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qemu-e2k/block/vpc.c

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/*
* Block driver for Connectix / Microsoft Virtual PC images
*
* Copyright (c) 2005 Alex Beregszaszi
* Copyright (c) 2009 Kevin Wolf <kwolf@suse.de>
*
* 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_SIZE 512
//#define CACHE
enum vhd_type {
VHD_FIXED = 2,
VHD_DYNAMIC = 3,
VHD_DIFFERENCING = 4,
};
// Seconds since Jan 1, 2000 0:00:00 (UTC)
#define VHD_TIMESTAMP_BASE 946684800
// always big-endian
struct vhd_footer {
char creator[8]; // "conectix"
uint32_t features;
uint32_t version;
// Offset of next header structure, 0xFFFFFFFF if none
uint64_t data_offset;
// Seconds since Jan 1, 2000 0:00:00 (UTC)
uint32_t timestamp;
char creator_app[4]; // "vpc "
uint16_t major;
uint16_t minor;
char creator_os[4]; // "Wi2k"
uint64_t orig_size;
uint64_t size;
uint16_t cyls;
uint8_t heads;
uint8_t secs_per_cyl;
uint32_t type;
// Checksum of the Hard Disk Footer ("one's complement of the sum of all
// the bytes in the footer without the checksum field")
uint32_t checksum;
// UUID used to identify a parent hard disk (backing file)
uint8_t uuid[16];
uint8_t in_saved_state;
};
struct vhd_dyndisk_header {
char magic[8]; // "cxsparse"
// Offset of next header structure, 0xFFFFFFFF if none
uint64_t data_offset;
// Offset of the Block Allocation Table (BAT)
uint64_t table_offset;
uint32_t version;
uint32_t max_table_entries; // 32bit/entry
// 2 MB by default, must be a power of two
uint32_t block_size;
uint32_t checksum;
uint8_t parent_uuid[16];
uint32_t parent_timestamp;
uint32_t reserved;
// Backing file name (in UTF-16)
uint8_t parent_name[512];
struct {
uint32_t platform;
uint32_t data_space;
uint32_t data_length;
uint32_t reserved;
uint64_t data_offset;
} parent_locator[8];
};
typedef struct BDRVVPCState {
BlockDriverState *hd;
uint8_t footer_buf[HEADER_SIZE];
uint64_t free_data_block_offset;
int max_table_entries;
uint32_t *pagetable;
uint64_t bat_offset;
uint64_t last_bitmap_offset;
uint32_t block_size;
uint32_t bitmap_size;
#ifdef CACHE
uint8_t *pageentry_u8;
uint32_t *pageentry_u32;
uint16_t *pageentry_u16;
uint64_t last_bitmap;
#endif
} BDRVVPCState;
static uint32_t vpc_checksum(uint8_t* buf, size_t size)
{
uint32_t res = 0;
int i;
for (i = 0; i < size; i++)
res += buf[i];
return ~res;
}
static int vpc_probe(const uint8_t *buf, int buf_size, const char *filename)
{
if (buf_size >= 8 && !strncmp((char *)buf, "conectix", 8))
return 100;
return 0;
}
static int vpc_open(BlockDriverState *bs, const char *filename, int flags)
{
BDRVVPCState *s = bs->opaque;
int ret, i;
struct vhd_footer* footer;
struct vhd_dyndisk_header* dyndisk_header;
uint8_t buf[HEADER_SIZE];
uint32_t checksum;
ret = bdrv_file_open(&s->hd, filename, flags);
if (ret < 0)
return ret;
if (bdrv_pread(s->hd, 0, s->footer_buf, HEADER_SIZE) != HEADER_SIZE)
goto fail;
footer = (struct vhd_footer*) s->footer_buf;
if (strncmp(footer->creator, "conectix", 8))
goto fail;
checksum = be32_to_cpu(footer->checksum);
footer->checksum = 0;
if (vpc_checksum(s->footer_buf, HEADER_SIZE) != checksum)
fprintf(stderr, "block-vpc: The header checksum of '%s' is "
"incorrect.\n", filename);
// The visible size of a image in Virtual PC depends on the geometry
// rather than on the size stored in the footer (the size in the footer
// is too large usually)
bs->total_sectors = (int64_t)
be16_to_cpu(footer->cyls) * footer->heads * footer->secs_per_cyl;
if (bdrv_pread(s->hd, be64_to_cpu(footer->data_offset), buf, HEADER_SIZE)
!= HEADER_SIZE)
goto fail;
dyndisk_header = (struct vhd_dyndisk_header*) buf;
if (strncmp(dyndisk_header->magic, "cxsparse", 8))
goto fail;
s->block_size = be32_to_cpu(dyndisk_header->block_size);
s->bitmap_size = ((s->block_size / (8 * 512)) + 511) & ~511;
s->max_table_entries = be32_to_cpu(dyndisk_header->max_table_entries);
s->pagetable = qemu_malloc(s->max_table_entries * 4);
s->bat_offset = be64_to_cpu(dyndisk_header->table_offset);
if (bdrv_pread(s->hd, s->bat_offset, s->pagetable,
s->max_table_entries * 4) != s->max_table_entries * 4)
goto fail;
s->free_data_block_offset =
(s->bat_offset + (s->max_table_entries * 4) + 511) & ~511;
for (i = 0; i < s->max_table_entries; i++) {
be32_to_cpus(&s->pagetable[i]);
if (s->pagetable[i] != 0xFFFFFFFF) {
int64_t next = (512 * (int64_t) s->pagetable[i]) +
s->bitmap_size + s->block_size;
if (next> s->free_data_block_offset)
s->free_data_block_offset = next;
}
}
s->last_bitmap_offset = (int64_t) -1;
#ifdef CACHE
s->pageentry_u8 = qemu_malloc(512);
s->pageentry_u32 = s->pageentry_u8;
s->pageentry_u16 = s->pageentry_u8;
s->last_pagetable = -1;
#endif
return 0;
fail:
bdrv_delete(s->hd);
return -1;
}
/*
* Returns the absolute byte offset of the given sector in the image file.
* If the sector is not allocated, -1 is returned instead.
*
* The parameter write must be 1 if the offset will be used for a write
* operation (the block bitmaps is updated then), 0 otherwise.
*/
static inline int64_t get_sector_offset(BlockDriverState *bs,
int64_t sector_num, int write)
{
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->block_size;
pageentry_index = (offset % s->block_size) / 512;
if (pagetable_index >= s->max_table_entries || s->pagetable[pagetable_index] == 0xffffffff)
return -1; // not allocated
bitmap_offset = 512 * (uint64_t) s->pagetable[pagetable_index];
block_offset = bitmap_offset + s->bitmap_size + (512 * pageentry_index);
// We must ensure that we don't write to any sectors which are marked as
// unused in the bitmap. We get away with setting all bits in the block
// bitmap each time we write to a new block. This might cause Virtual PC to
// miss sparse read optimization, but it's not a problem in terms of
// correctness.
if (write && (s->last_bitmap_offset != bitmap_offset)) {
uint8_t bitmap[s->bitmap_size];
s->last_bitmap_offset = bitmap_offset;
memset(bitmap, 0xff, s->bitmap_size);
bdrv_pwrite(s->hd, bitmap_offset, bitmap, s->bitmap_size);
}
// printf("sector: %" PRIx64 ", index: %x, offset: %x, bioff: %" PRIx64 ", bloff: %" PRIx64 "\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
return block_offset;
}
/*
* Writes the footer to the end of the image file. This is needed when the
* file grows as it overwrites the old footer
*
* Returns 0 on success and < 0 on error
*/
static int rewrite_footer(BlockDriverState* bs)
{
int ret;
BDRVVPCState *s = bs->opaque;
int64_t offset = s->free_data_block_offset;
ret = bdrv_pwrite(s->hd, offset, s->footer_buf, HEADER_SIZE);
if (ret < 0)
return ret;
return 0;
}
/*
* Allocates a new block. This involves writing a new footer and updating
* the Block Allocation Table to use the space at the old end of the image
* file (overwriting the old footer)
*
* Returns the sectors' offset in the image file on success and < 0 on error
*/
static int64_t alloc_block(BlockDriverState* bs, int64_t sector_num)
{
BDRVVPCState *s = bs->opaque;
int64_t bat_offset;
uint32_t index, bat_value;
int ret;
uint8_t bitmap[s->bitmap_size];
// Check if sector_num is valid
if ((sector_num < 0) || (sector_num > bs->total_sectors))
return -1;
// Write entry into in-memory BAT
index = (sector_num * 512) / s->block_size;
if (s->pagetable[index] != 0xFFFFFFFF)
return -1;
s->pagetable[index] = s->free_data_block_offset / 512;
// Initialize the block's bitmap
memset(bitmap, 0xff, s->bitmap_size);
bdrv_pwrite(s->hd, s->free_data_block_offset, bitmap, s->bitmap_size);
// Write new footer (the old one will be overwritten)
s->free_data_block_offset += s->block_size + s->bitmap_size;
ret = rewrite_footer(bs);
if (ret < 0)
goto fail;
// Write BAT entry to disk
bat_offset = s->bat_offset + (4 * index);
bat_value = be32_to_cpu(s->pagetable[index]);
ret = bdrv_pwrite(s->hd, bat_offset, &bat_value, 4);
if (ret < 0)
goto fail;
return get_sector_offset(bs, sector_num, 0);
fail:
s->free_data_block_offset -= (s->block_size + s->bitmap_size);
return -1;
}
static int vpc_read(BlockDriverState *bs, int64_t sector_num,
uint8_t *buf, int nb_sectors)
{
BDRVVPCState *s = bs->opaque;
int ret;
int64_t offset;
while (nb_sectors > 0) {
offset = get_sector_offset(bs, sector_num, 0);
if (offset == -1) {
memset(buf, 0, 512);
} else {
ret = bdrv_pread(s->hd, offset, buf, 512);
if (ret != 512)
return -1;
}
nb_sectors--;
sector_num++;
buf += 512;
}
return 0;
}
static int vpc_write(BlockDriverState *bs, int64_t sector_num,
const uint8_t *buf, int nb_sectors)
{
BDRVVPCState *s = bs->opaque;
int64_t offset;
int ret;
while (nb_sectors > 0) {
offset = get_sector_offset(bs, sector_num, 1);
if (offset == -1) {
offset = alloc_block(bs, sector_num);
if (offset < 0)
return -1;
}
ret = bdrv_pwrite(s->hd, offset, buf, 512);
if (ret != 512)
return -1;
nb_sectors--;
sector_num++;
buf += 512;
}
return 0;
}
/*
* Calculates the number of cylinders, heads and sectors per cylinder
* based on a given number of sectors. This is the algorithm described
* in the VHD specification.
*
* Note that the geometry doesn't always exactly match total_sectors but
* may round it down.
*
* Returns 0 on success, -EFBIG if the size is larger than 127 GB
*/
static int calculate_geometry(int64_t total_sectors, uint16_t* cyls,
uint8_t* heads, uint8_t* secs_per_cyl)
{
uint32_t cyls_times_heads;
if (total_sectors > 65535 * 16 * 255)
return -EFBIG;
if (total_sectors > 65535 * 16 * 63) {
*secs_per_cyl = 255;
*heads = 16;
cyls_times_heads = total_sectors / *secs_per_cyl;
} else {
*secs_per_cyl = 17;
cyls_times_heads = total_sectors / *secs_per_cyl;
*heads = (cyls_times_heads + 1023) / 1024;
if (*heads < 4)
*heads = 4;
if (cyls_times_heads >= (*heads * 1024) || *heads > 16) {
*secs_per_cyl = 31;
*heads = 16;
cyls_times_heads = total_sectors / *secs_per_cyl;
}
if (cyls_times_heads >= (*heads * 1024)) {
*secs_per_cyl = 63;
*heads = 16;
cyls_times_heads = total_sectors / *secs_per_cyl;
}
}
// Note: Rounding up deviates from the Virtual PC behaviour
// However, we need this to avoid truncating images in qemu-img convert
*cyls = (cyls_times_heads + *heads - 1) / *heads;
return 0;
}
static int vpc_create(const char *filename, QEMUOptionParameter *options)
{
uint8_t buf[1024];
struct vhd_footer* footer = (struct vhd_footer*) buf;
struct vhd_dyndisk_header* dyndisk_header =
(struct vhd_dyndisk_header*) buf;
int fd, i;
uint16_t cyls;
uint8_t heads;
uint8_t secs_per_cyl;
size_t block_size, num_bat_entries;
int64_t total_sectors = 0;
// Read out options
while (options && options->name) {
if (!strcmp(options->name, "size")) {
total_sectors = options->value.n / 512;
}
options++;
}
// Create the file
fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 0644);
if (fd < 0)
return -EIO;
// Calculate matching total_size and geometry
if (calculate_geometry(total_sectors, &cyls, &heads, &secs_per_cyl))
return -EFBIG;
total_sectors = (int64_t) cyls * heads * secs_per_cyl;
// Prepare the Hard Disk Footer
memset(buf, 0, 1024);
memcpy(footer->creator, "conectix", 8);
// TODO Check if "qemu" creator_app is ok for VPC
memcpy(footer->creator_app, "qemu", 4);
memcpy(footer->creator_os, "Wi2k", 4);
footer->features = be32_to_cpu(0x02);
footer->version = be32_to_cpu(0x00010000);
footer->data_offset = be64_to_cpu(HEADER_SIZE);
footer->timestamp = be32_to_cpu(time(NULL) - VHD_TIMESTAMP_BASE);
// Version of Virtual PC 2007
footer->major = be16_to_cpu(0x0005);
footer->minor =be16_to_cpu(0x0003);
footer->orig_size = be64_to_cpu(total_sectors * 512);
footer->size = be64_to_cpu(total_sectors * 512);
footer->cyls = be16_to_cpu(cyls);
footer->heads = heads;
footer->secs_per_cyl = secs_per_cyl;
footer->type = be32_to_cpu(VHD_DYNAMIC);
// TODO uuid is missing
footer->checksum = be32_to_cpu(vpc_checksum(buf, HEADER_SIZE));
// Write the footer (twice: at the beginning and at the end)
block_size = 0x200000;
num_bat_entries = (total_sectors + block_size / 512) / (block_size / 512);
if (write(fd, buf, HEADER_SIZE) != HEADER_SIZE)
return -EIO;
if (lseek(fd, 1536 + ((num_bat_entries * 4 + 511) & ~511), SEEK_SET) < 0)
return -EIO;
if (write(fd, buf, HEADER_SIZE) != HEADER_SIZE)
return -EIO;
// Write the initial BAT
if (lseek(fd, 3 * 512, SEEK_SET) < 0)
return -EIO;
memset(buf, 0xFF, 512);
for (i = 0; i < (num_bat_entries * 4 + 511) / 512; i++)
if (write(fd, buf, 512) != 512)
return -EIO;
// Prepare the Dynamic Disk Header
memset(buf, 0, 1024);
memcpy(dyndisk_header->magic, "cxsparse", 8);
dyndisk_header->data_offset = be64_to_cpu(0xFFFFFFFF);
dyndisk_header->table_offset = be64_to_cpu(3 * 512);
dyndisk_header->version = be32_to_cpu(0x00010000);
dyndisk_header->block_size = be32_to_cpu(block_size);
dyndisk_header->max_table_entries = be32_to_cpu(num_bat_entries);
dyndisk_header->checksum = be32_to_cpu(vpc_checksum(buf, 1024));
// Write the header
if (lseek(fd, 512, SEEK_SET) < 0)
return -EIO;
if (write(fd, buf, 1024) != 1024)
return -EIO;
close(fd);
return 0;
}
static void vpc_close(BlockDriverState *bs)
{
BDRVVPCState *s = bs->opaque;
qemu_free(s->pagetable);
#ifdef CACHE
qemu_free(s->pageentry_u8);
#endif
bdrv_delete(s->hd);
}
static QEMUOptionParameter vpc_create_options[] = {
{
.name = BLOCK_OPT_SIZE,
.type = OPT_SIZE,
.help = "Virtual disk size"
},
{ NULL }
};
static BlockDriver bdrv_vpc = {
.format_name = "vpc",
.instance_size = sizeof(BDRVVPCState),
.bdrv_probe = vpc_probe,
.bdrv_open = vpc_open,
.bdrv_read = vpc_read,
.bdrv_write = vpc_write,
.bdrv_close = vpc_close,
.bdrv_create = vpc_create,
.create_options = vpc_create_options,
};
static void bdrv_vpc_init(void)
{
bdrv_register(&bdrv_vpc);
}
block_init(bdrv_vpc_init);
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