block-qcow.c

   1 /*
   2  * Block driver for the QCOW format
   3  *
   4  * Copyright (c) 2004-2006 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 "qemu-common.h"
  25 #include "block_int.h"
  26 #include <zlib.h>
  27 #include "aes.h"
  28
  29 /**************************************************************/
  30 /* QEMU COW block driver with compression and encryption support */
  31
  32 #define QCOW_MAGIC (('Q' << 24) | ('F' << 16) | ('I' << 8) | 0xfb)
  33 #define QCOW_VERSION 1
  34
  35 #define QCOW_CRYPT_NONE 0
  36 #define QCOW_CRYPT_AES  1
  37
  38 #define QCOW_OFLAG_COMPRESSED (1LL << 63)
  39
  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;
  52
  53 #define L2_CACHE_SIZE 16
  54
  55 typedef struct BDRVQcowState {
  56     BlockDriverState *hd;
  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;
  77
  78 static int decompress_cluster(BDRVQcowState *s, uint64_t cluster_offset);
  79
  80 static int qcow_probe(const uint8_t *buf, int buf_size, const char *filename)
  81 {
  82     const QCowHeader *cow_header = (const void *)buf;
  83
  84     if (buf_size >= sizeof(QCowHeader) &&
  85         be32_to_cpu(cow_header->magic) == QCOW_MAGIC &&
  86         be32_to_cpu(cow_header->version) == QCOW_VERSION)
  87         return 100;
  88     else
  89         return 0;
  90 }
  91
  92 static int qcow_open(BlockDriverState *bs, const char *filename, int flags)
  93 {
  94     BDRVQcowState *s = bs->opaque;
  95     int len, i, shift, ret;
  96     QCowHeader header;
  97
  98     ret = bdrv_file_open(&s->hd, filename, flags);
  99     if (ret < 0)
 100         return ret;
 101     if (bdrv_pread(s->hd, 0, &header, sizeof(header)) != sizeof(header))
 102         goto fail;
 103     be32_to_cpus(&header.magic);
 104     be32_to_cpus(&header.version);
 105     be64_to_cpus(&header.backing_file_offset);
 106     be32_to_cpus(&header.backing_file_size);
 107     be32_to_cpus(&header.mtime);
 108     be64_to_cpus(&header.size);
 109     be32_to_cpus(&header.crypt_method);
 110     be64_to_cpus(&header.l1_table_offset);
 111
 112     if (header.magic != QCOW_MAGIC || header.version != QCOW_VERSION)
 113         goto fail;
 114     if (header.size <= 1 || header.cluster_bits < 9)
 115         goto fail;
 116     if (header.crypt_method > QCOW_CRYPT_AES)
 117         goto fail;
 118     s->crypt_method_header = header.crypt_method;
 119     if (s->crypt_method_header)
 120         bs->encrypted = 1;
 121     s->cluster_bits = header.cluster_bits;
 122     s->cluster_size = 1 << s->cluster_bits;
 123     s->cluster_sectors = 1 << (s->cluster_bits - 9);
 124     s->l2_bits = header.l2_bits;
 125     s->l2_size = 1 << s->l2_bits;
 126     bs->total_sectors = header.size / 512;
 127     s->cluster_offset_mask = (1LL << (63 - s->cluster_bits)) - 1;
 128
 129     /* read the level 1 table */
 130     shift = s->cluster_bits + s->l2_bits;
 131     s->l1_size = (header.size + (1LL << shift) - 1) >> shift;
 132
 133     s->l1_table_offset = header.l1_table_offset;
 134     s->l1_table = qemu_malloc(s->l1_size * sizeof(uint64_t));
 135     if (!s->l1_table)
 136         goto fail;
 137     if (bdrv_pread(s->hd, s->l1_table_offset, s->l1_table, s->l1_size * sizeof(uint64_t)) !=
 138         s->l1_size * sizeof(uint64_t))
 139         goto fail;
 140     for(i = 0;i < s->l1_size; i++) {
 141         be64_to_cpus(&s->l1_table[i]);
 142     }
 143     /* alloc L2 cache */
 144     s->l2_cache = qemu_malloc(s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t));
 145     if (!s->l2_cache)
 146         goto fail;
 147     s->cluster_cache = qemu_malloc(s->cluster_size);
 148     if (!s->cluster_cache)
 149         goto fail;
 150     s->cluster_data = qemu_malloc(s->cluster_size);
 151     if (!s->cluster_data)
 152         goto fail;
 153     s->cluster_cache_offset = -1;
 154
 155     /* read the backing file name */
 156     if (header.backing_file_offset != 0) {
 157         len = header.backing_file_size;
 158         if (len > 1023)
 159             len = 1023;
 160         if (bdrv_pread(s->hd, header.backing_file_offset, bs->backing_file, len) != len)
 161             goto fail;
 162         bs->backing_file[len] = '\0';
 163     }
 164     return 0;
 165
 166  fail:
 167     qemu_free(s->l1_table);
 168     qemu_free(s->l2_cache);
 169     qemu_free(s->cluster_cache);
 170     qemu_free(s->cluster_data);
 171     bdrv_delete(s->hd);
 172     return -1;
 173 }
 174
 175 static int qcow_set_key(BlockDriverState *bs, const char *key)
 176 {
 177     BDRVQcowState *s = bs->opaque;
 178     uint8_t keybuf[16];
 179     int len, i;
 180
 181     memset(keybuf, 0, 16);
 182     len = strlen(key);
 183     if (len > 16)
 184         len = 16;
 185     /* XXX: we could compress the chars to 7 bits to increase
 186        entropy */
 187     for(i = 0;i < len;i++) {
 188         keybuf[i] = key[i];
 189     }
 190     s->crypt_method = s->crypt_method_header;
 191
 192     if (AES_set_encrypt_key(keybuf, 128, &s->aes_encrypt_key) != 0)
 193         return -1;
 194     if (AES_set_decrypt_key(keybuf, 128, &s->aes_decrypt_key) != 0)
 195         return -1;
 196 #if 0
 197     /* test */
 198     {
 199         uint8_t in[16];
 200         uint8_t out[16];
 201         uint8_t tmp[16];
 202         for(i=0;i<16;i++)
 203             in[i] = i;
 204         AES_encrypt(in, tmp, &s->aes_encrypt_key);
 205         AES_decrypt(tmp, out, &s->aes_decrypt_key);
 206         for(i = 0; i < 16; i++)
 207             printf(" %02x", tmp[i]);
 208         printf("\n");
 209         for(i = 0; i < 16; i++)
 210             printf(" %02x", out[i]);
 211         printf("\n");
 212     }
 213 #endif
 214     return 0;
 215 }
 216
 217 /* The crypt function is compatible with the linux cryptoloop
 218    algorithm for < 4 GB images. NOTE: out_buf == in_buf is
 219    supported */
 220 static void encrypt_sectors(BDRVQcowState *s, int64_t sector_num,
 221                             uint8_t *out_buf, const uint8_t *in_buf,
 222                             int nb_sectors, int enc,
 223                             const AES_KEY *key)
 224 {
 225     union {
 226         uint64_t ll[2];
 227         uint8_t b[16];
 228     } ivec;
 229     int i;
 230
 231     for(i = 0; i < nb_sectors; i++) {
 232         ivec.ll[0] = cpu_to_le64(sector_num);
 233         ivec.ll[1] = 0;
 234         AES_cbc_encrypt(in_buf, out_buf, 512, key,
 235                         ivec.b, enc);
 236         sector_num++;
 237         in_buf += 512;
 238         out_buf += 512;
 239     }
 240 }
 241
 242 /* 'allocate' is:
 243  *
 244  * 0 to not allocate.
 245  *
 246  * 1 to allocate a normal cluster (for sector indexes 'n_start' to
 247  * 'n_end')
 248  *
 249  * 2 to allocate a compressed cluster of size
 250  * 'compressed_size'. 'compressed_size' must be > 0 and <
 251  * cluster_size
 252  *
 253  * return 0 if not allocated.
 254  */
 255 static uint64_t get_cluster_offset(BlockDriverState *bs,
 256                                    uint64_t offset, int allocate,
 257                                    int compressed_size,
 258                                    int n_start, int n_end)
 259 {
 260     BDRVQcowState *s = bs->opaque;
 261     int min_index, i, j, l1_index, l2_index;
 262     uint64_t l2_offset, *l2_table, cluster_offset, tmp;
 263     uint32_t min_count;
 264     int new_l2_table;
 265
 266     l1_index = offset >> (s->l2_bits + s->cluster_bits);
 267     l2_offset = s->l1_table[l1_index];
 268     new_l2_table = 0;
 269     if (!l2_offset) {
 270         if (!allocate)
 271             return 0;
 272         /* allocate a new l2 entry */
 273         l2_offset = bdrv_getlength(s->hd);
 274         /* round to cluster size */
 275         l2_offset = (l2_offset + s->cluster_size - 1) & ~(s->cluster_size - 1);
 276         /* update the L1 entry */
 277         s->l1_table[l1_index] = l2_offset;
 278         tmp = cpu_to_be64(l2_offset);
 279         if (bdrv_pwrite(s->hd, s->l1_table_offset + l1_index * sizeof(tmp),
 280                         &tmp, sizeof(tmp)) != sizeof(tmp))
 281             return 0;
 282         new_l2_table = 1;
 283     }
 284     for(i = 0; i < L2_CACHE_SIZE; i++) {
 285         if (l2_offset == s->l2_cache_offsets[i]) {
 286             /* increment the hit count */
 287             if (++s->l2_cache_counts[i] == 0xffffffff) {
 288                 for(j = 0; j < L2_CACHE_SIZE; j++) {
 289                     s->l2_cache_counts[j] >>= 1;
 290                 }
 291             }
 292             l2_table = s->l2_cache + (i << s->l2_bits);
 293             goto found;
 294         }
 295     }
 296     /* not found: load a new entry in the least used one */
 297     min_index = 0;
 298     min_count = 0xffffffff;
 299     for(i = 0; i < L2_CACHE_SIZE; i++) {
 300         if (s->l2_cache_counts[i] < min_count) {
 301             min_count = s->l2_cache_counts[i];
 302             min_index = i;
 303         }
 304     }
 305     l2_table = s->l2_cache + (min_index << s->l2_bits);
 306     if (new_l2_table) {
 307         memset(l2_table, 0, s->l2_size * sizeof(uint64_t));
 308         if (bdrv_pwrite(s->hd, l2_offset, l2_table, s->l2_size * sizeof(uint64_t)) !=
 309             s->l2_size * sizeof(uint64_t))
 310             return 0;
 311     } else {
 312         if (bdrv_pread(s->hd, l2_offset, l2_table, s->l2_size * sizeof(uint64_t)) !=
 313             s->l2_size * sizeof(uint64_t))
 314             return 0;
 315     }
 316     s->l2_cache_offsets[min_index] = l2_offset;
 317     s->l2_cache_counts[min_index] = 1;
 318  found:
 319     l2_index = (offset >> s->cluster_bits) & (s->l2_size - 1);
 320     cluster_offset = be64_to_cpu(l2_table[l2_index]);
 321     if (!cluster_offset ||
 322         ((cluster_offset & QCOW_OFLAG_COMPRESSED) && allocate == 1)) {
 323         if (!allocate)
 324             return 0;
 325         /* allocate a new cluster */
 326         if ((cluster_offset & QCOW_OFLAG_COMPRESSED) &&
 327             (n_end - n_start) < s->cluster_sectors) {
 328             /* if the cluster is already compressed, we must
 329                decompress it in the case it is not completely
 330                overwritten */
 331             if (decompress_cluster(s, cluster_offset) < 0)
 332                 return 0;
 333             cluster_offset = bdrv_getlength(s->hd);
 334             cluster_offset = (cluster_offset + s->cluster_size - 1) &
 335                 ~(s->cluster_size - 1);
 336             /* write the cluster content */
 337             if (bdrv_pwrite(s->hd, cluster_offset, s->cluster_cache, s->cluster_size) !=
 338                 s->cluster_size)
 339                 return -1;
 340         } else {
 341             cluster_offset = bdrv_getlength(s->hd);
 342             if (allocate == 1) {
 343                 /* round to cluster size */
 344                 cluster_offset = (cluster_offset + s->cluster_size - 1) &
 345                     ~(s->cluster_size - 1);
 346                 bdrv_truncate(s->hd, cluster_offset + s->cluster_size);
 347                 /* if encrypted, we must initialize the cluster
 348                    content which won't be written */
 349                 if (s->crypt_method &&
 350                     (n_end - n_start) < s->cluster_sectors) {
 351                     uint64_t start_sect;
 352                     start_sect = (offset & ~(s->cluster_size - 1)) >> 9;
 353                     memset(s->cluster_data + 512, 0x00, 512);
 354                     for(i = 0; i < s->cluster_sectors; i++) {
 355                         if (i < n_start || i >= n_end) {
 356                             encrypt_sectors(s, start_sect + i,
 357                                             s->cluster_data,
 358                                             s->cluster_data + 512, 1, 1,
 359                                             &s->aes_encrypt_key);
 360                             if (bdrv_pwrite(s->hd, cluster_offset + i * 512,
 361                                             s->cluster_data, 512) != 512)
 362                                 return -1;
 363                         }
 364                     }
 365                 }
 366             } else {
 367                 cluster_offset |= QCOW_OFLAG_COMPRESSED |
 368                     (uint64_t)compressed_size << (63 - s->cluster_bits);
 369             }
 370         }
 371         /* update L2 table */
 372         tmp = cpu_to_be64(cluster_offset);
 373         l2_table[l2_index] = tmp;
 374         if (bdrv_pwrite(s->hd,
 375                         l2_offset + l2_index * sizeof(tmp), &tmp, sizeof(tmp)) != sizeof(tmp))
 376             return 0;
 377     }
 378     return cluster_offset;
 379 }
 380
 381 static int qcow_is_allocated(BlockDriverState *bs, int64_t sector_num,
 382                              int nb_sectors, int *pnum)
 383 {
 384     BDRVQcowState *s = bs->opaque;
 385     int index_in_cluster, n;
 386     uint64_t cluster_offset;
 387
 388     cluster_offset = get_cluster_offset(bs, sector_num << 9, 0, 0, 0, 0);
 389     index_in_cluster = sector_num & (s->cluster_sectors - 1);
 390     n = s->cluster_sectors - index_in_cluster;
 391     if (n > nb_sectors)
 392         n = nb_sectors;
 393     *pnum = n;
 394     return (cluster_offset != 0);
 395 }
 396
 397 static int decompress_buffer(uint8_t *out_buf, int out_buf_size,
 398                              const uint8_t *buf, int buf_size)
 399 {
 400     z_stream strm1, *strm = &strm1;
 401     int ret, out_len;
 402
 403     memset(strm, 0, sizeof(*strm));
 404
 405     strm->next_in = (uint8_t *)buf;
 406     strm->avail_in = buf_size;
 407     strm->next_out = out_buf;
 408     strm->avail_out = out_buf_size;
 409
 410     ret = inflateInit2(strm, -12);
 411     if (ret != Z_OK)
 412         return -1;
 413     ret = inflate(strm, Z_FINISH);
 414     out_len = strm->next_out - out_buf;
 415     if ((ret != Z_STREAM_END && ret != Z_BUF_ERROR) ||
 416         out_len != out_buf_size) {
 417         inflateEnd(strm);
 418         return -1;
 419     }
 420     inflateEnd(strm);
 421     return 0;
 422 }
 423
 424 static int decompress_cluster(BDRVQcowState *s, uint64_t cluster_offset)
 425 {
 426     int ret, csize;
 427     uint64_t coffset;
 428
 429     coffset = cluster_offset & s->cluster_offset_mask;
 430     if (s->cluster_cache_offset != coffset) {
 431         csize = cluster_offset >> (63 - s->cluster_bits);
 432         csize &= (s->cluster_size - 1);
 433         ret = bdrv_pread(s->hd, coffset, s->cluster_data, csize);
 434         if (ret != csize)
 435             return -1;
 436         if (decompress_buffer(s->cluster_cache, s->cluster_size,
 437                               s->cluster_data, csize) < 0) {
 438             return -1;
 439         }
 440         s->cluster_cache_offset = coffset;
 441     }
 442     return 0;
 443 }
 444
 445 #if 0
 446
 447 static int qcow_read(BlockDriverState *bs, int64_t sector_num,
 448                      uint8_t *buf, int nb_sectors)
 449 {
 450     BDRVQcowState *s = bs->opaque;
 451     int ret, index_in_cluster, n;
 452     uint64_t cluster_offset;
 453
 454     while (nb_sectors > 0) {
 455         cluster_offset = get_cluster_offset(bs, sector_num << 9, 0, 0, 0, 0);
 456         index_in_cluster = sector_num & (s->cluster_sectors - 1);
 457         n = s->cluster_sectors - index_in_cluster;
 458         if (n > nb_sectors)
 459             n = nb_sectors;
 460         if (!cluster_offset) {
 461             if (bs->backing_hd) {
 462                 /* read from the base image */
 463                 ret = bdrv_read(bs->backing_hd, sector_num, buf, n);
 464                 if (ret < 0)
 465                     return -1;
 466             } else {
 467                 memset(buf, 0, 512 * n);
 468             }
 469         } else if (cluster_offset & QCOW_OFLAG_COMPRESSED) {
 470             if (decompress_cluster(s, cluster_offset) < 0)
 471                 return -1;
 472             memcpy(buf, s->cluster_cache + index_in_cluster * 512, 512 * n);
 473         } else {
 474             ret = bdrv_pread(s->hd, cluster_offset + index_in_cluster * 512, 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 }
 488 #endif
 489
 490 static int qcow_write(BlockDriverState *bs, int64_t sector_num,
 491                      const uint8_t *buf, int nb_sectors)
 492 {
 493     BDRVQcowState *s = bs->opaque;
 494     int ret, index_in_cluster, n;
 495     uint64_t cluster_offset;
 496
 497     while (nb_sectors > 0) {
 498         index_in_cluster = sector_num & (s->cluster_sectors - 1);
 499         n = s->cluster_sectors - index_in_cluster;
 500         if (n > nb_sectors)
 501             n = nb_sectors;
 502         cluster_offset = get_cluster_offset(bs, sector_num << 9, 1, 0,
 503                                             index_in_cluster,
 504                                             index_in_cluster + n);
 505         if (!cluster_offset)
 506             return -1;
 507         if (s->crypt_method) {
 508             encrypt_sectors(s, sector_num, s->cluster_data, buf, n, 1,
 509                             &s->aes_encrypt_key);
 510             ret = bdrv_pwrite(s->hd, cluster_offset + index_in_cluster * 512,
 511                               s->cluster_data, n * 512);
 512         } else {
 513             ret = bdrv_pwrite(s->hd, cluster_offset + index_in_cluster * 512, buf, n * 512);
 514         }
 515         if (ret != n * 512)
 516             return -1;
 517         nb_sectors -= n;
 518         sector_num += n;
 519         buf += n * 512;
 520     }
 521     s->cluster_cache_offset = -1; /* disable compressed cache */
 522     return 0;
 523 }
 524
 525 typedef struct QCowAIOCB {
 526     BlockDriverAIOCB common;
 527     int64_t sector_num;
 528     uint8_t *buf;
 529     int nb_sectors;
 530     int n;
 531     uint64_t cluster_offset;
 532     uint8_t *cluster_data;
 533     BlockDriverAIOCB *hd_aiocb;
 534 } QCowAIOCB;
 535
 536 static void qcow_aio_read_cb(void *opaque, int ret)
 537 {
 538     QCowAIOCB *acb = opaque;
 539     BlockDriverState *bs = acb->common.bs;
 540     BDRVQcowState *s = bs->opaque;
 541     int index_in_cluster;
 542
 543     acb->hd_aiocb = NULL;
 544     if (ret < 0) {
 545     fail:
 546         acb->common.cb(acb->common.opaque, ret);
 547         qemu_aio_release(acb);
 548         return;
 549     }
 550
 551  redo:
 552     /* post process the read buffer */
 553     if (!acb->cluster_offset) {
 554         /* nothing to do */
 555     } else if (acb->cluster_offset & QCOW_OFLAG_COMPRESSED) {
 556         /* nothing to do */
 557     } else {
 558         if (s->crypt_method) {
 559             encrypt_sectors(s, acb->sector_num, acb->buf, acb->buf,
 560                             acb->n, 0,
 561                             &s->aes_decrypt_key);
 562         }
 563     }
 564
 565     acb->nb_sectors -= acb->n;
 566     acb->sector_num += acb->n;
 567     acb->buf += acb->n * 512;
 568
 569     if (acb->nb_sectors == 0) {
 570         /* request completed */
 571         acb->common.cb(acb->common.opaque, 0);
 572         qemu_aio_release(acb);
 573         return;
 574     }
 575
 576     /* prepare next AIO request */
 577     acb->cluster_offset = get_cluster_offset(bs, acb->sector_num << 9,
 578                                              0, 0, 0, 0);
 579     index_in_cluster = acb->sector_num & (s->cluster_sectors - 1);
 580     acb->n = s->cluster_sectors - index_in_cluster;
 581     if (acb->n > acb->nb_sectors)
 582         acb->n = acb->nb_sectors;
 583
 584     if (!acb->cluster_offset) {
 585         if (bs->backing_hd) {
 586             /* read from the base image */
 587             acb->hd_aiocb = bdrv_aio_read(bs->backing_hd,
 588                 acb->sector_num, acb->buf, acb->n, qcow_aio_read_cb, acb);
 589             if (acb->hd_aiocb == NULL)
 590                 goto fail;
 591         } else {
 592             /* Note: in this case, no need to wait */
 593             memset(acb->buf, 0, 512 * acb->n);
 594             goto redo;
 595         }
 596     } else if (acb->cluster_offset & QCOW_OFLAG_COMPRESSED) {
 597         /* add AIO support for compressed blocks ? */
 598         if (decompress_cluster(s, acb->cluster_offset) < 0)
 599             goto fail;
 600         memcpy(acb->buf,
 601                s->cluster_cache + index_in_cluster * 512, 512 * acb->n);
 602         goto redo;
 603     } else {
 604         if ((acb->cluster_offset & 511) != 0) {
 605             ret = -EIO;
 606             goto fail;
 607         }
 608         acb->hd_aiocb = bdrv_aio_read(s->hd,
 609                             (acb->cluster_offset >> 9) + index_in_cluster,
 610                             acb->buf, acb->n, qcow_aio_read_cb, acb);
 611         if (acb->hd_aiocb == NULL)
 612             goto fail;
 613     }
 614 }
 615
 616 static BlockDriverAIOCB *qcow_aio_read(BlockDriverState *bs,
 617         int64_t sector_num, uint8_t *buf, int nb_sectors,
 618         BlockDriverCompletionFunc *cb, void *opaque)
 619 {
 620     QCowAIOCB *acb;
 621
 622     acb = qemu_aio_get(bs, cb, opaque);
 623     if (!acb)
 624         return NULL;
 625     acb->hd_aiocb = NULL;
 626     acb->sector_num = sector_num;
 627     acb->buf = buf;
 628     acb->nb_sectors = nb_sectors;
 629     acb->n = 0;
 630     acb->cluster_offset = 0;
 631
 632     qcow_aio_read_cb(acb, 0);
 633     return &acb->common;
 634 }
 635
 636 static void qcow_aio_write_cb(void *opaque, int ret)
 637 {
 638     QCowAIOCB *acb = opaque;
 639     BlockDriverState *bs = acb->common.bs;
 640     BDRVQcowState *s = bs->opaque;
 641     int index_in_cluster;
 642     uint64_t cluster_offset;
 643     const uint8_t *src_buf;
 644
 645     acb->hd_aiocb = NULL;
 646
 647     if (ret < 0) {
 648     fail:
 649         acb->common.cb(acb->common.opaque, ret);
 650         qemu_aio_release(acb);
 651         return;
 652     }
 653
 654     acb->nb_sectors -= acb->n;
 655     acb->sector_num += acb->n;
 656     acb->buf += acb->n * 512;
 657
 658     if (acb->nb_sectors == 0) {
 659         /* request completed */
 660         acb->common.cb(acb->common.opaque, 0);
 661         qemu_aio_release(acb);
 662         return;
 663     }
 664
 665     index_in_cluster = acb->sector_num & (s->cluster_sectors - 1);
 666     acb->n = s->cluster_sectors - index_in_cluster;
 667     if (acb->n > acb->nb_sectors)
 668         acb->n = acb->nb_sectors;
 669     cluster_offset = get_cluster_offset(bs, acb->sector_num << 9, 1, 0,
 670                                         index_in_cluster,
 671                                         index_in_cluster + acb->n);
 672     if (!cluster_offset || (cluster_offset & 511) != 0) {
 673         ret = -EIO;
 674         goto fail;
 675     }
 676     if (s->crypt_method) {
 677         if (!acb->cluster_data) {
 678             acb->cluster_data = qemu_mallocz(s->cluster_size);
 679             if (!acb->cluster_data) {
 680                 ret = -ENOMEM;
 681                 goto fail;
 682             }
 683         }
 684         encrypt_sectors(s, acb->sector_num, acb->cluster_data, acb->buf,
 685                         acb->n, 1, &s->aes_encrypt_key);
 686         src_buf = acb->cluster_data;
 687     } else {
 688         src_buf = acb->buf;
 689     }
 690     acb->hd_aiocb = bdrv_aio_write(s->hd,
 691                                    (cluster_offset >> 9) + index_in_cluster,
 692                                    src_buf, acb->n,
 693                                    qcow_aio_write_cb, acb);
 694     if (acb->hd_aiocb == NULL)
 695         goto fail;
 696 }
 697
 698 static BlockDriverAIOCB *qcow_aio_write(BlockDriverState *bs,
 699         int64_t sector_num, const uint8_t *buf, int nb_sectors,
 700         BlockDriverCompletionFunc *cb, void *opaque)
 701 {
 702     BDRVQcowState *s = bs->opaque;
 703     QCowAIOCB *acb;
 704
 705     s->cluster_cache_offset = -1; /* disable compressed cache */
 706
 707     acb = qemu_aio_get(bs, cb, opaque);
 708     if (!acb)
 709         return NULL;
 710     acb->hd_aiocb = NULL;
 711     acb->sector_num = sector_num;
 712     acb->buf = (uint8_t *)buf;
 713     acb->nb_sectors = nb_sectors;
 714     acb->n = 0;
 715
 716     qcow_aio_write_cb(acb, 0);
 717     return &acb->common;
 718 }
 719
 720 static void qcow_aio_cancel(BlockDriverAIOCB *blockacb)
 721 {
 722     QCowAIOCB *acb = (QCowAIOCB *)blockacb;
 723     if (acb->hd_aiocb)
 724         bdrv_aio_cancel(acb->hd_aiocb);
 725     qemu_aio_release(acb);
 726 }
 727
 728 static void qcow_close(BlockDriverState *bs)
 729 {
 730     BDRVQcowState *s = bs->opaque;
 731     qemu_free(s->l1_table);
 732     qemu_free(s->l2_cache);
 733     qemu_free(s->cluster_cache);
 734     qemu_free(s->cluster_data);
 735     bdrv_delete(s->hd);
 736 }
 737
 738 static int qcow_create(const char *filename, int64_t total_size,
 739                       const char *backing_file, int flags)
 740 {
 741     int fd, header_size, backing_filename_len, l1_size, i, shift;
 742     QCowHeader header;
 743     uint64_t tmp;
 744
 745     fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 0644);
 746     if (fd < 0)
 747         return -1;
 748     memset(&header, 0, sizeof(header));
 749     header.magic = cpu_to_be32(QCOW_MAGIC);
 750     header.version = cpu_to_be32(QCOW_VERSION);
 751     header.size = cpu_to_be64(total_size * 512);
 752     header_size = sizeof(header);
 753     backing_filename_len = 0;
 754     if (backing_file) {
 755         header.backing_file_offset = cpu_to_be64(header_size);
 756         backing_filename_len = strlen(backing_file);
 757         header.backing_file_size = cpu_to_be32(backing_filename_len);
 758         header_size += backing_filename_len;
 759         header.mtime = cpu_to_be32(0);
 760         header.cluster_bits = 9; /* 512 byte cluster to avoid copying
 761                                     unmodifyed sectors */
 762         header.l2_bits = 12; /* 32 KB L2 tables */
 763     } else {
 764         header.cluster_bits = 12; /* 4 KB clusters */
 765         header.l2_bits = 9; /* 4 KB L2 tables */
 766     }
 767     header_size = (header_size + 7) & ~7;
 768     shift = header.cluster_bits + header.l2_bits;
 769     l1_size = ((total_size * 512) + (1LL << shift) - 1) >> shift;
 770
 771     header.l1_table_offset = cpu_to_be64(header_size);
 772     if (flags & BLOCK_FLAG_ENCRYPT) {
 773         header.crypt_method = cpu_to_be32(QCOW_CRYPT_AES);
 774     } else {
 775         header.crypt_method = cpu_to_be32(QCOW_CRYPT_NONE);
 776     }
 777
 778     /* write all the data */
 779     write(fd, &header, sizeof(header));
 780     if (backing_file) {
 781         write(fd, backing_file, backing_filename_len);
 782     }
 783     lseek(fd, header_size, SEEK_SET);
 784     tmp = 0;
 785     for(i = 0;i < l1_size; i++) {
 786         write(fd, &tmp, sizeof(tmp));
 787     }
 788     close(fd);
 789     return 0;
 790 }
 791
 792 static int qcow_make_empty(BlockDriverState *bs)
 793 {
 794     BDRVQcowState *s = bs->opaque;
 795     uint32_t l1_length = s->l1_size * sizeof(uint64_t);
 796     int ret;
 797
 798     memset(s->l1_table, 0, l1_length);
 799     if (bdrv_pwrite(s->hd, s->l1_table_offset, s->l1_table, l1_length) < 0)
 800         return -1;
 801     ret = bdrv_truncate(s->hd, s->l1_table_offset + l1_length);
 802     if (ret < 0)
 803         return ret;
 804
 805     memset(s->l2_cache, 0, s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t));
 806     memset(s->l2_cache_offsets, 0, L2_CACHE_SIZE * sizeof(uint64_t));
 807     memset(s->l2_cache_counts, 0, L2_CACHE_SIZE * sizeof(uint32_t));
 808
 809     return 0;
 810 }
 811
 812 /* XXX: put compressed sectors first, then all the cluster aligned
 813    tables to avoid losing bytes in alignment */
 814 static int qcow_write_compressed(BlockDriverState *bs, int64_t sector_num,
 815                                  const uint8_t *buf, int nb_sectors)
 816 {
 817     BDRVQcowState *s = bs->opaque;
 818     z_stream strm;
 819     int ret, out_len;
 820     uint8_t *out_buf;
 821     uint64_t cluster_offset;
 822
 823     if (nb_sectors != s->cluster_sectors)
 824         return -EINVAL;
 825
 826     out_buf = qemu_malloc(s->cluster_size + (s->cluster_size / 1000) + 128);
 827     if (!out_buf)
 828         return -1;
 829
 830     /* best compression, small window, no zlib header */
 831     memset(&strm, 0, sizeof(strm));
 832     ret = deflateInit2(&strm, Z_DEFAULT_COMPRESSION,
 833                        Z_DEFLATED, -12,
 834                        9, Z_DEFAULT_STRATEGY);
 835     if (ret != 0) {
 836         qemu_free(out_buf);
 837         return -1;
 838     }
 839
 840     strm.avail_in = s->cluster_size;
 841     strm.next_in = (uint8_t *)buf;
 842     strm.avail_out = s->cluster_size;
 843     strm.next_out = out_buf;
 844
 845     ret = deflate(&strm, Z_FINISH);
 846     if (ret != Z_STREAM_END && ret != Z_OK) {
 847         qemu_free(out_buf);
 848         deflateEnd(&strm);
 849         return -1;
 850     }
 851     out_len = strm.next_out - out_buf;
 852
 853     deflateEnd(&strm);
 854
 855     if (ret != Z_STREAM_END || out_len >= s->cluster_size) {
 856         /* could not compress: write normal cluster */
 857         qcow_write(bs, sector_num, buf, s->cluster_sectors);
 858     } else {
 859         cluster_offset = get_cluster_offset(bs, sector_num << 9, 2,
 860                                             out_len, 0, 0);
 861         cluster_offset &= s->cluster_offset_mask;
 862         if (bdrv_pwrite(s->hd, cluster_offset, out_buf, out_len) != out_len) {
 863             qemu_free(out_buf);
 864             return -1;
 865         }
 866     }
 867
 868     qemu_free(out_buf);
 869     return 0;
 870 }
 871
 872 static void qcow_flush(BlockDriverState *bs)
 873 {
 874     BDRVQcowState *s = bs->opaque;
 875     bdrv_flush(s->hd);
 876 }
 877
 878 static int qcow_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
 879 {
 880     BDRVQcowState *s = bs->opaque;
 881     bdi->cluster_size = s->cluster_size;
 882     return 0;
 883 }
 884
 885 BlockDriver bdrv_qcow = {
 886     "qcow",
 887     sizeof(BDRVQcowState),
 888     qcow_probe,
 889     qcow_open,
 890     NULL,
 891     NULL,
 892     qcow_close,
 893     qcow_create,
 894     qcow_flush,
 895     qcow_is_allocated,
 896     qcow_set_key,
 897     qcow_make_empty,
 898
 899     .bdrv_aio_read = qcow_aio_read,
 900     .bdrv_aio_write = qcow_aio_write,
 901     .bdrv_aio_cancel = qcow_aio_cancel,
 902     .aiocb_size = sizeof(QCowAIOCB),
 903     .bdrv_write_compressed = qcow_write_compressed,
 904     .bdrv_get_info = qcow_get_info,
 905 };