Hello Willy,
Le 13/03/2016 23:49, Willy Tarreau a écrit :
> Hi Benoit,
>
> On Sat, Mar 12, 2016 at 09:45:25AM +0100, Benoît GARNIER wrote:
>> You just need to call tzset() once before chrooting to initialize the
>> timezone subsystem.
> Finally I did it directly in your patch, it was not worth delaying a
> release for such a small change.
I did not send the patch earlier because I was trying to gather some
more informations about chroot() and local times.
It seems that my patch would not play nicely with some versions of glibc
and could introduce a subtle bug.
Some time functions call tzset() internally. This is the case for
strftime() or localtime() (but not localtime_r() or gettimeofday()).
So when populating the GMT offset cache, a hidden call to tzset() is done.
The issue is that some old glibc, when not finding /etc/localtime (this
is the case after a chroot), would reset the timezone to GMT.
Thus, the first log would have a localtime with a GMT offset (wrongly)
set to +00:00, and subsequent logs would be in full GMT time.
See the following bug: https://bugzilla.redhat.com/show_bug.cgi?id=444043
In this case the only solution is to copy /etc/localtime to
<chroot>/etc/localtime.
So, I was trying to elaborate on your previous suggestion: prepare the
cache at startup, but without messing with the tm_isdst flag.
Benoit GARNIER
Le 13/03/2016 23:49, Willy Tarreau a écrit :
> Hi Benoit,
>
> On Sat, Mar 12, 2016 at 09:45:25AM +0100, Benoît GARNIER wrote:
>> You just need to call tzset() once before chrooting to initialize the
>> timezone subsystem.
> Finally I did it directly in your patch, it was not worth delaying a
> release for such a small change.
I did not send the patch earlier because I was trying to gather some
more informations about chroot() and local times.
It seems that my patch would not play nicely with some versions of glibc
and could introduce a subtle bug.
Some time functions call tzset() internally. This is the case for
strftime() or localtime() (but not localtime_r() or gettimeofday()).
So when populating the GMT offset cache, a hidden call to tzset() is done.
The issue is that some old glibc, when not finding /etc/localtime (this
is the case after a chroot), would reset the timezone to GMT.
Thus, the first log would have a localtime with a GMT offset (wrongly)
set to +00:00, and subsequent logs would be in full GMT time.
See the following bug: https://bugzilla.redhat.com/show_bug.cgi?id=444043
In this case the only solution is to copy /etc/localtime to
<chroot>/etc/localtime.
So, I was trying to elaborate on your previous suggestion: prepare the
cache at startup, but without messing with the tm_isdst flag.
Benoit GARNIER