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1 | /* | |
2 | * QEMU Block driver for CLOOP images | |
3 | * | |
4 | * Copyright (c) 2004 Johannes E. Schindelin | |
5 | * | |
6 | * Permission is hereby granted, free of charge, to any person obtaining a copy | |
7 | * of this software and associated documentation files (the "Software"), to deal | |
8 | * in the Software without restriction, including without limitation the rights | |
9 | * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell | |
10 | * copies of the Software, and to permit persons to whom the Software is | |
11 | * furnished to do so, subject to the following conditions: | |
12 | * | |
13 | * The above copyright notice and this permission notice shall be included in | |
14 | * all copies or substantial portions of the Software. | |
15 | * | |
16 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | |
17 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | |
18 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL | |
19 | * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | |
20 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, | |
21 | * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN | |
22 | * THE SOFTWARE. | |
23 | */ | |
24 | #include "qemu-common.h" | |
25 | #include "block/block_int.h" | |
26 | #include "qemu/module.h" | |
27 | #include <zlib.h> | |
28 | ||
29 | /* Maximum compressed block size */ | |
30 | #define MAX_BLOCK_SIZE (64 * 1024 * 1024) | |
31 | ||
32 | typedef struct BDRVCloopState { | |
33 | CoMutex lock; | |
34 | uint32_t block_size; | |
35 | uint32_t n_blocks; | |
36 | uint64_t *offsets; | |
37 | uint32_t sectors_per_block; | |
38 | uint32_t current_block; | |
39 | uint8_t *compressed_block; | |
40 | uint8_t *uncompressed_block; | |
41 | z_stream zstream; | |
42 | } BDRVCloopState; | |
43 | ||
44 | static int cloop_probe(const uint8_t *buf, int buf_size, const char *filename) | |
45 | { | |
46 | const char *magic_version_2_0 = "#!/bin/sh\n" | |
47 | "#V2.0 Format\n" | |
48 | "modprobe cloop file=$0 && mount -r -t iso9660 /dev/cloop $1\n"; | |
49 | int length = strlen(magic_version_2_0); | |
50 | if (length > buf_size) { | |
51 | length = buf_size; | |
52 | } | |
53 | if (!memcmp(magic_version_2_0, buf, length)) { | |
54 | return 2; | |
55 | } | |
56 | return 0; | |
57 | } | |
58 | ||
59 | static int cloop_open(BlockDriverState *bs, QDict *options, int flags, | |
60 | Error **errp) | |
61 | { | |
62 | BDRVCloopState *s = bs->opaque; | |
63 | uint32_t offsets_size, max_compressed_block_size = 1, i; | |
64 | int ret; | |
65 | ||
66 | bs->read_only = 1; | |
67 | ||
68 | /* read header */ | |
69 | ret = bdrv_pread(bs->file, 128, &s->block_size, 4); | |
70 | if (ret < 0) { | |
71 | return ret; | |
72 | } | |
73 | s->block_size = be32_to_cpu(s->block_size); | |
74 | if (s->block_size % 512) { | |
75 | error_setg(errp, "block_size %" PRIu32 " must be a multiple of 512", | |
76 | s->block_size); | |
77 | return -EINVAL; | |
78 | } | |
79 | if (s->block_size == 0) { | |
80 | error_setg(errp, "block_size cannot be zero"); | |
81 | return -EINVAL; | |
82 | } | |
83 | ||
84 | /* cloop's create_compressed_fs.c warns about block sizes beyond 256 KB but | |
85 | * we can accept more. Prevent ridiculous values like 4 GB - 1 since we | |
86 | * need a buffer this big. | |
87 | */ | |
88 | if (s->block_size > MAX_BLOCK_SIZE) { | |
89 | error_setg(errp, "block_size %" PRIu32 " must be %u MB or less", | |
90 | s->block_size, | |
91 | MAX_BLOCK_SIZE / (1024 * 1024)); | |
92 | return -EINVAL; | |
93 | } | |
94 | ||
95 | ret = bdrv_pread(bs->file, 128 + 4, &s->n_blocks, 4); | |
96 | if (ret < 0) { | |
97 | return ret; | |
98 | } | |
99 | s->n_blocks = be32_to_cpu(s->n_blocks); | |
100 | ||
101 | /* read offsets */ | |
102 | if (s->n_blocks > (UINT32_MAX - 1) / sizeof(uint64_t)) { | |
103 | /* Prevent integer overflow */ | |
104 | error_setg(errp, "n_blocks %" PRIu32 " must be %zu or less", | |
105 | s->n_blocks, | |
106 | (UINT32_MAX - 1) / sizeof(uint64_t)); | |
107 | return -EINVAL; | |
108 | } | |
109 | offsets_size = (s->n_blocks + 1) * sizeof(uint64_t); | |
110 | if (offsets_size > 512 * 1024 * 1024) { | |
111 | /* Prevent ridiculous offsets_size which causes memory allocation to | |
112 | * fail or overflows bdrv_pread() size. In practice the 512 MB | |
113 | * offsets[] limit supports 16 TB images at 256 KB block size. | |
114 | */ | |
115 | error_setg(errp, "image requires too many offsets, " | |
116 | "try increasing block size"); | |
117 | return -EINVAL; | |
118 | } | |
119 | ||
120 | s->offsets = g_try_malloc(offsets_size); | |
121 | if (s->offsets == NULL) { | |
122 | error_setg(errp, "Could not allocate offsets table"); | |
123 | return -ENOMEM; | |
124 | } | |
125 | ||
126 | ret = bdrv_pread(bs->file, 128 + 4 + 4, s->offsets, offsets_size); | |
127 | if (ret < 0) { | |
128 | goto fail; | |
129 | } | |
130 | ||
131 | for (i = 0; i < s->n_blocks + 1; i++) { | |
132 | uint64_t size; | |
133 | ||
134 | s->offsets[i] = be64_to_cpu(s->offsets[i]); | |
135 | if (i == 0) { | |
136 | continue; | |
137 | } | |
138 | ||
139 | if (s->offsets[i] < s->offsets[i - 1]) { | |
140 | error_setg(errp, "offsets not monotonically increasing at " | |
141 | "index %" PRIu32 ", image file is corrupt", i); | |
142 | ret = -EINVAL; | |
143 | goto fail; | |
144 | } | |
145 | ||
146 | size = s->offsets[i] - s->offsets[i - 1]; | |
147 | ||
148 | /* Compressed blocks should be smaller than the uncompressed block size | |
149 | * but maybe compression performed poorly so the compressed block is | |
150 | * actually bigger. Clamp down on unrealistic values to prevent | |
151 | * ridiculous s->compressed_block allocation. | |
152 | */ | |
153 | if (size > 2 * MAX_BLOCK_SIZE) { | |
154 | error_setg(errp, "invalid compressed block size at index %" PRIu32 | |
155 | ", image file is corrupt", i); | |
156 | ret = -EINVAL; | |
157 | goto fail; | |
158 | } | |
159 | ||
160 | if (size > max_compressed_block_size) { | |
161 | max_compressed_block_size = size; | |
162 | } | |
163 | } | |
164 | ||
165 | /* initialize zlib engine */ | |
166 | s->compressed_block = g_try_malloc(max_compressed_block_size + 1); | |
167 | if (s->compressed_block == NULL) { | |
168 | error_setg(errp, "Could not allocate compressed_block"); | |
169 | ret = -ENOMEM; | |
170 | goto fail; | |
171 | } | |
172 | ||
173 | s->uncompressed_block = g_try_malloc(s->block_size); | |
174 | if (s->uncompressed_block == NULL) { | |
175 | error_setg(errp, "Could not allocate uncompressed_block"); | |
176 | ret = -ENOMEM; | |
177 | goto fail; | |
178 | } | |
179 | ||
180 | if (inflateInit(&s->zstream) != Z_OK) { | |
181 | ret = -EINVAL; | |
182 | goto fail; | |
183 | } | |
184 | s->current_block = s->n_blocks; | |
185 | ||
186 | s->sectors_per_block = s->block_size/512; | |
187 | bs->total_sectors = s->n_blocks * s->sectors_per_block; | |
188 | qemu_co_mutex_init(&s->lock); | |
189 | return 0; | |
190 | ||
191 | fail: | |
192 | g_free(s->offsets); | |
193 | g_free(s->compressed_block); | |
194 | g_free(s->uncompressed_block); | |
195 | return ret; | |
196 | } | |
197 | ||
198 | static inline int cloop_read_block(BlockDriverState *bs, int block_num) | |
199 | { | |
200 | BDRVCloopState *s = bs->opaque; | |
201 | ||
202 | if (s->current_block != block_num) { | |
203 | int ret; | |
204 | uint32_t bytes = s->offsets[block_num + 1] - s->offsets[block_num]; | |
205 | ||
206 | ret = bdrv_pread(bs->file, s->offsets[block_num], s->compressed_block, | |
207 | bytes); | |
208 | if (ret != bytes) { | |
209 | return -1; | |
210 | } | |
211 | ||
212 | s->zstream.next_in = s->compressed_block; | |
213 | s->zstream.avail_in = bytes; | |
214 | s->zstream.next_out = s->uncompressed_block; | |
215 | s->zstream.avail_out = s->block_size; | |
216 | ret = inflateReset(&s->zstream); | |
217 | if (ret != Z_OK) { | |
218 | return -1; | |
219 | } | |
220 | ret = inflate(&s->zstream, Z_FINISH); | |
221 | if (ret != Z_STREAM_END || s->zstream.total_out != s->block_size) { | |
222 | return -1; | |
223 | } | |
224 | ||
225 | s->current_block = block_num; | |
226 | } | |
227 | return 0; | |
228 | } | |
229 | ||
230 | static int cloop_read(BlockDriverState *bs, int64_t sector_num, | |
231 | uint8_t *buf, int nb_sectors) | |
232 | { | |
233 | BDRVCloopState *s = bs->opaque; | |
234 | int i; | |
235 | ||
236 | for (i = 0; i < nb_sectors; i++) { | |
237 | uint32_t sector_offset_in_block = | |
238 | ((sector_num + i) % s->sectors_per_block), | |
239 | block_num = (sector_num + i) / s->sectors_per_block; | |
240 | if (cloop_read_block(bs, block_num) != 0) { | |
241 | return -1; | |
242 | } | |
243 | memcpy(buf + i * 512, | |
244 | s->uncompressed_block + sector_offset_in_block * 512, 512); | |
245 | } | |
246 | return 0; | |
247 | } | |
248 | ||
249 | static coroutine_fn int cloop_co_read(BlockDriverState *bs, int64_t sector_num, | |
250 | uint8_t *buf, int nb_sectors) | |
251 | { | |
252 | int ret; | |
253 | BDRVCloopState *s = bs->opaque; | |
254 | qemu_co_mutex_lock(&s->lock); | |
255 | ret = cloop_read(bs, sector_num, buf, nb_sectors); | |
256 | qemu_co_mutex_unlock(&s->lock); | |
257 | return ret; | |
258 | } | |
259 | ||
260 | static void cloop_close(BlockDriverState *bs) | |
261 | { | |
262 | BDRVCloopState *s = bs->opaque; | |
263 | g_free(s->offsets); | |
264 | g_free(s->compressed_block); | |
265 | g_free(s->uncompressed_block); | |
266 | inflateEnd(&s->zstream); | |
267 | } | |
268 | ||
269 | static BlockDriver bdrv_cloop = { | |
270 | .format_name = "cloop", | |
271 | .instance_size = sizeof(BDRVCloopState), | |
272 | .bdrv_probe = cloop_probe, | |
273 | .bdrv_open = cloop_open, | |
274 | .bdrv_read = cloop_co_read, | |
275 | .bdrv_close = cloop_close, | |
276 | }; | |
277 | ||
278 | static void bdrv_cloop_init(void) | |
279 | { | |
280 | bdrv_register(&bdrv_cloop); | |
281 | } | |
282 | ||
283 | block_init(bdrv_cloop_init); |