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/* -*- 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
#include "IDTracker.h"
#include "mozilla/Encoding.h"
#include "mozilla/dom/Document.h"
#include "mozilla/dom/DocumentOrShadowRoot.h"
#include "mozilla/dom/ShadowRoot.h"
#include "nsAtom.h"
#include "nsContentUtils.h"
#include "nsIURI.h"
#include "nsIReferrerInfo.h"
#include "nsEscape.h"
#include "nsCycleCollectionParticipant.h"
#include "nsStringFwd.h"
namespace mozilla::dom {
static Element* LookupElement(DocumentOrShadowRoot& aDocOrShadow,
const nsAString& aRef, bool aReferenceImage) {
if (aReferenceImage) {
return aDocOrShadow.LookupImageElement(aRef);
}
return aDocOrShadow.GetElementById(aRef);
}
static DocumentOrShadowRoot* FindTreeToWatch(nsIContent& aContent,
const nsAString& aID,
bool aReferenceImage) {
ShadowRoot* shadow = aContent.GetContainingShadow();
// We allow looking outside an <svg:use> shadow tree for backwards compat.
while (shadow && shadow->Host()->IsSVGElement(nsGkAtoms::use)) {
// <svg:use> shadow trees are immutable, so we can just early-out if we find
// our relevant element instead of having to support watching multiple
// trees.
if (LookupElement(*shadow, aID, aReferenceImage)) {
return shadow;
}
shadow = shadow->Host()->GetContainingShadow();
}
if (shadow) {
return shadow;
}
return aContent.OwnerDoc();
}
IDTracker::IDTracker() = default;
IDTracker::~IDTracker() { Unlink(); }
void IDTracker::ResetToURIFragmentID(nsIContent* aFromContent, nsIURI* aURI,
nsIReferrerInfo* aReferrerInfo,
bool aWatch, bool aReferenceImage) {
MOZ_ASSERT(aFromContent,
"ResetToURIFragmentID() expects non-null content pointer");
Unlink();
if (!aURI) return;
nsAutoCString refPart;
aURI->GetRef(refPart);
// Unescape %-escapes in the reference. The result will be in the
// document charset, hopefully...
NS_UnescapeURL(refPart);
// Get the thing to observe changes to.
Document* doc = aFromContent->OwnerDoc();
auto encoding = doc->GetDocumentCharacterSet();
nsAutoString ref;
nsresult rv = encoding->DecodeWithoutBOMHandling(refPart, ref);
if (NS_FAILED(rv) || ref.IsEmpty()) {
return;
}
if (aFromContent->IsInNativeAnonymousSubtree()) {
// This happens, for example, if aFromContent is part of the content
// inserted by a call to Document::InsertAnonymousContent, which we
// also want to handle. (It also happens for other native anonymous content
// etc.)
Element* anonRoot =
doc->GetAnonRootIfInAnonymousContentContainer(aFromContent);
if (anonRoot) {
mElement = nsContentUtils::MatchElementId(anonRoot, ref);
// We don't have watching working yet for anonymous content, so bail out
// here.
return;
}
}
bool isEqualExceptRef;
rv = aURI->EqualsExceptRef(doc->GetDocumentURI(), &isEqualExceptRef);
DocumentOrShadowRoot* docOrShadow;
if (NS_FAILED(rv) || !isEqualExceptRef) {
RefPtr<Document::ExternalResourceLoad> load;
doc = doc->RequestExternalResource(aURI, aReferrerInfo, aFromContent,
getter_AddRefs(load));
docOrShadow = doc;
if (!doc) {
if (!load || !aWatch) {
// Nothing will ever happen here
return;
}
DocumentLoadNotification* observer =
new DocumentLoadNotification(this, ref);
mPendingNotification = observer;
load->AddObserver(observer);
// Keep going so we set up our watching stuff a bit
}
} else {
docOrShadow = FindTreeToWatch(*aFromContent, ref, aReferenceImage);
}
if (aWatch) {
mWatchID = NS_Atomize(ref);
}
mReferencingImage = aReferenceImage;
HaveNewDocumentOrShadowRoot(docOrShadow, aWatch, ref);
}
void IDTracker::ResetWithLocalRef(Element& aFrom, const nsAString& aLocalRef,
bool aWatch) {
MOZ_ASSERT(nsContentUtils::IsLocalRefURL(aLocalRef));
auto ref = Substring(aLocalRef, 1);
if (ref.IsEmpty()) {
Unlink();
return;
}
nsAutoCString utf8Ref;
if (!AppendUTF16toUTF8(ref, utf8Ref, mozilla::fallible)) {
Unlink();
return;
}
// Only unescape ASCII characters; if we were to unescape arbitrary bytes,
// we'd potentially end up with invalid UTF-8.
nsAutoCString unescaped;
bool appended;
if (NS_FAILED(NS_UnescapeURL(utf8Ref.BeginReading(), utf8Ref.Length(),
esc_OnlyASCII | esc_AlwaysCopy, unescaped,
appended, mozilla::fallible))) {
Unlink();
return;
}
RefPtr<nsAtom> idAtom = NS_Atomize(unescaped);
ResetWithID(aFrom, idAtom, aWatch);
}
void IDTracker::ResetWithID(Element& aFrom, nsAtom* aID, bool aWatch) {
MOZ_ASSERT(aID);
Unlink();
if (aID->IsEmpty()) {
return;
}
if (aWatch) {
mWatchID = aID;
}
mReferencingImage = false;
nsDependentAtomString str(aID);
DocumentOrShadowRoot* docOrShadow =
FindTreeToWatch(aFrom, str, /* aReferenceImage = */ false);
HaveNewDocumentOrShadowRoot(docOrShadow, aWatch, str);
}
void IDTracker::HaveNewDocumentOrShadowRoot(DocumentOrShadowRoot* aDocOrShadow,
bool aWatch, const nsString& aRef) {
if (aWatch) {
mWatchDocumentOrShadowRoot = nullptr;
if (aDocOrShadow) {
mWatchDocumentOrShadowRoot = &aDocOrShadow->AsNode();
mElement = aDocOrShadow->AddIDTargetObserver(mWatchID, Observe, this,
mReferencingImage);
}
return;
}
if (!aDocOrShadow) {
return;
}
if (Element* e = LookupElement(*aDocOrShadow, aRef, mReferencingImage)) {
mElement = e;
}
}
void IDTracker::Traverse(nsCycleCollectionTraversalCallback* aCB) {
NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(*aCB, "mWatchDocumentOrShadowRoot");
aCB->NoteXPCOMChild(mWatchDocumentOrShadowRoot);
NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(*aCB, "mElement");
aCB->NoteXPCOMChild(mElement);
}
void IDTracker::Unlink() {
if (mWatchID) {
if (DocumentOrShadowRoot* docOrShadow = GetWatchDocOrShadowRoot()) {
docOrShadow->RemoveIDTargetObserver(mWatchID, Observe, this,
mReferencingImage);
}
}
if (mPendingNotification) {
mPendingNotification->Clear();
mPendingNotification = nullptr;
}
mWatchDocumentOrShadowRoot = nullptr;
mWatchID = nullptr;
mElement = nullptr;
mReferencingImage = false;
}
void IDTracker::ElementChanged(Element* aFrom, Element* aTo) { mElement = aTo; }
bool IDTracker::Observe(Element* aOldElement, Element* aNewElement,
void* aData) {
IDTracker* p = static_cast<IDTracker*>(aData);
if (p->mPendingNotification) {
p->mPendingNotification->SetTo(aNewElement);
} else {
NS_ASSERTION(aOldElement == p->mElement, "Failed to track content!");
ChangeNotification* watcher =
new ChangeNotification(p, aOldElement, aNewElement);
p->mPendingNotification = watcher;
nsContentUtils::AddScriptRunner(watcher);
}
bool keepTracking = p->IsPersistent();
if (!keepTracking) {
p->mWatchDocumentOrShadowRoot = nullptr;
p->mWatchID = nullptr;
}
return keepTracking;
}
IDTracker::ChangeNotification::ChangeNotification(IDTracker* aTarget,
Element* aFrom, Element* aTo)
: mozilla::Runnable("IDTracker::ChangeNotification"),
Notification(aTarget),
mFrom(aFrom),
mTo(aTo) {}
IDTracker::ChangeNotification::~ChangeNotification() = default;
void IDTracker::ChangeNotification::SetTo(Element* aTo) { mTo = aTo; }
void IDTracker::ChangeNotification::Clear() {
Notification::Clear();
mFrom = nullptr;
mTo = nullptr;
}
NS_IMPL_ISUPPORTS_INHERITED0(IDTracker::ChangeNotification, mozilla::Runnable)
NS_IMPL_ISUPPORTS(IDTracker::DocumentLoadNotification, nsIObserver)
NS_IMETHODIMP
IDTracker::DocumentLoadNotification::Observe(nsISupports* aSubject,
const char* aTopic,
const char16_t* aData) {
NS_ASSERTION(!strcmp(aTopic, "external-resource-document-created"),
"Unexpected topic");
if (mTarget) {
nsCOMPtr<Document> doc = do_QueryInterface(aSubject);
mTarget->mPendingNotification = nullptr;
NS_ASSERTION(!mTarget->mElement, "Why do we have content here?");
// If we got here, that means we had Reset*() called with
// aWatch == true. So keep watching if IsPersistent().
mTarget->HaveNewDocumentOrShadowRoot(doc, mTarget->IsPersistent(), mRef);
mTarget->ElementChanged(nullptr, mTarget->mElement);
}
return NS_OK;
}
DocumentOrShadowRoot* IDTracker::GetWatchDocOrShadowRoot() const {
if (!mWatchDocumentOrShadowRoot) {
return nullptr;
}
MOZ_ASSERT(mWatchDocumentOrShadowRoot->IsDocument() ||
mWatchDocumentOrShadowRoot->IsShadowRoot());
if (ShadowRoot* shadow = ShadowRoot::FromNode(*mWatchDocumentOrShadowRoot)) {
return shadow;
}
return mWatchDocumentOrShadowRoot->AsDocument();
}
} // namespace mozilla::dom