle.
115
116 To avoid races, we use the following bracketing operations. The idea
117 is to obtain the lock, do some operation and replace the lock again,
118 whether the operation succeeded or failed. We also want to handle the
119 case where the thread receives an exception while processing the IO
120 operation: in these cases we also want to relinquish the lock.
121
122 There are three versions of @withHandle@: corresponding to the three
123 possible combinations of:
124
125 - the operation may side-effect the handle
126 - the operation may return a result
127
128 If the operation generates an error or an exception is raised, the
129 original handle is always replaced [ this is the case at the moment,
130 but we might want to revisit this in the future --SDM ].
131 -}
132
133 {-# INLINE withHandle #-}
134 withHandle :: String -> Handle -> (Handle__ -> IO (Handle__,a)) -> IO a
135 withHandle fun h@(FileHandle _ m) act = withHandle' fun h m act
136 withHandle fun h@(DuplexHandle _ m _) act = withHandle' fun h m act
137
138 withHandle' :: String -> Handle -> MVar Handle__
139 -> (Handle__ -> IO (Handle__,a)) -> IO a
140 withHandle' fun h m act =
141 block $ do
142 h_ <- takeMVar m
143 checkBufferInvariants h_
144 (h',v) <- catchException (act h_)
145 (\ err -> putMVar m h_ >>
146 case err of
147 IOException ex -> ioError (augmentIOError ex fun h)
148 _ -> throw err)
149 checkBufferInvariants h'
150 putMVar m h'
151 return v
152
153 {-# INLINE withHandle_ #-}
154 withHandle_ :: String -> Handle -> (Handle__ -> IO a) -> IO a
155 withHandle_ fun h@(FileHandle _ m) act = withHandle_' fun h m act
156 withHandle_ fun h@(DuplexHandle _ m _) act = withHandle_' fun h m act
157
158 withHandle_' fun h m act =
159 block $ do
160 h_ <- takeMVar m
161 checkBufferInvariants h_
162 v <- catchException (act h_)
163 (\ err -> putMVar m h_ >>
164 case err of
165 IOException ex -> ioError (augmentIOError ex fun h)
166 _ -> throw err)
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__' fun h m act =
178 block $ do
179 h_ <- takeMVar m
180 checkBufferInvariants h_
181 h' <- catchException (act h_)
182 (\ err -> putMVar m h_ >>
183 case err of
184 IOException ex -> ioError (augmentIOError ex fun h)
185 _ -> throw err)
186 checkBufferInvariants h'
187 putMVar m h'
188 return ()
189
190 augmentIOError (IOError _ iot _ str fp) fun h
191 = IOError (Just h) iot fun str filepath
192 where filepath
193 | Just _ <- fp = fp
194 | otherwise = case h of
195 FileHandle fp _ -> Just fp
196 DuplexHandle fp _ _ -> Just fp
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 act handle_
215 = case haType handle_ of
216 ClosedHandle -> ioe_closedHandle
217 SemiClosedHandle -> ioe_closedHandle
218 ReadHandle -> ioe_notWritable
219 ReadWriteHandle -> do
220 let ref = haBuffer handle_
221 buf <- readIORef ref
222 new_buf <-
223 if not (bufferIsWritable buf)
224 then do b <- flushReadBuffer (haFD handle_) buf
225 return b{ bufState=WriteBuffer }
226 else return buf
227 writeIORef ref new_buf
228 act handle_
229 _other -> act handle_
230
231 -- ---------------------------------------------------------------------------
232 -- Wrapper for read operations.
233
234 wantReadableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
235 wantReadableHandle fun h@(FileHandle _ m) act
236 = wantReadableHandle' fun h m act
237 wantReadableHandle fun h@(DuplexHandle _ m _) act
238 = wantReadableHandle' fun h m act
239 -- ToDo: in the Duplex case, we don't need to checkReadableHandle
240
241 wantReadableHandle'
242 :: String -> Handle -> MVar Handle__
243 -> (Handle__ -> IO a) -> IO a
244 wantReadableHandle' fun h m act
245 = withHandle_' fun h m (checkReadableHandle act)
246
247 checkReadableHandle act handle_ =
248 case haType handle_ of
249 ClosedHandle -> ioe_closedHandle
250 SemiClosedHandle -> ioe_closedHandle
251 AppendHandle -> ioe_notReadable
252 WriteHandle -> ioe_notReadable
253 ReadWriteHandle -> do
254 let ref = haBuffer handle_
255 buf <- readIORef ref
256 when (bufferIsWritable buf) $ do
257 new_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
258 writeIORef ref new_buf{ bufState=ReadBuffer }
259 act handle_
260 _other -> act handle_
261
262 -- ---------------------------------------------------------------------------
263 -- Wrapper for seek operations.
264
265 wantSeekableHandle :: String -> Handle -> (Handle__ -> IO a) -> IO a
266 wantSeekableHandle fun h@(DuplexHandle _ _ _) _act =
267 ioException (IOError (Just h) IllegalOperation fun
268 "handle is not seekable" Nothing)
269 wantSeekableHandle fun h@(FileHandle _ m) act =
270 withHandle_' fun h m (checkSeekableHandle act)
271
272 checkSeekableHandle act handle_ =
273 case haType handle_ of
274 ClosedHandle -> ioe_closedHandle
275 SemiClosedHandle -> ioe_closedHandle
276 AppendHandle -> ioe_notSeekable
277 _ | haIsBin handle_ || tEXT_MODE_SEEK_ALLOWED -> act handle_
278 | otherwise -> ioe_notSeekable_notBin
279
280 -- -----------------------------------------------------------------------------
281 -- Handy IOErrors
282
283 ioe_closedHandle, ioe_EOF,
284 ioe_notReadable, ioe_notWritable,
285 ioe_notSeekable, ioe_notSeekable_notBin :: IO a
286
287 ioe_closedHandle = ioException
288 (IOError Nothing IllegalOperation ""
289 "handle is closed" Nothing)
290 ioe_EOF = ioException
291 (IOError Nothing EOF "" "" Nothing)
292 ioe_notReadable = ioException
293 (IOError Nothing IllegalOperation ""
294 "handle is not open for reading" Nothing)
295 ioe_notWritable = ioException
296 (IOError Nothing IllegalOperation ""
297 "handle is not open for writing" Nothing)
298 ioe_notSeekable = ioException
299 (IOError Nothing IllegalOperation ""
300 "handle is not seekable" Nothing)
301 ioe_notSeekable_notBin = ioException
302 (IOError Nothing IllegalOperation ""
303 "seek operations on text-mode handles are not allowed on this platform"
304 Nothing)
305
306 ioe_bufsiz :: Int -> IO a
307 ioe_bufsiz n = ioException
308 (IOError Nothing InvalidArgument "hSetBuffering"
309 ("illegal buffer size " ++ showsPrec 9 n []) Nothing)
310 -- 9 => should be parens'ified.
311
312 -- -----------------------------------------------------------------------------
313 -- Handle Finalizers
314
315 -- For a duplex handle, we arrange that the read side points to the write side
316 -- (and hence keeps it alive if the read side is alive). This is done by
317 -- having the haOtherSide field of the read side point to the read side.
318 -- The finalizer is then placed on the write side, and the handle only gets
319 -- finalized once, when both sides are no longer required.
320
321 stdHandleFinalizer :: MVar Handle__ -> IO ()
322 stdHandleFinalizer m = do
323 h_ <- takeMVar m
324 flushWriteBufferOnly h_
325
326 handleFinalizer :: MVar Handle__ -> IO ()
327 handleFinalizer m = do
328 handle_ <- takeMVar m
329 case haType handle_ of
330 ClosedHandle -> return ()
331 _ -> do flushWriteBufferOnly handle_ `catchException` \_ -> return ()
332 -- ignore errors and async exceptions, and close the
333 -- descriptor anyway...
334 hClose_handle_ handle_
335 return ()
336
337 -- ---------------------------------------------------------------------------
338 -- Grimy buffer operations
339
340 #ifdef DEBUG
341 checkBufferInvariants h_ = do
342 let ref = haBuffer h_
343 Buffer{ bufWPtr=w, bufRPtr=r, bufSize=size, bufState=state } <- readIORef ref
344 if not (
345 size > 0
346 && r <= w
347 && w <= size
348 && ( r /= w || (r == 0 && w == 0) )
349 && ( state /= WriteBuffer || r == 0 )
350 && ( state /= WriteBuffer || w < size ) -- write buffer is never full
351 )
352 then error "buffer invariant violation"
353 else return ()
354 #else
355 checkBufferInvariants h_ = return ()
356 #endif
357
358 newEmptyBuffer :: RawBuffer -> BufferState -> Int -> Buffer
359 newEmptyBuffer b state size
360 = Buffer{ bufBuf=b, bufRPtr=0, bufWPtr=0, bufSize=size, bufState=state }
361
362 allocateBuffer :: Int -> BufferState -> IO Buffer
363 allocateBuffer sz@(I# size) state = IO $ \s ->
364 #ifdef mingw32_TARGET_OS
365 -- To implement asynchronous I/O under Win32, we have to pass
366 -- buffer references to external threads that handles the
367 -- filling/emptying of their contents. Hence, the buffer cannot
368 -- be moved around by the GC.
369 case newPinnedByteArray# size s of { (# s, b #) ->
370 #else
371 case newByteArray# size s of { (# s, b #) ->
372 #endif
373 (# s, newEmptyBuffer b state sz #) }
374
375 writeCharIntoBuffer :: RawBuffer -> Int -> Char -> IO Int
376 writeCharIntoBuffer slab (I# off) (C# c)
377 = IO $ \s -> case writeCharArray# slab off c s of
378 s -> (# s, I# (off +# 1#) #)
379
380 readCharFromBuffer :: RawBuffer -> Int -> IO (Char, Int)
381 readCharFromBuffer slab (I# off)
382 = IO $ \s -> case readCharArray# slab off s of
383 (# s, c #) -> (# s, (C# c, I# (off +# 1#)) #)
384
385 getBuffer :: FD -> BufferState -> IO (IORef Buffer, BufferMode)
386 getBuffer fd state = do
387 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE state
388 ioref <- newIORef buffer
389 is_tty <- fdIsTTY fd
390
391 let buffer_mode
392 | is_tty = LineBuffering
393 | otherwise = BlockBuffering Nothing
394
395 return (ioref, buffer_mode)
396
397 mkUnBuffer :: IO (IORef Buffer)
398 mkUnBuffer = do
399 buffer <- allocateBuffer 1 ReadBuffer
400 newIORef buffer
401
402 -- flushWriteBufferOnly flushes the buffer iff it contains pending write data.
403 flushWriteBufferOnly :: Handle__ -> IO ()
404 flushWriteBufferOnly h_ = do
405 let fd = haFD h_
406 ref = haBuffer h_
407 buf <- readIORef ref
408 new_buf <- if bufferIsWritable buf
409 then flushWriteBuffer fd (haIsStream h_) buf
410 else return buf
411 writeIORef ref new_buf
412
413 -- flushBuffer syncs the file with the buffer, including moving the
414 -- file pointer backwards in the case of a read buffer.
415 flushBuffer :: Handle__ -> IO ()
416 flushBuffer h_ = do
417 let ref = haBuffer h_
418 buf <- readIORef ref
419
420 flushed_buf <-
421 case bufState buf of
422 ReadBuffer -> flushReadBuffer (haFD h_) buf
423 WriteBuffer -> flushWriteBuffer (haFD h_) (haIsStream h_) buf
424
425 writeIORef ref flushed_buf
426
427 -- When flushing a read buffer, we seek backwards by the number of
428 -- characters in the buffer. The file descriptor must therefore be
429 -- seekable: attempting to flush the read buffer on an unseekable
430 -- handle is not allowed.
431
432 flushReadBuffer :: FD -> Buffer -> IO Buffer
433 flushReadBuffer fd buf
434 | bufferEmpty buf = return buf
435 | otherwise = do
436 let off = negate (bufWPtr buf - bufRPtr buf)
437 # ifdef DEBUG_DUMP
438 puts ("flushReadBuffer: new file offset = " ++ show off ++ "\n")
439 # endif
440 throwErrnoIfMinus1Retry "flushReadBuffer"
441 (c_lseek (fromIntegral fd) (fromIntegral off) sEEK_CUR)
442 return buf{ bufWPtr=0, bufRPtr=0 }
443
444 flushWriteBuffer :: FD -> Bool -> Buffer -> IO Buffer
445 flushWriteBuffer fd is_stream buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w } =
446 seq fd $ do -- strictness hack
447 let bytes = w - r
448 #ifdef DEBUG_DUMP
449 puts ("flushWriteBuffer, fd=" ++ show fd ++ ", bytes=" ++ show bytes ++ "\n")
450 #endif
451 if bytes == 0
452 then return (buf{ bufRPtr=0, bufWPtr=0 })
453 else do
454 res <- writeRawBuffer "flushWriteBuffer" (fromIntegral fd) is_stream b
455 (fromIntegral r) (fromIntegral bytes)
456 let res' = fromIntegral res
457 if res' < bytes
458 then flushWriteBuffer fd is_stream (buf{ bufRPtr = r + res' })
459 else return buf{ bufRPtr=0, bufWPtr=0 }
460
461 fillReadBuffer :: FD -> Bool -> Bool -> Buffer -> IO Buffer
462 fillReadBuffer fd is_line is_stream
463 buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w, bufSize=size } =
464 -- buffer better be empty:
465 assert (r == 0 && w == 0) $ do
466 fillReadBufferLoop fd is_line is_stream buf b w size
467
468 -- For a line buffer, we just get the first chunk of data to arrive,
469 -- and don't wait for the whole buffer to be full (but we *do* wait
470 -- until some data arrives). This isn't really line buffering, but it
471 -- appears to be what GHC has done for a long time, and I suspect it
472 -- is more useful than line buffering in most cases.
473
474 fillReadBufferLoop fd is_line is_stream buf b w size = do
475 let bytes = size - w
476 if bytes == 0 -- buffer full?
477 then return buf{ bufRPtr=0, bufWPtr=w }
478 else do
479 #ifdef DEBUG_DUMP
480 puts ("fillReadBufferLoop: bytes = " ++ show bytes ++ "\n")
481 #endif
482 res <- readRawBuffer "fillReadBuffer" fd is_stream b
483 (fromIntegral w) (fromIntegral bytes)
484 let res' = fromIntegral res
485 #ifdef DEBUG_DUMP
486 puts ("fillReadBufferLoop: res' = " ++ show res' ++ "\n")
487 #endif
488 if res' == 0
489 then if w == 0
490 then ioe_EOF
491 else return buf{ bufRPtr=0, bufWPtr=w }
492 else if res' < bytes && not is_line
493 then fillReadBufferLoop fd is_line is_stream buf b (w+res') size
494 else return buf{ bufRPtr=0, bufWPtr=w+res' }
495
496
497 fillReadBufferWithoutBlocking :: FD -> Bool -> Buffer -> IO Buffer
498 fillReadBufferWithoutBlocking fd is_stream
499 buf@Buffer{ bufBuf=b, bufRPtr=r, bufWPtr=w, bufSize=size } =
500 -- buffer better be empty:
501 assert (r == 0 && w == 0) $ do
502 #ifdef DEBUG_DUMP
503 puts ("fillReadBufferLoopNoBlock: bytes = " ++ show bytes ++ "\n")
504 #endif
505 res <- readRawBufferNoBlock "fillReadBuffer" fd is_stream b
506 0 (fromIntegral size)
507 let res' = fromIntegral res
508 #ifdef DEBUG_DUMP
509 puts ("fillReadBufferLoopNoBlock: res' = " ++ show res' ++ "\n")
510 #endif
511 return buf{ bufRPtr=0, bufWPtr=res' }
512
513 -- Low level routines for reading/writing to (raw)buffers:
514
515 #ifndef mingw32_TARGET_OS
516 readRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
517 readRawBuffer loc fd is_stream buf off len =
518 throwErrnoIfMinus1RetryMayBlock loc
519 (read_rawBuffer fd is_stream buf off len)
520 (threadWaitRead fd)
521
522 readRawBufferNoBlock :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
523 readRawBufferNoBlock loc fd is_stream buf off len =
524 throwErrnoIfMinus1RetryOnBlock loc
525 (read_rawBuffer fd is_stream buf off len)
526 (return 0)
527
528 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
529 readRawBufferPtr loc fd is_stream buf off len =
530 throwErrnoIfMinus1RetryMayBlock loc
531 (read_off fd is_stream buf off len)
532 (threadWaitRead fd)
533
534 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
535 writeRawBuffer loc fd is_stream buf off len =
536 throwErrnoIfMinus1RetryMayBlock loc
537 (write_rawBuffer (fromIntegral fd) is_stream buf off len)
538 (threadWaitWrite fd)
539
540 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
541 writeRawBufferPtr loc fd is_stream buf off len =
542 throwErrnoIfMinus1RetryMayBlock loc
543 (write_off (fromIntegral fd) is_stream buf off len)
544 (threadWaitWrite fd)
545
546 foreign import ccall unsafe "__hscore_PrelHandle_read"
547 read_rawBuffer :: FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
548
549 foreign import ccall unsafe "__hscore_PrelHandle_read"
550 read_off :: FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
551
552 foreign import ccall unsafe "__hscore_PrelHandle_write"
553 write_rawBuffer :: CInt -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
554
555 foreign import ccall unsafe "__hscore_PrelHandle_write"
556 write_off :: CInt -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
557
558 #else
559 readRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
560 readRawBuffer loc fd is_stream buf off len = do
561 (l, rc) <- asyncReadBA fd (if is_stream then 1 else 0) (fromIntegral len) off buf
562 if l == (-1)
563 then
564 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
565 else return (fromIntegral l)
566
567 readRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
568 readRawBufferPtr loc fd is_stream buf off len = do
569 (l, rc) <- asyncRead fd (if is_stream then 1 else 0) (fromIntegral len) (buf `plusPtr` off)
570 if l == (-1)
571 then
572 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
573 else return (fromIntegral l)
574
575 writeRawBuffer :: String -> FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
576 writeRawBuffer loc fd is_stream buf off len = do
577 (l, rc) <- asyncWriteBA fd (if is_stream then 1 else 0) (fromIntegral len) off buf
578 if l == (-1)
579 then
580 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
581 else return (fromIntegral l)
582
583 writeRawBufferPtr :: String -> FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
584 writeRawBufferPtr loc fd is_stream buf off len = do
585 (l, rc) <- asyncWrite fd (if is_stream then 1 else 0) (fromIntegral len) (buf `plusPtr` off)
586 if l == (-1)
587 then
588 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
589 else return (fromIntegral l)
590
591 foreign import ccall unsafe "__hscore_PrelHandle_read"
592 read_rawBuffer :: FD -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
593
594 foreign import ccall unsafe "__hscore_PrelHandle_read"
595 read_off :: FD -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
596
597 foreign import ccall unsafe "__hscore_PrelHandle_write"
598 write_rawBuffer :: CInt -> Bool -> RawBuffer -> Int -> CInt -> IO CInt
599
600 foreign import ccall unsafe "__hscore_PrelHandle_write"
601 write_off :: CInt -> Bool -> Ptr CChar -> Int -> CInt -> IO CInt
602
603 #endif
604
605 -- ---------------------------------------------------------------------------
606 -- Standard Handles
607
608 -- Three handles are allocated during program initialisation. The first
609 -- two manage input or output from the Haskell program's standard input
610 -- or output channel respectively. The third manages output to the
611 -- standard error channel. These handles are initially open.
612
613 fd_stdin = 0 :: FD
614 fd_stdout = 1 :: FD
615 fd_stderr = 2 :: FD
616
617 -- | A handle managing input from the Haskell program's standard input channel.
618 stdin :: Handle
619 stdin = unsafePerformIO $ do
620 -- ToDo: acquire lock
621 setNonBlockingFD fd_stdin
622 (buf, bmode) <- getBuffer fd_stdin ReadBuffer
623 mkStdHandle fd_stdin "<stdin>" ReadHandle buf bmode
624
625 -- | A handle managing output to the Haskell program's standard output channel.
626 stdout :: Handle
627 stdout = unsafePerformIO $ do
628 -- ToDo: acquire lock
629 -- We don't set non-blocking mode on stdout or sterr, because
630 -- some shells don't recover properly.
631 -- setNonBlockingFD fd_stdout
632 (buf, bmode) <- getBuffer fd_stdout WriteBuffer
633 mkStdHandle fd_stdout "<stdout>" WriteHandle buf bmode
634
635 -- | A handle managing output to the Haskell program's standard error channel.
636 stderr :: Handle
637 stderr = unsafePerformIO $ do
638 -- ToDo: acquire lock
639 -- We don't set non-blocking mode on stdout or sterr, because
640 -- some shells don't recover properly.
641 -- setNonBlockingFD fd_stderr
642 buf <- mkUnBuffer
643 mkStdHandle fd_stderr "<stderr>" WriteHandle buf NoBuffering
644
645 -- ---------------------------------------------------------------------------
646 -- Opening and Closing Files
647
648 addFilePathToIOError fun fp (IOError h iot _ str _)
649 = IOError h iot fun str (Just fp)
650
651 -- | Computation 'openFile' @file mode@ allocates and returns a new, open
652 -- handle to manage the file @file@. It manages input if @mode@
653 -- is 'ReadMode', output if @mode@ is 'WriteMode' or 'AppendMode',
654 -- and both input and output if mode is 'ReadWriteMode'.
655 --
656 -- If the file does not exist and it is opened for output, it should be
657 -- created as a new file. If @mode@ is 'WriteMode' and the file
658 -- already exists, then it should be truncated to zero length.
659 -- Some operating systems delete empty files, so there is no guarantee
660 -- that the file will exist following an 'openFile' with @mode@
661 -- 'WriteMode' unless it is subsequently written to successfully.
662 -- The handle is positioned at the end of the file if @mode@ is
663 -- 'AppendMode', and otherwise at the beginning (in which case its
664 -- internal position is 0).
665 -- The initial buffer mode is implementation-dependent.
666 --
667 -- This operation may fail with:
668 --
669 -- * 'isAlreadyInUseError' if the file is already open and cannot be reopened;
670 --
671 -- * 'isDoesNotExistError' if the file does not exist; or
672 --
673 -- * 'isPermissionError' if the user does not have permission to open the file.
674
675 openFile :: FilePath -> IOMode -> IO Handle
676 openFile fp im =
677 catch
678 (openFile' fp im dEFAULT_OPEN_IN_BINARY_MODE)
679 (\e -> ioError (addFilePathToIOError "openFile" fp e))
680
681 -- | Like 'openFile', but open the file in binary mode.
682 -- On Windows, reading a file in text mode (which is the default)
683 -- will translate CRLF to LF, and writing will translate LF to CRLF.
684 -- This is usually what you want with text files. With binary files
685 -- this is undesirable; also, as usual under Microsoft operating systems,
686 -- text mode treats control-Z as EOF. Binary mode turns off all special
687 -- treatment of end-of-line and end-of-file characters.
688 -- (See also 'hSetBinaryMode'.)
689
690 openBinaryFile :: FilePath -> IOMode -> IO Handle
691 openBinaryFile fp m =
692 catch
693 (openFile' fp m True)
694 (\e -> ioError (addFilePathToIOError "openBinaryFile" fp e))
695
696 openFile' filepath mode binary =
697 withCString filepath $ \ f ->
698
699 let
700 oflags1 = case mode of
701 ReadMode -> read_flags
702 WriteMode -> write_flags
703 ReadWriteMode -> rw_flags
704 AppendMode -> append_flags
705
706 truncate | WriteMode <- mode = True
707 | otherwise = False
708
709 binary_flags
710 | binary = o_BINARY
711 | otherwise = 0
712
713 oflags = oflags1 .|. binary_flags
714 in do
715
716 -- the old implementation had a complicated series of three opens,
717 -- which is perhaps because we have to be careful not to open
718 -- directories. However, the man pages I've read say that open()
719 -- always returns EISDIR if the file is a directory and was opened
720 -- for writing, so I think we're ok with a single open() here...
721 fd <- fromIntegral `liftM`
722 throwErrnoIfMinus1Retry "openFile"
723 (c_open f (fromIntegral oflags) 0o666)
724
725 openFd fd Nothing filepath mode binary truncate
726 -- ASSERT: if we just created the file, then openFd won't fail
727 -- (so we don't need to worry about removing the newly created file
728 -- in the event of an error).
729
730
731 std_flags = o_NONBLOCK .|. o_NOCTTY
732 output_flags = std_flags .|. o_CREAT
733 read_flags = std_flags .|. o_RDONLY
734 write_flags = output_flags .|. o_WRONLY
735 rw_flags = output_flags .|. o_RDWR
736 append_flags = write_flags .|. o_APPEND
737
738 -- ---------------------------------------------------------------------------
739 -- openFd
740
741 openFd :: FD -> Maybe FDType -> FilePath -> IOMode -> Bool -> Bool -> IO Handle
742 openFd fd mb_fd_type filepath mode binary truncate = do
743 -- turn on non-blocking mode
744 setNonBlockingFD fd
745
746 let (ha_type, write) =
747 case mode of
748 ReadMode -> ( ReadHandle, False )
749 WriteMode -> ( WriteHandle, True )
750 ReadWriteMode -> ( ReadWriteHandle, True )
751 AppendMode -> ( AppendHandle, True )
752
753 -- open() won't tell us if it was a directory if we only opened for
754 -- reading, so check again.
755 fd_type <-
756 case mb_fd_type of
757 Just x -> return x
758 Nothing -> fdType fd
759 let is_stream = fd_type == Stream
760 case fd_type of
761 Directory ->
762 ioException (IOError Nothing InappropriateType "openFile"
763 "is a directory" Nothing)
764
765 Stream
766 | ReadWriteHandle <- ha_type -> mkDuplexHandle fd is_stream filepath binary
767 | otherwise -> mkFileHandle fd is_stream filepath ha_type binary
768
769 -- regular files need to be locked
770 RegularFile -> do
771 r <- lockFile (fromIntegral fd) (fromBool write) 1{-exclusive-}
772 when (r == -1) $
773 ioException (IOError Nothing ResourceBusy "openFile"
774 "file is locked" Nothing)
775
776 -- truncate the file if necessary
777 when truncate (fileTruncate filepath)
778
779 mkFileHandle fd is_stream filepath ha_type binary
780
781
782 fdToHandle :: FD -> IO Handle
783 fdToHandle fd = do
784 mode <- fdGetMode fd
785 let fd_str = "<file descriptor: " ++ show fd ++ ">"
786 openFd fd Nothing fd_str mode True{-bin mode-} False{-no truncate-}
787
788 foreign import ccall unsafe "lockFile"
789 lockFile :: CInt -> CInt -> CInt -> IO CInt
790
791 foreign import ccall unsafe "unlockFile"
792 unlockFile :: CInt -> IO CInt
793
794 mkStdHandle :: FD -> FilePath -> HandleType -> IORef Buffer -> BufferMode
795 -> IO Handle
796 mkStdHandle fd filepath ha_type buf bmode = do
797 spares <- newIORef BufferListNil
798 newFileHandle filepath stdHandleFinalizer
799 (Handle__ { haFD = fd,
800 haType = ha_type,
801 haIsBin = dEFAULT_OPEN_IN_BINARY_MODE,
802 haIsStream = False,
803 haBufferMode = bmode,
804 haBuffer = buf,
805 haBuffers = spares,
806 haOtherSide = Nothing
807 })
808
809 mkFileHandle :: FD -> Bool -> FilePath -> HandleType -> Bool -> IO Handle
810 mkFileHandle fd is_stream filepath ha_type binary = do
811 (buf, bmode) <- getBuffer fd (initBufferState ha_type)
812 spares <- newIORef BufferListNil
813 newFileHandle filepath handleFinalizer
814 (Handle__ { haFD = fd,
815 haType = ha_type,
816 haIsBin = binary,
817 haIsStream = is_stream,
818 haBufferMode = bmode,
819 haBuffer = buf,
820 haBuffers = spares,
821 haOtherSide = Nothing
822 })
823
824 mkDuplexHandle :: FD -> Bool -> FilePath -> Bool -> IO Handle
825 mkDuplexHandle fd is_stream filepath binary = do
826 (w_buf, w_bmode) <- getBuffer fd WriteBuffer
827 w_spares <- newIORef BufferListNil
828 let w_handle_ =
829 Handle__ { haFD = fd,
830 haType = WriteHandle,
831 haIsBin = binary,
832 haIsStream = is_stream,
833 haBufferMode = w_bmode,
834 haBuffer = w_buf,
835 haBuffers = w_spares,
836 haOtherSide = Nothing
837 }
838 write_side <- newMVar w_handle_
839
840 (r_buf, r_bmode) <- getBuffer fd ReadBuffer
841 r_spares <- newIORef BufferListNil
842 let r_handle_ =
843 Handle__ { haFD = fd,
844 haType = ReadHandle,
845 haIsBin = binary,
846 haIsStream = is_stream,
847 haBufferMode = r_bmode,
848 haBuffer = r_buf,
849 haBuffers = r_spares,
850 haOtherSide = Just write_side
851 }
852 read_side <- newMVar r_handle_
853
854 addMVarFinalizer write_side (handleFinalizer write_side)
855 return (DuplexHandle filepath read_side write_side)
856
857
858 initBufferState ReadHandle = ReadBuffer
859 initBufferState _ = WriteBuffer
860
861 -- ---------------------------------------------------------------------------
862 -- Closing a handle
863
864 -- | Computation 'hClose' @hdl@ makes handle @hdl@ closed. Before the
865 -- computation finishes, if @hdl@ is writable its buffer is flushed as
866 -- for 'hFlush'.
867 -- Performing 'hClose' on a handle that has already been closed has no effect;
868 -- doing so not an error. All other operations on a closed handle will fail.
869 -- If 'hClose' fails for any reason, any further operations (apart from
870 -- 'hClose') on the handle will still fail as if @hdl@ had been successfully
871 -- closed.
872
873 hClose :: Handle -> IO ()
874 hClose h@(FileHandle _ m) = hClose' h m
875 hClose h@(DuplexHandle _ r w) = hClose' h w >> hClose' h r
876
877 hClose' h m = withHandle__' "hClose" h m $ hClose_help
878
879 -- hClose_help is also called by lazyRead (in PrelIO) when EOF is read
880 -- or an IO error occurs on a lazy stream. The semi-closed Handle is
881 -- then closed immediately. We have to be careful with DuplexHandles
882 -- though: we have to leave the closing to the finalizer in that case,
883 -- because the write side may still be in use.
884 hClose_help :: Handle__ -> IO Handle__
885 hClose_help handle_ =
886 case haType handle_ of
887 ClosedHandle -> return handle_
888 _ -> do flushWriteBufferOnly handle_ -- interruptible
889 hClose_handle_ handle_
890
891 hClose_handle_ handle_ = do
892 let fd = haFD handle_
893 c_fd = fromIntegral fd
894
895 -- close the file descriptor, but not when this is the read
896 -- side of a duplex handle, and not when this is one of the
897 -- std file handles.
898 case haOtherSide handle_ of
899 Nothing ->
900 when (fd /= fd_stdin && fd /= fd_stdout && fd /= fd_stderr) $
901 throwErrnoIfMinus1Retry_ "hClose"
902 #ifdef mingw32_TARGET_OS
903 (closeFd (haIsStream handle_) c_fd)
904 #else
905 (c_close c_fd)
906 #endif
907 Just _ -> return ()
908
909 -- free the spare buffers
910 writeIORef (haBuffers handle_) BufferListNil
911
912 -- unlock it
913 unlockFile c_fd
914
915 -- we must set the fd to -1, because the finalizer is going
916 -- to run eventually and try to close/unlock it.
917 return (handle_{ haFD = -1,
918 haType = ClosedHandle
919 })
920
921 -----------------------------------------------------------------------------
922 -- Detecting the size of a file
923
924 -- | For a handle @hdl@ which attached to a physical file,
925 -- 'hFileSize' @hdl@ returns the size of that file in 8-bit bytes.
926
927 hFileSize :: Handle -> IO Integer
928 hFileSize handle =
929 withHandle_ "hFileSize" handle $ \ handle_ -> do
930 case haType handle_ of
931 ClosedHandle -> ioe_closedHandle
932 SemiClosedHandle -> ioe_closedHandle
933 _ -> do flushWriteBufferOnly handle_
934 r <- fdFileSize (haFD handle_)
935 if r /= -1
936 then return r
937 else ioException (IOError Nothing InappropriateType "hFileSize"
938 "not a regular file" Nothing)
939
940 -- ---------------------------------------------------------------------------
941 -- Detecting the End of Input
942
943 -- | For a readable handle @hdl@, 'hIsEOF' @hdl@ returns
944 -- 'True' if no further input can be taken from @hdl@ or for a
945 -- physical file, if the current I\/O position is equal to the length of
946 -- the file. Otherwise, it returns 'False'.
947
948 hIsEOF :: Handle -> IO Bool
949 hIsEOF handle =
950 catch
951 (do hLookAhead handle; return False)
952 (\e -> if isEOFError e then return True else ioError e)
953
954 -- | The computation 'isEOF' is identical to 'hIsEOF',
955 -- except that it works only on 'stdin'.
956
957 isEOF :: IO Bool
958 isEOF = hIsEOF stdin
959
960 -- ---------------------------------------------------------------------------
961 -- Looking ahead
962
963 -- | Computation 'hLookAhead' returns the next character from the handle
964 -- without removing it from the input buffer, blocking until a character
965 -- is available.
966 --
967 -- This operation may fail with:
968 --
969 -- * 'isEOFError' if the end of file has been reached.
970
971 hLookAhead :: Handle -> IO Char
972 hLookAhead handle = do
973 wantReadableHandle "hLookAhead" handle $ \handle_ -> do
974 let ref = haBuffer handle_
975 fd = haFD handle_
976 is_line = haBufferMode handle_ == LineBuffering
977 buf <- readIORef ref
978
979 -- fill up the read buffer if necessary
980 new_buf <- if bufferEmpty buf
981 then fillReadBuffer fd is_line (haIsStream handle_) buf
982 else return buf
983
984 writeIORef ref new_buf
985
986 (c,_) <- readCharFromBuffer (bufBuf buf) (bufRPtr buf)
987 return c
988
989 -- ---------------------------------------------------------------------------
990 -- Buffering Operations
991
992 -- Three kinds of buffering are supported: line-buffering,
993 -- block-buffering or no-buffering. See GHC.IOBase for definition and
994 -- further explanation of what the type represent.
995
996 -- | Computation 'hSetBuffering' @hdl mode@ sets the mode of buffering for
997 -- handle @hdl@ on subsequent reads and writes.
998 --
999 -- If the buffer mode is changed from 'BlockBuffering' or
1000 -- 'LineBuffering' to 'NoBuffering', then
1001 --
1002 -- * if @hdl@ is writable, the buffer is flushed as for 'hFlush';
1003 --
1004 -- * if @hdl@ is not writable, the contents of the buffer is discarded.
1005 --
1006 -- This operation may fail with:
1007 --
1008 -- * 'isPermissionError' if the handle has already been used for reading
1009 -- or writing and the implementation does not allow the buffering mode
1010 -- to be changed.
1011
1012 hSetBuffering :: Handle -> BufferMode -> IO ()
1013 hSetBuffering handle mode =
1014 withAllHandles__ "hSetBuffering" handle $ \ handle_ -> do
1015 case haType handle_ of
1016 ClosedHandle -> ioe_closedHandle
1017 _ -> do
1018 {- Note:
1019 - we flush the old buffer regardless of whether
1020 the new buffer could fit the contents of the old buffer
1021 or not.
1022 - allow a handle's buffering to change even if IO has
1023 occurred (ANSI C spec. does not allow this, nor did
1024 the previous implementation of IO.hSetBuffering).
1025 - a non-standard extension is to allow the buffering
1026 of semi-closed handles to change [sof 6/98]
1027 -}
1028 flushBuffer handle_
1029
1030 let state = initBufferState (haType handle_)
1031 new_buf <-
1032 case mode of
1033 -- we always have a 1-character read buffer for
1034 -- unbuffered handles: it's needed to
1035 -- support hLookAhead.
1036 NoBuffering -> allocateBuffer 1 ReadBuffer
1037 LineBuffering -> allocateBuffer dEFAULT_BUFFER_SIZE state
1038 BlockBuffering Nothing -> allocateBuffer dEFAULT_BUFFER_SIZE state
1039 BlockBuffering (Just n) | n <= 0 -> ioe_bufsiz n
1040 | otherwise -> allocateBuffer n state
1041 writeIORef (haBuffer handle_) new_buf
1042
1043 -- for input terminals we need to put the terminal into
1044 -- cooked or raw mode depending on the type of buffering.
1045 is_tty <- fdIsTTY (haFD handle_)
1046 when (is_tty && isReadableHandleType (haType handle_)) $
1047 case mode of
1048 #ifndef mingw32_TARGET_OS
1049 -- 'raw' mode under win32 is a bit too specialised (and troublesome
1050 -- for most common uses), so simply disable its use here.
1051 NoBuffering -> setCooked (haFD handle_) False
1052 #endif
1053 _ -> setCooked (haFD handle_) True
1054
1055 -- throw away spare buffers, they might be the wrong size
1056 writeIORef (haBuffers handle_) BufferListNil
1057
1058 return (handle_{ haBufferMode = mode })
1059
1060 -- -----------------------------------------------------------------------------
1061 -- hFlush
1062
1063 -- | The action 'hFlush' @hdl@ causes any items buffered for output
1064 -- in handle @hdl@ to be sent immediately to the operating system.
1065 --
1066 -- This operation may fail with:
1067 --
1068 -- * 'isFullError' if the device is full;
1069 --
1070 -- * 'isPermissionError' if a system resource limit would be exceeded.
1071 -- It is unspecified whether the characters in the buffer are discarded
1072 -- or retained under these circumstances.
1073
1074 hFlush :: Handle -> IO ()
1075 hFlush handle =
1076 wantWritableHandle "hFlush" handle $ \ handle_ -> do
1077 buf <- readIORef (haBuffer handle_)
1078 if bufferIsWritable buf && not (bufferEmpty buf)
1079 then do flushed_buf <- flushWriteBuffer (haFD handle_) (haIsStream handle_) buf
1080 writeIORef (haBuffer handle_) flushed_buf
1081 else return ()
1082
1083
1084 -- -----------------------------------------------------------------------------
1085 -- Repositioning Handles
1086
1087 data HandlePosn = HandlePosn Handle HandlePosition
1088
1089 instance Eq HandlePosn where
1090 (HandlePosn h1 p1) == (HandlePosn h2 p2) = p1==p2 && h1==h2
1091
1092 instance Show HandlePosn where
1093 showsPrec p (HandlePosn h pos) =
1094 showsPrec p h . showString " at position " . shows pos
1095
1096 -- HandlePosition is the Haskell equivalent of POSIX' off_t.
1097 -- We represent it as an Integer on the Haskell side, but
1098 -- cheat slightly in that hGetPosn calls upon a C helper
1099 -- that reports the position back via (merely) an Int.
1100 type HandlePosition = Integer
1101
1102 -- | Computation 'hGetPosn' @hdl@ returns the current I\/O position of
1103 -- @hdl@ as a value of the abstract type 'HandlePosn'.
1104
1105 hGetPosn :: Handle -> IO HandlePosn
1106 hGetPosn handle = do
1107 posn <- hTell handle
1108 return (HandlePosn handle posn)
1109
1110 -- | If a call to 'hGetPosn' @hdl@ returns a position @p@,
1111 -- then computation 'hSetPosn' @p@ sets the position of @hdl@
1112 -- to the position it held at the time of the call to 'hGetPosn'.
1113 --
1114 -- This operation may fail with:
1115 --
1116 -- * 'isPermissionError' if a system resource limit would be exceeded.
1117
1118 hSetPosn :: HandlePosn -> IO ()
1119 hSetPosn (HandlePosn h i) = hSeek h AbsoluteSeek i
1120
1121 -- ---------------------------------------------------------------------------
1122 -- hSeek
1123
1124 -- | A mode that determines the effect of 'hSeek' @hdl mode i@, as follows:
1125 data SeekMode
1126 = AbsoluteSeek -- ^ the position of @hdl@ is set to @i@.
1127 | RelativeSeek -- ^ the position of @hdl@ is set to offset @i@
1128 -- from the current position.
1129 | SeekFromEnd -- ^ the position of @hdl@ is set to offset @i@
1130 -- from the end of the file.
1131 deriving (Eq, Ord, Ix, Enum, Read, Show)
1132
1133 {- Note:
1134 - when seeking using `SeekFromEnd', positive offsets (>=0) means
1135 seeking at or past EOF.
1136
1137 - we possibly deviate from the report on the issue of seeking within
1138 the buffer and whether to flush it or not. The report isn't exactly
1139 clear here.
1140 -}
1141
1142 -- | Computation 'hSeek' @hdl mode i@ sets the position of handle
1143 -- @hdl@ depending on @mode@.
1144 -- The offset @i@ is given in terms of 8-bit bytes.
1145 --
1146 -- If @hdl@ is block- or line-buffered, then seeking to a position which is not
1147 -- in the current buffer will first cause any items in the output buffer to be
1148 -- written to the device, and then cause the input buffer to be discarded.
1149 -- Some handles may not be seekable (see 'hIsSeekable'), or only support a
1150 -- subset of the possible positioning operations (for instance, it may only
1151 -- be possible to seek to the end of a tape, or to a positive offset from
1152 -- the beginning or current position).
1153 -- It is not possible to set a negative I\/O position, or for
1154 -- a physical file, an I\/O position beyond the current end-of-file.
1155 --
1156 -- This operation may fail with:
1157 --
1158 -- * 'isPermissionError' if a system resource limit would be exceeded.
1159
1160 hSeek :: Handle -> SeekMode -> Integer -> IO ()
1161 hSeek handle mode offset =
1162 wantSeekableHandle "hSeek" handle $ \ handle_ -> do
1163 # ifdef DEBUG_DUMP
1164 puts ("hSeek " ++ show (mode,offset) ++ "\n")
1165 # endif
1166 let ref = haBuffer handle_
1167 buf <- readIORef ref
1168 let r = bufRPtr buf
1169 w = bufWPtr buf
1170 fd = haFD handle_
1171
1172 let do_seek =
1173 throwErrnoIfMinus1Retry_ "hSeek"
1174 (c_lseek (fromIntegral (haFD handle_)) (fromIntegral offset) whence)
1175
1176 whence :: CInt
1177 whence = case mode of
1178 AbsoluteSeek -> sEEK_SET
1179 RelativeSeek -> sEEK_CUR
1180 SeekFromEnd -> sEEK_END
1181
1182 if bufferIsWritable buf
1183 then do new_buf <- flushWriteBuffer fd (haIsStream handle_) buf
1184 writeIORef ref new_buf
1185 do_seek
1186 else do
1187
1188 if mode == RelativeSeek && offset >= 0 && offset < fromIntegral (w - r)
1189 then writeIORef ref buf{ bufRPtr = r + fromIntegral offset }
1190 else do
1191
1192 new_buf <- flushReadBuffer (haFD handle_) buf
1193 writeIORef ref new_buf
1194 do_seek
1195
1196
1197 hTell :: Handle -> IO Integer
1198 hTell handle =
1199 wantSeekableHandle "hGetPosn" handle $ \ handle_ -> do
1200
1201 #if defined(mingw32_TARGET_OS)
1202 -- urgh, on Windows we have to worry about \n -> \r\n translation,
1203 -- so we can't easily calculate the file position using the
1204 -- current buffer size. Just flush instead.
1205 flushBuffer handle_
1206 #endif
1207 let fd = fromIntegral (haFD handle_)
1208 posn <- fromIntegral `liftM`
1209 throwErrnoIfMinus1Retry "hGetPosn"
1210 (c_lseek fd 0 sEEK_CUR)
1211
1212 let ref = haBuffer handle_
1213 buf <- readIORef ref
1214
1215 let real_posn
1216 | bufferIsWritable buf = posn + fromIntegral (bufWPtr buf)
1217 | otherwise = posn - fromIntegral (bufWPtr buf - bufRPtr buf)
1218 # ifdef DEBUG_DUMP
1219 puts ("\nhGetPosn: (fd, posn, real_posn) = " ++ show (fd, posn, real_posn) ++ "\n")
1220 puts (" (bufWPtr, bufRPtr) = " ++ show (bufWPtr buf, bufRPtr buf) ++ "\n")
1221 # endif
1222 return real_posn
1223
1224 -- -----------------------------------------------------------------------------
1225 -- Handle Properties
1226
1227 -- A number of operations return information about the properties of a
1228 -- handle. Each of these operations returns `True' if the handle has
1229 -- the specified property, and `False' otherwise.
1230
1231 hIsOpen :: Handle -> IO Bool
1232 hIsOpen handle =
1233 withHandle_ "hIsOpen" handle $ \ handle_ -> do
1234 case haType handle_ of
1235 ClosedHandle -> return False
1236 SemiClosedHandle -> return False
1237 _ -> return True
1238
1239 hIsClosed :: Handle -> IO Bool
1240 hIsClosed handle =
1241 withHandle_ "hIsClosed" handle $ \ handle_ -> do
1242 case haType handle_ of
1243 ClosedHandle -> return True
1244 _ -> return False
1245
1246 {- not defined, nor exported, but mentioned
1247 here for documentation purposes:
1248
1249 hSemiClosed :: Handle -> IO Bool
1250 hSemiClosed h = do
1251 ho <- hIsOpen h
1252 hc <- hIsClosed h
1253 return (not (ho || hc))
1254 -}
1255
1256 hIsReadable :: Handle -> IO Bool
1257 hIsReadable (DuplexHandle _ _ _) = return True
1258 hIsReadable handle =
1259 withHandle_ "hIsReadable" handle $ \ handle_ -> do
1260 case haType handle_ of
1261 ClosedHandle -> ioe_closedHandle
1262 SemiClosedHandle -> ioe_closedHandle
1263 htype -> return (isReadableHandleType htype)
1264
1265 hIsWritable :: Handle -> IO Bool
1266 hIsWritable (DuplexHandle _ _ _) = return True
1267 hIsWritable handle =
1268 withHandle_ "hIsWritable" handle $ \ handle_ -> do
1269 case haType handle_ of
1270 ClosedHandle -> ioe_closedHandle
1271 SemiClosedHandle -> ioe_closedHandle
1272 htype -> return (isWritableHandleType htype)
1273
1274 -- | Computation 'hGetBuffering' @hdl@ returns the current buffering mode
1275 -- for @hdl@.
1276
1277 hGetBuffering :: Handle -> IO BufferMode
1278 hGetBuffering handle =
1279 withHandle_ "hGetBuffering" handle $ \ handle_ -> do
1280 case haType handle_ of
1281 ClosedHandle -> ioe_closedHandle
1282 _ ->
1283 -- We're being non-standard here, and allow the buffering
1284 -- of a semi-closed handle to be queried. -- sof 6/98
1285 return (haBufferMode handle_) -- could be stricter..
1286
1287 hIsSeekable :: Handle -> IO Bool
1288 hIsSeekable handle =
1289 withHandle_ "hIsSeekable" handle $ \ handle_ -> do
1290 case haType handle_ of
1291 ClosedHandle -> ioe_closedHandle
1292 SemiClosedHandle -> ioe_closedHandle
1293 AppendHandle -> return False
1294 _ -> do t <- fdType (haFD handle_)
1295 return (t == RegularFile
1296 && (haIsBin handle_
1297 || tEXT_MODE_SEEK_ALLOWED))
1298
1299 -- -----------------------------------------------------------------------------
1300 -- Changing echo status (Non-standard GHC extensions)
1301
1302 -- | Set the echoing status of a handle connected to a terminal (GHC only).
1303
1304 hSetEcho :: Handle -> Bool -> IO ()
1305 hSetEcho handle on = do
1306 isT <- hIsTerminalDevice handle
1307 if not isT
1308 then return ()
1309 else
1310 withHandle_ "hSetEcho" handle $ \ handle_ -> do
1311 case haType handle_ of
1312 ClosedHandle -> ioe_closedHandle
1313 _ -> setEcho (haFD handle_) on
1314
1315 -- | Get the echoing status of a handle connected to a terminal (GHC only).
1316
1317 hGetEcho :: Handle -> IO Bool
1318 hGetEcho handle = do
1319 isT <- hIsTerminalDevice handle
1320 if not isT
1321 then return False
1322 else
1323 withHandle_ "hGetEcho" handle $ \ handle_ -> do
1324 case haType handle_ of
1325 ClosedHandle -> ioe_closedHandle
1326 _ -> getEcho (haFD handle_)
1327
1328 -- | Is the handle connected to a terminal? (GHC only)
1329
1330 hIsTerminalDevice :: Handle -> IO Bool
1331 hIsTerminalDevice handle = do
1332 withHandle_ "hIsTerminalDevice" handle $ \ handle_ -> do
1333 case haType handle_ of
1334 ClosedHandle -> ioe_closedHandle
1335 _ -> fdIsTTY (haFD handle_)
1336
1337 -- -----------------------------------------------------------------------------
1338 -- hSetBinaryMode
1339
1340 -- | Select binary mode ('True') or text mode ('False') on a open handle.
1341 -- (GHC only; see also 'openBinaryFile'.)
1342
1343 hSetBinaryMode :: Handle -> Bool -> IO ()
1344 hSetBinaryMode handle bin =
1345 withAllHandles__ "hSetBinaryMode" handle $ \ handle_ ->
1346 do throwErrnoIfMinus1_ "hSetBinaryMode"
1347 (setmode (fromIntegral (haFD handle_)) bin)
1348 return handle_{haIsBin=bin}
1349
1350 foreign import ccall unsafe "__hscore_setmode"
1351 setmode :: CInt -> Bool -> IO CInt
1352
1353 -- -----------------------------------------------------------------------------
1354 -- Duplicating a Handle
1355
1356 -- |Returns a duplicate of the original handle, with its own buffer
1357 -- and file pointer. The original handle's buffer is flushed, including
1358 -- discarding any input data, before the handle is duplicated.
1359
1360 hDuplicate :: Handle -> IO Handle
1361 hDuplicate h@(FileHandle path m) = do
1362 new_h_ <- withHandle' "hDuplicate" h m (dupHandle_ Nothing)
1363 new_m <- newMVar new_h_
1364 return (FileHandle path new_m)
1365 hDuplicate h@(DuplexHandle path r w) = do
1366 new_w_ <- withHandle' "hDuplicate" h w (dupHandle_ Nothing)
1367 new_w <- newMVar new_w_
1368 new_r_ <- withHandle' "hDuplicate" h r (dupHandle_ (Just new_w))
1369 new_r <- newMVar new_r_
1370 return (DuplexHandle path new_r new_w)
1371
1372 dupHandle_ other_side h_ = do
1373 -- flush the buffer first, so we don't have to copy its contents
1374 flushBuffer h_
1375 new_fd <- c_dup (fromIntegral (haFD h_))
1376 buffer <- allocateBuffer dEFAULT_BUFFER_SIZE (initBufferState (haType h_))
1377 ioref <- newIORef buffer
1378 ioref_buffers <- newIORef BufferListNil
1379
1380 let new_handle_ = h_{ haFD = fromIntegral new_fd,
1381 haBuffer = ioref,
1382 haBuffers = ioref_buffers,
1383 haOtherSide = other_side }
1384 return (h_, new_handle_)
1385
1386 -- -----------------------------------------------------------------------------
1387 -- Replacing a Handle
1388
1389 {- |
1390 Makes the second handle a duplicate of the first handle. The second
1391 handle will be closed first, if it is not already.
1392
1393 This can be used to retarget the standard Handles, for example:
1394
1395 > do h <- openFile "mystdout" WriteMode
1396 > hDuplicateTo h stdout
1397 -}
1398
1399 hDuplicateTo :: Handle -> Handle -> IO ()
1400 hDuplicateTo h1@(FileHandle _ m1) h2@(FileHandle _ m2) = do
1401 withHandle__' "hDuplicateTo" h2 m2 $ \h2_ -> do
1402 _ <- hClose_help h2_
1403 withHandle' "hDuplicateTo" h1 m1 (dupHandle_ Nothing)
1404 hDuplicateTo h1@(DuplexHandle _ r1 w1) h2@(DuplexHandle _ r2 w2) = do
1405 withHandle__' "hDuplicateTo" h2 w2 $ \w2_ -> do
1406 _ <- hClose_help w2_
1407 withHandle' "hDuplicateTo" h1 r1 (dupHandle_ Nothing)
1408 withHandle__' "hDuplicateTo" h2 r2 $ \r2_ -> do
1409 _ <- hClose_help r2_
1410 withHandle' "hDuplicateTo" h1 r1 (dupHandle_ (Just w1))
1411 hDuplicateTo h1 _ =
1412 ioException (IOError (Just h1) IllegalOperation "hDuplicateTo"
1413 "handles are incompatible" Nothing)
1414
1415 -- ---------------------------------------------------------------------------
1416 -- showing Handles.
1417 --
1418 -- | 'hShow' is in the 'IO' monad, and gives more comprehensive output
1419 -- than the (pure) instance of 'Show' for 'Handle'.
1420
1421 hShow :: Handle -> IO String
1422 hShow h@(FileHandle path _) = showHandle' path False h
1423 hShow h@(DuplexHandle path _ _) = showHandle' path True h
1424
1425 showHandle' filepath is_duplex h =
1426 withHandle_ "showHandle" h $ \hdl_ ->
1427 let
1428 showType | is_duplex = showString "duplex (read-write)"
1429 | otherwise = shows (haType hdl_)
1430 in
1431 return
1432 (( showChar '{' .
1433 showHdl (haType hdl_)
1434 (showString "loc=" . showString filepath . showChar ',' .
1435 showString "type=" . showType . showChar ',' .
1436 showString "binary=" . shows (haIsBin hdl_) . showChar ',' .
1437 showString "buffering=" . showBufMode (unsafePerformIO (readIORef (haBuffer hdl_))) (haBufferMode hdl_) . showString "}" )
1438 ) "")
1439 where
1440
1441 showHdl :: HandleType -> ShowS -> ShowS
1442 showHdl ht cont =
1443 case ht of
1444 ClosedHandle -> shows ht . showString "}"
1445 _ -> cont
1446
1447 showBufMode :: Buffer -> BufferMode -> ShowS
1448 showBufMode buf bmo =
1449 case bmo of
1450 NoBuffering -> showString "none"
1451 LineBuffering -> showString "line"
1452 BlockBuffering (Just n) -> showString "block " . showParen True (shows n)
1453 BlockBuffering Nothing -> showString "block " . showParen True (shows def)
1454 where
1455 def :: Int
1456 def = bufSize buf
1457
1458 -- ---------------------------------------------------------------------------
1459 -- debugging
1460
1461 #ifdef DEBUG_DUMP
1462 puts :: String -> IO ()
1463 puts s = withCString s $ \cstr -> do write_rawBuffer 1 False cstr 0 (fromIntegral (length s))
1464 return ()
1465 #endif
1466
1467 -- -----------------------------------------------------------------------------
1468 -- utils
1469
1470 throwErrnoIfMinus1RetryOnBlock :: String -> IO CInt -> IO CInt -> IO CInt
1471 throwErrnoIfMinus1RetryOnBlock loc f on_block =
1472 do
1473 res <- f
1474 if (res :: CInt) == -1
1475 then do
1476 err <- getErrno
1477 if err == eINTR
1478 then throwErrnoIfMinus1RetryOnBlock loc f on_block
1479 else if err == eWOULDBLOCK || err == eAGAIN
1480 then do on_block
1481 else throwErrno loc
1482 else return res
1483
1484 -- -----------------------------------------------------------------------------
1485 -- wrappers to platform-specific constants:
1486
1487 foreign import ccall unsafe "__hscore_supportsTextMode"
1488 tEXT_MODE_SEEK_ALLOWED :: Bool
1489
1490 foreign import ccall unsafe "__hscore_bufsiz" dEFAULT_BUFFER_SIZE :: Int
1491 foreign import ccall unsafe "__hscore_seek_cur" sEEK_CUR :: CInt
1492 foreign import ccall unsafe "__hscore_seek_set" sEEK_SET :: CInt
1493 foreign import ccall unsafe "__hscore_seek_end" sEEK_END :: CInt