[modules] Disallow throwing in import.meta callback

... via a comment in the API and a CHECK in
Isolate::RunHostInitializeImportMetaObjectCallback.

Also restructure things a little bit such that
this function really just runs the callback and
doesn't deal with module internals. Memoization
now happens in the SourceTextModule class.

Bug: v8:7044
Change-Id: I5b850ae629c3638c4b30dfdeaa996642a33d14dc
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2190413
Reviewed-by: Sathya Gunasekaran  <gsathya@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Auto-Submit: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67682}

include/v8.h

@@ -7219,7 +7219,8 @@ typedef MaybeLocal<Promise> (*HostImportModuleDynamicallyCallback)(
 
 /**
  * HostInitializeImportMetaObjectCallback is called the first time import.meta
- * is accessed for a module. Subsequent access will reuse the same value.
+ * is accessed for a module. Subsequent access will reuse the same value. The
+ * callback must not throw.
  *
  * The method combines two implementation-defined abstract operations into one:
  * HostGetImportMetaProperties and HostFinalizeImportMeta.

src/execution/isolate.cc

@@ -3952,19 +3952,17 @@ void Isolate::SetHostImportModuleDynamicallyCallback(
 
 Handle<JSObject> Isolate::RunHostInitializeImportMetaObjectCallback(
     Handle<SourceTextModule> module) {
-  Handle<HeapObject> host_meta(module->import_meta(), this);
-  if (host_meta->IsTheHole(this)) {
-    host_meta = factory()->NewJSObjectWithNullProto();
-    if (host_initialize_import_meta_object_callback_ != nullptr) {
-      v8::Local<v8::Context> api_context =
-          v8::Utils::ToLocal(Handle<Context>(native_context()));
-      host_initialize_import_meta_object_callback_(
-          api_context, Utils::ToLocal(Handle<Module>::cast(module)),
-          v8::Local<v8::Object>::Cast(v8::Utils::ToLocal(host_meta)));
-    }
-    module->set_import_meta(*host_meta);
+  CHECK(module->import_meta().IsTheHole(this));
+  Handle<JSObject> import_meta = factory()->NewJSObjectWithNullProto();
+  if (host_initialize_import_meta_object_callback_ != nullptr) {
+    v8::Local<v8::Context> api_context =
+        v8::Utils::ToLocal(Handle<Context>(native_context()));
+    host_initialize_import_meta_object_callback_(
+        api_context, Utils::ToLocal(Handle<Module>::cast(module)),
+        v8::Local<v8::Object>::Cast(v8::Utils::ToLocal(import_meta)));
+    CHECK(!has_scheduled_exception());
   }
-  return Handle<JSObject>::cast(host_meta);
+  return import_meta;
 }
 
 void Isolate::SetHostInitializeImportMetaObjectCallback(

src/objects/source-text-module.cc

@@ -583,6 +583,16 @@ Handle<JSModuleNamespace> SourceTextModule::GetModuleNamespace(
   return Module::GetModuleNamespace(isolate, requested_module);
 }
 
+Handle<JSObject> SourceTextModule::GetImportMeta(
+    Isolate* isolate, Handle<SourceTextModule> module) {
+  Handle<HeapObject> import_meta(module->import_meta(), isolate);
+  if (import_meta->IsTheHole(isolate)) {
+    import_meta = isolate->RunHostInitializeImportMetaObjectCallback(module);
+    module->set_import_meta(*import_meta);
+  }
+  return Handle<JSObject>::cast(import_meta);
+}
+
 MaybeHandle<Object> SourceTextModule::EvaluateMaybeAsync(
     Isolate* isolate, Handle<SourceTextModule> module) {
   // In the event of errored evaluation, return a rejected promise.

src/objects/source-text-module.h

@@ -59,6 +59,11 @@ class SourceTextModule
   static Handle<JSModuleNamespace> GetModuleNamespace(
       Isolate* isolate, Handle<SourceTextModule> module, int module_request);
 
+  // Get the import.meta object of [module].  If it doesn't exist yet, it is
+  // created and passed to the embedder callback for initialization.
+  V8_EXPORT_PRIVATE static Handle<JSObject> GetImportMeta(
+      Isolate* isolate, Handle<SourceTextModule> module);
+
   using BodyDescriptor =
       SubclassBodyDescriptor<Module::BodyDescriptor,
                              FixedBodyDescriptor<kCodeOffset, kSize, kSize>>;

src/runtime/runtime-module.cc

@@ -41,7 +41,7 @@ RUNTIME_FUNCTION(Runtime_GetImportMetaObject) {
   HandleScope scope(isolate);
   DCHECK_EQ(0, args.length());
   Handle<SourceTextModule> module(isolate->context().module(), isolate);
-  return *isolate->RunHostInitializeImportMetaObjectCallback(module);
+  return *SourceTextModule::GetImportMeta(isolate, module);
 }
 
 }  // namespace internal

test/cctest/test-api.cc

@@ -25760,7 +25760,6 @@ void HostInitializeImportMetaObjectCallbackStatic(Local<Context> context,
                                                   Local<Module> module,
                                                   Local<Object> meta) {
   CHECK(!module.IsEmpty());
-
   meta->CreateDataProperty(context, v8_str("foo"), v8_str("bar")).ToChecked();
 }
 
@@ -25784,10 +25783,9 @@ TEST(ImportMeta) {
   v8::ScriptCompiler::Source source(source_text, origin);
   Local<Module> module =
       v8::ScriptCompiler::CompileModule(isolate, &source).ToLocalChecked();
-  i::Handle<i::Object> meta =
-      i_isolate->RunHostInitializeImportMetaObjectCallback(
-          i::Handle<i::SourceTextModule>::cast(v8::Utils::OpenHandle(*module)));
-  CHECK(meta->IsJSObject());
+  i::Handle<i::JSObject> meta = i::SourceTextModule::GetImportMeta(
+      i_isolate,
+      i::Handle<i::SourceTextModule>::cast(v8::Utils::OpenHandle(*module)));
   Local<Object> meta_obj = Local<Object>::Cast(v8::Utils::ToLocal(meta));
   CHECK(meta_obj->Get(context.local(), v8_str("foo"))
             .ToLocalChecked()