1.\" $NetBSD: inittodr.9,v 1.13 2007/02/20 08:26:35 wiz Exp $ 2.\" 3.\" Copyright (c) 1994 Christopher G. Demetriou 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. All advertising materials mentioning features or use of this software 15.\" must display the following acknowledgement: 16.\" This product includes software developed for the 17.\" NetBSD Project. See http://www.NetBSD.org/ for 18.\" information about NetBSD. 19.\" 4. The name of the author may not be used to endorse or promote products 20.\" derived from this software without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 23.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 24.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 25.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 26.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 27.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 28.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 29.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 30.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 31.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 32.\" 33.\" <<Id: LICENSE,v 1.2 2000/06/14 15:57:33 cgd Exp>> 34.\" 35.Dd September 6, 2006 36.Dt INITTODR 9 37.Os 38.Sh NAME 39.Nm inittodr 40.Nd initialize system time 41.Sh SYNOPSIS 42.Ft void 43.Fn inittodr "time_t base" 44.Sh DESCRIPTION 45The 46.Fn inittodr 47function determines the time and sets the system clock. 48It tries to pick the correct time using a set of heuristics that examine 49the system's battery-backed clock and the time reported by the file 50system, as given in 51.Fa base . 52Those heuristics include: 53.Bl -bullet 54.It 55If the battery-backed clock has a valid time, and is not significantly 56behind the time provided by 57.Fa base , 58it is used. 59.It 60If the battery-backed clock does not have a valid time, or is significantly 61behind the time provided in 62.Fa base , 63and the time provided in 64.Fa base 65is within reason, 66.Fa base 67is used as the current time. 68.It 69If the battery-backed clock appears invalid, and 70.Fa base 71appears non-sensical or was not provided (was given as zero), 72an arbitrary base (typically some time within the same year that 73the kernel was last updated) will be used. 74.El 75.Pp 76Once a system time has been determined, it is stored in the 77.Va time 78variable. 79.Sh DIAGNOSTICS 80The 81.Fn inittodr 82function prints diagnostic messages if it has trouble figuring 83out the system time. 84Conditions that can cause diagnostic messages to be printed include: 85.Bl -bullet 86.It 87There is no battery-backed clock present on the system. 88.It 89The battery-backed clock's time appears nonsensical. 90.It 91The 92.Fa base 93time appears nonsensical. 94.It 95The 96.Fa base 97time and the battery-backed clock's time differ by a large amount. 98.El 99.Sh SEE ALSO 100.Xr clock_ymdhms_to_secs 9 , 101.Xr resettodr 9 , 102.Xr time_second 9 103.Sh BUGS 104Some systems use heuristics for picking the correct time that are slightly 105different. 106