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 s->offsets = g_malloc(offsets_size); 120 121 ret = bdrv_pread(bs->file, 128 + 4 + 4, s->offsets, offsets_size); 122 if (ret < 0) { 123 goto fail; 124 } 125 126 for (i = 0; i < s->n_blocks + 1; i++) { 127 uint64_t size; 128 129 s->offsets[i] = be64_to_cpu(s->offsets[i]); 130 if (i == 0) { 131 continue; 132 } 133 134 if (s->offsets[i] < s->offsets[i - 1]) { 135 error_setg(errp, "offsets not monotonically increasing at " 136 "index %" PRIu32 ", image file is corrupt", i); 137 ret = -EINVAL; 138 goto fail; 139 } 140 141 size = s->offsets[i] - s->offsets[i - 1]; 142 143 /* Compressed blocks should be smaller than the uncompressed block size 144 * but maybe compression performed poorly so the compressed block is 145 * actually bigger. Clamp down on unrealistic values to prevent 146 * ridiculous s->compressed_block allocation. 147 */ 148 if (size > 2 * MAX_BLOCK_SIZE) { 149 error_setg(errp, "invalid compressed block size at index %" PRIu32 150 ", image file is corrupt", i); 151 ret = -EINVAL; 152 goto fail; 153 } 154 155 if (size > max_compressed_block_size) { 156 max_compressed_block_size = size; 157 } 158 } 159 160 /* initialize zlib engine */ 161 s->compressed_block = g_malloc(max_compressed_block_size + 1); 162 s->uncompressed_block = g_malloc(s->block_size); 163 if (inflateInit(&s->zstream) != Z_OK) { 164 ret = -EINVAL; 165 goto fail; 166 } 167 s->current_block = s->n_blocks; 168 169 s->sectors_per_block = s->block_size/512; 170 bs->total_sectors = s->n_blocks * s->sectors_per_block; 171 qemu_co_mutex_init(&s->lock); 172 return 0; 173 174 fail: 175 g_free(s->offsets); 176 g_free(s->compressed_block); 177 g_free(s->uncompressed_block); 178 return ret; 179 } 180 181 static inline int cloop_read_block(BlockDriverState *bs, int block_num) 182 { 183 BDRVCloopState *s = bs->opaque; 184 185 if (s->current_block != block_num) { 186 int ret; 187 uint32_t bytes = s->offsets[block_num + 1] - s->offsets[block_num]; 188 189 ret = bdrv_pread(bs->file, s->offsets[block_num], s->compressed_block, 190 bytes); 191 if (ret != bytes) { 192 return -1; 193 } 194 195 s->zstream.next_in = s->compressed_block; 196 s->zstream.avail_in = bytes; 197 s->zstream.next_out = s->uncompressed_block; 198 s->zstream.avail_out = s->block_size; 199 ret = inflateReset(&s->zstream); 200 if (ret != Z_OK) { 201 return -1; 202 } 203 ret = inflate(&s->zstream, Z_FINISH); 204 if (ret != Z_STREAM_END || s->zstream.total_out != s->block_size) { 205 return -1; 206 } 207 208 s->current_block = block_num; 209 } 210 return 0; 211 } 212 213 static int cloop_read(BlockDriverState *bs, int64_t sector_num, 214 uint8_t *buf, int nb_sectors) 215 { 216 BDRVCloopState *s = bs->opaque; 217 int i; 218 219 for (i = 0; i < nb_sectors; i++) { 220 uint32_t sector_offset_in_block = 221 ((sector_num + i) % s->sectors_per_block), 222 block_num = (sector_num + i) / s->sectors_per_block; 223 if (cloop_read_block(bs, block_num) != 0) { 224 return -1; 225 } 226 memcpy(buf + i * 512, 227 s->uncompressed_block + sector_offset_in_block * 512, 512); 228 } 229 return 0; 230 } 231 232 static coroutine_fn int cloop_co_read(BlockDriverState *bs, int64_t sector_num, 233 uint8_t *buf, int nb_sectors) 234 { 235 int ret; 236 BDRVCloopState *s = bs->opaque; 237 qemu_co_mutex_lock(&s->lock); 238 ret = cloop_read(bs, sector_num, buf, nb_sectors); 239 qemu_co_mutex_unlock(&s->lock); 240 return ret; 241 } 242 243 static void cloop_close(BlockDriverState *bs) 244 { 245 BDRVCloopState *s = bs->opaque; 246 g_free(s->offsets); 247 g_free(s->compressed_block); 248 g_free(s->uncompressed_block); 249 inflateEnd(&s->zstream); 250 } 251 252 static BlockDriver bdrv_cloop = { 253 .format_name = "cloop", 254 .instance_size = sizeof(BDRVCloopState), 255 .bdrv_probe = cloop_probe, 256 .bdrv_open = cloop_open, 257 .bdrv_read = cloop_co_read, 258 .bdrv_close = cloop_close, 259 }; 260 261 static void bdrv_cloop_init(void) 262 { 263 bdrv_register(&bdrv_cloop); 264 } 265 266 block_init(bdrv_cloop_init); 267