/*
* Return the boot0 version with the minor revision in the low byte, and
* the major revision in the next higher byte.
*/
static int
boot0version(const u_int8_t *bs)
{
/* Check for old version, and return 0x100 if found. */
int v = boot0bs(bs);
if (v != 0)
return v << 8;
/* We have a newer boot0, so extract the version number and return it. */
return *(const int *)(bs + OFF_VERSION) & 0xffff;
}
/*
* Read in the MBR of the disk. If it is boot0, then use the version to
* read in all of it if necessary. Use pointers to return a malloc'd
* buffer containing the MBR and then return its size.
*/
static int
read_mbr(const char *disk, u_int8_t **mbr, int check_version)
{
u_int8_t buf[MBRSIZE];
int mbr_size, fd;
int ver;
ssize_t n;
if ((fd = open(disk, O_RDONLY)) == -1)
err(1, "open %s", disk);
if ((n = read(fd, buf, MBRSIZE)) == -1)
err(1, "read %s", disk);
if (n != MBRSIZE)
errx(1, "%s: short read", disk);
if (cv2(buf + OFF_MAGIC) != 0xaa55)
errx(1, "%s: bad magic", disk);
if (! (ver = boot0bs(buf))) {
if (check_version)
errx(1, "%s: unknown or incompatible boot code", disk);
} else if (boot0version(buf) == 0x101) {
mbr_size = 1024;
if ((*mbr = malloc(mbr_size)) == NULL)
errx(1, "%s: unable to allocate read buffer", disk);
if (lseek(fd, 0, SEEK_SET) == -1 ||
(n = read(fd, *mbr, mbr_size)) == -1)
err(1, "%s", disk);
if (n != mbr_size)
errx(1, "%s: short read", disk);
close(fd);
return (mbr_size);
}
*mbr = malloc(sizeof(buf));
if (*mbr == NULL)
errx(1, "%s: unable to allocate MBR buffer", disk);
memcpy(*mbr, buf, sizeof(buf));
close(fd);
return sizeof(buf);
}