[Haskell-cafe] FFI: how to handle external dll crashes

[Miro Karpis]

Please, can you help me with following: I have an external dll that I'm
importing in my haskell program. In some particular cases the dll crashes.

Simplified: first I need to send to dll with MethodA some parameters and
then call MethodB to do some calculations on those parameters. If I didn't
give enough parameters then MethodB will crash the whole dll and my Haskell
application.

Is there a way to handle this? Unfortunately there are no exceptions thrown
from the dll.

In ghci I'm getting following message: ERROR in
InitNumericalSystem::initializeSystem. JuncLabel.

I have tried to use "catchAny but that didn't help. c_run is my external
dll method which takes 4 input parameters:

catchAny :: IO a -> (SomeException -> IO a) -> IO a
catchAny = Control.Exception.catch

main :: IO ()
main = do
  let timeTot = []::[CDouble]
      timeNow = []::[CDouble]
      runType = 2::CInt
  timeTotPtr <- newArray timeTot
  timeNowPtr <- newArray timeNow
  result <- (catchAny $ c_run timeTotPtr runType timeNowPtr 0) $ \e -> do
    putStrLn $ "Got an exception: " ++ show e
    putStrLn "Returning dummy value of -1"
    return (-1)
  free timeTotPtr
  free timeNowPtr
  print result



I have tried also with withAsync, and no luck

tryAny :: IO a -> IO (Either SomeException a)
tryAny action = withAsync action waitCatch

catchAny :: IO a -> (SomeException -> IO a) -> IO a
catchAny action onE = tryAny action >>= either onE return

try2 :: IO ()
try2 = do
      let timeTot = []::[CDouble]
          timeNow = []::[CDouble]
          runType = 2::CInt
      timeTotPtr <- newArray timeTot
      timeNowPtr <- newArray timeNow
      putStrLn $ "c_run going to call c_run.."
      result <- catchAny (c_run timeTotPtr runType timeNowPtr 0) (const $
return (-1))
      free timeTotPtr
      free timeNowPtr
      putStrLn $ "Result: " ++ show result


Is there a way how I can handle this?

cheers,
m.
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