static int vmdk_snapshot_create(const char *filename, const char *backing_file) { int snp_fd, p_fd; int ret; uint32_t p_cid; char *p_name, *gd_buf, *rgd_buf; const char *real_filename, *temp_str; VMDK4Header header; uint32_t gde_entries, gd_size; int64_t gd_offset, rgd_offset, capacity, gt_size; char p_desc[DESC_SIZE], s_desc[DESC_SIZE], hdr[HEADER_SIZE]; static const char desc_template[] = "# Disk DescriptorFile\n" "version=1\n" "CID=%x\n" "parentCID=%x\n" "createType=\"monolithicSparse\"\n" "parentFileNameHint=\"%s\"\n" "\n" "# Extent description\n" "RW %u SPARSE \"%s\"\n" "\n" "# The Disk Data Base \n" "#DDB\n" "\n"; snp_fd = open(filename, O_RDWR | O_CREAT | O_TRUNC | O_BINARY | O_LARGEFILE, 0644); if (snp_fd < 0) return -errno; p_fd = open(backing_file, O_RDONLY | O_BINARY | O_LARGEFILE); if (p_fd < 0) { close(snp_fd); return -errno; } /* read the header */ if (lseek(p_fd, 0x0, SEEK_SET) == -1) { ret = -errno; goto fail; } if (read(p_fd, hdr, HEADER_SIZE) != HEADER_SIZE) { ret = -errno; goto fail; } /* write the header */ if (lseek(snp_fd, 0x0, SEEK_SET) == -1) { ret = -errno; goto fail; } if (write(snp_fd, hdr, HEADER_SIZE) == -1) { ret = -errno; goto fail; } memset(&header, 0, sizeof(header)); memcpy(&header,&hdr[4], sizeof(header)); // skip the VMDK4_MAGIC if (ftruncate(snp_fd, header.grain_offset << 9)) { ret = -errno; goto fail; } /* the descriptor offset = 0x200 */ if (lseek(p_fd, 0x200, SEEK_SET) == -1) { ret = -errno; goto fail; } if (read(p_fd, p_desc, DESC_SIZE) != DESC_SIZE) { ret = -errno; goto fail; } if ((p_name = strstr(p_desc,"CID")) != NULL) { p_name += sizeof("CID"); sscanf(p_name,"%x",&p_cid); } real_filename = filename; if ((temp_str = strrchr(real_filename, '\\')) != NULL) real_filename = temp_str + 1; if ((temp_str = strrchr(real_filename, '/')) != NULL) real_filename = temp_str + 1; if ((temp_str = strrchr(real_filename, ':')) != NULL) real_filename = temp_str + 1; snprintf(s_desc, sizeof(s_desc), desc_template, p_cid, p_cid, backing_file, (uint32_t)header.capacity, real_filename); /* write the descriptor */ if (lseek(snp_fd, 0x200, SEEK_SET) == -1) { ret = -errno; goto fail; } if (write(snp_fd, s_desc, strlen(s_desc)) == -1) { ret = -errno; goto fail; } gd_offset = header.gd_offset * SECTOR_SIZE; // offset of GD table rgd_offset = header.rgd_offset * SECTOR_SIZE; // offset of RGD table capacity = header.capacity * SECTOR_SIZE; // Extent size /* * Each GDE span 32M disk, means: * 512 GTE per GT, each GTE points to grain */ gt_size = (int64_t)header.num_gtes_per_gte * header.granularity * SECTOR_SIZE; if (!gt_size) { ret = -EINVAL; goto fail; } gde_entries = (uint32_t)(capacity / gt_size); // number of gde/rgde gd_size = gde_entries * sizeof(uint32_t); /* write RGD */ rgd_buf = qemu_malloc(gd_size); if (lseek(p_fd, rgd_offset, SEEK_SET) == -1) { ret = -errno; goto fail_rgd; } if (read(p_fd, rgd_buf, gd_size) != gd_size) { ret = -errno; goto fail_rgd; } if (lseek(snp_fd, rgd_offset, SEEK_SET) == -1) { ret = -errno; goto fail_rgd; } if (write(snp_fd, rgd_buf, gd_size) == -1) { ret = -errno; goto fail_rgd; } qemu_free(rgd_buf); /* write GD */ gd_buf = qemu_malloc(gd_size); if (lseek(p_fd, gd_offset, SEEK_SET) == -1) { ret = -errno; goto fail_gd; } if (read(p_fd, gd_buf, gd_size) != gd_size) { ret = -errno; goto fail_gd; } if (lseek(snp_fd, gd_offset, SEEK_SET) == -1) { ret = -errno; goto fail_gd; } if (write(snp_fd, gd_buf, gd_size) == -1) { ret = -errno; goto fail_gd; } qemu_free(gd_buf); close(p_fd); close(snp_fd); return 0; fail_gd: qemu_free(gd_buf); fail_rgd: qemu_free(rgd_buf); fail: close(p_fd); close(snp_fd); return ret; }