inotify asio

#include <iostream>
#include <boost/asio.hpp>
#include <boost/bind.hpp>
#include <sys/inotify.h>

namespace asio = boost::asio;

struct test_inotify_asio
{
    asio::io_service io_svc;
    asio::posix::stream_descriptor stream_desc;
    std::string file_path;
    int raw_fd;
    int watch_fd;
    asio::streambuf buf;

    test_inotify_asio(const std::string & file_path_)
    : stream_desc(io_svc),
      file_path(file_path_),
      buf(1024)
    {
        if(0 < (raw_fd = inotify_init()))
        {
            if(0 > (watch_fd = inotify_add_watch
                       (raw_fd,
                        file_path.c_str(),
                        IN_MODIFY | IN_ACCESS | IN_CREATE | IN_DELETE | IN_OPEN)))
            {
                throw std::runtime_error("Unable to add watch on: " +
                             file_path);
            }
        }
        else
        {
            throw std::runtime_error("Unable to initialize inotify");
        }

        stream_desc.assign(raw_fd);

        start_notify_handler();
    };

    void start_notify_handler()
    {
      stream_desc
      .async_read_some(buf.prepare(buf.max_size()),
                       boost::bind
                              (&test_inotify_asio::notify_handler,
                               this,
                               asio::placeholders::error,
                               asio::placeholders::bytes_transferred));
    }

    void notify_handler(const boost::system::error_code&,
                        std::size_t transferred)
    {
      size_t processed = 0;

      while(transferred - processed >= sizeof(inotify_event))
      {
          const char* cdata = processed + asio::buffer_cast<const char*>(buf.data());

          const inotify_event* ievent = reinterpret_cast<const inotify_event*>(cdata);

          processed += sizeof(inotify_event) + ievent->len;

          if(ievent->len > 0 && ievent->mask & IN_MODIFY)
          {
              std::cout << "File modified: "
                    << file_path
                    << "[" << ievent->name << "]\n";
          }
          else if(ievent->len > 0 && ievent->mask & IN_ACCESS)
          {
              std::cout << "File accessed: "
                    << file_path
                    << "[" << ievent->name << "]\n";
          }
          else if(ievent->len > 0 && ievent->mask & IN_OPEN)
          {
                  std::cout << "File opened: "
                    << file_path
                    << "[" << ievent->name << "]\n";
          }
          else if(ievent->len > 0 && ievent->mask & IN_CREATE)
          {
              std::cout << "File created: "
                    << file_path
                    << "[" << ievent->name << "]\n";
          }
          else if(ievent->len > 0 && ievent->mask & IN_DELETE)
          {
                  std::cout << "File deleted: "
                        << file_path
                        << "[" << ievent->name << "]\n";
          }
      }

      start_notify_handler();
    }

    void operator()()
    {
        io_svc.run();
    }

    ~test_inotify_asio()
    {
        inotify_rm_watch(raw_fd, watch_fd);

        close(raw_fd);
    }
};

int main()
{
    test_inotify_asio tia("/abs/path/to/file");

    tia();
}