Check buffer index in shared memory for input audio.

media/audio/audio_parameters.h

 // Copyright (c) 2012 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.
 
 #ifndef MEDIA_AUDIO_AUDIO_PARAMETERS_H_
 #define MEDIA_AUDIO_AUDIO_PARAMETERS_H_
 
+#include <stdint.h>
 #include <string>
 
 #include "base/basictypes.h"
+#include "base/compiler_specific.h"
 #include "base/time/time.h"
+#include "media/base/audio_bus.h"
 #include "media/base/channel_layout.h"
 #include "media/base/media_export.h"
 
 namespace media {
 
-struct MEDIA_EXPORT AudioInputBufferParameters {
+struct ALIGNAS(AudioBus::kChannelAlignment) MEDIA_EXPORT
+    AudioInputBufferParameters {
   double volume;
   uint32 size;
+  uint32_t hardware_delay_bytes;
+  uint32_t id;
   bool key_pressed;
 };
 
+COMPILE_ASSERT(
+    sizeof(AudioInputBufferParameters) % AudioBus::kChannelAlignment == 0,
+           AudioInputBufferParameters_not_aligned);

[tommi (sloooow) - chröme, 2015/08/18 12:44:37]

I think we should apply the alignas attribute on the variable that actually
needs it, which is the 'audio' member variable of AudioInputBuffer.  Then we can
have a compile assert (and I think we use static_assert now), that the offset of
the audio member within AudioInputBuffer, is == kChannelAlignment.

The compiler should inject whatever padding is required before the member
variable, to get that alignment done right.

[Henrik Grunell, 2015/08/19 14:28:38]

Did that and hit dcheck in AudioBus::WrapMemory. As discussing and debugging
offline the problem is we rely on calculating required size by using
sizeof(AudioInputBufferParameters) + size for AudioBus data. This is done in
several places. So sticking with this seems like the best way.

+
 // Use a struct-in-struct approach to ensure that we can calculate the required
 // size as sizeof(AudioInputBufferParameters) + #(bytes in audio buffer) without
 // using packing.
 struct MEDIA_EXPORT AudioInputBuffer {
   AudioInputBufferParameters params;
   int8 audio[1];
 };
 
 class MEDIA_EXPORT AudioParameters {
  public:
@@ skipping 93 matching lines @@
   if (a.sample_rate() != b.sample_rate())
     return a.sample_rate() < b.sample_rate();
   if (a.bits_per_sample() != b.bits_per_sample())
     return a.bits_per_sample() < b.bits_per_sample();
   return a.frames_per_buffer() < b.frames_per_buffer();
 }
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_AUDIO_PARAMETERS_H_