CLOCK_GETTIME(2)          OpenBSD Programmer's Manual         CLOCK_GETTIME(2)

NAME
     clock_gettime, clock_settime, clock_getres - get/set/calibrate date and
     time



SYNOPSIS
     #include <sys/time.h>

     int
     clock_gettime(clockid_t clock_id, struct timespec *tp);

     int
     clock_settime(clockid_t clock_id, const struct timespec *tp);

     int
     clock_getres(clockid_t clock_id, struct timespec *tp);

DESCRIPTION
     The clock_gettime() and clock_settime() allow the calling process to re-
     trieve or set the value used by a clock which is specified by clock_id.

     clock_id can be one of three values: CLOCK_REALTIME for time that incre-
     ments as a wall clock should, CLOCK_VIRTUAL for time that increments only
     when the CPU is running in user mode on behalf of the calling process, or
     CLOCK_PROF for time that increments when the CPU is running in user or
     kernel mode.

     The structure pointed to by tp is defined in <sys/time.h> as:

     struct timespec {
             time_t  tv_sec;         /* seconds */
             long    tv_nsec;        /* and nanoseconds */
     };

     Only the super-user may set the time of day.  If the system securelevel
     is greater than 1 (see init(8)),  the time may only be advanced.  This
     limitation is imposed to prevent a malicious super-user from setting ar-
     bitrary time stamps on files.  The system time can still be adjusted
     backwards using the adjtime(2) system call even when the system is se-
     cure.

     The resolution (granularity) of a clock is returned by the clock_getres()
     call.  This value is placed in a (non-null) *tp.

RETURN VALUES
     A 0 return value indicates that the call succeeded.  A -1 return value
     indicates an error occurred, and in this case an error code is stored in-
     to the global variable errno.

ERRORS
     The following error codes may be set in errno:

     [EINVAL]  The clock_id was not a valid value.

     [EFAULT]  The *tp argument address referenced invalid memory.

     [EPERM]   A user other than the super-user attempted to set the time.

SEE ALSO
     date(1),  adjtime(2),  ctime(3),  timed(8)

STANDARDS
     The clock_gettime(), etc.  functions conform to IEEE Std1003.1b-1993
     (``POSIX'').

OpenBSD 2.6                       May 8, 1997                                1