ref: b4cb19235eb84f5e08539a10fcdd671a06494e94 dir: /sys/src/ape/lib/ap/gen/strnlen.c/
#include <string.h> size_t strnlen(const char *s, size_t maxlen) { size_t i; for (i = 0; i < maxlen && s[i] != '\0'; i++) ; return i; }