Implement Pepper proxy for PPB_DirectoryReader

ppapi/proxy/directory_reader_resource.cc

+// Copyright (c) 2013 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 "ppapi/proxy/directory_reader_resource.h"
+
+#include "base/bind.h"
+#include "ipc/ipc_message.h"
+#include "ppapi/c/pp_errors.h"
+#include "ppapi/proxy/dispatch_reply_message.h"
+#include "ppapi/proxy/ppapi_messages.h"
+#include "ppapi/proxy/ppb_file_ref_proxy.h"
+#include "ppapi/shared_impl/ppapi_globals.h"
+#include "ppapi/shared_impl/resource_tracker.h"
+#include "ppapi/shared_impl/tracked_callback.h"
+#include "ppapi/thunk/enter.h"
+#include "ppapi/thunk/ppb_file_ref_api.h"
+
+using ppapi::proxy::PPB_FileRef_Proxy;
+
+namespace ppapi {
+namespace proxy {
+
+DirectoryReaderResource::DirectoryReaderResource(
+    Connection connection,
+    PP_Instance instance,
+    PP_Resource directory_ref)
+    : PluginResource(connection, instance),
+      directory_ref_(directory_ref),
+      output_(NULL),
+      has_more_(true) {
+  PpapiGlobals::Get()->GetResourceTracker()->AddRefResource(directory_ref_);
+}
+
+DirectoryReaderResource::~DirectoryReaderResource() {
+  ResourceTracker* tracker = PpapiGlobals::Get()->GetResourceTracker();
+  while (!entries_.empty()) {
+    tracker->ReleaseResource(entries_.front().file_ref);
+    entries_.pop();
+  }
+  tracker->ReleaseResource(directory_ref_);
+}
+
+thunk::PPB_DirectoryReader_API*
+DirectoryReaderResource::AsPPB_DirectoryReader_API() {
+  return this;
+}
+
+int32_t DirectoryReaderResource::GetNextEntry(
+    PP_DirectoryEntry_Dev* entry,
+    scoped_refptr<TrackedCallback> callback) {
+  if (TrackedCallback::IsPending(callback_))
+    return PP_ERROR_INPROGRESS;
+
+  output_ = entry;
+  callback_ = callback;
+
+  if (FillUpEntry())
+    return PP_OK;
+
+  if (!sent_create_to_renderer())
+    SendCreate(RENDERER, PpapiHostMsg_DirectoryReader_Create());
+
+  ppapi::ResourceTracker* tracker = PpapiGlobals::Get()->GetResourceTracker();
+  PpapiHostMsg_DirectoryReader_GetNextEntry msg(
+      tracker->GetResource(directory_ref_)->host_resource());
+  Call<PpapiPluginMsg_DirectoryReader_GetNextEntryReply>(
+      RENDERER, msg,
+      base::Bind(&DirectoryReaderResource::OnPluginMsgGetNextEntryReply, this));
+  return PP_OK_COMPLETIONPENDING;
+}
+
+void DirectoryReaderResource::OnPluginMsgGetNextEntryReply(
+    const ResourceMessageReplyParams& params,
+    const std::vector<ppapi::PPB_FileRef_CreateInfo>& infos,
+    const std::vector<PP_FileType>& file_types) {
+  CHECK_EQ(infos.size(), file_types.size());
+  if (!TrackedCallback::IsPending(callback_))

[yzshen1, 2013/01/28 17:52:34]

This is a little bit tricky: when we send a host resource to the plugin side,
usually one ref is carried to the plugin side (otherwise, the resource may be
destroyed in the middle). And the plugin side will create a plugin-side resource
object to take that host-side ref. When the plugin-side resource object goes
away, that host-side ref is released by sending a message back to the host side.

In this case, if we return early, the host-side resource ref is leaked.

[nhiroki, 2013/01/29 05:10:34]

I see, thanks for your understandable explanations! I moved this check after
pushing entries to release them correctly in the dtor.

+    return;
+
+  for (std::vector<ppapi::PPB_FileRef_CreateInfo>::size_type i = 0;
+       i < infos.size(); ++i) {
+    PP_DirectoryEntry_Dev entry;
+    entry.file_ref = PPB_FileRef_Proxy::DeserializeFileRef(infos[i]);
+    entry.file_type = file_types[i];
+    entries_.push(entry);
+  }
+
+  // Current implementation returns all entries at once.
+  // TODO(nhiroki): DirectoryReader should return directory entries in multiple
+  // chunks.
+  has_more_ = false;
+
+  FillUpEntry();
+  output_ = NULL;

[yzshen1, 2013/01/28 17:52:34]

It is better to reset |output_| within FillUpEntry() if necessary, so that you
don't need to do it here and line 59.

[nhiroki, 2013/01/29 05:10:34]

Done.

+
+  callback_->Run(params.result());
+}
+
+bool DirectoryReaderResource::FillUpEntry() {
+  DCHECK(output_);
+  if (!entries_.empty()) {
+    *output_ = entries_.front();
+    entries_.pop();
+    return true;
+  }
+
+  if (!has_more_) {
+    output_->file_ref = 0;
+    output_->file_type = PP_FILETYPE_OTHER;
+    return true;
+  }
+
+  return false;
+}
+
+}  // namespace proxy
+}  // namespace ppapi