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

[Miro Karpis]

Hi Niklas,
I think that I'm doing this in my try2 function with tryAny and catchAny
functions. Unfortunately that didn't work. I'm just starting with Haskell
so maybe also my implementation of my haskell code is not 100% correct.

cheers,
m.


On Mon, Sep 23, 2013 at 1:36 PM, Niklas Hambüchen <mail at nh2.me> wrote:

> If you cannot do it with Haskell exceptions, I guess you need to look
> how you would do it in plain C in do the same.
>
> Keep in mind that if something crashes in a C library, that library
> might have corrupted (or leaked) any memory it had access to.
>
> I guess a somewhat reliable way is to fork an OS process, and run your
> crashy DLL in that; if it dies, the OS will keep care of cleaning up
> the low level garbage.
>
> On Mon 23 Sep 2013 17:37:49 SGT, Miro Karpis wrote:
> > 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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>
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