-{-# OPTIONS_GHC -fno-implicit-prelude #-}
-{-# OPTIONS_GHC -XRecordWildCards #-}
+{-# OPTIONS_GHC -XNoImplicitPrelude -XRecordWildCards #-}
{-# OPTIONS_GHC -fno-warn-unused-matches #-}
-----------------------------------------------------------------------------
-- |
mkFileHandle, mkDuplexHandle,
hFileSize, hSetFileSize, hIsEOF, hLookAhead,
- hSetBuffering, hSetBinaryMode, hSetEncoding,
+ hSetBuffering, hSetBinaryMode, hSetEncoding, hGetEncoding,
hFlush, hFlushAll, hDuplicate, hDuplicateTo,
hClose, hClose_help,
import GHC.IO.Handle.Types
import GHC.IO.Handle.Internals
import GHC.IO.Handle.Text
-import System.IO.Error
+import qualified GHC.IO.BufferedIO as Buffered
import GHC.Base
import GHC.Exception
-- physical file, if the current I\/O position is equal to the length of
-- the file. Otherwise, it returns 'False'.
--
--- NOTE: 'hIsEOF' may block, because it is the same as calling
--- 'hLookAhead' and checking for an EOF exception.
+-- NOTE: 'hIsEOF' may block, because it has to attempt to read from
+-- the stream to determine whether there is any more data to be read.
hIsEOF :: Handle -> IO Bool
-hIsEOF handle =
- catch
- (do hLookAhead handle; return False)
- (\e -> if isEOFError e then return True else ioError e)
+hIsEOF handle = wantReadableHandle_ "hIsEOF" handle $ \Handle__{..} -> do
+
+ cbuf <- readIORef haCharBuffer
+ if not (isEmptyBuffer cbuf) then return False else do
+
+ bbuf <- readIORef haByteBuffer
+ if not (isEmptyBuffer bbuf) then return False else do
+
+ -- NB. do no decoding, just fill the byte buffer; see #3808
+ (r,bbuf') <- Buffered.fillReadBuffer haDevice bbuf
+ if r == 0
+ then return True
+ else do writeIORef haByteBuffer bbuf'
+ return False
-- ---------------------------------------------------------------------------
-- Looking ahead
-- hSetEncoding
-- | The action 'hSetEncoding' @hdl@ @encoding@ changes the text encoding
--- for the handle @hdl@ to @encoding@. Encodings are available from the
--- module "GHC.IO.Encoding". The default encoding when a 'Handle' is
+-- for the handle @hdl@ to @encoding@. The default encoding when a 'Handle' is
-- created is 'localeEncoding', namely the default encoding for the current
-- locale.
--
-- stop further encoding or decoding on an existing 'Handle', use
-- 'hSetBinaryMode'.
--
+-- 'hSetEncoding' may need to flush buffered data in order to change
+-- the encoding.
+--
hSetEncoding :: Handle -> TextEncoding -> IO ()
hSetEncoding hdl encoding = do
- withHandle "hSetEncoding" hdl $ \h_@Handle__{..} -> do
+ withAllHandles__ "hSetEncoding" hdl $ \h_@Handle__{..} -> do
flushCharBuffer h_
+ closeTextCodecs h_
openTextEncoding (Just encoding) haType $ \ mb_encoder mb_decoder -> do
bbuf <- readIORef haByteBuffer
ref <- newIORef (error "last_decode")
- return (Handle__{ haLastDecode = ref, haDecoder = mb_decoder, haEncoder = mb_encoder, .. },
- ())
+ return (Handle__{ haLastDecode = ref,
+ haDecoder = mb_decoder,
+ haEncoder = mb_encoder,
+ haCodec = Just encoding, .. })
+
+-- | Return the current 'TextEncoding' for the specified 'Handle', or
+-- 'Nothing' if the 'Handle' is in binary mode.
+--
+-- Note that the 'TextEncoding' remembers nothing about the state of
+-- the encoder/decoder in use on this 'Handle'. For example, if the
+-- encoding in use is UTF-16, then using 'hGetEncoding' and
+-- 'hSetEncoding' to save and restore the encoding may result in an
+-- extra byte-order-mark being written to the file.
+--
+hGetEncoding :: Handle -> IO (Maybe TextEncoding)
+hGetEncoding hdl =
+ withHandle_ "hGetEncoding" hdl $ \h_@Handle__{..} -> return haCodec
-- -----------------------------------------------------------------------------
-- hFlush
--
-- This operation may fail with:
--
+-- * 'isIllegalOperationError' if the Handle is not seekable, or does
+-- not support the requested seek mode.
+--
-- * 'isPermissionError' if a system resource limit would be exceeded.
hSeek :: Handle -> SeekMode -> Integer -> IO ()
IODevice.seek haDevice mode offset
+-- | Computation 'hTell' @hdl@ returns the current position of the
+-- handle @hdl@, as the number of bytes from the beginning of
+-- the file. The value returned may be subsequently passed to
+-- 'hSeek' to reposition the handle to the current position.
+--
+-- This operation may fail with:
+--
+-- * 'isIllegalOperationError' if the Handle is not seekable.
+--
hTell :: Handle -> IO Integer
hTell handle =
wantSeekableHandle "hGetPosn" handle $ \ handle_@Handle__{..} -> do
hSetBinaryMode handle bin =
withAllHandles__ "hSetBinaryMode" handle $ \ h_@Handle__{..} ->
do
- flushBuffer h_
+ flushCharBuffer h_
+ closeTextCodecs h_
let mb_te | bin = Nothing
| otherwise = Just localeEncoding
return Handle__{ haLastDecode = ref,
haEncoder = mb_encoder,
haDecoder = mb_decoder,
+ haCodec = mb_te,
haInputNL = inputNL nl,
haOutputNL = outputNL nl, .. }
case cast devTo of
Nothing -> ioe_dupHandlesNotCompatible h
Just dev' -> do
- IODevice.dup2 dev dev'
+ _ <- IODevice.dup2 dev dev'
FileHandle _ m <- dupHandle_ dev' filepath other_side h_ mb_finalizer
takeMVar m