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qemu/block/bochs.c

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/*
* 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/osdep.h"
#include "qapi/error.h"
#include "qemu-common.h"
#include "block/block_int.h"
#include "qemu/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 {
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 */
uint32_t catalog; /* num of entries */
uint32_t bitmap; /* bitmap size */
uint32_t extent; /* extent size */
union {
struct {
uint32_t reserved; /* for ??? */
uint64_t disk; /* disk size */
char padding[HEADER_SIZE - 64 - 20 - 12];
} QEMU_PACKED redolog;
struct {
uint64_t disk; /* disk size */
char padding[HEADER_SIZE - 64 - 20 - 8];
} QEMU_PACKED redolog_v1;
char padding[HEADER_SIZE - 64 - 20];
} extra;
} QEMU_PACKED;
typedef struct BDRVBochsState {
CoMutex lock;
uint32_t *catalog_bitmap;
uint32_t catalog_size;
uint32_t data_offset;
uint32_t bitmap_blocks;
uint32_t extent_blocks;
uint32_t 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, QDict *options, int flags,
Error **errp)
{
BDRVBochsState *s = bs->opaque;
uint32_t i;
struct bochs_header bochs;
int ret;
bs->read_only = 1; // no write support yet
ret = bdrv_pread(bs->file->bs, 0, &bochs, sizeof(bochs));
if (ret < 0) {
return ret;
}
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))) {
error_setg(errp, "Image not in Bochs format");
return -EINVAL;
}
if (le32_to_cpu(bochs.version) == HEADER_V1) {
bs->total_sectors = le64_to_cpu(bochs.extra.redolog_v1.disk) / 512;
} else {
bs->total_sectors = le64_to_cpu(bochs.extra.redolog.disk) / 512;
}
/* Limit to 1M entries to avoid unbounded allocation. This is what is
* needed for the largest image that bximage can create (~8 TB). */
s->catalog_size = le32_to_cpu(bochs.catalog);
if (s->catalog_size > 0x100000) {
error_setg(errp, "Catalog size is too large");
return -EFBIG;
}
s->catalog_bitmap = g_try_new(uint32_t, s->catalog_size);
if (s->catalog_size && s->catalog_bitmap == NULL) {
error_setg(errp, "Could not allocate memory for catalog");
return -ENOMEM;
}
ret = bdrv_pread(bs->file->bs, le32_to_cpu(bochs.header), s->catalog_bitmap,
s->catalog_size * 4);
if (ret < 0) {
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.bitmap) - 1) / 512;
s->extent_blocks = 1 + (le32_to_cpu(bochs.extent) - 1) / 512;
s->extent_size = le32_to_cpu(bochs.extent);
if (s->extent_size < BDRV_SECTOR_SIZE) {
/* bximage actually never creates extents smaller than 4k */
error_setg(errp, "Extent size must be at least 512");
ret = -EINVAL;
goto fail;
} else if (!is_power_of_2(s->extent_size)) {
error_setg(errp, "Extent size %" PRIu32 " is not a power of two",
s->extent_size);
ret = -EINVAL;
goto fail;
} else if (s->extent_size > 0x800000) {
error_setg(errp, "Extent size %" PRIu32 " is too large",
s->extent_size);
ret = -EINVAL;
goto fail;
}
if (s->catalog_size < DIV_ROUND_UP(bs->total_sectors,
s->extent_size / BDRV_SECTOR_SIZE))
{
error_setg(errp, "Catalog size is too small for this disk size");
ret = -EINVAL;
goto fail;
}
qemu_co_mutex_init(&s->lock);
return 0;
fail:
g_free(s->catalog_bitmap);
return ret;
}
static int64_t seek_to_sector(BlockDriverState *bs, int64_t sector_num)
{
BDRVBochsState *s = bs->opaque;
uint64_t offset = sector_num * 512;
uint64_t extent_index, extent_offset, bitmap_offset;
char bitmap_entry;
int ret;
// seek to sector
extent_index = offset / s->extent_size;
extent_offset = (offset % s->extent_size) / 512;
if (s->catalog_bitmap[extent_index] == 0xffffffff) {
return 0; /* not allocated */
}
bitmap_offset = s->data_offset +
(512 * (uint64_t) s->catalog_bitmap[extent_index] *
(s->extent_blocks + s->bitmap_blocks));
/* read in bitmap for current extent */
ret = bdrv_pread(bs->file->bs, bitmap_offset + (extent_offset / 8),
&bitmap_entry, 1);
if (ret < 0) {
return ret;
}
if (!((bitmap_entry >> (extent_offset % 8)) & 1)) {
return 0; /* not allocated */
}
return bitmap_offset + (512 * (s->bitmap_blocks + extent_offset));
}
static int bochs_read(BlockDriverState *bs, int64_t sector_num,
uint8_t *buf, int nb_sectors)
{
int ret;
while (nb_sectors > 0) {
int64_t block_offset = seek_to_sector(bs, sector_num);
if (block_offset < 0) {
return block_offset;
} else if (block_offset > 0) {
ret = bdrv_pread(bs->file->bs, block_offset, buf, 512);
if (ret < 0) {
return ret;
}
} else {
memset(buf, 0, 512);
}
nb_sectors--;
sector_num++;
buf += 512;
}
return 0;
}
static coroutine_fn int bochs_co_read(BlockDriverState *bs, int64_t sector_num,
uint8_t *buf, int nb_sectors)
{
int ret;
BDRVBochsState *s = bs->opaque;
qemu_co_mutex_lock(&s->lock);
ret = bochs_read(bs, sector_num, buf, nb_sectors);
qemu_co_mutex_unlock(&s->lock);
return ret;
}
static void bochs_close(BlockDriverState *bs)
{
BDRVBochsState *s = bs->opaque;
g_free(s->catalog_bitmap);
}
static BlockDriver bdrv_bochs = {
.format_name = "bochs",
.instance_size = sizeof(BDRVBochsState),
.bdrv_probe = bochs_probe,
.bdrv_open = bochs_open,
.bdrv_read = bochs_co_read,
.bdrv_close = bochs_close,
};
static void bdrv_bochs_init(void)
{
bdrv_register(&bdrv_bochs);
}
block_init(bdrv_bochs_init);
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