Prevent JS execution and layout operations while DOM in inconsistent …

…state.

components/script/dom/bindings/callback.rs

@@ -4,12 +4,15 @@
 
 //! Base classes to work with IDL callbacks.
 
+use crate::dom::bindings::codegen::Bindings::WindowBinding::WindowBinding::WindowMethods;
 use crate::dom::bindings::error::{report_pending_exception, Error, Fallible};
+use crate::dom::bindings::inheritance::Castable;
 use crate::dom::bindings::reflector::DomObject;
 use crate::dom::bindings::root::{Dom, DomRoot};
 use crate::dom::bindings::settings_stack::{AutoEntryScript, AutoIncumbentScript};
 use crate::dom::bindings::utils::AsCCharPtrPtr;
 use crate::dom::globalscope::GlobalScope;
+use crate::dom::window::Window;
 use js::jsapi::Heap;
 use js::jsapi::JSAutoCompartment;
 use js::jsapi::{AddRawValueRoot, IsCallable, JSContext, JSObject};
@@ -242,6 +245,9 @@ impl CallSetup {
     #[allow(unrooted_must_root)]
     pub fn new<T: CallbackContainer>(callback: &T, handling: ExceptionHandling) -> CallSetup {
         let global = unsafe { GlobalScope::from_object(callback.callback()) };
+        if let Some(window) = global.downcast::<Window>() {
+            window.Document().ensure_safe_to_run_script_or_layout();
+        }
         let cx = global.get_cx();
 
         let aes = AutoEntryScript::new(&global);

components/script/dom/document.rs

@@ -410,6 +410,8 @@ pub struct Document {
     responsive_images: DomRefCell<Vec<Dom<HTMLImageElement>>>,
     /// Number of redirects for the document load
     redirect_count: Cell<u16>,
+    ///
+    script_and_layout_blockers: Cell<u32>,
 }
 
 #[derive(JSTraceable, MallocSizeOf)]
@@ -2695,9 +2697,27 @@ impl Document {
             fired_unload: Cell::new(false),
             responsive_images: Default::default(),
             redirect_count: Cell::new(0),
+            script_and_layout_blockers: Cell::new(0),
         }
     }
 
+    pub fn add_script_and_layout_blocker(&self) {
+        self.script_and_layout_blockers.set(
+            self.script_and_layout_blockers.get() + 1
+        );
+    }
+
+    pub fn remove_script_and_layout_blocker(&self) {
+        assert!(self.script_and_layout_blockers.get() > 0);
+        self.script_and_layout_blockers.set(
+            self.script_and_layout_blockers.get() - 1
+        );
+    }
+
+    pub fn ensure_safe_to_run_script_or_layout(&self) {
+        assert_eq!(self.script_and_layout_blockers.get(), 0);
+    }
+
     // https://dom.spec.whatwg.org/#dom-document-document
     pub fn Constructor(window: &Window) -> Fallible<DomRoot<Document>> {
         let doc = window.Document();

components/script/dom/node.rs

@@ -1504,8 +1504,11 @@ impl Node {
 
     // https://dom.spec.whatwg.org/#concept-node-adopt
     pub fn adopt(node: &Node, document: &Document) {
+        document.add_script_and_layout_blocker();
+
         // Step 1.
         let old_doc = node.owner_doc();
+        old_doc.add_script_and_layout_blocker();
         // Step 2.
         node.remove_self();
         // Step 3.
@@ -1530,6 +1533,9 @@ impl Node {
                 vtable_for(&descendant).adopting_steps(&old_doc);
             }
         }
+
+        old_doc.remove_script_and_layout_blocker();
+        document.remove_script_and_layout_blocker();
     }
 
     // https://dom.spec.whatwg.org/#concept-node-ensure-pre-insertion-validity
@@ -1685,6 +1691,7 @@ impl Node {
         child: Option<&Node>,
         suppress_observers: SuppressObserver,
     ) {
+        node.owner_doc().add_script_and_layout_blocker();
         debug_assert!(&*node.owner_doc() == &*parent.owner_doc());
         debug_assert!(child.map_or(true, |child| Some(parent) == child.GetParentNode().r()));
 
@@ -1774,10 +1781,12 @@ impl Node {
             };
             MutationObserver::queue_a_mutation_record(&parent, mutation);
         }
+        node.owner_doc().remove_script_and_layout_blocker();
     }
 
     // https://dom.spec.whatwg.org/#concept-node-replace-all
     pub fn replace_all(node: Option<&Node>, parent: &Node) {
+        parent.owner_doc().add_script_and_layout_blocker();
         // Step 1.
         if let Some(node) = node {
             Node::adopt(node, &*parent.owner_doc());
@@ -1819,6 +1828,7 @@ impl Node {
             };
             MutationObserver::queue_a_mutation_record(&parent, mutation);
         }
+        parent.owner_doc().remove_script_and_layout_blocker();
     }
 
     // https://dom.spec.whatwg.org/#concept-node-pre-remove
@@ -1839,6 +1849,7 @@ impl Node {
 
     // https://dom.spec.whatwg.org/#concept-node-remove
     fn remove(node: &Node, parent: &Node, suppress_observers: SuppressObserver) {
+        parent.owner_doc().add_script_and_layout_blocker();
         assert!(
             node.GetParentNode()
                 .map_or(false, |node_parent| &*node_parent == parent)
@@ -1884,6 +1895,7 @@ impl Node {
             };
             MutationObserver::queue_a_mutation_record(&parent, mutation);
         }
+        parent.owner_doc().remove_script_and_layout_blocker();
     }
 
     // https://dom.spec.whatwg.org/#concept-node-clone

components/script/dom/window.rs

@@ -1361,6 +1361,7 @@ impl Window {
     /// Returns true if layout actually happened, false otherwise.
     #[allow(unsafe_code)]
     pub fn force_reflow(&self, reflow_goal: ReflowGoal, reason: ReflowReason) -> bool {
+        self.Document().ensure_safe_to_run_script_or_layout();
         // Check if we need to unsuppress reflow. Note that this needs to be
         // *before* any early bailouts, or reflow might never be unsuppresed!
         match reason {
@@ -1497,6 +1498,7 @@ impl Window {
     /// may happen in the only case a query reflow may bail out, that is, if the
     /// viewport size is not present). See #11223 for an example of that.
     pub fn reflow(&self, reflow_goal: ReflowGoal, reason: ReflowReason) -> bool {
+        self.Document().ensure_safe_to_run_script_or_layout();
         let for_display = reflow_goal == ReflowGoal::Full;
 
         let mut issued_reflow = false;