On 6/5/07, Kevin O'Connor <[EMAIL PROTECTED]> wrote:
> On Sun, Jun 03, 2007 at 11:09:34PM +0100, Pedro Alves wrote:
> > Kevin O'Connor wrote:
> > > So, is it possible to have mingw32ce install a global SEH handler that
> > > just translates the exception into an sjlj one? That is, can we
> > > modify the standard crt0.S file so that it causes wince exceptions to
> > > raise C++ exceptions that g++ can then handle?
> > >
> >
> > Maybe, but it would be tricky.
> >[...]
> > The cegcc's crt0.S, start.c and __eh_handler.S files implement
> > something similar which may help as a starting point.
>
> Hrmm. I have another problem - it looks like gcc will optimize away
> try/catch blocks if it doesn't think the code can throw an exception.
> If we went down this route, would it be possible to prevent gcc from
> doing that?
>
I don't know if it is possible with a command line option, but the obvious
workaround is to insert a call into a dummy function in the try scope.
Maybe asking at gcc-help@ will yield better results.
> > > However, I'm a bit concerned with using IsBad{Read,Write}Ptr.
> > You're right, the WinCE version of the docs isn't clear. I've seen
> > several discussions on IsBad*Ptr, and always understood it as using
> > a __try/__except block inside.
>
> I'm not sure how it would do that. What would IsBadWritePtr(x, 400)
> actually write to memory? If it did actually generate extra
> read/write memory accesses that would be really bad - in haret we use
> these routines to get at memory mapped registers, and extra accesses
> could confuse the chips.
>
I don't know MSFT's implementation, but here is one:
http://www.google.com/codesearch?hl=en&q=+isbadwriteptr+show:5v_C0idOToQ:_iDKRUTKWrM:Y2l423JHiIo&sa=N&cd=4&ct=rc&cs_p=http://www.acc.umu.se/~bosse/libcpp2.zip&cs_f=libcpp/src/virtual.c#a0
It ors (|=) page boundary address values with 0.
Of course it would be a problem for memory mapped registers.
On the other hand, reactos', Wine's or Rewinds implementations should be more
close to what Windows does. They use VirtualQuery:
http://www.google.com/codesearch?hl=en&q=+isbadwriteptr+show:BwznxkJ_dvg:2wkRGv-GtGA:FgDW0L8NqJ8&sa=N&cd=13&ct=rc&cs_p=ftp://ftp.heanet.ie/mirrors/download.sourceforge.net/pub/sourceforge/r/re/reactos/reactos-0.2.4-rc1-src.zip&cs_f=reactos/lib/kernel32/mem/isbad.c#a0
... which will not catch problems other than access violations.
Other than doing the dangerous work in a MSVC built dll, I'm out of ideas.
Cheers,
Pedro Alves
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