sigset_t mask;
	int i;

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

	if (sigemptyset(&mask) < 0) {
		die("sigemptyset");
	}
	if (sigaddset(&mask, SIGSEGV) < 0) {
		die("sigaddset");
	}
	i = sigprocmask(SIG_UNBLOCK, &mask, NULL);
	if (i != 0) {
		fprintf(stderr, "sigprocmask: %s\n", strerror(i));

		oldHandler(signo, info, ctxt);
	}
}

int install_handler() {
	// Install our own signal handler.
	memset(&sa, 0, sizeof sa);
	sa.sa_sigaction = handler;
	sigemptyset(&sa.sa_mask);
	sa.sa_flags = SA_ONSTACK | SA_SIGINFO;
	memset(&osa, 0, sizeof osa);
	sigemptyset(&osa.sa_mask);
	if (sigaction(SIGSEGV, &sa, &osa) < 0) {
		perror("sigaction");
		return 2;
	}
	if (osa.sa_handler == SIG_DFL) {

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");
	}
	i = sigprocmask(SIG_UNBLOCK, &mask, NULL);
	if (i != 0) {
		fprintf(stderr, "sigprocmask: %s\n", strerror(i));

}

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

static void init() {
    struct sigaction sa;

	memset(&sa, 0, sizeof sa);
	sa.sa_sigaction = pipeHandler;
	if (sigemptyset(&sa.sa_mask) < 0) {
		die("sigemptyset");
	}
	sa.sa_flags = SA_SIGINFO;
	if (sigaction(SIGPIPE, &sa, NULL) < 0) {
		die("sigaction");
	}
}

static void *provokeSIGPIPE(void *arg) {
	ProvokeSIGPIPE();
	return NULL;
}

extern void IntoGoAndBack();

int CheckBlocked() {
	sigset_t mask;
	sigprocmask(SIG_BLOCK, NULL, &mask);
	return sigismember(&mask, SIGIO);
}

static void* sigthreadfunc(void* unused) {
	sigset_t mask;
	sigemptyset(&mask);
	sigaddset(&mask, SIGIO);
	sigprocmask(SIG_BLOCK, &mask, NULL);
	IntoGoAndBack();
	return NULL;
}

int RunSigThread() {
	int tries;
	pthread_t thread;
	int r;
	struct timespec ts;

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

static void init() {
	struct sigaction sa;

	memset(&sa, 0, sizeof sa);
	sa.sa_sigaction = ioHandler;
	if (sigemptyset(&sa.sa_mask) < 0) {
		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

#include <stdlib.h>
#include <string.h>

static void raise_usr2(int signo) {
	raise(SIGUSR2);
}

static void register_handler(int signo) {
	struct sigaction sa;
	memset(&sa, 0, sizeof(sa));
	sigemptyset(&sa.sa_mask);
	sa.sa_flags = SA_ONSTACK;
	sa.sa_handler = raise_usr2;

	if (sigaction(SIGUSR1, &sa, NULL) != 0) {
		perror("failed to register SIGUSR1 handler");
		exit(EXIT_FAILURE);
	}
}
*/
import "C"

	verbose = argc > 2;
	setvbuf(stdout, NULL, _IONBF, 0);

	if (verbose) {
		fprintf(stderr, "calling sigaction\n");
	}

	memset(&sa, 0, sizeof sa);
	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");
	}

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

		prev_sa.sa_handler(signo);
		return;
	}

	fprintf(stderr, "No Go handler to forward to!\n");
	abort();
}

void registerSegvFowarder() {
	struct sigaction sa;
	memset(&sa, 0, sizeof(sa));
	sigemptyset(&sa.sa_mask);
	sa.sa_flags = SA_SIGINFO | SA_ONSTACK;
	sa.sa_sigaction = forwardSignal;

	if (sigaction(SIGSEGV, &sa, &prev_sa) != 0) {
		perror("failed to register SEGV forwarder");
		exit(EXIT_FAILURE);
	}
}

	if (goact) {
		if (goact->flags & SA_SIGINFO) {
			act.sa_sigaction = (void(*)(int, siginfo_t*, void*))(goact->handler);
		} else {
			act.sa_handler = (void(*)(int))(goact->handler);
		}
		sigemptyset(&act.sa_mask);
		for (i = 0; i < 8 * sizeof(goact->mask); i++) {
			if (goact->mask.__bits[i/32] & ((uint32_t)(1)<<(i&31))) {
				sigaddset(&act.sa_mask, i+1);
			}
		}
		act.sa_flags = goact->flags;
	}