From bebec8fcb84dba6b684dfe1cc6c8a1e7741df374 Mon Sep 17 00:00:00 2001
From: "Matt A. Tobin" <email@mattatobin.com>
Date: Tue, 14 Apr 2020 21:50:13 -0400
Subject: Bug 1321284 - Crash in nsCSSFrameConstructor::GetInsertionPrevSibling
 when trying to reframe native anonymous content

* Make StyleChildrenIterator skip NAC generated by root element primary frame ancestors.
* Add nsINode::GetFlattenedTreeParentNodeForStyle.
* Add iterator class to find all restyle roots.

NOTE: Parts 1, 2, and "4.2"

Tag #1375
---
 layout/generic/nsIAnonymousContentCreator.h |  4 ++-
 layout/style/DocumentStyleRootIterator.cpp  | 41 +++++++++++++++++++++++++++++
 layout/style/DocumentStyleRootIterator.h    | 37 ++++++++++++++++++++++++++
 layout/style/moz.build                      |  2 ++
 4 files changed, 83 insertions(+), 1 deletion(-)
 create mode 100644 layout/style/DocumentStyleRootIterator.cpp
 create mode 100644 layout/style/DocumentStyleRootIterator.h

(limited to 'layout')

diff --git a/layout/generic/nsIAnonymousContentCreator.h b/layout/generic/nsIAnonymousContentCreator.h
index e7d4399b6..844b3a063 100644
--- a/layout/generic/nsIAnonymousContentCreator.h
+++ b/layout/generic/nsIAnonymousContentCreator.h
@@ -66,7 +66,9 @@ public:
    * Appends "native" anonymous children created by CreateAnonymousContent()
    * to the given content list depending on the filter.
    *
-   * @see nsIContent::GetChildren for set of values used for filter.
+   * @see nsIContent::GetChildren for set of values used for filter.  Currently,
+   *   eSkipPlaceholderContent is the only flag that any implementation of
+   *   this method heeds.
    */
   virtual void AppendAnonymousContentTo(nsTArray<nsIContent*>& aElements,
                                         uint32_t aFilter) = 0;
diff --git a/layout/style/DocumentStyleRootIterator.cpp b/layout/style/DocumentStyleRootIterator.cpp
new file mode 100644
index 000000000..af95c5c4f
--- /dev/null
+++ b/layout/style/DocumentStyleRootIterator.cpp
@@ -0,0 +1,41 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "DocumentStyleRootIterator.h"
+
+#include "nsContentUtils.h"
+
+namespace mozilla {
+
+DocumentStyleRootIterator::DocumentStyleRootIterator(nsIDocument* aDocument)
+  : mPosition(0)
+{
+  MOZ_COUNT_CTOR(DocumentStyleRootIterator);
+  if (Element* root = aDocument->GetRootElement()) {
+    mStyleRoots.AppendElement(root);
+  }
+  nsContentUtils::AppendDocumentLevelNativeAnonymousContentTo(
+      aDocument, mStyleRoots);
+}
+
+Element*
+DocumentStyleRootIterator::GetNextStyleRoot()
+{
+  for (;;) {
+    if (mPosition >= mStyleRoots.Length()) {
+      return nullptr;
+    }
+
+    nsIContent* next = mStyleRoots[mPosition];
+    ++mPosition;
+
+    if (next->IsElement()) {
+      return next->AsElement();
+    }
+  }
+}
+
+} // namespace mozilla
diff --git a/layout/style/DocumentStyleRootIterator.h b/layout/style/DocumentStyleRootIterator.h
new file mode 100644
index 000000000..7dcdc7fa1
--- /dev/null
+++ b/layout/style/DocumentStyleRootIterator.h
@@ -0,0 +1,37 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef DocumentStyleRootIterator_h
+#define DocumentStyleRootIterator_h
+
+#include "nsTArray.h"
+
+class nsIContent;
+class nsIDocument;
+
+namespace mozilla {
+
+/**
+ * DocumentStyleRootIterator traverses the roots of the document from the
+ * perspective of the Servo-backed style system.  This will first traverse
+ * the document root, followed by any document level native anonymous content.
+ */
+class DocumentStyleRootIterator
+{
+public:
+  explicit DocumentStyleRootIterator(nsIDocument* aDocument);
+  ~DocumentStyleRootIterator() { MOZ_COUNT_DTOR(DocumentStyleRootIterator); }
+
+  Element* GetNextStyleRoot();
+
+private:
+  AutoTArray<nsIContent*, 8> mStyleRoots;
+  uint32_t mPosition;
+};
+
+} // namespace mozilla
+
+#endif // DocumentStyleRootIterator_h
diff --git a/layout/style/moz.build b/layout/style/moz.build
index 3dc2a19af..40b9fd659 100644
--- a/layout/style/moz.build
+++ b/layout/style/moz.build
@@ -88,6 +88,7 @@ EXPORTS.mozilla += [
     'CSSVariableValues.h',
     'DeclarationBlock.h',
     'DeclarationBlockInlines.h',
+    'DocumentStyleRootIterator.h',
     'HandleRefPtr.h',
     'IncrementalClearCOMRuleArray.h',
     'LayerAnimationInfo.h',
@@ -151,6 +152,7 @@ UNIFIED_SOURCES += [
     'CSSVariableResolver.cpp',
     'CSSVariableValues.cpp',
     'Declaration.cpp',
+    'DocumentStyleRootIterator.cpp',
     'ErrorReporter.cpp',
     'FontFace.cpp',
     'FontFaceSet.cpp',
-- 
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