Add MBR & i386/disklabel probing in a generic fashion usable for more

disklabel types, and for other architectures if they chose.  Both read/write
supported for both alpha and i386/arc disklabels.  ISO9660 spoofing kept
and tested.  Add "option DISKLABEL_ALL" to your config to use.

2 files changed, 491 insertions, 156 deletions

diff --git a/sys/arch/alpha/alpha/disksubr.c b/sys/arch/alpha/alpha/disksubr.c
index 823538c037a..051e2b3c013 100644
--- a/sys/arch/alpha/alpha/disksubr.c
+++ b/sys/arch/alpha/alpha/disksubr.c
@@ -1,143 +1,411 @@
-/*	$OpenBSD: disksubr.c,v 1.8 1997/04/07 06:21:39 millert Exp $	*/
-/*	$NetBSD: disksubr.c,v 1.9 1996/11/13 21:13:05 cgd Exp $	*/
+/*	$OpenBSD: disksubr.c,v 1.9 1997/06/30 11:50:59 niklas Exp $	*/
+/*	$NetBSD: disksubr.c,v 1.21 1996/05/03 19:42:03 christos Exp $	*/
 
 /*
- * Copyright (c) 1994, 1995, 1996 Carnegie-Mellon University.
+ * Copyright (c) 1996 Theo de Raadt
+ * Copyright (c) 1982, 1986, 1988 Regents of the University of California.
  * All rights reserved.
  *
- * Authors: Keith Bostic, Chris G. Demetriou
- * 
- * Permission to use, copy, modify and distribute this software and
- * its documentation is hereby granted, provided that both the copyright
- * notice and this permission notice appear in all copies of the
- * software, derivative works or modified versions, and any portions
- * thereof, and that both notices appear in supporting documentation.
- * 
- * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 
- * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 
- * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
- * 
- * Carnegie Mellon requests users of this software to return to
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by the University of
+ *	California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
  *
- *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
- *  School of Computer Science
- *  Carnegie Mellon University
- *  Pittsburgh PA 15213-3890
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
  *
- * any improvements or extensions that they make and grant Carnegie the
- * rights to redistribute these changes.
+ *	@(#)ufs_disksubr.c	7.16 (Berkeley) 5/4/91
  */
 
 #include <sys/param.h>
+#include <sys/systm.h>
 #include <sys/buf.h>
-#include <sys/ioccom.h>
 #include <sys/device.h>
 #include <sys/disklabel.h>
+#include <sys/syslog.h>
 #include <sys/disk.h>
 
-#include <scsi/scsi_all.h>
-#include <scsi/scsiconf.h>
+#define	b_cylin	b_resid
 
-#include <machine/cpu.h>
-#include <machine/autoconf.h>
+#define BOOT_MAGIC 0xAA55
+#define BOOT_MAGIC_OFF (DOSPARTOFF+NDOSPART*sizeof(struct dos_partition))
 
-extern struct device *bootdv;
+char   *readbsdlabel __P((struct buf *, void (*) __P((struct buf *)), int, int,
+    int, struct disklabel *));
+char   *readdoslabel __P((struct buf *, void (*) __P((struct buf *)),
+    struct disklabel *, struct cpu_disklabel *));
+
+static enum disklabel_tag probe_order[] = { LABELPROBES, -1 };
 
-/* was this the boot device ? */
 void
 dk_establish(dk, dev)
 	struct disk *dk;
 	struct device *dev;
 {
-#ifdef NOTDEF
-	/* XXX: sd -> scsibus -> esp */
-	struct bootpath *bp = ((struct esp_softc *)dev->dv_parent->dv_parent)->sc_bp;
-	char name[10];
+}
 
-#define CRAZYMAP(v) ((v) == 3 ? 0 : (v) == 0 ? 3 : (v))
+/*
+ * Try to read a standard BSD disklabel at a certain sector.
+ */
+char *
+readbsdlabel(bp, strat, cyl, sec, off, lp)
+	struct buf *bp;
+	void (*strat) __P((struct buf *));
+	int cyl, sec, off;
+	struct disklabel *lp;
+{
+	struct disklabel *dlp;
+	char *msg = NULL;
 
-	if (bp == NULL) {
-		printf("no boot path\n");
-	}
-	sprintf(name, "%s%d", bp->name, CRAZYMAP(bp->val[0]));
-	if (strcmp(name, dev->dv_xname) == 0) {
-		bootdv = dev;
+	bp->b_blkno = sec;
+	bp->b_cylin = cyl;
+	bp->b_bcount = lp->d_secsize;
+	bp->b_flags = B_BUSY | B_READ;
+	(*strat)(bp);
+
+	/* if successful, locate disk label within block and validate */
+	if (biowait(bp)) {
+		/* XXX we return the faked label built so far */
+		msg = "disk label I/O error";
+		return (msg);
 	}
-#endif
+
+	/*
+	 * If off is negative, search until the end of the sector for
+	 * the label, otherwise, just look at the specific location
+	 * we're given.
+	 */
+	dlp = (struct disklabel *)(bp->b_data + (off >= 0 ? off : 0));
+	do {
+		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 (off >= 0)
+			break;
+		dlp = (struct disklabel *)((char *)dlp + sizeof(int32_t));
+	} while (dlp <= (struct disklabel *)(bp->b_data + lp->d_secsize -
+	    sizeof(*dlp)));
+	return (msg);
 }
 
 /*
  * Attempt to read a disk label from a device
  * using the indicated stategy 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.
+ * secpercyl, secsize and anything required for a block i/o read
+ * operation in the driver's strategy/start routines
+ * must be filled in before calling us.
+ *
  * Returns null on success and an error string on failure.
  */
 char *
-readdisklabel(dev, strat, lp, clp)
+readdisklabel(dev, strat, lp, osdep)
 	dev_t dev;
 	void (*strat) __P((struct buf *));
 	struct disklabel *lp;
-	struct cpu_disklabel *clp;
+	struct cpu_disklabel *osdep;
 {
 	struct buf *bp;
-	struct disklabel *dlp;
-	char *msg = NULL;
+	char *msg = "no disk label";
+	enum disklabel_tag *tp;
+	int i;
+	struct disklabel savedlabel;
 
 	/* minimal requirements for archtypal disk label */
 	if (lp->d_secperunit == 0)
-		lp->d_secperunit = 0x1fffffff; 
-	lp->d_npartitions = 1;
-	if (lp->d_partitions[0].p_size == 0)
-		lp->d_partitions[0].p_size = 0x1fffffff;
-	lp->d_partitions[0].p_offset = 0;
+		lp->d_secsize = DEV_BSIZE;
+	if (lp->d_secperunit == 0)
+		lp->d_secperunit = 0x1fffffff;
+	lp->d_npartitions = RAW_PART + 1;
+	for (i = 0; i < RAW_PART; i++) {
+		lp->d_partitions[i].p_size = 0;
+		lp->d_partitions[i].p_offset = 0;
+	}
+	if (lp->d_partitions[i].p_size == 0)
+		lp->d_partitions[i].p_size = 0x1fffffff;
+	lp->d_partitions[i].p_offset = 0;
+	savedlabel = *lp;
 
-	/* obtain buffer to probe drive with */
+	/* get a buffer and initialize it */
 	bp = geteblk((int)lp->d_secsize);
-
-	/* next, dig out disk label */
 	bp->b_dev = dev;
-	bp->b_blkno = LABELSECTOR;
-	bp->b_resid = 0;			/* was b_cylin */
-	bp->b_bcount = lp->d_secsize;
-	bp->b_flags = B_BUSY | B_READ;
-	(*strat)(bp);  
 
-	/* if successful, locate disk label within block and validate */
-	if (biowait(bp)) {
-		msg = "disk label read error";
-		goto done;
-	}
+	for (tp = probe_order; msg && *tp != -1; tp++) {
+		switch (*tp) {
+		case DLT_ALPHA:
+#if defined(DISKLABEL_ALPHA) || defined(DISKLABEL_ALL) || defined(__alpha__)
+			msg = readbsdlabel(bp, strat, 0, ALPHA_LABELSECTOR,
+			    ALPHA_LABELOFFSET, lp);
+			if (msg == NULL)
+				lp->d_spare[4] = ALPHA_LABELSECTOR; /* XXX */
+#endif
+			break;
 
-	dlp = (struct disklabel *)(bp->b_un.b_addr + LABELOFFSET);
-	if (dlp->d_magic == DISKMAGIC) {
-		if (dkcksum(dlp)) {
-			msg = "OpenBSD disk label corrupted";
-			goto done;
+		case DLT_I386:
+#if defined(DISKLABEL_I386) || defined(DISKLABEL_ALL) || defined(__i386__) || defined(__arc__)
+			msg = readdoslabel(bp, strat, lp, osdep);
+			if (msg == NULL)
+				lp->d_spare[4] = bp->b_blkno;	/* XXX */
+#endif
+			break;
+
+		default:
+			panic("unrecognized disklabel tag %d", *tp);
 		}
-		*lp = *dlp;
-		goto done;
+		if (msg)
+			*lp = savedlabel;
 	}
+
 #if defined(CD9660)
-	if (iso_disklabelspoof(dev, strat, lp) == 0)
-		goto done;
+	if (msg && iso_disklabelspoof(dev, strat, lp) == 0)
+		msg = NULL;
 #endif
-	msg = "no disk label";
-done:
-	bp->b_flags = B_INVAL | B_AGE | B_READ;
+
+	bp->b_flags |= B_INVAL;
 	brelse(bp);
 	return (msg);
 }
 
 /*
- * Check new disk label for sensibility before setting it.
+ * If dos partition table requested, attempt to load it and
+ * find disklabel inside a DOS partition. Also, if bad block
+ * table needed, attempt to extract it as well. Return buffer
+ * for use in signalling errors if requested.
+ *
+ * We would like to check if each MBR has a valid BOOT_MAGIC, but
+ * we cannot because it doesn't always exist. So.. we assume the
+ * MBR is valid.
+ */
+char *
+readdoslabel(bp, strat, lp, osdep)
+	struct buf *bp;
+	void (*strat) __P((struct buf *));
+	struct disklabel *lp;
+	struct cpu_disklabel *osdep;
+{
+	struct dos_partition *dp = osdep->dosparts, *dp2;
+	struct dkbad *db, *bdp = &osdep->bad;
+	char *msg = NULL, *cp;
+	int dospartoff, cyl, i, ourpart = -1;
+	dev_t dev;
+
+	/* do dos partitions in the process of getting disklabel? */
+	dospartoff = 0;
+	cyl = I386_LABELSECTOR / lp->d_secpercyl;
+	if (dp) {
+	        daddr_t part_blkno = DOSBBSECTOR;
+		unsigned long extoff = 0;
+		int wander = 1, n = 0, loop = 0;
+
+		/*
+		 * Read dos partition table, follow extended partitions.
+		 * Map the partitions to disklabel entries i-p
+		 */
+		while (wander && n < 8 && loop < 8) {
+		        loop++;
+			wander = 0;
+
+			/* read boot record */
+			bp->b_blkno = part_blkno;
+			bp->b_bcount = lp->d_secsize;
+			bp->b_flags = B_BUSY | B_READ;
+			bp->b_cylin = part_blkno / lp->d_secpercyl;
+			(*strat)(bp);
+		     
+			/* if successful, wander through dos partition table */
+			if (biowait(bp)) {
+				msg = "dos partition I/O error";
+				return (msg);
+			}
+			bcopy(bp->b_data + DOSPARTOFF, dp,
+			    NDOSPART * sizeof(*dp));
+
+			if (ourpart == -1) {
+				/* Search for our MBR partition */
+				for (dp2=dp, i=0;
+				    i < NDOSPART && ourpart == -1; i++, dp2++)
+					if (dp2->dp_size &&
+					    dp2->dp_typ == DOSPTYP_OPENBSD)
+						ourpart = i;
+				for (dp2=dp, i=0;
+				    i < NDOSPART && ourpart == -1; i++, dp2++)
+					if (dp2->dp_size &&
+					    dp2->dp_typ == DOSPTYP_386BSD)
+						ourpart = i;
+				if (ourpart == -1)
+					goto donot;
+				/*
+				 * This is our MBR partition. need sector
+				 * address for SCSI/IDE, cylinder for
+				 * ESDI/ST506/RLL
+				 */
+				dp2 = &dp[ourpart];
+				dospartoff = dp2->dp_start + part_blkno;
+				cyl = DPCYL(dp2->dp_scyl, dp2->dp_ssect);
+
+				/* XXX build a temporary disklabel */
+				lp->d_partitions[0].p_size = dp2->dp_size;
+				lp->d_partitions[0].p_offset = dp2->dp_start +
+				    part_blkno;
+				if (lp->d_ntracks == 0)
+					lp->d_ntracks = dp2->dp_ehd + 1;
+				if (lp->d_nsectors == 0)
+					lp->d_nsectors = DPSECT(dp2->dp_esect);
+				if (lp->d_secpercyl == 0)
+					lp->d_secpercyl = lp->d_ntracks *
+					    lp->d_nsectors;
+			}
+donot:
+			/*
+			 * In case the disklabel read below fails, we want to
+			 * provide a fake label in i-p.
+			 */
+			for (dp2=dp, i=0; i < NDOSPART && n < 8; i++, dp2++) {
+				struct partition *pp = &lp->d_partitions[8+n];
+
+				if (dp2->dp_size)
+					pp->p_size = dp2->dp_size;
+				if (dp2->dp_start)
+					pp->p_offset =
+					    dp2->dp_start + part_blkno;
+
+				switch (dp2->dp_typ) {
+				case DOSPTYP_UNUSED:
+					for (cp = (char *)dp2;
+					    cp < (char *)(dp2 + 1); cp++)
+						if (*cp)
+							break;
+					/*
+					 * Was it all zeroes?  If so, it is
+					 * an unused entry that we don't
+					 * want to show.
+					 */
+					if (cp == (char *)(dp2 + 1))
+					    continue;
+					lp->d_partitions[8 + n++].p_fstype =
+					    FS_UNUSED;
+					break;
+
+				case DOSPTYP_LINUX:
+					pp->p_fstype = FS_EXT2FS;
+					n++;
+					break;
+
+				case DOSPTYP_FAT12:
+				case DOSPTYP_FAT16S:
+				case DOSPTYP_FAT16B:
+				case DOSPTYP_FAT16C:
+					pp->p_fstype = FS_MSDOS;
+					n++;
+					break;
+				case DOSPTYP_EXTEND:
+					part_blkno = dp2->dp_start + extoff;
+					if (!extoff)
+						extoff = dp2->dp_start;
+					wander = 1;
+					break;
+				default:
+					pp->p_fstype = FS_OTHER;
+					n++;
+					break;
+				}
+			}
+		}
+		lp->d_bbsize = 8192;
+		lp->d_sbsize = 64*1024;		/* XXX ? */
+		lp->d_npartitions = MAXPARTITIONS;
+	}
+
+	/* next, dig out disk label */
+	msg = readbsdlabel(bp, strat, cyl, dospartoff + I386_LABELSECTOR, -1,
+	    lp);
+	if (msg)
+		return (msg);
+
+	/* obtain bad sector table if requested and present */
+	if (bdp && (lp->d_flags & D_BADSECT)) {
+		/*
+		 * get a new buffer and initialize it as callers trust the
+		 * buffer given to us, to point at the disklabel sector.
+		 */
+		dev = bp->b_dev;
+		bp = geteblk((int)lp->d_secsize);
+		bp->b_dev = dev;
+
+		i = 0;
+		do {
+			/* read a bad sector table */
+			bp->b_flags = B_BUSY | 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_cylin = 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_flags & B_ERROR) && (i += 2) < 10 &&
+		    i < lp->d_nsectors);
+
+		/* Give back the bad block buffer.  */
+		bp->b_flags |= B_INVAL;
+		brelse(bp);
+	}
+	return (msg);
+}
+
+/*
+ * Check new disk label for sensibility
+ * before setting it.
  */
 int
-setdisklabel(olp, nlp, openmask, clp)
-	register struct disklabel *olp, *nlp;
+setdisklabel(olp, nlp, openmask, osdep)
+	struct disklabel *olp, *nlp;
 	u_long openmask;
-	struct cpu_disklabel *clp;
+	struct cpu_disklabel *osdep;
 {
 	register i;
 	register struct partition *opp, *npp;
@@ -147,31 +415,32 @@ setdisklabel(olp, nlp, openmask, clp)
 	    (nlp->d_secsize % DEV_BSIZE) != 0)
 		return(EINVAL);
 
-#ifdef notdef
-	/* XXX WHY WAS THIS HERE?! */
+	/* XXX is this needed at all?  NetBSD/alpha doesn't have it.  */
 	/* special case to allow disklabel to be invalidated */
-	if (nlp->d_magic == 0xffffffff) { 
+	if (nlp->d_magic == 0xffffffff) {
 		*olp = *nlp;
 		return (0);
 	}
-#endif
 
 	if (nlp->d_magic != DISKMAGIC || nlp->d_magic2 != DISKMAGIC ||
-		dkcksum(nlp) != 0)
+	    dkcksum(nlp) != 0)
 		return (EINVAL);
 
-	while ((i = ffs((long)openmask)) != 0) {
-		i--;
+	/* XXX missing check if other dos partitions will be overwritten */
+
+	while (openmask != 0) {
+		i = ffs((long)openmask) - 1;
 		openmask &= ~(1 << i);
 		if (nlp->d_npartitions <= i)
 			return (EBUSY);
 		opp = &olp->d_partitions[i];
 		npp = &nlp->d_partitions[i];
-		if (npp->p_offset != opp->p_offset || npp->p_size < opp->p_size)
+		if (npp->p_offset != opp->p_offset ||
+		    npp->p_size < opp->p_size)
 			return (EBUSY);
 		/*
 		 * Copy internally-set partition information
-		 * if new label doesn't include it.             XXX
+		 * if new label doesn't include it.		XXX
 		 */
 		if (npp->p_fstype == FS_UNUSED && opp->p_fstype != FS_UNUSED) {
 			npp->p_fstype = opp->p_fstype;
@@ -183,70 +452,83 @@ setdisklabel(olp, nlp, openmask, clp)
 	nlp->d_checksum = 0;
 	nlp->d_checksum = dkcksum(nlp);
 	*olp = *nlp;
-	return (0);     
+	return (0);
 }
 
+
 /*
  * Write disk label back to device after modification.
- * this means write out the Rigid disk blocks to represent the 
- * label.  Hope the user was carefull.
+ * XXX cannot handle OpenBSD partitions in extended partitions!
  */
 int
-writedisklabel(dev, strat, lp, clp)
+writedisklabel(dev, strat, lp, osdep)
 	dev_t dev;
 	void (*strat) __P((struct buf *));
-	register struct disklabel *lp;
-	struct cpu_disklabel *clp;
+	struct disklabel *lp;
+	struct cpu_disklabel *osdep;
 {
-	struct buf *bp; 
-	struct disklabel *dlp;
-	int labelpart;
-	int error = 0;
+	enum disklabel_tag *tp;
+	char *msg = "no disk label";
+	struct buf *bp;
+	struct disklabel dl;
+#if defined(DISKLABEL_I386) || defined(DISKLABEL_ALL) || defined(__i386__) || defined(__arc__)
+	struct cpu_disklabel cdl;
+#endif
+	int labeloffset, error, i;
+	u_int64_t csum, *p;
 
-	labelpart = DISKPART(dev);
-	if (lp->d_partitions[labelpart].p_offset != 0) {
-		if (lp->d_partitions[0].p_offset != 0)
-			return (EXDEV);		/* not quite right */
-	}
+	/* get a buffer and initialize it */
 	bp = geteblk((int)lp->d_secsize);
-	bp->b_dev = MAKEDISKDEV(major(dev), DISKUNIT(dev), labelpart);
-	bp->b_blkno = LABELSECTOR;
-	bp->b_resid = 0;			/* was b_cylin */
-	bp->b_bcount = lp->d_secsize;
-	bp->b_flags = B_READ;           /* get current label */
-	(*strat)(bp);
-	if ((error = biowait(bp)) != 0)
+	bp->b_dev = dev;
+
+	for (tp = probe_order; msg && *tp != -1; tp++) {
+		dl = *lp;
+		switch (*tp) {
+		case DLT_ALPHA:
+#if defined(DISKLABEL_ALPHA) || defined(DISKLABEL_ALL) || defined(__alpha__)
+			msg = readbsdlabel(bp, strat, 0, ALPHA_LABELSECTOR,
+			    ALPHA_LABELOFFSET, &dl);
+			labeloffset = ALPHA_LABELOFFSET;
+#endif
+			break;
+
+		case DLT_I386:
+#if defined(DISKLABEL_I386) || defined(DISKLABEL_ALL) || defined(__i386__) || defined(__arc__)
+			msg = readdoslabel(bp, strat, &dl, &cdl);
+			labeloffset = I386_LABELOFFSET;
+#endif
+			break;
+
+		default:
+			panic("unrecognized disklabel tag %d", *tp);
+		}
+	}
+
+	if (msg) {
+		error = ESRCH;
 		goto done;
+	}
 
-	dlp = (struct disklabel *)(bp->b_un.b_addr + LABELOFFSET);
-	*dlp = *lp;     /* struct assignment */
+	*(struct disklabel *)(bp->b_data + labeloffset) = *lp;
 
-	/*
-	 * The Alpha requires that the boot block be checksummed.
-	 * The first 63 8-bit quantites are summed into the 64th.
-	 */
-	{
-		int i;
-		u_long *dp, sum;
-
-		dp = (u_long *)bp->b_un.b_addr;
-		sum = 0;
-		for (i = 0; i < 63; i++)
-			sum += dp[i];
-		dp[63] = sum;
+	/* Alpha bootblocks are checksummed.  */
+	if (*tp == DLT_ALPHA) {
+		for (csum = i = 0, p = (u_int64_t *)bp->b_data; i < 63; i++)
+			csum += *p++;
+		*p = csum;
 	}
 
-	bp->b_flags = B_WRITE;
+	bp->b_flags = B_BUSY | B_WRITE;
 	(*strat)(bp);
 	error = biowait(bp);
 
 done:
+	bp->b_flags |= B_INVAL;
 	brelse(bp);
-	return (error); 
+	return (error);
 }
 
-
-/* 
+/*
  * Determine the size of the transfer, and make sure it is
  * within the boundaries of the partition. Adjust transfer
  * if needed, and signal errors or early completion.
@@ -259,39 +541,41 @@ bounds_check_with_label(bp, lp, wlabel)
 {
 #define blockpersec(count, lp) ((count) * (((lp)->d_secsize) / DEV_BSIZE))
 	struct partition *p = lp->d_partitions + DISKPART(bp->b_dev);
-	int labelsect = blockpersec(lp->d_partitions[0].p_offset, lp) +
-	    LABELSECTOR;
+	int labelsector = blockpersec(lp->d_partitions[RAW_PART].p_offset, lp) +
+	    lp->d_spare[4];	/* XXX */
 	int sz = howmany(bp->b_bcount, DEV_BSIZE);
 
-	/* overwriting disk label ? */
-	/* XXX should also protect bootstrap in first 8K */ 
-	if (bp->b_blkno + blockpersec(p->p_offset, lp) <= labelsect &&
-	    (bp->b_flags & B_READ) == 0 && wlabel == 0) {
-		bp->b_error = EROFS;
-		goto bad;
-	}
-
-	/* beyond partition? */ 
 	if (bp->b_blkno + sz > blockpersec(p->p_size, lp)) {
 		sz = blockpersec(p->p_size, lp) - bp->b_blkno;
 		if (sz == 0) {
-			/* If exactly at end of disk, return an EOF */
+			/* If exactly at end of disk, return EOF. */
 			bp->b_resid = bp->b_bcount;
-			return(0);
+			goto done;
 		}
 		if (sz < 0) {
+			/* If past end of disk, return EINVAL. */
 			bp->b_error = EINVAL;
 			goto bad;
 		}
-		/* or truncate if part of it fits */
+		/* Otherwise, truncate request. */
 		bp->b_bcount = sz << DEV_BSHIFT;
-	}               
+	}
+
+	/* Overwriting disk label? */
+	if (bp->b_blkno + blockpersec(p->p_offset, lp) <= labelsector &&
+	    bp->b_blkno + blockpersec(p->p_offset, lp) + sz > labelsector &&
+	    (bp->b_flags & B_READ) == 0 && !wlabel) {
+		bp->b_error = EROFS;
+		goto bad;
+	}
 
 	/* calculate cylinder for disksort to order transfers with */
-	bp->b_resid = (bp->b_blkno + blockpersec(p->p_offset, lp)) /
+	bp->b_cylin = (bp->b_blkno + blockpersec(p->p_offset, lp)) /
 	    lp->d_secpercyl;
-	return(1);
+	return (1);
+
 bad:
 	bp->b_flags |= B_ERROR;
-	return(-1);
+done:
+	return (0);
 }
diff --git a/sys/arch/alpha/include/disklabel.h b/sys/arch/alpha/include/disklabel.h
index c15f1e71dee..c34a28db2a1 100644
--- a/sys/arch/alpha/include/disklabel.h
+++ b/sys/arch/alpha/include/disklabel.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: disklabel.h,v 1.4 1997/04/07 06:21:37 millert Exp $	*/
+/*	$OpenBSD: disklabel.h,v 1.5 1997/06/30 11:50:58 niklas Exp $	*/
 /*	$NetBSD: disklabel.h,v 1.1 1995/02/13 23:07:34 cgd Exp $	*/
 
 /*
@@ -34,16 +34,67 @@
 #ifndef _MACHINE_DISKLABEL_H_
 #define _MACHINE_DISKLABEL_H_
 
-#define	LABELSECTOR	0			/* sector containing label */
-#define	LABELOFFSET	64			/* offset of label in sector */
-#define	MAXPARTITIONS	16			/* number of partitions */
-#define	RAW_PART	2			/* raw partition: xx?c */
+enum disklabel_tag { DLT_ALPHA, DLT_I386 };
 
-/* Just a dummy */
+/*
+ * What disklabels are we probing for, and in which order?
+ */
+#ifndef LABELPROBES
+#define LABELPROBES		DLT_ALPHA, DLT_I386
+#endif
+
+#define	ALPHA_LABELSECTOR	0		/* sector containing label */
+#define	ALPHA_LABELOFFSET	64		/* offset of label in sector */
+#define	I386_LABELSECTOR	1		/* sector containing label */
+#define	I386_LABELOFFSET	0		/* offset of label in sector */
+
+#define LABELSECTOR		ALPHA_LABELSECTOR
+#define LABELOFFSET		ALPHA_LABELOFFSET
+
+#define	MAXPARTITIONS		16		/* number of partitions */
+#define	RAW_PART		2		/* raw partition: xx?c */
+
+/* DOS partition table -- located in boot block */
+#define	DOSBBSECTOR	0		/* DOS boot block relative sector # */
+#define	DOSPARTOFF	446
+#define	NDOSPART	4
+
+struct dos_partition {
+	u_int8_t	dp_flag;	/* bootstrap flags */
+	u_int8_t	dp_shd;		/* starting head */
+	u_int8_t	dp_ssect;	/* starting sector */
+	u_int8_t	dp_scyl;	/* starting cylinder */
+	u_int8_t	dp_typ;		/* partition type (see below) */
+	u_int8_t	dp_ehd;		/* end head */
+	u_int8_t	dp_esect;	/* end sector */
+	u_int8_t	dp_ecyl;	/* end cylinder */
+	u_int32_t	dp_start;	/* absolute starting sector number */
+	u_int32_t	dp_size;	/* partition size in sectors */
+};
+
+/* Known DOS partition types. */
+#define	DOSPTYP_UNUSED	0x00		/* Unused partition */
+#define DOSPTYP_FAT12	0x01		/* 12-bit FAT */
+#define DOSPTYP_FAT16S	0x04		/* 16-bit FAT, less than 32M */
+#define DOSPTYP_EXTEND	0x05		/* Extended; contains sub-partitions */
+#define DOSPTYP_FAT16B	0x06		/* 16-bit FAT, more than 32M */
+#define DOSPTYP_FAT16C	0x0e		/* 16-bit FAT, CHS-mapped */
+#define DOSPTYP_ONTRACK	0x54
+#define	DOSPTYP_LINUX	0x83		/* That other thing */
+#define DOSPTYP_386BSD	0xa5		/* 386BSD partition type */
+#define DOSPTYP_NETBSD	DOSPTYP_386BSD	/* NetBSD partition type (XXX) */
+#define DOSPTYP_OPENBSD	0xa6		/* OpenBSD partition type */
+
+#include <sys/dkbad.h>
 struct cpu_disklabel {
-	int	cd_dummy;			/* must have one element. */
+	struct dos_partition dosparts[NDOSPART];
+	struct dkbad bad;
 };
 
+/* Isolate the relevant bits to get sector and cylinder. */
+#define	DPSECT(s)	((s) & 0x3f)
+#define	DPCYL(c, s)	((c) + (((s) & 0xc0) << 2))
+
 #ifdef _KERNEL
 struct disklabel;
 int	bounds_check_with_label __P((struct buf *, struct disklabel *, int));