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