linux-user: Use safe_syscall for open and openat system calls
[qemu.git] / block / cloop.c
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/osdep.h"
25 #include "qapi/error.h"
26 #include "qemu-common.h"
27 #include "block/block_int.h"
28 #include "qemu/module.h"
29 #include "qemu/bswap.h"
30 #include <zlib.h>
31
32 /* Maximum compressed block size */
33 #define MAX_BLOCK_SIZE (64 * 1024 * 1024)
34
35 typedef struct BDRVCloopState {
36 CoMutex lock;
37 uint32_t block_size;
38 uint32_t n_blocks;
39 uint64_t *offsets;
40 uint32_t sectors_per_block;
41 uint32_t current_block;
42 uint8_t *compressed_block;
43 uint8_t *uncompressed_block;
44 z_stream zstream;
45 } BDRVCloopState;
46
47 static int cloop_probe(const uint8_t *buf, int buf_size, const char *filename)
48 {
49 const char *magic_version_2_0 = "#!/bin/sh\n"
50 "#V2.0 Format\n"
51 "modprobe cloop file=$0 && mount -r -t iso9660 /dev/cloop $1\n";
52 int length = strlen(magic_version_2_0);
53 if (length > buf_size) {
54 length = buf_size;
55 }
56 if (!memcmp(magic_version_2_0, buf, length)) {
57 return 2;
58 }
59 return 0;
60 }
61
62 static int cloop_open(BlockDriverState *bs, QDict *options, int flags,
63 Error **errp)
64 {
65 BDRVCloopState *s = bs->opaque;
66 uint32_t offsets_size, max_compressed_block_size = 1, i;
67 int ret;
68
69 bs->read_only = 1;
70 bs->request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O supported */
71
72 /* read header */
73 ret = bdrv_pread(bs->file->bs, 128, &s->block_size, 4);
74 if (ret < 0) {
75 return ret;
76 }
77 s->block_size = be32_to_cpu(s->block_size);
78 if (s->block_size % 512) {
79 error_setg(errp, "block_size %" PRIu32 " must be a multiple of 512",
80 s->block_size);
81 return -EINVAL;
82 }
83 if (s->block_size == 0) {
84 error_setg(errp, "block_size cannot be zero");
85 return -EINVAL;
86 }
87
88 /* cloop's create_compressed_fs.c warns about block sizes beyond 256 KB but
89 * we can accept more. Prevent ridiculous values like 4 GB - 1 since we
90 * need a buffer this big.
91 */
92 if (s->block_size > MAX_BLOCK_SIZE) {
93 error_setg(errp, "block_size %" PRIu32 " must be %u MB or less",
94 s->block_size,
95 MAX_BLOCK_SIZE / (1024 * 1024));
96 return -EINVAL;
97 }
98
99 ret = bdrv_pread(bs->file->bs, 128 + 4, &s->n_blocks, 4);
100 if (ret < 0) {
101 return ret;
102 }
103 s->n_blocks = be32_to_cpu(s->n_blocks);
104
105 /* read offsets */
106 if (s->n_blocks > (UINT32_MAX - 1) / sizeof(uint64_t)) {
107 /* Prevent integer overflow */
108 error_setg(errp, "n_blocks %" PRIu32 " must be %zu or less",
109 s->n_blocks,
110 (UINT32_MAX - 1) / sizeof(uint64_t));
111 return -EINVAL;
112 }
113 offsets_size = (s->n_blocks + 1) * sizeof(uint64_t);
114 if (offsets_size > 512 * 1024 * 1024) {
115 /* Prevent ridiculous offsets_size which causes memory allocation to
116 * fail or overflows bdrv_pread() size. In practice the 512 MB
117 * offsets[] limit supports 16 TB images at 256 KB block size.
118 */
119 error_setg(errp, "image requires too many offsets, "
120 "try increasing block size");
121 return -EINVAL;
122 }
123
124 s->offsets = g_try_malloc(offsets_size);
125 if (s->offsets == NULL) {
126 error_setg(errp, "Could not allocate offsets table");
127 return -ENOMEM;
128 }
129
130 ret = bdrv_pread(bs->file->bs, 128 + 4 + 4, s->offsets, offsets_size);
131 if (ret < 0) {
132 goto fail;
133 }
134
135 for (i = 0; i < s->n_blocks + 1; i++) {
136 uint64_t size;
137
138 s->offsets[i] = be64_to_cpu(s->offsets[i]);
139 if (i == 0) {
140 continue;
141 }
142
143 if (s->offsets[i] < s->offsets[i - 1]) {
144 error_setg(errp, "offsets not monotonically increasing at "
145 "index %" PRIu32 ", image file is corrupt", i);
146 ret = -EINVAL;
147 goto fail;
148 }
149
150 size = s->offsets[i] - s->offsets[i - 1];
151
152 /* Compressed blocks should be smaller than the uncompressed block size
153 * but maybe compression performed poorly so the compressed block is
154 * actually bigger. Clamp down on unrealistic values to prevent
155 * ridiculous s->compressed_block allocation.
156 */
157 if (size > 2 * MAX_BLOCK_SIZE) {
158 error_setg(errp, "invalid compressed block size at index %" PRIu32
159 ", image file is corrupt", i);
160 ret = -EINVAL;
161 goto fail;
162 }
163
164 if (size > max_compressed_block_size) {
165 max_compressed_block_size = size;
166 }
167 }
168
169 /* initialize zlib engine */
170 s->compressed_block = g_try_malloc(max_compressed_block_size + 1);
171 if (s->compressed_block == NULL) {
172 error_setg(errp, "Could not allocate compressed_block");
173 ret = -ENOMEM;
174 goto fail;
175 }
176
177 s->uncompressed_block = g_try_malloc(s->block_size);
178 if (s->uncompressed_block == NULL) {
179 error_setg(errp, "Could not allocate uncompressed_block");
180 ret = -ENOMEM;
181 goto fail;
182 }
183
184 if (inflateInit(&s->zstream) != Z_OK) {
185 ret = -EINVAL;
186 goto fail;
187 }
188 s->current_block = s->n_blocks;
189
190 s->sectors_per_block = s->block_size/512;
191 bs->total_sectors = s->n_blocks * s->sectors_per_block;
192 qemu_co_mutex_init(&s->lock);
193 return 0;
194
195 fail:
196 g_free(s->offsets);
197 g_free(s->compressed_block);
198 g_free(s->uncompressed_block);
199 return ret;
200 }
201
202 static inline int cloop_read_block(BlockDriverState *bs, int block_num)
203 {
204 BDRVCloopState *s = bs->opaque;
205
206 if (s->current_block != block_num) {
207 int ret;
208 uint32_t bytes = s->offsets[block_num + 1] - s->offsets[block_num];
209
210 ret = bdrv_pread(bs->file->bs, s->offsets[block_num],
211 s->compressed_block, bytes);
212 if (ret != bytes) {
213 return -1;
214 }
215
216 s->zstream.next_in = s->compressed_block;
217 s->zstream.avail_in = bytes;
218 s->zstream.next_out = s->uncompressed_block;
219 s->zstream.avail_out = s->block_size;
220 ret = inflateReset(&s->zstream);
221 if (ret != Z_OK) {
222 return -1;
223 }
224 ret = inflate(&s->zstream, Z_FINISH);
225 if (ret != Z_STREAM_END || s->zstream.total_out != s->block_size) {
226 return -1;
227 }
228
229 s->current_block = block_num;
230 }
231 return 0;
232 }
233
234 static int coroutine_fn
235 cloop_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
236 QEMUIOVector *qiov, int flags)
237 {
238 BDRVCloopState *s = bs->opaque;
239 uint64_t sector_num = offset >> BDRV_SECTOR_BITS;
240 int nb_sectors = bytes >> BDRV_SECTOR_BITS;
241 int ret, i;
242
243 assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
244 assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
245
246 qemu_co_mutex_lock(&s->lock);
247
248 for (i = 0; i < nb_sectors; i++) {
249 void *data;
250 uint32_t sector_offset_in_block =
251 ((sector_num + i) % s->sectors_per_block),
252 block_num = (sector_num + i) / s->sectors_per_block;
253 if (cloop_read_block(bs, block_num) != 0) {
254 ret = -EIO;
255 goto fail;
256 }
257
258 data = s->uncompressed_block + sector_offset_in_block * 512;
259 qemu_iovec_from_buf(qiov, i * 512, data, 512);
260 }
261
262 ret = 0;
263 fail:
264 qemu_co_mutex_unlock(&s->lock);
265
266 return ret;
267 }
268
269 static void cloop_close(BlockDriverState *bs)
270 {
271 BDRVCloopState *s = bs->opaque;
272 g_free(s->offsets);
273 g_free(s->compressed_block);
274 g_free(s->uncompressed_block);
275 inflateEnd(&s->zstream);
276 }
277
278 static BlockDriver bdrv_cloop = {
279 .format_name = "cloop",
280 .instance_size = sizeof(BDRVCloopState),
281 .bdrv_probe = cloop_probe,
282 .bdrv_open = cloop_open,
283 .bdrv_co_preadv = cloop_co_preadv,
284 .bdrv_close = cloop_close,
285 };
286
287 static void bdrv_cloop_init(void)
288 {
289 bdrv_register(&bdrv_cloop);
290 }
291
292 block_init(bdrv_cloop_init);