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qemu/block-qcow.c

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/*
* Block driver for the QCOW format
*
* Copyright (c) 2004-2006 Fabrice Bellard
*
* 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 <zlib.h>
#include "aes.h"
/**************************************************************/
/* QEMU COW block driver with compression and encryption support */
#define QCOW_MAGIC (('Q' << 24) | ('F' << 16) | ('I' << 8) | 0xfb)
#define QCOW_VERSION 1
#define QCOW_CRYPT_NONE 0
#define QCOW_CRYPT_AES 1
#define QCOW_OFLAG_COMPRESSED (1LL << 63)
typedef struct QCowHeader {
uint32_t magic;
uint32_t version;
uint64_t backing_file_offset;
uint32_t backing_file_size;
uint32_t mtime;
uint64_t size; /* in bytes */
uint8_t cluster_bits;
uint8_t l2_bits;
uint32_t crypt_method;
uint64_t l1_table_offset;
} QCowHeader;
#define L2_CACHE_SIZE 16
typedef struct BDRVQcowState {
BlockDriverState *hd;
int cluster_bits;
int cluster_size;
int cluster_sectors;
int l2_bits;
int l2_size;
int l1_size;
uint64_t cluster_offset_mask;
uint64_t l1_table_offset;
uint64_t *l1_table;
uint64_t *l2_cache;
uint64_t l2_cache_offsets[L2_CACHE_SIZE];
uint32_t l2_cache_counts[L2_CACHE_SIZE];
uint8_t *cluster_cache;
uint8_t *cluster_data;
uint64_t cluster_cache_offset;
uint32_t crypt_method; /* current crypt method, 0 if no key yet */
uint32_t crypt_method_header;
AES_KEY aes_encrypt_key;
AES_KEY aes_decrypt_key;
} BDRVQcowState;
static int decompress_cluster(BDRVQcowState *s, uint64_t cluster_offset);
static int qcow_probe(const uint8_t *buf, int buf_size, const char *filename)
{
const QCowHeader *cow_header = (const void *)buf;
if (buf_size >= sizeof(QCowHeader) &&
be32_to_cpu(cow_header->magic) == QCOW_MAGIC &&
be32_to_cpu(cow_header->version) == QCOW_VERSION)
return 100;
else
return 0;
}
static int qcow_open(BlockDriverState *bs, const char *filename, int flags)
{
BDRVQcowState *s = bs->opaque;
int len, i, shift, ret;
QCowHeader header;
ret = bdrv_file_open(&s->hd, filename, flags);
if (ret < 0)
return ret;
if (bdrv_pread(s->hd, 0, &header, sizeof(header)) != sizeof(header))
goto fail;
be32_to_cpus(&header.magic);
be32_to_cpus(&header.version);
be64_to_cpus(&header.backing_file_offset);
be32_to_cpus(&header.backing_file_size);
be32_to_cpus(&header.mtime);
be64_to_cpus(&header.size);
be32_to_cpus(&header.crypt_method);
be64_to_cpus(&header.l1_table_offset);
if (header.magic != QCOW_MAGIC || header.version != QCOW_VERSION)
goto fail;
if (header.size <= 1 || header.cluster_bits < 9)
goto fail;
if (header.crypt_method > QCOW_CRYPT_AES)
goto fail;
s->crypt_method_header = header.crypt_method;
if (s->crypt_method_header)
bs->encrypted = 1;
s->cluster_bits = header.cluster_bits;
s->cluster_size = 1 << s->cluster_bits;
s->cluster_sectors = 1 << (s->cluster_bits - 9);
s->l2_bits = header.l2_bits;
s->l2_size = 1 << s->l2_bits;
bs->total_sectors = header.size / 512;
s->cluster_offset_mask = (1LL << (63 - s->cluster_bits)) - 1;
/* read the level 1 table */
shift = s->cluster_bits + s->l2_bits;
s->l1_size = (header.size + (1LL << shift) - 1) >> shift;
s->l1_table_offset = header.l1_table_offset;
s->l1_table = qemu_malloc(s->l1_size * sizeof(uint64_t));
if (!s->l1_table)
goto fail;
if (bdrv_pread(s->hd, s->l1_table_offset, s->l1_table, s->l1_size * sizeof(uint64_t)) !=
s->l1_size * sizeof(uint64_t))
goto fail;
for(i = 0;i < s->l1_size; i++) {
be64_to_cpus(&s->l1_table[i]);
}
/* alloc L2 cache */
s->l2_cache = qemu_malloc(s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t));
if (!s->l2_cache)
goto fail;
s->cluster_cache = qemu_malloc(s->cluster_size);
if (!s->cluster_cache)
goto fail;
s->cluster_data = qemu_malloc(s->cluster_size);
if (!s->cluster_data)
goto fail;
s->cluster_cache_offset = -1;
/* read the backing file name */
if (header.backing_file_offset != 0) {
len = header.backing_file_size;
if (len > 1023)
len = 1023;
if (bdrv_pread(s->hd, header.backing_file_offset, bs->backing_file, len) != len)
goto fail;
bs->backing_file[len] = '\0';
}
return 0;
fail:
qemu_free(s->l1_table);
qemu_free(s->l2_cache);
qemu_free(s->cluster_cache);
qemu_free(s->cluster_data);
bdrv_delete(s->hd);
return -1;
}
static int qcow_set_key(BlockDriverState *bs, const char *key)
{
BDRVQcowState *s = bs->opaque;
uint8_t keybuf[16];
int len, i;
memset(keybuf, 0, 16);
len = strlen(key);
if (len > 16)
len = 16;
/* XXX: we could compress the chars to 7 bits to increase
entropy */
for(i = 0;i < len;i++) {
keybuf[i] = key[i];
}
s->crypt_method = s->crypt_method_header;
if (AES_set_encrypt_key(keybuf, 128, &s->aes_encrypt_key) != 0)
return -1;
if (AES_set_decrypt_key(keybuf, 128, &s->aes_decrypt_key) != 0)
return -1;
#if 0
/* test */
{
uint8_t in[16];
uint8_t out[16];
uint8_t tmp[16];
for(i=0;i<16;i++)
in[i] = i;
AES_encrypt(in, tmp, &s->aes_encrypt_key);
AES_decrypt(tmp, out, &s->aes_decrypt_key);
for(i = 0; i < 16; i++)
printf(" %02x", tmp[i]);
printf("\n");
for(i = 0; i < 16; i++)
printf(" %02x", out[i]);
printf("\n");
}
#endif
return 0;
}
/* The crypt function is compatible with the linux cryptoloop
algorithm for < 4 GB images. NOTE: out_buf == in_buf is
supported */
static void encrypt_sectors(BDRVQcowState *s, int64_t sector_num,
uint8_t *out_buf, const uint8_t *in_buf,
int nb_sectors, int enc,
const AES_KEY *key)
{
union {
uint64_t ll[2];
uint8_t b[16];
} ivec;
int i;
for(i = 0; i < nb_sectors; i++) {
ivec.ll[0] = cpu_to_le64(sector_num);
ivec.ll[1] = 0;
AES_cbc_encrypt(in_buf, out_buf, 512, key,
ivec.b, enc);
sector_num++;
in_buf += 512;
out_buf += 512;
}
}
/* 'allocate' is:
*
* 0 to not allocate.
*
* 1 to allocate a normal cluster (for sector indexes 'n_start' to
* 'n_end')
*
* 2 to allocate a compressed cluster of size
* 'compressed_size'. 'compressed_size' must be > 0 and <
* cluster_size
*
* return 0 if not allocated.
*/
static uint64_t get_cluster_offset(BlockDriverState *bs,
uint64_t offset, int allocate,
int compressed_size,
int n_start, int n_end)
{
BDRVQcowState *s = bs->opaque;
int min_index, i, j, l1_index, l2_index;
uint64_t l2_offset, *l2_table, cluster_offset, tmp;
uint32_t min_count;
int new_l2_table;
l1_index = offset >> (s->l2_bits + s->cluster_bits);
l2_offset = s->l1_table[l1_index];
new_l2_table = 0;
if (!l2_offset) {
if (!allocate)
return 0;
/* allocate a new l2 entry */
l2_offset = bdrv_getlength(s->hd);
/* round to cluster size */
l2_offset = (l2_offset + s->cluster_size - 1) & ~(s->cluster_size - 1);
/* update the L1 entry */
s->l1_table[l1_index] = l2_offset;
tmp = cpu_to_be64(l2_offset);
if (bdrv_pwrite(s->hd, s->l1_table_offset + l1_index * sizeof(tmp),
&tmp, sizeof(tmp)) != sizeof(tmp))
return 0;
new_l2_table = 1;
}
for(i = 0; i < L2_CACHE_SIZE; i++) {
if (l2_offset == s->l2_cache_offsets[i]) {
/* increment the hit count */
if (++s->l2_cache_counts[i] == 0xffffffff) {
for(j = 0; j < L2_CACHE_SIZE; j++) {
s->l2_cache_counts[j] >>= 1;
}
}
l2_table = s->l2_cache + (i << s->l2_bits);
goto found;
}
}
/* not found: load a new entry in the least used one */
min_index = 0;
min_count = 0xffffffff;
for(i = 0; i < L2_CACHE_SIZE; i++) {
if (s->l2_cache_counts[i] < min_count) {
min_count = s->l2_cache_counts[i];
min_index = i;
}
}
l2_table = s->l2_cache + (min_index << s->l2_bits);
if (new_l2_table) {
memset(l2_table, 0, s->l2_size * sizeof(uint64_t));
if (bdrv_pwrite(s->hd, l2_offset, l2_table, s->l2_size * sizeof(uint64_t)) !=
s->l2_size * sizeof(uint64_t))
return 0;
} else {
if (bdrv_pread(s->hd, l2_offset, l2_table, s->l2_size * sizeof(uint64_t)) !=
s->l2_size * sizeof(uint64_t))
return 0;
}
s->l2_cache_offsets[min_index] = l2_offset;
s->l2_cache_counts[min_index] = 1;
found:
l2_index = (offset >> s->cluster_bits) & (s->l2_size - 1);
cluster_offset = be64_to_cpu(l2_table[l2_index]);
if (!cluster_offset ||
((cluster_offset & QCOW_OFLAG_COMPRESSED) && allocate == 1)) {
if (!allocate)
return 0;
/* allocate a new cluster */
if ((cluster_offset & QCOW_OFLAG_COMPRESSED) &&
(n_end - n_start) < s->cluster_sectors) {
/* if the cluster is already compressed, we must
decompress it in the case it is not completely
overwritten */
if (decompress_cluster(s, cluster_offset) < 0)
return 0;
cluster_offset = bdrv_getlength(s->hd);
cluster_offset = (cluster_offset + s->cluster_size - 1) &
~(s->cluster_size - 1);
/* write the cluster content */
if (bdrv_pwrite(s->hd, cluster_offset, s->cluster_cache, s->cluster_size) !=
s->cluster_size)
return -1;
} else {
cluster_offset = bdrv_getlength(s->hd);
/* round to cluster size */
cluster_offset = (cluster_offset + s->cluster_size - 1) &
~(s->cluster_size - 1);
bdrv_truncate(s->hd, cluster_offset + s->cluster_size);
/* if encrypted, we must initialize the cluster
content which won't be written */
if (s->crypt_method &&
(n_end - n_start) < s->cluster_sectors) {
uint64_t start_sect;
start_sect = (offset & ~(s->cluster_size - 1)) >> 9;
memset(s->cluster_data + 512, 0x00, 512);
for(i = 0; i < s->cluster_sectors; i++) {
if (i < n_start || i >= n_end) {
encrypt_sectors(s, start_sect + i,
s->cluster_data,
s->cluster_data + 512, 1, 1,
&s->aes_encrypt_key);
if (bdrv_pwrite(s->hd, cluster_offset + i * 512,
s->cluster_data, 512) != 512)
return -1;
}
}
}
}
/* update L2 table */
tmp = cpu_to_be64(cluster_offset);
l2_table[l2_index] = tmp;
if (bdrv_pwrite(s->hd,
l2_offset + l2_index * sizeof(tmp), &tmp, sizeof(tmp)) != sizeof(tmp))
return 0;
}
return cluster_offset;
}
static int qcow_is_allocated(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, int *pnum)
{
BDRVQcowState *s = bs->opaque;
int index_in_cluster, n;
uint64_t cluster_offset;
cluster_offset = get_cluster_offset(bs, sector_num << 9, 0, 0, 0, 0);
index_in_cluster = sector_num & (s->cluster_sectors - 1);
n = s->cluster_sectors - index_in_cluster;
if (n > nb_sectors)
n = nb_sectors;
*pnum = n;
return (cluster_offset != 0);
}
static int decompress_buffer(uint8_t *out_buf, int out_buf_size,
const uint8_t *buf, int buf_size)
{
z_stream strm1, *strm = &strm1;
int ret, out_len;
memset(strm, 0, sizeof(*strm));
strm->next_in = (uint8_t *)buf;
strm->avail_in = buf_size;
strm->next_out = out_buf;
strm->avail_out = out_buf_size;
ret = inflateInit2(strm, -12);
if (ret != Z_OK)
return -1;
ret = inflate(strm, Z_FINISH);
out_len = strm->next_out - out_buf;
if ((ret != Z_STREAM_END && ret != Z_BUF_ERROR) ||
out_len != out_buf_size) {
inflateEnd(strm);
return -1;
}
inflateEnd(strm);
return 0;
}
static int decompress_cluster(BDRVQcowState *s, uint64_t cluster_offset)
{
int ret, csize;
uint64_t coffset;
coffset = cluster_offset & s->cluster_offset_mask;
if (s->cluster_cache_offset != coffset) {
csize = cluster_offset >> (63 - s->cluster_bits);
csize &= (s->cluster_size - 1);
ret = bdrv_pread(s->hd, coffset, s->cluster_data, csize);
if (ret != csize)
return -1;
if (decompress_buffer(s->cluster_cache, s->cluster_size,
s->cluster_data, csize) < 0) {
return -1;
}
s->cluster_cache_offset = coffset;
}
return 0;
}
#if 0
static int qcow_read(BlockDriverState *bs, int64_t sector_num,
uint8_t *buf, int nb_sectors)
{
BDRVQcowState *s = bs->opaque;
int ret, index_in_cluster, n;
uint64_t cluster_offset;
while (nb_sectors > 0) {
cluster_offset = get_cluster_offset(bs, sector_num << 9, 0, 0, 0, 0);
index_in_cluster = sector_num & (s->cluster_sectors - 1);
n = s->cluster_sectors - index_in_cluster;
if (n > nb_sectors)
n = nb_sectors;
if (!cluster_offset) {
if (bs->backing_hd) {
/* read from the base image */
ret = bdrv_read(bs->backing_hd, sector_num, buf, n);
if (ret < 0)
return -1;
} else {
memset(buf, 0, 512 * n);
}
} else if (cluster_offset & QCOW_OFLAG_COMPRESSED) {
if (decompress_cluster(s, cluster_offset) < 0)
return -1;
memcpy(buf, s->cluster_cache + index_in_cluster * 512, 512 * n);
} else {
ret = bdrv_pread(s->hd, cluster_offset + index_in_cluster * 512, buf, n * 512);
if (ret != n * 512)
return -1;
if (s->crypt_method) {
encrypt_sectors(s, sector_num, buf, buf, n, 0,
&s->aes_decrypt_key);
}
}
nb_sectors -= n;
sector_num += n;
buf += n * 512;
}
return 0;
}
#endif
static int qcow_write(BlockDriverState *bs, int64_t sector_num,
const uint8_t *buf, int nb_sectors)
{
BDRVQcowState *s = bs->opaque;
int ret, index_in_cluster, n;
uint64_t cluster_offset;
while (nb_sectors > 0) {
index_in_cluster = sector_num & (s->cluster_sectors - 1);
n = s->cluster_sectors - index_in_cluster;
if (n > nb_sectors)
n = nb_sectors;
cluster_offset = get_cluster_offset(bs, sector_num << 9, 1, 0,
index_in_cluster,
index_in_cluster + n);
if (!cluster_offset)
return -1;
if (s->crypt_method) {
encrypt_sectors(s, sector_num, s->cluster_data, buf, n, 1,
&s->aes_encrypt_key);
ret = bdrv_pwrite(s->hd, cluster_offset + index_in_cluster * 512,
s->cluster_data, n * 512);
} else {
ret = bdrv_pwrite(s->hd, cluster_offset + index_in_cluster * 512, buf, n * 512);
}
if (ret != n * 512)
return -1;
nb_sectors -= n;
sector_num += n;
buf += n * 512;
}
s->cluster_cache_offset = -1; /* disable compressed cache */
return 0;
}
typedef struct QCowAIOCB {
BlockDriverAIOCB common;
int64_t sector_num;
uint8_t *buf;
int nb_sectors;
int n;
uint64_t cluster_offset;
uint8_t *cluster_data;
BlockDriverAIOCB *hd_aiocb;
} QCowAIOCB;
static void qcow_aio_read_cb(void *opaque, int ret)
{
QCowAIOCB *acb = opaque;
BlockDriverState *bs = acb->common.bs;
BDRVQcowState *s = bs->opaque;
int index_in_cluster;
acb->hd_aiocb = NULL;
if (ret < 0) {
fail:
acb->common.cb(acb->common.opaque, ret);
qemu_aio_release(acb);
return;
}
redo:
/* post process the read buffer */
if (!acb->cluster_offset) {
/* nothing to do */
} else if (acb->cluster_offset & QCOW_OFLAG_COMPRESSED) {
/* nothing to do */
} else {
if (s->crypt_method) {
encrypt_sectors(s, acb->sector_num, acb->buf, acb->buf,
acb->n, 0,
&s->aes_decrypt_key);
}
}
acb->nb_sectors -= acb->n;
acb->sector_num += acb->n;
acb->buf += acb->n * 512;
if (acb->nb_sectors == 0) {
/* request completed */
acb->common.cb(acb->common.opaque, 0);
qemu_aio_release(acb);
return;
}
/* prepare next AIO request */
acb->cluster_offset = get_cluster_offset(bs, acb->sector_num << 9,
0, 0, 0, 0);
index_in_cluster = acb->sector_num & (s->cluster_sectors - 1);
acb->n = s->cluster_sectors - index_in_cluster;
if (acb->n > acb->nb_sectors)
acb->n = acb->nb_sectors;
if (!acb->cluster_offset) {
if (bs->backing_hd) {
/* read from the base image */
acb->hd_aiocb = bdrv_aio_read(bs->backing_hd,
acb->sector_num, acb->buf, acb->n, qcow_aio_read_cb, acb);
if (acb->hd_aiocb == NULL)
goto fail;
} else {
/* Note: in this case, no need to wait */
memset(acb->buf, 0, 512 * acb->n);
goto redo;
}
} else if (acb->cluster_offset & QCOW_OFLAG_COMPRESSED) {
/* add AIO support for compressed blocks ? */
if (decompress_cluster(s, acb->cluster_offset) < 0)
goto fail;
memcpy(acb->buf,
s->cluster_cache + index_in_cluster * 512, 512 * acb->n);
goto redo;
} else {
if ((acb->cluster_offset & 511) != 0) {
ret = -EIO;
goto fail;
}
acb->hd_aiocb = bdrv_aio_read(s->hd,
(acb->cluster_offset >> 9) + index_in_cluster,
acb->buf, acb->n, qcow_aio_read_cb, acb);
if (acb->hd_aiocb == NULL)
goto fail;
}
}
static BlockDriverAIOCB *qcow_aio_read(BlockDriverState *bs,
int64_t sector_num, uint8_t *buf, int nb_sectors,
BlockDriverCompletionFunc *cb, void *opaque)
{
QCowAIOCB *acb;
acb = qemu_aio_get(bs, cb, opaque);
if (!acb)
return NULL;
acb->hd_aiocb = NULL;
acb->sector_num = sector_num;
acb->buf = buf;
acb->nb_sectors = nb_sectors;
acb->n = 0;
acb->cluster_offset = 0;
qcow_aio_read_cb(acb, 0);
return &acb->common;
}
static void qcow_aio_write_cb(void *opaque, int ret)
{
QCowAIOCB *acb = opaque;
BlockDriverState *bs = acb->common.bs;
BDRVQcowState *s = bs->opaque;
int index_in_cluster;
uint64_t cluster_offset;
const uint8_t *src_buf;
acb->hd_aiocb = NULL;
if (ret < 0) {
fail:
acb->common.cb(acb->common.opaque, ret);
qemu_aio_release(acb);
return;
}
acb->nb_sectors -= acb->n;
acb->sector_num += acb->n;
acb->buf += acb->n * 512;
if (acb->nb_sectors == 0) {
/* request completed */
acb->common.cb(acb->common.opaque, 0);
qemu_aio_release(acb);
return;
}
index_in_cluster = acb->sector_num & (s->cluster_sectors - 1);
acb->n = s->cluster_sectors - index_in_cluster;
if (acb->n > acb->nb_sectors)
acb->n = acb->nb_sectors;
cluster_offset = get_cluster_offset(bs, acb->sector_num << 9, 1, 0,
index_in_cluster,
index_in_cluster + acb->n);
if (!cluster_offset || (cluster_offset & 511) != 0) {
ret = -EIO;
goto fail;
}
if (s->crypt_method) {
if (!acb->cluster_data) {
acb->cluster_data = qemu_mallocz(s->cluster_size);
if (!acb->cluster_data) {
ret = -ENOMEM;
goto fail;
}
}
encrypt_sectors(s, acb->sector_num, acb->cluster_data, acb->buf,
acb->n, 1, &s->aes_encrypt_key);
src_buf = acb->cluster_data;
} else {
src_buf = acb->buf;
}
acb->hd_aiocb = bdrv_aio_write(s->hd,
(cluster_offset >> 9) + index_in_cluster,
src_buf, acb->n,
qcow_aio_write_cb, acb);
if (acb->hd_aiocb == NULL)
goto fail;
}
static BlockDriverAIOCB *qcow_aio_write(BlockDriverState *bs,
int64_t sector_num, const uint8_t *buf, int nb_sectors,
BlockDriverCompletionFunc *cb, void *opaque)
{
BDRVQcowState *s = bs->opaque;
QCowAIOCB *acb;
s->cluster_cache_offset = -1; /* disable compressed cache */
acb = qemu_aio_get(bs, cb, opaque);
if (!acb)
return NULL;
acb->hd_aiocb = NULL;
acb->sector_num = sector_num;
acb->buf = (uint8_t *)buf;
acb->nb_sectors = nb_sectors;
acb->n = 0;
qcow_aio_write_cb(acb, 0);
return &acb->common;
}
static void qcow_aio_cancel(BlockDriverAIOCB *blockacb)
{
QCowAIOCB *acb = (QCowAIOCB *)blockacb;
if (acb->hd_aiocb)
bdrv_aio_cancel(acb->hd_aiocb);
qemu_aio_release(acb);
}
static void qcow_close(BlockDriverState *bs)
{
BDRVQcowState *s = bs->opaque;
qemu_free(s->l1_table);
qemu_free(s->l2_cache);
qemu_free(s->cluster_cache);
qemu_free(s->cluster_data);
bdrv_delete(s->hd);
}
static int qcow_create(const char *filename, int64_t total_size,
const char *backing_file, int flags)
{
int fd, header_size, backing_filename_len, l1_size, i, shift;
QCowHeader header;
uint64_t tmp;
fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 0644);
if (fd < 0)
return -1;
memset(&header, 0, sizeof(header));
header.magic = cpu_to_be32(QCOW_MAGIC);
header.version = cpu_to_be32(QCOW_VERSION);
header.size = cpu_to_be64(total_size * 512);
header_size = sizeof(header);
backing_filename_len = 0;
if (backing_file) {
if (strcmp(backing_file, "fat:")) {
header.backing_file_offset = cpu_to_be64(header_size);
backing_filename_len = strlen(backing_file);
header.backing_file_size = cpu_to_be32(backing_filename_len);
header_size += backing_filename_len;
} else {
/* special backing file for vvfat */
backing_file = NULL;
}
header.cluster_bits = 9; /* 512 byte cluster to avoid copying
unmodifyed sectors */
header.l2_bits = 12; /* 32 KB L2 tables */
} else {
header.cluster_bits = 12; /* 4 KB clusters */
header.l2_bits = 9; /* 4 KB L2 tables */
}
header_size = (header_size + 7) & ~7;
shift = header.cluster_bits + header.l2_bits;
l1_size = ((total_size * 512) + (1LL << shift) - 1) >> shift;
header.l1_table_offset = cpu_to_be64(header_size);
if (flags & BLOCK_FLAG_ENCRYPT) {
header.crypt_method = cpu_to_be32(QCOW_CRYPT_AES);
} else {
header.crypt_method = cpu_to_be32(QCOW_CRYPT_NONE);
}
/* write all the data */
write(fd, &header, sizeof(header));
if (backing_file) {
write(fd, backing_file, backing_filename_len);
}
lseek(fd, header_size, SEEK_SET);
tmp = 0;
for(i = 0;i < l1_size; i++) {
write(fd, &tmp, sizeof(tmp));
}
close(fd);
return 0;
}
static int qcow_make_empty(BlockDriverState *bs)
{
BDRVQcowState *s = bs->opaque;
uint32_t l1_length = s->l1_size * sizeof(uint64_t);
int ret;
memset(s->l1_table, 0, l1_length);
if (bdrv_pwrite(s->hd, s->l1_table_offset, s->l1_table, l1_length) < 0)
return -1;
ret = bdrv_truncate(s->hd, s->l1_table_offset + l1_length);
if (ret < 0)
return ret;
memset(s->l2_cache, 0, s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t));
memset(s->l2_cache_offsets, 0, L2_CACHE_SIZE * sizeof(uint64_t));
memset(s->l2_cache_counts, 0, L2_CACHE_SIZE * sizeof(uint32_t));
return 0;
}
/* XXX: put compressed sectors first, then all the cluster aligned
tables to avoid losing bytes in alignment */
static int qcow_write_compressed(BlockDriverState *bs, int64_t sector_num,
const uint8_t *buf, int nb_sectors)
{
BDRVQcowState *s = bs->opaque;
z_stream strm;
int ret, out_len;
uint8_t *out_buf;
uint64_t cluster_offset;
if (nb_sectors != s->cluster_sectors)
return -EINVAL;
out_buf = qemu_malloc(s->cluster_size + (s->cluster_size / 1000) + 128);
if (!out_buf)
return -1;
/* best compression, small window, no zlib header */
memset(&strm, 0, sizeof(strm));
ret = deflateInit2(&strm, Z_DEFAULT_COMPRESSION,
Z_DEFLATED, -12,
9, Z_DEFAULT_STRATEGY);
if (ret != 0) {
qemu_free(out_buf);
return -1;
}
strm.avail_in = s->cluster_size;
strm.next_in = (uint8_t *)buf;
strm.avail_out = s->cluster_size;
strm.next_out = out_buf;
ret = deflate(&strm, Z_FINISH);
if (ret != Z_STREAM_END && ret != Z_OK) {
qemu_free(out_buf);
deflateEnd(&strm);
return -1;
}
out_len = strm.next_out - out_buf;
deflateEnd(&strm);
if (ret != Z_STREAM_END || out_len >= s->cluster_size) {
/* could not compress: write normal cluster */
qcow_write(bs, sector_num, buf, s->cluster_sectors);
} else {
cluster_offset = get_cluster_offset(bs, sector_num << 9, 2,
out_len, 0, 0);
cluster_offset &= s->cluster_offset_mask;
if (bdrv_pwrite(s->hd, cluster_offset, out_buf, out_len) != out_len) {
qemu_free(out_buf);
return -1;
}
}
qemu_free(out_buf);
return 0;
}
static void qcow_flush(BlockDriverState *bs)
{
BDRVQcowState *s = bs->opaque;
bdrv_flush(s->hd);
}
static int qcow_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
{
BDRVQcowState *s = bs->opaque;
bdi->cluster_size = s->cluster_size;
return 0;
}
BlockDriver bdrv_qcow = {
"qcow",
sizeof(BDRVQcowState),
qcow_probe,
qcow_open,
NULL,
NULL,
qcow_close,
qcow_create,
qcow_flush,
qcow_is_allocated,
qcow_set_key,
qcow_make_empty,
.bdrv_aio_read = qcow_aio_read,
.bdrv_aio_write = qcow_aio_write,
.bdrv_aio_cancel = qcow_aio_cancel,
.aiocb_size = sizeof(QCowAIOCB),
.bdrv_write_compressed = qcow_write_compressed,
.bdrv_get_info = qcow_get_info,
};
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