block: honor BDRV_O_ALLOW_RDWR when clearing bs->read_only
[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/osdep.h"
26 #include "qapi/error.h"
27 #include "qemu-common.h"
28 #include "block/block_int.h"
29 #include "qemu/module.h"
30 #include "qemu/bswap.h"
31
32 /**************************************************************/
33
34 #define HEADER_MAGIC "Bochs Virtual HD Image"
35 #define HEADER_VERSION 0x00020000
36 #define HEADER_V1 0x00010000
37 #define HEADER_SIZE 512
38
39 #define REDOLOG_TYPE "Redolog"
40 #define GROWING_TYPE "Growing"
41
42 // not allocated: 0xffffffff
43
44 // always little-endian
45 struct bochs_header {
46 char magic[32]; /* "Bochs Virtual HD Image" */
47 char type[16]; /* "Redolog" */
48 char subtype[16]; /* "Undoable" / "Volatile" / "Growing" */
49 uint32_t version;
50 uint32_t header; /* size of header */
51
52 uint32_t catalog; /* num of entries */
53 uint32_t bitmap; /* bitmap size */
54 uint32_t extent; /* extent size */
55
56 union {
57 struct {
58 uint32_t reserved; /* for ??? */
59 uint64_t disk; /* disk size */
60 char padding[HEADER_SIZE - 64 - 20 - 12];
61 } QEMU_PACKED redolog;
62 struct {
63 uint64_t disk; /* disk size */
64 char padding[HEADER_SIZE - 64 - 20 - 8];
65 } QEMU_PACKED redolog_v1;
66 char padding[HEADER_SIZE - 64 - 20];
67 } extra;
68 } QEMU_PACKED;
69
70 typedef struct BDRVBochsState {
71 CoMutex lock;
72 uint32_t *catalog_bitmap;
73 uint32_t catalog_size;
74
75 uint32_t data_offset;
76
77 uint32_t bitmap_blocks;
78 uint32_t extent_blocks;
79 uint32_t extent_size;
80 } BDRVBochsState;
81
82 static int bochs_probe(const uint8_t *buf, int buf_size, const char *filename)
83 {
84 const struct bochs_header *bochs = (const void *)buf;
85
86 if (buf_size < HEADER_SIZE)
87 return 0;
88
89 if (!strcmp(bochs->magic, HEADER_MAGIC) &&
90 !strcmp(bochs->type, REDOLOG_TYPE) &&
91 !strcmp(bochs->subtype, GROWING_TYPE) &&
92 ((le32_to_cpu(bochs->version) == HEADER_VERSION) ||
93 (le32_to_cpu(bochs->version) == HEADER_V1)))
94 return 100;
95
96 return 0;
97 }
98
99 static int bochs_open(BlockDriverState *bs, QDict *options, int flags,
100 Error **errp)
101 {
102 BDRVBochsState *s = bs->opaque;
103 uint32_t i;
104 struct bochs_header bochs;
105 int ret;
106
107 bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file,
108 false, errp);
109 if (!bs->file) {
110 return -EINVAL;
111 }
112
113 ret = bdrv_set_read_only(bs, true, errp); /* no write support yet */
114 if (ret < 0) {
115 return ret;
116 }
117
118 ret = bdrv_pread(bs->file, 0, &bochs, sizeof(bochs));
119 if (ret < 0) {
120 return ret;
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 error_setg(errp, "Image not in Bochs format");
129 return -EINVAL;
130 }
131
132 if (le32_to_cpu(bochs.version) == HEADER_V1) {
133 bs->total_sectors = le64_to_cpu(bochs.extra.redolog_v1.disk) / 512;
134 } else {
135 bs->total_sectors = le64_to_cpu(bochs.extra.redolog.disk) / 512;
136 }
137
138 /* Limit to 1M entries to avoid unbounded allocation. This is what is
139 * needed for the largest image that bximage can create (~8 TB). */
140 s->catalog_size = le32_to_cpu(bochs.catalog);
141 if (s->catalog_size > 0x100000) {
142 error_setg(errp, "Catalog size is too large");
143 return -EFBIG;
144 }
145
146 s->catalog_bitmap = g_try_new(uint32_t, s->catalog_size);
147 if (s->catalog_size && s->catalog_bitmap == NULL) {
148 error_setg(errp, "Could not allocate memory for catalog");
149 return -ENOMEM;
150 }
151
152 ret = bdrv_pread(bs->file, le32_to_cpu(bochs.header), s->catalog_bitmap,
153 s->catalog_size * 4);
154 if (ret < 0) {
155 goto fail;
156 }
157
158 for (i = 0; i < s->catalog_size; i++)
159 le32_to_cpus(&s->catalog_bitmap[i]);
160
161 s->data_offset = le32_to_cpu(bochs.header) + (s->catalog_size * 4);
162
163 s->bitmap_blocks = 1 + (le32_to_cpu(bochs.bitmap) - 1) / 512;
164 s->extent_blocks = 1 + (le32_to_cpu(bochs.extent) - 1) / 512;
165
166 s->extent_size = le32_to_cpu(bochs.extent);
167 if (s->extent_size < BDRV_SECTOR_SIZE) {
168 /* bximage actually never creates extents smaller than 4k */
169 error_setg(errp, "Extent size must be at least 512");
170 ret = -EINVAL;
171 goto fail;
172 } else if (!is_power_of_2(s->extent_size)) {
173 error_setg(errp, "Extent size %" PRIu32 " is not a power of two",
174 s->extent_size);
175 ret = -EINVAL;
176 goto fail;
177 } else if (s->extent_size > 0x800000) {
178 error_setg(errp, "Extent size %" PRIu32 " is too large",
179 s->extent_size);
180 ret = -EINVAL;
181 goto fail;
182 }
183
184 if (s->catalog_size < DIV_ROUND_UP(bs->total_sectors,
185 s->extent_size / BDRV_SECTOR_SIZE))
186 {
187 error_setg(errp, "Catalog size is too small for this disk size");
188 ret = -EINVAL;
189 goto fail;
190 }
191
192 qemu_co_mutex_init(&s->lock);
193 return 0;
194
195 fail:
196 g_free(s->catalog_bitmap);
197 return ret;
198 }
199
200 static void bochs_refresh_limits(BlockDriverState *bs, Error **errp)
201 {
202 bs->bl.request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O */
203 }
204
205 static int64_t seek_to_sector(BlockDriverState *bs, int64_t sector_num)
206 {
207 BDRVBochsState *s = bs->opaque;
208 uint64_t offset = sector_num * 512;
209 uint64_t extent_index, extent_offset, bitmap_offset;
210 char bitmap_entry;
211 int ret;
212
213 // seek to sector
214 extent_index = offset / s->extent_size;
215 extent_offset = (offset % s->extent_size) / 512;
216
217 if (s->catalog_bitmap[extent_index] == 0xffffffff) {
218 return 0; /* not allocated */
219 }
220
221 bitmap_offset = s->data_offset +
222 (512 * (uint64_t) s->catalog_bitmap[extent_index] *
223 (s->extent_blocks + s->bitmap_blocks));
224
225 /* read in bitmap for current extent */
226 ret = bdrv_pread(bs->file, bitmap_offset + (extent_offset / 8),
227 &bitmap_entry, 1);
228 if (ret < 0) {
229 return ret;
230 }
231
232 if (!((bitmap_entry >> (extent_offset % 8)) & 1)) {
233 return 0; /* not allocated */
234 }
235
236 return bitmap_offset + (512 * (s->bitmap_blocks + extent_offset));
237 }
238
239 static int coroutine_fn
240 bochs_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
241 QEMUIOVector *qiov, int flags)
242 {
243 BDRVBochsState *s = bs->opaque;
244 uint64_t sector_num = offset >> BDRV_SECTOR_BITS;
245 int nb_sectors = bytes >> BDRV_SECTOR_BITS;
246 uint64_t bytes_done = 0;
247 QEMUIOVector local_qiov;
248 int ret;
249
250 assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
251 assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
252
253 qemu_iovec_init(&local_qiov, qiov->niov);
254 qemu_co_mutex_lock(&s->lock);
255
256 while (nb_sectors > 0) {
257 int64_t block_offset = seek_to_sector(bs, sector_num);
258 if (block_offset < 0) {
259 ret = block_offset;
260 goto fail;
261 }
262
263 qemu_iovec_reset(&local_qiov);
264 qemu_iovec_concat(&local_qiov, qiov, bytes_done, 512);
265
266 if (block_offset > 0) {
267 ret = bdrv_co_preadv(bs->file, block_offset, 512,
268 &local_qiov, 0);
269 if (ret < 0) {
270 goto fail;
271 }
272 } else {
273 qemu_iovec_memset(&local_qiov, 0, 0, 512);
274 }
275 nb_sectors--;
276 sector_num++;
277 bytes_done += 512;
278 }
279
280 ret = 0;
281 fail:
282 qemu_co_mutex_unlock(&s->lock);
283 qemu_iovec_destroy(&local_qiov);
284
285 return ret;
286 }
287
288 static void bochs_close(BlockDriverState *bs)
289 {
290 BDRVBochsState *s = bs->opaque;
291 g_free(s->catalog_bitmap);
292 }
293
294 static BlockDriver bdrv_bochs = {
295 .format_name = "bochs",
296 .instance_size = sizeof(BDRVBochsState),
297 .bdrv_probe = bochs_probe,
298 .bdrv_open = bochs_open,
299 .bdrv_child_perm = bdrv_format_default_perms,
300 .bdrv_refresh_limits = bochs_refresh_limits,
301 .bdrv_co_preadv = bochs_co_preadv,
302 .bdrv_close = bochs_close,
303 };
304
305 static void bdrv_bochs_init(void)
306 {
307 bdrv_register(&bdrv_bochs);
308 }
309
310 block_init(bdrv_bochs_init);