[!! SPAM] Re: [fpc-devel] unwinding stack from within ExceptProc?

[Bogusław Brandys]

Lukas Zeller pisze:
> Thanks, Jonas for the quick response (again)!
> 
> On Sep 26, 2009, at 15:31 , Jonas Maebe wrote:
> 
>> On 25 Sep 2009, at 18:09, Lukas Zeller wrote:
>>
>>> The longjmp itself works, but after this has happened once, further 
>>> exceptions crash the program. I wonder if there is some (FPC) cleanup 
>>> routine I could or should call before the longjmp that would make the 
>>> scenario work, or if there is technical evidence that it can't work 
>>> at all.
>>
>> There is no "technical evidence" that it can't work at all, but you 
>> would have to call internal RTL routines [...]
> 
> I hope I read that correctly as: "just longjump can't work and leaves a 
> mess behind that might explain crashes on subsequent exceptions"
> 
>> [...] which are not for public use, so
>> a) this is not documented or supported in any way (I can't tell you 
>> the names by heart either)
>> b) if you manage to figure it out, then your code can break with any 
>> future FPC version
> 
> Yes - if it was "my code", I'd try to avoid the situation. It 
> unfortunately isn't, the calling environment only provides that routine 
> which longjmps to handle a exception situation. So making it work with 
> the current FPC version and risking it'll break in a future version 
> would be better than nothing.
> 
> Maybe there's a better solution, but what are the official options I 
> have in ExceptProc other than halt? If I just return from it, how does 
> the call flow continue? At that time the stack must be already unwound, 
> but how far? While I understand ExceptProc is called when a exception 
> falls through all the way down to a pascal main program, I can't really 
> imagine at what point the same happens in a pascal shared lib.
> 
> Thanks for any explanations!
> 
> Lukas
> 
> _______________________________________________
> fpc-devel maillist  -  fpc-devel at lists.freepascal.org
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> 

Don't know if that help you,but check it : 
http://bugs.freepascal.org/view.php?id=13518


Boguslaw