/*      $OpenBSD: cansig.c,v 1.2 2021/12/13 16:56:50 deraadt Exp $      */
/*      Written by Michael Shalayeff, 2008. Public Domain       */

#include <sys/types.h>
#include <signal.h>
#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <err.h>

int
main()
{
        pid_t   pid;
        int     serrno;

        if ((pid = fork()) < 0)
                err(1, "fork");

        /* nun sex */
        if (!pid) {
                if (seteuid(1))
                        err(1, "seteuid");
                sleep(3);
                return 0;
        }

        /* monk rock */
        sleep(1);
        /* first see if we can still do it */
        if (kill(pid, 0)) {
                serrno = errno;
                kill(pid, SIGKILL);
                errno = serrno;
                err(1, "kill0");
        }
        if (setreuid(1, 1)) {
                serrno = errno;
                kill(pid, SIGKILL);
                errno = serrno;
                err(1, "seteuid1");
        }
        /* not allowed */
        if (!kill(pid, 0))
                errx(1, "kill1");

        /* we can't collect the remains from the kiddo */
        return 0;
}