#include <assert.h>
#include <stddef.h>
#include <string.h>
#include <signal.h>
#include <unistd.h>
#include <sys/wait.h>
#include <sys/socket.h>
#include <sys/un.h>

static void
handler(int sig)
{
	assert(close(1) == 0);
	_exit(0);
}

int
main(int ac, const char **av)
{
	struct sockaddr_un addr = {
		.sun_family = AF_UNIX,
	};
	socklen_t len;

	assert(ac == 2);
	assert(strlen(av[1]) > 0);

	strncpy(addr.sun_path, av[1], sizeof(addr.sun_path));
	len = offsetof(struct sockaddr_un, sun_path) + strlen(av[1]) + 1;
	if (len > sizeof(addr))
		len = sizeof(addr);

	unlink(av[1]);
	close(0);
	close(1);

	assert(socket(PF_LOCAL, SOCK_STREAM, 0) == 0);
	assert(bind(0, (struct sockaddr *) &addr, len) == 0);
	assert(listen(0, 5) == 0);

	memset(&addr, 0, sizeof addr);
	assert(getsockname(0, (struct sockaddr *) &addr, &len) == 0);
	if (len > sizeof(addr))
		len = sizeof(addr);

	pid_t pid = fork();
	assert(pid >= 0);

	if (pid) {
		assert(accept(0, (struct sockaddr *) &addr, &len) == 1);
		assert(close(0) == 0);
		assert(kill(pid, SIGUSR1) == 0);
		int status;
		assert(waitpid(pid, &status, 0) == pid);
		assert(status == 0);
		assert(close(1) == 0);
	} else {
		sigset_t set;
		sigemptyset(&set);
		sigaddset(&set, SIGUSR1);

		assert(sigprocmask(SIG_BLOCK, &set, NULL) == 0);
		assert(signal(SIGUSR1, handler) != SIG_ERR);
		assert(socket(PF_LOCAL, SOCK_STREAM, 0) == 1);
		assert(close(0) == 0);
		assert(connect(1, (struct sockaddr *) &addr, len) == 0);
		assert(sigprocmask(SIG_UNBLOCK, &set, NULL) == 0);
		assert(pause() == 99);
		return 1;
	}

	unlink(av[1]);
	return 0;
}