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/*
*
* THIS SOFTWARE IS PROVIDED BY THE WRITERS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE WRITERS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* written by julian elischer (julian@tfs.com)
*
* @(#)readMBR.c 8.5 (tfs) 1/21/94
* $Id: readMBR.c,v 1.4 1994/11/14 13:22:41 bde Exp $
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/buf.h>
#include <sys/disklabel.h>
#define b_cylinder b_resid
/*
* Attempt to read a machine-type dependent Device partitioning table
* In this case a PC BIOS MBR.
* Destroys the original disklabel if it finds an MBR, so you'd better
* know what you're doing. It assumes that the label you've given it
* Is the one that controls the device, so that it can fiddle with it
* to make sure it's reading absolute sectors.
* On exit:
* Leaves the disklabel set up with the various partitions
* in the last 4 entries,
* the A partition pointing to the BSD part
* the C partition set as the BSD partition, (read the disklabel from there) and
* the D partition set as the whole disk for beating up
* will also give you a copy of the machine dependent table if you ask..
* returns 0 for success,
* On failure, restores the disklabel and returns a messages pointer.
*/
char *
readMBRtolabel(dev, strat, lp, dp, cyl)
dev_t dev;
void (*strat)();
register struct disklabel *lp;
struct dos_partition *dp;
int *cyl;
{
register struct buf *bp;
struct disklabel *dlp;
struct disklabel labelsave;
char *msg = NULL;
int i;
int pseudopart = 4; /* we fill in pseudoparts from e through h*/
int seenBSD = 0;
/*
* Save a copy of the disklabel in case we return with an error
*/
bcopy(lp,&labelsave,sizeof(labelsave));
/*
* Set the disklabel to some useable partitions in case it's rubbish
*/
if (lp->d_secperunit == 0)
lp->d_secperunit = 0x1fffffff;
lp->d_npartitions = 4;
for (i=0; i<MAXPARTITIONS; i++) {
lp->d_partitions[i].p_offset = 0;
lp->d_partitions[i].p_size = 0;
}
lp->d_partitions[RAWPART].p_size = DOSBBSECTOR + 1; /* start low */
strcpy(lp->d_packname,"MBR based label"); /* Watch the length ! */
/*
* Get a buffer and get ready to read the MBR
*/
bp = geteblk((int)lp->d_secsize);
/* read master boot record */
bp->b_dev = makedev(major(dev), dkminor(dkunit(dev), RAWPART));
bp->b_blkno = DOSBBSECTOR;
bp->b_bcount = lp->d_secsize;
bp->b_flags = B_BUSY | B_READ;
bp->b_cylinder = DOSBBSECTOR / lp->d_secpercyl;
(*strat)(bp);
/* if successful, wander through dos partition table */
if ( biowait(bp)) {
msg = "dos partition I/O error";
goto bad;
} else {
/*
* If there seems to be BIOS bootblock and partition table
* in that block, then try interpret it, otherwise
* give up and use whatever we have synthesised so far
*/
if ((*(bp->b_un.b_addr + 510) != (char) 0x55)
||(*(bp->b_un.b_addr + 511) != (char) 0xaa)) {
printf("disk doesn't have an MBR\n");
if(dp)
bzero(bp->b_un.b_addr + DOSPARTOFF,
NDOSPART * sizeof(*dp));
goto hrumpf;
}
if(dp) { /* if they asked for a copy, give it to them */
bcopy(bp->b_un.b_addr + DOSPARTOFF, dp,
NDOSPART * sizeof(*dp));
}
dp = (struct dos_partition *)(bp->b_un.b_addr + DOSPARTOFF);
/*
* We have a DOS MBR..
* We set up the last 4 partitions in the
* disklabel to reflect the DOS partitions
* In case we never find a disklabel, in which
* case this information will be all we have
* but it might be all we need to access a DOS
* partition.
*/
for (i = 0; i < NDOSPART; i++, dp++,pseudopart++) {
if (!dp->dp_size)
continue;
/*
* Set this DOS part into the disklabel
*/
lp->d_partitions[pseudopart].p_size =
dp->dp_size;
lp->d_partitions[pseudopart].p_offset =
dp->dp_start;
/*
* make sure the D part can hold it all
*/
if((dp->dp_start + dp->dp_size)
> lp->d_partitions[3].p_size) {
lp->d_partitions[3].p_size
= (dp->dp_start + dp->dp_size);
}
/*
* If we haven't seen a *BSD partition then
* check if this is a valid part..
* if it is it may be the best we are going to
* to see, so take note of it to deduce a
* geometry in case we never find a disklabel.
*/
switch(dp->dp_typ) {
case DOSPTYP_386BSD:
/*
* at a pinch we could throw
* a FFS on here
*/
lp->d_partitions[pseudopart].p_fstype
= FS_BSDFFS;
/*
* Only get a disklabel from the
* first one we see..
*/
if (seenBSD == 0) {
/*
* If it IS our part, then we
* need sector address for
* SCSI/IDE, cylinder for
* ESDI/ST506/RLL
*/
seenBSD = 1;
*cyl = DPCYL(dp->dp_scyl,
dp->dp_ssect);
/*
* Note which part we are in (?)
*/
lp->d_subtype &= ~3;
lp->d_subtype |= i & 3;
lp->d_subtype
|= DSTYPE_INDOSPART;
/*
* update disklabel with
* details for reading the REAL
* disklabel it it exists
*/
lp->d_partitions[OURPART].p_size =
dp->dp_size;
lp->d_partitions[OURPART].p_offset =
dp->dp_start;
}
break;
case 0xB7: /* BSDI (?)*//* doubtful */
lp->d_partitions[pseudopart].p_fstype
= FS_BSDFFS;
break;
case 1:
case 4:
case 6:
case 0xF2:
lp->d_partitions[pseudopart].p_fstype
= FS_MSDOS;
break;
}
/*
* Try deduce the geometry, working
* on the principle that this
* partition PROBABLY ends on a
* cylinder boundary.
* This is really a kludge, but we are
* forced into it by the PC's design.
* If we've seen a 386bsd part,
* believe it and check no further.
*/
if (seenBSD) continue;
lp->d_ntracks = dp->dp_ehd + 1;
lp->d_nsectors = DPSECT(dp->dp_esect);
lp->d_secpercyl = lp->d_ntracks *
lp->d_nsectors;
}
lp->d_npartitions = 8;
}
hrumpf:
bp->b_flags = B_INVAL | B_AGE;
brelse(bp);
return 0;
bad:
bcopy(&labelsave,lp,sizeof(labelsave));
bp->b_flags = B_INVAL | B_AGE;
brelse(bp);
return msg;
}
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