Note gettimeofday(2) for second handling should use clock_gettime(2).

gettimeofday(2) is vulnerable to issues around time changes (DST, leap
seconds, other clock resets) that could cause strange behavior.
clock_gettime with CLOCK_MONOTONIC will give more accurate time deltas,
and should be used instead. (clock_gettime is not available on OSX,
and possibly other OSs, so it should be wrapped.)