From 62ecff0b4052e1dee95c3bc6ad1dbdf9cdd61299 Mon Sep 17 00:00:00 2001
From: Tim Ledbetter <tim.ledbetter@ladybird.org>
Date: Thu, 5 Dec 2024 10:05:10 +0000
Subject: [PATCH] LibWeb: Report exceptions that occur during microtask
 callback

---
 Libraries/LibWeb/HTML/HTMLCanvasElement.cpp   |  4 +--
 .../LibWeb/HTML/UniversalGlobalScope.cpp      |  8 ++---
 ...-cross-realm-callback-report-exception.txt |  6 ++++
 ...-cross-realm-callback-report-exception.txt |  6 ++++
 ...cross-realm-callback-report-exception.html | 29 +++++++++++++++++++
 ...cross-realm-callback-report-exception.html | 28 ++++++++++++++++++
 6 files changed, 74 insertions(+), 7 deletions(-)
 create mode 100644 Tests/LibWeb/Text/expected/wpt-import/html/semantics/embedded-content/the-canvas-element/toBlob-cross-realm-callback-report-exception.txt
 create mode 100644 Tests/LibWeb/Text/expected/wpt-import/html/webappapis/microtask-queuing/queue-microtask-cross-realm-callback-report-exception.txt
 create mode 100644 Tests/LibWeb/Text/input/wpt-import/html/semantics/embedded-content/the-canvas-element/toBlob-cross-realm-callback-report-exception.html
 create mode 100644 Tests/LibWeb/Text/input/wpt-import/html/webappapis/microtask-queuing/queue-microtask-cross-realm-callback-report-exception.html

diff --git a/Libraries/LibWeb/HTML/HTMLCanvasElement.cpp b/Libraries/LibWeb/HTML/HTMLCanvasElement.cpp
index 0b3a630d437..0e9fc291561 100644
--- a/Libraries/LibWeb/HTML/HTMLCanvasElement.cpp
+++ b/Libraries/LibWeb/HTML/HTMLCanvasElement.cpp
@@ -375,8 +375,8 @@ WebIDL::ExceptionOr<void> HTMLCanvasElement::to_blob(GC::Ref<WebIDL::CallbackTyp
                 if (file_result.has_value())
                     blob_result = FileAPI::Blob::create(realm(), file_result->buffer, TRY_OR_THROW_OOM(vm(), String::from_utf8(file_result->mime_type)));
 
-                // 2. Invoke callback with « result ».
-                TRY(WebIDL::invoke_callback(*callback, {}, move(blob_result)));
+                // 2. Invoke callback with « result » and "report".
+                TRY(WebIDL::invoke_callback(*callback, {}, WebIDL::ExceptionBehavior::Report, move(blob_result)));
                 return {};
             });
             if (maybe_error.is_throw_completion())
diff --git a/Libraries/LibWeb/HTML/UniversalGlobalScope.cpp b/Libraries/LibWeb/HTML/UniversalGlobalScope.cpp
index a655e333a21..3199611b7fe 100644
--- a/Libraries/LibWeb/HTML/UniversalGlobalScope.cpp
+++ b/Libraries/LibWeb/HTML/UniversalGlobalScope.cpp
@@ -84,11 +84,9 @@ void UniversalGlobalScopeMixin::queue_microtask(WebIDL::CallbackType& callback)
     if (is<Window>(this_impl()))
         document = &static_cast<Window&>(this_impl()).associated_document();
 
-    // The queueMicrotask(callback) method must queue a microtask to invoke callback, and if callback throws an exception, report the exception.
-    HTML::queue_a_microtask(document, GC::create_function(realm.heap(), [&callback, &realm] {
-        auto result = WebIDL::invoke_callback(callback, {});
-        if (result.is_error())
-            HTML::report_exception(result, realm);
+    // The queueMicrotask(callback) method must queue a microtask to invoke callback with « » and "report".
+    HTML::queue_a_microtask(document, GC::create_function(realm.heap(), [&callback] {
+        (void)WebIDL::invoke_callback(callback, {}, WebIDL::ExceptionBehavior::Report);
     }));
 }
 
diff --git a/Tests/LibWeb/Text/expected/wpt-import/html/semantics/embedded-content/the-canvas-element/toBlob-cross-realm-callback-report-exception.txt b/Tests/LibWeb/Text/expected/wpt-import/html/semantics/embedded-content/the-canvas-element/toBlob-cross-realm-callback-report-exception.txt
new file mode 100644
index 00000000000..b03164168bb
--- /dev/null
+++ b/Tests/LibWeb/Text/expected/wpt-import/html/semantics/embedded-content/the-canvas-element/toBlob-cross-realm-callback-report-exception.txt
@@ -0,0 +1,6 @@
+Harness status: OK
+
+Found 1 tests
+
+1 Pass
+Pass	toBlob() reports the exception from its callback in the callback's global object
\ No newline at end of file
diff --git a/Tests/LibWeb/Text/expected/wpt-import/html/webappapis/microtask-queuing/queue-microtask-cross-realm-callback-report-exception.txt b/Tests/LibWeb/Text/expected/wpt-import/html/webappapis/microtask-queuing/queue-microtask-cross-realm-callback-report-exception.txt
new file mode 100644
index 00000000000..1519c3376f6
--- /dev/null
+++ b/Tests/LibWeb/Text/expected/wpt-import/html/webappapis/microtask-queuing/queue-microtask-cross-realm-callback-report-exception.txt
@@ -0,0 +1,6 @@
+Harness status: OK
+
+Found 1 tests
+
+1 Pass
+Pass	queueMicrotask() reports the exception from its callback in the callback's global object
\ No newline at end of file
diff --git a/Tests/LibWeb/Text/input/wpt-import/html/semantics/embedded-content/the-canvas-element/toBlob-cross-realm-callback-report-exception.html b/Tests/LibWeb/Text/input/wpt-import/html/semantics/embedded-content/the-canvas-element/toBlob-cross-realm-callback-report-exception.html
new file mode 100644
index 00000000000..9e7faad6ff9
--- /dev/null
+++ b/Tests/LibWeb/Text/input/wpt-import/html/semantics/embedded-content/the-canvas-element/toBlob-cross-realm-callback-report-exception.html
@@ -0,0 +1,29 @@
+<!doctype html>
+<meta charset=utf-8>
+<title>toBlob() reports the exception from its callback in the callback's global object</title>
+<script src=../../../../resources/testharness.js></script>
+<script src=../../../../resources/testharnessreport.js></script>
+<iframe srcdoc="<canvas></canvas>"></iframe>
+<iframe></iframe>
+<iframe></iframe>
+<script>
+setup({ allow_uncaught_exception: true });
+
+const onerrorCalls = [];
+window.onerror = () => { onerrorCalls.push("top"); };
+frames[0].onerror = () => { onerrorCalls.push("frame0"); };
+frames[1].onerror = () => { onerrorCalls.push("frame1"); };
+frames[2].onerror = () => { onerrorCalls.push("frame2"); };
+
+async_test(t => {
+  window.onload = t.step_func(() => {
+    const canvas = frames[0].document.querySelector("canvas");
+    canvas.toBlob(new frames[1].Function(`throw new parent.frames[2].Error("PASS");`));
+
+    t.step_timeout(() => {
+      assert_array_equals(onerrorCalls, ["frame1"]);
+      t.done();
+    }, 25);
+  });
+});
+</script>
diff --git a/Tests/LibWeb/Text/input/wpt-import/html/webappapis/microtask-queuing/queue-microtask-cross-realm-callback-report-exception.html b/Tests/LibWeb/Text/input/wpt-import/html/webappapis/microtask-queuing/queue-microtask-cross-realm-callback-report-exception.html
new file mode 100644
index 00000000000..9c1113eab8a
--- /dev/null
+++ b/Tests/LibWeb/Text/input/wpt-import/html/webappapis/microtask-queuing/queue-microtask-cross-realm-callback-report-exception.html
@@ -0,0 +1,28 @@
+<!doctype html>
+<meta charset=utf-8>
+<title>queueMicrotask() reports the exception from its callback in the callback's global object</title>
+<script src=../../../resources/testharness.js></script>
+<script src=../../../resources/testharnessreport.js></script>
+<iframe></iframe>
+<iframe></iframe>
+<iframe></iframe>
+<script>
+setup({ allow_uncaught_exception: true });
+
+const onerrorCalls = [];
+window.onerror = () => { onerrorCalls.push("top"); };
+frames[0].onerror = () => { onerrorCalls.push("frame0"); };
+frames[1].onerror = () => { onerrorCalls.push("frame1"); };
+frames[2].onerror = () => { onerrorCalls.push("frame2"); };
+
+async_test(t => {
+  window.onload = t.step_func(() => {
+    frames[0].queueMicrotask(new frames[1].Function(`throw new parent.frames[2].Error("PASS");`));
+
+    t.step_timeout(() => {
+      assert_array_equals(onerrorCalls, ["frame1"]);
+      t.done();
+    }, 4);
+  });
+});
+</script>