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/*
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 * Block driver for Conectix/Microsoft Virtual PC images
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 * 
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 * Copyright (c) 2005 Alex Beregszaszi
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 * 
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 * Permission is hereby granted, free of charge, to any person obtaining a copy
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 * of this software and associated documentation files (the "Software"), to deal
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 * in the Software without restriction, including without limitation the rights
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 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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 * copies of the Software, and to permit persons to whom the Software is
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 * furnished to do so, subject to the following conditions:
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 *
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 * The above copyright notice and this permission notice shall be included in
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 * all copies or substantial portions of the Software.
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 *
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 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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 * THE SOFTWARE.
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 */
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#include "vl.h"
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#include "block_int.h"
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/**************************************************************/
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#define HEADER_SIZE 512
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//#define CACHE
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// always big-endian
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struct vpc_subheader {
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    char magic[8]; // "conectix" / "cxsparse"
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    union {
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        struct {
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            uint32_t unk1[2];
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            uint32_t unk2; // always zero?
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            uint32_t subheader_offset;
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            uint32_t unk3; // some size?
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            char creator[4]; // "vpc "
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            uint16_t major;
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            uint16_t minor;
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            char guest[4]; // "Wi2k"
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            uint32_t unk4[7];
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            uint8_t vnet_id[16]; // virtual network id, purpose unknown
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            // next 16 longs are used, but dunno the purpose
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            // next 6 longs unknown, following 7 long maybe a serial
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            char padding[HEADER_SIZE - 84];
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        } main;
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        struct {
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            uint32_t unk1[2]; // all bits set
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            uint32_t unk2; // always zero?
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            uint32_t pagetable_offset;
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            uint32_t unk3;
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            uint32_t pagetable_entries; // 32bit/entry
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            uint32_t pageentry_size; // 512*8*512
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            uint32_t nb_sectors;
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            char padding[HEADER_SIZE - 40];
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        } sparse;
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        char padding[HEADER_SIZE - 8];
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    } type;
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};
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typedef struct BDRVVPCState {
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    int fd;
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    int pagetable_entries;
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    uint32_t *pagetable;
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    uint32_t pageentry_size;
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#ifdef CACHE
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    uint8_t *pageentry_u8;
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    uint32_t *pageentry_u32;
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    uint16_t *pageentry_u16;
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    uint64_t last_bitmap;
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#endif
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} BDRVVPCState;
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static int vpc_probe(const uint8_t *buf, int buf_size, const char *filename)
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{
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    if (buf_size >= 8 && !strncmp(buf, "conectix", 8))
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        return 100;
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    return 0;
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}
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static int vpc_open(BlockDriverState *bs, const char *filename)
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{
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    BDRVVPCState *s = bs->opaque;
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    int fd, i;
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    struct vpc_subheader header;
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    fd = open(filename, O_RDWR | O_BINARY | O_LARGEFILE);
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    if (fd < 0) {
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        fd = open(filename, O_RDONLY | O_BINARY | O_LARGEFILE);
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        if (fd < 0)
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            return -1;
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    }
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    bs->read_only = 1; // no write support yet
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    s->fd = fd;
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    if (read(fd, &header, HEADER_SIZE) != HEADER_SIZE)
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        goto fail;
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    if (strncmp(header.magic, "conectix", 8))
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        goto fail;
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    lseek(s->fd, be32_to_cpu(header.type.main.subheader_offset), SEEK_SET);
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    if (read(fd, &header, HEADER_SIZE) != HEADER_SIZE)
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        goto fail;
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    if (strncmp(header.magic, "cxsparse", 8))
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        goto fail;
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    bs->total_sectors = ((uint64_t)be32_to_cpu(header.type.sparse.pagetable_entries) *
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                        be32_to_cpu(header.type.sparse.pageentry_size)) / 512;
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    lseek(s->fd, be32_to_cpu(header.type.sparse.pagetable_offset), SEEK_SET);
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    s->pagetable_entries = be32_to_cpu(header.type.sparse.pagetable_entries);
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    s->pagetable = qemu_malloc(s->pagetable_entries * 4);
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    if (!s->pagetable)
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        goto fail;
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    if (read(s->fd, s->pagetable, s->pagetable_entries * 4) !=
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        s->pagetable_entries * 4)
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        goto fail;
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    for (i = 0; i < s->pagetable_entries; i++)
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        be32_to_cpus(&s->pagetable[i]);
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    s->pageentry_size = be32_to_cpu(header.type.sparse.pageentry_size);
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#ifdef CACHE
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    s->pageentry_u8 = qemu_malloc(512);
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    if (!s->pageentry_u8)
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        goto fail;
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    s->pageentry_u32 = s->pageentry_u8;
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    s->pageentry_u16 = s->pageentry_u8;
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    s->last_pagetable = -1;
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#endif
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    return 0;
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 fail:
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    close(fd);
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    return -1;
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}
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static inline int seek_to_sector(BlockDriverState *bs, int64_t sector_num)
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{
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    BDRVVPCState *s = bs->opaque;
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    uint64_t offset = sector_num * 512;
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    uint64_t bitmap_offset, block_offset;
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    uint32_t pagetable_index, pageentry_index;
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    pagetable_index = offset / s->pageentry_size;
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    pageentry_index = (offset % s->pageentry_size) / 512;
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    if (pagetable_index > s->pagetable_entries || s->pagetable[pagetable_index] == 0xffffffff)
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        return -1; // not allocated
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    bitmap_offset = 512 * s->pagetable[pagetable_index];
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    block_offset = bitmap_offset + 512 + (512 * pageentry_index);
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//    printf("sector: %" PRIx64 ", index: %x, offset: %x, bioff: %" PRIx64 ", bloff: %" PRIx64 "\n",
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//        sector_num, pagetable_index, pageentry_index,
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//        bitmap_offset, block_offset);
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// disabled by reason
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#if 0
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#ifdef CACHE
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    if (bitmap_offset != s->last_bitmap)
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    {
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        lseek(s->fd, bitmap_offset, SEEK_SET);
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        s->last_bitmap = bitmap_offset;
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        // Scary! Bitmap is stored as big endian 32bit entries,
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        // while we used to look it up byte by byte
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        read(s->fd, s->pageentry_u8, 512);
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        for (i = 0; i < 128; i++)
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            be32_to_cpus(&s->pageentry_u32[i]);
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    }
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    if ((s->pageentry_u8[pageentry_index / 8] >> (pageentry_index % 8)) & 1)
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        return -1;
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#else
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    lseek(s->fd, bitmap_offset + (pageentry_index / 8), SEEK_SET);
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    read(s->fd, &bitmap_entry, 1);
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    if ((bitmap_entry >> (pageentry_index % 8)) & 1)
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        return -1; // not allocated
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#endif
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#endif
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    lseek(s->fd, block_offset, SEEK_SET);
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    return 0;
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}
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static int vpc_read(BlockDriverState *bs, int64_t sector_num, 
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                    uint8_t *buf, int nb_sectors)
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{
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    BDRVVPCState *s = bs->opaque;
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    int ret;
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    while (nb_sectors > 0) {
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        if (!seek_to_sector(bs, sector_num))
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        {
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            ret = read(s->fd, buf, 512);
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            if (ret != 512)
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                return -1;
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        }
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        else
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            memset(buf, 0, 512);
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        nb_sectors--;
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        sector_num++;
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        buf += 512;
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    }
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    return 0;
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}
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static void vpc_close(BlockDriverState *bs)
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{
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    BDRVVPCState *s = bs->opaque;
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    qemu_free(s->pagetable);
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#ifdef CACHE
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    qemu_free(s->pageentry_u8);
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#endif
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    close(s->fd);
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}
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BlockDriver bdrv_vpc = {
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    "vpc",
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    sizeof(BDRVVPCState),
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    vpc_probe,
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    vpc_open,
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    vpc_read,
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    NULL,
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    vpc_close,
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};