static int qcow_open(BlockDriverState *bs, QDict *options, int flags, Error **errp) { BDRVQcowState *s = bs->opaque; int len, i, shift, ret; QCowHeader header; ret = bdrv_pread(bs->file, 0, &header, sizeof(header)); if (ret < 0) { goto fail; } be32_to_cpus(&header.magic); be32_to_cpus(&header.version); be64_to_cpus(&header.backing_file_offset); be32_to_cpus(&header.backing_file_size); be32_to_cpus(&header.mtime); be64_to_cpus(&header.size); be32_to_cpus(&header.crypt_method); be64_to_cpus(&header.l1_table_offset); if (header.magic != QCOW_MAGIC) { error_setg(errp, "Image not in qcow format"); ret = -EINVAL; goto fail; } if (header.version != QCOW_VERSION) { char version[64]; snprintf(version, sizeof(version), "QCOW version %" PRIu32, header.version); error_set(errp, QERR_UNKNOWN_BLOCK_FORMAT_FEATURE, bs->device_name, "qcow", version); ret = -ENOTSUP; goto fail; } if (header.size <= 1) { error_setg(errp, "Image size is too small (must be at least 2 bytes)"); ret = -EINVAL; goto fail; } if (header.cluster_bits < 9 || header.cluster_bits > 16) { error_setg(errp, "Cluster size must be between 512 and 64k"); ret = -EINVAL; goto fail; } /* l2_bits specifies number of entries; storing a uint64_t in each entry, * so bytes = num_entries << 3. */ if (header.l2_bits < 9 - 3 || header.l2_bits > 16 - 3) { error_setg(errp, "L2 table size must be between 512 and 64k"); ret = -EINVAL; goto fail; } if (header.crypt_method > QCOW_CRYPT_AES) { error_setg(errp, "invalid encryption method in qcow header"); ret = -EINVAL; goto fail; } s->crypt_method_header = header.crypt_method; if (s->crypt_method_header) { bs->encrypted = 1; } s->cluster_bits = header.cluster_bits; s->cluster_size = 1 << s->cluster_bits; s->cluster_sectors = 1 << (s->cluster_bits - 9); s->l2_bits = header.l2_bits; s->l2_size = 1 << s->l2_bits; bs->total_sectors = header.size / 512; s->cluster_offset_mask = (1LL << (63 - s->cluster_bits)) - 1; /* read the level 1 table */ shift = s->cluster_bits + s->l2_bits; if (header.size > UINT64_MAX - (1LL << shift)) { error_setg(errp, "Image too large"); ret = -EINVAL; goto fail; } else { uint64_t l1_size = (header.size + (1LL << shift) - 1) >> shift; if (l1_size > INT_MAX / sizeof(uint64_t)) { error_setg(errp, "Image too large"); ret = -EINVAL; goto fail; } s->l1_size = l1_size; } s->l1_table_offset = header.l1_table_offset; s->l1_table = g_malloc(s->l1_size * sizeof(uint64_t)); ret = bdrv_pread(bs->file, s->l1_table_offset, s->l1_table, s->l1_size * sizeof(uint64_t)); if (ret < 0) { goto fail; } for(i = 0;i < s->l1_size; i++) { be64_to_cpus(&s->l1_table[i]); } /* alloc L2 cache */ s->l2_cache = g_malloc(s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t)); s->cluster_cache = g_malloc(s->cluster_size); s->cluster_data = g_malloc(s->cluster_size); s->cluster_cache_offset = -1; /* read the backing file name */ if (header.backing_file_offset != 0) { len = header.backing_file_size; if (len > 1023) { len = 1023; } ret = bdrv_pread(bs->file, header.backing_file_offset, bs->backing_file, len); if (ret < 0) { goto fail; } bs->backing_file[len] = '\0'; } /* Disable migration when qcow images are used */ error_set(&s->migration_blocker, QERR_BLOCK_FORMAT_FEATURE_NOT_SUPPORTED, "qcow", bs->device_name, "live migration"); migrate_add_blocker(s->migration_blocker); qemu_co_mutex_init(&s->lock); return 0; fail: g_free(s->l1_table); g_free(s->l2_cache); g_free(s->cluster_cache); g_free(s->cluster_data); return ret; }