pe-library 0.4.1: calculateCheckSumForPE

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 pe-library.calculateCheckSumForPE in pkg:npm/pe-library@0.4.1
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/pe-library@0.4.1
Demonstrate these symbols/APIs:
  - pe-library.calculateCheckSumForPE

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:a7449a6625565861819f230bd6c68db61609cfd813964d5cfbf01cff831707ba","contract":["calculateCheckSumForPE computes a positive integer checksum from PE image binary ArrayBuffer","calculateCheckSumForPE updates the PE Optional Header checksum field in-place when storeToBinary is true","calculateCheckSumForPE produces an identical checksum value on re-calculation after in-place storage","calculateCheckSumForPE accurately calculates checksums for both 64-bit and 32-bit PE binaries","calculateCheckSumForPE throws an error when given a binary buffer insufficient to hold PE headers"],"goal":"verify pe-library.calculateCheckSumForPE in pkg:npm/pe-library@0.4.1","kind":"HOW","packages":["pkg:npm/pe-library@0.4.1"],"schemaVersion":1,"symbols":["pe-library.calculateCheckSumForPE"]},"contractCommand":["node","test/contract.mjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"npm","packageManagerVersion":"10.9.8","runtime":"node","runtimeVersion":"22.23.2","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/pe-library@0.4.1"],"schemaVersion":1,"subject":"pkg:npm/pe-library@0.4.1","symbols":["pe-library.calculateCheckSumForPE"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-pe-library-calculatechecksumforpe",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-pe-library-calculatechecksumforpe",
      "version": "1.0.0",
      "dependencies": {
        "pe-library": "0.4.1"
      }
    },
    "node_modules/pe-library": {
      "version": "0.4.1",
      "resolved": "https://registry.npmjs.org/pe-library/-/pe-library-0.4.1.tgz",
      "integrity": "sha512-eRWB5LBz7PpDu4PUlwT0PhnQfTQJlDDdPa35urV4Osrm0t0AqQFGn+UIkU3klZvwJ8KPO3VbBFsXquA6p6kqZw==",
      "license": "MIT",
      "engines": {
        "node": ">=12",
        "npm": ">=6"
      },
      "funding": {
        "type": "github",
        "url": "https://github.com/sponsors/jet2jet"
      }
    }
  }
}

{
  "name": "sample-pe-library-calculatechecksumforpe",
  "version": "1.0.0",
  "private": true,
  "type": "module",
  "dependencies": {
    "pe-library": "0.4.1"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify pe-library.calculateCheckSumForPE in pkg:npm/pe-library@0.4.1",
  "kind": "HOW",
  "packages": [
    "pkg:npm/pe-library@0.4.1"
  ],
  "symbols": [
    "pe-library.calculateCheckSumForPE"
  ]
}

import assert from 'node:assert/strict';
import { NtExecutable, calculateCheckSumForPE } from 'pe-library';

// 1. calculateCheckSumForPE computes a positive integer checksum from PE image binary ArrayBuffer
const exe64 = NtExecutable.createEmpty(false, true);
const bin64 = exe64.generate();
assert.ok(bin64 instanceof ArrayBuffer, 'generate should return an ArrayBuffer');
const sum64 = calculateCheckSumForPE(bin64, false);
assert.equal(typeof sum64, 'number', 'checksum must be a number');
assert.ok(Number.isInteger(sum64), 'checksum must be an integer');
assert.ok(sum64 > 0, 'checksum must be positive');

// 2. calculateCheckSumForPE updates the PE Optional Header checksum field in-place when storeToBinary is true
const checkSumOffset64 = exe64.dosHeader.newHeaderAddress + 88;
const viewBefore = new DataView(bin64);
assert.equal(viewBefore.getUint32(checkSumOffset64, true), 0, 'initial checksum in binary should be 0');

const storedSum = calculateCheckSumForPE(bin64, true);
assert.equal(storedSum, sum64, 'returned checksum when storing should match calculated checksum');
const viewAfter = new DataView(bin64);
assert.equal(viewAfter.getUint32(checkSumOffset64, true), sum64, 'stored checksum in binary must match returned checksum');

// 3. calculateCheckSumForPE produces an identical checksum value on re-calculation after in-place storage
const sumAfterStore = calculateCheckSumForPE(bin64, false);
assert.equal(sumAfterStore, sum64, 'checksum re-calculated after storeToBinary must match original checksum');

// 4. calculateCheckSumForPE accurately calculates checksums for both 64-bit and 32-bit PE binaries
const exe32 = NtExecutable.createEmpty(true, false);
assert.equal(exe32.is32bit(), true, 'executable should be 32-bit');
const bin32 = exe32.generate();
const sum32 = calculateCheckSumForPE(bin32, true);
assert.equal(typeof sum32, 'number', '32-bit checksum must be a number');
assert.ok(sum32 > 0, '32-bit checksum must be positive');
const checkSumOffset32 = exe32.dosHeader.newHeaderAddress + 88;
const view32 = new DataView(bin32);
assert.equal(view32.getUint32(checkSumOffset32, true), sum32, 'stored 32-bit checksum must match returned checksum');

// 5. calculateCheckSumForPE throws an error when given a binary buffer insufficient to hold PE headers
assert.throws(
  () => {
    calculateCheckSumForPE(new ArrayBuffer(16));
  },
  {
    name: 'RangeError'
  },
  'should throw RangeError for buffer too small to contain PE header'
);

console.log('pe-library.calculateCheckSumForPE contract test passed.');