buffer: make File cloneable

Fixes: https://github.com/nodejs/node/issues/47612
PR-URL: https://github.com/nodejs/node/pull/47613
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

doc/api/buffer.md

@@ -5094,6 +5094,9 @@ added:
   - v19.2.0
   - v18.13.0
 changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/47613
+    description: Makes File instances cloneable.
   - version: v20.0.0
     pr-url: https://github.com/nodejs/node/pull/47153
     description: No longer experimental.

lib/internal/blob.js

@@ -504,4 +504,5 @@ module.exports = {
   isBlob,
   kHandle,
   resolveObjectURL,
+  TransferableBlob,
 };

lib/internal/file.js

@@ -2,14 +2,18 @@
 
 const {
   DateNow,
+  FunctionPrototypeApply,
   NumberIsNaN,
   ObjectDefineProperties,
+  ObjectSetPrototypeOf,
   StringPrototypeToWellFormed,
+  Symbol,
   SymbolToStringTag,
 } = primordials;
 
 const {
   Blob,
+  TransferableBlob,
 } = require('internal/blob');
 
 const {
@@ -20,6 +24,7 @@ const {
 
 const {
   codes: {
+    ERR_INVALID_THIS,
     ERR_MISSING_ARGS,
   },
 } = require('internal/errors');
@@ -28,13 +33,32 @@ const {
   inspect,
 } = require('internal/util/inspect');
 
+const {
+  kClone,
+  kDeserialize,
+} = require('internal/worker/js_transferable');
+
+const kState = Symbol('state');
+
+function isFile(object) {
+  return object?.[kState] !== undefined;
+}
+
+class FileState {
+  name;
+  lastModified;
+
+  /**
+   * @param {string} name
+   * @param {number} lastModified
+   */
+  constructor(name, lastModified) {
+    this.name = name;
+    this.lastModified = lastModified;
+  }
+}
+
 class File extends Blob {
-  /** @type {string} */
-  #name;
-
-  /** @type {number} */
-  #lastModified;
-
   constructor(fileBits, fileName, options = kEmptyObject) {
     if (arguments.length < 2) {
       throw new ERR_MISSING_ARGS('fileBits', 'fileName');
@@ -55,16 +79,21 @@ class File extends Blob {
       lastModified = DateNow();
     }
 
-    this.#name = StringPrototypeToWellFormed(`${fileName}`);
-    this.#lastModified = lastModified;
+    this[kState] = new FileState(StringPrototypeToWellFormed(`${fileName}`), lastModified);
   }
 
   get name() {
-    return this.#name;
+    if (!isFile(this))
+      throw new ERR_INVALID_THIS('File');
+
+    return this[kState].name;
   }
 
   get lastModified() {
-    return this.#lastModified;
+    if (!isFile(this))
+      throw new ERR_INVALID_THIS('File');
+
+    return this[kState].lastModified;
   }
 
   [kInspect](depth, options) {
@@ -80,12 +109,32 @@ class File extends Blob {
     return `File ${inspect({
       size: this.size,
       type: this.type,
-      name: this.#name,
-      lastModified: this.#lastModified,
+      name: this[kState].name,
+      lastModified: this[kState].lastModified,
     }, opts)}`;
   }
+
+  [kClone]() {
+    return {
+      data: { ...super[kClone]().data, ...this[kState] },
+      deserializeInfo: 'internal/file:TransferableFile',
+    };
+  }
+
+  [kDeserialize](data) {
+    super[kDeserialize](data);
+
+    this[kState] = new FileState(data.name, data.lastModified);
+  }
 }
 
+function TransferableFile(handle, length, type = '') {
+  FunctionPrototypeApply(TransferableBlob, this, [handle, length, type]);
+}
+
+ObjectSetPrototypeOf(TransferableFile.prototype, File.prototype);
+ObjectSetPrototypeOf(TransferableFile, File);
+
 ObjectDefineProperties(File.prototype, {
   name: kEnumerableProperty,
   lastModified: kEnumerableProperty,
@@ -98,4 +147,5 @@ ObjectDefineProperties(File.prototype, {
 
 module.exports = {
   File,
+  TransferableFile,
 };

test/parallel/test-file.js

@@ -158,3 +158,25 @@ const { inspect } = require('util');
     );
   });
 }
+
+(async () => {
+  // File should be cloneable via structuredClone.
+  // Refs: https://github.com/nodejs/node/issues/47612
+
+  const body = ['hello, ', 'world'];
+  const lastModified = Date.now() - 10_000;
+  const name = 'hello_world.txt';
+
+  const file = new File(body, name, { lastModified });
+  const clonedFile = structuredClone(file);
+
+  assert.deepStrictEqual(await clonedFile.text(), await file.text());
+  assert.deepStrictEqual(clonedFile.lastModified, file.lastModified);
+  assert.deepStrictEqual(clonedFile.name, file.name);
+
+  const clonedFile2 = structuredClone(clonedFile);
+
+  assert.deepStrictEqual(await clonedFile2.text(), await clonedFile.text());
+  assert.deepStrictEqual(clonedFile2.lastModified, clonedFile.lastModified);
+  assert.deepStrictEqual(clonedFile2.name, clonedFile.name);
+})().then(common.mustCall());

test/wpt/status/html/webappapis/structured-clone.json

@@ -1,7 +1 @@
-{
-  "structured-clone.any.js": {
-    "fail": {
-      "expected": ["File basic"]
-    }
-  }
-}
+{}