new disk image layer
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@1037 c046a42c-6fe2-441c-8c8c-71466251a162
diff --git a/block-qcow.c b/block-qcow.c
new file mode 100644
index 0000000..ed6359f
--- /dev/null
+++ b/block-qcow.c
@@ -0,0 +1,677 @@
+/*
+ * Block driver for the QCOW format
+ *
+ * Copyright (c) 2004 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 "vl.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 {
+ int fd;
+ 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 (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)
+{
+ BDRVQcowState *s = bs->opaque;
+ int fd, len, i, shift;
+ QCowHeader header;
+
+ fd = open(filename, O_RDWR | O_BINARY | O_LARGEFILE);
+ if (fd < 0) {
+ fd = open(filename, O_RDONLY | O_BINARY | O_LARGEFILE);
+ if (fd < 0)
+ return -1;
+ }
+ s->fd = fd;
+ if (read(fd, &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;
+ lseek64(fd, s->l1_table_offset, SEEK_SET);
+ if (read(fd, 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;
+ lseek64(fd, header.backing_file_offset, SEEK_SET);
+ if (read(fd, 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);
+ close(fd);
+ 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 = lseek64(s->fd, 0, SEEK_END);
+ /* 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);
+ lseek64(s->fd, s->l1_table_offset + l1_index * sizeof(tmp), SEEK_SET);
+ if (write(s->fd, &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);
+ lseek(s->fd, l2_offset, SEEK_SET);
+ if (new_l2_table) {
+ memset(l2_table, 0, s->l2_size * sizeof(uint64_t));
+ if (write(s->fd, l2_table, s->l2_size * sizeof(uint64_t)) !=
+ s->l2_size * sizeof(uint64_t))
+ return 0;
+ } else {
+ if (read(s->fd, 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 = lseek64(s->fd, 0, SEEK_END);
+ cluster_offset = (cluster_offset + s->cluster_size - 1) &
+ ~(s->cluster_size - 1);
+ /* write the cluster content */
+ lseek64(s->fd, cluster_offset, SEEK_SET);
+ if (write(s->fd, s->cluster_cache, s->cluster_size) !=
+ s->cluster_size)
+ return -1;
+ } else {
+ cluster_offset = lseek64(s->fd, 0, SEEK_END);
+ if (allocate == 1) {
+ /* round to cluster size */
+ cluster_offset = (cluster_offset + s->cluster_size - 1) &
+ ~(s->cluster_size - 1);
+ ftruncate(s->fd, 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, 0xaa, 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);
+ lseek64(s->fd, cluster_offset + i * 512, SEEK_SET);
+ if (write(s->fd, s->cluster_data, 512) != 512)
+ return -1;
+ }
+ }
+ }
+ } else {
+ cluster_offset |= QCOW_OFLAG_COMPRESSED |
+ (uint64_t)compressed_size << (63 - s->cluster_bits);
+ }
+ }
+ /* update L2 table */
+ tmp = cpu_to_be64(cluster_offset);
+ l2_table[l2_index] = tmp;
+ lseek64(s->fd, l2_offset + l2_index * sizeof(tmp), SEEK_SET);
+ if (write(s->fd, &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);
+ lseek64(s->fd, coffset, SEEK_SET);
+ ret = read(s->fd, 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;
+}
+
+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) {
+ 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 {
+ lseek64(s->fd, cluster_offset + index_in_cluster * 512, SEEK_SET);
+ ret = read(s->fd, 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;
+}
+
+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;
+ lseek64(s->fd, cluster_offset + index_in_cluster * 512, SEEK_SET);
+ if (s->crypt_method) {
+ encrypt_sectors(s, sector_num, s->cluster_data, buf, n, 1,
+ &s->aes_encrypt_key);
+ ret = write(s->fd, s->cluster_data, n * 512);
+ } else {
+ ret = write(s->fd, 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;
+}
+
+static int 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);
+ close(s->fd);
+}
+
+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;
+ char backing_filename[1024];
+ uint64_t tmp;
+ struct stat st;
+
+ fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY | O_LARGEFILE,
+ 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) {
+ realpath(backing_file, backing_filename);
+ if (stat(backing_filename, &st) != 0) {
+ return -1;
+ }
+ header.mtime = cpu_to_be32(st.st_mtime);
+ header.backing_file_offset = cpu_to_be64(header_size);
+ backing_filename_len = strlen(backing_filename);
+ header.backing_file_size = cpu_to_be32(backing_filename_len);
+ header_size += backing_filename_len;
+ 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) {
+ 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_filename, 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;
+}
+
+int qcow_get_cluster_size(BlockDriverState *bs)
+{
+ BDRVQcowState *s = bs->opaque;
+ if (bs->drv != &bdrv_qcow)
+ return -1;
+ return s->cluster_size;
+}
+
+/* XXX: put compressed sectors first, then all the cluster aligned
+ tables to avoid losing bytes in alignment */
+int qcow_compress_cluster(BlockDriverState *bs, int64_t sector_num,
+ const uint8_t *buf)
+{
+ BDRVQcowState *s = bs->opaque;
+ z_stream strm;
+ int ret, out_len;
+ uint8_t *out_buf;
+ uint64_t cluster_offset;
+
+ if (bs->drv != &bdrv_qcow)
+ return -1;
+
+ 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;
+ lseek64(s->fd, cluster_offset, SEEK_SET);
+ if (write(s->fd, out_buf, out_len) != out_len) {
+ qemu_free(out_buf);
+ return -1;
+ }
+ }
+
+ qemu_free(out_buf);
+ return 0;
+}
+
+BlockDriver bdrv_qcow = {
+ "qcow",
+ sizeof(BDRVQcowState),
+ qcow_probe,
+ qcow_open,
+ qcow_read,
+ qcow_write,
+ qcow_close,
+ qcow_create,
+ qcow_is_allocated,
+ qcow_set_key,
+};
+
+
