1.\" $OpenBSD: inittodr.9,v 1.12 2020/06/26 18:48:31 cheloha Exp $ 2.\" $NetBSD: inittodr.9,v 1.2 1996/03/27 21:16:06 jtc Exp $ 3.\" 4.\" Copyright (c) 1994 Christopher G. Demetriou 5.\" All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. All advertising materials mentioning features or use of this software 16.\" must display the following acknowledgement: 17.\" This product includes software developed by Christopher G. Demetriou 18.\" for the NetBSD Project. 19.\" 3. 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.Dd $Mdocdate: June 26 2020 $ 34.Dt INITTODR 9 35.Os 36.Sh NAME 37.Nm inittodr 38.Nd initialize system time 39.Sh SYNOPSIS 40.Ft void 41.Fn inittodr "time_t base" 42.Sh DESCRIPTION 43The 44.Fn inittodr 45function determines the time and sets the system clock. 46It tries to pick the correct time using a set of heuristics that examine 47the system's battery-backed clock and the time reported by the file 48system, as given in 49.Fa base . 50Those heuristics include: 51.Bl -bullet 52.It 53If the battery-backed clock has a valid time, it is used. 54.It 55If the battery-backed clock does not have a valid time, and 56the time provided in 57.Fa base 58is within reason, 59.Fa base 60is used as the current time. 61.It 62If the battery-backed clock appears invalid, and 63.Fa base 64appears nonsensical or was not provided (was given as zero), 65an arbitrary base (typically some time in the late 1970s) 66will be used. 67.El 68.Pp 69Once a system time has been determined, it is passed to the 70.Fn tc_setclock 71function. 72.Sh DIAGNOSTICS 73The 74.Fn inittodr 75function prints diagnostic messages if it has trouble figuring 76out the system time. 77Conditions that can cause diagnostic messages to be printed include: 78.Bl -bullet 79.It 80The battery-backed clock's time appears nonsensical. 81.It 82The 83.Fa base 84time appears nonsensical. 85.It 86The 87.Fa base 88time and the battery-backed clock's time differ by a large amount. 89.El 90.Sh SEE ALSO 91.Xr microtime 9 , 92.Xr resettodr 9 93.Sh BUGS 94Each system's heuristics for picking the correct time are slightly 95different. 96