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From: jbro on 28 Nov 2009 04:21
On Nov 27, 8:53 am, Paul Tarvydas <tarvy...(a)visualframeworksinc.com>
wrote:
> > The C code in question is
>
> > int _stdcall myarray(int sz)
> > {
> >   int *end;
> >   int pin [4]={sz,2,73,4};
> >   end= pin;
> >   return *end;
> > }
>
> > I don't know what _stdcall does but I doubt that it is so powerful that
> > it fixes the issue of returning a pointer to automatic storage.
>
> Yes, I missed the "sz" stuck in the array initializer.  This C code is
> utterly wrong.
>
You are right about stdcall, but that is not the issue and neither is
the "sz". What Spiros is trying to say is that once your function
returns (to Lisp) pin's memory is deallocated and so now end points
somewhere it shouldn't (i.e. to already deallocated memory). You need
to create your array on the heap with malloc and then arrange for Lisp
to call into a function that calls free to deallocate the memory.
Write a main function in C and test your function -- you'll get the
same seg fault. It has nothing to do with Lisp.
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