Re: Should the tcpdump tests be run with TZ=GMT0, or should the AFS printer print time stamps in UTC?

[Francois-Xavier Le Bail <devel.fx.lebail () orange fr>]

On 05/08/2018 15:12, Francois-Xavier Le Bail wrote:
> On 05/08/2018 14:46, Denis Ovsienko wrote:
> >  ---- On Sat, 04 Aug 2018 08:41:10 +0100 Francois-Xavier Le Bail <devel.fx.lebail () orange fr> wrote ---- 
> >  > On 04/08/2018 09:03, Guy Harris wrote:
> >  > > On Aug 3, 2018, at 6:44 PM, Michael Richardson <mcr () sandelman ca> wrote:
> >  > > 
> >  > >> Guy Harris <gharris () sonic net> wrote:
> >  > >>> Currently, the tcpdump tests for AFS fail if you're not in the time
> >  > >>> zone where the .out files were generated, because AFS time stamps are
> >  > >>> printed as local time rather than as UTC.
> >  > >>
> >  > >> That's broken
> >  > 
> >  > Why broken ? it's just local time.
> >
> > The problem is to make the printed value unambiguous (i.e. for any valid binary value VP1 from the packet there is 
> > exactly one printed string value VS, and VS can be parsed into exactly one binary value VP2, and VP1 == VP2). If the 
> > VS value uses local clock time, the format should tell the timezone, such that the output of tcpdump made in one 
> > time zone can be correctly understood by the user in another (less human errors).
> >
> > One problem with setting TZ before running is that tcpdump output does not tell what timezone it uses, and even if 
> > it does, some users will get different output for the same input by default. Another is that the test will require a 
> > custom script because at the moment the tests in TESTLIST either all use a custom TZ, or none of them (as it is now).
> >
> > That said, if the output uses UTC, it could be helpful to use an unambiguous format as well, as in commit 99412d6.
> >
> >  > > So we should just change it to use gmtime() rather than localtime().
> >  > 
> >  > I think an user prefer have the local time.
>
> There are two cases:
>
> 1) As a user, when I run a capture, I prefer the printing of local time for all time display.
> If, for any reason, I want to change this I can use: (TZ=... ; tcpdump ...)

I mean: (TZ=... ./tcpdump ...)

> 2) For tests in TESTLIST, we could build and check the output with TZ=GMT0 (in TESTrun.sh and
> update-test.sh).
> Like that, we could run the tests without the '-t' option and get problems/changes in time printing
> functions. Need an update to the current tests outputs (I can do it).
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-- 
Francois-Xavier
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