Annotation of qemu/block-qcow.c, revision 1.1.1.6

1.1       root        1: /*
                      2:  * Block driver for the QCOW format
1.1.1.5   root        3:  *
1.1.1.4   root        4:  * Copyright (c) 2004-2006 Fabrice Bellard
1.1.1.5   root        5:  *
1.1       root        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:  */
1.1.1.5   root       24: #include "qemu-common.h"
1.1       root       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 {
1.1.1.4   root       56:     BlockDriverState *hd;
1.1       root       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;
1.1.1.5   root       83: 
1.1       root       84:     if (buf_size >= sizeof(QCowHeader) &&
                     85:         be32_to_cpu(cow_header->magic) == QCOW_MAGIC &&
1.1.1.5   root       86:         be32_to_cpu(cow_header->version) == QCOW_VERSION)
1.1       root       87:         return 100;
                     88:     else
                     89:         return 0;
                     90: }
                     91: 
1.1.1.4   root       92: static int qcow_open(BlockDriverState *bs, const char *filename, int flags)
1.1       root       93: {
                     94:     BDRVQcowState *s = bs->opaque;
1.1.1.4   root       95:     int len, i, shift, ret;
1.1       root       96:     QCowHeader header;
1.1.1.4   root       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))
1.1       root      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);
1.1.1.5   root      111: 
1.1       root      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;
1.1.1.5   root      137:     if (bdrv_pread(s->hd, s->l1_table_offset, s->l1_table, s->l1_size * sizeof(uint64_t)) !=
1.1       root      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;
1.1.1.5   root      154: 
1.1       root      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;
1.1.1.4   root      160:         if (bdrv_pread(s->hd, header.backing_file_offset, bs->backing_file, len) != len)
1.1       root      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);
1.1.1.4   root      171:     bdrv_delete(s->hd);
1.1       root      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;
1.1.1.5   root      180: 
1.1       root      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;
1.1.1.5   root      234:         AES_cbc_encrypt(in_buf, out_buf, 512, key,
1.1       root      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 <
1.1.1.5   root      251:  * cluster_size
1.1       root      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;
1.1.1.5   root      265: 
1.1       root      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 */
1.1.1.4   root      273:         l2_offset = bdrv_getlength(s->hd);
1.1       root      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);
1.1.1.5   root      279:         if (bdrv_pwrite(s->hd, s->l1_table_offset + l1_index * sizeof(tmp),
1.1.1.4   root      280:                         &tmp, sizeof(tmp)) != sizeof(tmp))
1.1       root      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));
1.1.1.4   root      308:         if (bdrv_pwrite(s->hd, l2_offset, l2_table, s->l2_size * sizeof(uint64_t)) !=
1.1       root      309:             s->l2_size * sizeof(uint64_t))
                    310:             return 0;
                    311:     } else {
1.1.1.5   root      312:         if (bdrv_pread(s->hd, l2_offset, l2_table, s->l2_size * sizeof(uint64_t)) !=
1.1       root      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]);
1.1.1.5   root      321:     if (!cluster_offset ||
1.1       root      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;
1.1.1.4   root      333:             cluster_offset = bdrv_getlength(s->hd);
1.1.1.5   root      334:             cluster_offset = (cluster_offset + s->cluster_size - 1) &
1.1       root      335:                 ~(s->cluster_size - 1);
                    336:             /* write the cluster content */
1.1.1.5   root      337:             if (bdrv_pwrite(s->hd, cluster_offset, s->cluster_cache, s->cluster_size) !=
1.1       root      338:                 s->cluster_size)
                    339:                 return -1;
                    340:         } else {
1.1.1.4   root      341:             cluster_offset = bdrv_getlength(s->hd);
1.1       root      342:             if (allocate == 1) {
                    343:                 /* round to cluster size */
1.1.1.5   root      344:                 cluster_offset = (cluster_offset + s->cluster_size - 1) &
1.1       root      345:                     ~(s->cluster_size - 1);
1.1.1.4   root      346:                 bdrv_truncate(s->hd, cluster_offset + s->cluster_size);
1.1       root      347:                 /* if encrypted, we must initialize the cluster
                    348:                    content which won't be written */
1.1.1.5   root      349:                 if (s->crypt_method &&
1.1       root      350:                     (n_end - n_start) < s->cluster_sectors) {
                    351:                     uint64_t start_sect;
                    352:                     start_sect = (offset & ~(s->cluster_size - 1)) >> 9;
1.1.1.4   root      353:                     memset(s->cluster_data + 512, 0x00, 512);
1.1       root      354:                     for(i = 0; i < s->cluster_sectors; i++) {
                    355:                         if (i < n_start || i >= n_end) {
1.1.1.5   root      356:                             encrypt_sectors(s, start_sect + i,
                    357:                                             s->cluster_data,
1.1       root      358:                                             s->cluster_data + 512, 1, 1,
                    359:                                             &s->aes_encrypt_key);
1.1.1.5   root      360:                             if (bdrv_pwrite(s->hd, cluster_offset + i * 512,
1.1.1.4   root      361:                                             s->cluster_data, 512) != 512)
1.1       root      362:                                 return -1;
                    363:                         }
                    364:                     }
                    365:                 }
1.1.1.6 ! root      366:             } else if (allocate == 2) {
1.1.1.5   root      367:                 cluster_offset |= QCOW_OFLAG_COMPRESSED |
1.1       root      368:                     (uint64_t)compressed_size << (63 - s->cluster_bits);
                    369:             }
                    370:         }
                    371:         /* update L2 table */
                    372:         tmp = cpu_to_be64(cluster_offset);
                    373:         l2_table[l2_index] = tmp;
1.1.1.5   root      374:         if (bdrv_pwrite(s->hd,
1.1.1.4   root      375:                         l2_offset + l2_index * sizeof(tmp), &tmp, sizeof(tmp)) != sizeof(tmp))
1.1       root      376:             return 0;
                    377:     }
                    378:     return cluster_offset;
                    379: }
                    380: 
1.1.1.5   root      381: static int qcow_is_allocated(BlockDriverState *bs, int64_t sector_num,
1.1       root      382:                              int nb_sectors, int *pnum)
                    383: {
                    384:     BDRVQcowState *s = bs->opaque;
                    385:     int index_in_cluster, n;
                    386:     uint64_t cluster_offset;
                    387: 
                    388:     cluster_offset = get_cluster_offset(bs, sector_num << 9, 0, 0, 0, 0);
                    389:     index_in_cluster = sector_num & (s->cluster_sectors - 1);
                    390:     n = s->cluster_sectors - index_in_cluster;
                    391:     if (n > nb_sectors)
                    392:         n = nb_sectors;
                    393:     *pnum = n;
                    394:     return (cluster_offset != 0);
                    395: }
                    396: 
                    397: static int decompress_buffer(uint8_t *out_buf, int out_buf_size,
                    398:                              const uint8_t *buf, int buf_size)
                    399: {
                    400:     z_stream strm1, *strm = &strm1;
                    401:     int ret, out_len;
                    402: 
                    403:     memset(strm, 0, sizeof(*strm));
                    404: 
                    405:     strm->next_in = (uint8_t *)buf;
                    406:     strm->avail_in = buf_size;
                    407:     strm->next_out = out_buf;
                    408:     strm->avail_out = out_buf_size;
                    409: 
                    410:     ret = inflateInit2(strm, -12);
                    411:     if (ret != Z_OK)
                    412:         return -1;
                    413:     ret = inflate(strm, Z_FINISH);
                    414:     out_len = strm->next_out - out_buf;
                    415:     if ((ret != Z_STREAM_END && ret != Z_BUF_ERROR) ||
                    416:         out_len != out_buf_size) {
                    417:         inflateEnd(strm);
                    418:         return -1;
                    419:     }
                    420:     inflateEnd(strm);
                    421:     return 0;
                    422: }
1.1.1.5   root      423: 
1.1       root      424: static int decompress_cluster(BDRVQcowState *s, uint64_t cluster_offset)
                    425: {
                    426:     int ret, csize;
                    427:     uint64_t coffset;
                    428: 
                    429:     coffset = cluster_offset & s->cluster_offset_mask;
                    430:     if (s->cluster_cache_offset != coffset) {
                    431:         csize = cluster_offset >> (63 - s->cluster_bits);
                    432:         csize &= (s->cluster_size - 1);
1.1.1.4   root      433:         ret = bdrv_pread(s->hd, coffset, s->cluster_data, csize);
1.1.1.5   root      434:         if (ret != csize)
1.1       root      435:             return -1;
                    436:         if (decompress_buffer(s->cluster_cache, s->cluster_size,
                    437:                               s->cluster_data, csize) < 0) {
                    438:             return -1;
                    439:         }
                    440:         s->cluster_cache_offset = coffset;
                    441:     }
                    442:     return 0;
                    443: }
                    444: 
1.1.1.4   root      445: #if 0
                    446: 
1.1.1.5   root      447: static int qcow_read(BlockDriverState *bs, int64_t sector_num,
1.1       root      448:                      uint8_t *buf, int nb_sectors)
                    449: {
                    450:     BDRVQcowState *s = bs->opaque;
                    451:     int ret, index_in_cluster, n;
                    452:     uint64_t cluster_offset;
1.1.1.5   root      453: 
1.1       root      454:     while (nb_sectors > 0) {
                    455:         cluster_offset = get_cluster_offset(bs, sector_num << 9, 0, 0, 0, 0);
                    456:         index_in_cluster = sector_num & (s->cluster_sectors - 1);
                    457:         n = s->cluster_sectors - index_in_cluster;
                    458:         if (n > nb_sectors)
                    459:             n = nb_sectors;
                    460:         if (!cluster_offset) {
1.1.1.4   root      461:             if (bs->backing_hd) {
                    462:                 /* read from the base image */
                    463:                 ret = bdrv_read(bs->backing_hd, sector_num, buf, n);
                    464:                 if (ret < 0)
                    465:                     return -1;
                    466:             } else {
                    467:                 memset(buf, 0, 512 * n);
                    468:             }
1.1       root      469:         } else if (cluster_offset & QCOW_OFLAG_COMPRESSED) {
                    470:             if (decompress_cluster(s, cluster_offset) < 0)
                    471:                 return -1;
                    472:             memcpy(buf, s->cluster_cache + index_in_cluster * 512, 512 * n);
                    473:         } else {
1.1.1.4   root      474:             ret = bdrv_pread(s->hd, cluster_offset + index_in_cluster * 512, buf, n * 512);
1.1.1.5   root      475:             if (ret != n * 512)
1.1       root      476:                 return -1;
                    477:             if (s->crypt_method) {
1.1.1.5   root      478:                 encrypt_sectors(s, sector_num, buf, buf, n, 0,
1.1       root      479:                                 &s->aes_decrypt_key);
                    480:             }
                    481:         }
                    482:         nb_sectors -= n;
                    483:         sector_num += n;
                    484:         buf += n * 512;
                    485:     }
                    486:     return 0;
                    487: }
1.1.1.4   root      488: #endif
1.1       root      489: 
1.1.1.5   root      490: static int qcow_write(BlockDriverState *bs, int64_t sector_num,
1.1       root      491:                      const uint8_t *buf, int nb_sectors)
                    492: {
                    493:     BDRVQcowState *s = bs->opaque;
                    494:     int ret, index_in_cluster, n;
                    495:     uint64_t cluster_offset;
1.1.1.5   root      496: 
1.1       root      497:     while (nb_sectors > 0) {
                    498:         index_in_cluster = sector_num & (s->cluster_sectors - 1);
                    499:         n = s->cluster_sectors - index_in_cluster;
                    500:         if (n > nb_sectors)
                    501:             n = nb_sectors;
1.1.1.5   root      502:         cluster_offset = get_cluster_offset(bs, sector_num << 9, 1, 0,
                    503:                                             index_in_cluster,
1.1       root      504:                                             index_in_cluster + n);
                    505:         if (!cluster_offset)
                    506:             return -1;
                    507:         if (s->crypt_method) {
                    508:             encrypt_sectors(s, sector_num, s->cluster_data, buf, n, 1,
                    509:                             &s->aes_encrypt_key);
1.1.1.5   root      510:             ret = bdrv_pwrite(s->hd, cluster_offset + index_in_cluster * 512,
1.1.1.4   root      511:                               s->cluster_data, n * 512);
1.1       root      512:         } else {
1.1.1.4   root      513:             ret = bdrv_pwrite(s->hd, cluster_offset + index_in_cluster * 512, buf, n * 512);
1.1       root      514:         }
1.1.1.5   root      515:         if (ret != n * 512)
1.1       root      516:             return -1;
                    517:         nb_sectors -= n;
                    518:         sector_num += n;
                    519:         buf += n * 512;
                    520:     }
                    521:     s->cluster_cache_offset = -1; /* disable compressed cache */
                    522:     return 0;
                    523: }
                    524: 
1.1.1.4   root      525: typedef struct QCowAIOCB {
                    526:     BlockDriverAIOCB common;
                    527:     int64_t sector_num;
                    528:     uint8_t *buf;
                    529:     int nb_sectors;
                    530:     int n;
                    531:     uint64_t cluster_offset;
1.1.1.5   root      532:     uint8_t *cluster_data;
1.1.1.4   root      533:     BlockDriverAIOCB *hd_aiocb;
                    534: } QCowAIOCB;
                    535: 
                    536: static void qcow_aio_read_cb(void *opaque, int ret)
                    537: {
                    538:     QCowAIOCB *acb = opaque;
                    539:     BlockDriverState *bs = acb->common.bs;
                    540:     BDRVQcowState *s = bs->opaque;
                    541:     int index_in_cluster;
                    542: 
                    543:     acb->hd_aiocb = NULL;
                    544:     if (ret < 0) {
                    545:     fail:
                    546:         acb->common.cb(acb->common.opaque, ret);
                    547:         qemu_aio_release(acb);
                    548:         return;
                    549:     }
                    550: 
                    551:  redo:
                    552:     /* post process the read buffer */
                    553:     if (!acb->cluster_offset) {
                    554:         /* nothing to do */
                    555:     } else if (acb->cluster_offset & QCOW_OFLAG_COMPRESSED) {
                    556:         /* nothing to do */
                    557:     } else {
                    558:         if (s->crypt_method) {
1.1.1.5   root      559:             encrypt_sectors(s, acb->sector_num, acb->buf, acb->buf,
                    560:                             acb->n, 0,
1.1.1.4   root      561:                             &s->aes_decrypt_key);
                    562:         }
                    563:     }
                    564: 
                    565:     acb->nb_sectors -= acb->n;
                    566:     acb->sector_num += acb->n;
                    567:     acb->buf += acb->n * 512;
                    568: 
                    569:     if (acb->nb_sectors == 0) {
                    570:         /* request completed */
                    571:         acb->common.cb(acb->common.opaque, 0);
                    572:         qemu_aio_release(acb);
                    573:         return;
                    574:     }
1.1.1.5   root      575: 
1.1.1.4   root      576:     /* prepare next AIO request */
1.1.1.5   root      577:     acb->cluster_offset = get_cluster_offset(bs, acb->sector_num << 9,
1.1.1.4   root      578:                                              0, 0, 0, 0);
                    579:     index_in_cluster = acb->sector_num & (s->cluster_sectors - 1);
                    580:     acb->n = s->cluster_sectors - index_in_cluster;
                    581:     if (acb->n > acb->nb_sectors)
                    582:         acb->n = acb->nb_sectors;
                    583: 
                    584:     if (!acb->cluster_offset) {
                    585:         if (bs->backing_hd) {
                    586:             /* read from the base image */
                    587:             acb->hd_aiocb = bdrv_aio_read(bs->backing_hd,
                    588:                 acb->sector_num, acb->buf, acb->n, qcow_aio_read_cb, acb);
                    589:             if (acb->hd_aiocb == NULL)
                    590:                 goto fail;
                    591:         } else {
                    592:             /* Note: in this case, no need to wait */
                    593:             memset(acb->buf, 0, 512 * acb->n);
                    594:             goto redo;
                    595:         }
                    596:     } else if (acb->cluster_offset & QCOW_OFLAG_COMPRESSED) {
                    597:         /* add AIO support for compressed blocks ? */
                    598:         if (decompress_cluster(s, acb->cluster_offset) < 0)
                    599:             goto fail;
1.1.1.5   root      600:         memcpy(acb->buf,
1.1.1.4   root      601:                s->cluster_cache + index_in_cluster * 512, 512 * acb->n);
                    602:         goto redo;
                    603:     } else {
                    604:         if ((acb->cluster_offset & 511) != 0) {
                    605:             ret = -EIO;
                    606:             goto fail;
                    607:         }
                    608:         acb->hd_aiocb = bdrv_aio_read(s->hd,
1.1.1.5   root      609:                             (acb->cluster_offset >> 9) + index_in_cluster,
1.1.1.4   root      610:                             acb->buf, acb->n, qcow_aio_read_cb, acb);
                    611:         if (acb->hd_aiocb == NULL)
                    612:             goto fail;
                    613:     }
                    614: }
                    615: 
                    616: static BlockDriverAIOCB *qcow_aio_read(BlockDriverState *bs,
                    617:         int64_t sector_num, uint8_t *buf, int nb_sectors,
                    618:         BlockDriverCompletionFunc *cb, void *opaque)
                    619: {
                    620:     QCowAIOCB *acb;
                    621: 
                    622:     acb = qemu_aio_get(bs, cb, opaque);
                    623:     if (!acb)
                    624:         return NULL;
                    625:     acb->hd_aiocb = NULL;
                    626:     acb->sector_num = sector_num;
                    627:     acb->buf = buf;
                    628:     acb->nb_sectors = nb_sectors;
                    629:     acb->n = 0;
1.1.1.5   root      630:     acb->cluster_offset = 0;
1.1.1.4   root      631: 
                    632:     qcow_aio_read_cb(acb, 0);
                    633:     return &acb->common;
                    634: }
                    635: 
                    636: static void qcow_aio_write_cb(void *opaque, int ret)
                    637: {
                    638:     QCowAIOCB *acb = opaque;
                    639:     BlockDriverState *bs = acb->common.bs;
                    640:     BDRVQcowState *s = bs->opaque;
                    641:     int index_in_cluster;
                    642:     uint64_t cluster_offset;
                    643:     const uint8_t *src_buf;
                    644: 
                    645:     acb->hd_aiocb = NULL;
                    646: 
                    647:     if (ret < 0) {
                    648:     fail:
                    649:         acb->common.cb(acb->common.opaque, ret);
                    650:         qemu_aio_release(acb);
                    651:         return;
                    652:     }
                    653: 
                    654:     acb->nb_sectors -= acb->n;
                    655:     acb->sector_num += acb->n;
                    656:     acb->buf += acb->n * 512;
                    657: 
                    658:     if (acb->nb_sectors == 0) {
                    659:         /* request completed */
                    660:         acb->common.cb(acb->common.opaque, 0);
                    661:         qemu_aio_release(acb);
                    662:         return;
                    663:     }
1.1.1.5   root      664: 
1.1.1.4   root      665:     index_in_cluster = acb->sector_num & (s->cluster_sectors - 1);
                    666:     acb->n = s->cluster_sectors - index_in_cluster;
                    667:     if (acb->n > acb->nb_sectors)
                    668:         acb->n = acb->nb_sectors;
1.1.1.5   root      669:     cluster_offset = get_cluster_offset(bs, acb->sector_num << 9, 1, 0,
                    670:                                         index_in_cluster,
1.1.1.4   root      671:                                         index_in_cluster + acb->n);
                    672:     if (!cluster_offset || (cluster_offset & 511) != 0) {
                    673:         ret = -EIO;
                    674:         goto fail;
                    675:     }
                    676:     if (s->crypt_method) {
                    677:         if (!acb->cluster_data) {
                    678:             acb->cluster_data = qemu_mallocz(s->cluster_size);
                    679:             if (!acb->cluster_data) {
                    680:                 ret = -ENOMEM;
                    681:                 goto fail;
                    682:             }
                    683:         }
1.1.1.5   root      684:         encrypt_sectors(s, acb->sector_num, acb->cluster_data, acb->buf,
1.1.1.4   root      685:                         acb->n, 1, &s->aes_encrypt_key);
                    686:         src_buf = acb->cluster_data;
                    687:     } else {
                    688:         src_buf = acb->buf;
                    689:     }
                    690:     acb->hd_aiocb = bdrv_aio_write(s->hd,
1.1.1.5   root      691:                                    (cluster_offset >> 9) + index_in_cluster,
                    692:                                    src_buf, acb->n,
1.1.1.4   root      693:                                    qcow_aio_write_cb, acb);
                    694:     if (acb->hd_aiocb == NULL)
                    695:         goto fail;
                    696: }
                    697: 
                    698: static BlockDriverAIOCB *qcow_aio_write(BlockDriverState *bs,
                    699:         int64_t sector_num, const uint8_t *buf, int nb_sectors,
                    700:         BlockDriverCompletionFunc *cb, void *opaque)
                    701: {
                    702:     BDRVQcowState *s = bs->opaque;
                    703:     QCowAIOCB *acb;
1.1.1.5   root      704: 
1.1.1.4   root      705:     s->cluster_cache_offset = -1; /* disable compressed cache */
                    706: 
                    707:     acb = qemu_aio_get(bs, cb, opaque);
                    708:     if (!acb)
                    709:         return NULL;
                    710:     acb->hd_aiocb = NULL;
                    711:     acb->sector_num = sector_num;
                    712:     acb->buf = (uint8_t *)buf;
                    713:     acb->nb_sectors = nb_sectors;
                    714:     acb->n = 0;
1.1.1.5   root      715: 
1.1.1.4   root      716:     qcow_aio_write_cb(acb, 0);
                    717:     return &acb->common;
                    718: }
                    719: 
                    720: static void qcow_aio_cancel(BlockDriverAIOCB *blockacb)
                    721: {
                    722:     QCowAIOCB *acb = (QCowAIOCB *)blockacb;
                    723:     if (acb->hd_aiocb)
                    724:         bdrv_aio_cancel(acb->hd_aiocb);
                    725:     qemu_aio_release(acb);
                    726: }
                    727: 
1.1       root      728: static void qcow_close(BlockDriverState *bs)
                    729: {
                    730:     BDRVQcowState *s = bs->opaque;
                    731:     qemu_free(s->l1_table);
                    732:     qemu_free(s->l2_cache);
                    733:     qemu_free(s->cluster_cache);
                    734:     qemu_free(s->cluster_data);
1.1.1.4   root      735:     bdrv_delete(s->hd);
1.1       root      736: }
                    737: 
                    738: static int qcow_create(const char *filename, int64_t total_size,
                    739:                       const char *backing_file, int flags)
                    740: {
                    741:     int fd, header_size, backing_filename_len, l1_size, i, shift;
                    742:     QCowHeader header;
                    743:     uint64_t tmp;
                    744: 
1.1.1.4   root      745:     fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 0644);
1.1       root      746:     if (fd < 0)
                    747:         return -1;
                    748:     memset(&header, 0, sizeof(header));
                    749:     header.magic = cpu_to_be32(QCOW_MAGIC);
                    750:     header.version = cpu_to_be32(QCOW_VERSION);
                    751:     header.size = cpu_to_be64(total_size * 512);
                    752:     header_size = sizeof(header);
                    753:     backing_filename_len = 0;
                    754:     if (backing_file) {
1.1.1.6 ! root      755:         if (strcmp(backing_file, "fat:")) {
        !           756:             header.backing_file_offset = cpu_to_be64(header_size);
        !           757:             backing_filename_len = strlen(backing_file);
        !           758:             header.backing_file_size = cpu_to_be32(backing_filename_len);
        !           759:             header_size += backing_filename_len;
        !           760:         } else {
        !           761:             /* special backing file for vvfat */
        !           762:             backing_file = NULL;
        !           763:         }
1.1       root      764:         header.cluster_bits = 9; /* 512 byte cluster to avoid copying
                    765:                                     unmodifyed sectors */
                    766:         header.l2_bits = 12; /* 32 KB L2 tables */
                    767:     } else {
                    768:         header.cluster_bits = 12; /* 4 KB clusters */
                    769:         header.l2_bits = 9; /* 4 KB L2 tables */
                    770:     }
                    771:     header_size = (header_size + 7) & ~7;
                    772:     shift = header.cluster_bits + header.l2_bits;
                    773:     l1_size = ((total_size * 512) + (1LL << shift) - 1) >> shift;
                    774: 
                    775:     header.l1_table_offset = cpu_to_be64(header_size);
1.1.1.5   root      776:     if (flags & BLOCK_FLAG_ENCRYPT) {
1.1       root      777:         header.crypt_method = cpu_to_be32(QCOW_CRYPT_AES);
                    778:     } else {
                    779:         header.crypt_method = cpu_to_be32(QCOW_CRYPT_NONE);
                    780:     }
1.1.1.5   root      781: 
1.1       root      782:     /* write all the data */
                    783:     write(fd, &header, sizeof(header));
                    784:     if (backing_file) {
1.1.1.4   root      785:         write(fd, backing_file, backing_filename_len);
1.1       root      786:     }
                    787:     lseek(fd, header_size, SEEK_SET);
                    788:     tmp = 0;
                    789:     for(i = 0;i < l1_size; i++) {
                    790:         write(fd, &tmp, sizeof(tmp));
                    791:     }
                    792:     close(fd);
                    793:     return 0;
                    794: }
                    795: 
1.1.1.4   root      796: static int qcow_make_empty(BlockDriverState *bs)
1.1.1.2   root      797: {
                    798:     BDRVQcowState *s = bs->opaque;
                    799:     uint32_t l1_length = s->l1_size * sizeof(uint64_t);
1.1.1.4   root      800:     int ret;
1.1.1.2   root      801: 
                    802:     memset(s->l1_table, 0, l1_length);
1.1.1.4   root      803:     if (bdrv_pwrite(s->hd, s->l1_table_offset, s->l1_table, l1_length) < 0)
1.1.1.2   root      804:        return -1;
1.1.1.4   root      805:     ret = bdrv_truncate(s->hd, s->l1_table_offset + l1_length);
                    806:     if (ret < 0)
                    807:         return ret;
1.1.1.2   root      808: 
                    809:     memset(s->l2_cache, 0, s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t));
                    810:     memset(s->l2_cache_offsets, 0, L2_CACHE_SIZE * sizeof(uint64_t));
                    811:     memset(s->l2_cache_counts, 0, L2_CACHE_SIZE * sizeof(uint32_t));
                    812: 
                    813:     return 0;
                    814: }
                    815: 
1.1       root      816: /* XXX: put compressed sectors first, then all the cluster aligned
                    817:    tables to avoid losing bytes in alignment */
1.1.1.5   root      818: static int qcow_write_compressed(BlockDriverState *bs, int64_t sector_num,
1.1.1.4   root      819:                                  const uint8_t *buf, int nb_sectors)
1.1       root      820: {
                    821:     BDRVQcowState *s = bs->opaque;
                    822:     z_stream strm;
                    823:     int ret, out_len;
                    824:     uint8_t *out_buf;
                    825:     uint64_t cluster_offset;
                    826: 
1.1.1.4   root      827:     if (nb_sectors != s->cluster_sectors)
                    828:         return -EINVAL;
1.1       root      829: 
                    830:     out_buf = qemu_malloc(s->cluster_size + (s->cluster_size / 1000) + 128);
                    831:     if (!out_buf)
                    832:         return -1;
                    833: 
                    834:     /* best compression, small window, no zlib header */
                    835:     memset(&strm, 0, sizeof(strm));
                    836:     ret = deflateInit2(&strm, Z_DEFAULT_COMPRESSION,
1.1.1.5   root      837:                        Z_DEFLATED, -12,
1.1       root      838:                        9, Z_DEFAULT_STRATEGY);
                    839:     if (ret != 0) {
                    840:         qemu_free(out_buf);
                    841:         return -1;
                    842:     }
                    843: 
                    844:     strm.avail_in = s->cluster_size;
                    845:     strm.next_in = (uint8_t *)buf;
                    846:     strm.avail_out = s->cluster_size;
                    847:     strm.next_out = out_buf;
                    848: 
                    849:     ret = deflate(&strm, Z_FINISH);
                    850:     if (ret != Z_STREAM_END && ret != Z_OK) {
                    851:         qemu_free(out_buf);
                    852:         deflateEnd(&strm);
                    853:         return -1;
                    854:     }
                    855:     out_len = strm.next_out - out_buf;
                    856: 
                    857:     deflateEnd(&strm);
                    858: 
                    859:     if (ret != Z_STREAM_END || out_len >= s->cluster_size) {
                    860:         /* could not compress: write normal cluster */
                    861:         qcow_write(bs, sector_num, buf, s->cluster_sectors);
                    862:     } else {
1.1.1.5   root      863:         cluster_offset = get_cluster_offset(bs, sector_num << 9, 2,
1.1       root      864:                                             out_len, 0, 0);
                    865:         cluster_offset &= s->cluster_offset_mask;
1.1.1.4   root      866:         if (bdrv_pwrite(s->hd, cluster_offset, out_buf, out_len) != out_len) {
1.1       root      867:             qemu_free(out_buf);
                    868:             return -1;
                    869:         }
                    870:     }
1.1.1.5   root      871: 
1.1       root      872:     qemu_free(out_buf);
                    873:     return 0;
                    874: }
                    875: 
1.1.1.3   root      876: static void qcow_flush(BlockDriverState *bs)
                    877: {
                    878:     BDRVQcowState *s = bs->opaque;
1.1.1.4   root      879:     bdrv_flush(s->hd);
                    880: }
                    881: 
                    882: static int qcow_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
                    883: {
                    884:     BDRVQcowState *s = bs->opaque;
                    885:     bdi->cluster_size = s->cluster_size;
                    886:     return 0;
1.1.1.3   root      887: }
                    888: 
1.1       root      889: BlockDriver bdrv_qcow = {
                    890:     "qcow",
                    891:     sizeof(BDRVQcowState),
                    892:     qcow_probe,
                    893:     qcow_open,
1.1.1.4   root      894:     NULL,
                    895:     NULL,
1.1       root      896:     qcow_close,
                    897:     qcow_create,
1.1.1.3   root      898:     qcow_flush,
1.1       root      899:     qcow_is_allocated,
                    900:     qcow_set_key,
1.1.1.4   root      901:     qcow_make_empty,
1.1       root      902: 
1.1.1.4   root      903:     .bdrv_aio_read = qcow_aio_read,
                    904:     .bdrv_aio_write = qcow_aio_write,
                    905:     .bdrv_aio_cancel = qcow_aio_cancel,
                    906:     .aiocb_size = sizeof(QCowAIOCB),
                    907:     .bdrv_write_compressed = qcow_write_compressed,
                    908:     .bdrv_get_info = qcow_get_info,
                    909: };

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