From: Mathieu Bouchard <matju@...>
Date: 2003-07-13T13:56:52+09:00
Subject: Re: stack problem


On Sat, 12 Jul 2003, Mauricio Fern�ndez wrote:
> You can use Init_stack, see the thread starting at [ruby-talk:74400].

Thanks. If I understood correctly, I have to use it like this?



volatile long bogus_variable = 0; /* just even *try* to optimise me out of
existence! */

sigjmp_buf rescue_segfault;

static void trap_segfault (int patate) {
	fprintf(stderr,"THIS IS INSIDE A SIGHANDLER!\n");
	siglongjmp(rescue_segfault,11);
}

extern "C" void Init_stack(VALUE *addr);

static void bridge_localize_sysstack () {
	volatile long * volatile bp = (volatile long *)&bp; /* get any
stack address */
	fprintf(stderr,"sysstack top is at 0x%08lx\n",(long)bp);
	post("sysstack top is at 0x%08lx\n",(long)bp);
	signal(11,trap_segfault);
	// in this loop, segfault is overridden to mean breaking out of
the for-loop.
	if (!sigsetjmp(rescue_segfault,0)) {
		for (;;) {
			//fprintf(stderr,"sysstack: trying
0x%08lx\n",(long)bp);
			bp+=1;
			bogus_variable += *bp;
		}
	}
	bp-=1;
	signal(11,SIG_DFL); /* can't really restore it. don't know where
it was. */
	fprintf(stderr,"sysstack starts at 0x%08lx\n",(long)bp);
	post("sysstack starts at 0x%08lx\n",(long)bp);
	Init_stack((VALUE *)bp);
}


________________________________________________________________
Mathieu Bouchard                       http://artengine.ca/matju