From 2505cecc0f6d8b70b21952c30ee1f885c67debd8 Mon Sep 17 00:00:00 2001
From: Andrew Kaster <akaster@serenityos.org>
Date: Thu, 18 Jan 2024 16:59:22 -0700
Subject: [PATCH] LibWeb: Exclude [Global] interfaces from legacy platform
 object methods

Window and other global objects are not technically legacy platform
objects, and have other ways to override their setters and getters.

However, Window does need to share some code with the legacy platform
object paths, and simply adding another bool check to the mix seems
the shortest putt.
---
 .../expected/HTML/Window-set-properties.txt   |  6 +++++
 .../input/HTML/Window-set-properties.html     | 22 +++++++++++++++++++
 .../LibWeb/Bindings/PlatformObject.cpp        | 10 ++++-----
 3 files changed, 33 insertions(+), 5 deletions(-)
 create mode 100644 Tests/LibWeb/Text/expected/HTML/Window-set-properties.txt
 create mode 100644 Tests/LibWeb/Text/input/HTML/Window-set-properties.html

diff --git a/Tests/LibWeb/Text/expected/HTML/Window-set-properties.txt b/Tests/LibWeb/Text/expected/HTML/Window-set-properties.txt
new file mode 100644
index 0000000000..ec001f5d98
--- /dev/null
+++ b/Tests/LibWeb/Text/expected/HTML/Window-set-properties.txt
@@ -0,0 +1,6 @@
+window.__NEXT_DATA__ = [object HTMLScriptElement]
+window.__NEXT_DATA__ = undefined
+window[0] = undefined
+e = TypeError: Cannot set property '0' of [object WindowProxy]
+window[0] = undefined
+window[0] = 42
diff --git a/Tests/LibWeb/Text/input/HTML/Window-set-properties.html b/Tests/LibWeb/Text/input/HTML/Window-set-properties.html
new file mode 100644
index 0000000000..9637531eb7
--- /dev/null
+++ b/Tests/LibWeb/Text/input/HTML/Window-set-properties.html
@@ -0,0 +1,22 @@
+<script src="../include.js"></script>
+<script id="__NEXT_DATA__"></script>
+<script>
+    test(() => {
+        "use strict";
+        println(`window.__NEXT_DATA__ = ${window.__NEXT_DATA__}`);
+        window.__NEXT_DATA__ = undefined;
+        println(`window.__NEXT_DATA__ = ${window.__NEXT_DATA__}`);
+
+        println(`window[0] = ${window[0]}`);
+
+        // FIXME: Other browsers just swallow this error, but we throw an exception.
+        try {
+            window[0] = 42;
+        } catch (e) {
+            println(`e = ${e}`);
+        }
+        println(`window[0] = ${window[0]}`);
+        window.__proto__[0] = 42;
+        println(`window[0] = ${window[0]}`);
+    });
+</script>
diff --git a/Userland/Libraries/LibWeb/Bindings/PlatformObject.cpp b/Userland/Libraries/LibWeb/Bindings/PlatformObject.cpp
index 6dfd8a4919..30804ae952 100644
--- a/Userland/Libraries/LibWeb/Bindings/PlatformObject.cpp
+++ b/Userland/Libraries/LibWeb/Bindings/PlatformObject.cpp
@@ -217,7 +217,7 @@ WebIDL::ExceptionOr<void> PlatformObject::invoke_named_property_setter(String co
 // https://webidl.spec.whatwg.org/#legacy-platform-object-getownproperty
 JS::ThrowCompletionOr<Optional<JS::PropertyDescriptor>> PlatformObject::internal_get_own_property(JS::PropertyKey const& property_name) const
 {
-    if (m_legacy_platform_object_flags.has_value()) {
+    if (m_legacy_platform_object_flags.has_value() && !m_legacy_platform_object_flags->has_global_interface_extended_attribute) {
         // 1. Return ? PlatformObjectGetOwnProperty(O, P, false).
         return TRY(legacy_platform_object_get_own_property(property_name, IgnoreNamedProps::No));
     } else {
@@ -228,7 +228,7 @@ JS::ThrowCompletionOr<Optional<JS::PropertyDescriptor>> PlatformObject::internal
 // https://webidl.spec.whatwg.org/#legacy-platform-object-set
 JS::ThrowCompletionOr<bool> PlatformObject::internal_set(JS::PropertyKey const& property_name, JS::Value value, JS::Value receiver, JS::CacheablePropertyMetadata* metadata)
 {
-    if (!m_legacy_platform_object_flags.has_value())
+    if (!m_legacy_platform_object_flags.has_value() || m_legacy_platform_object_flags->has_global_interface_extended_attribute)
         return Base::internal_set(property_name, value, receiver, metadata);
 
     auto& vm = this->vm();
@@ -266,7 +266,7 @@ JS::ThrowCompletionOr<bool> PlatformObject::internal_set(JS::PropertyKey const&
 // https://webidl.spec.whatwg.org/#legacy-platform-object-defineownproperty
 JS::ThrowCompletionOr<bool> PlatformObject::internal_define_own_property(JS::PropertyKey const& property_name, JS::PropertyDescriptor const& property_descriptor)
 {
-    if (!m_legacy_platform_object_flags.has_value())
+    if (!m_legacy_platform_object_flags.has_value() || m_legacy_platform_object_flags->has_global_interface_extended_attribute)
         return Base::internal_define_own_property(property_name, property_descriptor);
 
     auto& vm = this->vm();
@@ -335,7 +335,7 @@ JS::ThrowCompletionOr<bool> PlatformObject::internal_define_own_property(JS::Pro
 // https://webidl.spec.whatwg.org/#legacy-platform-object-delete
 JS::ThrowCompletionOr<bool> PlatformObject::internal_delete(JS::PropertyKey const& property_name)
 {
-    if (!m_legacy_platform_object_flags.has_value())
+    if (!m_legacy_platform_object_flags.has_value() || m_legacy_platform_object_flags->has_global_interface_extended_attribute)
         return Base::internal_delete(property_name);
 
     auto& vm = this->vm();
@@ -403,7 +403,7 @@ JS::ThrowCompletionOr<bool> PlatformObject::internal_delete(JS::PropertyKey cons
 // https://webidl.spec.whatwg.org/#legacy-platform-object-preventextensions
 JS::ThrowCompletionOr<bool> PlatformObject::internal_prevent_extensions()
 {
-    if (!m_legacy_platform_object_flags.has_value())
+    if (!m_legacy_platform_object_flags.has_value() || m_legacy_platform_object_flags->has_global_interface_extended_attribute)
         return Base::internal_prevent_extensions();
 
     // 1. Return false.