Fix a reentrance issue in DecryptingDemuxerStream.

media/filters/decrypting_demuxer_stream.cc

Index: media/filters/decrypting_demuxer_stream.cc
diff --git a/media/filters/decrypting_demuxer_stream.cc b/media/filters/decrypting_demuxer_stream.cc
index 39386e075ec68b2ab27095624a407b5dd0e6a72c..170fad850d991d111719e5793c7affb032eb1abe 100644
--- a/media/filters/decrypting_demuxer_stream.cc
+++ b/media/filters/decrypting_demuxer_stream.cc
@@ -43,17 +43,16 @@ DecryptingDemuxerStream::DecryptingDemuxerStream(
       key_added_while_decrypt_pending_(false) {
 }
 
-void DecryptingDemuxerStream::Initialize(
-    DemuxerStream* stream,
-    const PipelineStatusCB& status_cb) {
-  DVLOG(2) << "Initialize()";
+void DecryptingDemuxerStream::Initialize(DemuxerStream* stream,
+                                         const PipelineStatusCB& status_cb) {
+  DVLOG(2) << __FUNCTION__;
   DCHECK(message_loop_->BelongsToCurrentThread());
   DCHECK_EQ(state_, kUninitialized) << state_;
 
   DCHECK(!demuxer_stream_);
   weak_this_ = weak_factory_.GetWeakPtr();
   demuxer_stream_ = stream;
-  init_cb_ = status_cb;
+  init_cb_ = BindToCurrentLoop(status_cb);
 
   InitializeDecoderConfig();
 
@@ -63,20 +62,20 @@ void DecryptingDemuxerStream::Initialize(
 }
 
 void DecryptingDemuxerStream::Read(const ReadCB& read_cb) {
-  DVLOG(3) << "Read()";
+  DVLOG(3) << __FUNCTION__;
   DCHECK(message_loop_->BelongsToCurrentThread());
   DCHECK_EQ(state_, kIdle) << state_;
   DCHECK(!read_cb.is_null());
   CHECK(read_cb_.is_null()) << "Overlapping reads are not supported.";
 
-  read_cb_ = read_cb;
+  read_cb_ = BindToCurrentLoop(read_cb);
   state_ = kPendingDemuxerRead;
   demuxer_stream_->Read(
       base::Bind(&DecryptingDemuxerStream::DecryptBuffer, weak_this_));
 }
 
 void DecryptingDemuxerStream::Reset(const base::Closure& closure) {
-  DVLOG(2) << "Reset() - state: " << state_;
+  DVLOG(2) << __FUNCTION__ << " - state: " << state_;
   DCHECK(message_loop_->BelongsToCurrentThread());
   DCHECK(state_ != kUninitialized && state_ != kDecryptorRequested) << state_;
   DCHECK(init_cb_.is_null());  // No Reset() during pending initialization.
@@ -126,10 +125,16 @@ void DecryptingDemuxerStream::EnableBitstreamConverter() {
   demuxer_stream_->EnableBitstreamConverter();
 }
 
-DecryptingDemuxerStream::~DecryptingDemuxerStream() {}
+DecryptingDemuxerStream::~DecryptingDemuxerStream() {
+  DVLOG(2) << __FUNCTION__;
+  if (!set_decryptor_ready_cb_.is_null()) {
+    base::ResetAndReturn(&set_decryptor_ready_cb_).Run(DecryptorReadyCB());
+    set_decryptor_ready_cb_.Reset();

[whywhat, 2013/09/17 01:00:40]

Hm, so you reset the callback, then call it and reset it again before it's
destructed? isn't it too much?

[xhwang, 2013/09/17 01:13:00]

Good catch. Done.

+  }
+}
 
 void DecryptingDemuxerStream::SetDecryptor(Decryptor* decryptor) {
-  DVLOG(2) << "SetDecryptor()";
+  DVLOG(2) << __FUNCTION__;
   DCHECK(message_loop_->BelongsToCurrentThread());
   DCHECK_EQ(state_, kDecryptorRequested) << state_;
   DCHECK(!init_cb_.is_null());
@@ -138,8 +143,8 @@ void DecryptingDemuxerStream::SetDecryptor(Decryptor* decryptor) {
   set_decryptor_ready_cb_.Reset();
 
   if (!decryptor) {
-    base::ResetAndReturn(&init_cb_).Run(DECODER_ERROR_NOT_SUPPORTED);

[xhwang, 2013/09/17 00:53:49]

The caller could destroy |this| and create a new one here. If the new one's
address is the same as the old one, the state will be set to kUninitialized,
which triggers a DCHECK because we have a funny state.

[whywhat, 2013/09/17 01:00:40]

I'd at least leave a comment in the code saying that Run() should be the last
thing to happen before return (or post it to the message loop instead of relying
on fragile ordering).

[xhwang, 2013/09/17 01:13:00]

I am forcing the post. See line 55 in the new code. But still setting state
before posting callback is a better style.

On 2013/09/17 01:00:40, whywhat wrote:

     state_ = kUninitialized;
+    base::ResetAndReturn(&init_cb_).Run(DECODER_ERROR_NOT_SUPPORTED);
     return;
   }
 
@@ -156,7 +161,7 @@ void DecryptingDemuxerStream::SetDecryptor(Decryptor* decryptor) {
 void DecryptingDemuxerStream::DecryptBuffer(
     DemuxerStream::Status status,
     const scoped_refptr<DecoderBuffer>& buffer) {
-  DVLOG(3) << "DecryptBuffer()";
+  DVLOG(3) << __FUNCTION__;
   DCHECK(message_loop_->BelongsToCurrentThread());
   DCHECK_EQ(state_, kPendingDemuxerRead) << state_;
   DCHECK(!read_cb_.is_null());
@@ -212,7 +217,7 @@ void DecryptingDemuxerStream::DecryptPendingBuffer() {
 void DecryptingDemuxerStream::DeliverBuffer(
     Decryptor::Status status,
     const scoped_refptr<DecoderBuffer>& decrypted_buffer) {
-  DVLOG(3) << "DeliverBuffer() - status: " << status;
+  DVLOG(3) << __FUNCTION__ << " - status: " << status;
   DCHECK(message_loop_->BelongsToCurrentThread());
   DCHECK_EQ(state_, kPendingDecrypt) << state_;
   DCHECK_NE(status, Decryptor::kNeedMoreData);