1 files changed, 58 insertions, 8 deletions

diff --git a/dom/base/nsINode.cpp b/dom/base/nsINode.cpp
index d5455e5596..6c77574df7 100644
--- a/dom/base/nsINode.cpp
+++ b/dom/base/nsINode.cpp
@@ -287,11 +287,17 @@ static const nsINode* GetClosestCommonInclusiveAncestorForRangeInSelection(
     const nsINode* aNode) {
   while (aNode &&
          !aNode->IsClosestCommonInclusiveAncestorForRangeInSelection()) {
+    const bool isNodeInShadowTree =
+        StaticPrefs::dom_shadowdom_selection_across_boundary_enabled() &&
+        aNode->IsInShadowTree();
     if (!aNode
-             ->IsDescendantOfClosestCommonInclusiveAncestorForRangeInSelection()) {
+             ->IsDescendantOfClosestCommonInclusiveAncestorForRangeInSelection() &&
+        !isNodeInShadowTree) {
       return nullptr;
     }
-    aNode = aNode->GetParentNode();
+    aNode = StaticPrefs::dom_shadowdom_selection_across_boundary_enabled()
+                ? aNode->GetParentOrShadowHostNode()
+                : aNode->GetParentNode();
   }
   return aNode;
 }
@@ -315,12 +321,12 @@ class IsItemInRangeComparator {
 
   int operator()(const AbstractRange* const aRange) const {
     int32_t cmp = nsContentUtils::ComparePoints_Deprecated(
-        &mNode, mEndOffset, aRange->GetStartContainer(), aRange->StartOffset(),
-        nullptr, mCache);
+        &mNode, mEndOffset, aRange->GetMayCrossShadowBoundaryStartContainer(),
+        aRange->MayCrossShadowBoundaryStartOffset(), nullptr, mCache);
     if (cmp == 1) {
       cmp = nsContentUtils::ComparePoints_Deprecated(
-          &mNode, mStartOffset, aRange->GetEndContainer(), aRange->EndOffset(),
-          nullptr, mCache);
+          &mNode, mStartOffset, aRange->GetMayCrossShadowBoundaryEndContainer(),
+          aRange->MayCrossShadowBoundaryEndOffset(), nullptr, mCache);
       if (cmp == -1) {
         return 0;
       }
@@ -386,6 +392,18 @@ bool nsINode::IsSelected(const uint32_t aStartOffset,
           return true;
         }
 
+        if (range->MayCrossShadowBoundary()) {
+          MOZ_ASSERT(range->IsDynamicRange(),
+                     "range->MayCrossShadowBoundary() can only return true for "
+                     "dynamic range");
+          StaticRange* crossBoundaryRange =
+              range->AsDynamicRange()->GetCrossShadowBoundaryRange();
+          MOZ_ASSERT(crossBoundaryRange);
+          if (!crossBoundaryRange->Collapsed()) {
+            return true;
+          }
+        }
+
         const AbstractRange* middlePlus1;
         const AbstractRange* middleMinus1;
         // if node end > start of middle+1, result = 1
@@ -552,7 +570,8 @@ static nsIContent* GetRootForContentSubtree(nsIContent* aContent) {
   return nsIContent::FromNode(aContent->SubtreeRoot());
 }
 
-nsIContent* nsINode::GetSelectionRootContent(PresShell* aPresShell) {
+nsIContent* nsINode::GetSelectionRootContent(PresShell* aPresShell,
+                                             bool aAllowCrossShadowBoundary) {
   NS_ENSURE_TRUE(aPresShell, nullptr);
 
   if (IsDocument()) return AsDocument()->GetRootElement();
@@ -596,7 +615,7 @@ nsIContent* nsINode::GetSelectionRootContent(PresShell* aPresShell) {
   }
 
   RefPtr<nsFrameSelection> fs = aPresShell->FrameSelection();
-  nsIContent* content = fs->GetLimiter();
+  nsCOMPtr<nsIContent> content = fs->GetLimiter();
   if (!content) {
     content = fs->GetAncestorLimiter();
     if (!content) {
@@ -616,6 +635,10 @@ nsIContent* nsINode::GetSelectionRootContent(PresShell* aPresShell) {
     // Use the host as the root.
     if (ShadowRoot* shadowRoot = ShadowRoot::FromNode(content)) {
       content = shadowRoot->GetHost();
+      if (content && aAllowCrossShadowBoundary) {
+        content = content->GetSelectionRootContent(aPresShell,
+                                                   aAllowCrossShadowBoundary);
+      }
     }
   }
 
@@ -3826,6 +3849,33 @@ void nsINode::FireNodeRemovedForChildren() {
   }
 }
 
+ShadowRoot* nsINode::GetShadowRoot() const {
+  return IsContent() ? AsContent()->GetShadowRoot() : nullptr;
+}
+
+ShadowRoot* nsINode::GetShadowRootForSelection() const {
+  if (!StaticPrefs::dom_shadowdom_selection_across_boundary_enabled()) {
+    return nullptr;
+  }
+
+  ShadowRoot* shadowRoot = GetShadowRoot();
+  if (!shadowRoot) {
+    return nullptr;
+  }
+
+  // ie. <details> and <video>
+  if (shadowRoot->IsUAWidget()) {
+    return nullptr;
+  }
+
+  // ie. <use> element
+  if (IsElement() && !AsElement()->CanAttachShadowDOM()) {
+    return nullptr;
+  }
+
+  return shadowRoot;
+}
+
 NS_IMPL_ISUPPORTS(nsNodeWeakReference, nsIWeakReference)
 
 nsNodeWeakReference::nsNodeWeakReference(nsINode* aNode)