Comment by jacquesm

> The str_buf treats capacity as 1 less than it really is such that it can ensure there's always a stupid 0 at the end for compatibility with APIs that expect 0 terminated strings.

Off-by-one errors are a thing.

> Just make your own string functions from scratch when using C, you'll thank me later.

No, if you're going to use C and you need a string type use a well supported string library so that you don't end up reinventing the wheel (probably in a buggy way) and benefit from the battle testing that that code has gone through.

If we're looking at actual strings (as in text) then I'd use 'libunistring'.