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 31 /**************************************************************/ 32 33 #define HEADER_MAGIC "Bochs Virtual HD Image" 34 #define HEADER_VERSION 0x00020000 35 #define HEADER_V1 0x00010000 36 #define HEADER_SIZE 512 37 38 #define REDOLOG_TYPE "Redolog" 39 #define GROWING_TYPE "Growing" 40 41 // not allocated: 0xffffffff 42 43 // always little-endian 44 struct bochs_header { 45 char magic[32]; /* "Bochs Virtual HD Image" */ 46 char type[16]; /* "Redolog" */ 47 char subtype[16]; /* "Undoable" / "Volatile" / "Growing" */ 48 uint32_t version; 49 uint32_t header; /* size of header */ 50 51 uint32_t catalog; /* num of entries */ 52 uint32_t bitmap; /* bitmap size */ 53 uint32_t extent; /* extent size */ 54 55 union { 56 struct { 57 uint32_t reserved; /* for ??? */ 58 uint64_t disk; /* disk size */ 59 char padding[HEADER_SIZE - 64 - 20 - 12]; 60 } QEMU_PACKED redolog; 61 struct { 62 uint64_t disk; /* disk size */ 63 char padding[HEADER_SIZE - 64 - 20 - 8]; 64 } QEMU_PACKED redolog_v1; 65 char padding[HEADER_SIZE - 64 - 20]; 66 } extra; 67 } QEMU_PACKED; 68 69 typedef struct BDRVBochsState { 70 CoMutex lock; 71 uint32_t *catalog_bitmap; 72 uint32_t catalog_size; 73 74 uint32_t data_offset; 75 76 uint32_t bitmap_blocks; 77 uint32_t extent_blocks; 78 uint32_t extent_size; 79 } BDRVBochsState; 80 81 static int bochs_probe(const uint8_t *buf, int buf_size, const char *filename) 82 { 83 const struct bochs_header *bochs = (const void *)buf; 84 85 if (buf_size < HEADER_SIZE) 86 return 0; 87 88 if (!strcmp(bochs->magic, HEADER_MAGIC) && 89 !strcmp(bochs->type, REDOLOG_TYPE) && 90 !strcmp(bochs->subtype, GROWING_TYPE) && 91 ((le32_to_cpu(bochs->version) == HEADER_VERSION) || 92 (le32_to_cpu(bochs->version) == HEADER_V1))) 93 return 100; 94 95 return 0; 96 } 97 98 static int bochs_open(BlockDriverState *bs, QDict *options, int flags, 99 Error **errp) 100 { 101 BDRVBochsState *s = bs->opaque; 102 uint32_t i; 103 struct bochs_header bochs; 104 int ret; 105 106 bs->read_only = 1; // no write support yet 107 108 ret = bdrv_pread(bs->file->bs, 0, &bochs, sizeof(bochs)); 109 if (ret < 0) { 110 return ret; 111 } 112 113 if (strcmp(bochs.magic, HEADER_MAGIC) || 114 strcmp(bochs.type, REDOLOG_TYPE) || 115 strcmp(bochs.subtype, GROWING_TYPE) || 116 ((le32_to_cpu(bochs.version) != HEADER_VERSION) && 117 (le32_to_cpu(bochs.version) != HEADER_V1))) { 118 error_setg(errp, "Image not in Bochs format"); 119 return -EINVAL; 120 } 121 122 if (le32_to_cpu(bochs.version) == HEADER_V1) { 123 bs->total_sectors = le64_to_cpu(bochs.extra.redolog_v1.disk) / 512; 124 } else { 125 bs->total_sectors = le64_to_cpu(bochs.extra.redolog.disk) / 512; 126 } 127 128 /* Limit to 1M entries to avoid unbounded allocation. This is what is 129 * needed for the largest image that bximage can create (~8 TB). */ 130 s->catalog_size = le32_to_cpu(bochs.catalog); 131 if (s->catalog_size > 0x100000) { 132 error_setg(errp, "Catalog size is too large"); 133 return -EFBIG; 134 } 135 136 s->catalog_bitmap = g_try_new(uint32_t, s->catalog_size); 137 if (s->catalog_size && s->catalog_bitmap == NULL) { 138 error_setg(errp, "Could not allocate memory for catalog"); 139 return -ENOMEM; 140 } 141 142 ret = bdrv_pread(bs->file->bs, le32_to_cpu(bochs.header), s->catalog_bitmap, 143 s->catalog_size * 4); 144 if (ret < 0) { 145 goto fail; 146 } 147 148 for (i = 0; i < s->catalog_size; i++) 149 le32_to_cpus(&s->catalog_bitmap[i]); 150 151 s->data_offset = le32_to_cpu(bochs.header) + (s->catalog_size * 4); 152 153 s->bitmap_blocks = 1 + (le32_to_cpu(bochs.bitmap) - 1) / 512; 154 s->extent_blocks = 1 + (le32_to_cpu(bochs.extent) - 1) / 512; 155 156 s->extent_size = le32_to_cpu(bochs.extent); 157 if (s->extent_size < BDRV_SECTOR_SIZE) { 158 /* bximage actually never creates extents smaller than 4k */ 159 error_setg(errp, "Extent size must be at least 512"); 160 ret = -EINVAL; 161 goto fail; 162 } else if (!is_power_of_2(s->extent_size)) { 163 error_setg(errp, "Extent size %" PRIu32 " is not a power of two", 164 s->extent_size); 165 ret = -EINVAL; 166 goto fail; 167 } else if (s->extent_size > 0x800000) { 168 error_setg(errp, "Extent size %" PRIu32 " is too large", 169 s->extent_size); 170 ret = -EINVAL; 171 goto fail; 172 } 173 174 if (s->catalog_size < DIV_ROUND_UP(bs->total_sectors, 175 s->extent_size / BDRV_SECTOR_SIZE)) 176 { 177 error_setg(errp, "Catalog size is too small for this disk size"); 178 ret = -EINVAL; 179 goto fail; 180 } 181 182 qemu_co_mutex_init(&s->lock); 183 return 0; 184 185 fail: 186 g_free(s->catalog_bitmap); 187 return ret; 188 } 189 190 static int64_t seek_to_sector(BlockDriverState *bs, int64_t sector_num) 191 { 192 BDRVBochsState *s = bs->opaque; 193 uint64_t offset = sector_num * 512; 194 uint64_t extent_index, extent_offset, bitmap_offset; 195 char bitmap_entry; 196 int ret; 197 198 // seek to sector 199 extent_index = offset / s->extent_size; 200 extent_offset = (offset % s->extent_size) / 512; 201 202 if (s->catalog_bitmap[extent_index] == 0xffffffff) { 203 return 0; /* not allocated */ 204 } 205 206 bitmap_offset = s->data_offset + 207 (512 * (uint64_t) s->catalog_bitmap[extent_index] * 208 (s->extent_blocks + s->bitmap_blocks)); 209 210 /* read in bitmap for current extent */ 211 ret = bdrv_pread(bs->file->bs, bitmap_offset + (extent_offset / 8), 212 &bitmap_entry, 1); 213 if (ret < 0) { 214 return ret; 215 } 216 217 if (!((bitmap_entry >> (extent_offset % 8)) & 1)) { 218 return 0; /* not allocated */ 219 } 220 221 return bitmap_offset + (512 * (s->bitmap_blocks + extent_offset)); 222 } 223 224 static int bochs_read(BlockDriverState *bs, int64_t sector_num, 225 uint8_t *buf, int nb_sectors) 226 { 227 int ret; 228 229 while (nb_sectors > 0) { 230 int64_t block_offset = seek_to_sector(bs, sector_num); 231 if (block_offset < 0) { 232 return block_offset; 233 } else if (block_offset > 0) { 234 ret = bdrv_pread(bs->file->bs, block_offset, buf, 512); 235 if (ret < 0) { 236 return ret; 237 } 238 } else { 239 memset(buf, 0, 512); 240 } 241 nb_sectors--; 242 sector_num++; 243 buf += 512; 244 } 245 return 0; 246 } 247 248 static coroutine_fn int bochs_co_read(BlockDriverState *bs, int64_t sector_num, 249 uint8_t *buf, int nb_sectors) 250 { 251 int ret; 252 BDRVBochsState *s = bs->opaque; 253 qemu_co_mutex_lock(&s->lock); 254 ret = bochs_read(bs, sector_num, buf, nb_sectors); 255 qemu_co_mutex_unlock(&s->lock); 256 return ret; 257 } 258 259 static void bochs_close(BlockDriverState *bs) 260 { 261 BDRVBochsState *s = bs->opaque; 262 g_free(s->catalog_bitmap); 263 } 264 265 static BlockDriver bdrv_bochs = { 266 .format_name = "bochs", 267 .instance_size = sizeof(BDRVBochsState), 268 .bdrv_probe = bochs_probe, 269 .bdrv_open = bochs_open, 270 .bdrv_read = bochs_co_read, 271 .bdrv_close = bochs_close, 272 }; 273 274 static void bdrv_bochs_init(void) 275 { 276 bdrv_register(&bdrv_bochs); 277 } 278 279 block_init(bdrv_bochs_init); 280