Merge pull request #291 from mat1jaczyyy/feature/compose-sourcemaps

Compose sourcemaps

Author: z0ffy

package.json

@@ -51,13 +51,16 @@
     "version": "auto-changelog"
   },
   "dependencies": {
+    "@jridgewell/remapping": "^2.3.5",
     "javascript-obfuscator": "^4.1.1"
   },
   "devDependencies": {
     "@commitlint/cli": "^19.8.1",
     "@commitlint/config-conventional": "^19.8.1",
     "@commitlint/types": "^19.8.1",
     "@eslint/js": "^9.32.0",
+    "@jridgewell/sourcemap-codec": "^1.5.5",
+    "@jridgewell/trace-mapping": "^0.3.31",
     "@stylistic/eslint-plugin": "^5.2.2",
     "@types/node": "^24.2.0",
     "@vitest/coverage-v8": "^3.2.4",
@@ -88,4 +91,4 @@
       "esbuild"
     ]
   }
-}
+}

pnpm-lock.yaml

@@ -8,6 +8,7 @@ import {
   getThreadPoolSize, 
   getValidBundleList, 
   Log, 
+  composeSourcemaps,
   isEnabledFeature, 
   isEnableThreadPool, 
   isEnableAutoExcludesNodeModules, 
@@ -19,6 +20,8 @@ import {
 import {BundleList, Config} from "../type";
 import {isArray, isFunction, isFileNameExcluded} from '../utils/is';
 import { Worker } from 'node:worker_threads';
+import { encode } from '@jridgewell/sourcemap-codec';
+import { TraceMap, originalPositionFor, sourceContentFor } from '@jridgewell/trace-mapping';
 
 // Mock WORKER_FILE_PATH
 vi.stubGlobal('WORKER_FILE_PATH', './worker.js');
@@ -237,6 +240,58 @@ describe('getChunkName', () => {
   });
 });
 
+describe('composeSourcemaps', () => {
+  it('should compose maps and preserve the original source content', () => {
+    const originalSource = 'const message = "hi";\nconsole.log(message);\n';
+    const intermediateSource = 'const message="hi";\nconsole.log(message);\n';
+
+    const bundlerMap: Rollup.SourceMapInput = {
+      version: 3,
+      file: 'bundle.js',
+      sources: ['original.ts'],
+      sourcesContent: [originalSource],
+      names: [],
+      mappings: encode([
+        [[0, 0, 0, 0]],
+        [[0, 0, 1, 0]],
+      ]),
+    };
+
+    const obfuscatorMap: Rollup.SourceMapInput = {
+      version: 3,
+      file: 'bundle-obf.js',
+      sources: ['bundle.js'],
+      sourcesContent: [intermediateSource],
+      names: [],
+      mappings: encode([
+        [[0, 0, 0, 0]],
+        [[0, 0, 1, 0]],
+      ]),
+    };
+
+    const logSpy = vi.fn();
+
+    const composed = composeSourcemaps(bundlerMap, obfuscatorMap, logSpy);
+
+    expect(logSpy).toHaveBeenCalledWith('composing source maps...');
+    expect(composed).not.toBeNull();
+
+    const trace = new TraceMap(composed as any);
+
+    const firstLine = originalPositionFor(trace, { line: 1, column: 0 });
+    expect(firstLine.source).toBe('original.ts');
+    expect(firstLine.line).toBe(1);
+    expect(firstLine.column).toBe(0);
+
+    const secondLine = originalPositionFor(trace, { line: 2, column: 0 });
+    expect(secondLine.source).toBe('original.ts');
+    expect(secondLine.line).toBe(2);
+
+    const recoveredSource = sourceContentFor(trace, firstLine.source as string);
+    expect(recoveredSource).toBe(originalSource);
+  });
+});
+
 describe('CodeSizeAnalyzer', () => {
   let analyzer: CodeSizeAnalyzer;
   const mockLog = new Log(true);

src/__tests__/plugin.spec.ts

@@ -5,6 +5,7 @@ import path from 'node:path';
 import os from 'node:os';
 import { gzipSync } from 'node:zlib';
 import javascriptObfuscator from 'javascript-obfuscator';
+import remapping from '@jridgewell/remapping';
 
 import type { BundleList, Config, FormatSizeResult, ObfuscationResult, SizeResult } from '../type';
 import { isBoolean, isFileNameExcluded, isObject } from './is';
@@ -105,6 +106,20 @@ export function getChunkName(id: string, manualChunks: string[]): string {
   return VENDOR_MODULES;
 }
 
+export function composeSourcemaps(map1: Rollup.SourceMapInput | null, map2: Rollup.SourceMapInput | null, log?: (msg: string) => void): Rollup.SourceMapInput | null {
+  if (!map1) return map2;
+  if (!map2) return map1;
+
+  log?.('composing source maps...');
+
+  const composed = remapping(
+    [map2 as remapping.SourceMapInput, map1 as remapping.SourceMapInput],
+    () => null,
+  );
+
+  return composed as Rollup.SourceMapInput;
+}
+
 export class ObfuscatedFilesRegistry {
   private static instance: ObfuscatedFilesRegistry;
   private obfuscatedFiles: Set<string> = new Set();
@@ -167,17 +182,19 @@ export function obfuscateBundle(finalConfig: Config, fileName: string, bundleIte
         sourceMapFileName: `${fileName}.map`,
       }
     : finalConfig.options;
-  const obfuscationResult = javascriptObfuscator.obfuscate(bundleItem.code, fileSpecificOptions);
+  const obfuscated = javascriptObfuscator.obfuscate(bundleItem.code, fileSpecificOptions);
   _log.info(`obfuscation complete for ${fileName}.`);
 
   registry.markAsObfuscated(fileName);
   _log.info(`added ${fileName} to obfuscated files registry`);
 
-  const sourceMap = obfuscationResult.getSourceMap();
-
   return {
-    code: obfuscationResult.getObfuscatedCode(),
-    map: sourceMap ? JSON.parse(sourceMap) : null,
+    code: obfuscated.getObfuscatedCode(),
+    map: composeSourcemaps(
+      JSON.parse(JSON.stringify(bundleItem.map) || 'null'), // strip methods
+      JSON.parse(obfuscated.getSourceMap() || 'null'),
+      _log.info.bind(_log),
+    ),
   };
 }
 

src/utils/index.ts

@@ -1,6 +1,6 @@
 import { parentPort } from 'node:worker_threads';
 import javascriptObfuscator, { ObfuscatorOptions } from 'javascript-obfuscator';
-import { Log, ObfuscatedFilesRegistry } from '../utils';
+import { composeSourcemaps, Log, ObfuscatedFilesRegistry } from '../utils';
 import type { ObfuscationResult, WorkerMessage } from '../type';
 
 if (parentPort) {
@@ -40,7 +40,11 @@ if (parentPort) {
       results.push({
         fileName,
         obfuscatedCode: obfuscated.getObfuscatedCode(),
-        map: JSON.parse(obfuscated.getSourceMap() || 'null'),
+        map: composeSourcemaps(
+          JSON.parse(JSON.stringify(bundleItem.map) || 'null'), // strip methods
+          JSON.parse(obfuscated.getSourceMap() || 'null'),
+          _log.info.bind(_log),
+        ),
       });
     }