1.\" $OpenBSD: adjfreq.2,v 1.5 2013/08/14 06:32:29 jmc Exp $ 2.\" 3.\" Copyright (c) 2006 Otto Moerbeek 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 15.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 18.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24.\" SUCH DAMAGE. 25.\" 26.Dd $Mdocdate: August 14 2013 $ 27.Dt ADJFREQ 2 28.Os 29.Sh NAME 30.Nm adjfreq 31.Nd correct the rate of the system clock 32.Sh SYNOPSIS 33.Fd #include <sys/types.h> 34.Fd #include <sys/time.h> 35.Ft int 36.Fn adjfreq "const int64_t *freq" "int64_t *oldfreq" 37.Sh DESCRIPTION 38.Fn adjfreq 39adjusts the rate in which time progresses if 40.Fa freq 41is non-null. 42The unit of the rate of adjustment is nanoseconds per second, 43shifted left 32 bits to allow for fractional values. 44.Pp 45If 46.Fa oldfreq 47is non-null, the current value is returned. 48.Pp 49Only the superuser may adjust the frequency. 50.Sh RETURN VALUES 51A return value of 0 indicates that the call succeeded. 52A return value of \-1 indicates that an error occurred, and in this 53case an error code is stored in the global variable 54.Va errno . 55.Sh ERRORS 56.Fn adjfreq 57will fail if: 58.Bl -tag -width Er 59.It Bq Er EFAULT 60Either of the arguments point outside the process's allocated address space. 61.It Bq Er EPERM 62The 63.Fa freq 64argument is non-null and the process's effective user ID is not that 65of the superuser. 66.El 67.Sh SEE ALSO 68.Xr date 1 , 69.Xr adjtime 2 , 70.Xr gettimeofday 2 , 71.Xr ntpd 8 72.Sh HISTORY 73The 74.Fn adjfreq 75function call first appeared in 76.Ox 4.0 . 77