#ifndef _XOPEN_SOURCE
#define _XOPEN_SOURCE 800
#endif
#include <locale.h>
#include <signal.h>
#include <stdatomic.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>

static atomic_uintptr_t stack_base;
static atomic_size_t stack_size;
static atomic_int stack_flags;

static void handler(int signo, siginfo_t *restrict info, void *context) {
	// context = ((ucontext_t *)context)->uc_link;
	if(!context) {
		return;
	}
	const stack_t stack = ((ucontext_t *)context)->uc_stack;
	stack_base = (uintptr_t)stack.ss_sp;
	stack_size = stack.ss_size;
	stack_flags = stack.ss_flags;
}

int main(void) {
	(void)setlocale(LC_ALL, "");
	if(!atomic_is_lock_free(&stack_base) || !atomic_is_lock_free(&stack_size) || !atomic_is_lock_free(&stack_flags)) {
		fputs("Atomic type is not lock-free\n", stderr);
		exit(EXIT_FAILURE);
	}

	struct sigaction act = {
		.sa_sigaction = handler,
		.sa_flags = SA_SIGINFO
	};
	if(sigemptyset(&act.sa_mask) == -1
	|| sigprocmask(SIG_SETMASK, &act.sa_mask, NULL) == -1
	|| sigaction(SIGUSR1, &act, NULL) == -1
	|| raise(SIGUSR1)
	|| printf("%p\t%zu\t%#x\n", (void *)stack_base, (size_t)stack_size, (unsigned int)stack_flags) < 0) {
		perror(NULL);
		exit(EXIT_FAILURE);
	}
}