Bug 1706937 - Cleanup JS source-element callback. r=jandem

Rename the JSGetElementCallback hook to JSSourceElementCallback to avoid
confusion with GetElement operations.

Differential Revision: https://phabricator.services.mozilla.com/D113985

dom/script/ScriptSettings.cpp

@@ -50,33 +50,33 @@
 namespace mozilla {
 namespace dom {
 
-JSObject* GetElementCallback(JSContext* aCx, JS::HandleValue aValue) {
-  JS::RootedValue privateValue(aCx, aValue);
-  MOZ_ASSERT(!privateValue.isObjectOrNull() && !privateValue.isUndefined());
-  LoadedScript* script = static_cast<LoadedScript*>(privateValue.toPrivate());
+JSObject* SourceElementCallback(JSContext* aCx, JS::HandleValue aPrivateValue) {
+  // NOTE: The result of this is only used by DevTools for matching sources, so
+  // it is safe to silently ignore any errors and return nullptr for them.
+
+  LoadedScript* script = static_cast<LoadedScript*>(aPrivateValue.toPrivate());
 
   if (!script->GetFetchOptions()) {
     return nullptr;
   }
 
-  JS::Rooted<JS::Value> elementValue(aCx);
-  {
-    nsCOMPtr<Element> domElement = script->GetFetchOptions()->mElement;
-    if (!domElement) {
-      return nullptr;
-    }
-
-    JSObject* globalObject =
-        domElement->OwnerDoc()->GetScopeObject()->GetGlobalJSObject();
-    JSAutoRealm ar(aCx, globalObject);
-
-    nsresult rv = nsContentUtils::WrapNative(aCx, domElement, &elementValue,
-                                             /* aAllowWrapping = */ true);
-    if (NS_FAILED(rv)) {
-      return nullptr;
-    }
+  nsCOMPtr<Element> domElement = script->GetFetchOptions()->mElement;
+  if (!domElement) {
+    return nullptr;
   }
-  return elementValue.toObjectOrNull();
+
+  JSObject* globalObject =
+      domElement->OwnerDoc()->GetScopeObject()->GetGlobalJSObject();
+  JSAutoRealm ar(aCx, globalObject);
+
+  JS::Rooted<JS::Value> elementValue(aCx);
+  nsresult rv = nsContentUtils::WrapNative(aCx, domElement, &elementValue,
+                                           /* aAllowWrapping = */ true);
+  if (NS_FAILED(rv)) {
+    return nullptr;
+  }
+
+  return &elementValue.toObject();
 }
 
 static MOZ_THREAD_LOCAL(ScriptSettingsStackEntry*) sScriptSettingsTLS;
@@ -340,7 +340,7 @@ void AutoJSAPI::InitInternal(nsIGlobalObject* aGlobalObject, JSObject* aGlobal,
   mOldWarningReporter.emplace(JS::GetWarningReporter(aCx));
 
   JS::SetWarningReporter(aCx, WarningOnlyErrorReporter);
-  JS::SetGetElementCallback(aCx, &GetElementCallback);
+  JS::SetSourceElementCallback(aCx, SourceElementCallback);
 
 #ifdef DEBUG
   if (haveException) {

js/public/CompilationAndEvaluation.h

@@ -266,8 +266,13 @@ extern JS_PUBLIC_API bool UpdateDebugMetadata(
     HandleString elementAttributeName, HandleScript introScript,
     HandleScript scriptOrModule);
 
-extern JS_PUBLIC_API void SetGetElementCallback(JSContext* cx,
-                                                JSGetElementCallback callback);
+// The debugger API exposes an optional "element" property on DebuggerSource
+// objects.  The callback defined here provides that value.  SpiderMonkey
+// doesn't particularly care about this, but within Firefox the "element" is the
+// HTML script tag for the script which DevTools can use for a better debugging
+// experience.
+extern JS_PUBLIC_API void SetSourceElementCallback(
+    JSContext* cx, JSSourceElementCallback callback);
 
 } /* namespace JS */
 

js/src/debugger/Source.cpp

@@ -397,14 +397,14 @@ struct DebuggerSourceGetElementMatcher {
 
 bool DebuggerSource::CallData::getElement() {
   DebuggerSourceGetElementMatcher matcher(cx);
+  RootedValue elementValue(cx);
   if (JSObject* element = referent.match(matcher)) {
-    args.rval().setObjectOrNull(element);
-    if (!obj->owner()->wrapDebuggeeValue(cx, args.rval())) {
+    elementValue.setObject(*element);
+    if (!obj->owner()->wrapDebuggeeValue(cx, &elementValue)) {
       return false;
     }
-  } else {
-    args.rval().setUndefined();
   }
+  args.rval().set(elementValue);
   return true;
 }
 

js/src/jsapi.h

@@ -99,8 +99,11 @@ class MOZ_RAII JS_PUBLIC_API CustomAutoRooter : private AutoGCRooter {
 /* Callbacks and their arguments. */
 
 /************************************************************************/
-using JSGetElementCallback = JSObject* (*)(JSContext* aCx,
-                                           JS::HandleValue privateValue);
+
+// Callback for the embedding to map from a ScriptSourceObject private-value to
+// an object that is exposed as the source "element" in debugger API.  This hook
+// must be infallible, but can return nullptr if no such element exists.
+using JSSourceElementCallback = JSObject* (*)(JSContext*, JS::HandleValue);
 
 using JSInterruptCallback = bool (*)(JSContext*);
 

js/src/shell/js.cpp

@@ -4717,8 +4717,8 @@ static void DestroyShellCompartmentPrivate(JSFreeOp* fop,
 static void SetWorkerContextOptions(JSContext* cx);
 static bool ShellBuildId(JS::BuildIdCharVector* buildId);
 
-JSObject* GetElementCallback(JSContext* cx, JS::HandleValue value) {
-  RootedValue privateValue(cx, value);
+static JSObject* ShellSourceElementCallback(JSContext* cx,
+                                            JS::HandleValue privateValue) {
   if (!privateValue.isObject()) {
     return nullptr;
   }
@@ -4783,7 +4783,7 @@ static void WorkerMain(WorkerInput* input) {
                                   DummyHasReleasedWrapperCallback);
   JS_InitDestroyPrincipalsCallback(cx, ShellPrincipals::destroy);
   JS_SetDestroyCompartmentCallback(cx, DestroyShellCompartmentPrivate);
-  JS::SetGetElementCallback(cx, &GetElementCallback);
+  JS::SetSourceElementCallback(cx, ShellSourceElementCallback);
 
   js::SetWindowProxyClass(cx, &ShellWindowProxyClass);
 
@@ -12421,7 +12421,7 @@ int main(int argc, char** argv) {
   JS_SetSecurityCallbacks(cx, &ShellPrincipals::securityCallbacks);
   JS_InitDestroyPrincipalsCallback(cx, ShellPrincipals::destroy);
   JS_SetDestroyCompartmentCallback(cx, DestroyShellCompartmentPrivate);
-  JS::SetGetElementCallback(cx, &GetElementCallback);
+  JS::SetSourceElementCallback(cx, ShellSourceElementCallback);
 
   js::SetWindowProxyClass(cx, &ShellWindowProxyClass);
 

js/src/vm/CompilationAndEvaluation.cpp

@@ -470,10 +470,10 @@ JS_PUBLIC_API bool JS::UpdateDebugMetadata(
   return true;
 }
 
-JS_PUBLIC_API void JS::SetGetElementCallback(JSContext* cx,
-                                             JSGetElementCallback callback) {
+JS_PUBLIC_API void JS::SetSourceElementCallback(
+    JSContext* cx, JSSourceElementCallback callback) {
   MOZ_ASSERT(cx->runtime());
-  cx->runtime()->setElementCallback(cx->runtime(), callback);
+  cx->runtime()->setSourceElementCallback(cx->runtime(), callback);
 }
 
 MOZ_NEVER_INLINE static bool ExecuteScript(JSContext* cx, HandleObject envChain,

js/src/vm/JSScript.cpp

@@ -1741,8 +1741,11 @@ JSObject* ScriptSourceObject::unwrappedElement(JSContext* cx) const {
     return nullptr;
   }
 
-  MOZ_ASSERT(cx->runtime()->getElementCallback);
-  return (*cx->runtime()->getElementCallback)(cx, privateValue);
+  if (cx->runtime()->sourceElementCallback) {
+    return (*cx->runtime()->sourceElementCallback)(cx, privateValue);
+  }
+
+  return nullptr;
 }
 
 class ScriptSource::LoadSourceMatcher {

js/src/vm/Runtime.cpp

@@ -332,9 +332,9 @@ void JSRuntime::setTelemetryCallback(
   rt->telemetryCallback = callback;
 }
 
-void JSRuntime::setElementCallback(JSRuntime* rt,
-                                   JSGetElementCallback callback) {
-  rt->getElementCallback = callback;
+void JSRuntime::setSourceElementCallback(JSRuntime* rt,
+                                         JSSourceElementCallback callback) {
+  rt->sourceElementCallback = callback;
 }
 
 void JSRuntime::setUseCounter(JSObject* obj, JSUseCounter counter) {

js/src/vm/Runtime.h

@@ -307,7 +307,7 @@ struct JSRuntime {
   /* Call this to accumulate use counter data. */
   js::MainThreadData<JSSetUseCounterCallback> useCounterCallback;
 
-  js::MainThreadData<JSGetElementCallback> getElementCallback;
+  js::MainThreadData<JSSourceElementCallback> sourceElementCallback;
 
  public:
   // Accumulates data for Firefox telemetry. |id| is the ID of a JS_TELEMETRY_*
@@ -320,7 +320,8 @@ struct JSRuntime {
   void setTelemetryCallback(JSRuntime* rt,
                             JSAccumulateTelemetryDataCallback callback);
 
-  void setElementCallback(JSRuntime* rt, JSGetElementCallback callback);
+  void setSourceElementCallback(JSRuntime* rt,
+                                JSSourceElementCallback callback);
 
   // Sets the use counter for a specific feature, measuring the presence or
   // absence of usage of a feature on a specific web page and document which