gecko-dev/image/imgLoader.cpp

/* -*- 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/. */

// Undefine windows version of LoadImage because our code uses that name.
#undef LoadImage

#include "ImageLogging.h"
#include "imgLoader.h"

#include "mozilla/Attributes.h"
#include "mozilla/ClearOnShutdown.h"
#include "mozilla/Move.h"
#include "mozilla/Preferences.h"
#include "mozilla/ChaosMode.h"

#include "nsImageModule.h"
#include "imgRequestProxy.h"

#include "nsCOMPtr.h"

#include "nsContentPolicyUtils.h"
#include "nsContentUtils.h"
#include "nsNetUtil.h"
#include "nsNetCID.h"
#include "nsIProtocolHandler.h"
#include "nsMimeTypes.h"
#include "nsStreamUtils.h"
#include "nsIHttpChannel.h"
#include "nsICacheInfoChannel.h"
#include "nsIClassOfService.h"
#include "nsIInterfaceRequestor.h"
#include "nsIInterfaceRequestorUtils.h"
#include "nsIProgressEventSink.h"
#include "nsIChannelEventSink.h"
#include "nsIAsyncVerifyRedirectCallback.h"
#include "nsIFileURL.h"
#include "nsIFile.h"
#include "nsCRT.h"
#include "nsINetworkPredictor.h"
#include "mozilla/dom/ContentParent.h"
#include "mozilla/dom/nsMixedContentBlocker.h"

#include "nsIApplicationCache.h"
#include "nsIApplicationCacheContainer.h"

#include "nsIMemoryReporter.h"
#include "DecoderFactory.h"
#include "Image.h"
#include "gfxPrefs.h"
#include "prtime.h"

// we want to explore making the document own the load group
// so we can associate the document URI with the load group.
// until this point, we have an evil hack:
#include "nsIHttpChannelInternal.h"
#include "nsILoadContext.h"
#include "nsILoadGroupChild.h"
#include "nsIDOMDocument.h"
#include "nsIDocShell.h"

using namespace mozilla;
using namespace mozilla::dom;
using namespace mozilla::image;
using namespace mozilla::net;

MOZ_DEFINE_MALLOC_SIZE_OF(ImagesMallocSizeOf)

class imgMemoryReporter final : public nsIMemoryReporter
{
  ~imgMemoryReporter() = default;

public:
  NS_DECL_ISUPPORTS

  NS_IMETHOD CollectReports(nsIHandleReportCallback* aHandleReport,
                            nsISupports* aData, bool aAnonymize) override
  {
    nsTArray<ImageMemoryCounter> chrome;
    nsTArray<ImageMemoryCounter> content;
    nsTArray<ImageMemoryCounter> uncached;

    for (uint32_t i = 0; i < mKnownLoaders.Length(); i++) {
      for (auto iter = mKnownLoaders[i]->mChromeCache.Iter(); !iter.Done(); iter.Next()) {
        imgCacheEntry* entry = iter.UserData();
        RefPtr<imgRequest> req = entry->GetRequest();
        RecordCounterForRequest(req, &chrome, !entry->HasNoProxies());
      }
      for (auto iter = mKnownLoaders[i]->mCache.Iter(); !iter.Done(); iter.Next()) {
        imgCacheEntry* entry = iter.UserData();
        RefPtr<imgRequest> req = entry->GetRequest();
        RecordCounterForRequest(req, &content, !entry->HasNoProxies());
      }
      MutexAutoLock lock(mKnownLoaders[i]->mUncachedImagesMutex);
      for (auto iter = mKnownLoaders[i]->mUncachedImages.Iter();
           !iter.Done();
           iter.Next()) {
        nsPtrHashKey<imgRequest>* entry = iter.Get();
        RefPtr<imgRequest> req = entry->GetKey();
        RecordCounterForRequest(req, &uncached, req->HasConsumers());
      }
    }

    // Note that we only need to anonymize content image URIs.

    ReportCounterArray(aHandleReport, aData, chrome, "images/chrome");

    ReportCounterArray(aHandleReport, aData, content, "images/content",
                       aAnonymize);

    // Uncached images may be content or chrome, so anonymize them.
    ReportCounterArray(aHandleReport, aData, uncached, "images/uncached",
                       aAnonymize);

    return NS_OK;
  }

  static int64_t ImagesContentUsedUncompressedDistinguishedAmount()
  {
    size_t n = 0;
    for (uint32_t i = 0; i < imgLoader::sMemReporter->mKnownLoaders.Length();
         i++) {
      for (auto iter = imgLoader::sMemReporter->mKnownLoaders[i]->mCache.Iter();
           !iter.Done();
           iter.Next()) {
        imgCacheEntry* entry = iter.UserData();
        if (entry->HasNoProxies()) {
          continue;
        }

        RefPtr<imgRequest> req = entry->GetRequest();
        RefPtr<image::Image> image = req->GetImage();
        if (!image) {
          continue;
        }

        // Both this and EntryImageSizes measure images/content/raster/used/decoded
        // memory.  This function's measurement is secondary -- the result doesn't
        // go in the "explicit" tree -- so we use moz_malloc_size_of instead of
        // ImagesMallocSizeOf to prevent DMD from seeing it reported twice.
        SizeOfState state(moz_malloc_size_of);
        ImageMemoryCounter counter(image, state, /* aIsUsed = */ true);

        n += counter.Values().DecodedHeap();
        n += counter.Values().DecodedNonHeap();
      }
    }
    return n;
  }

  void RegisterLoader(imgLoader* aLoader)
  {
    mKnownLoaders.AppendElement(aLoader);
  }

  void UnregisterLoader(imgLoader* aLoader)
  {
    mKnownLoaders.RemoveElement(aLoader);
  }

private:
  nsTArray<imgLoader*> mKnownLoaders;

  struct MemoryTotal
  {
    MemoryTotal& operator+=(const ImageMemoryCounter& aImageCounter)
    {
      if (aImageCounter.Type() == imgIContainer::TYPE_RASTER) {
        if (aImageCounter.IsUsed()) {
          mUsedRasterCounter += aImageCounter.Values();
        } else {
          mUnusedRasterCounter += aImageCounter.Values();
        }
      } else if (aImageCounter.Type() == imgIContainer::TYPE_VECTOR) {
        if (aImageCounter.IsUsed()) {
          mUsedVectorCounter += aImageCounter.Values();
        } else {
          mUnusedVectorCounter += aImageCounter.Values();
        }
      } else {
        MOZ_CRASH("Unexpected image type");
      }

      return *this;
    }

    const MemoryCounter& UsedRaster() const { return mUsedRasterCounter; }
    const MemoryCounter& UnusedRaster() const { return mUnusedRasterCounter; }
    const MemoryCounter& UsedVector() const { return mUsedVectorCounter; }
    const MemoryCounter& UnusedVector() const { return mUnusedVectorCounter; }

  private:
    MemoryCounter mUsedRasterCounter;
    MemoryCounter mUnusedRasterCounter;
    MemoryCounter mUsedVectorCounter;
    MemoryCounter mUnusedVectorCounter;
  };

  // Reports all images of a single kind, e.g. all used chrome images.
  void ReportCounterArray(nsIHandleReportCallback* aHandleReport,
                          nsISupports* aData,
                          nsTArray<ImageMemoryCounter>& aCounterArray,
                          const char* aPathPrefix,
                          bool aAnonymize = false)
  {
    MemoryTotal summaryTotal;
    MemoryTotal nonNotableTotal;

    // Report notable images, and compute total and non-notable aggregate sizes.
    for (uint32_t i = 0; i < aCounterArray.Length(); i++) {
      ImageMemoryCounter& counter = aCounterArray[i];

      if (aAnonymize) {
        counter.URI().Truncate();
        counter.URI().AppendPrintf("<anonymized-%u>", i);
      } else {
        // The URI could be an extremely long data: URI. Truncate if needed.
        static const size_t max = 256;
        if (counter.URI().Length() > max) {
          counter.URI().Truncate(max);
          counter.URI().AppendLiteral(" (truncated)");
        }
        counter.URI().ReplaceChar('/', '\\');
      }

      summaryTotal += counter;

      if (counter.IsNotable()) {
        ReportImage(aHandleReport, aData, aPathPrefix, counter);
      } else {
        nonNotableTotal += counter;
      }
    }

    // Report non-notable images in aggregate.
    ReportTotal(aHandleReport, aData, /* aExplicit = */ true,
                aPathPrefix, "<non-notable images>/", nonNotableTotal);

    // Report a summary in aggregate, outside of the explicit tree.
    ReportTotal(aHandleReport, aData, /* aExplicit = */ false,
                aPathPrefix, "", summaryTotal);
  }

  static void ReportImage(nsIHandleReportCallback* aHandleReport,
                          nsISupports* aData,
                          const char* aPathPrefix,
                          const ImageMemoryCounter& aCounter)
  {
    nsAutoCString pathPrefix(NS_LITERAL_CSTRING("explicit/"));
    pathPrefix.Append(aPathPrefix);
    pathPrefix.Append(aCounter.Type() == imgIContainer::TYPE_RASTER
                        ? "/raster/"
                        : "/vector/");
    pathPrefix.Append(aCounter.IsUsed() ? "used/" : "unused/");
    pathPrefix.Append("image(");
    pathPrefix.AppendInt(aCounter.IntrinsicSize().width);
    pathPrefix.Append("x");
    pathPrefix.AppendInt(aCounter.IntrinsicSize().height);
    pathPrefix.Append(", ");

    if (aCounter.URI().IsEmpty()) {
      pathPrefix.Append("<unknown URI>");
    } else {
      pathPrefix.Append(aCounter.URI());
    }

    pathPrefix.Append(")/");

    ReportSurfaces(aHandleReport, aData, pathPrefix, aCounter);

    ReportSourceValue(aHandleReport, aData, pathPrefix, aCounter.Values());
  }

  static void ReportSurfaces(nsIHandleReportCallback* aHandleReport,
                             nsISupports* aData,
                             const nsACString& aPathPrefix,
                             const ImageMemoryCounter& aCounter)
  {
    for (const SurfaceMemoryCounter& counter : aCounter.Surfaces()) {
      nsAutoCString surfacePathPrefix(aPathPrefix);
      surfacePathPrefix.Append(counter.IsLocked() ? "locked/" : "unlocked/");
      surfacePathPrefix.Append("surface(");
      surfacePathPrefix.AppendInt(counter.Key().Size().width);
      surfacePathPrefix.Append("x");
      surfacePathPrefix.AppendInt(counter.Key().Size().height);

      if (counter.Values().SharedHandles() > 0) {
        surfacePathPrefix.Append(", shared:");
        surfacePathPrefix.AppendInt(uint32_t(counter.Values().SharedHandles()));
      }

      if (counter.Type() == SurfaceMemoryCounterType::NORMAL) {
        PlaybackType playback = counter.Key().Playback();
        surfacePathPrefix.Append(playback == PlaybackType::eAnimated
                                 ? " (animation)"
                                 : "");

        if (counter.Key().Flags() != DefaultSurfaceFlags()) {
          surfacePathPrefix.Append(", flags:");
          surfacePathPrefix.AppendInt(uint32_t(counter.Key().Flags()),
                                      /* aRadix = */ 16);
        }
      } else if (counter.Type() == SurfaceMemoryCounterType::COMPOSITING) {
        surfacePathPrefix.Append(", compositing frame");
      } else if (counter.Type() == SurfaceMemoryCounterType::COMPOSITING_PREV) {
        surfacePathPrefix.Append(", compositing prev frame");
      } else {
        MOZ_ASSERT_UNREACHABLE("Unknown counter type");
      }

      surfacePathPrefix.Append(")/");

      ReportValues(aHandleReport, aData, surfacePathPrefix, counter.Values());
    }
  }

  static void ReportTotal(nsIHandleReportCallback* aHandleReport,
                          nsISupports* aData,
                          bool aExplicit,
                          const char* aPathPrefix,
                          const char* aPathInfix,
                          const MemoryTotal& aTotal)
  {
    nsAutoCString pathPrefix;
    if (aExplicit) {
      pathPrefix.Append("explicit/");
    }
    pathPrefix.Append(aPathPrefix);

    nsAutoCString rasterUsedPrefix(pathPrefix);
    rasterUsedPrefix.Append("/raster/used/");
    rasterUsedPrefix.Append(aPathInfix);
    ReportValues(aHandleReport, aData, rasterUsedPrefix, aTotal.UsedRaster());

    nsAutoCString rasterUnusedPrefix(pathPrefix);
    rasterUnusedPrefix.Append("/raster/unused/");
    rasterUnusedPrefix.Append(aPathInfix);
    ReportValues(aHandleReport, aData, rasterUnusedPrefix,
                 aTotal.UnusedRaster());

    nsAutoCString vectorUsedPrefix(pathPrefix);
    vectorUsedPrefix.Append("/vector/used/");
    vectorUsedPrefix.Append(aPathInfix);
    ReportValues(aHandleReport, aData, vectorUsedPrefix, aTotal.UsedVector());

    nsAutoCString vectorUnusedPrefix(pathPrefix);
    vectorUnusedPrefix.Append("/vector/unused/");
    vectorUnusedPrefix.Append(aPathInfix);
    ReportValues(aHandleReport, aData, vectorUnusedPrefix,
                 aTotal.UnusedVector());
  }

  static void ReportValues(nsIHandleReportCallback* aHandleReport,
                           nsISupports* aData,
                           const nsACString& aPathPrefix,
                           const MemoryCounter& aCounter)
  {
    ReportSourceValue(aHandleReport, aData, aPathPrefix, aCounter);

    ReportValue(aHandleReport, aData, KIND_HEAP, aPathPrefix,
                "decoded-heap",
                "Decoded image data which is stored on the heap.",
                aCounter.DecodedHeap());

    ReportValue(aHandleReport, aData, KIND_NONHEAP, aPathPrefix,
                "decoded-nonheap",
                "Decoded image data which isn't stored on the heap.",
                aCounter.DecodedNonHeap());
  }

  static void ReportSourceValue(nsIHandleReportCallback* aHandleReport,
                                nsISupports* aData,
                                const nsACString& aPathPrefix,
                                const MemoryCounter& aCounter)
  {
    ReportValue(aHandleReport, aData, KIND_HEAP, aPathPrefix,
                "source",
                "Raster image source data and vector image documents.",
                aCounter.Source());
  }

  static void ReportValue(nsIHandleReportCallback* aHandleReport,
                          nsISupports* aData,
                          int32_t aKind,
                          const nsACString& aPathPrefix,
                          const char* aPathSuffix,
                          const char* aDescription,
                          size_t aValue)
  {
    if (aValue == 0) {
      return;
    }

    nsAutoCString desc(aDescription);
    nsAutoCString path(aPathPrefix);
    path.Append(aPathSuffix);

    aHandleReport->Callback(EmptyCString(), path, aKind, UNITS_BYTES,
                            aValue, desc, aData);
  }

  static void RecordCounterForRequest(imgRequest* aRequest,
                                      nsTArray<ImageMemoryCounter>* aArray,
                                      bool aIsUsed)
  {
    RefPtr<image::Image> image = aRequest->GetImage();
    if (!image) {
      return;
    }

    SizeOfState state(ImagesMallocSizeOf);
    ImageMemoryCounter counter(image, state, aIsUsed);

    aArray->AppendElement(Move(counter));
  }
};

NS_IMPL_ISUPPORTS(imgMemoryReporter, nsIMemoryReporter)

NS_IMPL_ISUPPORTS(nsProgressNotificationProxy,
                  nsIProgressEventSink,
                  nsIChannelEventSink,
                  nsIInterfaceRequestor)

NS_IMETHODIMP
nsProgressNotificationProxy::OnProgress(nsIRequest* request,
                                        nsISupports* ctxt,
                                        int64_t progress,
                                        int64_t progressMax)
{
  nsCOMPtr<nsILoadGroup> loadGroup;
  request->GetLoadGroup(getter_AddRefs(loadGroup));

  nsCOMPtr<nsIProgressEventSink> target;
  NS_QueryNotificationCallbacks(mOriginalCallbacks,
                                loadGroup,
                                NS_GET_IID(nsIProgressEventSink),
                                getter_AddRefs(target));
  if (!target) {
    return NS_OK;
  }
  return target->OnProgress(mImageRequest, ctxt, progress, progressMax);
}

NS_IMETHODIMP
nsProgressNotificationProxy::OnStatus(nsIRequest* request,
                                      nsISupports* ctxt,
                                      nsresult status,
                                      const char16_t* statusArg)
{
  nsCOMPtr<nsILoadGroup> loadGroup;
  request->GetLoadGroup(getter_AddRefs(loadGroup));

  nsCOMPtr<nsIProgressEventSink> target;
  NS_QueryNotificationCallbacks(mOriginalCallbacks,
                                loadGroup,
                                NS_GET_IID(nsIProgressEventSink),
                                getter_AddRefs(target));
  if (!target) {
    return NS_OK;
  }
  return target->OnStatus(mImageRequest, ctxt, status, statusArg);
}

NS_IMETHODIMP
nsProgressNotificationProxy::
  AsyncOnChannelRedirect(nsIChannel* oldChannel,
                         nsIChannel* newChannel,
                         uint32_t flags,
                         nsIAsyncVerifyRedirectCallback* cb)
{
  // Tell the original original callbacks about it too
  nsCOMPtr<nsILoadGroup> loadGroup;
  newChannel->GetLoadGroup(getter_AddRefs(loadGroup));
  nsCOMPtr<nsIChannelEventSink> target;
  NS_QueryNotificationCallbacks(mOriginalCallbacks,
                                loadGroup,
                                NS_GET_IID(nsIChannelEventSink),
                                getter_AddRefs(target));
  if (!target) {
      cb->OnRedirectVerifyCallback(NS_OK);
      return NS_OK;
  }

  // Delegate to |target| if set, reusing |cb|
  return target->AsyncOnChannelRedirect(oldChannel, newChannel, flags, cb);
}

NS_IMETHODIMP
nsProgressNotificationProxy::GetInterface(const nsIID& iid,
                                          void** result)
{
  if (iid.Equals(NS_GET_IID(nsIProgressEventSink))) {
    *result = static_cast<nsIProgressEventSink*>(this);
    NS_ADDREF_THIS();
    return NS_OK;
  }
  if (iid.Equals(NS_GET_IID(nsIChannelEventSink))) {
    *result = static_cast<nsIChannelEventSink*>(this);
    NS_ADDREF_THIS();
    return NS_OK;
  }
  if (mOriginalCallbacks) {
    return mOriginalCallbacks->GetInterface(iid, result);
  }
  return NS_NOINTERFACE;
}

static void
NewRequestAndEntry(bool aForcePrincipalCheckForCacheEntry, imgLoader* aLoader,
                   const ImageCacheKey& aKey,
                   imgRequest** aRequest, imgCacheEntry** aEntry)
{
  RefPtr<imgRequest> request = new imgRequest(aLoader, aKey);
  RefPtr<imgCacheEntry> entry =
    new imgCacheEntry(aLoader, request, aForcePrincipalCheckForCacheEntry);
  aLoader->AddToUncachedImages(request);
  request.forget(aRequest);
  entry.forget(aEntry);
}

static bool
ShouldRevalidateEntry(imgCacheEntry* aEntry,
                      nsLoadFlags aFlags,
                      bool aHasExpired)
{
  bool bValidateEntry = false;

  if (aFlags & nsIRequest::LOAD_BYPASS_CACHE) {
    return false;
  }

  if (aFlags & nsIRequest::VALIDATE_ALWAYS) {
    bValidateEntry = true;
  } else if (aEntry->GetMustValidate()) {
    bValidateEntry = true;
  } else if (aHasExpired) {
    // The cache entry has expired...  Determine whether the stale cache
    // entry can be used without validation...
    if (aFlags & (nsIRequest::VALIDATE_NEVER |
                  nsIRequest::VALIDATE_ONCE_PER_SESSION)) {
      // VALIDATE_NEVER and VALIDATE_ONCE_PER_SESSION allow stale cache
      // entries to be used unless they have been explicitly marked to
      // indicate that revalidation is necessary.
      bValidateEntry = false;

    } else if (!(aFlags & nsIRequest::LOAD_FROM_CACHE)) {
      // LOAD_FROM_CACHE allows a stale cache entry to be used... Otherwise,
      // the entry must be revalidated.
      bValidateEntry = true;
    }
  }

  return bValidateEntry;
}

/* Call content policies on cached images that went through a redirect */
static bool
ShouldLoadCachedImage(imgRequest* aImgRequest,
                      nsISupports* aLoadingContext,
                      nsIPrincipal* aLoadingPrincipal,
                      nsContentPolicyType aPolicyType)
{
  /* Call content policies on cached images - Bug 1082837
   * Cached images are keyed off of the first uri in a redirect chain.
   * Hence content policies don't get a chance to test the intermediate hops
   * or the final desitnation.  Here we test the final destination using
   * mCurrentURI off of the imgRequest and passing it into content policies.
   * For Mixed Content Blocker, we do an additional check to determine if any
   * of the intermediary hops went through an insecure redirect with the
   * mHadInsecureRedirect flag
   */
  bool insecureRedirect = aImgRequest->HadInsecureRedirect();
  nsCOMPtr<nsIURI> contentLocation;
  aImgRequest->GetCurrentURI(getter_AddRefs(contentLocation));
  nsresult rv;

  int16_t decision = nsIContentPolicy::REJECT_REQUEST;
  rv = NS_CheckContentLoadPolicy(aPolicyType,
                                 contentLocation,
                                 aLoadingPrincipal,
                                 aLoadingContext,
                                 EmptyCString(), //mime guess
                                 nullptr, //aExtra
                                 &decision,
                                 nsContentUtils::GetContentPolicy());
  if (NS_FAILED(rv) || !NS_CP_ACCEPTED(decision)) {
    return false;
  }

  // We call all Content Policies above, but we also have to call mcb
  // individually to check the intermediary redirect hops are secure.
  if (insecureRedirect) {
    // Bug 1314356: If the image ended up in the cache upgraded by HSTS and the page
    // uses upgrade-inscure-requests it had an insecure redirect (http->https).
    // We need to invalidate the image and reload it because mixed content blocker
    // only bails if upgrade-insecure-requests is set on the doc and the resource
    // load is http: which would result in an incorrect mixed content warning.
    nsCOMPtr<nsIDocShell> docShell = NS_CP_GetDocShellFromContext(aLoadingContext);
    if (docShell) {
      nsIDocument* document = docShell->GetDocument();
      if (document && document->GetUpgradeInsecureRequests(false)) {
        return false;
      }
    }

    if (!nsContentUtils::IsSystemPrincipal(aLoadingPrincipal)) {
      // Set the requestingLocation from the aLoadingPrincipal.
      nsCOMPtr<nsIURI> requestingLocation;
      if (aLoadingPrincipal) {
        rv = aLoadingPrincipal->GetURI(getter_AddRefs(requestingLocation));
        NS_ENSURE_SUCCESS(rv, false);
      }

      // reset the decision for mixed content blocker check
      decision = nsIContentPolicy::REJECT_REQUEST;
      rv = nsMixedContentBlocker::ShouldLoad(insecureRedirect,
                                             aPolicyType,
                                             contentLocation,
                                             requestingLocation,
                                             aLoadingContext,
                                             EmptyCString(), //mime guess
                                             nullptr,
                                             aLoadingPrincipal,
                                             &decision);
      if (NS_FAILED(rv) || !NS_CP_ACCEPTED(decision)) {
        return false;
      }
    }
  }

  bool sendPriming = false;
  bool mixedContentWouldBlock = false;
  rv = nsMixedContentBlocker::GetHSTSPrimingFromRequestingContext(contentLocation,
      aLoadingContext, &sendPriming, &mixedContentWouldBlock);
  if (NS_FAILED(rv)) {
    return false;
  }
  if (sendPriming && mixedContentWouldBlock) {
    // if either of the securty checks above would cause a priming request, we
    // can't load this image from the cache, so go ahead and return false here
    return false;
  }

  return true;
}

// Returns true if this request is compatible with the given CORS mode on the
// given loading principal, and false if the request may not be reused due
// to CORS.  Also checks the Referrer Policy, since requests with different
// referrers/policies may generate different responses.
static bool
ValidateSecurityInfo(imgRequest* request, bool forcePrincipalCheck,
                     int32_t corsmode, nsIPrincipal* loadingPrincipal,
                     nsISupports* aCX, nsContentPolicyType aPolicyType,
                     ReferrerPolicy referrerPolicy)
{
  // If the entry's Referrer Policy doesn't match, we can't use this request.
  // XXX: this will return false if an image has different referrer attributes,
  // i.e. we currently don't use the cached image but reload the image with
  // the new referrer policy bug 1174921
  if (referrerPolicy != request->GetReferrerPolicy()) {
    return false;
  }

  // If the entry's CORS mode doesn't match, or the CORS mode matches but the
  // document principal isn't the same, we can't use this request.
  if (request->GetCORSMode() != corsmode) {
    return false;
  }
  if (request->GetCORSMode() != imgIRequest::CORS_NONE ||
      forcePrincipalCheck) {
    nsCOMPtr<nsIPrincipal> otherprincipal = request->GetLoadingPrincipal();

    // If we previously had a principal, but we don't now, we can't use this
    // request.
    if (otherprincipal && !loadingPrincipal) {
      return false;
    }

    if (otherprincipal && loadingPrincipal) {
      bool equals = false;
      otherprincipal->Equals(loadingPrincipal, &equals);
      if (!equals) {
        return false;
      }
    }
  }

  // Content Policy Check on Cached Images
  return ShouldLoadCachedImage(request, aCX, loadingPrincipal, aPolicyType);
}

static nsresult
NewImageChannel(nsIChannel** aResult,
                // If aForcePrincipalCheckForCacheEntry is true, then we will
                // force a principal check even when not using CORS before
                // assuming we have a cache hit on a cache entry that we
                // create for this channel.  This is an out param that should
                // be set to true if this channel ends up depending on
                // aLoadingPrincipal and false otherwise.
                bool* aForcePrincipalCheckForCacheEntry,
                nsIURI* aURI,
                nsIURI* aInitialDocumentURI,
                int32_t aCORSMode,
                nsIURI* aReferringURI,
                ReferrerPolicy aReferrerPolicy,
                nsILoadGroup* aLoadGroup,
                const nsCString& aAcceptHeader,
                nsLoadFlags aLoadFlags,
                nsContentPolicyType aPolicyType,
                nsIPrincipal* aLoadingPrincipal,
                nsISupports* aRequestingContext,
                bool aRespectPrivacy)
{
  MOZ_ASSERT(aResult);

  nsresult rv;
  nsCOMPtr<nsIHttpChannel> newHttpChannel;

  nsCOMPtr<nsIInterfaceRequestor> callbacks;

  if (aLoadGroup) {
    // Get the notification callbacks from the load group for the new channel.
    //
    // XXX: This is not exactly correct, because the network request could be
    //      referenced by multiple windows...  However, the new channel needs
    //      something.  So, using the 'first' notification callbacks is better
    //      than nothing...
    //
    aLoadGroup->GetNotificationCallbacks(getter_AddRefs(callbacks));
  }

  // Pass in a nullptr loadgroup because this is the underlying network
  // request. This request may be referenced by several proxy image requests
  // (possibly in different documents).
  // If all of the proxy requests are canceled then this request should be
  // canceled too.
  //
  aLoadFlags |= nsIChannel::LOAD_CLASSIFY_URI;

  nsCOMPtr<nsINode> requestingNode = do_QueryInterface(aRequestingContext);

  nsSecurityFlags securityFlags =
    aCORSMode == imgIRequest::CORS_NONE
    ? nsILoadInfo::SEC_ALLOW_CROSS_ORIGIN_DATA_INHERITS
    : nsILoadInfo::SEC_REQUIRE_CORS_DATA_INHERITS;
  if (aCORSMode == imgIRequest::CORS_ANONYMOUS) {
    securityFlags |= nsILoadInfo::SEC_COOKIES_SAME_ORIGIN;
  } else if (aCORSMode == imgIRequest::CORS_USE_CREDENTIALS) {
    securityFlags |= nsILoadInfo::SEC_COOKIES_INCLUDE;
  }
  securityFlags |= nsILoadInfo::SEC_ALLOW_CHROME;

  // Note we are calling NS_NewChannelWithTriggeringPrincipal() here with a
  // node and a principal. This is for things like background images that are
  // specified by user stylesheets, where the document is being styled, but
  // the principal is that of the user stylesheet.
  if (requestingNode && aLoadingPrincipal) {
    rv = NS_NewChannelWithTriggeringPrincipal(aResult,
                                              aURI,
                                              requestingNode,
                                              aLoadingPrincipal,
                                              securityFlags,
                                              aPolicyType,
                                              nullptr,   // loadGroup
                                              callbacks,
                                              aLoadFlags);

    if (NS_FAILED(rv)) {
      return rv;
    }

    if (aPolicyType == nsIContentPolicy::TYPE_INTERNAL_IMAGE_FAVICON) {
      // If this is a favicon loading, we will use the originAttributes from the
      // loadingPrincipal as the channel's originAttributes. This allows the favicon
      // loading from XUL will use the correct originAttributes.

      nsCOMPtr<nsILoadInfo> loadInfo = (*aResult)->GetLoadInfo();
      if (loadInfo) {
        rv =
          loadInfo->SetOriginAttributes(aLoadingPrincipal->OriginAttributesRef());
      }
    }
  } else {
    // either we are loading something inside a document, in which case
    // we should always have a requestingNode, or we are loading something
    // outside a document, in which case the loadingPrincipal and
    // triggeringPrincipal should always be the systemPrincipal.
    // However, there are exceptions: one is Notifications which create a
    // channel in the parent prcoess in which case we can't get a requestingNode.
    rv = NS_NewChannel(aResult,
                       aURI,
                       nsContentUtils::GetSystemPrincipal(),
                       securityFlags,
                       aPolicyType,
                       nullptr,   // loadGroup
                       callbacks,
                       aLoadFlags);

    if (NS_FAILED(rv)) {
      return rv;
    }

    // Use the OriginAttributes from the loading principal, if one is available,
    // and adjust the private browsing ID based on what kind of load the caller
    // has asked us to perform.
    OriginAttributes attrs;
    if (aLoadingPrincipal) {
      attrs = aLoadingPrincipal->OriginAttributesRef();
    }
    attrs.mPrivateBrowsingId = aRespectPrivacy ? 1 : 0;

    nsCOMPtr<nsILoadInfo> loadInfo = (*aResult)->GetLoadInfo();
    if (loadInfo) {
      rv = loadInfo->SetOriginAttributes(attrs);
    }
  }

  if (NS_FAILED(rv)) {
    return rv;
  }

  // only inherit if we have a principal
  *aForcePrincipalCheckForCacheEntry =
    aLoadingPrincipal &&
    nsContentUtils::ChannelShouldInheritPrincipal(
      aLoadingPrincipal,
      aURI,
      /* aInheritForAboutBlank */ false,
      /* aForceInherit */ false);

  // Initialize HTTP-specific attributes
  newHttpChannel = do_QueryInterface(*aResult);
  if (newHttpChannel) {
    rv = newHttpChannel->SetRequestHeader(NS_LITERAL_CSTRING("Accept"),
                                          aAcceptHeader,
                                          false);
    MOZ_ASSERT(NS_SUCCEEDED(rv));

    nsCOMPtr<nsIHttpChannelInternal> httpChannelInternal =
      do_QueryInterface(newHttpChannel);
    NS_ENSURE_TRUE(httpChannelInternal, NS_ERROR_UNEXPECTED);
    rv = httpChannelInternal->SetDocumentURI(aInitialDocumentURI);
    MOZ_ASSERT(NS_SUCCEEDED(rv));
    rv = newHttpChannel->SetReferrerWithPolicy(aReferringURI, aReferrerPolicy);
    MOZ_ASSERT(NS_SUCCEEDED(rv));
  }

  // Image channels are loaded by default with reduced priority.
  nsCOMPtr<nsISupportsPriority> p = do_QueryInterface(*aResult);
  if (p) {
    uint32_t priority = nsISupportsPriority::PRIORITY_LOW;

    if (aLoadFlags & nsIRequest::LOAD_BACKGROUND) {
      ++priority; // further reduce priority for background loads
    }

    p->AdjustPriority(priority);
  }

  // Create a new loadgroup for this new channel, using the old group as
  // the parent. The indirection keeps the channel insulated from cancels,
  // but does allow a way for this revalidation to be associated with at
  // least one base load group for scheduling/caching purposes.

  nsCOMPtr<nsILoadGroup> loadGroup = do_CreateInstance(NS_LOADGROUP_CONTRACTID);
  nsCOMPtr<nsILoadGroupChild> childLoadGroup = do_QueryInterface(loadGroup);
  if (childLoadGroup) {
    childLoadGroup->SetParentLoadGroup(aLoadGroup);
  }
  (*aResult)->SetLoadGroup(loadGroup);

  return NS_OK;
}

static uint32_t
SecondsFromPRTime(PRTime prTime)
{
  return uint32_t(int64_t(prTime) / int64_t(PR_USEC_PER_SEC));
}

imgCacheEntry::imgCacheEntry(imgLoader* loader, imgRequest* request,
                             bool forcePrincipalCheck)
 : mLoader(loader),
   mRequest(request),
   mDataSize(0),
   mTouchedTime(SecondsFromPRTime(PR_Now())),
   mLoadTime(SecondsFromPRTime(PR_Now())),
   mExpiryTime(0),
   mMustValidate(false),
   // We start off as evicted so we don't try to update the cache. PutIntoCache
   // will set this to false.
   mEvicted(true),
   mHasNoProxies(true),
   mForcePrincipalCheck(forcePrincipalCheck)
{ }

imgCacheEntry::~imgCacheEntry()
{
  LOG_FUNC(gImgLog, "imgCacheEntry::~imgCacheEntry()");
}

void
imgCacheEntry::Touch(bool updateTime /* = true */)
{
  LOG_SCOPE(gImgLog, "imgCacheEntry::Touch");

  if (updateTime) {
    mTouchedTime = SecondsFromPRTime(PR_Now());
  }

  UpdateCache();
}

void
imgCacheEntry::UpdateCache(int32_t diff /* = 0 */)
{
  // Don't update the cache if we've been removed from it or it doesn't care
  // about our size or usage.
  if (!Evicted() && HasNoProxies()) {
    mLoader->CacheEntriesChanged(mRequest->IsChrome(), diff);
  }
}

void imgCacheEntry::UpdateLoadTime()
{
  mLoadTime = SecondsFromPRTime(PR_Now());
}

void
imgCacheEntry::SetHasNoProxies(bool hasNoProxies)
{
  if (MOZ_LOG_TEST(gImgLog, LogLevel::Debug)) {
    if (hasNoProxies) {
      LOG_FUNC_WITH_PARAM(gImgLog, "imgCacheEntry::SetHasNoProxies true",
                          "uri", mRequest->CacheKey().Spec());
    } else {
      LOG_FUNC_WITH_PARAM(gImgLog, "imgCacheEntry::SetHasNoProxies false",
                          "uri", mRequest->CacheKey().Spec());
    }
  }

  mHasNoProxies = hasNoProxies;
}

imgCacheQueue::imgCacheQueue()
 : mDirty(false),
   mSize(0)
{ }

void
imgCacheQueue::UpdateSize(int32_t diff)
{
  mSize += diff;
}

uint32_t
imgCacheQueue::GetSize() const
{
  return mSize;
}

#include <algorithm>
using namespace std;

void
imgCacheQueue::Remove(imgCacheEntry* entry)
{
  auto it = find(mQueue.begin(), mQueue.end(), entry);
  if (it != mQueue.end()) {
    mSize -= (*it)->GetDataSize();
    mQueue.erase(it);
    MarkDirty();
  }
}

void
imgCacheQueue::Push(imgCacheEntry* entry)
{
  mSize += entry->GetDataSize();

  RefPtr<imgCacheEntry> refptr(entry);
  mQueue.push_back(refptr);
  MarkDirty();
}

already_AddRefed<imgCacheEntry>
imgCacheQueue::Pop()
{
  if (mQueue.empty()) {
    return nullptr;
  }
  if (IsDirty()) {
    Refresh();
  }

  RefPtr<imgCacheEntry> entry = mQueue[0];
  std::pop_heap(mQueue.begin(), mQueue.end(), imgLoader::CompareCacheEntries);
  mQueue.pop_back();

  mSize -= entry->GetDataSize();
  return entry.forget();
}

void
imgCacheQueue::Refresh()
{
  std::make_heap(mQueue.begin(), mQueue.end(), imgLoader::CompareCacheEntries);
  mDirty = false;
}

void
imgCacheQueue::MarkDirty()
{
  mDirty = true;
}

bool
imgCacheQueue::IsDirty()
{
  return mDirty;
}

uint32_t
imgCacheQueue::GetNumElements() const
{
  return mQueue.size();
}

imgCacheQueue::iterator
imgCacheQueue::begin()
{
  return mQueue.begin();
}

imgCacheQueue::const_iterator
imgCacheQueue::begin() const
{
  return mQueue.begin();
}

imgCacheQueue::iterator
imgCacheQueue::end()
{
  return mQueue.end();
}

imgCacheQueue::const_iterator
imgCacheQueue::end() const
{
  return mQueue.end();
}

nsresult
imgLoader::CreateNewProxyForRequest(imgRequest* aRequest,
                                    nsILoadGroup* aLoadGroup,
                                    nsIDocument* aLoadingDocument,
                                    imgINotificationObserver* aObserver,
                                    nsLoadFlags aLoadFlags,
                                    imgRequestProxy** _retval)
{
  LOG_SCOPE_WITH_PARAM(gImgLog, "imgLoader::CreateNewProxyForRequest",
                       "imgRequest", aRequest);

  /* XXX If we move decoding onto separate threads, we should save off the
     calling thread here and pass it off to |proxyRequest| so that it call
     proxy calls to |aObserver|.
   */

  RefPtr<imgRequestProxy> proxyRequest = new imgRequestProxy();

  /* It is important to call |SetLoadFlags()| before calling |Init()| because
     |Init()| adds the request to the loadgroup.
   */
  proxyRequest->SetLoadFlags(aLoadFlags);

  RefPtr<ImageURL> uri;
  aRequest->GetURI(getter_AddRefs(uri));

  // init adds itself to imgRequest's list of observers
  nsresult rv = proxyRequest->Init(aRequest, aLoadGroup, aLoadingDocument,
                                   uri, aObserver);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  proxyRequest.forget(_retval);
  return NS_OK;
}

class imgCacheExpirationTracker final
  : public nsExpirationTracker<imgCacheEntry, 3>
{
  enum { TIMEOUT_SECONDS = 10 };
public:
  imgCacheExpirationTracker();

protected:
  void NotifyExpired(imgCacheEntry* entry) override;
};

imgCacheExpirationTracker::imgCacheExpirationTracker()
 : nsExpirationTracker<imgCacheEntry, 3>(TIMEOUT_SECONDS * 1000,
                                         "imgCacheExpirationTracker")
{ }

void
imgCacheExpirationTracker::NotifyExpired(imgCacheEntry* entry)
{
  // Hold on to a reference to this entry, because the expiration tracker
  // mechanism doesn't.
  RefPtr<imgCacheEntry> kungFuDeathGrip(entry);

  if (MOZ_LOG_TEST(gImgLog, LogLevel::Debug)) {
    RefPtr<imgRequest> req = entry->GetRequest();
    if (req) {
      LOG_FUNC_WITH_PARAM(gImgLog,
                         "imgCacheExpirationTracker::NotifyExpired",
                         "entry", req->CacheKey().Spec());
    }
  }

  // We can be called multiple times on the same entry. Don't do work multiple
  // times.
  if (!entry->Evicted()) {
    entry->Loader()->RemoveFromCache(entry);
  }

  entry->Loader()->VerifyCacheSizes();
}


///////////////////////////////////////////////////////////////////////////////
// imgLoader
///////////////////////////////////////////////////////////////////////////////

double imgLoader::sCacheTimeWeight;
uint32_t imgLoader::sCacheMaxSize;
imgMemoryReporter* imgLoader::sMemReporter;

NS_IMPL_ISUPPORTS(imgLoader, imgILoader, nsIContentSniffer, imgICache,
                  nsISupportsWeakReference, nsIObserver)

static imgLoader* gNormalLoader = nullptr;
static imgLoader* gPrivateBrowsingLoader = nullptr;

/* static */ already_AddRefed<imgLoader>
imgLoader::CreateImageLoader()
{
  // In some cases, such as xpctests, XPCOM modules are not automatically
  // initialized.  We need to make sure that our module is initialized before
  // we hand out imgLoader instances and code starts using them.
  mozilla::image::EnsureModuleInitialized();

  RefPtr<imgLoader> loader = new imgLoader();
  loader->Init();

  return loader.forget();
}

imgLoader*
imgLoader::NormalLoader()
{
  if (!gNormalLoader) {
    gNormalLoader = CreateImageLoader().take();
  }
  return gNormalLoader;
}

imgLoader*
imgLoader::PrivateBrowsingLoader()
{
  if (!gPrivateBrowsingLoader) {
    gPrivateBrowsingLoader = CreateImageLoader().take();
    gPrivateBrowsingLoader->RespectPrivacyNotifications();
  }
  return gPrivateBrowsingLoader;
}

imgLoader::imgLoader()
: mUncachedImagesMutex("imgLoader::UncachedImages"), mRespectPrivacy(false)
{
  sMemReporter->AddRef();
  sMemReporter->RegisterLoader(this);
}

imgLoader::~imgLoader()
{
  ClearChromeImageCache();
  ClearImageCache();
  {
    // If there are any of our imgRequest's left they are in the uncached
    // images set, so clear their pointer to us.
    MutexAutoLock lock(mUncachedImagesMutex);
    for (auto iter = mUncachedImages.Iter(); !iter.Done(); iter.Next()) {
      nsPtrHashKey<imgRequest>* entry = iter.Get();
      RefPtr<imgRequest> req = entry->GetKey();
      req->ClearLoader();
    }
  }
  sMemReporter->UnregisterLoader(this);
  sMemReporter->Release();
}

void
imgLoader::VerifyCacheSizes()
{
#ifdef DEBUG
  if (!mCacheTracker) {
    return;
  }

  uint32_t cachesize = mCache.Count() + mChromeCache.Count();
  uint32_t queuesize =
    mCacheQueue.GetNumElements() + mChromeCacheQueue.GetNumElements();
  uint32_t trackersize = 0;
  for (nsExpirationTracker<imgCacheEntry, 3>::Iterator it(mCacheTracker.get());
       it.Next(); ){
    trackersize++;
  }
  MOZ_ASSERT(queuesize == trackersize, "Queue and tracker sizes out of sync!");
  MOZ_ASSERT(queuesize <= cachesize, "Queue has more elements than cache!");
#endif
}

imgLoader::imgCacheTable&
imgLoader::GetCache(bool aForChrome)
{
  return aForChrome ? mChromeCache : mCache;
}

imgLoader::imgCacheTable&
imgLoader::GetCache(const ImageCacheKey& aKey)
{
  return GetCache(aKey.IsChrome());
}

imgCacheQueue&
imgLoader::GetCacheQueue(bool aForChrome)
{
  return aForChrome ? mChromeCacheQueue : mCacheQueue;

}

imgCacheQueue&
imgLoader::GetCacheQueue(const ImageCacheKey& aKey)
{
  return GetCacheQueue(aKey.IsChrome());

}

void imgLoader::GlobalInit()
{
  sCacheTimeWeight = gfxPrefs::ImageCacheTimeWeight() / 1000.0;
  int32_t cachesize = gfxPrefs::ImageCacheSize();
  sCacheMaxSize = cachesize > 0 ? cachesize : 0;

  sMemReporter = new imgMemoryReporter();
  RegisterStrongMemoryReporter(sMemReporter);
  RegisterImagesContentUsedUncompressedDistinguishedAmount(
    imgMemoryReporter::ImagesContentUsedUncompressedDistinguishedAmount);
}

void imgLoader::ShutdownMemoryReporter()
{
  UnregisterImagesContentUsedUncompressedDistinguishedAmount();
  UnregisterStrongMemoryReporter(sMemReporter);
}

nsresult
imgLoader::InitCache()
{
  nsCOMPtr<nsIObserverService> os = mozilla::services::GetObserverService();
  if (!os) {
    return NS_ERROR_FAILURE;
  }

  os->AddObserver(this, "memory-pressure", false);
  os->AddObserver(this, "chrome-flush-skin-caches", false);
  os->AddObserver(this, "chrome-flush-caches", false);
  os->AddObserver(this, "last-pb-context-exited", false);
  os->AddObserver(this, "profile-before-change", false);
  os->AddObserver(this, "xpcom-shutdown", false);

  mCacheTracker = MakeUnique<imgCacheExpirationTracker>();

  return NS_OK;
}

nsresult
imgLoader::Init()
{
  InitCache();

  ReadAcceptHeaderPref();

  Preferences::AddWeakObserver(this, "image.http.accept");

    return NS_OK;
}

NS_IMETHODIMP
imgLoader::RespectPrivacyNotifications()
{
  mRespectPrivacy = true;
  return NS_OK;
}

NS_IMETHODIMP
imgLoader::Observe(nsISupports* aSubject, const char* aTopic,
                   const char16_t* aData)
{
  // We listen for pref change notifications...
  if (!strcmp(aTopic, NS_PREFBRANCH_PREFCHANGE_TOPIC_ID)) {
    if (!NS_strcmp(aData, u"image.http.accept")) {
      ReadAcceptHeaderPref();
    }

  } else if (strcmp(aTopic, "memory-pressure") == 0) {
    MinimizeCaches();
  } else if (strcmp(aTopic, "chrome-flush-skin-caches") == 0 ||
             strcmp(aTopic, "chrome-flush-caches") == 0) {
    MinimizeCaches();
    ClearChromeImageCache();
  } else if (strcmp(aTopic, "last-pb-context-exited") == 0) {
    if (mRespectPrivacy) {
      ClearImageCache();
      ClearChromeImageCache();
    }
  } else if (strcmp(aTopic, "profile-before-change") == 0) {
    mCacheTracker = nullptr;
  } else if (strcmp(aTopic, "xpcom-shutdown") == 0) {
    mCacheTracker = nullptr;
    ShutdownMemoryReporter();

  } else {
  // (Nothing else should bring us here)
    MOZ_ASSERT(0, "Invalid topic received");
  }

  return NS_OK;
}

void imgLoader::ReadAcceptHeaderPref()
{
  nsAutoCString accept;
  nsresult rv = Preferences::GetCString("image.http.accept", accept);
  if (NS_SUCCEEDED(rv)) {
    mAcceptHeader = accept;
  } else {
    mAcceptHeader =
      IMAGE_PNG "," IMAGE_WILDCARD ";q=0.8," ANY_WILDCARD ";q=0.5";
  }
}

NS_IMETHODIMP
imgLoader::ClearCache(bool chrome)
{
  if (XRE_IsParentProcess()) {
    bool privateLoader = this == gPrivateBrowsingLoader;
    for (auto* cp : ContentParent::AllProcesses(ContentParent::eLive)) {
      Unused << cp->SendClearImageCache(privateLoader, chrome);
    }
  }

  if (chrome) {
    return ClearChromeImageCache();
  }
  return ClearImageCache();

}

NS_IMETHODIMP
imgLoader::RemoveEntry(nsIURI* aURI,
                       nsIDOMDocument* aDOMDoc)
{
  nsCOMPtr<nsIDocument> doc = do_QueryInterface(aDOMDoc);
  if (aURI) {
    OriginAttributes attrs;
    if (doc) {
      nsCOMPtr<nsIPrincipal> principal = doc->NodePrincipal();
      if (principal) {
        attrs = principal->OriginAttributesRef();
      }
    }

    nsresult rv = NS_OK;
    ImageCacheKey key(aURI, attrs, doc, rv);
    if (NS_SUCCEEDED(rv) && RemoveFromCache(key)) {
      return NS_OK;
    }
  }
  return NS_ERROR_NOT_AVAILABLE;
}

NS_IMETHODIMP
imgLoader::FindEntryProperties(nsIURI* uri,
                               nsIDOMDocument* aDOMDoc,
                               nsIProperties** _retval)
{
  *_retval = nullptr;

  nsCOMPtr<nsIDocument> doc = do_QueryInterface(aDOMDoc);

  OriginAttributes attrs;
  if (doc) {
    nsCOMPtr<nsIPrincipal> principal = doc->NodePrincipal();
    if (principal) {
      attrs = principal->OriginAttributesRef();
    }
  }

  nsresult rv;
  ImageCacheKey key(uri, attrs, doc, rv);
  NS_ENSURE_SUCCESS(rv, rv);
  imgCacheTable& cache = GetCache(key);

  RefPtr<imgCacheEntry> entry;
  if (cache.Get(key, getter_AddRefs(entry)) && entry) {
    if (mCacheTracker && entry->HasNoProxies()) {
      mCacheTracker->MarkUsed(entry);
    }

    RefPtr<imgRequest> request = entry->GetRequest();
    if (request) {
      nsCOMPtr<nsIProperties> properties = request->Properties();
      properties.forget(_retval);
    }
  }

  return NS_OK;
}

NS_IMETHODIMP_(void)
imgLoader::ClearCacheForControlledDocument(nsIDocument* aDoc)
{
  MOZ_ASSERT(aDoc);
  AutoTArray<RefPtr<imgCacheEntry>, 128> entriesToBeRemoved;
  imgCacheTable& cache = GetCache(false);
  for (auto iter = cache.Iter(); !iter.Done(); iter.Next()) {
    auto& key = iter.Key();
    if (key.ControlledDocument() == aDoc) {
      entriesToBeRemoved.AppendElement(iter.Data());
    }
  }
  for (auto& entry : entriesToBeRemoved) {
    if (!RemoveFromCache(entry)) {
      NS_WARNING("Couldn't remove an entry from the cache in ClearCacheForControlledDocument()\n");
    }
  }
}

void
imgLoader::Shutdown()
{
  NS_IF_RELEASE(gNormalLoader);
  gNormalLoader = nullptr;
  NS_IF_RELEASE(gPrivateBrowsingLoader);
  gPrivateBrowsingLoader = nullptr;
}

nsresult
imgLoader::ClearChromeImageCache()
{
  return EvictEntries(mChromeCache);
}

nsresult
imgLoader::ClearImageCache()
{
  return EvictEntries(mCache);
}

void
imgLoader::MinimizeCaches()
{
  EvictEntries(mCacheQueue);
  EvictEntries(mChromeCacheQueue);
}

bool
imgLoader::PutIntoCache(const ImageCacheKey& aKey, imgCacheEntry* entry)
{
  imgCacheTable& cache = GetCache(aKey);

  LOG_STATIC_FUNC_WITH_PARAM(gImgLog,
                             "imgLoader::PutIntoCache", "uri", aKey.Spec());

  // Check to see if this request already exists in the cache. If so, we'll
  // replace the old version.
  RefPtr<imgCacheEntry> tmpCacheEntry;
  if (cache.Get(aKey, getter_AddRefs(tmpCacheEntry)) && tmpCacheEntry) {
    MOZ_LOG(gImgLog, LogLevel::Debug,
           ("[this=%p] imgLoader::PutIntoCache -- Element already in the cache",
            nullptr));
    RefPtr<imgRequest> tmpRequest = tmpCacheEntry->GetRequest();

    // If it already exists, and we're putting the same key into the cache, we
    // should remove the old version.
    MOZ_LOG(gImgLog, LogLevel::Debug,
           ("[this=%p] imgLoader::PutIntoCache -- Replacing cached element",
            nullptr));

    RemoveFromCache(aKey);
  } else {
    MOZ_LOG(gImgLog, LogLevel::Debug,
           ("[this=%p] imgLoader::PutIntoCache --"
            " Element NOT already in the cache", nullptr));
  }

  cache.Put(aKey, entry);

  // We can be called to resurrect an evicted entry.
  if (entry->Evicted()) {
    entry->SetEvicted(false);
  }

  // If we're resurrecting an entry with no proxies, put it back in the
  // tracker and queue.
  if (entry->HasNoProxies()) {
    nsresult addrv = NS_OK;

    if (mCacheTracker) {
      addrv = mCacheTracker->AddObject(entry);
    }

    if (NS_SUCCEEDED(addrv)) {
      imgCacheQueue& queue = GetCacheQueue(aKey);
      queue.Push(entry);
    }
  }

  RefPtr<imgRequest> request = entry->GetRequest();
  request->SetIsInCache(true);
  RemoveFromUncachedImages(request);

  return true;
}

bool
imgLoader::SetHasNoProxies(imgRequest* aRequest, imgCacheEntry* aEntry)
{
  LOG_STATIC_FUNC_WITH_PARAM(gImgLog,
                             "imgLoader::SetHasNoProxies", "uri",
                             aRequest->CacheKey().Spec());

  aEntry->SetHasNoProxies(true);

  if (aEntry->Evicted()) {
    return false;
  }

  imgCacheQueue& queue = GetCacheQueue(aRequest->IsChrome());

  nsresult addrv = NS_OK;

  if (mCacheTracker) {
    addrv = mCacheTracker->AddObject(aEntry);
  }

  if (NS_SUCCEEDED(addrv)) {
    queue.Push(aEntry);
  }

  imgCacheTable& cache = GetCache(aRequest->IsChrome());
  CheckCacheLimits(cache, queue);

  return true;
}

bool
imgLoader::SetHasProxies(imgRequest* aRequest)
{
  VerifyCacheSizes();

  const ImageCacheKey& key = aRequest->CacheKey();
  imgCacheTable& cache = GetCache(key);

  LOG_STATIC_FUNC_WITH_PARAM(gImgLog,
                             "imgLoader::SetHasProxies", "uri", key.Spec());

  RefPtr<imgCacheEntry> entry;
  if (cache.Get(key, getter_AddRefs(entry)) && entry) {
    // Make sure the cache entry is for the right request
    RefPtr<imgRequest> entryRequest = entry->GetRequest();
    if (entryRequest == aRequest && entry->HasNoProxies()) {
      imgCacheQueue& queue = GetCacheQueue(key);
      queue.Remove(entry);

      if (mCacheTracker) {
        mCacheTracker->RemoveObject(entry);
      }

      entry->SetHasNoProxies(false);

      return true;
    }
  }

  return false;
}

void
imgLoader::CacheEntriesChanged(bool aForChrome, int32_t aSizeDiff /* = 0 */)
{
  imgCacheQueue& queue = GetCacheQueue(aForChrome);
  queue.MarkDirty();
  queue.UpdateSize(aSizeDiff);
}

void
imgLoader::CheckCacheLimits(imgCacheTable& cache, imgCacheQueue& queue)
{
  if (queue.GetNumElements() == 0) {
    NS_ASSERTION(queue.GetSize() == 0,
                 "imgLoader::CheckCacheLimits -- incorrect cache size");
  }

  // Remove entries from the cache until we're back at our desired max size.
  while (queue.GetSize() > sCacheMaxSize) {
    // Remove the first entry in the queue.
    RefPtr<imgCacheEntry> entry(queue.Pop());

    NS_ASSERTION(entry, "imgLoader::CheckCacheLimits -- NULL entry pointer");

    if (MOZ_LOG_TEST(gImgLog, LogLevel::Debug)) {
      RefPtr<imgRequest> req = entry->GetRequest();
      if (req) {
        LOG_STATIC_FUNC_WITH_PARAM(gImgLog,
                                   "imgLoader::CheckCacheLimits",
                                   "entry", req->CacheKey().Spec());
      }
    }

    if (entry) {
      RemoveFromCache(entry);
    }
  }
}

bool
imgLoader::ValidateRequestWithNewChannel(imgRequest* request,
                                         nsIURI* aURI,
                                         nsIURI* aInitialDocumentURI,
                                         nsIURI* aReferrerURI,
                                         ReferrerPolicy aReferrerPolicy,
                                         nsILoadGroup* aLoadGroup,
                                         imgINotificationObserver* aObserver,
                                         nsISupports* aCX,
                                         nsIDocument* aLoadingDocument,
                                         nsLoadFlags aLoadFlags,
                                         nsContentPolicyType aLoadPolicyType,
                                         imgRequestProxy** aProxyRequest,
                                         nsIPrincipal* aLoadingPrincipal,
                                         int32_t aCORSMode)
{
  // now we need to insert a new channel request object inbetween the real
  // request and the proxy that basically delays loading the image until it
  // gets a 304 or figures out that this needs to be a new request

  nsresult rv;

  // If we're currently in the middle of validating this request, just hand
  // back a proxy to it; the required work will be done for us.
  if (request->GetValidator()) {
    rv = CreateNewProxyForRequest(request, aLoadGroup, aLoadingDocument,
                                  aObserver, aLoadFlags, aProxyRequest);
    if (NS_FAILED(rv)) {
      return false;
    }

    if (*aProxyRequest) {
      imgRequestProxy* proxy = static_cast<imgRequestProxy*>(*aProxyRequest);

      // We will send notifications from imgCacheValidator::OnStartRequest().
      // In the mean time, we must defer notifications because we are added to
      // the imgRequest's proxy list, and we can get extra notifications
      // resulting from methods such as StartDecoding(). See bug 579122.
      proxy->SetNotificationsDeferred(true);

      // Attach the proxy without notifying
      request->GetValidator()->AddProxy(proxy);
    }

    return NS_SUCCEEDED(rv);

  }
  // We will rely on Necko to cache this request when it's possible, and to
  // tell imgCacheValidator::OnStartRequest whether the request came from its
  // cache.
  nsCOMPtr<nsIChannel> newChannel;
  bool forcePrincipalCheck;
  rv = NewImageChannel(getter_AddRefs(newChannel),
                       &forcePrincipalCheck,
                       aURI,
                       aInitialDocumentURI,
                       aCORSMode,
                       aReferrerURI,
                       aReferrerPolicy,
                       aLoadGroup,
                       mAcceptHeader,
                       aLoadFlags,
                       aLoadPolicyType,
                       aLoadingPrincipal,
                       aCX,
                       mRespectPrivacy);
  if (NS_FAILED(rv)) {
    return false;
  }

  RefPtr<imgRequestProxy> req;
  rv = CreateNewProxyForRequest(request, aLoadGroup, aLoadingDocument,
                                aObserver, aLoadFlags, getter_AddRefs(req));
  if (NS_FAILED(rv)) {
    return false;
  }

  // Make sure that OnStatus/OnProgress calls have the right request set...
  RefPtr<nsProgressNotificationProxy> progressproxy =
    new nsProgressNotificationProxy(newChannel, req);
  if (!progressproxy) {
    return false;
  }

  RefPtr<imgCacheValidator> hvc =
    new imgCacheValidator(progressproxy, this, request, aCX,
                          forcePrincipalCheck);

  // Casting needed here to get past multiple inheritance.
  nsCOMPtr<nsIStreamListener> listener =
    do_QueryInterface(static_cast<nsIThreadRetargetableStreamListener*>(hvc));
  NS_ENSURE_TRUE(listener, false);

  // We must set the notification callbacks before setting up the
  // CORS listener, because that's also interested inthe
  // notification callbacks.
  newChannel->SetNotificationCallbacks(hvc);

  request->SetValidator(hvc);

  // We will send notifications from imgCacheValidator::OnStartRequest().
  // In the mean time, we must defer notifications because we are added to
  // the imgRequest's proxy list, and we can get extra notifications
  // resulting from methods such as StartDecoding(). See bug 579122.
  req->SetNotificationsDeferred(true);

  // Add the proxy without notifying
  hvc->AddProxy(req);

  mozilla::net::PredictorLearn(aURI, aInitialDocumentURI,
                               nsINetworkPredictor::LEARN_LOAD_SUBRESOURCE, aLoadGroup);
  rv = newChannel->AsyncOpen2(listener);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    req->CancelAndForgetObserver(rv);
    return false;
  }

  req.forget(aProxyRequest);
  return true;
}

bool
imgLoader::ValidateEntry(imgCacheEntry* aEntry,
                         nsIURI* aURI,
                         nsIURI* aInitialDocumentURI,
                         nsIURI* aReferrerURI,
                         ReferrerPolicy aReferrerPolicy,
                         nsILoadGroup* aLoadGroup,
                         imgINotificationObserver* aObserver,
                         nsISupports* aCX,
                         nsIDocument* aLoadingDocument,
                         nsLoadFlags aLoadFlags,
                         nsContentPolicyType aLoadPolicyType,
                         bool aCanMakeNewChannel,
                         imgRequestProxy** aProxyRequest,
                         nsIPrincipal* aLoadingPrincipal,
                         int32_t aCORSMode)
{
  LOG_SCOPE(gImgLog, "imgLoader::ValidateEntry");

  bool hasExpired;
  uint32_t expirationTime = aEntry->GetExpiryTime();
  if (expirationTime <= SecondsFromPRTime(PR_Now())) {
    hasExpired = true;
  } else {
    hasExpired = false;
  }

  nsresult rv;

  // Special treatment for file URLs - aEntry has expired if file has changed
  nsCOMPtr<nsIFileURL> fileUrl(do_QueryInterface(aURI));
  if (fileUrl) {
    uint32_t lastModTime = aEntry->GetLoadTime();

    nsCOMPtr<nsIFile> theFile;
    rv = fileUrl->GetFile(getter_AddRefs(theFile));
    if (NS_SUCCEEDED(rv)) {
      PRTime fileLastMod;
      rv = theFile->GetLastModifiedTime(&fileLastMod);
      if (NS_SUCCEEDED(rv)) {
        // nsIFile uses millisec, NSPR usec
        fileLastMod *= 1000;
        hasExpired = SecondsFromPRTime((PRTime)fileLastMod) > lastModTime;
      }
    }
  }

  RefPtr<imgRequest> request(aEntry->GetRequest());

  if (!request) {
    return false;
  }

  if (!ValidateSecurityInfo(request, aEntry->ForcePrincipalCheck(),
                            aCORSMode, aLoadingPrincipal,
                            aCX, aLoadPolicyType, aReferrerPolicy))
    return false;

  // data URIs are immutable and by their nature can't leak data, so we can
  // just return true in that case.  Doing so would mean that shift-reload
  // doesn't reload data URI documents/images though (which is handy for
  // debugging during gecko development) so we make an exception in that case.
  nsAutoCString scheme;
  aURI->GetScheme(scheme);
  if (scheme.EqualsLiteral("data") &&
      !(aLoadFlags & nsIRequest::LOAD_BYPASS_CACHE)) {
    return true;
  }

  bool validateRequest = false;

  // If the request's loadId is the same as the aCX, then it is ok to use
  // this one because it has already been validated for this context.
  //
  // XXX: nullptr seems to be a 'special' key value that indicates that NO
  //      validation is required.
  //
  void *key = (void*) aCX;
  if (request->LoadId() != key) {
    // If we would need to revalidate this entry, but we're being told to
    // bypass the cache, we don't allow this entry to be used.
    if (aLoadFlags & nsIRequest::LOAD_BYPASS_CACHE) {
      return false;
    }

    if (MOZ_UNLIKELY(ChaosMode::isActive(ChaosFeature::ImageCache))) {
      if (ChaosMode::randomUint32LessThan(4) < 1) {
        return false;
      }
    }

    // Determine whether the cache aEntry must be revalidated...
    validateRequest = ShouldRevalidateEntry(aEntry, aLoadFlags, hasExpired);

    MOZ_LOG(gImgLog, LogLevel::Debug,
           ("imgLoader::ValidateEntry validating cache entry. "
            "validateRequest = %d", validateRequest));
  } else if (!key && MOZ_LOG_TEST(gImgLog, LogLevel::Debug)) {
    MOZ_LOG(gImgLog, LogLevel::Debug,
           ("imgLoader::ValidateEntry BYPASSING cache validation for %s "
            "because of NULL LoadID", aURI->GetSpecOrDefault().get()));
  }

  // We can't use a cached request if it comes from a different
  // application cache than this load is expecting.
  nsCOMPtr<nsIApplicationCacheContainer> appCacheContainer;
  nsCOMPtr<nsIApplicationCache> requestAppCache;
  nsCOMPtr<nsIApplicationCache> groupAppCache;
  if ((appCacheContainer = do_GetInterface(request->GetRequest()))) {
    appCacheContainer->GetApplicationCache(getter_AddRefs(requestAppCache));
  }
  if ((appCacheContainer = do_QueryInterface(aLoadGroup))) {
    appCacheContainer->GetApplicationCache(getter_AddRefs(groupAppCache));
  }

  if (requestAppCache != groupAppCache) {
    MOZ_LOG(gImgLog, LogLevel::Debug,
           ("imgLoader::ValidateEntry - Unable to use cached imgRequest "
            "[request=%p] because of mismatched application caches\n",
            address_of(request)));
    return false;
  }

  if (validateRequest && aCanMakeNewChannel) {
    LOG_SCOPE(gImgLog,
              "imgLoader::ValidateRequest |cache hit| must validate");

    return ValidateRequestWithNewChannel(request, aURI, aInitialDocumentURI,
                                         aReferrerURI, aReferrerPolicy,
                                         aLoadGroup, aObserver,
                                         aCX, aLoadingDocument,
                                         aLoadFlags, aLoadPolicyType,
                                         aProxyRequest, aLoadingPrincipal,
                                         aCORSMode);
  }

  return !validateRequest;
}

bool
imgLoader::RemoveFromCache(const ImageCacheKey& aKey)
{
  LOG_STATIC_FUNC_WITH_PARAM(gImgLog,
                             "imgLoader::RemoveFromCache", "uri", aKey.Spec());

  imgCacheTable& cache = GetCache(aKey);
  imgCacheQueue& queue = GetCacheQueue(aKey);

  RefPtr<imgCacheEntry> entry;
  cache.Remove(aKey, getter_AddRefs(entry));
  if (entry) {
    MOZ_ASSERT(!entry->Evicted(), "Evicting an already-evicted cache entry!");

    // Entries with no proxies are in the tracker.
    if (entry->HasNoProxies()) {
      if (mCacheTracker) {
        mCacheTracker->RemoveObject(entry);
      }
      queue.Remove(entry);
    }

    entry->SetEvicted(true);

    RefPtr<imgRequest> request = entry->GetRequest();
    request->SetIsInCache(false);
    AddToUncachedImages(request);

    return true;
  }
  return false;
}

bool
imgLoader::RemoveFromCache(imgCacheEntry* entry)
{
  LOG_STATIC_FUNC(gImgLog, "imgLoader::RemoveFromCache entry");

  RefPtr<imgRequest> request = entry->GetRequest();
  if (request) {
    const ImageCacheKey& key = request->CacheKey();
    imgCacheTable& cache = GetCache(key);
    imgCacheQueue& queue = GetCacheQueue(key);

    LOG_STATIC_FUNC_WITH_PARAM(gImgLog,
                               "imgLoader::RemoveFromCache", "entry's uri",
                               key.Spec());

    cache.Remove(key);

    if (entry->HasNoProxies()) {
      LOG_STATIC_FUNC(gImgLog,
                      "imgLoader::RemoveFromCache removing from tracker");
      if (mCacheTracker) {
        mCacheTracker->RemoveObject(entry);
      }
      queue.Remove(entry);
    }

    entry->SetEvicted(true);
    request->SetIsInCache(false);
    AddToUncachedImages(request);

    return true;
  }

  return false;
}

nsresult
imgLoader::EvictEntries(imgCacheTable& aCacheToClear)
{
  LOG_STATIC_FUNC(gImgLog, "imgLoader::EvictEntries table");

  // We have to make a temporary, since RemoveFromCache removes the element
  // from the queue, invalidating iterators.
  nsTArray<RefPtr<imgCacheEntry> > entries;
  for (auto iter = aCacheToClear.Iter(); !iter.Done(); iter.Next()) {
    RefPtr<imgCacheEntry>& data = iter.Data();
    entries.AppendElement(data);
  }

  for (uint32_t i = 0; i < entries.Length(); ++i) {
    if (!RemoveFromCache(entries[i])) {
      return NS_ERROR_FAILURE;
    }
  }

  MOZ_ASSERT(aCacheToClear.Count() == 0);

  return NS_OK;
}

nsresult
imgLoader::EvictEntries(imgCacheQueue& aQueueToClear)
{
  LOG_STATIC_FUNC(gImgLog, "imgLoader::EvictEntries queue");

  // We have to make a temporary, since RemoveFromCache removes the element
  // from the queue, invalidating iterators.
  nsTArray<RefPtr<imgCacheEntry> > entries(aQueueToClear.GetNumElements());
  for (imgCacheQueue::const_iterator i = aQueueToClear.begin();
       i != aQueueToClear.end(); ++i) {
    entries.AppendElement(*i);
  }

  for (uint32_t i = 0; i < entries.Length(); ++i) {
    if (!RemoveFromCache(entries[i])) {
      return NS_ERROR_FAILURE;
    }
  }

  MOZ_ASSERT(aQueueToClear.GetNumElements() == 0);

  return NS_OK;
}

void
imgLoader::AddToUncachedImages(imgRequest* aRequest)
{
  MutexAutoLock lock(mUncachedImagesMutex);
  mUncachedImages.PutEntry(aRequest);
}

void
imgLoader::RemoveFromUncachedImages(imgRequest* aRequest)
{
  MutexAutoLock lock(mUncachedImagesMutex);
  mUncachedImages.RemoveEntry(aRequest);
}


#define LOAD_FLAGS_CACHE_MASK    (nsIRequest::LOAD_BYPASS_CACHE | \
                                  nsIRequest::LOAD_FROM_CACHE)

#define LOAD_FLAGS_VALIDATE_MASK (nsIRequest::VALIDATE_ALWAYS |   \
                                  nsIRequest::VALIDATE_NEVER |    \
                                  nsIRequest::VALIDATE_ONCE_PER_SESSION)

NS_IMETHODIMP
imgLoader::LoadImageXPCOM(nsIURI* aURI,
                          nsIURI* aInitialDocumentURI,
                          nsIURI* aReferrerURI,
                          const nsAString& aReferrerPolicy,
                          nsIPrincipal* aLoadingPrincipal,
                          nsILoadGroup* aLoadGroup,
                          imgINotificationObserver* aObserver,
                          nsISupports* aCX,
                          nsLoadFlags aLoadFlags,
                          nsISupports* aCacheKey,
                          nsContentPolicyType aContentPolicyType,
                          imgIRequest** _retval)
{
    // Optional parameter, so defaults to 0 (== TYPE_INVALID)
    if (!aContentPolicyType) {
      aContentPolicyType = nsIContentPolicy::TYPE_INTERNAL_IMAGE;
    }
    imgRequestProxy* proxy;
    ReferrerPolicy refpol = ReferrerPolicyFromString(aReferrerPolicy);
    nsCOMPtr<nsINode> node = do_QueryInterface(aCX);
    nsCOMPtr<nsIDocument> doc = do_QueryInterface(aCX);
    nsresult rv = LoadImage(aURI,
                            aInitialDocumentURI,
                            aReferrerURI,
                            refpol,
                            aLoadingPrincipal,
                            aLoadGroup,
                            aObserver,
                            node,
                            doc,
                            aLoadFlags,
                            aCacheKey,
                            aContentPolicyType,
                            EmptyString(),
                            /* aUseUrgentStartForChannel */ false,
                            &proxy);
    *_retval = proxy;
    return rv;
}

nsresult
imgLoader::LoadImage(nsIURI* aURI,
                     nsIURI* aInitialDocumentURI,
                     nsIURI* aReferrerURI,
                     ReferrerPolicy aReferrerPolicy,
                     nsIPrincipal* aLoadingPrincipal,
                     nsILoadGroup* aLoadGroup,
                     imgINotificationObserver* aObserver,
                     nsINode *aContext,
                     nsIDocument* aLoadingDocument,
                     nsLoadFlags aLoadFlags,
                     nsISupports* aCacheKey,
                     nsContentPolicyType aContentPolicyType,
                     const nsAString& initiatorType,
                     bool aUseUrgentStartForChannel,
                     imgRequestProxy** _retval)
{
  VerifyCacheSizes();

  NS_ASSERTION(aURI, "imgLoader::LoadImage -- NULL URI pointer");

  if (!aURI) {
    return NS_ERROR_NULL_POINTER;
  }

  LOG_SCOPE_WITH_PARAM(gImgLog, "imgLoader::LoadImage", "aURI",
                       aURI->GetSpecOrDefault().get());

  *_retval = nullptr;

  RefPtr<imgRequest> request;

  nsresult rv;
  nsLoadFlags requestFlags = nsIRequest::LOAD_NORMAL;

#ifdef DEBUG
  bool isPrivate = false;

  if (aLoadingDocument) {
    isPrivate = nsContentUtils::IsInPrivateBrowsing(aLoadingDocument);
  } else if (aLoadGroup) {
    isPrivate = nsContentUtils::IsInPrivateBrowsing(aLoadGroup);
  }
  MOZ_ASSERT(isPrivate == mRespectPrivacy);
#endif

  // Get the default load flags from the loadgroup (if possible)...
  if (aLoadGroup) {
    aLoadGroup->GetLoadFlags(&requestFlags);
  }
  //
  // Merge the default load flags with those passed in via aLoadFlags.
  // Currently, *only* the caching, validation and background load flags
  // are merged...
  //
  // The flags in aLoadFlags take precedence over the default flags!
  //
  if (aLoadFlags & LOAD_FLAGS_CACHE_MASK) {
    // Override the default caching flags...
    requestFlags = (requestFlags & ~LOAD_FLAGS_CACHE_MASK) |
                   (aLoadFlags & LOAD_FLAGS_CACHE_MASK);
  }
  if (aLoadFlags & LOAD_FLAGS_VALIDATE_MASK) {
    // Override the default validation flags...
    requestFlags = (requestFlags & ~LOAD_FLAGS_VALIDATE_MASK) |
                   (aLoadFlags & LOAD_FLAGS_VALIDATE_MASK);
  }
  if (aLoadFlags & nsIRequest::LOAD_BACKGROUND) {
    // Propagate background loading...
    requestFlags |= nsIRequest::LOAD_BACKGROUND;
  }

  int32_t corsmode = imgIRequest::CORS_NONE;
  if (aLoadFlags & imgILoader::LOAD_CORS_ANONYMOUS) {
    corsmode = imgIRequest::CORS_ANONYMOUS;
  } else if (aLoadFlags & imgILoader::LOAD_CORS_USE_CREDENTIALS) {
    corsmode = imgIRequest::CORS_USE_CREDENTIALS;
  }

  RefPtr<imgCacheEntry> entry;

  // Look in the cache for our URI, and then validate it.
  // XXX For now ignore aCacheKey. We will need it in the future
  // for correctly dealing with image load requests that are a result
  // of post data.
  OriginAttributes attrs;
  if (aLoadingPrincipal) {
    attrs = aLoadingPrincipal->OriginAttributesRef();
  }
  ImageCacheKey key(aURI, attrs, aLoadingDocument, rv);
  NS_ENSURE_SUCCESS(rv, rv);
  imgCacheTable& cache = GetCache(key);

  if (cache.Get(key, getter_AddRefs(entry)) && entry) {
    if (ValidateEntry(entry, aURI, aInitialDocumentURI, aReferrerURI,
                      aReferrerPolicy, aLoadGroup, aObserver, aLoadingDocument,
                      aLoadingDocument, requestFlags, aContentPolicyType, true,
                      _retval, aLoadingPrincipal, corsmode)) {
      request = entry->GetRequest();

      // If this entry has no proxies, its request has no reference to the
      // entry.
      if (entry->HasNoProxies()) {
        LOG_FUNC_WITH_PARAM(gImgLog,
          "imgLoader::LoadImage() adding proxyless entry", "uri", key.Spec());
        MOZ_ASSERT(!request->HasCacheEntry(),
          "Proxyless entry's request has cache entry!");
        request->SetCacheEntry(entry);

        if (mCacheTracker && entry->GetExpirationState()->IsTracked()) {
          mCacheTracker->MarkUsed(entry);
        }
      }

      entry->Touch();

    } else {
      // We can't use this entry. We'll try to load it off the network, and if
      // successful, overwrite the old entry in the cache with a new one.
      entry = nullptr;
    }
  }

  // Keep the channel in this scope, so we can adjust its notificationCallbacks
  // later when we create the proxy.
  nsCOMPtr<nsIChannel> newChannel;
  // If we didn't get a cache hit, we need to load from the network.
  if (!request) {
    LOG_SCOPE(gImgLog, "imgLoader::LoadImage |cache miss|");

    bool forcePrincipalCheck;
    rv = NewImageChannel(getter_AddRefs(newChannel),
                         &forcePrincipalCheck,
                         aURI,
                         aInitialDocumentURI,
                         corsmode,
                         aReferrerURI,
                         aReferrerPolicy,
                         aLoadGroup,
                         mAcceptHeader,
                         requestFlags,
                         aContentPolicyType,
                         aLoadingPrincipal,
                         aContext,
                         mRespectPrivacy);
    if (NS_FAILED(rv)) {
      return NS_ERROR_FAILURE;
    }

    MOZ_ASSERT(NS_UsePrivateBrowsing(newChannel) == mRespectPrivacy);

    NewRequestAndEntry(forcePrincipalCheck, this, key,
                       getter_AddRefs(request),
                       getter_AddRefs(entry));

    MOZ_LOG(gImgLog, LogLevel::Debug,
           ("[this=%p] imgLoader::LoadImage -- Created new imgRequest"
            " [request=%p]\n", this, request.get()));

    nsCOMPtr<nsIClassOfService> cos(do_QueryInterface(newChannel));
    if (cos && aUseUrgentStartForChannel) {
      cos->AddClassFlags(nsIClassOfService::UrgentStart);
    }

    nsCOMPtr<nsILoadGroup> channelLoadGroup;
    newChannel->GetLoadGroup(getter_AddRefs(channelLoadGroup));
    rv = request->Init(aURI, aURI, /* aHadInsecureRedirect = */ false,
                       channelLoadGroup, newChannel, entry, aLoadingDocument,
                       aLoadingPrincipal, corsmode, aReferrerPolicy);
    if (NS_FAILED(rv)) {
      return NS_ERROR_FAILURE;
    }

    // Add the initiator type for this image load
    nsCOMPtr<nsITimedChannel> timedChannel = do_QueryInterface(newChannel);
    if (timedChannel) {
      timedChannel->SetInitiatorType(initiatorType);
    }

    // create the proxy listener
    nsCOMPtr<nsIStreamListener> listener = new ProxyListener(request.get());

    MOZ_LOG(gImgLog, LogLevel::Debug,
           ("[this=%p] imgLoader::LoadImage -- Calling channel->AsyncOpen2()\n",
            this));

    mozilla::net::PredictorLearn(aURI, aInitialDocumentURI,
        nsINetworkPredictor::LEARN_LOAD_SUBRESOURCE, aLoadGroup);

    nsresult openRes = newChannel->AsyncOpen2(listener);

    if (NS_FAILED(openRes)) {
      MOZ_LOG(gImgLog, LogLevel::Debug,
             ("[this=%p] imgLoader::LoadImage -- AsyncOpen2() failed: 0x%" PRIx32 "\n",
              this, static_cast<uint32_t>(openRes)));
      request->CancelAndAbort(openRes);
      return openRes;
    }

    // Try to add the new request into the cache.
    PutIntoCache(key, entry);
  } else {
    LOG_MSG_WITH_PARAM(gImgLog,
                       "imgLoader::LoadImage |cache hit|", "request", request);
  }


  // If we didn't get a proxy when validating the cache entry, we need to
  // create one.
  if (!*_retval) {
    // ValidateEntry() has three return values: "Is valid," "might be valid --
    // validating over network", and "not valid." If we don't have a _retval,
    // we know ValidateEntry is not validating over the network, so it's safe
    // to SetLoadId here because we know this request is valid for this context.
    //
    // Note, however, that this doesn't guarantee the behaviour we want (one
    // URL maps to the same image on a page) if we load the same image in a
    // different tab (see bug 528003), because its load id will get re-set, and
    // that'll cause us to validate over the network.
    request->SetLoadId(aLoadingDocument);

    LOG_MSG(gImgLog, "imgLoader::LoadImage", "creating proxy request.");
    rv = CreateNewProxyForRequest(request, aLoadGroup, aLoadingDocument,
                                  aObserver, requestFlags, _retval);
    if (NS_FAILED(rv)) {
      return rv;
    }

    imgRequestProxy* proxy = *_retval;

    // Make sure that OnStatus/OnProgress calls have the right request set, if
    // we did create a channel here.
    if (newChannel) {
      nsCOMPtr<nsIInterfaceRequestor> requestor(
          new nsProgressNotificationProxy(newChannel, proxy));
      if (!requestor) {
        return NS_ERROR_OUT_OF_MEMORY;
      }
      newChannel->SetNotificationCallbacks(requestor);
    }

    // Note that it's OK to add here even if the request is done.  If it is,
    // it'll send a OnStopRequest() to the proxy in imgRequestProxy::Notify and
    // the proxy will be removed from the loadgroup.
    proxy->AddToLoadGroup();

    // If we're loading off the network, explicitly don't notify our proxy,
    // because necko (or things called from necko, such as imgCacheValidator)
    // are going to call our notifications asynchronously, and we can't make it
    // further asynchronous because observers might rely on imagelib completing
    // its work between the channel's OnStartRequest and OnStopRequest.
    if (!newChannel) {
      proxy->NotifyListener();
    }

    return rv;
  }

  NS_ASSERTION(*_retval, "imgLoader::LoadImage -- no return value");

  return NS_OK;
}

NS_IMETHODIMP
imgLoader::LoadImageWithChannelXPCOM(nsIChannel* channel,
                                     imgINotificationObserver* aObserver,
                                     nsISupports* aCX,
                                     nsIStreamListener** listener,
                                     imgIRequest** _retval)
{
    nsresult result;
    imgRequestProxy* proxy;
    result = LoadImageWithChannel(channel,
                                  aObserver,
                                  aCX,
                                  listener,
                                  &proxy);
    *_retval = proxy;
    return result;
}

nsresult
imgLoader::LoadImageWithChannel(nsIChannel* channel,
                                imgINotificationObserver* aObserver,
                                nsISupports* aCX,
                                nsIStreamListener** listener,
                                imgRequestProxy** _retval)
{
  NS_ASSERTION(channel,
               "imgLoader::LoadImageWithChannel -- NULL channel pointer");

  MOZ_ASSERT(NS_UsePrivateBrowsing(channel) == mRespectPrivacy);

  RefPtr<imgRequest> request;

  nsCOMPtr<nsIURI> uri;
  channel->GetURI(getter_AddRefs(uri));
  nsCOMPtr<nsIDocument> doc = do_QueryInterface(aCX);

  NS_ENSURE_TRUE(channel, NS_ERROR_FAILURE);
  nsCOMPtr<nsILoadInfo> loadInfo = channel->GetLoadInfo();

  OriginAttributes attrs;
  if (loadInfo) {
    attrs = loadInfo->GetOriginAttributes();
  }

  nsresult rv;
  ImageCacheKey key(uri, attrs, doc, rv);
  NS_ENSURE_SUCCESS(rv, rv);

  nsLoadFlags requestFlags = nsIRequest::LOAD_NORMAL;
  channel->GetLoadFlags(&requestFlags);

  RefPtr<imgCacheEntry> entry;

  if (requestFlags & nsIRequest::LOAD_BYPASS_CACHE) {
    RemoveFromCache(key);
  } else {
    // Look in the cache for our URI, and then validate it.
    // XXX For now ignore aCacheKey. We will need it in the future
    // for correctly dealing with image load requests that are a result
    // of post data.
    imgCacheTable& cache = GetCache(key);
    if (cache.Get(key, getter_AddRefs(entry)) && entry) {
      // We don't want to kick off another network load. So we ask
      // ValidateEntry to only do validation without creating a new proxy. If
      // it says that the entry isn't valid any more, we'll only use the entry
      // we're getting if the channel is loading from the cache anyways.
      //
      // XXX -- should this be changed? it's pretty much verbatim from the old
      // code, but seems nonsensical.
      //
      // Since aCanMakeNewChannel == false, we don't need to pass content policy
      // type/principal/etc

      nsCOMPtr<nsILoadInfo> loadInfo = channel->GetLoadInfo();
      // if there is a loadInfo, use the right contentType, otherwise
      // default to the internal image type
      nsContentPolicyType policyType = loadInfo
        ? loadInfo->InternalContentPolicyType()
        : nsIContentPolicy::TYPE_INTERNAL_IMAGE;

      if (ValidateEntry(entry, uri, nullptr, nullptr, RP_Unset,
                        nullptr, aObserver, aCX, doc, requestFlags,
                        policyType, false, nullptr,
                        nullptr, imgIRequest::CORS_NONE)) {
        request = entry->GetRequest();
      } else {
        nsCOMPtr<nsICacheInfoChannel> cacheChan(do_QueryInterface(channel));
        bool bUseCacheCopy;

        if (cacheChan) {
          cacheChan->IsFromCache(&bUseCacheCopy);
        } else {
          bUseCacheCopy = false;
        }

        if (!bUseCacheCopy) {
          entry = nullptr;
        } else {
          request = entry->GetRequest();
        }
      }

      if (request && entry) {
        // If this entry has no proxies, its request has no reference to
        // the entry.
        if (entry->HasNoProxies()) {
          LOG_FUNC_WITH_PARAM(gImgLog,
            "imgLoader::LoadImageWithChannel() adding proxyless entry",
            "uri", key.Spec());
          MOZ_ASSERT(!request->HasCacheEntry(),
            "Proxyless entry's request has cache entry!");
          request->SetCacheEntry(entry);

          if (mCacheTracker && entry->GetExpirationState()->IsTracked()) {
            mCacheTracker->MarkUsed(entry);
          }
        }
      }
    }
  }

  nsCOMPtr<nsILoadGroup> loadGroup;
  channel->GetLoadGroup(getter_AddRefs(loadGroup));

  // Filter out any load flags not from nsIRequest
  requestFlags &= nsIRequest::LOAD_REQUESTMASK;

  rv = NS_OK;
  if (request) {
    // we have this in our cache already.. cancel the current (document) load

    // this should fire an OnStopRequest
    channel->Cancel(NS_ERROR_PARSED_DATA_CACHED);

    *listener = nullptr; // give them back a null nsIStreamListener

    rv = CreateNewProxyForRequest(request, loadGroup, doc, aObserver,
                                  requestFlags, _retval);
    static_cast<imgRequestProxy*>(*_retval)->NotifyListener();
  } else {
    // We use originalURI here to fulfil the imgIRequest contract on GetURI.
    nsCOMPtr<nsIURI> originalURI;
    channel->GetOriginalURI(getter_AddRefs(originalURI));

    // XXX(seth): We should be able to just use |key| here, except that |key| is
    // constructed above with the *current URI* and not the *original URI*. I'm
    // pretty sure this is a bug, and it's preventing us from ever getting a
    // cache hit in LoadImageWithChannel when redirects are involved.
    ImageCacheKey originalURIKey(originalURI, attrs, doc, rv);
    NS_ENSURE_SUCCESS(rv, rv);

    // Default to doing a principal check because we don't know who
    // started that load and whether their principal ended up being
    // inherited on the channel.
    NewRequestAndEntry(/* aForcePrincipalCheckForCacheEntry = */ true,
                       this, originalURIKey,
                       getter_AddRefs(request),
                       getter_AddRefs(entry));

    // No principal specified here, because we're not passed one.
    // In LoadImageWithChannel, the redirects that may have been
    // assoicated with this load would have gone through necko.
    // We only have the final URI in ImageLib and hence don't know
    // if the request went through insecure redirects.  But if it did,
    // the necko cache should have handled that (since all necko cache hits
    // including the redirects will go through content policy).  Hence, we
    // can set aHadInsecureRedirect to false here.
    rv = request->Init(originalURI, uri, /* aHadInsecureRedirect = */ false,
                       channel, channel, entry, aCX, nullptr,
                       imgIRequest::CORS_NONE, RP_Unset);
    NS_ENSURE_SUCCESS(rv, rv);

    RefPtr<ProxyListener> pl =
      new ProxyListener(static_cast<nsIStreamListener*>(request.get()));
    pl.forget(listener);

    // Try to add the new request into the cache.
    PutIntoCache(originalURIKey, entry);

    rv = CreateNewProxyForRequest(request, loadGroup, doc, aObserver,
                                  requestFlags, _retval);

    // Explicitly don't notify our proxy, because we're loading off the
    // network, and necko (or things called from necko, such as
    // imgCacheValidator) are going to call our notifications asynchronously,
    // and we can't make it further asynchronous because observers might rely
    // on imagelib completing its work between the channel's OnStartRequest and
    // OnStopRequest.
  }

  return rv;
}

bool
imgLoader::SupportImageWithMimeType(const char* aMimeType,
                                    AcceptedMimeTypes aAccept
                                      /* = AcceptedMimeTypes::IMAGES */)
{
  nsAutoCString mimeType(aMimeType);
  ToLowerCase(mimeType);

  if (aAccept == AcceptedMimeTypes::IMAGES_AND_DOCUMENTS &&
      mimeType.EqualsLiteral("image/svg+xml")) {
    return true;
  }

  DecoderType type = DecoderFactory::GetDecoderType(mimeType.get());
  return type != DecoderType::UNKNOWN;
}

NS_IMETHODIMP
imgLoader::GetMIMETypeFromContent(nsIRequest* aRequest,
                                  const uint8_t* aContents,
                                  uint32_t aLength,
                                  nsACString& aContentType)
{
  return GetMimeTypeFromContent((const char*)aContents, aLength, aContentType);
}

/* static */
nsresult
imgLoader::GetMimeTypeFromContent(const char* aContents,
                                  uint32_t aLength,
                                  nsACString& aContentType)
{
  /* Is it a GIF? */
  if (aLength >= 6 && (!nsCRT::strncmp(aContents, "GIF87a", 6) ||
                       !nsCRT::strncmp(aContents, "GIF89a", 6))) {
    aContentType.AssignLiteral(IMAGE_GIF);

  /* or a PNG? */
  } else if (aLength >= 8 && ((unsigned char)aContents[0]==0x89 &&
                              (unsigned char)aContents[1]==0x50 &&
                              (unsigned char)aContents[2]==0x4E &&
                              (unsigned char)aContents[3]==0x47 &&
                              (unsigned char)aContents[4]==0x0D &&
                              (unsigned char)aContents[5]==0x0A &&
                              (unsigned char)aContents[6]==0x1A &&
                              (unsigned char)aContents[7]==0x0A)) {
    aContentType.AssignLiteral(IMAGE_PNG);

  /* maybe a JPEG (JFIF)? */
  /* JFIF files start with SOI APP0 but older files can start with SOI DQT
   * so we test for SOI followed by any marker, i.e. FF D8 FF
   * this will also work for SPIFF JPEG files if they appear in the future.
   *
   * (JFIF is 0XFF 0XD8 0XFF 0XE0 <skip 2> 0X4A 0X46 0X49 0X46 0X00)
   */
  } else if (aLength >= 3 &&
             ((unsigned char)aContents[0])==0xFF &&
             ((unsigned char)aContents[1])==0xD8 &&
             ((unsigned char)aContents[2])==0xFF) {
    aContentType.AssignLiteral(IMAGE_JPEG);

  /* or how about ART? */
  /* ART begins with JG (4A 47). Major version offset 2.
   * Minor version offset 3. Offset 4 must be nullptr.
   */
  } else if (aLength >= 5 &&
             ((unsigned char) aContents[0])==0x4a &&
             ((unsigned char) aContents[1])==0x47 &&
             ((unsigned char) aContents[4])==0x00 ) {
    aContentType.AssignLiteral(IMAGE_ART);

  } else if (aLength >= 2 && !nsCRT::strncmp(aContents, "BM", 2)) {
    aContentType.AssignLiteral(IMAGE_BMP);

  // ICOs always begin with a 2-byte 0 followed by a 2-byte 1.
  // CURs begin with 2-byte 0 followed by 2-byte 2.
  } else if (aLength >= 4 && (!memcmp(aContents, "\000\000\001\000", 4) ||
                              !memcmp(aContents, "\000\000\002\000", 4))) {
    aContentType.AssignLiteral(IMAGE_ICO);

  } else {
    /* none of the above?  I give up */
    return NS_ERROR_NOT_AVAILABLE;
  }

  return NS_OK;
}

/**
 * proxy stream listener class used to handle multipart/x-mixed-replace
 */

#include "nsIRequest.h"
#include "nsIStreamConverterService.h"

NS_IMPL_ISUPPORTS(ProxyListener,
                  nsIStreamListener,
                  nsIThreadRetargetableStreamListener,
                  nsIRequestObserver)

ProxyListener::ProxyListener(nsIStreamListener* dest) :
  mDestListener(dest)
{
  /* member initializers and constructor code */
}

ProxyListener::~ProxyListener()
{
  /* destructor code */
}


/** nsIRequestObserver methods **/

NS_IMETHODIMP
ProxyListener::OnStartRequest(nsIRequest* aRequest, nsISupports* ctxt)
{
  if (!mDestListener) {
    return NS_ERROR_FAILURE;
  }

  nsCOMPtr<nsIChannel> channel(do_QueryInterface(aRequest));
  if (channel) {
    // We need to set the initiator type for the image load
    nsCOMPtr<nsITimedChannel> timedChannel = do_QueryInterface(channel);
    if (timedChannel) {
      nsAutoString type;
      timedChannel->GetInitiatorType(type);
      if (type.IsEmpty()) {
        timedChannel->SetInitiatorType(NS_LITERAL_STRING("img"));
      }
    }

    nsAutoCString contentType;
    nsresult rv = channel->GetContentType(contentType);

    if (!contentType.IsEmpty()) {
     /* If multipart/x-mixed-replace content, we'll insert a MIME decoder
        in the pipeline to handle the content and pass it along to our
        original listener.
      */
      if (NS_LITERAL_CSTRING("multipart/x-mixed-replace").Equals(contentType)) {

        nsCOMPtr<nsIStreamConverterService> convServ(
          do_GetService("@mozilla.org/streamConverters;1", &rv));
        if (NS_SUCCEEDED(rv)) {
          nsCOMPtr<nsIStreamListener> toListener(mDestListener);
          nsCOMPtr<nsIStreamListener> fromListener;

          rv = convServ->AsyncConvertData("multipart/x-mixed-replace",
                                          "*/*",
                                          toListener,
                                          nullptr,
                                          getter_AddRefs(fromListener));
          if (NS_SUCCEEDED(rv)) {
            mDestListener = fromListener;
          }
        }
      }
    }
  }

  return mDestListener->OnStartRequest(aRequest, ctxt);
}

NS_IMETHODIMP
ProxyListener::OnStopRequest(nsIRequest* aRequest,
                             nsISupports* ctxt,
                             nsresult status)
{
  if (!mDestListener) {
    return NS_ERROR_FAILURE;
  }

  return mDestListener->OnStopRequest(aRequest, ctxt, status);
}

/** nsIStreamListener methods **/

NS_IMETHODIMP
ProxyListener::OnDataAvailable(nsIRequest* aRequest, nsISupports* ctxt,
                               nsIInputStream* inStr, uint64_t sourceOffset,
                               uint32_t count)
{
  if (!mDestListener) {
    return NS_ERROR_FAILURE;
  }

  return mDestListener->OnDataAvailable(aRequest, ctxt, inStr,
                                        sourceOffset, count);
}

/** nsThreadRetargetableStreamListener methods **/
NS_IMETHODIMP
ProxyListener::CheckListenerChain()
{
  NS_ASSERTION(NS_IsMainThread(), "Should be on the main thread!");
  nsresult rv = NS_OK;
  nsCOMPtr<nsIThreadRetargetableStreamListener> retargetableListener =
    do_QueryInterface(mDestListener, &rv);
  if (retargetableListener) {
    rv = retargetableListener->CheckListenerChain();
  }
  MOZ_LOG(gImgLog, LogLevel::Debug,
         ("ProxyListener::CheckListenerChain %s [this=%p listener=%p rv=%" PRIx32 "]",
          (NS_SUCCEEDED(rv) ? "success" : "failure"),
          this, (nsIStreamListener*)mDestListener, static_cast<uint32_t>(rv)));
  return rv;
}

/**
 * http validate class.  check a channel for a 304
 */

NS_IMPL_ISUPPORTS(imgCacheValidator, nsIStreamListener, nsIRequestObserver,
                  nsIThreadRetargetableStreamListener,
                  nsIChannelEventSink, nsIInterfaceRequestor,
                  nsIAsyncVerifyRedirectCallback)

imgCacheValidator::imgCacheValidator(nsProgressNotificationProxy* progress,
                                     imgLoader* loader, imgRequest* request,
                                     nsISupports* aContext,
                                     bool forcePrincipalCheckForCacheEntry)
 : mProgressProxy(progress),
   mRequest(request),
   mContext(aContext),
   mImgLoader(loader),
   mHadInsecureRedirect(false)
{
  NewRequestAndEntry(forcePrincipalCheckForCacheEntry, loader,
                     mRequest->CacheKey(),
                     getter_AddRefs(mNewRequest),
                     getter_AddRefs(mNewEntry));
}

imgCacheValidator::~imgCacheValidator()
{
  if (mRequest) {
    mRequest->SetValidator(nullptr);
  }
}

void
imgCacheValidator::AddProxy(imgRequestProxy* aProxy)
{
  // aProxy needs to be in the loadgroup since we're validating from
  // the network.
  aProxy->AddToLoadGroup();

  mProxies.AppendObject(aProxy);
}

/** nsIRequestObserver methods **/

NS_IMETHODIMP
imgCacheValidator::OnStartRequest(nsIRequest* aRequest, nsISupports* ctxt)
{
  // We may be holding on to a document, so ensure that it's released.
  nsCOMPtr<nsISupports> context = mContext.forget();

  // If for some reason we don't still have an existing request (probably
  // because OnStartRequest got delivered more than once), just bail.
  if (!mRequest) {
    MOZ_ASSERT_UNREACHABLE("OnStartRequest delivered more than once?");
    aRequest->Cancel(NS_BINDING_ABORTED);
    return NS_ERROR_FAILURE;
  }

  // If this request is coming from cache and has the same URI as our
  // imgRequest, the request all our proxies are pointing at is valid, and all
  // we have to do is tell them to notify their listeners.
  nsCOMPtr<nsICacheInfoChannel> cacheChan(do_QueryInterface(aRequest));
  nsCOMPtr<nsIChannel> channel(do_QueryInterface(aRequest));
  if (cacheChan && channel && !mRequest->CacheChanged(aRequest)) {
    bool isFromCache = false;
    cacheChan->IsFromCache(&isFromCache);

    nsCOMPtr<nsIURI> channelURI;
    channel->GetURI(getter_AddRefs(channelURI));

    nsCOMPtr<nsIURI> currentURI;
    mRequest->GetCurrentURI(getter_AddRefs(currentURI));

    bool sameURI = false;
    if (channelURI && currentURI) {
      channelURI->Equals(currentURI, &sameURI);
    }

    if (isFromCache && sameURI) {
      uint32_t count = mProxies.Count();
      for (int32_t i = count-1; i>=0; i--) {
        imgRequestProxy* proxy = static_cast<imgRequestProxy*>(mProxies[i]);

        // Proxies waiting on cache validation should be deferring
        // notifications. Undefer them.
        MOZ_ASSERT(proxy->NotificationsDeferred(),
                   "Proxies waiting on cache validation should be "
                   "deferring notifications!");
        proxy->SetNotificationsDeferred(false);

        // Notify synchronously, because we're already in OnStartRequest, an
        // asynchronously-called function.
        proxy->SyncNotifyListener();
      }

      // We don't need to load this any more.
      aRequest->Cancel(NS_BINDING_ABORTED);

      mRequest->SetLoadId(context);
      mRequest->SetValidator(nullptr);

      mRequest = nullptr;

      mNewRequest = nullptr;
      mNewEntry = nullptr;

      return NS_OK;
    }
  }

  // We can't load out of cache. We have to create a whole new request for the
  // data that's coming in off the channel.
  nsCOMPtr<nsIURI> uri;
  {
    RefPtr<ImageURL> imageURL;
    mRequest->GetURI(getter_AddRefs(imageURL));
    uri = imageURL->ToIURI();
  }

  if (MOZ_LOG_TEST(gImgLog, LogLevel::Debug)) {
    LOG_MSG_WITH_PARAM(gImgLog,
                       "imgCacheValidator::OnStartRequest creating new request",
                       "uri", uri->GetSpecOrDefault().get());
  }

  int32_t corsmode = mRequest->GetCORSMode();
  ReferrerPolicy refpol = mRequest->GetReferrerPolicy();
  nsCOMPtr<nsIPrincipal> loadingPrincipal = mRequest->GetLoadingPrincipal();

  // Doom the old request's cache entry
  mRequest->RemoveFromCache();

  mRequest->SetValidator(nullptr);
  mRequest = nullptr;

  // We use originalURI here to fulfil the imgIRequest contract on GetURI.
  nsCOMPtr<nsIURI> originalURI;
  channel->GetOriginalURI(getter_AddRefs(originalURI));
  nsresult rv =
    mNewRequest->Init(originalURI, uri, mHadInsecureRedirect, aRequest, channel,
                      mNewEntry, context, loadingPrincipal, corsmode, refpol);
  if (NS_FAILED(rv)) {
    return rv;
  }

  mDestListener = new ProxyListener(mNewRequest);

  // Try to add the new request into the cache. Note that the entry must be in
  // the cache before the proxies' ownership changes, because adding a proxy
  // changes the caching behaviour for imgRequests.
  mImgLoader->PutIntoCache(mNewRequest->CacheKey(), mNewEntry);

  uint32_t count = mProxies.Count();
  for (int32_t i = count-1; i>=0; i--) {
    imgRequestProxy* proxy = static_cast<imgRequestProxy*>(mProxies[i]);
    proxy->ChangeOwner(mNewRequest);

    // Notify synchronously, because we're already in OnStartRequest, an
    // asynchronously-called function.
    proxy->SetNotificationsDeferred(false);
    proxy->SyncNotifyListener();
  }

  mNewRequest = nullptr;
  mNewEntry = nullptr;

  return mDestListener->OnStartRequest(aRequest, ctxt);
}

NS_IMETHODIMP
imgCacheValidator::OnStopRequest(nsIRequest* aRequest,
                                 nsISupports* ctxt,
                                 nsresult status)
{
  // Be sure we've released the document that we may have been holding on to.
  mContext = nullptr;

  if (!mDestListener) {
    return NS_OK;
  }

  return mDestListener->OnStopRequest(aRequest, ctxt, status);
}

/** nsIStreamListener methods **/


NS_IMETHODIMP
imgCacheValidator::OnDataAvailable(nsIRequest* aRequest, nsISupports* ctxt,
                                   nsIInputStream* inStr,
                                   uint64_t sourceOffset, uint32_t count)
{
  if (!mDestListener) {
    // XXX see bug 113959
    uint32_t _retval;
    inStr->ReadSegments(NS_DiscardSegment, nullptr, count, &_retval);
    return NS_OK;
  }

  return mDestListener->OnDataAvailable(aRequest, ctxt, inStr, sourceOffset,
                                        count);
}

/** nsIThreadRetargetableStreamListener methods **/

NS_IMETHODIMP
imgCacheValidator::CheckListenerChain()
{
  NS_ASSERTION(NS_IsMainThread(), "Should be on the main thread!");
  nsresult rv = NS_OK;
  nsCOMPtr<nsIThreadRetargetableStreamListener> retargetableListener =
    do_QueryInterface(mDestListener, &rv);
  if (retargetableListener) {
    rv = retargetableListener->CheckListenerChain();
  }
  MOZ_LOG(gImgLog, LogLevel::Debug,
         ("[this=%p] imgCacheValidator::CheckListenerChain -- rv %" PRId32 "=%s",
          this, static_cast<uint32_t>(rv), NS_SUCCEEDED(rv) ? "succeeded" : "failed"));
  return rv;
}

/** nsIInterfaceRequestor methods **/

NS_IMETHODIMP
imgCacheValidator::GetInterface(const nsIID& aIID, void** aResult)
{
  if (aIID.Equals(NS_GET_IID(nsIChannelEventSink))) {
    return QueryInterface(aIID, aResult);
  }

  return mProgressProxy->GetInterface(aIID, aResult);
}

// These functions are materially the same as the same functions in imgRequest.
// We duplicate them because we're verifying whether cache loads are necessary,
// not unconditionally loading.

/** nsIChannelEventSink methods **/
NS_IMETHODIMP
imgCacheValidator::
  AsyncOnChannelRedirect(nsIChannel* oldChannel,
                         nsIChannel* newChannel,
                         uint32_t flags,
                         nsIAsyncVerifyRedirectCallback* callback)
{
  // Note all cache information we get from the old channel.
  mNewRequest->SetCacheValidation(mNewEntry, oldChannel);

  // If the previous URI is a non-HTTPS URI, record that fact for later use by
  // security code, which needs to know whether there is an insecure load at any
  // point in the redirect chain.
  nsCOMPtr<nsIURI> oldURI;
  bool isHttps = false;
  bool isChrome = false;
  bool schemeLocal = false;
  if (NS_FAILED(oldChannel->GetURI(getter_AddRefs(oldURI))) ||
      NS_FAILED(oldURI->SchemeIs("https", &isHttps)) ||
      NS_FAILED(oldURI->SchemeIs("chrome", &isChrome)) ||
      NS_FAILED(NS_URIChainHasFlags(oldURI,
                                    nsIProtocolHandler::URI_IS_LOCAL_RESOURCE,
                                    &schemeLocal))  ||
      (!isHttps && !isChrome && !schemeLocal)) {
    mHadInsecureRedirect = true;
  }

  // Prepare for callback
  mRedirectCallback = callback;
  mRedirectChannel = newChannel;

  return mProgressProxy->AsyncOnChannelRedirect(oldChannel, newChannel, flags,
                                                this);
}

NS_IMETHODIMP
imgCacheValidator::OnRedirectVerifyCallback(nsresult aResult)
{
  // If we've already been told to abort, just do so.
  if (NS_FAILED(aResult)) {
      mRedirectCallback->OnRedirectVerifyCallback(aResult);
      mRedirectCallback = nullptr;
      mRedirectChannel = nullptr;
      return NS_OK;
  }

  // make sure we have a protocol that returns data rather than opens
  // an external application, e.g. mailto:
  nsCOMPtr<nsIURI> uri;
  mRedirectChannel->GetURI(getter_AddRefs(uri));
  bool doesNotReturnData = false;
  NS_URIChainHasFlags(uri, nsIProtocolHandler::URI_DOES_NOT_RETURN_DATA,
                      &doesNotReturnData);

  nsresult result = NS_OK;

  if (doesNotReturnData) {
    result = NS_ERROR_ABORT;
  }

  mRedirectCallback->OnRedirectVerifyCallback(result);
  mRedirectCallback = nullptr;
  mRedirectChannel = nullptr;
  return NS_OK;
}