libfdisk: (gpt) move code from fdisk to libfdisk

Signed-off-by: Karel Zak <kzak@redhat.com>

1 files changed, 1819 insertions, 0 deletions

diff --git a/libfdisk/src/gpt.c b/libfdisk/src/gpt.c
new file mode 100644
index 000000000..03fad41ef
--- /dev/null
+++ b/libfdisk/src/gpt.c
@@ -0,0 +1,1819 @@
+/*
+ * Copyright (C) 2007 Karel Zak <kzak@redhat.com>
+ * Copyright (C) 2012 Davidlohr Bueso <dave@gnu.org>
+ *
+ * GUID Partition Table (GPT) support. Based on UEFI Specs 2.3.1
+ * Chapter 5: GUID Partition Table (GPT) Disk Layout (Jun 27th, 2012).
+ * Some ideas and inspiration from GNU parted and gptfdisk.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <inttypes.h>
+#include <sys/stat.h>
+#include <sys/utsname.h>
+#include <sys/types.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+#include <ctype.h>
+#include <uuid.h>
+
+#include "fdiskP.h"
+
+#include "nls.h"
+#include "xalloc.h"
+#include "crc32.h"
+#include "blkdev.h"
+#include "bitops.h"
+#include "strutils.h"
+#include "all-io.h"
+
+/* temporary -- exported from fdisk/sfdisk.c
+ * TODO: use fdisk_dialog API
+ */
+extern unsigned int read_int(struct fdisk_context *cxt,
+			unsigned int low, unsigned int dflt,
+			unsigned int high, unsigned int base, char *mesg);
+
+extern unsigned int read_int_with_suffix(struct fdisk_context *cxt,
+			unsigned int low, unsigned int dflt, unsigned int high,
+			unsigned int base, char *mesg, int *is_suffix_used);
+
+#define GPT_HEADER_SIGNATURE 0x5452415020494645LL /* EFI PART */
+#define GPT_HEADER_REVISION_V1_02 0x00010200
+#define GPT_HEADER_REVISION_V1_00 0x00010000
+#define GPT_HEADER_REVISION_V0_99 0x00009900
+#define GPT_HEADER_MINSZ          92 /* bytes */
+
+#define GPT_PMBR_LBA        0
+#define GPT_MBR_PROTECTIVE  1
+#define GPT_MBR_HYBRID      2
+
+#define GPT_PRIMARY_PARTITION_TABLE_LBA 0x00000001
+
+#define EFI_PMBR_OSTYPE     0xEE
+#define MSDOS_MBR_SIGNATURE 0xAA55
+#define GPT_PART_NAME_LEN   72 / sizeof(uint16_t)
+#define GPT_NPARTITIONS     128
+
+/* Globally unique identifier */
+struct gpt_guid {
+	uint32_t   time_low;
+	uint16_t   time_mid;
+	uint16_t   time_hi_and_version;
+	uint8_t    clock_seq_hi;
+	uint8_t    clock_seq_low;
+	uint8_t    node[6];
+};
+
+
+/* only checking that the GUID is 0 is enough to verify an empty partition. */
+#define GPT_UNUSED_ENTRY_GUID						\
+	((struct gpt_guid) { 0x00000000, 0x0000, 0x0000, 0x00, 0x00,	\
+			     { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }})
+
+/* Linux native partition type */
+#define GPT_DEFAULT_ENTRY_GUID						\
+	((struct gpt_guid) { 0x0FC63DAF, 0x8483, 0x4772, 0x8E, 0x79,	\
+			     { 0x3D, 0x69, 0xD8, 0x47, 0x7D, 0xE4 }})
+
+
+/*
+ * Attribute bits
+ */
+struct gpt_attr {
+	uint64_t            required_to_function:1;
+	uint64_t            no_blockio_protocol:1;
+	uint64_t            legacy_bios_bootable:1;
+	uint64_t            reserved:45;
+	uint64_t            guid_secific:16;
+}  __attribute__ ((packed));
+
+/* The GPT Partition entry array contains an array of GPT entries. */
+struct gpt_entry {
+	struct gpt_guid     partition_type_guid; /* purpose and type of the partition */
+	struct gpt_guid     unique_partition_guid;
+	uint64_t            lba_start;
+	uint64_t            lba_end;
+	struct gpt_attr     attr;
+	uint16_t            partition_name[GPT_PART_NAME_LEN];
+}  __attribute__ ((packed));
+
+/* GPT header */
+struct gpt_header {
+	uint64_t            signature; /* header identification */
+	uint32_t            revision; /* header version */
+	uint32_t            size; /* in bytes */
+	uint32_t            crc32; /* header CRC checksum */
+	uint32_t            reserved1; /* must be 0 */
+	uint64_t            my_lba; /* LBA that contains this struct (LBA 1) */
+	uint64_t            alternative_lba; /* backup GPT header */
+	uint64_t            first_usable_lba; /* first usable logical block for partitions */
+	uint64_t            last_usable_lba; /* last usable logical block for partitions */
+	struct gpt_guid     disk_guid; /* unique disk identifier */
+	uint64_t            partition_entry_lba; /* stat LBA of the partition entry array */
+	uint32_t            npartition_entries; /* total partition entries - normally 128 */
+	uint32_t            sizeof_partition_entry; /* bytes for each GUID pt */
+	uint32_t            partition_entry_array_crc32; /* partition CRC checksum */
+	uint8_t             reserved2[512 - 92]; /* must be 0 */
+} __attribute__ ((packed));
+
+struct gpt_record {
+	uint8_t             boot_indicator; /* unused by EFI, set to 0x80 for bootable */
+	uint8_t             start_head; /* unused by EFI, pt start in CHS */
+	uint8_t             start_sector; /* unused by EFI, pt start in CHS */
+	uint8_t             start_track;
+	uint8_t             os_type; /* EFI and legacy non-EFI OS types */
+	uint8_t             end_head; /* unused by EFI, pt end in CHS */
+	uint8_t             end_sector; /* unused by EFI, pt end in CHS */
+	uint8_t             end_track; /* unused by EFI, pt end in CHS */
+	uint32_t            starting_lba; /* used by EFI - start addr of the on disk pt */
+	uint32_t            size_in_lba; /* used by EFI - size of pt in LBA */
+} __attribute__ ((packed));
+
+/* Protected MBR and legacy MBR share same structure */
+struct gpt_legacy_mbr {
+	uint8_t             boot_code[440];
+	uint32_t            unique_mbr_signature;
+	uint16_t            unknown;
+	struct gpt_record   partition_record[4];
+	uint16_t            signature;
+} __attribute__ ((packed));
+
+/*
+ * Here be dragons!
+ * See: http://en.wikipedia.org/wiki/GUID_Partition_Table#Partition_type_GUIDs
+ */
+#define DEF_GUID(_u, _n) \
+	{ \
+		.typestr = (_u), \
+		.name = (_n),    \
+	}
+
+static struct fdisk_parttype gpt_parttypes[] =
+{
+	/* Generic OS */
+	DEF_GUID("C12A7328-F81F-11D2-BA4B-00A0C93EC93B", N_("EFI System")),
+
+	DEF_GUID("024DEE41-33E7-11D3-9D69-0008C781F39F", N_("MBR partition scheme")),
+	/* Hah!IdontneedEFI */
+	DEF_GUID("21686148-6449-6E6F-744E-656564454649", N_("BIOS boot partition")),
+
+	/* Windows */
+	DEF_GUID("E3C9E316-0B5C-4DB8-817D-F92DF00215AE", N_("Microsoft reserved")),
+	DEF_GUID("EBD0A0A2-B9E5-4433-87C0-68B6B72699C7", N_("Microsoft basic data")),
+	DEF_GUID("5808C8AA-7E8F-42E0-85D2-E1E90434CFB3", N_("Microsoft LDM metadata")),
+	DEF_GUID("AF9B60A0-1431-4F62-BC68-3311714A69AD", N_("Microsoft LDM data")),
+	DEF_GUID("DE94BBA4-06D1-4D40-A16A-BFD50179D6AC", N_("Windows recovery evironmnet")),
+	DEF_GUID("37AFFC90-EF7D-4E96-91C3-2D7AE055B174", N_("IBM General Parallel Fs")),
+
+	/* HP-UX */
+	DEF_GUID("75894C1E-3AEB-11D3-B7C1-7B03A0000000", N_("HP-UX data partition")),
+	DEF_GUID("E2A1E728-32E3-11D6-A682-7B03A0000000", N_("HP-UX service partition")),
+
+	/* Linux */
+	DEF_GUID("0FC63DAF-8483-4772-8E79-3D69D8477DE4", N_("Linux filesystem")),
+	DEF_GUID("A19D880F-05FC-4D3B-A006-743F0F84911E", N_("Linux RAID")),
+	DEF_GUID("0657FD6D-A4AB-43C4-84E5-0933C84B4F4F", N_("Linux swap")),
+	DEF_GUID("E6D6D379-F507-44C2-A23C-238F2A3DF928", N_("Linux LVM")),
+	DEF_GUID("8DA63339-0007-60C0-C436-083AC8230908", N_("Linux reserved")),
+
+	/* FreeBSD */
+	DEF_GUID("516E7CB4-6ECF-11D6-8FF8-00022D09712B", N_("FreeBSD data")),
+	DEF_GUID("83BD6B9D-7F41-11DC-BE0B-001560B84F0F", N_("FreeBSD boot")),
+	DEF_GUID("516E7CB5-6ECF-11D6-8FF8-00022D09712B", N_("FreeBSD swap")),
+	DEF_GUID("516E7CB6-6ECF-11D6-8FF8-00022D09712B", N_("FreeBSD UFS")),
+	DEF_GUID("516E7CBA-6ECF-11D6-8FF8-00022D09712B", N_("FreeBSD ZFS")),
+	DEF_GUID("516E7CB8-6ECF-11D6-8FF8-00022D09712B", N_("FreeBSD Vinum")),
+
+	/* Apple OSX */
+	DEF_GUID("48465300-0000-11AA-AA11-00306543ECAC", N_("Apple HFS/HFS+")),
+	DEF_GUID("55465300-0000-11AA-AA11-00306543ECAC", N_("Apple UFS")),
+	DEF_GUID("52414944-0000-11AA-AA11-00306543ECAC", N_("Apple RAID")),
+	DEF_GUID("52414944-5F4F-11AA-AA11-00306543ECAC", N_("Apple RAID offline")),
+	DEF_GUID("426F6F74-0000-11AA-AA11-00306543ECAC", N_("Apple boot")),
+	DEF_GUID("4C616265-6C00-11AA-AA11-00306543ECAC", N_("Apple label")),
+	DEF_GUID("5265636F-7665-11AA-AA11-00306543ECAC", N_("Apple TV recovery")),
+	DEF_GUID("53746F72-6167-11AA-AA11-00306543ECAC", N_("Apple Core storage")),
+
+	/* Solaris */
+	DEF_GUID("6A82CB45-1DD2-11B2-99A6-080020736631", N_("Solaris boot")),
+	DEF_GUID("6A85CF4D-1DD2-11B2-99A6-080020736631", N_("Solaris root")),
+	/* same as Apple ZFS */
+	DEF_GUID("6A898CC3-1DD2-11B2-99A6-080020736631", N_("Solaris /usr & Apple ZFS")),
+	DEF_GUID("6A87C46F-1DD2-11B2-99A6-080020736631", N_("Solaris swap")),
+	DEF_GUID("6A8B642B-1DD2-11B2-99A6-080020736631", N_("Solaris backup")),
+	DEF_GUID("6A8EF2E9-1DD2-11B2-99A6-080020736631", N_("Solaris /var")),
+	DEF_GUID("6A90BA39-1DD2-11B2-99A6-080020736631", N_("Solaris /home")),
+	DEF_GUID("6A9283A5-1DD2-11B2-99A6-080020736631", N_("Solaris alternate sector")),
+	DEF_GUID("6A945A3B-1DD2-11B2-99A6-080020736631", N_("Solaris reserved 1")),
+	DEF_GUID("6A9630D1-1DD2-11B2-99A6-080020736631", N_("Solaris reserved 2")),
+	DEF_GUID("6A980767-1DD2-11B2-99A6-080020736631", N_("Solaris reserved 3")),
+	DEF_GUID("6A96237F-1DD2-11B2-99A6-080020736631", N_("Solaris reserved 4")),
+	DEF_GUID("6A8D2AC7-1DD2-11B2-99A6-080020736631", N_("Solaris reserved 5")),
+
+	/* NetBSD */
+	DEF_GUID("49F48D32-B10E-11DC-B99B-0019D1879648", N_("NetBSD swap")),
+	DEF_GUID("49F48D5A-B10E-11DC-B99B-0019D1879648", N_("NetBSD FFS")),
+	DEF_GUID("49F48D82-B10E-11DC-B99B-0019D1879648", N_("NetBSD LFS")),
+	DEF_GUID("2DB519C4-B10E-11DC-B99B-0019D1879648", N_("NetBSD concatenated")),
+	DEF_GUID("2DB519EC-B10E-11DC-B99B-0019D1879648", N_("NetBSD encrypted")),
+	DEF_GUID("49F48DAA-B10E-11DC-B99B-0019D1879648", N_("NetBSD RAID")),
+
+	/* ChromeOS */
+	DEF_GUID("FE3A2A5D-4F32-41A7-B725-ACCC3285A309", N_("ChromeOS kernel")),
+	DEF_GUID("3CB8E202-3B7E-47DD-8A3C-7FF2A13CFCEC", N_("ChromeOS root fs")),
+	DEF_GUID("2E0A753D-9E48-43B0-8337-B15192CB1B5E", N_("ChromeOS reserved")),
+
+	/* MidnightBSD */
+	DEF_GUID("85D5E45A-237C-11E1-B4B3-E89A8F7FC3A7", N_("MidnightBSD data")),
+	DEF_GUID("85D5E45E-237C-11E1-B4B3-E89A8F7FC3A7", N_("MidnightBSD boot")),
+	DEF_GUID("85D5E45B-237C-11E1-B4B3-E89A8F7FC3A7", N_("MidnightBSD swap")),
+	DEF_GUID("0394Ef8B-237C-11E1-B4B3-E89A8F7FC3A7", N_("MidnightBSD UFS")),
+	DEF_GUID("85D5E45D-237C-11E1-B4B3-E89A8F7FC3A7", N_("MidnightBSD ZFS")),
+	DEF_GUID("85D5E45C-237C-11E1-B4B3-E89A8F7FC3A7", N_("MidnightBSD Vinum")),
+};
+
+/* gpt_entry macros */
+#define gpt_partition_start(_e)		le64_to_cpu((_e)->lba_start)
+#define gpt_partition_end(_e)		le64_to_cpu((_e)->lba_end)
+
+/*
+ * in-memory fdisk GPT stuff
+ */
+struct fdisk_gpt_label {
+	struct fdisk_label	head;		/* generic part */
+
+	/* gpt specific part */
+	struct gpt_header	*pheader;	/* primary header */
+	struct gpt_header	*bheader;	/* backup header */
+	struct gpt_entry	*ents;		/* entries (partitions) */
+};
+
+static void gpt_deinit(struct fdisk_label *lb);
+
+static inline struct fdisk_gpt_label *gpt_label(struct fdisk_context *cxt)
+{
+	assert(cxt);
+	assert(cxt->label);
+	assert(fdisk_is_disklabel(cxt, GPT));
+
+	return (struct fdisk_gpt_label *) cxt->label;
+}
+
+/*
+ * Returns the partition length, or 0 if end is before beginning.
+ */
+static uint64_t gpt_partition_size(const struct gpt_entry *e)
+{
+	uint64_t start = gpt_partition_start(e);
+	uint64_t end = gpt_partition_end(e);
+
+	return start > end ? 0 : end - start + 1ULL;
+}
+
+/*
+ * UUID is traditionally 16 byte big-endian array, except Intel EFI
+ * specification where the UUID is a structure of little-endian fields.
+ */
+static void swap_efi_guid(struct gpt_guid *uid)
+{
+	uid->time_low = swab32(uid->time_low);
+	uid->time_mid = swab16(uid->time_mid);
+	uid->time_hi_and_version = swab16(uid->time_hi_and_version);
+}
+
+static int string_to_uuid(const char *in, struct gpt_guid *uuid)
+{
+	if (uuid_parse(in, (unsigned char *) uuid))
+		return -1;
+
+	swap_efi_guid(uuid);
+	return 0;
+}
+
+static void uuid_to_string(struct gpt_guid *uuid, char *out)
+{
+	uuid_unparse_upper((unsigned char *) uuid, out);
+}
+
+static const char *gpt_get_header_revstr(struct gpt_header *header)
+{
+	if (!header)
+		goto unknown;
+
+	switch (header->revision) {
+	case GPT_HEADER_REVISION_V1_02:
+		return "1.2";
+	case GPT_HEADER_REVISION_V1_00:
+		return "1.0";
+	case GPT_HEADER_REVISION_V0_99:
+		return "0.99";
+	default:
+		goto unknown;
+	}
+
+unknown:
+	return "unknown";
+}
+
+static inline int partition_unused(const struct gpt_entry *e)
+{
+	return !memcmp(&e->partition_type_guid, &GPT_UNUSED_ENTRY_GUID,
+			sizeof(struct gpt_guid));
+}
+
+/*
+ * Builds a clean new valid protective MBR - will wipe out any existing data.
+ * Returns 0 on success, otherwise < 0 on error.
+ */
+static int gpt_mknew_pmbr(struct fdisk_context *cxt)
+{
+	struct gpt_legacy_mbr *pmbr = NULL;
+
+	if (!cxt || !cxt->firstsector)
+		return -ENOSYS;
+
+	fdisk_zeroize_firstsector(cxt);
+
+	pmbr = (struct gpt_legacy_mbr *) cxt->firstsector;
+
+	pmbr->signature = cpu_to_le16(MSDOS_MBR_SIGNATURE);
+	pmbr->partition_record[0].os_type      = EFI_PMBR_OSTYPE;
+	pmbr->partition_record[0].start_sector = 1;
+	pmbr->partition_record[0].end_head     = 0xFE;
+	pmbr->partition_record[0].end_sector   = 0xFF;
+	pmbr->partition_record[0].end_track    = 0xFF;
+	pmbr->partition_record[0].starting_lba = cpu_to_le32(1);
+	pmbr->partition_record[0].size_in_lba  =
+		cpu_to_le32(min((uint32_t) cxt->total_sectors - 1, 0xFFFFFFFF));
+
+	return 0;
+}
+
+/* some universal differences between the headers */
+static void gpt_mknew_header_common(struct fdisk_context *cxt,
+				    struct gpt_header *header, uint64_t lba)
+{
+	if (!cxt || !header)
+		return;
+
+	header->my_lba = cpu_to_le64(lba);
+
+	if (lba == GPT_PRIMARY_PARTITION_TABLE_LBA) { /* primary */
+		header->alternative_lba = cpu_to_le64(cxt->total_sectors - 1);
+		header->partition_entry_lba = cpu_to_le64(2);
+	} else { /* backup */
+		uint64_t esz = le32_to_cpu(header->npartition_entries) * sizeof(struct gpt_entry);
+		uint64_t esects = (esz + cxt->sector_size - 1) / cxt->sector_size;
+
+		header->alternative_lba = cpu_to_le64(GPT_PRIMARY_PARTITION_TABLE_LBA);
+		header->partition_entry_lba = cpu_to_le64(cxt->total_sectors - 1 - esects);
+	}
+}
+
+/*
+ * Builds a new GPT header (at sector lba) from a backup header2.
+ * If building a primary header, then backup is the secondary, and vice versa.
+ *
+ * Always pass a new (zeroized) header to build upon as we don't
+ * explicitly zero-set some values such as CRCs and reserved.
+ *
+ * Returns 0 on success, otherwise < 0 on error.
+ */
+static int gpt_mknew_header_from_bkp(struct fdisk_context *cxt,
+				     struct gpt_header *header,
+				     uint64_t lba,
+				     struct gpt_header *header2)
+{
+	if (!cxt || !header || !header2)
+		return -ENOSYS;
+
+	header->signature              = header2->signature;
+	header->revision               = header2->revision;
+	header->size                   = header2->size;
+	header->npartition_entries     = header2->npartition_entries;
+	header->sizeof_partition_entry = header2->sizeof_partition_entry;
+	header->first_usable_lba       = header2->first_usable_lba;
+	header->last_usable_lba        = header2->last_usable_lba;
+
+	memcpy(&header->disk_guid,
+	       &header2->disk_guid, sizeof(header2->disk_guid));
+	gpt_mknew_header_common(cxt, header, lba);
+
+	return 0;
+}
+
+/*
+ * Builds a clean new GPT header (currently under revision 1.0).
+ *
+ * Always pass a new (zeroized) header to build upon as we don't
+ * explicitly zero-set some values such as CRCs and reserved.
+ *
+ * Returns 0 on success, otherwise < 0 on error.
+ */
+static int gpt_mknew_header(struct fdisk_context *cxt,
+			    struct gpt_header *header, uint64_t lba)
+{
+	uint64_t esz = 0, first, last;
+
+	if (!cxt || !header)
+		return -ENOSYS;
+
+	esz = sizeof(struct gpt_entry) * GPT_NPARTITIONS / cxt->sector_size;
+
+	header->signature = cpu_to_le64(GPT_HEADER_SIGNATURE);
+	header->revision  = cpu_to_le32(GPT_HEADER_REVISION_V1_00);
+	header->size      = cpu_to_le32(sizeof(struct gpt_header));
+
+	/*
+	 * 128 partitions is the default. It can go behond this, however,
+	 * we're creating a de facto header here, so no funny business.
+	 */
+	header->npartition_entries     = cpu_to_le32(GPT_NPARTITIONS);
+	header->sizeof_partition_entry = cpu_to_le32(sizeof(struct gpt_entry));
+
+	last = cxt->total_sectors - 2 - esz;
+	first = esz + 2;
+
+	if (first < cxt->first_lba && cxt->first_lba < last)
+		/* Align according to topology */
+		first = cxt->first_lba;
+
+	header->first_usable_lba = cpu_to_le64(first);
+	header->last_usable_lba  = cpu_to_le64(last);
+
+	gpt_mknew_header_common(cxt, header, lba);
+	uuid_generate_random((unsigned char *) &header->disk_guid);
+	swap_efi_guid(&header->disk_guid);
+
+	return 0;
+}
+
+/*
+ * Checks if there is a valid protective MBR partition table.
+ * Returns 0 if it is invalid or failure. Otherwise, return
+ * GPT_MBR_PROTECTIVE or GPT_MBR_HYBRID, depeding on the detection.
+ */
+static int valid_pmbr(struct fdisk_context *cxt)
+{
+	int i, ret = 0; /* invalid by default */
+	struct gpt_legacy_mbr *pmbr = NULL;
+
+	if (!cxt->firstsector)
+		goto done;
+
+	pmbr = (struct gpt_legacy_mbr *) cxt->firstsector;
+
+	if (pmbr->signature != cpu_to_le64(MSDOS_MBR_SIGNATURE))
+		goto done;
+
+	/* LBA of the GPT partition header */
+	if (pmbr->partition_record[0].starting_lba !=
+	    cpu_to_le32(GPT_PRIMARY_PARTITION_TABLE_LBA))
+		goto done;
+
+	/* seems like a valid MBR was found, check DOS primary partitions */
+	for (i = 0; i < 4; i++)
+		if (pmbr->partition_record[i].os_type == EFI_PMBR_OSTYPE) {
+			/*
+			 * Ok, we at least know that there's a protective MBR,
+			 * now check if there are other partition types for
+			 * hybrid MBR.
+			 */
+			ret = GPT_MBR_PROTECTIVE;
+			goto check_hybrid;
+		}
+
+check_hybrid:
+	if (ret != GPT_MBR_PROTECTIVE)
+		goto done;
+	for (i = 0 ; i < 4; i++)
+		if ((pmbr->partition_record[i].os_type != EFI_PMBR_OSTYPE) &&
+		    (pmbr->partition_record[i].os_type != 0x00))
+			ret = GPT_MBR_HYBRID;
+
+	/*
+	 * Protective MBRs take up the lesser of the whole disk
+	 * or 2 TiB (32bit LBA), ignoring the rest of the disk.
+	 *
+	 * Hybrid MBRs do not necessarily comply with this.
+	 */
+	if (ret == GPT_MBR_PROTECTIVE)
+		if (pmbr->partition_record[0].size_in_lba !=
+		    cpu_to_le32(min((uint32_t) cxt->total_sectors - 1, 0xFFFFFFFF)))
+			ret = 0;
+done:
+	return ret;
+}
+
+static uint64_t last_lba(struct fdisk_context *cxt)
+{
+	struct stat s;
+
+	memset(&s, 0, sizeof(s));
+	if (fstat(cxt->dev_fd, &s) == -1) {
+		fprintf(stderr, "last_lba() could not stat: %m\n");
+		return 0;
+	}
+
+	if (S_ISBLK(s.st_mode))
+		return cxt->total_sectors - 1;
+	else if (S_ISREG(s.st_mode)) {
+		uint64_t sectors = s.st_size >> cxt->sector_size;
+		return (sectors / cxt->sector_size) - 1ULL;
+	} else {
+		fprintf(stderr,
+			"last_lba(): I don't know how to handle files with mode %o\n",
+			s.st_mode);
+	}
+	return 0;
+}
+
+static ssize_t read_lba(struct fdisk_context *cxt, uint64_t lba,
+			void *buffer, const size_t bytes)
+{
+	off_t offset = lba * cxt->sector_size;
+
+	lseek(cxt->dev_fd, offset, SEEK_SET);
+	return read(cxt->dev_fd, buffer, bytes);
+}
+
+
+/* Returns the GPT entry array */
+static struct gpt_entry *gpt_read_entries(struct fdisk_context *cxt,
+					 struct gpt_header *header)
+{
+	ssize_t sz;
+	struct gpt_entry *ret = NULL;
+	off_t offset;
+
+	assert(cxt);
+	assert(header);
+
+	sz = le32_to_cpu(header->npartition_entries) *
+	     le32_to_cpu(header->sizeof_partition_entry);
+
+	ret = calloc(1, sizeof(*ret) * sz);
+	if (!ret)
+		return NULL;
+	offset = le64_to_cpu(header->partition_entry_lba) *
+		       cxt->sector_size;
+
+	if (offset != lseek(cxt->dev_fd, offset, SEEK_SET))
+		goto fail;
+	if (sz != read(cxt->dev_fd, ret, sz))
+		goto fail;
+
+	return ret;
+
+fail:
+	free(ret);
+	return NULL;
+}
+
+static inline uint32_t count_crc32(const unsigned char *buf, size_t len)
+{
+	return (crc32(~0L, buf, len) ^ ~0L);
+}
+
+/*
+ * Recompute header and partition array 32bit CRC checksums.
+ * This function does not fail - if there's corruption, then it
+ * will be reported when checksuming it again (ie: probing or verify).
+ */
+static void gpt_recompute_crc(struct gpt_header *header, struct gpt_entry *ents)
+{
+	uint32_t crc = 0;
+	size_t entry_sz = 0;
+
+	if (!header)
+		return;
+
+	/* header CRC */
+	header->crc32 = 0;
+	crc = count_crc32((unsigned char *) header, le32_to_cpu(header->size));
+	header->crc32 = cpu_to_le32(crc);
+
+	/* partition entry array CRC */
+	header->partition_entry_array_crc32 = 0;
+	entry_sz = le32_to_cpu(header->npartition_entries) *
+		le32_to_cpu(header->sizeof_partition_entry);
+
+	crc = count_crc32((unsigned char *) ents, entry_sz);
+	header->partition_entry_array_crc32 = cpu_to_le32(crc);
+}
+
+/*
+ * Compute the 32bit CRC checksum of the partition table header.
+ * Returns 1 if it is valid, otherwise 0.
+ */
+static int gpt_check_header_crc(struct gpt_header *header, struct gpt_entry *ents)
+{
+	uint32_t crc, orgcrc = le32_to_cpu(header->crc32);
+
+	header->crc32 = 0;
+	crc = count_crc32((unsigned char *) header, le32_to_cpu(header->size));
+	header->crc32 = cpu_to_le32(orgcrc);
+
+	if (crc == le32_to_cpu(header->crc32))
+		return 1;
+
+	/*
+	 * If we have checksum mismatch it may be due to stale data,
+	 * like a partition being added or deleted. Recompute the CRC again
+	 * and make sure this is not the case.
+	 */
+	if (ents) {
+		gpt_recompute_crc(header, ents);
+		orgcrc = le32_to_cpu(header->crc32);
+		header->crc32 = 0;
+		crc = count_crc32((unsigned char *) header, le32_to_cpu(header->size));
+		header->crc32 = cpu_to_le32(orgcrc);
+
+		return crc == le32_to_cpu(header->crc32);
+	}
+
+	return 0;
+}
+
+/*
+ * It initializes the partition entry array.
+ * Returns 1 if the checksum is valid, otherwise 0.
+ */
+static int gpt_check_entryarr_crc(struct gpt_header *header,
+				  struct gpt_entry *ents)
+{
+	int ret = 0;
+	ssize_t entry_sz;
+	uint32_t crc;
+
+	if (!header || !ents)
+		goto done;
+
+	entry_sz = le32_to_cpu(header->npartition_entries) *
+		   le32_to_cpu(header->sizeof_partition_entry);
+
+	if (!entry_sz)
+		goto done;
+
+	crc = count_crc32((unsigned char *) ents, entry_sz);
+	ret = (crc == le32_to_cpu(header->partition_entry_array_crc32));
+done:
+	return ret;
+}
+
+static int gpt_check_lba_sanity(struct fdisk_context *cxt, struct gpt_header *header)
+{
+	int ret = 0;
+	uint64_t lu, fu, lastlba = last_lba(cxt);
+
+	fu = le64_to_cpu(header->first_usable_lba);
+	lu = le64_to_cpu(header->last_usable_lba);
+
+	/* check if first and last usable LBA make sense */
+	if (lu < fu) {
+		DBG(LABEL, dbgprint("error: header last LBA is before first LBA"));
+		goto done;
+	}
+
+	/* check if first and last usable LBAs with the disk's last LBA */
+	if (fu > lastlba || lu > lastlba) {
+		DBG(LABEL, dbgprint("error: header LBAs are after the disk's last LBA"));
+		goto done;
+	}
+
+	/* the header has to be outside usable range */
+	if (fu < GPT_PRIMARY_PARTITION_TABLE_LBA &&
+	    GPT_PRIMARY_PARTITION_TABLE_LBA < lu) {
+		DBG(LABEL, dbgprint("error: header outside of usable range"));
+		goto done;
+	}
+
+	ret = 1; /* sane */
+done:
+	return ret;
+}
+
+/* Check if there is a valid header signature */
+static int gpt_check_signature(struct gpt_header *header)
+{
+	return header->signature == cpu_to_le64(GPT_HEADER_SIGNATURE);
+}
+
+/*
+ * Return the specified GPT Header, or NULL upon failure/invalid.
+ * Note that all tests must pass to ensure a valid header,
+ * we do not rely on only testing the signature for a valid probe.
+ */
+static struct gpt_header *gpt_read_header(struct fdisk_context *cxt,
+					  uint64_t lba,
+					  struct gpt_entry **_ents)
+{
+	struct gpt_header *header = NULL;
+	struct gpt_entry *ents = NULL;
+	uint32_t hsz;
+
+	if (!cxt)
+		return NULL;
+
+	header = xcalloc(1, sizeof(*header));
+
+	/* read and verify header */
+	if (!read_lba(cxt, lba, header, sizeof(struct gpt_header)))
+		goto invalid;
+
+	if (!gpt_check_signature(header))
+		goto invalid;
+
+	if (!gpt_check_header_crc(header, NULL))
+		goto invalid;
+
+	/* read and verify entries */
+	ents = gpt_read_entries(cxt, header);
+	if (!ents)
+		goto invalid;
+
+	if (!gpt_check_entryarr_crc(header, ents))
+		goto invalid;
+
+	if (!gpt_check_lba_sanity(cxt, header))
+		goto invalid;
+
+	/* valid header must be at MyLBA */
+	if (le64_to_cpu(header->my_lba) != lba)
+		goto invalid;
+
+	/* make sure header size is between 92 and sector size bytes */
+	hsz = le32_to_cpu(header->size);
+	if (hsz < GPT_HEADER_MINSZ || hsz > cxt->sector_size)
+		goto invalid;
+
+	if (_ents)
+		*_ents = ents;
+	else
+		free(ents);
+
+	return header;
+invalid:
+	free(header);
+	free(ents);
+	return NULL;
+}
+
+/*
+ * Returns the number of partitions that are in use.
+ */
+static unsigned partitions_in_use(struct gpt_header *header, struct gpt_entry *e)
+{
+	uint32_t i, used = 0;
+
+	if (!header || ! e)
+		return 0;
+
+	for (i = 0; i < le32_to_cpu(header->npartition_entries); i++)
+		if (!partition_unused(&e[i]))
+			used++;
+	return used;
+}
+
+
+/*
+ * Check if a partition is too big for the disk (sectors).
+ * Returns the faulting partition number, otherwise 0.
+ */
+static unsigned partition_check_too_big(struct gpt_header *header,
+				   struct gpt_entry *e, uint64_t sectors)
+{
+	uint32_t i;
+
+	for (i = 0; i < le32_to_cpu(header->npartition_entries); i++) {
+		if (partition_unused(&e[i]))
+			continue;
+		if (gpt_partition_end(&e[i]) >= sectors)
+			return i + 1;
+	}
+
+	return 0;
+}
+
+/*
+ * Check if a partition ends before it begins
+ * Returns the faulting partition number, otherwise 0.
+ */
+static unsigned partition_start_after_end(struct gpt_header *header, struct gpt_entry *e)
+{
+	uint32_t i;
+
+	for (i = 0; i < le32_to_cpu(header->npartition_entries); i++) {
+		if (partition_unused(&e[i]))
+			continue;
+		if (gpt_partition_start(&e[i]) > gpt_partition_end(&e[i]))
+			return i + 1;
+	}
+
+	return 0;
+}
+
+/*
+ * Check if partition e1 overlaps with partition e2
+ */
+static inline int partition_overlap(struct gpt_entry *e1, struct gpt_entry *e2)
+{
+	uint64_t start1 = gpt_partition_start(e1);
+	uint64_t end1   = gpt_partition_end(e1);
+	uint64_t start2 = gpt_partition_start(e2);
+	uint64_t end2   = gpt_partition_end(e2);
+
+	return (start1 && start2 && (start1 <= end2) != (end1 < start2));
+}
+
+/*
+ * Find any paritions that overlap.
+ */
+static unsigned partition_check_overlaps(struct gpt_header *header, struct gpt_entry *e)
+{
+	uint32_t i, j;
+
+	for (i = 0; i < le32_to_cpu(header->npartition_entries); i++)
+		for (j = 0; j < i; j++) {
+			if (partition_unused(&e[i]) ||
+			    partition_unused(&e[j]))
+				continue;
+			if (partition_overlap(&e[i], &e[j]))
+				/* two overlaping partitions is enough! */
+				return i + 1;
+		}
+
+	return 0;
+}
+
+/*
+ * Find the first available block after the starting point; returns 0 if
+ * there are no available blocks left, or error. From gdisk.
+ */
+static uint64_t find_first_available(struct gpt_header *header,
+				     struct gpt_entry *e, uint64_t start)
+{
+	uint64_t first;
+	uint32_t i, first_moved = 0;
+
+	uint64_t fu, lu;
+
+	if (!header || !e)
+		return 0;
+
+	fu = le64_to_cpu(header->first_usable_lba);
+	lu = le64_to_cpu(header->last_usable_lba);
+
+	/*
+	 * Begin from the specified starting point or from the first usable
+	 * LBA, whichever is greater...
+	 */
+	first = start < fu ? fu : start;
+
+	/*
+	 * Now search through all partitions; if first is within an
+	 * existing partition, move it to the next sector after that
+	 * partition and repeat. If first was moved, set firstMoved
+	 * flag; repeat until firstMoved is not set, so as to catch
+	 * cases where partitions are out of sequential order....
+	 */
+	do {
+		first_moved = 0;
+		for (i = 0; i < le32_to_cpu(header->npartition_entries); i++) {
+			if (partition_unused(&e[i]))
+				continue;
+			if (first < gpt_partition_start(&e[i]))
+				continue;
+			if (first <= gpt_partition_end(&e[i])) {
+				first = gpt_partition_end(&e[i]) + 1;
+				first_moved = 1;
+			}
+		}
+	} while (first_moved == 1);
+
+	if (first > lu)
+		first = 0;
+
+	return first;
+}
+
+
+/* Returns last available sector in the free space pointed to by start. From gdisk. */
+static uint64_t find_last_free(struct gpt_header *header,
+			       struct gpt_entry *e, uint64_t start)
+{
+	uint32_t i;
+	uint64_t nearest_start;
+
+	if (!header || !e)
+		return 0;
+
+	nearest_start = le64_to_cpu(header->last_usable_lba);
+
+	for (i = 0; i < le32_to_cpu(header->npartition_entries); i++) {
+		uint64_t ps = gpt_partition_start(&e[i]);
+
+		if (nearest_start > ps && ps > start)
+			nearest_start = ps - 1;
+	}
+
+	return nearest_start;
+}
+
+/* Returns the last free sector on the disk. From gdisk. */
+static uint64_t find_last_free_sector(struct gpt_header *header,
+				      struct gpt_entry *e)
+{
+	uint32_t i, last_moved;
+	uint64_t last = 0;
+
+	if (!header || !e)
+		goto done;
+
+	/* start by assuming the last usable LBA is available */
+	last = le64_to_cpu(header->last_usable_lba);
+	do {
+		last_moved = 0;
+		for (i = 0; i < le32_to_cpu(header->npartition_entries); i++) {
+			if ((last >= gpt_partition_start(&e[i])) &&
+			    (last <= gpt_partition_end(&e[i]))) {
+				last = gpt_partition_start(&e[i]) - 1;
+				last_moved = 1;
+			}
+		}
+	} while (last_moved == 1);
+done:
+	return last;
+}
+
+/*
+ * Finds the first available sector in the largest block of unallocated
+ * space on the disk. Returns 0 if there are no available blocks left.
+ * From gdisk.
+ */
+static uint64_t find_first_in_largest(struct gpt_header *header, struct gpt_entry *e)
+{
+	uint64_t start = 0, first_sect, last_sect;
+	uint64_t segment_size, selected_size = 0, selected_segment = 0;
+
+	if (!header || !e)
+		goto done;
+
+	do {
+		first_sect =  find_first_available(header, e, start);
+		if (first_sect != 0) {
+			last_sect = find_last_free(header, e, first_sect);
+			segment_size = last_sect - first_sect + 1;
+
+			if (segment_size > selected_size) {
+				selected_size = segment_size;
+				selected_segment = first_sect;
+			}
+			start = last_sect + 1;
+		}
+	} while (first_sect != 0);
+
+done:
+	return selected_segment;
+}
+
+/*
+ * Find the total number of free sectors, the number of segments in which
+ * they reside, and the size of the largest of those segments. From gdisk.
+ */
+static uint64_t get_free_sectors(struct fdisk_context *cxt, struct gpt_header *header,
+				 struct gpt_entry *e, uint32_t *nsegments,
+				 uint64_t *largest_segment)
+{
+	uint32_t num = 0;
+	uint64_t first_sect, last_sect;
+	uint64_t largest_seg = 0, segment_sz;
+	uint64_t totfound = 0, start = 0; /* starting point for each search */
+
+	if (!cxt->total_sectors)
+		goto done;
+
+	do {
+		first_sect = find_first_available(header, e, start);
+		if (first_sect) {
+			last_sect = find_last_free(header, e, first_sect);
+			segment_sz = last_sect - first_sect + 1;
+
+			if (segment_sz > largest_seg)
+				largest_seg = segment_sz;
+			totfound += segment_sz;
+			num++;
+			start = last_sect + 1;
+		}
+	} while (first_sect);
+
+done:
+	if (nsegments)
+		*nsegments = num;
+	if (largest_segment)
+		*largest_segment = largest_seg;
+
+	return totfound;
+}
+
+static int gpt_probe_label(struct fdisk_context *cxt, struct fdisk_label *lb)
+{
+	int mbr_type;
+	struct fdisk_gpt_label *gpt = (struct fdisk_gpt_label *) lb;
+
+	if (!cxt || !lb)
+		goto failed;
+
+	mbr_type = valid_pmbr(cxt);
+	if (!mbr_type)
+		goto failed;
+
+	DBG(LABEL, dbgprint("found a %s MBR", mbr_type == GPT_MBR_PROTECTIVE ?
+			    "protective" : "hybrid"));
+
+	/* primary header */
+	gpt->pheader = gpt_read_header(cxt, GPT_PRIMARY_PARTITION_TABLE_LBA,
+				       &gpt->ents);
+
+	/*
+	 * TODO: If the primary GPT is corrupt, we must check the last LBA of the
+	 * device to see if it has a valid GPT Header and point to a valid GPT
+	 * Partition Entry Array.
+	 * If it points to a valid GPT Partition Entry Array, then software should
+	 * restore the primary GPT if allowed by platform policy settings.
+	 *
+	 * For now we just abort GPT probing!
+	 */
+	if (!gpt->pheader || !gpt->ents)
+		goto failed;
+
+	/* OK, probing passed, now initialize backup header and fdisk variables. */
+	gpt->bheader = gpt_read_header(cxt, last_lba(cxt), NULL);
+
+	lb->nparts_max = le32_to_cpu(gpt->pheader->npartition_entries);
+	lb->nparts_cur = partitions_in_use(gpt->pheader, gpt->ents);
+
+	printf(_("\nWARNING: fdisk GPT support is currently new, and therefore "
+		 "in an experimental phase. Use at your own discretion.\n\n"));
+
+	return 1;
+failed:
+	DBG(LABEL, dbgprint("GPT probe failed"));
+	gpt_deinit(lb);
+	return 0;
+}
+
+/*
+ * Stolen from libblkid - can be removed once partition semantics
+ * are added to the fdisk API.
+ */
+static char *encode_to_utf8(unsigned char *src, size_t count)
+{
+	uint16_t c;
+	char *dest = xmalloc(count * sizeof(char));
+	size_t i, j, len = count;
+
+	memset(dest, 0, sizeof(char) * count);
+
+	for (j = i = 0; i + 2 <= count; i += 2) {
+		/* always little endian */
+		c = (src[i+1] << 8) | src[i];
+		if (c == 0) {
+			dest[j] = '\0';
+			break;
+		} else if (c < 0x80) {
+			if (j+1 >= len)
+				break;
+			dest[j++] = (uint8_t) c;
+		} else if (c < 0x800) {
+			if (j+2 >= len)
+				break;
+			dest[j++] = (uint8_t) (0xc0 | (c >> 6));
+			dest[j++] = (uint8_t) (0x80 | (c & 0x3f));
+		} else {
+			if (j+3 >= len)
+				break;
+			dest[j++] = (uint8_t) (0xe0 | (c >> 12));
+			dest[j++] = (uint8_t) (0x80 | ((c >> 6) & 0x3f));
+			dest[j++] = (uint8_t) (0x80 | (c & 0x3f));
+		}
+	}
+	dest[j] = '\0';
+
+	return dest;
+}
+
+/*
+ * List label partitions.
+ * This function must currently exist to comply with standard fdisk
+ * requirements, but once partition semantics are added to the fdisk
+ * API it can be removed for custom implementation (see gpt_label struct).
+ */
+void gpt_list_table(struct fdisk_context *cxt,
+		    int xtra  __attribute__ ((__unused__)))
+{
+	uint32_t i;
+	struct fdisk_gpt_label *gpt = gpt_label(cxt);
+	uint64_t fu = le64_to_cpu(gpt->pheader->first_usable_lba);
+	uint64_t lu = le64_to_cpu(gpt->pheader->last_usable_lba);
+
+	printf("\n#         Start          End    Size  Type            Name\n");
+
+	for (i = 0; i < le32_to_cpu(gpt->pheader->npartition_entries); i++) {
+		char *name = NULL, *sizestr = NULL;
+		uint64_t start = gpt_partition_start(&gpt->ents[i]);
+		uint64_t size = gpt_partition_size(&gpt->ents[i]);
+		struct fdisk_parttype *t;
+
+		if (partition_unused(&gpt->ents[i]) || !size)
+			continue;
+
+		/* the partition has to inside usable range */
+		if (start < fu || start + size - 1 > lu)
+			continue;
+
+		name = encode_to_utf8((unsigned char *)gpt->ents[i].partition_name,
+				      sizeof(gpt->ents[i].partition_name));
+		if (!name)
+			continue;
+		sizestr = size_to_human_string(SIZE_SUFFIX_1LETTER,
+					       size * cxt->sector_size);
+		if (!sizestr)
+			continue;
+
+		t = fdisk_get_partition_type(cxt, i);
+
+		printf("%2d %12ju %12ju  %6s  %-15.15s %s\n",
+		       i+1,
+		       start,
+		       gpt_partition_end(&gpt->ents[i]),
+		       sizestr,
+		       t->name,
+		       name);
+
+		fdisk_warn_alignment(cxt, start, i);
+
+		free(name);
+		free(sizestr);
+		fdisk_free_parttype(t);
+	}
+}
+
+/*
+ * Write partitions.
+ * Returns 0 on success, or corresponding error otherwise.
+ */
+static int gpt_write_partitions(struct fdisk_context *cxt,
+				struct gpt_header *header, struct gpt_entry *ents)
+{
+	off_t offset = le64_to_cpu(header->partition_entry_lba) * cxt->sector_size;
+	uint32_t nparts = le32_to_cpu(header->npartition_entries);
+	uint32_t totwrite = nparts * le32_to_cpu(header->sizeof_partition_entry);
+	ssize_t rc;
+
+	if (offset != lseek(cxt->dev_fd, offset, SEEK_SET))
+		goto fail;
+
+	rc = write(cxt->dev_fd, ents, totwrite);
+	if (rc > 0 && totwrite == (uint32_t) rc)
+		return 0;
+fail:
+	return -errno;
+}
+
+/*
+ * Write a GPT header to a specified LBA
+ * Returns 0 on success, or corresponding error otherwise.
+ */
+static int gpt_write_header(struct fdisk_context *cxt,
+			    struct gpt_header *header, uint64_t lba)
+{
+	off_t offset = lba * cxt->sector_size;
+
+	if (offset != lseek(cxt->dev_fd, offset, SEEK_SET))
+		goto fail;
+	if (cxt->sector_size ==
+	    (size_t) write(cxt->dev_fd, header, cxt->sector_size))
+		return 0;
+fail:
+	return -errno;
+}
+
+/*
+ * Write the protective MBR.
+ * Returns 0 on success, or corresponding error otherwise.
+ */
+static int gpt_write_pmbr(struct fdisk_context *cxt)
+{
+	off_t offset;
+	struct gpt_legacy_mbr *pmbr = NULL;
+
+	if (!cxt || !cxt->firstsector)
+		return -EINVAL;
+
+	pmbr = (struct gpt_legacy_mbr *) cxt->firstsector;
+
+	/* zero out the legacy partitions */
+	memset(pmbr->partition_record, 0, sizeof(pmbr->partition_record));
+
+	pmbr->signature = cpu_to_le16(MSDOS_MBR_SIGNATURE);
+	pmbr->partition_record[0].os_type      = EFI_PMBR_OSTYPE;
+	pmbr->partition_record[0].start_sector = 1;
+	pmbr->partition_record[0].end_head     = 0xFE;
+	pmbr->partition_record[0].end_sector   = 0xFF;
+	pmbr->partition_record[0].end_track    = 0xFF;
+	pmbr->partition_record[0].starting_lba = cpu_to_le32(1);
+
+	/*
+	 * Set size_in_lba to the size of the disk minus one. If the size of the disk
+	 * is too large to be represented by a 32bit LBA (2Tb), set it to 0xFFFFFFFF.
+	 */
+	if (cxt->total_sectors - 1 > 0xFFFFFFFFULL)
+		pmbr->partition_record[0].size_in_lba = cpu_to_le32(0xFFFFFFFF);
+	else
+		pmbr->partition_record[0].size_in_lba =
+			cpu_to_le32(cxt->total_sectors - 1UL);
+
+	offset = GPT_PMBR_LBA * cxt->sector_size;
+	if (offset != lseek(cxt->dev_fd, offset, SEEK_SET))
+		goto fail;
+
+	/* pMBR covers the first sector (LBA) of the disk */
+	if (write_all(cxt->dev_fd, pmbr, cxt->sector_size))
+		goto fail;
+	return 0;
+fail:
+	return -errno;
+}
+
+/*
+ * Writes in-memory GPT and pMBR data to disk.
+ * Returns 0 if successful write, otherwise, a corresponding error.
+ * Any indication of error will abort the operation.
+ */
+static int gpt_write_disklabel(struct fdisk_context *cxt, struct fdisk_label *lb)
+{
+	struct fdisk_gpt_label *gpt = (struct fdisk_gpt_label *) lb;
+
+	if (!cxt || !lb)
+		goto err0;
+
+	/* we do not want to mess up hybrid MBRs by creating a valid pmbr */
+	if (valid_pmbr(cxt) == GPT_MBR_HYBRID)
+		goto err0;
+
+	/* check that disk is big enough to handle the backup header */
+	if (gpt->pheader->alternative_lba > cxt->total_sectors)
+		goto err0;
+
+	/* check that the backup header is properly placed */
+	if (gpt->pheader->alternative_lba < cxt->total_sectors - 1)
+		/* TODO: correct this (with user authorization) and write */
+		goto err0;
+
+	if (partition_check_overlaps(gpt->pheader, gpt->ents))
+		goto err0;
+
+	/* recompute CRCs for both headers */
+	gpt_recompute_crc(gpt->pheader, gpt->ents);
+	gpt_recompute_crc(gpt->bheader, gpt->ents);
+
+	/*
+	 * UEFI requires writing in this specific order:
+	 *   1) backup partition tables
+	 *   2) backup GPT header
+	 *   3) primary partition tables
+	 *   4) primary GPT header
+	 *   5) protective MBR
+	 *
+	 * If any write fails, we abort the rest.
+	 */
+	if (gpt_write_partitions(cxt, gpt->bheader, gpt->ents) != 0)
+		goto err1;
+	if (gpt_write_header(cxt, gpt->bheader, gpt->pheader->alternative_lba) != 0)
+		goto err1;
+	if (gpt_write_partitions(cxt, gpt->pheader, gpt->ents) != 0)
+		goto err1;
+	if (gpt_write_header(cxt, gpt->pheader, GPT_PRIMARY_PARTITION_TABLE_LBA) != 0)
+		goto err1;
+	if (gpt_write_pmbr(cxt) != 0)
+		goto err1;
+
+	return 0;
+err0:
+	return -EINVAL;
+err1:
+	return -errno;
+}
+
+/*
+ * Verify data integrity and report any found problems for:
+ *   - primary and backup header validations
+ *   - paritition validations
+ */
+static int gpt_verify_disklabel(struct fdisk_context *cxt, struct fdisk_label *lb)
+{
+	int nerror = 0, ptnum;
+	struct fdisk_gpt_label *gpt = (struct fdisk_gpt_label *) lb;
+
+	if (!gpt || !gpt->bheader) {
+		nerror++;
+		printf(_("Disk does not contain a valid backup header.\n"));
+	}
+
+	if (!gpt_check_header_crc(gpt->pheader, gpt->ents)) {
+		nerror++;
+		printf(_("Invalid primary header CRC checksum.\n"));
+	}
+	if (gpt->bheader && !gpt_check_header_crc(gpt->bheader, gpt->ents)) {
+		nerror++;
+		printf(_("Invalid backup header CRC checksum.\n"));
+	}
+
+	if (!gpt_check_entryarr_crc(gpt->pheader, gpt->ents)) {
+		nerror++;
+		printf(_("Invalid partition entry checksum.\n"));
+	}
+
+	if (!gpt_check_lba_sanity(cxt, gpt->pheader)) {
+		nerror++;
+		printf(_("Invalid primary header LBA sanity checks.\n"));
+	}
+	if (gpt->bheader && !gpt_check_lba_sanity(cxt, gpt->bheader)) {
+		nerror++;
+		printf(_("Invalid backup header LBA sanity checks.\n"));
+	}
+
+	if (le64_to_cpu(gpt->pheader->my_lba) != GPT_PRIMARY_PARTITION_TABLE_LBA) {
+		nerror++;
+		printf(_("MyLBA mismatch with real position at primary header.\n"));
+	}
+	if (gpt->bheader && le64_to_cpu(gpt->bheader->my_lba) != last_lba(cxt)) {
+		nerror++;
+		printf(_("MyLBA mismatch with real position at backup header.\n"));
+
+	}
+
+	if (gpt->pheader->alternative_lba >= cxt->total_sectors) {
+		nerror++;
+		printf(_("Disk is to small to hold all data.\n"));
+	}
+
+	/*
+	 * if the GPT is the primary table, check the alternateLBA
+	 * to see if it is a valid GPT
+	 */
+	if (gpt->bheader && (gpt->pheader->my_lba != gpt->bheader->alternative_lba)) {
+		nerror++;
+		printf(_("Primary and backup header mismatch.\n"));
+	}
+
+	ptnum = partition_check_overlaps(gpt->pheader, gpt->ents);
+	if (ptnum) {
+		nerror++;
+		printf(_("Partition %d overlaps with partition %d.\n"),
+				ptnum, ptnum + 1);
+	}
+
+	ptnum = partition_check_too_big(gpt->pheader, gpt->ents, cxt->total_sectors);
+	if (ptnum) {
+		nerror++;
+		printf(_("Partition %u is too big for the disk.\n"), ptnum);
+	}
+
+	ptnum = partition_start_after_end(gpt->pheader, gpt->ents);
+	if (ptnum) {
+		nerror++;
+		printf(_("Partition %u ends before it starts.\n"), ptnum);
+	}
+
+	if (!nerror) { /* yay :-) */
+		uint32_t nsegments = 0;
+		uint64_t free_sectors = 0, largest_segment = 0;
+
+		printf(_("No errors detected\n"));
+		printf(_("Header version: %s\n"), gpt_get_header_revstr(gpt->pheader));
+		printf(_("Using %d out of %d partitions\n"),
+		       partitions_in_use(gpt->pheader, gpt->ents),
+		       le32_to_cpu(gpt->pheader->npartition_entries));
+
+		free_sectors = get_free_sectors(cxt, gpt->pheader, gpt->ents,
+						&nsegments, &largest_segment);
+		printf(_("A total of %ju free sectors available in %u segment(s) "
+			 "(largest %ju).\n"),
+		       free_sectors, nsegments, largest_segment);
+	} else
+		printf(_("Detected %d error(s).\n"), nerror);
+
+	return 0;
+}
+
+/* Delete a single GPT partition, specified by partnum. */
+static int gpt_delete_partition(struct fdisk_context *cxt,
+				struct fdisk_label *lb,
+				int partnum)
+{
+	struct fdisk_gpt_label *gpt = (struct fdisk_gpt_label *) lb;
+
+	if (!cxt || partnum < 0 || !gpt)
+		return -EINVAL;
+
+	if (partition_unused(&gpt->ents[partnum]))
+		return -EINVAL;
+
+	/* hasta la vista, baby! */
+	memset(&gpt->ents[partnum], 0, sizeof(struct gpt_entry));
+	if (!partition_unused(&gpt->ents[partnum]))
+		return -EINVAL;
+	else {
+		gpt_recompute_crc(gpt->pheader, gpt->ents);
+		gpt_recompute_crc(gpt->bheader, gpt->ents);
+		lb->nparts_cur--;
+		fdisk_label_set_changed(lb, 1);
+	}
+
+	return 0;
+}
+
+static void gpt_entry_set_type(struct gpt_entry *e, struct gpt_guid *type)
+{
+	size_t i;
+
+	/*
+	 * Copy corresponding partition type GUID. Only the first three blocks
+	 * are endian-aware.
+	 */
+	e->partition_type_guid.time_low = cpu_to_le32(type->time_low);
+	e->partition_type_guid.time_mid = cpu_to_le16(type->time_mid);
+	e->partition_type_guid.time_hi_and_version = cpu_to_le16(type->time_hi_and_version);
+	e->partition_type_guid.clock_seq_hi = type->clock_seq_hi;
+	e->partition_type_guid.clock_seq_low = type->clock_seq_low;
+	for (i = 0; i < 6; i++)
+		e->partition_type_guid.node[i] = type->node[i];
+
+	DBG(LABEL, fprintf(stderr, "new type: %08X-%04X-%04X-%02X%02X-%02X%02X%02X%02X%02X%02X\n",
+		type->time_low, type->time_mid, type->time_hi_and_version,
+		type->clock_seq_hi, type->clock_seq_low,
+		type->node[0], type->node[1], type->node[2],
+		type->node[3], type->node[4], type->node[5]));
+}
+
+/*
+ * Create a new GPT partition entry, specified by partnum, and with a range
+ * of fsect to lsenct sectors, of type t.
+ * Returns 0 on success, or negative upon failure.
+ */
+static int gpt_create_new_partition(struct fdisk_context *cxt,
+				    int partnum, uint64_t fsect, uint64_t lsect,
+				    struct gpt_guid *type,
+				    struct gpt_entry *entries)
+{
+	struct gpt_entry *e = NULL;
+	struct fdisk_gpt_label *gpt;
+
+	if (!cxt || fsect > lsect || partnum < 0)
+		return -EINVAL;
+
+	gpt = gpt_label(cxt);
+
+	e = xcalloc(1, sizeof(*e));
+	e->lba_end = cpu_to_le64(lsect);
+	e->lba_start = cpu_to_le64(fsect);
+
+	gpt_entry_set_type(e, type);
+
+	/* deal with partition name
+	for (i = 0; i < GPT_PART_NAME_LEN; i++)
+		e->partition_name[i] =
+			cpu_to_le16((uint16_t) gpt_sys_types[sys].name[i]);
+	*/
+
+	/*
+	 * Any time a new partition entry is created a new GUID must be
+	 * generated for that partition, and every partition is guaranteed
+	 * to have a unique GUID.
+	 */
+	uuid_generate_random((unsigned char *) &e->unique_partition_guid);
+	swap_efi_guid(&e->unique_partition_guid);
+
+	memcpy(&entries[partnum], e, sizeof(*e));
+
+	gpt_recompute_crc(gpt->pheader, entries);
+	gpt_recompute_crc(gpt->bheader, entries);
+
+	free(e);
+	return 0;
+}
+
+/* Performs logical checks to add a new partition entry */
+static int gpt_add_partition(
+		struct fdisk_context *cxt,
+		struct fdisk_label *lb,
+		int partnum,
+		struct fdisk_parttype *t)
+{
+	uint64_t user_f, user_l;	/* user input ranges for first and last sectors */
+	uint64_t disk_f, disk_l;	/* first and last available sector ranges on device*/
+	uint64_t dflt_f, dflt_l;	/* largest segment (default) */
+	struct gpt_guid uuid = GPT_DEFAULT_ENTRY_GUID;
+	struct fdisk_gpt_label *gpt = (struct fdisk_gpt_label *) lb;
+	struct gpt_header *pheader;
+	struct gpt_entry *ents;
+
+	/* check basic tests before even considering adding a new partition */
+	if (!cxt || partnum < 0 || !gpt)
+		return -EINVAL;
+
+	pheader = gpt->pheader;
+	ents = gpt->ents;
+
+	if (!partition_unused(&ents[partnum])) {
+		printf(_("Partition %d is already defined. "
+			 "Delete it before re-adding it.\n"), partnum +1);
+		return -EINVAL;
+	}
+	if (le32_to_cpu(pheader->npartition_entries) ==
+			partitions_in_use(pheader, ents)) {
+		printf(_("All partitions are already in use.\n"));
+		return -EINVAL;
+	}
+
+	if (!get_free_sectors(cxt, pheader, ents, NULL, NULL)) {
+		printf(_("No free sectors available.\n"));
+		return -ENOSPC;
+	}
+
+	disk_f = find_first_available(pheader, ents, 0);
+	disk_l = find_last_free_sector(pheader, ents);
+
+	/* the default is the largest free space */
+	dflt_f = find_first_in_largest(pheader, ents);
+	dflt_l = find_last_free(pheader, ents, dflt_f);
+
+	/* align the default in range <dflt_f,dflt_l>*/
+	dflt_f = fdisk_align_lba_in_range(cxt, dflt_f, dflt_f, dflt_l);
+
+	if (t && t->typestr)
+		string_to_uuid(t->typestr, &uuid);
+
+	/* get user input for first and last sectors of the new partition */
+	for (;;) {
+		int is_suffix_used = 0;
+
+		/* first sector */
+		user_f = read_int(cxt,	disk_f,	/* minimal */
+					dflt_f, /* default */
+					disk_l, /* maximal */
+					0, _("First sector"));
+
+		if (user_f < disk_f || user_f > disk_l)
+			continue;	/* bug in read_int() dialog? */
+
+		if (user_f != find_first_available(pheader, ents, user_f)) {
+			printf(_("Sector %ju already used\n"), user_f);
+			continue;
+		}
+
+		/* Last sector */
+		dflt_l = find_last_free(pheader, ents, user_f);
+		user_l = read_int_with_suffix(cxt,
+					user_f, /* minimal */
+					dflt_l, /* default */
+					dflt_l, /* maximal */
+					user_f, /* base for relative input */
+					_("Last sector, +sectors or +size{K,M,G}"),
+					&is_suffix_used);
+
+		if (is_suffix_used)
+			user_l = fdisk_align_lba_in_range(cxt, user_l, user_f, dflt_l) - 1;
+
+		if (user_l > user_f && user_l <= disk_l)
+			break;
+	}
+
+	if (gpt_create_new_partition(cxt, partnum,
+				     user_f, user_l, &uuid, ents) != 0)
+		printf(_("Could not create partition %d\n"), partnum + 1);
+	else {
+		printf(_("Created partition %d\n"), partnum + 1);
+		lb->nparts_cur++;
+		fdisk_label_set_changed(lb, 1);
+	}
+
+	return 0;
+}
+
+/*
+ * Create a new GPT disklabel - destroys any previous data.
+ */
+static int gpt_create_disklabel(struct fdisk_context *cxt, struct fdisk_label *lb)
+{
+	int rc = 0;
+	ssize_t entry_sz = 0;
+	struct gpt_guid *uid;
+	struct fdisk_gpt_label *gpt = (struct fdisk_gpt_label *) lb;
+
+	/* label private stuff has to be empty, see gpt_deinit() */
+	assert(gpt);
+	assert(gpt->pheader == NULL);
+	assert(gpt->bheader == NULL);
+
+	/*
+	 * When no header, entries or pmbr is set, we're probably
+	 * dealing with a new, empty disk - so always allocate memory
+	 * to deal with the data structures whatever the case is.
+	 */
+	rc = gpt_mknew_pmbr(cxt);
+	if (rc < 0)
+		goto done;
+
+	/* primary */
+	gpt->pheader = xcalloc(1, sizeof(*gpt->pheader));
+	rc = gpt_mknew_header(cxt, gpt->pheader, GPT_PRIMARY_PARTITION_TABLE_LBA);
+	if (rc < 0)
+		goto done;
+
+	/* backup ("copy" primary) */
+	gpt->bheader = xcalloc(1, sizeof(*gpt->bheader));
+	rc = gpt_mknew_header_from_bkp(cxt, gpt->bheader,
+			last_lba(cxt), gpt->pheader);
+	if (rc < 0)
+		goto done;
+
+	entry_sz = le32_to_cpu(gpt->pheader->npartition_entries) *
+		le32_to_cpu(gpt->pheader->sizeof_partition_entry);
+	gpt->ents = xcalloc(1, sizeof(*gpt->ents) * entry_sz);
+
+	gpt_recompute_crc(gpt->pheader, gpt->ents);
+	gpt_recompute_crc(gpt->bheader, gpt->ents);
+
+	lb->nparts_max = le32_to_cpu(gpt->pheader->npartition_entries);
+	lb->nparts_cur = 0;
+
+	uid = &gpt->pheader->disk_guid;
+	fprintf(stderr, ("Building a new GPT disklabel "
+			    "(GUID: %08X-%04X-%04X-%02X%02X-%02X%02X%02X%02X%02X%02X)\n"),
+			    uid->time_low, uid->time_mid,
+			    uid->time_hi_and_version,
+			    uid->clock_seq_hi,
+			    uid->clock_seq_low,
+			    uid->node[0], uid->node[1],
+			    uid->node[2], uid->node[3],
+			    uid->node[4], uid->node[5]);
+	fdisk_label_set_changed(lb, 1);
+done:
+	return rc;
+}
+
+static struct fdisk_parttype *gpt_get_partition_type(
+		struct fdisk_context *cxt,
+		struct fdisk_label *lb,
+		int i)
+{
+	struct fdisk_parttype *t;
+	struct gpt_guid uuid;
+	char str[37];
+	struct fdisk_gpt_label *gpt = (struct fdisk_gpt_label *) lb;
+
+	if (!cxt)
+		return NULL;
+
+	if (!cxt || !gpt || i < 0
+	         || (uint32_t) i >= le32_to_cpu(gpt->pheader->npartition_entries))
+		return NULL;
+
+	uuid = gpt->ents[i].partition_type_guid;
+	swap_efi_guid(&uuid);
+
+	uuid_to_string(&uuid, str);
+	t = fdisk_get_parttype_from_string(cxt, str);
+	if (!t)
+		t = fdisk_new_unknown_parttype(0, str);
+
+	return t;
+}
+
+
+static int gpt_set_partition_type(
+		struct fdisk_context *cxt,
+		struct fdisk_label *lb,
+		int i,
+		struct fdisk_parttype *t)
+{
+	struct gpt_guid uuid;
+	struct fdisk_gpt_label *gpt = (struct fdisk_gpt_label *) lb;
+
+
+	if (!cxt || !gpt || i < 0
+	     || (uint32_t) i >= le32_to_cpu(gpt->pheader->npartition_entries)
+	     || !t || !t->typestr || string_to_uuid(t->typestr, &uuid) != 0)
+		return -EINVAL;
+
+	gpt_entry_set_type(&gpt->ents[i], &uuid);
+	gpt_recompute_crc(gpt->pheader, gpt->ents);
+	gpt_recompute_crc(gpt->bheader, gpt->ents);
+
+	fdisk_label_set_changed(lb, 1);
+	return 0;
+}
+
+static int gpt_get_partition_status(
+		struct fdisk_context *cxt,
+		struct fdisk_label *lb __attribute__((__unused__)),
+		int i,
+		int *status)
+{
+	struct fdisk_gpt_label *gpt = gpt_label(cxt);
+	struct gpt_entry *e;
+
+	if (!cxt || !gpt || i < 0 || !status
+	     || (uint32_t) i >= le32_to_cpu(gpt->pheader->npartition_entries))
+		return -EINVAL;
+
+	e = &gpt->ents[i];
+	*status = FDISK_PARTSTAT_NONE;
+
+	if (!partition_unused(&gpt->ents[i]) || gpt_partition_size(e))
+		*status = FDISK_PARTSTAT_USED;
+
+	return 0;
+}
+
+
+/*
+ * Deinitialize fdisk-specific variables
+ */
+static void gpt_deinit(struct fdisk_label *lb)
+{
+	struct fdisk_gpt_label *gpt = (struct fdisk_gpt_label *) lb;
+
+	if (!gpt)
+		return;
+
+	free(gpt->ents);
+	free(gpt->pheader);
+	free(gpt->bheader);
+
+	gpt->ents = NULL;
+	gpt->pheader = NULL;
+	gpt->bheader = NULL;
+}
+
+static const struct fdisk_label_operations gpt_operations =
+{
+	.probe		= gpt_probe_label,
+	.write		= gpt_write_disklabel,
+	.verify		= gpt_verify_disklabel,
+	.create		= gpt_create_disklabel,
+	.part_add	= gpt_add_partition,
+	.part_delete	= gpt_delete_partition,
+	.part_get_type	= gpt_get_partition_type,
+	.part_set_type	= gpt_set_partition_type,
+
+	.part_get_status = gpt_get_partition_status,
+
+	.deinit		= gpt_deinit
+};
+
+/*
+ * allocates GPT in-memory stuff
+ */
+struct fdisk_label *fdisk_new_gpt_label(struct fdisk_context *cxt)
+{
+	struct fdisk_label *lb;
+	struct fdisk_gpt_label *gpt;
+
+	assert(cxt);
+
+	gpt = calloc(1, sizeof(*gpt));
+	if (!gpt)
+		return NULL;
+
+	/* initialize generic part of the driver */
+	lb = (struct fdisk_label *) gpt;
+	lb->name = "gpt";
+	lb->id = FDISK_DISKLABEL_GPT;
+	lb->op = &gpt_operations;
+	lb->parttypes = gpt_parttypes;
+	lb->nparttypes = ARRAY_SIZE(gpt_parttypes);
+
+	return lb;
+}