adjtime - gradually adjust system clock
#include <sys/time.h>
int adjtime(const struct timeval* delta, struct timeval* old_delta);adjtime() gradually increments the system time by delta, if it is non-null.
Serenity OS slows down or speeds up the system clock by at most 1%, so adjusting the time by N seconds takes 100 * n seconds to complete.
Calling settimeofday() or clock_settime() cancels in-progress time adjustments done by adjtime.
If delta is not null, adjtime can only called by the superuser.
If old_delta is not null, it returns the currently remaining time adjustment. Querying the remaining time adjustment does not need special permissions.
In pledged programs, the settime promise is required when delta is not null.
EFAULT: delta and/or old_delta are not null and not in readable memory.EINVAL: delta is not null and has a tv_nsec field that's less than 0 or larger or equal to 10^6. Negative deltas should have a negative tv_sec field but a tv_nsec that's larger or equal zero. For example, a delta of -0.5 s is represented by {-1, 500'000}.EPERM: delta is not null but geteuid() is not 0.