/*      $OpenBSD: confuse.c,v 1.1 2005/12/07 01:43:39 pedro Exp $       */

/*
 * Written by Artur Grabowski <art@openbsd.org> in 2002. Public Domain.
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <err.h>
#include <fcntl.h>
#include <errno.h>

int
main(int argc, char *argv[])
{
        char fname[64];
        int fd, newfd;

        if ((fd = open("/dev/null", O_RDONLY)) < 0)
                err(1, "open(/dev/null)");

        /* Try to confuse fdescfs by making it open into itself. */
        close(fd);

        snprintf(fname, sizeof(fname), "/dev/fd/%d", fd);

        if ((newfd = open(fname, O_RDONLY)) == fd)
                errx(1, "open of %s to %d succeeded, beware.", fname, fd);

        if (newfd >= 0)
                errx(1, "open(%s) gave us the unexpected %d", fname, fd);

        if (errno == ENOENT)
                err(1, "open(%s)", fname);

        if (errno == ENXIO)
                errx(1, "no support for fdesc in kernel"); 

        warn("errno was (%d)", errno);

        return 0;
}