mkfs/vbr.c

   1 /*
   2         vbr.c (09.11.10)
   3         Volume Boot Record creation code.
   4
   5         Copyright (C) 2011-2013  Andrew Nayenko
   6
   7         This program is free software: you can redistribute it and/or modify
   8         it under the terms of the GNU General Public License as published by
   9         the Free Software Foundation, either version 3 of the License, or
  10         (at your option) any later version.
  11
  12         This program is distributed in the hope that it will be useful,
  13         but WITHOUT ANY WARRANTY; without even the implied warranty of
  14         MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15         GNU General Public License for more details.
  16
  17         You should have received a copy of the GNU General Public License
  18         along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19 */
  20
  21 #include <string.h>
  22 #include "vbr.h"
  23 #include "fat.h"
  24 #include "cbm.h"
  25 #include "uct.h"
  26 #include "rootdir.h"
  27
  28 static off_t vbr_alignment(void)
  29 {
  30         return get_sector_size();
  31 }
  32
  33 static off_t vbr_size(void)
  34 {
  35         return 12 * get_sector_size();
  36 }
  37
  38 static void init_sb(struct exfat_super_block* sb)
  39 {
  40         uint32_t clusters_max;
  41         uint32_t fat_sectors;
  42
  43         clusters_max = get_volume_size() / get_cluster_size();
  44         fat_sectors = DIV_ROUND_UP((off_t) clusters_max * sizeof(cluster_t),
  45                         get_sector_size());
  46
  47         memset(sb, 0, sizeof(struct exfat_super_block));
  48         sb->jump[0] = 0xeb;
  49         sb->jump[1] = 0x76;
  50         sb->jump[2] = 0x90;
  51         memcpy(sb->oem_name, "EXFAT   ", sizeof(sb->oem_name));
  52         sb->sector_start = cpu_to_le64(get_first_sector());
  53         sb->sector_count = cpu_to_le64(get_volume_size() / get_sector_size());
  54         sb->fat_sector_start = cpu_to_le32(
  55                         fat.get_alignment() / get_sector_size());
  56         sb->fat_sector_count = cpu_to_le32(ROUND_UP(
  57                         le32_to_cpu(sb->fat_sector_start) + fat_sectors,
  58                                 1 << get_spc_bits()) -
  59                         le32_to_cpu(sb->fat_sector_start));
  60         sb->cluster_sector_start = cpu_to_le32(
  61                         get_position(&cbm) / get_sector_size());
  62         sb->cluster_count = cpu_to_le32(clusters_max -
  63                         ((le32_to_cpu(sb->fat_sector_start) +
  64                           le32_to_cpu(sb->fat_sector_count)) >> get_spc_bits()));
  65         sb->rootdir_cluster = cpu_to_le32(
  66                         (get_position(&rootdir) - get_position(&cbm)) / get_cluster_size()
  67                         + EXFAT_FIRST_DATA_CLUSTER);
  68         sb->volume_serial = cpu_to_le32(get_volume_serial());
  69         sb->version.major = 1;
  70         sb->version.minor = 0;
  71         sb->volume_state = cpu_to_le16(0);
  72         sb->sector_bits = get_sector_bits();
  73         sb->spc_bits = get_spc_bits();
  74         sb->fat_count = 1;
  75         sb->drive_no = 0x80;
  76         sb->allocated_percent = 0;
  77         sb->boot_signature = cpu_to_le16(0xaa55);
  78 }
  79
  80 static int vbr_write(struct exfat_dev* dev)
  81 {
  82         struct exfat_super_block sb;
  83         uint32_t checksum;
  84         le32_t* sector = malloc(get_sector_size());
  85         size_t i;
  86
  87         if (sector == NULL)
  88         {
  89                 exfat_error("failed to allocate sector-sized block of memory");
  90                 return 1;
  91         }
  92
  93         init_sb(&sb);
  94         if (exfat_write(dev, &sb, sizeof(struct exfat_super_block)) < 0)
  95         {
  96                 free(sector);
  97                 exfat_error("failed to write super block sector");
  98                 return 1;
  99         }
 100         checksum = exfat_vbr_start_checksum(&sb, sizeof(struct exfat_super_block));
 101
 102         memset(sector, 0, get_sector_size());
 103         sector[get_sector_size() / sizeof(sector[0]) - 1] =
 104                         cpu_to_le32(0xaa550000);
 105         for (i = 0; i < 8; i++)
 106         {
 107                 if (exfat_write(dev, sector, get_sector_size()) < 0)
 108                 {
 109                         free(sector);
 110                         exfat_error("failed to write a sector with boot signature");
 111                         return 1;
 112                 }
 113                 checksum = exfat_vbr_add_checksum(sector, get_sector_size(), checksum);
 114         }
 115
 116         memset(sector, 0, get_sector_size());
 117         for (i = 0; i < 2; i++)
 118         {
 119                 if (exfat_write(dev, sector, get_sector_size()) < 0)
 120                 {
 121                         free(sector);
 122                         exfat_error("failed to write an empty sector");
 123                         return 1;
 124                 }
 125                 checksum = exfat_vbr_add_checksum(sector, get_sector_size(), checksum);
 126         }
 127
 128         for (i = 0; i < get_sector_size() / sizeof(sector[0]); i++)
 129                 sector[i] = cpu_to_le32(checksum);
 130         if (exfat_write(dev, sector, get_sector_size()) < 0)
 131         {
 132                 free(sector);
 133                 exfat_error("failed to write checksum sector");
 134                 return 1;
 135         }
 136
 137         free(sector);
 138         return 0;
 139 }
 140
 141 const struct fs_object vbr =
 142 {
 143         .get_alignment = vbr_alignment,
 144         .get_size = vbr_size,
 145         .write = vbr_write,
 146 };