allow to install and boot the OpenBSD A6 partition and disklabel in an

extended DOS partition.  the concept of extended partitions is very
simple, it is just another mbr at the partition offset (well, the
standard "EBR" is a linked list with a few limitations, but this diff
works with both variants).

this diff has been in the snapshots for a while.

with input from weingart@ and krw@
ok deraadt@

5 files changed, 287 insertions, 99 deletions

diff --git a/sys/arch/amd64/stand/installboot/installboot.c b/sys/arch/amd64/stand/installboot/installboot.c
index 85bc9bf0399..88f134a0094 100644
--- a/sys/arch/amd64/stand/installboot/installboot.c
+++ b/sys/arch/amd64/stand/installboot/installboot.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: installboot.c,v 1.8 2008/01/24 12:09:53 krw Exp $	*/
+/*	$OpenBSD: installboot.c,v 1.9 2008/06/25 15:26:44 reyk Exp $	*/
 /*	$NetBSD: installboot.c,v 1.5 1995/11/17 23:23:50 gwr Exp $ */
 
 /*
@@ -98,6 +98,7 @@ static void	devread(int, void *, daddr_t, size_t, char *);
 static void	sym_set_value(struct sym_data *, char *, u_int32_t);
 static void	pbr_set_symbols(char *, char *, struct sym_data *);
 static void	usage(void);
+static long	findopenbsd(int, struct disklabel *, off_t, int *);
 
 static void
 usage(void)
@@ -120,9 +121,9 @@ main(int argc, char *argv[])
 	long	protosize;
 	struct	stat sb;
 	struct	disklabel dl;
-	struct	dos_mbr mbr;
-	struct	dos_partition *dp;
 	off_t	startoff = 0;
+	long	start = 0;
+	int	n = 8;
 
 	while ((c = getopt(argc, argv, "vn")) != -1) {
 		switch (c) {
@@ -200,29 +201,11 @@ main(int argc, char *argv[])
 
 	if (dl.d_type != 0 && dl.d_type != DTYPE_FLOPPY &&
 	    dl.d_type != DTYPE_VND) {
-		if (lseek(devfd, (off_t)DOSBBSECTOR, SEEK_SET) < 0 ||
-		    read(devfd, &mbr, sizeof(mbr)) != sizeof(mbr))
-			err(4, "can't read master boot record");
-
-		if (mbr.dmbr_sign != DOSMBR_SIGNATURE)
-			errx(1, "broken MBR");
-
 		/* Find OpenBSD partition. */
-		for (dp = mbr.dmbr_parts; dp < &mbr.dmbr_parts[NDOSPART];
-		    dp++) {
-			if (dp->dp_size && dp->dp_typ == DOSPTYP_OPENBSD) {
-				startoff = (off_t)dp->dp_start * dl.d_secsize;
-				fprintf(stderr, "using MBR partition %ld: "
-				    "type %d (0x%02x) offset %d (0x%x)\n",
-				    (long)(dp - mbr.dmbr_parts),
-				    dp->dp_typ, dp->dp_typ,
-				    dp->dp_start, dp->dp_start);
-				break;
-			}
-		}
-		/* Don't check for old part number, that is ;-p */
-		if (dp >= &mbr.dmbr_parts[NDOSPART])
-			errx(1, "no OpenBSD partition");
+		start = findopenbsd(devfd, &dl, (off_t)DOSBBSECTOR, &n);
+		if (start == -1)
+ 			errx(1, "no OpenBSD partition");
+		startoff = (off_t)start * dl.d_secsize;
 	}
 
 	if (!nowrite) {
@@ -236,6 +219,56 @@ main(int argc, char *argv[])
 	return 0;
 }
 
+long
+findopenbsd(int devfd, struct disklabel *dl, off_t mbroff, int *n)
+{
+	struct		dos_mbr mbr;
+	struct		dos_partition *dp;
+	off_t		startoff;
+	long		start;
+
+	/* Limit the number of recursions */
+	if (!(*n)--)
+		return (-1);
+
+	if (lseek(devfd, mbroff, SEEK_SET) < 0 ||
+	    read(devfd, &mbr, sizeof(mbr)) != sizeof(mbr))
+		err(4, "can't read master boot record");
+
+	if (mbr.dmbr_sign != DOSMBR_SIGNATURE)
+		errx(1, "broken MBR");
+
+	for (dp = mbr.dmbr_parts; dp < &mbr.dmbr_parts[NDOSPART];
+	    dp++) {
+		if (!dp->dp_size)
+			continue;
+		startoff = (off_t)dp->dp_start * dl->d_secsize;
+		if (dp->dp_typ == DOSPTYP_OPENBSD) {
+			fprintf(stderr, "using MBR partition %ld: "
+			    "type %d (0x%02x) offset %d (0x%x)\n",
+			    (long)(dp - mbr.dmbr_parts),
+			    dp->dp_typ, dp->dp_typ,
+			    dp->dp_start, dp->dp_start);
+			break;
+		} else if (dp->dp_typ == DOSPTYP_EXTEND ||
+		    dp->dp_typ == DOSPTYP_EXTENDL) {
+			fprintf(stderr, "extended partition %ld: "
+			    "type %d (0x%02x) offset %d (0x%x)\n",
+			    (long)(dp - mbr.dmbr_parts),
+			    dp->dp_typ, dp->dp_typ,
+			    dp->dp_start, dp->dp_start);
+			start = findopenbsd(devfd, dl, startoff, n);
+			if (start != -1)
+				return (dp->dp_start + start);
+		}
+	}
+	/* Don't check for old part number, that is ;-p */
+	if (dp >= &mbr.dmbr_parts[NDOSPART])
+		return (-1);
+
+	return (dp->dp_start);
+}
+
 /*
  * Load the prototype boot sector (biosboot) into memory.
  */
diff --git a/sys/arch/amd64/stand/libsa/biosdev.c b/sys/arch/amd64/stand/libsa/biosdev.c
index 696acf81d24..0e4439c8296 100644
--- a/sys/arch/amd64/stand/libsa/biosdev.c
+++ b/sys/arch/amd64/stand/libsa/biosdev.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: biosdev.c,v 1.4 2007/04/04 14:36:05 jmc Exp $	*/
+/*	$OpenBSD: biosdev.c,v 1.5 2008/06/25 15:26:44 reyk Exp $	*/
 
 /*
  * Copyright (c) 1996 Michael Shalayeff
@@ -45,6 +45,9 @@ static int biosdisk_errno(u_int);
 static int CHS_rw (int, int, int, int, int, int, void *);
 static int EDD_rw (int, int, u_int64_t, u_int32_t, void *);
 
+static daddr_t findopenbsd(bios_diskinfo_t *, daddr_t, daddr_t *,
+    const char **, int *);
+
 extern int debug;
 int bios_bootdev;
 int bios_cddev = -1;		/* Set by srt0 if coming from CD */
@@ -335,13 +338,76 @@ biosd_io(int rw, bios_diskinfo_t *bd, daddr_t off, int nsect, void *buf)
 /*
  * Try to read the bsd label on the given BIOS device
  */
+static daddr_t
+findopenbsd(bios_diskinfo_t *bd, daddr_t off, daddr_t *roff, const char **err,
+    int *n)
+{
+	int error, i;
+	struct dos_mbr mbr;
+	struct dos_partition *dp;
+
+	/* Limit the number of recursions */
+	if (!(*n)--) {
+		*err = "too many extended partitions";
+		return (0);
+	}
+
+	/* Read MBR */
+	error = biosd_io(F_READ, bd, off, 1, &mbr);
+	if (error) {
+		*err = biosdisk_err(error);
+		return (0);
+	}
+
+	/* check mbr signature */
+	if (mbr.dmbr_sign != DOSMBR_SIGNATURE) {
+		*err = "bad MBR signature\n";
+		return (0);
+	}
+
+	/* Search for OpenBSD partition */
+	for (off = 0, i = 0; off == 0 && i < NDOSPART; i++) {
+		dp = &mbr.dmbr_parts[i];
+#ifdef BIOS_DEBUG
+		if (debug)
+			printf("found partition %u: "
+			    "type %u (0x%x) offset %u (0x%x)\n",
+			    (int)(dp - mbr.dmbr_parts),
+			    dp->dp_typ, dp->dp_typ,
+			    dp->dp_start, dp->dp_start);
+#endif
+		if (dp->dp_typ == DOSPTYP_OPENBSD)
+			off = dp->dp_start;
+		else if (dp->dp_typ == DOSPTYP_EXTEND ||
+		    dp->dp_typ == DOSPTYP_EXTENDL) {
+			off = findopenbsd(bd, dp->dp_start, roff, err, n);
+			if (off != 0)
+				*roff = dp->dp_start;
+		}
+	}
+
+#ifdef BIOS_DEBUG
+	if (debug)
+		printf("using offset %u\n", off);
+#endif
+
+	if (off == 0) {
+		if (*err == NULL)
+			*err = "no OpenBSD partition\n";
+		return (0);
+	}
+
+	return (off);
+}
+
 const char *
 bios_getdisklabel(bios_diskinfo_t *bd, struct disklabel *label)
 {
-	daddr_t off = LABELSECTOR;
+	daddr_t off = 0, roff = 0;
 	char *buf;
-	struct dos_mbr mbr;
-	int error, i;
+	const char *err = NULL;
+	int error;
+	int n = 8;
 
 	/* Sanity check */
 	if(bd->bios_heads == 0 || bd->bios_sectors == 0)
@@ -349,23 +415,14 @@ bios_getdisklabel(bios_diskinfo_t *bd, struct disklabel *label)
 
 	/* MBR is a harddisk thing */
 	if (bd->bios_number & 0x80) {
-		/* Read MBR */
-		error = biosd_io(F_READ, bd, DOSBBSECTOR, 1, &mbr);
-		if (error)
-			return(biosdisk_err(error));
-
-		/* check mbr signature */
-		if (mbr.dmbr_sign != DOSMBR_SIGNATURE)
-			return("bad MBR signature\n");
-
-		/* Search for OpenBSD partition */
-		for (off = 0, i = 0; off == 0 && i < NDOSPART; i++)
-			if (mbr.dmbr_parts[i].dp_typ == DOSPTYP_OPENBSD)
-				off = mbr.dmbr_parts[i].dp_start + LABELSECTOR;
-		if (off == 0)
-			return("no OpenBSD partition\n");
-	} else
-		off = LABELSECTOR;
+		off = findopenbsd(bd, DOSBBSECTOR, &roff, &err, &n);
+		if (off == 0) {
+			if (err != NULL)
+				return (err);
+ 			return "no OpenBSD partition\n";
+		}
+	}
+	off = LABELSECTOR + off + roff;
 
 	/* Load BSD disklabel */
 	buf = alloca(DEV_BSIZE);
diff --git a/sys/arch/i386/stand/installboot/installboot.c b/sys/arch/i386/stand/installboot/installboot.c
index d8c7a7daa3a..d0a450147a1 100644
--- a/sys/arch/i386/stand/installboot/installboot.c
+++ b/sys/arch/i386/stand/installboot/installboot.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: installboot.c,v 1.51 2008/01/24 12:09:54 krw Exp $	*/
+/*	$OpenBSD: installboot.c,v 1.52 2008/06/25 15:26:44 reyk Exp $	*/
 /*	$NetBSD: installboot.c,v 1.5 1995/11/17 23:23:50 gwr Exp $ */
 
 /*
@@ -94,6 +94,7 @@ static void	devread(int, void *, daddr_t, size_t, char *);
 static void	sym_set_value(struct sym_data *, char *, u_int32_t);
 static void	pbr_set_symbols(char *, char *, struct sym_data *);
 static void	usage(void);
+static long	findopenbsd(int, struct disklabel *, off_t, int *);
 
 static void
 usage(void)
@@ -116,9 +117,9 @@ main(int argc, char *argv[])
 	long	protosize;
 	struct	stat sb;
 	struct	disklabel dl;
-	struct	dos_mbr mbr;
-	struct	dos_partition *dp;
 	off_t	startoff = 0;
+	long	start = 0;
+	int	n = 8;
 
 	while ((c = getopt(argc, argv, "vn")) != -1) {
 		switch (c) {
@@ -196,29 +197,11 @@ main(int argc, char *argv[])
 
 	if (dl.d_type != 0 && dl.d_type != DTYPE_FLOPPY &&
 	    dl.d_type != DTYPE_VND) {
-		if (lseek(devfd, (off_t)DOSBBSECTOR, SEEK_SET) < 0 ||
-		    read(devfd, &mbr, sizeof(mbr)) != sizeof(mbr))
-			err(4, "can't read master boot record");
-
-		if (mbr.dmbr_sign != DOSMBR_SIGNATURE)
-			errx(1, "broken MBR");
-
 		/* Find OpenBSD partition. */
-		for (dp = mbr.dmbr_parts; dp < &mbr.dmbr_parts[NDOSPART];
-		    dp++) {
-			if (dp->dp_size && dp->dp_typ == DOSPTYP_OPENBSD) {
-				startoff = (off_t)dp->dp_start * dl.d_secsize;
-				fprintf(stderr, "using MBR partition %ld: "
-				    "type %d (0x%02x) offset %d (0x%x)\n",
-				    (long)(dp - mbr.dmbr_parts),
-				    dp->dp_typ, dp->dp_typ,
-				    dp->dp_start, dp->dp_start);
-				break;
-			}
-		}
-		/* Don't check for old part number, that is ;-p */
-		if (dp >= &mbr.dmbr_parts[NDOSPART])
-			errx(1, "no OpenBSD partition");
+		start = findopenbsd(devfd, &dl, (off_t)DOSBBSECTOR, &n);
+		if (start == -1)
+ 			errx(1, "no OpenBSD partition");
+		startoff = (off_t)start * dl.d_secsize;
 	}
 
 	if (!nowrite) {
@@ -232,6 +215,56 @@ main(int argc, char *argv[])
 	return 0;
 }
 
+long
+findopenbsd(int devfd, struct disklabel *dl, off_t mbroff, int *n)
+{
+	struct		dos_mbr mbr;
+	struct		dos_partition *dp;
+	off_t		startoff;
+	long		start;
+
+	/* Limit the number of recursions */
+	if (!(*n)--)
+		return (-1);
+
+	if (lseek(devfd, mbroff, SEEK_SET) < 0 ||
+	    read(devfd, &mbr, sizeof(mbr)) != sizeof(mbr))
+		err(4, "can't read master boot record");
+
+	if (mbr.dmbr_sign != DOSMBR_SIGNATURE)
+		errx(1, "broken MBR");
+
+	for (dp = mbr.dmbr_parts; dp < &mbr.dmbr_parts[NDOSPART];
+	    dp++) {
+		if (!dp->dp_size)
+			continue;
+		startoff = (off_t)dp->dp_start * dl->d_secsize;
+		if (dp->dp_typ == DOSPTYP_OPENBSD) {
+			fprintf(stderr, "using MBR partition %ld: "
+			    "type %d (0x%02x) offset %d (0x%x)\n",
+			    (long)(dp - mbr.dmbr_parts),
+			    dp->dp_typ, dp->dp_typ,
+			    dp->dp_start, dp->dp_start);
+			break;
+		} else if (dp->dp_typ == DOSPTYP_EXTEND ||
+		    dp->dp_typ == DOSPTYP_EXTENDL) {
+			fprintf(stderr, "extended partition %ld: "
+			    "type %d (0x%02x) offset %d (0x%x)\n",
+			    (long)(dp - mbr.dmbr_parts),
+			    dp->dp_typ, dp->dp_typ,
+			    dp->dp_start, dp->dp_start);
+			start = findopenbsd(devfd, dl, startoff, n);
+			if (start != -1)
+				return (dp->dp_start + start);
+		}
+	}
+	/* Don't check for old part number, that is ;-p */
+	if (dp >= &mbr.dmbr_parts[NDOSPART])
+		return (-1);
+
+	return (dp->dp_start);
+}
+
 /*
  * Load the prototype boot sector (biosboot) into memory.
  */
diff --git a/sys/arch/i386/stand/libsa/biosdev.c b/sys/arch/i386/stand/libsa/biosdev.c
index 4d6348a8c72..9603fcb8ddd 100644
--- a/sys/arch/i386/stand/libsa/biosdev.c
+++ b/sys/arch/i386/stand/libsa/biosdev.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: biosdev.c,v 1.72 2007/05/27 00:57:17 tom Exp $	*/
+/*	$OpenBSD: biosdev.c,v 1.73 2008/06/25 15:26:44 reyk Exp $	*/
 
 /*
  * Copyright (c) 1996 Michael Shalayeff
@@ -46,6 +46,9 @@ static int biosdisk_errno(u_int);
 static int CHS_rw (int, int, int, int, int, int, void *);
 static int EDD_rw (int, int, u_int64_t, u_int32_t, void *);
 
+static daddr_t findopenbsd(bios_diskinfo_t *, daddr_t, daddr_t *,
+    const char **, int *);
+
 extern int debug;
 int bios_bootdev;
 int bios_cddev = -1;		/* Set by srt0 if coming from CD */
@@ -338,13 +341,76 @@ biosd_io(int rw, bios_diskinfo_t *bd, daddr_t off, int nsect, void *buf)
 /*
  * Try to read the bsd label on the given BIOS device
  */
+static daddr_t
+findopenbsd(bios_diskinfo_t *bd, daddr_t off, daddr_t *roff, const char **err,
+    int *n)
+{
+	int error, i;
+	struct dos_mbr mbr;
+	struct dos_partition *dp;
+
+	/* Limit the number of recursions */
+	if (!(*n)--) {
+		*err = "too many extended partitions";
+		return (0);
+	}
+
+	/* Read MBR */
+	error = biosd_io(F_READ, bd, off, 1, &mbr);
+	if (error) {
+		*err = biosdisk_err(error);
+		return (0);
+	}
+
+	/* check mbr signature */
+	if (mbr.dmbr_sign != DOSMBR_SIGNATURE) {
+		*err = "bad MBR signature\n";
+		return (0);
+	}
+
+	/* Search for OpenBSD partition */
+	for (off = 0, i = 0; off == 0 && i < NDOSPART; i++) {
+		dp = &mbr.dmbr_parts[i];
+#ifdef BIOS_DEBUG
+		if (debug)
+			printf("found partition %u: "
+			    "type %u (0x%x) offset %u (0x%x)\n",
+			    (int)(dp - mbr.dmbr_parts),
+			    dp->dp_typ, dp->dp_typ,
+			    dp->dp_start, dp->dp_start);
+#endif
+		if (dp->dp_typ == DOSPTYP_OPENBSD)
+			off = dp->dp_start;
+		else if (dp->dp_typ == DOSPTYP_EXTEND ||
+		    dp->dp_typ == DOSPTYP_EXTENDL) {
+			off = findopenbsd(bd, dp->dp_start, roff, err, n);
+			if (off != 0)
+				*roff = dp->dp_start;
+		}
+	}
+
+#ifdef BIOS_DEBUG
+	if (debug)
+		printf("using offset %u\n", off);
+#endif
+
+	if (off == 0) {
+		if (*err == NULL)
+			*err = "no OpenBSD partition\n";
+		return (0);
+	}
+
+	return (off);
+}
+
 const char *
 bios_getdisklabel(bios_diskinfo_t *bd, struct disklabel *label)
 {
-	daddr_t off = LABELSECTOR;
+	daddr_t off = 0, roff = 0;
 	char *buf;
-	struct dos_mbr mbr;
-	int error, i;
+	const char *err = NULL;
+	int error;
+	int n = 8;
 
 	/* Sanity check */
 	if (bd->bios_heads == 0 || bd->bios_sectors == 0)
@@ -352,23 +418,14 @@ bios_getdisklabel(bios_diskinfo_t *bd, struct disklabel *label)
 
 	/* MBR is a harddisk thing */
 	if (bd->bios_number & 0x80) {
-		/* Read MBR */
-		error = biosd_io(F_READ, bd, DOSBBSECTOR, 1, &mbr);
-		if (error)
-			return (biosdisk_err(error));
-
-		/* check mbr signature */
-		if (mbr.dmbr_sign != DOSMBR_SIGNATURE)
-			return "bad MBR signature\n";
-
-		/* Search for OpenBSD partition */
-		for (off = 0, i = 0; off == 0 && i < NDOSPART; i++)
-			if (mbr.dmbr_parts[i].dp_typ == DOSPTYP_OPENBSD)
-				off = mbr.dmbr_parts[i].dp_start + LABELSECTOR;
-		if (off == 0)
-			return "no OpenBSD partition\n";
-	} else
-		off = LABELSECTOR;
+		off = findopenbsd(bd, DOSBBSECTOR, &roff, &err, &n);
+		if (off == 0) {
+			if (err != NULL)
+				return (err);
+ 			return "no OpenBSD partition\n";
+		}
+	}
+	off = LABELSECTOR + off + roff;
 
 	/* Load BSD disklabel */
 	buf = alloca(DEV_BSIZE);
diff --git a/sys/kern/subr_disk.c b/sys/kern/subr_disk.c
index e3d80ae69ff..186ff615e10 100644
--- a/sys/kern/subr_disk.c
+++ b/sys/kern/subr_disk.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: subr_disk.c,v 1.78 2008/06/12 06:58:39 deraadt Exp $	*/
+/*	$OpenBSD: subr_disk.c,v 1.79 2008/06/25 15:26:43 reyk Exp $	*/
 /*	$NetBSD: subr_disk.c,v 1.17 1996/03/16 23:17:08 christos Exp $	*/
 
 /*
@@ -409,7 +409,7 @@ readdoslabel(struct buf *bp, void (*strat)(struct buf *),
 
 		bcopy(bp->b_data + DOSPARTOFF, dp, sizeof(dp));
 
-		if (ourpart == -1 && part_blkno == DOSBBSECTOR) {
+		if (ourpart == -1) {
 			/* Search for our MBR partition */
 			for (dp2=dp, i=0; i < NDOSPART && ourpart == -1;
 			    i++, dp2++)
@@ -454,11 +454,6 @@ donot:
 				continue;
 			if (letoh32(dp2->dp_size) == 0)
 				continue;
-			if (letoh32(dp2->dp_start))
-				DL_SETPOFFSET(pp,
-				    letoh32(dp2->dp_start) + part_blkno);
-
-			DL_SETPSIZE(pp, letoh32(dp2->dp_size));
 
 			switch (dp2->dp_typ) {
 			case DOSPTYP_UNUSED:
@@ -499,6 +494,19 @@ donot:
 				n++;
 				break;
 			}
+
+			/*
+			 * There is no need to set the offset/size when
+			 * wandering; it would also invalidate the
+			 * disklabel checksum.
+			 */
+			if (wander)
+				continue;
+
+			if (letoh32(dp2->dp_start))
+				DL_SETPOFFSET(pp,
+				    letoh32(dp2->dp_start) + part_blkno);
+			DL_SETPSIZE(pp, letoh32(dp2->dp_size));
 		}
 	}
 	lp->d_npartitions = MAXPARTITIONS;