die("sigemptyset");
	}
	sa.sa_flags = SA_SIGINFO | SA_ONSTACK;
	if (sigaction(SIGIO, &sa, NULL) < 0) {
		die("sigaction");
	}
}

// Test raising SIGIO on a C thread with an alternate signal stack
// when there is a Go signal handler for SIGIO.
static void* thread1(void* arg __attribute__ ((unused))) {
	stack_t ss;
	int i;
	stack_t nss;
	struct timespec ts;

	// Set up an alternate signal stack for this thread.

	if (i != 0) {
		fprintf(stderr, "sigprocmask: %s\n", strerror(i));
		exit(EXIT_FAILURE);
	}

	// Don't try this at home.
	longjmp(jmp, signo);

	// We should never get here.
	abort();
}

// Set up the signal handlers in a high priority constructor,
// so that they are installed before the Go code starts.

static void init(void) __attribute__ ((constructor (200)));

		fprintf(stderr, "calling dlopen\n");
	}

	handle = dlopen(argv[1], RTLD_NOW | RTLD_GLOBAL);
	if (handle == NULL) {
		fprintf(stderr, "%s\n", dlerror());
		exit(EXIT_FAILURE);
	}

	// At this point there should not be a Go signal handler
	// installed for SIGIO.

	if (verbose) {
		fprintf(stderr, "raising SIGIO\n");
	}

	if (raise(SIGIO) < 0) {
		die("raise");
	}

	if (verbose) {

	sa.sa_sigaction = ioHandler;
	if (sigemptyset(&sa.sa_mask) < 0) {
		die("sigemptyset");
	}
	sa.sa_flags = SA_SIGINFO;
	if (sigaction(SIGIO, &sa, NULL) < 0) {
		die("sigaction");
	}

	// At this point there should not be a Go signal handler
	// installed for SIGIO.

	if (verbose) {
		printf("raising SIGIO\n");
	}

	if (raise(SIGIO) < 0) {
		die("raise");
	}

	if (verbose) {

	if (i != 0) {
		fprintf(stderr, "sigprocmask: %s\n", strerror(i));
		exit(EXIT_FAILURE);
	}

	// Don't try this at home.
	longjmp(jmp, signo);

	// We should never get here.
	abort();
}

int main(int argc, char** argv) {
	int verbose;
	struct sigaction sa;
	void* handle;
	void (*fn)(void);
	sigset_t mask;
	int i;
	struct timespec ts;

	verbose = argc > 2;