1.\" $NetBSD: inittodr.9,v 1.2 1996/03/27 21:16:06 jtc 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 by Christopher G. Demetriou 17.\" for the NetBSD Project. 18.\" 3. The name of the author may not be used to endorse or promote products 19.\" derived from this software without specific prior written permission 20.\" 21.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 22.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 23.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 24.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 25.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 26.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 27.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 28.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 30.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 31.\" 32.Dd March 22, 1997 33.Dt INITTODR 9 34.Os 35.Sh NAME 36.Nm inittodr 37.Nd initialize system time 38.Sh SYNOPSIS 39.In sys/types.h 40.In sys/systm.h 41.Ft void 42.Fn inittodr "time_t base" 43.Sh DESCRIPTION 44The 45.Fn inittodr 46function determines the time and sets the system clock. 47It tries to pick the correct time using a set of heuristics that examine 48the system's battery backed clock and the time obtained from the root 49file system, as given in 50.Fa base . 51How the 52.Fa base 53value is obtained will vary depending on the 54root file system type. 55The heuristics used include: 56.Bl -bullet 57.It 58If the battery-backed clock has a valid time, it is used. 59.\" .It 60.\" If the battery-backed clock does not have a valid time, and 61.\" the time provided in 62.\" .Fa base 63.\" is within reason, 64.\" .Fa base 65.\" is used as the current time. 66.\" .It 67.\" If the battery-backed clock appears invalid, and 68.\" .Fa base 69.\" appears non-sensical or was not provided (was given as zero), 70.\" a arbitrary base (typically some time in the late 1970s) 71.\" will be used. 72.It 73If the battery-backed clock does not have a valid time, 74the time provided in 75.Fa base 76will be used. 77.El 78.Pp 79Once a system time has been determined, it is stored in the 80.Va time 81variable. 82.Sh DIAGNOSTICS 83The 84.Fn inittodr 85function prints diagnostic messages if it has trouble figuring 86out the system time. 87Conditions that can cause diagnostic messages to be printed include: 88.Bl -bullet 89.It 90The battery-backed clock's time appears nonsensical. 91.\" .It 92.\" The 93.\" .Fa base 94.\" time appears nonsensical. 95.\" .It 96.\" The 97.\" .Fa base 98.\" time and the battery-backed clock's time differ by a large amount. 99.El 100.Sh SEE ALSO 101.Xr resettodr 9 , 102.Xr time 9 103.Sh BUGS 104On many systems, 105.Fn inittodr 106has to convert from 107a time expressed in terms of year, month, day, hours, minutes, 108and seconds to 109.Va time , 110expressed in seconds. 111Many of the implementations could share code, but do not. 112.Pp 113Each system's heuristics for picking the correct time are slightly 114different. 115.Pp 116The 117.Fx 118implementation should do a better job of validating the time provided in 119.Fa base 120when the battery-backed clock is unusable. 121Currently it unconditionally sets the system clock to this value. 122