-- Stability : internal
-- Portability : non-portable (GHC Extensions)
--
--- Top-level IO actions want to catch exceptions (e.g., 'forkIO' and
--- 'GHC.Main.mainIO') and report them - 'topHandler' is the exception
--- handler they should use for this.
+-- Support for catching exceptions raised during top-level computations
+-- (e.g. @Main.main@, 'Control.Concurrent.forkIO', and foreign exports)
--
-----------------------------------------------------------------------------
module GHC.TopHandler (
- runIO, runNonIO, reportStackOverflow, reportError
+ runIO, runNonIO, reportStackOverflow, reportError
) where
import Prelude
import System.IO
+import Control.Exception
import Foreign.C.String
import Foreign.Ptr
import GHC.Exception
import GHC.Prim (unsafeCoerce#)
--- | 'runIO' is wrapped around 'Main.main' by @TcModule@. It is also wrapped
+-- | 'runIO' is wrapped around @Main.main@ by @TcModule@. It is also wrapped
-- around every @foreign export@ and @foreign import \"wrapper\"@ to mop up
-- any uncaught exceptions. Thus, the result of running
-- 'System.Exit.exitWith' in a foreign-exported function is the same as
ExitException ExitSuccess -> safe_exit 0
ExitException (ExitFailure n) -> safe_exit n
- Deadlock -> reportError True
- "no threads to run: infinite loop or deadlock?"
-
- ErrorCall s -> reportError True s
- other -> reportError True (showsPrec 0 other "\n")
+ other -> reportError True other
+
reportStackOverflow :: Bool -> IO a
reportStackOverflow bombOut = do
then exit 2
else return undefined
-reportError :: Bool -> String -> IO a
-reportError bombOut str = do
- (hFlush stdout) `catchException` (\ _ -> return ())
- withCStringLen str $ \(cstr,len) -> do
- writeErrString errorHdrHook cstr len
- if bombOut
- then exit 1
- else return undefined
-
-#ifndef ILX
-foreign import ccall "&ErrorHdrHook" errorHdrHook :: Ptr ()
-#else
-foreign import ccall "ErrorHdrHook" errorHdrHook :: Ptr ()
-#endif
-
-foreign import ccall unsafe "writeErrString__"
- writeErrString :: Ptr () -> CString -> Int -> IO ()
+reportError :: Bool -> Exception -> IO a
+reportError bombOut ex = do
+ handler <- getUncaughtExceptionHandler
+ handler ex
+ if bombOut
+ then exit 1
+ else return undefined
-- SUP: Are the hooks allowed to re-enter Haskell land? If so, remove
-- the unsafe below.