cloop.c (9424B)
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/error-report.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 ret = bdrv_apply_auto_read_only(bs, NULL, errp); 70 if (ret < 0) { 71 return ret; 72 } 73 74 ret = bdrv_open_file_child(NULL, options, "file", bs, errp); 75 if (ret < 0) { 76 return ret; 77 } 78 79 /* read header */ 80 ret = bdrv_pread(bs->file, 128, 4, &s->block_size, 0); 81 if (ret < 0) { 82 return ret; 83 } 84 s->block_size = be32_to_cpu(s->block_size); 85 if (s->block_size % 512) { 86 error_setg(errp, "block_size %" PRIu32 " must be a multiple of 512", 87 s->block_size); 88 return -EINVAL; 89 } 90 if (s->block_size == 0) { 91 error_setg(errp, "block_size cannot be zero"); 92 return -EINVAL; 93 } 94 95 /* cloop's create_compressed_fs.c warns about block sizes beyond 256 KB but 96 * we can accept more. Prevent ridiculous values like 4 GB - 1 since we 97 * need a buffer this big. 98 */ 99 if (s->block_size > MAX_BLOCK_SIZE) { 100 error_setg(errp, "block_size %" PRIu32 " must be %u MB or less", 101 s->block_size, 102 MAX_BLOCK_SIZE / (1024 * 1024)); 103 return -EINVAL; 104 } 105 106 ret = bdrv_pread(bs->file, 128 + 4, 4, &s->n_blocks, 0); 107 if (ret < 0) { 108 return ret; 109 } 110 s->n_blocks = be32_to_cpu(s->n_blocks); 111 112 /* read offsets */ 113 if (s->n_blocks > (UINT32_MAX - 1) / sizeof(uint64_t)) { 114 /* Prevent integer overflow */ 115 error_setg(errp, "n_blocks %" PRIu32 " must be %zu or less", 116 s->n_blocks, 117 (UINT32_MAX - 1) / sizeof(uint64_t)); 118 return -EINVAL; 119 } 120 offsets_size = (s->n_blocks + 1) * sizeof(uint64_t); 121 if (offsets_size > 512 * 1024 * 1024) { 122 /* Prevent ridiculous offsets_size which causes memory allocation to 123 * fail or overflows bdrv_pread() size. In practice the 512 MB 124 * offsets[] limit supports 16 TB images at 256 KB block size. 125 */ 126 error_setg(errp, "image requires too many offsets, " 127 "try increasing block size"); 128 return -EINVAL; 129 } 130 131 s->offsets = g_try_malloc(offsets_size); 132 if (s->offsets == NULL) { 133 error_setg(errp, "Could not allocate offsets table"); 134 return -ENOMEM; 135 } 136 137 ret = bdrv_pread(bs->file, 128 + 4 + 4, offsets_size, s->offsets, 0); 138 if (ret < 0) { 139 goto fail; 140 } 141 142 for (i = 0; i < s->n_blocks + 1; i++) { 143 uint64_t size; 144 145 s->offsets[i] = be64_to_cpu(s->offsets[i]); 146 if (i == 0) { 147 continue; 148 } 149 150 if (s->offsets[i] < s->offsets[i - 1]) { 151 error_setg(errp, "offsets not monotonically increasing at " 152 "index %" PRIu32 ", image file is corrupt", i); 153 ret = -EINVAL; 154 goto fail; 155 } 156 157 size = s->offsets[i] - s->offsets[i - 1]; 158 159 /* Compressed blocks should be smaller than the uncompressed block size 160 * but maybe compression performed poorly so the compressed block is 161 * actually bigger. Clamp down on unrealistic values to prevent 162 * ridiculous s->compressed_block allocation. 163 */ 164 if (size > 2 * MAX_BLOCK_SIZE) { 165 error_setg(errp, "invalid compressed block size at index %" PRIu32 166 ", image file is corrupt", i); 167 ret = -EINVAL; 168 goto fail; 169 } 170 171 if (size > max_compressed_block_size) { 172 max_compressed_block_size = size; 173 } 174 } 175 176 /* initialize zlib engine */ 177 s->compressed_block = g_try_malloc(max_compressed_block_size + 1); 178 if (s->compressed_block == NULL) { 179 error_setg(errp, "Could not allocate compressed_block"); 180 ret = -ENOMEM; 181 goto fail; 182 } 183 184 s->uncompressed_block = g_try_malloc(s->block_size); 185 if (s->uncompressed_block == NULL) { 186 error_setg(errp, "Could not allocate uncompressed_block"); 187 ret = -ENOMEM; 188 goto fail; 189 } 190 191 if (inflateInit(&s->zstream) != Z_OK) { 192 ret = -EINVAL; 193 goto fail; 194 } 195 s->current_block = s->n_blocks; 196 197 s->sectors_per_block = s->block_size/512; 198 bs->total_sectors = s->n_blocks * s->sectors_per_block; 199 qemu_co_mutex_init(&s->lock); 200 return 0; 201 202 fail: 203 g_free(s->offsets); 204 g_free(s->compressed_block); 205 g_free(s->uncompressed_block); 206 return ret; 207 } 208 209 static void cloop_refresh_limits(BlockDriverState *bs, Error **errp) 210 { 211 bs->bl.request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O */ 212 } 213 214 static inline int cloop_read_block(BlockDriverState *bs, int block_num) 215 { 216 BDRVCloopState *s = bs->opaque; 217 218 if (s->current_block != block_num) { 219 int ret; 220 uint32_t bytes = s->offsets[block_num + 1] - s->offsets[block_num]; 221 222 ret = bdrv_pread(bs->file, s->offsets[block_num], bytes, 223 s->compressed_block, 0); 224 if (ret < 0) { 225 return -1; 226 } 227 228 s->zstream.next_in = s->compressed_block; 229 s->zstream.avail_in = bytes; 230 s->zstream.next_out = s->uncompressed_block; 231 s->zstream.avail_out = s->block_size; 232 ret = inflateReset(&s->zstream); 233 if (ret != Z_OK) { 234 return -1; 235 } 236 ret = inflate(&s->zstream, Z_FINISH); 237 if (ret != Z_STREAM_END || s->zstream.total_out != s->block_size) { 238 return -1; 239 } 240 241 s->current_block = block_num; 242 } 243 return 0; 244 } 245 246 static int coroutine_fn 247 cloop_co_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes, 248 QEMUIOVector *qiov, BdrvRequestFlags flags) 249 { 250 BDRVCloopState *s = bs->opaque; 251 uint64_t sector_num = offset >> BDRV_SECTOR_BITS; 252 int nb_sectors = bytes >> BDRV_SECTOR_BITS; 253 int ret, i; 254 255 assert(QEMU_IS_ALIGNED(offset, BDRV_SECTOR_SIZE)); 256 assert(QEMU_IS_ALIGNED(bytes, BDRV_SECTOR_SIZE)); 257 258 qemu_co_mutex_lock(&s->lock); 259 260 for (i = 0; i < nb_sectors; i++) { 261 void *data; 262 uint32_t sector_offset_in_block = 263 ((sector_num + i) % s->sectors_per_block), 264 block_num = (sector_num + i) / s->sectors_per_block; 265 if (cloop_read_block(bs, block_num) != 0) { 266 ret = -EIO; 267 goto fail; 268 } 269 270 data = s->uncompressed_block + sector_offset_in_block * 512; 271 qemu_iovec_from_buf(qiov, i * 512, data, 512); 272 } 273 274 ret = 0; 275 fail: 276 qemu_co_mutex_unlock(&s->lock); 277 278 return ret; 279 } 280 281 static void cloop_close(BlockDriverState *bs) 282 { 283 BDRVCloopState *s = bs->opaque; 284 g_free(s->offsets); 285 g_free(s->compressed_block); 286 g_free(s->uncompressed_block); 287 inflateEnd(&s->zstream); 288 } 289 290 static BlockDriver bdrv_cloop = { 291 .format_name = "cloop", 292 .instance_size = sizeof(BDRVCloopState), 293 .bdrv_probe = cloop_probe, 294 .bdrv_open = cloop_open, 295 .bdrv_child_perm = bdrv_default_perms, 296 .bdrv_refresh_limits = cloop_refresh_limits, 297 .bdrv_co_preadv = cloop_co_preadv, 298 .bdrv_close = cloop_close, 299 .is_format = true, 300 }; 301 302 static void bdrv_cloop_init(void) 303 { 304 bdrv_register(&bdrv_cloop); 305 } 306 307 block_init(bdrv_cloop_init);