Annotation of qemu/block-bochs.c, revision 1.1.1.2

1.1       root        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 "vl.h"
                     26: #include "block_int.h"
                     27: 
                     28: /**************************************************************/
                     29: 
                     30: #define HEADER_MAGIC "Bochs Virtual HD Image"
1.1.1.2 ! root       31: #define HEADER_VERSION 0x00020000
        !            32: #define HEADER_V1 0x00010000
1.1       root       33: #define HEADER_SIZE 512
                     34: 
                     35: #define REDOLOG_TYPE "Redolog"
                     36: #define GROWING_TYPE "Growing"
                     37: 
                     38: // not allocated: 0xffffffff
                     39: 
                     40: // always little-endian
1.1.1.2 ! root       41: struct bochs_header_v1 {
1.1       root       42:     char magic[32]; // "Bochs Virtual HD Image"
                     43:     char type[16]; // "Redolog"
                     44:     char subtype[16]; // "Undoable" / "Volatile" / "Growing"
                     45:     uint32_t version;
                     46:     uint32_t header; // size of header
                     47:     
                     48:     union {
                     49:        struct {
                     50:            uint32_t catalog; // num of entries
                     51:            uint32_t bitmap; // bitmap size
                     52:            uint32_t extent; // extent size
                     53:            uint64_t disk; // disk size
                     54:            char padding[HEADER_SIZE - 64 - 8 - 20];
                     55:        } redolog;
                     56:        char padding[HEADER_SIZE - 64 - 8];
                     57:     } extra;
                     58: };
                     59: 
1.1.1.2 ! root       60: // always little-endian
        !            61: struct bochs_header {
        !            62:     char magic[32]; // "Bochs Virtual HD Image"
        !            63:     char type[16]; // "Redolog"
        !            64:     char subtype[16]; // "Undoable" / "Volatile" / "Growing"
        !            65:     uint32_t version;
        !            66:     uint32_t header; // size of header
        !            67:     
        !            68:     union {
        !            69:        struct {
        !            70:            uint32_t catalog; // num of entries
        !            71:            uint32_t bitmap; // bitmap size
        !            72:            uint32_t extent; // extent size
        !            73:            uint32_t reserved; // for ???
        !            74:            uint64_t disk; // disk size
        !            75:            char padding[HEADER_SIZE - 64 - 8 - 24];
        !            76:        } redolog;
        !            77:        char padding[HEADER_SIZE - 64 - 8];
        !            78:     } extra;
        !            79: };
        !            80: 
1.1       root       81: typedef struct BDRVBochsState {
                     82:     int fd;
                     83: 
                     84:     uint32_t *catalog_bitmap;
                     85:     int catalog_size;
                     86:     
                     87:     int data_offset;
                     88:     
                     89:     int bitmap_blocks;
                     90:     int extent_blocks;
                     91:     int extent_size;
                     92: } BDRVBochsState;
                     93: 
                     94: static int bochs_probe(const uint8_t *buf, int buf_size, const char *filename)
                     95: {
                     96:     const struct bochs_header *bochs = (const void *)buf;
                     97:     
                     98:     if (buf_size < HEADER_SIZE)
                     99:        return 0;
                    100: 
                    101:     if (!strcmp(bochs->magic, HEADER_MAGIC) &&
                    102:        !strcmp(bochs->type, REDOLOG_TYPE) &&
                    103:        !strcmp(bochs->subtype, GROWING_TYPE) &&
1.1.1.2 ! root      104:        ((le32_to_cpu(bochs->version) == HEADER_VERSION) ||
        !           105:        (le32_to_cpu(bochs->version) == HEADER_V1)))
1.1       root      106:        return 100;
                    107: 
                    108:     return 0;
                    109: }
                    110: 
1.1.1.2 ! root      111: static int bochs_open(BlockDriverState *bs, const char *filename, int flags)
1.1       root      112: {
                    113:     BDRVBochsState *s = bs->opaque;
                    114:     int fd, i;
                    115:     struct bochs_header bochs;
1.1.1.2 ! root      116:     struct bochs_header_v1 header_v1;
1.1       root      117: 
1.1.1.2 ! root      118:     fd = open(filename, O_RDWR | O_BINARY);
1.1       root      119:     if (fd < 0) {
1.1.1.2 ! root      120:         fd = open(filename, O_RDONLY | O_BINARY);
1.1       root      121:         if (fd < 0)
                    122:             return -1;
                    123:     }
                    124:     
                    125:     bs->read_only = 1; // no write support yet
                    126:     
                    127:     s->fd = fd;
                    128: 
                    129:     if (read(fd, &bochs, sizeof(bochs)) != sizeof(bochs)) {
                    130:         goto fail;
                    131:     }
                    132: 
                    133:     if (strcmp(bochs.magic, HEADER_MAGIC) ||
                    134:         strcmp(bochs.type, REDOLOG_TYPE) ||
                    135:         strcmp(bochs.subtype, GROWING_TYPE) ||
1.1.1.2 ! root      136:        ((le32_to_cpu(bochs.version) != HEADER_VERSION) &&
        !           137:        (le32_to_cpu(bochs.version) != HEADER_V1))) {
1.1       root      138:         goto fail;
                    139:     }
                    140: 
1.1.1.2 ! root      141:     if (le32_to_cpu(bochs.version) == HEADER_V1) {
        !           142:       memcpy(&header_v1, &bochs, sizeof(bochs));
        !           143:       bs->total_sectors = le64_to_cpu(header_v1.extra.redolog.disk) / 512;
        !           144:     } else {
        !           145:       bs->total_sectors = le64_to_cpu(bochs.extra.redolog.disk) / 512;
        !           146:     }
1.1       root      147: 
                    148:     lseek(s->fd, le32_to_cpu(bochs.header), SEEK_SET);
                    149: 
                    150:     s->catalog_size = le32_to_cpu(bochs.extra.redolog.catalog);
                    151:     s->catalog_bitmap = qemu_malloc(s->catalog_size * 4);
                    152:     if (!s->catalog_bitmap)
                    153:        goto fail;
                    154:     if (read(s->fd, s->catalog_bitmap, s->catalog_size * 4) !=
                    155:        s->catalog_size * 4)
                    156:        goto fail;
                    157:     for (i = 0; i < s->catalog_size; i++)
                    158:        le32_to_cpus(&s->catalog_bitmap[i]);
                    159: 
                    160:     s->data_offset = le32_to_cpu(bochs.header) + (s->catalog_size * 4);
                    161: 
                    162:     s->bitmap_blocks = 1 + (le32_to_cpu(bochs.extra.redolog.bitmap) - 1) / 512;
                    163:     s->extent_blocks = 1 + (le32_to_cpu(bochs.extra.redolog.extent) - 1) / 512;
                    164:     
                    165:     s->extent_size = le32_to_cpu(bochs.extra.redolog.extent);
                    166: 
                    167:     return 0;
                    168:  fail:
                    169:     close(fd);
                    170:     return -1;
                    171: }
                    172: 
                    173: static inline int seek_to_sector(BlockDriverState *bs, int64_t sector_num)
                    174: {
                    175:     BDRVBochsState *s = bs->opaque;
                    176:     int64_t offset = sector_num * 512;
                    177:     int64_t extent_index, extent_offset, bitmap_offset, block_offset;
                    178:     char bitmap_entry;
                    179: 
                    180:     // seek to sector
                    181:     extent_index = offset / s->extent_size;
                    182:     extent_offset = (offset % s->extent_size) / 512;
                    183:     
                    184:     if (s->catalog_bitmap[extent_index] == 0xffffffff)
                    185:     {
                    186: //     fprintf(stderr, "page not allocated [%x - %x:%x]\n",
                    187: //         sector_num, extent_index, extent_offset);
                    188:        return -1; // not allocated
                    189:     }
                    190: 
                    191:     bitmap_offset = s->data_offset + (512 * s->catalog_bitmap[extent_index] *
                    192:        (s->extent_blocks + s->bitmap_blocks));
                    193:     block_offset = bitmap_offset + (512 * (s->bitmap_blocks + extent_offset));
                    194:     
                    195: //    fprintf(stderr, "sect: %x [ext i: %x o: %x] -> %x bitmap: %x block: %x\n",
                    196: //     sector_num, extent_index, extent_offset,
                    197: //     le32_to_cpu(s->catalog_bitmap[extent_index]),
                    198: //     bitmap_offset, block_offset);
                    199:     
                    200:     // read in bitmap for current extent
                    201:     lseek(s->fd, bitmap_offset + (extent_offset / 8), SEEK_SET);
                    202:     
                    203:     read(s->fd, &bitmap_entry, 1);
                    204:     
                    205:     if (!((bitmap_entry >> (extent_offset % 8)) & 1))
                    206:     {
                    207: //     fprintf(stderr, "sector (%x) in bitmap not allocated\n",
                    208: //         sector_num);
                    209:        return -1; // not allocated
                    210:     }
                    211: 
                    212:     lseek(s->fd, block_offset, SEEK_SET);
                    213:     
                    214:     return 0;
                    215: }
                    216: 
                    217: static int bochs_read(BlockDriverState *bs, int64_t sector_num, 
                    218:                     uint8_t *buf, int nb_sectors)
                    219: {
                    220:     BDRVBochsState *s = bs->opaque;
                    221:     int ret;
                    222: 
                    223:     while (nb_sectors > 0) {
                    224:        if (!seek_to_sector(bs, sector_num))
                    225:        {
                    226:            ret = read(s->fd, buf, 512);
                    227:            if (ret != 512)
                    228:                return -1;
                    229:        }
                    230:        else
                    231:             memset(buf, 0, 512);
                    232:         nb_sectors--;
                    233:         sector_num++;
                    234:         buf += 512;
                    235:     }
                    236:     return 0;
                    237: }
                    238: 
                    239: static void bochs_close(BlockDriverState *bs)
                    240: {
                    241:     BDRVBochsState *s = bs->opaque;
                    242:     qemu_free(s->catalog_bitmap);
                    243:     close(s->fd);
                    244: }
                    245: 
                    246: BlockDriver bdrv_bochs = {
                    247:     "bochs",
                    248:     sizeof(BDRVBochsState),
                    249:     bochs_probe,
                    250:     bochs_open,
                    251:     bochs_read,
                    252:     NULL,
                    253:     bochs_close,
                    254: };

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