1 /*
2 * Block driver for the various disk image formats used by Bochs
3 * Currently only for "growing" type in read-only mode
4 *
5 * Copyright (c) 2005 Alex Beregszaszi
6 *
7 * Permission is hereby granted, free of charge, to any person obtaining a copy
8 * of this software and associated documentation files (the "Software"), to deal
9 * in the Software without restriction, including without limitation the rights
10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
11 * copies of the Software, and to permit persons to whom the Software is
12 * furnished to do so, subject to the following conditions:
13 *
14 * The above copyright notice and this permission notice shall be included in
15 * all copies or substantial portions of the Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
20 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
23 * THE SOFTWARE.
24 */
25 #include "qemu-common.h"
26 #include "block_int.h"
27 #include "module.h"
28
29 /**************************************************************/
30
31 #define HEADER_MAGIC "Bochs Virtual HD Image"
32 #define HEADER_VERSION 0x00020000
33 #define HEADER_V1 0x00010000
34 #define HEADER_SIZE 512
35
36 #define REDOLOG_TYPE "Redolog"
37 #define GROWING_TYPE "Growing"
38
39 // not allocated: 0xffffffff
40
41 // always little-endian
42 struct bochs_header_v1 {
43 char magic[32]; // "Bochs Virtual HD Image"
44 char type[16]; // "Redolog"
45 char subtype[16]; // "Undoable" / "Volatile" / "Growing"
46 uint32_t version;
47 uint32_t header; // size of header
48
49 union {
50 struct {
51 uint32_t catalog; // num of entries
52 uint32_t bitmap; // bitmap size
53 uint32_t extent; // extent size
54 uint64_t disk; // disk size
55 char padding[HEADER_SIZE - 64 - 8 - 20];
56 } redolog;
57 char padding[HEADER_SIZE - 64 - 8];
58 } extra;
59 };
60
61 // always little-endian
62 struct bochs_header {
63 char magic[32]; // "Bochs Virtual HD Image"
64 char type[16]; // "Redolog"
65 char subtype[16]; // "Undoable" / "Volatile" / "Growing"
66 uint32_t version;
67 uint32_t header; // size of header
68
69 union {
70 struct {
71 uint32_t catalog; // num of entries
72 uint32_t bitmap; // bitmap size
73 uint32_t extent; // extent size
74 uint32_t reserved; // for ???
75 uint64_t disk; // disk size
76 char padding[HEADER_SIZE - 64 - 8 - 24];
77 } redolog;
78 char padding[HEADER_SIZE - 64 - 8];
79 } extra;
80 };
81
82 typedef struct BDRVBochsState {
83 uint32_t *catalog_bitmap;
84 int catalog_size;
85
86 int data_offset;
87
88 int bitmap_blocks;
89 int extent_blocks;
90 int extent_size;
91 } BDRVBochsState;
92
bochs_probe(const uint8_t * buf,int buf_size,const char * filename)93 static int bochs_probe(const uint8_t *buf, int buf_size, const char *filename)
94 {
95 const struct bochs_header *bochs = (const void *)buf;
96
97 if (buf_size < HEADER_SIZE)
98 return 0;
99
100 if (!strcmp(bochs->magic, HEADER_MAGIC) &&
101 !strcmp(bochs->type, REDOLOG_TYPE) &&
102 !strcmp(bochs->subtype, GROWING_TYPE) &&
103 ((le32_to_cpu(bochs->version) == HEADER_VERSION) ||
104 (le32_to_cpu(bochs->version) == HEADER_V1)))
105 return 100;
106
107 return 0;
108 }
109
bochs_open(BlockDriverState * bs,int flags)110 static int bochs_open(BlockDriverState *bs, int flags)
111 {
112 BDRVBochsState *s = bs->opaque;
113 int i;
114 struct bochs_header bochs;
115 struct bochs_header_v1 header_v1;
116
117 bs->read_only = 1; // no write support yet
118
119 if (bdrv_pread(bs->file, 0, &bochs, sizeof(bochs)) != sizeof(bochs)) {
120 goto fail;
121 }
122
123 if (strcmp(bochs.magic, HEADER_MAGIC) ||
124 strcmp(bochs.type, REDOLOG_TYPE) ||
125 strcmp(bochs.subtype, GROWING_TYPE) ||
126 ((le32_to_cpu(bochs.version) != HEADER_VERSION) &&
127 (le32_to_cpu(bochs.version) != HEADER_V1))) {
128 goto fail;
129 }
130
131 if (le32_to_cpu(bochs.version) == HEADER_V1) {
132 memcpy(&header_v1, &bochs, sizeof(bochs));
133 bs->total_sectors = le64_to_cpu(header_v1.extra.redolog.disk) / 512;
134 } else {
135 bs->total_sectors = le64_to_cpu(bochs.extra.redolog.disk) / 512;
136 }
137
138 s->catalog_size = le32_to_cpu(bochs.extra.redolog.catalog);
139 s->catalog_bitmap = qemu_malloc(s->catalog_size * 4);
140 if (bdrv_pread(bs->file, le32_to_cpu(bochs.header), s->catalog_bitmap,
141 s->catalog_size * 4) != s->catalog_size * 4)
142 goto fail;
143 for (i = 0; i < s->catalog_size; i++)
144 le32_to_cpus(&s->catalog_bitmap[i]);
145
146 s->data_offset = le32_to_cpu(bochs.header) + (s->catalog_size * 4);
147
148 s->bitmap_blocks = 1 + (le32_to_cpu(bochs.extra.redolog.bitmap) - 1) / 512;
149 s->extent_blocks = 1 + (le32_to_cpu(bochs.extra.redolog.extent) - 1) / 512;
150
151 s->extent_size = le32_to_cpu(bochs.extra.redolog.extent);
152
153 return 0;
154 fail:
155 return -1;
156 }
157
seek_to_sector(BlockDriverState * bs,int64_t sector_num)158 static int64_t seek_to_sector(BlockDriverState *bs, int64_t sector_num)
159 {
160 BDRVBochsState *s = bs->opaque;
161 int64_t offset = sector_num * 512;
162 int64_t extent_index, extent_offset, bitmap_offset;
163 char bitmap_entry;
164
165 // seek to sector
166 extent_index = offset / s->extent_size;
167 extent_offset = (offset % s->extent_size) / 512;
168
169 if (s->catalog_bitmap[extent_index] == 0xffffffff) {
170 return -1; /* not allocated */
171 }
172
173 bitmap_offset = s->data_offset + (512 * s->catalog_bitmap[extent_index] *
174 (s->extent_blocks + s->bitmap_blocks));
175
176 /* read in bitmap for current extent */
177 if (bdrv_pread(bs->file, bitmap_offset + (extent_offset / 8),
178 &bitmap_entry, 1) != 1) {
179 return -1;
180 }
181
182 if (!((bitmap_entry >> (extent_offset % 8)) & 1)) {
183 return -1; /* not allocated */
184 }
185
186 return bitmap_offset + (512 * (s->bitmap_blocks + extent_offset));
187 }
188
bochs_read(BlockDriverState * bs,int64_t sector_num,uint8_t * buf,int nb_sectors)189 static int bochs_read(BlockDriverState *bs, int64_t sector_num,
190 uint8_t *buf, int nb_sectors)
191 {
192 int ret;
193
194 while (nb_sectors > 0) {
195 int64_t block_offset = seek_to_sector(bs, sector_num);
196 if (block_offset >= 0) {
197 ret = bdrv_pread(bs->file, block_offset, buf, 512);
198 if (ret != 512) {
199 return -1;
200 }
201 } else
202 memset(buf, 0, 512);
203 nb_sectors--;
204 sector_num++;
205 buf += 512;
206 }
207 return 0;
208 }
209
bochs_close(BlockDriverState * bs)210 static void bochs_close(BlockDriverState *bs)
211 {
212 BDRVBochsState *s = bs->opaque;
213 qemu_free(s->catalog_bitmap);
214 }
215
216 static BlockDriver bdrv_bochs = {
217 .format_name = "bochs",
218 .instance_size = sizeof(BDRVBochsState),
219 .bdrv_probe = bochs_probe,
220 .bdrv_open = bochs_open,
221 .bdrv_read = bochs_read,
222 .bdrv_close = bochs_close,
223 };
224
bdrv_bochs_init(void)225 static void bdrv_bochs_init(void)
226 {
227 bdrv_register(&bdrv_bochs);
228 }
229
230 block_init(bdrv_bochs_init);
231