Commit c49c7f3b authored by Richard Pospesel's avatar Richard Pospesel
Browse files

Bug 1532486 - Ensure media cache is memory-only when in Private Browsing Mode r=jya,xeonchen 

When in private browsing mode and the
'browser.privatebrowsing.forceMediaMemoryCache' pref is set to 'true'
MediaCache::GetMediaCache will only return an in-memory cache to avoid
disk leakage.

Differential Revision: https://phabricator.services.mozilla.com/D22337

--HG--
extra : moz-landing-system : lando
parent 2c43c377

dom/media/MediaCache.cpp

+49 −10
Original line number Diff line number Diff line
@@ -158,7 +158,10 @@ class MediaCache { 
  // If the length is known and considered small enough, a discrete MediaCache

  // with memory backing will be given. Otherwise the one MediaCache with

  // file backing will be provided.

  static RefPtr<MediaCache> GetMediaCache(int64_t aContentLength);

  // If aIsPrivateBrowsing is true, only initialization of a memory backed

  // MediaCache will be attempted, returning nullptr if that fails.

  static RefPtr<MediaCache> GetMediaCache(int64_t aContentLength,

                                          bool aIsPrivateBrowsing);



  nsISerialEventTarget* OwnerThread() const { return sThread; }
@@ -763,7 +766,8 @@ void MediaCache::CloseStreamsForPrivateBrowsing() { 
}



/* static */

RefPtr<MediaCache> MediaCache::GetMediaCache(int64_t aContentLength) {

RefPtr<MediaCache> MediaCache::GetMediaCache(int64_t aContentLength,

                                             bool aIsPrivateBrowsing) {

  NS_ASSERTION(NS_IsMainThread(), "Only call on main thread");



  if (!sThreadInit) {
@@ -791,11 +795,41 @@ RefPtr<MediaCache> MediaCache::GetMediaCache(int64_t aContentLength) { 
    return nullptr;

  }



  if (aContentLength > 0 &&

      aContentLength <=

          int64_t(StaticPrefs::media_memory_cache_max_size()) * 1024) {

    // Small-enough resource, use a new memory-backed MediaCache.

    RefPtr<MediaBlockCacheBase> bc = new MemoryBlockCache(aContentLength);

  const int64_t mediaMemoryCacheMaxSize =

      static_cast<int64_t>(StaticPrefs::media_memory_cache_max_size()) * 1024;



  // Force usage of in-memory cache if we are in private browsing mode

  // and the forceMediaMemoryCache pref is set

  // We will not attempt to create an on-disk cache if this is the case

  const bool forceMediaMemoryCache =

      aIsPrivateBrowsing &&

      StaticPrefs::browser_privatebrowsing_forceMediaMemoryCache();



  // Alternatively, use an in-memory cache if the media will fit entirely

  // in memory

  // aContentLength < 0 indicates we do not know content's actual size

  const bool contentFitsInMediaMemoryCache =

      (aContentLength > 0) && (aContentLength <= mediaMemoryCacheMaxSize);



  // Try to allocate a memory cache for our content

  if (contentFitsInMediaMemoryCache || forceMediaMemoryCache) {

    // Figure out how large our cache should be

    int64_t cacheSize = 0;

    if (contentFitsInMediaMemoryCache) {

      cacheSize = aContentLength;

    } else if (forceMediaMemoryCache) {

      // Unknown content length, we'll give the maximum allowed cache size

      // just to be sure.

      if (aContentLength < 0) {

        cacheSize = mediaMemoryCacheMaxSize;

      } else {

        // If the content length is less than the maximum allowed cache size,

        // use that, otherwise we cap it to max size.

        cacheSize = std::min(aContentLength, mediaMemoryCacheMaxSize);

      }

    }



    RefPtr<MediaBlockCacheBase> bc = new MemoryBlockCache(cacheSize);

    nsresult rv = bc->Init();

    if (NS_SUCCEEDED(rv)) {

      RefPtr<MediaCache> mc = new MediaCache(bc);
@@ -803,8 +837,13 @@ RefPtr<MediaCache> MediaCache::GetMediaCache(int64_t aContentLength) { 
          mc.get());

      return mc;

    }

    // MemoryBlockCache initialization failed, clean up and try for a

    // file-backed MediaCache below.



    // MemoryBlockCache initialization failed.

    // If we require use of a memory media cache, we will bail here.

    // Otherwise use a file-backed MediaCache below.

    if (forceMediaMemoryCache) {

      return nullptr;

    }

  }



  if (gMediaCache) {
@@ -2658,7 +2697,7 @@ nsresult MediaCacheStream::Init(int64_t aContentLength) { 
    mStreamLength = aContentLength;

  }



  mMediaCache = MediaCache::GetMediaCache(aContentLength);

  mMediaCache = MediaCache::GetMediaCache(aContentLength, mIsPrivateBrowsing);

  if (!mMediaCache) {

    return NS_ERROR_FAILURE;

  }

modules/libpref/init/StaticPrefList.yaml

+6 −0
Original line number Diff line number Diff line
@@ -903,6 +903,12 @@ 
  value: true

  mirror: always



# Force usage of in-memory (rather than file on disk) media cache for video streaming when private browsing

- name: browser.privatebrowsing.forceMediaMemoryCache

  type: bool

  value: false

  mirror: always



# Blocked plugin content

- name: browser.safebrowsing.blockedURIs.enabled

  type: bool