Extra.hs

module System.IO.Extra(openFileM, openTmpFile, splitTmp) where
import Foreign.C.String

splitTmp :: String -> (String, String)
splitTmp tmpl = 
  case span (/= '.') (reverse tmpl) of
    (rsuf, "") -> (tmpl, "")
    (rsuf, _:rpre) -> (reverse rpre, '.':reverse rsuf)

-- Create a temporary file, take a prefix and a suffix
-- and returns a malloc()ed string.
foreign import ccall "tmpname" c_tmpname :: CString -> CString -> IO CString

-- Create and open a temporary file.
openTmpFile :: String -> IO (String, Handle)
openTmpFile tmpl = do
  let (pre, suf) = splitTmp tmpl
  ctmp <- withCAString pre $ withCAString suf . c_tmpname
  tmp <- peekCAString ctmp
  free ctmp
  h <- openFile tmp ReadWriteMode
  return (tmp, h)