static int create_dynamic_disk(int fd, uint8_t *buf, int64_t total_sectors) { VHDDynDiskHeader *dyndisk_header = (VHDDynDiskHeader *) buf; size_t block_size, num_bat_entries; int i; int ret = -EIO; // Write the footer (twice: at the beginning and at the end) block_size = 0x200000; num_bat_entries = (total_sectors + block_size / 512) / (block_size / 512); if (write(fd, buf, HEADER_SIZE) != HEADER_SIZE) { goto fail; } if (lseek(fd, 1536 + ((num_bat_entries * 4 + 511) & ~511), SEEK_SET) < 0) { goto fail; } if (write(fd, buf, HEADER_SIZE) != HEADER_SIZE) { goto fail; } // Write the initial BAT if (lseek(fd, 3 * 512, SEEK_SET) < 0) { goto fail; } memset(buf, 0xFF, 512); for (i = 0; i < (num_bat_entries * 4 + 511) / 512; i++) { if (write(fd, buf, 512) != 512) { goto fail; } } // Prepare the Dynamic Disk Header memset(buf, 0, 1024); memcpy(dyndisk_header->magic, "cxsparse", 8); /* * Note: The spec is actually wrong here for data_offset, it says * 0xFFFFFFFF, but MS tools expect all 64 bits to be set. */ dyndisk_header->data_offset = be64_to_cpu(0xFFFFFFFFFFFFFFFFULL); dyndisk_header->table_offset = be64_to_cpu(3 * 512); dyndisk_header->version = be32_to_cpu(0x00010000); dyndisk_header->block_size = be32_to_cpu(block_size); dyndisk_header->max_table_entries = be32_to_cpu(num_bat_entries); dyndisk_header->checksum = be32_to_cpu(vpc_checksum(buf, 1024)); // Write the header if (lseek(fd, 512, SEEK_SET) < 0) { goto fail; } if (write(fd, buf, 1024) != 1024) { goto fail; } ret = 0; fail: return ret; }