[Reproducible-builds] Variation in day

[Jérémy Bobbio]

Reiner Herrmann:
> after Faux found a package with a variation not in time, but only
> in the date [1] because it was built around midnight, I had an idea
> about how to get a variation in the day, without having to change
> the clock of the host.
> 
> Varying the timezone between the first and second build to the
> lowest and highest possible offset gives a difference of about
> one day:
> 
> $ TZ=/usr/share/zoneinfo/Etc/GMT+12 date
> Tue Feb 24 09:05:40 GMT+12 2015
> $ TZ=/usr/share/zoneinfo/Etc/GMT-14 date
> Wed Feb 25 11:05:49 GMT-14 2015
> 
> It is even possible to cover a day and 2 hours. :)
> (Perhaps it's even possible to create custom timezones, that
> would allow even larger variations like a year or so...?)
> 
> What do you think about this approach?
> Would there be any disadvantages, and does anyone know
> of tools that ignore the TZ setting?

That would be the difference between gmtime(3) and localtime(3). So this
will not catch tools using time in UTC format.

But timezone is a worthwhile variation in itself! :)

-- 
Lunar                                .''`. 
lunar at debian.org                    : :Ⓐ  :  # apt-get install anarchism
                                    `. `'` 
                                      `-   
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