Hi Ken,
On Jun 26 10:33, Ken Brown wrote:
> On 6/26/2015 10:14 AM, Corinna Vinschen wrote:
> >On Jun 26 08:02, Ken Brown wrote:
> >>On 6/26/2015 7:12 AM, Corinna Vinschen wrote:
> >Thank you. I'll try to test this in the next couple of days. One hint
> >and one question:
> >
> >>The signal handler:
> >>
> >>/* Attempt to recover from SIGSEGV caused by C stack overflow. */
> >>static void
> >>handle_sigsegv (int sig, siginfo_t *siginfo, void *arg)
> >>{
> >> /* Hard GC error may lead to stack overflow caused by
> >> too nested calls to mark_object. No way to survive. */
> >> if (!gc_in_progress)
> >> {
> >> struct rlimit rlim;
> >>
> >> if (!getrlimit (RLIMIT_STACK, &rlim))
> >
> >This getrlimit probably won't work as desired. I just had a quick look
> >how this request is handled. It will return the size of the alternate
> >stack while running the signal handler, rather than the size of the
> >initial thread's stack as required by POSIX. This definitely needs
> >fixing.
> >
> >> {
> >> enum { STACK_DANGER_ZONE = 16 * 1024 };
> >> char *beg, *end, *addr;
> >>
> >> beg = stack_bottom;
> >> end = stack_bottom + stack_direction * rlim.rlim_cur;
> >> if (beg > end)
> >> addr = beg, beg = end, end = addr;
> >> addr = (char *) siginfo->si_addr;
> >> /* If we're somewhere on stack and too close to
> >> one of its boundaries, most likely this is it. */
> >> if (beg < addr && addr < end
> >> && (addr - beg < STACK_DANGER_ZONE
> >> || end - addr < STACK_DANGER_ZONE))
> >> siglongjmp (return_to_command_loop, 1);
> >> }
> >> }
> >>
> >> /* Otherwise we can't do anything with this. */
> >> deliver_fatal_thread_signal (sig);
> >>}
> >>
> >>The code to set up the signal handler on the alternate stack:
> >>
> >>static bool
> >>init_sigsegv (void)
> >>{
> >> struct sigaction sa;
> >> stack_t ss;
> >>
> >> stack_direction = ((char *) &ss < stack_bottom) ? -1 : 1;
> >>
> >> ss.ss_sp = sigsegv_stack;
> >> ss.ss_size = sizeof (sigsegv_stack);
> > ^^^^^^^^^^^^^^^^^^^^^^^
> >
> >What's that size in bytes?
>
> SIGSTKSZThanks. Another question: How does emacs compute stack_bottom? Corinna -- Corinna Vinschen Please, send mails regarding Cygwin to Cygwin Maintainer cygwin AT cygwin DOT com Red Hat
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