From bdf6f733bfa27d8a322e9ed4ea90ff8af999b19e Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Sat, 3 Jul 2021 10:11:41 +0200
Subject: [PATCH] Don't attempt to structure clone unsupported types with
 workers disabled

Please refer to https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API/Structured_clone_algorithm

Based on that information, and manually testing our code, the implementation in `cloneValue` has the following shortcomings:
 - Attempting to clone `function`s is only prevented when they're part of an Object, but is currently allowed when they occur standalone.
 - Cloning of `Symbol`s is currently not prevented, which it should be since the native structured clone algorithm throws.
 - Any disallowed types should be checked first, to reduce the risk of future changes accidentally allowing something that shouldn't be supported.
---
 src/display/api.js | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/src/display/api.js b/src/display/api.js
index 8e69941de..e4b4c7c10 100644
--- a/src/display/api.js
+++ b/src/display/api.js
@@ -1805,6 +1805,16 @@ class LoopbackPort {
     function cloneValue(value) {
       // Trying to perform a structured clone close to the spec, including
       // transfers.
+      if (
+        typeof value === "function" ||
+        typeof value === "symbol" ||
+        value instanceof URL
+      ) {
+        throw new Error(
+          `LoopbackPort.postMessage - cannot clone: ${value?.toString()}`
+        );
+      }
+
       if (typeof value !== "object" || value === null) {
         return value;
       }
@@ -1843,9 +1853,6 @@ class LoopbackPort {
         }
         return result;
       }
-      if (value instanceof URL) {
-        throw new Error(`LoopbackPort.postMessage - cannot clone: ${value}`);
-      }
       result = Array.isArray(value) ? [] : Object.create(null);
       cloned.set(value, result); // Adding to cache now for cyclic references.
       // Cloning all value and object properties, however ignoring properties
@@ -1859,12 +1866,7 @@ class LoopbackPort {
         if (typeof desc.value === "undefined") {
           continue;
         }
-        if (typeof desc.value === "function") {
-          if (value.hasOwnProperty?.(i)) {
-            throw new Error(
-              `LoopbackPort.postMessage - cannot clone: ${value[i]}`
-            );
-          }
+        if (typeof desc.value === "function" && !value.hasOwnProperty?.(i)) {
           continue;
         }
         result[i] = cloneValue(desc.value);