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| author |   deraadt <deraadt@openbsd.org> | 2010-04-01 06:34:41 +0000 |
|---|---|---|
| committer | deraadt <deraadt@openbsd.org> | 2010-04-01 06:34:41 +0000 |
| commit | 84bf3185e873b30b0a60804386c8de6a576b38e8 (patch) | |
| tree | e198a98daf26274f182b4f9fbc64c4a1ed1452a0 /lib/libc | |
| parent | tweak previous; ok deraadt (diff) | |
| download | wireguard-openbsd-84bf3185e873b30b0a60804386c8de6a576b38e8.tar.xz wireguard-openbsd-84bf3185e873b30b0a60804386c8de6a576b38e8.zip | |
document that setting the time of the machine is unsafe. explain why,
and suggest workarounds
ok guenther
Diffstat (limited to 'lib/libc')
| -rw-r--r-- | lib/libc/sys/gettimeofday.2 | 20 |
1 files changed, 18 insertions, 2 deletions
diff --git a/lib/libc/sys/gettimeofday.2 b/lib/libc/sys/gettimeofday.2 index 1ffedba9895..e12da5fe515 100644 --- a/lib/libc/sys/gettimeofday.2 +++ b/lib/libc/sys/gettimeofday.2 @@ -1,4 +1,4 @@ -.\" $OpenBSD: gettimeofday.2,v 1.16 2007/05/31 19:19:32 jmc Exp $ +.\" $OpenBSD: gettimeofday.2,v 1.17 2010/04/01 06:34:41 deraadt Exp $ .\" .\" Copyright (c) 1980, 1991, 1993 .\" The Regents of the University of California. All rights reserved. @@ -29,7 +29,7 @@ .\" .\" @(#)gettimeofday.2 8.2 (Berkeley) 5/26/95 .\" -.Dd $Mdocdate: May 31 2007 $ +.Dd $Mdocdate: April 1 2010 $ .Dt GETTIMEOFDAY 2 .Os .Sh NAME @@ -124,6 +124,22 @@ A user other than the superuser attempted to set the time. .Xr getitimer 2 , .Xr ctime 3 , .Xr timed 8 +.Sh WARNINGS +Setting the time with +.Fn settimeofday +is dangerous; if possible use +.Xr adjtime 2 +instead. +Many daemon programming techniques utilize time-delta techniques +using the results from +.Xr gettimeofday 2 +instead of from +.Xr clock_gettime 2 +on the +.Dv CLOCK_MONOTONIC +clock. +Time jumps can can cause these programs to malfunction in unexpected ways. +If the time must be set, consider rebooting the machine for safety. .Sh HISTORY The .Fn gettimeofday |