utils/isohybrid.c

   1 /*
   2  * isohybrid.c: Post process an ISO 9660 image generated with mkisofs or
   3  * genisoimage to allow - hybrid booting - as a CD-ROM or as a hard
   4  * disk.
   5  *
   6  * This is based on the original Perl script written by H. Peter Anvin. The
   7  * rewrite in C is to avoid dependency on Perl on a system under installation.
   8  *
   9  * Copyright (C) 2010 P J P <pj.pandit@yahoo.co.in>
  10  *
  11  * isohybrid is a free software; you can redistribute it and/or modify it
  12  * under the terms of GNU General Public License as published by Free Software
  13  * Foundation; either version 2 of the license, or (at your option) any later
  14  * version.
  15  *
  16  * isohybrid is distributed in the hope that it will be useful, but WITHOUT
  17  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  18  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  19  * more details.
  20  *
  21  * You should have received a copy of the GNU General Public License along
  22  * with isohybrid; if not, see: <http://www.gnu.org/licenses>.
  23  *
  24  */
  25
  26 #include <err.h>
  27 #include <time.h>
  28 #include <ctype.h>
  29 #include <fcntl.h>
  30 #include <stdio.h>
  31 #include <alloca.h>
  32 #include <getopt.h>
  33 #include <signal.h>
  34 #include <stdlib.h>
  35 #include <string.h>
  36 #include <unistd.h>
  37 #include <sys/stat.h>
  38 #include <inttypes.h>
  39
  40 #include "isohybrid.h"
  41
  42 char *prog = NULL;
  43 extern int opterr, optind;
  44
  45 uint8_t mode = 0;
  46 enum { VERBOSE = 1 };
  47
  48 /* user options */
  49 uint16_t head = 64;             /* 1 <= head <= 256 */
  50 uint8_t sector = 32;            /* 1 <= sector <= 63  */
  51
  52 uint8_t entry = 1;              /* partition number: 1 <= entry <= 4 */
  53 uint8_t offset = 0;             /* partition offset: 0 <= offset <= 64 */
  54 uint16_t type = 0x17;           /* partition type: 0 <= type <= 255 */
  55 uint32_t id = 0;                /* MBR: 0 <= id <= 0xFFFFFFFF(4294967296) */
  56
  57 uint8_t hd0 = 0;                /* 0 <= hd0 <= 2 */
  58 uint8_t partok = 0;             /* 0 <= partok <= 1 */
  59
  60 uint16_t ve[16];
  61 uint32_t catoffset = 0;
  62 uint32_t c = 0, cc = 0, cs = 0;
  63
  64 /* boot catalogue parameters */
  65 uint32_t de_lba = 0;
  66 uint16_t de_seg = 0, de_count = 0, de_mbz2 = 0;
  67 uint8_t de_boot = 0, de_media = 0, de_sys = 0, de_mbz1 = 0;
  68
  69
  70 void
  71 usage(void)
  72 {
  73     printf("Usage: %s [OPTIONS] <boot.iso>\n", prog);
  74 }
  75
  76
  77 void
  78 printh(void)
  79 {
  80 #define FMT "%-18s %s\n"
  81
  82     usage();
  83
  84     printf("\n");
  85     printf("Options:\n");
  86     printf(FMT, "   -h <X>", "Number of default geometry heads");
  87     printf(FMT, "   -s <X>", "Number of default geometry sectors");
  88     printf(FMT, "   -e --entry", "Specify partition entry number (1-4)");
  89     printf(FMT, "   -o --offset", "Specify partition offset (default 0)");
  90     printf(FMT, "   -t --type", "Specify partition type (default 0x17)");
  91     printf(FMT, "   -i --id", "Specify MBR ID (default random)");
  92
  93     printf("\n");
  94     printf(FMT, "   --forcehd0", "Assume we are loaded as disk ID 0");
  95     printf(FMT, "   --ctrlhd0", "Assume disk ID 0 if the Ctrl key is pressed");
  96     printf(FMT, "   --partok", "Allow booting from within a partition");
  97
  98     printf("\n");
  99     printf(FMT, "   -? --help", "Display this help");
 100     printf(FMT, "   -v --verbose", "Display verbose output");
 101     printf(FMT, "   -V --version", "Display version information");
 102
 103     printf("\n");
 104     printf("Report bugs to <pj.pandit@yahoo.co.in>\n");
 105 }
 106
 107
 108 int
 109 check_option(int argc, char *argv[])
 110 {
 111     int n = 0, ind = 0;
 112
 113     const char optstr[] = ":h:s:e:o:t:i:fcp?vV";
 114     struct option lopt[] = \
 115     {
 116         { "entry", required_argument, NULL, 'e' },
 117         { "offset", required_argument, NULL, 'o' },
 118         { "type", required_argument, NULL, 't' },
 119         { "id", required_argument, NULL, 'i' },
 120
 121         { "forcehd0", no_argument, NULL, 'f' },
 122         { "ctrlhd0", no_argument, NULL, 'c' },
 123         { "partok", no_argument, NULL, 'p'},
 124
 125         { "help", no_argument, NULL, '?' },
 126         { "verbose", no_argument, NULL, 'v' },
 127         { "version", no_argument, NULL, 'V' },
 128
 129         { 0, 0, 0, 0 }
 130     };
 131
 132     opterr = mode = 0;
 133     while ((n = getopt_long_only(argc, argv, optstr, lopt, &ind)) != -1)
 134     {
 135         switch (n)
 136         {
 137         case 'h':
 138             if (!sscanf(optarg, "%hu", &head) || head < 1 || head > 256)
 139                 errx(1, "invalid head: `%s', 1 <= head <= 256", optarg);
 140             break;
 141
 142         case 's':
 143             if (!sscanf(optarg, "%hhu", &sector) || sector < 1 || sector > 63)
 144                 errx(1, "invalid sector: `%s', 1 <= sector <= 63", optarg);
 145             break;
 146
 147         case 'e':
 148             if (!sscanf(optarg, "%hhu", &entry) || entry < 1 || entry > 4)
 149                 errx(1, "invalid entry: `%s', 1 <= entry <= 4", optarg);
 150             break;
 151
 152         case 'o':
 153             if (!sscanf(optarg, "%hhu", &offset) || offset > 64)
 154                 errx(1, "invalid offset: `%s', 0 <= offset <= 64", optarg);
 155             break;
 156
 157         case 't':
 158             if (!sscanf(optarg, "%hu", &type) || type > 255)
 159                 errx(1, "invalid type: `%s', 0 <= type <= 255", optarg);
 160             break;
 161
 162         case 'i':
 163             if (!sscanf(optarg, "%u", &id))
 164                 errx(1, "invalid id: `%s'", optarg);
 165             break;
 166
 167         case 'f':
 168             hd0 = 1;
 169             break;
 170
 171         case 'c':
 172             hd0 = 2;
 173             break;
 174
 175         case 'p':
 176             partok = 1;
 177             break;
 178
 179         case 'v':
 180             mode |= VERBOSE;
 181             break;
 182
 183         case 'V':
 184             printf("%s version %s\n", prog, VERSION);
 185             exit(0);
 186
 187         case ':':
 188             errx(1, "option `-%c' takes an argument", optopt);
 189
 190         default:
 191         case '?':
 192             if (optopt)
 193                 errx(1, "invalid option `-%c', see --help", optopt);
 194
 195             printh();
 196             exit(0);
 197         }
 198     }
 199
 200     return optind;
 201 }
 202
 203
 204 uint16_t
 205 lendian_short(const uint16_t s)
 206 {
 207     uint16_t r = 1;
 208
 209     if (*(uint8_t *)&r)
 210         return s;
 211
 212     r = (s & 0x00FF) << 8 | (s & 0xFF00) >> 8;
 213
 214     return r;
 215 }
 216
 217
 218 uint32_t
 219 lendian_int(const uint32_t s)
 220 {
 221     uint32_t r = 1;
 222
 223     if (*(uint8_t *)&r)
 224         return s;
 225
 226     r = (s & 0x000000FF) << 24 | (s & 0xFF000000) >> 24
 227         | (s & 0x0000FF00) << 8 | (s & 0x00FF0000) >> 8;
 228
 229     return r;
 230 }
 231
 232
 233 int
 234 check_banner(const uint8_t *buf)
 235 {
 236     static const char banner[] = "\0CD001\1EL TORITO SPECIFICATION\0\0\0\0" \
 237         "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0" \
 238         "\0\0\0\0\0";
 239
 240     if (!buf || memcmp(buf, banner, sizeof(banner) - 1))
 241         return 1;
 242
 243     buf += sizeof(banner) - 1;
 244     memcpy(&catoffset, buf, sizeof(catoffset));
 245
 246     catoffset = lendian_int(catoffset);
 247
 248     return 0;
 249 }
 250
 251
 252 int
 253 check_catalogue(const uint8_t *buf)
 254 {
 255     int i = 0;
 256
 257     for (i = 0, cs = 0; i < 16; i++)
 258     {
 259         ve[i] = 0;
 260         memcpy(&ve[i], buf, sizeof(ve[i]));
 261
 262         ve[i] = lendian_short(ve[i]);
 263
 264         buf += 2;
 265         cs += ve[i];
 266
 267         if (mode & VERBOSE)
 268             printf("ve[%d]: %d, cs: %d\n", i, ve[i], cs);
 269     }
 270     if ((ve[0] != 0x0001) || (ve[15] != 0xAA55) || (cs & 0xFFFF))
 271         return 1;
 272
 273     return 0;
 274 }
 275
 276
 277 int
 278 read_catalogue(const uint8_t *buf)
 279 {
 280     memcpy(&de_boot, buf++, 1);
 281     memcpy(&de_media, buf++, 1);
 282
 283     memcpy(&de_seg, buf, 2);
 284     de_seg = lendian_short(de_seg);
 285     buf += 2;
 286
 287     memcpy(&de_sys, buf++, 1);
 288     memcpy(&de_mbz1, buf++, 1);
 289
 290     memcpy(&de_count, buf, 2);
 291     de_count = lendian_short(de_count);
 292     buf += 2;
 293
 294     memcpy(&de_lba, buf, 4);
 295     de_lba = lendian_int(de_lba);
 296     buf += 4;
 297
 298     memcpy(&de_mbz2, buf, 2);
 299     de_mbz2 = lendian_short(de_mbz2);
 300     buf += 2;
 301
 302     if (de_boot != 0x88 || de_media != 0
 303         || (de_seg != 0 && de_seg != 0x7C0) || de_count != 4)
 304         return 1;
 305
 306     return 0;
 307 }
 308
 309
 310 void
 311 display_catalogue(void)
 312 {
 313     printf("de_boot: %hhu\n", de_boot);
 314     printf("de_media: %hhu\n", de_media);
 315     printf("de_seg: %hu\n", de_seg);
 316     printf("de_sys: %hhu\n", de_sys);
 317     printf("de_mbz1: %hhu\n", de_mbz1);
 318     printf("de_count: %hu\n", de_count);
 319     printf("de_lba: %u\n", de_lba);
 320     printf("de_mbz2: %hu\n", de_mbz2);
 321 }
 322
 323
 324 int
 325 initialise_mbr(uint8_t *mbr)
 326 {
 327     int i = 0;
 328     uint32_t psize = 0, tmp = 0;
 329     uint8_t ptype = 0, *rbm = mbr;
 330     uint8_t bhead = 0, bsect = 0, bcyle = 0;
 331     uint8_t ehead = 0, esect = 0, ecyle = 0;
 332
 333     extern unsigned char isohdpfx[][MBRSIZE];
 334
 335     memcpy(mbr, &isohdpfx[hd0 + 3 * partok], MBRSIZE);
 336     mbr += MBRSIZE;                                 /* offset 432 */
 337
 338     tmp = lendian_int(de_lba * 4);
 339     memcpy(mbr, &tmp, sizeof(tmp));
 340     mbr += sizeof(tmp);                             /* offset 436 */
 341
 342     tmp = 0;
 343     memcpy(mbr, &tmp, sizeof(tmp));
 344     mbr += sizeof(tmp);                             /* offset 440 */
 345
 346     tmp = lendian_int(id);
 347     memcpy(mbr, &tmp, sizeof(tmp));
 348     mbr += sizeof(tmp);                             /* offset 444 */
 349
 350     mbr[0] = '\0';
 351     mbr[1] = '\0';
 352     mbr += 2;                                       /* offset 446 */
 353
 354     ptype = type;
 355     psize = c * head * sector - offset;
 356
 357     bhead = (offset / sector) % head;
 358     bsect = (offset % sector) + 1;
 359     bcyle = offset / (head * sector);
 360
 361     bsect += (bcyle & 0x300) >> 2;
 362     bcyle  &= 0xFF;
 363
 364     ehead = head - 1;
 365     esect = sector + (((cc - 1) & 0x300) >> 2);
 366     ecyle = (cc - 1) & 0xFF;
 367
 368     for (i = 1; i <= 4; i++)
 369     {
 370         memset(mbr, 0, 16);
 371         if (i == entry)
 372         {
 373             mbr[0] = 0x80;
 374             mbr[1] = bhead;
 375             mbr[2] = bsect;
 376             mbr[3] = bcyle;
 377             mbr[4] = ptype;
 378             mbr[5] = ehead;
 379             mbr[6] = esect;
 380             mbr[7] = ecyle;
 381
 382             tmp = lendian_int(offset);
 383             memcpy(&mbr[8], &tmp, sizeof(tmp));
 384
 385             tmp = lendian_int(psize);
 386             memcpy(&mbr[12], &tmp, sizeof(tmp));
 387         }
 388         mbr += 16;
 389     }
 390     mbr[0] = 0x55;
 391     mbr[1] = 0xAA;
 392     mbr += 2;
 393
 394     return mbr - rbm;
 395 }
 396
 397
 398 void
 399 display_mbr(const uint8_t *mbr, size_t len)
 400 {
 401     unsigned char c = 0;
 402     unsigned int i = 0, j = 0;
 403
 404     printf("sizeof(MBR): %zu bytes\n", len);
 405     for (i = 0; i < len; i++)
 406     {
 407         if (!(i % 16))
 408             printf("%04d ", i);
 409
 410         if (!(i % 8))
 411             printf(" ");
 412
 413         c = mbr[i];
 414         printf("%02x ", c);
 415
 416         if (!((i + 1) % 16))
 417         {
 418             printf(" |");
 419             for (; j <= i; j++)
 420                 printf("%c", isprint(mbr[j]) ? mbr[j] : '.');
 421             printf("|\n");
 422         }
 423     }
 424 }
 425
 426
 427 int
 428 main(int argc, char *argv[])
 429 {
 430     int i = 0;
 431     FILE *fp = NULL;
 432     struct stat isostat;
 433     uint8_t *buf = NULL, *bufz = NULL;
 434     int cylsize = 0, frac = 0, padding = 0;
 435
 436     prog = strcpy(alloca(strlen(argv[0]) + 1), argv[0]);
 437     i = check_option(argc, argv);
 438     argc -= i;
 439     argv += i;
 440
 441     if (!argc)
 442     {
 443         usage();
 444         return 1;
 445     }
 446     srand(time(NULL) << (getppid() << getpid()));
 447
 448     if (!(fp = fopen(argv[0], "r+")))
 449         err(1, "could not open file `%s'", argv[0]);
 450     if (fseek(fp, 17 * 2048, SEEK_SET))
 451         err(1, "%s: seek error - 1", argv[0]);
 452
 453     bufz = buf = calloc(BUFSIZE, sizeof(char));
 454     if (fread(buf, sizeof(char), BUFSIZE, fp) != BUFSIZE)
 455         err(1, "%s", argv[0]);
 456
 457     if (check_banner(buf))
 458         errx(1, "%s: could not find boot record", argv[0]);
 459
 460     if (mode & VERBOSE)
 461         printf("catalogue offset: %d\n", catoffset);
 462
 463     if (fseek(fp, catoffset * 2048, SEEK_SET))
 464         err(1, "%s: seek error - 2", argv[0]);
 465
 466     buf = bufz;
 467     memset(buf, 0, BUFSIZE);
 468     if (fread(buf, sizeof(char), BUFSIZE, fp) != BUFSIZE)
 469         err(1, "%s", argv[0]);
 470
 471     if (check_catalogue(buf))
 472         errx(1, "%s: invalid boot catalogue", argv[0]);
 473
 474     buf += sizeof(ve);
 475     if (read_catalogue(buf))
 476         errx(1, "%s: unexpected boot catalogue parameters", argv[0]);
 477
 478     if (mode & VERBOSE)
 479         display_catalogue();
 480
 481     if (fseek(fp, (de_lba * 2048 + 0x40), SEEK_SET))
 482         err(1, "%s: seek error - 3", argv[0]);
 483
 484     buf = bufz;
 485     memset(buf, 0, BUFSIZE);
 486     if (fread(buf, sizeof(char), 4, fp) != 4)
 487         err(1, "%s", argv[0]);
 488
 489     if (memcmp(buf, "\xFB\xC0\x78\x70", 4))
 490         errx(1, "%s: boot loader does not have an isolinux.bin hybrid " \
 491                  "signature. Note that isolinux-debug.bin does not support " \
 492                  "hybrid booting", argv[0]);
 493
 494     if (stat(argv[0], &isostat))
 495         err(1, "%s", argv[0]);
 496
 497     cylsize = head * sector * 512;
 498     frac = isostat.st_size % cylsize;
 499     padding = (frac > 0) ? cylsize - frac : 0;
 500
 501     if (mode & VERBOSE)
 502         printf("imgsize: %zu, padding: %d\n", (size_t)isostat.st_size, padding);
 503
 504     cc = c = (isostat.st_size + padding) / cylsize;
 505     if (c > 1024)
 506     {
 507         warnx("Warning: more than 1024 cylinders: %d", c);
 508         warnx("Not all BIOSes will be able to boot this device");
 509         cc = 1024;
 510     }
 511
 512     if (!id)
 513     {
 514         if (fseek(fp, 440, SEEK_SET))
 515             err(1, "%s: seek error - 4", argv[0]);
 516
 517         if (fread(&id, 1, 4, fp) != 4)
 518             err(1, "%s: read error", argv[0]);
 519
 520         id = lendian_int(id);
 521         if (!id)
 522         {
 523             if (mode & VERBOSE)
 524                 printf("random ");
 525             id = rand();
 526         }
 527     }
 528     if (mode & VERBOSE)
 529         printf("id: %u\n", id);
 530
 531     buf = bufz;
 532     memset(buf, 0, BUFSIZE);
 533     i = initialise_mbr(buf);
 534
 535     if (mode & VERBOSE)
 536         display_mbr(buf, i);
 537
 538     if (fseek(fp, 0, SEEK_SET))
 539         err(1, "%s: seek error - 5", argv[0]);
 540
 541     if (fwrite(buf, sizeof(char), i, fp) != (size_t)i)
 542         err(1, "%s: write error - 1", argv[0]);
 543
 544     if (padding)
 545     {
 546         if (fsync(fileno(fp)))
 547             err(1, "%s: could not synchronise", argv[0]);
 548
 549         if (ftruncate(fileno(fp), isostat.st_size + padding))
 550             err(1, "%s: could not add padding bytes", argv[0]);
 551     }
 552
 553     free(buf);
 554     fclose(fp);
 555
 556     return 0;
 557 }