On 11/06/12 23:12, Tom Boutell wrote:
> Can you really use setjmp and longjmp in that way safely? I thought it
> was only safe to longjmp "back," not "forward" - you can use them to
> fake exception support but that's it because you'll smash the stack
> otherwise. Something like that...
My first reaction was also "How do you return to the mid-running function?"
However, given that the running function is in PHP-land, I think you could
(in non-zts, it's direct in zts), save EG() contents and replace with
new values,
and then continue the execution.
As it's treating "threads" non-preemtively, that should work.
The C code would also view a different thread, but because it is viewing
different globals (some extensions might need changes). Not really
involving
setjmp() / longjmp().
You could make userland context switches (adding arch-specific code) for
the C code by switching the stack under your ESP, but it's highly likely to
produce some obscure bugs by missing to keep a register...