root / block-bochs.c @ 1247c5f7
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/*
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* Block driver for the various disk image formats used by Bochs
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* Currently only for "growing" type in read-only mode
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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_MAGIC "Bochs Virtual HD Image" |
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#define HEADER_VERSION 0x00010000 |
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#define HEADER_SIZE 512 |
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#define REDOLOG_TYPE "Redolog" |
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#define GROWING_TYPE "Growing" |
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// not allocated: 0xffffffff
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// always little-endian
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struct bochs_header {
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char magic[32]; // "Bochs Virtual HD Image" |
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char type[16]; // "Redolog" |
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char subtype[16]; // "Undoable" / "Volatile" / "Growing" |
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uint32_t version; |
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uint32_t header; // size of header
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union {
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struct {
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uint32_t catalog; // num of entries
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uint32_t bitmap; // bitmap size
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uint32_t extent; // extent size
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uint64_t disk; // disk size
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char padding[HEADER_SIZE - 64 - 8 - 20]; |
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} redolog; |
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char padding[HEADER_SIZE - 64 - 8]; |
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} extra; |
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}; |
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typedef struct BDRVBochsState { |
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int fd;
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uint32_t *catalog_bitmap; |
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int catalog_size;
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int data_offset;
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int bitmap_blocks;
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int extent_blocks;
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int extent_size;
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} BDRVBochsState; |
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static int bochs_probe(const uint8_t *buf, int buf_size, const char *filename) |
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{ |
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const struct bochs_header *bochs = (const void *)buf; |
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if (buf_size < HEADER_SIZE)
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return 0; |
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if (!strcmp(bochs->magic, HEADER_MAGIC) &&
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!strcmp(bochs->type, REDOLOG_TYPE) && |
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!strcmp(bochs->subtype, GROWING_TYPE) && |
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(le32_to_cpu(bochs->version) == HEADER_VERSION)) |
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return 100; |
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return 0; |
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} |
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static int bochs_open(BlockDriverState *bs, const char *filename) |
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{ |
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BDRVBochsState *s = bs->opaque; |
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int fd, i;
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struct bochs_header bochs;
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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, &bochs, sizeof(bochs)) != sizeof(bochs)) { |
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goto fail;
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} |
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if (strcmp(bochs.magic, HEADER_MAGIC) ||
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strcmp(bochs.type, REDOLOG_TYPE) || |
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strcmp(bochs.subtype, GROWING_TYPE) || |
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(le32_to_cpu(bochs.version) != HEADER_VERSION)) { |
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goto fail;
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} |
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bs->total_sectors = le64_to_cpu(bochs.extra.redolog.disk) / 512;
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lseek(s->fd, le32_to_cpu(bochs.header), SEEK_SET); |
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s->catalog_size = le32_to_cpu(bochs.extra.redolog.catalog); |
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s->catalog_bitmap = qemu_malloc(s->catalog_size * 4);
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if (!s->catalog_bitmap)
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goto fail;
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if (read(s->fd, s->catalog_bitmap, s->catalog_size * 4) != |
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s->catalog_size * 4)
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goto fail;
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for (i = 0; i < s->catalog_size; i++) |
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le32_to_cpus(&s->catalog_bitmap[i]); |
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s->data_offset = le32_to_cpu(bochs.header) + (s->catalog_size * 4);
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s->bitmap_blocks = 1 + (le32_to_cpu(bochs.extra.redolog.bitmap) - 1) / 512; |
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s->extent_blocks = 1 + (le32_to_cpu(bochs.extra.redolog.extent) - 1) / 512; |
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s->extent_size = le32_to_cpu(bochs.extra.redolog.extent); |
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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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BDRVBochsState *s = bs->opaque; |
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int64_t offset = sector_num * 512;
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int64_t extent_index, extent_offset, bitmap_offset, block_offset; |
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char bitmap_entry;
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// seek to sector
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extent_index = offset / s->extent_size; |
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extent_offset = (offset % s->extent_size) / 512;
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if (s->catalog_bitmap[extent_index] == 0xffffffff) |
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{ |
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// fprintf(stderr, "page not allocated [%x - %x:%x]\n",
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// sector_num, extent_index, extent_offset);
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return -1; // not allocated |
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} |
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bitmap_offset = s->data_offset + (512 * s->catalog_bitmap[extent_index] *
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(s->extent_blocks + s->bitmap_blocks)); |
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block_offset = bitmap_offset + (512 * (s->bitmap_blocks + extent_offset));
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// fprintf(stderr, "sect: %x [ext i: %x o: %x] -> %x bitmap: %x block: %x\n",
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// sector_num, extent_index, extent_offset,
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// le32_to_cpu(s->catalog_bitmap[extent_index]),
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// bitmap_offset, block_offset);
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// read in bitmap for current extent
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lseek(s->fd, bitmap_offset + (extent_offset / 8), SEEK_SET);
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read(s->fd, &bitmap_entry, 1);
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if (!((bitmap_entry >> (extent_offset % 8)) & 1)) |
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{ |
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// fprintf(stderr, "sector (%x) in bitmap not allocated\n",
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// sector_num);
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return -1; // not allocated |
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} |
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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 bochs_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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BDRVBochsState *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 bochs_close(BlockDriverState *bs) |
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{ |
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BDRVBochsState *s = bs->opaque; |
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qemu_free(s->catalog_bitmap); |
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close(s->fd); |
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} |
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BlockDriver bdrv_bochs = { |
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"bochs",
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sizeof(BDRVBochsState),
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bochs_probe, |
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bochs_open, |
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bochs_read, |
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NULL,
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bochs_close, |
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}; |