qemu/block/bochs.c
Kevin Wolf 66f82ceed6 block: Open the underlying image file in generic code
Format drivers shouldn't need to bother with things like file names, but rather
just get an open BlockDriverState for the underlying protocol. This patch
introduces this behaviour for bdrv_open implementation. For protocols which
need to access the filename to open their file/device/connection/... a new
callback bdrv_file_open is introduced which doesn't get an underlying file
opened.

For now, also some of the more obscure formats use bdrv_file_open because they
open() the file themselves instead of using the block.c functions. They need to
be fixed in later patches.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-05-03 10:07:30 +02:00

266 lines
7.3 KiB
C

/*
* 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_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;
}
if (lseek(s->fd, le32_to_cpu(bochs.header), SEEK_SET) == (off_t)-1) {
goto fail;
}
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
if (lseek(s->fd, bitmap_offset + (extent_offset / 8), SEEK_SET) ==
(off_t)-1) {
return -1;
}
if (read(s->fd, &bitmap_entry, 1) != 1)
return -1;
if (!((bitmap_entry >> (extent_offset % 8)) & 1))
{
// fprintf(stderr, "sector (%x) in bitmap not allocated\n",
// sector_num);
return -1; // not allocated
}
if (lseek(s->fd, block_offset, SEEK_SET) == (off_t)-1) {
return -1;
}
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_file_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);