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             /* round to cluster size */
 343             cluster_offset = (cluster_offset + s->cluster_size - 1) &
 344                 ~(s->cluster_size - 1);
 345             bdrv_truncate(s->hd, cluster_offset + s->cluster_size);
 346             /* if encrypted, we must initialize the cluster
 347                content which won't be written */
 348             if (s->crypt_method &&
 349                 (n_end - n_start) < s->cluster_sectors) {
 350                 uint64_t start_sect;
 351                 start_sect = (offset & ~(s->cluster_size - 1)) >> 9;
 352                 memset(s->cluster_data + 512, 0x00, 512);
 353                 for(i = 0; i < s->cluster_sectors; i++) {
 354                     if (i < n_start || i >= n_end) {
 355                         encrypt_sectors(s, start_sect + i,
 356                                         s->cluster_data,
 357                                         s->cluster_data + 512, 1, 1,
 358                                         &s->aes_encrypt_key);
 359                         if (bdrv_pwrite(s->hd, cluster_offset + i * 512,
 360                                         s->cluster_data, 512) != 512)
 361                             return -1;
 362                     }
 363                 }
 364             }
 365         }
 366         /* update L2 table */
 367         tmp = cpu_to_be64(cluster_offset);
 368         l2_table[l2_index] = tmp;
 369         if (bdrv_pwrite(s->hd,
 370                         l2_offset + l2_index * sizeof(tmp), &tmp, sizeof(tmp)) != sizeof(tmp))
 371             return 0;
 372     }
 373     return cluster_offset;
 374 }
 375
 376 static int qcow_is_allocated(BlockDriverState *bs, int64_t sector_num,
 377                              int nb_sectors, int *pnum)
 378 {
 379     BDRVQcowState *s = bs->opaque;
 380     int index_in_cluster, n;
 381     uint64_t cluster_offset;
 382
 383     cluster_offset = get_cluster_offset(bs, sector_num << 9, 0, 0, 0, 0);
 384     index_in_cluster = sector_num & (s->cluster_sectors - 1);
 385     n = s->cluster_sectors - index_in_cluster;
 386     if (n > nb_sectors)
 387         n = nb_sectors;
 388     *pnum = n;
 389     return (cluster_offset != 0);
 390 }
 391
 392 static int decompress_buffer(uint8_t *out_buf, int out_buf_size,
 393                              const uint8_t *buf, int buf_size)
 394 {
 395     z_stream strm1, *strm = &strm1;
 396     int ret, out_len;
 397
 398     memset(strm, 0, sizeof(*strm));
 399
 400     strm->next_in = (uint8_t *)buf;
 401     strm->avail_in = buf_size;
 402     strm->next_out = out_buf;
 403     strm->avail_out = out_buf_size;
 404
 405     ret = inflateInit2(strm, -12);
 406     if (ret != Z_OK)
 407         return -1;
 408     ret = inflate(strm, Z_FINISH);
 409     out_len = strm->next_out - out_buf;
 410     if ((ret != Z_STREAM_END && ret != Z_BUF_ERROR) ||
 411         out_len != out_buf_size) {
 412         inflateEnd(strm);
 413         return -1;
 414     }
 415     inflateEnd(strm);
 416     return 0;
 417 }
 418
 419 static int decompress_cluster(BDRVQcowState *s, uint64_t cluster_offset)
 420 {
 421     int ret, csize;
 422     uint64_t coffset;
 423
 424     coffset = cluster_offset & s->cluster_offset_mask;
 425     if (s->cluster_cache_offset != coffset) {
 426         csize = cluster_offset >> (63 - s->cluster_bits);
 427         csize &= (s->cluster_size - 1);
 428         ret = bdrv_pread(s->hd, coffset, s->cluster_data, csize);
 429         if (ret != csize)
 430             return -1;
 431         if (decompress_buffer(s->cluster_cache, s->cluster_size,
 432                               s->cluster_data, csize) < 0) {
 433             return -1;
 434         }
 435         s->cluster_cache_offset = coffset;
 436     }
 437     return 0;
 438 }
 439
 440 #if 0
 441
 442 static int qcow_read(BlockDriverState *bs, int64_t sector_num,
 443                      uint8_t *buf, int nb_sectors)
 444 {
 445     BDRVQcowState *s = bs->opaque;
 446     int ret, index_in_cluster, n;
 447     uint64_t cluster_offset;
 448
 449     while (nb_sectors > 0) {
 450         cluster_offset = get_cluster_offset(bs, sector_num << 9, 0, 0, 0, 0);
 451         index_in_cluster = sector_num & (s->cluster_sectors - 1);
 452         n = s->cluster_sectors - index_in_cluster;
 453         if (n > nb_sectors)
 454             n = nb_sectors;
 455         if (!cluster_offset) {
 456             if (bs->backing_hd) {
 457                 /* read from the base image */
 458                 ret = bdrv_read(bs->backing_hd, sector_num, buf, n);
 459                 if (ret < 0)
 460                     return -1;
 461             } else {
 462                 memset(buf, 0, 512 * n);
 463             }
 464         } else if (cluster_offset & QCOW_OFLAG_COMPRESSED) {
 465             if (decompress_cluster(s, cluster_offset) < 0)
 466                 return -1;
 467             memcpy(buf, s->cluster_cache + index_in_cluster * 512, 512 * n);
 468         } else {
 469             ret = bdrv_pread(s->hd, cluster_offset + index_in_cluster * 512, buf, n * 512);
 470             if (ret != n * 512)
 471                 return -1;
 472             if (s->crypt_method) {
 473                 encrypt_sectors(s, sector_num, buf, buf, n, 0,
 474                                 &s->aes_decrypt_key);
 475             }
 476         }
 477         nb_sectors -= n;
 478         sector_num += n;
 479         buf += n * 512;
 480     }
 481     return 0;
 482 }
 483 #endif
 484
 485 static int qcow_write(BlockDriverState *bs, int64_t sector_num,
 486                      const uint8_t *buf, int nb_sectors)
 487 {
 488     BDRVQcowState *s = bs->opaque;
 489     int ret, index_in_cluster, n;
 490     uint64_t cluster_offset;
 491
 492     while (nb_sectors > 0) {
 493         index_in_cluster = sector_num & (s->cluster_sectors - 1);
 494         n = s->cluster_sectors - index_in_cluster;
 495         if (n > nb_sectors)
 496             n = nb_sectors;
 497         cluster_offset = get_cluster_offset(bs, sector_num << 9, 1, 0,
 498                                             index_in_cluster,
 499                                             index_in_cluster + n);
 500         if (!cluster_offset)
 501             return -1;
 502         if (s->crypt_method) {
 503             encrypt_sectors(s, sector_num, s->cluster_data, buf, n, 1,
 504                             &s->aes_encrypt_key);
 505             ret = bdrv_pwrite(s->hd, cluster_offset + index_in_cluster * 512,
 506                               s->cluster_data, n * 512);
 507         } else {
 508             ret = bdrv_pwrite(s->hd, cluster_offset + index_in_cluster * 512, buf, n * 512);
 509         }
 510         if (ret != n * 512)
 511             return -1;
 512         nb_sectors -= n;
 513         sector_num += n;
 514         buf += n * 512;
 515     }
 516     s->cluster_cache_offset = -1; /* disable compressed cache */
 517     return 0;
 518 }
 519
 520 typedef struct QCowAIOCB {
 521     BlockDriverAIOCB common;
 522     int64_t sector_num;
 523     uint8_t *buf;
 524     int nb_sectors;
 525     int n;
 526     uint64_t cluster_offset;
 527     uint8_t *cluster_data;
 528     BlockDriverAIOCB *hd_aiocb;
 529 } QCowAIOCB;
 530
 531 static void qcow_aio_read_cb(void *opaque, int ret)
 532 {
 533     QCowAIOCB *acb = opaque;
 534     BlockDriverState *bs = acb->common.bs;
 535     BDRVQcowState *s = bs->opaque;
 536     int index_in_cluster;
 537
 538     acb->hd_aiocb = NULL;
 539     if (ret < 0) {
 540     fail:
 541         acb->common.cb(acb->common.opaque, ret);
 542         qemu_aio_release(acb);
 543         return;
 544     }
 545
 546  redo:
 547     /* post process the read buffer */
 548     if (!acb->cluster_offset) {
 549         /* nothing to do */
 550     } else if (acb->cluster_offset & QCOW_OFLAG_COMPRESSED) {
 551         /* nothing to do */
 552     } else {
 553         if (s->crypt_method) {
 554             encrypt_sectors(s, acb->sector_num, acb->buf, acb->buf,
 555                             acb->n, 0,
 556                             &s->aes_decrypt_key);
 557         }
 558     }
 559
 560     acb->nb_sectors -= acb->n;
 561     acb->sector_num += acb->n;
 562     acb->buf += acb->n * 512;
 563
 564     if (acb->nb_sectors == 0) {
 565         /* request completed */
 566         acb->common.cb(acb->common.opaque, 0);
 567         qemu_aio_release(acb);
 568         return;
 569     }
 570
 571     /* prepare next AIO request */
 572     acb->cluster_offset = get_cluster_offset(bs, acb->sector_num << 9,
 573                                              0, 0, 0, 0);
 574     index_in_cluster = acb->sector_num & (s->cluster_sectors - 1);
 575     acb->n = s->cluster_sectors - index_in_cluster;
 576     if (acb->n > acb->nb_sectors)
 577         acb->n = acb->nb_sectors;
 578
 579     if (!acb->cluster_offset) {
 580         if (bs->backing_hd) {
 581             /* read from the base image */
 582             acb->hd_aiocb = bdrv_aio_read(bs->backing_hd,
 583                 acb->sector_num, acb->buf, acb->n, qcow_aio_read_cb, acb);
 584             if (acb->hd_aiocb == NULL)
 585                 goto fail;
 586         } else {
 587             /* Note: in this case, no need to wait */
 588             memset(acb->buf, 0, 512 * acb->n);
 589             goto redo;
 590         }
 591     } else if (acb->cluster_offset & QCOW_OFLAG_COMPRESSED) {
 592         /* add AIO support for compressed blocks ? */
 593         if (decompress_cluster(s, acb->cluster_offset) < 0)
 594             goto fail;
 595         memcpy(acb->buf,
 596                s->cluster_cache + index_in_cluster * 512, 512 * acb->n);
 597         goto redo;
 598     } else {
 599         if ((acb->cluster_offset & 511) != 0) {
 600             ret = -EIO;
 601             goto fail;
 602         }
 603         acb->hd_aiocb = bdrv_aio_read(s->hd,
 604                             (acb->cluster_offset >> 9) + index_in_cluster,
 605                             acb->buf, acb->n, qcow_aio_read_cb, acb);
 606         if (acb->hd_aiocb == NULL)
 607             goto fail;
 608     }
 609 }
 610
 611 static BlockDriverAIOCB *qcow_aio_read(BlockDriverState *bs,
 612         int64_t sector_num, uint8_t *buf, int nb_sectors,
 613         BlockDriverCompletionFunc *cb, void *opaque)
 614 {
 615     QCowAIOCB *acb;
 616
 617     acb = qemu_aio_get(bs, cb, opaque);
 618     if (!acb)
 619         return NULL;
 620     acb->hd_aiocb = NULL;
 621     acb->sector_num = sector_num;
 622     acb->buf = buf;
 623     acb->nb_sectors = nb_sectors;
 624     acb->n = 0;
 625     acb->cluster_offset = 0;
 626
 627     qcow_aio_read_cb(acb, 0);
 628     return &acb->common;
 629 }
 630
 631 static void qcow_aio_write_cb(void *opaque, int ret)
 632 {
 633     QCowAIOCB *acb = opaque;
 634     BlockDriverState *bs = acb->common.bs;
 635     BDRVQcowState *s = bs->opaque;
 636     int index_in_cluster;
 637     uint64_t cluster_offset;
 638     const uint8_t *src_buf;
 639
 640     acb->hd_aiocb = NULL;
 641
 642     if (ret < 0) {
 643     fail:
 644         acb->common.cb(acb->common.opaque, ret);
 645         qemu_aio_release(acb);
 646         return;
 647     }
 648
 649     acb->nb_sectors -= acb->n;
 650     acb->sector_num += acb->n;
 651     acb->buf += acb->n * 512;
 652
 653     if (acb->nb_sectors == 0) {
 654         /* request completed */
 655         acb->common.cb(acb->common.opaque, 0);
 656         qemu_aio_release(acb);
 657         return;
 658     }
 659
 660     index_in_cluster = acb->sector_num & (s->cluster_sectors - 1);
 661     acb->n = s->cluster_sectors - index_in_cluster;
 662     if (acb->n > acb->nb_sectors)
 663         acb->n = acb->nb_sectors;
 664     cluster_offset = get_cluster_offset(bs, acb->sector_num << 9, 1, 0,
 665                                         index_in_cluster,
 666                                         index_in_cluster + acb->n);
 667     if (!cluster_offset || (cluster_offset & 511) != 0) {
 668         ret = -EIO;
 669         goto fail;
 670     }
 671     if (s->crypt_method) {
 672         if (!acb->cluster_data) {
 673             acb->cluster_data = qemu_mallocz(s->cluster_size);
 674             if (!acb->cluster_data) {
 675                 ret = -ENOMEM;
 676                 goto fail;
 677             }
 678         }
 679         encrypt_sectors(s, acb->sector_num, acb->cluster_data, acb->buf,
 680                         acb->n, 1, &s->aes_encrypt_key);
 681         src_buf = acb->cluster_data;
 682     } else {
 683         src_buf = acb->buf;
 684     }
 685     acb->hd_aiocb = bdrv_aio_write(s->hd,
 686                                    (cluster_offset >> 9) + index_in_cluster,
 687                                    src_buf, acb->n,
 688                                    qcow_aio_write_cb, acb);
 689     if (acb->hd_aiocb == NULL)
 690         goto fail;
 691 }
 692
 693 static BlockDriverAIOCB *qcow_aio_write(BlockDriverState *bs,
 694         int64_t sector_num, const uint8_t *buf, int nb_sectors,
 695         BlockDriverCompletionFunc *cb, void *opaque)
 696 {
 697     BDRVQcowState *s = bs->opaque;
 698     QCowAIOCB *acb;
 699
 700     s->cluster_cache_offset = -1; /* disable compressed cache */
 701
 702     acb = qemu_aio_get(bs, cb, opaque);
 703     if (!acb)
 704         return NULL;
 705     acb->hd_aiocb = NULL;
 706     acb->sector_num = sector_num;
 707     acb->buf = (uint8_t *)buf;
 708     acb->nb_sectors = nb_sectors;
 709     acb->n = 0;
 710
 711     qcow_aio_write_cb(acb, 0);
 712     return &acb->common;
 713 }
 714
 715 static void qcow_aio_cancel(BlockDriverAIOCB *blockacb)
 716 {
 717     QCowAIOCB *acb = (QCowAIOCB *)blockacb;
 718     if (acb->hd_aiocb)
 719         bdrv_aio_cancel(acb->hd_aiocb);
 720     qemu_aio_release(acb);
 721 }
 722
 723 static void qcow_close(BlockDriverState *bs)
 724 {
 725     BDRVQcowState *s = bs->opaque;
 726     qemu_free(s->l1_table);
 727     qemu_free(s->l2_cache);
 728     qemu_free(s->cluster_cache);
 729     qemu_free(s->cluster_data);
 730     bdrv_delete(s->hd);
 731 }
 732
 733 static int qcow_create(const char *filename, int64_t total_size,
 734                       const char *backing_file, int flags)
 735 {
 736     int fd, header_size, backing_filename_len, l1_size, i, shift;
 737     QCowHeader header;
 738     uint64_t tmp;
 739
 740     fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 0644);
 741     if (fd < 0)
 742         return -1;
 743     memset(&header, 0, sizeof(header));
 744     header.magic = cpu_to_be32(QCOW_MAGIC);
 745     header.version = cpu_to_be32(QCOW_VERSION);
 746     header.size = cpu_to_be64(total_size * 512);
 747     header_size = sizeof(header);
 748     backing_filename_len = 0;
 749     if (backing_file) {
 750         if (strcmp(backing_file, "fat:")) {
 751             header.backing_file_offset = cpu_to_be64(header_size);
 752             backing_filename_len = strlen(backing_file);
 753             header.backing_file_size = cpu_to_be32(backing_filename_len);
 754             header_size += backing_filename_len;
 755         } else {
 756             /* special backing file for vvfat */
 757             backing_file = NULL;
 758         }
 759         header.cluster_bits = 9; /* 512 byte cluster to avoid copying
 760                                     unmodifyed sectors */
 761         header.l2_bits = 12; /* 32 KB L2 tables */
 762     } else {
 763         header.cluster_bits = 12; /* 4 KB clusters */
 764         header.l2_bits = 9; /* 4 KB L2 tables */
 765     }
 766     header_size = (header_size + 7) & ~7;
 767     shift = header.cluster_bits + header.l2_bits;
 768     l1_size = ((total_size * 512) + (1LL << shift) - 1) >> shift;
 769
 770     header.l1_table_offset = cpu_to_be64(header_size);
 771     if (flags & BLOCK_FLAG_ENCRYPT) {
 772         header.crypt_method = cpu_to_be32(QCOW_CRYPT_AES);
 773     } else {
 774         header.crypt_method = cpu_to_be32(QCOW_CRYPT_NONE);
 775     }
 776
 777     /* write all the data */
 778     write(fd, &header, sizeof(header));
 779     if (backing_file) {
 780         write(fd, backing_file, backing_filename_len);
 781     }
 782     lseek(fd, header_size, SEEK_SET);
 783     tmp = 0;
 784     for(i = 0;i < l1_size; i++) {
 785         write(fd, &tmp, sizeof(tmp));
 786     }
 787     close(fd);
 788     return 0;
 789 }
 790
 791 static int qcow_make_empty(BlockDriverState *bs)
 792 {
 793     BDRVQcowState *s = bs->opaque;
 794     uint32_t l1_length = s->l1_size * sizeof(uint64_t);
 795     int ret;
 796
 797     memset(s->l1_table, 0, l1_length);
 798     if (bdrv_pwrite(s->hd, s->l1_table_offset, s->l1_table, l1_length) < 0)
 799         return -1;
 800     ret = bdrv_truncate(s->hd, s->l1_table_offset + l1_length);
 801     if (ret < 0)
 802         return ret;
 803
 804     memset(s->l2_cache, 0, s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t));
 805     memset(s->l2_cache_offsets, 0, L2_CACHE_SIZE * sizeof(uint64_t));
 806     memset(s->l2_cache_counts, 0, L2_CACHE_SIZE * sizeof(uint32_t));
 807
 808     return 0;
 809 }
 810
 811 /* XXX: put compressed sectors first, then all the cluster aligned
 812    tables to avoid losing bytes in alignment */
 813 static int qcow_write_compressed(BlockDriverState *bs, int64_t sector_num,
 814                                  const uint8_t *buf, int nb_sectors)
 815 {
 816     BDRVQcowState *s = bs->opaque;
 817     z_stream strm;
 818     int ret, out_len;
 819     uint8_t *out_buf;
 820     uint64_t cluster_offset;
 821
 822     if (nb_sectors != s->cluster_sectors)
 823         return -EINVAL;
 824
 825     out_buf = qemu_malloc(s->cluster_size + (s->cluster_size / 1000) + 128);
 826     if (!out_buf)
 827         return -1;
 828
 829     /* best compression, small window, no zlib header */
 830     memset(&strm, 0, sizeof(strm));
 831     ret = deflateInit2(&strm, Z_DEFAULT_COMPRESSION,
 832                        Z_DEFLATED, -12,
 833                        9, Z_DEFAULT_STRATEGY);
 834     if (ret != 0) {
 835         qemu_free(out_buf);
 836         return -1;
 837     }
 838
 839     strm.avail_in = s->cluster_size;
 840     strm.next_in = (uint8_t *)buf;
 841     strm.avail_out = s->cluster_size;
 842     strm.next_out = out_buf;
 843
 844     ret = deflate(&strm, Z_FINISH);
 845     if (ret != Z_STREAM_END && ret != Z_OK) {
 846         qemu_free(out_buf);
 847         deflateEnd(&strm);
 848         return -1;
 849     }
 850     out_len = strm.next_out - out_buf;
 851
 852     deflateEnd(&strm);
 853
 854     if (ret != Z_STREAM_END || out_len >= s->cluster_size) {
 855         /* could not compress: write normal cluster */
 856         qcow_write(bs, sector_num, buf, s->cluster_sectors);
 857     } else {
 858         cluster_offset = get_cluster_offset(bs, sector_num << 9, 2,
 859                                             out_len, 0, 0);
 860         cluster_offset &= s->cluster_offset_mask;
 861         if (bdrv_pwrite(s->hd, cluster_offset, out_buf, out_len) != out_len) {
 862             qemu_free(out_buf);
 863             return -1;
 864         }
 865     }
 866
 867     qemu_free(out_buf);
 868     return 0;
 869 }
 870
 871 static void qcow_flush(BlockDriverState *bs)
 872 {
 873     BDRVQcowState *s = bs->opaque;
 874     bdrv_flush(s->hd);
 875 }
 876
 877 static int qcow_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
 878 {
 879     BDRVQcowState *s = bs->opaque;
 880     bdi->cluster_size = s->cluster_size;
 881     return 0;
 882 }
 883
 884 BlockDriver bdrv_qcow = {
 885     "qcow",
 886     sizeof(BDRVQcowState),
 887     qcow_probe,
 888     qcow_open,
 889     NULL,
 890     NULL,
 891     qcow_close,
 892     qcow_create,
 893     qcow_flush,
 894     qcow_is_allocated,
 895     qcow_set_key,
 896     qcow_make_empty,
 897
 898     .bdrv_aio_read = qcow_aio_read,
 899     .bdrv_aio_write = qcow_aio_write,
 900     .bdrv_aio_cancel = qcow_aio_cancel,
 901     .aiocb_size = sizeof(QCowAIOCB),
 902     .bdrv_write_compressed = qcow_write_compressed,
 903     .bdrv_get_info = qcow_get_info,
 904 };