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-common.h" 26 #include "block/block_int.h" 27 #include "qemu/module.h" 28 29 /**************************************************************/ 30 31 #define HEADER_MAGIC "Bochs Virtual HD Image" 32 #define HEADER_VERSION 0x00020000 33 #define HEADER_V1 0x00010000 34 #define HEADER_SIZE 512 35 36 #define REDOLOG_TYPE "Redolog" 37 #define GROWING_TYPE "Growing" 38 39 // not allocated: 0xffffffff 40 41 // always little-endian 42 struct bochs_header { 43 char magic[32]; /* "Bochs Virtual HD Image" */ 44 char type[16]; /* "Redolog" */ 45 char subtype[16]; /* "Undoable" / "Volatile" / "Growing" */ 46 uint32_t version; 47 uint32_t header; /* size of header */ 48 49 uint32_t catalog; /* num of entries */ 50 uint32_t bitmap; /* bitmap size */ 51 uint32_t extent; /* extent size */ 52 53 union { 54 struct { 55 uint32_t reserved; /* for ??? */ 56 uint64_t disk; /* disk size */ 57 char padding[HEADER_SIZE - 64 - 20 - 12]; 58 } QEMU_PACKED redolog; 59 struct { 60 uint64_t disk; /* disk size */ 61 char padding[HEADER_SIZE - 64 - 20 - 8]; 62 } QEMU_PACKED redolog_v1; 63 char padding[HEADER_SIZE - 64 - 20]; 64 } extra; 65 } QEMU_PACKED; 66 67 typedef struct BDRVBochsState { 68 CoMutex lock; 69 uint32_t *catalog_bitmap; 70 int catalog_size; 71 72 int data_offset; 73 74 int bitmap_blocks; 75 int extent_blocks; 76 int extent_size; 77 } BDRVBochsState; 78 79 static int bochs_probe(const uint8_t *buf, int buf_size, const char *filename) 80 { 81 const struct bochs_header *bochs = (const void *)buf; 82 83 if (buf_size < HEADER_SIZE) 84 return 0; 85 86 if (!strcmp(bochs->magic, HEADER_MAGIC) && 87 !strcmp(bochs->type, REDOLOG_TYPE) && 88 !strcmp(bochs->subtype, GROWING_TYPE) && 89 ((le32_to_cpu(bochs->version) == HEADER_VERSION) || 90 (le32_to_cpu(bochs->version) == HEADER_V1))) 91 return 100; 92 93 return 0; 94 } 95 96 static int bochs_open(BlockDriverState *bs, QDict *options, int flags, 97 Error **errp) 98 { 99 BDRVBochsState *s = bs->opaque; 100 int i; 101 struct bochs_header bochs; 102 int ret; 103 104 bs->read_only = 1; // no write support yet 105 106 ret = bdrv_pread(bs->file, 0, &bochs, sizeof(bochs)); 107 if (ret < 0) { 108 return ret; 109 } 110 111 if (strcmp(bochs.magic, HEADER_MAGIC) || 112 strcmp(bochs.type, REDOLOG_TYPE) || 113 strcmp(bochs.subtype, GROWING_TYPE) || 114 ((le32_to_cpu(bochs.version) != HEADER_VERSION) && 115 (le32_to_cpu(bochs.version) != HEADER_V1))) { 116 error_setg(errp, "Image not in Bochs format"); 117 return -EINVAL; 118 } 119 120 if (le32_to_cpu(bochs.version) == HEADER_V1) { 121 bs->total_sectors = le64_to_cpu(bochs.extra.redolog_v1.disk) / 512; 122 } else { 123 bs->total_sectors = le64_to_cpu(bochs.extra.redolog.disk) / 512; 124 } 125 126 s->catalog_size = le32_to_cpu(bochs.catalog); 127 s->catalog_bitmap = g_malloc(s->catalog_size * 4); 128 129 ret = bdrv_pread(bs->file, le32_to_cpu(bochs.header), s->catalog_bitmap, 130 s->catalog_size * 4); 131 if (ret < 0) { 132 goto fail; 133 } 134 135 for (i = 0; i < s->catalog_size; i++) 136 le32_to_cpus(&s->catalog_bitmap[i]); 137 138 s->data_offset = le32_to_cpu(bochs.header) + (s->catalog_size * 4); 139 140 s->bitmap_blocks = 1 + (le32_to_cpu(bochs.bitmap) - 1) / 512; 141 s->extent_blocks = 1 + (le32_to_cpu(bochs.extent) - 1) / 512; 142 143 s->extent_size = le32_to_cpu(bochs.extent); 144 145 qemu_co_mutex_init(&s->lock); 146 return 0; 147 148 fail: 149 g_free(s->catalog_bitmap); 150 return ret; 151 } 152 153 static int64_t seek_to_sector(BlockDriverState *bs, int64_t sector_num) 154 { 155 BDRVBochsState *s = bs->opaque; 156 int64_t offset = sector_num * 512; 157 int64_t extent_index, extent_offset, bitmap_offset; 158 char bitmap_entry; 159 160 // seek to sector 161 extent_index = offset / s->extent_size; 162 extent_offset = (offset % s->extent_size) / 512; 163 164 if (s->catalog_bitmap[extent_index] == 0xffffffff) { 165 return -1; /* not allocated */ 166 } 167 168 bitmap_offset = s->data_offset + (512 * s->catalog_bitmap[extent_index] * 169 (s->extent_blocks + s->bitmap_blocks)); 170 171 /* read in bitmap for current extent */ 172 if (bdrv_pread(bs->file, bitmap_offset + (extent_offset / 8), 173 &bitmap_entry, 1) != 1) { 174 return -1; 175 } 176 177 if (!((bitmap_entry >> (extent_offset % 8)) & 1)) { 178 return -1; /* not allocated */ 179 } 180 181 return bitmap_offset + (512 * (s->bitmap_blocks + extent_offset)); 182 } 183 184 static int bochs_read(BlockDriverState *bs, int64_t sector_num, 185 uint8_t *buf, int nb_sectors) 186 { 187 int ret; 188 189 while (nb_sectors > 0) { 190 int64_t block_offset = seek_to_sector(bs, sector_num); 191 if (block_offset >= 0) { 192 ret = bdrv_pread(bs->file, block_offset, buf, 512); 193 if (ret != 512) { 194 return -1; 195 } 196 } else 197 memset(buf, 0, 512); 198 nb_sectors--; 199 sector_num++; 200 buf += 512; 201 } 202 return 0; 203 } 204 205 static coroutine_fn int bochs_co_read(BlockDriverState *bs, int64_t sector_num, 206 uint8_t *buf, int nb_sectors) 207 { 208 int ret; 209 BDRVBochsState *s = bs->opaque; 210 qemu_co_mutex_lock(&s->lock); 211 ret = bochs_read(bs, sector_num, buf, nb_sectors); 212 qemu_co_mutex_unlock(&s->lock); 213 return ret; 214 } 215 216 static void bochs_close(BlockDriverState *bs) 217 { 218 BDRVBochsState *s = bs->opaque; 219 g_free(s->catalog_bitmap); 220 } 221 222 static BlockDriver bdrv_bochs = { 223 .format_name = "bochs", 224 .instance_size = sizeof(BDRVBochsState), 225 .bdrv_probe = bochs_probe, 226 .bdrv_open = bochs_open, 227 .bdrv_read = bochs_co_read, 228 .bdrv_close = bochs_close, 229 }; 230 231 static void bdrv_bochs_init(void) 232 { 233 bdrv_register(&bdrv_bochs); 234 } 235 236 block_init(bdrv_bochs_init); 237