opensolaris man page for adjtime

adjtime(2)							   System Calls 							adjtime(2)

NAME
       adjtime - correct the time to allow synchronization of the system clock

SYNOPSIS
       #include <sys/time.h>

       int adjtime(struct timeval *delta, struct timeval *olddelta);

DESCRIPTION
       The  adjtime()  function  adjusts the system's notion of the current time as returned by gettimeofday(3C), advancing or retarding it by the
       amount of time specified in the struct timeval pointed to by delta.

       The adjustment is effected by speeding up (if that amount of time is positive) or slowing down (if that amount of  time	is  negative)  the
       system's  clock	by  some  small percentage, generally a fraction of one percent. The time is always a monotonically increasing function. A
       time correction from an earlier call to adjtime() may not be finished when adjtime() is called again.

       If delta is 0, then olddelta returns the status of the effects of the previous adjtime() call with no effect on the time  correction  as  a
       result of this call. If olddelta is not a null pointer, then the structure it points to will contain, upon successful return, the number of
       seconds and/or microseconds still to be corrected from the earlier call. If olddelta is a null pointer, the corresponding information  will
       not be returned.

       This  call  may be used in time servers that synchronize the clocks of computers in a local area network. Such time servers would slow down
       the clocks of some machines and speed up the clocks of others to bring them to the average network time.

       Only a processes with appropriate privileges can adjust the time of day.

       The adjustment value will be silently rounded to the resolution of the system clock.

RETURN VALUES
       Upon successful completion, adjtime() returns 0. Otherwise, it returns -1 and sets errno to indicate the error.

ERRORS
       The adjtime() function will fail if:

       EFAULT	 The delta or olddelta argument points outside the process's allocated address space, or  olddelta  points  to	a  region  of  the
		 process's allocated address space that is not writable.

       EINVAL	 The tv_usec member of delta is not within valid range (-1000000 to 1000000).

       EPERM	 The {PRIV_SYS_TIME} privilege is not asserted in the effective set of the calling process.

       Additionally, the adjtime() function will fail for 32-bit interfaces if:

       EOVERFLOW    The  size  of  the tv_sec member of the timeval structure pointed to by olddelta is too small to contain the correct number of
		    seconds.

SEE ALSO
       date(1), gettimeofday(3C), privileges(5)

SunOS 5.11							    20 Jan 2003 							adjtime(2)