source: mainline/uspace/lib/label/src/gpt.c@ 6deb2cd

/*
 * Copyright (c) 2015 Jiri Svoboda
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup liblabel
 * @{
 */
/**
 * @file GUID Partition Table label.
 */

#include <adt/checksum.h>
#include <byteorder.h>
#include <errno.h>
#include <mem.h>
#include <stdint.h>
#include <stdlib.h>
#include <uuid.h>

#include "std/mbr.h"
#include "std/gpt.h"
#include "gpt.h"

static int gpt_open(label_bd_t *, label_t **);
static int gpt_create(label_bd_t *, label_t **);
static void gpt_close(label_t *);
static int gpt_destroy(label_t *);
static int gpt_get_info(label_t *, label_info_t *);
static label_part_t *gpt_part_first(label_t *);
static label_part_t *gpt_part_next(label_part_t *);
static void gpt_part_get_info(label_part_t *, label_part_info_t *);
static int gpt_part_create(label_t *, label_part_spec_t *, label_part_t **);
static int gpt_part_destroy(label_part_t *);
static int gpt_suggest_ptype(label_t *, label_pcnt_t, label_ptype_t *);

static int gpt_check_free_idx(label_t *, int);
static int gpt_check_free_range(label_t *, uint64_t, uint64_t);

static void gpt_unused_pte(gpt_entry_t *);
static int gpt_part_to_pte(label_part_t *, gpt_entry_t *);
static int gpt_pte_to_part(label_t *, gpt_entry_t *, int);
static int gpt_pte_update(label_t *, gpt_entry_t *, int);

static int gpt_update_pt_crc(label_t *, uint32_t);
static void gpt_hdr_compute_crc(gpt_header_t *, size_t);
static int gpt_hdr_get_crc(gpt_header_t *, size_t, uint32_t *);

static int gpt_pmbr_create(label_bd_t *, size_t, uint64_t);
static int gpt_pmbr_destroy(label_bd_t *, size_t);

const uint8_t efi_signature[8] = {
        /* "EFI PART" in ASCII */
        0x45, 0x46, 0x49, 0x20, 0x50, 0x41, 0x52, 0x54
};

label_ops_t gpt_label_ops = {
        .open = gpt_open,
        .create = gpt_create,
        .close = gpt_close,
        .destroy = gpt_destroy,
        .get_info = gpt_get_info,
        .part_first = gpt_part_first,
        .part_next = gpt_part_next,
        .part_get_info = gpt_part_get_info,
        .part_create = gpt_part_create,
        .part_destroy = gpt_part_destroy,
        .suggest_ptype = gpt_suggest_ptype
};

static int gpt_open(label_bd_t *bd, label_t **rlabel)
{
        label_t *label = NULL;
        gpt_header_t *gpt_hdr[2];
        gpt_entry_t *eptr;
        uint8_t *etable[2];
        size_t bsize;
        aoff64_t nblocks;
        uint32_t num_entries;
        uint32_t esize;
        uint32_t pt_blocks;
        uint64_t ptba[2];
        uint64_t h1ba;
        uint32_t entry;
        uint32_t pt_crc;
        uint64_t ba_min, ba_max;
        uint32_t hdr_size;
        uint32_t hdr_crc;
        int i, j;
        int rc;

        gpt_hdr[0] = NULL;
        gpt_hdr[1] = NULL;
        etable[0] = NULL;
        etable[1] = NULL;

        rc = bd->ops->get_bsize(bd->arg, &bsize);
        if (rc != EOK) {
                rc = EIO;
                goto error;
        }

        rc = bd->ops->get_nblocks(bd->arg, &nblocks);
        if (rc != EOK) {
                rc = EIO;
                goto error;
        }

        if (bsize < 512 || (bsize % 512) != 0) {
                rc = EINVAL;
                goto error;
        }

        gpt_hdr[0] = calloc(1, bsize);
        if (gpt_hdr[0] == NULL) {
                rc = ENOMEM;
                goto error;
        }

        gpt_hdr[1] = calloc(1, bsize);
        if (gpt_hdr[1] == NULL) {
                rc = ENOMEM;
                goto error;
        }

        rc = bd->ops->read(bd->arg, gpt_hdr_ba, 1, gpt_hdr[0]);
        if (rc != EOK) {
                rc = EIO;
                goto error;
        }

        h1ba = uint64_t_le2host(gpt_hdr[0]->alternate_lba);

        if (h1ba >= nblocks) {
                rc = EINVAL;
                goto error;
        }

        rc = bd->ops->read(bd->arg, h1ba, 1, gpt_hdr[1]);
        if (rc != EOK) {
                rc = EIO;
                goto error;
        }

        label = calloc(1, sizeof(label_t));
        if (label == NULL)
                return ENOMEM;

        list_initialize(&label->parts);
        list_initialize(&label->pri_parts);
        list_initialize(&label->log_parts);

        for (j = 0; j < 2; j++) {
                for (i = 0; i < 8; ++i) {
                        if (gpt_hdr[j]->efi_signature[i] != efi_signature[i]) {
                                rc = EINVAL;
                                goto error;
                        }
                }
        }

        if (uint32_t_le2host(gpt_hdr[0]->revision) !=
            uint32_t_le2host(gpt_hdr[1]->revision)) {
                rc = EINVAL;
                goto error;
        }

        if (uint32_t_le2host(gpt_hdr[0]->header_size) !=
            uint32_t_le2host(gpt_hdr[1]->header_size)) {
                rc = EINVAL;
                goto error;
        }

        hdr_size = uint32_t_le2host(gpt_hdr[0]->header_size);
        if (hdr_size < sizeof(gpt_header_t) ||
            hdr_size > bsize) {
                rc = EINVAL;
                goto error;
        }

        for (j = 0; j < 2; j++) {
                rc = gpt_hdr_get_crc(gpt_hdr[j], hdr_size, &hdr_crc);
                if (rc != EOK)
                        goto error;

                if (uint32_t_le2host(gpt_hdr[j]->header_crc32) != hdr_crc) {
                        rc = EINVAL;
                        goto error;
                }
        }

        if (uint64_t_le2host(gpt_hdr[0]->my_lba) != gpt_hdr_ba) {
                rc = EINVAL;
                goto error;
        }

        if (uint64_t_le2host(gpt_hdr[1]->my_lba) != h1ba) {
                rc = EINVAL;
                goto error;
        }

        if (uint64_t_le2host(gpt_hdr[1]->alternate_lba) != gpt_hdr_ba) {
                rc = EINVAL;
                goto error;
        }

        num_entries = uint32_t_le2host(gpt_hdr[0]->num_entries);
        esize = uint32_t_le2host(gpt_hdr[0]->entry_size);
        pt_blocks = (num_entries * esize + bsize - 1) / bsize;
        ptba[0] = uint64_t_le2host(gpt_hdr[0]->entry_lba);
        ptba[1] = uint64_t_le2host(gpt_hdr[1]->entry_lba);
        ba_min = uint64_t_le2host(gpt_hdr[0]->first_usable_lba);
        ba_max = uint64_t_le2host(gpt_hdr[0]->last_usable_lba);
        pt_crc = uint32_t_le2host(gpt_hdr[0]->pe_array_crc32);

        if (uint64_t_le2host(gpt_hdr[1]->first_usable_lba) != ba_min) {
                rc = EINVAL;
                goto error;
        }

        if (uint64_t_le2host(gpt_hdr[1]->last_usable_lba) != ba_max) {
                rc = EINVAL;
                goto error;
        }

        for (i = 0; i < 16; i++) {
                if (gpt_hdr[1]->disk_guid[i] != gpt_hdr[0]->disk_guid[i]) {
                        rc = EINVAL;
                        goto error;
                }
        }

        if (uint32_t_le2host(gpt_hdr[1]->num_entries) != num_entries) {
                rc = EINVAL;
                goto error;
        }

        if (uint32_t_le2host(gpt_hdr[1]->entry_size) != esize) {
                rc = EINVAL;
                goto error;
        }

        if (num_entries < 1) {
                rc = EINVAL;
                goto error;
        }

        if (esize < sizeof(gpt_entry_t)) {
                rc = EINVAL;
                goto error;
        }

        if (ba_max < ba_min) {
                rc = EINVAL;
                goto error;
        }

        /* Check fields in backup header for validity */

        for (j = 0; j < 2; j++) {
                etable[j] = calloc(1, pt_blocks * bsize);
                if (etable[j] == NULL) {
                        rc = ENOMEM;
                        goto error;
                }

                rc = bd->ops->read(bd->arg, ptba[j], pt_blocks / 2, etable[j]);
                if (rc != EOK) {
                        rc = EIO;
                        goto error;
                }

                if (compute_crc32(etable[j], num_entries * esize) != pt_crc) {
                        rc = EIO;
                        goto error;
                }

        }

        for (entry = 0; entry < num_entries; entry++) {
                eptr = (gpt_entry_t *)(etable[0] + entry * esize);
                rc = gpt_pte_to_part(label, eptr, entry + 1);
                if (rc != EOK)
                        goto error;
        }

        free(etable[0]);
        etable[0] = NULL;
        free(etable[1]);
        etable[1] = NULL;
        free(gpt_hdr[0]);
        gpt_hdr[0] = NULL;
        free(gpt_hdr[1]);
        gpt_hdr[1] = NULL;

        label->ops = &gpt_label_ops;
        label->ltype = lt_gpt;
        label->bd = *bd;
        label->ablock0 = ba_min;
        label->anblocks = ba_max - ba_min + 1;
        label->pri_entries = num_entries;
        label->block_size = bsize;

        label->lt.gpt.hdr_ba[0] = gpt_hdr_ba;
        label->lt.gpt.hdr_ba[1] = h1ba;
        label->lt.gpt.ptable_ba[0] = ptba[0];
        label->lt.gpt.ptable_ba[1] = ptba[1];
        label->lt.gpt.esize = esize;
        label->lt.gpt.pt_blocks = pt_blocks;
        label->lt.gpt.pt_crc = pt_crc;
        label->lt.gpt.hdr_size = hdr_size;

        *rlabel = label;
        return EOK;
error:
        free(etable[0]);
        free(etable[1]);
        free(gpt_hdr[0]);
        free(gpt_hdr[1]);
        free(label);
        return rc;
}

static int gpt_create(label_bd_t *bd, label_t **rlabel)
{
        label_t *label = NULL;
        gpt_header_t *gpt_hdr = NULL;
        uint8_t *etable = NULL;
        size_t bsize;
        uint32_t num_entries;
        uint32_t esize;
        uint64_t ptba[2];
        uint64_t hdr_ba[2];
        uint64_t pt_blocks;
        uint64_t ba_min, ba_max;
        aoff64_t nblocks;
        uint64_t resv_blocks;
        uint32_t pt_crc;
        uuid_t disk_uuid;
        int i, j;
        int rc;

        rc = bd->ops->get_bsize(bd->arg, &bsize);
        if (rc != EOK) {
                rc = EIO;
                goto error;
        }

        if (bsize < 512 || (bsize % 512) != 0) {
                rc = EINVAL;
                goto error;
        }

        rc = bd->ops->get_nblocks(bd->arg, &nblocks);
        if (rc != EOK) {
                rc = EIO;
                goto error;
        }

        /* Number of blocks of a partition table */
        pt_blocks = gpt_ptable_min_size / bsize;
        /* Minimum number of reserved (not allocatable) blocks */
        resv_blocks = 3 + 2 * pt_blocks;

        if (nblocks <= resv_blocks) {
                rc = ENOSPC;
                goto error;
        }

        rc = gpt_pmbr_create(bd, bsize, nblocks);
        if (rc != EOK) {
                rc = EIO;
                goto error;
        }

        uuid_generate(&disk_uuid);

        hdr_ba[0] = gpt_hdr_ba;
        hdr_ba[1] = nblocks - 1;
        ptba[0] = 2;
        ptba[1] = nblocks - 1 - pt_blocks;
        ba_min = ptba[0] + pt_blocks;
        ba_max = ptba[1] - 1;
        esize = sizeof(gpt_entry_t);

        num_entries = pt_blocks * bsize / sizeof(gpt_entry_t);

        for (i = 0; i < 2; i++) {
                etable = calloc(1, pt_blocks * bsize);
                if (etable == NULL) {
                        rc = ENOMEM;
                        goto error;
                }

                rc = bd->ops->write(bd->arg, ptba[i], pt_blocks, etable);
                if (rc != EOK) {
                        rc = EIO;
                        goto error;
                }

                pt_crc = compute_crc32((uint8_t *)etable,
                    num_entries * esize);

                free(etable);
                etable = NULL;

                gpt_hdr = calloc(1, bsize);
                if (gpt_hdr == NULL) {
                        rc = ENOMEM;
                        goto error;
                }

                for (j = 0; j < 8; ++j)
                        gpt_hdr->efi_signature[j] = efi_signature[j];
                gpt_hdr->revision = host2uint32_t_le(gpt_revision);
                gpt_hdr->header_size = host2uint32_t_le(sizeof(gpt_header_t));
                gpt_hdr->header_crc32 = 0;
                gpt_hdr->my_lba = host2uint64_t_le(hdr_ba[i]);
                gpt_hdr->alternate_lba = host2uint64_t_le(hdr_ba[1 - i]);
                gpt_hdr->first_usable_lba = host2uint64_t_le(ba_min);
                gpt_hdr->last_usable_lba = host2uint64_t_le(ba_max);
                uuid_encode(&disk_uuid, gpt_hdr->disk_guid);
                gpt_hdr->entry_lba = host2uint64_t_le(ptba[i]);
                gpt_hdr->num_entries = host2uint32_t_le(num_entries);
                gpt_hdr->entry_size = host2uint32_t_le(esize);
                gpt_hdr->pe_array_crc32 = pt_crc;

                gpt_hdr_compute_crc(gpt_hdr, sizeof(gpt_header_t));

                rc = bd->ops->write(bd->arg, hdr_ba[i], 1, gpt_hdr);
                if (rc != EOK) {
                        rc = EIO;
                        goto error;
                }

                free(gpt_hdr);
                gpt_hdr = NULL;
        }

        label = calloc(1, sizeof(label_t));
        if (label == NULL)
                return ENOMEM;

        list_initialize(&label->parts);
        list_initialize(&label->pri_parts);
        list_initialize(&label->log_parts);

        label->ops = &gpt_label_ops;
        label->ltype = lt_gpt;
        label->bd = *bd;
        label->ablock0 = ba_min;
        label->anblocks = ba_max - ba_min + 1;
        label->pri_entries = num_entries;
        label->block_size = bsize;

        label->lt.gpt.hdr_ba[0] = hdr_ba[0];
        label->lt.gpt.hdr_ba[1] = hdr_ba[1];
        label->lt.gpt.ptable_ba[0] = ptba[0];
        label->lt.gpt.ptable_ba[1] = ptba[1];
        label->lt.gpt.esize = esize;
        label->lt.gpt.pt_blocks = pt_blocks;
        label->lt.gpt.pt_crc = pt_crc;
        label->lt.gpt.hdr_size = sizeof(gpt_header_t);

        *rlabel = label;
        return EOK;
error:
        free(etable);
        free(gpt_hdr);
        free(label);
        return rc;
}

static void gpt_close(label_t *label)
{
        label_part_t *part;

        part = gpt_part_first(label);
        while (part != NULL) {
                list_remove(&part->lparts);
                list_remove(&part->lpri);
                free(part);
                part = gpt_part_first(label);
        }

        free(label);
}

static int gpt_destroy(label_t *label)
{
        gpt_header_t *gpt_hdr = NULL;
        uint8_t *etable = NULL;
        label_part_t *part;
        int i;
        int rc;

        part = gpt_part_first(label);
        if (part != NULL) {
                rc = ENOTEMPTY;
                goto error;
        }

        for (i = 0; i < 2; i++) {
                gpt_hdr = calloc(1, label->block_size);
                if (gpt_hdr == NULL) {
                        rc = ENOMEM;
                        goto error;
                }

                rc = label->bd.ops->write(label->bd.arg, label->lt.gpt.hdr_ba[i],
                    1, gpt_hdr);
                if (rc != EOK) {
                        rc = EIO;
                        goto error;
                }

                free(gpt_hdr);
                gpt_hdr = NULL;

                etable = calloc(1, label->lt.gpt.pt_blocks *
                    label->block_size);
                if (etable == NULL) {
                        rc = ENOMEM;
                        goto error;
                }

                rc = label->bd.ops->write(label->bd.arg,
                    label->lt.gpt.ptable_ba[i], label->lt.gpt.pt_blocks,
                    etable);
                if (rc != EOK) {
                        rc = EIO;
                        goto error;
                }

                free(etable);
                etable = 0;
        }

        rc = gpt_pmbr_destroy(&label->bd, label->block_size);
        if (rc != EOK)
                goto error;

        free(label);
        return EOK;
error:
        return rc;
}

static bool gpt_can_create_pri(label_t *label)
{
        return list_count(&label->parts) < (size_t)label->pri_entries;
}

static bool gpt_can_delete_part(label_t *label)
{
        return list_count(&label->parts) > 0;
}

static int gpt_get_info(label_t *label, label_info_t *linfo)
{
        memset(linfo, 0, sizeof(label_info_t));
        linfo->ltype = lt_gpt;
        linfo->flags = lf_ptype_uuid; /* Partition type is in UUID format */
        if (gpt_can_create_pri(label))
                linfo->flags = linfo->flags | lf_can_create_pri;
        if (gpt_can_delete_part(label))
                linfo->flags = linfo->flags | lf_can_delete_part;
        linfo->ablock0 = label->ablock0;
        linfo->anblocks = label->anblocks;
        return EOK;
}

static label_part_t *gpt_part_first(label_t *label)
{
        link_t *link;

        link = list_first(&label->parts);
        if (link == NULL)
                return NULL;

        return list_get_instance(link, label_part_t, lparts);
}

static label_part_t *gpt_part_next(label_part_t *part)
{
        link_t *link;

        link = list_next(&part->lparts, &part->label->parts);
        if (link == NULL)
                return NULL;

        return list_get_instance(link, label_part_t, lparts);
}

static void gpt_part_get_info(label_part_t *part, label_part_info_t *pinfo)
{
        pinfo->index = part->index;
        pinfo->pkind = lpk_primary;
        pinfo->block0 = part->block0;
        pinfo->nblocks = part->nblocks;
}

static int gpt_part_create(label_t *label, label_part_spec_t *pspec,
    label_part_t **rpart)
{
        label_part_t *part;
        gpt_entry_t pte;
        int rc;

        part = calloc(1, sizeof(label_part_t));
        if (part == NULL) {
                rc = ENOMEM;
                goto error;
        }

        /* Verify index is within bounds and free */
        rc = gpt_check_free_idx(label, pspec->index);
        if (rc != EOK) {
                rc = EINVAL;
                goto error;
        }

        /* Verify range is within bounds and free */
        rc = gpt_check_free_range(label, pspec->block0, pspec->nblocks);
        if (rc != EOK) {
                rc = EINVAL;
                goto error;
        }

        /* GPT only has primary partitions */
        if (pspec->pkind != lpk_primary) {
                rc = EINVAL;
                goto error;
        }

        /* Partition type must be in UUID format */
        if (pspec->ptype.fmt != lptf_uuid) {
                rc = EINVAL;
                goto error;
        }

        /* XXX Check if index is used */

        part->label = label;
        part->index = pspec->index;
        part->block0 = pspec->block0;
        part->nblocks = pspec->nblocks;
        part->ptype = pspec->ptype;
        uuid_generate(&part->part_uuid);

        /* Prepare partition table entry */
        rc = gpt_part_to_pte(part, &pte);
        if (rc != EOK) {
                rc = EINVAL;
                goto error;
        }

        /* Modify partition tables */
        rc = gpt_pte_update(label, &pte, pspec->index - 1);
        if (rc != EOK) {
                rc = EIO;
                goto error;
        }

        list_append(&part->lparts, &label->parts);
        list_append(&part->lpri, &label->pri_parts);

        *rpart = part;
        return EOK;
error:
        free(part);
        return rc;
}

static int gpt_part_destroy(label_part_t *part)
{
        gpt_entry_t pte;
        int rc;

        /* Prepare unused partition table entry */
        gpt_unused_pte(&pte);

        /* Modify partition tables */
        rc = gpt_pte_update(part->label, &pte, part->index - 1);
        if (rc != EOK)
                return EIO;

        list_remove(&part->lparts);
        list_remove(&part->lpri);
        free(part);
        return EOK;
}

static int gpt_suggest_ptype(label_t *label, label_pcnt_t pcnt,
    label_ptype_t *ptype)
{
        const char *ptid;
        int rc;

        ptid = NULL;

        switch (pcnt) {
        case lpc_fat12_16:
        case lpc_exfat:
        case lpc_fat32:
                ptid = GPT_MS_BASIC_DATA;
                break;
        case lpc_ext4:
                ptid = GPT_LINUX_FS_DATA;
                break;
        case lpc_minix:
                ptid = GPT_MINIX_FAKE;
                break;
        }

        if (ptid == NULL)
                return EINVAL;

        ptype->fmt = lptf_uuid;
        rc = uuid_parse(ptid, &ptype->t.uuid, NULL);
        assert(rc == EOK);

        return EOK;
}

/** Verify that the specified index is valid and free. */
static int gpt_check_free_idx(label_t *label, int index)
{
        label_part_t *part;

        if (index < 1 || index > label->pri_entries)
                return EINVAL;

        part = gpt_part_first(label);
        while (part != NULL) {
                if (part->index == index)
                        return EEXIST;
                part = gpt_part_next(part);
        }

        return EOK;
}

/** Determine if two block address ranges overlap. */
static bool gpt_overlap(uint64_t a0, uint64_t an, uint64_t b0, uint64_t bn)
{
        return !(a0 + an <= b0 || b0 + bn <= a0);
}

static int gpt_check_free_range(label_t *label, uint64_t block0,
    uint64_t nblocks)
{
        label_part_t *part;

        if (block0 < label->ablock0)
                return EINVAL;
        if (block0 + nblocks > label->ablock0 + label->anblocks)
                return EINVAL;

        part = gpt_part_first(label);
        while (part != NULL) {
                if (gpt_overlap(block0, nblocks, part->block0, part->nblocks))
                        return EEXIST;
                part = gpt_part_next(part);
        }

        return EOK;
}

static void gpt_unused_pte(gpt_entry_t *pte)
{
        memset(pte, 0, sizeof(gpt_entry_t));
}

static int gpt_part_to_pte(label_part_t *part, gpt_entry_t *pte)
{
        uint64_t eblock;

        eblock = part->block0 + part->nblocks - 1;
        if (eblock < part->block0)
                return EINVAL;

        memset(pte, 0, sizeof(gpt_entry_t));
        uuid_encode(&part->ptype.t.uuid, pte->part_type);
        uuid_encode(&part->part_uuid, pte->part_id);
        pte->start_lba = host2uint64_t_le(part->block0);
        pte->end_lba = host2uint64_t_le(eblock);
//      pte->attributes
//      pte->part_name
        return EOK;
}

static int gpt_pte_to_part(label_t *label, gpt_entry_t *pte, int index)
{
        label_part_t *part;
        bool present;
        uint64_t b0, b1;
        int i;

        present = false;
        for (i = 0; i < 8; i++)
                if (pte->part_type[i] != 0x00)
                        present = true;

        if (!present)
                return EOK;

        b0 = uint64_t_le2host(pte->start_lba);
        b1 = uint64_t_le2host(pte->end_lba);
        if (b1 <= b0)
                return EINVAL;

        part = calloc(1, sizeof(label_part_t));
        if (part == NULL)
                return ENOMEM;

        part->index = index;
        part->block0 = b0;
        part->nblocks = b1 - b0 + 1;
        part->ptype.fmt = lptf_uuid;
        uuid_decode(pte->part_type, &part->ptype.t.uuid);
        uuid_decode(pte->part_id, &part->part_uuid);

        part->label = label;
        list_append(&part->lparts, &label->parts);
        list_append(&part->lpri, &label->pri_parts);
        return EOK;
}

/** Update partition table entry at specified index.
 *
 * Replace partition entry at index @a index with the contents of
 * @a pte.
 */
static int gpt_pte_update(label_t *label, gpt_entry_t *pte, int index)
{
        size_t pos;
        uint64_t ba;
        uint64_t nblocks;
        size_t ptbytes;
        uint8_t *buf;
        gpt_entry_t *e;
        uint32_t crc;
        int i;
        int rc;

        /* Byte offset of partition entry */
        pos = index * label->lt.gpt.esize;
        /* Number of bytes in partition table */
        ptbytes = label->pri_entries * label->lt.gpt.esize;

        buf = calloc(1, label->block_size * label->lt.gpt.pt_blocks);
        if (buf == NULL)
                return ENOMEM;

        /* For both partition tables: read, modify, write */
        for (i = 0; i < 2; i++) {
                ba = label->lt.gpt.ptable_ba[i];
                nblocks = label->lt.gpt.pt_blocks;

                rc = label->bd.ops->read(label->bd.arg, ba, nblocks, buf);
                if (rc != EOK) {
                        rc = EIO;
                        goto error;
                }

                crc = compute_crc32(buf, ptbytes);
                if (crc != label->lt.gpt.pt_crc) {
                        /* Corruption detected */
                        rc = EIO;
                        goto error;
                }

                /* Replace single entry */
                e = (gpt_entry_t *)(&buf[pos]);
                *e = *pte;

                rc = label->bd.ops->write(label->bd.arg, ba, nblocks, buf);
                if (rc != EOK) {
                        rc = EIO;
                        goto error;
                }

                crc = compute_crc32(buf, ptbytes);
                rc = gpt_update_pt_crc(label, crc);
                if (rc != EOK) {
                        rc = EIO;
                        goto error;
                }
        }

        label->lt.gpt.pt_crc = crc;
        free(buf);
        return EOK;
error:
        free(buf);
        return rc;
}

static int gpt_update_pt_crc(label_t *label, uint32_t crc)
{
        gpt_header_t *gpt_hdr;
        int rc;
        int i;

        gpt_hdr = calloc(1, label->block_size);
        if (gpt_hdr == NULL) {
                rc = ENOMEM;
                goto exit;
        }

        for (i = 0; i < 2; i++) {
                rc = label->bd.ops->read(label->bd.arg,
                    label->lt.gpt.hdr_ba[i], 1, gpt_hdr);
                if (rc != EOK) {
                        rc = EIO;
                        goto exit;
                }

                gpt_hdr->pe_array_crc32 = host2uint32_t_le(crc);
                gpt_hdr_compute_crc(gpt_hdr, label->lt.gpt.hdr_size);

                rc = label->bd.ops->write(label->bd.arg,
                    label->lt.gpt.hdr_ba[i], 1, gpt_hdr);
                if (rc != EOK) {
                        rc = EIO;
                        goto exit;
                }
        }

        rc = EOK;

exit:
        free(gpt_hdr);
        return rc;
}

static void gpt_hdr_compute_crc(gpt_header_t *hdr, size_t hdr_size)
{
        uint32_t crc;

        hdr->header_crc32 = 0;
        crc = compute_crc32((uint8_t *)hdr, hdr_size);
        hdr->header_crc32 = crc;
}

static int gpt_hdr_get_crc(gpt_header_t *hdr, size_t hdr_size, uint32_t *crc)
{
        gpt_header_t *c;

        c = calloc(1, hdr_size);
        if (c == NULL)
                return ENOMEM;

        memcpy(c, hdr, hdr_size);
        c->header_crc32 = 0;
        *crc = compute_crc32((uint8_t *)c, hdr_size);
        free(c);

        return EOK;
}

/** Create GPT Protective MBR */
static int gpt_pmbr_create(label_bd_t *bd, size_t bsize, uint64_t nblocks)
{
        mbr_br_block_t *pmbr = NULL;
        uint64_t pmbr_nb;
        int rc;

        pmbr = calloc(1, bsize);
        if (pmbr == NULL) {
                rc = ENOMEM;
                goto error;
        }

        pmbr_nb = nblocks - gpt_hdr_ba;

        pmbr->pte[0].ptype = mbr_pt_gpt_protect;
        pmbr->pte[0].first_lba = gpt_hdr_ba;

        if (pmbr_nb <= UINT32_MAX)
                pmbr->pte[0].length = host2uint32_t_le((uint32_t)pmbr_nb);
        else
                pmbr->pte[0].length = host2uint32_t_le(UINT32_MAX);

        pmbr->signature = host2uint16_t_le(mbr_br_signature);

        rc = bd->ops->write(bd->arg, mbr_ba, 1, pmbr);
        if (rc != EOK) {
                rc = EIO;
                goto error;
        }

        free(pmbr);
        return EOK;
error:
        free(pmbr);
        return rc;
}

/** Destroy GPT Protective MBR */
static int gpt_pmbr_destroy(label_bd_t *bd, size_t bsize)
{
        mbr_br_block_t *pmbr = NULL;
        int rc;

        pmbr = calloc(1, bsize);
        if (pmbr == NULL) {
                rc = ENOMEM;
                goto error;
        }

        rc = bd->ops->write(bd->arg, mbr_ba, 1, pmbr);
        if (rc != EOK) {
                rc = EIO;
                goto error;
        }

        free(pmbr);
        return EOK;
error:
        free(pmbr);
        return rc;
}

/** @}
 */