sig_atomic_t expectCSigsegv;
int *sigfwdP;

static void sigsegv() {
	expectCSigsegv = 1;
	*sigfwdP = 1;
	fprintf(stderr, "ERROR: C SIGSEGV not thrown on caught?.\n");
	exit(2);
}

static void segvhandler(int signum) {
	if (signum == SIGSEGV) {
		if (expectCSigsegv == 0) {
			fprintf(stderr, "SIGSEGV caught in C unexpectedly\n");
			exit(1);
		}
		fprintf(stdout, "OK\n");
		exit(0);  // success
	}
}

// http://golang.org/issue/17641.
static void callWithVarargs(void* dummy, ...) {
	va_list args;
	va_start(args, dummy);
	va_end(args);
}

// Signal handler for SIGSEGV on a C thread.
static void segvHandler(int signo, siginfo_t* info, void* ctxt) {
	sigset_t mask;
	int i;

	// Call an arbitrary function that requires the stack to be properly aligned.
	callWithVarargs("dummy arg", 3.1415);

	char a[1024];

	recur(4, a);
	sigioSeen = 1;
}

static jmp_buf jmp;
static char* nullPointer;

// Signal handler for SIGSEGV on a C thread.
static void segvHandler(int signo, siginfo_t* info, void* ctxt) {
	sigset_t mask;
	int i;

	if (sigemptyset(&mask) < 0) {
		die("sigemptyset");
	}
	if (sigaddset(&mask, SIGSEGV) < 0) {
		die("sigaddset");
	}