fix: support cross-context ArrayBuffer in TextDecoder

Author: ChALkeR

fallback/encoding.js

@@ -47,11 +47,18 @@ export function normalizeEncoding(label) {
 
 const define = (obj, key, value) => Object.defineProperty(obj, key, { value, writable: false })
 
+function isAnyArrayBuffer(x) {
+  if (!x || typeof x.byteLength !== 'number') return false
+  const s = Object.prototype.toString.call(x)
+  return s === '[object ArrayBuffer]' || s === '[object SharedArrayBuffer]'
+}
+
 const fromSource = (x) => {
   if (x instanceof Uint8Array) return x
   if (x instanceof ArrayBuffer) return new Uint8Array(x)
   if (ArrayBuffer.isView(x)) return new Uint8Array(x.buffer, x.byteOffset, x.byteLength)
   if (globalThis.SharedArrayBuffer && x instanceof SharedArrayBuffer) return new Uint8Array(x)
+  if (isAnyArrayBuffer(x)) return new Uint8Array(x)
   throw new TypeError('Argument must be a SharedArrayBuffer, ArrayBuffer or ArrayBufferView')
 }
 

tests/encoding/cross-context.test.cjs

@@ -11,20 +11,29 @@ try {
 describe('vm', { skip: !vm }, () => {
   const string = 'Hello, \u2200'
   const u = Uint8Array.of(0x48, 0x65, 0x6c, 0x6c, 0x6f, 0x2c, 0x20, 0xe2, 0x88, 0x80)
+  const ctx = { TextDecoder, TextEncoder }
 
   test('TextEncoder', (t) => {
-    const ctx = { TextEncoder }
     const outer = new TextEncoder().encode(string)
     const inner = vm.runInNewContext(`new TextEncoder().encode(${JSON.stringify(string)})`, ctx)
     t.assert.deepStrictEqual(outer, u)
     t.assert.deepStrictEqual(inner, u)
   })
 
-  test('TextDecoder', (t) => {
-    const ctx = { TextDecoder }
+  test('TextDecoder + Uint8Array', (t) => {
     const outer = new TextDecoder().decode(u)
     const inner = vm.runInNewContext(`new TextDecoder().decode(Uint8Array.of(${u.join(',')}))`, ctx)
     t.assert.deepStrictEqual(outer, string)
     t.assert.deepStrictEqual(inner, string)
   })
+
+  test('TextDecoder + ArrayBuffer', (t) => {
+    const outer = new TextDecoder().decode(u.buffer)
+    const inner = vm.runInNewContext(
+      `new TextDecoder().decode(Uint8Array.of(${u.join(',')}).buffer)`,
+      ctx
+    )
+    t.assert.deepStrictEqual(outer, string)
+    t.assert.deepStrictEqual(inner, string)
+  })
 })