#include <unistd.h>
#include <signal.h>
#include <ucontext.h>

static union
{
	char buffer[SIGSTKSZ];
	long double ld;
	long u;
	void *p;
} alternate_signal_stack;

#if STACK_DIRECTION
# define find_stack_direction(ptr) STACK_DIRECTION
#else
static int
find_stack_direction (char const *addr)
{
	char dummy;
	return (! addr ? find_stack_direction (&dummy)
		: addr < &dummy ? 1 : -1);
}
#endif

static void
segv_handler (int signo, siginfo_t *info, void *context)
{
	if (0 < info->si_code)
	{
		ucontext_t const *user_context = context;
		char const *stack_min = user_context->uc_stack.ss_sp;
		size_t stack_size = user_context->uc_stack.ss_size;
		char const *faulting_address = info->si_addr;
		size_t s = faulting_address - stack_min;
		size_t page_size = sysconf (_SC_PAGESIZE);
		if (find_stack_direction (0) < 0)
			s += page_size;
		if (s < stack_size + page_size)
			_exit (0);
	}

	 _exit (1);
}

static int
c_stack_action (void)
{
	stack_t st;
	struct sigaction act;
	int r;

	st.ss_flags = 0;
	st.ss_sp = alternate_signal_stack.buffer;
	st.ss_size = sizeof alternate_signal_stack.buffer;
	r = sigaltstack (&st, 0);
	if (r != 0)
		return r;

	sigemptyset (&act.sa_mask);
	act.sa_flags = SA_NODEFER | SA_ONSTACK | SA_RESETHAND | SA_SIGINFO;
	act.sa_sigaction = segv_handler;
		return sigaction (SIGSEGV, &act, 0);
}

static int
recurse (char *p)
{
	char array[500];
	array[0] = 1;
	return *p + recurse (array);
}

int main (void)
{
	c_stack_action ();
	return recurse ("\1");
}