Comment # 7 on bug 1214249 from Richard Biener

I'll note again that __strlcpy_chk does

  if (__glibc_unlikely (s1len < n))
    __chk_fail ();

  return __strlcpy (s1, s2, n);

so it doesn't check whether 's2' might be shorter than s1len and thus
the call is actually safe (it might be safe to call strnlen (s2, n)).