source: projects/initscripts/tags/initscripts-8.91.3/src/genhostid.c @ 1108

/* Copyright (C) 2003 Red Hat, Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License, version 2,
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
 *         
 */

#include <fcntl.h>
#include <stdlib.h>
#include <time.h>
#include <unistd.h>
#include <sys/stat.h>
int
main (void)
{
  struct stat st;
  long int n;
  if (stat ("/etc/hostid", &st) == 0 && S_ISREG (st.st_mode)
      && st.st_size >= sizeof (n))
    return 0;
  int fd = open ("/dev/random", O_RDONLY);
  if (fd == -1 || read (fd, &n, sizeof (n)) != sizeof (n))
    {
      srand48 ((long int) time (NULL) ^ (long int) getpid ());
      n = lrand48 ();
    }
  return sethostid ((int32_t)n);
}