fixed rt_kprintf %s precision print error.
@@ -922,7 +922,7 @@ rt_int32_t rt_vsnprintf(char *buf,
s = va_arg(args, char *);
if (!s) s = "(NULL)";
- len = rt_strlen(s);
+ for (len = 0; (len != field_width) && (s[len] != '\0'); len++);
#ifdef RT_PRINTF_PRECISION
if (precision > 0 && len > precision) len = precision;
#endif
