From 4ab7c8a12520e07cffe95b7d0bd91ddb14a2eba9 Mon Sep 17 00:00:00 2001
From: Khafra <maitken033380023@gmail.com>
Date: Wed, 25 Oct 2023 17:24:45 -0400
Subject: [PATCH] src: readiterable entries may be empty

---
 src/node_messaging.cc                        |  7 +++++--
 test/parallel/test-messagechannel.js         | 12 ++++++++++++
 test/parallel/test-structuredClone-global.js | 11 +++++++++++
 3 files changed, 28 insertions(+), 2 deletions(-)
 create mode 100644 test/parallel/test-messagechannel.js

diff --git a/src/node_messaging.cc b/src/node_messaging.cc
index 571b271b69605a..47cc80cf551f74 100644
--- a/src/node_messaging.cc
+++ b/src/node_messaging.cc
@@ -1003,8 +1003,11 @@ static Maybe<bool> ReadIterable(Environment* env,
     entries.push_back(val);
   }
 
-  transfer_list.AllocateSufficientStorage(entries.size());
-  std::copy(entries.begin(), entries.end(), &transfer_list[0]);
+  if (!entries.empty()) {
+    transfer_list.AllocateSufficientStorage(entries.size());
+    std::copy(entries.begin(), entries.end(), &transfer_list[0]);
+  }
+
   return Just(true);
 }
 
diff --git a/test/parallel/test-messagechannel.js b/test/parallel/test-messagechannel.js
new file mode 100644
index 00000000000000..4f92924daa5048
--- /dev/null
+++ b/test/parallel/test-messagechannel.js
@@ -0,0 +1,12 @@
+'use strict';
+
+const common = require('../common');
+
+// See: https://github.com/nodejs/node/issues/49940
+(async () => {
+  new MessageChannel().port1.postMessage({}, {
+    transfer: {
+      *[Symbol.iterator]() {}
+    }
+  });
+})().then(common.mustCall());
diff --git a/test/parallel/test-structuredClone-global.js b/test/parallel/test-structuredClone-global.js
index 2b49a7a2e70696..ac5fc370c7845b 100644
--- a/test/parallel/test-structuredClone-global.js
+++ b/test/parallel/test-structuredClone-global.js
@@ -15,3 +15,14 @@ assert.strictEqual(structuredClone(undefined, null), undefined);
 // Transfer can be null or undefined.
 assert.strictEqual(structuredClone(undefined, { transfer: null }), undefined);
 assert.strictEqual(structuredClone(undefined, { }), undefined);
+
+{
+  // See: https://github.com/nodejs/node/issues/49940
+  const cloned = structuredClone({}, {
+    transfer: {
+      *[Symbol.iterator]() {}
+    }
+  });
+
+  assert.strictEqual(cloned, {});
+}