id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
8722	The boost::asio::windows::stream_handle::read_some method may (incorrectly) throw when used with named-pipes in message mode (on Windows) and receives an ERROR_MORE_DATA error	Dentcho Bankov <dbankov@…>	chris_kohlhoff	"Please note that this ticket is similar to Ticket#2936.

When using named-pipes in message mode on Windows it is possible that the read operation on the client side will fail with GetLastError() == ERROR_MORE_DATA. In the overlapped IO case the latter means that  GetOverlappedResult(...) fails and reports this error.

Now looking at the win_iocp_handle_service::do_read(...) when in the above scenario if the GetOverlappedResult(...) fails do_read(...) would update the ec parameter with the error value (in this case ERROR_MORE_DATA) and then boost::asio::windows::stream_handle::read_some(...) would throw. The latter may be incorrect as the ReadFile(...) function may have actually read some data but the information about this data (bytes read) would be lost when the exception is thrown leaving the upper layers practically unable to recover from this situation even if they'd catch the exception... (see attached code)

It seems the fix for this should be to avoid throwing the exception by adding an ""if"" statement similar to the one after the ReadFile(...) call (several lines above in do_read(...)) e.g. making the code around GetOverlappedResult(...) look as follows:

  // Wait for the operation to complete.
  DWORD bytes_transferred = 0;
  ok = ::GetOverlappedResult(impl.handle_,
      &overlapped, &bytes_transferred, TRUE);
  if (!ok)
  {
    DWORD last_error = ::GetLastError();
    if (last_error != ERROR_MORE_DATA) // <---- added ""if"" statement
    {
      if (last_error == ERROR_HANDLE_EOF)
      {
        ec = boost::asio::error::eof;
      }
      else
      {
        ec = boost::system::error_code(last_error,
             boost::asio::error::get_system_category());
      }
      return 0;
    }
  }

Please comment if the proposed fix is correct as I'd like to apply it before it is released in an official BOOST release."	Bugs	closed	To Be Determined	asio	Boost Development Trunk	Problem	fixed		chris_kohlhoff