138 lines
4.4 KiB
Groff
138 lines
4.4 KiB
Groff
.\" $NetBSD: gettimeofday.2,v 1.11 1999/03/22 19:45:05 garbled Exp $
|
|
.\"
|
|
.\" Copyright (c) 1980, 1991, 1993
|
|
.\" The Regents of the University of California. All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 3. All advertising materials mentioning features or use of this software
|
|
.\" must display the following acknowledgement:
|
|
.\" This product includes software developed by the University of
|
|
.\" California, Berkeley and its contributors.
|
|
.\" 4. Neither the name of the University nor the names of its contributors
|
|
.\" may be used to endorse or promote products derived from this software
|
|
.\" without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" @(#)gettimeofday.2 8.2 (Berkeley) 5/26/95
|
|
.\"
|
|
.Dd May 26, 1995
|
|
.Dt GETTIMEOFDAY 2
|
|
.Os
|
|
.Sh NAME
|
|
.Nm gettimeofday ,
|
|
.Nm settimeofday
|
|
.Nd get/set date and time
|
|
.Sh SYNOPSIS
|
|
.Fd #include <sys/time.h>
|
|
.Ft int
|
|
.Fn gettimeofday "struct timeval *tp" "struct timezone *tzp"
|
|
.Ft int
|
|
.Fn settimeofday "const struct timeval *tp" "const struct timezone *tzp"
|
|
.Sh DESCRIPTION
|
|
.Bf -symbolic
|
|
Note: time zone information is no longer provided by this interface.
|
|
See
|
|
.Xr localtime 3
|
|
for information on how to retrieve it.
|
|
.Ef
|
|
.Pp
|
|
The system's notion of the current UTC time is obtained with the
|
|
.Fn gettimeofday
|
|
call, and set with the
|
|
.Fn settimeofday
|
|
call. The time is expressed in seconds and microseconds
|
|
since midnight (0 hour), January 1, 1970. The resolution of the system
|
|
clock is hardware dependent, and the time may be updated continuously or
|
|
in ``ticks.'' If
|
|
.Fa tp
|
|
is NULL, the time will not be returned or set.
|
|
.Pp
|
|
The structures pointed to by
|
|
.Fa tp
|
|
and
|
|
.Fa tzp
|
|
are defined in
|
|
.Ao Pa sys/time.h Ac
|
|
as:
|
|
.Pp
|
|
.Bd -literal
|
|
struct timeval {
|
|
long tv_sec; /* seconds since Jan. 1, 1970 */
|
|
long tv_usec; /* and microseconds */
|
|
};
|
|
|
|
struct timezone {
|
|
int tz_minuteswest; /* of Greenwich */
|
|
int tz_dsttime; /* type of dst correction to apply */
|
|
};
|
|
.Ed
|
|
.Pp
|
|
The
|
|
.Fa timezone
|
|
structure is provided only for source compatibility. It is ignored by
|
|
.Fn settimeofday ,
|
|
and
|
|
.Fn gettimeofday
|
|
will always return zeroes.
|
|
.Pp
|
|
Only the super-user may set the time of day.
|
|
.\" XXX uncomment when/if this is put into place!
|
|
.\" If the system is running in secure mode (see
|
|
.\" .Xr init 8 ),
|
|
.\" the time may only be advanced.
|
|
.\" This limitation is imposed to prevent a malicious super-user
|
|
.\" from setting arbitrary time stamps on files.
|
|
.\" The system time can still be adjusted backwards using the
|
|
.\" .Xr adjtime 2
|
|
.\" system call even when the system is secure.
|
|
.Sh RETURN
|
|
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 into the global variable
|
|
.Va errno .
|
|
.Sh ERRORS
|
|
The following error codes may be set in
|
|
.Va errno :
|
|
.Bl -tag -width Er
|
|
.It Bq Er EFAULT
|
|
An argument address referenced invalid memory.
|
|
.It Bq Er EPERM
|
|
A user other than the super-user attempted to set the time, or the specified
|
|
time was less than the current time, which was not permitted at the current
|
|
security level.
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr date 1 ,
|
|
.Xr adjtime 2 ,
|
|
.Xr ctime 3 ,
|
|
.Xr localtime 3 ,
|
|
.Xr timed 8
|
|
.Sh HISTORY
|
|
The
|
|
.Fn gettimeofday
|
|
function call appeared in
|
|
.Bx 4.2 .
|
|
The
|
|
.Fa tzp
|
|
argument was deprecated in
|
|
.Bx 4.4
|
|
(and many other systems).
|