commitBuffer', -- hack, see below
hGetcBuffered, -- needed by ghc/compiler/utils/StringBuffer.lhs
hGetBuf, hGetBufNonBlocking, hPutBuf, hPutBufNonBlocking, slurpFile,
-{- NOTE: As far as I can tell, not defined.
- createPipe, createPipeEx,
--}
memcpy_ba_baoff,
memcpy_ptr_baoff,
memcpy_baoff_ba,
import GHC.Show
import GHC.List
import GHC.Exception ( ioError, catch )
-import GHC.Conc
-- ---------------------------------------------------------------------------
-- Simple input operations
-- It returns 'True' as soon as input is available on @hdl@,
-- or 'False' if no input is available within @t@ milliseconds.
--
+-- If @t@ is less than zero, then @hWaitForInput@ waits indefinitely.
+-- NOTE: in the current implementation, this is the only case that works
+-- correctly (if @t@ is non-zero, then all other concurrent threads are
+-- blocked until data is available).
+--
-- This operation may fail with:
--
-- * 'isEOFError' if the end of file has been reached.
then return True
else do
- r <- throwErrnoIfMinus1Retry "hWaitForInput"
- (inputReady (fromIntegral (haFD handle_)) (fromIntegral msecs) (haIsStream handle_))
- return (r /= 0)
+ if msecs < 0
+ then do buf' <- fillReadBuffer (haFD handle_) True
+ (haIsStream handle_) buf
+ writeIORef ref buf'
+ return True
+ else do r <- throwErrnoIfMinus1Retry "hWaitForInput" $
+ inputReady (fromIntegral (haFD handle_))
+ (fromIntegral msecs) (haIsStream handle_)
+ return (r /= 0)
foreign import ccall unsafe "inputReady"
inputReady :: CInt -> CInt -> Bool -> IO CInt
-- is closed, 'hGetBuf' will behave as if EOF was reached.
hGetBuf :: Handle -> Ptr a -> Int -> IO Int
-hGetBuf h ptr count = hGetBuf' h ptr count True
-
-hGetBufNonBlocking :: Handle -> Ptr a -> Int -> IO Int
-hGetBufNonBlocking h ptr count = hGetBuf' h ptr count False
-
-hGetBuf' :: Handle -> Ptr a -> Int -> Bool -> IO Int
-hGetBuf' handle ptr count can_block
+hGetBuf h ptr count
| count == 0 = return 0
- | count < 0 = illegalBufferSize handle "hGetBuf" count
+ | count < 0 = illegalBufferSize h "hGetBuf" count
| otherwise =
- wantReadableHandle "hGetBuf" handle $
+ wantReadableHandle "hGetBuf" h $
\ handle_@Handle__{ haFD=fd, haBuffer=ref, haIsStream=is_stream } -> do
- bufRead fd ref is_stream ptr 0 count can_block
+ bufRead fd ref is_stream ptr 0 count
-bufRead fd ref is_stream ptr so_far count can_block =
+-- small reads go through the buffer, large reads are satisfied by
+-- taking data first from the buffer and then direct from the file
+-- descriptor.
+bufRead fd ref is_stream ptr so_far count =
seq fd $ seq so_far $ seq count $ do -- strictness hack
buf@Buffer{ bufBuf=raw, bufWPtr=w, bufRPtr=r, bufSize=sz } <- readIORef ref
if bufferEmpty buf
- then if so_far > 0 then return so_far else
- if count < sz
- then do
- mb_buf <- maybeFillReadBuffer fd (not can_block) is_stream buf
- case mb_buf of
- Nothing -> return 0
- Just new_buf -> do
- writeIORef ref new_buf
- bufRead fd ref is_stream ptr so_far count can_block
- else if can_block
- then readChunk fd is_stream ptr count
- else readChunkNonBlocking fd is_stream ptr count
+ then if count > sz -- small read?
+ then do rest <- readChunk fd is_stream ptr count
+ return (so_far + rest)
+ else do mb_buf <- maybeFillReadBuffer fd True is_stream buf
+ case mb_buf of
+ Nothing -> return so_far -- got nothing, we're done
+ Just new_buf -> do
+ writeIORef ref new_buf
+ bufRead fd ref is_stream ptr so_far count
else do
- let avail = w - r
+ let avail = w - r
if (count == avail)
then do
memcpy_ptr_baoff ptr raw r (fromIntegral count)
writeIORef ref buf{ bufRPtr = r + count }
return (so_far + count)
else do
-
- memcpy_ptr_baoff ptr raw r (fromIntegral avail)
- writeIORef ref buf{ bufWPtr=0, bufRPtr=0 }
-
+
let remaining = count - avail
so_far' = so_far + avail
ptr' = ptr `plusPtr` avail
if remaining < sz
- then bufRead fd ref is_stream ptr' so_far' remaining can_block
+ then bufRead fd ref is_stream ptr' so_far' remaining
else do
- rest <- if can_block
- then readChunk fd is_stream ptr' remaining
- else readChunkNonBlocking fd is_stream ptr' remaining
+ rest <- readChunk fd is_stream ptr' remaining
return (so_far' + rest)
readChunk :: FD -> Bool -> Ptr a -> Int -> IO Int
then return off
else loop (off + r) (bytes - r)
+
+-- | 'hGetBufNonBlocking' @hdl buf count@ reads data from the handle @hdl@
+-- into the buffer @buf@ until either EOF is reached, or
+-- @count@ 8-bit bytes have been read, or there is no more data available
+-- to read immediately.
+--
+-- 'hGetBufNonBlocking' is identical to 'hGetBuf', except that it will
+-- never block waiting for data to become available, instead it returns
+-- only whatever data is available. To wait for data to arrive before
+-- calling 'hGetBufNonBlocking', use 'hWaitForInput'.
+--
+-- If the handle is a pipe or socket, and the writing end
+-- is closed, 'hGetBufNonBlocking' will behave as if EOF was reached.
+--
+hGetBufNonBlocking :: Handle -> Ptr a -> Int -> IO Int
+hGetBufNonBlocking h ptr count
+ | count == 0 = return 0
+ | count < 0 = illegalBufferSize h "hGetBufNonBlocking" count
+ | otherwise =
+ wantReadableHandle "hGetBufNonBlocking" h $
+ \ handle_@Handle__{ haFD=fd, haBuffer=ref, haIsStream=is_stream } -> do
+ bufReadNonBlocking fd ref is_stream ptr 0 count
+
+bufReadNonBlocking fd ref is_stream ptr so_far count =
+ seq fd $ seq so_far $ seq count $ do -- strictness hack
+ buf@Buffer{ bufBuf=raw, bufWPtr=w, bufRPtr=r, bufSize=sz } <- readIORef ref
+ if bufferEmpty buf
+ then if count > sz -- large read?
+ then do rest <- readChunkNonBlocking fd is_stream ptr count
+ return (so_far + rest)
+ else do buf' <- fillReadBufferWithoutBlocking fd is_stream buf
+ case buf' of { Buffer{ bufWPtr=w } ->
+ if (w == 0)
+ then return so_far
+ else do writeIORef ref buf'
+ bufReadNonBlocking fd ref is_stream ptr
+ so_far (min count w)
+ -- NOTE: new count is 'min count w'
+ -- so we will just copy the contents of the
+ -- buffer in the recursive call, and not
+ -- loop again.
+ }
+ else do
+ let avail = w - r
+ if (count == avail)
+ then do
+ memcpy_ptr_baoff ptr raw r (fromIntegral count)
+ writeIORef ref buf{ bufWPtr=0, bufRPtr=0 }
+ return (so_far + count)
+ else do
+ if (count < avail)
+ then do
+ memcpy_ptr_baoff ptr raw r (fromIntegral count)
+ writeIORef ref buf{ bufRPtr = r + count }
+ return (so_far + count)
+ else do
+
+ let remaining = count - avail
+ so_far' = so_far + avail
+ ptr' = ptr `plusPtr` avail
+
+ -- we haven't attempted to read anything yet if we get to here.
+ if remaining < sz
+ then bufReadNonBlocking fd ref is_stream ptr' so_far' remaining
+ else do
+
+ rest <- readChunkNonBlocking fd is_stream ptr' remaining
+ return (so_far' + rest)
+
+
readChunkNonBlocking :: FD -> Bool -> Ptr a -> Int -> IO Int
-readChunkNonBlocking fd is_stream ptr bytes = loop 0 bytes
- where
- loop :: Int -> Int -> IO Int
- loop off bytes | bytes <= 0 = return off
- loop off bytes = do
+readChunkNonBlocking fd is_stream ptr bytes = do
#ifndef mingw32_TARGET_OS
- ssize <- c_read (fromIntegral fd) (ptr `plusPtr` off) (fromIntegral bytes)
+ ssize <- c_read (fromIntegral fd) (castPtr ptr) (fromIntegral bytes)
let r = fromIntegral ssize :: Int
if (r == -1)
then do errno <- getErrno
if (errno == eAGAIN || errno == eWOULDBLOCK)
- then return off
+ then return 0
else throwErrno "readChunk"
- else if (r == 0)
- then return off
- else loop (off + r) (bytes - r)
+ else return r
#else
(ssize, rc) <- asyncRead fd (fromIntegral $ fromEnum is_stream)
- (fromIntegral bytes)
- (ptr `plusPtr` off)
+ (fromIntegral bytes) ptr
let r = fromIntegral ssize :: Int
if r == (-1)
then ioError (errnoToIOError "hGetBufNonBlocking" (Errno (fromIntegral rc)) Nothing Nothing)
- else if (r == 0)
- then return off
- else loop (off + r) (bytes - r)
+ else return r
#endif
slurpFile :: FilePath -> IO (Ptr (), Int)
projects / ghc-base.git / commitdiff