Archipelago » qemu

/*

 * Block driver for the various disk image formats used by Bochs

 * Currently only for "growing" type in read-only mode

 *

 * Copyright (c) 2005 Alex Beregszaszi

 *

 * Permission is hereby granted, free of charge, to any person obtaining a copy

 * of this software and associated documentation files (the "Software"), to deal

 * in the Software without restriction, including without limitation the rights

 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

 * copies of the Software, and to permit persons to whom the Software is

 * furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice shall be included in

 * all copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL

 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN

 * THE SOFTWARE.

 */

#include "qemu-common.h"

#include "block_int.h"

#include "module.h"

/**************************************************************/

#define HEADER_MAGIC "Bochs Virtual HD Image"

#define HEADER_VERSION 0x00020000

#define HEADER_V1 0x00010000

#define HEADER_SIZE 512

#define REDOLOG_TYPE "Redolog"

#define GROWING_TYPE "Growing"

// not allocated: 0xffffffff

// always little-endian

struct bochs_header_v1 {

    char magic[32]; // "Bochs Virtual HD Image"

    char type[16]; // "Redolog"

    char subtype[16]; // "Undoable" / "Volatile" / "Growing"

    uint32_t version;

    uint32_t header; // size of header

    union {

        struct {

            uint32_t catalog; // num of entries

            uint32_t bitmap; // bitmap size

            uint32_t extent; // extent size

            uint64_t disk; // disk size

            char padding[HEADER_SIZE - 64 - 8 - 20];

        } redolog;

        char padding[HEADER_SIZE - 64 - 8];

    } extra;

};

// always little-endian

struct bochs_header {

    char magic[32]; // "Bochs Virtual HD Image"

    char type[16]; // "Redolog"

    char subtype[16]; // "Undoable" / "Volatile" / "Growing"

    uint32_t version;

    uint32_t header; // size of header

    union {

        struct {

            uint32_t catalog; // num of entries

            uint32_t bitmap; // bitmap size

            uint32_t extent; // extent size

            uint32_t reserved; // for ???

            uint64_t disk; // disk size

            char padding[HEADER_SIZE - 64 - 8 - 24];

        } redolog;

        char padding[HEADER_SIZE - 64 - 8];

    } extra;

};

typedef struct BDRVBochsState {

    int fd;

    uint32_t *catalog_bitmap;

    int catalog_size;

    int data_offset;

    int bitmap_blocks;

    int extent_blocks;

    int extent_size;

} BDRVBochsState;

static int bochs_probe(const uint8_t *buf, int buf_size, const char *filename)

{

    const struct bochs_header *bochs = (const void *)buf;

    if (buf_size < HEADER_SIZE)

        return 0;

    if (!strcmp(bochs->magic, HEADER_MAGIC) &&

        !strcmp(bochs->type, REDOLOG_TYPE) &&

        !strcmp(bochs->subtype, GROWING_TYPE) &&

        ((le32_to_cpu(bochs->version) == HEADER_VERSION) ||

        (le32_to_cpu(bochs->version) == HEADER_V1)))

        return 100;

    return 0;

}

static int bochs_open(BlockDriverState *bs, const char *filename, int flags)

{

    BDRVBochsState *s = bs->opaque;

    int fd, i;

    struct bochs_header bochs;

    struct bochs_header_v1 header_v1;

    fd = open(filename, O_RDWR | O_BINARY);

    if (fd < 0) {

        fd = open(filename, O_RDONLY | O_BINARY);

        if (fd < 0)

            return -1;

    }

    bs->read_only = 1; // no write support yet

    s->fd = fd;

    if (read(fd, &bochs, sizeof(bochs)) != sizeof(bochs)) {

        goto fail;

    }

    if (strcmp(bochs.magic, HEADER_MAGIC) ||

        strcmp(bochs.type, REDOLOG_TYPE) ||

        strcmp(bochs.subtype, GROWING_TYPE) ||

        ((le32_to_cpu(bochs.version) != HEADER_VERSION) &&

        (le32_to_cpu(bochs.version) != HEADER_V1))) {

        goto fail;

    }

    if (le32_to_cpu(bochs.version) == HEADER_V1) {

      memcpy(&header_v1, &bochs, sizeof(bochs));

      bs->total_sectors = le64_to_cpu(header_v1.extra.redolog.disk) / 512;

    } else {

      bs->total_sectors = le64_to_cpu(bochs.extra.redolog.disk) / 512;

    }

    lseek(s->fd, le32_to_cpu(bochs.header), SEEK_SET);

    s->catalog_size = le32_to_cpu(bochs.extra.redolog.catalog);

    s->catalog_bitmap = qemu_malloc(s->catalog_size * 4);

    if (read(s->fd, s->catalog_bitmap, s->catalog_size * 4) !=

        s->catalog_size * 4)

        goto fail;

    for (i = 0; i < s->catalog_size; i++)

        le32_to_cpus(&s->catalog_bitmap[i]);

    s->data_offset = le32_to_cpu(bochs.header) + (s->catalog_size * 4);

    s->bitmap_blocks = 1 + (le32_to_cpu(bochs.extra.redolog.bitmap) - 1) / 512;

    s->extent_blocks = 1 + (le32_to_cpu(bochs.extra.redolog.extent) - 1) / 512;

    s->extent_size = le32_to_cpu(bochs.extra.redolog.extent);

    return 0;

 fail:

    close(fd);

    return -1;

}

static inline int seek_to_sector(BlockDriverState *bs, int64_t sector_num)

{

    BDRVBochsState *s = bs->opaque;

    int64_t offset = sector_num * 512;

    int64_t extent_index, extent_offset, bitmap_offset, block_offset;

    char bitmap_entry;

    // seek to sector

    extent_index = offset / s->extent_size;

    extent_offset = (offset % s->extent_size) / 512;

    if (s->catalog_bitmap[extent_index] == 0xffffffff)

    {

//        fprintf(stderr, "page not allocated [%x - %x:%x]\n",

//            sector_num, extent_index, extent_offset);

        return -1; // not allocated

    }

    bitmap_offset = s->data_offset + (512 * s->catalog_bitmap[extent_index] *

        (s->extent_blocks + s->bitmap_blocks));

    block_offset = bitmap_offset + (512 * (s->bitmap_blocks + extent_offset));

//    fprintf(stderr, "sect: %x [ext i: %x o: %x] -> %x bitmap: %x block: %x\n",

//        sector_num, extent_index, extent_offset,

//        le32_to_cpu(s->catalog_bitmap[extent_index]),

//        bitmap_offset, block_offset);

    // read in bitmap for current extent

    lseek(s->fd, bitmap_offset + (extent_offset / 8), SEEK_SET);

    read(s->fd, &bitmap_entry, 1);

    if (!((bitmap_entry >> (extent_offset % 8)) & 1))

    {

//        fprintf(stderr, "sector (%x) in bitmap not allocated\n",

//            sector_num);

        return -1; // not allocated

    }

    lseek(s->fd, block_offset, SEEK_SET);

    return 0;

}

static int bochs_read(BlockDriverState *bs, int64_t sector_num,

                    uint8_t *buf, int nb_sectors)

{

    BDRVBochsState *s = bs->opaque;

    int ret;

    while (nb_sectors > 0) {

        if (!seek_to_sector(bs, sector_num))

        {

            ret = read(s->fd, buf, 512);

            if (ret != 512)

                return -1;

        }

        else

            memset(buf, 0, 512);

        nb_sectors--;

        sector_num++;

        buf += 512;

    }

    return 0;

}

static void bochs_close(BlockDriverState *bs)

{

    BDRVBochsState *s = bs->opaque;

    qemu_free(s->catalog_bitmap);

    close(s->fd);

}

static BlockDriver bdrv_bochs = {

    .format_name        = "bochs",

    .instance_size        = sizeof(BDRVBochsState),

    .bdrv_probe                = bochs_probe,

    .bdrv_open                = bochs_open,

    .bdrv_read                = bochs_read,

    .bdrv_close                = bochs_close,

};

static void bdrv_bochs_init(void)

{

    bdrv_register(&bdrv_bochs);

}

block_init(bdrv_bochs_init);