Take advantage of MojoGetBufferInformation

services/media/common/media_pipe_base.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/logging.h"
 #include "services/media/common/media_pipe_base.h"
 
 namespace mojo {
 namespace media {
 
@@ skipping 22 matching lines @@
 }
 
 void MediaPipeBase::Reset() {
   if (binding_.is_bound()) {
     binding_.Close();
   }
   buffer_ = nullptr;
 }
 
 void MediaPipeBase::SetBuffer(ScopedSharedBufferHandle handle,
-                              uint64_t size,
                               const SetBufferCallback& cbk) {
+  DCHECK(handle.is_valid());
+
   // Double init?  Close the connection.
   if (buffer_) {
-    LOG(ERROR) << "Attempting to set a new buffer (size = "
-               << size
-               << ") on a MediaConsumer which already has a buffer (size = "
+    LOG(ERROR) << "Attempting to set a new buffer on a MediaConsumer which "
+                  "already has a buffer assigned. (size = "
                << buffer_->size()
                << ")";
     Reset();
     return;
   }
 
+  // Query the buffer for its size.  If we fail to query the info, close the
+  // connection.
+  MojoResult res;
+  struct MojoBufferInformation info;

[viettrungluu, 2016/03/22 17:58:58]

Up to you, but in most of our C++ code, we omit the |struct|.

[johngro, 2016/03/22 18:16:40]

Done.

+  res = MojoGetBufferInformation(handle.get().value(), &info, sizeof(info));
+  if (res != MOJO_RESULT_OK) {
+    LOG(ERROR) << "Failed to query shared buffer info (res = " << res << ")";
+    Reset();
+  }

[viettrungluu, 2016/03/22 17:58:58]

|return;|?

[johngro, 2016/03/22 18:16:40]

good catch!

+
   // Invalid size?  Close the connection.
+  uint64_t size = info.num_bytes;
   if (!size || (size > MediaConsumer::kMaxBufferLen)) {
     LOG(ERROR) << "Invalid shared buffer size (size = " << size << ")";
     Reset();
     return;
   }
 
-
   // Failed to map the buffer?  Close the connection.
   buffer_ = MappedSharedBuffer::Create(handle.Pass(), size);
   if (!buffer_) {
     LOG(ERROR) << "Failed to map shared memory buffer (size = " << size << ")";
     Reset();
     return;
   }
 
   cbk.Run();
 }
@@ skipping 121 matching lines @@
   if (MOJO_RESULT_OK != res) {
     LOG(ERROR) << "Failed to map shared buffer of size " << size_
                << " (res " << res << ")";
     DCHECK(base_ == nullptr);
     handle_.reset();
   }
 }
 
 }  // namespace media
 }  // namespace mojo