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 -> Bool -> IO FD
347 setNonBlockingMode fd set = do
348 setNonBlockingFD (fdFD fd) set
349 return fd{ fdIsNonBlocking = fromEnum set }
351 ready :: FD -> Bool -> Int -> IO Bool
352 ready fd write msecs = do
353 r <- throwErrnoIfMinus1Retry "GHC.IO.FD.ready" $
354 fdReady (fdFD fd) (fromIntegral $ fromEnum $ write)
356 #if defined(mingw32_HOST_OS)
357 (fromIntegral $ fromEnum $ fdIsSocket fd)
361 return (toEnum (fromIntegral r))
363 foreign import ccall safe "fdReady"
364 fdReady :: CInt -> CInt -> CInt -> CInt -> IO CInt
366 -- ---------------------------------------------------------------------------
367 -- Terminal-related stuff
369 isTerminal :: FD -> IO Bool
370 isTerminal fd = c_isatty (fdFD fd) >>= return.toBool
372 setEcho :: FD -> Bool -> IO ()
373 setEcho fd on = System.Posix.Internals.setEcho (fdFD fd) on
375 getEcho :: FD -> IO Bool
376 getEcho fd = System.Posix.Internals.getEcho (fdFD fd)
378 setRaw :: FD -> Bool -> IO ()
379 setRaw fd raw = System.Posix.Internals.setCooked (fdFD fd) (not raw)
381 -- -----------------------------------------------------------------------------
382 -- Reading and Writing
384 fdRead :: FD -> Ptr Word8 -> Int -> IO Int
385 fdRead fd ptr bytes = do
386 r <- readRawBufferPtr "GHC.IO.FD.fdRead" fd ptr 0 (fromIntegral bytes)
387 return (fromIntegral r)
389 fdReadNonBlocking :: FD -> Ptr Word8 -> Int -> IO (Maybe Int)
390 fdReadNonBlocking fd ptr bytes = do
391 r <- readRawBufferPtrNoBlock "GHC.IO.FD.fdReadNonBlocking" fd ptr
392 0 (fromIntegral bytes)
394 (-1) -> return (Nothing)
395 n -> return (Just (fromIntegral n))
398 fdWrite :: FD -> Ptr Word8 -> Int -> IO ()
399 fdWrite fd ptr bytes = do
400 res <- writeRawBufferPtr "GHC.IO.FD.fdWrite" fd ptr 0 (fromIntegral bytes)
401 let res' = fromIntegral res
403 then fdWrite fd (ptr `plusPtr` res') (bytes - res')
406 -- XXX ToDo: this isn't non-blocking
407 fdWriteNonBlocking :: FD -> Ptr Word8 -> Int -> IO Int
408 fdWriteNonBlocking fd ptr bytes = do
409 res <- writeRawBufferPtrNoBlock "GHC.IO.FD.fdWriteNonBlocking" fd ptr 0
411 return (fromIntegral res)
413 -- -----------------------------------------------------------------------------
416 -- Low level routines for reading/writing to (raw)buffers:
418 #ifndef mingw32_HOST_OS
423 Unix has broken semantics when it comes to non-blocking I/O: you can
424 set the O_NONBLOCK flag on an FD, but it applies to the all other FDs
425 attached to the same underlying file, pipe or TTY; there's no way to
426 have private non-blocking behaviour for an FD. See bug #724.
428 We fix this by only setting O_NONBLOCK on FDs that we create; FDs that
429 come from external sources or are exposed externally are left in
430 blocking mode. This solution has some problems though. We can't
431 completely simulate a non-blocking read without O_NONBLOCK: several
432 cases are wrong here. The cases that are wrong:
434 * reading/writing to a blocking FD in non-threaded mode.
435 In threaded mode, we just make a safe call to read().
436 In non-threaded mode we call select() before attempting to read,
437 but that leaves a small race window where the data can be read
438 from the file descriptor before we issue our blocking read().
439 * readRawBufferNoBlock for a blocking FD
443 In the threaded RTS we could just make safe calls to read()/write()
444 for file descriptors in blocking mode without worrying about blocking
445 other threads, but the problem with this is that the thread will be
446 uninterruptible while it is blocked in the foreign call. See #2363.
447 So now we always call fdReady() before reading, and if fdReady
448 indicates that there's no data, we call threadWaitRead.
452 readRawBufferPtr :: String -> FD -> Ptr Word8 -> Int -> CSize -> IO Int
453 readRawBufferPtr loc !fd buf off len
454 | isNonBlocking fd = unsafe_read -- unsafe is ok, it can't block
455 | otherwise = do r <- throwErrnoIfMinus1 loc
456 (unsafe_fdReady (fdFD fd) 0 0 0)
459 else do threadWaitRead (fromIntegral (fdFD fd)); read
461 do_read call = fromIntegral `fmap`
462 throwErrnoIfMinus1RetryMayBlock loc call
463 (threadWaitRead (fromIntegral (fdFD fd)))
464 read = if threaded then safe_read else unsafe_read
465 unsafe_read = do_read (c_read (fdFD fd) (buf `plusPtr` off) len)
466 safe_read = do_read (c_safe_read (fdFD fd) (buf `plusPtr` off) len)
468 -- return: -1 indicates EOF, >=0 is bytes read
469 readRawBufferPtrNoBlock :: String -> FD -> Ptr Word8 -> Int -> CSize -> IO Int
470 readRawBufferPtrNoBlock loc !fd buf off len
471 | isNonBlocking fd = unsafe_read -- unsafe is ok, it can't block
472 | otherwise = do r <- unsafe_fdReady (fdFD fd) 0 0 0
473 if r /= 0 then safe_read
475 -- XXX see note [nonblock]
477 do_read call = do r <- throwErrnoIfMinus1RetryOnBlock loc call (return (-1))
481 n -> return (fromIntegral n)
482 unsafe_read = do_read (c_read (fdFD fd) (buf `plusPtr` off) len)
483 safe_read = do_read (c_safe_read (fdFD fd) (buf `plusPtr` off) len)
485 writeRawBufferPtr :: String -> FD -> Ptr Word8 -> Int -> CSize -> IO CInt
486 writeRawBufferPtr loc !fd buf off len
487 | isNonBlocking fd = unsafe_write -- unsafe is ok, it can't block
488 | otherwise = do r <- unsafe_fdReady (fdFD fd) 1 0 0
491 else do threadWaitWrite (fromIntegral (fdFD fd)); write
493 do_write call = fromIntegral `fmap`
494 throwErrnoIfMinus1RetryMayBlock loc call
495 (threadWaitWrite (fromIntegral (fdFD fd)))
496 write = if threaded then safe_write else unsafe_write
497 unsafe_write = do_write (c_write (fdFD fd) (buf `plusPtr` off) len)
498 safe_write = do_write (c_safe_write (fdFD fd) (buf `plusPtr` off) len)
500 writeRawBufferPtrNoBlock :: String -> FD -> Ptr Word8 -> Int -> CSize -> IO CInt
501 writeRawBufferPtrNoBlock loc !fd buf off len
502 | isNonBlocking fd = unsafe_write -- unsafe is ok, it can't block
503 | otherwise = do r <- unsafe_fdReady (fdFD fd) 1 0 0
507 do_write call = do r <- throwErrnoIfMinus1RetryOnBlock loc call (return (-1))
510 n -> return (fromIntegral n)
511 write = if threaded then safe_write else unsafe_write
512 unsafe_write = do_write (c_write (fdFD fd) (buf `plusPtr` off) len)
513 safe_write = do_write (c_safe_write (fdFD fd) (buf `plusPtr` off) len)
515 isNonBlocking :: FD -> Bool
516 isNonBlocking fd = fdIsNonBlocking fd /= 0
518 foreign import ccall unsafe "fdReady"
519 unsafe_fdReady :: CInt -> CInt -> CInt -> CInt -> IO CInt
521 #else /* mingw32_HOST_OS.... */
523 readRawBufferPtr :: String -> FD -> Ptr Word8 -> Int -> CSize -> IO CInt
524 readRawBufferPtr loc !fd buf off len
525 | threaded = blockingReadRawBufferPtr loc fd buf off len
526 | otherwise = asyncReadRawBufferPtr loc fd buf off len
528 writeRawBufferPtr :: String -> FD -> Ptr Word8 -> Int -> CSize -> IO CInt
529 writeRawBufferPtr loc !fd buf off len
530 | threaded = blockingWriteRawBufferPtr loc fd buf off len
531 | otherwise = asyncWriteRawBufferPtr loc fd buf off len
533 readRawBufferPtrNoBlock :: String -> FD -> Ptr Word8 -> Int -> CSize -> IO CInt
534 readRawBufferPtrNoBlock = readRawBufferPtr
536 writeRawBufferPtrNoBlock :: String -> FD -> Ptr Word8 -> Int -> CSize -> IO CInt
537 writeRawBufferPtrNoBlock = writeRawBufferPtr
539 -- Async versions of the read/write primitives, for the non-threaded RTS
541 asyncReadRawBufferPtr :: String -> FD -> Ptr Word8 -> Int -> CSize -> IO CInt
542 asyncReadRawBufferPtr loc !fd buf off len = do
543 (l, rc) <- asyncRead (fromIntegral (fdFD fd)) (fdIsSocket_ fd)
544 (fromIntegral len) (buf `plusPtr` off)
547 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
548 else return (fromIntegral l)
550 asyncWriteRawBufferPtr :: String -> FD -> Ptr Word8 -> Int -> CSize -> IO CInt
551 asyncWriteRawBufferPtr loc !fd buf off len = do
552 (l, rc) <- asyncWrite (fromIntegral (fdFD fd)) (fdIsSocket_ fd)
553 (fromIntegral len) (buf `plusPtr` off)
556 ioError (errnoToIOError loc (Errno (fromIntegral rc)) Nothing Nothing)
557 else return (fromIntegral l)
559 -- Blocking versions of the read/write primitives, for the threaded RTS
561 blockingReadRawBufferPtr :: String -> FD -> Ptr Word8 -> Int -> CSize -> IO CInt
562 blockingReadRawBufferPtr loc fd buf off len
563 = fmap fromIntegral $ throwErrnoIfMinus1Retry loc $
565 then c_safe_recv (fdFD fd) (buf `plusPtr` off) len 0
566 else c_safe_read (fdFD fd) (buf `plusPtr` off) len
568 blockingWriteRawBufferPtr :: String -> FD -> Ptr Word8-> Int -> CSize -> IO CInt
569 blockingWriteRawBufferPtr loc fd buf off len
570 = fmap fromIntegral $ throwErrnoIfMinus1Retry loc $
572 then c_safe_send (fdFD fd) (buf `plusPtr` off) len 0
573 else c_safe_write (fdFD fd) (buf `plusPtr` off) len
575 -- NOTE: "safe" versions of the read/write calls for use by the threaded RTS.
576 -- These calls may block, but that's ok.
578 foreign import stdcall safe "recv"
579 c_safe_recv :: CInt -> Ptr Word8 -> CSize -> CInt{-flags-} -> IO CSsize
581 foreign import stdcall safe "send"
582 c_safe_send :: CInt -> Ptr Word8 -> CSize -> CInt{-flags-} -> IO CSsize
586 foreign import ccall "rtsSupportsBoundThreads" threaded :: Bool
588 -- -----------------------------------------------------------------------------
591 #ifndef mingw32_HOST_OS
592 throwErrnoIfMinus1RetryOnBlock :: String -> IO CSsize -> IO CSsize -> IO CSsize
593 throwErrnoIfMinus1RetryOnBlock loc f on_block =
596 if (res :: CSsize) == -1
600 then throwErrnoIfMinus1RetryOnBlock loc f on_block
601 else if err == eWOULDBLOCK || err == eAGAIN
607 -- -----------------------------------------------------------------------------
610 #ifndef mingw32_HOST_OS
611 foreign import ccall unsafe "lockFile"
612 lockFile :: CInt -> CDev -> CIno -> CInt -> IO CInt
614 foreign import ccall unsafe "unlockFile"
615 unlockFile :: CInt -> IO CInt
618 #if defined(DEBUG_DUMP)
619 puts :: String -> IO ()
620 puts s = do withCStringLen s $ \(p,len) -> c_write 1 p (fromIntegral len)