MirBSD manpage: gettimeofday(2), settimeofday(2)

GETTIMEOFDAY(2)            BSD Programmer's Manual             GETTIMEOFDAY(2)

NAME

     gettimeofday, settimeofday - get/set date and time

SYNOPSIS

     #include <sys/time.h>

     int
     gettimeofday(struct timeval *tp, struct timezone *tzp);

     int
     settimeofday(const struct timeval *tp, const struct timezone *tzp);

DESCRIPTION

     Note: timezone is no longer used; this information is kept outside the
     kernel.

     The system's notion of the current Greenwich time and the current time
     zone is obtained with the gettimeofday() call, and set with the set-
     timeofday() call. The time is expressed in seconds and microseconds since
     the epoch, 00:00:00 seconds at midnight (0 hour), January 1, 1970, Temps
     Atomique International (TAI). Leap seconds are counted, violating POSIX
     but providing correct time. The resolution of the system clock is
     hardware dependent, and the time may be updated continuously or in
     "ticks". If tp or tzp is NULL, the associated time information will not
     be returned or set.

     The structures pointed to by tp and tzp are defined in <sys/time.h> as:

     struct timeval {
             time_t  tv_sec;         /* seconds since Jan. 1, 1970, 00:00:00 */
             long    tv_usec;        /* and microseconds */
     };

     struct timezone {
             int     tz_minuteswest; /* of Greenwich */
             int     tz_dsttime;     /* type of dst correction to apply */
     };

     The timezone structure indicates the local time zone (measured in minutes
     of time westward from Greenwich), and a flag that, if nonzero, indicates
     that Daylight Saving time applies locally during the appropriate part of
     the year.

     Only the superuser may set the time of day or time zone. If the system
     securelevel is greater than 1 (see init(8)), the time may only be ad-
     vanced. This limitation is imposed to prevent a malicious superuser from
     setting arbitrary time stamps on files. The system time can still be ad-
     justed backwards using the adjtime(2) system call even when the system is
     secure.

RETURN VALUES

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

ERRORS

     The following error codes may be set in errno:

     [EFAULT]  An argument address referenced invalid memory.

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

SEE ALSO

     date(1), adjtime(2), getitimer(2), ctime(3), timed(8)

HISTORY

     The gettimeofday() function call appeared in 4.2BSD. The tv_sec element
     of struct timeval is of type time_t since MirBSD #8.

MirBSD #10-current               May 26, 1995                                1