dom/base/IDTracker.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "IDTracker.h"
   8
   9 #include "mozilla/Encoding.h"
  10 #include "nsContentUtils.h"
  11 #include "nsIURI.h"
  12 #include "nsBindingManager.h"
  13 #include "nsEscape.h"
  14 #include "nsXBLPrototypeBinding.h"
  15 #include "nsCycleCollectionParticipant.h"
  16
  17 namespace mozilla {
  18 namespace dom {
  19
  20 static DocumentOrShadowRoot* DocOrShadowFromContent(nsIContent& aContent) {
  21   ShadowRoot* shadow = aContent.GetContainingShadow();
  22
  23   // We never look in <svg:use> shadow trees, for backwards compat.
  24   while (shadow && shadow->Host()->IsSVGElement(nsGkAtoms::use)) {
  25     shadow = shadow->Host()->GetContainingShadow();
  26   }
  27
  28   if (shadow) {
  29     return shadow;
  30   }
  31
  32   return aContent.OwnerDoc();
  33 }
  34
  35 void IDTracker::ResetToURIFragmentID(nsIContent* aFromContent, nsIURI* aURI,
  36                                      nsIURI* aReferrer,
  37                                      uint32_t aReferrerPolicy, bool aWatch,
  38                                      bool aReferenceImage) {
  39   MOZ_ASSERT(aFromContent,
  40              "ResetToURIFragmentID() expects non-null content pointer");
  41
  42   Unlink();
  43
  44   if (!aURI) return;
  45
  46   nsAutoCString refPart;
  47   aURI->GetRef(refPart);
  48   // Unescape %-escapes in the reference. The result will be in the
  49   // document charset, hopefully...
  50   NS_UnescapeURL(refPart);
  51
  52   // Get the thing to observe changes to.
  53   Document* doc = aFromContent->OwnerDoc();
  54   DocumentOrShadowRoot* docOrShadow = DocOrShadowFromContent(*aFromContent);
  55   auto encoding = doc->GetDocumentCharacterSet();
  56
  57   nsAutoString ref;
  58   nsresult rv = encoding->DecodeWithoutBOMHandling(refPart, ref);
  59   if (NS_FAILED(rv) || ref.IsEmpty()) {
  60     return;
  61   }
  62   rv = NS_OK;
  63
  64   nsIContent* bindingParent = aFromContent->GetBindingParent();
  65   if (bindingParent && !aFromContent->IsInShadowTree()) {
  66     nsXBLBinding* binding = bindingParent->GetXBLBinding();
  67     if (!binding) {
  68       // This happens, for example, if aFromContent is part of the content
  69       // inserted by a call to Document::InsertAnonymousContent, which we
  70       // also want to handle.  (It also happens for <use>'s anonymous
  71       // content etc.)
  72       Element* anonRoot =
  73           doc->GetAnonRootIfInAnonymousContentContainer(aFromContent);
  74       if (anonRoot) {
  75         mElement = nsContentUtils::MatchElementId(anonRoot, ref);
  76         // We don't have watching working yet for anonymous content, so bail out
  77         // here.
  78         return;
  79       }
  80     } else {
  81       bool isEqualExceptRef;
  82       rv = aURI->EqualsExceptRef(binding->PrototypeBinding()->DocURI(),
  83                                  &isEqualExceptRef);
  84       if (NS_SUCCEEDED(rv) && isEqualExceptRef) {
  85         // XXX sXBL/XBL2 issue
  86         // Our content is an anonymous XBL element from a binding inside the
  87         // same document that the referenced URI points to. In order to avoid
  88         // the risk of ID collisions we restrict ourselves to anonymous
  89         // elements from this binding; specifically, URIs that are relative to
  90         // the binding document should resolve to the copy of the target
  91         // element that has been inserted into the bound document.
  92         // If the URI points to a different document we don't need this
  93         // restriction.
  94         nsINodeList* anonymousChildren =
  95             doc->BindingManager()->GetAnonymousNodesFor(bindingParent);
  96
  97         if (anonymousChildren) {
  98           uint32_t length = anonymousChildren->Length();
  99           for (uint32_t i = 0; i < length && !mElement; ++i) {
 100             mElement =
 101                 nsContentUtils::MatchElementId(anonymousChildren->Item(i), ref);
 102           }
 103         }
 104
 105         // We don't have watching working yet for XBL, so bail out here.
 106         return;
 107       }
 108     }
 109   }
 110
 111   bool isEqualExceptRef;
 112   rv = aURI->EqualsExceptRef(doc->GetDocumentURI(), &isEqualExceptRef);
 113   if (NS_FAILED(rv) || !isEqualExceptRef) {
 114     RefPtr<Document::ExternalResourceLoad> load;
 115     doc = doc->RequestExternalResource(aURI, aReferrer, aReferrerPolicy,
 116                                        aFromContent, getter_AddRefs(load));
 117     docOrShadow = doc;
 118     if (!doc) {
 119       if (!load || !aWatch) {
 120         // Nothing will ever happen here
 121         return;
 122       }
 123
 124       DocumentLoadNotification* observer =
 125           new DocumentLoadNotification(this, ref);
 126       mPendingNotification = observer;
 127       load->AddObserver(observer);
 128       // Keep going so we set up our watching stuff a bit
 129     }
 130   }
 131
 132   if (aWatch) {
 133     mWatchID = NS_Atomize(ref);
 134   }
 135
 136   mReferencingImage = aReferenceImage;
 137   HaveNewDocumentOrShadowRoot(docOrShadow, aWatch, ref);
 138 }
 139
 140 void IDTracker::ResetWithID(Element& aFrom, nsAtom* aID, bool aWatch) {
 141   MOZ_ASSERT(aID);
 142
 143   if (aWatch) {
 144     mWatchID = aID;
 145   }
 146
 147   mReferencingImage = false;
 148
 149   DocumentOrShadowRoot* docOrShadow = DocOrShadowFromContent(aFrom);
 150   HaveNewDocumentOrShadowRoot(docOrShadow, aWatch, nsDependentAtomString(aID));
 151 }
 152
 153 void IDTracker::HaveNewDocumentOrShadowRoot(DocumentOrShadowRoot* aDocOrShadow,
 154                                             bool aWatch, const nsString& aRef) {
 155   if (aWatch) {
 156     mWatchDocumentOrShadowRoot = nullptr;
 157     if (aDocOrShadow) {
 158       mWatchDocumentOrShadowRoot = &aDocOrShadow->AsNode();
 159       mElement = aDocOrShadow->AddIDTargetObserver(mWatchID, Observe, this,
 160                                                    mReferencingImage);
 161     }
 162     return;
 163   }
 164
 165   if (!aDocOrShadow) {
 166     return;
 167   }
 168
 169   Element* e = mReferencingImage ? aDocOrShadow->LookupImageElement(aRef)
 170                                  : aDocOrShadow->GetElementById(aRef);
 171   if (e) {
 172     mElement = e;
 173   }
 174 }
 175
 176 void IDTracker::Traverse(nsCycleCollectionTraversalCallback* aCB) {
 177   NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(*aCB, "mWatchDocumentOrShadowRoot");
 178   aCB->NoteXPCOMChild(mWatchDocumentOrShadowRoot);
 179   NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(*aCB, "mElement");
 180   aCB->NoteXPCOMChild(mElement);
 181 }
 182
 183 void IDTracker::Unlink() {
 184   if (mWatchID) {
 185     if (DocumentOrShadowRoot* docOrShadow = GetWatchDocOrShadowRoot()) {
 186       docOrShadow->RemoveIDTargetObserver(mWatchID, Observe, this,
 187                                           mReferencingImage);
 188     }
 189   }
 190   if (mPendingNotification) {
 191     mPendingNotification->Clear();
 192     mPendingNotification = nullptr;
 193   }
 194   mWatchDocumentOrShadowRoot = nullptr;
 195   mWatchID = nullptr;
 196   mElement = nullptr;
 197   mReferencingImage = false;
 198 }
 199
 200 bool IDTracker::Observe(Element* aOldElement, Element* aNewElement,
 201                         void* aData) {
 202   IDTracker* p = static_cast<IDTracker*>(aData);
 203   if (p->mPendingNotification) {
 204     p->mPendingNotification->SetTo(aNewElement);
 205   } else {
 206     NS_ASSERTION(aOldElement == p->mElement, "Failed to track content!");
 207     ChangeNotification* watcher =
 208         new ChangeNotification(p, aOldElement, aNewElement);
 209     p->mPendingNotification = watcher;
 210     nsContentUtils::AddScriptRunner(watcher);
 211   }
 212   bool keepTracking = p->IsPersistent();
 213   if (!keepTracking) {
 214     p->mWatchDocumentOrShadowRoot = nullptr;
 215     p->mWatchID = nullptr;
 216   }
 217   return keepTracking;
 218 }
 219
 220 NS_IMPL_ISUPPORTS_INHERITED0(IDTracker::ChangeNotification, mozilla::Runnable)
 221 NS_IMPL_ISUPPORTS(IDTracker::DocumentLoadNotification, nsIObserver)
 222
 223 NS_IMETHODIMP
 224 IDTracker::DocumentLoadNotification::Observe(nsISupports* aSubject,
 225                                              const char* aTopic,
 226                                              const char16_t* aData) {
 227   NS_ASSERTION(PL_strcmp(aTopic, "external-resource-document-created") == 0,
 228                "Unexpected topic");
 229   if (mTarget) {
 230     nsCOMPtr<Document> doc = do_QueryInterface(aSubject);
 231     mTarget->mPendingNotification = nullptr;
 232     NS_ASSERTION(!mTarget->mElement, "Why do we have content here?");
 233     // If we got here, that means we had Reset*() called with
 234     // aWatch == true.  So keep watching if IsPersistent().
 235     mTarget->HaveNewDocumentOrShadowRoot(doc, mTarget->IsPersistent(), mRef);
 236     mTarget->ElementChanged(nullptr, mTarget->mElement);
 237   }
 238   return NS_OK;
 239 }
 240
 241 }  // namespace dom
 242 }  // namespace mozilla