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bigbiff bigbiff9c754052013-01-09 09:09:08 -05001/*
2 vbr.c (09.11.10)
3 Volume Boot Record creation code.
4
bigbiff bigbiffca829c42013-01-28 08:14:25 -05005 Copyright (C) 2011-2013 Andrew Nayenko
bigbiff bigbiff9c754052013-01-09 09:09:08 -05006
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
28static off64_t vbr_alignment(void)
29{
30 return get_sector_size();
31}
32
33static off64_t vbr_size(void)
34{
35 return 12 * get_sector_size();
36}
37
38static 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((off64_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
80static 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
141const struct fs_object vbr =
142{
143 .get_alignment = vbr_alignment,
144 .get_size = vbr_size,
145 .write = vbr_write,
146};