static int qcow2_open(BlockDriverState *bs, QDict *options, int flags, Error **errp) { BDRVQcowState *s = bs->opaque; int len, i, ret = 0; QCowHeader header; QemuOpts *opts; Error *local_err = NULL; uint64_t ext_end; uint64_t l1_vm_state_index; const char *opt_overlap_check; int overlap_check_template = 0; ret = bdrv_pread(bs->file, 0, &header, sizeof(header)); if (ret < 0) { error_setg_errno(errp, -ret, "Could not read qcow2 header"); 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); be64_to_cpus(&header.size); be32_to_cpus(&header.cluster_bits); be32_to_cpus(&header.crypt_method); be64_to_cpus(&header.l1_table_offset); be32_to_cpus(&header.l1_size); be64_to_cpus(&header.refcount_table_offset); be32_to_cpus(&header.refcount_table_clusters); be64_to_cpus(&header.snapshots_offset); be32_to_cpus(&header.nb_snapshots); if (header.magic != QCOW_MAGIC) { error_setg(errp, "Image is not in qcow2 format"); ret = -EINVAL; goto fail; } if (header.version < 2 || header.version > 3) { report_unsupported(bs, errp, "QCOW version %d", header.version); ret = -ENOTSUP; goto fail; } s->qcow_version = header.version; /* Initialise version 3 header fields */ if (header.version == 2) { header.incompatible_features = 0; header.compatible_features = 0; header.autoclear_features = 0; header.refcount_order = 4; header.header_length = 72; } else { be64_to_cpus(&header.incompatible_features); be64_to_cpus(&header.compatible_features); be64_to_cpus(&header.autoclear_features); be32_to_cpus(&header.refcount_order); be32_to_cpus(&header.header_length); } if (header.header_length > sizeof(header)) { s->unknown_header_fields_size = header.header_length - sizeof(header); s->unknown_header_fields = g_malloc(s->unknown_header_fields_size); ret = bdrv_pread(bs->file, sizeof(header), s->unknown_header_fields, s->unknown_header_fields_size); if (ret < 0) { error_setg_errno(errp, -ret, "Could not read unknown qcow2 header " "fields"); goto fail; } } if (header.backing_file_offset) { ext_end = header.backing_file_offset; } else { ext_end = 1 << header.cluster_bits; } /* Handle feature bits */ s->incompatible_features = header.incompatible_features; s->compatible_features = header.compatible_features; s->autoclear_features = header.autoclear_features; if (s->incompatible_features & ~QCOW2_INCOMPAT_MASK) { void *feature_table = NULL; qcow2_read_extensions(bs, header.header_length, ext_end, &feature_table, NULL); report_unsupported_feature(bs, errp, feature_table, s->incompatible_features & ~QCOW2_INCOMPAT_MASK); ret = -ENOTSUP; g_free(feature_table); goto fail; } if (s->incompatible_features & QCOW2_INCOMPAT_CORRUPT) { /* Corrupt images may not be written to unless they are being repaired */ if ((flags & BDRV_O_RDWR) && !(flags & BDRV_O_CHECK)) { error_setg(errp, "qcow2: Image is corrupt; cannot be opened " "read/write"); ret = -EACCES; goto fail; } } /* Check support for various header values */ if (header.refcount_order != 4) { report_unsupported(bs, errp, "%d bit reference counts", 1 << header.refcount_order); ret = -ENOTSUP; goto fail; } s->refcount_order = header.refcount_order; if (header.cluster_bits < MIN_CLUSTER_BITS || header.cluster_bits > MAX_CLUSTER_BITS) { error_setg(errp, "Unsupported cluster size: 2^%i", header.cluster_bits); ret = -EINVAL; goto fail; } if (header.crypt_method > QCOW_CRYPT_AES) { error_setg(errp, "Unsupported encryption method: %i", header.crypt_method); 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 = s->cluster_bits - 3; /* L2 is always one cluster */ s->l2_size = 1 << s->l2_bits; bs->total_sectors = header.size / 512; s->csize_shift = (62 - (s->cluster_bits - 8)); s->csize_mask = (1 << (s->cluster_bits - 8)) - 1; s->cluster_offset_mask = (1LL << s->csize_shift) - 1; s->refcount_table_offset = header.refcount_table_offset; s->refcount_table_size = header.refcount_table_clusters << (s->cluster_bits - 3); s->snapshots_offset = header.snapshots_offset; s->nb_snapshots = header.nb_snapshots; /* read the level 1 table */ s->l1_size = header.l1_size; l1_vm_state_index = size_to_l1(s, header.size); if (l1_vm_state_index > INT_MAX) { error_setg(errp, "Image is too big"); ret = -EFBIG; goto fail; } s->l1_vm_state_index = l1_vm_state_index; /* the L1 table must contain at least enough entries to put header.size bytes */ if (s->l1_size < s->l1_vm_state_index) { error_setg(errp, "L1 table is too small"); ret = -EINVAL; goto fail; } s->l1_table_offset = header.l1_table_offset; if (s->l1_size > 0) { s->l1_table = g_malloc0( align_offset(s->l1_size * sizeof(uint64_t), 512)); ret = bdrv_pread(bs->file, s->l1_table_offset, s->l1_table, s->l1_size * sizeof(uint64_t)); if (ret < 0) { error_setg_errno(errp, -ret, "Could not read L1 table"); goto fail; } for(i = 0;i < s->l1_size; i++) { be64_to_cpus(&s->l1_table[i]); } } /* alloc L2 table/refcount block cache */ s->l2_table_cache = qcow2_cache_create(bs, L2_CACHE_SIZE); s->refcount_block_cache = qcow2_cache_create(bs, REFCOUNT_CACHE_SIZE); s->cluster_cache = g_malloc(s->cluster_size); /* one more sector for decompressed data alignment */ s->cluster_data = qemu_blockalign(bs, QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size + 512); s->cluster_cache_offset = -1; s->flags = flags; ret = qcow2_refcount_init(bs); if (ret != 0) { error_setg_errno(errp, -ret, "Could not initialize refcount handling"); goto fail; } QLIST_INIT(&s->cluster_allocs); QTAILQ_INIT(&s->discards); /* read qcow2 extensions */ if (qcow2_read_extensions(bs, header.header_length, ext_end, NULL, &local_err)) { error_propagate(errp, local_err); ret = -EINVAL; goto fail; } /* 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) { error_setg_errno(errp, -ret, "Could not read backing file name"); goto fail; } bs->backing_file[len] = '\0'; } ret = qcow2_read_snapshots(bs); if (ret < 0) { error_setg_errno(errp, -ret, "Could not read snapshots"); goto fail; } /* Clear unknown autoclear feature bits */ if (!bs->read_only && !(flags & BDRV_O_INCOMING) && s->autoclear_features) { s->autoclear_features = 0; ret = qcow2_update_header(bs); if (ret < 0) { error_setg_errno(errp, -ret, "Could not update qcow2 header"); goto fail; } } /* Initialise locks */ qemu_co_mutex_init(&s->lock); /* Repair image if dirty */ if (!(flags & (BDRV_O_CHECK | BDRV_O_INCOMING)) && !bs->read_only && (s->incompatible_features & QCOW2_INCOMPAT_DIRTY)) { BdrvCheckResult result = {0}; ret = qcow2_check(bs, &result, BDRV_FIX_ERRORS); if (ret < 0) { error_setg_errno(errp, -ret, "Could not repair dirty image"); goto fail; } } /* Enable lazy_refcounts according to image and command line options */ opts = qemu_opts_create(&qcow2_runtime_opts, NULL, 0, &error_abort); qemu_opts_absorb_qdict(opts, options, &local_err); if (local_err) { error_propagate(errp, local_err); ret = -EINVAL; goto fail; } s->use_lazy_refcounts = qemu_opt_get_bool(opts, QCOW2_OPT_LAZY_REFCOUNTS, (s->compatible_features & QCOW2_COMPAT_LAZY_REFCOUNTS)); s->discard_passthrough[QCOW2_DISCARD_NEVER] = false; s->discard_passthrough[QCOW2_DISCARD_ALWAYS] = true; s->discard_passthrough[QCOW2_DISCARD_REQUEST] = qemu_opt_get_bool(opts, QCOW2_OPT_DISCARD_REQUEST, flags & BDRV_O_UNMAP); s->discard_passthrough[QCOW2_DISCARD_SNAPSHOT] = qemu_opt_get_bool(opts, QCOW2_OPT_DISCARD_SNAPSHOT, true); s->discard_passthrough[QCOW2_DISCARD_OTHER] = qemu_opt_get_bool(opts, QCOW2_OPT_DISCARD_OTHER, false); opt_overlap_check = qemu_opt_get(opts, "overlap-check") ?: "cached"; if (!strcmp(opt_overlap_check, "none")) { overlap_check_template = 0; } else if (!strcmp(opt_overlap_check, "constant")) { overlap_check_template = QCOW2_OL_CONSTANT; } else if (!strcmp(opt_overlap_check, "cached")) { overlap_check_template = QCOW2_OL_CACHED; } else if (!strcmp(opt_overlap_check, "all")) { overlap_check_template = QCOW2_OL_ALL; } else { error_setg(errp, "Unsupported value '%s' for qcow2 option " "'overlap-check'. Allowed are either of the following: " "none, constant, cached, all", opt_overlap_check); qemu_opts_del(opts); ret = -EINVAL; goto fail; } s->overlap_check = 0; for (i = 0; i < QCOW2_OL_MAX_BITNR; i++) { /* overlap-check defines a template bitmask, but every flag may be * overwritten through the associated boolean option */ s->overlap_check |= qemu_opt_get_bool(opts, overlap_bool_option_names[i], overlap_check_template & (1 << i)) << i; } qemu_opts_del(opts); if (s->use_lazy_refcounts && s->qcow_version < 3) { error_setg(errp, "Lazy refcounts require a qcow2 image with at least " "qemu 1.1 compatibility level"); ret = -EINVAL; goto fail; } #ifdef DEBUG_ALLOC { BdrvCheckResult result = {0}; qcow2_check_refcounts(bs, &result, 0); } #endif return ret; fail: g_free(s->unknown_header_fields); cleanup_unknown_header_ext(bs); qcow2_free_snapshots(bs); qcow2_refcount_close(bs); g_free(s->l1_table); /* else pre-write overlap checks in cache_destroy may crash */ s->l1_table = NULL; if (s->l2_table_cache) { qcow2_cache_destroy(bs, s->l2_table_cache); } if (s->refcount_block_cache) { qcow2_cache_destroy(bs, s->refcount_block_cache); } g_free(s->cluster_cache); qemu_vfree(s->cluster_data); return ret; }