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From: julian@tfs.com (Julian Elischer)
Subject: Mounting unlabelled (DOS) hard disks
Message-ID: <CuyHsn.C1x@tfs.com>
Organization: TRW Financial Systems
Date: Mon, 22 Aug 1994 21:45:59 GMT
Lines: 256
Yesterday I posted a patch (which Icouldn't fully test,
and last night I suddenly woke up realising that there was
a logical flaw in it, and that the patch needed to be
extended.
here is the new patch:
if you have an unlabelled DOS hard-disk,
please try this out..
the four BIOS partitions should appear as partitions
e,f,g and h.
julian
-------------cut here-------
*** ufs_disksubr.c.orig Sun Aug 21 22:51:21 1994
--- ufs_disksubr.c Mon Aug 22 14:04:07 1994
***************
*** 177,182 ****
--- 177,184 ----
struct disklabel *dlp;
char *msg = NULL;
int cyl, dospartoff, i;
+ int pseudopart = 4; /* we fill in pseudoparts from e through h*/
+ int seenBSD = 0;
/* minimal requirements for archtypal disk label */
if (lp->d_secperunit == 0)
***************
*** 185,190 ****
--- 187,198 ----
if (lp->d_partitions[0].p_size == 0)
lp->d_partitions[0].p_size = 0x1fffffff;
lp->d_partitions[0].p_offset = 0;
+ lp->d_partitions[1].p_size = 0;
+ lp->d_partitions[1].p_offset = 0;
+ lp->d_partitions[2].p_size = 0;
+ lp->d_partitions[2].p_offset = 0;
+ lp->d_partitions[3].p_size = 0;
+ lp->d_partitions[3].p_offset = 0;
/* obtain buffer to probe drive with */
bp = geteblk((int)lp->d_secsize);
***************
*** 205,246 ****
bp->b_cylin = DOSBBSECTOR / lp->d_secpercyl;
(*strat)(bp);
! /* if successful, wander through dos partition table */
if (biowait(bp)) {
msg = "dos partition I/O error";
goto done;
! } else {
! /* XXX how do we check veracity/bounds of this? */
! bcopy(bp->b_un.b_addr + DOSPARTOFF, dp,
! NDOSPART * sizeof(*dp));
! for (i = 0; i < NDOSPART; i++, dp++)
! /* is this ours? */
! if (dp->dp_size &&
! dp->dp_typ == DOSPTYP_386BSD
! && dospartoff == 0) {
! /* need sector address for SCSI/IDE,
! cylinder for ESDI/ST506/RLL */
dospartoff = dp->dp_start;
! cyl = DPCYL(dp->dp_scyl, dp->dp_ssect);
!
! /* update disklabel with details */
lp->d_partitions[0].p_size =
dp->dp_size;
lp->d_partitions[0].p_offset =
dp->dp_start;
- lp->d_ntracks = dp->dp_ehd + 1;
- lp->d_nsectors = DPSECT(dp->dp_esect);
- lp->d_subtype |= (lp->d_subtype & 3)
- + i | DSTYPE_INDOSPART;
- lp->d_secpercyl = lp->d_ntracks *
- lp->d_nsectors;
}
}
!
}
! /* next, dig out disk label */
bp->b_blkno = dospartoff + LABELSECTOR;
bp->b_cylin = cyl;
bp->b_bcount = lp->d_secsize;
--- 213,313 ----
bp->b_cylin = DOSBBSECTOR / lp->d_secpercyl;
(*strat)(bp);
! /*
! * if we failed in the read, give up.
! */
if (biowait(bp)) {
msg = "dos partition I/O error";
goto done;
! }
! /*
! * 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] |= 0x55)
! ||(bp->b_un.b_addr[511] |= 0xaa)) {
! msg = "Disk has no Fdisk partitions";
! goto done;
! }
! /* XXX how do we check veracity/bounds of this? */
! bcopy(bp->b_un.b_addr + DOSPARTOFF, dp,
! NDOSPART * sizeof(*dp));
! /*
! * 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++) {
!
! /*
! * 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;
! /*
! * 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.
! */
! if (dp->dp_size && (seenBSD == 0)) {
! if( dp->dp_typ == DOSPTYP_386BSD) {
! /*
! * If it IS our part, then we
! * need sector address for
! * SCSI/IDE, cylinder for
! * ESDI/ST506/RLL
! */
dospartoff = dp->dp_start;
! seenBSD = 1;
! cyl = DPCYL(dp->dp_scyl,
! dp->dp_ssect);
!
! /*
! * update disklabel with
! * details for reading the REAL
! * disklabel it it exists
! */
lp->d_partitions[0].p_size =
dp->dp_size;
lp->d_partitions[0].p_offset =
dp->dp_start;
}
+ /*
+ * 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.
+ */
+ lp->d_ntracks = dp->dp_ehd + 1;
+ lp->d_nsectors = DPSECT(dp->dp_esect);
+ lp->d_subtype |= (lp->d_subtype & 3)
+ + i | DSTYPE_INDOSPART;
+ lp->d_secpercyl = lp->d_ntracks *
+ lp->d_nsectors;
+ }
}
! lp->d_npartitions = 8;
}
! /*
! * If we haven't seen a BSD partition, give up, use the dos version
! */
! if(!seenBSD) goto done;
!
! /*
! * next, dig out disk label
! */
bp->b_blkno = dospartoff + LABELSECTOR;
bp->b_cylin = cyl;
bp->b_bcount = lp->d_secsize;
***************
*** 249,274 ****
/* if successful, locate disk label within block and validate */
if (biowait(bp)) {
! msg = "disk label I/O error";
goto done;
! } else for (dlp = (struct disklabel *)bp->b_un.b_addr;
dlp <= (struct disklabel *)(bp->b_un.b_addr+DEV_BSIZE-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;
/* obtain bad sector table if requested and present */
if (bdp && (lp->d_flags & D_BADSECT)) {
--- 316,345 ----
/* if successful, locate disk label within block and validate */
if (biowait(bp)) {
! printf("disk label I/O error\n");
goto done;
! /* leave us at least with the dos partitions */
! }
! for (dlp = (struct disklabel *)bp->b_un.b_addr;
dlp <= (struct disklabel *)(bp->b_un.b_addr+DEV_BSIZE-sizeof(*dlp));
dlp = (struct disklabel *)((char *)dlp + sizeof(long))) {
if (dlp->d_magic != DISKMAGIC || dlp->d_magic2 != DISKMAGIC) {
! continue;
}
+ if (dlp->d_npartitions > MAXPARTITIONS ||
+ dkcksum(dlp) != 0) {
+ printf("disk label corrupted\n");
+ goto done;
+ /* leave us at least with the dos partitions */
+ }
+ *lp = *dlp;
+ msg = NULL;
+ break;
}
! if (dlp->d_magic != DISKMAGIC || dlp->d_magic2 != DISKMAGIC) {
! printf("No disklabel found\n");
goto done;
+ }
/* obtain bad sector table if requested and present */
if (bdp && (lp->d_flags & D_BADSECT)) {
-------------end of patch--------
+----------------------------------+ ______ _ __
| __--_|\ Julian Elischer | \ U \/ / On assignment
| / \ julian@tfs.com +------>x USA \ in a very strange
| ( OZ ) 300 lakeside Dr. oakland CA. \___ ___ | country !
+- X_.---._/ USA+(510) 645-3137(wk) \_/ \\
v