Add code to detect new added ReceiveError on Linux

device/serial/serial_io_handler_posix.h

 // Copyright 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.
 
 #ifndef DEVICE_SERIAL_SERIAL_IO_HANDLER_POSIX_H_
 #define DEVICE_SERIAL_SERIAL_IO_HANDLER_POSIX_H_
 
 #include "base/message_loop/message_loop.h"
 #include "base/single_thread_task_runner.h"
 #include "base/thread_task_runner_handle.h"
 #include "device/serial/serial_io_handler.h"
 
 namespace device {
 
+// Linux reports breaks and parity errors by inserting the sequence '\377\0x'
+// into the byte stream where 'x' is '\0' for a break and the corrupted byte for
+// a parity error.
+enum class ErrorDetectState { NO_ERROR, MARK_377_SEEN, MARK_0_SEEN };
+
 class SerialIoHandlerPosix : public SerialIoHandler,
                              public base::MessageLoopForIO::Watcher {
  protected:
   // SerialIoHandler impl.
   void ReadImpl() override;
   void WriteImpl() override;
   void CancelReadImpl() override;
   void CancelWriteImpl() override;
   bool ConfigurePortImpl() override;
   bool Flush() const override;
   serial::DeviceControlSignalsPtr GetControlSignals() const override;
   bool SetControlSignals(
       const serial::HostControlSignals& control_signals) override;
   serial::ConnectionInfoPtr GetPortInfo() const override;
   bool SetBreak() override;
   bool ClearBreak() override;
+  int CheckReceiveError(char* buffer,
+                        int buffer_len,
+                        int bytes_read,
+                        bool& break_detected,
+                        bool& parity_error_detected);
 
  private:
   friend class SerialIoHandler;
+  friend class SerialIoHandlerPosixTest;
 
   SerialIoHandlerPosix(
       scoped_refptr<base::SingleThreadTaskRunner> file_thread_task_runner,
       scoped_refptr<base::SingleThreadTaskRunner> ui_thread_task_runner);
   ~SerialIoHandlerPosix() override;
 
   // base::MessageLoopForIO::Watcher implementation.
   void OnFileCanWriteWithoutBlocking(int fd) override;
   void OnFileCanReadWithoutBlocking(int fd) override;
 
   void EnsureWatchingReads();
   void EnsureWatchingWrites();
 
   base::MessageLoopForIO::FileDescriptorWatcher file_read_watcher_;
   base::MessageLoopForIO::FileDescriptorWatcher file_write_watcher_;
 
   // Flags indicating if the message loop is watching the device for IO events.
   bool is_watching_reads_;
   bool is_watching_writes_;
 
+  ErrorDetectState error_detect_state_;
+  bool parity_check_enabled_;
+  char chars_stashed_[2];
+  int num_chars_stashed_;
+
   DISALLOW_COPY_AND_ASSIGN(SerialIoHandlerPosix);
 };
 
 }  // namespace device
 
 #endif  // DEVICE_SERIAL_SERIAL_IO_HANDLER_POSIX_H_