cond_reltimedwait(3C) is very similar to cond_timedwait(), except for the value for the third argument. cond_reltimedwait() takes a relative time interval value in its third argument rather than an absolute time of day value. For POSIX threads, see the pthread_cond_reltimedwait_np(3C) man page.
cond_reltimedwait() always returns with the mutex locked and owned by the calling thread even when returning an error. The cond_reltimedwait() function blocks until the condition is signaled or until the time interval specified by the last argument has elapsed.
#include <thread.h>
int cond_reltimedwait(cond_t *cv, mutex_t *mp,
timestruct_t reltime);
cond_reltimedwait() returns 0 if successful. When any of the following conditions is detected, cond_reltimedwait() fails and returns the corresponding value.
EFAULT
Description: cv points to an illegal address.
ETIME
Description: The time specified by reltime has expired.