# @balena/udif 中文文档

规范地址：https://npmcn.com/package/%40balena/udif/

版本：1\.1\.2
npm 元数据更新时间：2026-01-20T12:09:13.769Z
中文译文更新时间：2026-11-07T15:44:06.986Z
软件包许可：MIT

本文由上游 README 翻译，可能存在偏差，请结合原文核对 API、命令与配置。版权与许可归原作者所有。

原始 npm 页面：https://www.npmjs.com/package/%40balena/udif
原文对照：https://npmcn.com/package/%40balena/udif/?lang=original
项目主页：https://github.com/balena-io-modules/node-udif
源码仓库：https://github.com/balena-io-modules/node-udif

## 关键信息（来自 npm 元数据）

- 包体积（解压后）：83 kB，41 个文件
- 模块格式：CommonJS
- TypeScript 类型：未声明
- 运行依赖：4 个
- 首次发布：2020-07-24T06:53:56.493Z
- 最新版本发布：2021-10-07T13:55:26.701Z
- 近 30 天下载量：10577（2026-10-08 至 2026-11-06，npm 官方下载统计）
- 已发布版本数：19（近 12 个月 0 个）

## 中文简介

苹果通用磁盘图像格式(UDIF/DMG)

## 安装

```sh
npm install @balena/udif
```

也可以使用：`pnpm add @balena/udif`、`yarn add @balena/udif`、`bun add @balena/udif`

## README

# 苹果通用磁盘图像格式(UDIF/DMG)

## 通过 [无](https://npmjs.com/)

```sh
$ npm install --save @balena/udif
```

## 用于

-   **[伊彻](https://github.com/balena-io/etcher)** 支持 Apple 磁盘图像格式 (.dmg)

## 使用量

```typescript
import * as UDIF from '@balena/udif';
```

### 打开 .dmg 图像

```typescript
await UDIF.withOpenImage('path/to/image.dmg', async (image) => {
    // ...
});
```

### 确定未压缩大小

注意图像必须打开来确定未压缩大小, 因为它是从资源分叉读取的.

```typescript
return await UDIF.withOpenImage('path/to/image.dmg', async (image) => {
    return await image.getUncompressedSize();
});
```

### 创建可读流

```typescript
await UDIF.withOpenImage('path/to/image.dmg', async (image) => {
    const readableStream = await image.createReadStream();
});
```

### 提取原始磁盘图像

提取未压缩的原始磁盘图像 `.dmg` 文件变得与以下文件一样容易:

```typescript
import * as UDIF from '@balena/udif';
import { pipeline } from 'stream';
import { promisify } from 'util';

const pipelineAsync = promisify(pipeline);

await UDIF.withOpenImage('path/to/image.dmg', async (image) => {
    await pipelineAsync(
        await image.createReadStream(),
        fs.createWriteStream('/path/to/destination.img'),
    );
});
```

### 分层流

```typescript
await UDIF.withOpenImage('path/to/image.dmg', async (image) => {
    const sparseStream = await image.createSparseReadStream();
});
```

Sparse 读取流在 `objectMode` 将射出形状的物体 `{ buffer, position }`。 。 。 . 这表示你需要一个写字的溪流 同时在 `objectMode` 并知道如何处理这些. 为了简洁起见,以下例子仅表明将块属性传递给 `fs.write()`· ;

```typescript
sparseStream.on('data', (chunk) => {
    fs.writeSync(fd, chunk.buffer, 0, chunk.buffer.length, chunk.position);
})
```

### 使用自定义文件系统

```typescript
import * as UDIF from '@balena/udif';
import * as fs from 'fs';

const fd = fs.openSync('path/to/image.dmg', 'r');
const size = fs.fstatSync(fd).size;

const dmg = new UDIF.Image({
    size,
    createReadStream: async (start: number, end: number) => {
        return fs.createReadStream('', { fd, start, end, autoClose: false });
    },
})
await dmg.ready;

// ...

fs.closeSync(fd);
```

### 检查UDIF页脚

页脚( aka "Koly Block" ) 中包含指向 XML 元数据, 数据分叉和资源分叉以及校验和.

```typescript
await UDIF.withOpenImage('path/to/image.dmg', async (image) => {
    console.log(image.footer)
});
```

```typescript
KolyBlock {
  signature: 1802464377,
  version: 4,
  headerSize: 512,
  flags: 1,
  runningDataForkOffset: 0,
  dataForkOffset: 0,
  dataForkLength: 6585140266,
  resourceForkOffset: 0,
  resourceForkLength: 0,
  segmentNumber: 1,
  segmentCount: 1,
  segmentId: <Buffer 18 66 9e 31 fa 6 d 4 f 7 d aa d0 f2 50 12 8 f 49 54>,
  dataChecksum: Checksum { type: 2, bits: 32, value: 'c2208200' },
  xmlOffset: 6585140266,
  xmlLength: 1752206,
  reserved1: <Buffer 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ...>,
  checksum: Checksum { type: 2, bits: 32, value: '3f40bb47' },
  imageVariant: 1,
  sectorCount: 15178432,
  reserved2: 0,
  reserved3: 0,
  reserved4: 0,
}
```

### 检查 XML 元数据

XML 数据为 [属性列表](https://en.wikipedia.org/wiki/Property_list),(或列表),其中包含块图 `resource-fork.blkx`。 。 。 .

```typescript
await UDIF.withOpenImage('path/to/image.dmg', async (image) => {
    console.log(image.resourceFork)
});
```

```typescript
{
  blkx: [{
    id: -1,
    attributes: 80,
    name: 'Driver Descriptor Map (DDM : 0)',
    coreFoundationName: 'Driver Descriptor Map (DDM : 0)',
    map: BlockMap {
      signature: 1835627368,
      version: 1,
      sectorNumber: 0,
      sectorCount: 1,
      dataOffset: 0,
      buffersNeeded: 520,
      blockDescriptorCount: 0,
      reserved1: 0,
      reserved2: 0,
      reserved3: 0,
      reserved4: 0,
      reserved5: 0,
      reserved6: 0,
      checksum: Checksum { type: 2, bits: 32, value: '698a85ed' },
      blockCount: 2,
      blocks: [
        Block {
          type: 2147483653,
          description: 'UDZO (zlib-compressed)',
          comment: '',
          sectorNumber: 0,
          sectorCount: 1,
          compressedOffset: 0,
          compressedLength: 22
        },
        Block {
          type: 4294967295,
          description: 'TERMINATOR',
          comment: '',
          sectorNumber: 1,
          sectorCount: 0,
          compressedOffset: 22,
          compressedLength: 0
        }
      ]
    }
  }, {
    id: 0,
    attributes: 80,
    name: 'WINDOWSSUPPORT (Apple_ISO : 1)',
    coreFoundationName: 'WINDOWSSUPPORT (Apple_ISO : 1)',
    map: BlockMap {
      signature: 1835627368,
      version: 1,
      sectorNumber: 1,
      sectorCount: 3,
      dataOffset: 0,
      buffersNeeded: 520,
      blockDescriptorCount: 1,
      reserved1: 0,
      reserved2: 0,
      reserved3: 0,
      reserved4: 0,
      reserved5: 0,
      reserved6: 0,
      checksum: Checksum { type: 2, bits: 32, value: '6c1ce17e' },
      blockCount: 2,
      blocks: [
        Block {
          type: 2147483653,
          description: 'UDZO (zlib-compressed)',
          comment: '',
          sectorNumber: 0,
          sectorCount: 3,
          compressedOffset: 22,
          compressedLength: 24
        },
        Block {
          type: 4294967295,
          description: 'TERMINATOR',
          comment: '',
          sectorNumber: 3,
          sectorCount: 0,
          compressedOffset: 46,
          compressedLength: 0
        }
      ]
    }
  }, {
    id: 1,
    attributes: 80,
    name: 'Apple (Apple_partition_map : 2)',
    coreFoundationName: 'Apple (Apple_partition_map : 2)',
    map: BlockMap {
      signature: 1835627368,
      version: 1,
      sectorNumber: 4,
      sectorCount: 60,
      dataOffset: 0,
      buffersNeeded: 520,
      blockDescriptorCount: 2,
      reserved1: 0,
      reserved2: 0,
      reserved3: 0,
      reserved4: 0,
      reserved5: 0,
      reserved6: 0,
      checksum: Checksum { type: 2, bits: 32, value: '115fc68e' },
      blockCount: 2,
      blocks: [
        Block {
          type: 2147483653,
          description: 'UDZO (zlib-compressed)',
          comment: '',
          sectorNumber: 0,
          sectorCount: 60,
          compressedOffset: 46,
          compressedLength: 358
        },
        Block {
          type: 4294967295,
          description: 'TERMINATOR',
          comment: '',
          sectorNumber: 60,
          sectorCount: 0,
          compressedOffset: 404,
          compressedLength: 0
        }
      ]
    }
  }, {
    id: 2,
    attributes: 80,
    name: 'Macintosh (Apple_Driver_ATAPI : 3)',
    coreFoundationName: 'Macintosh (Apple_Driver_ATAPI : 3)',
    map: BlockMap {
      signature: 1835627368,
      version: 1,
      sectorNumber: 64,
      sectorCount: 2020420,
      dataOffset: 0,
      buffersNeeded: 520,
      blockDescriptorCount: 3,
      reserved1: 0,
      reserved2: 0,
      reserved3: 0,
      reserved4: 0,
      reserved5: 0,
      reserved6: 0,
      checksum: Checksum { type: 2, bits: 32, value: 'b2bb86f8' },
      blockCount: 3948,
      blocks: [
        Block {
          type: 2147483653,
          description: 'UDZO (zlib-compressed)',
          comment: '',
          sectorNumber: 0,
          sectorCount: 512,
          compressedOffset: 404,
          compressedLength: 25147
        },
        Block {
          type: 2147483653,
          description: 'UDZO (zlib-compressed)',
          comment: '',
          sectorNumber: 512,
          sectorCount: 512,
          compressedOffset: 25551,
          compressedLength: 29149
        },
        ... more items
      ]
    }
  }, {
    id: 3,
    attributes: 80,
    name: ' (Apple_Free : 4)',
    coreFoundationName: ' (Apple_Free : 4)',
    map: BlockMap {
      signature: 1835627368,
      version: 1,
      sectorNumber: 2020484,
      sectorCount: 4,
      dataOffset: 0,
      buffersNeeded: 0,
      blockDescriptorCount: 4,
      reserved1: 0,
      reserved2: 0,
      reserved3: 0,
      reserved4: 0,
      reserved5: 0,
      reserved6: 0,
      checksum: Checksum { type: 2, bits: 32, value: '00000000' },
      blockCount: 2,
      blocks: [
        Block {
          type: 2,
          description: 'FREE (unallocated)',
          comment: '',
          sectorNumber: 0,
          sectorCount: 4,
          compressedOffset: 984141554,
          compressedLength: 0
        },
        Block {
          type: 4294967295,
          description: 'TERMINATOR',
          comment: '',
          sectorNumber: 4,
          sectorCount: 0,
          compressedOffset: 984141554,
          compressedLength: 0
        }
      ]
    }
  }, {
    id: 4,
    attributes: 80,
    name: 'Mac_OS_X (Apple_HFS : 5)',
    coreFoundationName: 'Mac_OS_X (Apple_HFS : 5)',
    map: BlockMap {
      signature: 1835627368,
      version: 1,
      sectorNumber: 2020488,
      sectorCount: 13157944,
      dataOffset: 0,
      buffersNeeded: 520,
      blockDescriptorCount: 5,
      reserved1: 0,
      reserved2: 0,
      reserved3: 0,
      reserved4: 0,
      reserved5: 0,
      reserved6: 0,
      checksum: Checksum { type: 2, bits: 32, value: '39ce04b6' },
      blockCount: 25387,
      blocks: [
        Block {
          type: 2147483646,
          description: 'COMMENT',
          comment: '+beg',
          sectorNumber: 0,
          sectorCount: 0,
          compressedOffset: 984141554,
          compressedLength: 0
        },
        Block {
          type: 2147483653,
          description: 'UDZO (zlib-compressed)',
          comment: '',
          sectorNumber: 0,
          sectorCount: 512,
          compressedOffset: 984141554,
          compressedLength: 1812
        },
        ... more items
      ]
    }
  }],
  cSum: [{
    Attributes: '0x0000',
    Data: <Buffer 01 00 02 00 00 00 00 00 00 00>,
    ID: '0',
    Name: null
  }, {
    Attributes: '0x0000',
    Data: <Buffer 01 00 02 00 00 00 10 fc a8 3f>,
    ID: '1',
    Name: null
  }, {
    Attributes: '0x0000',
    Data: <Buffer 01 00 02 00 00 00 10 37 71 ef>,
    ID: '2',
    Name: null
  }],
  nsiz: [{
    Attributes: '0x0000',
    Data: <Buffer 3 c 3 f 78 6 d 6 c 20 76 65 72 73 69 6 f 6e 3 d 22 31 2e 30 22 20 65 6e 63 6 f 64 69 6e 67 3 d 22 55 54 46 2 d 38 22 3 f 3e 0 a 3 c 21 44 4 f 43 54 59 50 45 20 70 ...>,
    ID: '0',
    Name: null
  }, {
    Attributes: '0x0000',
    Data: <Buffer 3 c 3 f 78 6 d 6 c 20 76 65 72 73 69 6 f 6e 3 d 22 31 2e 30 22 20 65 6e 63 6 f 64 69 6e 67 3 d 22 55 54 46 2 d 38 22 3 f 3e 0 a 3 c 21 44 4 f 43 54 59 50 45 20 70 ...>,
    ID: '1',
    Name: null
  }, {
    Attributes: '0x0000',
    Data: <Buffer 3 c 3 f 78 6 d 6 c 20 76 65 72 73 69 6 f 6e 3 d 22 31 2e 30 22 20 65 6e 63 6 f 64 69 6e 67 3 d 22 55 54 46 2 d 38 22 3 f 3e 0 a 3 c 21 44 4 f 43 54 59 50 45 20 70 ...>,
    ID: '2',
    Name: null
  }],
  plst: [{
    Attributes: '0x0050',
    Data: <Buffer 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ...>,
    ID: '0',
    Name: null
  }],
  size: [{
    Attributes: '0x0000',
    Data: <Buffer 05 00 01 00 00 00 00 60 8 c 91 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ...>,
    ID: '2',
    Name: null
  }]
}

```

## 参考资料

-   [解密 DMG 文件格式](http://newosxbook.com/DMG.html)
-   [VBox/Storage/DMG.cpp (英语)](https://www.virtualbox.org/svn/vbox/trunk/src/VBox/Storage/DMG.cpp)
-   [man1/hdiutil. 1 (中文(简体) )](https://www.unix.com/man-page/osx/1/hdiutil/)
-   [维基百科/苹果 磁盘 图像](https://en.wikipedia.org/wiki/Apple_Disk_Image)

## 常见问题

### @balena/udif 是什么？

苹果通用磁盘图像格式\(UDIF/DMG\)

### 如何安装 @balena/udif？

在项目目录运行 npm install @balena/udif，或使用 pnpm add / yarn add / bun add。

### @balena/udif 支持 TypeScript 吗？

该包的 package\.json 没有声明类型入口。需要类型提示时，可以在 npm 上查找社区维护的 @types/balena\_\_udif 是否存在。

### @balena/udif 支持 ESM 还是 CommonJS？

以 CommonJS 形式发布，可以直接 require\(\)；在 ES Module 项目中也可以用 import 引入（Node\.js 会把 module\.exports 作为默认导出）。

### @balena/udif 可以商用吗？

@balena/udif 使用 MIT 许可。宽松许可：允许商业使用、修改和再分发，通常只需在分发时保留原版权与许可声明。以上为概括，不构成法律意见，请以许可原文为准。

### @balena/udif 的下载量有多少？

根据 npm 官方下载统计，@balena/udif 在 2026/10/08 – 2026/11/06 这 30 天内被下载 10,577 次，日均约 353 次。下载量会把 CI 构建、镜像同步和作为其他包依赖的安装一并计入，适合横向比较热度，不能直接等同于使用人数。

### @balena/udif 还在维护吗？

最新版本 1\.1\.2 发布于 2021/10/07（5 年前）；至今共发布 19 个版本，其中过去 12 个月发布了 0 个；首次发布于 2020/07/24。发布频率只是参考信号：功能稳定的工具可能很少需要更新，建议结合源码仓库的 issue 和提交记录判断。