fix: accept Uint8Array where Buffer is accepted

Also fixes NODE-3223 (ensureBuffer ignores byteLength/byteOffset).
This is the "proper" alternative to
#418 and matches what e.g.
Node.js APIs do.

Author: addaleax

src/ensure_buffer.ts

@@ -1,5 +1,5 @@
 import { Buffer } from 'buffer';
-import { isBuffer, isAnyArrayBuffer } from './parser/utils';
+import { isAnyArrayBuffer } from './parser/utils';
 
 /**
  * Makes sure that, if a Uint8Array is passed in, it is wrapped in a Buffer.
@@ -10,12 +10,12 @@ import { isBuffer, isAnyArrayBuffer } from './parser/utils';
  * @throws TypeError If anything other than a Buffer or Uint8Array is passed in
  */
 export function ensureBuffer(potentialBuffer: Buffer | ArrayBufferView | ArrayBuffer): Buffer {
-  if (isBuffer(potentialBuffer)) {
-    return potentialBuffer;
-  }
-
   if (ArrayBuffer.isView(potentialBuffer)) {
-    return Buffer.from(potentialBuffer.buffer);
+    return Buffer.from(
+      potentialBuffer.buffer,
+      potentialBuffer.byteOffset,
+      potentialBuffer.byteLength
+    );
   }
 
   if (isAnyArrayBuffer(potentialBuffer)) {

src/objectid.ts

@@ -1,6 +1,6 @@
 import { Buffer } from 'buffer';
 import { ensureBuffer } from './ensure_buffer';
-import { deprecate, randomBytes } from './parser/utils';
+import { deprecate, isUint8Array, randomBytes } from './parser/utils';
 
 // constants
 const PROCESS_UNIQUE = randomBytes(5);
@@ -229,9 +229,9 @@ export class ObjectId {
       typeof otherId === 'string' &&
       ObjectId.isValid(otherId) &&
       otherId.length === 12 &&
-      Buffer.isBuffer(this.id)
+      isUint8Array(this.id)
     ) {
-      return otherId === this.id.toString('binary');
+      return otherId === Buffer.prototype.toString.call(this.id, 'latin1');
     }
 
     if (typeof otherId === 'string' && ObjectId.isValid(otherId) && otherId.length === 24) {
@@ -300,7 +300,7 @@ export class ObjectId {
    *
    * @param id - ObjectId instance to validate.
    */
-  static isValid(id: number | string | ObjectId | Buffer | ObjectIdLike): boolean {
+  static isValid(id: number | string | ObjectId | Uint8Array | ObjectIdLike): boolean {
     if (id == null) return false;
 
     if (typeof id === 'number') {
@@ -315,7 +315,7 @@ export class ObjectId {
       return true;
     }
 
-    if (Buffer.isBuffer(id) && id.length === 12) {
+    if (isUint8Array(id) && id.length === 12) {
       return true;
     }
 

src/parser/serializer.ts

@@ -18,7 +18,6 @@ import type { BSONRegExp } from '../regexp';
 import {
   isBigInt64Array,
   isBigUInt64Array,
-  isBuffer,
   isDate,
   isMap,
   isRegExp,
@@ -784,7 +783,7 @@ export function serializeInto(
         index = serializeNull(buffer, key, value, index, true);
       } else if (value['_bsontype'] === 'ObjectId' || value['_bsontype'] === 'ObjectID') {
         index = serializeObjectId(buffer, key, value, index, true);
-      } else if (isBuffer(value) || isUint8Array(value)) {
+      } else if (isUint8Array(value)) {
         index = serializeBuffer(buffer, key, value, index, true);
       } else if (value instanceof RegExp || isRegExp(value)) {
         index = serializeRegExp(buffer, key, value, index, true);
@@ -890,7 +889,7 @@ export function serializeInto(
         index = serializeNull(buffer, key, value, index);
       } else if (value['_bsontype'] === 'ObjectId' || value['_bsontype'] === 'ObjectID') {
         index = serializeObjectId(buffer, key, value, index);
-      } else if (isBuffer(value) || isUint8Array(value)) {
+      } else if (isUint8Array(value)) {
         index = serializeBuffer(buffer, key, value, index);
       } else if (value instanceof RegExp || isRegExp(value)) {
         index = serializeRegExp(buffer, key, value, index);
@@ -996,7 +995,7 @@ export function serializeInto(
         index = serializeNull(buffer, key, value, index);
       } else if (value['_bsontype'] === 'ObjectId' || value['_bsontype'] === 'ObjectID') {
         index = serializeObjectId(buffer, key, value, index);
-      } else if (isBuffer(value) || isUint8Array(value)) {
+      } else if (isUint8Array(value)) {
         index = serializeBuffer(buffer, key, value, index);
       } else if (value instanceof RegExp || isRegExp(value)) {
         index = serializeRegExp(buffer, key, value, index);

src/parser/utils.ts

@@ -93,11 +93,6 @@ export function haveBuffer(): boolean {
   return typeof global !== 'undefined' && typeof global.Buffer !== 'undefined';
 }
 
-/** Callable in any environment to check if value is a Buffer */
-export function isBuffer(value: unknown): value is Buffer {
-  return typeof value === 'object' && value?.constructor?.name === 'Buffer';
-}
-
 // To ensure that 0.4 of node works correctly
 export function isDate(d: unknown): d is Date {
   return isObjectLike(d) && Object.prototype.toString.call(d) === '[object Date]';

src/uuid.ts

@@ -2,7 +2,7 @@ import { Buffer } from 'buffer';
 import { ensureBuffer } from './ensure_buffer';
 import { Binary } from './binary';
 import { bufferToUuidHexString, uuidHexStringToBuffer, uuidValidateString } from './uuid_utils';
-import { randomBytes } from './parser/utils';
+import { isUint8Array, randomBytes } from './parser/utils';
 
 /** @public */
 export type UUIDExtended = {
@@ -40,10 +40,7 @@ export class UUID {
     } else if (input instanceof UUID) {
       this[kId] = Buffer.from(input.id);
       this.__id = input.__id;
-    } else if (
-      (Buffer.isBuffer(input) || ArrayBuffer.isView(input)) &&
-      input.byteLength === BYTE_LENGTH
-    ) {
+    } else if (ArrayBuffer.isView(input) && input.byteLength === BYTE_LENGTH) {
       this.id = ensureBuffer(input);
     } else if (typeof input === 'string') {
       this.id = uuidHexStringToBuffer(input);
@@ -167,7 +164,7 @@ export class UUID {
       return uuidValidateString(input);
     }
 
-    if (Buffer.isBuffer(input)) {
+    if (isUint8Array(input)) {
       // check for length & uuid version (https://tools.ietf.org/html/rfc4122#section-4.1.3)
       if (input.length !== BYTE_LENGTH) {
         return false;

test/node/ensure_buffer_test.js

@@ -9,15 +9,18 @@ describe('ensureBuffer tests', function () {
     expect(ensureBuffer).to.be.a('function');
   });
 
-  it('should return the exact same buffer if a buffer is passed in', function () {
+  it('should return a view over the exact same memory when a Buffer is passed in', function () {
     const bufferIn = Buffer.alloc(10);
     let bufferOut;
 
     expect(function () {
       bufferOut = ensureBuffer(bufferIn);
     }).to.not.throw(Error);
 
-    expect(bufferOut).to.equal(bufferIn);
+    expect(bufferOut).to.be.an.instanceOf(Buffer);
+    expect(bufferOut.buffer).to.equal(bufferIn.buffer);
+    expect(bufferOut.byteLength).to.equal(bufferIn.byteLength);
+    expect(bufferOut.byteOffset).to.equal(bufferIn.byteOffset);
   });
 
   it('should wrap a Uint8Array with a buffer', function () {
@@ -60,6 +63,19 @@ describe('ensureBuffer tests', function () {
     expect(bufferOut.buffer).to.equal(arrayBufferIn);
   });
 
+  it('should account for the input view byteLength and byteOffset', function () {
+    const input = new Uint8Array(new Uint8Array([1, 2, 3, 4, 5]).buffer, 1, 3);
+    let bufferOut;
+
+    expect(function () {
+      bufferOut = ensureBuffer(input);
+    }).to.not.throw(Error);
+
+    expect(bufferOut).to.be.an.instanceOf(Buffer);
+    expect(bufferOut.byteLength).to.equal(3);
+    expect(bufferOut.byteOffset).to.equal(1);
+  });
+
   [0, 12, -1, '', 'foo', null, undefined, ['list'], {}, /x/].forEach(function (item) {
     it(`should throw if input is ${typeof item}: ${item}`, function () {
       expect(function () {