/src/util-linux/libfdisk/src/gpt.c

Source
/*
 * 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)
#define GPT_NPARTITIONS_MAX (4 * 1024 * 1024 / sizeof(struct gpt_entry))

/* 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)
        * le32_to_cpu(src->sizeof_partition_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 (%ju != %ju) "
             "will be corrected by write."),
          (uintmax_t) sz_lba, (uintmax_t) (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 (ul_vfs_lseek(cxt->vfs, cxt->dev_fd, offset, SEEK_SET) == (off_t) -1)
    return -1;
  return (size_t)ul_vfs_read(cxt->vfs, 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;
  if (sz > GPT_NPARTITIONS_MAX * sizeof(struct gpt_entry)
      || sz / cxt->sector_size >= le64_to_cpu(header->first_usable_lba)) {
    DBG(GPT, ul_debug("entries array too large"));
    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 != ul_vfs_lseek(cxt->vfs, cxt->dev_fd, offset, SEEK_SET))
    goto fail;

  ssz = ul_vfs_read(cxt->vfs, 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;

  /* valid header must be at MyLBA */
  if (le64_to_cpu(header->my_lba) != lba)
    goto invalid;

  /* entry size must be large enough to hold struct gpt_entry */
  if (le32_to_cpu(header->sizeof_partition_entry) < sizeof(struct gpt_entry))
    goto invalid;

  if (!gpt_check_lba_sanity(cxt, header))
    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 (_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, res_size;
  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_size = sizeof(GPT_ATTRSTR_NOBLOCK) +
       sizeof(GPT_ATTRSTR_REQ) +
       sizeof(GPT_ATTRSTR_LEGACY) +
       sizeof("GUID:") + (GPT_ATTRBIT_GUID_COUNT * 3);
  *res = calloc(1, res_size);
  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++) {
    int rc;

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

    if (rc < 0 || (size_t) rc >= res_size - (p - *res))
      break;
    p += rc;
    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;
    const char *item;

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

    item = p;
    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>. Bare numeric input accepts
     * the named-flag bits (0..2) and the GUID-specific range
     * (48..63). The GUID: prefix is the documented namespace
     * for 48..63 only. Bits 3..47 are reserved by UEFI. */
    } else if (isdigit((unsigned char) *p)
         || (strncmp(p, "GUID:", 5) == 0
             && isdigit((unsigned char) *(p + 5)))) {
      const char *num_start, *num_end;
      char buf[32];
      size_t len;
      uint16_t val;
      int is_guid = (*p == 'G');

      if (is_guid)
        p += 5;

      num_start = p;
      num_end = p;
      while (*num_end && *num_end != ',' && !isblank(*num_end))
        num_end++;
      len = num_end - num_start;

      if (len == 0 || len >= sizeof(buf)) {
        bit = -1;
      } else {
        memcpy(buf, num_start, len);
        buf[len] = '\0';

        if (ul_strtou16(buf, &val, 0) != 0)
          bit = -1;
        else if (val >= GPT_ATTRBIT_GUID_FIRST
           && val < GPT_ATTRBIT_GUID_FIRST + GPT_ATTRBIT_GUID_COUNT) {
          bit = val;
          p = num_end;
        } else if (!is_guid && val <= GPT_ATTRBIT_LEGACY) {
          bit = val;
          p = num_end;
        } else
          bit = -1;
      }
    }

    if (bit < 0) {
      fdisk_warnx(cxt, _("unsupported GPT attribute bit '%s'"), item);
      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 != ul_vfs_lseek(cxt->vfs, cxt->dev_fd, offset, SEEK_SET))
    return -errno;

  if (ul_vfs_read_all(cxt->vfs, 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 != ul_vfs_lseek(cxt->vfs, cxt->dev_fd, offset, SEEK_SET))
    return -errno;

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

  if (ul_vfs_fsync(cxt->vfs, 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),
         (uintmax_t)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."), (uintmax_t)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."),
        (uintmax_t)le64_to_cpu(pheader->last_usable_lba), (uintmax_t)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."),
        (uintmax_t)le64_to_cpu(pheader->first_usable_lba), (uintmax_t)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 %ju sectors)"),
                        i + 1, (uintmax_t) first_usable);
      rc = -EINVAL;
    }
    if (gpt_partition_end(e) > last_usable) {
      fdisk_warnx(cxt, _("Partition #%zu out of range (maximal end is %ju sectors)"),
                        i + 1, (uintmax_t) (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, esects = 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;
  }

  /* The primary entries array is not relocated when the table length
   * changes, so derive the first usable LBA from its real on-disk
   * location rather than the default LBA 2. */
  rc = gpt_calculate_sectorsof_entries(gpt->pheader, nents, &esects, cxt);
  if (rc == 0)
    first_usable = le64_to_cpu(gpt->pheader->partition_entry_lba) + esects;
  if (rc == 0)
    rc = gpt_calculate_last_lba(gpt->pheader, nents, &last_usable, cxt);
  if (rc)
    return rc;
  if (first_usable > last_usable)
    return -ENOSPC;

  /* 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 %ju to %ju."),
      (uintmax_t) old_nents, (uintmax_t) 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%016jx."),
      partnum + 1, (uintmax_t) 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,
      le32_to_cpu(gpt->pheader->sizeof_partition_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

Coverage Report

Created: 2026-08-14 06:25