ref: 7f7c098f85fba9612ea2aa3901b7f5fae3b209f5 dir: /sys/src/cmd/unix/drawterm/libc/runestrlen.c/
#include <u.h> #include <libc.h> long runestrlen(Rune *s) { return runestrchr(s, 0) - s; }