Archipelago » qemu

  - Virtual PC read-only disk image support (Alex Beregszaszi)

qemu-img$(EXESUF): qemu-img.c block.c block-cow.c block-qcow.c aes.c block-vmdk.c block-cloop.c block-dmg.c block-bochs.c block-vpc.c

VL_OBJS=vl.o osdep.o block.o readline.o monitor.o pci.o console.o

VL_OBJS+=block-cow.o block-qcow.o aes.o block-vmdk.o block-cloop.o block-dmg.o block-bochs.o block-vpc.o

/*

 * Block driver for Conectix/Microsoft Virtual PC images

 * 

 * 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 "vl.h"

#include "block_int.h"

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

#define HEADER_SIZE 512

//#define CACHE

// always big-endian

struct vpc_subheader {

    char magic[8]; // "conectix" / "cxsparse"

    union {

	struct {

	    uint32_t unk1[2];

	    uint32_t unk2; // always zero?

	    uint32_t subheader_offset;

	    uint32_t unk3; // some size?

	    char creator[4]; // "vpc "

	    uint16_t major;

	    uint16_t minor;

	    char guest[4]; // "Wi2k"

	    uint32_t unk4[7];

	    uint8_t vnet_id[16]; // virtual network id, purpose unknown

	    // next 16 longs are used, but dunno the purpose

	    // next 6 longs unknown, following 7 long maybe a serial

	    char padding[HEADER_SIZE - 84];

	} main;

	struct {

	    uint32_t unk1[2]; // all bits set

	    uint32_t unk2; // always zero?

	    uint32_t pagetable_offset;

	    uint32_t unk3;

	    uint32_t pagetable_entries; // 32bit/entry

	    uint32_t pageentry_size; // 512*8*512

	    uint32_t nb_sectors;

	    char padding[HEADER_SIZE - 40];

	} sparse;

	char padding[HEADER_SIZE - 8];

    } type;

};

typedef struct BDRVVPCState {

    int fd;

    int pagetable_entries;

    uint32_t *pagetable;

    uint32_t pageentry_size;

#ifdef CACHE

    uint8_t *pageentry_u8;

    uint32_t *pageentry_u32;

    uint16_t *pageentry_u16;

    uint64_t last_bitmap;

#endif

} BDRVVPCState;

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

{

    if (!strncmp(buf, "conectix", 8))

	return 100;

    return 0;

}

static int vpc_open(BlockDriverState *bs, const char *filename)

{

    BDRVVPCState *s = bs->opaque;

    int fd, i;

    struct vpc_subheader header;

    fd = open(filename, O_RDWR | O_BINARY | O_LARGEFILE);

    if (fd < 0) {

        fd = open(filename, O_RDONLY | O_BINARY | O_LARGEFILE);

        if (fd < 0)

            return -1;

    }

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

    s->fd = fd;

    if (read(fd, &header, HEADER_SIZE) != HEADER_SIZE)

        goto fail;

    if (strncmp(header.magic, "conectix", 8))

        goto fail;

    lseek(s->fd, be32_to_cpu(header.type.main.subheader_offset), SEEK_SET);

    if (read(fd, &header, HEADER_SIZE) != HEADER_SIZE)

        goto fail;

    if (strncmp(header.magic, "cxsparse", 8))

	goto fail;

    bs->total_sectors = ((uint64_t)be32_to_cpu(header.type.sparse.pagetable_entries) *

			be32_to_cpu(header.type.sparse.pageentry_size)) / 512;

    lseek(s->fd, be32_to_cpu(header.type.sparse.pagetable_offset), SEEK_SET);

    s->pagetable_entries = be32_to_cpu(header.type.sparse.pagetable_entries);

    s->pagetable = qemu_malloc(s->pagetable_entries * 4);

    if (!s->pagetable)

	goto fail;

    if (read(s->fd, s->pagetable, s->pagetable_entries * 4) !=

	s->pagetable_entries * 4)

	goto fail;

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

	be32_to_cpus(&s->pagetable[i]);

    s->pageentry_size = be32_to_cpu(header.type.sparse.pageentry_size);

#ifdef CACHE

    s->pageentry_u8 = qemu_malloc(512);

    if (!s->pageentry_u8)

	goto fail;

    s->pageentry_u32 = s->pageentry_u8;

    s->pageentry_u16 = s->pageentry_u8;

    s->last_pagetable = -1;

#endif

    return 0;

 fail:

    close(fd);

    return -1;

}

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

{

    BDRVVPCState *s = bs->opaque;

    uint64_t offset = sector_num * 512;

    uint64_t bitmap_offset, block_offset;

    uint32_t pagetable_index, pageentry_index;

    pagetable_index = offset / s->pageentry_size;

    pageentry_index = (offset % s->pageentry_size) / 512;

    if (pagetable_index > s->pagetable_entries || s->pagetable[pagetable_index] == 0xffffffff)

	return -1; // not allocated

    bitmap_offset = 512 * s->pagetable[pagetable_index];

    block_offset = bitmap_offset + 512 + (512 * pageentry_index);

//    printf("sector: %llx, index: %x, offset: %x, bioff: %llx, bloff: %llx\n",

//	sector_num, pagetable_index, pageentry_index,

//	bitmap_offset, block_offset);

// disabled by reason

#if 0

#ifdef CACHE

    if (bitmap_offset != s->last_bitmap)

    {

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

	s->last_bitmap = bitmap_offset;

	// Scary! Bitmap is stored as big endian 32bit entries,

	// while we used to look it up byte by byte

	read(s->fd, s->pageentry_u8, 512);

	for (i = 0; i < 128; i++)

	    be32_to_cpus(&s->pageentry_u32[i]);

    }

    if ((s->pageentry_u8[pageentry_index / 8] >> (pageentry_index % 8)) & 1)

	return -1;

#else

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

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

    if ((bitmap_entry >> (pageentry_index % 8)) & 1)

	return -1; // not allocated

#endif

#endif

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

    return 0;

}

static int vpc_read(BlockDriverState *bs, int64_t sector_num, 

                    uint8_t *buf, int nb_sectors)

{

    BDRVVPCState *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 vpc_close(BlockDriverState *bs)

{

    BDRVVPCState *s = bs->opaque;

    qemu_free(s->pagetable);

#ifdef CACHE

    qemu_free(s->pageentry_u8);

#endif

    close(s->fd);

}

BlockDriver bdrv_vpc = {

    "vpc",

    sizeof(BDRVVPCState),

    vpc_probe,

    vpc_open,

    vpc_read,

    NULL,

    vpc_close,

};

    bdrv_register(&bdrv_vpc);

extern BlockDriver bdrv_vpc;