Making alloca more safe

[BCS]

Hello Walter,

> Max Samukha wrote:
> 
>> On Mon, 16 Nov 2009 12:48:51 -0800, Walter Bright
>> <newshound1 at digitalmars.com> wrote:
>>> If you've got a system that relies on the software continuing to
>>> function after an unexpected null seg fault, you have a VERY BADLY
>>> DESIGNED and COMPLETELY UNSAFE system. I really cannot emphasize
>>> this enough.
>>> 
>> I have an example of such a software:
>> http://www.steinberg.net/en/products/audiopostproduction_product/nuen
>> do4.html
>> It loads third-party plugins into the host process's address space,
>> an consequently it may fail at any moment. The software's design is
>> not the best ever but it gives the user last chance to save his work
>> in case of fatal error. This feature has saved my back a couple of
>> times.
>> 
> 
> Be that as it may, it is certainly possible to catch seg faults in an
> exception handler and write files out. That would be an unacceptable
> behavior, though, in a system that needs to be safe.
> 

For some systems, once you hit a seg-v, things can't get any worse so why 
not try to make things better by saving what you can?