> query file size, allocate buffer once, read it into the buffer, drop some NULL's into strategic positions, maybe shuffle some bytes around for that rare escape case, and you have a whole bunch of C strings, ready to use, and with no length limits.

I have also done this, but I would argue that, even at the time, the design was very poor. A much much better solution would have been wise pointers — pass around the length of the string separately from the pointer, much like string_view or Rust’s &str. Then you could skip the NULL-writing part.

Maybe C strings made sense on even older machines which had severely limited registers —- if you have an accumulator and one resister usable as a pointer, you want to minimize the number of variables involved in a computation.