source: mainline/uspace/lib/label/src/mbr.c@ 09ab0a9a

/*
 * 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 Master Boot Record label
 */

#include <byteorder.h>
#include <errno.h>
#include <mem.h>
#include <stdlib.h>

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

static errno_t mbr_open(label_bd_t *, label_t **);
static errno_t mbr_open_ext(label_t *);
static errno_t mbr_create(label_bd_t *, label_t **);
static void mbr_close(label_t *);
static errno_t mbr_destroy(label_t *);
static errno_t mbr_get_info(label_t *, label_info_t *);
static label_part_t *mbr_part_first(label_t *);
static label_part_t *mbr_part_next(label_part_t *);
static void mbr_part_get_info(label_part_t *, label_part_info_t *);
static errno_t mbr_part_create(label_t *, label_part_spec_t *, label_part_t **);
static errno_t mbr_part_destroy(label_part_t *);
static errno_t mbr_suggest_ptype(label_t *, label_pcnt_t, label_ptype_t *);

static errno_t mbr_check_free_idx(label_t *, int);
static errno_t mbr_check_free_pri_range(label_t *, uint64_t, uint64_t);
static errno_t mbr_check_free_log_range(label_t *, uint64_t, uint64_t, uint64_t);

static void mbr_unused_pte(mbr_pte_t *);
static errno_t mbr_part_to_pte(label_part_t *, mbr_pte_t *);
static errno_t mbr_pte_to_part(label_t *, mbr_pte_t *, int);
static errno_t mbr_pte_to_log_part(label_t *, uint64_t, mbr_pte_t *);
static void mbr_log_part_to_ptes(label_part_t *, mbr_pte_t *, mbr_pte_t *);
static errno_t mbr_pte_update(label_t *, mbr_pte_t *, int);
static errno_t mbr_log_part_insert(label_t *, label_part_t *);
static errno_t mbr_ebr_create(label_t *, label_part_t *);
static errno_t mbr_ebr_delete(label_t *, label_part_t *);
static errno_t mbr_ebr_update_next(label_t *, label_part_t *);
static void mbr_update_log_indices(label_t *);

label_ops_t mbr_label_ops = {
        .open = mbr_open,
        .create = mbr_create,
        .close = mbr_close,
        .destroy = mbr_destroy,
        .get_info = mbr_get_info,
        .part_first = mbr_part_first,
        .part_next = mbr_part_next,
        .part_get_info = mbr_part_get_info,
        .part_create = mbr_part_create,
        .part_destroy = mbr_part_destroy,
        .suggest_ptype = mbr_suggest_ptype
};

static errno_t mbr_open(label_bd_t *bd, label_t **rlabel)
{
        label_t *label = NULL;
        mbr_br_block_t *mbr = NULL;
        fat_bs_t *bs;
        mbr_pte_t *eptr;
        uint16_t sgn;
        size_t bsize;
        aoff64_t nblocks;
        uint32_t entry;
        errno_t rc;

        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;
        }

        if (nblocks < mbr_ablock0) {
                rc = EINVAL;
                goto error;
        }

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

        bs = (fat_bs_t *)mbr;

        rc = bd->ops->read(bd->arg, mbr_ba, 1, mbr);
        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);

        /* Verify boot record signature */
        sgn = uint16_t_le2host(mbr->signature);
        if (sgn != mbr_br_signature) {
                rc = EIO;
                goto error;
        }

        /*
         * We can't really tell whether this is an MBR. Make sure
         * this is not actually the BR of a 12/16-bit FAT file system
         */
        if (bs->type[0] == 'F' && bs->type[1] == 'A' && bs->type[2] == 'T') {
                rc = EIO;
                goto error;
        }

        /*
         * Or a 32-bit FAT file system
         */
        if (bs->fat32.type[0] == 'F' && bs->fat32.type[1] == 'A' &&
            bs->fat32.type[2] == 'T') {
                rc = EIO;
                goto error;
        }

        label->ext_part = NULL;
        for (entry = 0; entry < mbr_nprimary; entry++) {
                eptr = &mbr->pte[entry];
                rc = mbr_pte_to_part(label, eptr, entry + 1);
                if (rc != EOK)
                        goto error;
        }

        free(mbr);
        mbr = NULL;

        label->ops = &mbr_label_ops;
        label->ltype = lt_mbr;
        label->bd = *bd;
        label->block_size = bsize;
        label->ablock0 = mbr_ablock0;
        label->anblocks = nblocks - mbr_ablock0;
        label->pri_entries = mbr_nprimary;

        if (label->ext_part != NULL) {
                /* Open extended partition */
                rc = mbr_open_ext(label);
                if (rc != EOK)
                        goto error;
        }

        *rlabel = label;
        return EOK;
error:
        free(mbr);
        mbr_close(label);
        return rc;
}

/** Open extended partition */
static errno_t mbr_open_ext(label_t *label)
{
        mbr_br_block_t *ebr = NULL;
        mbr_pte_t *ethis;
        mbr_pte_t *enext;
        uint64_t ebr_b0;
        uint64_t ebr_nblocks_min;
        uint64_t ebr_nblocks_max;
        uint64_t pebr_b0;
        uint64_t pebr_nblocks;
        uint64_t pb0;
        uint64_t pnblocks;
        uint64_t ep_b0;
        errno_t rc;

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

        /* First block of extended partition */
        ep_b0 = label->ext_part->block0;

        /* First block of current EBR */
        ebr_b0 = label->ext_part->block0;

        /*
         * We don't have bounds for the first EBR, so for purpose of
         * verification let's say it contains at least one block and
         * at most all blocks from the extended partition.
         */
        ebr_nblocks_min = 1;
        ebr_nblocks_max = label->ext_part->nblocks;

        while (true) {
                /* Read EBR */
                rc = label->bd.ops->read(label->bd.arg, ebr_b0, 1, ebr);
                if (rc != EOK) {
                        rc = EIO;
                        goto error;
                }

                ethis = &ebr->pte[mbr_ebr_pte_this];
                enext = &ebr->pte[mbr_ebr_pte_next];

                pb0 = ebr_b0 + uint32_t_le2host(ethis->first_lba);
                pnblocks = uint32_t_le2host(ethis->length);

                if (ethis->ptype == mbr_pt_unused || pnblocks == 0)
                        break;

                /* Verify partition lies within the range of EBR */
                if (pb0 + pnblocks > ebr_b0 + ebr_nblocks_max) {
                        rc = EIO;
                        goto error;
                }

                /* Create partition structure */
                rc = mbr_pte_to_log_part(label, ebr_b0, ethis);
                if (rc != EOK) {
                        rc = EIO;
                        goto error;
                }

                /* Save previous EBR range */
                pebr_b0 = ebr_b0;
                pebr_nblocks = ebr_nblocks_min;

                /* Proceed to next EBR */
                ebr_b0 = ep_b0 + uint32_t_le2host(enext->first_lba);
                ebr_nblocks_min = uint32_t_le2host(enext->length);
                ebr_nblocks_max = ebr_nblocks_min;

                if (enext->ptype == mbr_pt_unused || ebr_nblocks_min == 0)
                        break;

                /* Verify next EBR does not overlap this EBR */
                if (ebr_b0 < pebr_b0 + pebr_nblocks) {
                        rc = EIO;
                        goto error;
                }

                /* Verify next EBR does not extend beyond end of label */
                if (ebr_b0 + ebr_nblocks_max > label->ablock0 + label->anblocks) {
                        rc = EIO;
                        goto error;
                }
        }

        free(ebr);
        return EOK;
error:
        /* Note that logical partitions need to be deleted by caller */
        free(ebr);
        return rc;
}

static errno_t mbr_create(label_bd_t *bd, label_t **rlabel)
{
        label_t *label = NULL;
        mbr_br_block_t *mbr = NULL;
        aoff64_t nblocks;
        size_t bsize;
        int i;
        errno_t rc;

        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;
        }

        mbr = calloc(1, bsize);
        if (mbr == NULL) {
                rc = ENOMEM;
                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);

        mbr->media_id = 0;
        mbr->pad0 = 0;
        for (i = 0; i < mbr_nprimary; i++)
                mbr_unused_pte(&mbr->pte[i]);
        mbr->signature = host2uint16_t_le(mbr_br_signature);

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

        free(mbr);
        mbr = NULL;

        label->ops = &mbr_label_ops;
        label->ltype = lt_mbr;
        label->block_size = bsize;
        label->bd = *bd;
        label->ablock0 = mbr_ablock0;
        label->anblocks = nblocks - mbr_ablock0;
        label->pri_entries = mbr_nprimary;
        label->ext_part = NULL;

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

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

        if (label == NULL)
                return;

        part = mbr_part_first(label);
        while (part != NULL) {
                list_remove(&part->lparts);
                if (link_used(&part->lpri))
                        list_remove(&part->lpri);
                if (link_used(&part->llog))
                        list_remove(&part->llog);
                free(part);

                part = mbr_part_first(label);
        }

        free(label);
}

static errno_t mbr_destroy(label_t *label)
{
        mbr_br_block_t *mbr = NULL;
        label_part_t *part;
        errno_t rc;

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

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

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

        free(mbr);
        mbr = NULL;

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

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

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

static errno_t mbr_get_info(label_t *label, label_info_t *linfo)
{
        memset(linfo, 0, sizeof(label_info_t));
        linfo->ltype = lt_mbr;

        /* We support extended partitions */
        linfo->flags = lf_ext_supp;

        /** Can create primary if there is a free slot */
        if (list_count(&label->pri_parts) < mbr_nprimary)
                linfo->flags |= lf_can_create_pri;
        /* Can create extended if there is a free slot and no extended */
        if ((linfo->flags & lf_can_create_pri) != 0 && label->ext_part == NULL)
                linfo->flags |= lf_can_create_ext;
        /* Can create logical if there is an extended partition */
        if (label->ext_part != NULL)
                linfo->flags |= lf_can_create_log;
        /* Can delete partition */
        if (mbr_can_delete_part(label))
                linfo->flags |= lf_can_delete_part;
        /* Can modify partition */
        if (mbr_can_modify_part(label))
                linfo->flags |= lf_can_modify_part;

        linfo->ablock0 = label->ablock0;
        linfo->anblocks = label->anblocks;

        return EOK;
}

static label_part_t *mbr_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 *mbr_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 label_part_t *mbr_log_part_first(label_t *label)
{
        link_t *link;

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

        return list_get_instance(link, label_part_t, llog);
}

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

        link = list_next(&part->llog, &part->label->log_parts);
        if (link == NULL)
                return NULL;

        return list_get_instance(link, label_part_t, llog);
}

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

        link = list_prev(&part->llog, &part->label->log_parts);
        if (link == NULL)
                return NULL;

        return list_get_instance(link, label_part_t, llog);
}

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

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

        return list_get_instance(link, label_part_t, lpri);
}

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

        link = list_next(&part->lpri, &part->label->pri_parts);
        if (link == NULL)
                return NULL;

        return list_get_instance(link, label_part_t, lpri);
}

static void mbr_part_get_info(label_part_t *part, label_part_info_t *pinfo)
{
        pinfo->index = part->index;
        pinfo->block0 = part->block0;
        pinfo->nblocks = part->nblocks;

        if (link_used(&part->llog))
                pinfo->pkind = lpk_logical;
        else if (part->ptype.t.num == mbr_pt_extended)
                pinfo->pkind = lpk_extended;
        else
                pinfo->pkind = lpk_primary;
}

static errno_t mbr_part_create(label_t *label, label_part_spec_t *pspec,
    label_part_t **rpart)
{
        label_part_t *part;
        label_part_t *prev;
        label_part_t *next;
        mbr_pte_t pte;
        errno_t rc;

        if (pspec->ptype.fmt != lptf_num)
                return EINVAL;

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

        /* XXX Check if index is used */
        part->label = label;
        part->index = pspec->index;
        part->block0 = pspec->block0;
        part->nblocks = pspec->nblocks;
        part->hdr_blocks = pspec->hdr_blocks;

        switch (pspec->pkind) {
        case lpk_primary:
                part->ptype = pspec->ptype;
                break;
        case lpk_extended:
                part->ptype.fmt = lptf_num;
                part->ptype.t.num = mbr_pt_extended;
                if (pspec->ptype.t.num != 0) {
                        rc = EINVAL;
                        goto error;
                }
                if (label->ext_part != NULL) {
                        rc = EEXIST;
                        goto error;
                }
                break;
        case lpk_logical:
                part->ptype = pspec->ptype;
                if (pspec->index != 0) {
                        rc = EINVAL;
                        goto error;
                }
                break;
        }

        if (pspec->pkind != lpk_logical) {
                /* Primary or extended partition */

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

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

                if (pspec->hdr_blocks != 0) {
                        rc = EINVAL;
                        goto error;
                }

                rc = mbr_part_to_pte(part, &pte);
                if (rc != EOK) {
                        rc = EINVAL;
                        goto error;
                }

                rc = mbr_pte_update(label, &pte, pspec->index - 1);
                if (rc != EOK) {
                        rc = EIO;
                        goto error;
                }

                if (pspec->pkind == lpk_extended) {
                        label->ext_part = part;

                        /* Create EBR for empty partition chain */
                        rc = mbr_ebr_create(label, NULL);
                        if (rc != EOK) {
                                label->ext_part = NULL;
                                rc = EIO;
                                goto error;
                        }
                }

                list_append(&part->lparts, &label->parts);
                list_append(&part->lpri, &label->pri_parts);
        } else {
                /* Verify range is within bounds and free */
                rc = mbr_check_free_log_range(label, pspec->hdr_blocks,
                    pspec->block0, pspec->nblocks);
                if (rc != EOK) {
                        rc = EINVAL;
                        goto error;
                }

                /* Logical partition */
                rc = mbr_log_part_insert(label, part);
                if (rc != EOK)
                        goto error;

                /* Create EBR for new partition */
                rc = mbr_ebr_create(label, part);
                if (rc != EOK)
                        goto error;

                prev = mbr_log_part_prev(part);
                if (prev != NULL) {
                        /* Update 'next' PTE in EBR of previous partition */
                        rc = mbr_ebr_update_next(label, prev);
                        if (rc != EOK) {
                                goto error;
                        }
                } else {
                        /* New partition is now the first one */
                        next = mbr_log_part_next(part);
                        if (next != NULL) {
                                /*
                                 * Create new, relocated EBR for the former
                                 * first partition
                                 */
                                next->hdr_blocks = pspec->hdr_blocks;
                                rc = mbr_ebr_create(label, next);
                                if (rc != EOK)
                                        goto error;
                        }
                }

                /* This also sets index for the new partition. */
                mbr_update_log_indices(label);
        }

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

static errno_t mbr_part_destroy(label_part_t *part)
{
        mbr_pte_t pte;
        label_part_t *prev;
        label_part_t *next;
        uint64_t ep_b0;
        errno_t rc;

        if (link_used(&part->lpri)) {
                /* Primary/extended partition */

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

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

                /* If it was the extended partition, clear ext. part. pointer */
                if (part == part->label->ext_part)
                        part->label->ext_part = NULL;

                list_remove(&part->lpri);
        } else {
                /* Logical partition */

                prev = mbr_log_part_prev(part);
                if (prev != NULL) {
                        /* Update next link in previous EBR */
                        list_remove(&part->llog);

                        rc = mbr_ebr_update_next(part->label, prev);
                        if (rc != EOK) {
                                /* Roll back */
                                list_insert_after(&part->llog, &prev->llog);
                                return EIO;
                        }

                        /* Delete EBR */
                        rc = mbr_ebr_delete(part->label, part);
                        if (rc != EOK)
                                return EIO;
                } else {
                        next = mbr_log_part_next(part);
                        list_remove(&part->llog);

                        if (next != NULL) {
                                /*
                                 * Relocate next partition's EBR to the beginning
                                 * of the extended partition. This also
                                 * overwrites the EBR of the former first
                                 * partition.
                                 */

                                /* First block of extended partition */
                                ep_b0 = part->label->ext_part->block0;

                                next->hdr_blocks = next->block0 - ep_b0;

                                rc = mbr_ebr_create(part->label, next);
                                if (rc != EOK) {
                                        list_prepend(&part->llog, &part->label->log_parts);
                                        return EIO;
                                }
                        } else {
                                /* Delete EBR */
                                rc = mbr_ebr_delete(part->label, part);
                                if (rc != EOK)
                                        return EIO;
                        }
                }

                /* Update indices */
                mbr_update_log_indices(part->label);
        }

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

static errno_t mbr_suggest_ptype(label_t *label, label_pcnt_t pcnt,
    label_ptype_t *ptype)
{
        ptype->fmt = lptf_num;
        ptype->t.num = 0;

        switch (pcnt) {
        case lpc_exfat:
                ptype->t.num = mbr_pt_ms_advanced;
                break;
        case lpc_ext4:
                ptype->t.num = mbr_pt_linux;
                break;
        case lpc_fat12_16:
                ptype->t.num = mbr_pt_fat16_lba;
                break;
        case lpc_fat32:
                ptype->t.num = mbr_pt_fat32_lba;
                break;
        case lpc_minix:
                ptype->t.num = mbr_pt_minix;
                break;
        }

        if (ptype->t.num == 0)
                return EINVAL;

        return EOK;
}

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

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

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

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

        return EOK;
}

static errno_t mbr_check_free_pri_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 = mbr_pri_part_first(label);
        while (part != NULL) {
                if (mbr_overlap(block0, nblocks, part->block0, part->nblocks))
                        return EEXIST;
                part = mbr_pri_part_next(part);
        }

        return EOK;
}

static errno_t mbr_check_free_log_range(label_t *label, uint64_t hdr_blocks,
    uint64_t block0, uint64_t nblocks)
{
        label_part_t *part;

        if (block0 - hdr_blocks < label->ext_part->block0)
                return EINVAL;
        if (block0 + nblocks > label->ext_part->block0 + label->ext_part->nblocks)
                return EINVAL;

        part = mbr_log_part_first(label);
        while (part != NULL) {
                if (mbr_overlap(block0 - hdr_blocks, nblocks + hdr_blocks,
                    part->block0 - part->hdr_blocks, part->nblocks + part->hdr_blocks))
                        return EEXIST;
                part = mbr_log_part_next(part);
        }

        return EOK;
}

static void mbr_unused_pte(mbr_pte_t *pte)
{
        memset(pte, 0, sizeof(mbr_pte_t));
}

static errno_t mbr_part_to_pte(label_part_t *part, mbr_pte_t *pte)
{
        if ((part->block0 >> 32) != 0)
                return EINVAL;
        if ((part->nblocks >> 32) != 0)
                return EINVAL;
        if ((part->ptype.t.num >> 8) != 0)
                return EINVAL;

        memset(pte, 0, sizeof(mbr_pte_t));
        pte->ptype = part->ptype.t.num;
        pte->first_lba = host2uint32_t_le(part->block0);
        pte->length = host2uint32_t_le(part->nblocks);
        return EOK;
}

static errno_t mbr_pte_to_part(label_t *label, mbr_pte_t *pte, int index)
{
        label_part_t *part;
        uint32_t block0;
        uint32_t nblocks;

        block0 = uint32_t_le2host(pte->first_lba);
        nblocks = uint32_t_le2host(pte->length);

        /* See UEFI specification 2.0 section 5.2.1 Legacy Master Boot Record */
        if (pte->ptype == mbr_pt_unused || nblocks == 0)
                return EOK;

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

        part->ptype.fmt = lptf_num;
        part->ptype.t.num = pte->ptype;
        part->index = index;
        part->block0 = block0;
        part->nblocks = nblocks;

        /*
         * TODO: Verify
         *   - partition must reside on disk
         *   - partition must not overlap any other partition
         */

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

        if (pte->ptype == mbr_pt_extended)
                label->ext_part = part;
        return EOK;
}

static errno_t mbr_pte_to_log_part(label_t *label, uint64_t ebr_b0,
    mbr_pte_t *pte)
{
        label_part_t *part;
        uint32_t block0;
        uint32_t nblocks;
        size_t nlparts;

        block0 = ebr_b0 + uint32_t_le2host(pte->first_lba);
        nblocks = uint32_t_le2host(pte->length);

        if (pte->ptype == mbr_pt_unused || nblocks == 0)
                return EOK;

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

        nlparts = list_count(&label->log_parts);

        part->ptype.fmt = lptf_num;
        part->ptype.t.num = pte->ptype;
        part->index = mbr_nprimary + 1 + nlparts;
        part->block0 = block0;
        part->nblocks = nblocks;
        part->hdr_blocks = block0 - ebr_b0;

        part->label = label;
        list_append(&part->lparts, &label->parts);
        list_append(&part->llog, &label->log_parts);

        return EOK;
}

static void mbr_log_part_to_ptes(label_part_t *part, mbr_pte_t *pthis,
    mbr_pte_t *pnext)
{
        label_part_t *next;
        uint64_t ep_b0;
        uint64_t totsize;

        /* First block of extended partition */
        ep_b0 = part->label->ext_part->block0;

        assert(link_used(&part->llog));
        assert(part->block0 >= ep_b0);
        assert(part->hdr_blocks <= part->block0 - ep_b0);

        /* 'This' EBR entry */
        if (pthis != NULL) {
                memset(pthis, 0, sizeof(mbr_pte_t));
                pthis->ptype = part->ptype.t.num;
                pthis->first_lba = host2uint32_t_le(part->hdr_blocks);
                pthis->length = host2uint32_t_le(part->nblocks);
        }

        /* 'Next' EBR entry */
        if (pnext != NULL) {
                next = mbr_log_part_next(part);

                memset(pnext, 0, sizeof(mbr_pte_t));
                if (next != NULL) {
                        /* Total size of EBR + partition */
                        totsize = next->hdr_blocks + next->nblocks;

                        pnext->ptype = mbr_pt_extended;
                        pnext->first_lba = host2uint32_t_le(next->block0 -
                            next->hdr_blocks - ep_b0);
                        pnext->length = host2uint32_t_le(totsize);
                }
        }
}

/** Update partition table entry at specified index.
 *
 * Replace partition entry at index @a index with the contents of
 * @a pte.
 */
static errno_t mbr_pte_update(label_t *label, mbr_pte_t *pte, int index)
{
        mbr_br_block_t *br;
        errno_t rc;

        br = calloc(1, label->block_size);
        if (br == NULL)
                return ENOMEM;

        rc = label->bd.ops->read(label->bd.arg, mbr_ba, 1, br);
        if (rc != EOK) {
                rc = EIO;
                goto error;
        }

        br->pte[index] = *pte;

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

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

/** Insert logical partition into logical partition list. */
static errno_t mbr_log_part_insert(label_t *label, label_part_t *part)
{
        label_part_t *cur;

        cur = mbr_log_part_first(label);
        while (cur != NULL) {
                if (cur->block0 + cur->nblocks > part->block0)
                        break;
                cur = mbr_log_part_next(part);
        }

        if (cur != NULL)
                list_insert_before(&part->llog, &cur->llog);
        else
                list_append(&part->llog, &label->log_parts);

        return EOK;
}

/** Create EBR for partition.
 *
 * @param label Label
 * @param part Partition for which to create EBR or @c NULL to create
 *        EBR for empty partition chain
 * @return EOK on success or non-zero error code
 */
static errno_t mbr_ebr_create(label_t *label, label_part_t *part)
{
        mbr_br_block_t *br;
        uint64_t ba;
        errno_t rc;

        br = calloc(1, label->block_size);
        if (br == NULL)
                return ENOMEM;

        if (part != NULL) {
                ba = part->block0 - part->hdr_blocks;
                mbr_log_part_to_ptes(part, &br->pte[mbr_ebr_pte_this],
                    &br->pte[mbr_ebr_pte_next]);
        } else {
                ba = label->ext_part->block0;
        }

        br->signature = host2uint16_t_le(mbr_br_signature);

        rc = label->bd.ops->write(label->bd.arg, ba, 1, br);
        if (rc != EOK) {
                rc = EIO;
                goto error;
        }

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

static errno_t mbr_ebr_delete(label_t *label, label_part_t *part)
{
        mbr_br_block_t *br;
        uint64_t ba;
        errno_t rc;

        br = calloc(1, label->block_size);
        if (br == NULL)
                return ENOMEM;

        ba = part->block0 - part->hdr_blocks;

        rc = label->bd.ops->write(label->bd.arg, ba, 1, br);
        if (rc != EOK) {
                rc = EIO;
                goto error;
        }

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

/** Update 'next' PTE in EBR of partition. */
static errno_t mbr_ebr_update_next(label_t *label, label_part_t *part)
{
        mbr_br_block_t *br;
        uint64_t ba;
        uint16_t sgn;
        errno_t rc;

        ba = part->block0 - part->hdr_blocks;

        br = calloc(1, label->block_size);
        if (br == NULL)
                return ENOMEM;

        rc = label->bd.ops->read(label->bd.arg, ba, 1, br);
        if (rc != EOK) {
                rc = EIO;
                goto error;
        }

        /* Verify boot record signature */
        sgn = uint16_t_le2host(br->signature);
        if (sgn != mbr_br_signature) {
                rc = EIO;
                goto error;
        }

        mbr_log_part_to_ptes(part, NULL, &br->pte[mbr_ebr_pte_next]);

        rc = label->bd.ops->write(label->bd.arg, ba, 1, br);
        if (rc != EOK) {
                rc = EIO;
                goto error;
        }

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

/** Update indices of logical partitions.
 *
 * Logical partition indices are unstable, i.e. they can change during
 * the lifetime of a logical partition. Since the index corresponds to the
 * position of the partition in order of block address, anytime a partition
 * is created or deleted, indices of all partitions at higher addresses
 * change.
 */
static void mbr_update_log_indices(label_t *label)
{
        label_part_t *part;
        int idx;

        idx = mbr_nprimary + 1;

        part = mbr_log_part_first(label);
        while (part != NULL) {
                part->index = idx++;
                part = mbr_log_part_next(part);
        }
}

/** @}
 */