1 -- -----------------------------------------------------------------------------
2 -- $Id: PrelTopHandler.lhs,v 1.3 2001/07/12 10:37:55 rrt Exp $
4 -- (c) The University of Glasgow, 2001
8 -- 'Top-level' IO actions want to catch exceptions (e.g., forkIO and
9 -- PrelMain.mainIO) and report them - topHandler is the exception
10 -- handler they should use for this:
12 -- make sure we handle errors while reporting the error!
13 -- (e.g. evaluating the string passed to 'error' might generate
14 -- another error, etc.)
16 -- These functions can't go in PrelMain, because PrelMain isn't
17 -- included in HSstd.o (because PrelMain depends on Main, which
18 -- doesn't exist yet...).
21 module PrelTopHandler (
22 topHandler, reportStackOverflow, reportError
32 topHandler :: Exception -> IO ()
33 topHandler err = catchException (real_handler err) topHandler
35 real_handler :: Exception -> IO ()
38 AsyncException StackOverflow -> reportStackOverflow True
40 -- only the main thread gets ExitException exceptions
41 ExitException ExitSuccess -> shutdownHaskellAndExit 0
42 ExitException (ExitFailure n) -> shutdownHaskellAndExit n
44 ErrorCall s -> reportError True s
45 other -> reportError True (showsPrec 0 other "\n")
47 -- NOTE: shutdownHaskellAndExit must be called "safe", because it *can*
48 -- re-enter Haskell land through finalizers.
49 foreign import ccall "shutdownHaskellAndExit"
50 shutdownHaskellAndExit :: Int -> IO ()
52 reportStackOverflow :: Bool -> IO ()
53 reportStackOverflow bombOut = do
54 (hFlush stdout) `catchException` (\ _ -> return ())
61 reportError :: Bool -> String -> IO ()
62 reportError bombOut str = do
63 (hFlush stdout) `catchException` (\ _ -> return ())
64 withCStringLen str $ \(cstr,len) -> do
65 writeErrString errorHdrHook cstr len
70 foreign label "ErrorHdrHook" errorHdrHook :: Ptr ()
72 foreign import ccall "writeErrString__" unsafe
73 writeErrString :: Ptr () -> CString -> Int -> IO ()
75 -- SUP: Are the hooks allowed to re-enter Haskell land? If so, remove
77 foreign import ccall "stackOverflow" unsafe
78 callStackOverflowHook :: IO ()
80 foreign import ccall "stg_exit" unsafe
81 stg_exit :: Int -> IO ()