#include <fcntl.h>
#include <kvm.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)
{
    kvm_t * kd;
    struct kinfo_proc * kp;
    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);

    kd = kvm_open(NULL, "/dev/null", NULL, O_RDONLY, "kvm");
    if (kd == NULL)
    {
        return 1;
    }

    kp = kvm_getprocs(kd, KERN_PROC_PID, pid, &cnt);
    if (kp == NULL || cnt != 1)
    {
        return 1;
    }

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