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.\" $FreeBSD: src/share/man/man9/inittodr.9,v 1.4.2.4 2001/12/17 11:30:18 ru Exp $ 33.\" $DragonFly: src/share/man/man9/inittodr.9,v 1.3 2004/03/11 12:28:57 hmp Exp $ 34.\" 35.Dd March 22, 1997 36.Dt INITTODR 9 37.Os 38.Sh NAME 39.Nm inittodr 40.Nd initialize system time 41.Sh SYNOPSIS 42.In sys/types.h 43.In sys/systm.h 44.Ft void 45.Fn inittodr "time_t base" 46.Sh DESCRIPTION 47The 48.Fn inittodr 49function determines the time and sets the system clock. 50It tries to pick the correct time using a set of heuristics that examine 51the system's battery backed clock and the time obtained from the root 52file system, as given in 53.Fa base . 54How the 55.Fa base 56value is obtained will vary depending on the 57root file system type. 58The heuristics used include: 59.Bl -bullet 60.It 61If the battery-backed clock has a valid time, it is used. 62.\" .It 63.\" If the battery-backed clock does not have a valid time, and 64.\" the time provided in 65.\" .Fa base 66.\" is within reason, 67.\" .Fa base 68.\" is used as the current time. 69.\" .It 70.\" If the battery-backed clock appears invalid, and 71.\" .Fa base 72.\" appears non-sensical or was not provided (was given as zero), 73.\" a arbitrary base (typically some time in the late 1970s) 74.\" will be used. 75.It 76If the battery-backed clock does not have a valid time, 77the time provided in 78.Fa base 79will be used. 80.El 81.Pp 82Once a system time has been determined, it is stored in the 83.Va time 84variable. 85.Sh DIAGNOSTICS 86The 87.Fn inittodr 88function prints diagnostic messages if it has trouble figuring 89out the system time. Conditions that can cause diagnostic 90messages to be printed include: 91.Bl -bullet 92.It 93The battery-backed clock's time appears nonsensical. 94.\" .It 95.\" The 96.\" .Fa base 97.\" time appears nonsensical. 98.\" .It 99.\" The 100.\" .Fa base 101.\" time and the battery-backed clock's time differ by a large amount. 102.El 103.Sh SEE ALSO 104.Xr resettodr 9 , 105.Xr time 9 106.Sh BUGS 107On many systems, 108.Fn inittodr 109has to convert from 110a time expressed in terms of year, month, day, hours, minutes, 111and seconds to 112.Va time , 113expressed in seconds. Many of the implementations could share code, 114but do not. 115.Pp 116Each system's heuristics for picking the correct time are slightly 117different. 118.Pp 119The 120.Dx 121implementation should do a better job of validating the time provided in 122.Fa base 123when the battery-backed clock is unusable. Currently it unconditionally 124sets the system clock to this value. 125