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 "qemu-common.h" 27 #include "block/block_int.h" 28 #include "qemu/module.h" 29 30 /**************************************************************/ 31 32 #define HEADER_MAGIC "Bochs Virtual HD Image" 33 #define HEADER_VERSION 0x00020000 34 #define HEADER_V1 0x00010000 35 #define HEADER_SIZE 512 36 37 #define REDOLOG_TYPE "Redolog" 38 #define GROWING_TYPE "Growing" 39 40 // not allocated: 0xffffffff 41 42 // always little-endian 43 struct bochs_header { 44 char magic[32]; /* "Bochs Virtual HD Image" */ 45 char type[16]; /* "Redolog" */ 46 char subtype[16]; /* "Undoable" / "Volatile" / "Growing" */ 47 uint32_t version; 48 uint32_t header; /* size of header */ 49 50 uint32_t catalog; /* num of entries */ 51 uint32_t bitmap; /* bitmap size */ 52 uint32_t extent; /* extent size */ 53 54 union { 55 struct { 56 uint32_t reserved; /* for ??? */ 57 uint64_t disk; /* disk size */ 58 char padding[HEADER_SIZE - 64 - 20 - 12]; 59 } QEMU_PACKED redolog; 60 struct { 61 uint64_t disk; /* disk size */ 62 char padding[HEADER_SIZE - 64 - 20 - 8]; 63 } QEMU_PACKED redolog_v1; 64 char padding[HEADER_SIZE - 64 - 20]; 65 } extra; 66 } QEMU_PACKED; 67 68 typedef struct BDRVBochsState { 69 CoMutex lock; 70 uint32_t *catalog_bitmap; 71 uint32_t catalog_size; 72 73 uint32_t data_offset; 74 75 uint32_t bitmap_blocks; 76 uint32_t extent_blocks; 77 uint32_t extent_size; 78 } BDRVBochsState; 79 80 static int bochs_probe(const uint8_t *buf, int buf_size, const char *filename) 81 { 82 const struct bochs_header *bochs = (const void *)buf; 83 84 if (buf_size < HEADER_SIZE) 85 return 0; 86 87 if (!strcmp(bochs->magic, HEADER_MAGIC) && 88 !strcmp(bochs->type, REDOLOG_TYPE) && 89 !strcmp(bochs->subtype, GROWING_TYPE) && 90 ((le32_to_cpu(bochs->version) == HEADER_VERSION) || 91 (le32_to_cpu(bochs->version) == HEADER_V1))) 92 return 100; 93 94 return 0; 95 } 96 97 static int bochs_open(BlockDriverState *bs, QDict *options, int flags, 98 Error **errp) 99 { 100 BDRVBochsState *s = bs->opaque; 101 uint32_t i; 102 struct bochs_header bochs; 103 int ret; 104 105 bs->read_only = 1; // no write support yet 106 107 ret = bdrv_pread(bs->file->bs, 0, &bochs, sizeof(bochs)); 108 if (ret < 0) { 109 return ret; 110 } 111 112 if (strcmp(bochs.magic, HEADER_MAGIC) || 113 strcmp(bochs.type, REDOLOG_TYPE) || 114 strcmp(bochs.subtype, GROWING_TYPE) || 115 ((le32_to_cpu(bochs.version) != HEADER_VERSION) && 116 (le32_to_cpu(bochs.version) != HEADER_V1))) { 117 error_setg(errp, "Image not in Bochs format"); 118 return -EINVAL; 119 } 120 121 if (le32_to_cpu(bochs.version) == HEADER_V1) { 122 bs->total_sectors = le64_to_cpu(bochs.extra.redolog_v1.disk) / 512; 123 } else { 124 bs->total_sectors = le64_to_cpu(bochs.extra.redolog.disk) / 512; 125 } 126 127 /* Limit to 1M entries to avoid unbounded allocation. This is what is 128 * needed for the largest image that bximage can create (~8 TB). */ 129 s->catalog_size = le32_to_cpu(bochs.catalog); 130 if (s->catalog_size > 0x100000) { 131 error_setg(errp, "Catalog size is too large"); 132 return -EFBIG; 133 } 134 135 s->catalog_bitmap = g_try_new(uint32_t, s->catalog_size); 136 if (s->catalog_size && s->catalog_bitmap == NULL) { 137 error_setg(errp, "Could not allocate memory for catalog"); 138 return -ENOMEM; 139 } 140 141 ret = bdrv_pread(bs->file->bs, le32_to_cpu(bochs.header), s->catalog_bitmap, 142 s->catalog_size * 4); 143 if (ret < 0) { 144 goto fail; 145 } 146 147 for (i = 0; i < s->catalog_size; i++) 148 le32_to_cpus(&s->catalog_bitmap[i]); 149 150 s->data_offset = le32_to_cpu(bochs.header) + (s->catalog_size * 4); 151 152 s->bitmap_blocks = 1 + (le32_to_cpu(bochs.bitmap) - 1) / 512; 153 s->extent_blocks = 1 + (le32_to_cpu(bochs.extent) - 1) / 512; 154 155 s->extent_size = le32_to_cpu(bochs.extent); 156 if (s->extent_size < BDRV_SECTOR_SIZE) { 157 /* bximage actually never creates extents smaller than 4k */ 158 error_setg(errp, "Extent size must be at least 512"); 159 ret = -EINVAL; 160 goto fail; 161 } else if (!is_power_of_2(s->extent_size)) { 162 error_setg(errp, "Extent size %" PRIu32 " is not a power of two", 163 s->extent_size); 164 ret = -EINVAL; 165 goto fail; 166 } else if (s->extent_size > 0x800000) { 167 error_setg(errp, "Extent size %" PRIu32 " is too large", 168 s->extent_size); 169 ret = -EINVAL; 170 goto fail; 171 } 172 173 if (s->catalog_size < DIV_ROUND_UP(bs->total_sectors, 174 s->extent_size / BDRV_SECTOR_SIZE)) 175 { 176 error_setg(errp, "Catalog size is too small for this disk size"); 177 ret = -EINVAL; 178 goto fail; 179 } 180 181 qemu_co_mutex_init(&s->lock); 182 return 0; 183 184 fail: 185 g_free(s->catalog_bitmap); 186 return ret; 187 } 188 189 static int64_t seek_to_sector(BlockDriverState *bs, int64_t sector_num) 190 { 191 BDRVBochsState *s = bs->opaque; 192 uint64_t offset = sector_num * 512; 193 uint64_t extent_index, extent_offset, bitmap_offset; 194 char bitmap_entry; 195 int ret; 196 197 // seek to sector 198 extent_index = offset / s->extent_size; 199 extent_offset = (offset % s->extent_size) / 512; 200 201 if (s->catalog_bitmap[extent_index] == 0xffffffff) { 202 return 0; /* not allocated */ 203 } 204 205 bitmap_offset = s->data_offset + 206 (512 * (uint64_t) s->catalog_bitmap[extent_index] * 207 (s->extent_blocks + s->bitmap_blocks)); 208 209 /* read in bitmap for current extent */ 210 ret = bdrv_pread(bs->file->bs, bitmap_offset + (extent_offset / 8), 211 &bitmap_entry, 1); 212 if (ret < 0) { 213 return ret; 214 } 215 216 if (!((bitmap_entry >> (extent_offset % 8)) & 1)) { 217 return 0; /* not allocated */ 218 } 219 220 return bitmap_offset + (512 * (s->bitmap_blocks + extent_offset)); 221 } 222 223 static int bochs_read(BlockDriverState *bs, int64_t sector_num, 224 uint8_t *buf, int nb_sectors) 225 { 226 int ret; 227 228 while (nb_sectors > 0) { 229 int64_t block_offset = seek_to_sector(bs, sector_num); 230 if (block_offset < 0) { 231 return block_offset; 232 } else if (block_offset > 0) { 233 ret = bdrv_pread(bs->file->bs, block_offset, buf, 512); 234 if (ret < 0) { 235 return ret; 236 } 237 } else { 238 memset(buf, 0, 512); 239 } 240 nb_sectors--; 241 sector_num++; 242 buf += 512; 243 } 244 return 0; 245 } 246 247 static coroutine_fn int bochs_co_read(BlockDriverState *bs, int64_t sector_num, 248 uint8_t *buf, int nb_sectors) 249 { 250 int ret; 251 BDRVBochsState *s = bs->opaque; 252 qemu_co_mutex_lock(&s->lock); 253 ret = bochs_read(bs, sector_num, buf, nb_sectors); 254 qemu_co_mutex_unlock(&s->lock); 255 return ret; 256 } 257 258 static void bochs_close(BlockDriverState *bs) 259 { 260 BDRVBochsState *s = bs->opaque; 261 g_free(s->catalog_bitmap); 262 } 263 264 static BlockDriver bdrv_bochs = { 265 .format_name = "bochs", 266 .instance_size = sizeof(BDRVBochsState), 267 .bdrv_probe = bochs_probe, 268 .bdrv_open = bochs_open, 269 .bdrv_read = bochs_co_read, 270 .bdrv_close = bochs_close, 271 }; 272 273 static void bdrv_bochs_init(void) 274 { 275 bdrv_register(&bdrv_bochs); 276 } 277 278 block_init(bdrv_bochs_init); 279