/*   cc -o readlabel sun_read_disk_label.c
 *
 * A simple program to read disk labels on Sun systems .
 *  usage: readlabel /dev/rdsk/cNtXdYsZ
 *
 * Author: Paul Farrall pfarrall@brains2bytes.com
 * Copyright 2001, 2002 Paul Farrall
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or (at
 * your option) any later version.
 * 
 * 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 <stdio.h>
#include <libgen.h>
#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/dklabel.h>

#define MAXLEN    20             /* enough to hold "/dev/rdsk/cXtYdZsN" */
#define PROGNAME  "readlabel"    /* Name of this program */

void usage() {
  printf("Usage:\n\t%s <device name>  (Device name like \"/dev/rdsk/c0t0d0s0\")\n", 
	 PROGNAME);
  return;
}

void err_exit(char * str) {
  perror(str);
  exit(1);
}

int main(int argc, char * argv[]) {

  char            fname[MAXLEN];
  int             fd;
  struct dk_label label;  /* from <sys/dklabel.h> */

  if (argc < 2) {
    usage();
    exit(1);
  }

  if (geteuid() != 0)
    err_exit("You must be root to run this program");

  if (snprintf(fname, MAXLEN, "%s", argv[1]) < strlen(argv[1]))
    err_exit("There was a problem reading arg1");

  if ( (fd = open(fname, O_RDONLY)) < 0)
    err_exit("Problem opening file");

  if (lseek(fd, DK_LABEL_LOC, SEEK_SET) != DK_LABEL_LOC)
    err_exit("Problem with lseek");

  if (read(fd, &label, sizeof(label)) != sizeof(label))
    err_exit("Problem reading file");

  printf("%s  => %s\n", fname, label.dkl_asciilabel);
  return(0);
}