[PPAPI] Implement an IOStreamResource for data transmission between plugin and renderer.

content/renderer/pepper/pepper_io_stream_host.cc

+// Copyright (c) 2014 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 "content/renderer/pepper/pepper_io_stream_host.h"
+
+#include "content/public/renderer/render_thread.h"
+#include "content/public/renderer/renderer_ppapi_host.h"
+#include "ppapi/c/pp_errors.h"
+#include "ppapi/host/dispatch_host_message.h"
+#include "ppapi/host/ppapi_host.h"
+#include "ppapi/proxy/host_dispatcher.h"
+#include "ppapi/proxy/ppapi_messages.h"
+
+
+using ppapi::host::HostMessageContext;
+using ppapi::host::ReplyMessageContext;
+using ppapi::proxy::HostDispatcher;
+using ppapi::proxy::SerializedHandle;
+
+namespace content {
+
+namespace {
+
+base::PlatformFile ToPlatformFile(const base::SharedMemoryHandle& handle) {
+#if defined(OS_WIN)
+  return reinterpret_cast<HANDLE>(static_cast<intptr_t>(handle));
+#elif defined(OS_POSIX)
+  return handle.fd;
+#else
+#error Not implemented.
+#endif
+}
+
+}  // namespace
+
+PepperIOStreamHost::PepperIOStreamHost(
+    RendererPpapiHost* host,
+    PP_Instance instance,
+    PP_Resource resource,
+    bool is_input)
+    : ResourceHost(host->GetPpapiHost(), instance, resource),
+      ppapi::IOStreamShared(is_input) {
+}
+
+PepperIOStreamHost::~PepperIOStreamHost() {
+}
+
+void PepperIOStreamHost::MovePeerLimit(uint32_t offset) {
+  CHECK(offset);

[bbudge, 2014/01/02 22:16:22]

DCHECK?

[Peng, 2014/01/03 16:15:11]

Done.

+  host()->SendUnsolicitedReply(pp_resource(),
+                               PpapiPluginMsg_IOStream_MoveLimit(offset));
+}
+
+bool PepperIOStreamHost::InitSharedBufferAndNotifyPlugin(uint32_t size) {
+  if (!InitSharedBuffer(size))
+    return false;
+
+  base::SharedMemoryHandle shm_handle = shared_memory()->handle();
+  base::PlatformFile platform_file = ToPlatformFile(shm_handle);
+  HostDispatcher* dispatcher = HostDispatcher::GetForInstance(pp_instance());
+  SerializedHandle handle(
+      dispatcher->ShareHandleWithRemote(platform_file, false),
+      size);
+  host()->SendUnsolicitedReplyWithHandle(pp_resource(),
+      PpapiPluginMsg_IOStream_Init(size), handle);
+  return true;
+}
+
+bool PepperIOStreamHost::InitSharedBuffer(uint32_t size) {
+  DCHECK(size);
+  content::RenderThread* render_thread = content::RenderThread::Get();
+  scoped_ptr<base::SharedMemory> shm;
+  shm = render_thread->HostAllocateSharedMemoryBuffer(size).Pass();

[bbudge, 2014/01/02 22:16:22]

Why not assign directly (on line above) to avoid default ctor running? i.e.

scoped_ptr<base::SharedMemory> shm = ...

[Peng, 2014/01/03 16:15:11]

Done

+  if (!shm)
+    return false;
+
+  SetBuffer(shm.Pass(), size);
+  return true;
+}
+
+int32_t PepperIOStreamHost::OnResourceMessageReceived(
+    const IPC::Message& msg,
+    HostMessageContext* context) {
+  IPC_BEGIN_MESSAGE_MAP(PepperIOStreamHost, msg)
+    PPAPI_DISPATCH_HOST_RESOURCE_CALL(PpapiHostMsg_IOStream_Init,
+                                      OnHostMsgInit)
+    PPAPI_DISPATCH_HOST_RESOURCE_CALL(PpapiHostMsg_IOStream_MoveLimit,
+                                      OnHostMsgMoveLimit)
+  IPC_END_MESSAGE_MAP()
+  return PP_ERROR_FAILED;
+}
+
+int32_t PepperIOStreamHost::OnHostMsgInit(HostMessageContext* context,
+                                          uint32_t size) {
+  if (!InitSharedBuffer(size))
+    return PP_ERROR_NOMEMORY;
+
+  base::SharedMemoryHandle shm_handle = shared_memory()->handle();
+  base::PlatformFile platform_file = ToPlatformFile(shm_handle);
+  // We need send the SerializedHandle back, so we have to send reply by
+  // ourselves.

[bbudge, 2014/01/02 22:16:22]

This comment won't be needed if you have a reply message (see below).

[Peng, 2014/01/03 16:15:11]

Done.

+  ReplyMessageContext reply_context = context->MakeReplyMessageContext();
+  HostDispatcher* dispatcher = HostDispatcher::GetForInstance(pp_instance());
+  SerializedHandle handle(
+      dispatcher->ShareHandleWithRemote(platform_file, false),
+      size);
+  reply_context.params.AppendHandle(handle);
+  reply_context.params.set_result(PP_OK);
+  SendReply(reply_context, IPC::Message());

[bbudge, 2014/01/02 22:16:22]

If a message requires a reply to get back some result or handle, we usually
define a reply message. In this case you define:

IPC_MESSAGE_CONTROL1(PpapiHostMsg_IOStream_Init,
                                         uint32_t /* size */)

So, you would define this reply:

IPC_MESSAGE_CONTROL0(PpapiPluginMsg_IOStream_InitReply)

[Peng, 2014/01/03 16:15:11]

Done.

+
+  return PP_OK_COMPLETIONPENDING;
+}
+
+int32_t PepperIOStreamHost::OnHostMsgMoveLimit(HostMessageContext* context,
+                                               uint32_t offset) {
+  DCHECK(offset);
+  MoveLimit(offset);
+  return PP_OK;
+}
+
+}  // namespace content