bochs: Unify header structs and make them QEMU_PACKED
[qemu.git] / block / bochs.c
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/block_int.h"
27 #include "qemu/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 {
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 uint32_t catalog; /* num of entries */
50 uint32_t bitmap; /* bitmap size */
51 uint32_t extent; /* extent size */
52
53 union {
54 struct {
55 uint32_t reserved; /* for ??? */
56 uint64_t disk; /* disk size */
57 char padding[HEADER_SIZE - 64 - 20 - 12];
58 } QEMU_PACKED redolog;
59 struct {
60 uint64_t disk; /* disk size */
61 char padding[HEADER_SIZE - 64 - 20 - 8];
62 } QEMU_PACKED redolog_v1;
63 char padding[HEADER_SIZE - 64 - 20];
64 } extra;
65 } QEMU_PACKED;
66
67 typedef struct BDRVBochsState {
68 CoMutex lock;
69 uint32_t *catalog_bitmap;
70 int catalog_size;
71
72 int data_offset;
73
74 int bitmap_blocks;
75 int extent_blocks;
76 int extent_size;
77 } BDRVBochsState;
78
79 static int bochs_probe(const uint8_t *buf, int buf_size, const char *filename)
80 {
81 const struct bochs_header *bochs = (const void *)buf;
82
83 if (buf_size < HEADER_SIZE)
84 return 0;
85
86 if (!strcmp(bochs->magic, HEADER_MAGIC) &&
87 !strcmp(bochs->type, REDOLOG_TYPE) &&
88 !strcmp(bochs->subtype, GROWING_TYPE) &&
89 ((le32_to_cpu(bochs->version) == HEADER_VERSION) ||
90 (le32_to_cpu(bochs->version) == HEADER_V1)))
91 return 100;
92
93 return 0;
94 }
95
96 static int bochs_open(BlockDriverState *bs, QDict *options, int flags,
97 Error **errp)
98 {
99 BDRVBochsState *s = bs->opaque;
100 int i;
101 struct bochs_header bochs;
102 int ret;
103
104 bs->read_only = 1; // no write support yet
105
106 ret = bdrv_pread(bs->file, 0, &bochs, sizeof(bochs));
107 if (ret < 0) {
108 return ret;
109 }
110
111 if (strcmp(bochs.magic, HEADER_MAGIC) ||
112 strcmp(bochs.type, REDOLOG_TYPE) ||
113 strcmp(bochs.subtype, GROWING_TYPE) ||
114 ((le32_to_cpu(bochs.version) != HEADER_VERSION) &&
115 (le32_to_cpu(bochs.version) != HEADER_V1))) {
116 error_setg(errp, "Image not in Bochs format");
117 return -EINVAL;
118 }
119
120 if (le32_to_cpu(bochs.version) == HEADER_V1) {
121 bs->total_sectors = le64_to_cpu(bochs.extra.redolog_v1.disk) / 512;
122 } else {
123 bs->total_sectors = le64_to_cpu(bochs.extra.redolog.disk) / 512;
124 }
125
126 s->catalog_size = le32_to_cpu(bochs.catalog);
127 s->catalog_bitmap = g_malloc(s->catalog_size * 4);
128
129 ret = bdrv_pread(bs->file, le32_to_cpu(bochs.header), s->catalog_bitmap,
130 s->catalog_size * 4);
131 if (ret < 0) {
132 goto fail;
133 }
134
135 for (i = 0; i < s->catalog_size; i++)
136 le32_to_cpus(&s->catalog_bitmap[i]);
137
138 s->data_offset = le32_to_cpu(bochs.header) + (s->catalog_size * 4);
139
140 s->bitmap_blocks = 1 + (le32_to_cpu(bochs.bitmap) - 1) / 512;
141 s->extent_blocks = 1 + (le32_to_cpu(bochs.extent) - 1) / 512;
142
143 s->extent_size = le32_to_cpu(bochs.extent);
144
145 qemu_co_mutex_init(&s->lock);
146 return 0;
147
148 fail:
149 g_free(s->catalog_bitmap);
150 return ret;
151 }
152
153 static int64_t seek_to_sector(BlockDriverState *bs, int64_t sector_num)
154 {
155 BDRVBochsState *s = bs->opaque;
156 int64_t offset = sector_num * 512;
157 int64_t extent_index, extent_offset, bitmap_offset;
158 char bitmap_entry;
159
160 // seek to sector
161 extent_index = offset / s->extent_size;
162 extent_offset = (offset % s->extent_size) / 512;
163
164 if (s->catalog_bitmap[extent_index] == 0xffffffff) {
165 return -1; /* not allocated */
166 }
167
168 bitmap_offset = s->data_offset + (512 * s->catalog_bitmap[extent_index] *
169 (s->extent_blocks + s->bitmap_blocks));
170
171 /* read in bitmap for current extent */
172 if (bdrv_pread(bs->file, bitmap_offset + (extent_offset / 8),
173 &bitmap_entry, 1) != 1) {
174 return -1;
175 }
176
177 if (!((bitmap_entry >> (extent_offset % 8)) & 1)) {
178 return -1; /* not allocated */
179 }
180
181 return bitmap_offset + (512 * (s->bitmap_blocks + extent_offset));
182 }
183
184 static int bochs_read(BlockDriverState *bs, int64_t sector_num,
185 uint8_t *buf, int nb_sectors)
186 {
187 int ret;
188
189 while (nb_sectors > 0) {
190 int64_t block_offset = seek_to_sector(bs, sector_num);
191 if (block_offset >= 0) {
192 ret = bdrv_pread(bs->file, block_offset, buf, 512);
193 if (ret != 512) {
194 return -1;
195 }
196 } else
197 memset(buf, 0, 512);
198 nb_sectors--;
199 sector_num++;
200 buf += 512;
201 }
202 return 0;
203 }
204
205 static coroutine_fn int bochs_co_read(BlockDriverState *bs, int64_t sector_num,
206 uint8_t *buf, int nb_sectors)
207 {
208 int ret;
209 BDRVBochsState *s = bs->opaque;
210 qemu_co_mutex_lock(&s->lock);
211 ret = bochs_read(bs, sector_num, buf, nb_sectors);
212 qemu_co_mutex_unlock(&s->lock);
213 return ret;
214 }
215
216 static void bochs_close(BlockDriverState *bs)
217 {
218 BDRVBochsState *s = bs->opaque;
219 g_free(s->catalog_bitmap);
220 }
221
222 static BlockDriver bdrv_bochs = {
223 .format_name = "bochs",
224 .instance_size = sizeof(BDRVBochsState),
225 .bdrv_probe = bochs_probe,
226 .bdrv_open = bochs_open,
227 .bdrv_read = bochs_co_read,
228 .bdrv_close = bochs_close,
229 };
230
231 static void bdrv_bochs_init(void)
232 {
233 bdrv_register(&bdrv_bochs);
234 }
235
236 block_init(bdrv_bochs_init);