From 119321d8c21e16b2855268a66af347b8545417f1 Mon Sep 17 00:00:00 2001
From: Jean-Yves Avenard <jyavenard@mozilla.com>
Date: Thu, 6 Nov 2014 19:08:04 +1100
Subject: [PATCH] Bug 1092996 - MSE/WebM: limit size read to what is available.
 r=kinetik

---
 dom/media/AbstractMediaDecoder.h              | 4 ++++
 dom/media/mediasource/SourceBufferDecoder.cpp | 6 ++++++
 dom/media/mediasource/SourceBufferDecoder.h   | 1 +
 dom/media/webm/WebMReader.cpp                 | 3 ++-
 4 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/dom/media/AbstractMediaDecoder.h b/dom/media/AbstractMediaDecoder.h
index 01e198974785..8b158ffe7ab5 100644
--- a/dom/media/AbstractMediaDecoder.h
+++ b/dom/media/AbstractMediaDecoder.h
@@ -127,6 +127,10 @@ public:
   // Called from HTMLMediaElement when owner document activity changes
   virtual void SetElementVisibility(bool aIsVisible) {}
 
+  // Called by some MediaDecoderReader to determine if we can rely
+  // on the resource length to limit reads.
+  virtual bool HasInitializationData() { return false; }
+
   // Stack based class to assist in notifying the frame statistics of
   // parsed and decoded frames. Use inside video demux & decode functions
   // to ensure all parsed and decoded frames are reported on all return paths.
diff --git a/dom/media/mediasource/SourceBufferDecoder.cpp b/dom/media/mediasource/SourceBufferDecoder.cpp
index 24cb642c856a..c284736c766c 100644
--- a/dom/media/mediasource/SourceBufferDecoder.cpp
+++ b/dom/media/mediasource/SourceBufferDecoder.cpp
@@ -119,6 +119,12 @@ SourceBufferDecoder::UpdatePlaybackPosition(int64_t aTime)
   MSE_DEBUG("SourceBufferDecoder(%p)::UpdatePlaybackPosition UNIMPLEMENTED", this);
 }
 
+bool
+SourceBufferDecoder::HasInitializationData()
+{
+  return true;
+}
+
 void
 SourceBufferDecoder::OnReadMetadataCompleted()
 {
diff --git a/dom/media/mediasource/SourceBufferDecoder.h b/dom/media/mediasource/SourceBufferDecoder.h
index fb272162be9a..e186c9c9df92 100644
--- a/dom/media/mediasource/SourceBufferDecoder.h
+++ b/dom/media/mediasource/SourceBufferDecoder.h
@@ -60,6 +60,7 @@ public:
   virtual void SetMediaSeekable(bool aMediaSeekable) MOZ_FINAL MOZ_OVERRIDE;
   virtual void UpdateEstimatedMediaDuration(int64_t aDuration) MOZ_FINAL MOZ_OVERRIDE;
   virtual void UpdatePlaybackPosition(int64_t aTime) MOZ_FINAL MOZ_OVERRIDE;
+  virtual bool HasInitializationData() MOZ_FINAL MOZ_OVERRIDE;
 
   // SourceBufferResource specific interface below.
 
diff --git a/dom/media/webm/WebMReader.cpp b/dom/media/webm/WebMReader.cpp
index 91b4c3bd6f40..546f9614058a 100644
--- a/dom/media/webm/WebMReader.cpp
+++ b/dom/media/webm/WebMReader.cpp
@@ -287,7 +287,8 @@ nsresult WebMReader::ReadMetadata(MediaInfo* aInfo,
   io.seek = webm_seek;
   io.tell = webm_tell;
   io.userdata = mDecoder;
-  int64_t maxOffset = -1;
+  int64_t maxOffset = mDecoder->HasInitializationData() ?
+    mDecoder->GetResource()->GetLength() : -1;
   int r = nestegg_init(&mContext, io, &webm_log, maxOffset);
   if (r == -1) {
     return NS_ERROR_FAILURE;