blob: 8a6053133439bfc8d80d061582ca129d5687d168 [file] [log] [blame]
/*
* isohybrid.c: Post process an ISO 9660 image generated with mkisofs or
* genisoimage to allow - hybrid booting - as a CD-ROM or as a hard
* disk.
*
* This is based on the original Perl script written by H. Peter Anvin. The
* rewrite in C is to avoid dependency on Perl on a system under installation.
*
* Copyright (C) 2010 P J P <pj.pandit@yahoo.co.in>
*
* isohybrid is a free software; you can redistribute it and/or modify it
* under the terms of GNU General Public License as published by Free Software
* Foundation; either version 2 of the license, or (at your option) any later
* version.
*
* isohybrid 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 isohybrid; if not, see: <http://www.gnu.org/licenses>.
*
*/
#include <err.h>
#include <time.h>
#include <ctype.h>
#include <fcntl.h>
#include <stdio.h>
#include <alloca.h>
#include <getopt.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/stat.h>
#include <inttypes.h>
#include "isohybrid.h"
char *prog = NULL;
extern int opterr, optind;
uint8_t mode = 0;
enum { VERBOSE = 1 };
/* user options */
uint16_t head = 64; /* 1 <= head <= 256 */
uint8_t sector = 32; /* 1 <= sector <= 63 */
uint8_t entry = 1; /* partition number: 1 <= entry <= 4 */
uint8_t offset = 0; /* partition offset: 0 <= offset <= 64 */
uint16_t type = 0x17; /* partition type: 0 <= type <= 255 */
uint32_t id = 0; /* MBR: 0 <= id <= 0xFFFFFFFF(4294967296) */
uint8_t hd0 = 0; /* 0 <= hd0 <= 2 */
uint8_t partok = 0; /* 0 <= partok <= 1 */
uint16_t ve[16];
uint32_t catoffset = 0;
uint32_t c = 0, cc = 0, cs = 0;
/* boot catalogue parameters */
uint32_t de_lba = 0;
uint16_t de_seg = 0, de_count = 0, de_mbz2 = 0;
uint8_t de_boot = 0, de_media = 0, de_sys = 0, de_mbz1 = 0;
void
usage(void)
{
printf("Usage: %s [OPTIONS] <boot.iso>\n", prog);
}
void
printh(void)
{
#define FMT "%-18s %s\n"
usage();
printf("\n");
printf("Options:\n");
printf(FMT, " -h <X>", "Number of default geometry heads");
printf(FMT, " -s <X>", "Number of default geometry sectors");
printf(FMT, " -e --entry", "Specify partition entry number (1-4)");
printf(FMT, " -o --offset", "Specify partition offset (default 0)");
printf(FMT, " -t --type", "Specify partition type (default 0x17)");
printf(FMT, " -i --id", "Specify MBR ID (default random)");
printf("\n");
printf(FMT, " --forcehd0", "Assume we are loaded as disk ID 0");
printf(FMT, " --ctrlhd0", "Assume disk ID 0 if the Ctrl key is pressed");
printf(FMT, " --partok", "Allow booting from within a partition");
printf("\n");
printf(FMT, " -? --help", "Display this help");
printf(FMT, " -v --verbose", "Display verbose output");
printf(FMT, " -V --version", "Display version information");
printf("\n");
printf("Report bugs to <pj.pandit@yahoo.co.in>\n");
}
int
check_option(int argc, char *argv[])
{
char *err = NULL;
int n = 0, ind = 0;
const char optstr[] = ":h:s:e:o:t:i:fcp?vV";
struct option lopt[] = \
{
{ "entry", required_argument, NULL, 'e' },
{ "offset", required_argument, NULL, 'o' },
{ "type", required_argument, NULL, 't' },
{ "id", required_argument, NULL, 'i' },
{ "forcehd0", no_argument, NULL, 'f' },
{ "ctrlhd0", no_argument, NULL, 'c' },
{ "partok", no_argument, NULL, 'p'},
{ "help", no_argument, NULL, '?' },
{ "verbose", no_argument, NULL, 'v' },
{ "version", no_argument, NULL, 'V' },
{ 0, 0, 0, 0 }
};
opterr = mode = 0;
while ((n = getopt_long_only(argc, argv, optstr, lopt, &ind)) != -1)
{
switch (n)
{
case 'h':
head = strtoul(optarg, &err, 0);
if (head < 1 || head > 256)
errx(1, "invalid head: `%s', 1 <= head <= 256", optarg);
break;
case 's':
sector = strtoul(optarg, &err, 0);
if (sector < 1 || sector > 63)
errx(1, "invalid sector: `%s', 1 <= sector <= 63", optarg);
break;
case 'e':
entry = strtoul(optarg, &err, 0);
if (entry < 1 || entry > 4)
errx(1, "invalid entry: `%s', 1 <= entry <= 4", optarg);
break;
case 'o':
offset = strtoul(optarg, &err, 0);
if (*err || offset > 64)
errx(1, "invalid offset: `%s', 0 <= offset <= 64", optarg);
break;
case 't':
type = strtoul(optarg, &err, 0);
if (*err || type > 255)
errx(1, "invalid type: `%s', 0 <= type <= 255", optarg);
break;
case 'i':
id = strtoul(optarg, &err, 0);
if (*err)
errx(1, "invalid id: `%s'", optarg);
break;
case 'f':
hd0 = 1;
break;
case 'c':
hd0 = 2;
break;
case 'p':
partok = 1;
break;
case 'v':
mode |= VERBOSE;
break;
case 'V':
printf("%s version %s\n", prog, VERSION);
exit(0);
case ':':
errx(1, "option `-%c' takes an argument", optopt);
default:
case '?':
if (optopt)
errx(1, "invalid option `-%c', see --help", optopt);
printh();
exit(0);
}
}
return optind;
}
uint16_t
lendian_short(const uint16_t s)
{
uint16_t r = 1;
if (*(uint8_t *)&r)
return s;
r = (s & 0x00FF) << 8 | (s & 0xFF00) >> 8;
return r;
}
uint32_t
lendian_int(const uint32_t s)
{
uint32_t r = 1;
if (*(uint8_t *)&r)
return s;
r = (s & 0x000000FF) << 24 | (s & 0xFF000000) >> 24
| (s & 0x0000FF00) << 8 | (s & 0x00FF0000) >> 8;
return r;
}
int
check_banner(const uint8_t *buf)
{
static const char banner[] = "\0CD001\1EL TORITO SPECIFICATION\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\0\0\0\0" \
"\0\0\0\0\0";
if (!buf || memcmp(buf, banner, sizeof(banner) - 1))
return 1;
buf += sizeof(banner) - 1;
memcpy(&catoffset, buf, sizeof(catoffset));
catoffset = lendian_int(catoffset);
return 0;
}
int
check_catalogue(const uint8_t *buf)
{
int i = 0;
for (i = 0, cs = 0; i < 16; i++)
{
ve[i] = 0;
memcpy(&ve[i], buf, sizeof(ve[i]));
ve[i] = lendian_short(ve[i]);
buf += 2;
cs += ve[i];
if (mode & VERBOSE)
printf("ve[%d]: %d, cs: %d\n", i, ve[i], cs);
}
if ((ve[0] != 0x0001) || (ve[15] != 0xAA55) || (cs & 0xFFFF))
return 1;
return 0;
}
int
read_catalogue(const uint8_t *buf)
{
memcpy(&de_boot, buf++, 1);
memcpy(&de_media, buf++, 1);
memcpy(&de_seg, buf, 2);
de_seg = lendian_short(de_seg);
buf += 2;
memcpy(&de_sys, buf++, 1);
memcpy(&de_mbz1, buf++, 1);
memcpy(&de_count, buf, 2);
de_count = lendian_short(de_count);
buf += 2;
memcpy(&de_lba, buf, 4);
de_lba = lendian_int(de_lba);
buf += 4;
memcpy(&de_mbz2, buf, 2);
de_mbz2 = lendian_short(de_mbz2);
buf += 2;
if (de_boot != 0x88 || de_media != 0
|| (de_seg != 0 && de_seg != 0x7C0) || de_count != 4)
return 1;
return 0;
}
void
display_catalogue(void)
{
printf("de_boot: %hhu\n", de_boot);
printf("de_media: %hhu\n", de_media);
printf("de_seg: %hu\n", de_seg);
printf("de_sys: %hhu\n", de_sys);
printf("de_mbz1: %hhu\n", de_mbz1);
printf("de_count: %hu\n", de_count);
printf("de_lba: %u\n", de_lba);
printf("de_mbz2: %hu\n", de_mbz2);
}
int
initialise_mbr(uint8_t *mbr)
{
int i = 0;
uint32_t psize = 0, tmp = 0;
uint8_t ptype = 0, *rbm = mbr;
uint8_t bhead = 0, bsect = 0, bcyle = 0;
uint8_t ehead = 0, esect = 0, ecyle = 0;
extern unsigned char isohdpfx[][MBRSIZE];
memcpy(mbr, &isohdpfx[hd0 + 3 * partok], MBRSIZE);
mbr += MBRSIZE; /* offset 432 */
tmp = lendian_int(de_lba * 4);
memcpy(mbr, &tmp, sizeof(tmp));
mbr += sizeof(tmp); /* offset 436 */
tmp = 0;
memcpy(mbr, &tmp, sizeof(tmp));
mbr += sizeof(tmp); /* offset 440 */
tmp = lendian_int(id);
memcpy(mbr, &tmp, sizeof(tmp));
mbr += sizeof(tmp); /* offset 444 */
mbr[0] = '\0';
mbr[1] = '\0';
mbr += 2; /* offset 446 */
ptype = type;
psize = c * head * sector - offset;
bhead = (offset / sector) % head;
bsect = (offset % sector) + 1;
bcyle = offset / (head * sector);
bsect += (bcyle & 0x300) >> 2;
bcyle &= 0xFF;
ehead = head - 1;
esect = sector + (((cc - 1) & 0x300) >> 2);
ecyle = (cc - 1) & 0xFF;
for (i = 1; i <= 4; i++)
{
memset(mbr, 0, 16);
if (i == entry)
{
mbr[0] = 0x80;
mbr[1] = bhead;
mbr[2] = bsect;
mbr[3] = bcyle;
mbr[4] = ptype;
mbr[5] = ehead;
mbr[6] = esect;
mbr[7] = ecyle;
tmp = lendian_int(offset);
memcpy(&mbr[8], &tmp, sizeof(tmp));
tmp = lendian_int(psize);
memcpy(&mbr[12], &tmp, sizeof(tmp));
}
mbr += 16;
}
mbr[0] = 0x55;
mbr[1] = 0xAA;
mbr += 2;
return mbr - rbm;
}
void
display_mbr(const uint8_t *mbr, size_t len)
{
unsigned char c = 0;
unsigned int i = 0, j = 0;
printf("sizeof(MBR): %zu bytes\n", len);
for (i = 0; i < len; i++)
{
if (!(i % 16))
printf("%04d ", i);
if (!(i % 8))
printf(" ");
c = mbr[i];
printf("%02x ", c);
if (!((i + 1) % 16))
{
printf(" |");
for (; j <= i; j++)
printf("%c", isprint(mbr[j]) ? mbr[j] : '.');
printf("|\n");
}
}
}
int
main(int argc, char *argv[])
{
int i = 0;
FILE *fp = NULL;
struct stat isostat;
uint8_t *buf = NULL, *bufz = NULL;
int cylsize = 0, frac = 0, padding = 0;
prog = strcpy(alloca(strlen(argv[0]) + 1), argv[0]);
i = check_option(argc, argv);
argc -= i;
argv += i;
if (!argc)
{
usage();
return 1;
}
srand(time(NULL) << (getppid() << getpid()));
if (!(fp = fopen(argv[0], "r+")))
err(1, "could not open file `%s'", argv[0]);
if (fseek(fp, 17 * 2048, SEEK_SET))
err(1, "%s: seek error - 1", argv[0]);
bufz = buf = calloc(BUFSIZE, sizeof(char));
if (fread(buf, sizeof(char), BUFSIZE, fp) != BUFSIZE)
err(1, "%s", argv[0]);
if (check_banner(buf))
errx(1, "%s: could not find boot record", argv[0]);
if (mode & VERBOSE)
printf("catalogue offset: %d\n", catoffset);
if (fseek(fp, catoffset * 2048, SEEK_SET))
err(1, "%s: seek error - 2", argv[0]);
buf = bufz;
memset(buf, 0, BUFSIZE);
if (fread(buf, sizeof(char), BUFSIZE, fp) != BUFSIZE)
err(1, "%s", argv[0]);
if (check_catalogue(buf))
errx(1, "%s: invalid boot catalogue", argv[0]);
buf += sizeof(ve);
if (read_catalogue(buf))
errx(1, "%s: unexpected boot catalogue parameters", argv[0]);
if (mode & VERBOSE)
display_catalogue();
if (fseek(fp, (de_lba * 2048 + 0x40), SEEK_SET))
err(1, "%s: seek error - 3", argv[0]);
buf = bufz;
memset(buf, 0, BUFSIZE);
if (fread(buf, sizeof(char), 4, fp) != 4)
err(1, "%s", argv[0]);
if (memcmp(buf, "\xFB\xC0\x78\x70", 4))
errx(1, "%s: boot loader does not have an isolinux.bin hybrid " \
"signature. Note that isolinux-debug.bin does not support " \
"hybrid booting", argv[0]);
if (stat(argv[0], &isostat))
err(1, "%s", argv[0]);
cylsize = head * sector * 512;
frac = isostat.st_size % cylsize;
padding = (frac > 0) ? cylsize - frac : 0;
if (mode & VERBOSE)
printf("imgsize: %zu, padding: %d\n", (size_t)isostat.st_size, padding);
cc = c = (isostat.st_size + padding) / cylsize;
if (c > 1024)
{
warnx("Warning: more than 1024 cylinders: %d", c);
warnx("Not all BIOSes will be able to boot this device");
cc = 1024;
}
if (!id)
{
if (fseek(fp, 440, SEEK_SET))
err(1, "%s: seek error - 4", argv[0]);
if (fread(&id, 1, 4, fp) != 4)
err(1, "%s: read error", argv[0]);
id = lendian_int(id);
if (!id)
{
if (mode & VERBOSE)
printf("random ");
id = rand();
}
}
if (mode & VERBOSE)
printf("id: %u\n", id);
buf = bufz;
memset(buf, 0, BUFSIZE);
i = initialise_mbr(buf);
if (mode & VERBOSE)
display_mbr(buf, i);
if (fseek(fp, 0, SEEK_SET))
err(1, "%s: seek error - 5", argv[0]);
if (fwrite(buf, sizeof(char), i, fp) != (size_t)i)
err(1, "%s: write error - 1", argv[0]);
if (padding)
{
if (fsync(fileno(fp)))
err(1, "%s: could not synchronise", argv[0]);
if (ftruncate(fileno(fp), isostat.st_size + padding))
err(1, "%s: could not add padding bytes", argv[0]);
}
free(buf);
fclose(fp);
return 0;
}