PPAPI/NaCl: Make NaClIPCAdapter transfer handles more generally

ppapi/proxy/ppb_audio_proxy.cc

Index: ppapi/proxy/ppb_audio_proxy.cc
diff --git a/ppapi/proxy/ppb_audio_proxy.cc b/ppapi/proxy/ppb_audio_proxy.cc
index f60ac812127e96804d053ddf7ac1e5d76cc8014b..bc83be368a19e3b9f54dc272dab8d27c9a05ccd2 100644
--- a/ppapi/proxy/ppb_audio_proxy.cc
+++ b/ppapi/proxy/ppb_audio_proxy.cc
@@ -6,6 +6,7 @@
 
 #include "base/compiler_specific.h"
 #include "base/threading/simple_thread.h"
+#include "media/audio/shared_memory_util.h"
 #include "ppapi/c/pp_errors.h"
 #include "ppapi/c/ppb_audio.h"
 #include "ppapi/c/ppb_audio_config.h"
@@ -238,13 +239,13 @@ void PPB_Audio_Proxy::AudioChannelConnected(
   IPC::PlatformFileForTransit socket_handle =
       IPC::InvalidPlatformFileForTransit();
   base::SharedMemoryHandle shared_memory = IPC::InvalidPlatformFileForTransit();
-  uint32_t shared_memory_length = 0;
+  uint32_t audio_buffer_length = 0;
 
   int32_t result_code = result;
   if (result_code == PP_OK) {
     result_code = GetAudioConnectedHandles(resource, &socket_handle,
                                            &shared_memory,
-                                           &shared_memory_length);
+                                           &audio_buffer_length);
   }
 
   // Send all the values, even on error. This simplifies some of our cleanup
@@ -252,9 +253,18 @@ void PPB_Audio_Proxy::AudioChannelConnected(
   // inconvenient to clean up. Our IPC code will automatically handle this for
   // us, as long as the remote side always closes the handles it receives
   // (in OnMsgNotifyAudioStreamCreated), even in the failure case.
+  ppapi::proxy::SerializedHandle fd_wrapper(socket_handle);
+
+  // Note that we must call TotalSharedMemorySizeInBytes because
+  // Audio allocates extra space in shared memory for book-keeping, so the
+  // actual size of the shared memory buffer is larger than audio_buffer_length.
+  // When sending to NaCl, NaClIPCAdapter expects this size to match the size
+  // of the full shared memory buffer.
+  ppapi::proxy::SerializedHandle handle_wrapper(
+      shared_memory,
+      media::TotalSharedMemorySizeInBytes(audio_buffer_length));
   dispatcher()->Send(new PpapiMsg_PPBAudio_NotifyAudioStreamCreated(
-      API_ID_PPB_AUDIO, resource, result_code, socket_handle,
-      shared_memory, shared_memory_length));
+      API_ID_PPB_AUDIO, resource, result_code, fd_wrapper, handle_wrapper));
 }
 
 int32_t PPB_Audio_Proxy::GetAudioConnectedHandles(
@@ -299,21 +309,27 @@ int32_t PPB_Audio_Proxy::GetAudioConnectedHandles(
 void PPB_Audio_Proxy::OnMsgNotifyAudioStreamCreated(
     const HostResource& audio_id,
     int32_t result_code,
-    IPC::PlatformFileForTransit socket_handle,
-    base::SharedMemoryHandle handle,
-    uint32_t length) {
+    ppapi::proxy::SerializedHandle socket_handle,
+    ppapi::proxy::SerializedHandle handle) {
+  CHECK(socket_handle.is_socket());
+  CHECK(handle.is_shmem());
   EnterPluginFromHostResource<PPB_Audio_API> enter(audio_id);
   if (enter.failed() || result_code != PP_OK) {
     // The caller may still have given us these handles in the failure case.
     // The easiest way to clean these up is to just put them in the objects
     // and then close them. This failure case is not performance critical.
     base::SyncSocket temp_socket(
-        IPC::PlatformFileForTransitToPlatformFile(socket_handle));
-    base::SharedMemory temp_mem(handle, false);
+        IPC::PlatformFileForTransitToPlatformFile(socket_handle.descriptor()));
+    base::SharedMemory temp_mem(handle.shmem(), false);
   } else {
+    // See the comment above about how we must call
+    // TotalSharedMemorySizeInBytes to get the actual size of the buffer. Here,
+    // we must call PacketSizeInBytes to get back the size of the audio buffer,
+    // excluding the bytes that audio uses for book-keeping.
     static_cast<Audio*>(enter.object())->SetStreamInfo(
-        enter.resource()->pp_instance(), handle, length,
-        IPC::PlatformFileForTransitToPlatformFile(socket_handle));
+        enter.resource()->pp_instance(), handle.shmem(),
+        media::PacketSizeInBytes(handle.size()),
+        IPC::PlatformFileForTransitToPlatformFile(socket_handle.descriptor()));
   }
 }