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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "imgRequest.h"
#include "ImageLogging.h"

#include "imgLoader.h"
#include "imgRequestProxy.h"
#include "DecodePool.h"
#include "ProgressTracker.h"
#include "ImageFactory.h"
#include "Image.h"
#include "MultipartImage.h"
#include "RasterImage.h"

#include "nsIChannel.h"
#include "nsICachingChannel.h"
#include "nsIThreadRetargetableRequest.h"
#include "nsIInputStream.h"
#include "nsIMultiPartChannel.h"
#include "nsIHttpChannel.h"
#include "nsIApplicationCache.h"
#include "nsIApplicationCacheChannel.h"
#include "nsMimeTypes.h"

#include "nsIInterfaceRequestorUtils.h"
#include "nsISupportsPrimitives.h"
#include "nsIScriptSecurityManager.h"
#include "nsContentUtils.h"

#include "nsICacheEntry.h"

#include "plstr.h" // PL_strcasestr(...)
#include "nsNetUtil.h"
#include "nsIProtocolHandler.h"
#include "imgIRequest.h"

using namespace mozilla;
using namespace mozilla::image;

#if defined(PR_LOGGING)
PRLogModuleInfo*
GetImgLog()
{
  static PRLogModuleInfo* sImgLog;
  if (!sImgLog)
    sImgLog = PR_NewLogModule("imgRequest");
  return sImgLog;
}
#define LOG_TEST(level) (GetImgLog() && PR_LOG_TEST(GetImgLog(), (level)))
#else
#define LOG_TEST(level) false
#endif

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

imgRequest::imgRequest(imgLoader* aLoader)
 : mLoader(aLoader)
 , mProgressTracker(new ProgressTracker())
 , mValidator(nullptr)
 , mMutex("imgRequest")
 , mInnerWindowId(0)
 , mCORSMode(imgIRequest::CORS_NONE)
 , mReferrerPolicy(mozilla::net::RP_Default)
 , mImageErrorCode(NS_OK)
 , mDecodeRequested(false)
 , mIsMultiPartChannel(false)
 , mGotData(false)
 , mIsInCache(false)
 , mNewPartPending(false)
{ }

imgRequest::~imgRequest()
{
  if (mLoader) {
    mLoader->RemoveFromUncachedImages(this);
  }
  if (mURI) {
    nsAutoCString spec;
    mURI->GetSpec(spec);
    LOG_FUNC_WITH_PARAM(GetImgLog(), "imgRequest::~imgRequest()", "keyuri", spec.get());
  } else
    LOG_FUNC(GetImgLog(), "imgRequest::~imgRequest()");
}

nsresult imgRequest::Init(nsIURI *aURI,
                          nsIURI *aCurrentURI,
                          nsIRequest *aRequest,
                          nsIChannel *aChannel,
                          imgCacheEntry *aCacheEntry,
                          void *aLoadId,
                          nsIPrincipal* aLoadingPrincipal,
                          int32_t aCORSMode,
                          ReferrerPolicy aReferrerPolicy)
{
  MOZ_ASSERT(NS_IsMainThread(), "Cannot use nsIURI off main thread!");

  LOG_FUNC(GetImgLog(), "imgRequest::Init");

  MOZ_ASSERT(!mImage, "Multiple calls to init");
  MOZ_ASSERT(aURI, "No uri");
  MOZ_ASSERT(aCurrentURI, "No current uri");
  MOZ_ASSERT(aRequest, "No request");
  MOZ_ASSERT(aChannel, "No channel");

  mProperties = do_CreateInstance("@mozilla.org/properties;1");

  // Use ImageURL to ensure access to URI data off main thread.
  mURI = new ImageURL(aURI);
  mCurrentURI = aCurrentURI;
  mRequest = aRequest;
  mChannel = aChannel;
  mTimedChannel = do_QueryInterface(mChannel);

  mLoadingPrincipal = aLoadingPrincipal;
  mCORSMode = aCORSMode;
  mReferrerPolicy = aReferrerPolicy;

  mChannel->GetNotificationCallbacks(getter_AddRefs(mPrevChannelSink));

  NS_ASSERTION(mPrevChannelSink != this,
               "Initializing with a channel that already calls back to us!");

  mChannel->SetNotificationCallbacks(this);

  mCacheEntry = aCacheEntry;

  SetLoadId(aLoadId);

  return NS_OK;
}

void imgRequest::ClearLoader() {
  mLoader = nullptr;
}

already_AddRefed<Image>
imgRequest::GetImage()
{
  MutexAutoLock lock(mMutex);

  nsRefPtr<Image> image = mImage;
  return image.forget();
}

already_AddRefed<ProgressTracker>
imgRequest::GetProgressTracker()
{
  MutexAutoLock lock(mMutex);

  if (mImage) {
    MOZ_ASSERT(!mProgressTracker,
               "Should have given mProgressTracker to mImage");
    return mImage->GetProgressTracker();
  } else {
    MOZ_ASSERT(mProgressTracker,
               "Should have mProgressTracker until we create mImage");
    nsRefPtr<ProgressTracker> progressTracker = mProgressTracker;
    MOZ_ASSERT(progressTracker);
    return progressTracker.forget();
  }
}

void
imgRequest::SetImage(Image* aImage)
{
  MutexAutoLock lock(mMutex);
  mImage = aImage;
}

void
imgRequest::SetProgressTracker(ProgressTracker* aProgressTracker)
{
  MutexAutoLock lock(mMutex);
  mProgressTracker = aProgressTracker;
}

void imgRequest::SetCacheEntry(imgCacheEntry *entry)
{
  mCacheEntry = entry;
}

bool imgRequest::HasCacheEntry() const
{
  return mCacheEntry != nullptr;
}

void imgRequest::ResetCacheEntry()
{
  if (HasCacheEntry()) {
    mCacheEntry->SetDataSize(0);
  }
}

void imgRequest::AddProxy(imgRequestProxy *proxy)
{
  NS_PRECONDITION(proxy, "null imgRequestProxy passed in");
  LOG_SCOPE_WITH_PARAM(GetImgLog(), "imgRequest::AddProxy", "proxy", proxy);

  // If we're empty before adding, we have to tell the loader we now have
  // proxies.
  nsRefPtr<ProgressTracker> progressTracker = GetProgressTracker();
  if (progressTracker->ObserverCount() == 0) {
    MOZ_ASSERT(mURI, "Trying to SetHasProxies without key uri.");
    if (mLoader) {
      mLoader->SetHasProxies(this);
    }
  }

  progressTracker->AddObserver(proxy);
}

nsresult imgRequest::RemoveProxy(imgRequestProxy *proxy, nsresult aStatus)
{
  LOG_SCOPE_WITH_PARAM(GetImgLog(), "imgRequest::RemoveProxy", "proxy", proxy);

  // This will remove our animation consumers, so after removing
  // this proxy, we don't end up without proxies with observers, but still
  // have animation consumers.
  proxy->ClearAnimationConsumers();

  // Let the status tracker do its thing before we potentially call Cancel()
  // below, because Cancel() may result in OnStopRequest being called back
  // before Cancel() returns, leaving the image in a different state then the
  // one it was in at this point.
  nsRefPtr<ProgressTracker> progressTracker = GetProgressTracker();
  if (!progressTracker->RemoveObserver(proxy))
    return NS_OK;

  if (progressTracker->ObserverCount() == 0) {
    // If we have no observers, there's nothing holding us alive. If we haven't
    // been cancelled and thus removed from the cache, tell the image loader so
    // we can be evicted from the cache.
    if (mCacheEntry) {
      MOZ_ASSERT(mURI, "Removing last observer without key uri.");

      if (mLoader) {
        mLoader->SetHasNoProxies(this, mCacheEntry);
      }
    }
#if defined(PR_LOGGING)
    else {
      nsAutoCString spec;
      mURI->GetSpec(spec);
      LOG_MSG_WITH_PARAM(GetImgLog(), "imgRequest::RemoveProxy no cache entry", "uri", spec.get());
    }
#endif

    /* If |aStatus| is a failure code, then cancel the load if it is still in progress.
       Otherwise, let the load continue, keeping 'this' in the cache with no observers.
       This way, if a proxy is destroyed without calling cancel on it, it won't leak
       and won't leave a bad pointer in the observer list.
     */
    if (!(progressTracker->GetProgress() & FLAG_LAST_PART_COMPLETE) &&
        NS_FAILED(aStatus)) {
      LOG_MSG(GetImgLog(), "imgRequest::RemoveProxy", "load in progress.  canceling");

      this->Cancel(NS_BINDING_ABORTED);
    }

    /* break the cycle from the cache entry. */
    mCacheEntry = nullptr;
  }

  // If a proxy is removed for a reason other than its owner being
  // changed, remove the proxy from the loadgroup.
  if (aStatus != NS_IMAGELIB_CHANGING_OWNER)
    proxy->RemoveFromLoadGroup(true);

  return NS_OK;
}

void imgRequest::CancelAndAbort(nsresult aStatus)
{
  LOG_SCOPE(GetImgLog(), "imgRequest::CancelAndAbort");

  Cancel(aStatus);

  // It's possible for the channel to fail to open after we've set our
  // notification callbacks. In that case, make sure to break the cycle between
  // the channel and us, because it won't.
  if (mChannel) {
    mChannel->SetNotificationCallbacks(mPrevChannelSink);
    mPrevChannelSink = nullptr;
  }
}

class imgRequestMainThreadCancel : public nsRunnable
{
public:
  imgRequestMainThreadCancel(imgRequest *aImgRequest, nsresult aStatus)
    : mImgRequest(aImgRequest)
    , mStatus(aStatus)
  {
    MOZ_ASSERT(!NS_IsMainThread(), "Create me off main thread only!");
    MOZ_ASSERT(aImgRequest);
  }

  NS_IMETHOD Run()
  {
    MOZ_ASSERT(NS_IsMainThread(), "I should be running on the main thread!");
    mImgRequest->ContinueCancel(mStatus);
    return NS_OK;
  } 
private:
  nsRefPtr<imgRequest> mImgRequest;
  nsresult mStatus;
};

void imgRequest::Cancel(nsresult aStatus)
{
  /* The Cancel() method here should only be called by this class. */
  LOG_SCOPE(GetImgLog(), "imgRequest::Cancel");

  if (NS_IsMainThread()) {
    ContinueCancel(aStatus);
  } else {
    NS_DispatchToMainThread(new imgRequestMainThreadCancel(this, aStatus));
  }
}

void imgRequest::ContinueCancel(nsresult aStatus)
{
  MOZ_ASSERT(NS_IsMainThread());

  nsRefPtr<ProgressTracker> progressTracker = GetProgressTracker();
  progressTracker->SyncNotifyProgress(FLAG_HAS_ERROR | FLAG_ONLOAD_UNBLOCKED);

  RemoveFromCache();

  if (mRequest && !(progressTracker->GetProgress() & FLAG_LAST_PART_COMPLETE)) {
     mRequest->Cancel(aStatus);
  }
}

class imgRequestMainThreadEvict : public nsRunnable
{
public:
  explicit imgRequestMainThreadEvict(imgRequest *aImgRequest)
    : mImgRequest(aImgRequest)
  {
    MOZ_ASSERT(!NS_IsMainThread(), "Create me off main thread only!");
    MOZ_ASSERT(aImgRequest);
  }

  NS_IMETHOD Run()
  {
    MOZ_ASSERT(NS_IsMainThread(), "I should be running on the main thread!");
    mImgRequest->ContinueEvict();
    return NS_OK;
  }
private:
  nsRefPtr<imgRequest> mImgRequest;
};

// EvictFromCache() is written to allowed to get called from any thread
void imgRequest::EvictFromCache()
{
  /* The EvictFromCache() method here should only be called by this class. */
  LOG_SCOPE(GetImgLog(), "imgRequest::EvictFromCache");

  if (NS_IsMainThread()) {
    ContinueEvict();
  } else {
    NS_DispatchToMainThread(new imgRequestMainThreadEvict(this));
  }
}

// Helper-method used by EvictFromCache()
void imgRequest::ContinueEvict()
{
  MOZ_ASSERT(NS_IsMainThread());

  RemoveFromCache();
}

nsresult imgRequest::GetURI(ImageURL **aURI)
{
  MOZ_ASSERT(aURI);

  LOG_FUNC(GetImgLog(), "imgRequest::GetURI");

  if (mURI) {
    *aURI = mURI;
    NS_ADDREF(*aURI);
    return NS_OK;
  }

  return NS_ERROR_FAILURE;
}

nsresult imgRequest::GetCurrentURI(nsIURI **aURI)
{
  MOZ_ASSERT(aURI);

  LOG_FUNC(GetImgLog(), "imgRequest::GetCurrentURI");

  if (mCurrentURI) {
    *aURI = mCurrentURI;
    NS_ADDREF(*aURI);
    return NS_OK;
  }

  return NS_ERROR_FAILURE;
}

nsresult imgRequest::GetImageErrorCode()
{
  return mImageErrorCode;
}

nsresult imgRequest::GetSecurityInfo(nsISupports **aSecurityInfo)
{
  LOG_FUNC(GetImgLog(), "imgRequest::GetSecurityInfo");

  // Missing security info means this is not a security load
  // i.e. it is not an error when security info is missing
  NS_IF_ADDREF(*aSecurityInfo = mSecurityInfo);
  return NS_OK;
}

void imgRequest::RemoveFromCache()
{
  LOG_SCOPE(GetImgLog(), "imgRequest::RemoveFromCache");

  if (mIsInCache && mLoader) {
    // mCacheEntry is nulled out when we have no more observers.
    if (mCacheEntry) {
      mLoader->RemoveFromCache(mCacheEntry);
    } else {
      mLoader->RemoveFromCache(mURI);
    }
  }

  mCacheEntry = nullptr;
}

bool imgRequest::HasConsumers()
{
  nsRefPtr<ProgressTracker> progressTracker = GetProgressTracker();
  return progressTracker && progressTracker->ObserverCount() > 0;
}

int32_t imgRequest::Priority() const
{
  int32_t priority = nsISupportsPriority::PRIORITY_NORMAL;
  nsCOMPtr<nsISupportsPriority> p = do_QueryInterface(mRequest);
  if (p)
    p->GetPriority(&priority);
  return priority;
}

void imgRequest::AdjustPriority(imgRequestProxy *proxy, int32_t delta)
{
  // only the first proxy is allowed to modify the priority of this image load.
  //
  // XXX(darin): this is probably not the most optimal algorithm as we may want
  // to increase the priority of requests that have a lot of proxies.  the key
  // concern though is that image loads remain lower priority than other pieces
  // of content such as link clicks, CSS, and JS.
  //
  nsRefPtr<ProgressTracker> progressTracker = GetProgressTracker();
  if (!progressTracker->FirstObserverIs(proxy))
    return;

  nsCOMPtr<nsISupportsPriority> p = do_QueryInterface(mChannel);
  if (p)
    p->AdjustPriority(delta);
}

void imgRequest::SetIsInCache(bool incache)
{
  LOG_FUNC_WITH_PARAM(GetImgLog(), "imgRequest::SetIsCacheable", "incache", incache);
  mIsInCache = incache;
}

void imgRequest::UpdateCacheEntrySize()
{
  if (mCacheEntry) {
    nsRefPtr<Image> image = GetImage();
    size_t size = image->SizeOfSourceWithComputedFallback(moz_malloc_size_of);
    mCacheEntry->SetDataSize(size);
  }
}

void imgRequest::SetCacheValidation(imgCacheEntry* aCacheEntry, nsIRequest* aRequest)
{
  /* get the expires info */
  if (aCacheEntry) {
    nsCOMPtr<nsICachingChannel> cacheChannel(do_QueryInterface(aRequest));
    if (cacheChannel) {
      nsCOMPtr<nsISupports> cacheToken;
      cacheChannel->GetCacheToken(getter_AddRefs(cacheToken));
      if (cacheToken) {
        nsCOMPtr<nsICacheEntry> entryDesc(do_QueryInterface(cacheToken));
        if (entryDesc) {
          uint32_t expiration;
          /* get the expiration time from the caching channel's token */
          entryDesc->GetExpirationTime(&expiration);

          // Expiration time defaults to 0. We set the expiration time on our
          // entry if it hasn't been set yet.
          if (aCacheEntry->GetExpiryTime() == 0)
            aCacheEntry->SetExpiryTime(expiration);
        }
      }
    }

    // Determine whether the cache entry must be revalidated when we try to use it.
    // Currently, only HTTP specifies this information...
    nsCOMPtr<nsIHttpChannel> httpChannel(do_QueryInterface(aRequest));
    if (httpChannel) {
      bool bMustRevalidate = false;

      httpChannel->IsNoStoreResponse(&bMustRevalidate);

      if (!bMustRevalidate) {
        httpChannel->IsNoCacheResponse(&bMustRevalidate);
      }

      if (!bMustRevalidate) {
        nsAutoCString cacheHeader;

        httpChannel->GetResponseHeader(NS_LITERAL_CSTRING("Cache-Control"),
                                            cacheHeader);
        if (PL_strcasestr(cacheHeader.get(), "must-revalidate")) {
          bMustRevalidate = true;
        }
      }

      // Cache entries default to not needing to validate. We ensure that
      // multiple calls to this function don't override an earlier decision to
      // validate by making validation a one-way decision.
      if (bMustRevalidate)
        aCacheEntry->SetMustValidate(bMustRevalidate);
    }

    // We always need to validate file URIs.
    nsCOMPtr<nsIChannel> channel = do_QueryInterface(aRequest);
    if (channel) {
      nsCOMPtr<nsIURI> uri;
      channel->GetURI(getter_AddRefs(uri));
      bool isfile = false;
      uri->SchemeIs("file", &isfile);
      if (isfile)
        aCacheEntry->SetMustValidate(isfile);
    }
  }
}

namespace { // anon

already_AddRefed<nsIApplicationCache>
GetApplicationCache(nsIRequest* aRequest)
{
  nsresult rv;

  nsCOMPtr<nsIApplicationCacheChannel> appCacheChan = do_QueryInterface(aRequest);
  if (!appCacheChan) {
    return nullptr;
  }

  bool fromAppCache;
  rv = appCacheChan->GetLoadedFromApplicationCache(&fromAppCache);
  NS_ENSURE_SUCCESS(rv, nullptr);

  if (!fromAppCache) {
    return nullptr;
  }

  nsCOMPtr<nsIApplicationCache> appCache;
  rv = appCacheChan->GetApplicationCache(getter_AddRefs(appCache));
  NS_ENSURE_SUCCESS(rv, nullptr);

  return appCache.forget();
}

} // anon

bool
imgRequest::CacheChanged(nsIRequest* aNewRequest)
{
  nsCOMPtr<nsIApplicationCache> newAppCache = GetApplicationCache(aNewRequest);

  // Application cache not involved at all or the same app cache involved
  // in both of the loads (original and new).
  if (newAppCache == mApplicationCache)
    return false;

  // In a rare case it may happen that two objects still refer
  // the same application cache version.
  if (newAppCache && mApplicationCache) {
    nsresult rv;

    nsAutoCString oldAppCacheClientId, newAppCacheClientId;
    rv = mApplicationCache->GetClientID(oldAppCacheClientId);
    NS_ENSURE_SUCCESS(rv, true);
    rv = newAppCache->GetClientID(newAppCacheClientId);
    NS_ENSURE_SUCCESS(rv, true);

    if (oldAppCacheClientId == newAppCacheClientId)
      return false;
  }

  // When we get here, app caches differ or app cache is involved
  // just in one of the loads what we also consider as a change
  // in a loading cache.
  return true;
}

nsresult
imgRequest::LockImage()
{
  nsRefPtr<Image> image = GetImage();
  return image->LockImage();
}

nsresult
imgRequest::UnlockImage()
{
  nsRefPtr<Image> image = GetImage();
  return image->UnlockImage();
}

nsresult
imgRequest::RequestDecode()
{
  // If we've initialized our image, we can request a decode.
  nsRefPtr<Image> image = GetImage();
  if (image) {
    return image->RequestDecode();
  }

  // Otherwise, flag to do it when we get the image
  mDecodeRequested = true;

  return NS_OK;
}

nsresult
imgRequest::StartDecoding()
{
  // If we've initialized our image, we can request a decode.
  nsRefPtr<Image> image = GetImage();
  if (image) {
    return image->StartDecoding();
  }

  // Otherwise, flag to do it when we get the image
  mDecodeRequested = true;

  return NS_OK;
}

/** nsIRequestObserver methods **/

/* void onStartRequest (in nsIRequest request, in nsISupports ctxt); */
NS_IMETHODIMP imgRequest::OnStartRequest(nsIRequest *aRequest, nsISupports *ctxt)
{
  LOG_SCOPE(GetImgLog(), "imgRequest::OnStartRequest");

  mNewPartPending = true;

  // Figure out if we're multipart.
  nsCOMPtr<nsIMultiPartChannel> mpchan(do_QueryInterface(aRequest));
  nsRefPtr<ProgressTracker> progressTracker = GetProgressTracker();
  if (mpchan) {
    mIsMultiPartChannel = true;
  } else {
    MOZ_ASSERT(!mIsMultiPartChannel, "Something went wrong");
  }

  // If we're not multipart, we shouldn't have an image yet
  nsRefPtr<Image> image = GetImage();
  if (image && !mIsMultiPartChannel) {
    MOZ_ASSERT_UNREACHABLE("Already have an image for a non-multipart request");
    Cancel(NS_IMAGELIB_ERROR_FAILURE);
    return NS_ERROR_FAILURE;
  }

  /*
   * If mRequest is null here, then we need to set it so that we'll be able to
   * cancel it if our Cancel() method is called.  Note that this can only
   * happen for multipart channels.  We could simply not null out mRequest for
   * non-last parts, if GetIsLastPart() were reliable, but it's not.  See
   * https://bugzilla.mozilla.org/show_bug.cgi?id=339610
   */
  if (!mRequest) {
    NS_ASSERTION(mpchan,
                 "We should have an mRequest here unless we're multipart");
    nsCOMPtr<nsIChannel> chan;
    mpchan->GetBaseChannel(getter_AddRefs(chan));
    mRequest = chan;
  }

  nsCOMPtr<nsIChannel> channel(do_QueryInterface(aRequest));
  if (channel)
    channel->GetSecurityInfo(getter_AddRefs(mSecurityInfo));

  /* Get our principal */
  nsCOMPtr<nsIChannel> chan(do_QueryInterface(aRequest));
  if (chan) {
    nsCOMPtr<nsIScriptSecurityManager> secMan = nsContentUtils::GetSecurityManager();
    if (secMan) {
      nsresult rv = secMan->GetChannelResultPrincipal(chan,
                                                      getter_AddRefs(mPrincipal));
      if (NS_FAILED(rv)) {
        return rv;
      }
    }
  }

  SetCacheValidation(mCacheEntry, aRequest);

  mApplicationCache = GetApplicationCache(aRequest);

  // Shouldn't we be dead already if this gets hit?  Probably multipart/x-mixed-replace...
  if (progressTracker->ObserverCount() == 0) {
    this->Cancel(NS_IMAGELIB_ERROR_FAILURE);
  }

  // Try to retarget OnDataAvailable to a decode thread.
  nsCOMPtr<nsIHttpChannel> httpChannel = do_QueryInterface(aRequest);
  nsCOMPtr<nsIThreadRetargetableRequest> retargetable =
    do_QueryInterface(aRequest);
  if (httpChannel && retargetable) {
    nsAutoCString mimeType;
    nsresult rv = httpChannel->GetContentType(mimeType);
    if (NS_SUCCEEDED(rv) && !mimeType.EqualsLiteral(IMAGE_SVG_XML)) {
      // Retarget OnDataAvailable to the DecodePool's IO thread.
      nsCOMPtr<nsIEventTarget> target =
        DecodePool::Singleton()->GetIOEventTarget();
      rv = retargetable->RetargetDeliveryTo(target);
    }
    PR_LOG(GetImgLog(), PR_LOG_WARNING,
           ("[this=%p] imgRequest::OnStartRequest -- "
            "RetargetDeliveryTo rv %d=%s\n",
            this, rv, NS_SUCCEEDED(rv) ? "succeeded" : "failed"));
  }

  return NS_OK;
}

/* void onStopRequest (in nsIRequest request, in nsISupports ctxt, in nsresult status); */
NS_IMETHODIMP imgRequest::OnStopRequest(nsIRequest *aRequest, nsISupports *ctxt, nsresult status)
{
  LOG_FUNC(GetImgLog(), "imgRequest::OnStopRequest");
  MOZ_ASSERT(NS_IsMainThread(), "Can't send notifications off-main-thread");

  // XXXldb What if this is a non-last part of a multipart request?
  // xxx before we release our reference to mRequest, lets
  // save the last status that we saw so that the
  // imgRequestProxy will have access to it.
  if (mRequest) {
    mRequest = nullptr;  // we no longer need the request
  }

  // stop holding a ref to the channel, since we don't need it anymore
  if (mChannel) {
    mChannel->SetNotificationCallbacks(mPrevChannelSink);
    mPrevChannelSink = nullptr;
    mChannel = nullptr;
  }

  bool lastPart = true;
  nsCOMPtr<nsIMultiPartChannel> mpchan(do_QueryInterface(aRequest));
  if (mpchan)
    mpchan->GetIsLastPart(&lastPart);

  bool isPartial = false;
  nsRefPtr<Image> image = GetImage();
  if (image && (status == NS_ERROR_NET_PARTIAL_TRANSFER)) {
    isPartial = true;
    status = NS_OK; // fake happy face
  }

  // Tell the image that it has all of the source data. Note that this can
  // trigger a failure, since the image might be waiting for more non-optional
  // data and this is the point where we break the news that it's not coming.
  if (image) {
    nsresult rv = image->OnImageDataComplete(aRequest, ctxt, status, lastPart);

    // If we got an error in the OnImageDataComplete() call, we don't want to
    // proceed as if nothing bad happened. However, we also want to give
    // precedence to failure status codes from necko, since presumably they're
    // more meaningful.
    if (NS_FAILED(rv) && NS_SUCCEEDED(status))
      status = rv;
  }

  // If the request went through, update the cache entry size. Otherwise,
  // cancel the request, which removes us from the cache.
  if (image && NS_SUCCEEDED(status) && !isPartial) {
    // We update the cache entry size here because this is where we finish
    // loading compressed source data, which is part of our size calculus.
    UpdateCacheEntrySize();
  }
  else if (isPartial) {
    // Remove the partial image from the cache.
    this->EvictFromCache();
  }
  else {
    mImageErrorCode = status;

    // if the error isn't "just" a partial transfer
    // stops animations, removes from cache
    this->Cancel(status);
  }

  if (!image) {
    // We have to fire the OnStopRequest notifications ourselves because there's
    // no image capable of doing so.
    Progress progress =
      LoadCompleteProgress(lastPart, /* aError = */ false, status);

    nsRefPtr<ProgressTracker> progressTracker = GetProgressTracker();
    progressTracker->SyncNotifyProgress(progress);
  }

  mTimedChannel = nullptr;
  return NS_OK;
}

struct mimetype_closure
{
  nsACString* newType;
};

/* prototype for these defined below */
static NS_METHOD sniff_mimetype_callback(nsIInputStream* in, void* closure, const char* fromRawSegment,
                                         uint32_t toOffset, uint32_t count, uint32_t *writeCount);

/** nsThreadRetargetableStreamListener methods **/
NS_IMETHODIMP
imgRequest::CheckListenerChain()
{
  // TODO Might need more checking here.
  NS_ASSERTION(NS_IsMainThread(), "Should be on the main thread!");
  return NS_OK;
}

/** nsIStreamListener methods **/

/* void onDataAvailable (in nsIRequest request, in nsISupports ctxt, in nsIInputStream inStr, in unsigned long long sourceOffset, in unsigned long count); */
NS_IMETHODIMP
imgRequest::OnDataAvailable(nsIRequest *aRequest, nsISupports *ctxt,
                            nsIInputStream *inStr, uint64_t sourceOffset,
                            uint32_t count)
{
  LOG_SCOPE_WITH_PARAM(GetImgLog(), "imgRequest::OnDataAvailable", "count", count);

  NS_ASSERTION(aRequest, "imgRequest::OnDataAvailable -- no request!");

  nsresult rv;
  mGotData = true;
  nsRefPtr<Image> image = GetImage();

  if (mNewPartPending) {
    LOG_SCOPE(GetImgLog(), "imgRequest::OnDataAvailable |New part; finding MIME type|");

    mNewPartPending = false;

    mimetype_closure closure;
    nsAutoCString newType;
    closure.newType = &newType;

    /* look at the first few bytes and see if we can tell what the data is from that
     * since servers tend to lie. :(
     */
    uint32_t out;
    inStr->ReadSegments(sniff_mimetype_callback, &closure, count, &out);

    nsCOMPtr<nsIChannel> chan(do_QueryInterface(aRequest));
    if (newType.IsEmpty()) {
      LOG_SCOPE(GetImgLog(), "imgRequest::OnDataAvailable |sniffing of mimetype failed|");

      rv = NS_ERROR_FAILURE;
      if (chan) {
        rv = chan->GetContentType(newType);
      }

      if (NS_FAILED(rv)) {
        PR_LOG(GetImgLog(), PR_LOG_ERROR,
               ("[this=%p] imgRequest::OnDataAvailable -- Content type unavailable from the channel\n",
                this));

        this->Cancel(NS_IMAGELIB_ERROR_FAILURE);

        return NS_BINDING_ABORTED;
      }

      LOG_MSG(GetImgLog(), "imgRequest::OnDataAvailable", "Got content type from the channel");
    }

    mContentType = newType;
    SetProperties(chan);
    bool firstPart = !image;

    LOG_MSG_WITH_PARAM(GetImgLog(), "imgRequest::OnDataAvailable", "content type", mContentType.get());

    // XXX If server lied about mimetype and it's SVG, we may need to copy
    // the data and dispatch back to the main thread, AND tell the channel to
    // dispatch there in the future.

    nsRefPtr<ProgressTracker> progressTracker;
    {
      MutexAutoLock lock(mMutex);
      progressTracker = mProgressTracker;
    }

    // Create the new image and give it ownership of our ProgressTracker.
    if (mIsMultiPartChannel) {
      // Create the ProgressTracker and image for this part.
      nsRefPtr<ProgressTracker> partProgressTracker = new ProgressTracker();
      nsRefPtr<Image> partImage =
        ImageFactory::CreateImage(aRequest, partProgressTracker, mContentType,
                                  mURI, /* aIsMultipart = */ true,
                                  static_cast<uint32_t>(mInnerWindowId));

      if (!image) {
        // First part for a multipart channel. Create the MultipartImage wrapper.
        MOZ_ASSERT(progressTracker, "Shouldn't have given away tracker yet");
        image = new MultipartImage(partImage, progressTracker);
        SetImage(image);
        progressTracker = nullptr;
        SetProgressTracker(nullptr);
      } else {
        // Transition to the new part.
        static_cast<MultipartImage*>(image.get())->BeginTransitionToPart(partImage);
      }
    } else {
      MOZ_ASSERT(!image, "New part for non-multipart channel?");
      MOZ_ASSERT(progressTracker, "Shouldn't have given away tracker yet");

      // Create an image using our progress tracker.
      image =
        ImageFactory::CreateImage(aRequest, progressTracker, mContentType,
                                  mURI, /* aIsMultipart = */ false,
                                  static_cast<uint32_t>(mInnerWindowId));
      SetImage(image);
      progressTracker = nullptr;
      SetProgressTracker(nullptr);
    }

    if (firstPart) {
      // Notify listeners that we have an image.
      nsRefPtr<ProgressTracker> progressTracker = GetProgressTracker();
      progressTracker->OnImageAvailable();
      MOZ_ASSERT(progressTracker->HasImage());
    }

    if (image->HasError() && !mIsMultiPartChannel) { // Probably bad mimetype
      // We allow multipart images to fail to initialize without cancelling the
      // load because subsequent images might be fine; thus only single part
      // images end up here.
      this->Cancel(NS_IMAGELIB_ERROR_FAILURE);
      return NS_BINDING_ABORTED;
    }

    MOZ_ASSERT(!progressTracker, "Should've given tracker to image");
    MOZ_ASSERT(image, "Should have image");

    if (mDecodeRequested) {
      image->StartDecoding();
    }
  }

  // Notify the image that it has new data.
  rv = image->OnImageDataAvailable(aRequest, ctxt, inStr, sourceOffset, count);

  if (NS_FAILED(rv)) {
    PR_LOG(GetImgLog(), PR_LOG_WARNING,
           ("[this=%p] imgRequest::OnDataAvailable -- "
            "copy to RasterImage failed\n", this));
    this->Cancel(NS_IMAGELIB_ERROR_FAILURE);
    return NS_BINDING_ABORTED;
  }

  return NS_OK;
}

class SetPropertiesEvent : public nsRunnable
{
public:
  SetPropertiesEvent(imgRequest* aImgRequest, nsIChannel* aChan)
    : mImgRequest(aImgRequest)
    , mChan(aChan)
  {
    MOZ_ASSERT(!NS_IsMainThread(), "Should be created off the main thread");
    MOZ_ASSERT(aImgRequest, "aImgRequest cannot be null");
  }
  NS_IMETHOD Run()
  {
    MOZ_ASSERT(NS_IsMainThread(), "Should run on the main thread only");
    MOZ_ASSERT(mImgRequest, "mImgRequest cannot be null");
    mImgRequest->SetProperties(mChan);
    return NS_OK;
  }
private:
  nsRefPtr<imgRequest> mImgRequest;
  nsCOMPtr<nsIChannel> mChan;
};

void
imgRequest::SetProperties(nsIChannel* aChan)
{
  // Force execution on main thread since some property objects are non
  // threadsafe.
  if (!NS_IsMainThread()) {
    NS_DispatchToMainThread(new SetPropertiesEvent(this, aChan));
    return;
  }
  /* set our mimetype as a property */
  nsCOMPtr<nsISupportsCString> contentType(do_CreateInstance("@mozilla.org/supports-cstring;1"));
  if (contentType) {
    contentType->SetData(mContentType);
    mProperties->Set("type", contentType);
  }

  /* set our content disposition as a property */
  nsAutoCString disposition;
  if (aChan) {
    aChan->GetContentDispositionHeader(disposition);
  }
  if (!disposition.IsEmpty()) {
    nsCOMPtr<nsISupportsCString> contentDisposition(do_CreateInstance("@mozilla.org/supports-cstring;1"));
    if (contentDisposition) {
      contentDisposition->SetData(disposition);
      mProperties->Set("content-disposition", contentDisposition);
    }
  }
}

static NS_METHOD sniff_mimetype_callback(nsIInputStream* in,
                                         void* data,
                                         const char* fromRawSegment,
                                         uint32_t toOffset,
                                         uint32_t count,
                                         uint32_t *writeCount)
{
  mimetype_closure* closure = static_cast<mimetype_closure*>(data);

  NS_ASSERTION(closure, "closure is null!");

  if (count > 0)
    imgLoader::GetMimeTypeFromContent(fromRawSegment, count, *closure->newType);

  *writeCount = 0;
  return NS_ERROR_FAILURE;
}


/** nsIInterfaceRequestor methods **/

NS_IMETHODIMP
imgRequest::GetInterface(const nsIID & aIID, void **aResult)
{
  if (!mPrevChannelSink || aIID.Equals(NS_GET_IID(nsIChannelEventSink)))
    return QueryInterface(aIID, aResult);

  NS_ASSERTION(mPrevChannelSink != this,
               "Infinite recursion - don't keep track of channel sinks that are us!");
  return mPrevChannelSink->GetInterface(aIID, aResult);
}

/** nsIChannelEventSink methods **/
NS_IMETHODIMP
imgRequest::AsyncOnChannelRedirect(nsIChannel *oldChannel,
                                   nsIChannel *newChannel, uint32_t flags,
                                   nsIAsyncVerifyRedirectCallback *callback)
{
  NS_ASSERTION(mRequest && mChannel, "Got a channel redirect after we nulled out mRequest!");
  NS_ASSERTION(mChannel == oldChannel, "Got a channel redirect for an unknown channel!");
  NS_ASSERTION(newChannel, "Got a redirect to a NULL channel!");

  SetCacheValidation(mCacheEntry, oldChannel);

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

  nsCOMPtr<nsIChannelEventSink> sink(do_GetInterface(mPrevChannelSink));
  if (sink) {
    nsresult rv = sink->AsyncOnChannelRedirect(oldChannel, newChannel, flags,
                                               this);
    if (NS_FAILED(rv)) {
        mRedirectCallback = nullptr;
        mNewRedirectChannel = nullptr;
    }
    return rv;
  }

  (void) OnRedirectVerifyCallback(NS_OK);
  return NS_OK;
}

NS_IMETHODIMP
imgRequest::OnRedirectVerifyCallback(nsresult result)
{
  NS_ASSERTION(mRedirectCallback, "mRedirectCallback not set in callback");
  NS_ASSERTION(mNewRedirectChannel, "mNewRedirectChannel not set in callback");

  if (NS_FAILED(result)) {
      mRedirectCallback->OnRedirectVerifyCallback(result);
      mRedirectCallback = nullptr;
      mNewRedirectChannel = nullptr;
      return NS_OK;
  }

  mChannel = mNewRedirectChannel;
  mTimedChannel = do_QueryInterface(mChannel);
  mNewRedirectChannel = nullptr;

  if (LOG_TEST(PR_LOG_DEBUG)) {
    nsAutoCString spec;
    if (mCurrentURI)
      mCurrentURI->GetSpec(spec);
    LOG_MSG_WITH_PARAM(GetImgLog(), "imgRequest::OnChannelRedirect", "old", spec.get());
  }

  // make sure we have a protocol that returns data rather than opens
  // an external application, e.g. mailto:
  mChannel->GetURI(getter_AddRefs(mCurrentURI));

  if (LOG_TEST(PR_LOG_DEBUG)) {
    nsAutoCString spec;
    if (mCurrentURI)
      mCurrentURI->GetSpec(spec);
    LOG_MSG_WITH_PARAM(GetImgLog(), "imgRequest::OnChannelRedirect", "new", spec.get());
  }

  bool doesNotReturnData = false;
  nsresult rv =
    NS_URIChainHasFlags(mCurrentURI, nsIProtocolHandler::URI_DOES_NOT_RETURN_DATA,
                        &doesNotReturnData);

  if (NS_SUCCEEDED(rv) && doesNotReturnData)
    rv = NS_ERROR_ABORT;

  if (NS_FAILED(rv)) {
    mRedirectCallback->OnRedirectVerifyCallback(rv);
    mRedirectCallback = nullptr;
    return NS_OK;
  }

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