CSSStyleSheetResource should cache decoded text instead of raw bytes

third_party/WebKit/Source/core/fetch/CSSStyleSheetResource.cpp

 /*
     Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
     Copyright (C) 2001 Dirk Mueller (mueller@kde.org)
     Copyright (C) 2002 Waldo Bastian (bastian@kde.org)
     Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
     Copyright (C) 2004, 2005, 2006 Apple Computer, Inc.
 
     This library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Library General Public
     License as published by the Free Software Foundation; either
@@ skipping 25 matching lines @@
 #include "wtf/CurrentTime.h"
 
 namespace blink {
 
 CSSStyleSheetResource* CSSStyleSheetResource::fetch(FetchRequest& request,
                                                     ResourceFetcher* fetcher) {
   DCHECK_EQ(request.resourceRequest().frameType(),
             WebURLRequest::FrameTypeNone);
   request.mutableResourceRequest().setRequestContext(
       WebURLRequest::RequestContextStyle);
-  return toCSSStyleSheetResource(
+  CSSStyleSheetResource* resource = toCSSStyleSheetResource(
       fetcher->requestResource(request, CSSStyleSheetResourceFactory()));
+  // TODO(kouhei): Dedupe this logic w/ ScriptResource::fetch
+  if (resource && !request.integrityMetadata().isEmpty())
+    resource->setIntegrityMetadata(request.integrityMetadata());
+  return resource;
 }
 
 CSSStyleSheetResource* CSSStyleSheetResource::createForTest(
     const ResourceRequest& request,
     const String& charset) {
   return new CSSStyleSheetResource(request, ResourceLoaderOptions(), charset);
 }
 
 CSSStyleSheetResource::CSSStyleSheetResource(
     const ResourceRequest& resourceRequest,
@@ skipping 34 matching lines @@
     static_cast<StyleSheetResourceClient*>(c)->didAppendFirstData(this);
 
   // |c| might be removed in didAppendFirstData, so ensure it is still a client.
   if (hasClient(c) && !isLoading())
     static_cast<StyleSheetResourceClient*>(c)->setCSSStyleSheet(
         resourceRequest().url(), response().url(), encoding(), this);
 }
 
 const String CSSStyleSheetResource::sheetText(
     MIMETypeCheck mimeTypeCheck) const {
-  if (!data() || data()->isEmpty() || !canUseSheet(mimeTypeCheck))
+  if (!canUseSheet(mimeTypeCheck))
     return String();
 
-  if (!m_decodedSheetText.isNull())
+  // Use cached decoded sheet text when available
+  if (!m_decodedSheetText.isNull()) {
+    // We should have the decoded sheet text cached when the resource is fully
+    // loaded.
+    DCHECK_EQ(getStatus(), Resource::Cached);
+
     return m_decodedSheetText;
+  }
 
-  // Don't cache the decoded text, regenerating is cheap and it can use quite a
-  // bit of memory
+  if (!data() || data()->isEmpty())
+    return String();
+
   return decodedText();
 }
 
 void CSSStyleSheetResource::appendData(const char* data, size_t length) {
   Resource::appendData(data, length);
   if (m_didNotifyFirstData)
     return;
   ResourceClientWalker<StyleSheetResourceClient> w(clients());
   while (StyleSheetResourceClient* c = w.next())
     c->didAppendFirstData(this);
   m_didNotifyFirstData = true;
 }
 
 void CSSStyleSheetResource::checkNotify() {
-  // Decode the data to find out the encoding and keep the sheet text around
-  // during checkNotify()
-  if (data())
+  // Decode the data to find out the encoding and cache the decoded sheet text.
+  if (data()) {
     m_decodedSheetText = decodedText();
+  }
 
   ResourceClientWalker<StyleSheetResourceClient> w(clients());
   while (StyleSheetResourceClient* c = w.next()) {
     markClientFinished(c);
     c->setCSSStyleSheet(resourceRequest().url(), response().url(), encoding(),
                         this);
   }
-  // Clear the decoded text as it is unlikely to be needed immediately again and
-  // is cheap to regenerate.
-  m_decodedSheetText = String();
+
+  // Clear raw bytes as now we have the full decoded sheet text.
+  // We wait for all LinkStyle::setCSSStyleSheet to run (at least once)
+  // as SubresourceIntegrity checks require raw bytes.
+  // Note that LinkStyle::setCSSStyleSheet can be called from didAddClient too,
+  // but is safe as we should have a cached ResourceIntegrityDisposition.
+  clearData();
 }
 
 void CSSStyleSheetResource::destroyDecodedDataIfPossible() {
   if (!m_parsedStyleSheetCache)
     return;
 
   setParsedStyleSheetCache(nullptr);
   setDecodedSize(0);
 }
 
+void CSSStyleSheetResource::destroyDecodedDataForFailedRevalidation() {
+  m_decodedSheetText = String();
+  destroyDecodedDataIfPossible();
+}
+
 bool CSSStyleSheetResource::canUseSheet(MIMETypeCheck mimeTypeCheck) const {
   if (errorOccurred())
     return false;
 
   // This check exactly matches Firefox. Note that we grab the Content-Type
   // header directly because we want to see what the value is BEFORE content
   // sniffing. Firefox does this by setting a "type hint" on the channel. This
   // implementation should be observationally equivalent.
   //
   // This code defaults to allowing the stylesheet for non-HTTP protocols so
@@ skipping 35 matching lines @@
     // This stylesheet resource did conflict with another resource and was not
     // added to the cache.
     setParsedStyleSheetCache(nullptr);
     return;
   }
   setParsedStyleSheetCache(sheet);
   setDecodedSize(m_parsedStyleSheetCache->estimatedSizeInBytes());
 }
 
 }  // namespace blink