Service name too long

[Tor Kringeland <tor.a.s.kringeland@ntnu.no>]

I recently encountered the error "Service name too long" when using the
package subed [1].  It seems to originate from `src/process.c'.  The
problem was that the value `subed-mpv-socket-dir' was too large.  It was
automatically set too

  /var/folders/6y/bnw7_h3j6w389gndfds7mzxm0000gn/T/subed-mpv-socket

However, changing it to a smaller value, for instance

  /tmp/subed-mpv-socket

solved the issue.

Is there a necessary reason why this error was thrown (/e.g./ the max
limit is dependent on the OS)?  The required length of string to cause
it is rather small.