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/*
vbr.c (09.11.10)
Volume Boot Record creation code.
Free exFAT implementation.
Copyright (C) 2011-2015 Andrew Nayenko
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "vbr.h"
#include "fat.h"
#include "cbm.h"
#include "uct.h"
#include "rootdir.h"
#include <string.h>
static off_t vbr_alignment(void)
{
return get_sector_size();
}
static off_t vbr_size(void)
{
return 12 * get_sector_size();
}
static void init_sb(struct exfat_super_block* sb)
{
uint32_t clusters_max;
uint32_t fat_sectors;
clusters_max = get_volume_size() / get_cluster_size();
fat_sectors = DIV_ROUND_UP((off_t) clusters_max * sizeof(cluster_t),
get_sector_size());
memset(sb, 0, sizeof(struct exfat_super_block));
sb->jump[0] = 0xeb;
sb->jump[1] = 0x76;
sb->jump[2] = 0x90;
memcpy(sb->oem_name, "EXFAT ", sizeof(sb->oem_name));
sb->sector_start = cpu_to_le64(get_first_sector());
sb->sector_count = cpu_to_le64(get_volume_size() / get_sector_size());
sb->fat_sector_start = cpu_to_le32(
fat.get_alignment() / get_sector_size());
sb->fat_sector_count = cpu_to_le32(ROUND_UP(
le32_to_cpu(sb->fat_sector_start) + fat_sectors,
1 << get_spc_bits()) -
le32_to_cpu(sb->fat_sector_start));
sb->cluster_sector_start = cpu_to_le32(
get_position(&cbm) / get_sector_size());
sb->cluster_count = cpu_to_le32(clusters_max -
((le32_to_cpu(sb->fat_sector_start) +
le32_to_cpu(sb->fat_sector_count)) >> get_spc_bits()));
sb->rootdir_cluster = cpu_to_le32(
(get_position(&rootdir) - get_position(&cbm)) / get_cluster_size()
+ EXFAT_FIRST_DATA_CLUSTER);
sb->volume_serial = cpu_to_le32(get_volume_serial());
sb->version.major = 1;
sb->version.minor = 0;
sb->volume_state = cpu_to_le16(0);
sb->sector_bits = get_sector_bits();
sb->spc_bits = get_spc_bits();
sb->fat_count = 1;
sb->drive_no = 0x80;
sb->allocated_percent = 0;
sb->boot_signature = cpu_to_le16(0xaa55);
}
static int vbr_write(struct exfat_dev* dev)
{
struct exfat_super_block sb;
uint32_t checksum;
le32_t* sector = malloc(get_sector_size());
size_t i;
if (sector == NULL)
{
exfat_error("failed to allocate sector-sized block of memory");
return 1;
}
init_sb(&sb);
if (exfat_write(dev, &sb, sizeof(struct exfat_super_block)) < 0)
{
free(sector);
exfat_error("failed to write super block sector");
return 1;
}
checksum = exfat_vbr_start_checksum(&sb, sizeof(struct exfat_super_block));
memset(sector, 0, get_sector_size());
sector[get_sector_size() / sizeof(sector[0]) - 1] =
cpu_to_le32(0xaa550000);
for (i = 0; i < 8; i++)
{
if (exfat_write(dev, sector, get_sector_size()) < 0)
{
free(sector);
exfat_error("failed to write a sector with boot signature");
return 1;
}
checksum = exfat_vbr_add_checksum(sector, get_sector_size(), checksum);
}
memset(sector, 0, get_sector_size());
for (i = 0; i < 2; i++)
{
if (exfat_write(dev, sector, get_sector_size()) < 0)
{
free(sector);
exfat_error("failed to write an empty sector");
return 1;
}
checksum = exfat_vbr_add_checksum(sector, get_sector_size(), checksum);
}
for (i = 0; i < get_sector_size() / sizeof(sector[0]); i++)
sector[i] = cpu_to_le32(checksum);
if (exfat_write(dev, sector, get_sector_size()) < 0)
{
free(sector);
exfat_error("failed to write checksum sector");
return 1;
}
free(sector);
return 0;
}
const struct fs_object vbr =
{
.get_alignment = vbr_alignment,
.get_size = vbr_size,
.write = vbr_write,
};
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