static int
validate_label(mbr_args_t *a, uint label_sector)
{
struct disklabel *dlp;
char *dlp_lim, *dlp_byte;
int error;
/* Next, dig out disk label */
if (read_sector(a, label_sector, 2)) {
a->msg = "disk label read failed";
return SCAN_ERROR;
}
/* Locate disk label within block and validate */
/*
* XXX (dsl) This search may be a waste of time, a lot of other i386
* code assumes the label is at offset LABELOFFSET (=0) in the sector.
*
* If we want to support disks from other netbsd ports, then the
* code should also allow for a shorter label nearer the end of
* the disk sector, and (IIRC) labels within 8k of the disk start.
*/
dlp = (void *)a->bp->b_data;
dlp_lim = (char *)a->bp->b_data + a->bp->b_bcount - sizeof *dlp;
for (;; dlp = (void *)((char *)dlp + sizeof(long))) {
if ((char *)dlp > dlp_lim) {
if (a->action != WRITE_LABEL)
return SCAN_CONTINUE;
/* Write at arch. dependant default location */
dlp_byte = (char *)a->bp->b_data + LABELOFFSET;
if (label_sector)
dlp_byte += MBR_LABELSECTOR * a->lp->d_secsize;
else
dlp_byte += LABELSECTOR * a->lp->d_secsize;
dlp = (void *)dlp_byte;
break;
}
if (dlp->d_magic != DISKMAGIC || dlp->d_magic2 != DISKMAGIC)
continue;
if (dlp->d_npartitions > MAXPARTITIONS || dkcksum(dlp) != 0) {
a->msg = "disk label corrupted";
continue;
}
break;
}
switch (a->action) {
case READ_LABEL:
*a->lp = *dlp;
if ((a->msg = convertdisklabel(a->lp, a->strat, a->bp,
a->secperunit)) != NULL)
return SCAN_ERROR;
a->label_sector = label_sector;
return SCAN_FOUND;
case UPDATE_LABEL:
case WRITE_LABEL:
*dlp = *a->lp;
a->bp->b_oflags &= ~BO_DONE;
a->bp->b_flags &= ~B_READ;
a->bp->b_flags |= B_WRITE;
(*a->strat)(a->bp);
error = biowait(a->bp);
if (error != 0) {
a->error = error;
a->msg = "disk label write failed";
return SCAN_ERROR;
}
a->written++;
/* Write label to all mbr partitions */
return SCAN_CONTINUE;
default:
return SCAN_ERROR;
}
}
/*
* Attempt to read a disk label from a device
* using the indicated strategy routine.
* The label must be partly set up before this:
* secpercyl and anything required in the strategy routine
* (e.g., sector size) must be filled in before calling us.
* Returns null on success and an error string on failure.
*/
const char *
readdisklabel(dev_t dev, void (*strat)(struct buf *), struct disklabel *lp,
struct cpu_disklabel *clp)
{
struct buf *bp;
struct disklabel *dlp;
struct dkbad *bdp;
const char *msg = NULL;
uint32_t secperunit;
int i;
/* minimal requirements for archtypal disk label */
if (lp->d_secsize == 0)
lp->d_secsize = DEV_BSIZE;
if (lp->d_secperunit == 0)
lp->d_secperunit = 0x1fffffff;
lp->d_npartitions = RAW_PART + 1;
if (lp->d_partitions[RAW_PART].p_size == 0)
lp->d_partitions[RAW_PART].p_size = lp->d_secperunit;
lp->d_partitions[RAW_PART].p_offset = 0;
secperunit = lp->d_secperunit;
/* obtain buffer to probe drive with */
bp = geteblk((int)lp->d_secsize);
bp->b_dev = dev;
/* Next, dig out disk label. If successful, locate disk
* label within block and validate.
*/
if (disk_read_sectors(strat, lp, bp, LABELSECTOR, 1) != 0) {
msg = "disk label read error";
goto done;
}
for (dlp = (struct disklabel *)bp->b_data;
dlp <= (struct disklabel *)((char *)bp->b_data + lp->d_secsize -
sizeof(*dlp));
dlp = (struct disklabel *)((char *)dlp + sizeof(long))) {
if (dlp->d_magic != DISKMAGIC || dlp->d_magic2 != DISKMAGIC) {
if (msg == NULL)
msg = "no disk label";
} else if (dlp->d_npartitions > MAXPARTITIONS ||
dkcksum(dlp) != 0)
msg = "disk label corrupted";
else {
*lp = *dlp;
msg = NULL;
break;
}
}
if (msg)
goto done;
if ((msg = convertdisklabel(lp, strat, bp, secperunit)) != NULL)
goto done;
/* obtain bad sector table if requested and present */
if (clp && (bdp = &clp->bad) != NULL && (lp->d_flags & D_BADSECT)) {
struct dkbad *db;
i = 0;
do {
/* read a bad sector table */
bp->b_oflags &= ~(BO_DONE);
bp->b_flags |= B_READ;
bp->b_blkno = lp->d_secperunit - lp->d_nsectors + i;
if (lp->d_secsize > DEV_BSIZE)
bp->b_blkno *= lp->d_secsize / DEV_BSIZE;
else
bp->b_blkno /= DEV_BSIZE / lp->d_secsize;
bp->b_bcount = lp->d_secsize;
bp->b_cylinder = lp->d_ncylinders - 1;
(*strat)(bp);
/* if successful, validate, otherwise try another */
if (biowait(bp)) {
msg = "bad sector table I/O error";
} else {
db = (struct dkbad *)(bp->b_data);
#define DKBAD_MAGIC 0x4321
if (db->bt_mbz == 0
&& db->bt_flag == DKBAD_MAGIC) {
msg = NULL;
*bdp = *db;
break;
} else
msg = "bad sector table corrupted";
}
} while (bp->b_error != 0 && (i += 2) < 10 &&
i < lp->d_nsectors);
}
done:
brelse(bp, 0);
return (msg);
}