ChorusOS man pages section 2POSIX: POSIX System Calls

adjtime(2POSIX)

NAME

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

SYNOPSIS

#include <sys/time.h>

delta

olddelta

API RESTRICTIONS

The function or functions documented here may not be used safely in all application contexts with all APIs provided in the ChorusOS 5.0 product.

See API(5FEA) for details.

DESCRIPTION

The adjtime() function adjusts the system's notion of the current time as returned by gettimeofday(2POSIX), 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 olddelta is not a null pointer, then the structure it points to will contain, upon successful return, the number of 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 the super-user may adjust the time of day.

RETURN VALUES

Upon successful completion, adjtime() returns 0. Otherwise, it returns -1 and sets errno to indicate the error and in this case an error code is stored in the global variable errno.

ERRORS

The adjtime() function will fail if:

EFAULT: The delta or olddelta argument points outside the process's allocated address space.
EPERM: The effective user of the calling process is not super-user.
EINVAL: The tv_usec member of delta is not within valid range (-999999 to 999999).