#include <sys/socket.h>
#include <sys/un.h>
#include <sys/wait.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>

int main(int argc, char *argv[]) {
	int fd = socket(AF_UNIX, SOCK_STREAM, 0);
	if (fd < 0) {
		perror("socket");
		return 1;
	}

	pid_t conn_pid = fork();
	if (conn_pid < 0) {
		perror("fork");
		return 1;
	} else if (conn_pid == 0) {
		// On Linux, SO_PEERCRED is stashed on connect
		struct sockaddr_un addr = {
			.sun_family = AF_UNIX,
			.sun_path = "socket",
		};
		if (connect(fd, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
			perror("connect");
			_exit(1);
		}

		execl("./client", NULL);
		perror("exec");
		_exit(1);
	}

	sleep(1);
	printf("connected with PID %d\n", conn_pid);

	int data = 42;
	write(fd, &data, sizeof(data));

	read(fd, &data, sizeof(data));

	return 0;
}