ref: a5488ad1e64e34f8a2f2e604ca5bcd2a0b750f67 dir: /sys/src/cmd/unix/drawterm/libc/runestrlen.c/
#include <u.h> #include <libc.h> long runestrlen(Rune *s) { return runestrchr(s, 0) - s; }