1 {-# OPTIONS_GHC -XNoImplicitPrelude -XBangPatterns #-}
2 {-# OPTIONS_HADDOCK hide #-}
3 -----------------------------------------------------------------------------
6 -- Copyright : (c) The University of Glasgow, 1994-2008
7 -- License : see libraries/base/LICENSE
9 -- Maintainer : libraries@haskell.org
10 -- Stability : internal
11 -- Portability : non-portable
13 -- Raw read/write operations on file descriptors
15 -----------------------------------------------------------------------------
19 openFile, mkFD, release,
21 readRawBufferPtr, readRawBufferPtrNoBlock, writeRawBufferPtr,
39 import GHC.IO.BufferedIO
40 import qualified GHC.IO.Device
41 import GHC.IO.Device (SeekMode(..), IODeviceType(..))
43 import GHC.IO.Exception
47 import qualified System.Posix.Internals
48 import System.Posix.Internals hiding (FD, setEcho, getEcho)
49 import System.Posix.Types
52 -- -----------------------------------------------------------------------------
53 -- The file-descriptor IO device
56 fdFD :: {-# UNPACK #-} !CInt,
57 #ifdef mingw32_HOST_OS
58 -- On Windows, a socket file descriptor needs to be read and written
59 -- using different functions (send/recv).
60 fdIsSocket_ :: {-# UNPACK #-} !Int
62 -- On Unix we need to know whether this FD has O_NONBLOCK set.
63 -- If it has, then we can use more efficient routines to read/write to it.
64 -- It is always safe for this to be off.
65 fdIsNonBlocking :: {-# UNPACK #-} !Int
70 #ifdef mingw32_HOST_OS
71 fdIsSocket :: FD -> Bool
72 fdIsSocket fd = fdIsSocket_ fd /= 0
75 instance Show FD where
76 show fd = show (fdFD fd)
78 instance GHC.IO.Device.RawIO FD where
80 readNonBlocking = fdReadNonBlocking
82 writeNonBlocking = fdWriteNonBlocking
84 instance GHC.IO.Device.IODevice FD where
87 isTerminal = isTerminal
88 isSeekable = isSeekable
100 instance BufferedIO FD where
101 newBuffer _dev state = newByteBuffer dEFAULT_BUFFER_SIZE state
102 fillReadBuffer fd buf = readBuf' fd buf
103 fillReadBuffer0 fd buf = readBufNonBlocking fd buf
104 flushWriteBuffer fd buf = writeBuf' fd buf
105 flushWriteBuffer0 fd buf = writeBufNonBlocking fd buf
107 readBuf' :: FD -> Buffer Word8 -> IO (Int, Buffer Word8)
110 puts ("readBuf fd=" ++ show fd ++ " " ++ summaryBuffer buf ++ "\n")
112 (r,buf') <- readBuf fd buf
114 puts ("after: " ++ summaryBuffer buf' ++ "\n")
118 writeBuf' :: FD -> Buffer Word8 -> IO ()
119 writeBuf' fd buf = do
121 puts ("writeBuf fd=" ++ show fd ++ " " ++ summaryBuffer buf ++ "\n")
125 -- -----------------------------------------------------------------------------
128 -- | Open a file and make an 'FD' for it. Truncates the file to zero
129 -- size when the `IOMode` is `WriteMode`. Puts the file descriptor
130 -- into non-blocking mode on Unix systems.
131 openFile :: FilePath -> IOMode -> IO (FD,IODeviceType)
132 openFile filepath iomode =
133 withFilePath filepath $ \ f ->
136 oflags1 = case iomode of
137 ReadMode -> read_flags
138 #ifdef mingw32_HOST_OS
139 WriteMode -> write_flags .|. o_TRUNC
141 WriteMode -> write_flags
143 ReadWriteMode -> rw_flags
144 AppendMode -> append_flags
146 #ifdef mingw32_HOST_OS
147 binary_flags = o_BINARY
152 oflags = oflags1 .|. binary_flags
155 -- the old implementation had a complicated series of three opens,
156 -- which is perhaps because we have to be careful not to open
157 -- directories. However, the man pages I've read say that open()
158 -- always returns EISDIR if the file is a directory and was opened
159 -- for writing, so I think we're ok with a single open() here...
160 fd <- throwErrnoIfMinus1Retry "openFile"
161 (c_open f (fromIntegral oflags) 0o666)
163 (fD,fd_type) <- mkFD fd iomode Nothing{-no stat-}
164 False{-not a socket-}
165 True{-is non-blocking-}
166 `catchAny` \e -> do c_close fd; throwIO e
168 #ifndef mingw32_HOST_OS
169 -- we want to truncate() if this is an open in WriteMode, but only
170 -- if the target is a RegularFile. ftruncate() fails on special files
172 if iomode == WriteMode && fd_type == RegularFile
179 std_flags, output_flags, read_flags, write_flags, rw_flags,
181 std_flags = o_NONBLOCK .|. o_NOCTTY
182 output_flags = std_flags .|. o_CREAT
183 read_flags = std_flags .|. o_RDONLY
184 write_flags = output_flags .|. o_WRONLY
185 rw_flags = output_flags .|. o_RDWR
186 append_flags = write_flags .|. o_APPEND
189 -- | Make a 'FD' from an existing file descriptor. Fails if the FD
190 -- refers to a directory. If the FD refers to a file, `mkFD` locks
191 -- the file according to the Haskell 98 single writer/multiple reader
192 -- locking semantics (this is why we need the `IOMode` argument too).
195 -> Maybe (IODeviceType, CDev, CIno)
196 -- the results of fdStat if we already know them, or we want
197 -- to prevent fdToHandle_stat from doing its own stat.
198 -- These are used for:
199 -- - we fail if the FD refers to a directory
200 -- - if the FD refers to a file, we lock it using (cdev,cino)
201 -> Bool -- ^ is a socket (on Windows)
202 -> Bool -- ^ is in non-blocking mode on Unix
203 -> IO (FD,IODeviceType)
205 mkFD fd iomode mb_stat is_socket is_nonblock = do
207 let _ = (is_socket, is_nonblock) -- warning suppression
212 Just stat -> return stat
214 let write = case iomode of
218 #ifdef mingw32_HOST_OS
219 let _ = (dev,ino,write,fd) -- warning suppression
224 ioException (IOError Nothing InappropriateType "openFile"
225 "is a directory" Nothing Nothing)
227 #ifndef mingw32_HOST_OS
228 -- regular files need to be locked
230 -- On Windows we use explicit exclusion via sopen() to implement
231 -- this locking (see __hscore_open()); on Unix we have to
232 -- implment it in the RTS.
233 r <- lockFile fd dev ino (fromBool write)
235 ioException (IOError Nothing ResourceBusy "openFile"
236 "file is locked" Nothing Nothing)
239 _other_type -> return ()
241 return (FD{ fdFD = fd,
242 #ifndef mingw32_HOST_OS
243 fdIsNonBlocking = fromEnum is_nonblock
245 fdIsSocket_ = fromEnum is_socket
250 -- -----------------------------------------------------------------------------
251 -- Standard file descriptors
254 stdFD fd = FD { fdFD = fd,
255 #ifdef mingw32_HOST_OS
259 -- We don't set non-blocking mode on standard handles, because it may
260 -- confuse other applications attached to the same TTY/pipe
261 -- see Note [nonblock]
265 stdin, stdout, stderr :: FD
270 -- -----------------------------------------------------------------------------
271 -- Operations on file descriptors
275 #ifndef mingw32_HOST_OS
276 (flip finally) (release fd) $ do
278 throwErrnoIfMinus1Retry_ "GHC.IO.FD.close" $
279 #ifdef mingw32_HOST_OS
280 if fdIsSocket fd then
281 c_closesocket (fdFD fd)
286 release :: FD -> IO ()
288 #ifndef mingw32_HOST_OS
291 let _ = fd -- warning suppression
294 #ifdef mingw32_HOST_OS
295 foreign import stdcall unsafe "HsBase.h closesocket"
296 c_closesocket :: CInt -> IO CInt
299 isSeekable :: FD -> IO Bool
302 return (t == RegularFile || t == RawDevice)
304 seek :: FD -> SeekMode -> Integer -> IO ()
305 seek fd mode off = do
306 throwErrnoIfMinus1Retry "seek" $
307 c_lseek (fdFD fd) (fromIntegral off) seektype
311 seektype = case mode of
312 AbsoluteSeek -> sEEK_SET
313 RelativeSeek -> sEEK_CUR
314 SeekFromEnd -> sEEK_END
316 tell :: FD -> IO Integer
319 (throwErrnoIfMinus1Retry "hGetPosn" $
320 c_lseek (fdFD fd) 0 sEEK_CUR)
322 getSize :: FD -> IO Integer
323 getSize fd = fdFileSize (fdFD fd)
325 setSize :: FD -> Integer -> IO ()
327 throwErrnoIf (/=0) "GHC.IO.FD.setSize" $
328 c_ftruncate (fdFD fd) (fromIntegral size)
331 devType :: FD -> IO IODeviceType
332 devType fd = do (ty,_,_) <- fdStat (fdFD fd); return ty
336 newfd <- throwErrnoIfMinus1 "GHC.IO.FD.dup" $ c_dup (fdFD fd)
337 return fd{ fdFD = newfd }
339 dup2 :: FD -> FD -> IO FD
341 -- Windows' dup2 does not return the new descriptor, unlike Unix
342 throwErrnoIfMinus1 "GHC.IO.FD.dup2" $
343 c_dup2 (fdFD fd) (fdFD fdto)
344 return fd{ fdFD = fdFD fdto } -- original FD, with the new fdFD
346 setNonBlockingMode :: FD -> IO ()
347 setNonBlockingMode fd = setNonBlockingFD (fdFD fd)
349 ready :: FD -> Bool -> Int -> IO Bool
350 ready fd write msecs = do
351 r <- throwErrnoIfMinus1Retry "GHC.IO.FD.ready" $
352 fdReady (fdFD fd) (fromIntegral $ fromEnum $ write)
354 #if defined(mingw32_HOST_OS)
355 (fromIntegral $ fromEnum $ fdIsSocket fd)
359 return (toEnum (fromIntegral r))
361 foreign import ccall safe "fdReady"
362 fdReady :: CInt -> CInt -> CInt -> CInt -> IO CInt
364 -- ---------------------------------------------------------------------------
365 -- Terminal-related stuff
367 isTerminal :: FD -> IO Bool
368 isTerminal fd = c_isatty (fdFD fd) >>= return.toBool
370 setEcho :: FD -> Bool -> IO ()
371 setEcho fd on = System.Posix.Internals.setEcho (fdFD fd) on
373 getEcho :: FD -> IO Bool
374 getEcho fd = System.Posix.Internals.getEcho (fdFD fd)
376 setRaw :: FD -> Bool -> IO ()
377 setRaw fd raw = System.Posix.Internals.setCooked (fdFD fd) (not raw)
379 -- -----------------------------------------------------------------------------
380 -- Reading and Writing
382 fdRead :: FD -> Ptr Word8 -> Int -> IO Int
383 fdRead fd ptr bytes = do
384 r <- readRawBufferPtr "GHC.IO.FD.fdRead" fd ptr 0 (fromIntegral bytes)
385 return (fromIntegral r)
387 fdReadNonBlocking :: FD -> Ptr Word8 -> Int -> IO (Maybe Int)
388 fdReadNonBlocking fd ptr bytes = do
389 r <- readRawBufferPtrNoBlock "GHC.IO.FD.fdReadNonBlocking" fd ptr
390 0 (fromIntegral bytes)
392 (-1) -> return (Nothing)
393 n -> return (Just (fromIntegral n))
396 fdWrite :: FD -> Ptr Word8 -> Int -> IO ()
397 fdWrite fd ptr bytes = do
398 res <- writeRawBufferPtr "GHC.IO.FD.fdWrite" fd ptr 0 (fromIntegral bytes)
399 let res' = fromIntegral res
401 then fdWrite fd (ptr `plusPtr` res') (bytes - res')
404 -- XXX ToDo: this isn't non-blocking
405 fdWriteNonBlocking :: FD -> Ptr Word8 -> Int -> IO Int
406 fdWriteNonBlocking fd ptr bytes = do
407 res <- writeRawBufferPtrNoBlock "GHC.IO.FD.fdWriteNonBlocking" fd ptr 0
409 return (fromIntegral res)
411 -- -----------------------------------------------------------------------------
414 -- Low level routines for reading/writing to (raw)buffers:
416 #ifndef mingw32_HOST_OS
421 Unix has broken semantics when it comes to non-blocking I/O: you can
422 set the O_NONBLOCK flag on an FD, but it applies to the all other FDs
423 attached to the same underlying file, pipe or TTY; there's no way to
424 have private non-blocking behaviour for an FD. See bug #724.
426 We fix this by only setting O_NONBLOCK on FDs that we create; FDs that
427 come from external sources or are exposed externally are left in
428 blocking mode. This solution has some problems though. We can't
429 completely simulate a non-blocking read without O_NONBLOCK: several
430 cases are wrong here. The cases that are wrong:
432 * reading/writing to a blocking FD in non-threaded mode.
433 In threaded mode, we just make a safe call to read().
434 In non-threaded mode we call select() before attempting to read,
435 but that leaves a small race window where the data can be read
436 from the file descriptor before we issue our blocking read().
437 * readRawBufferNoBlock for a blocking FD
441 In the threaded RTS we could just make safe calls to read()/write()
442 for file descriptors in blocking mode without worrying about blocking
443 other threads, but the problem with this is that the thread will be
444 uninterruptible while it is blocked in the foreign call. See #2363.
445 So now we always call fdReady() before reading, and if fdReady
446 indicates that there's no data, we call threadWaitRead.
450 readRawBufferPtr :: String -> FD -> Ptr Word8 -> Int -> CSize -> IO Int
451 readRawBufferPtr loc !fd buf off len
452 | isNonBlocking fd = unsafe_read -- unsafe is ok, it can't block
453 | otherwise = do r <- throwErrnoIfMinus1 loc
454 (unsafe_fdReady (fdFD fd) 0 0 0)
457 else do threadWaitRead (fromIntegral (fdFD fd)); read
459 do_read call = fromIntegral `fmap`
460 throwErrnoIfMinus1RetryMayBlock loc call
461 (threadWaitRead (fromIntegral (fdFD fd)))
462 read = if threaded then safe_read else unsafe_read
463 unsafe_read = do_read (c_read (fdFD fd) (buf `plusPtr` off) len)
464 safe_read = do_read (c_safe_read (fdFD fd) (buf `plusPtr` off) len)
466 -- return: -1 indicates EOF, >=0 is bytes read
467 readRawBufferPtrNoBlock :: String -> FD -> Ptr Word8 -> Int -> CSize -> IO Int
468 readRawBufferPtrNoBlock loc !fd buf off len
469 | isNonBlocking fd = unsafe_read -- unsafe is ok, it can't block
470 | otherwise = do r <- unsafe_fdReady (fdFD fd) 0 0 0
471 if r /= 0 then safe_read
473 -- XXX see note [nonblock]
475 do_read call = do r <- throwErrnoIfMinus1RetryOnBlock loc call (return (-1))
479 n -> return (fromIntegral n)
480 unsafe_read = do_read (c_read (fdFD fd) (buf `plusPtr` off) len)
481 safe_read = do_read (c_safe_read (fdFD fd) (buf `plusPtr` off) len)
483 writeRawBufferPtr :: String -> FD -> Ptr Word8 -> Int -> CSize -> IO CInt
484 writeRawBufferPtr loc !fd buf off len
485 | isNonBlocking fd = unsafe_write -- unsafe is ok, it can't block
486 | otherwise = do r <- unsafe_fdReady (fdFD fd) 1 0 0
489 else do threadWaitWrite (fromIntegral (fdFD fd)); write
491 do_write call = fromIntegral `fmap`
492 throwErrnoIfMinus1RetryMayBlock loc call
493 (threadWaitWrite (fromIntegral (fdFD fd)))
494 write = if threaded then safe_write else unsafe_write
495 unsafe_write = do_write (c_write (fdFD fd) (buf `plusPtr` off) len)
496 safe_write = do_write (c_safe_write (fdFD fd) (buf `plusPtr` off) len)
498 writeRawBufferPtrNoBlock :: String -> FD -> Ptr Word8 -> Int -> CSize -> IO CInt
499 writeRawBufferPtrNoBlock loc !fd buf off len
500 | isNonBlocking fd = unsafe_write -- unsafe is ok, it can't block
501 | otherwise = do r <- unsafe_fdReady (fdFD fd) 1 0 0
505 do_write call = do r <- throwErrnoIfMinus1RetryOnBlock loc call (return (-1))
508 n -> return (fromIntegral n)
509 write = if threaded then safe_write else unsafe_write
510 unsafe_write = do_write (c_write (fdFD fd) (buf `plusPtr` off) len)
511 safe_write = do_write (c_safe_write (fdFD fd) (buf `plusPtr` off) len)
513 isNonBlocking :: FD -> Bool
514 isNonBlocking fd = fdIsNonBlocking fd /= 0
516 foreign import ccall unsafe "fdReady"
517 unsafe_fdReady :: CInt -> CInt -> CInt -> CInt -> IO CInt
519 #else /* mingw32_HOST_OS.... */
521 readRawBufferPtr :: String -> FD -> Ptr Word8 -> Int -> CSize -> IO CInt
522 readRawBufferPtr loc !fd buf off len
523 | threaded = blockingReadRawBufferPtr loc fd buf off len
524 | otherwise = asyncReadRawBufferPtr loc fd buf off len
526 writeRawBufferPtr :: String -> FD -> Ptr Word8 -> Int -> CSize -> IO CInt
527 writeRawBufferPtr loc !fd buf off len
528 | threaded = blockingWriteRawBufferPtr loc fd buf off len
529 | otherwise = asyncWriteRawBufferPtr loc fd buf off len
531 readRawBufferPtrNoBlock :: String -> FD -> Ptr Word8 -> Int -> CSize -> IO CInt
532 readRawBufferPtrNoBlock = readRawBufferPtr
534 writeRawBufferPtrNoBlock :: String -> FD -> Ptr Word8 -> Int -> CSize -> IO CInt
535 writeRawBufferPtrNoBlock = writeRawBufferPtr
537 -- Async versions of the read/write primitives, for the non-threaded RTS
539 asyncReadRawBufferPtr :: String -> FD -> Ptr Word8 -> Int -> CSize -> IO CInt
540 asyncReadRawBufferPtr loc !fd buf off len = do
541 (l, rc) <- asyncRead (fromIntegral (fdFD fd)) (fdIsSocket_ fd)
542 (fromIntegral len) (buf `plusPtr` off)
545 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
546 else return (fromIntegral l)
548 asyncWriteRawBufferPtr :: String -> FD -> Ptr Word8 -> Int -> CSize -> IO CInt
549 asyncWriteRawBufferPtr loc !fd buf off len = do
550 (l, rc) <- asyncWrite (fromIntegral (fdFD fd)) (fdIsSocket_ fd)
551 (fromIntegral len) (buf `plusPtr` off)
554 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
555 else return (fromIntegral l)
557 -- Blocking versions of the read/write primitives, for the threaded RTS
559 blockingReadRawBufferPtr :: String -> FD -> Ptr Word8 -> Int -> CSize -> IO CInt
560 blockingReadRawBufferPtr loc fd buf off len
561 = fmap fromIntegral $ throwErrnoIfMinus1Retry loc $
563 then c_safe_recv (fdFD fd) (buf `plusPtr` off) len 0
564 else c_safe_read (fdFD fd) (buf `plusPtr` off) len
566 blockingWriteRawBufferPtr :: String -> FD -> Ptr Word8-> Int -> CSize -> IO CInt
567 blockingWriteRawBufferPtr loc fd buf off len
568 = fmap fromIntegral $ throwErrnoIfMinus1Retry loc $
570 then c_safe_send (fdFD fd) (buf `plusPtr` off) len 0
571 else c_safe_write (fdFD fd) (buf `plusPtr` off) len
573 -- NOTE: "safe" versions of the read/write calls for use by the threaded RTS.
574 -- These calls may block, but that's ok.
576 foreign import stdcall safe "recv"
577 c_safe_recv :: CInt -> Ptr Word8 -> CSize -> CInt{-flags-} -> IO CSsize
579 foreign import stdcall safe "send"
580 c_safe_send :: CInt -> Ptr Word8 -> CSize -> CInt{-flags-} -> IO CSsize
584 foreign import ccall "rtsSupportsBoundThreads" threaded :: Bool
586 -- -----------------------------------------------------------------------------
589 #ifndef mingw32_HOST_OS
590 throwErrnoIfMinus1RetryOnBlock :: String -> IO CSsize -> IO CSsize -> IO CSsize
591 throwErrnoIfMinus1RetryOnBlock loc f on_block =
594 if (res :: CSsize) == -1
598 then throwErrnoIfMinus1RetryOnBlock loc f on_block
599 else if err == eWOULDBLOCK || err == eAGAIN
605 -- -----------------------------------------------------------------------------
608 #ifndef mingw32_HOST_OS
609 foreign import ccall unsafe "lockFile"
610 lockFile :: CInt -> CDev -> CIno -> CInt -> IO CInt
612 foreign import ccall unsafe "unlockFile"
613 unlockFile :: CInt -> IO CInt
616 #if defined(DEBUG_DUMP)
617 puts :: String -> IO ()
618 puts s = do withCStringLen s $ \(p,len) -> c_write 1 p (fromIntegral len)