fix(node): deepCopy not working for large Buffers (#909)

deepCopy does not work when copying an object
with a large Buffer (see test case).

This causes issues when using multipartUpload with the
`checkpoint` option: e.g.

```js
const file = Buffer.alloc(Math.pow(2, 30) - 1);
// throws RangeError in utils/deepCopy
multipartUpload("name", file, {checkpoint: {file, ...}});
```

lib/common/utils/deepCopy.js

@@ -1,10 +1,14 @@
 "use strict";
 Object.defineProperty(exports, "__esModule", { value: true });
 exports.deepCopy = void 0;
+const isBuffer_1 = require("./isBuffer");
 exports.deepCopy = (obj) => {
     if (obj === null || typeof obj !== 'object') {
         return obj;
     }
+    if (isBuffer_1.isBuffer(obj)) {
+        return Buffer.from(obj);
+    }
     const copy = Array.isArray(obj) ? [] : {};
     Object.keys(obj).forEach((key) => {
         copy[key] = exports.deepCopy(obj[key]);

lib/common/utils/deepCopy.ts

@@ -1,7 +1,12 @@
+import { isBuffer } from './isBuffer';
+
 export const deepCopy = (obj) => {
   if (obj === null || typeof obj !== 'object') {
     return obj;
   }
+  if (isBuffer(obj)) {
+    return Buffer.from(obj);
+  }
 
   const copy = Array.isArray(obj) ? [] : {};
 

test/node/utils/deepCopy.test.js

@@ -0,0 +1,15 @@
+const assert = require('assert');
+const { Buffer } = require('buffer');
+const { deepCopy } = require('../../../lib/common/utils/deepCopy');
+
+describe('utils/deepCopy()', () => {
+  it('should copy big Buffers correctly', () => {
+    // 2^30 - 1 ~ 1GB is max size on 32-bit computer
+    // See https://nodejs.org/api/buffer.html#buffer_buffer_constants_max_length
+    const numberBytes = Math.pow(2, 30) - 1;
+    const obj = {
+      buffer: Buffer.alloc(numberBytes),
+    };
+    assert.deepStrictEqual(deepCopy(obj), obj);
+  });
+});