Change atoi to strtol in same place

Hello,

we use atoi for user argument processing in same place which return zero
for both invalid input and input value zero. In most case its ok because we
error out with appropriate error message for input zero but in same place
where we accept zero as valued input it case a problem by preceding for
invalid input as input value zero. The attached patch change those place to
strtol which can handle invalid input

regards

Surafel