ref: d80cdf26e535edc0ceaa6ee8b0d5df8e1f98b5a7 dir: /sys/src/cmd/unix/drawterm/libc/runestrlen.c/
#include <u.h> #include <libc.h> long runestrlen(Rune *s) { return runestrchr(s, 0) - s; }