Create the interface to work with various partition tables from the

loader(8). The following partition tables are supported: BSD label, GPT,
MBR, EBR and VTOC8.

2 files changed, 921 insertions, 0 deletions

diff --git a/sys/boot/common/part.c b/sys/boot/common/part.c
new file mode 100644
index 0000000..34a08b1
--- /dev/null
+++ b/sys/boot/common/part.c
@@ -0,0 +1,839 @@
+/*-
+ * Copyright (c) 2012 Andrey V. Elsukov <ae@FreeBSD.org>
+ * All rights reserved.
+ *
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHORS 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 AUTHORS 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.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <stand.h>
+#include <sys/param.h>
+#include <sys/diskmbr.h>
+#include <sys/disklabel.h>
+#include <sys/endian.h>
+#include <sys/gpt.h>
+#include <sys/stddef.h>
+#include <sys/queue.h>
+#include <sys/vtoc.h>
+
+#include <crc32.h>
+#include <part.h>
+#include <uuid.h>
+
+#ifdef PART_DEBUG
+#define	DEBUG(fmt, args...) printf("%s: " fmt "\n" , __func__ , ## args)
+#else
+#define	DEBUG(fmt, args...)
+#endif
+
+#ifdef LOADER_GPT_SUPPORT
+#define	MAXTBLSZ	64
+static const uuid_t gpt_uuid_unused = GPT_ENT_TYPE_UNUSED;
+static const uuid_t gpt_uuid_ms_basic_data = GPT_ENT_TYPE_MS_BASIC_DATA;
+static const uuid_t gpt_uuid_freebsd_ufs = GPT_ENT_TYPE_FREEBSD_UFS;
+static const uuid_t gpt_uuid_efi = GPT_ENT_TYPE_EFI;
+static const uuid_t gpt_uuid_freebsd_boot = GPT_ENT_TYPE_FREEBSD_BOOT;
+static const uuid_t gpt_uuid_freebsd_nandfs = GPT_ENT_TYPE_FREEBSD_NANDFS;
+static const uuid_t gpt_uuid_freebsd_swap = GPT_ENT_TYPE_FREEBSD_SWAP;
+static const uuid_t gpt_uuid_freebsd_zfs = GPT_ENT_TYPE_FREEBSD_ZFS;
+static const uuid_t gpt_uuid_freebsd_vinum = GPT_ENT_TYPE_FREEBSD_VINUM;
+#endif
+
+struct pentry {
+	struct ptable_entry	part;
+	uint64_t		flags;
+	union {
+		uint8_t bsd;
+		uint8_t	mbr;
+		uuid_t	gpt;
+		uint16_t vtoc8;
+	} type;
+	STAILQ_ENTRY(pentry)	entry;
+};
+
+struct ptable {
+	enum ptable_type	type;
+	uint16_t		sectorsize;
+	uint64_t		sectors;
+
+	STAILQ_HEAD(, pentry)	entries;
+};
+
+static struct parttypes {
+	enum partition_type	type;
+	const char		*desc;
+} ptypes[] = {
+	{ PART_UNKNOWN,		"Unknown" },
+	{ PART_EFI,		"EFI" },
+	{ PART_FREEBSD,		"FreeBSD" },
+	{ PART_FREEBSD_BOOT,	"FreeBSD boot" },
+	{ PART_FREEBSD_NANDFS,	"FreeBSD nandfs" },
+	{ PART_FREEBSD_UFS,	"FreeBSD UFS" },
+	{ PART_FREEBSD_ZFS,	"FreeBSD ZFS" },
+	{ PART_FREEBSD_SWAP,	"FreeBSD swap" },
+	{ PART_FREEBSD_VINUM,	"FreeBSD vinum" },
+	{ PART_LINUX,		"Linux" },
+	{ PART_LINUX_SWAP,	"Linux swap" },
+	{ PART_DOS,		"DOS/Windows" },
+};
+
+const char *
+parttype2str(enum partition_type type)
+{
+	int i;
+
+	for (i = 0; i < sizeof(ptypes) / sizeof(ptypes[0]); i++)
+		if (ptypes[i].type == type)
+			return (ptypes[i].desc);
+	return (ptypes[0].desc);
+}
+
+#ifdef LOADER_GPT_SUPPORT
+static void
+uuid_letoh(uuid_t *uuid)
+{
+
+	uuid->time_low = le32toh(uuid->time_low);
+	uuid->time_mid = le16toh(uuid->time_mid);
+	uuid->time_hi_and_version = le16toh(uuid->time_hi_and_version);
+}
+
+static enum partition_type
+gpt_parttype(uuid_t type)
+{
+
+	if (uuid_equal(&type, &gpt_uuid_efi, NULL))
+		return (PART_EFI);
+	else if (uuid_equal(&type, &gpt_uuid_ms_basic_data, NULL))
+		return (PART_DOS);
+	else if (uuid_equal(&type, &gpt_uuid_freebsd_boot, NULL))
+		return (PART_FREEBSD_BOOT);
+	else if (uuid_equal(&type, &gpt_uuid_freebsd_ufs, NULL))
+		return (PART_FREEBSD_UFS);
+	else if (uuid_equal(&type, &gpt_uuid_freebsd_zfs, NULL))
+		return (PART_FREEBSD_ZFS);
+	else if (uuid_equal(&type, &gpt_uuid_freebsd_swap, NULL))
+		return (PART_FREEBSD_SWAP);
+	else if (uuid_equal(&type, &gpt_uuid_freebsd_vinum, NULL))
+		return (PART_FREEBSD_VINUM);
+	else if (uuid_equal(&type, &gpt_uuid_freebsd_nandfs, NULL))
+		return (PART_FREEBSD_NANDFS);
+	return (PART_UNKNOWN);
+}
+
+static struct gpt_hdr*
+gpt_checkhdr(struct gpt_hdr *hdr, uint64_t lba_self, uint64_t lba_last,
+    uint16_t sectorsize)
+{
+	uint32_t sz, crc;
+
+	if (memcmp(hdr->hdr_sig, GPT_HDR_SIG, sizeof(hdr->hdr_sig)) != 0) {
+		DEBUG("no GPT signature");
+		return (NULL);
+	}
+	sz = le32toh(hdr->hdr_size);
+	if (sz < 92 || sz > sectorsize) {
+		DEBUG("invalid GPT header size: %d", sz);
+		return (NULL);
+	}
+	crc = le32toh(hdr->hdr_crc_self);
+	hdr->hdr_crc_self = 0;
+	if (crc32(hdr, sz) != crc) {
+		DEBUG("GPT header's CRC doesn't match");
+		return (NULL);
+	}
+	hdr->hdr_crc_self = crc;
+	hdr->hdr_revision = le32toh(hdr->hdr_revision);
+	if (hdr->hdr_revision < GPT_HDR_REVISION) {
+		DEBUG("unsupported GPT revision %d", hdr->hdr_revision);
+		return (NULL);
+	}
+	hdr->hdr_lba_self = le64toh(hdr->hdr_lba_self);
+	if (hdr->hdr_lba_self != lba_self) {
+		DEBUG("self LBA doesn't match");
+		return (NULL);
+	}
+	hdr->hdr_lba_alt = le64toh(hdr->hdr_lba_alt);
+	if (hdr->hdr_lba_alt == hdr->hdr_lba_self) {
+		DEBUG("invalid alternate LBA");
+		return (NULL);
+	}
+	hdr->hdr_entries = le32toh(hdr->hdr_entries);
+	hdr->hdr_entsz = le32toh(hdr->hdr_entsz);
+	if (hdr->hdr_entries < 128 ||
+	    hdr->hdr_entsz < sizeof(struct gpt_ent) ||
+	    sectorsize % hdr->hdr_entsz != 0) {
+		DEBUG("invalid entry size or number of entries");
+		return (NULL);
+	}
+	hdr->hdr_lba_start = le64toh(hdr->hdr_lba_start);
+	hdr->hdr_lba_end = le64toh(hdr->hdr_lba_end);
+	hdr->hdr_lba_table = le64toh(hdr->hdr_lba_table);
+	hdr->hdr_crc_table = le32toh(hdr->hdr_crc_table);
+	uuid_letoh(&hdr->hdr_uuid);
+	return (hdr);
+}
+
+static int
+gpt_checktbl(const struct gpt_hdr *hdr, u_char *tbl, size_t size,
+    uint64_t lba_last)
+{
+	struct gpt_ent *ent;
+	int i, cnt;
+
+	cnt = size / hdr->hdr_entsz;
+	/* Check CRC only when buffer size is enough for table. */
+	if (hdr->hdr_entries <= cnt &&
+	    crc32(tbl, size) != hdr->hdr_crc_table) {
+		DEBUG("GPT table's CRC doesn't match");
+		return (-1);
+	}
+	ent = (struct gpt_ent *)tbl;
+	for (i = 0; i < cnt; i++, ent++) {
+		uuid_letoh(&ent->ent_type);
+		if (uuid_equal(&ent->ent_type, &gpt_uuid_unused, NULL))
+			continue;
+		ent->ent_lba_start = le64toh(ent->ent_lba_start);
+		ent->ent_lba_end = le64toh(ent->ent_lba_end);
+	}
+	return (0);
+}
+
+static struct ptable*
+ptable_gptread(struct ptable *table, void *dev, diskread_t dread)
+{
+	struct pentry *entry;
+	struct gpt_hdr *phdr, hdr;
+	struct gpt_ent *ent;
+	u_char *buf, *tbl;
+	uint64_t offset;
+	int pri, sec, i;
+	size_t size;
+
+	buf = malloc(table->sectorsize);
+	if (buf == NULL)
+		return (NULL);
+	tbl = malloc(table->sectorsize * MAXTBLSZ);
+	if (tbl == NULL) {
+		free(buf);
+		return (NULL);
+	}
+	/* Read the primary GPT header. */
+	if (dread(dev, buf, 1, 1) != 0) {
+		ptable_close(table);
+		table = NULL;
+		goto out;
+	}
+	pri = sec = 0;
+	/* Check the primary GPT header. */
+	phdr = gpt_checkhdr((struct gpt_hdr *)buf, 1, table->sectors - 1,
+	    table->sectorsize);
+	if (phdr != NULL) {
+		/* Read the primary GPT table. */
+		size = MIN(MAXTBLSZ,
+		    phdr->hdr_entries * phdr->hdr_entsz / table->sectorsize);
+		if (dread(dev, tbl, size, phdr->hdr_lba_table) == 0 &&
+		    gpt_checktbl(phdr, tbl, size * table->sectorsize,
+		    table->sectors - 1) == 0) {
+			memcpy(&hdr, phdr, sizeof(hdr));
+			pri = 1;
+		}
+	}
+	offset = pri ? hdr.hdr_lba_alt: table->sectors - 1;
+	/* Read the backup GPT header. */
+	if (dread(dev, buf, 1, offset) != 0)
+		phdr = NULL;
+	else
+		phdr = gpt_checkhdr((struct gpt_hdr *)buf, offset,
+		    table->sectors - 1, table->sectorsize);
+	if (phdr != NULL) {
+		/*
+		 * Compare primary and backup headers.
+		 * If they are equal, then we do not need to read backup
+		 * table. If they are different, then prefer backup header
+		 * and try to read backup table.
+		 */
+		if (pri == 0 ||
+		    uuid_equal(&hdr.hdr_uuid, &phdr->hdr_uuid, NULL) == 0 ||
+		    hdr.hdr_revision != phdr->hdr_revision ||
+		    hdr.hdr_size != phdr->hdr_size ||
+		    hdr.hdr_lba_start != phdr->hdr_lba_start ||
+		    hdr.hdr_lba_end != phdr->hdr_lba_end ||
+		    hdr.hdr_entries != phdr->hdr_entries ||
+		    hdr.hdr_entsz != phdr->hdr_entsz ||
+		    hdr.hdr_crc_table != phdr->hdr_crc_table) {
+			/* Read the backup GPT table. */
+			size = MIN(MAXTBLSZ, phdr->hdr_entries *
+			    phdr->hdr_entsz / table->sectorsize);
+			if (dread(dev, tbl, size, phdr->hdr_lba_table) == 0 &&
+			    gpt_checktbl(phdr, tbl, size * table->sectorsize,
+			    table->sectors - 1) == 0) {
+				memcpy(&hdr, phdr, sizeof(hdr));
+				sec = 1;
+			}
+		}
+	}
+	if (pri == 0 && sec == 0) {
+		/* Both primary and backup tables are invalid. */
+		table->type = PTABLE_NONE;
+		goto out;
+	}
+	ent = (struct gpt_ent *)tbl;
+	size = MIN(hdr.hdr_entries * hdr.hdr_entsz,
+	    MAXTBLSZ * table->sectorsize);
+	for (i = 0; i < size / hdr.hdr_entsz; i++, ent++) {
+		if (uuid_equal(&ent->ent_type, &gpt_uuid_unused, NULL))
+			continue;
+		entry = malloc(sizeof(*entry));
+		if (entry == NULL)
+			break;
+		entry->part.start = ent->ent_lba_start;
+		entry->part.end = ent->ent_lba_end;
+		entry->part.index = i + 1;
+		entry->part.type = gpt_parttype(ent->ent_type);
+		entry->flags = le64toh(ent->ent_attr);
+		memcpy(&entry->type.gpt, &ent->ent_type, sizeof(uuid_t));
+		STAILQ_INSERT_TAIL(&table->entries, entry, entry);
+		DEBUG("new GPT partition added");
+	}
+out:
+	free(buf);
+	free(tbl);
+	return (table);
+}
+#endif /* LOADER_GPT_SUPPORT */
+
+#ifdef LOADER_MBR_SUPPORT
+/* We do not need to support too many EBR partitions in the loader */
+#define	MAXEBRENTRIES		8
+static enum partition_type
+mbr_parttype(uint8_t type)
+{
+
+	switch (type) {
+	case DOSPTYP_386BSD:
+		return (PART_FREEBSD);
+	case DOSPTYP_LINSWP:
+		return (PART_LINUX_SWAP);
+	case DOSPTYP_LINUX:
+		return (PART_LINUX);
+	case 0x01:
+	case 0x04:
+	case 0x06:
+	case 0x07:
+	case 0x0b:
+	case 0x0c:
+	case 0x0e:
+		return (PART_DOS);
+	}
+	return (PART_UNKNOWN);
+}
+
+struct ptable*
+ptable_ebrread(struct ptable *table, void *dev, diskread_t dread)
+{
+	struct dos_partition *dp;
+	struct pentry *e1, *entry;
+	uint32_t start, end, offset;
+	u_char *buf;
+	int i, index;
+
+	STAILQ_FOREACH(e1, &table->entries, entry) {
+		if (e1->type.mbr == DOSPTYP_EXT ||
+		    e1->type.mbr == DOSPTYP_EXTLBA)
+			break;
+	}
+	if (e1 == NULL)
+		return (table);
+	index = 5;
+	offset = e1->part.start;
+	buf = malloc(table->sectorsize);
+	if (buf == NULL)
+		return (table);
+	for (i = 0; i < MAXEBRENTRIES; i++) {
+		if (offset >= table->sectors)
+			break;
+		if (dread(dev, buf, 1, offset) != 0)
+			break;
+		dp = (struct dos_partition *)(buf + DOSPARTOFF);
+		if (dp[0].dp_typ == 0)
+			break;
+		start = le32toh(dp[0].dp_start);
+		if (dp[0].dp_typ == DOSPTYP_EXT &&
+		    dp[1].dp_typ == 0) {
+			offset = e1->part.start + start;
+			continue;
+		}
+		end = le32toh(dp[0].dp_size);
+		entry = malloc(sizeof(*entry));
+		if (entry == NULL)
+			break;
+		entry->part.start = e1->part.start + start;
+		entry->part.end = entry->part.start + end - 1;
+		entry->part.index = index++;
+		entry->part.type = mbr_parttype(dp[0].dp_typ);
+		entry->flags = dp[0].dp_flag;
+		entry->type.mbr = dp[0].dp_typ;
+		STAILQ_INSERT_TAIL(&table->entries, entry, entry);
+		DEBUG("new EBR partition added");
+		if (dp[1].dp_typ == 0)
+			break;
+		offset = e1->part.start + le32toh(dp[1].dp_start);
+	}
+	free(buf);
+	return (table);
+}
+#endif /* LOADER_MBR_SUPPORT */
+
+static enum partition_type
+bsd_parttype(uint8_t type)
+{
+
+	switch (type) {
+	case FS_NANDFS:
+		return (PART_FREEBSD_NANDFS);
+	case FS_SWAP:
+		return (PART_FREEBSD_SWAP);
+	case FS_BSDFFS:
+		return (PART_FREEBSD_UFS);
+	case FS_VINUM:
+		return (PART_FREEBSD_VINUM);
+	case FS_ZFS:
+		return (PART_FREEBSD_ZFS);
+	}
+	return (PART_UNKNOWN);
+}
+
+struct ptable*
+ptable_bsdread(struct ptable *table, void *dev, diskread_t dread)
+{
+	struct disklabel *dl;
+	struct partition *part;
+	struct pentry *entry;
+	u_char *buf;
+	uint32_t raw_offset;
+	int i;
+
+	if (table->sectorsize < sizeof(struct disklabel)) {
+		DEBUG("Too small sectorsize");
+		return (table);
+	}
+	buf = malloc(table->sectorsize);
+	if (buf == NULL)
+		return (table);
+	if (dread(dev, buf, 1, 1) != 0) {
+		DEBUG("read failed");
+		ptable_close(table);
+		table = NULL;
+		goto out;
+	}
+	dl = (struct disklabel *)buf;
+	if (le32toh(dl->d_magic) != DISKMAGIC &&
+	    le32toh(dl->d_magic2) != DISKMAGIC)
+		goto out;
+	if (le32toh(dl->d_secsize) != table->sectorsize) {
+		DEBUG("unsupported sector size");
+		goto out;
+	}
+	dl->d_npartitions = le16toh(dl->d_npartitions);
+	if (dl->d_npartitions > 20 || dl->d_npartitions < 8) {
+		DEBUG("invalid number of partitions");
+		goto out;
+	}
+	part = &dl->d_partitions[0];
+	raw_offset = le32toh(part[RAW_PART].p_offset);
+	for (i = 0; i < dl->d_npartitions; i++, part++) {
+		if (i == RAW_PART)
+			continue;
+		if (part->p_size == 0 || part->p_fstype == 0)
+			continue;
+		entry = malloc(sizeof(*entry));
+		if (entry == NULL)
+			break;
+		entry->part.start = le32toh(part->p_offset) - raw_offset;
+		entry->part.end = entry->part.start +
+		    le32toh(part->p_size) + 1;
+		entry->part.type = bsd_parttype(part->p_fstype);
+		entry->part.index = i; /* starts from zero */
+		entry->type.bsd = part->p_fstype;
+		STAILQ_INSERT_TAIL(&table->entries, entry, entry);
+		DEBUG("new BSD partition added");
+	}
+	table->type = PTABLE_BSD;
+out:
+	free(buf);
+	return (table);
+}
+
+#ifdef LOADER_VTOC8_SUPPORT
+static enum partition_type
+vtoc8_parttype(uint16_t type)
+{
+
+	switch (type) {
+	case VTOC_TAG_FREEBSD_NANDFS:
+		return (PART_FREEBSD_NANDFS);
+	case VTOC_TAG_FREEBSD_SWAP:
+		return (PART_FREEBSD_SWAP);
+	case VTOC_TAG_FREEBSD_UFS:
+		return (PART_FREEBSD_UFS);
+	case VTOC_TAG_FREEBSD_VINUM:
+		return (PART_FREEBSD_VINUM);
+	case VTOC_TAG_FREEBSD_ZFS:
+		return (PART_FREEBSD_ZFS);
+	};
+	return (PART_UNKNOWN);
+}
+
+static struct ptable*
+ptable_vtoc8read(struct ptable *table, void *dev, diskread_t dread)
+{
+	struct pentry *entry;
+	struct vtoc8 *dl;
+	u_char *buf;
+	uint16_t sum, heads, sectors;
+	int i;
+
+	if (table->sectorsize != sizeof(struct vtoc8))
+		return (table);
+	buf = malloc(table->sectorsize);
+	if (buf == NULL)
+		return (table);
+	if (dread(dev, buf, 1, 0) != 0) {
+		DEBUG("read failed");
+		ptable_close(table);
+		table = NULL;
+		goto out;
+	}
+	dl = (struct vtoc8 *)buf;
+	/* Check the sum */
+	for (i = sum = 0; i < sizeof(struct vtoc8); i += sizeof(sum))
+		sum ^= be16dec(buf + i);
+	if (sum != 0) {
+		DEBUG("incorrect checksum");
+		goto out;
+	}
+	if (be16toh(dl->nparts) != VTOC8_NPARTS) {
+		DEBUG("invalid number of entries");
+		goto out;
+	}
+	sectors = be16toh(dl->nsecs);
+	heads = be16toh(dl->nheads);
+	if (sectors * heads == 0) {
+		DEBUG("invalid geometry");
+		goto out;
+	}
+	for (i = 0; i < VTOC8_NPARTS; i++) {
+		dl->part[i].tag = be16toh(dl->part[i].tag);
+		if (i == VTOC_RAW_PART ||
+		    dl->part[i].tag == VTOC_TAG_UNASSIGNED)
+			continue;
+		entry = malloc(sizeof(*entry));
+		if (entry == NULL)
+			break;
+		entry->part.start = be32toh(dl->map[i].cyl) * heads * sectors;
+		entry->part.end = be32toh(dl->map[i].nblks) +
+		    entry->part.start - 1;
+		entry->part.type = vtoc8_parttype(dl->part[i].tag);
+		entry->part.index = i; /* starts from zero */
+		entry->type.vtoc8 = dl->part[i].tag;
+		STAILQ_INSERT_TAIL(&table->entries, entry, entry);
+		DEBUG("new VTOC8 partition added");
+	}
+	table->type = PTABLE_VTOC8;
+out:
+	free(buf);
+	return (table);
+
+}
+#endif /* LOADER_VTOC8_SUPPORT */
+
+struct ptable*
+ptable_open(void *dev, off_t sectors, uint16_t sectorsize,
+    diskread_t *dread)
+{
+	struct dos_partition *dp;
+	struct ptable *table;
+	u_char *buf;
+	int i, count;
+#ifdef LOADER_MBR_SUPPORT
+	struct pentry *entry;
+	uint32_t start, end;
+	int has_ext;
+#endif
+	table = NULL;
+	buf = malloc(sectorsize);
+	if (buf == NULL)
+		return (NULL);
+	/* First, read the MBR. */
+	if (dread(dev, buf, 1, DOSBBSECTOR) != 0) {
+		DEBUG("read failed");
+		goto out;
+	}
+
+	table = malloc(sizeof(*table));
+	if (table == NULL)
+		goto out;
+	table->sectors = sectors;
+	table->sectorsize = sectorsize;
+	table->type = PTABLE_NONE;
+	STAILQ_INIT(&table->entries);
+
+#ifdef LOADER_VTOC8_SUPPORT
+	if (be16dec(buf + offsetof(struct vtoc8, magic)) == VTOC_MAGIC) {
+		if (ptable_vtoc8read(table, dev, dread) == NULL) {
+			/* Read error. */
+			table = NULL;
+			goto out;
+		} else if (table->type == PTABLE_VTOC8)
+			goto out;
+	}
+#endif
+	/* Check the BSD label. */
+	if (ptable_bsdread(table, dev, dread) == NULL) { /* Read error. */
+		table = NULL;
+		goto out;
+	} else if (table->type == PTABLE_BSD)
+		goto out;
+
+#if defined(LOADER_GPT_SUPPORT) || defined(LOADER_MBR_SUPPORT)
+	/* Check the MBR magic. */
+	if (buf[DOSMAGICOFFSET] != 0x55 ||
+	    buf[DOSMAGICOFFSET + 1] != 0xaa) {
+		DEBUG("magic sequence not found");
+		goto out;
+	}
+	/* Check that we have PMBR. Also do some validation. */
+	dp = (struct dos_partition *)(buf + DOSPARTOFF);
+	for (i = 0, count = 0; i < NDOSPART; i++) {
+		if (dp[i].dp_flag != 0 && dp[i].dp_flag != 0x80) {
+			DEBUG("invalid partition flag %x", dp[i].dp_flag);
+			break;
+		}
+#ifdef LOADER_GPT_SUPPORT
+		if (dp[i].dp_typ == DOSPTYP_PMBR) {
+			table->type = PTABLE_GPT;
+			DEBUG("PMBR detected");
+		}
+#endif
+		if (dp[i].dp_typ != 0)
+			count++;
+	}
+	/* Do we have some invalid values? */
+	if (i != NDOSPART ||
+	    (table->type == PTABLE_GPT && count > 1)) {
+		table->type = PTABLE_NONE;
+		DEBUG("invalid values detected, ignore partition table");
+		goto out;
+	}
+#ifdef LOADER_GPT_SUPPORT
+	if (table->type == PTABLE_GPT) {
+		table = ptable_gptread(table, dev, dread);
+		goto out;
+	}
+#endif
+#ifdef LOADER_MBR_SUPPORT
+	/* Read MBR. */
+	table->type = PTABLE_MBR;
+	for (i = has_ext = 0; i < NDOSPART; i++) {
+		if (dp[i].dp_typ == 0)
+			continue;
+		start = le32toh(dp[i].dp_start);
+		end = le32toh(dp[i].dp_size);
+		if (start == 0 || end == 0)
+			continue;
+		if (start + end - 1 >= sectors)
+			continue;	/* XXX: ignore */
+		if (dp[i].dp_typ == DOSPTYP_EXT ||
+		    dp[i].dp_typ == DOSPTYP_EXTLBA)
+			has_ext = 1;
+		entry = malloc(sizeof(*entry));
+		if (entry == NULL)
+			break;
+		entry->part.start = start;
+		entry->part.end = start + end - 1;
+		entry->part.index = i + 1;
+		entry->part.type = mbr_parttype(dp[i].dp_typ);
+		entry->flags = dp[i].dp_flag;
+		entry->type.mbr = dp[i].dp_typ;
+		STAILQ_INSERT_TAIL(&table->entries, entry, entry);
+		DEBUG("new MBR partition added");
+	}
+	if (has_ext) {
+		table = ptable_ebrread(table, dev, dread);
+		/* FALLTHROUGH */
+	}
+#endif /* LOADER_MBR_SUPPORT */
+#endif /* LOADER_MBR_SUPPORT || LOADER_GPT_SUPPORT */
+out:
+	free(buf);
+	return (table);
+}
+
+void
+ptable_close(struct ptable *table)
+{
+	struct pentry *entry;
+
+	while (!STAILQ_EMPTY(&table->entries)) {
+		entry = STAILQ_FIRST(&table->entries);
+		STAILQ_REMOVE_HEAD(&table->entries, entry);
+		free(entry);
+	}
+	free(table);
+}
+
+enum ptable_type
+ptable_gettype(const struct ptable *table)
+{
+
+	return (table->type);
+}
+
+int
+ptable_getpart(const struct ptable *table, struct ptable_entry *part, int index)
+{
+	struct pentry *entry;
+
+	if (part == NULL || table == NULL)
+		return (EINVAL);
+
+	STAILQ_FOREACH(entry, &table->entries, entry) {
+		if (entry->part.index != index)
+			continue;
+		memcpy(part, &entry->part, sizeof(*part));
+		return (0);
+	}
+	return (ENOENT);
+}
+
+/*
+ * Search for a slice with the following preferences:
+ *
+ * 1: Active FreeBSD slice
+ * 2: Non-active FreeBSD slice
+ * 3: Active Linux slice
+ * 4: non-active Linux slice
+ * 5: Active FAT/FAT32 slice
+ * 6: non-active FAT/FAT32 slice
+ */
+#define PREF_RAWDISK	0
+#define PREF_FBSD_ACT	1
+#define PREF_FBSD	2
+#define PREF_LINUX_ACT	3
+#define PREF_LINUX	4
+#define PREF_DOS_ACT	5
+#define PREF_DOS	6
+#define PREF_NONE	7
+int
+ptable_getbestpart(const struct ptable *table, struct ptable_entry *part)
+{
+	struct pentry *entry, *best;
+	int pref, preflevel;
+
+	if (part == NULL || table == NULL)
+		return (EINVAL);
+
+	best = NULL;
+	preflevel = pref = PREF_NONE;
+	STAILQ_FOREACH(entry, &table->entries, entry) {
+#ifdef LOADER_MBR_SUPPORT
+		if (table->type == PTABLE_MBR) {
+			switch (entry->type.mbr) {
+			case DOSPTYP_386BSD:
+				pref = entry->flags & 0x80 ? PREF_FBSD_ACT:
+				    PREF_FBSD;
+				break;
+			case DOSPTYP_LINUX:
+				pref = entry->flags & 0x80 ? PREF_LINUX_ACT:
+				    PREF_LINUX;
+				break;
+			case 0x01:		/* DOS/Windows */
+			case 0x04:
+			case 0x06:
+			case 0x0c:
+			case 0x0e:
+			case DOSPTYP_FAT32:
+				pref = entry->flags & 0x80 ? PREF_DOS_ACT:
+				    PREF_DOS;
+				break;
+			default:
+				pref = PREF_NONE;
+			}
+		}
+#endif /* LOADER_MBR_SUPPORT */
+#ifdef LOADER_GPT_SUPPORT
+		if (table->type == PTABLE_GPT) {
+			if (entry->part.type == PART_DOS)
+				pref = PREF_DOS;
+			else if (entry->part.type == PART_FREEBSD_UFS ||
+			    entry->part.type == PART_FREEBSD_ZFS)
+				pref = PREF_FBSD;
+			else
+				pref = PREF_NONE;
+		}
+#endif /* LOADER_GPT_SUPPORT */
+		if (pref < preflevel) {
+			preflevel = pref;
+			best = entry;
+		}
+	}
+	if (best != NULL) {
+		memcpy(part, &best->part, sizeof(*part));
+		return (0);
+	}
+	return (ENOENT);
+}
+
+void
+ptable_iterate(const struct ptable *table, void *arg, ptable_iterate_t *iter)
+{
+	struct pentry *entry;
+	char name[32];
+
+	name[0] = '\0';
+	STAILQ_FOREACH(entry, &table->entries, entry) {
+#ifdef LOADER_MBR_SUPPORT
+		if (table->type == PTABLE_MBR)
+			sprintf(name, "s%d", entry->part.index);
+		else
+#endif
+#ifdef LOADER_GPT_SUPPORT
+		if (table->type == PTABLE_GPT)
+			sprintf(name, "p%d", entry->part.index);
+		else
+#endif
+#ifdef LOADER_VTOC8_SUPPORT
+		if (table->type == PTABLE_VTOC8)
+			sprintf(name, "%c", (u_char) 'a' +
+			    entry->part.index);
+		else
+#endif
+		if (table->type == PTABLE_BSD)
+			sprintf(name, "%c", (u_char) 'a' +
+			    entry->part.index);
+		iter(arg, name, &entry->part);
+	}
+}
+
diff --git a/sys/boot/common/part.h b/sys/boot/common/part.h
new file mode 100644
index 0000000..9f80267
--- /dev/null
+++ b/sys/boot/common/part.h
@@ -0,0 +1,82 @@
+/*-
+ * Copyright (c) 2012 Andrey V. Elsukov <ae@FreeBSD.org>
+ * All rights reserved.
+ *
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHORS 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 AUTHORS 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.
+ *
+ * $FreeBSD$
+ */
+
+#ifndef _PART_H_
+#define	_PART_H_
+
+struct ptable;
+
+enum ptable_type {
+	PTABLE_NONE,
+	PTABLE_BSD,
+	PTABLE_MBR,
+	PTABLE_GPT,
+	PTABLE_VTOC8
+};
+
+enum partition_type {
+	PART_UNKNOWN,
+	PART_EFI,
+	PART_FREEBSD,
+	PART_FREEBSD_BOOT,
+	PART_FREEBSD_NANDFS,
+	PART_FREEBSD_UFS,
+	PART_FREEBSD_ZFS,
+	PART_FREEBSD_SWAP,
+	PART_FREEBSD_VINUM,
+	PART_LINUX,
+	PART_LINUX_SWAP,
+	PART_DOS,
+};
+
+struct ptable_entry {
+	uint64_t		start;
+	uint64_t		end;
+	int			index;
+	enum partition_type	type;
+};
+
+/* The offset and size are in sectors */
+typedef int (diskread_t)(void *arg, void *buf, size_t blocks, off_t offset);
+typedef void (ptable_iterate_t)(void *arg, const char *partname,
+    const struct ptable_entry *part);
+
+struct ptable *ptable_open(void *dev, off_t sectors, uint16_t sectorsize,
+    diskread_t *dread);
+void ptable_close(struct ptable *table);
+enum ptable_type ptable_gettype(const struct ptable *table);
+
+int ptable_getpart(const struct ptable *table, struct ptable_entry *part,
+    int index);
+int ptable_getbestpart(const struct ptable *table, struct ptable_entry *part);
+
+void ptable_iterate(const struct ptable *table, void *arg,
+    ptable_iterate_t *iter);
+const char *parttype2str(enum partition_type type);
+
+#endif	/* !_PART_H_ */