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 };