Adding the message reading class used for remote_security_key STDIN communication.

remoting/host/security_key/remote_security_key_message_reader.cc

+// Copyright 2016 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 "remoting/host/security_key/remote_security_key_message_reader.h"
+
+#include <stdint.h>
+
+#include <string>
+#include <utility>
+
+#include "base/bind.h"
+#include "base/files/file.h"
+#include "base/macros.h"
+#include "base/single_thread_task_runner.h"
+#include "base/stl_util.h"

[Sergey Ulanov, 2016/03/30 21:34:28]

Don't need this

[joedow, 2016/03/31 01:45:12]

The 'string_as_array' function I use below is defined there.

+#include "base/thread_task_runner_handle.h"
+#include "base/threading/thread_checker.h"

[Sergey Ulanov, 2016/03/30 21:34:28]

Don't need this include.

[joedow, 2016/03/31 01:45:12]

Done.

+#include "remoting/host/security_key/security_key_message.h"
+
+namespace remoting {
+
+RemoteSecurityKeyMessageReader::RemoteSecurityKeyMessageReader(
+    base::File input_file)
+    : read_stream_(std::move(input_file)),
+      reader_thread_("RemoteSecurityKeyMessageReader"),
+      weak_factory_(this) {
+  base::Thread::Options options;
+  options.message_loop_type = base::MessageLoop::TYPE_IO;
+  reader_thread_.StartWithOptions(options);
+
+  read_task_runner_ = reader_thread_.task_runner();
+  main_task_runner_ = base::ThreadTaskRunnerHandle::Get();
+  reader_ = weak_factory_.GetWeakPtr();

[Sergey Ulanov, 2016/03/30 21:34:28]

I don't think you really need reader_. Just use weak_factory_.GetWeakPtr() when
posting tasks from read_thread_ to main_task_runner_.

[joedow, 2016/03/31 01:45:12]

Done.

+}
+
+RemoteSecurityKeyMessageReader::~RemoteSecurityKeyMessageReader() {
+  DCHECK(main_task_runner_->RunsTasksOnCurrentThread());
+
+  // In order to ensure the reader thread is stopped cleanly, we close the
+  // stream it is blocking on and then wait for the thread to exit.
+  read_stream_.Close();
+  reader_thread_.Stop();

[Sergey Ulanov, 2016/03/30 21:34:28]

nit: Thread destructor calls stop, so you don't need to call it explicitly here,
but feel free to keep it here if you think it makes the code clearer.

[joedow, 2016/03/31 01:45:12]

Acknowledged.

+}
+
+void RemoteSecurityKeyMessageReader::Start(
+    SecurityKeyMessageCallback message_callback,
+    base::Closure error_callback) {
+  DCHECK(main_task_runner_->RunsTasksOnCurrentThread());
+
+  message_callback_ = message_callback;
+  error_callback_ = error_callback;
+
+  // base::Unretained is safe since this class owns the thread running this task
+  // which will be destroyed before this instance is.
+  read_task_runner_->PostTask(
+      FROM_HERE, base::Bind(&RemoteSecurityKeyMessageReader::ReadMessage,
+                            base::Unretained(this)));
+}
+
+void RemoteSecurityKeyMessageReader::ReadMessage() {
+  DCHECK(read_task_runner_->RunsTasksOnCurrentThread());
+
+  while (true) {
+    if (!read_stream_.IsValid()) {
+      LOG(ERROR) << "Cannot read from invalid stream.";
+      NotifyError();
+      return;
+    }
+
+    // Read the message header to retrieve the remaining message length.
+    uint32_t total_message_size_bytes;
+    int read_result = read_stream_.ReadAtCurrentPos(
+        reinterpret_cast<char*>(&total_message_size_bytes),
+        SecurityKeyMessage::kHeaderSizeBytes);
+    if (read_result != SecurityKeyMessage::kHeaderSizeBytes) {
+      // 0 means EOF which is normal and should not be logged as an error.
+      if (read_result != 0) {
+        LOG(ERROR) << "Failed to read message header, read returned "
+                   << read_result;
+      }
+      NotifyError();
+      return;
+    }
+
+    if (!SecurityKeyMessage::IsValidMessageSize(total_message_size_bytes)) {
+      LOG(ERROR) << "Message size too large: " << total_message_size_bytes;
+      NotifyError();
+      return;
+    }
+
+    std::string message_data(total_message_size_bytes, '\0');
+    read_result = read_stream_.ReadAtCurrentPos(string_as_array(&message_data),
+                                                total_message_size_bytes);
+    // The static cast is safe as we know the value is smaller than max int.
+    if (read_result != static_cast<int>(total_message_size_bytes)) {
+      LOG(ERROR) << "Failed to read message: " << read_result;
+      NotifyError();
+      return;
+    }
+
+    scoped_ptr<SecurityKeyMessage> message(new SecurityKeyMessage());
+    if (!message->ParseMessage(message_data)) {
+      LOG(ERROR) << "Invalid message data received.";
+      NotifyError();
+      return;
+    }
+
+    // Notify callback of the new message received.
+    main_task_runner_->PostTask(
+        FROM_HERE,
+        base::Bind(&RemoteSecurityKeyMessageReader::InvokeMessageCallback,
+                   reader_, base::Passed(&message)));
+  }
+}
+
+void RemoteSecurityKeyMessageReader::NotifyError() {
+  DCHECK(read_task_runner_->RunsTasksOnCurrentThread());
+
+  main_task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&RemoteSecurityKeyMessageReader::InvokeErrorCallback,
+                 reader_));
+}
+
+void RemoteSecurityKeyMessageReader::InvokeMessageCallback(
+    scoped_ptr<SecurityKeyMessage> message) {
+  DCHECK(main_task_runner_->RunsTasksOnCurrentThread());
+  message_callback_.Run(std::move(message));
+}
+
+void RemoteSecurityKeyMessageReader::InvokeErrorCallback() {
+  DCHECK(main_task_runner_->RunsTasksOnCurrentThread());
+  error_callback_.Run();
+}
+
+}  // namespace remoting