[thirdparty/util-linux.git] / libfdisk / src / gpt.c

/*
 * 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.
 */
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <inttypes.h>
#include <stdint.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 "crc32.h"
#include "blkdev.h"
#include "bitops.h"
#include "strutils.h"
#include "all-io.h"
#include "pt-mbr.h"
#include "encode.h"

/**
 * SECTION: gpt
 * @title: UEFI GPT
 * @short_description: specific functionality
 */

#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 0x00000001ULL

#define EFI_PMBR_OSTYPE     0xEE
#define MSDOS_MBR_SIGNATURE 0xAA55
#define GPT_PART_NAME_LEN   (72 / sizeof(uint16_t))
#define GPT_NPARTITIONS     ((size_t) FDISK_GPT_NPARTITIONS_DEFAULT)

/* 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_TYPE "0FC63DAF-8483-4772-8E79-3D69D8477DE4"

/*
 * Attribute bits
 */
enum {
        /* UEFI specific */
        GPT_ATTRBIT_REQ      = 0,
        GPT_ATTRBIT_NOBLOCK  = 1,
        GPT_ATTRBIT_LEGACY   = 2,

        /* GUID specific (range 48..64)*/
        GPT_ATTRBIT_GUID_FIRST  = 48,
        GPT_ATTRBIT_GUID_COUNT  = 16
};

#define GPT_ATTRSTR_REQ         "RequiredPartition"
#define GPT_ATTRSTR_REQ_TYPO    "RequiredPartiton"
#define GPT_ATTRSTR_NOBLOCK     "NoBlockIOProtocol"
#define GPT_ATTRSTR_LEGACY      "LegacyBIOSBootable"

/* The GPT Partition entry array contains an array of GPT entries. */
struct gpt_entry {
        struct gpt_guid     type; /* purpose and type of the partition */
        struct gpt_guid     partition_guid;
        uint64_t            lba_start;
        uint64_t            lba_end;
        uint64_t            attrs;
        uint16_t            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 of block 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; /* LBA of start of partition entries 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 all 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 const struct fdisk_parttype gpt_parttypes[] =
{
        #include "pt-gpt-partnames.h"
};

static const struct fdisk_shortcut gpt_parttype_cuts[] =
{
        { .shortcut = "L", .alias = "linux",    .data = "0FC63DAF-8483-4772-8E79-3D69D8477DE4" }, /* Linux */
        { .shortcut = "S", .alias = "swap",     .data = "0657FD6D-A4AB-43C4-84E5-0933C84B4F4F" }, /* Swap */
        { .shortcut = "H", .alias = "home",     .data = "933AC7E1-2EB4-4F13-B844-0E14E2AEF915" }, /* Home */
        { .shortcut = "U", .alias = "uefi",     .data = "C12A7328-F81F-11D2-BA4B-00A0C93EC93B" }, /* UEFI system */
        { .shortcut = "R", .alias = "raid",     .data = "A19D880F-05FC-4D3B-A006-743F0F84911E" }, /* Linux RAID */
        { .shortcut = "V", .alias = "lvm",      .data = "E6D6D379-F507-44C2-A23C-238F2A3DF928" }, /* LVM */
        { .shortcut = "X", .alias = "xbootldr", .data = "BC13C2FF-59E6-4262-A352-B275FD6F7172" }, /* Linux extended boot */
};

#define alignment_required(_x)  ((_x)->grain != (_x)->sector_size)

/* 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 */

        unsigned char *ents;                    /* entries (partitions) */

        unsigned int no_relocate :1,            /* do not fix backup location */
                     minimize :1;
};

static void gpt_deinit(struct fdisk_label *lb);

static inline struct fdisk_gpt_label *self_label(struct fdisk_context *cxt)
{
        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;
}

/* prints UUID in the real byte order! */
static void gpt_debug_uuid(const char *mesg, struct gpt_guid *guid)
{
        const unsigned char *uuid = (unsigned char *) guid;

        fprintf(stderr, "%s: "
                "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x\n",
                mesg,
                uuid[0], uuid[1], uuid[2], uuid[3],
                uuid[4], uuid[5],
                uuid[6], uuid[7],
                uuid[8], uuid[9],
                uuid[10], uuid[11], uuid[12], uuid[13], uuid[14],uuid[15]);
}

/*
 * 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_guid(const char *in, struct gpt_guid *guid)
{
        if (uuid_parse(in, (unsigned char *) guid)) {   /* BE */
                DBG(GPT, ul_debug("failed to parse GUID: %s", in));
                return -EINVAL;
        }
        swap_efi_guid(guid);                            /* LE */
        return 0;
}

static char *guid_to_string(const struct gpt_guid *guid, char *out)
{
        struct gpt_guid u = *guid;      /* LE */

        swap_efi_guid(&u);              /* BE */
        uuid_unparse_upper((unsigned char *) &u, out);

        return out;
}

static struct fdisk_parttype *gpt_partition_parttype(
                struct fdisk_context *cxt,
                const struct gpt_entry *e)
{
        struct fdisk_parttype *t;
        char str[UUID_STR_LEN];
        struct gpt_guid guid = e->type;

        guid_to_string(&guid, str);
        t = fdisk_label_get_parttype_from_string(cxt->label, str);
        return t ? : fdisk_new_unknown_parttype(0, str);
}

static void gpt_entry_set_type(struct gpt_entry *e, struct gpt_guid *uuid)
{
        e->type = *uuid;
        DBG(GPT, gpt_debug_uuid("new type", uuid));
}

static int gpt_entry_set_name(struct gpt_entry *e, char *str)
{
        uint16_t name[GPT_PART_NAME_LEN] = { 0 };
        size_t i, mblen = 0;
        uint8_t *in = (uint8_t *) str;

        for (i = 0; *in && i < GPT_PART_NAME_LEN; in++) {
                if (!mblen) {
                        if (!(*in & 0x80)) {
                                name[i++] = *in;
                        } else if ((*in & 0xE0) == 0xC0) {
                                mblen = 1;
                                name[i] = (uint16_t)(*in & 0x1F) << (mblen *6);
                        } else if ((*in & 0xF0) == 0xE0) {
                                mblen = 2;
                                name[i] = (uint16_t)(*in & 0x0F) << (mblen *6);
                        } else {
                                /* broken UTF-8 or code point greater than U+FFFF */
                                return -EILSEQ;
                        }
                } else {
                        /* incomplete UTF-8 sequence */
                        if ((*in & 0xC0) != 0x80)
                                return -EILSEQ;

                        name[i] |= (uint16_t)(*in & 0x3F) << (--mblen *6);
                        if (!mblen) {
                                /* check for code points reserved for surrogate pairs*/
                                if ((name[i] & 0xF800) == 0xD800)
                                        return -EILSEQ;
                                i++;
                        }
                }
        }

        for (i = 0; i < GPT_PART_NAME_LEN; i++)
                e->name[i] = cpu_to_le16(name[i]);

        return (int)((char *) in - str);
}

static int gpt_entry_set_uuid(struct gpt_entry *e, char *str)
{
        struct gpt_guid uuid;
        int rc;

        rc = string_to_guid(str, &uuid);
        if (rc)
                return rc;

        e->partition_guid = uuid;
        return 0;
}

static inline int gpt_entry_is_used(const struct gpt_entry *e)
{
        return memcmp(&e->type, &GPT_UNUSED_ENTRY_GUID,
                        sizeof(struct gpt_guid)) != 0;
}


static const char *gpt_get_header_revstr(struct gpt_header *header)
{
        if (!header)
                goto unknown;

        switch (le32_to_cpu(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 unsigned char *gpt_get_entry_ptr(struct fdisk_gpt_label *gpt, size_t i)
{
        return gpt->ents + le32_to_cpu(gpt->pheader->sizeof_partition_entry) * i;
}

static inline struct gpt_entry *gpt_get_entry(struct fdisk_gpt_label *gpt, size_t i)
{
        return (struct gpt_entry *) gpt_get_entry_ptr(gpt, i);
}

static inline struct gpt_entry *gpt_zeroize_entry(struct fdisk_gpt_label *gpt, size_t i)
{
        return (struct gpt_entry *) memset(gpt_get_entry_ptr(gpt, i),
                        0, le32_to_cpu(gpt->pheader->sizeof_partition_entry));
}

/* Use to access array of entries, for() loops, etc. But don't use when
 * you directly do something with GPT header, then use uint32_t.
 */
static inline size_t gpt_get_nentries(struct fdisk_gpt_label *gpt)
{
        return (size_t) le32_to_cpu(gpt->pheader->npartition_entries);
}

/* calculate size of entries array in bytes for specified number of entries */
static inline int gpt_calculate_sizeof_entries(
                                struct gpt_header *hdr,
                                uint32_t nents, size_t *sz)
{
        uint32_t esz = hdr ? le32_to_cpu(hdr->sizeof_partition_entry) :
                             sizeof(struct gpt_entry);

        if (nents == 0 || esz == 0 || SIZE_MAX/esz < nents) {
                DBG(GPT, ul_debug("entries array size check failed"));
                return -ERANGE;
        }

        *sz = (size_t) nents * esz;
        return 0;
}

/* calculate size of entries array in sectors for specified number of entries */
static inline int gpt_calculate_sectorsof_entries(
                                struct gpt_header *hdr,
                                uint32_t nents, uint64_t *sz,
                                struct fdisk_context *cxt)
{
        size_t esz = 0;
        int rc = gpt_calculate_sizeof_entries(hdr, nents, &esz);        /* in bytes */

        if (rc == 0)
                *sz = (esz + cxt->sector_size - 1) / cxt->sector_size;
        return rc;
}

/* calculate alternative (backup) entries array offset from primary header */
static inline int gpt_calculate_alternative_entries_lba(
                                struct gpt_header *hdr,
                                uint32_t nents,
                                uint64_t *sz,
                                struct fdisk_context *cxt)
{
        uint64_t esects = 0;
        int rc = gpt_calculate_sectorsof_entries(hdr, nents, &esects, cxt);

        if (rc)
                return rc;
        if (cxt->total_sectors < 1ULL + esects)
                return -ENOSPC;

        *sz = cxt->total_sectors - 1ULL - esects;
        return 0;
}

static inline int gpt_calculate_last_lba(
                                struct gpt_header *hdr,
                                uint32_t nents,
                                uint64_t *sz,
                                struct fdisk_context *cxt)
{
        uint64_t esects = 0;
        int rc = gpt_calculate_sectorsof_entries(hdr, nents, &esects, cxt);

        if (rc)
                return rc;
        if (cxt->total_sectors < 2ULL + esects)
                return -ENOSPC;

        *sz = cxt->total_sectors - 2ULL - esects;
        return 0;
}

static inline int gpt_calculate_first_lba(
                                struct gpt_header *hdr,
                                uint32_t nents,
                                uint64_t *sz,
                                struct fdisk_context *cxt)
{
        uint64_t esects = 0;
        int rc = gpt_calculate_sectorsof_entries(hdr, nents, &esects, cxt);

        if (rc == 0)
                *sz = esects + 2ULL;
        return rc;
}

/* the current size of entries array in bytes */
static inline int gpt_sizeof_entries(struct gpt_header *hdr, size_t *sz)
{
        return gpt_calculate_sizeof_entries(hdr, le32_to_cpu(hdr->npartition_entries), sz);
}

static char *gpt_get_header_id(struct gpt_header *header)
{
        char str[UUID_STR_LEN];
        struct gpt_guid guid = header->disk_guid;

        guid_to_string(&guid, str);

        return strdup(str);
}

/*
 * 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;
        int rc;

        if (!cxt || !cxt->firstsector)
                return -ENOSYS;

        if (fdisk_has_protected_bootbits(cxt))
                rc = fdisk_init_firstsector_buffer(cxt, 0, MBR_PT_BOOTBITS_SIZE);
        else
                rc = fdisk_init_firstsector_buffer(cxt, 0, 0);
        if (rc)
                return rc;

        pmbr = (struct gpt_legacy_mbr *) cxt->firstsector;
        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 = 2;
        pmbr->partition_record[0].end_head     = 0xFF;
        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((uint32_t) min( cxt->total_sectors - 1ULL, 0xFFFFFFFFULL) );

        return 0;
}


/* Move backup header to the end of the device */
static int gpt_fix_alternative_lba(struct fdisk_context *cxt, struct fdisk_gpt_label *gpt)
{
        struct gpt_header *p, *b;
        uint64_t x = 0, orig;
        size_t nents;
        int rc;

        if (!cxt)
                return -EINVAL;

        p = gpt->pheader;       /* primary */
        b = gpt->bheader;       /* backup */

        nents = le32_to_cpu(p->npartition_entries);
        orig = le64_to_cpu(p->alternative_lba);

        /* reference from primary to backup */
        p->alternative_lba = cpu_to_le64(cxt->total_sectors - 1ULL);

        /* reference from backup to primary */
        b->alternative_lba = p->my_lba;
        b->my_lba = p->alternative_lba;

        /* fix backup partitions array address */
        rc = gpt_calculate_alternative_entries_lba(p, nents, &x, cxt);
        if (rc)
                goto failed;

        b->partition_entry_lba = cpu_to_le64(x);

        /* update last usable LBA */
        rc = gpt_calculate_last_lba(p, nents, &x, cxt);
        if (rc)
                goto failed;

        p->last_usable_lba  = cpu_to_le64(x);
        b->last_usable_lba  = cpu_to_le64(x);

        DBG(GPT, ul_debug("Alternative-LBA updated from %"PRIu64" to %"PRIu64,
                                orig, le64_to_cpu(p->alternative_lba)));
        return 0;
failed:
        DBG(GPT, ul_debug("failed to fix alternative-LBA [rc=%d]", rc));
        return rc;
}

static uint64_t gpt_calculate_minimal_size(struct fdisk_context *cxt, struct fdisk_gpt_label *gpt)
{
        size_t i;
        uint64_t x = 0, total = 0;
        struct gpt_header *hdr;

        assert(cxt);
        assert(gpt);
        assert(gpt->pheader);
        assert(gpt->ents);

        hdr = gpt->pheader;

        /* LBA behind the last partition */
        for (i = 0; i < gpt_get_nentries(gpt); i++) {
                struct gpt_entry *e = gpt_get_entry(gpt, i);

                if (gpt_entry_is_used(e)) {
                        uint64_t end = gpt_partition_end(e);
                        if (end > x)
                                x = end;
                }
        }
        total = x + 1;

        /* the current last LBA usable for partitions */
        gpt_calculate_last_lba(hdr, le32_to_cpu(hdr->npartition_entries), &x, cxt);

        /* size of all stuff at the end of the device */
        total += cxt->total_sectors - x;

        DBG(GPT, ul_debug("minimal device is %"PRIu64, total));
        return total;
}

static int gpt_possible_minimize(struct fdisk_context *cxt, struct fdisk_gpt_label *gpt)
{
        struct gpt_header *hdr = gpt->pheader;
        uint64_t total = gpt_calculate_minimal_size(cxt, gpt);

        return le64_to_cpu(hdr->alternative_lba) > (total - 1ULL);
}

/* move backup header behind the last partition */
static int gpt_minimize_alternative_lba(struct fdisk_context *cxt, struct fdisk_gpt_label *gpt)
{
        uint64_t total = gpt_calculate_minimal_size(cxt, gpt);
        uint64_t orig = cxt->total_sectors;
        int rc;

        /* Let's temporary change size of the device to recalculate backup header */
        cxt->total_sectors = total;
        rc = gpt_fix_alternative_lba(cxt, gpt);
        if (rc)
                return rc;

        cxt->total_sectors = orig;
        fdisk_label_set_changed(cxt->label, 1);
        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 - 1ULL);
                header->partition_entry_lba = cpu_to_le64(2ULL);

        } else {
                /* backup */
                uint64_t x = 0;
                gpt_calculate_alternative_entries_lba(header,
                                le32_to_cpu(header->npartition_entries), &x, cxt);

                header->alternative_lba = cpu_to_le64(GPT_PRIMARY_PARTITION_TABLE_LBA);
                header->partition_entry_lba = cpu_to_le64(x);
        }
}

/*
 * 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;
}

static struct gpt_header *gpt_copy_header(struct fdisk_context *cxt,
                           struct gpt_header *src)
{
        struct gpt_header *res;

        if (!cxt || !src)
                return NULL;

        assert(cxt->sector_size >= sizeof(struct gpt_header));

        res = calloc(1, cxt->sector_size);
        if (!res) {
                fdisk_warn(cxt, _("failed to allocate GPT header"));
                return NULL;
        }

        res->my_lba                 = src->alternative_lba;
        res->alternative_lba        = src->my_lba;

        res->signature              = src->signature;
        res->revision               = src->revision;
        res->size                   = src->size;
        res->npartition_entries     = src->npartition_entries;
        res->sizeof_partition_entry = src->sizeof_partition_entry;
        res->first_usable_lba       = src->first_usable_lba;
        res->last_usable_lba        = src->last_usable_lba;

        memcpy(&res->disk_guid, &src->disk_guid, sizeof(src->disk_guid));


        if (res->my_lba == GPT_PRIMARY_PARTITION_TABLE_LBA)
                res->partition_entry_lba = cpu_to_le64(2ULL);
        else {
                uint64_t esz = (uint64_t) le32_to_cpu(src->npartition_entries) * sizeof(struct gpt_entry);
                uint64_t esects = (esz + cxt->sector_size - 1) / cxt->sector_size;

                res->partition_entry_lba = cpu_to_le64(cxt->total_sectors - 1ULL - esects);
        }

        return res;
}

static int get_script_u64(struct fdisk_context *cxt, uint64_t *num, const char *name)
{
        const char *str;
        int pwr = 0, rc = 0;

        assert(cxt);

        *num = 0;

        if (!cxt->script)
                return 1;

        str = fdisk_script_get_header(cxt->script, name);
        if (!str)
                return 1;

        rc = ul_parse_size(str, (uintmax_t *) num, &pwr);
        if (rc < 0)
                return rc;
        if (pwr)
                *num /= cxt->sector_size;
        return 0;
}

static int count_first_last_lba(struct fdisk_context *cxt,
                                 uint64_t *first, uint64_t *last,
                                 uint32_t *maxents)
{
        int rc = 0;
        uint64_t flba = 0, llba = 0;
        uint64_t nents = GPT_NPARTITIONS;

        assert(cxt);
        assert(first);
        assert(last);

        *first = *last = 0;

        /* Get the table length from the script, if given */
        if (cxt->script) {
                rc = get_script_u64(cxt, &nents, "table-length");
                if (rc == 1)
                        nents = GPT_NPARTITIONS;  /* undefined by script */
                else if (rc < 0)
                        return rc;
        }

        /* The table length was not changed by the script, compute it. */
        if (flba == 0) {
                /* If the device is not large enough reduce this number of
                 * partitions and try to recalculate it again, until we get
                 * something useful or return error.
                 */
                for (; nents > 0; nents--) {
                        rc = gpt_calculate_last_lba(NULL, nents, &llba, cxt);
                        if (rc == 0)
                                rc = gpt_calculate_first_lba(NULL, nents, &flba, cxt);
                        if (llba < flba)
                                rc = -ENOSPC;
                        else if (rc == 0)
                                break;
                }
        }

        if (rc)
                return rc;
        if (maxents)
                *maxents = nents;

        /* script default */
        if (cxt->script) {
                rc = get_script_u64(cxt, first, "first-lba");
                if (rc < 0)
                        return rc;

                DBG(GPT, ul_debug("FirstLBA: script=%"PRIu64", uefi=%"PRIu64", topology=%ju.",
                                    *first, flba,  (uintmax_t)cxt->first_lba));

                if (rc == 0 && (*first < flba || *first > llba)) {
                        fdisk_warnx(cxt, _("First LBA specified by script is out of range."));
                        return -ERANGE;
                }

                rc = get_script_u64(cxt, last, "last-lba");
                if (rc < 0)
                        return rc;

                DBG(GPT, ul_debug("LastLBA: script=%"PRIu64", uefi=%"PRIu64", topology=%ju.",
                                    *last, llba,  (uintmax_t)cxt->last_lba));

                if (rc == 0 && (*last > llba || *last < flba)) {
                        fdisk_warnx(cxt, _("Last LBA specified by script is out of range."));
                        return -ERANGE;
                }
        }

        if (!*last)
                *last = llba;

        /* default by topology */
        if (!*first)
                *first = flba < cxt->first_lba &&
                         cxt->first_lba < *last ? cxt->first_lba : flba;
        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 first, last;
        uint32_t nents = 0;
        int has_id = 0, rc;

        if (!cxt || !header)
                return -ENOSYS;

        header->signature = cpu_to_le64(GPT_HEADER_SIGNATURE);
        header->revision  = cpu_to_le32(GPT_HEADER_REVISION_V1_00);

        /* According to EFI standard it's valid to count all the first
         * sector into header size, but some tools may have a problem
         * to accept it, so use the header without the zeroed area.
         * This does not have any impact to CRC, etc.   --kzak Jan-2015
         */
        header->size = cpu_to_le32(sizeof(struct gpt_header)
                                - sizeof(header->reserved2));

        /* Set {First,Last}LBA and number of the partitions
         * (default is GPT_NPARTITIONS) */
        rc = count_first_last_lba(cxt, &first, &last, &nents);
        if (rc)
                return rc;

        header->npartition_entries     = cpu_to_le32(nents);
        header->sizeof_partition_entry = cpu_to_le32(sizeof(struct gpt_entry));

        header->first_usable_lba = cpu_to_le64(first);
        header->last_usable_lba  = cpu_to_le64(last);

        gpt_mknew_header_common(cxt, header, lba);

        if (cxt->script) {
                const char *id = fdisk_script_get_header(cxt->script, "label-id");
                struct gpt_guid guid = header->disk_guid;
                if (id && string_to_guid(id, &guid) == 0)
                        has_id = 1;
                header->disk_guid = guid;
        }

        if (!has_id) {
                struct gpt_guid guid;

                uuid_generate_random((unsigned char *) &guid);
                swap_efi_guid(&guid);
                header->disk_guid = 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, depending on the detection.
 */
static int valid_pmbr(struct fdisk_context *cxt)
{
        int i, part = 0, ret = 0; /* invalid by default */
        struct gpt_legacy_mbr *pmbr = NULL;

        if (!cxt->firstsector)
                goto done;

        pmbr = (struct gpt_legacy_mbr *) cxt->firstsector;

        if (le16_to_cpu(pmbr->signature) != MSDOS_MBR_SIGNATURE)
                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.
                         */
                        part = i;
                        ret = GPT_MBR_PROTECTIVE;
                        break;
                }
        }

        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;
                        goto done;
                }
        }

        /* LBA of the GPT partition header */
        if (pmbr->partition_record[part].starting_lba !=
            cpu_to_le32(GPT_PRIMARY_PARTITION_TABLE_LBA))
                goto done;

        /*
         * Protective MBRs take up the lesser of the whole disk
         * or 2 TiB (32bit LBA), ignoring the rest of the disk.
         * Some partitioning programs, nonetheless, choose to set
         * the size to the maximum 32-bit limitation, disregarding
         * the disk size.
         *
         * Hybrid MBRs do not necessarily comply with this.
         *
         * Consider a bad value here to be a warning to support dd-ing
         * an image from a smaller disk to a bigger disk.
         */
        if (ret == GPT_MBR_PROTECTIVE) {
                uint64_t sz_lba = (uint64_t) le32_to_cpu(pmbr->partition_record[part].size_in_lba);
                if (sz_lba != cxt->total_sectors - 1ULL && sz_lba != 0xFFFFFFFFULL) {

                        fdisk_warnx(cxt, _("GPT PMBR size mismatch (%"PRIu64" != %"PRIu64") "
                                           "will be corrected by write."),
                                        sz_lba, cxt->total_sectors - (uint64_t) 1);

                        /* Note that gpt_write_pmbr() overwrites PMBR, but we want to keep it valid already
                         * in memory too to disable warnings when valid_pmbr() called next time */
                        pmbr->partition_record[part].size_in_lba  =
                                cpu_to_le32((uint32_t) min( cxt->total_sectors - 1ULL, 0xFFFFFFFFULL) );
                        fdisk_label_set_changed(cxt->label, 1);
                }
        }
done:
        DBG(GPT, ul_debug("PMBR type: %s",
                        ret == GPT_MBR_PROTECTIVE ? "protective" :
                        ret == GPT_MBR_HYBRID     ? "hybrid"     : "???" ));
        return ret;
}

static uint64_t last_lba(struct fdisk_context *cxt)
{
        struct stat s;
        uint64_t sectors = 0;

        memset(&s, 0, sizeof(s));
        if (fstat(cxt->dev_fd, &s) == -1) {
                fdisk_warn(cxt, _("gpt: stat() failed"));
                return 0;
        }

        if (S_ISBLK(s.st_mode))
                sectors = cxt->total_sectors - 1ULL;
        else if (S_ISREG(s.st_mode))
                sectors = ((uint64_t) s.st_size /
                           (uint64_t) cxt->sector_size) - 1ULL;
        else
                fdisk_warnx(cxt, _("gpt: cannot handle files with mode %o"), s.st_mode);

        DBG(GPT, ul_debug("last LBA: %"PRIu64"", sectors));
        return sectors;
}

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;

        if (lseek(cxt->dev_fd, offset, SEEK_SET) == (off_t) -1)
                return -1;
        return (size_t)read(cxt->dev_fd, buffer, bytes) != bytes;
}


/* Returns the GPT entry array */
static unsigned char *gpt_read_entries(struct fdisk_context *cxt,
                                         struct gpt_header *header)
{
        size_t sz = 0;
        ssize_t ssz;

        unsigned char *ret = NULL;
        off_t offset;

        assert(cxt);
        assert(header);

        if (gpt_sizeof_entries(header, &sz))
                return NULL;

        ret = calloc(1, sz);
        if (!ret)
                return NULL;

        offset = (off_t) le64_to_cpu(header->partition_entry_lba) *
                       cxt->sector_size;

        if (offset != lseek(cxt->dev_fd, offset, SEEK_SET))
                goto fail;

        ssz = read(cxt->dev_fd, ret, sz);
        if (ssz < 0 || (size_t) ssz != sz)
                goto fail;

        return ret;

fail:
        free(ret);
        return NULL;
}

static inline uint32_t count_crc32(const unsigned char *buf, size_t len,
                                   size_t ex_off, size_t ex_len)
{
        return (ul_crc32_exclude_offset(~0L, buf, len, ex_off, ex_len, 0) ^ ~0L);
}

static inline uint32_t gpt_header_count_crc32(struct gpt_header *header)
{
        return count_crc32((unsigned char *) header,            /* buffer */
                        le32_to_cpu(header->size),              /* size of buffer */
                        offsetof(struct gpt_header, crc32),     /* exclude */
                        sizeof(header->crc32));                 /* size of excluded area */
}

static inline uint32_t gpt_entryarr_count_crc32(struct gpt_header *header, unsigned char *ents)
{
        size_t arysz = 0;

        if (gpt_sizeof_entries(header, &arysz))
                return 0;

        return count_crc32(ents, arysz, 0, 0);
}


/*
 * Recompute header and partition array 32bit CRC checksums.
 * This function does not fail - if there's corruption, then it
 * will be reported when checksumming it again (ie: probing or verify).
 */
static void gpt_recompute_crc(struct gpt_header *header, unsigned char *ents)
{
        if (!header)
                return;

        header->partition_entry_array_crc32 =
                        cpu_to_le32( gpt_entryarr_count_crc32(header, ents) );

        header->crc32 = cpu_to_le32( gpt_header_count_crc32(header) );
}

/*
 * 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, unsigned char *ents)
{
        uint32_t orgcrc = le32_to_cpu(header->crc32),
                 crc = gpt_header_count_crc32(header);

        if (crc == orgcrc)
                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);
                return gpt_header_count_crc32(header) == orgcrc;
        }

        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, unsigned char *ents)
{
        if (!header || !ents)
                return 0;

        return gpt_entryarr_count_crc32(header, ents) ==
                        le32_to_cpu(header->partition_entry_array_crc32);
}

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(GPT, ul_debug("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(GPT, ul_debug("error: header LBAs are after the disk's last LBA (%ju..%ju)",
                                        (uintmax_t) fu, (uintmax_t) lu));
                goto done;
        }

        /* the header has to be outside usable range */
        if (fu < GPT_PRIMARY_PARTITION_TABLE_LBA &&
            GPT_PRIMARY_PARTITION_TABLE_LBA < lu) {
                DBG(GPT, ul_debug("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,
                                          unsigned char **_ents)
{
        struct gpt_header *header = NULL;
        unsigned char *ents = NULL;
        uint32_t hsz;

        if (!cxt)
                return NULL;

        /* always allocate all sector, the area after GPT header
         * has to be fill by zeros */
        assert(cxt->sector_size >= sizeof(struct gpt_header));

        header = calloc(1, cxt->sector_size);
        if (!header)
                return NULL;

        /* read and verify header */
        if (read_lba(cxt, lba, header, cxt->sector_size) != 0)
                goto invalid;

        if (!gpt_check_signature(header))
                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 (!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;

        if (_ents)
                *_ents = ents;
        else
                free(ents);

        DBG(GPT, ul_debug("found valid header on LBA %"PRIu64"", lba));
        return header;
invalid:
        free(header);
        free(ents);

        DBG(GPT, ul_debug("read header on LBA %"PRIu64" failed", lba));
        return NULL;
}


static int gpt_locate_disklabel(struct fdisk_context *cxt, int n,
                const char **name, uint64_t *offset, size_t *size)
{
        struct fdisk_gpt_label *gpt;

        assert(cxt);

        *name = NULL;
        *offset = 0;
        *size = 0;

        switch (n) {
        case 0:
                *name = "PMBR";
                *offset = 0;
                *size = 512;
                break;
        case 1:
                *name = _("GPT Header");
                *offset = (uint64_t) GPT_PRIMARY_PARTITION_TABLE_LBA * cxt->sector_size;
                *size = sizeof(struct gpt_header);
                break;
        case 2:
                *name = _("GPT Entries");
                gpt = self_label(cxt);
                *offset = (uint64_t) le64_to_cpu(gpt->pheader->partition_entry_lba) *
                                     cxt->sector_size;
                return gpt_sizeof_entries(gpt->pheader, size);
        case 3:
                *name = _("GPT Backup Entries");
                gpt = self_label(cxt);
                *offset = (uint64_t) le64_to_cpu(gpt->bheader->partition_entry_lba) *
                                     cxt->sector_size;
                return gpt_sizeof_entries(gpt->bheader, size);
        case 4:
                *name = _("GPT Backup Header");
                gpt = self_label(cxt);
                *offset = (uint64_t) le64_to_cpu(gpt->pheader->alternative_lba) * cxt->sector_size;
                *size = sizeof(struct gpt_header);
                break;
        default:
                return 1;                       /* no more chunks */
        }

        return 0;
}

static int gpt_get_disklabel_item(struct fdisk_context *cxt, struct fdisk_labelitem *item)
{
        struct gpt_header *h;
        int rc = 0;
        uint64_t x = 0;

        assert(cxt);
        assert(cxt->label);
        assert(fdisk_is_label(cxt, GPT));

        h = self_label(cxt)->pheader;

        switch (item->id) {
        case GPT_LABELITEM_ID:
                item->name = _("Disk identifier");
                item->type = 's';
                item->data.str = gpt_get_header_id(h);
                if (!item->data.str)
                        rc = -ENOMEM;
                break;
        case GPT_LABELITEM_FIRSTLBA:
                item->name = _("First usable LBA");
                item->type = 'j';
                item->data.num64 = le64_to_cpu(h->first_usable_lba);
                break;
        case GPT_LABELITEM_LASTLBA:
                item->name = _("Last usable LBA");
                item->type = 'j';
                item->data.num64 = le64_to_cpu(h->last_usable_lba);
                break;
        case GPT_LABELITEM_ALTLBA:
                /* TRANSLATORS: The LBA (Logical Block Address) of the backup GPT header. */
                item->name = _("Alternative LBA");
                item->type = 'j';
                item->data.num64 = le64_to_cpu(h->alternative_lba);
                break;
        case GPT_LABELITEM_ENTRIESLBA:
                /* TRANSLATORS: The start of the array of partition entries. */
                item->name = _("Partition entries starting LBA");
                item->type = 'j';
                item->data.num64 = le64_to_cpu(h->partition_entry_lba);
                break;
        case GPT_LABELITEM_ENTRIESLASTLBA:
                /* TRANSLATORS: The end of the array of partition entries. */
                item->name = _("Partition entries ending LBA");
                item->type = 'j';
                gpt_calculate_sectorsof_entries(h,
                                le32_to_cpu(h->npartition_entries), &x, cxt);
                item->data.num64 = le64_to_cpu(h->partition_entry_lba) + x - 1;
                break;
        case GPT_LABELITEM_ENTRIESALLOC:
                item->name = _("Allocated partition entries");
                item->type = 'j';
                item->data.num64 = le32_to_cpu(h->npartition_entries);
                break;
        default:
                if (item->id < __FDISK_NLABELITEMS)
                        rc = 1; /* unsupported generic item */
                else
                        rc = 2; /* out of range */
                break;
        }

        return rc;
}

/*
 * Returns the number of partitions that are in use.
 */
static size_t partitions_in_use(struct fdisk_gpt_label *gpt)
{
        size_t i, used = 0;

        assert(gpt);
        assert(gpt->pheader);
        assert(gpt->ents);

        for (i = 0; i < gpt_get_nentries(gpt); i++) {
                struct gpt_entry *e = gpt_get_entry(gpt, i);

                if (gpt_entry_is_used(e))
                        used++;
        }
        return used;
}


/*
 * Check if a partition is too big for the disk (sectors).
 * Returns the faulting partition number, otherwise 0.
 */
static uint32_t check_too_big_partitions(struct fdisk_gpt_label *gpt, uint64_t sectors)
{
        size_t i;

        assert(gpt);
        assert(gpt->pheader);
        assert(gpt->ents);

        for (i = 0; i < gpt_get_nentries(gpt); i++) {
                struct gpt_entry *e = gpt_get_entry(gpt, i);

                if (!gpt_entry_is_used(e))
                        continue;
                if (gpt_partition_end(e) >= sectors)
                        return i + 1;
        }

        return 0;
}

/*
 * Check if a partition ends before it begins
 * Returns the faulting partition number, otherwise 0.
 */
static uint32_t check_start_after_end_partitions(struct fdisk_gpt_label *gpt)
{
        size_t i;

        assert(gpt);
        assert(gpt->pheader);
        assert(gpt->ents);

        for (i = 0; i < gpt_get_nentries(gpt); i++) {
                struct gpt_entry *e = gpt_get_entry(gpt, i);

                if (!gpt_entry_is_used(e))
                        continue;
                if (gpt_partition_start(e) > gpt_partition_end(e))
                        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 partitions that overlap.
 */
static uint32_t check_overlap_partitions(struct fdisk_gpt_label *gpt)
{
        size_t i, j;

        assert(gpt);
        assert(gpt->pheader);
        assert(gpt->ents);

        for (i = 0; i < gpt_get_nentries(gpt); i++)
                for (j = 0; j < i; j++) {
                        struct gpt_entry *ei = gpt_get_entry(gpt, i);
                        struct gpt_entry *ej = gpt_get_entry(gpt, j);

                        if (!gpt_entry_is_used(ei) || !gpt_entry_is_used(ej))
                                continue;
                        if (partition_overlap(ei, ej)) {
                                DBG(GPT, ul_debug("partitions overlap detected [%zu vs. %zu]", i, j));
                                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 fdisk_gpt_label *gpt, uint64_t start)
{
        int first_moved = 0;
        uint64_t first;
        uint64_t fu, lu;

        assert(gpt);
        assert(gpt->pheader);
        assert(gpt->ents);

        fu = le64_to_cpu(gpt->pheader->first_usable_lba);
        lu = le64_to_cpu(gpt->pheader->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 {
                size_t i;

                first_moved = 0;
                for (i = 0; i < gpt_get_nentries(gpt); i++) {
                        struct gpt_entry *e = gpt_get_entry(gpt, i);

                        if (!gpt_entry_is_used(e))
                                continue;
                        if (first < gpt_partition_start(e))
                                continue;
                        if (first <= gpt_partition_end(e)) {
                                first = gpt_partition_end(e) + 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 fdisk_gpt_label *gpt, uint64_t start)
{
        size_t i;
        uint64_t nearest_start;

        assert(gpt);
        assert(gpt->pheader);
        assert(gpt->ents);

        nearest_start = le64_to_cpu(gpt->pheader->last_usable_lba);

        for (i = 0; i < gpt_get_nentries(gpt); i++) {
                struct gpt_entry *e = gpt_get_entry(gpt, i);
                uint64_t ps = gpt_partition_start(e);

                if (nearest_start > ps && ps > start)
                        nearest_start = ps - 1ULL;
        }

        return nearest_start;
}

/* Returns the last free sector on the disk. From gdisk. */
static uint64_t find_last_free_sector(struct fdisk_gpt_label *gpt)
{
        int last_moved;
        uint64_t last = 0;

        assert(gpt);
        assert(gpt->pheader);
        assert(gpt->ents);

        /* start by assuming the last usable LBA is available */
        last = le64_to_cpu(gpt->pheader->last_usable_lba);
        do {
                size_t i;

                last_moved = 0;
                for (i = 0; i < gpt_get_nentries(gpt); i++) {
                        struct gpt_entry *e = gpt_get_entry(gpt, i);

                        if (last >= gpt_partition_start(e) &&
                            last <= gpt_partition_end(e)) {
                                last = gpt_partition_start(e) - 1ULL;
                                last_moved = 1;
                        }
                }
        } while (last_moved == 1);

        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 fdisk_gpt_label *gpt)
{
        uint64_t start = 0, first_sect, last_sect;
        uint64_t segment_size, selected_size = 0, selected_segment = 0;

        assert(gpt);
        assert(gpt->pheader);
        assert(gpt->ents);

        do {
                first_sect = find_first_available(gpt, start);
                if (first_sect != 0) {
                        last_sect = find_last_free(gpt, first_sect);
                        segment_size = last_sect - first_sect + 1ULL;

                        if (segment_size > selected_size) {
                                selected_size = segment_size;
                                selected_segment = first_sect;
                        }
                        start = last_sect + 1ULL;
                }
        } while (first_sect != 0);

        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 fdisk_gpt_label *gpt,
                                 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;

        assert(gpt);
        assert(gpt->pheader);
        assert(gpt->ents);

        do {
                first_sect = find_first_available(gpt, start);
                if (first_sect) {
                        last_sect = find_last_free(gpt, 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 + 1ULL;
                }
        } 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)
{
        int mbr_type;
        struct fdisk_gpt_label *gpt;

        assert(cxt);
        assert(cxt->label);
        assert(fdisk_is_label(cxt, GPT));

        gpt = self_label(cxt);

        /* TODO: it would be nice to support scenario when GPT headers are OK,
         *       but PMBR is corrupt */
        mbr_type = valid_pmbr(cxt);
        if (!mbr_type)
                goto failed;

        /* primary header */
        gpt->pheader = gpt_read_header(cxt, GPT_PRIMARY_PARTITION_TABLE_LBA,
                                       &gpt->ents);

        if (gpt->pheader)
                /* primary OK, try backup from alternative LBA */
                gpt->bheader = gpt_read_header(cxt,
                                        le64_to_cpu(gpt->pheader->alternative_lba),
                                        NULL);
        else
                /* primary corrupted -- try last LBA */
                gpt->bheader = gpt_read_header(cxt, last_lba(cxt), &gpt->ents);

        if (!gpt->pheader && !gpt->bheader)
                goto failed;

        /* primary OK, backup corrupted -- recovery */
        if (gpt->pheader && !gpt->bheader) {
                fdisk_warnx(cxt, _("The backup GPT table is corrupt, but the "
                                  "primary appears OK, so that will be used."));
                gpt->bheader = gpt_copy_header(cxt, gpt->pheader);
                if (!gpt->bheader)
                        goto failed;
                gpt_recompute_crc(gpt->bheader, gpt->ents);
                fdisk_label_set_changed(cxt->label, 1);

        /* primary corrupted, backup OK -- recovery */
        } else if (!gpt->pheader && gpt->bheader) {
                fdisk_warnx(cxt, _("The primary GPT table is corrupt, but the "
                                  "backup appears OK, so that will be used."));
                gpt->pheader = gpt_copy_header(cxt, gpt->bheader);
                if (!gpt->pheader)
                        goto failed;
                gpt_recompute_crc(gpt->pheader, gpt->ents);
                fdisk_label_set_changed(cxt->label, 1);
        }

        /* The headers make be correct, but Backup do not have to be on the end
         * of the device (due to device resize, etc.). Let's fix this issue. */
        if (gpt->minimize == 0 &&
            (le64_to_cpu(gpt->pheader->alternative_lba) > cxt->total_sectors ||
             le64_to_cpu(gpt->pheader->alternative_lba) < cxt->total_sectors - 1ULL)) {

                if (gpt->no_relocate || fdisk_is_readonly(cxt))
                        fdisk_warnx(cxt, _("The backup GPT table is not on the end of the device."));

                else {
                        fdisk_warnx(cxt, _("The backup GPT table is not on the end of the device. "
                                           "This problem will be corrected by write."));

                        if (gpt_fix_alternative_lba(cxt, gpt) != 0)
                                fdisk_warnx(cxt, _("Failed to recalculate backup GPT table location"));
                        gpt_recompute_crc(gpt->bheader, gpt->ents);
                        gpt_recompute_crc(gpt->pheader, gpt->ents);
                        fdisk_label_set_changed(cxt->label, 1);
                }
        }

        if (gpt->minimize && gpt_possible_minimize(cxt, gpt))
                fdisk_label_set_changed(cxt->label, 1);

        cxt->label->nparts_max = gpt_get_nentries(gpt);
        cxt->label->nparts_cur = partitions_in_use(gpt);
        return 1;
failed:
        DBG(GPT, ul_debug("probe failed"));
        gpt_deinit(cxt->label);
        return 0;
}

static char *encode_to_utf8(unsigned char *src, size_t count)
{
        unsigned char *dest;
        size_t len = (count * 3 / 2) + 1;

        dest = calloc(1, len);
        if (!dest)
                return NULL;

        ul_encode_to_utf8(UL_ENCODE_UTF16LE, dest, len, src, count);
        return (char *) dest;
}

static int gpt_entry_attrs_to_string(struct gpt_entry *e, char **res)
{
        unsigned int n, count = 0;
        size_t l;
        char *bits, *p;
        uint64_t attrs;

        assert(e);
        assert(res);

        *res = NULL;
        attrs = e->attrs;
        if (!attrs)
                return 0;       /* no attributes at all */

        bits = (char *) &attrs;

        /* Note that sizeof() is correct here, we need separators between
         * the strings so also count \0 is correct */
        *res = calloc(1, sizeof(GPT_ATTRSTR_NOBLOCK) +
                         sizeof(GPT_ATTRSTR_REQ) +
                         sizeof(GPT_ATTRSTR_LEGACY) +
                         sizeof("GUID:") + (GPT_ATTRBIT_GUID_COUNT * 3));
        if (!*res)
                return -errno;

        p = *res;
        if (isset(bits, GPT_ATTRBIT_REQ)) {
                memcpy(p, GPT_ATTRSTR_REQ, (l = sizeof(GPT_ATTRSTR_REQ)));
                p += l - 1;
        }
        if (isset(bits, GPT_ATTRBIT_NOBLOCK)) {
                if (p != *res)
                        *p++ = ' ';
                memcpy(p, GPT_ATTRSTR_NOBLOCK, (l = sizeof(GPT_ATTRSTR_NOBLOCK)));
                p += l - 1;
        }
        if (isset(bits, GPT_ATTRBIT_LEGACY)) {
                if (p != *res)
                        *p++ = ' ';
                memcpy(p, GPT_ATTRSTR_LEGACY, (l = sizeof(GPT_ATTRSTR_LEGACY)));
                p += l - 1;
        }

        for (n = GPT_ATTRBIT_GUID_FIRST;
             n < GPT_ATTRBIT_GUID_FIRST + GPT_ATTRBIT_GUID_COUNT; n++) {

                if (!isset(bits, n))
                        continue;
                if (!count) {
                        if (p != *res)
                                *p++ = ' ';
                        p += sprintf(p, "GUID:%u", n);
                } else
                        p += sprintf(p, ",%u", n);
                count++;
        }

        return 0;
}

static int gpt_entry_attrs_from_string(
                        struct fdisk_context *cxt,
                        struct gpt_entry *e,
                        const char *str)
{
        const char *p = str;
        uint64_t attrs = 0;
        char *bits;

        assert(e);
        assert(p);

        DBG(GPT, ul_debug("parsing string attributes '%s'", p));

        bits = (char *) &attrs;

        while (p && *p) {
                int bit = -1;

                while (isblank(*p)) p++;
                if (!*p)
                        break;

                DBG(GPT, ul_debug(" item '%s'", p));

                if (strncmp(p, GPT_ATTRSTR_REQ,
                                        sizeof(GPT_ATTRSTR_REQ) - 1) == 0) {
                        bit = GPT_ATTRBIT_REQ;
                        p += sizeof(GPT_ATTRSTR_REQ) - 1;
                } else if (strncmp(p, GPT_ATTRSTR_REQ_TYPO,
                                        sizeof(GPT_ATTRSTR_REQ_TYPO) - 1) == 0) {
                        bit = GPT_ATTRBIT_REQ;
                        p += sizeof(GPT_ATTRSTR_REQ_TYPO) - 1;
                } else if (strncmp(p, GPT_ATTRSTR_LEGACY,
                                        sizeof(GPT_ATTRSTR_LEGACY) - 1) == 0) {
                        bit = GPT_ATTRBIT_LEGACY;
                        p += sizeof(GPT_ATTRSTR_LEGACY) - 1;
                } else if (strncmp(p, GPT_ATTRSTR_NOBLOCK,
                                        sizeof(GPT_ATTRSTR_NOBLOCK) - 1) == 0) {
                        bit = GPT_ATTRBIT_NOBLOCK;
                        p += sizeof(GPT_ATTRSTR_NOBLOCK) - 1;

                /* GUID:<bit> as well as <bit> */
                } else if (isdigit((unsigned char) *p)
                           || (strncmp(p, "GUID:", 5) == 0
                               && isdigit((unsigned char) *(p + 5)))) {
                        char *end = NULL;

                        if (*p == 'G')
                                p += 5;

                        errno = 0;
                        bit = strtol(p, &end, 0);
                        if (errno || !end || end == str
                            || bit < GPT_ATTRBIT_GUID_FIRST
                            || bit >= GPT_ATTRBIT_GUID_FIRST + GPT_ATTRBIT_GUID_COUNT)
                                bit = -1;
                        else
                                p = end;
                }

                if (bit < 0) {
                        fdisk_warnx(cxt, _("unsupported GPT attribute bit '%s'"), p);
                        return -EINVAL;
                }

                if (*p && *p != ',' && !isblank(*p)) {
                        fdisk_warnx(cxt, _("failed to parse GPT attribute string '%s'"), str);
                        return -EINVAL;
                }

                setbit(bits, bit);

                while (isblank(*p)) p++;
                if (*p == ',')
                        p++;
        }

        e->attrs = attrs;
        return 0;
}

static int gpt_get_partition(struct fdisk_context *cxt, size_t n,
                             struct fdisk_partition *pa)
{
        struct fdisk_gpt_label *gpt;
        struct gpt_entry *e;
        char u_str[UUID_STR_LEN];
        int rc = 0;
        struct gpt_guid guid;

        assert(cxt);
        assert(cxt->label);
        assert(fdisk_is_label(cxt, GPT));

        gpt = self_label(cxt);

        if (n >= gpt_get_nentries(gpt))
                return -EINVAL;

        gpt = self_label(cxt);
        e = gpt_get_entry(gpt, n);

        pa->used = gpt_entry_is_used(e) || gpt_partition_start(e);
        if (!pa->used)
                return 0;

        pa->start = gpt_partition_start(e);
        pa->size = gpt_partition_size(e);
        pa->type = gpt_partition_parttype(cxt, e);

        guid = e->partition_guid;
        if (guid_to_string(&guid, u_str)) {
                pa->uuid = strdup(u_str);
                if (!pa->uuid) {
                        rc = -errno;
                        goto done;
                }
        } else
                pa->uuid = NULL;

        rc = gpt_entry_attrs_to_string(e, &pa->attrs);
        if (rc)
                goto done;

        pa->name = encode_to_utf8((unsigned char *)e->name, sizeof(e->name));
        return 0;
done:
        fdisk_reset_partition(pa);
        return rc;
}


static int gpt_set_partition(struct fdisk_context *cxt, size_t n,
                             struct fdisk_partition *pa)
{
        struct fdisk_gpt_label *gpt;
        struct gpt_entry *e;
        int rc = 0;
        uint64_t start, end;

        assert(cxt);
        assert(cxt->label);
        assert(fdisk_is_label(cxt, GPT));

        gpt = self_label(cxt);

        if (n >= gpt_get_nentries(gpt))
                return -EINVAL;

        FDISK_INIT_UNDEF(start);
        FDISK_INIT_UNDEF(end);

        gpt = self_label(cxt);
        e = gpt_get_entry(gpt, n);

        if (pa->uuid) {
                char new_u[UUID_STR_LEN], old_u[UUID_STR_LEN];
                struct gpt_guid guid;

                guid = e->partition_guid;
                guid_to_string(&guid, old_u);
                rc = gpt_entry_set_uuid(e, pa->uuid);
                if (rc)
                        return rc;
                guid = e->partition_guid;
                guid_to_string(&guid, new_u);
                fdisk_info(cxt, _("Partition UUID changed from %s to %s."),
                        old_u, new_u);
        }

        if (pa->name) {
                int len;
                char *old = encode_to_utf8((unsigned char *)e->name, sizeof(e->name));
                len = gpt_entry_set_name(e, pa->name);
                if (len < 0)
                        fdisk_warn(cxt, _("Failed to translate partition name, name not changed."));
                else
                        fdisk_info(cxt, _("Partition name changed from '%s' to '%.*s'."),
                                old, len, pa->name);
                free(old);
        }

        if (pa->type && pa->type->typestr) {
                struct gpt_guid typeid;

                rc = string_to_guid(pa->type->typestr, &typeid);
                if (rc)
                        return rc;
                gpt_entry_set_type(e, &typeid);
        }
        if (pa->attrs) {
                rc = gpt_entry_attrs_from_string(cxt, e, pa->attrs);
                if (rc)
                        return rc;
        }

        if (fdisk_partition_has_start(pa))
                start = pa->start;
        if (fdisk_partition_has_size(pa) || fdisk_partition_has_start(pa)) {
                uint64_t xstart = fdisk_partition_has_start(pa) ? pa->start : gpt_partition_start(e);
                uint64_t xsize  = fdisk_partition_has_size(pa)  ? pa->size  : gpt_partition_size(e);
                end = xstart + xsize - 1ULL;
        }

        if (!FDISK_IS_UNDEF(start)) {
                if (start < le64_to_cpu(gpt->pheader->first_usable_lba)) {
                        fdisk_warnx(cxt, _("The start of the partition understeps FirstUsableLBA."));
                        return -EINVAL;
                }
                e->lba_start = cpu_to_le64(start);
        }
        if (!FDISK_IS_UNDEF(end)) {
                if (end > le64_to_cpu(gpt->pheader->last_usable_lba)) {
                        fdisk_warnx(cxt, _("The end of the partition oversteps LastUsableLBA."));
                        return -EINVAL;
                }
                e->lba_end = cpu_to_le64(end);
        }
        gpt_recompute_crc(gpt->pheader, gpt->ents);
        gpt_recompute_crc(gpt->bheader, gpt->ents);

        fdisk_label_set_changed(cxt->label, 1);
        return rc;
}

static int gpt_read(struct fdisk_context *cxt, off_t offset, void *buf, size_t count)
{
        if (offset != lseek(cxt->dev_fd, offset, SEEK_SET))
                return -errno;

        if (read_all(cxt->dev_fd, buf, count))
                return -errno;

        DBG(GPT, ul_debug("  read OK [offset=%zu, size=%zu]",
                                (size_t) offset, count));
        return 0;
}

static int gpt_write(struct fdisk_context *cxt, off_t offset, void *buf, size_t count)
{
        if (offset != lseek(cxt->dev_fd, offset, SEEK_SET))
                return -errno;

        if (write_all(cxt->dev_fd, buf, count))
                return -errno;

        if (fsync(cxt->dev_fd) != 0)
                return -errno;

        DBG(GPT, ul_debug("  write OK [offset=%zu, size=%zu]",
                                (size_t) offset, count));
        return 0;
}

/*
 * Write partitions.
 * Returns 0 on success, or corresponding error otherwise.
 */
static int gpt_write_partitions(struct fdisk_context *cxt,
                                struct gpt_header *header, unsigned char *ents)
{
        size_t esz = 0;
        int rc;

        rc = gpt_sizeof_entries(header, &esz);
        if (rc)
                return rc;

        return gpt_write(cxt,
                        (off_t) le64_to_cpu(header->partition_entry_lba) * cxt->sector_size,
                        ents, esz);
}

/*
 * Write a GPT header to a specified LBA.
 *
 * We read all sector, so we have to write all sector back
 * to the device -- never ever rely on sizeof(struct gpt_header)!
 *
 * Returns 0 on success, or corresponding error otherwise.
 */
static int gpt_write_header(struct fdisk_context *cxt,
                            struct gpt_header *header, uint64_t lba)
{
        return gpt_write(cxt, lba * cxt->sector_size, header, cxt->sector_size);
}

/*
 * Write the protective MBR.
 * Returns 0 on success, or corresponding error otherwise.
 */
static int gpt_write_pmbr(struct fdisk_context *cxt)
{
        struct gpt_legacy_mbr *pmbr;
        struct gpt_legacy_mbr *current;
        int rc;

        assert(cxt);
        assert(cxt->firstsector);

        DBG(GPT, ul_debug("(over)writing PMBR"));
        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 = 2;
        pmbr->partition_record[0].end_head     = 0xFF;
        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 - 1ULL > 0xFFFFFFFFULL)
                pmbr->partition_record[0].size_in_lba = cpu_to_le32(0xFFFFFFFF);
        else
                pmbr->partition_record[0].size_in_lba =
                        cpu_to_le32((uint32_t) (cxt->total_sectors - 1ULL));

        /* Read the current PMBR and compare it with the new, don't write if
         * the same. */
        current = malloc(sizeof(*current));
        if (!current)
                goto do_write;

        rc = gpt_read(cxt, GPT_PMBR_LBA * cxt->sector_size,
                      current, sizeof(*current));
        if (!rc)
                rc = memcmp(pmbr, current, sizeof(*current));

        free(current);

        if (!rc) {
                DBG(GPT, ul_debug("Same MBR on disk => don't write it"));
                return 0;
        }

 do_write:
        /* pMBR covers the first sector (LBA) of the disk */
        return gpt_write(cxt, GPT_PMBR_LBA * cxt->sector_size,
                         pmbr, cxt->sector_size);
}

/*
 * 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_gpt_label *gpt;
        int mbr_type;

        assert(cxt);
        assert(cxt->label);
        assert(fdisk_is_label(cxt, GPT));

        DBG(GPT, ul_debug("writing..."));

        gpt = self_label(cxt);
        mbr_type = valid_pmbr(cxt);

        /* check that disk is big enough to handle the backup header */
        if (le64_to_cpu(gpt->pheader->alternative_lba) > cxt->total_sectors)
                goto err0;

        /* check that the backup header is properly placed */
        if (le64_to_cpu(gpt->pheader->alternative_lba) < cxt->total_sectors - 1ULL)
                goto err0;

        if (check_overlap_partitions(gpt))
                goto err0;

        if (gpt->minimize)
                gpt_minimize_alternative_lba(cxt, gpt);

        /* 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,
                             le64_to_cpu(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 (mbr_type == GPT_MBR_HYBRID)
                fdisk_warnx(cxt, _("The device contains hybrid MBR -- writing GPT only."));
        else if (gpt_write_pmbr(cxt) != 0)
                goto err1;

        DBG(GPT, ul_debug("...write success"));
        return 0;
err0:
        DBG(GPT, ul_debug("...write failed: incorrect input"));
        errno = EINVAL;
        return -EINVAL;
err1:
        DBG(GPT, ul_debug("...write failed: %m"));
        return -errno;
}

/*
 * Verify data integrity and report any found problems for:
 *   - primary and backup header validations
 *   - partition validations
 */
static int gpt_verify_disklabel(struct fdisk_context *cxt)
{
        int nerror = 0;
        unsigned int ptnum;
        struct fdisk_gpt_label *gpt;

        assert(cxt);
        assert(cxt->label);
        assert(fdisk_is_label(cxt, GPT));

        gpt = self_label(cxt);
        if (!gpt)
                return -EINVAL;

        if (!gpt->bheader) {
                nerror++;
                fdisk_warnx(cxt, _("Disk does not contain a valid backup header."));
        }

        if (!gpt_check_header_crc(gpt->pheader, gpt->ents)) {
                nerror++;
                fdisk_warnx(cxt, _("Invalid primary header CRC checksum."));
        }
        if (gpt->bheader && !gpt_check_header_crc(gpt->bheader, gpt->ents)) {
                nerror++;
                fdisk_warnx(cxt, _("Invalid backup header CRC checksum."));
        }

        if (!gpt_check_entryarr_crc(gpt->pheader, gpt->ents)) {
                nerror++;
                fdisk_warnx(cxt, _("Invalid partition entry checksum."));
        }

        if (!gpt_check_lba_sanity(cxt, gpt->pheader)) {
                nerror++;
                fdisk_warnx(cxt, _("Invalid primary header LBA sanity checks."));
        }
        if (gpt->bheader && !gpt_check_lba_sanity(cxt, gpt->bheader)) {
                nerror++;
                fdisk_warnx(cxt, _("Invalid backup header LBA sanity checks."));
        }

        if (le64_to_cpu(gpt->pheader->my_lba) != GPT_PRIMARY_PARTITION_TABLE_LBA) {
                nerror++;
                fdisk_warnx(cxt, _("MyLBA mismatch with real position at primary header."));
        }
        if (gpt->bheader && le64_to_cpu(gpt->bheader->my_lba) != last_lba(cxt)) {
                nerror++;
                fdisk_warnx(cxt, _("MyLBA mismatch with real position at backup header."));

        }
        if (le64_to_cpu(gpt->pheader->alternative_lba) >= cxt->total_sectors) {
                nerror++;
                fdisk_warnx(cxt, _("Disk is too small to hold all data."));
        }

        /*
         * if the GPT is the primary table, check the alternateLBA
         * to see if it is a valid GPT
         */
        if (gpt->bheader && (le64_to_cpu(gpt->pheader->my_lba) !=
                             le64_to_cpu(gpt->bheader->alternative_lba))) {
                nerror++;
                fdisk_warnx(cxt, _("Primary and backup header mismatch."));
        }

        ptnum = check_overlap_partitions(gpt);
        if (ptnum) {
                nerror++;
                fdisk_warnx(cxt, _("Partition %u overlaps with partition %u."),
                                ptnum, ptnum+1);
        }

        ptnum = check_too_big_partitions(gpt, cxt->total_sectors);
        if (ptnum) {
                nerror++;
                fdisk_warnx(cxt, _("Partition %u is too big for the disk."),
                                ptnum);
        }

        ptnum = check_start_after_end_partitions(gpt);
        if (ptnum) {
                nerror++;
                fdisk_warnx(cxt, _("Partition %u ends before it starts."),
                                ptnum);
        }

        if (!nerror) { /* yay :-) */
                uint32_t nsegments = 0;
                uint64_t free_sectors = 0, largest_segment = 0;
                char *strsz = NULL;

                fdisk_info(cxt, _("No errors detected."));
                fdisk_info(cxt, _("Header version: %s"), gpt_get_header_revstr(gpt->pheader));
                fdisk_info(cxt, _("Using %zu out of %zu partitions."),
                       partitions_in_use(gpt),
                       gpt_get_nentries(gpt));

                free_sectors = get_free_sectors(cxt, gpt, &nsegments, &largest_segment);
                if (largest_segment)
                        strsz = size_to_human_string(SIZE_SUFFIX_SPACE | SIZE_SUFFIX_3LETTER,
                                        largest_segment * cxt->sector_size);

                fdisk_info(cxt,
                           P_("A total of %ju free sectors is available in %u segment.",
                              "A total of %ju free sectors is available in %u segments "
                              "(the largest is %s).", nsegments),
                           free_sectors, nsegments, strsz ? : "0 B");
                free(strsz);

        } else
                fdisk_warnx(cxt,
                        P_("%d error detected.", "%d errors detected.", nerror),
                        nerror);

        return nerror;
}

/* Delete a single GPT partition, specified by partnum. */
static int gpt_delete_partition(struct fdisk_context *cxt,
                                size_t partnum)
{
        struct fdisk_gpt_label *gpt;

        assert(cxt);
        assert(cxt->label);
        assert(fdisk_is_label(cxt, GPT));

        gpt = self_label(cxt);

        if (partnum >= cxt->label->nparts_max)
                return -EINVAL;

        if (!gpt_entry_is_used(gpt_get_entry(gpt, partnum)))
                return -EINVAL;

        /* hasta la vista, baby! */
        gpt_zeroize_entry(gpt, partnum);

        gpt_recompute_crc(gpt->pheader, gpt->ents);
        gpt_recompute_crc(gpt->bheader, gpt->ents);
        cxt->label->nparts_cur--;
        fdisk_label_set_changed(cxt->label, 1);

        return 0;
}


/* Performs logical checks to add a new partition entry */
static int gpt_add_partition(
                struct fdisk_context *cxt,
                struct fdisk_partition *pa,
                size_t *partno)
{
        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, max_l; /* largest segment (default) */
        struct gpt_guid typeid;
        struct fdisk_gpt_label *gpt;
        struct gpt_header *pheader;
        struct gpt_entry *e;
        struct fdisk_ask *ask = NULL;
        size_t partnum;
        int rc;

        assert(cxt);
        assert(cxt->label);
        assert(fdisk_is_label(cxt, GPT));

        gpt = self_label(cxt);

        assert(gpt);
        assert(gpt->pheader);
        assert(gpt->ents);

        pheader = gpt->pheader;

        rc = fdisk_partition_next_partno(pa, cxt, &partnum);
        if (rc) {
                DBG(GPT, ul_debug("failed to get next partno"));
                return rc;
        }

        assert(partnum < gpt_get_nentries(gpt));

        if (gpt_entry_is_used(gpt_get_entry(gpt, partnum))) {
                fdisk_warnx(cxt, _("Partition %zu is already defined.  "
                                   "Delete it before re-adding it."), partnum +1);
                return -ERANGE;
        }
        if (gpt_get_nentries(gpt) == partitions_in_use(gpt)) {
                fdisk_warnx(cxt, _("All partitions are already in use."));
                return -ENOSPC;
        }
        if (!get_free_sectors(cxt, gpt, NULL, NULL)) {
                fdisk_warnx(cxt, _("No free sectors available."));
                return -ENOSPC;
        }

        rc = string_to_guid(pa && pa->type && pa->type->typestr ?
                                pa->type->typestr:
                                GPT_DEFAULT_ENTRY_TYPE, &typeid);
        if (rc)
                return rc;

        disk_f = find_first_available(gpt, le64_to_cpu(pheader->first_usable_lba));
        e = gpt_get_entry(gpt, 0);

        /* if first sector no explicitly defined then ignore small gaps before
         * the first partition */
        if ((!pa || !fdisk_partition_has_start(pa))
            && gpt_entry_is_used(e)
            && disk_f < gpt_partition_start(e)) {

                do {
                        uint64_t x;
                        DBG(GPT, ul_debug("testing first sector %"PRIu64"", disk_f));
                        disk_f = find_first_available(gpt, disk_f);
                        if (!disk_f)
                                break;
                        x = find_last_free(gpt, disk_f);
                        if (x - disk_f >= cxt->grain / cxt->sector_size)
                                break;
                        DBG(GPT, ul_debug("first sector %"PRIu64" addresses to small space, continue...", disk_f));
                        disk_f = x + 1ULL;
                } while(1);

                if (disk_f == 0)
                        disk_f = find_first_available(gpt, le64_to_cpu(pheader->first_usable_lba));
        }

        e = NULL;
        disk_l = find_last_free_sector(gpt);

        /* the default is the largest free space */
        dflt_f = find_first_in_largest(gpt);
        dflt_l = find_last_free(gpt, dflt_f);

        /* don't offer too small free space by default, this is possible to
         * bypass by sfdisk script */
        if ((!pa || !fdisk_partition_has_start(pa))
            && dflt_l - dflt_f + 1 < cxt->grain / cxt->sector_size) {
                fdisk_warnx(cxt, _("No enough free sectors available."));
                return -ENOSPC;
        }

        /* align the default in range <dflt_f,dflt_l>*/
        dflt_f = fdisk_align_lba_in_range(cxt, dflt_f, dflt_f, dflt_l);

        /* first sector */
        if (pa && pa->start_follow_default) {
                user_f = dflt_f;

        } else if (pa && fdisk_partition_has_start(pa)) {
                DBG(GPT, ul_debug("first sector defined: %ju",  (uintmax_t)pa->start));
                if (pa->start != find_first_available(gpt, pa->start)) {
                        fdisk_warnx(cxt, _("Sector %ju already used."),  (uintmax_t)pa->start);
                        return -ERANGE;
                }
                user_f = pa->start;
        } else {
                /*  ask by dialog */
                for (;;) {
                        if (!ask)
                                ask = fdisk_new_ask();
                        else
                                fdisk_reset_ask(ask);
                        if (!ask)
                                return -ENOMEM;

                        /* First sector */
                        fdisk_ask_set_query(ask, _("First sector"));
                        fdisk_ask_set_type(ask, FDISK_ASKTYPE_NUMBER);
                        fdisk_ask_number_set_low(ask,     disk_f);      /* minimal */
                        fdisk_ask_number_set_default(ask, dflt_f);      /* default */
                        fdisk_ask_number_set_high(ask,    disk_l);      /* maximal */

                        rc = fdisk_do_ask(cxt, ask);
                        if (rc)
                                goto done;

                        user_f = fdisk_ask_number_get_result(ask);
                        if (user_f != find_first_available(gpt, user_f)) {
                                fdisk_warnx(cxt, _("Sector %ju already used."), user_f);
                                continue;
                        }
                        break;
                }
        }


        /* Last sector */
        dflt_l = max_l = find_last_free(gpt, user_f);

        /* Make sure the last partition has aligned size by default because
         * range specified by LastUsableLBA may be unaligned on disks where
         * logical sector != physical (512/4K) because backup header size is
         * calculated from logical sectors. */
        if (max_l == le64_to_cpu(gpt->pheader->last_usable_lba))
                dflt_l = fdisk_align_lba_in_range(cxt, max_l, user_f, max_l) - 1;

        if (pa && pa->end_follow_default) {
                user_l = dflt_l;

        } else if (pa && fdisk_partition_has_size(pa)) {
                user_l = user_f + pa->size - 1;
                DBG(GPT, ul_debug("size defined: %ju, end: %"PRIu64
                                  "(last possible: %"PRIu64", optimal: %"PRIu64")",
                                (uintmax_t)pa->size, user_l, max_l, dflt_l));

                if (user_l != dflt_l
                    && !pa->size_explicit
                    && alignment_required(cxt)
                    && user_l - user_f > (cxt->grain / fdisk_get_sector_size(cxt))) {

                        user_l = fdisk_align_lba_in_range(cxt, user_l, user_f, dflt_l);
                        if (user_l > user_f)
                                user_l -= 1ULL;
                }
        } else {
                for (;;) {
                        if (!ask)
                                ask = fdisk_new_ask();
                        else
                                fdisk_reset_ask(ask);
                        if (!ask)
                                return -ENOMEM;

                        fdisk_ask_set_query(ask, _("Last sector, +/-sectors or +/-size{K,M,G,T,P}"));
                        fdisk_ask_set_type(ask, FDISK_ASKTYPE_OFFSET);
                        fdisk_ask_number_set_low(ask,     user_f);      /* minimal */
                        fdisk_ask_number_set_default(ask, dflt_l);      /* default */
                        fdisk_ask_number_set_high(ask,    max_l);       /* maximal */
                        fdisk_ask_number_set_base(ask,    user_f);      /* base for relative input */
                        fdisk_ask_number_set_unit(ask,    cxt->sector_size);
                        fdisk_ask_number_set_wrap_negative(ask, 1);     /* wrap negative around high */

                        rc = fdisk_do_ask(cxt, ask);
                        if (rc)
                                goto done;

                        user_l = fdisk_ask_number_get_result(ask);
                        if (fdisk_ask_number_is_relative(ask)) {
                                user_l = fdisk_align_lba_in_range(cxt, user_l, user_f, dflt_l);
                                if (user_l > user_f)
                                        user_l -= 1ULL;
                        }

                        if (user_l >= user_f && user_l <= disk_l)
                                break;

                        fdisk_warnx(cxt, _("Value out of range."));
                }
        }


        if (user_f > user_l || partnum >= cxt->label->nparts_max) {
                fdisk_warnx(cxt, _("Could not create partition %zu"), partnum + 1);
                rc = -EINVAL;
                goto done;
        }

        /* Be paranoid and check against on-disk setting rather than against libfdisk cxt */
        if (user_l > le64_to_cpu(pheader->last_usable_lba)) {
                fdisk_warnx(cxt, _("The last usable GPT sector is %ju, but %ju is requested."),
                                le64_to_cpu(pheader->last_usable_lba), user_l);
                rc = -EINVAL;
                goto done;
        }

        if (user_f < le64_to_cpu(pheader->first_usable_lba)) {
                fdisk_warnx(cxt, _("The first usable GPT sector is %ju, but %ju is requested."),
                                le64_to_cpu(pheader->first_usable_lba), user_f);
                rc = -EINVAL;
                goto done;
        }

        assert(!FDISK_IS_UNDEF(user_l));
        assert(!FDISK_IS_UNDEF(user_f));
        assert(partnum < gpt_get_nentries(gpt));

        e = gpt_get_entry(gpt, partnum);
        e->lba_end = cpu_to_le64(user_l);
        e->lba_start = cpu_to_le64(user_f);

        gpt_entry_set_type(e, &typeid);

        if (pa && pa->uuid) {
                /* Sometimes it's necessary to create a copy of the PT and
                 * reuse already defined UUID
                 */
                rc = gpt_entry_set_uuid(e, pa->uuid);
                if (rc)
                        goto done;
        } else {
                /* 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.
                 */
                struct gpt_guid guid;

                uuid_generate_random((unsigned char *) &guid);
                swap_efi_guid(&guid);
                e->partition_guid = guid;
        }

        if (pa && pa->name && *pa->name)
                gpt_entry_set_name(e, pa->name);
        if (pa && pa->attrs)
                gpt_entry_attrs_from_string(cxt, e, pa->attrs);

        DBG(GPT, ul_debug("new partition: partno=%zu, start=%"PRIu64", end=%"PRIu64", size=%"PRIu64"",
                                partnum,
                                gpt_partition_start(e),
                                gpt_partition_end(e),
                                gpt_partition_size(e)));

        gpt_recompute_crc(gpt->pheader, gpt->ents);
        gpt_recompute_crc(gpt->bheader, gpt->ents);

        /* report result */
        {
                struct fdisk_parttype *t;

                cxt->label->nparts_cur++;
                fdisk_label_set_changed(cxt->label, 1);

                t = gpt_partition_parttype(cxt, e);
                fdisk_info_new_partition(cxt, partnum + 1, user_f, user_l, t);
                fdisk_unref_parttype(t);
        }

        rc = 0;
        if (partno)
                *partno = partnum;
done:
        fdisk_unref_ask(ask);
        return rc;
}

/*
 * Create a new GPT disklabel - destroys any previous data.
 */
static int gpt_create_disklabel(struct fdisk_context *cxt)
{
        int rc = 0;
        size_t esz = 0;
        char str[UUID_STR_LEN];
        struct fdisk_gpt_label *gpt;
        struct gpt_guid guid;

        assert(cxt);
        assert(cxt->label);
        assert(fdisk_is_label(cxt, GPT));

        gpt = self_label(cxt);

        /* label private stuff has to be empty, see gpt_deinit() */
        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;

        assert(cxt->sector_size >= sizeof(struct gpt_header));

        /* primary */
        gpt->pheader = calloc(1, cxt->sector_size);
        if (!gpt->pheader) {
                rc = -ENOMEM;
                goto done;
        }
        rc = gpt_mknew_header(cxt, gpt->pheader, GPT_PRIMARY_PARTITION_TABLE_LBA);
        if (rc < 0)
                goto done;

        /* backup ("copy" primary) */
        gpt->bheader = calloc(1, cxt->sector_size);
        if (!gpt->bheader) {
                rc = -ENOMEM;
                goto done;
        }
        rc = gpt_mknew_header_from_bkp(cxt, gpt->bheader,
                        last_lba(cxt), gpt->pheader);
        if (rc < 0)
                goto done;

        rc = gpt_sizeof_entries(gpt->pheader, &esz);
        if (rc)
                goto done;
        gpt->ents = calloc(1, esz);
        if (!gpt->ents) {
                rc = -ENOMEM;
                goto done;
        }
        gpt_recompute_crc(gpt->pheader, gpt->ents);
        gpt_recompute_crc(gpt->bheader, gpt->ents);

        cxt->label->nparts_max = gpt_get_nentries(gpt);
        cxt->label->nparts_cur = 0;

        guid = gpt->pheader->disk_guid;
        guid_to_string(&guid, str);
        fdisk_label_set_changed(cxt->label, 1);
        fdisk_info(cxt, _("Created a new GPT disklabel (GUID: %s)."), str);

        if (gpt_get_nentries(gpt) < GPT_NPARTITIONS)
                fdisk_info(cxt, _("The maximal number of partitions is %zu (default is %zu)."),
                                gpt_get_nentries(gpt), GPT_NPARTITIONS);
done:
        return rc;
}

static int gpt_set_disklabel_id(struct fdisk_context *cxt, const char *str)
{
        struct fdisk_gpt_label *gpt;
        struct gpt_guid uuid;
        char *old, *new;
        int rc;

        assert(cxt);
        assert(cxt->label);
        assert(fdisk_is_label(cxt, GPT));

        gpt = self_label(cxt);
        if (!str) {
                char *buf = NULL;

                if (fdisk_ask_string(cxt,
                                _("Enter new disk UUID (in 8-4-4-4-12 format)"), &buf))
                        return -EINVAL;
                rc = string_to_guid(buf, &uuid);
                free(buf);
        } else
                rc = string_to_guid(str, &uuid);

        if (rc) {
                fdisk_warnx(cxt, _("Failed to parse your UUID."));
                return rc;
        }

        old = gpt_get_header_id(gpt->pheader);

        gpt->pheader->disk_guid = uuid;
        gpt->bheader->disk_guid = uuid;

        gpt_recompute_crc(gpt->pheader, gpt->ents);
        gpt_recompute_crc(gpt->bheader, gpt->ents);

        new = gpt_get_header_id(gpt->pheader);

        fdisk_info(cxt, _("Disk identifier changed from %s to %s."), old, new);

        free(old);
        free(new);
        fdisk_label_set_changed(cxt->label, 1);
        return 0;
}

static int gpt_check_table_overlap(struct fdisk_context *cxt,
                                   uint64_t first_usable,
                                   uint64_t last_usable)
{
        struct fdisk_gpt_label *gpt = self_label(cxt);
        size_t i;
        int rc = 0;

        /* First check if there's enough room for the table. last_lba may have wrapped */
        if (first_usable > cxt->total_sectors || /* far too little space */
            last_usable > cxt->total_sectors || /* wrapped */
            first_usable > last_usable) { /* too little space */
                fdisk_warnx(cxt, _("Not enough space for new partition table!"));
                return -ENOSPC;
        }

        /* check that all partitions fit in the remaining space */
        for (i = 0; i < gpt_get_nentries(gpt); i++) {
                struct gpt_entry *e = gpt_get_entry(gpt, i);

                if (!gpt_entry_is_used(e))
                        continue;
                if (gpt_partition_start(e) < first_usable) {
                        fdisk_warnx(cxt, _("Partition #%zu out of range (minimal start is %"PRIu64" sectors)"),
                                    i + 1, first_usable);
                        rc = -EINVAL;
                }
                if (gpt_partition_end(e) > last_usable) {
                        fdisk_warnx(cxt, _("Partition #%zu out of range (maximal end is %"PRIu64" sectors)"),
                                    i + 1, last_usable - (uint64_t) 1);
                        rc = -EINVAL;
                }
        }
        return rc;
}

/**
 * fdisk_gpt_set_npartitions:
 * @cxt: context
 * @nents: number of wanted entries
 *
 * Enlarge GPT entries array if possible. The function check if an existing
 * partition does not overlap the entries array area. If yes, then it report
 * warning and returns -EINVAL.
 *
 * Returns: 0 on success, < 0 on error.
 * Since: 2.29
 */
int fdisk_gpt_set_npartitions(struct fdisk_context *cxt, uint32_t nents)
{
        struct fdisk_gpt_label *gpt;
        size_t new_size = 0;
        uint32_t old_nents;
        uint64_t first_usable = 0ULL, last_usable = 0ULL;
        int rc;

        assert(cxt);
        assert(cxt->label);

        if (!fdisk_is_label(cxt, GPT))
                return -EINVAL;

        gpt = self_label(cxt);

        old_nents = le32_to_cpu(gpt->pheader->npartition_entries);
        if (old_nents == nents)
                return 0;       /* do nothing, say nothing */

        /* calculate the size (bytes) of the entries array */
        rc = gpt_calculate_sizeof_entries(gpt->pheader, nents, &new_size);
        if (rc) {
                uint32_t entry_size = le32_to_cpu(gpt->pheader->sizeof_partition_entry);

                if (entry_size == 0)
                        fdisk_warnx(cxt, _("The partition entry size is zero."));
                else
                        fdisk_warnx(cxt, _("The number of the partition has to be smaller than %zu."),
                                (size_t) UINT32_MAX / entry_size);
                return rc;
        }

        rc = gpt_calculate_first_lba(gpt->pheader, nents, &first_usable, cxt);
        if (rc == 0)
                rc = gpt_calculate_last_lba(gpt->pheader, nents, &last_usable, cxt);
        if (rc)
                return rc;

        /* if expanding the table, first check that everything fits,
         * then allocate more memory and zero. */
        if (nents > old_nents) {
                unsigned char *ents;
                size_t old_size = 0;

                rc = gpt_calculate_sizeof_entries(gpt->pheader, old_nents, &old_size);
                if (rc == 0)
                        rc = gpt_check_table_overlap(cxt, first_usable, last_usable);
                if (rc)
                        return rc;
                ents = realloc(gpt->ents, new_size);
                if (!ents) {
                        fdisk_warnx(cxt, _("Cannot allocate memory!"));
                        return -ENOMEM;
                }
                memset(ents + old_size, 0, new_size - old_size);
                gpt->ents = ents;
        }

        /* everything's ok, apply the new size */
        gpt->pheader->npartition_entries = cpu_to_le32(nents);
        gpt->bheader->npartition_entries = cpu_to_le32(nents);

        /* usable LBA addresses will have changed */
        fdisk_set_first_lba(cxt, first_usable);
        fdisk_set_last_lba(cxt, last_usable);
        gpt->pheader->first_usable_lba = cpu_to_le64(first_usable);
        gpt->bheader->first_usable_lba = cpu_to_le64(first_usable);
        gpt->pheader->last_usable_lba = cpu_to_le64(last_usable);
        gpt->bheader->last_usable_lba = cpu_to_le64(last_usable);

        /* The backup header must be recalculated */
        gpt_mknew_header_common(cxt, gpt->bheader, le64_to_cpu(gpt->pheader->alternative_lba));

        /* CRCs will have changed */
        gpt_recompute_crc(gpt->pheader, gpt->ents);
        gpt_recompute_crc(gpt->bheader, gpt->ents);

        /* update library info */
        cxt->label->nparts_max = gpt_get_nentries(gpt);

        fdisk_info(cxt, _("Partition table length changed from %"PRIu32" to %"PRIu32"."),
                        old_nents, nents);

        fdisk_label_set_changed(cxt->label, 1);
        return 0;
}

static int gpt_part_is_used(struct fdisk_context *cxt, size_t i)
{
        struct fdisk_gpt_label *gpt;
        struct gpt_entry *e;

        assert(cxt);
        assert(cxt->label);
        assert(fdisk_is_label(cxt, GPT));

        gpt = self_label(cxt);

        if (i >= gpt_get_nentries(gpt))
                return 0;

        e = gpt_get_entry(gpt, i);

        return gpt_entry_is_used(e) || gpt_partition_start(e);
}

/**
 * fdisk_gpt_is_hybrid:
 * @cxt: context
 *
 * The regular GPT contains PMBR (dummy protective MBR) where the protective
 * MBR does not address any partitions.
 *
 * Hybrid GPT contains regular MBR where this partition table addresses the
 * same partitions as GPT. It's recommended to not use hybrid GPT due to MBR
 * limits.
 *
 * The libfdisk does not provide functionality to sync GPT and MBR, you have to
 * directly access and modify (P)MBR (see fdisk_new_nested_context()).
 *
 * Returns: 1 if partition table detected as hybrid otherwise return 0
 */
int fdisk_gpt_is_hybrid(struct fdisk_context *cxt)
{
        assert(cxt);
        return valid_pmbr(cxt) == GPT_MBR_HYBRID;
}

/**
 * fdisk_gpt_get_partition_attrs:
 * @cxt: context
 * @partnum: partition number
 * @attrs: GPT partition attributes
 *
 * Sets @attrs for the given partition
 *
 * Returns: 0 on success, <0 on error.
 */
int fdisk_gpt_get_partition_attrs(
                struct fdisk_context *cxt,
                size_t partnum,
                uint64_t *attrs)
{
        struct fdisk_gpt_label *gpt;

        assert(cxt);
        assert(cxt->label);

        if (!fdisk_is_label(cxt, GPT))
                return -EINVAL;

        gpt = self_label(cxt);

        if (partnum >= gpt_get_nentries(gpt))
                return -EINVAL;

        *attrs = le64_to_cpu(gpt_get_entry(gpt, partnum)->attrs);
        return 0;
}

/**
 * fdisk_gpt_set_partition_attrs:
 * @cxt: context
 * @partnum: partition number
 * @attrs: GPT partition attributes
 *
 * Sets the GPT partition attributes field to @attrs.
 *
 * Returns: 0 on success, <0 on error.
 */
int fdisk_gpt_set_partition_attrs(
                struct fdisk_context *cxt,
                size_t partnum,
                uint64_t attrs)
{
        struct fdisk_gpt_label *gpt;

        assert(cxt);
        assert(cxt->label);

        if (!fdisk_is_label(cxt, GPT))
                return -EINVAL;

        DBG(GPT, ul_debug("entry attributes change requested partno=%zu", partnum));
        gpt = self_label(cxt);

        if (partnum >= gpt_get_nentries(gpt))
                return -EINVAL;

        gpt_get_entry(gpt, partnum)->attrs = cpu_to_le64(attrs);
        fdisk_info(cxt, _("The attributes on partition %zu changed to 0x%016" PRIx64 "."),
                        partnum + 1, attrs);

        gpt_recompute_crc(gpt->pheader, gpt->ents);
        gpt_recompute_crc(gpt->bheader, gpt->ents);
        fdisk_label_set_changed(cxt->label, 1);
        return 0;
}

static int gpt_toggle_partition_flag(
                struct fdisk_context *cxt,
                size_t i,
                unsigned long flag)
{
        struct fdisk_gpt_label *gpt;
        struct gpt_entry *e;
        uint64_t attrs;
        uintmax_t tmp;
        char *bits;
        const char *name = NULL;
        int bit = -1, rc;

        assert(cxt);
        assert(cxt->label);
        assert(fdisk_is_label(cxt, GPT));

        DBG(GPT, ul_debug("entry attribute change requested partno=%zu", i));
        gpt = self_label(cxt);

        if (i >= gpt_get_nentries(gpt))
                return -EINVAL;

        e = gpt_get_entry(gpt, i);
        attrs = e->attrs;
        bits = (char *) &attrs;

        switch (flag) {
        case GPT_FLAG_REQUIRED:
                bit = GPT_ATTRBIT_REQ;
                name = GPT_ATTRSTR_REQ;
                break;
        case GPT_FLAG_NOBLOCK:
                bit = GPT_ATTRBIT_NOBLOCK;
                name = GPT_ATTRSTR_NOBLOCK;
                break;
        case GPT_FLAG_LEGACYBOOT:
                bit = GPT_ATTRBIT_LEGACY;
                name = GPT_ATTRSTR_LEGACY;
                break;
        case GPT_FLAG_GUIDSPECIFIC:
                rc = fdisk_ask_number(cxt, 48, 48, 63, _("Enter GUID specific bit"), &tmp);
                if (rc)
                        return rc;
                bit = tmp;
                break;
        default:
                /* already specified PT_FLAG_GUIDSPECIFIC bit */
                if (flag >= 48 && flag <= 63) {
                        bit = flag;
                        flag = GPT_FLAG_GUIDSPECIFIC;
                }
                break;
        }

        if (bit < 0) {
                fdisk_warnx(cxt, _("failed to toggle unsupported bit %lu"), flag);
                return -EINVAL;
        }

        if (!isset(bits, bit))
                setbit(bits, bit);
        else
                clrbit(bits, bit);

        e->attrs = attrs;

        if (flag == GPT_FLAG_GUIDSPECIFIC)
                fdisk_info(cxt, isset(bits, bit) ?
                        _("The GUID specific bit %d on partition %zu is enabled now.") :
                        _("The GUID specific bit %d on partition %zu is disabled now."),
                        bit, i + 1);
        else
                fdisk_info(cxt, isset(bits, bit) ?
                        _("The %s flag on partition %zu is enabled now.") :
                        _("The %s flag on partition %zu is disabled now."),
                        name, i + 1);

        gpt_recompute_crc(gpt->pheader, gpt->ents);
        gpt_recompute_crc(gpt->bheader, gpt->ents);
        fdisk_label_set_changed(cxt->label, 1);
        return 0;
}

static int gpt_entry_cmp_start(const void *a, const void *b)
{
        const struct gpt_entry  *ae = (const struct gpt_entry *) a,
                                *be = (const struct gpt_entry *) b;
        int au = gpt_entry_is_used(ae),
            bu = gpt_entry_is_used(be);

        if (!au && !bu)
                return 0;
        if (!au)
                return 1;
        if (!bu)
                return -1;

        return cmp_numbers(gpt_partition_start(ae), gpt_partition_start(be));
}

/* sort partition by start sector */
static int gpt_reorder(struct fdisk_context *cxt)
{
        struct fdisk_gpt_label *gpt;
        size_t i, nparts, mess;

        assert(cxt);
        assert(cxt->label);
        assert(fdisk_is_label(cxt, GPT));

        gpt = self_label(cxt);
        nparts = gpt_get_nentries(gpt);

        for (i = 0, mess = 0; mess == 0 && i + 1 < nparts; i++)
                mess = gpt_entry_cmp_start(
                                (const void *) gpt_get_entry(gpt, i),
                                (const void *) gpt_get_entry(gpt, i + 1)) > 0;

        if (!mess)
                return 1;

        qsort(gpt->ents, nparts, sizeof(struct gpt_entry),
                        gpt_entry_cmp_start);

        gpt_recompute_crc(gpt->pheader, gpt->ents);
        gpt_recompute_crc(gpt->bheader, gpt->ents);
        fdisk_label_set_changed(cxt->label, 1);

        return 0;
}

static int gpt_reset_alignment(struct fdisk_context *cxt)
{
        struct fdisk_gpt_label *gpt;
        struct gpt_header *h;

        assert(cxt);
        assert(cxt->label);
        assert(fdisk_is_label(cxt, GPT));

        gpt = self_label(cxt);
        h = gpt ? gpt->pheader : NULL;

        if (h) {
                /* always follow existing table */
                cxt->first_lba = le64_to_cpu(h->first_usable_lba);
                cxt->last_lba  = le64_to_cpu(h->last_usable_lba);
        } else {
                /* estimate ranges for GPT */
                uint64_t first, last;
                int rc;

                rc = count_first_last_lba(cxt, &first, &last, NULL);
                if (rc)
                        return rc;
                if (cxt->first_lba < first)
                        cxt->first_lba = first;
                if (cxt->last_lba > last)
                        cxt->last_lba = last;
        }

        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,
        .locate         = gpt_locate_disklabel,
        .get_item       = gpt_get_disklabel_item,
        .set_id         = gpt_set_disklabel_id,

        .get_part       = gpt_get_partition,
        .set_part       = gpt_set_partition,
        .add_part       = gpt_add_partition,
        .del_part       = gpt_delete_partition,
        .reorder        = gpt_reorder,

        .part_is_used   = gpt_part_is_used,
        .part_toggle_flag = gpt_toggle_partition_flag,

        .deinit         = gpt_deinit,

        .reset_alignment = gpt_reset_alignment
};

static const struct fdisk_field gpt_fields[] =
{
        /* basic */
        { FDISK_FIELD_DEVICE,   N_("Device"),    10,    0 },
        { FDISK_FIELD_START,    N_("Start"),      5,    FDISK_FIELDFL_NUMBER },
        { FDISK_FIELD_END,      N_("End"),        5,    FDISK_FIELDFL_NUMBER },
        { FDISK_FIELD_SECTORS,  N_("Sectors"),    5,    FDISK_FIELDFL_NUMBER },
        { FDISK_FIELD_SIZE,     N_("Size"),       5,    FDISK_FIELDFL_NUMBER | FDISK_FIELDFL_EYECANDY },
        { FDISK_FIELD_TYPE,     N_("Type"),     0.1,    FDISK_FIELDFL_EYECANDY },
        /* expert */
        { FDISK_FIELD_TYPEID,   N_("Type-UUID"), 36,    FDISK_FIELDFL_DETAIL },
        { FDISK_FIELD_UUID,     N_("UUID"),      36,    FDISK_FIELDFL_DETAIL },
        { FDISK_FIELD_NAME,     N_("Name"),     0.2,    FDISK_FIELDFL_DETAIL },
        { FDISK_FIELD_ATTR,     N_("Attrs"),      0,    FDISK_FIELDFL_DETAIL }
};

/*
 * allocates GPT in-memory stuff
 */
struct fdisk_label *fdisk_new_gpt_label(struct fdisk_context *cxt __attribute__ ((__unused__)))
{
        struct fdisk_label *lb;
        struct fdisk_gpt_label *gpt;

        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);
        lb->parttype_cuts = gpt_parttype_cuts;
        lb->nparttype_cuts = ARRAY_SIZE(gpt_parttype_cuts);

        lb->fields = gpt_fields;
        lb->nfields = ARRAY_SIZE(gpt_fields);

        /* return calloc() result to keep static anaylizers happy */
        return (struct fdisk_label *) gpt;
}

/**
 * fdisk_gpt_disable_relocation
 * @lb: label
 * @disable: 0 or 1
 *
 * Disable automatic backup header relocation to the end of the device. The
 * header position is recalculated during libfdisk probing stage by
 * fdisk_assign_device() and later written by fdisk_write_disklabel(), so you
 * need to call it before fdisk_assign_device().
 *
 * Since: 2.36
 */
void fdisk_gpt_disable_relocation(struct fdisk_label *lb, int disable)
{
        struct fdisk_gpt_label *gpt = (struct fdisk_gpt_label *) lb;

        assert(gpt);
        gpt->no_relocate = disable ? 1 : 0;
}

/**
 * fdisk_gpt_enable_minimize
 * @lb: label
 * @enable: 0 or 1
 *
 * Force libfdisk to write backup header to behind last partition. The
 * header position is recalculated on fdisk_write_disklabel().
 *
 * Since: 2.36
 */
void fdisk_gpt_enable_minimize(struct fdisk_label *lb, int enable)
{
        struct fdisk_gpt_label *gpt = (struct fdisk_gpt_label *) lb;

        assert(gpt);
        gpt->minimize = enable ? 1 : 0;
}

#ifdef TEST_PROGRAM
static int test_getattr(struct fdisk_test *ts __attribute__((unused)),
                        int argc, char *argv[])
{
        if (argc != 3)
                return -1;

        const char *disk = argv[1];
        size_t part = strtoul(argv[2], NULL, 0) - 1;
        struct fdisk_context *cxt;
        uint64_t atters = 0;

        cxt = fdisk_new_context();
        fdisk_assign_device(cxt, disk, 1);

        if (!fdisk_is_label(cxt, GPT))
                return EXIT_FAILURE;

        if (fdisk_gpt_get_partition_attrs(cxt, part, &atters))
                return EXIT_FAILURE;

        printf("%s: 0x%016" PRIx64 "\n", argv[2], atters);

        fdisk_unref_context(cxt);
        return 0;
}

static int test_setattr(struct fdisk_test *ts __attribute__((unused)),
                        int argc, char *argv[])
{
        if (argc != 4)
                return -1;

        const char *disk = argv[1];
        size_t part = strtoul(argv[2], NULL, 0) - 1;
        uint64_t atters = strtoull(argv[3], NULL, 0);
        struct fdisk_context *cxt;

        cxt = fdisk_new_context();
        fdisk_assign_device(cxt, disk, 0);

        if (!fdisk_is_label(cxt, GPT))
                return EXIT_FAILURE;

        if (fdisk_gpt_set_partition_attrs(cxt, part, atters))
                return EXIT_FAILURE;

        if (fdisk_write_disklabel(cxt))
                return EXIT_FAILURE;

        fdisk_unref_context(cxt);
        return 0;
}

int main(int argc, char *argv[])
{
        struct fdisk_test tss[] = {
                { "--getattr",  test_getattr,  "<disk> <partition>             print attributes" },
                { "--setattr",  test_setattr,  "<disk> <partition> <value>     set attributes" },
                { NULL }
        };

        return fdisk_run_test(tss, argc, argv);
}

#endif