Since the process name is truncated by the kernel, we need to look at the cmdline to work out the full process name.
However sometimes the cmdline contains nothing helpful (For some reason, for example, xorg's command line is just ":0").

So strip off any path on the cmdline, and check if the cmdline begins with the string of the process name.
If it does, assume that the cmdline contains the full processname, and use the stripped cmdline as the process name.

This does mean that the process name now contains the arguments.