explain_adjtime_or_die(3) [debian man page]

explain_adjtime_or_die(3)				     Library Functions Manual					 explain_adjtime_or_die(3)

NAME

       explain_adjtime_or_die - smoothly tune kernel clock and report errors

SYNOPSIS

       #include <libexplain/adjtime.h>
       void explain_adjtime_or_die(const struct timeval *delta, struct timeval *olddelta);
       int explain_adjtime_on_error(const struct timeval *delta, struct timeval *olddelta);

DESCRIPTION

       The  explain_adjtime_or_die  function  is  used	to  call  the adjtime(2) system call. On failure an explanation will be printed to stderr,
       obtained from the explain_adjtime(3) function, and then the process terminates by calling exit(EXIT_FAILURE).

       The explain_adjtime_on_error function is used to call the adjtime(2) system call. On failure an explanation  will  be  printed  to  stderr,
       obtained from the explain_adjtime(3) function, but still returns to the caller.

       delta   The delta, exactly as to be passed to the adjtime(2) system call.

       olddelta
	       The olddelta, exactly as to be passed to the adjtime(2) system call.

RETURN VALUE

       The  explain_adjtime_or_die  function  only  returns on success, see adjtime(2) for more information. On failure, prints an explanation and
       exits, it does not return.

       The explain_adjtime_on_error function always returns the value return by the wrapped adjtime(2) system call.

EXAMPLE

       The explain_adjtime_or_die function is intended to be used in a fashion similar to the following example:
	      explain_adjtime_or_die(delta, olddelta);

SEE ALSO

       adjtime(2)
	       smoothly tune kernel clock

       explain_adjtime(3)
	       explain adjtime(2) errors

       exit(2) terminate the calling process

COPYRIGHT

       libexplain version 0.52
       Copyright (C) 2009 Peter Miller

															 explain_adjtime_or_die(3)

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 5.10							    20 Jan 2003 							adjtime(2)