Bug 1125776: Part5. Limit metadata parsing to init segment size if known. r=kinetik

dom/media/webm/WebMBufferedParser.cpp

@@ -340,6 +340,7 @@ void WebMBufferedState::NotifyDataArrived(const char* aBuffer, uint32_t aLength,
   while (i + 1 < mRangeParsers.Length()) {
     if (mRangeParsers[i].mCurrentOffset >= mRangeParsers[i + 1].mStartOffset) {
       mRangeParsers[i + 1].mStartOffset = mRangeParsers[i].mStartOffset;
+      mRangeParsers[i + 1].mInitEndOffset = mRangeParsers[i].mInitEndOffset;
       mRangeParsers.RemoveElementAt(i);
     } else {
       i += 1;
@@ -347,4 +348,12 @@ void WebMBufferedState::NotifyDataArrived(const char* aBuffer, uint32_t aLength,
   }
 }
 
+int64_t WebMBufferedState::GetInitEndOffset()
+{
+  if (mRangeParsers.IsEmpty()) {
+    return -1;
+  }
+  return mRangeParsers[0].mInitEndOffset;
+}
+
 } // namespace mozilla

dom/media/webm/WebMBufferedParser.h

@@ -241,6 +241,9 @@ public:
   // dependencies to arrive at aTime.
   bool GetOffsetForTime(uint64_t aTime, int64_t* aOffset);
 
+  // Returns end offset of init segment or -1 if none found.
+  int64_t GetInitEndOffset();
+
 private:
   // Private destructor, to discourage deletion outside of Release():
   ~WebMBufferedState() {

dom/media/webm/WebMReader.cpp

@@ -337,7 +337,7 @@ nsresult WebMReader::ReadMetadata(MediaInfo* aInfo,
   io.tell = webm_tell;
   io.userdata = mDecoder;
   int64_t maxOffset = mDecoder->HasInitializationData() ?
-    mDecoder->GetResource()->GetLength() : -1;
+    mBufferedState->GetInitEndOffset() : -1;
   int r = nestegg_init(&mContext, io, &webm_log, maxOffset);
   if (r == -1) {
     return NS_ERROR_FAILURE;