Re: [Boost-users] [ASIO] Problem with reading of serial ports using ASIO

Subject: Re: [Boost-users] [ASIO] Problem with reading of serial ports using ASIO
From: Igor R (boost.lists_at_[hidden])
Date: 2010-10-19 14:48:38

> http://gist.github.com/634618
>
> We regularly call the function
> PCTimeoutUart::wait( iseSize_t len, uint32 timeoutInMS ) which wraps the
> calls to the boost asio libraries.
>
> This creates a deadline_timer, and binds it to our timeout callback
> (PCTimeoutUart::finishedTimer)
> It also calls async_read_some on the boost::asio::serial_port object  m_port
> to read the required length, and binds that to the
> PCTimeoutUart::finishedRead callback.
>
> We call the runone() function on m_io, which is declared in the header as a
> boost::asio::io_service and has been passed to both the timer and serial
> port's constructors.
>
> We continually call this in a loop until either m_timedOut has been set by
> the asynchronous call back to PCTimeoutUart::finishedTimer
> or m_finishedRead has been set via the call back to
> PCTimeoutUart::finishedRead
>
> Normally, this works well. However, there are certain scenarios when it
> fails to write anything to the buffer, despite the fact that finishedRead()
> is called with error = 0 and the correct length .

I don't know whether it's related or not (most likely not), but it
seems that the following code is dangerous, as you delete the buffer
without waiting for the async read completion. You assume that after
you call cancel(), the buffer won't be used anymore by the async
operation -- which is not obvious, imho.

if( m_timedOut )		
{			
  m_port.cancel();			
  delete[] buffer;			
  return false;		
}