C++ boost asio Windows file handle async_read_until infinite loop - no eof

Question

I\'m using boost 1.50 with VS2010, reading using a Windows file HANDLE (which seems to be relatively uncommon compared to asio use with sockets).

Probl

Answer 1

One option is to fseek() the file to the next position before the user's ReadHandler is called. Then async_read_some() can be implemented as async_read_at(ftell()).

The AsyncReader can use ReadUntilHandle instead of the stream_handle:

class ReadUntilHandle : public boost::asio::windows::random_access_handle
{
  public:
    ReadUntilHandle(boost::asio::io_service& ios, HANDLE handle)
      : boost::asio::windows::random_access_handle(ios, handle)
    {}

    template 
    void async_read_some(const MutableBufferSequence& buffers, Handler& handler)
    {
      LARGE_INTEGER offset;
      offset.QuadPart = 0;
      if (::SetFilePointerEx(native_handle(), offset, &offset, FILE_CURRENT)) {
        async_read_some_at(offset.QuadPart, buffers,
                           std::bind(&on_read_complete, handler,
                                     native_handle(), std::ref(get_io_service()),
                                     std::placeholders::_1, std::placeholders::_2));
      } else {
        boost::system::error_code error(::GetLastError(), boost::asio::error::get_system_category());
        get_io_service().post(boost::asio::detail::bind_handler(handler, error, 0));
      }
    }
  private:
    template  static void
    on_read_complete(Handler& handler, HANDLE native_handle, boost::asio::io_service& ios,
                   boost::system::error_code error, std::size_t length)
    {
      if (0 != length) { // update file position
        LARGE_INTEGER offset;
        offset.QuadPart = length;
        if (!::SetFilePointerEx(native_handle, offset, NULL, FILE_CURRENT) && !error) {
          error.assign(::GetLastError(),  boost::asio::error::get_system_category());
        }
      }
      ios.dispatch(boost::asio::detail::bind_handler(handler, error, length));
    }
};