#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include <unistd.h>
#include <sys/param.h>
#include <sys/sysctl.h>
#include <sys/types.h>
#include <sys/user.h>

int
main(int argc, char ** argv)
{
	int mib[4];
	struct kinfo_proc kp;
	size_t len = sizeof(struct kinfo_proc);
	int cnt = 0;
	pid_t pid;

	if (argc != 2) {
		fprintf(stderr, "Usage: %s pid\n", argv[0]);
		return 1;
	}

	pid = strtol(argv[1], NULL, 10);

	mib[0] = CTL_KERN;
	mib[1] = KERN_PROC;
	mib[2] = KERN_PROC_PID;
	mib[3] = pid;

	if (sysctl(mib, 4, &kp, &len, NULL, 0) == -1)
		return 2;

	if (len == 0)
		return 1;

	printf("Running in jail %d\n", kp.ki_jid);
}