ia64/xen-unstable

view tools/ioemu/block-qcow.c @ 8740:3d7ea7972b39

Update patches for linux 2.6.15.

Signed-off-by: Christian Limpach <Christian.Limpach@cl.cam.ac.uk>
author cl349@firebug.cl.cam.ac.uk
date Thu Feb 02 17:16:00 2006 +0000 (2006-02-02)
parents 8e5fc5fe636c
children f7b43e5c42b9
line source
1 /*
2 * Block driver for the QCOW format
3 *
4 * Copyright (c) 2004 Fabrice Bellard
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to deal
8 * in the Software without restriction, including without limitation the rights
9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10 * copies of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
22 * THE SOFTWARE.
23 */
24 #include "vl.h"
25 #include "block_int.h"
26 #include <zlib.h>
27 #include "aes.h"
29 /**************************************************************/
30 /* QEMU COW block driver with compression and encryption support */
32 #define QCOW_MAGIC (('Q' << 24) | ('F' << 16) | ('I' << 8) | 0xfb)
33 #define QCOW_VERSION 1
35 #define QCOW_CRYPT_NONE 0
36 #define QCOW_CRYPT_AES 1
38 #define QCOW_OFLAG_COMPRESSED (1LL << 63)
40 typedef struct QCowHeader {
41 uint32_t magic;
42 uint32_t version;
43 uint64_t backing_file_offset;
44 uint32_t backing_file_size;
45 uint32_t mtime;
46 uint64_t size; /* in bytes */
47 uint8_t cluster_bits;
48 uint8_t l2_bits;
49 uint32_t crypt_method;
50 uint64_t l1_table_offset;
51 } QCowHeader;
53 #define L2_CACHE_SIZE 16
55 typedef struct BDRVQcowState {
56 int fd;
57 int cluster_bits;
58 int cluster_size;
59 int cluster_sectors;
60 int l2_bits;
61 int l2_size;
62 int l1_size;
63 uint64_t cluster_offset_mask;
64 uint64_t l1_table_offset;
65 uint64_t *l1_table;
66 uint64_t *l2_cache;
67 uint64_t l2_cache_offsets[L2_CACHE_SIZE];
68 uint32_t l2_cache_counts[L2_CACHE_SIZE];
69 uint8_t *cluster_cache;
70 uint8_t *cluster_data;
71 uint64_t cluster_cache_offset;
72 uint32_t crypt_method; /* current crypt method, 0 if no key yet */
73 uint32_t crypt_method_header;
74 AES_KEY aes_encrypt_key;
75 AES_KEY aes_decrypt_key;
76 } BDRVQcowState;
78 static int decompress_cluster(BDRVQcowState *s, uint64_t cluster_offset);
80 static int qcow_probe(const uint8_t *buf, int buf_size, const char *filename)
81 {
82 const QCowHeader *cow_header = (const void *)buf;
84 if (be32_to_cpu(cow_header->magic) == QCOW_MAGIC &&
85 be32_to_cpu(cow_header->version) == QCOW_VERSION)
86 return 100;
87 else
88 return 0;
89 }
91 static int qcow_open(BlockDriverState *bs, const char *filename)
92 {
93 BDRVQcowState *s = bs->opaque;
94 int fd, len, i, shift;
95 QCowHeader header;
97 fd = open(filename, O_RDWR | O_BINARY | O_LARGEFILE);
98 if (fd < 0) {
99 fd = open(filename, O_RDONLY | O_BINARY | O_LARGEFILE);
100 if (fd < 0)
101 return -1;
102 }
103 s->fd = fd;
104 if (read(fd, &header, sizeof(header)) != sizeof(header))
105 goto fail;
106 be32_to_cpus(&header.magic);
107 be32_to_cpus(&header.version);
108 be64_to_cpus(&header.backing_file_offset);
109 be32_to_cpus(&header.backing_file_size);
110 be32_to_cpus(&header.mtime);
111 be64_to_cpus(&header.size);
112 be32_to_cpus(&header.crypt_method);
113 be64_to_cpus(&header.l1_table_offset);
115 if (header.magic != QCOW_MAGIC || header.version != QCOW_VERSION)
116 goto fail;
117 if (header.size <= 1 || header.cluster_bits < 9)
118 goto fail;
119 if (header.crypt_method > QCOW_CRYPT_AES)
120 goto fail;
121 s->crypt_method_header = header.crypt_method;
122 if (s->crypt_method_header)
123 bs->encrypted = 1;
124 s->cluster_bits = header.cluster_bits;
125 s->cluster_size = 1 << s->cluster_bits;
126 s->cluster_sectors = 1 << (s->cluster_bits - 9);
127 s->l2_bits = header.l2_bits;
128 s->l2_size = 1 << s->l2_bits;
129 bs->total_sectors = header.size / 512;
130 s->cluster_offset_mask = (1LL << (63 - s->cluster_bits)) - 1;
132 /* read the level 1 table */
133 shift = s->cluster_bits + s->l2_bits;
134 s->l1_size = (header.size + (1LL << shift) - 1) >> shift;
136 s->l1_table_offset = header.l1_table_offset;
137 s->l1_table = qemu_malloc(s->l1_size * sizeof(uint64_t));
138 if (!s->l1_table)
139 goto fail;
140 lseek(fd, s->l1_table_offset, SEEK_SET);
141 if (read(fd, s->l1_table, s->l1_size * sizeof(uint64_t)) !=
142 s->l1_size * sizeof(uint64_t))
143 goto fail;
144 for(i = 0;i < s->l1_size; i++) {
145 be64_to_cpus(&s->l1_table[i]);
146 }
147 /* alloc L2 cache */
148 s->l2_cache = qemu_malloc(s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t));
149 if (!s->l2_cache)
150 goto fail;
151 s->cluster_cache = qemu_malloc(s->cluster_size);
152 if (!s->cluster_cache)
153 goto fail;
154 s->cluster_data = qemu_malloc(s->cluster_size);
155 if (!s->cluster_data)
156 goto fail;
157 s->cluster_cache_offset = -1;
159 /* read the backing file name */
160 if (header.backing_file_offset != 0) {
161 len = header.backing_file_size;
162 if (len > 1023)
163 len = 1023;
164 lseek(fd, header.backing_file_offset, SEEK_SET);
165 if (read(fd, bs->backing_file, len) != len)
166 goto fail;
167 bs->backing_file[len] = '\0';
168 }
169 return 0;
171 fail:
172 qemu_free(s->l1_table);
173 qemu_free(s->l2_cache);
174 qemu_free(s->cluster_cache);
175 qemu_free(s->cluster_data);
176 close(fd);
177 return -1;
178 }
180 static int qcow_set_key(BlockDriverState *bs, const char *key)
181 {
182 BDRVQcowState *s = bs->opaque;
183 uint8_t keybuf[16];
184 int len, i;
186 memset(keybuf, 0, 16);
187 len = strlen(key);
188 if (len > 16)
189 len = 16;
190 /* XXX: we could compress the chars to 7 bits to increase
191 entropy */
192 for(i = 0;i < len;i++) {
193 keybuf[i] = key[i];
194 }
195 s->crypt_method = s->crypt_method_header;
197 if (AES_set_encrypt_key(keybuf, 128, &s->aes_encrypt_key) != 0)
198 return -1;
199 if (AES_set_decrypt_key(keybuf, 128, &s->aes_decrypt_key) != 0)
200 return -1;
201 #if 0
202 /* test */
203 {
204 uint8_t in[16];
205 uint8_t out[16];
206 uint8_t tmp[16];
207 for(i=0;i<16;i++)
208 in[i] = i;
209 AES_encrypt(in, tmp, &s->aes_encrypt_key);
210 AES_decrypt(tmp, out, &s->aes_decrypt_key);
211 for(i = 0; i < 16; i++)
212 printf(" %02x", tmp[i]);
213 printf("\n");
214 for(i = 0; i < 16; i++)
215 printf(" %02x", out[i]);
216 printf("\n");
217 }
218 #endif
219 return 0;
220 }
222 /* The crypt function is compatible with the linux cryptoloop
223 algorithm for < 4 GB images. NOTE: out_buf == in_buf is
224 supported */
225 static void encrypt_sectors(BDRVQcowState *s, int64_t sector_num,
226 uint8_t *out_buf, const uint8_t *in_buf,
227 int nb_sectors, int enc,
228 const AES_KEY *key)
229 {
230 union {
231 uint64_t ll[2];
232 uint8_t b[16];
233 } ivec;
234 int i;
236 for(i = 0; i < nb_sectors; i++) {
237 ivec.ll[0] = cpu_to_le64(sector_num);
238 ivec.ll[1] = 0;
239 AES_cbc_encrypt(in_buf, out_buf, 512, key,
240 ivec.b, enc);
241 sector_num++;
242 in_buf += 512;
243 out_buf += 512;
244 }
245 }
247 /* 'allocate' is:
248 *
249 * 0 to not allocate.
250 *
251 * 1 to allocate a normal cluster (for sector indexes 'n_start' to
252 * 'n_end')
253 *
254 * 2 to allocate a compressed cluster of size
255 * 'compressed_size'. 'compressed_size' must be > 0 and <
256 * cluster_size
257 *
258 * return 0 if not allocated.
259 */
260 static uint64_t get_cluster_offset(BlockDriverState *bs,
261 uint64_t offset, int allocate,
262 int compressed_size,
263 int n_start, int n_end)
264 {
265 BDRVQcowState *s = bs->opaque;
266 int min_index, i, j, l1_index, l2_index;
267 uint64_t l2_offset, *l2_table, cluster_offset, tmp;
268 uint32_t min_count;
269 int new_l2_table;
271 l1_index = offset >> (s->l2_bits + s->cluster_bits);
272 l2_offset = s->l1_table[l1_index];
273 new_l2_table = 0;
274 if (!l2_offset) {
275 if (!allocate)
276 return 0;
277 /* allocate a new l2 entry */
278 l2_offset = lseek(s->fd, 0, SEEK_END);
279 /* round to cluster size */
280 l2_offset = (l2_offset + s->cluster_size - 1) & ~(s->cluster_size - 1);
281 /* update the L1 entry */
282 s->l1_table[l1_index] = l2_offset;
283 tmp = cpu_to_be64(l2_offset);
284 lseek(s->fd, s->l1_table_offset + l1_index * sizeof(tmp), SEEK_SET);
285 if (write(s->fd, &tmp, sizeof(tmp)) != sizeof(tmp))
286 return 0;
287 new_l2_table = 1;
288 }
289 for(i = 0; i < L2_CACHE_SIZE; i++) {
290 if (l2_offset == s->l2_cache_offsets[i]) {
291 /* increment the hit count */
292 if (++s->l2_cache_counts[i] == 0xffffffff) {
293 for(j = 0; j < L2_CACHE_SIZE; j++) {
294 s->l2_cache_counts[j] >>= 1;
295 }
296 }
297 l2_table = s->l2_cache + (i << s->l2_bits);
298 goto found;
299 }
300 }
301 /* not found: load a new entry in the least used one */
302 min_index = 0;
303 min_count = 0xffffffff;
304 for(i = 0; i < L2_CACHE_SIZE; i++) {
305 if (s->l2_cache_counts[i] < min_count) {
306 min_count = s->l2_cache_counts[i];
307 min_index = i;
308 }
309 }
310 l2_table = s->l2_cache + (min_index << s->l2_bits);
311 lseek(s->fd, l2_offset, SEEK_SET);
312 if (new_l2_table) {
313 memset(l2_table, 0, s->l2_size * sizeof(uint64_t));
314 if (write(s->fd, l2_table, s->l2_size * sizeof(uint64_t)) !=
315 s->l2_size * sizeof(uint64_t))
316 return 0;
317 } else {
318 if (read(s->fd, l2_table, s->l2_size * sizeof(uint64_t)) !=
319 s->l2_size * sizeof(uint64_t))
320 return 0;
321 }
322 s->l2_cache_offsets[min_index] = l2_offset;
323 s->l2_cache_counts[min_index] = 1;
324 found:
325 l2_index = (offset >> s->cluster_bits) & (s->l2_size - 1);
326 cluster_offset = be64_to_cpu(l2_table[l2_index]);
327 if (!cluster_offset ||
328 ((cluster_offset & QCOW_OFLAG_COMPRESSED) && allocate == 1)) {
329 if (!allocate)
330 return 0;
331 /* allocate a new cluster */
332 if ((cluster_offset & QCOW_OFLAG_COMPRESSED) &&
333 (n_end - n_start) < s->cluster_sectors) {
334 /* if the cluster is already compressed, we must
335 decompress it in the case it is not completely
336 overwritten */
337 if (decompress_cluster(s, cluster_offset) < 0)
338 return 0;
339 cluster_offset = lseek(s->fd, 0, SEEK_END);
340 cluster_offset = (cluster_offset + s->cluster_size - 1) &
341 ~(s->cluster_size - 1);
342 /* write the cluster content */
343 lseek(s->fd, cluster_offset, SEEK_SET);
344 if (write(s->fd, s->cluster_cache, s->cluster_size) !=
345 s->cluster_size)
346 return -1;
347 } else {
348 cluster_offset = lseek(s->fd, 0, SEEK_END);
349 if (allocate == 1) {
350 /* round to cluster size */
351 cluster_offset = (cluster_offset + s->cluster_size - 1) &
352 ~(s->cluster_size - 1);
353 ftruncate(s->fd, cluster_offset + s->cluster_size);
354 /* if encrypted, we must initialize the cluster
355 content which won't be written */
356 if (s->crypt_method &&
357 (n_end - n_start) < s->cluster_sectors) {
358 uint64_t start_sect;
359 start_sect = (offset & ~(s->cluster_size - 1)) >> 9;
360 memset(s->cluster_data + 512, 0xaa, 512);
361 for(i = 0; i < s->cluster_sectors; i++) {
362 if (i < n_start || i >= n_end) {
363 encrypt_sectors(s, start_sect + i,
364 s->cluster_data,
365 s->cluster_data + 512, 1, 1,
366 &s->aes_encrypt_key);
367 lseek(s->fd, cluster_offset + i * 512, SEEK_SET);
368 if (write(s->fd, s->cluster_data, 512) != 512)
369 return -1;
370 }
371 }
372 }
373 } else {
374 cluster_offset |= QCOW_OFLAG_COMPRESSED |
375 (uint64_t)compressed_size << (63 - s->cluster_bits);
376 }
377 }
378 /* update L2 table */
379 tmp = cpu_to_be64(cluster_offset);
380 l2_table[l2_index] = tmp;
381 lseek(s->fd, l2_offset + l2_index * sizeof(tmp), SEEK_SET);
382 if (write(s->fd, &tmp, sizeof(tmp)) != sizeof(tmp))
383 return 0;
384 }
385 return cluster_offset;
386 }
388 static int qcow_is_allocated(BlockDriverState *bs, int64_t sector_num,
389 int nb_sectors, int *pnum)
390 {
391 BDRVQcowState *s = bs->opaque;
392 int index_in_cluster, n;
393 uint64_t cluster_offset;
395 cluster_offset = get_cluster_offset(bs, sector_num << 9, 0, 0, 0, 0);
396 index_in_cluster = sector_num & (s->cluster_sectors - 1);
397 n = s->cluster_sectors - index_in_cluster;
398 if (n > nb_sectors)
399 n = nb_sectors;
400 *pnum = n;
401 return (cluster_offset != 0);
402 }
404 static int decompress_buffer(uint8_t *out_buf, int out_buf_size,
405 const uint8_t *buf, int buf_size)
406 {
407 z_stream strm1, *strm = &strm1;
408 int ret, out_len;
410 memset(strm, 0, sizeof(*strm));
412 strm->next_in = (uint8_t *)buf;
413 strm->avail_in = buf_size;
414 strm->next_out = out_buf;
415 strm->avail_out = out_buf_size;
417 ret = inflateInit2(strm, -12);
418 if (ret != Z_OK)
419 return -1;
420 ret = inflate(strm, Z_FINISH);
421 out_len = strm->next_out - out_buf;
422 if ((ret != Z_STREAM_END && ret != Z_BUF_ERROR) ||
423 out_len != out_buf_size) {
424 inflateEnd(strm);
425 return -1;
426 }
427 inflateEnd(strm);
428 return 0;
429 }
431 static int decompress_cluster(BDRVQcowState *s, uint64_t cluster_offset)
432 {
433 int ret, csize;
434 uint64_t coffset;
436 coffset = cluster_offset & s->cluster_offset_mask;
437 if (s->cluster_cache_offset != coffset) {
438 csize = cluster_offset >> (63 - s->cluster_bits);
439 csize &= (s->cluster_size - 1);
440 lseek(s->fd, coffset, SEEK_SET);
441 ret = read(s->fd, s->cluster_data, csize);
442 if (ret != csize)
443 return -1;
444 if (decompress_buffer(s->cluster_cache, s->cluster_size,
445 s->cluster_data, csize) < 0) {
446 return -1;
447 }
448 s->cluster_cache_offset = coffset;
449 }
450 return 0;
451 }
453 static int qcow_read(BlockDriverState *bs, int64_t sector_num,
454 uint8_t *buf, int nb_sectors)
455 {
456 BDRVQcowState *s = bs->opaque;
457 int ret, index_in_cluster, n;
458 uint64_t cluster_offset;
460 while (nb_sectors > 0) {
461 cluster_offset = get_cluster_offset(bs, sector_num << 9, 0, 0, 0, 0);
462 index_in_cluster = sector_num & (s->cluster_sectors - 1);
463 n = s->cluster_sectors - index_in_cluster;
464 if (n > nb_sectors)
465 n = nb_sectors;
466 if (!cluster_offset) {
467 memset(buf, 0, 512 * n);
468 } else if (cluster_offset & QCOW_OFLAG_COMPRESSED) {
469 if (decompress_cluster(s, cluster_offset) < 0)
470 return -1;
471 memcpy(buf, s->cluster_cache + index_in_cluster * 512, 512 * n);
472 } else {
473 lseek(s->fd, cluster_offset + index_in_cluster * 512, SEEK_SET);
474 ret = read(s->fd, buf, n * 512);
475 if (ret != n * 512)
476 return -1;
477 if (s->crypt_method) {
478 encrypt_sectors(s, sector_num, buf, buf, n, 0,
479 &s->aes_decrypt_key);
480 }
481 }
482 nb_sectors -= n;
483 sector_num += n;
484 buf += n * 512;
485 }
486 return 0;
487 }
489 static int qcow_write(BlockDriverState *bs, int64_t sector_num,
490 const uint8_t *buf, int nb_sectors)
491 {
492 BDRVQcowState *s = bs->opaque;
493 int ret, index_in_cluster, n;
494 uint64_t cluster_offset;
496 while (nb_sectors > 0) {
497 index_in_cluster = sector_num & (s->cluster_sectors - 1);
498 n = s->cluster_sectors - index_in_cluster;
499 if (n > nb_sectors)
500 n = nb_sectors;
501 cluster_offset = get_cluster_offset(bs, sector_num << 9, 1, 0,
502 index_in_cluster,
503 index_in_cluster + n);
504 if (!cluster_offset)
505 return -1;
506 lseek(s->fd, cluster_offset + index_in_cluster * 512, SEEK_SET);
507 if (s->crypt_method) {
508 encrypt_sectors(s, sector_num, s->cluster_data, buf, n, 1,
509 &s->aes_encrypt_key);
510 ret = write(s->fd, s->cluster_data, n * 512);
511 } else {
512 ret = write(s->fd, buf, n * 512);
513 }
514 if (ret != n * 512)
515 return -1;
516 nb_sectors -= n;
517 sector_num += n;
518 buf += n * 512;
519 }
520 s->cluster_cache_offset = -1; /* disable compressed cache */
521 return 0;
522 }
524 static void qcow_close(BlockDriverState *bs)
525 {
526 BDRVQcowState *s = bs->opaque;
527 qemu_free(s->l1_table);
528 qemu_free(s->l2_cache);
529 qemu_free(s->cluster_cache);
530 qemu_free(s->cluster_data);
531 close(s->fd);
532 }
534 static int qcow_create(const char *filename, int64_t total_size,
535 const char *backing_file, int flags)
536 {
537 int fd, header_size, backing_filename_len, l1_size, i, shift;
538 QCowHeader header;
539 char backing_filename[1024];
540 uint64_t tmp;
541 struct stat st;
543 fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY | O_LARGEFILE,
544 0644);
545 if (fd < 0)
546 return -1;
547 memset(&header, 0, sizeof(header));
548 header.magic = cpu_to_be32(QCOW_MAGIC);
549 header.version = cpu_to_be32(QCOW_VERSION);
550 header.size = cpu_to_be64(total_size * 512);
551 header_size = sizeof(header);
552 backing_filename_len = 0;
553 if (backing_file) {
554 realpath(backing_file, backing_filename);
555 if (stat(backing_filename, &st) != 0) {
556 return -1;
557 }
558 header.mtime = cpu_to_be32(st.st_mtime);
559 header.backing_file_offset = cpu_to_be64(header_size);
560 backing_filename_len = strlen(backing_filename);
561 header.backing_file_size = cpu_to_be32(backing_filename_len);
562 header_size += backing_filename_len;
563 header.cluster_bits = 9; /* 512 byte cluster to avoid copying
564 unmodifyed sectors */
565 header.l2_bits = 12; /* 32 KB L2 tables */
566 } else {
567 header.cluster_bits = 12; /* 4 KB clusters */
568 header.l2_bits = 9; /* 4 KB L2 tables */
569 }
570 header_size = (header_size + 7) & ~7;
571 shift = header.cluster_bits + header.l2_bits;
572 l1_size = ((total_size * 512) + (1LL << shift) - 1) >> shift;
574 header.l1_table_offset = cpu_to_be64(header_size);
575 if (flags) {
576 header.crypt_method = cpu_to_be32(QCOW_CRYPT_AES);
577 } else {
578 header.crypt_method = cpu_to_be32(QCOW_CRYPT_NONE);
579 }
581 /* write all the data */
582 write(fd, &header, sizeof(header));
583 if (backing_file) {
584 write(fd, backing_filename, backing_filename_len);
585 }
586 lseek(fd, header_size, SEEK_SET);
587 tmp = 0;
588 for(i = 0;i < l1_size; i++) {
589 write(fd, &tmp, sizeof(tmp));
590 }
591 close(fd);
592 return 0;
593 }
595 int qcow_get_cluster_size(BlockDriverState *bs)
596 {
597 BDRVQcowState *s = bs->opaque;
598 if (bs->drv != &bdrv_qcow)
599 return -1;
600 return s->cluster_size;
601 }
603 /* XXX: put compressed sectors first, then all the cluster aligned
604 tables to avoid losing bytes in alignment */
605 int qcow_compress_cluster(BlockDriverState *bs, int64_t sector_num,
606 const uint8_t *buf)
607 {
608 BDRVQcowState *s = bs->opaque;
609 z_stream strm;
610 int ret, out_len;
611 uint8_t *out_buf;
612 uint64_t cluster_offset;
614 if (bs->drv != &bdrv_qcow)
615 return -1;
617 out_buf = qemu_malloc(s->cluster_size + (s->cluster_size / 1000) + 128);
618 if (!out_buf)
619 return -1;
621 /* best compression, small window, no zlib header */
622 memset(&strm, 0, sizeof(strm));
623 ret = deflateInit2(&strm, Z_DEFAULT_COMPRESSION,
624 Z_DEFLATED, -12,
625 9, Z_DEFAULT_STRATEGY);
626 if (ret != 0) {
627 qemu_free(out_buf);
628 return -1;
629 }
631 strm.avail_in = s->cluster_size;
632 strm.next_in = (uint8_t *)buf;
633 strm.avail_out = s->cluster_size;
634 strm.next_out = out_buf;
636 ret = deflate(&strm, Z_FINISH);
637 if (ret != Z_STREAM_END && ret != Z_OK) {
638 qemu_free(out_buf);
639 deflateEnd(&strm);
640 return -1;
641 }
642 out_len = strm.next_out - out_buf;
644 deflateEnd(&strm);
646 if (ret != Z_STREAM_END || out_len >= s->cluster_size) {
647 /* could not compress: write normal cluster */
648 qcow_write(bs, sector_num, buf, s->cluster_sectors);
649 } else {
650 cluster_offset = get_cluster_offset(bs, sector_num << 9, 2,
651 out_len, 0, 0);
652 cluster_offset &= s->cluster_offset_mask;
653 lseek(s->fd, cluster_offset, SEEK_SET);
654 if (write(s->fd, out_buf, out_len) != out_len) {
655 qemu_free(out_buf);
656 return -1;
657 }
658 }
660 qemu_free(out_buf);
661 return 0;
662 }
664 BlockDriver bdrv_qcow = {
665 "qcow",
666 sizeof(BDRVQcowState),
667 qcow_probe,
668 qcow_open,
669 qcow_read,
670 qcow_write,
671 qcow_close,
672 qcow_create,
673 qcow_is_allocated,
674 qcow_set_key,
675 };