Not for a cost-constrained network appliance. I think you're overestimating how hard this is. Maybe I'm underestimating it - I've been doing things in a "safe"

Not for a cost-constrained network appliance. I think you're overestimating how hard this is. Maybe I'm underestimating it - I've been doing things in a "safe" manner since the 1980s in 'C'. It's second nature to me. And I've never even been interested in UTF-8, much less implemented anything that uses it. I think the OP is a little too cute with "don't use sprintf()" - it and snprintf() can both be used completely safely. Now, it may well be that the UI can be completely done in, say, eLua and the guts of the thing done in 'C'. I'd go for that if it made any sense to any body else on the team. As a practice, I avoid working on things that will be on the larger Internet.