sbin/nextboot/nextboot.c

   1 /*
   2  * Copyright (c) 1996 Whistle Communications
   3  * All Rights Reserved.
   4  *
   5  * Permission to use, copy, modify and distribute this software and its
   6  * documentation is hereby granted, provided that both the copyright
   7  * notice and this permission notice appear in all copies of the
   8  * software, derivative works or modified versions, and any portions
   9  * thereof, and that both notices appear in supporting documentation.
  10  *
  11  * Whistle Communications allows free use of this software in its "as is"
  12  * condition.  Whistle Communications disclaims any liability of any kind for
  13  * any damages whatsoever resulting from the use of this software.
  14  *
  15  * $FreeBSD: src/sbin/i386/nextboot/nextboot.c,v 1.6 1999/08/28 00:13:06 peter Exp $
  16  * $DragonFly: src/sbin/i386/nextboot/nextboot.c,v 1.5 2007/05/20 23:21:36 dillon Exp $
  17  */
  18
  19 #include <sys/types.h>
  20 #include <sys/diskmbr.h>
  21 #include <fcntl.h>
  22 #include <err.h>
  23 #include <stdio.h>
  24 #include <stdlib.h>
  25 #include <string.h>
  26 #include <unistd.h>
  27
  28 struct mboot
  29 {
  30         unsigned char padding[2]; /* force the longs to be long aligned */
  31         unsigned char bootinst[DOSPARTOFF];
  32         struct  dos_partition parts[4];
  33         unsigned short int      signature;
  34 };
  35 struct mboot mboot;
  36
  37 #define NAMEBLOCK 1 /* 2nd block */
  38 #define BLOCKSIZE 512
  39 #define ENABLE_MAGIC 0xfadefeed
  40 #define DISABLE_MAGIC 0xfadefade
  41 static int      bflag;
  42 static int      eflag;
  43 static int      dflag;
  44
  45 #define BOOT_MAGIC 0xAA55
  46
  47 static void
  48 usage(void) {
  49         fprintf (stderr, "%s\n%s\n",
  50         "usage: nextboot [-b] device bootstring [bootstring] ...",
  51         "       nextboot {-e,-d} device");
  52         exit(1);
  53 }
  54
  55 int
  56 main (int argc, char** argv)
  57 {
  58         int     fd = -1;
  59         char namebuf[1024], *cp = namebuf;
  60         int     i,j;
  61         int     ch;
  62         int     part;
  63
  64         bflag = 0;
  65         while ((ch = getopt(argc, argv, "bde")) != -1) {
  66                 switch(ch) {
  67                 case 'b':
  68                         bflag = 1;
  69                         break;
  70                 case 'd':
  71                         dflag = 1;
  72                         break;
  73                 case 'e':
  74                         eflag = 1;
  75                         break;
  76                 case '?':
  77                 default:
  78                         usage();
  79                 }
  80         }
  81         argc -= optind;
  82         argv += optind;
  83
  84         if ( (dflag + eflag + bflag) > 1 ) {
  85                 usage();
  86         }
  87         if (dflag + eflag){
  88                 if(argc != 1 ) {
  89                         usage();
  90                 }
  91         } else {
  92                 if (argc <2) {
  93                         usage();
  94                 }
  95         }
  96         if ((fd = open(argv[0], O_RDWR, 0)) < 0)
  97                 errx(1, "can't open %s", argv[0]);
  98
  99         argc--;
 100         argv++;
 101
 102         /*******************************************
 103          * Check that we have an MBR
 104          */
 105         if (lseek(fd,0,0) == -1)
 106                 err(1, "lseek");
 107         if (read (fd,&mboot.bootinst[0],BLOCKSIZE ) != BLOCKSIZE)
 108                 err(1, "read0");
 109         if (mboot.signature != (unsigned short)BOOT_MAGIC)
 110                 errx(1, "no fdisk part.. not touching block 1");
 111
 112         /*******************************************
 113          * And check that none of the partitions in it cover the name block;
 114          */
 115         for ( part = 0; part < 4; part++) {
 116                 if( mboot.parts[part].dp_size
 117                  && (mboot.parts[part].dp_start <= NAMEBLOCK)
 118                  && (mboot.parts[part].dp_start
 119                         + mboot.parts[part].dp_size > NAMEBLOCK))
 120                         errx(1,
 121                 "name sector lies within a Bios partition: aborting write");
 122         }
 123
 124
 125         /*******************************************
 126          *  Now check the  name sector itself to see if it's been initialized.
 127          */
 128         if (lseek(fd,NAMEBLOCK * BLOCKSIZE,0) == -1)
 129                 err(1, "lseek");
 130         if (read(fd,namebuf,BLOCKSIZE) != BLOCKSIZE)
 131                 err(1, "read1");
 132         /*******************************************
 133          * check if we are just enabling or disabling
 134          * Remember the flags are exclusive..
 135          */
 136         if(!bflag) { /* don't care what's there if bflag is set */
 137                 switch(*(unsigned long *)cp)
 138                 {
 139                 case    DISABLE_MAGIC:
 140                 case    ENABLE_MAGIC:
 141                         break;
 142                 default:
 143                         errx(1, "namesector not initialized, use the -b flag");
 144                 }
 145         }
 146
 147
 148         /*******************************************
 149          *  If the z or r flag is set, damage or restore the magic number..
 150          * to disable/enable the feature
 151          */
 152         if(dflag) {
 153                 *(unsigned long *)cp = DISABLE_MAGIC;
 154         } else {
 155                 *(unsigned long *)cp = ENABLE_MAGIC;
 156         }
 157         if ((!dflag) && (!eflag)) {
 158                 /*******************************************
 159                  *  Create a new namesector in ram
 160                  */
 161                 cp += 4;
 162                 for ( i = 0 ; i < argc ; i++ ) {
 163                         *cp++ = 'D';
 164                         *cp++ = 'N';
 165                         j = strlen(argv[i]);
 166                         strncpy(cp,argv[i],j);
 167                         cp += j;
 168                         *cp++ = 0;
 169                 }
 170                 *cp++ = 0xff;
 171                 *cp++ = 0xff;
 172                 *cp++ = 0xff;
 173                 namebuf[BLOCKSIZE-1] = 0; /* paranoid */
 174                 namebuf[BLOCKSIZE] = 0xff;
 175         }
 176
 177         /*******************************************
 178          *  write it to disk.
 179          */
 180         if (lseek(fd,NAMEBLOCK * BLOCKSIZE,0) == -1)
 181                 err(1, "lseek");
 182         if(write (fd,namebuf,BLOCKSIZE ) != BLOCKSIZE)
 183                 err(1, "write");
 184
 185 #if 0
 186         /*******************************************
 187          * just to be safe/paranoid.. read it back..
 188          * and print it..
 189          */
 190         if (lseek(fd,NAMEBLOCK * BLOCKSIZE,0) == -1)
 191                 err(1, "lseek (second)");
 192         read (fd,namebuf,512);
 193         for (i = 0;i< 16;i++) {
 194                 for ( j = 0; j < 16; j++) {
 195                         printf("%02x ",(unsigned char )namebuf[(i*16) + j ]);
 196                 }
 197                 printf("\n");
 198         }
 199 #endif
 200         exit(0);
 201 }