module GHC.IO.Handle.Text (
hWaitForInput, hGetChar, hGetLine, hGetContents, hPutChar, hPutStr,
commitBuffer', -- hack, see below
- hGetBuf, hGetBufNonBlocking, hPutBuf, hPutBufNonBlocking,
+ hGetBuf, hGetBufSome, hGetBufNonBlocking, hPutBuf, hPutBufNonBlocking,
memcpy,
) where
-- | Computation 'hWaitForInput' @hdl t@
-- waits until input is available on handle @hdl@.
-- It returns 'True' as soon as input is available on @hdl@,
--- or 'False' if no input is available within @t@ milliseconds.
+-- or 'False' if no input is available within @t@ milliseconds. Note that
+-- 'hWaitForInput' waits until one or more full /characters/ are available,
+-- which means that it needs to do decoding, and hence may fail
+-- with a decoding error.
--
-- If @t@ is less than zero, then @hWaitForInput@ waits indefinitely.
--
-- This operation may fail with:
--
-- * 'isEOFError' if the end of file has been reached.
+-- * a decoding error, if the input begins with an invalid byte sequence
+-- in this Handle's encoding.
--
-- NOTE for GHC users: unless you use the @-threaded@ flag,
-- @hWaitForInput t@ where @t >= 0@ will block all other Haskell
-- threads for the duration of the call. It behaves like a
-- @safe@ foreign call in this respect.
+--
hWaitForInput :: Handle -> Int -> IO Bool
hWaitForInput h msecs = do
-- It returns the number of bytes actually read. This may be zero if
-- EOF was reached before any data was read (or if @count@ is zero).
--
--- 'hGetBuf' ignores whatever 'TextEncoding' the 'Handle' is currently
--- using, and reads bytes directly from the underlying IO device.
---
-- 'hGetBuf' never raises an EOF exception, instead it returns a value
-- smaller than @count@.
--
then return off
else loop fd (off + r) (bytes - r)
+-- ---------------------------------------------------------------------------
+-- hGetBufSome
+
+-- | 'hGetBufSome' @hdl buf count@ reads data from the handle @hdl@
+-- into the buffer @buf@. If there is any data available to read,
+-- then 'hGetBufSome' returns it immediately; it only blocks if there
+-- is no data to be read.
+--
+-- It returns the number of bytes actually read. This may be zero if
+-- EOF was reached before any data was read (or if @count@ is zero).
+--
+-- 'hGetBufSome' never raises an EOF exception, instead it returns a value
+-- smaller than @count@.
+--
+-- If the handle is a pipe or socket, and the writing end
+-- is closed, 'hGetBufSome' will behave as if EOF was reached.
+--
+-- 'hGetBufSome' ignores the prevailing 'TextEncoding' and 'NewlineMode'
+-- on the 'Handle', and reads bytes directly.
+
+hGetBufSome :: Handle -> Ptr a -> Int -> IO Int
+hGetBufSome h ptr count
+ | count == 0 = return 0
+ | count < 0 = illegalBufferSize h "hGetBuf" count
+ | otherwise =
+ wantReadableHandle_ "hGetBuf" h $ \ h_@Handle__{..} -> do
+ flushCharReadBuffer h_
+ buf@Buffer{ bufSize=sz } <- readIORef haByteBuffer
+ if isEmptyBuffer buf
+ then if count > sz -- large read?
+ then do RawIO.read (haFD h_) (castPtr ptr) count
+ else do (r,buf') <- Buffered.fillReadBuffer haDevice buf
+ if r == 0
+ then return 0
+ else do writeIORef haByteBuffer buf'
+ bufReadNBNonEmpty h_ buf' (castPtr ptr) 0 count
+ else
+ bufReadNBEmpty h_ buf (castPtr ptr) 0 count
+
+haFD :: Handle__ -> FD
+haFD h_@Handle__{} =
+ case cast h_ of
+ Nothing -> error "not an FD"
+ Just fd -> fd
+
-- | '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
-- only whatever data is available. To wait for data to arrive before
-- calling 'hGetBufNonBlocking', use 'hWaitForInput'.
--
--- 'hGetBufNonBlocking' ignores whatever 'TextEncoding' the 'Handle'
--- is currently using, and reads bytes directly from the underlying IO
--- device.
---
-- If the handle is a pipe or socket, and the writing end
-- is closed, 'hGetBufNonBlocking' will behave as if EOF was reached.
--
seq so_far $ seq count $ do -- strictness hack
buf@Buffer{ bufRaw=raw, bufR=w, bufL=r, bufSize=sz } <- readIORef haByteBuffer
if isEmptyBuffer buf
- then if count > sz -- large read?
- then do rest <- readChunkNonBlocking h_ ptr count
- return (so_far + rest)
- else do (r,buf') <- Buffered.fillReadBuffer0 haDevice buf
- case r of
- Nothing -> return so_far
- Just 0 -> return so_far
- Just r -> do
- writeIORef haByteBuffer buf'
- bufReadNonBlocking h_ ptr so_far (min count r)
- -- 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
+ then bufReadNBEmpty h_ buf ptr so_far count
+ else bufReadNBNonEmpty h_ buf ptr so_far count
+
+bufReadNBEmpty :: Handle__ -> Buffer Word8 -> Ptr Word8 -> Int -> Int -> IO Int
+bufReadNBEmpty h_@Handle__{..}
+ buf@Buffer{ bufRaw=raw, bufR=w, bufL=r, bufSize=sz }
+ ptr so_far count
+ = if count > sz -- large read?
+ then do rest <- readChunkNonBlocking h_ ptr count
+ return (so_far + rest)
+ else do (r,buf') <- Buffered.fillReadBuffer0 haDevice buf
+ case r of
+ Nothing -> return so_far
+ Just 0 -> return so_far
+ Just r -> do
+ writeIORef haByteBuffer buf'
+ bufReadNBNonEmpty h_ buf' ptr so_far (min count r)
+ -- 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.
+
+bufReadNBNonEmpty :: Handle__ -> Buffer Word8 -> Ptr Word8 -> Int -> Int -> IO Int
+bufReadNBNonEmpty h_@Handle__{..}
+ buf@Buffer{ bufRaw=raw, bufR=w, bufL=r, bufSize=sz }
+ ptr so_far count
+ = do
let avail = w - r
if (count == avail)
then do
else do
copyFromRawBuffer ptr raw (fromIntegral r) (fromIntegral avail)
- writeIORef haByteBuffer buf{ bufR=0, bufL=0 }
+ let buf' = buf{ bufR=0, bufL=0 }
+ writeIORef haByteBuffer buf'
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 h_ ptr' so_far' remaining
- else do
-
- rest <- readChunkNonBlocking h_ ptr' remaining
- return (so_far' + rest)
+ bufReadNBEmpty h_ buf' ptr' so_far' remaining
readChunkNonBlocking :: Handle__ -> Ptr Word8 -> Int -> IO Int
projects / ghc-base.git / commitdiff