From 9d15da813e619f4568ec4557dff8da01a6618612 Mon Sep 17 00:00:00 2001
From: Xia Chao <236466140+bun-unsafe@users.noreply.github.com>
Date: Wed, 26 Aug 2026 18:09:04 +0800
Subject: [PATCH 1/2] fix(res.send): preserve bytes when sending DataView

DataView is an ArrayBuffer view but has no .length, so the binary
path produced an empty body with HTTP 200. Copy via byteOffset/byteLength.
---
 lib/response.js  |  3 +++
 test/res.send.js | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/lib/response.js b/lib/response.js
index bc672434890..1848bbed8e5 100644
--- a/lib/response.js
+++ b/lib/response.js
@@ -149,6 +149,9 @@ res.send = function send(body) {
       if (chunk === null) {
         chunk = '';
       } else if (ArrayBuffer.isView(chunk)) {
+        if (!Buffer.isBuffer(chunk)) {
+          chunk = Buffer.from(chunk.buffer, chunk.byteOffset, chunk.byteLength)
+        }
         if (!this.get('Content-Type')) {
           this.type('bin');
         }
diff --git a/test/res.send.js b/test/res.send.js
index f38ffde9776..51607533214 100644
--- a/test/res.send.js
+++ b/test/res.send.js
@@ -217,6 +217,38 @@ describe('res', function(){
         .expect(200, "hey", done);
     })
 
+    it('should accept DataView', function (done) {
+      var app = express()
+      var ab = new ArrayBuffer(4)
+      new Uint8Array(ab).set([1, 2, 3, 4])
+
+      app.use(function (req, res) {
+        res.send(new DataView(ab))
+      })
+
+      request(app)
+        .get('/')
+        .expect('Content-Type', 'application/octet-stream')
+        .expect(utils.shouldHaveBody(Buffer.from([1, 2, 3, 4])))
+        .end(done)
+    })
+
+    it('should honor DataView byteOffset and byteLength', function (done) {
+      var app = express()
+      var ab = new ArrayBuffer(6)
+      new Uint8Array(ab).set([9, 1, 2, 3, 4, 8])
+
+      app.use(function (req, res) {
+        res.send(new DataView(ab, 1, 4))
+      })
+
+      request(app)
+        .get('/')
+        .expect('Content-Type', 'application/octet-stream')
+        .expect(utils.shouldHaveBody(Buffer.from([1, 2, 3, 4])))
+        .end(done)
+    })
+
     it('should not override ETag', function (done) {
       var app = express()
 

From f9330f13a6b0d9cd65e9974a4fbcadc514ff51c9 Mon Sep 17 00:00:00 2001
From: Xia Chao <236466140+bun-unsafe@users.noreply.github.com>
Date: Mon, 31 Aug 2026 01:22:14 +0800
Subject: [PATCH 2/2] fix(res.send): limit backing-buffer copy to DataView

Keep the existing typed-array path so Uint16Array and similar views
still send one byte per element. Add a regression test.
---
 lib/response.js  |  2 +-
 test/res.send.js | 15 +++++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/lib/response.js b/lib/response.js
index 1848bbed8e5..d2f2294ca46 100644
--- a/lib/response.js
+++ b/lib/response.js
@@ -149,7 +149,7 @@ res.send = function send(body) {
       if (chunk === null) {
         chunk = '';
       } else if (ArrayBuffer.isView(chunk)) {
-        if (!Buffer.isBuffer(chunk)) {
+        if (typeof DataView === 'function' && chunk instanceof DataView) {
           chunk = Buffer.from(chunk.buffer, chunk.byteOffset, chunk.byteLength)
         }
         if (!this.get('Content-Type')) {
diff --git a/test/res.send.js b/test/res.send.js
index 51607533214..169e73a7131 100644
--- a/test/res.send.js
+++ b/test/res.send.js
@@ -249,6 +249,21 @@ describe('res', function(){
         .end(done)
     })
 
+    it('should keep existing non-byte typed array payload', function (done) {
+      var app = express()
+
+      app.use(function (req, res) {
+        res.send(new Uint16Array([0x0102, 0x0304]))
+      })
+
+      request(app)
+        .get('/')
+        .expect('Content-Type', 'application/octet-stream')
+        .expect('Content-Length', '2')
+        .expect(utils.shouldHaveBody(Buffer.from([0x02, 0x04])))
+        .end(done)
+    })
+
     it('should not override ETag', function (done) {
       var app = express()