source: mainline/uspace/lib/mbr/libmbr.c@ d3a92c87

/*
 * Copyright (c) 2011 Dominik Taborsky
 * 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 libmbr
 * @{
 */
/** @file MBR extraxtion library
 */

#include <ipc/bd.h>
#include <async.h>
#include <stdio.h>
#include <block.h>
#include <errno.h>
#include <stdlib.h>
#include <assert.h>
#include <byteorder.h>

#include "libmbr.h"

static br_block_t * alloc_br(void);
static int decode_part(pt_entry_t * src, part_t * trgt, uint32_t base);
static int decode_logical(mbr_t * mbr, mbr_parts_t * p, part_t * ext);
static void encode_part(part_t * src, pt_entry_t * trgt, uint32_t base);

/** Read MBR from specific device
 * @param       dev_handle      device to read MBR from
 *
 * @return                              mbr record on success, NULL on error
 */
mbr_t * mbr_read_mbr(service_id_t dev_handle)
{
        int rc;

        mbr_t * mbr = malloc(sizeof(mbr_t));
        if (mbr == NULL) {
                return NULL;
        }

        rc = block_init(EXCHANGE_ATOMIC, dev_handle, 512);
        if (rc != EOK) {
                return NULL;
        }

        rc = block_read_direct(dev_handle, 0, 1, &(mbr->raw_data));
        if (rc != EOK) {
                block_fini(dev_handle);
                return NULL;
        }

        block_fini(dev_handle);

        mbr->device = dev_handle;
        //mbr->partitions = NULL;

        return mbr;
}

/** Write mbr to disk
 * @param mbr                   MBR to be written
 * @param dev_handle    device handle to write MBR to (may be different
 *                                                      from the device in 'mbr')
 *
 * @return                              0 on success, -1 on block_init error, -2 on write error
 */
int mbr_write_mbr(mbr_t * mbr, service_id_t dev_handle)
{
        int rc;

        rc = block_init(EXCHANGE_ATOMIC, dev_handle, 512);
        if (rc != EOK) {
                return rc;
        }

        rc = block_write_direct(dev_handle, 0, 1, &(mbr->raw_data));
        block_fini(dev_handle);
        if (rc != EOK) {
                return rc;
        }

        return 0;
}

/** Decide whether this is an actual MBR or a Protective MBR from GPT
 *
 * @param mbr           the actual MBR to decide upon
 *
 * @return                      1 if MBR, 0 if GPT
 */
int mbr_is_mbr(mbr_t * mbr)
{
        return (mbr->raw_data.pte[0].ptype != PT_GPT) ? 1 : 0;
}

/** Parse partitions from MBR
 * @param mbr   MBR to be parsed
 *
 * @return              linked list of partitions or NULL on error
 */
mbr_parts_t * mbr_read_partitions(mbr_t * mbr)
{
        int rc, i;
        part_t * p;
        part_t * ext = NULL;
        mbr_parts_t * parts;

        if (mbr == NULL)
                return NULL;

        parts = mbr_alloc_partitions();
        if (parts == NULL) {
                return NULL;
        }

        // Generate the primary partitions
        for (i = 0; i < N_PRIMARY; ++i) {
                if (mbr->raw_data.pte[i].ptype == PT_UNUSED)
                        continue;
                
                p = malloc(sizeof(part_t));
                if (p == NULL) {
                        printf(NAME ": Error on memory allocation.\n");
                        free(p);
                        mbr_free_partitions(parts);
                        return NULL;
                }
                list_append(&(p->link), &(parts->list));
                p->ebr = NULL;
                if (decode_part(&(mbr->raw_data.pte[i]), p, 0))
                        ext = p;
        }

        // Fill in the primary partitions and generate logical ones, if any
        rc = decode_logical(mbr, parts, ext);
        if (rc != EOK) {
                printf(NAME ": Error occured during decoding the MBR.\n" \
                           NAME ": Partition list may be incomplete.\n");
        }

        return parts;
}

/** Write MBR and partitions to device
 * @param parts                 partition list to be written
 * @param mbr                   MBR to be written with 'parts' partitions
 * @param dev_handle    device to write the data to
 *
 * @return                              returns EOK on succes, specific error code otherwise
 */
int mbr_write_partitions(mbr_parts_t * parts, mbr_t * mbr, service_id_t dev_handle)
{
        bool logical = false;
        int i = 0;
        int rc;
        part_t * p;
        part_t * ext = (parts->l_extended == NULL) ? NULL
                                        : list_get_instance(parts->l_extended, part_t, link);
        
        br_block_t * last_ebr = NULL;


        rc = block_init(EXCHANGE_ATOMIC, dev_handle, 512);
        if (rc != EOK) {
                return rc;
        }

        if (ext == NULL)
                goto no_extended;

        aoff64_t addr = ext->start_addr;
        part_t * prev_part = NULL;

        list_foreach(parts->list, it) {
                p = list_get_instance(it, part_t, link);
                if (mbr_get_flag(p, ST_LOGIC)) {
                        // writing logical partition

                        if (p->ebr == NULL) {
                                p->ebr = alloc_br();
                                if (p->ebr == NULL)
                                {
                                        rc = ENOMEM;
                                        goto end;
                                }
                        }


                        encode_part(p, &(p->ebr->pte[0]), addr);
                        if (prev_part != NULL) {
                                encode_part(p, &(prev_part->ebr->pte[1]), ext->start_addr);
                                rc = block_write_direct(dev_handle, p->start_addr, 1, prev_part->ebr);
                                if (rc != EOK)
                                        goto end;
                        }
                        
                        addr = p->start_addr;
                        prev_part = p;
                } else {
                        // writing primary partition
                        if (i >= 4) {
                                rc = EINVAL;
                                goto end;
                        }

                        encode_part(p, &(mbr->raw_data.pte[i]), 0);

                        ++i;
                }
        }

        /* If there was an extended but no logical, we should overwrite
         * the space where the first logical's EBR would have been. There
         * might be some garbage from the past.
         */
        
        last_ebr = prev_part->ebr;
        
        if (!logical)
        {
                last_ebr = alloc_br();
                if (last_ebr == NULL) {
                        rc = ENOMEM;
                        goto end;
                }
                
                last_ebr->pte[0].ptype = PT_UNUSED;
        }
        
        
        encode_part(NULL, &(last_ebr->pte[1]), 0);
        rc = block_write_direct(dev_handle, addr, 1, last_ebr);
        
        if (!logical)
        {
                free(last_ebr);
        }
        
        if (rc != EOK)
                goto end;

        goto skip;

no_extended:

        list_foreach(parts->list, it) {
                p = list_get_instance(it, part_t, link);
                if (mbr_get_flag(p, ST_LOGIC)) {
                        // extended does not exist, fail
                        return EINVAL;
                } else {
                        // writing primary partition
                        if (i >= 4)
                                return EINVAL;

                        encode_part(p, &(mbr->raw_data.pte[i]), 0);

                        ++i;
                }
        }

skip:
        rc = block_write_direct(dev_handle, 0, 1, &(mbr->raw_data));
        if (rc != EOK)
                goto end;

        /*
        for (i = 0; i < N_PRIMARY; ++i) {
                encode_part(&(p->partition), &(mbr->raw_data.pte[i]), 0);
                if (p->type == PT_EXTENDED)
                        ext = p;

                //p = list_get_instance(p->link.next, mbr_parts_t, link);
                p = p->next;
        }

        rc = block_write_direct(dev_handle, 0, 1, &(mbr->raw_data));
        if (rc != EOK) {
                block_fini(dev_handle);
                return rc;
        }

        //writing logical partitions

        if (p == NULL && ext != NULL) {
                //we need an empty EBR to rewrite the old EBR on disk, if we need to delete it
                br_block_t * temp_ebr = alloc_br();
                if (temp_ebr == NULL) {
                        block_fini(dev_handle);
                        return ENOMEM;
                }

                temp_ebr->pte[0].ptype = PT_UNUSED;
                encode_part(NULL, &(temp_ebr->pte[1]), 0);
                rc = block_write_direct(dev_handle, ext->start_addr, 1, temp_ebr);
                free(temp_ebr);
                block_fini(dev_handle);
                return rc;
        }

        if (p != NULL && ext == NULL) {
                block_fini(dev_handle);
                //no extended but one or more logical? EINVAL to the rescue!
                return EINVAL;
        }

        aoff64_t addr = ext->start_addr;

        while (p != NULL) {
                if (p->type == PT_UNUSED) {
                        p = p->next;
                        continue;
                }
                //encode_part(p, &(p->ebr->pte[0]), p->start_addr - 63 * 512);
                encode_part(p, &(p->ebr->pte[0]), addr);
                encode_part(p->next, &(p->ebr->pte[1]), ext->start_addr);

                rc = block_write_direct(dev_handle, p->start_addr, 1, p->ebr);
                if (rc != EOK) {
                        block_fini(dev_handle);
                        return rc;
                }
                addr = p->start_addr;
                p = p->next;
        }*/

        rc = EOK;
        
end:
        block_fini(dev_handle);

        return rc;
}

/** part_t constructor */
part_t * mbr_alloc_partition(void)
{
        part_t * p = malloc(sizeof(part_t));
        if (p == NULL) {
                return NULL;
        }
        link_initialize(&(p->link));
        p->ebr = NULL;
        p->type = 0;
        p->status = 0;
        p->start_addr = 0;
        p->length = 0;

        return p;
}

mbr_parts_t * mbr_alloc_partitions(void)
{
        mbr_parts_t * parts = malloc(sizeof(mbr_parts_t));
        if (parts == NULL) {
                return NULL;
        }

        list_initialize(&(parts->list));

        return parts;
}

/** Add partition */
void mbr_add_partition(mbr_parts_t * parts, part_t * partition)
{
        list_append(&(partition->link), &(parts->list));
}

/** Remove partition */
void mbr_remove_partition(mbr_parts_t * parts, int idx)
{
        link_t * l = list_nth(&(parts->list), idx);
        list_remove(l);
        part_t * p = list_get_instance(l, part_t, link);
        mbr_free_partition(p);
}

/** part_t destructor */
void mbr_free_partition(part_t * p)
{
        if (p->ebr != NULL)
                free(p->ebr);
        free(p);
}

/** Get flag bool value */
int mbr_get_flag(part_t * p, MBR_FLAGS flag)
{
        return (p->status & (1 << flag)) ? 1 : 0;
}

/** Set a specifig status flag to a value */
void mbr_set_flag(part_t * p, MBR_FLAGS flag, bool value)
{
        uint8_t status = p->status;

        if (value)
                status = status | (1 << flag);
        else
                status = status ^ (status & (1 << flag));

        p->status = status;
}

/** Just a wrapper for free() */
void mbr_free_mbr(mbr_t * mbr)
{
        free(mbr);
}

/** Free partition list
 *
 * @param parts         partition list to be freed
 */
void mbr_free_partitions(mbr_parts_t * parts)
{
        list_foreach_safe(parts->list, cur_link, next) {
                part_t * p = list_get_instance(cur_link, part_t, link);
                list_remove(cur_link);
                mbr_free_partition(p);
        }
}

// Internal functions follow //

static br_block_t * alloc_br()
{
        br_block_t * br = malloc(sizeof(br_block_t));
        if (br == NULL)
                return NULL;

        br->media_id = 0;
        br->pad0 = 0;
        br->signature = host2uint16_t_le(BR_SIGNATURE);

        return br;
}

/** Parse partition entry to part_t */
static int decode_part(pt_entry_t * src, part_t * trgt, uint32_t base)
{
        trgt->type = src->ptype;

        /* Checking only 0x80; otherwise writing will fix to 0x00 */
        //trgt->bootable = (src->status == B_ACTIVE) ? true : false;
        mbr_set_flag(trgt, ST_BOOT, (src->status == B_ACTIVE) ? true : false);

        trgt->start_addr = uint32_t_le2host(src->first_lba) + base;
        trgt->length = uint32_t_le2host(src->length);

        return (src->ptype == PT_EXTENDED) ? 1 : 0;
}

/** Parse MBR contents to part_t list
 * parameter 'p' is allocated for only used primary partitions
 */
static int decode_logical(mbr_t * mbr, mbr_parts_t * parts, part_t * ext)
{
        int rc;
        part_t * p;

        if (mbr == NULL || parts == NULL)
                return EINVAL;


        if (ext == NULL)
                return EOK;


        uint32_t addr = ext->start_addr;
        //uint32_t base = ext->start_addr;
        br_block_t * ebr;

        rc = block_init(EXCHANGE_ATOMIC, mbr->device, 512);
        if (rc != EOK)
                return rc;

        do {
                ebr = alloc_br();
                if (ebr == NULL) {
                        return ENOMEM;
                }

                rc = block_read_direct(mbr->device, addr, 1, ebr);
                if (rc != EOK) {
                        return rc;
                }

                //FIXME: is this the right way?
                if (uint16_t_le2host(ebr->signature) != BR_SIGNATURE) {
                        return EINVAL;
                }

                p = mbr_alloc_partition();

                decode_part(&(ebr->pte[0]), p, addr);
                mbr_set_flag(p, ST_LOGIC, true);
                p->ebr = ebr;
                mbr_add_partition(parts, p);

                //TODO: Check this code
                addr = ebr->pte[1].first_lba + ext->start_addr;
        } while (ebr->pte[1].ptype != PT_UNUSED);


        block_fini(mbr->device);

        return EOK;
}

/** Convert part_t to pt_entry_t */
static void encode_part(part_t * src, pt_entry_t * trgt, uint32_t base)
{
        if (src != NULL) {
                trgt->status = mbr_get_flag(src, ST_BOOT) ? B_ACTIVE : B_INACTIVE;
                trgt->ptype = src->type;
                trgt->first_lba = host2uint32_t_le(src->start_addr - base + 63); //63 sectors skipped
                trgt->length = host2uint32_t_le(src->length - 64);      //63 + 1 (EBR)
        } else {
                trgt->status = 0;
                trgt->first_chs[0] = 0;
                trgt->first_chs[1] = 0;
                trgt->first_chs[2] = 0;
                trgt->ptype = 0;
                trgt->last_chs[0] = 0;
                trgt->last_chs[1] = 0;
                trgt->last_chs[2] = 0;
                trgt->first_lba = 0;
                trgt->length = 0;
        }
}