Annotation of qemu/block-bochs.c, revision 1.1

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

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