nsresult
nsXBLProtoImpl::InstallImplementation(nsXBLPrototypeBinding* aPrototypeBinding,
nsXBLBinding* aBinding)
{
// This function is called to install a concrete implementation on a bound element using
// this prototype implementation as a guide. The prototype implementation is compiled lazily,
// so for the first bound element that needs a concrete implementation, we also build the
// prototype implementation.
if (!mMembers && !mFields) // Constructor and destructor also live in mMembers
return NS_OK; // Nothing to do, so let's not waste time.
// If the way this gets the script context changes, fix
// nsXBLProtoImplAnonymousMethod::Execute
nsIDocument* document = aBinding->GetBoundElement()->OwnerDoc();
nsCOMPtr<nsIScriptGlobalObject> global = do_QueryInterface(document->GetScopeObject());
if (!global) return NS_OK;
nsCOMPtr<nsIScriptContext> context = global->GetContext();
if (!context) return NS_OK;
JSContext* cx = context->GetNativeContext();
AutoCxPusher pusher(cx);
// InitTarget objects gives us back the JS object that represents the bound element and the
// class object in the bound document that represents the concrete version of this implementation.
// This function also has the side effect of building up the prototype implementation if it has
// not been built already.
JS::Rooted<JSObject*> targetClassObject(cx, nullptr);
bool targetObjectIsNew = false;
nsresult rv = InitTargetObjects(aPrototypeBinding,
aBinding->GetBoundElement(),
&targetClassObject,
&targetObjectIsNew);
NS_ENSURE_SUCCESS(rv, rv); // kick out if we were unable to properly intialize our target objects
MOZ_ASSERT(targetClassObject);
// Stash a strong reference to the JSClass in the binding.
aBinding->SetJSClass(nsXBLJSClass::fromJSClass(JS_GetClass(targetClassObject)));
// If the prototype already existed, we don't need to install anything. return early.
if (!targetObjectIsNew)
return NS_OK;
// We want to define the canonical set of members in a safe place. If we're
// using a separate XBL scope, we want to define them there first (so that
// they'll be available for Xray lookups, among other things), and then copy
// the properties to the content-side prototype as needed. We don't need to
// bother about the field accessors here, since we don't use/support those
// for in-content bindings.
// First, start by entering the compartment of the XBL scope. This may or may
// not be the same compartment as globalObject.
JS::Rooted<JSObject*> globalObject(cx,
GetGlobalForObjectCrossCompartment(targetClassObject));
JS::Rooted<JSObject*> scopeObject(cx, xpc::GetXBLScopeOrGlobal(cx, globalObject));
NS_ENSURE_TRUE(scopeObject, NS_ERROR_OUT_OF_MEMORY);
JSAutoCompartment ac(cx, scopeObject);
// If they're different, create our safe holder object in the XBL scope.
JS::Rooted<JSObject*> propertyHolder(cx);
if (scopeObject != globalObject) {
// This is just a property holder, so it doesn't need any special JSClass.
propertyHolder = JS_NewObjectWithGivenProto(cx, nullptr, JS::NullPtr(), scopeObject);
NS_ENSURE_TRUE(propertyHolder, NS_ERROR_OUT_OF_MEMORY);
// Define it as a property on the scopeObject, using the same name used on
// the content side.
bool ok = JS_DefineProperty(cx, scopeObject,
js::GetObjectClass(targetClassObject)->name,
JS::ObjectValue(*propertyHolder), JS_PropertyStub,
JS_StrictPropertyStub,
JSPROP_PERMANENT | JSPROP_READONLY);
NS_ENSURE_TRUE(ok, NS_ERROR_UNEXPECTED);
} else {
propertyHolder = targetClassObject;
}
// Walk our member list and install each one in turn on the XBL scope object.
for (nsXBLProtoImplMember* curr = mMembers;
curr;
curr = curr->GetNext())
curr->InstallMember(cx, propertyHolder);
// Now, if we're using a separate XBL scope, enter the compartment of the
// bound node and copy exposable properties to the prototype there. This
// rewraps them appropriately, which should result in cross-compartment
// function wrappers.
if (propertyHolder != targetClassObject) {
AssertSameCompartment(propertyHolder, scopeObject);
AssertSameCompartment(targetClassObject, globalObject);
for (nsXBLProtoImplMember* curr = mMembers; curr; curr = curr->GetNext()) {
if (curr->ShouldExposeToUntrustedContent()) {
JS::Rooted<jsid> id(cx);
JS::TwoByteChars chars(curr->GetName(), NS_strlen(curr->GetName()));
bool ok = JS_CharsToId(cx, chars, &id);
NS_ENSURE_TRUE(ok, NS_ERROR_UNEXPECTED);
JS_CopyPropertyFrom(cx, id, targetClassObject, propertyHolder);
NS_ENSURE_TRUE(ok, NS_ERROR_UNEXPECTED);
}
}
}
// From here on out, work in the scope of the bound element.
JSAutoCompartment ac2(cx, targetClassObject);
// Install all of our field accessors.
for (nsXBLProtoImplField* curr = mFields;
curr;
curr = curr->GetNext())
curr->InstallAccessors(cx, targetClassObject);
return NS_OK;
}
nsresult
nsXBLProtoImpl::InstallImplementation(nsXBLPrototypeBinding* aPrototypeBinding,
nsXBLBinding* aBinding)
{
// This function is called to install a concrete implementation on a bound element using
// this prototype implementation as a guide. The prototype implementation is compiled lazily,
// so for the first bound element that needs a concrete implementation, we also build the
// prototype implementation.
if (!mMembers && !mFields) // Constructor and destructor also live in mMembers
return NS_OK; // Nothing to do, so let's not waste time.
// If the way this gets the script context changes, fix
// nsXBLProtoImplAnonymousMethod::Execute
nsIDocument* document = aBinding->GetBoundElement()->OwnerDoc();
// This sometimes gets called when we have no outer window and if we don't
// catch this, we get leaks during crashtests and reftests.
if (NS_WARN_IF(!document->GetWindow())) {
return NS_OK;
}
// |propertyHolder| (below) can be an existing object, so in theory we might
// hit something that could end up running script. We never want that to
// happen here, so we use an AutoJSAPI instead of an AutoEntryScript.
dom::AutoJSAPI jsapi;
if (NS_WARN_IF(!jsapi.Init(document->GetScopeObject()))) {
return NS_OK;
}
JSContext* cx = jsapi.cx();
// InitTarget objects gives us back the JS object that represents the bound element and the
// class object in the bound document that represents the concrete version of this implementation.
// This function also has the side effect of building up the prototype implementation if it has
// not been built already.
JS::Rooted<JSObject*> targetClassObject(cx, nullptr);
bool targetObjectIsNew = false;
nsresult rv = InitTargetObjects(aPrototypeBinding,
aBinding->GetBoundElement(),
&targetClassObject,
&targetObjectIsNew);
NS_ENSURE_SUCCESS(rv, rv); // kick out if we were unable to properly intialize our target objects
MOZ_ASSERT(targetClassObject);
// If the prototype already existed, we don't need to install anything. return early.
if (!targetObjectIsNew)
return NS_OK;
// We want to define the canonical set of members in a safe place. If we're
// using a separate XBL scope, we want to define them there first (so that
// they'll be available for Xray lookups, among other things), and then copy
// the properties to the content-side prototype as needed. We don't need to
// bother about the field accessors here, since we don't use/support those
// for in-content bindings.
// First, start by entering the compartment of the XBL scope. This may or may
// not be the same compartment as globalObject.
JSAddonId* addonId = MapURIToAddonID(aPrototypeBinding->BindingURI());
JS::Rooted<JSObject*> globalObject(cx,
GetGlobalForObjectCrossCompartment(targetClassObject));
JS::Rooted<JSObject*> scopeObject(cx, xpc::GetScopeForXBLExecution(cx, globalObject, addonId));
NS_ENSURE_TRUE(scopeObject, NS_ERROR_OUT_OF_MEMORY);
JSAutoCompartment ac(cx, scopeObject);
// Determine the appropriate property holder.
//
// Note: If |targetIsNew| is false, we'll early-return above. However, that only
// tells us if the content-side object is new, which may be the case even if
// we've already set up the binding on the XBL side. For example, if we apply
// a binding #foo to a <span> when we've already applied it to a <div>, we'll
// end up with a different content prototype, but we'll already have a property
// holder called |foo| in the XBL scope. Check for that to avoid wasteful and
// weird property holder duplication.
const char* className = aPrototypeBinding->ClassName().get();
JS::Rooted<JSObject*> propertyHolder(cx);
JS::Rooted<JSPropertyDescriptor> existingHolder(cx);
if (scopeObject != globalObject &&
!JS_GetOwnPropertyDescriptor(cx, scopeObject, className, &existingHolder)) {
return NS_ERROR_FAILURE;
}
bool propertyHolderIsNew = !existingHolder.object() || !existingHolder.value().isObject();
if (!propertyHolderIsNew) {
propertyHolder = &existingHolder.value().toObject();
} else if (scopeObject != globalObject) {
// This is just a property holder, so it doesn't need any special JSClass.
propertyHolder = JS_NewObjectWithGivenProto(cx, nullptr, JS::NullPtr(), scopeObject);
NS_ENSURE_TRUE(propertyHolder, NS_ERROR_OUT_OF_MEMORY);
// Define it as a property on the scopeObject, using the same name used on
// the content side.
bool ok = JS_DefineProperty(cx, scopeObject, className, propertyHolder,
JSPROP_PERMANENT | JSPROP_READONLY,
JS_PropertyStub, JS_StrictPropertyStub);
NS_ENSURE_TRUE(ok, NS_ERROR_UNEXPECTED);
} else {
propertyHolder = targetClassObject;
}
// Walk our member list and install each one in turn on the XBL scope object.
if (propertyHolderIsNew) {
for (nsXBLProtoImplMember* curr = mMembers;
curr;
curr = curr->GetNext())
curr->InstallMember(cx, propertyHolder);
}
// Now, if we're using a separate XBL scope, enter the compartment of the
// bound node and copy exposable properties to the prototype there. This
// rewraps them appropriately, which should result in cross-compartment
// function wrappers.
if (propertyHolder != targetClassObject) {
AssertSameCompartment(propertyHolder, scopeObject);
AssertSameCompartment(targetClassObject, globalObject);
bool inContentXBLScope = xpc::IsInContentXBLScope(scopeObject);
for (nsXBLProtoImplMember* curr = mMembers; curr; curr = curr->GetNext()) {
if (!inContentXBLScope || curr->ShouldExposeToUntrustedContent()) {
JS::Rooted<jsid> id(cx);
JS::TwoByteChars chars(curr->GetName(), NS_strlen(curr->GetName()));
bool ok = JS_CharsToId(cx, chars, &id);
NS_ENSURE_TRUE(ok, NS_ERROR_UNEXPECTED);
bool found;
ok = JS_HasPropertyById(cx, propertyHolder, id, &found);
NS_ENSURE_TRUE(ok, NS_ERROR_UNEXPECTED);
if (!found) {
// Some members don't install anything in InstallMember (e.g.,
// nsXBLProtoImplAnonymousMethod). We need to skip copying in
// those cases.
continue;
}
ok = JS_CopyPropertyFrom(cx, id, targetClassObject, propertyHolder);
NS_ENSURE_TRUE(ok, NS_ERROR_UNEXPECTED);
}
}
}
// From here on out, work in the scope of the bound element.
JSAutoCompartment ac2(cx, targetClassObject);
// Install all of our field accessors.
for (nsXBLProtoImplField* curr = mFields;
curr;
curr = curr->GetNext())
curr->InstallAccessors(cx, targetClassObject);
return NS_OK;
}