tar-stream 2.2.0: pack

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify tar-stream.pack in pkg:npm/tar-stream@2.2.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/tar-stream@2.2.0
Demonstrate these symbols/APIs:
  - tar-stream.pack

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:9378eb95a92e632c91e33459e23bdc5269a93f92ec96e223c6206ee95869ad0d","constraints":{"executionContext":"node"},"contract":["tar.pack returns a readable stream that yields 512-byte aligned blocks and terminates with a 1024-byte zero block after finalize","pack.entry buffers string or Buffer payload with custom header metadata and writes padded tar blocks","pack.entry returns a writable sink stream when payload is omitted and finalizes after streaming exactly header.size bytes","pack.entry destroys the pack stream and reports size mismatch when streamed bytes do not match header.size","pack.entry throws an error when called while another entry stream is still actively piping","pack.entry writes directory entries with type directory, default 0755 mode, zero size, and returns a void sink"],"goal":"verify tar-stream.pack in pkg:npm/tar-stream@2.2.0","kind":"HOW","packages":["pkg:npm/tar-stream@2.2.0"],"schemaVersion":1,"symbols":["tar-stream.pack"]},"contractCommand":["node","test/contract.mjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","executionContext":"node","language":"javascript","libc":"glibc","libcVersion":"2.39","moduleSystem":"cjs","os":"linux","osVersionBucket":"24","packageManager":"npm","packageManagerVersion":"10.9.8","runtime":"node","runtimeVersion":"22.23.2","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/tar-stream@2.2.0"],"schemaVersion":1,"subject":"pkg:npm/tar-stream@2.2.0","symbols":["tar-stream.pack"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-tar-stream-pack",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-tar-stream-pack",
      "version": "1.0.0",
      "dependencies": {
        "tar-stream": "2.2.0"
      }
    },
    "node_modules/base64-js": {
      "version": "1.5.1",
      "resolved": "https://registry.npmjs.org/base64-js/-/base64-js-1.5.1.tgz",
      "integrity": "sha512-AKpaYlHn8t4SVbOHCy+b5+KKgvR4vrsD8vbvrbiQJps7fKDTkjkDry6ji0rUJjC0kzbNePLwzxq8iypo41qeWA==",
      "funding": [
        {
          "type": "github",
          "url": "https://github.com/sponsors/feross"
        },
        {
          "type": "patreon",
          "url": "https://www.patreon.com/feross"
        },
        {
          "type": "consulting",
          "url": "https://feross.org/support"
        }
      ],
      "license": "MIT"
    },
    "node_modules/bl": {
      "version": "4.1.0",
      "resolved": "https://registry.npmjs.org/bl/-/bl-4.1.0.tgz",
      "integrity": "sha512-1W07cM9gS6DcLperZfFSj+bWLtaPGSOHWhPiGzXmvVJbRLdG82sH/Kn8EtW1VqWVA54AKf2h5k5BbnIbwF3h6w==",
      "license": "MIT",
      "dependencies": {
        "buffer": "^5.5.0",
        "inherits": "^2.0.4",
        "readable-stream": "^3.4.0"
      }
    },
    "node_modules/buffer": {
      "version": "5.7.1",
      "resolved": "https://registry.npmjs.org/buffer/-/buffer-5.7.1.tgz",
      "integrity": "sha512-EHcyIPBQ4BSGlvjB16k5KgAJ27CIsHY/2JBmCRReo48y9rQ3MaUzWX3KVlBa4U7MyX02HdVj0K7C3WaB3ju7FQ==",
      "funding": [
        {
          "type": "github",
          "url": "https://github.com/sponsors/feross"
        },
        {
          "type": "patreon",
          "url": "https://www.patreon.com/feross"
        },
        {
          "type": "consulting",
          "url": "https://feross.org/support"
        }
      ],
      "license": "MIT",
      "dependencies": {
        "base64-js": "^1.3.1",
        "ieee754": "^1.1.13"
      }
    },
    "node_modules/end-of-stream": {
      "version": "1.4.5",
      "resolved": "https://registry.npmjs.org/end-of-stream/-/end-of-stream-1.4.5.tgz",
      "integrity": "sha512-ooEGc6HP26xXq/N+GCGOT0JKCLDGrq2bQUZrQ7gyrJiZANJ/8YDTxTpQBXGMn+WbIQXNVpyWymm7KYVICQnyOg==",
      "license": "MIT",
      "dependencies": {
        "once": "^1.4.0"
      }
    },
    "node_modules/fs-constants": {
      "version": "1.0.0",
      "resolved": "https://registry.npmjs.org/fs-constants/-/fs-constants-1.0.0.tgz",
      "integrity": "sha512-y6OAwoSIf7FyjMIv94u+b5rdheZEjzR63GTyZJm5qh4Bi+2YgwLCcI/fPFZkL5PSixOt6ZNKm+w+Hfp/Bciwow==",
      "license": "MIT"
    },
    "node_modules/ieee754": {
      "version": "1.2.1",
      "resolved": "https://registry.npmjs.org/ieee754/-/ieee754-1.2.1.tgz",
      "integrity": "sha512-dcyqhDvX1C46lXZcVqCpK+FtMRQVdIMN6/Df5js2zouUsqG7I6sFxitIC+7KYK29KdXOLHdu9zL4sFnoVQnqaA==",
      "funding": [
        {
          "type": "github",
          "url": "https://github.com/sponsors/feross"
        },
        {
          "type": "patreon",
          "url": "https://www.patreon.com/feross"
        },
        {
          "type": "consulting",
          "url": "https://feross.org/support"
        }
      ],
      "license": "BSD-3-Clause"
    },
    "node_modules/inherits": {
      "version": "2.0.4",
      "resolved": "https://registry.npmjs.org/inherits/-/inherits-2.0.4.tgz",
      "integrity": "sha512-k/vGaX4/Yla3WzyMCvTQOXYeIHvqOKtnqBduzTHpzpQZzAskKMhZ2K+EnBiSM9zGSoIFeMpXKxa4dYeZIQqewQ==",
      "license": "ISC"
    },
    "node_modules/once": {
      "version": "1.4.0",
      "resolved": "https://registry.npmjs.org/once/-/once-1.4.0.tgz",
      "integrity": "sha512-lNaJgI+2Q5URQBkccEKHTQOPaXdUxnZZElQTZY0MFUAuaEqe1E+Nyvgdz/aIyNi6Z9MzO5dv1H8n58/GELp3+w==",
      "license": "ISC",
      "dependencies": {
        "wrappy": "1"
      }
    },
    "node_modules/readable-stream": {
      "version": "3.6.2",
      "resolved": "https://registry.npmjs.org/readable-stream/-/readable-stream-3.6.2.tgz",
      "integrity": "sha512-9u/sniCrY3D5WdsERHzHE4G2YCXqoG5FTHUiCC4SIbr6XcLZBY05ya9EKjYek9O5xOAwjGq+1JdGBAS7Q9ScoA==",
      "license": "MIT",
      "dependencies": {
        "inherits": "^2.0.3",
        "string_decoder": "^1.1.1",
        "util-deprecate": "^1.0.1"
      },
      "engines": {
        "node": ">= 6"
      }
    },
    "node_modules/safe-buffer": {
      "version": "5.2.1",
      "resolved": "https://registry.npmjs.org/safe-buffer/-/safe-buffer-5.2.1.tgz",
      "integrity": "sha512-rp3So07KcdmmKbGvgaNxQSJr7bGVSVk5S9Eq1F+ppbRo70+YeaDxkw5Dd8NPN+GD6bjnYm2VuPuCXmpuYvmCXQ==",
      "funding": [
        {
          "type": "github",
          "url": "https://github.com/sponsors/feross"
        },
        {
          "type": "patreon",
          "url": "https://www.patreon.com/feross"
        },
        {
          "type": "consulting",
          "url": "https://feross.org/support"
        }
      ],
      "license": "MIT"
    },
    "node_modules/string_decoder": {
      "version": "1.3.0",
      "resolved": "https://registry.npmjs.org/string_decoder/-/string_decoder-1.3.0.tgz",
      "integrity": "sha512-hkRX8U1WjJFd8LsDJ2yQ/wWWxaopEsABU1XfkM8A+j0+85JAGppt16cr1Whg6KIbb4okU6Mql6BOj+uup/wKeA==",
      "license": "MIT",
      "dependencies": {
        "safe-buffer": "~5.2.0"
      }
    },
    "node_modules/tar-stream": {
      "version": "2.2.0",
      "resolved": "https://registry.npmjs.org/tar-stream/-/tar-stream-2.2.0.tgz",
      "integrity": "sha512-ujeqbceABgwMZxEJnk2HDY2DlnUZ+9oEcb1KzTVfYHio0UE6dG71n60d8D2I4qNvleWrrXpmjpt7vZeF1LnMZQ==",
      "license": "MIT",
      "dependencies": {
        "bl": "^4.0.3",
        "end-of-stream": "^1.4.1",
        "fs-constants": "^1.0.0",
        "inherits": "^2.0.3",
        "readable-stream": "^3.1.1"
      },
      "engines": {
        "node": ">=6"
      }
    },
    "node_modules/util-deprecate": {
      "version": "1.0.2",
      "resolved": "https://registry.npmjs.org/util-deprecate/-/util-deprecate-1.0.2.tgz",
      "integrity": "sha512-EPD5q1uXyFxJpCrLnCc1nHnq3gOa6DZBocAIiI2TaSCA7VCJ1UJDMagCzIkXNsUYfD1daK//LTEQ8xiIbrHtcw==",
      "license": "MIT"
    },
    "node_modules/wrappy": {
      "version": "1.0.2",
      "resolved": "https://registry.npmjs.org/wrappy/-/wrappy-1.0.2.tgz",
      "integrity": "sha512-l4Sp/DRseor9wL6EvV2+TuQn63dMkPjZ/sp9XkghTEbV9KlPS1xUsZ3u7/IQO4wxtcFB4bgpQPRcR3QCvezPcQ==",
      "license": "ISC"
    }
  }
}

{
  "name": "sample-tar-stream-pack",
  "version": "1.0.0",
  "private": true,
  "dependencies": {
    "tar-stream": "2.2.0"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify tar-stream.pack in pkg:npm/tar-stream@2.2.0",
  "kind": "HOW",
  "packages": [
    "pkg:npm/tar-stream@2.2.0"
  ],
  "symbols": [
    "tar-stream.pack"
  ]
}

import assert from 'node:assert/strict';
import { Buffer } from 'node:buffer';
import tar from 'tar-stream';

// 1. tar.pack returns a readable stream that yields 512-byte aligned blocks and terminates with a 1024-byte zero block after finalize
await new Promise((resolve, reject) => {
	const pack = tar.pack();
	const chunks = [];

	pack.on('data', (chunk) => chunks.push(chunk));
	pack.on('end', () => {
		try {
			const tarBuf = Buffer.concat(chunks);
			assert.ok(tarBuf.length >= 1024);
			assert.equal(tarBuf.length % 512, 0);
			const trailer = tarBuf.subarray(tarBuf.length - 1024);
			assert.deepEqual(trailer, Buffer.alloc(1024, 0));
			resolve();
		} catch (err) {
			reject(err);
		}
	});
	pack.on('error', reject);

	pack.finalize();
});

// 2. pack.entry buffers string or Buffer payload with custom header metadata and writes padded tar blocks
await new Promise((resolve, reject) => {
	const pack = tar.pack();
	const chunks = [];

	pack.on('data', (chunk) => chunks.push(chunk));
	pack.on('end', () => {
		try {
			const tarBuf = Buffer.concat(chunks);
			assert.equal(tarBuf.length % 512, 0);

			// Inspect header at offset 0
			const name = tarBuf
				.subarray(0, 100)
				.toString('utf8')
				.replace(/\0.*$/, '');
			assert.equal(name, 'test-file.txt');

			// Check mode, size, and magic
			const sizeOctal = tarBuf
				.subarray(124, 136)
				.toString('utf8')
				.replace(/\0.*$/, '')
				.trim();
			assert.equal(parseInt(sizeOctal, 8), 14);

			const magic = tarBuf.subarray(257, 263).toString('utf8');
			assert.ok(magic.startsWith('ustar'));

			// Check content at offset 512
			const content = tarBuf.subarray(512, 512 + 14).toString('utf8');
			assert.equal(content, 'hello tar pack');

			// Check padding between 512+14 and 1024
			const padding = tarBuf.subarray(512 + 14, 1024);
			assert.deepEqual(padding, Buffer.alloc(512 - 14, 0));

			resolve();
		} catch (err) {
			reject(err);
		}
	});
	pack.on('error', reject);

	pack.entry(
		{ name: 'test-file.txt', mode: 0o644, mtime: new Date(1700000000000) },
		'hello tar pack',
		(err) => {
			if (err) return reject(err);
			pack.finalize();
		},
	);
});

// 3. pack.entry returns a writable sink stream when payload is omitted and finalizes after streaming exactly header.size bytes
await new Promise((resolve, reject) => {
	const pack = tar.pack();
	const chunks = [];

	pack.on('data', (chunk) => chunks.push(chunk));
	pack.on('end', () => {
		try {
			const tarBuf = Buffer.concat(chunks);
			assert.equal(tarBuf.length % 512, 0);

			const name = tarBuf
				.subarray(0, 100)
				.toString('utf8')
				.replace(/\0.*$/, '');
			assert.equal(name, 'streamed.txt');

			const content = tarBuf.subarray(512, 512 + 11).toString('utf8');
			assert.equal(content, 'stream-data');
			resolve();
		} catch (err) {
			reject(err);
		}
	});
	pack.on('error', reject);

	const entryStream = pack.entry({ name: 'streamed.txt', size: 11 }, (err) => {
		if (err) return reject(err);
		pack.finalize();
	});

	assert.equal(typeof entryStream.write, 'function');
	entryStream.write(Buffer.from('stream-'));
	entryStream.end(Buffer.from('data'));
});

// 4. pack.entry destroys the pack stream and reports size mismatch when streamed bytes do not match header.size
await new Promise((resolve, reject) => {
	const pack = tar.pack();

	const entryStream = pack.entry({ name: 'mismatch.txt', size: 20 }, (err) => {
		try {
			assert.ok(err instanceof Error);
			assert.match(err.message, /size mismatch/);
			resolve();
		} catch (e) {
			reject(e);
		}
	});

	// Write only 5 bytes instead of declared 20 bytes
	entryStream.write(Buffer.from('short'));
	entryStream.end();
});

// 5. pack.entry throws an error when called while another entry stream is still actively piping
{
	const pack = tar.pack();
	const stream1 = pack.entry({ name: 'first.txt', size: 10 });
	assert.throws(
		() => {
			pack.entry({ name: 'second.txt', size: 5 });
		},
		{
			name: 'Error',
			message: /already piping an entry/,
		},
	);
	stream1.destroy();
}

// 6. pack.entry writes directory entries with type directory, default 0755 mode, zero size, and returns a void sink
await new Promise((resolve, reject) => {
	const pack = tar.pack();
	const chunks = [];

	pack.on('data', (chunk) => chunks.push(chunk));
	pack.on('end', () => {
		try {
			const tarBuf = Buffer.concat(chunks);
			const name = tarBuf
				.subarray(0, 100)
				.toString('utf8')
				.replace(/\0.*$/, '');
			assert.equal(name, 'some-dir/');

			const modeOctal = tarBuf
				.subarray(100, 108)
				.toString('utf8')
				.replace(/\0.*$/, '')
				.trim();
			assert.equal(parseInt(modeOctal, 8), 0o755);

			const typeflag = String.fromCharCode(tarBuf[156]);
			assert.equal(typeflag, '5'); // '5' is directory in POSIX tar

			const sizeOctal = tarBuf
				.subarray(124, 136)
				.toString('utf8')
				.replace(/\0.*$/, '')
				.trim();
			assert.equal(parseInt(sizeOctal, 8), 0);

			resolve();
		} catch (err) {
			reject(err);
		}
	});
	pack.on('error', reject);

	let voidErrorCaught = false;
	const voidSink = pack.entry({ name: 'some-dir/', type: 'directory' }, (err) => {
		if (err) return reject(err);
		pack.finalize();
	});

	voidSink.on('error', (err) => {
		assert.match(err.message, /No body allowed for this entry/);
		voidErrorCaught = true;
	});

	// Writing to void sink triggers error event
	voidSink.write(Buffer.from('unexpected'));
	assert.equal(voidErrorCaught, true);
});