o Newer EFI implementations require that a GPT is preceeded by

   a PMBR. Make sure the create command creates a PMBR as well
   (if not already present).
o  When parsing the MBR, explicitly check for a PMBR and create
   a PMBR map node if one is found.
o  When parsing the MBR, recurse to handle extended partitions.
   This allows us to flatten nested MBRs when migrating to a
   GPT.
o  Have the migrate command bail out if it encounters a partition
   it doesn't know how to migrate. This avoids data loss.
o  Change the output of the show command so that the UUIDs of the
   GPT partitions fit on the same line.
o  Show when partitions are extended partitions and add the PMBR
   type.

Approved by: re (blanket)

5 files changed, 153 insertions, 55 deletions

diff --git a/sbin/gpt/create.c b/sbin/gpt/create.c
index ec2b121..e9ac8ce 100644
--- a/sbin/gpt/create.c
+++ b/sbin/gpt/create.c
@@ -58,6 +58,7 @@ create(int fd)
 	map_t *gpt, *tpg;
 	map_t *tbl, *lbt;
 	map_t *map;
+	struct mbr *mbr;
 	struct gpt_hdr *hdr;
 	struct gpt_ent *ent;
 	unsigned int i;
@@ -67,6 +68,40 @@ create(int fd)
 		warnx("%s: error: device already contains a GPT", device_name);
 		return;
 	}
+	if (map_find(MAP_TYPE_MBR) != NULL) {
+		warnx("%s: error: device contains a MBR", device_name);
+		return;
+	}
+
+	/*
+	 * Create PMBR.
+	 */
+	if (map_find(MAP_TYPE_PMBR) == NULL) {
+		if (map_free(0LL, 1LL) == 0) {
+			warnx("%s: error: no room for the PMBR", device_name);
+			return;
+		}
+		mbr = gpt_read(fd, 0LL, 1);
+		bzero(mbr, sizeof(*mbr));
+		mbr->mbr_sig = MBR_SIG;
+		mbr->mbr_part[0].part_shd = 0xff;
+		mbr->mbr_part[0].part_ssect = 0xff;
+		mbr->mbr_part[0].part_scyl = 0xff;
+		mbr->mbr_part[0].part_typ = 0xee;
+		mbr->mbr_part[0].part_ehd = 0xff;
+		mbr->mbr_part[0].part_esect = 0xff;
+		mbr->mbr_part[0].part_ecyl = 0xff;
+		mbr->mbr_part[0].part_start_lo = 1;
+		if (mediasz > 0xffffffff) {
+			mbr->mbr_part[0].part_size_lo = 0xffff;
+			mbr->mbr_part[0].part_size_hi = 0xffff;
+		} else {
+			mbr->mbr_part[0].part_size_lo = mediasz & 0xffff;
+			mbr->mbr_part[0].part_size_hi = mediasz >> 16;
+		}
+		map = map_add(0LL, 1LL, MAP_TYPE_PMBR, mbr);
+		gpt_write(fd, map);
+	}
 
 	/* Get the amount of free space after the MBR */
 	blocks = map_free(1LL, 0LL);
diff --git a/sbin/gpt/gpt.c b/sbin/gpt/gpt.c
index 28b28b2..6ab98d1 100644
--- a/sbin/gpt/gpt.c
+++ b/sbin/gpt/gpt.c
@@ -162,6 +162,90 @@ gpt_write(int fd, map_t *map)
 }
 
 static int
+gpt_mbr(int fd, off_t lba)
+{
+	struct mbr *mbr;
+	map_t *m, *p;
+	off_t size, start;
+	unsigned int i, pmbr;
+
+	mbr = gpt_read(fd, lba, 1);
+	if (mbr == NULL)
+		return (-1);
+
+	if (mbr->mbr_sig != MBR_SIG) {
+		if (verbose)
+			warnx("%s: MBR not found at sector %llu", device_name,
+			    (long long)lba);
+		free(mbr);
+		return (0);
+	}
+
+	/*
+	 * Differentiate between a regular MBR and a PMBR. This is more
+	 * convenient in general. A PMBR is one with a single partition
+	 * of type 0xee.
+	 */
+	pmbr = 0;
+	for (i = 0; i < 4; i++) {
+		if (mbr->mbr_part[i].part_typ == 0)
+			continue;
+		if (mbr->mbr_part[i].part_typ == 0xee)
+			pmbr++;
+		else
+			break;
+	}
+	if (pmbr && i == 4 && lba == 0) {
+		if (pmbr != 1)
+			warnx("%s: Suspicious PMBR at sector %llu",
+			    device_name, (long long)lba);
+		else if (verbose > 1)
+			warnx("%s: PMBR at sector %llu", device_name,
+			    (long long)lba);
+		p = map_add(lba, 1LL, MAP_TYPE_PMBR, mbr);
+		return ((p == NULL) ? -1 : 0);
+	}
+	if (pmbr)
+		warnx("%s: Suspicious MBR at sector %llu", device_name,
+		    (long long)lba);
+	else if (verbose > 1)
+		warnx("%s: MBR at sector %llu", device_name, (long long)lba);
+
+	p = map_add(lba, 1LL, MAP_TYPE_MBR, mbr);
+	if (p == NULL)
+		return (-1);
+	for (i = 0; i < 4; i++) {
+		if (mbr->mbr_part[i].part_typ == 0 ||
+		    mbr->mbr_part[i].part_typ == 0xee)
+			continue;
+		start = mbr->mbr_part[i].part_start_hi;
+		start = (start << 16) + mbr->mbr_part[i].part_start_lo;
+		size = mbr->mbr_part[i].part_size_hi;
+		size = (size << 16) + mbr->mbr_part[i].part_size_lo;
+		if (start == 0 && size == 0) {
+			warnx("%s: Malformed MBR at sector %llu", device_name,
+			    (long long)lba);
+			continue;
+		}
+		/* start is relative to the offset of the MBR itself. */
+		start += lba;
+		if (verbose > 2)
+			warnx("%s: MBR part: type=%d, start=%llu, size=%llu",
+			    device_name, mbr->mbr_part[i].part_typ,
+			    (long long)start, (long long)size);
+		if (mbr->mbr_part[i].part_typ != 15) {
+			m = map_add(start, size, MAP_TYPE_MBR_PART, p);
+			if (m == NULL)
+				return (-1);
+		} else {
+			if (gpt_mbr(fd, start) == -1)
+				return (-1);
+		}
+	}
+	return (0);
+}
+
+static int
 gpt_gpt(int fd, off_t lba)
 {
 	off_t size;
@@ -252,10 +336,6 @@ int
 gpt_open(const char *dev)
 {
 	struct stat sb;
-	struct mbr *mbr;
-	map_t *m;
-	uint32_t size, start;
-	unsigned int i;
 	int fd;
 
 	if (!stat(dev, &sb)) {
@@ -306,46 +386,8 @@ gpt_open(const char *dev)
 
 	map_init(mediasz / secsz);
 
-	/*
-	 * MBR
-	 */
-	mbr = gpt_read(fd, 0LL, 1);
-	if (mbr == NULL)
+	if (gpt_mbr(fd, 0LL) == -1)
 		goto close;
-
-	if (mbr->mbr_sig == MBR_SIG) {
-		if (verbose > 1)
-			warnx("%s: MBR at sector 0", device_name);
-		m = map_add(0LL, 1LL, MAP_TYPE_MBR, mbr);
-		if (m == NULL)
-			goto close;
-		for (i = 0; i < 4; i++) {
-			start = mbr->mbr_part[i].part_start_hi;
-			start = (start << 16) + mbr->mbr_part[i].part_start_lo;
-			size = mbr->mbr_part[i].part_size_hi;
-			size = (size << 16) + mbr->mbr_part[i].part_size_lo;
-			if (start == 0 && size == 0)
-				continue;
-			if (verbose > 2)
-				warnx("%s: MBR partition: type=%d, start=%llu, size=%llu",
-				    device_name, mbr->mbr_part[i].part_typ,
-				    (long long)start, (long long)size);
-			if (mbr->mbr_part[i].part_typ == 0xee)
-				continue;
-			m = map_add(start, size, MAP_TYPE_MBR_PART,
-			    mbr->mbr_part + i);
-			if (m == NULL)
-				goto close;
-		}
-	} else {
-		if (verbose)
-			warnx("%s: MBR not found", device_name);
-		free(mbr);
-	}
-
-	/*
-	 * GPT
-	 */
 	if (gpt_gpt(fd, 1LL) == -1)
 		goto close;
 	if (gpt_gpt(fd, mediasz / secsz - 1LL) == -1)
diff --git a/sbin/gpt/map.h b/sbin/gpt/map.h
index 4bdc94a..34ea0a6 100644
--- a/sbin/gpt/map.h
+++ b/sbin/gpt/map.h
@@ -43,6 +43,7 @@ typedef struct map {
 #define	MAP_TYPE_PRI_GPT_TBL	5
 #define	MAP_TYPE_SEC_GPT_TBL	6
 #define	MAP_TYPE_GPT_PART	7
+#define	MAP_TYPE_PMBR		8
 	void 	*map_data;
 } map_t;
 
diff --git a/sbin/gpt/migrate.c b/sbin/gpt/migrate.c
index eca172d..f0affa9 100644
--- a/sbin/gpt/migrate.c
+++ b/sbin/gpt/migrate.c
@@ -92,6 +92,8 @@ migrate_disklabel(int fd, off_t start, struct gpt_ent *ent)
 			break;
 		}
 		default:
+			warnx("%s: warning: unknown FreeBSD partition (%d)",
+			    device_name, dl->d_partitions[i].p_fstype);
 			continue;
 		}
 
@@ -120,9 +122,8 @@ migrate(int fd)
 	last = mediasz / secsz - 1LL;
 
 	map = map_find(MAP_TYPE_MBR);
-	if (map == NULL || map_find(MAP_TYPE_MBR_PART) == NULL) {
-		warnx("%s: error: no partitions to convert",
-		    device_name);
+	if (map == NULL || map->map_start != 0) {
+		warnx("%s: error: no partitions to convert", device_name);
 		return;
 	}
 
@@ -212,6 +213,8 @@ migrate(int fd)
 		size = (size << 16) + mbr->mbr_part[i].part_size_lo;
 
 		switch (mbr->mbr_part[i].part_typ) {
+		case 0:
+			continue;
 		case 165: {	/* FreeBSD */
 			if (slice) {
 				uuid_t freebsd = GPT_ENT_TYPE_FREEBSD;
@@ -235,7 +238,9 @@ migrate(int fd)
 			break;
 		}
 		default:
-			continue;
+			warnx("%s: error: unknown partition type (%d)",
+			    device_name, mbr->mbr_part[i].part_typ);
+			return;
 		}
 	}
 	ent = tbl->map_data;
diff --git a/sbin/gpt/show.c b/sbin/gpt/show.c
index 27fc113..3e9ebc8 100644
--- a/sbin/gpt/show.c
+++ b/sbin/gpt/show.c
@@ -52,11 +52,12 @@ usage_show(void)
 static void
 show(int fd __unused)
 {
-	off_t end;
-	map_t *m;
-	struct mbr_part *part;
+	off_t start, end;
+	map_t *m, *p;
+	struct mbr *mbr;
 	struct gpt_ent *ent;
 	char *s;
+	unsigned int i;
 
 	printf("  %*s", lbawidth, "start");
 	printf("  %*s", lbawidth, "end");
@@ -73,6 +74,8 @@ show(int fd __unused)
 		putchar(' '); putchar(' ');
 		switch (m->map_type) {
 		case MAP_TYPE_MBR:
+			if (m->map_start != 0)
+				printf("Extended ");
 			printf("MBR");
 			break;
 		case MAP_TYPE_PRI_GPT_HDR:
@@ -88,17 +91,29 @@ show(int fd __unused)
 			printf("Sec GPT table");
 			break;
 		case MAP_TYPE_MBR_PART:
-			printf("MBR partition: ");
-			part = m->map_data;
-			printf("type=%d", part->part_typ);
+			p = m->map_data;
+			if (p->map_start != 0)
+				printf("Extended ");
+			printf("MBR part ");
+			mbr = p->map_data;
+			for (i = 0; i < 4; i++) {
+				start = mbr->mbr_part[i].part_start_hi << 16;
+				start += mbr->mbr_part[i].part_start_lo;
+				if (m->map_start == p->map_start + start)
+					break;
+			}
+			printf("%d", mbr->mbr_part[i].part_typ);
 			break;
 		case MAP_TYPE_GPT_PART:
-			printf("GPT partition: ");
+			printf("GPT part ");
 			ent = m->map_data;
 			uuid_to_string(&ent->ent_type, &s, NULL);
-			printf("type=%s", s);
+			printf("%s", s);
 			free(s);
 			break;
+		case MAP_TYPE_PMBR:
+			printf("PMBR");
+			break;
 		}
 		putchar('\n');
 		m = m->map_next;