Annotation of qemu/block-qcow.c, revision 1.1.1.1

1.1       root        1: /*
                      2:  * Block driver for the QCOW format
                      3:  * 
                      4:  * Copyright (c) 2004 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 "vl.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:     int fd;
                     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)
                     93: {
                     94:     BDRVQcowState *s = bs->opaque;
                     95:     int fd, len, i, shift;
                     96:     QCowHeader header;
                     97:     
                     98:     fd = open(filename, O_RDWR | O_BINARY | O_LARGEFILE);
                     99:     if (fd < 0) {
                    100:         fd = open(filename, O_RDONLY | O_BINARY | O_LARGEFILE);
                    101:         if (fd < 0)
                    102:             return -1;
                    103:     }
                    104:     s->fd = fd;
                    105:     if (read(fd, &header, sizeof(header)) != sizeof(header))
                    106:         goto fail;
                    107:     be32_to_cpus(&header.magic);
                    108:     be32_to_cpus(&header.version);
                    109:     be64_to_cpus(&header.backing_file_offset);
                    110:     be32_to_cpus(&header.backing_file_size);
                    111:     be32_to_cpus(&header.mtime);
                    112:     be64_to_cpus(&header.size);
                    113:     be32_to_cpus(&header.crypt_method);
                    114:     be64_to_cpus(&header.l1_table_offset);
                    115:     
                    116:     if (header.magic != QCOW_MAGIC || header.version != QCOW_VERSION)
                    117:         goto fail;
                    118:     if (header.size <= 1 || header.cluster_bits < 9)
                    119:         goto fail;
                    120:     if (header.crypt_method > QCOW_CRYPT_AES)
                    121:         goto fail;
                    122:     s->crypt_method_header = header.crypt_method;
                    123:     if (s->crypt_method_header)
                    124:         bs->encrypted = 1;
                    125:     s->cluster_bits = header.cluster_bits;
                    126:     s->cluster_size = 1 << s->cluster_bits;
                    127:     s->cluster_sectors = 1 << (s->cluster_bits - 9);
                    128:     s->l2_bits = header.l2_bits;
                    129:     s->l2_size = 1 << s->l2_bits;
                    130:     bs->total_sectors = header.size / 512;
                    131:     s->cluster_offset_mask = (1LL << (63 - s->cluster_bits)) - 1;
                    132: 
                    133:     /* read the level 1 table */
                    134:     shift = s->cluster_bits + s->l2_bits;
                    135:     s->l1_size = (header.size + (1LL << shift) - 1) >> shift;
                    136: 
                    137:     s->l1_table_offset = header.l1_table_offset;
                    138:     s->l1_table = qemu_malloc(s->l1_size * sizeof(uint64_t));
                    139:     if (!s->l1_table)
                    140:         goto fail;
                    141:     lseek(fd, s->l1_table_offset, SEEK_SET);
                    142:     if (read(fd, s->l1_table, s->l1_size * sizeof(uint64_t)) != 
                    143:         s->l1_size * sizeof(uint64_t))
                    144:         goto fail;
                    145:     for(i = 0;i < s->l1_size; i++) {
                    146:         be64_to_cpus(&s->l1_table[i]);
                    147:     }
                    148:     /* alloc L2 cache */
                    149:     s->l2_cache = qemu_malloc(s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t));
                    150:     if (!s->l2_cache)
                    151:         goto fail;
                    152:     s->cluster_cache = qemu_malloc(s->cluster_size);
                    153:     if (!s->cluster_cache)
                    154:         goto fail;
                    155:     s->cluster_data = qemu_malloc(s->cluster_size);
                    156:     if (!s->cluster_data)
                    157:         goto fail;
                    158:     s->cluster_cache_offset = -1;
                    159:     
                    160:     /* read the backing file name */
                    161:     if (header.backing_file_offset != 0) {
                    162:         len = header.backing_file_size;
                    163:         if (len > 1023)
                    164:             len = 1023;
                    165:         lseek(fd, header.backing_file_offset, SEEK_SET);
                    166:         if (read(fd, bs->backing_file, len) != len)
                    167:             goto fail;
                    168:         bs->backing_file[len] = '\0';
                    169:     }
                    170:     return 0;
                    171: 
                    172:  fail:
                    173:     qemu_free(s->l1_table);
                    174:     qemu_free(s->l2_cache);
                    175:     qemu_free(s->cluster_cache);
                    176:     qemu_free(s->cluster_data);
                    177:     close(fd);
                    178:     return -1;
                    179: }
                    180: 
                    181: static int qcow_set_key(BlockDriverState *bs, const char *key)
                    182: {
                    183:     BDRVQcowState *s = bs->opaque;
                    184:     uint8_t keybuf[16];
                    185:     int len, i;
                    186:     
                    187:     memset(keybuf, 0, 16);
                    188:     len = strlen(key);
                    189:     if (len > 16)
                    190:         len = 16;
                    191:     /* XXX: we could compress the chars to 7 bits to increase
                    192:        entropy */
                    193:     for(i = 0;i < len;i++) {
                    194:         keybuf[i] = key[i];
                    195:     }
                    196:     s->crypt_method = s->crypt_method_header;
                    197: 
                    198:     if (AES_set_encrypt_key(keybuf, 128, &s->aes_encrypt_key) != 0)
                    199:         return -1;
                    200:     if (AES_set_decrypt_key(keybuf, 128, &s->aes_decrypt_key) != 0)
                    201:         return -1;
                    202: #if 0
                    203:     /* test */
                    204:     {
                    205:         uint8_t in[16];
                    206:         uint8_t out[16];
                    207:         uint8_t tmp[16];
                    208:         for(i=0;i<16;i++)
                    209:             in[i] = i;
                    210:         AES_encrypt(in, tmp, &s->aes_encrypt_key);
                    211:         AES_decrypt(tmp, out, &s->aes_decrypt_key);
                    212:         for(i = 0; i < 16; i++)
                    213:             printf(" %02x", tmp[i]);
                    214:         printf("\n");
                    215:         for(i = 0; i < 16; i++)
                    216:             printf(" %02x", out[i]);
                    217:         printf("\n");
                    218:     }
                    219: #endif
                    220:     return 0;
                    221: }
                    222: 
                    223: /* The crypt function is compatible with the linux cryptoloop
                    224:    algorithm for < 4 GB images. NOTE: out_buf == in_buf is
                    225:    supported */
                    226: static void encrypt_sectors(BDRVQcowState *s, int64_t sector_num,
                    227:                             uint8_t *out_buf, const uint8_t *in_buf,
                    228:                             int nb_sectors, int enc,
                    229:                             const AES_KEY *key)
                    230: {
                    231:     union {
                    232:         uint64_t ll[2];
                    233:         uint8_t b[16];
                    234:     } ivec;
                    235:     int i;
                    236: 
                    237:     for(i = 0; i < nb_sectors; i++) {
                    238:         ivec.ll[0] = cpu_to_le64(sector_num);
                    239:         ivec.ll[1] = 0;
                    240:         AES_cbc_encrypt(in_buf, out_buf, 512, key, 
                    241:                         ivec.b, enc);
                    242:         sector_num++;
                    243:         in_buf += 512;
                    244:         out_buf += 512;
                    245:     }
                    246: }
                    247: 
                    248: /* 'allocate' is:
                    249:  *
                    250:  * 0 to not allocate.
                    251:  *
                    252:  * 1 to allocate a normal cluster (for sector indexes 'n_start' to
                    253:  * 'n_end')
                    254:  *
                    255:  * 2 to allocate a compressed cluster of size
                    256:  * 'compressed_size'. 'compressed_size' must be > 0 and <
                    257:  * cluster_size 
                    258:  *
                    259:  * return 0 if not allocated.
                    260:  */
                    261: static uint64_t get_cluster_offset(BlockDriverState *bs,
                    262:                                    uint64_t offset, int allocate,
                    263:                                    int compressed_size,
                    264:                                    int n_start, int n_end)
                    265: {
                    266:     BDRVQcowState *s = bs->opaque;
                    267:     int min_index, i, j, l1_index, l2_index;
                    268:     uint64_t l2_offset, *l2_table, cluster_offset, tmp;
                    269:     uint32_t min_count;
                    270:     int new_l2_table;
                    271:     
                    272:     l1_index = offset >> (s->l2_bits + s->cluster_bits);
                    273:     l2_offset = s->l1_table[l1_index];
                    274:     new_l2_table = 0;
                    275:     if (!l2_offset) {
                    276:         if (!allocate)
                    277:             return 0;
                    278:         /* allocate a new l2 entry */
                    279:         l2_offset = lseek(s->fd, 0, SEEK_END);
                    280:         /* round to cluster size */
                    281:         l2_offset = (l2_offset + s->cluster_size - 1) & ~(s->cluster_size - 1);
                    282:         /* update the L1 entry */
                    283:         s->l1_table[l1_index] = l2_offset;
                    284:         tmp = cpu_to_be64(l2_offset);
                    285:         lseek(s->fd, s->l1_table_offset + l1_index * sizeof(tmp), SEEK_SET);
                    286:         if (write(s->fd, &tmp, sizeof(tmp)) != sizeof(tmp))
                    287:             return 0;
                    288:         new_l2_table = 1;
                    289:     }
                    290:     for(i = 0; i < L2_CACHE_SIZE; i++) {
                    291:         if (l2_offset == s->l2_cache_offsets[i]) {
                    292:             /* increment the hit count */
                    293:             if (++s->l2_cache_counts[i] == 0xffffffff) {
                    294:                 for(j = 0; j < L2_CACHE_SIZE; j++) {
                    295:                     s->l2_cache_counts[j] >>= 1;
                    296:                 }
                    297:             }
                    298:             l2_table = s->l2_cache + (i << s->l2_bits);
                    299:             goto found;
                    300:         }
                    301:     }
                    302:     /* not found: load a new entry in the least used one */
                    303:     min_index = 0;
                    304:     min_count = 0xffffffff;
                    305:     for(i = 0; i < L2_CACHE_SIZE; i++) {
                    306:         if (s->l2_cache_counts[i] < min_count) {
                    307:             min_count = s->l2_cache_counts[i];
                    308:             min_index = i;
                    309:         }
                    310:     }
                    311:     l2_table = s->l2_cache + (min_index << s->l2_bits);
                    312:     lseek(s->fd, l2_offset, SEEK_SET);
                    313:     if (new_l2_table) {
                    314:         memset(l2_table, 0, s->l2_size * sizeof(uint64_t));
                    315:         if (write(s->fd, l2_table, s->l2_size * sizeof(uint64_t)) !=
                    316:             s->l2_size * sizeof(uint64_t))
                    317:             return 0;
                    318:     } else {
                    319:         if (read(s->fd, l2_table, s->l2_size * sizeof(uint64_t)) != 
                    320:             s->l2_size * sizeof(uint64_t))
                    321:             return 0;
                    322:     }
                    323:     s->l2_cache_offsets[min_index] = l2_offset;
                    324:     s->l2_cache_counts[min_index] = 1;
                    325:  found:
                    326:     l2_index = (offset >> s->cluster_bits) & (s->l2_size - 1);
                    327:     cluster_offset = be64_to_cpu(l2_table[l2_index]);
                    328:     if (!cluster_offset || 
                    329:         ((cluster_offset & QCOW_OFLAG_COMPRESSED) && allocate == 1)) {
                    330:         if (!allocate)
                    331:             return 0;
                    332:         /* allocate a new cluster */
                    333:         if ((cluster_offset & QCOW_OFLAG_COMPRESSED) &&
                    334:             (n_end - n_start) < s->cluster_sectors) {
                    335:             /* if the cluster is already compressed, we must
                    336:                decompress it in the case it is not completely
                    337:                overwritten */
                    338:             if (decompress_cluster(s, cluster_offset) < 0)
                    339:                 return 0;
                    340:             cluster_offset = lseek(s->fd, 0, SEEK_END);
                    341:             cluster_offset = (cluster_offset + s->cluster_size - 1) & 
                    342:                 ~(s->cluster_size - 1);
                    343:             /* write the cluster content */
                    344:             lseek(s->fd, cluster_offset, SEEK_SET);
                    345:             if (write(s->fd, s->cluster_cache, s->cluster_size) != 
                    346:                 s->cluster_size)
                    347:                 return -1;
                    348:         } else {
                    349:             cluster_offset = lseek(s->fd, 0, SEEK_END);
                    350:             if (allocate == 1) {
                    351:                 /* round to cluster size */
                    352:                 cluster_offset = (cluster_offset + s->cluster_size - 1) & 
                    353:                     ~(s->cluster_size - 1);
                    354:                 ftruncate(s->fd, cluster_offset + s->cluster_size);
                    355:                 /* if encrypted, we must initialize the cluster
                    356:                    content which won't be written */
                    357:                 if (s->crypt_method && 
                    358:                     (n_end - n_start) < s->cluster_sectors) {
                    359:                     uint64_t start_sect;
                    360:                     start_sect = (offset & ~(s->cluster_size - 1)) >> 9;
                    361:                     memset(s->cluster_data + 512, 0xaa, 512);
                    362:                     for(i = 0; i < s->cluster_sectors; i++) {
                    363:                         if (i < n_start || i >= n_end) {
                    364:                             encrypt_sectors(s, start_sect + i, 
                    365:                                             s->cluster_data, 
                    366:                                             s->cluster_data + 512, 1, 1,
                    367:                                             &s->aes_encrypt_key);
                    368:                             lseek(s->fd, cluster_offset + i * 512, SEEK_SET);
                    369:                             if (write(s->fd, s->cluster_data, 512) != 512)
                    370:                                 return -1;
                    371:                         }
                    372:                     }
                    373:                 }
                    374:             } else {
                    375:                 cluster_offset |= QCOW_OFLAG_COMPRESSED | 
                    376:                     (uint64_t)compressed_size << (63 - s->cluster_bits);
                    377:             }
                    378:         }
                    379:         /* update L2 table */
                    380:         tmp = cpu_to_be64(cluster_offset);
                    381:         l2_table[l2_index] = tmp;
                    382:         lseek(s->fd, l2_offset + l2_index * sizeof(tmp), SEEK_SET);
                    383:         if (write(s->fd, &tmp, sizeof(tmp)) != sizeof(tmp))
                    384:             return 0;
                    385:     }
                    386:     return cluster_offset;
                    387: }
                    388: 
                    389: static int qcow_is_allocated(BlockDriverState *bs, int64_t sector_num, 
                    390:                              int nb_sectors, int *pnum)
                    391: {
                    392:     BDRVQcowState *s = bs->opaque;
                    393:     int index_in_cluster, n;
                    394:     uint64_t cluster_offset;
                    395: 
                    396:     cluster_offset = get_cluster_offset(bs, sector_num << 9, 0, 0, 0, 0);
                    397:     index_in_cluster = sector_num & (s->cluster_sectors - 1);
                    398:     n = s->cluster_sectors - index_in_cluster;
                    399:     if (n > nb_sectors)
                    400:         n = nb_sectors;
                    401:     *pnum = n;
                    402:     return (cluster_offset != 0);
                    403: }
                    404: 
                    405: static int decompress_buffer(uint8_t *out_buf, int out_buf_size,
                    406:                              const uint8_t *buf, int buf_size)
                    407: {
                    408:     z_stream strm1, *strm = &strm1;
                    409:     int ret, out_len;
                    410: 
                    411:     memset(strm, 0, sizeof(*strm));
                    412: 
                    413:     strm->next_in = (uint8_t *)buf;
                    414:     strm->avail_in = buf_size;
                    415:     strm->next_out = out_buf;
                    416:     strm->avail_out = out_buf_size;
                    417: 
                    418:     ret = inflateInit2(strm, -12);
                    419:     if (ret != Z_OK)
                    420:         return -1;
                    421:     ret = inflate(strm, Z_FINISH);
                    422:     out_len = strm->next_out - out_buf;
                    423:     if ((ret != Z_STREAM_END && ret != Z_BUF_ERROR) ||
                    424:         out_len != out_buf_size) {
                    425:         inflateEnd(strm);
                    426:         return -1;
                    427:     }
                    428:     inflateEnd(strm);
                    429:     return 0;
                    430: }
                    431:                               
                    432: static int decompress_cluster(BDRVQcowState *s, uint64_t cluster_offset)
                    433: {
                    434:     int ret, csize;
                    435:     uint64_t coffset;
                    436: 
                    437:     coffset = cluster_offset & s->cluster_offset_mask;
                    438:     if (s->cluster_cache_offset != coffset) {
                    439:         csize = cluster_offset >> (63 - s->cluster_bits);
                    440:         csize &= (s->cluster_size - 1);
                    441:         lseek(s->fd, coffset, SEEK_SET);
                    442:         ret = read(s->fd, s->cluster_data, csize);
                    443:         if (ret != csize) 
                    444:             return -1;
                    445:         if (decompress_buffer(s->cluster_cache, s->cluster_size,
                    446:                               s->cluster_data, csize) < 0) {
                    447:             return -1;
                    448:         }
                    449:         s->cluster_cache_offset = coffset;
                    450:     }
                    451:     return 0;
                    452: }
                    453: 
                    454: static int qcow_read(BlockDriverState *bs, int64_t sector_num, 
                    455:                      uint8_t *buf, int nb_sectors)
                    456: {
                    457:     BDRVQcowState *s = bs->opaque;
                    458:     int ret, index_in_cluster, n;
                    459:     uint64_t cluster_offset;
                    460:     
                    461:     while (nb_sectors > 0) {
                    462:         cluster_offset = get_cluster_offset(bs, sector_num << 9, 0, 0, 0, 0);
                    463:         index_in_cluster = sector_num & (s->cluster_sectors - 1);
                    464:         n = s->cluster_sectors - index_in_cluster;
                    465:         if (n > nb_sectors)
                    466:             n = nb_sectors;
                    467:         if (!cluster_offset) {
                    468:             memset(buf, 0, 512 * n);
                    469:         } else if (cluster_offset & QCOW_OFLAG_COMPRESSED) {
                    470:             if (decompress_cluster(s, cluster_offset) < 0)
                    471:                 return -1;
                    472:             memcpy(buf, s->cluster_cache + index_in_cluster * 512, 512 * n);
                    473:         } else {
                    474:             lseek(s->fd, cluster_offset + index_in_cluster * 512, SEEK_SET);
                    475:             ret = read(s->fd, buf, n * 512);
                    476:             if (ret != n * 512) 
                    477:                 return -1;
                    478:             if (s->crypt_method) {
                    479:                 encrypt_sectors(s, sector_num, buf, buf, n, 0, 
                    480:                                 &s->aes_decrypt_key);
                    481:             }
                    482:         }
                    483:         nb_sectors -= n;
                    484:         sector_num += n;
                    485:         buf += n * 512;
                    486:     }
                    487:     return 0;
                    488: }
                    489: 
                    490: static int qcow_write(BlockDriverState *bs, int64_t sector_num, 
                    491:                      const uint8_t *buf, int nb_sectors)
                    492: {
                    493:     BDRVQcowState *s = bs->opaque;
                    494:     int ret, index_in_cluster, n;
                    495:     uint64_t cluster_offset;
                    496:     
                    497:     while (nb_sectors > 0) {
                    498:         index_in_cluster = sector_num & (s->cluster_sectors - 1);
                    499:         n = s->cluster_sectors - index_in_cluster;
                    500:         if (n > nb_sectors)
                    501:             n = nb_sectors;
                    502:         cluster_offset = get_cluster_offset(bs, sector_num << 9, 1, 0, 
                    503:                                             index_in_cluster, 
                    504:                                             index_in_cluster + n);
                    505:         if (!cluster_offset)
                    506:             return -1;
                    507:         lseek(s->fd, cluster_offset + index_in_cluster * 512, SEEK_SET);
                    508:         if (s->crypt_method) {
                    509:             encrypt_sectors(s, sector_num, s->cluster_data, buf, n, 1,
                    510:                             &s->aes_encrypt_key);
                    511:             ret = write(s->fd, s->cluster_data, n * 512);
                    512:         } else {
                    513:             ret = write(s->fd, buf, n * 512);
                    514:         }
                    515:         if (ret != n * 512) 
                    516:             return -1;
                    517:         nb_sectors -= n;
                    518:         sector_num += n;
                    519:         buf += n * 512;
                    520:     }
                    521:     s->cluster_cache_offset = -1; /* disable compressed cache */
                    522:     return 0;
                    523: }
                    524: 
                    525: static void qcow_close(BlockDriverState *bs)
                    526: {
                    527:     BDRVQcowState *s = bs->opaque;
                    528:     qemu_free(s->l1_table);
                    529:     qemu_free(s->l2_cache);
                    530:     qemu_free(s->cluster_cache);
                    531:     qemu_free(s->cluster_data);
                    532:     close(s->fd);
                    533: }
                    534: 
                    535: static int qcow_create(const char *filename, int64_t total_size,
                    536:                       const char *backing_file, int flags)
                    537: {
                    538:     int fd, header_size, backing_filename_len, l1_size, i, shift;
                    539:     QCowHeader header;
                    540:     char backing_filename[1024];
                    541:     uint64_t tmp;
                    542:     struct stat st;
                    543: 
                    544:     fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY | O_LARGEFILE, 
                    545:               0644);
                    546:     if (fd < 0)
                    547:         return -1;
                    548:     memset(&header, 0, sizeof(header));
                    549:     header.magic = cpu_to_be32(QCOW_MAGIC);
                    550:     header.version = cpu_to_be32(QCOW_VERSION);
                    551:     header.size = cpu_to_be64(total_size * 512);
                    552:     header_size = sizeof(header);
                    553:     backing_filename_len = 0;
                    554:     if (backing_file) {
                    555:         const char *p;
                    556:         /* XXX: this is a hack: we do not attempt to check for URL
                    557:            like syntax */
                    558:         p = strchr(backing_file, ':');
                    559:         if (p && (p - backing_file) >= 2) {
                    560:             /* URL like but exclude "c:" like filenames */
                    561:             pstrcpy(backing_filename, sizeof(backing_filename),
                    562:                     backing_file);
                    563:         } else {
                    564:             realpath(backing_file, backing_filename);
                    565:             if (stat(backing_filename, &st) != 0) {
                    566:                 return -1;
                    567:             }
                    568:         }
                    569:         header.mtime = cpu_to_be32(st.st_mtime);
                    570:         header.backing_file_offset = cpu_to_be64(header_size);
                    571:         backing_filename_len = strlen(backing_filename);
                    572:         header.backing_file_size = cpu_to_be32(backing_filename_len);
                    573:         header_size += backing_filename_len;
                    574:         header.cluster_bits = 9; /* 512 byte cluster to avoid copying
                    575:                                     unmodifyed sectors */
                    576:         header.l2_bits = 12; /* 32 KB L2 tables */
                    577:     } else {
                    578:         header.cluster_bits = 12; /* 4 KB clusters */
                    579:         header.l2_bits = 9; /* 4 KB L2 tables */
                    580:     }
                    581:     header_size = (header_size + 7) & ~7;
                    582:     shift = header.cluster_bits + header.l2_bits;
                    583:     l1_size = ((total_size * 512) + (1LL << shift) - 1) >> shift;
                    584: 
                    585:     header.l1_table_offset = cpu_to_be64(header_size);
                    586:     if (flags) {
                    587:         header.crypt_method = cpu_to_be32(QCOW_CRYPT_AES);
                    588:     } else {
                    589:         header.crypt_method = cpu_to_be32(QCOW_CRYPT_NONE);
                    590:     }
                    591:     
                    592:     /* write all the data */
                    593:     write(fd, &header, sizeof(header));
                    594:     if (backing_file) {
                    595:         write(fd, backing_filename, backing_filename_len);
                    596:     }
                    597:     lseek(fd, header_size, SEEK_SET);
                    598:     tmp = 0;
                    599:     for(i = 0;i < l1_size; i++) {
                    600:         write(fd, &tmp, sizeof(tmp));
                    601:     }
                    602:     close(fd);
                    603:     return 0;
                    604: }
                    605: 
                    606: int qcow_get_cluster_size(BlockDriverState *bs)
                    607: {
                    608:     BDRVQcowState *s = bs->opaque;
                    609:     if (bs->drv != &bdrv_qcow)
                    610:         return -1;
                    611:     return s->cluster_size;
                    612: }
                    613: 
                    614: /* XXX: put compressed sectors first, then all the cluster aligned
                    615:    tables to avoid losing bytes in alignment */
                    616: int qcow_compress_cluster(BlockDriverState *bs, int64_t sector_num, 
                    617:                           const uint8_t *buf)
                    618: {
                    619:     BDRVQcowState *s = bs->opaque;
                    620:     z_stream strm;
                    621:     int ret, out_len;
                    622:     uint8_t *out_buf;
                    623:     uint64_t cluster_offset;
                    624: 
                    625:     if (bs->drv != &bdrv_qcow)
                    626:         return -1;
                    627: 
                    628:     out_buf = qemu_malloc(s->cluster_size + (s->cluster_size / 1000) + 128);
                    629:     if (!out_buf)
                    630:         return -1;
                    631: 
                    632:     /* best compression, small window, no zlib header */
                    633:     memset(&strm, 0, sizeof(strm));
                    634:     ret = deflateInit2(&strm, Z_DEFAULT_COMPRESSION,
                    635:                        Z_DEFLATED, -12, 
                    636:                        9, Z_DEFAULT_STRATEGY);
                    637:     if (ret != 0) {
                    638:         qemu_free(out_buf);
                    639:         return -1;
                    640:     }
                    641: 
                    642:     strm.avail_in = s->cluster_size;
                    643:     strm.next_in = (uint8_t *)buf;
                    644:     strm.avail_out = s->cluster_size;
                    645:     strm.next_out = out_buf;
                    646: 
                    647:     ret = deflate(&strm, Z_FINISH);
                    648:     if (ret != Z_STREAM_END && ret != Z_OK) {
                    649:         qemu_free(out_buf);
                    650:         deflateEnd(&strm);
                    651:         return -1;
                    652:     }
                    653:     out_len = strm.next_out - out_buf;
                    654: 
                    655:     deflateEnd(&strm);
                    656: 
                    657:     if (ret != Z_STREAM_END || out_len >= s->cluster_size) {
                    658:         /* could not compress: write normal cluster */
                    659:         qcow_write(bs, sector_num, buf, s->cluster_sectors);
                    660:     } else {
                    661:         cluster_offset = get_cluster_offset(bs, sector_num << 9, 2, 
                    662:                                             out_len, 0, 0);
                    663:         cluster_offset &= s->cluster_offset_mask;
                    664:         lseek(s->fd, cluster_offset, SEEK_SET);
                    665:         if (write(s->fd, out_buf, out_len) != out_len) {
                    666:             qemu_free(out_buf);
                    667:             return -1;
                    668:         }
                    669:     }
                    670:     
                    671:     qemu_free(out_buf);
                    672:     return 0;
                    673: }
                    674: 
                    675: BlockDriver bdrv_qcow = {
                    676:     "qcow",
                    677:     sizeof(BDRVQcowState),
                    678:     qcow_probe,
                    679:     qcow_open,
                    680:     qcow_read,
                    681:     qcow_write,
                    682:     qcow_close,
                    683:     qcow_create,
                    684:     qcow_is_allocated,
                    685:     qcow_set_key,
                    686: };
                    687: 
                    688: 

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