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
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.
9 * Copyright (C) 2010 P J P <pj.pandit@yahoo.co.in>
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
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
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>.
40 #include "isohybrid.h"
43 extern int opterr, optind;
49 uint16_t head = 64; /* 1 <= head <= 256 */
50 uint8_t sector = 32; /* 1 <= sector <= 63 */
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) */
57 uint8_t hd0 = 0; /* 0 <= hd0 <= 2 */
58 uint8_t partok = 0; /* 0 <= partok <= 1 */
61 uint32_t catoffset = 0;
62 uint32_t c = 0, cc = 0, cs = 0;
64 /* boot catalogue parameters */
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;
73 printf("Usage: %s [OPTIONS] <boot.iso>\n", prog);
80 #define FMT "%-18s %s\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)");
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");
99 printf(FMT, " -? --help", "Display this help");
100 printf(FMT, " -v --verbose", "Display verbose output");
101 printf(FMT, " -V --version", "Display version information");
104 printf("Report bugs to <pj.pandit@yahoo.co.in>\n");
109 check_option(int argc, char *argv[])
113 const char optstr[] = ":h:s:e:o:t:i:fcp?vV";
114 struct option lopt[] = \
116 { "entry", required_argument, NULL, 'e' },
117 { "offset", required_argument, NULL, 'o' },
118 { "type", required_argument, NULL, 't' },
119 { "id", required_argument, NULL, 'i' },
121 { "forcehd0", no_argument, NULL, 'f' },
122 { "ctrlhd0", no_argument, NULL, 'c' },
123 { "partok", no_argument, NULL, 'p'},
125 { "help", no_argument, NULL, '?' },
126 { "verbose", no_argument, NULL, 'v' },
127 { "version", no_argument, NULL, 'V' },
133 while ((n = getopt_long_only(argc, argv, optstr, lopt, &ind)) != -1)
138 if (!sscanf(optarg, "%hu", &head) || head < 1 || head > 256)
139 errx(1, "invalid head: `%s', 1 <= head <= 256", optarg);
143 if (!sscanf(optarg, "%hhu", §or) || sector < 1 || sector > 63)
144 errx(1, "invalid sector: `%s', 1 <= sector <= 63", optarg);
148 if (!sscanf(optarg, "%hhu", &entry) || entry < 1 || entry > 4)
149 errx(1, "invalid entry: `%s', 1 <= entry <= 4", optarg);
153 if (!sscanf(optarg, "%hhu", &offset) || offset > 64)
154 errx(1, "invalid offset: `%s', 0 <= offset <= 64", optarg);
158 if (!sscanf(optarg, "%hu", &type) || type > 255)
159 errx(1, "invalid type: `%s', 0 <= type <= 255", optarg);
163 if (!sscanf(optarg, "%u", &id))
164 errx(1, "invalid id: `%s'", optarg);
184 printf("%s version %s\n", prog, VERSION);
188 errx(1, "option `-%c' takes an argument", optopt);
193 errx(1, "invalid option `-%c', see --help", optopt);
205 lendian_short(const uint16_t s)
212 r = (s & 0x00FF) << 8 | (s & 0xFF00) >> 8;
219 lendian_int(const uint32_t s)
226 r = (s & 0x000000FF) << 24 | (s & 0xFF000000) >> 24
227 | (s & 0x0000FF00) << 8 | (s & 0x00FF0000) >> 8;
234 check_banner(const uint8_t *buf)
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" \
240 if (!buf || memcmp(buf, banner, sizeof(banner) - 1))
243 buf += sizeof(banner) - 1;
244 memcpy(&catoffset, buf, sizeof(catoffset));
246 catoffset = lendian_int(catoffset);
253 check_catalogue(const uint8_t *buf)
257 for (i = 0, cs = 0; i < 16; i++)
260 memcpy(&ve[i], buf, sizeof(ve[i]));
262 ve[i] = lendian_short(ve[i]);
268 printf("ve[%d]: %d, cs: %d\n", i, ve[i], cs);
270 if ((ve[0] != 0x0001) || (ve[15] != 0xAA55) || (cs & 0xFFFF))
278 read_catalogue(const uint8_t *buf)
280 memcpy(&de_boot, buf++, 1);
281 memcpy(&de_media, buf++, 1);
283 memcpy(&de_seg, buf, 2);
284 de_seg = lendian_short(de_seg);
287 memcpy(&de_sys, buf++, 1);
288 memcpy(&de_mbz1, buf++, 1);
290 memcpy(&de_count, buf, 2);
291 de_count = lendian_short(de_count);
294 memcpy(&de_lba, buf, 4);
295 de_lba = lendian_int(de_lba);
298 memcpy(&de_mbz2, buf, 2);
299 de_mbz2 = lendian_short(de_mbz2);
302 if (de_boot != 0x88 || de_media != 0
303 || (de_seg != 0 && de_seg != 0x7C0) || de_count != 4)
311 display_catalogue(void)
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);
325 initialise_mbr(uint8_t *mbr)
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;
333 extern unsigned char isohdpfx[][MBRSIZE];
335 memcpy(mbr, &isohdpfx[hd0 + 3 * partok], MBRSIZE);
336 mbr += MBRSIZE; /* offset 432 */
338 tmp = lendian_int(de_lba * 4);
339 memcpy(mbr, &tmp, sizeof(tmp));
340 mbr += sizeof(tmp); /* offset 436 */
343 memcpy(mbr, &tmp, sizeof(tmp));
344 mbr += sizeof(tmp); /* offset 440 */
346 tmp = lendian_int(id);
347 memcpy(mbr, &tmp, sizeof(tmp));
348 mbr += sizeof(tmp); /* offset 444 */
352 mbr += 2; /* offset 446 */
355 psize = c * head * sector - offset;
357 bhead = (offset / sector) % head;
358 bsect = (offset % sector) + 1;
359 bcyle = offset / (head * sector);
361 bsect += (bcyle & 0x300) >> 2;
365 esect = sector + (((cc - 1) & 0x300) >> 2);
366 ecyle = (cc - 1) & 0xFF;
368 for (i = 1; i <= 4; i++)
382 tmp = lendian_int(offset);
383 memcpy(&mbr[8], &tmp, sizeof(tmp));
385 tmp = lendian_int(psize);
386 memcpy(&mbr[12], &tmp, sizeof(tmp));
399 display_mbr(const uint8_t *mbr, size_t len)
402 unsigned int i = 0, j = 0;
404 printf("sizeof(MBR): %zu bytes\n", len);
405 for (i = 0; i < len; i++)
420 printf("%c", isprint(mbr[j]) ? mbr[j] : '.');
428 main(int argc, char *argv[])
433 uint8_t *buf = NULL, *bufz = NULL;
434 int cylsize = 0, frac = 0, padding = 0;
436 prog = strcpy(alloca(strlen(argv[0]) + 1), argv[0]);
437 i = check_option(argc, argv);
446 srand(time(NULL) << (getppid() << getpid()));
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]);
453 bufz = buf = calloc(BUFSIZE, sizeof(char));
454 if (fread(buf, sizeof(char), BUFSIZE, fp) != BUFSIZE)
455 err(1, "%s", argv[0]);
457 if (check_banner(buf))
458 errx(1, "%s: could not find boot record", argv[0]);
461 printf("catalogue offset: %d\n", catoffset);
463 if (fseek(fp, catoffset * 2048, SEEK_SET))
464 err(1, "%s: seek error - 2", argv[0]);
467 memset(buf, 0, BUFSIZE);
468 if (fread(buf, sizeof(char), BUFSIZE, fp) != BUFSIZE)
469 err(1, "%s", argv[0]);
471 if (check_catalogue(buf))
472 errx(1, "%s: invalid boot catalogue", argv[0]);
475 if (read_catalogue(buf))
476 errx(1, "%s: unexpected boot catalogue parameters", argv[0]);
481 if (fseek(fp, (de_lba * 2048 + 0x40), SEEK_SET))
482 err(1, "%s: seek error - 3", argv[0]);
485 memset(buf, 0, BUFSIZE);
486 if (fread(buf, sizeof(char), 4, fp) != 4)
487 err(1, "%s", argv[0]);
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]);
494 if (stat(argv[0], &isostat))
495 err(1, "%s", argv[0]);
497 cylsize = head * sector * 512;
498 frac = isostat.st_size % cylsize;
499 padding = (frac > 0) ? cylsize - frac : 0;
502 printf("imgsize: %lu, padding: %d\n", isostat.st_size, padding);
504 cc = c = (isostat.st_size + padding) / cylsize;
507 warnx("Warning: more than 1024 cylinders: %d", c);
508 warnx("Not all BIOSes will be able to boot this device");
514 if (fseek(fp, 440, SEEK_SET))
515 err(1, "%s: seek error - 4", argv[0]);
517 fread(&id, 4, 1, fp);
518 id = lendian_int(id);
527 printf("id: %u\n", id);
530 memset(buf, 0, BUFSIZE);
531 i = initialise_mbr(buf);
536 if (fseek(fp, 0, SEEK_SET))
537 err(1, "%s: seek error - 5", argv[0]);
539 if (fwrite(buf, sizeof(char), i, fp) != (size_t)i)
540 err(1, "%s: write error - 1", argv[0]);
544 if (!(buf = realloc(buf, padding)))
545 err(1, "%s: could not re-size buffer", argv[0]);
547 if (fseek(fp, isostat.st_size, SEEK_SET))
548 err(1, "%s: seek error - 6", argv[0]);
550 memset(buf, 0, padding);
551 if (fwrite(buf, sizeof(char), padding, fp) != (size_t)padding)
552 err(1, "%s: write error - 2", argv[0]);