Quelle HTMLLinkElement.cpp Sprache: C

/* -*- 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 "mozilla/dom/HTMLLinkElement.h"

#include "mozilla/AsyncEventDispatcher.h"
#include "mozilla/Attributes.h"
#include "mozilla/Components.h"
#include "mozilla/EventDispatcher.h"
#include "mozilla/MemoryReporting.h"
#include "mozilla/Preferences.h"
#include "mozilla/StaticPrefs_dom.h"
#include "mozilla/StaticPrefs_network.h"
#include "mozilla/dom/BindContext.h"
#include "mozilla/dom/DocumentInlines.h"
#include "mozilla/dom/HTMLLinkElementBinding.h"
#include "mozilla/dom/HTMLDNSPrefetch.h"
#include "mozilla/dom/ReferrerInfo.h"
#include "mozilla/dom/ScriptLoader.h"
#include "nsContentUtils.h"
#include "nsDOMTokenList.h"
#include "nsGenericHTMLElement.h"
#include "nsGkAtoms.h"
#include "nsIContentInlines.h"
#include "mozilla/dom/Document.h"
#include "nsINode.h"
#include "nsIPrefetchService.h"
#include "nsISizeOf.h"
#include "nsPIDOMWindow.h"
#include "nsReadableUtils.h"
#include "nsStyleConsts.h"
#include "nsUnicharUtils.h"
#include "nsWindowSizes.h"
#include "nsIContentPolicy.h"
#include "nsMimeTypes.h"
#include "imgLoader.h"
#include "MediaContainerType.h"
#include "DecoderDoctorDiagnostics.h"
#include "DecoderTraits.h"
#include "MediaList.h"
#include "nsAttrValueInlines.h"

NS_IMPL_NS_NEW_HTML_ELEMENT(Link)

namespace mozilla::dom {

HTMLLinkElement::HTMLLinkElement(
    already_AddRefed<mozilla::dom::NodeInfo>&& aNodeInfo)
    : nsGenericHTMLElement(std::move(aNodeInfo)) {}

HTMLLinkElement::~HTMLLinkElement() { SupportsDNSPrefetch::Destroyed(*this); }

NS_IMPL_CYCLE_COLLECTION_CLASS(HTMLLinkElement)

NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(HTMLLinkElement,
                                                  nsGenericHTMLElement)
  tmp->LinkStyle::Traverse(cb);
  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mRelList)
  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mSizes)
  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mBlocking)
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END

NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(HTMLLinkElement,
                                                nsGenericHTMLElement)
  tmp->LinkStyle::Unlink();
  NS_IMPL_CYCLE_COLLECTION_UNLINK(mRelList)
  NS_IMPL_CYCLE_COLLECTION_UNLINK(mSizes)
  NS_IMPL_CYCLE_COLLECTION_UNLINK(mBlocking)
NS_IMPL_CYCLE_COLLECTION_UNLINK_END

NS_IMPL_ISUPPORTS_CYCLE_COLLECTION_INHERITED_0(HTMLLinkElement,
                                               nsGenericHTMLElement)

NS_IMPL_ELEMENT_CLONE(HTMLLinkElement)

bool HTMLLinkElement::Disabled() const {
  return GetBoolAttr(nsGkAtoms::disabled);
}

void HTMLLinkElement::SetDisabled(bool aDisabled, ErrorResult& aRv) {
  return SetHTMLBoolAttr(nsGkAtoms::disabled, aDisabled, aRv);
}

nsresult HTMLLinkElement::BindToTree(BindContext& aContext, nsINode& aParent) {
  nsresult rv = nsGenericHTMLElement::BindToTree(aContext, aParent);
  NS_ENSURE_SUCCESS(rv, rv);

  if (IsInComposedDoc()) {
    TryDNSPrefetchOrPreconnectOrPrefetchOrPreloadOrPrerender();
  }

  LinkStyle::BindToTree();

  if (IsInUncomposedDoc()) {
    if (AttrValueIs(kNameSpaceID_None, nsGkAtoms::rel, nsGkAtoms::localization,
                    eIgnoreCase)) {
      aContext.OwnerDoc().LocalizationLinkAdded(this);
    }

    LinkAdded();
  }

  return rv;
}

void HTMLLinkElement::LinkAdded() {
  CreateAndDispatchEvent(u"DOMLinkAdded"_ns);
}

void HTMLLinkElement::UnbindFromTree(UnbindContext& aContext) {
  CancelDNSPrefetch(*this);
  CancelPrefetchOrPreload();

  // If this is reinserted back into the document it will not be
  // from the parser.
  Document* oldDoc = GetUncomposedDoc();
  ShadowRoot* oldShadowRoot = GetContainingShadow();

  // We want to update the localization but only if the link is removed from a
  // DOM change, and not because the document is going away.
  bool ignore;
  if (oldDoc) {
    if (oldDoc->GetScriptHandlingObject(ignore) &&
        AttrValueIs(kNameSpaceID_None, nsGkAtoms::rel, nsGkAtoms::localization,
                    eIgnoreCase)) {
      oldDoc->LocalizationLinkRemoved(this);
    }
  }

  nsGenericHTMLElement::UnbindFromTree(aContext);

  Unused << UpdateStyleSheetInternal(oldDoc, oldShadowRoot);
}

bool HTMLLinkElement::ParseAttribute(int32_t aNamespaceID, nsAtom* aAttribute,
                                     const nsAString& aValue,
                                     nsIPrincipal* aMaybeScriptedPrincipal,
                                     nsAttrValue& aResult) {
  if (aNamespaceID == kNameSpaceID_None) {
    if (aAttribute == nsGkAtoms::crossorigin) {
      ParseCORSValue(aValue, aResult);
      return true;
    }

    if (aAttribute == nsGkAtoms::as) {
      net::ParseAsValue(aValue, aResult);
      return true;
    }

    if (aAttribute == nsGkAtoms::sizes) {
      aResult.ParseAtomArray(aValue);
      return true;
    }

    if (aAttribute == nsGkAtoms::integrity) {
      aResult.ParseStringOrAtom(aValue);
      return true;
    }

    if (aAttribute == nsGkAtoms::fetchpriority) {
      ParseFetchPriority(aValue, aResult);
      return true;
    }

    if (aAttribute == nsGkAtoms::blocking &&
        StaticPrefs::dom_element_blocking_enabled()) {
      aResult.ParseAtomArray(aValue);
      return true;
    }
  }

  return nsGenericHTMLElement::ParseAttribute(aNamespaceID, aAttribute, aValue,
                                              aMaybeScriptedPrincipal, aResult);
}

void HTMLLinkElement::CreateAndDispatchEvent(const nsAString& aEventName) {
  MOZ_ASSERT(IsInUncomposedDoc());

  // In the unlikely case that both rev is specified *and* rel=stylesheet,
  // this code will cause the event to fire, on the principle that maybe the
  // page really does want to specify that its author is a stylesheet. Since
  // this should never actually happen and the performance hit is minimal,
  // doing the "right" thing costs virtually nothing here, even if it doesn't
  // make much sense.
  static AttrArray::AttrValuesArray strings[] = {
      nsGkAtoms::_empty, nsGkAtoms::stylesheet, nullptr};

  if (!nsContentUtils::HasNonEmptyAttr(this, kNameSpaceID_None,
                                       nsGkAtoms::rev) &&
      FindAttrValueIn(kNameSpaceID_None, nsGkAtoms::rel, strings,
                      eIgnoreCase) != AttrArray::ATTR_VALUE_NO_MATCH) {
    return;
  }

  RefPtr<AsyncEventDispatcher> asyncDispatcher = new AsyncEventDispatcher(
      this, aEventName, CanBubble::eYes, ChromeOnlyDispatch::eYes);
  // Always run async in order to avoid running script when the content
  // sink isn't expecting it.
  asyncDispatcher->PostDOMEvent();
}

void HTMLLinkElement::BeforeSetAttr(int32_t aNameSpaceID, nsAtom* aName,
                                    const nsAttrValue* aValue, bool aNotify) {
  if (aNameSpaceID == kNameSpaceID_None &&
      (aName == nsGkAtoms::href || aName == nsGkAtoms::rel)) {
    CancelDNSPrefetch(*this);
    CancelPrefetchOrPreload();
  }

  return nsGenericHTMLElement::BeforeSetAttr(aNameSpaceID, aName, aValue,
                                             aNotify);
}

void HTMLLinkElement::AfterSetAttr(int32_t aNameSpaceID, nsAtom* aName,
                                   const nsAttrValue* aValue,
                                   const nsAttrValue* aOldValue,
                                   nsIPrincipal* aSubjectPrincipal,
                                   bool aNotify) {
  if (aNameSpaceID == kNameSpaceID_None && aName == nsGkAtoms::href) {
    mCachedURI = nullptr;
    if (IsInUncomposedDoc()) {
      CreateAndDispatchEvent(u"DOMLinkChanged"_ns);
    }
    mTriggeringPrincipal = nsContentUtils::GetAttrTriggeringPrincipal(
        this, aValue ? aValue->GetStringValue() : EmptyString(),
        aSubjectPrincipal);

    // If the link has `rel=localization` and its `href` attribute is changed,
    // update the list of localization links.
    if (AttrValueIs(kNameSpaceID_None, nsGkAtoms::rel, nsGkAtoms::localization,
                    eIgnoreCase)) {
      if (Document* doc = GetUncomposedDoc()) {
        if (aOldValue) {
          doc->LocalizationLinkRemoved(this);
        }
        if (aValue) {
          doc->LocalizationLinkAdded(this);
        }
      }
    }
  }

  // If a link's `rel` attribute was changed from or to `localization`,
  // update the list of localization links.
  if (aNameSpaceID == kNameSpaceID_None && aName == nsGkAtoms::rel) {
    if (Document* doc = GetUncomposedDoc()) {
      if ((aValue && aValue->Equals(nsGkAtoms::localization, eIgnoreCase)) &&
          (!aOldValue ||
           !aOldValue->Equals(nsGkAtoms::localization, eIgnoreCase))) {
        doc->LocalizationLinkAdded(this);
      } else if ((aOldValue &&
                  aOldValue->Equals(nsGkAtoms::localization, eIgnoreCase)) &&
                 (!aValue ||
                  !aValue->Equals(nsGkAtoms::localization, eIgnoreCase))) {
        doc->LocalizationLinkRemoved(this);
      }
    }
  }

  if (aValue) {
    if (aNameSpaceID == kNameSpaceID_None &&
        (aName == nsGkAtoms::href || aName == nsGkAtoms::rel ||
         aName == nsGkAtoms::title || aName == nsGkAtoms::media ||
         aName == nsGkAtoms::type || aName == nsGkAtoms::as ||
         aName == nsGkAtoms::crossorigin || aName == nsGkAtoms::disabled)) {
      bool dropSheet = false;
      if (aName == nsGkAtoms::rel) {
        nsAutoString value;
        aValue->ToString(value);
        uint32_t linkTypes = ParseLinkTypes(value);
        if (GetSheet()) {
          dropSheet = !(linkTypes & eSTYLESHEET);
        }
      }

      if ((aName == nsGkAtoms::rel || aName == nsGkAtoms::href) &&
          IsInComposedDoc()) {
        TryDNSPrefetchOrPreconnectOrPrefetchOrPreloadOrPrerender();
      }

      if ((aName == nsGkAtoms::as || aName == nsGkAtoms::type ||
           aName == nsGkAtoms::crossorigin || aName == nsGkAtoms::media) &&
          IsInComposedDoc()) {
        UpdatePreload(aName, aValue, aOldValue);
      }

      const bool forceUpdate =
          dropSheet || aName == nsGkAtoms::title || aName == nsGkAtoms::media ||
          aName == nsGkAtoms::type || aName == nsGkAtoms::disabled;

      Unused << UpdateStyleSheetInternal(
          nullptr, nullptr, forceUpdate ? ForceUpdate::Yes : ForceUpdate::No);
    }
  } else {
    if (aNameSpaceID == kNameSpaceID_None) {
      if (aName == nsGkAtoms::disabled) {
        mExplicitlyEnabled = true;
      }
      // Since removing href or rel makes us no longer link to a stylesheet,
      // force updates for those too.
      if (aName == nsGkAtoms::href || aName == nsGkAtoms::rel ||
          aName == nsGkAtoms::title || aName == nsGkAtoms::media ||
          aName == nsGkAtoms::type || aName == nsGkAtoms::disabled) {
        Unused << UpdateStyleSheetInternal(nullptr, nullptr, ForceUpdate::Yes);
      }
      if ((aName == nsGkAtoms::as || aName == nsGkAtoms::type ||
           aName == nsGkAtoms::crossorigin || aName == nsGkAtoms::media) &&
          IsInComposedDoc()) {
        UpdatePreload(aName, aValue, aOldValue);
      }
    }
  }

  return nsGenericHTMLElement::AfterSetAttr(
      aNameSpaceID, aName, aValue, aOldValue, aSubjectPrincipal, aNotify);
}

// Keep this and the arrays below in sync with ToLinkMask in LinkStyle.cpp.
#define SUPPORTED_REL_VALUES_BASE                                           \
  "preload", "prefetch", "dns-prefetch", "stylesheet", "next", "alternate", \
      "preconnect", "icon", "search", nullptr

static const DOMTokenListSupportedToken sSupportedRelValueCombinations[][12] = {
    {SUPPORTED_REL_VALUES_BASE},
    {"manifest", SUPPORTED_REL_VALUES_BASE},
    {"modulepreload", SUPPORTED_REL_VALUES_BASE},
    {"modulepreload", "manifest", SUPPORTED_REL_VALUES_BASE}};
#undef SUPPORTED_REL_VALUES_BASE

nsDOMTokenList* HTMLLinkElement::RelList() {
  if (!mRelList) {
    int index = (StaticPrefs::dom_manifest_enabled() ? 1 : 0) |
                (StaticPrefs::network_modulepreload() ? 2 : 0);

    mRelList = new nsDOMTokenList(this, nsGkAtoms::rel,
                                  sSupportedRelValueCombinations[index]);
  }
  return mRelList;
}

Maybe<LinkStyle::SheetInfo> HTMLLinkElement::GetStyleSheetInfo() {
  nsAutoString rel;
  GetAttr(nsGkAtoms::rel, rel);
  uint32_t linkTypes = ParseLinkTypes(rel);
  if (!(linkTypes & eSTYLESHEET)) {
    return Nothing();
  }

  if (!IsCSSMimeTypeAttributeForLinkElement(*this)) {
    return Nothing();
  }

  if (Disabled()) {
    return Nothing();
  }

  nsAutoString title;
  nsAutoString media;
  GetTitleAndMediaForElement(*this, title, media);

  bool alternate = linkTypes & eALTERNATE;
  if (alternate && title.IsEmpty()) {
    // alternates must have title.
    return Nothing();
  }

  if (!HasNonEmptyAttr(nsGkAtoms::href)) {
    return Nothing();
  }

  nsAutoString integrity;
  GetAttr(nsGkAtoms::integrity, integrity);

  nsCOMPtr<nsIURI> uri = GetURI();
  nsCOMPtr<nsIPrincipal> prin = mTriggeringPrincipal;

  nsAutoString nonce;
  nsString* cspNonce = static_cast<nsString*>(GetProperty(nsGkAtoms::nonce));
  if (cspNonce) {
    nonce = *cspNonce;
  }

  return Some(SheetInfo{
      *OwnerDoc(),
      this,
      uri.forget(),
      prin.forget(),
      MakeAndAddRef<ReferrerInfo>(*this),
      GetCORSMode(),
      title,
      media,
      integrity,
      nonce,
      alternate ? HasAlternateRel::Yes : HasAlternateRel::No,
      IsInline::No,
      mExplicitlyEnabled ? IsExplicitlyEnabled::Yes : IsExplicitlyEnabled::No,
      GetFetchPriority(),
  });
}

void HTMLLinkElement::AddSizeOfExcludingThis(nsWindowSizes& aSizes,
                                             size_t* aNodeSize) const {
  nsGenericHTMLElement::AddSizeOfExcludingThis(aSizes, aNodeSize);
  if (nsCOMPtr<nsISizeOf> iface = do_QueryInterface(mCachedURI)) {
    *aNodeSize += iface->SizeOfExcludingThis(aSizes.mState.mMallocSizeOf);
  }
}

JSObject* HTMLLinkElement::WrapNode(JSContext* aCx,
                                    JS::Handle<JSObject*> aGivenProto) {
  return HTMLLinkElement_Binding::Wrap(aCx, this, aGivenProto);
}

void HTMLLinkElement::GetAs(nsAString& aResult) {
  GetEnumAttr(nsGkAtoms::as, "", aResult);
}

void HTMLLinkElement::GetContentPolicyMimeTypeMedia(
    nsAttrValue& aAsAttr, nsContentPolicyType& aPolicyType, nsString& aMimeType,
    nsAString& aMedia) {
  nsAutoString as;
  GetAttr(nsGkAtoms::as, as);
  net::ParseAsValue(as, aAsAttr);
  aPolicyType = net::AsValueToContentPolicy(aAsAttr);

  nsAutoString type;
  GetAttr(nsGkAtoms::type, type);
  nsAutoString notUsed;
  nsContentUtils::SplitMimeType(type, aMimeType, notUsed);

  GetAttr(nsGkAtoms::media, aMedia);
}

void HTMLLinkElement::
    TryDNSPrefetchOrPreconnectOrPrefetchOrPreloadOrPrerender() {
  MOZ_ASSERT(IsInComposedDoc());
  if (!HasAttr(nsGkAtoms::href)) {
    return;
  }

  nsAutoString rel;
  if (!GetAttr(nsGkAtoms::rel, rel)) {
    return;
  }

  if (!nsContentUtils::PrefetchPreloadEnabled(OwnerDoc()->GetDocShell())) {
    return;
  }

  uint32_t linkTypes = ParseLinkTypes(rel);

  if ((linkTypes & ePREFETCH) || (linkTypes & eNEXT)) {
    nsCOMPtr<nsIPrefetchService> prefetchService(
        components::Prefetch::Service());
    if (prefetchService) {
      if (nsCOMPtr<nsIURI> uri = GetURI()) {
        auto referrerInfo = MakeRefPtr<ReferrerInfo>(*this);
        prefetchService->PrefetchURI(uri, referrerInfo, this,
                                     linkTypes & ePREFETCH);
        return;
      }
    }
  }

  if (linkTypes & ePRELOAD) {
    if (nsCOMPtr<nsIURI> uri = GetURI()) {
      nsContentPolicyType policyType;

      nsAttrValue asAttr;
      nsAutoString mimeType;
      nsAutoString media;
      GetContentPolicyMimeTypeMedia(asAttr, policyType, mimeType, media);

      if (policyType == nsIContentPolicy::TYPE_INVALID ||
          !net::CheckPreloadAttrs(asAttr, mimeType, media, OwnerDoc())) {
        // Ignore preload with a wrong or empty as attribute.
        net::WarnIgnoredPreload(*OwnerDoc(), *uri);
        return;
      }

      StartPreload(policyType);
      return;
    }
  }

  if (linkTypes & eMODULE_PRELOAD) {
    ScriptLoader* scriptLoader = OwnerDoc()->ScriptLoader();
    ModuleLoader* moduleLoader = scriptLoader->GetModuleLoader();

    if (!moduleLoader) {
      // For the print preview documents, at this moment it doesn't have module
      // loader yet, as the (print preview) document is not attached to the
      // nsIDocumentViewer yet, so it doesn't have the GlobalObject.
      // Also, the script elements won't be processed as they are also cloned
      // from the original document.
      // So we simply bail out if the module loader is null.
      return;
    }

    if (!StaticPrefs::network_modulepreload()) {
      // Keep behavior from https://phabricator.services.mozilla.com/D149371,
      // prior to main implementation of modulepreload
      moduleLoader->DisallowImportMaps();
      return;
    }

    // https://html.spec.whatwg.org/multipage/semantics.html#processing-the-media-attribute
    // TODO: apply this check for all linkTypes
    nsAutoString media;
    if (GetAttr(nsGkAtoms::media, media)) {
      RefPtr<mozilla::dom::MediaList> mediaList =
          mozilla::dom::MediaList::Create(NS_ConvertUTF16toUTF8(media));
      if (!mediaList->Matches(*OwnerDoc())) {
        return;
      }
    }

    // TODO: per spec, apply this check for ePREFETCH as well
    if (!HasNonEmptyAttr(nsGkAtoms::href)) {
      return;
    }

    nsAutoString as;
    GetAttr(nsGkAtoms::as, as);

    if (!net::IsScriptLikeOrInvalid(as)) {
      RefPtr<AsyncEventDispatcher> asyncDispatcher = new AsyncEventDispatcher(
          this, u"error"_ns, CanBubble::eNo, ChromeOnlyDispatch::eNo);
      asyncDispatcher->PostDOMEvent();
      return;
    }

    nsCOMPtr<nsIURI> uri = GetURI();
    if (!uri) {
      return;
    }

    // https://html.spec.whatwg.org/multipage/webappapis.html#fetch-a-modulepreload-module-script-graph
    // Step 1. Disallow further import maps given settings object.
    moduleLoader->DisallowImportMaps();

    StartPreload(nsIContentPolicy::TYPE_SCRIPT);
    return;
  }

  if (linkTypes & ePRECONNECT) {
    if (nsCOMPtr<nsIURI> uri = GetURI()) {
      OwnerDoc()->MaybePreconnect(
          uri, AttrValueToCORSMode(GetParsedAttr(nsGkAtoms::crossorigin)));
      return;
    }
  }

  if (linkTypes & eDNS_PREFETCH) {
    TryDNSPrefetch(*this, HTMLDNSPrefetch::PrefetchSource::LinkDnsPrefetch);
  }
}

void HTMLLinkElement::UpdatePreload(nsAtom* aName, const nsAttrValue* aValue,
                                    const nsAttrValue* aOldValue) {
  MOZ_ASSERT(IsInComposedDoc());

  if (!HasAttr(nsGkAtoms::href)) {
    return;
  }

  nsAutoString rel;
  if (!GetAttr(nsGkAtoms::rel, rel)) {
    return;
  }

  if (!nsContentUtils::PrefetchPreloadEnabled(OwnerDoc()->GetDocShell())) {
    return;
  }

  uint32_t linkTypes = ParseLinkTypes(rel);

  if (!(linkTypes & ePRELOAD)) {
    return;
  }

  nsCOMPtr<nsIURI> uri = GetURI();
  if (!uri) {
    return;
  }

  nsAttrValue asAttr;
  nsContentPolicyType asPolicyType;
  nsAutoString mimeType;
  nsAutoString media;
  GetContentPolicyMimeTypeMedia(asAttr, asPolicyType, mimeType, media);

  if (asPolicyType == nsIContentPolicy::TYPE_INVALID ||
      !net::CheckPreloadAttrs(asAttr, mimeType, media, OwnerDoc())) {
    // Ignore preload with a wrong or empty as attribute, but be sure to cancel
    // the old one.
    CancelPrefetchOrPreload();
    net::WarnIgnoredPreload(*OwnerDoc(), *uri);
    return;
  }

  if (aName == nsGkAtoms::crossorigin) {
    CORSMode corsMode = AttrValueToCORSMode(aValue);
    CORSMode oldCorsMode = AttrValueToCORSMode(aOldValue);
    if (corsMode != oldCorsMode) {
      CancelPrefetchOrPreload();
      StartPreload(asPolicyType);
    }
    return;
  }

  nsContentPolicyType oldPolicyType;

  if (aName == nsGkAtoms::as) {
    if (aOldValue) {
      oldPolicyType = net::AsValueToContentPolicy(*aOldValue);
      if (!net::CheckPreloadAttrs(*aOldValue, mimeType, media, OwnerDoc())) {
        oldPolicyType = nsIContentPolicy::TYPE_INVALID;
      }
    } else {
      oldPolicyType = nsIContentPolicy::TYPE_INVALID;
    }
  } else if (aName == nsGkAtoms::type) {
    nsAutoString oldType;
    nsAutoString notUsed;
    if (aOldValue) {
      aOldValue->ToString(oldType);
    }
    nsAutoString oldMimeType;
    nsContentUtils::SplitMimeType(oldType, oldMimeType, notUsed);
    if (net::CheckPreloadAttrs(asAttr, oldMimeType, media, OwnerDoc())) {
      oldPolicyType = asPolicyType;
    } else {
      oldPolicyType = nsIContentPolicy::TYPE_INVALID;
    }
  } else {
    MOZ_ASSERT(aName == nsGkAtoms::media);
    nsAutoString oldMedia;
    if (aOldValue) {
      aOldValue->ToString(oldMedia);
    }
    if (net::CheckPreloadAttrs(asAttr, mimeType, oldMedia, OwnerDoc())) {
      oldPolicyType = asPolicyType;
    } else {
      oldPolicyType = nsIContentPolicy::TYPE_INVALID;
    }
  }

  if (asPolicyType != oldPolicyType &&
      oldPolicyType != nsIContentPolicy::TYPE_INVALID) {
    CancelPrefetchOrPreload();
  }

  // Trigger a new preload if the policy type has changed.
  if (asPolicyType != oldPolicyType) {
    StartPreload(asPolicyType);
  }
}

void HTMLLinkElement::CancelPrefetchOrPreload() {
  CancelPreload();

  nsCOMPtr<nsIPrefetchService> prefetchService(components::Prefetch::Service());
  if (prefetchService) {
    if (nsCOMPtr<nsIURI> uri = GetURI()) {
      prefetchService->CancelPrefetchPreloadURI(uri, this);
    }
  }
}

void HTMLLinkElement::StartPreload(nsContentPolicyType aPolicyType) {
  MOZ_ASSERT(!mPreload, "Forgot to cancel the running preload");
  RefPtr<PreloaderBase> preload =
      OwnerDoc()->Preloads().PreloadLinkElement(this, aPolicyType);
  mPreload = preload.get();
}

void HTMLLinkElement::CancelPreload() {
  if (mPreload) {
    // This will cancel the loading channel if this was the last referred node
    // and the preload is not used up until now to satisfy a regular tag load
    // request.
    mPreload->RemoveLinkPreloadNode(this);
    mPreload = nullptr;
  }
}

bool HTMLLinkElement::IsCSSMimeTypeAttributeForLinkElement(
    const Element& aSelf) {
  // Processing the type attribute per
  // https://html.spec.whatwg.org/multipage/semantics.html#processing-the-type-attribute
  // for HTML link elements.
  nsAutoString type;
  nsAutoString mimeType;
  nsAutoString notUsed;
  aSelf.GetAttr(nsGkAtoms::type, type);
  nsContentUtils::SplitMimeType(type, mimeType, notUsed);
  return mimeType.IsEmpty() || mimeType.LowerCaseEqualsLiteral("text/css");
}

nsDOMTokenList* HTMLLinkElement::Blocking() {
  if (!mBlocking) {
    mBlocking =
        new nsDOMTokenList(this, nsGkAtoms::blocking, sSupportedBlockingValues);
  }
  return mBlocking;
}

bool HTMLLinkElement::IsPotentiallyRenderBlocking() {
  return BlockingContainsRender();

  // TODO: handle implicitly potentially render blocking
  // https://html.spec.whatwg.org/#implicitly-potentially-render-blocking
  // The default type for resources given by the stylesheet keyword is text/css.
  // A link element of this type is implicitly potentially render-blocking if
  // the element was created by its node document's parser.
}

}  // namespace mozilla::dom

quality100%

¤ Dauer der Verarbeitung: 0.16 Sekunden (vorverarbeitet) ¤

Wurzel

Suchen

Beweissystem der NASA

Beweissystem Isabelle

NIST Cobol Testsuite

Cephes Mathematical Library

Wiener Entwicklungsmethode

Haftungshinweis

Die Informationen auf dieser Webseite wurden nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit, noch Qualität der bereit gestellten Informationen zugesichert.

Bemerkung:

Die farbliche Syntaxdarstellung ist noch experimentell.