ref: 8f4053d1efa1ee75a7bea09e624f1134d71a289a
dir: /sys/src/libc/port/utflen.c/
#include <u.h> #include <libc.h> int utflen(char *s) { int c; long n; Rune rune; n = 0; for(;;) { c = *(uchar*)s; if(c < Runeself) { if(c == 0) return n; s++; } else s += chartorune(&rune, s); n++; } }