use LANGUAGE instead of OPTIONS_GHC

[ghc-base.git] / GHC / IO / Handle.hs

diff --git a/GHC/IO/Handle.hs b/GHC/IO/Handle.hs
index b3c780e..10b7004 100644 (file)
--- a/GHC/IO/Handle.hs
+++ b/GHC/IO/Handle.hs
@@ -1,5 +1,6 @@
-{-# OPTIONS_GHC -XNoImplicitPrelude -XRecordWildCards #-}
 {-# OPTIONS_GHC -fno-warn-unused-matches #-}
+{-# LANGUAGE NoImplicitPrelude, RecordWildCards #-}
+
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  GHC.IO.Handle
@@ -51,7 +52,7 @@ import GHC.IO.Device as IODevice
 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
@@ -140,14 +141,24 @@ hSetFileSize handle size =
 -- 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
-     (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
@@ -258,16 +269,16 @@ hSetBuffering handle mode =
 --
 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,
-                      haCodec   = Just encoding, .. },
-            ())
+                      haCodec   = Just encoding, .. })
 
 -- | Return the current 'TextEncoding' for the specified 'Handle', or
 -- 'Nothing' if the 'Handle' is in binary mode.
@@ -384,6 +395,9 @@ hSetPosn (HandlePosn h i) = hSeek h AbsoluteSeek i
 --
 -- 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 () 
@@ -408,6 +422,15 @@ hSeek handle mode offset =
     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
@@ -551,7 +574,8 @@ hSetBinaryMode :: Handle -> Bool -> IO ()
 hSetBinaryMode handle bin =
   withAllHandles__ "hSetBinaryMode" handle $ \ h_@Handle__{..} ->
     do 
-         flushBuffer h_
+         flushCharBuffer h_
+         closeTextCodecs h_
 
          let mb_te | bin       = Nothing
                    | otherwise = Just localeEncoding