[project @ 2002-05-10 16:18:28 by simonmar]

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

diff --git a/GHC/IO.hs b/GHC/IO.hs
index 39725a5..9467c53 100644 (file)
--- a/GHC/IO.hs
+++ b/GHC/IO.hs
@@ -2,17 +2,29 @@
 
 #undef DEBUG_DUMP
 
--- -----------------------------------------------------------------------------
--- $Id: IO.hs,v 1.4 2002/02/07 11:13:30 simonmar Exp $
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  GHC.IO
+-- Copyright   :  (c) The University of Glasgow, 1992-2001
+-- License     :  see libraries/base/LICENSE
+-- 
+-- Maintainer  :  libraries@haskell.org
+-- Stability   :  internal
+-- Portability :  non-portable
 --
--- (c) The University of Glasgow, 1992-2001
+-- String I\/O functions
 --
+-----------------------------------------------------------------------------
 
 module GHC.IO ( 
    hWaitForInput, hGetChar, hGetLine, hGetContents, hPutChar, hPutStr,
    commitBuffer',      -- hack, see below
    hGetcBuffered,      -- needed by ghc/compiler/utils/StringBuffer.lhs
-   hGetBuf, hPutBuf, slurpFile
+   hGetBuf, hPutBuf, slurpFile,
+   memcpy_ba_baoff,
+   memcpy_ptr_baoff,
+   memcpy_baoff_ba,
+   memcpy_baoff_ptr,
  ) where
 
 import Foreign
@@ -304,7 +316,7 @@ lazyReadHaveBuffer h handle_ fd ref buf = do
 
 
 unpackAcc :: RawBuffer -> Int -> Int -> [Char] -> IO [Char]
-unpackAcc buf r 0 acc  = return ""
+unpackAcc buf r 0 acc  = return acc
 unpackAcc buf (I# r) (I# len) acc = IO $ \s -> unpack acc (len -# 1#) s
    where
     unpack acc i s
@@ -595,7 +607,8 @@ hPutBuf :: Handle                   -- handle to write to
        -> Int                          -- number of bytes of data in buffer
        -> IO ()
 hPutBuf handle ptr count
-  | count <= 0 = illegalBufferSize handle "hPutBuf" count
+  | count == 0 = return ()
+  | count <  0 = illegalBufferSize handle "hPutBuf" count
   | otherwise = 
     wantWritableHandle "hPutBuf" handle $ 
       \ handle_@Handle__{ haFD=fd, haBuffer=ref, haIsStream=is_stream } -> do
@@ -635,7 +648,8 @@ writeChunk fd ptr bytes = loop 0 bytes
 
 hGetBuf :: Handle -> Ptr a -> Int -> IO Int
 hGetBuf handle ptr count
-  | count <= 0 = illegalBufferSize handle "hGetBuf" count
+  | count == 0 = return 0
+  | count <  0 = illegalBufferSize handle "hGetBuf" count
   | otherwise = 
       wantReadableHandle "hGetBuf" handle $ 
        \ handle_@Handle__{ haFD=fd, haBuffer=ref } -> do
@@ -682,6 +696,7 @@ slurpFile fname = do
     ioError (userError "slurpFile: file too big")
    else do
     let sz_i = fromIntegral sz
+    if sz_i == 0 then return (nullPtr, 0) else do
     chunk <- mallocBytes sz_i
     r <- hGetBuf handle chunk sz_i
     hClose handle