1/*
2 * Copyright (c) 2015 Grzegorz Kostka (kostka.grzegorz@gmail.com)
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *
9 * - Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * - Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * - The name of the author may not be used to endorse or promote products
15 * derived from this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29/** @addtogroup lwext4
30 * @{
31 */
32/**
33 * @file ext4_mbr.c
34 * @brief Master boot record parser
35 */
36
37#include <ext4_config.h>
38#include <ext4_types.h>
39#include <ext4_misc.h>
40#include <ext4_errno.h>
41#include <ext4_debug.h>
42
43#include <ext4_mbr.h>
44
45#include <inttypes.h>
46#include <string.h>
47
48#define MBR_SIGNATURE 0xAA55
49
50#pragma pack(push, 1)
51
52struct ext4_part_entry {
53 uint8_t status;
54 uint8_t chs1[3];
55 uint8_t type;
56 uint8_t chs2[3];
57 uint32_t first_lba;
58 uint32_t sectors;
59};
60
61struct ext4_mbr {
62 uint8_t bootstrap[442];
63 uint32_t disk_id;
64 struct ext4_part_entry part_entry[4];
65 uint16_t signature;
66};
67
68#pragma pack(pop)
69
70int ext4_mbr_scan(struct ext4_blockdev *parent, struct ext4_mbr_bdevs *bdevs)
71{
72 int r;
73 size_t i;
74
75 ext4_dbg(DEBUG_MBR, DBG_INFO "ext4_mbr_scan\n");
76 memset(dest: bdevs, c: 0, size: sizeof(struct ext4_mbr_bdevs));
77 r = ext4_block_init(bdev: parent);
78 if (r != EOK)
79 return r;
80
81 r = ext4_block_readbytes(bdev: parent, off: 0, buf: parent->bdif->ph_bbuf, len: 512);
82 if (r != EOK) {
83 goto blockdev_fini;
84 }
85
86 const struct ext4_mbr *mbr = (void *)parent->bdif->ph_bbuf;
87
88 if (to_le16(mbr->signature) != MBR_SIGNATURE) {
89 ext4_dbg(DEBUG_MBR, DBG_ERROR "ext4_mbr_scan: unknown "
90 "signature: 0x%x\n", to_le16(mbr->signature));
91 r = ENOENT;
92 goto blockdev_fini;
93 }
94
95 /*Show bootstrap code*/
96 ext4_dbg(DEBUG_MBR, "mbr_part: bootstrap:");
97 for (i = 0; i < sizeof(mbr->bootstrap); ++i) {
98 if (!(i & 0xF))
99 ext4_dbg(DEBUG_MBR | DEBUG_NOPREFIX, "\n");
100 ext4_dbg(DEBUG_MBR | DEBUG_NOPREFIX, "%02x, ", mbr->bootstrap[i]);
101 }
102
103 ext4_dbg(DEBUG_MBR | DEBUG_NOPREFIX, "\n\n");
104 for (i = 0; i < 4; ++i) {
105 const struct ext4_part_entry *pe = &mbr->part_entry[i];
106 ext4_dbg(DEBUG_MBR, "mbr_part: %d\n", (int)i);
107 ext4_dbg(DEBUG_MBR, "\tstatus: 0x%x\n", pe->status);
108 ext4_dbg(DEBUG_MBR, "\ttype 0x%x:\n", pe->type);
109 ext4_dbg(DEBUG_MBR, "\tfirst_lba: 0x%"PRIx32"\n", pe->first_lba);
110 ext4_dbg(DEBUG_MBR, "\tsectors: 0x%"PRIx32"\n", pe->sectors);
111
112 if (!pe->sectors)
113 continue; /*Empty entry*/
114
115 if (pe->type != 0x83)
116 continue; /*Unsupported entry. 0x83 - linux native*/
117
118 bdevs->partitions[i].bdif = parent->bdif;
119 bdevs->partitions[i].part_offset =
120 (uint64_t)pe->first_lba * parent->bdif->ph_bsize;
121 bdevs->partitions[i].part_size =
122 (uint64_t)pe->sectors * parent->bdif->ph_bsize;
123 }
124
125 blockdev_fini:
126 ext4_block_fini(bdev: parent);
127 return r;
128}
129
130int ext4_mbr_write(struct ext4_blockdev *parent, struct ext4_mbr_parts *parts, uint32_t disk_id)
131{
132 int r;
133 uint64_t disk_size;
134 uint32_t division_sum = parts->division[0] + parts->division[1] +
135 parts->division[2] + parts->division[3];
136
137 if (division_sum > 100)
138 return EINVAL;
139
140 ext4_dbg(DEBUG_MBR, DBG_INFO "ext4_mbr_write\n");
141 r = ext4_block_init(bdev: parent);
142 if (r != EOK)
143 return r;
144
145 disk_size = parent->part_size;
146
147 /*Calculate CHS*/
148 uint32_t k = 16;
149 while ((k < 256) && ((disk_size / k / 63) > 1024))
150 k *= 2;
151
152 if (k == 256)
153 --k;
154
155 const uint32_t cyl_size = 63 * k;
156 const uint32_t cyl_count = disk_size / cyl_size;
157
158 struct ext4_mbr *mbr = (void *)parent->bdif->ph_bbuf;
159 memset(dest: mbr, c: 0, size: sizeof(struct ext4_mbr));
160
161 mbr->disk_id = disk_id;
162
163 uint32_t cyl_it = 0;
164 for (int i = 0; i < 4; ++i) {
165 uint32_t cyl_part = cyl_count * parts->division[i] / 100;
166 if (!cyl_part)
167 continue;
168
169 uint32_t part_start = cyl_it * cyl_size;
170 uint32_t part_size = cyl_part * cyl_size;
171
172 if (i == 0) {
173 part_start += 63;
174 part_size -= 63 * parent->bdif->ph_bsize;
175 }
176
177 uint32_t cyl_end = cyl_part + cyl_it - 1;
178
179 mbr->part_entry[i].status = 0;
180 mbr->part_entry[i].chs1[0] = i ? 0 : 1;;
181 mbr->part_entry[i].chs1[1] = (cyl_it >> 2) + 1;
182 mbr->part_entry[i].chs1[2] = cyl_it;
183 mbr->part_entry[i].type = 0x83;
184 mbr->part_entry[i].chs2[0] = k - 1;
185 mbr->part_entry[i].chs2[1] = (cyl_end >> 2) + 63;
186 mbr->part_entry[i].chs2[2] = cyl_end;
187
188 mbr->part_entry[i].first_lba = part_start;
189 mbr->part_entry[i].sectors = part_size / parent->bdif->ph_bsize;
190
191 cyl_it += cyl_part;
192 }
193
194 mbr->signature = MBR_SIGNATURE;
195 r = ext4_block_writebytes(bdev: parent, off: 0, buf: parent->bdif->ph_bbuf, len: 512);
196 if (r != EOK)
197 goto blockdev_fini;
198
199
200 blockdev_fini:
201 ext4_block_fini(bdev: parent);
202 return r;
203}
204
205/**
206 * @}
207 */
208
209