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));

	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");
	}

// be invoked with all registers msan-undefined.
__attribute__((noinline))
void msanGoWait(unsigned long a1, unsigned long a2, unsigned long a3, unsigned long a4, unsigned long a5, unsigned long a6) {
	sigset_t mask;

	sigemptyset(&mask);
        sigsuspend(&mask);
}

// msanGoSignalThread is the thread ID of the msanGoLoop thread.
static pthread_t msanGoSignalThread;

// msanGoSignalThreadSet is used to record that msanGoSignalThread