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 "module.h"
  27 #include <zlib.h>
  28 #include "aes.h"
  29
  30 /**************************************************************/
  31 /* QEMU COW block driver with compression and encryption support */
  32
  33 #define QCOW_MAGIC (('Q' << 24) | ('F' << 16) | ('I' << 8) | 0xfb)
  34 #define QCOW_VERSION 1
  35
  36 #define QCOW_CRYPT_NONE 0
  37 #define QCOW_CRYPT_AES  1
  38
  39 #define QCOW_OFLAG_COMPRESSED (1LL << 63)
  40
  41 typedef struct QCowHeader {
  42     uint32_t magic;
  43     uint32_t version;
  44     uint64_t backing_file_offset;
  45     uint32_t backing_file_size;
  46     uint32_t mtime;
  47     uint64_t size; /* in bytes */
  48     uint8_t cluster_bits;
  49     uint8_t l2_bits;
  50     uint32_t crypt_method;
  51     uint64_t l1_table_offset;
  52 } QCowHeader;
  53
  54 #define L2_CACHE_SIZE 16
  55
  56 typedef struct BDRVQcowState {
  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     CoMutex lock;
  77 } BDRVQcowState;
  78
  79 static int decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset);
  80
  81 static int qcow_probe(const uint8_t *buf, int buf_size, const char *filename)
  82 {
  83     const QCowHeader *cow_header = (const void *)buf;
  84
  85     if (buf_size >= sizeof(QCowHeader) &&
  86         be32_to_cpu(cow_header->magic) == QCOW_MAGIC &&
  87         be32_to_cpu(cow_header->version) == QCOW_VERSION)
  88         return 100;
  89     else
  90         return 0;
  91 }
  92
  93 static int qcow_open(BlockDriverState *bs, int flags)
  94 {
  95     BDRVQcowState *s = bs->opaque;
  96     int len, i, shift;
  97     QCowHeader header;
  98
  99     if (bdrv_pread(bs->file, 0, &header, sizeof(header)) != sizeof(header))
 100         goto fail;
 101     be32_to_cpus(&header.magic);
 102     be32_to_cpus(&header.version);
 103     be64_to_cpus(&header.backing_file_offset);
 104     be32_to_cpus(&header.backing_file_size);
 105     be32_to_cpus(&header.mtime);
 106     be64_to_cpus(&header.size);
 107     be32_to_cpus(&header.crypt_method);
 108     be64_to_cpus(&header.l1_table_offset);
 109
 110     if (header.magic != QCOW_MAGIC || header.version != QCOW_VERSION)
 111         goto fail;
 112     if (header.size <= 1 || header.cluster_bits < 9)
 113         goto fail;
 114     if (header.crypt_method > QCOW_CRYPT_AES)
 115         goto fail;
 116     s->crypt_method_header = header.crypt_method;
 117     if (s->crypt_method_header)
 118         bs->encrypted = 1;
 119     s->cluster_bits = header.cluster_bits;
 120     s->cluster_size = 1 << s->cluster_bits;
 121     s->cluster_sectors = 1 << (s->cluster_bits - 9);
 122     s->l2_bits = header.l2_bits;
 123     s->l2_size = 1 << s->l2_bits;
 124     bs->total_sectors = header.size / 512;
 125     s->cluster_offset_mask = (1LL << (63 - s->cluster_bits)) - 1;
 126
 127     /* read the level 1 table */
 128     shift = s->cluster_bits + s->l2_bits;
 129     s->l1_size = (header.size + (1LL << shift) - 1) >> shift;
 130
 131     s->l1_table_offset = header.l1_table_offset;
 132     s->l1_table = g_malloc(s->l1_size * sizeof(uint64_t));
 133     if (!s->l1_table)
 134         goto fail;
 135     if (bdrv_pread(bs->file, s->l1_table_offset, s->l1_table, s->l1_size * sizeof(uint64_t)) !=
 136         s->l1_size * sizeof(uint64_t))
 137         goto fail;
 138     for(i = 0;i < s->l1_size; i++) {
 139         be64_to_cpus(&s->l1_table[i]);
 140     }
 141     /* alloc L2 cache */
 142     s->l2_cache = g_malloc(s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t));
 143     if (!s->l2_cache)
 144         goto fail;
 145     s->cluster_cache = g_malloc(s->cluster_size);
 146     if (!s->cluster_cache)
 147         goto fail;
 148     s->cluster_data = g_malloc(s->cluster_size);
 149     if (!s->cluster_data)
 150         goto fail;
 151     s->cluster_cache_offset = -1;
 152
 153     /* read the backing file name */
 154     if (header.backing_file_offset != 0) {
 155         len = header.backing_file_size;
 156         if (len > 1023)
 157             len = 1023;
 158         if (bdrv_pread(bs->file, header.backing_file_offset, bs->backing_file, len) != len)
 159             goto fail;
 160         bs->backing_file[len] = '\0';
 161     }
 162
 163     qemu_co_mutex_init(&s->lock);
 164     return 0;
 165
 166  fail:
 167     g_free(s->l1_table);
 168     g_free(s->l2_cache);
 169     g_free(s->cluster_cache);
 170     g_free(s->cluster_data);
 171     return -1;
 172 }
 173
 174 static int qcow_set_key(BlockDriverState *bs, const char *key)
 175 {
 176     BDRVQcowState *s = bs->opaque;
 177     uint8_t keybuf[16];
 178     int len, i;
 179
 180     memset(keybuf, 0, 16);
 181     len = strlen(key);
 182     if (len > 16)
 183         len = 16;
 184     /* XXX: we could compress the chars to 7 bits to increase
 185        entropy */
 186     for(i = 0;i < len;i++) {
 187         keybuf[i] = key[i];
 188     }
 189     s->crypt_method = s->crypt_method_header;
 190
 191     if (AES_set_encrypt_key(keybuf, 128, &s->aes_encrypt_key) != 0)
 192         return -1;
 193     if (AES_set_decrypt_key(keybuf, 128, &s->aes_decrypt_key) != 0)
 194         return -1;
 195     return 0;
 196 }
 197
 198 /* The crypt function is compatible with the linux cryptoloop
 199    algorithm for < 4 GB images. NOTE: out_buf == in_buf is
 200    supported */
 201 static void encrypt_sectors(BDRVQcowState *s, int64_t sector_num,
 202                             uint8_t *out_buf, const uint8_t *in_buf,
 203                             int nb_sectors, int enc,
 204                             const AES_KEY *key)
 205 {
 206     union {
 207         uint64_t ll[2];
 208         uint8_t b[16];
 209     } ivec;
 210     int i;
 211
 212     for(i = 0; i < nb_sectors; i++) {
 213         ivec.ll[0] = cpu_to_le64(sector_num);
 214         ivec.ll[1] = 0;
 215         AES_cbc_encrypt(in_buf, out_buf, 512, key,
 216                         ivec.b, enc);
 217         sector_num++;
 218         in_buf += 512;
 219         out_buf += 512;
 220     }
 221 }
 222
 223 /* 'allocate' is:
 224  *
 225  * 0 to not allocate.
 226  *
 227  * 1 to allocate a normal cluster (for sector indexes 'n_start' to
 228  * 'n_end')
 229  *
 230  * 2 to allocate a compressed cluster of size
 231  * 'compressed_size'. 'compressed_size' must be > 0 and <
 232  * cluster_size
 233  *
 234  * return 0 if not allocated.
 235  */
 236 static uint64_t get_cluster_offset(BlockDriverState *bs,
 237                                    uint64_t offset, int allocate,
 238                                    int compressed_size,
 239                                    int n_start, int n_end)
 240 {
 241     BDRVQcowState *s = bs->opaque;
 242     int min_index, i, j, l1_index, l2_index;
 243     uint64_t l2_offset, *l2_table, cluster_offset, tmp;
 244     uint32_t min_count;
 245     int new_l2_table;
 246
 247     l1_index = offset >> (s->l2_bits + s->cluster_bits);
 248     l2_offset = s->l1_table[l1_index];
 249     new_l2_table = 0;
 250     if (!l2_offset) {
 251         if (!allocate)
 252             return 0;
 253         /* allocate a new l2 entry */
 254         l2_offset = bdrv_getlength(bs->file);
 255         /* round to cluster size */
 256         l2_offset = (l2_offset + s->cluster_size - 1) & ~(s->cluster_size - 1);
 257         /* update the L1 entry */
 258         s->l1_table[l1_index] = l2_offset;
 259         tmp = cpu_to_be64(l2_offset);
 260         if (bdrv_pwrite_sync(bs->file,
 261                 s->l1_table_offset + l1_index * sizeof(tmp),
 262                 &tmp, sizeof(tmp)) < 0)
 263             return 0;
 264         new_l2_table = 1;
 265     }
 266     for(i = 0; i < L2_CACHE_SIZE; i++) {
 267         if (l2_offset == s->l2_cache_offsets[i]) {
 268             /* increment the hit count */
 269             if (++s->l2_cache_counts[i] == 0xffffffff) {
 270                 for(j = 0; j < L2_CACHE_SIZE; j++) {
 271                     s->l2_cache_counts[j] >>= 1;
 272                 }
 273             }
 274             l2_table = s->l2_cache + (i << s->l2_bits);
 275             goto found;
 276         }
 277     }
 278     /* not found: load a new entry in the least used one */
 279     min_index = 0;
 280     min_count = 0xffffffff;
 281     for(i = 0; i < L2_CACHE_SIZE; i++) {
 282         if (s->l2_cache_counts[i] < min_count) {
 283             min_count = s->l2_cache_counts[i];
 284             min_index = i;
 285         }
 286     }
 287     l2_table = s->l2_cache + (min_index << s->l2_bits);
 288     if (new_l2_table) {
 289         memset(l2_table, 0, s->l2_size * sizeof(uint64_t));
 290         if (bdrv_pwrite_sync(bs->file, l2_offset, l2_table,
 291                 s->l2_size * sizeof(uint64_t)) < 0)
 292             return 0;
 293     } else {
 294         if (bdrv_pread(bs->file, l2_offset, l2_table, s->l2_size * sizeof(uint64_t)) !=
 295             s->l2_size * sizeof(uint64_t))
 296             return 0;
 297     }
 298     s->l2_cache_offsets[min_index] = l2_offset;
 299     s->l2_cache_counts[min_index] = 1;
 300  found:
 301     l2_index = (offset >> s->cluster_bits) & (s->l2_size - 1);
 302     cluster_offset = be64_to_cpu(l2_table[l2_index]);
 303     if (!cluster_offset ||
 304         ((cluster_offset & QCOW_OFLAG_COMPRESSED) && allocate == 1)) {
 305         if (!allocate)
 306             return 0;
 307         /* allocate a new cluster */
 308         if ((cluster_offset & QCOW_OFLAG_COMPRESSED) &&
 309             (n_end - n_start) < s->cluster_sectors) {
 310             /* if the cluster is already compressed, we must
 311                decompress it in the case it is not completely
 312                overwritten */
 313             if (decompress_cluster(bs, cluster_offset) < 0)
 314                 return 0;
 315             cluster_offset = bdrv_getlength(bs->file);
 316             cluster_offset = (cluster_offset + s->cluster_size - 1) &
 317                 ~(s->cluster_size - 1);
 318             /* write the cluster content */
 319             if (bdrv_pwrite(bs->file, cluster_offset, s->cluster_cache, s->cluster_size) !=
 320                 s->cluster_size)
 321                 return -1;
 322         } else {
 323             cluster_offset = bdrv_getlength(bs->file);
 324             if (allocate == 1) {
 325                 /* round to cluster size */
 326                 cluster_offset = (cluster_offset + s->cluster_size - 1) &
 327                     ~(s->cluster_size - 1);
 328                 bdrv_truncate(bs->file, cluster_offset + s->cluster_size);
 329                 /* if encrypted, we must initialize the cluster
 330                    content which won't be written */
 331                 if (s->crypt_method &&
 332                     (n_end - n_start) < s->cluster_sectors) {
 333                     uint64_t start_sect;
 334                     start_sect = (offset & ~(s->cluster_size - 1)) >> 9;
 335                     memset(s->cluster_data + 512, 0x00, 512);
 336                     for(i = 0; i < s->cluster_sectors; i++) {
 337                         if (i < n_start || i >= n_end) {
 338                             encrypt_sectors(s, start_sect + i,
 339                                             s->cluster_data,
 340                                             s->cluster_data + 512, 1, 1,
 341                                             &s->aes_encrypt_key);
 342                             if (bdrv_pwrite(bs->file, cluster_offset + i * 512,
 343                                             s->cluster_data, 512) != 512)
 344                                 return -1;
 345                         }
 346                     }
 347                 }
 348             } else if (allocate == 2) {
 349                 cluster_offset |= QCOW_OFLAG_COMPRESSED |
 350                     (uint64_t)compressed_size << (63 - s->cluster_bits);
 351             }
 352         }
 353         /* update L2 table */
 354         tmp = cpu_to_be64(cluster_offset);
 355         l2_table[l2_index] = tmp;
 356         if (bdrv_pwrite_sync(bs->file, l2_offset + l2_index * sizeof(tmp),
 357                 &tmp, sizeof(tmp)) < 0)
 358             return 0;
 359     }
 360     return cluster_offset;
 361 }
 362
 363 static int qcow_is_allocated(BlockDriverState *bs, int64_t sector_num,
 364                              int nb_sectors, int *pnum)
 365 {
 366     BDRVQcowState *s = bs->opaque;
 367     int index_in_cluster, n;
 368     uint64_t cluster_offset;
 369
 370     cluster_offset = get_cluster_offset(bs, sector_num << 9, 0, 0, 0, 0);
 371     index_in_cluster = sector_num & (s->cluster_sectors - 1);
 372     n = s->cluster_sectors - index_in_cluster;
 373     if (n > nb_sectors)
 374         n = nb_sectors;
 375     *pnum = n;
 376     return (cluster_offset != 0);
 377 }
 378
 379 static int decompress_buffer(uint8_t *out_buf, int out_buf_size,
 380                              const uint8_t *buf, int buf_size)
 381 {
 382     z_stream strm1, *strm = &strm1;
 383     int ret, out_len;
 384
 385     memset(strm, 0, sizeof(*strm));
 386
 387     strm->next_in = (uint8_t *)buf;
 388     strm->avail_in = buf_size;
 389     strm->next_out = out_buf;
 390     strm->avail_out = out_buf_size;
 391
 392     ret = inflateInit2(strm, -12);
 393     if (ret != Z_OK)
 394         return -1;
 395     ret = inflate(strm, Z_FINISH);
 396     out_len = strm->next_out - out_buf;
 397     if ((ret != Z_STREAM_END && ret != Z_BUF_ERROR) ||
 398         out_len != out_buf_size) {
 399         inflateEnd(strm);
 400         return -1;
 401     }
 402     inflateEnd(strm);
 403     return 0;
 404 }
 405
 406 static int decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset)
 407 {
 408     BDRVQcowState *s = bs->opaque;
 409     int ret, csize;
 410     uint64_t coffset;
 411
 412     coffset = cluster_offset & s->cluster_offset_mask;
 413     if (s->cluster_cache_offset != coffset) {
 414         csize = cluster_offset >> (63 - s->cluster_bits);
 415         csize &= (s->cluster_size - 1);
 416         ret = bdrv_pread(bs->file, coffset, s->cluster_data, csize);
 417         if (ret != csize)
 418             return -1;
 419         if (decompress_buffer(s->cluster_cache, s->cluster_size,
 420                               s->cluster_data, csize) < 0) {
 421             return -1;
 422         }
 423         s->cluster_cache_offset = coffset;
 424     }
 425     return 0;
 426 }
 427
 428 static int qcow_co_readv(BlockDriverState *bs, int64_t sector_num,
 429                          int nb_sectors, QEMUIOVector *qiov)
 430 {
 431     BDRVQcowState *s = bs->opaque;
 432     int index_in_cluster;
 433     int ret = 0, n;
 434     uint64_t cluster_offset;
 435     struct iovec hd_iov;
 436     QEMUIOVector hd_qiov;
 437     uint8_t *buf;
 438     void *orig_buf;
 439
 440     if (qiov->niov > 1) {
 441         buf = orig_buf = qemu_blockalign(bs, qiov->size);
 442     } else {
 443         orig_buf = NULL;
 444         buf = (uint8_t *)qiov->iov->iov_base;
 445     }
 446
 447     qemu_co_mutex_lock(&s->lock);
 448
 449     while (nb_sectors != 0) {
 450         /* prepare next request */
 451         cluster_offset = get_cluster_offset(bs, sector_num << 9,
 452                                                  0, 0, 0, 0);
 453         index_in_cluster = sector_num & (s->cluster_sectors - 1);
 454         n = s->cluster_sectors - index_in_cluster;
 455         if (n > nb_sectors) {
 456             n = nb_sectors;
 457         }
 458
 459         if (!cluster_offset) {
 460             if (bs->backing_hd) {
 461                 /* read from the base image */
 462                 hd_iov.iov_base = (void *)buf;
 463                 hd_iov.iov_len = n * 512;
 464                 qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
 465                 qemu_co_mutex_unlock(&s->lock);
 466                 ret = bdrv_co_readv(bs->backing_hd, sector_num,
 467                                     n, &hd_qiov);
 468                 qemu_co_mutex_lock(&s->lock);
 469                 if (ret < 0) {
 470                     goto fail;
 471                 }
 472             } else {
 473                 /* Note: in this case, no need to wait */
 474                 memset(buf, 0, 512 * n);
 475             }
 476         } else if (cluster_offset & QCOW_OFLAG_COMPRESSED) {
 477             /* add AIO support for compressed blocks ? */
 478             if (decompress_cluster(bs, cluster_offset) < 0) {
 479                 goto fail;
 480             }
 481             memcpy(buf,
 482                    s->cluster_cache + index_in_cluster * 512, 512 * n);
 483         } else {
 484             if ((cluster_offset & 511) != 0) {
 485                 goto fail;
 486             }
 487             hd_iov.iov_base = (void *)buf;
 488             hd_iov.iov_len = n * 512;
 489             qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
 490             qemu_co_mutex_unlock(&s->lock);
 491             ret = bdrv_co_readv(bs->file,
 492                                 (cluster_offset >> 9) + index_in_cluster,
 493                                 n, &hd_qiov);
 494             qemu_co_mutex_lock(&s->lock);
 495             if (ret < 0) {
 496                 break;
 497             }
 498             if (s->crypt_method) {
 499                 encrypt_sectors(s, sector_num, buf, buf,
 500                                 n, 0,
 501                                 &s->aes_decrypt_key);
 502             }
 503         }
 504         ret = 0;
 505
 506         nb_sectors -= n;
 507         sector_num += n;
 508         buf += n * 512;
 509     }
 510
 511 done:
 512     qemu_co_mutex_unlock(&s->lock);
 513
 514     if (qiov->niov > 1) {
 515         qemu_iovec_from_buffer(qiov, orig_buf, qiov->size);
 516         qemu_vfree(orig_buf);
 517     }
 518
 519     return ret;
 520
 521 fail:
 522     ret = -EIO;
 523     goto done;
 524 }
 525
 526 static int qcow_co_writev(BlockDriverState *bs, int64_t sector_num,
 527                           int nb_sectors, QEMUIOVector *qiov)
 528 {
 529     BDRVQcowState *s = bs->opaque;
 530     int index_in_cluster;
 531     uint64_t cluster_offset;
 532     const uint8_t *src_buf;
 533     int ret = 0, n;
 534     uint8_t *cluster_data = NULL;
 535     struct iovec hd_iov;
 536     QEMUIOVector hd_qiov;
 537     uint8_t *buf;
 538     void *orig_buf;
 539
 540     s->cluster_cache_offset = -1; /* disable compressed cache */
 541
 542     if (qiov->niov > 1) {
 543         buf = orig_buf = qemu_blockalign(bs, qiov->size);
 544         qemu_iovec_to_buffer(qiov, buf);
 545     } else {
 546         orig_buf = NULL;
 547         buf = (uint8_t *)qiov->iov->iov_base;
 548     }
 549
 550     qemu_co_mutex_lock(&s->lock);
 551
 552     while (nb_sectors != 0) {
 553
 554         index_in_cluster = sector_num & (s->cluster_sectors - 1);
 555         n = s->cluster_sectors - index_in_cluster;
 556         if (n > nb_sectors) {
 557             n = nb_sectors;
 558         }
 559         cluster_offset = get_cluster_offset(bs, sector_num << 9, 1, 0,
 560                                             index_in_cluster,
 561                                             index_in_cluster + n);
 562         if (!cluster_offset || (cluster_offset & 511) != 0) {
 563             ret = -EIO;
 564             break;
 565         }
 566         if (s->crypt_method) {
 567             if (!cluster_data) {
 568                 cluster_data = g_malloc0(s->cluster_size);
 569             }
 570             encrypt_sectors(s, sector_num, cluster_data, buf,
 571                             n, 1, &s->aes_encrypt_key);
 572             src_buf = cluster_data;
 573         } else {
 574             src_buf = buf;
 575         }
 576
 577         hd_iov.iov_base = (void *)src_buf;
 578         hd_iov.iov_len = n * 512;
 579         qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
 580         qemu_co_mutex_unlock(&s->lock);
 581         ret = bdrv_co_writev(bs->file,
 582                              (cluster_offset >> 9) + index_in_cluster,
 583                              n, &hd_qiov);
 584         qemu_co_mutex_lock(&s->lock);
 585         if (ret < 0) {
 586             break;
 587         }
 588         ret = 0;
 589
 590         nb_sectors -= n;
 591         sector_num += n;
 592         buf += n * 512;
 593     }
 594     qemu_co_mutex_unlock(&s->lock);
 595
 596     if (qiov->niov > 1) {
 597         qemu_vfree(orig_buf);
 598     }
 599     g_free(cluster_data);
 600
 601     return ret;
 602 }
 603
 604 static void qcow_close(BlockDriverState *bs)
 605 {
 606     BDRVQcowState *s = bs->opaque;
 607     g_free(s->l1_table);
 608     g_free(s->l2_cache);
 609     g_free(s->cluster_cache);
 610     g_free(s->cluster_data);
 611 }
 612
 613 static int qcow_create(const char *filename, QEMUOptionParameter *options)
 614 {
 615     int fd, header_size, backing_filename_len, l1_size, i, shift;
 616     QCowHeader header;
 617     uint64_t tmp;
 618     int64_t total_size = 0;
 619     const char *backing_file = NULL;
 620     int flags = 0;
 621     int ret;
 622
 623     /* Read out options */
 624     while (options && options->name) {
 625         if (!strcmp(options->name, BLOCK_OPT_SIZE)) {
 626             total_size = options->value.n / 512;
 627         } else if (!strcmp(options->name, BLOCK_OPT_BACKING_FILE)) {
 628             backing_file = options->value.s;
 629         } else if (!strcmp(options->name, BLOCK_OPT_ENCRYPT)) {
 630             flags |= options->value.n ? BLOCK_FLAG_ENCRYPT : 0;
 631         }
 632         options++;
 633     }
 634
 635     fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 0644);
 636     if (fd < 0)
 637         return -errno;
 638     memset(&header, 0, sizeof(header));
 639     header.magic = cpu_to_be32(QCOW_MAGIC);
 640     header.version = cpu_to_be32(QCOW_VERSION);
 641     header.size = cpu_to_be64(total_size * 512);
 642     header_size = sizeof(header);
 643     backing_filename_len = 0;
 644     if (backing_file) {
 645         if (strcmp(backing_file, "fat:")) {
 646             header.backing_file_offset = cpu_to_be64(header_size);
 647             backing_filename_len = strlen(backing_file);
 648             header.backing_file_size = cpu_to_be32(backing_filename_len);
 649             header_size += backing_filename_len;
 650         } else {
 651             /* special backing file for vvfat */
 652             backing_file = NULL;
 653         }
 654         header.cluster_bits = 9; /* 512 byte cluster to avoid copying
 655                                     unmodifyed sectors */
 656         header.l2_bits = 12; /* 32 KB L2 tables */
 657     } else {
 658         header.cluster_bits = 12; /* 4 KB clusters */
 659         header.l2_bits = 9; /* 4 KB L2 tables */
 660     }
 661     header_size = (header_size + 7) & ~7;
 662     shift = header.cluster_bits + header.l2_bits;
 663     l1_size = ((total_size * 512) + (1LL << shift) - 1) >> shift;
 664
 665     header.l1_table_offset = cpu_to_be64(header_size);
 666     if (flags & BLOCK_FLAG_ENCRYPT) {
 667         header.crypt_method = cpu_to_be32(QCOW_CRYPT_AES);
 668     } else {
 669         header.crypt_method = cpu_to_be32(QCOW_CRYPT_NONE);
 670     }
 671
 672     /* write all the data */
 673     ret = qemu_write_full(fd, &header, sizeof(header));
 674     if (ret != sizeof(header)) {
 675         ret = -errno;
 676         goto exit;
 677     }
 678
 679     if (backing_file) {
 680         ret = qemu_write_full(fd, backing_file, backing_filename_len);
 681         if (ret != backing_filename_len) {
 682             ret = -errno;
 683             goto exit;
 684         }
 685
 686     }
 687     lseek(fd, header_size, SEEK_SET);
 688     tmp = 0;
 689     for(i = 0;i < l1_size; i++) {
 690         ret = qemu_write_full(fd, &tmp, sizeof(tmp));
 691         if (ret != sizeof(tmp)) {
 692             ret = -errno;
 693             goto exit;
 694         }
 695     }
 696
 697     ret = 0;
 698 exit:
 699     close(fd);
 700     return ret;
 701 }
 702
 703 static int qcow_make_empty(BlockDriverState *bs)
 704 {
 705     BDRVQcowState *s = bs->opaque;
 706     uint32_t l1_length = s->l1_size * sizeof(uint64_t);
 707     int ret;
 708
 709     memset(s->l1_table, 0, l1_length);
 710     if (bdrv_pwrite_sync(bs->file, s->l1_table_offset, s->l1_table,
 711             l1_length) < 0)
 712         return -1;
 713     ret = bdrv_truncate(bs->file, s->l1_table_offset + l1_length);
 714     if (ret < 0)
 715         return ret;
 716
 717     memset(s->l2_cache, 0, s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t));
 718     memset(s->l2_cache_offsets, 0, L2_CACHE_SIZE * sizeof(uint64_t));
 719     memset(s->l2_cache_counts, 0, L2_CACHE_SIZE * sizeof(uint32_t));
 720
 721     return 0;
 722 }
 723
 724 /* XXX: put compressed sectors first, then all the cluster aligned
 725    tables to avoid losing bytes in alignment */
 726 static int qcow_write_compressed(BlockDriverState *bs, int64_t sector_num,
 727                                  const uint8_t *buf, int nb_sectors)
 728 {
 729     BDRVQcowState *s = bs->opaque;
 730     z_stream strm;
 731     int ret, out_len;
 732     uint8_t *out_buf;
 733     uint64_t cluster_offset;
 734
 735     if (nb_sectors != s->cluster_sectors)
 736         return -EINVAL;
 737
 738     out_buf = g_malloc(s->cluster_size + (s->cluster_size / 1000) + 128);
 739     if (!out_buf)
 740         return -1;
 741
 742     /* best compression, small window, no zlib header */
 743     memset(&strm, 0, sizeof(strm));
 744     ret = deflateInit2(&strm, Z_DEFAULT_COMPRESSION,
 745                        Z_DEFLATED, -12,
 746                        9, Z_DEFAULT_STRATEGY);
 747     if (ret != 0) {
 748         g_free(out_buf);
 749         return -1;
 750     }
 751
 752     strm.avail_in = s->cluster_size;
 753     strm.next_in = (uint8_t *)buf;
 754     strm.avail_out = s->cluster_size;
 755     strm.next_out = out_buf;
 756
 757     ret = deflate(&strm, Z_FINISH);
 758     if (ret != Z_STREAM_END && ret != Z_OK) {
 759         g_free(out_buf);
 760         deflateEnd(&strm);
 761         return -1;
 762     }
 763     out_len = strm.next_out - out_buf;
 764
 765     deflateEnd(&strm);
 766
 767     if (ret != Z_STREAM_END || out_len >= s->cluster_size) {
 768         /* could not compress: write normal cluster */
 769         bdrv_write(bs, sector_num, buf, s->cluster_sectors);
 770     } else {
 771         cluster_offset = get_cluster_offset(bs, sector_num << 9, 2,
 772                                             out_len, 0, 0);
 773         cluster_offset &= s->cluster_offset_mask;
 774         if (bdrv_pwrite(bs->file, cluster_offset, out_buf, out_len) != out_len) {
 775             g_free(out_buf);
 776             return -1;
 777         }
 778     }
 779
 780     g_free(out_buf);
 781     return 0;
 782 }
 783
 784 static int qcow_flush(BlockDriverState *bs)
 785 {
 786     return bdrv_flush(bs->file);
 787 }
 788
 789 static BlockDriverAIOCB *qcow_aio_flush(BlockDriverState *bs,
 790         BlockDriverCompletionFunc *cb, void *opaque)
 791 {
 792     return bdrv_aio_flush(bs->file, cb, opaque);
 793 }
 794
 795 static int qcow_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
 796 {
 797     BDRVQcowState *s = bs->opaque;
 798     bdi->cluster_size = s->cluster_size;
 799     return 0;
 800 }
 801
 802
 803 static QEMUOptionParameter qcow_create_options[] = {
 804     {
 805         .name = BLOCK_OPT_SIZE,
 806         .type = OPT_SIZE,
 807         .help = "Virtual disk size"
 808     },
 809     {
 810         .name = BLOCK_OPT_BACKING_FILE,
 811         .type = OPT_STRING,
 812         .help = "File name of a base image"
 813     },
 814     {
 815         .name = BLOCK_OPT_ENCRYPT,
 816         .type = OPT_FLAG,
 817         .help = "Encrypt the image"
 818     },
 819     { NULL }
 820 };
 821
 822 static BlockDriver bdrv_qcow = {
 823     .format_name        = "qcow",
 824     .instance_size      = sizeof(BDRVQcowState),
 825     .bdrv_probe         = qcow_probe,
 826     .bdrv_open          = qcow_open,
 827     .bdrv_close         = qcow_close,
 828     .bdrv_create        = qcow_create,
 829     .bdrv_flush         = qcow_flush,
 830     .bdrv_is_allocated  = qcow_is_allocated,
 831     .bdrv_set_key       = qcow_set_key,
 832     .bdrv_make_empty    = qcow_make_empty,
 833     .bdrv_co_readv  = qcow_co_readv,
 834     .bdrv_co_writev = qcow_co_writev,
 835     .bdrv_aio_flush     = qcow_aio_flush,
 836     .bdrv_write_compressed = qcow_write_compressed,
 837     .bdrv_get_info      = qcow_get_info,
 838
 839     .create_options = qcow_create_options,
 840 };
 841
 842 static void bdrv_qcow_init(void)
 843 {
 844     bdrv_register(&bdrv_qcow);
 845 }
 846
 847 block_init(bdrv_qcow_init);