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_int.h" 27 #include "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_v1 { 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 union { 50 struct { 51 uint32_t catalog; // num of entries 52 uint32_t bitmap; // bitmap size 53 uint32_t extent; // extent size 54 uint64_t disk; // disk size 55 char padding[HEADER_SIZE - 64 - 8 - 20]; 56 } redolog; 57 char padding[HEADER_SIZE - 64 - 8]; 58 } extra; 59 }; 60 61 // always little-endian 62 struct bochs_header { 63 char magic[32]; // "Bochs Virtual HD Image" 64 char type[16]; // "Redolog" 65 char subtype[16]; // "Undoable" / "Volatile" / "Growing" 66 uint32_t version; 67 uint32_t header; // size of header 68 69 union { 70 struct { 71 uint32_t catalog; // num of entries 72 uint32_t bitmap; // bitmap size 73 uint32_t extent; // extent size 74 uint32_t reserved; // for ??? 75 uint64_t disk; // disk size 76 char padding[HEADER_SIZE - 64 - 8 - 24]; 77 } redolog; 78 char padding[HEADER_SIZE - 64 - 8]; 79 } extra; 80 }; 81 82 typedef struct BDRVBochsState { 83 uint32_t *catalog_bitmap; 84 int catalog_size; 85 86 int data_offset; 87 88 int bitmap_blocks; 89 int extent_blocks; 90 int extent_size; 91 } BDRVBochsState; 92 93 static int bochs_probe(const uint8_t *buf, int buf_size, const char *filename) 94 { 95 const struct bochs_header *bochs = (const void *)buf; 96 97 if (buf_size < HEADER_SIZE) 98 return 0; 99 100 if (!strcmp(bochs->magic, HEADER_MAGIC) && 101 !strcmp(bochs->type, REDOLOG_TYPE) && 102 !strcmp(bochs->subtype, GROWING_TYPE) && 103 ((le32_to_cpu(bochs->version) == HEADER_VERSION) || 104 (le32_to_cpu(bochs->version) == HEADER_V1))) 105 return 100; 106 107 return 0; 108 } 109 110 static int bochs_open(BlockDriverState *bs, int flags) 111 { 112 BDRVBochsState *s = bs->opaque; 113 int i; 114 struct bochs_header bochs; 115 struct bochs_header_v1 header_v1; 116 117 bs->read_only = 1; // no write support yet 118 119 if (bdrv_pread(bs->file, 0, &bochs, sizeof(bochs)) != sizeof(bochs)) { 120 goto fail; 121 } 122 123 if (strcmp(bochs.magic, HEADER_MAGIC) || 124 strcmp(bochs.type, REDOLOG_TYPE) || 125 strcmp(bochs.subtype, GROWING_TYPE) || 126 ((le32_to_cpu(bochs.version) != HEADER_VERSION) && 127 (le32_to_cpu(bochs.version) != HEADER_V1))) { 128 goto fail; 129 } 130 131 if (le32_to_cpu(bochs.version) == HEADER_V1) { 132 memcpy(&header_v1, &bochs, sizeof(bochs)); 133 bs->total_sectors = le64_to_cpu(header_v1.extra.redolog.disk) / 512; 134 } else { 135 bs->total_sectors = le64_to_cpu(bochs.extra.redolog.disk) / 512; 136 } 137 138 s->catalog_size = le32_to_cpu(bochs.extra.redolog.catalog); 139 s->catalog_bitmap = qemu_malloc(s->catalog_size * 4); 140 if (bdrv_pread(bs->file, le32_to_cpu(bochs.header), s->catalog_bitmap, 141 s->catalog_size * 4) != s->catalog_size * 4) 142 goto fail; 143 for (i = 0; i < s->catalog_size; i++) 144 le32_to_cpus(&s->catalog_bitmap[i]); 145 146 s->data_offset = le32_to_cpu(bochs.header) + (s->catalog_size * 4); 147 148 s->bitmap_blocks = 1 + (le32_to_cpu(bochs.extra.redolog.bitmap) - 1) / 512; 149 s->extent_blocks = 1 + (le32_to_cpu(bochs.extra.redolog.extent) - 1) / 512; 150 151 s->extent_size = le32_to_cpu(bochs.extra.redolog.extent); 152 153 return 0; 154 fail: 155 return -1; 156 } 157 158 static int64_t seek_to_sector(BlockDriverState *bs, int64_t sector_num) 159 { 160 BDRVBochsState *s = bs->opaque; 161 int64_t offset = sector_num * 512; 162 int64_t extent_index, extent_offset, bitmap_offset; 163 char bitmap_entry; 164 165 // seek to sector 166 extent_index = offset / s->extent_size; 167 extent_offset = (offset % s->extent_size) / 512; 168 169 if (s->catalog_bitmap[extent_index] == 0xffffffff) { 170 return -1; /* not allocated */ 171 } 172 173 bitmap_offset = s->data_offset + (512 * s->catalog_bitmap[extent_index] * 174 (s->extent_blocks + s->bitmap_blocks)); 175 176 /* read in bitmap for current extent */ 177 if (bdrv_pread(bs->file, bitmap_offset + (extent_offset / 8), 178 &bitmap_entry, 1) != 1) { 179 return -1; 180 } 181 182 if (!((bitmap_entry >> (extent_offset % 8)) & 1)) { 183 return -1; /* not allocated */ 184 } 185 186 return bitmap_offset + (512 * (s->bitmap_blocks + extent_offset)); 187 } 188 189 static int bochs_read(BlockDriverState *bs, int64_t sector_num, 190 uint8_t *buf, int nb_sectors) 191 { 192 int ret; 193 194 while (nb_sectors > 0) { 195 int64_t block_offset = seek_to_sector(bs, sector_num); 196 if (block_offset >= 0) { 197 ret = bdrv_pread(bs->file, block_offset, buf, 512); 198 if (ret != 512) { 199 return -1; 200 } 201 } else 202 memset(buf, 0, 512); 203 nb_sectors--; 204 sector_num++; 205 buf += 512; 206 } 207 return 0; 208 } 209 210 static void bochs_close(BlockDriverState *bs) 211 { 212 BDRVBochsState *s = bs->opaque; 213 qemu_free(s->catalog_bitmap); 214 } 215 216 static BlockDriver bdrv_bochs = { 217 .format_name = "bochs", 218 .instance_size = sizeof(BDRVBochsState), 219 .bdrv_probe = bochs_probe, 220 .bdrv_open = bochs_open, 221 .bdrv_read = bochs_read, 222 .bdrv_close = bochs_close, 223 }; 224 225 static void bdrv_bochs_init(void) 226 { 227 bdrv_register(&bdrv_bochs); 228 } 229 230 block_init(bdrv_bochs_init); 231