Bug#846365: debrepro: warn about faketime and allow alternative values

[Ximin Luo]

Antonio Terceiro:
> On Wed, Nov 30, 2016 at 07:11:00PM +0000, Ximin Luo wrote:
>> Antonio Terceiro:
>>> On Wed, Nov 30, 2016 at 05:52:04PM +0100, Ximin Luo wrote:
>>>> Package: devscripts
>>>> Version: 2.16.10
>>>> Severity: normal
>>>> Tags: patch
>>>>
>>>> Dear Maintainer,
>>>>
>>>> Running debrepro on glibc causes an infinite loop in the second build (13
>>>> days+ build before I interrupted it). I didn't yet figure out the root cause
>>>> of this in the glibc buildscripts, but faketime causing problems like this is
>>>> a known issue with it, and people are not really expected to work around it.
>>>>
>>>> So debrepro should at least document this, and ideally make it possible to
>>>> disable the time variation or do something else for it. For example, I could
>>>> make the glibc build work by instead using:
>>>>
>>>>   vary 'fakeroot debian/rules binary' \
>>>>     'faketime "@$SOURCE_DATE_EPOCH" fakeroot debian/rules binary'
>>>
>>> the current version is not calling debian/rules directly anymore, nor has
>>> $SOURCE_DATE_EPOCH. it looks like this:
>>>
>>>   vary 'dpkg-buildpackage -b -us -uc' \
>>>     'faketime +213days+7hours+13minutes dpkg-buildpackage -b -us -uc'
>>>
>>> can you please make sure you are running the latest version, and if so, let me
>>> now if it still doesn't work for you?
>>>
>>
>> Hi Antonio, the bug is about the +213days value, so based on what you
>> described it would still exist in the new version. I will test it
>> again to confirm, but this will take a few more days.
>>
>> The suggested fix is to use a value that is in the past instead of the
>> future, but still after the latest entry in d/changelog. One doesn't
>> have to set SOURCE_DATE_EPOCH, merely calling dpkg-parsechangelog
>> would be fine.
> 
> Can you try this instead:
> 
> future=$(date -d '+213days+7hours+13minutes' +%s)
> faketime "@$future" dpkg-buildpackage -b -us -uc
> 

Hi Antonio, why do you think this would have a different effect? Everything that `man faketime` says indicates that all the 3 options that you described would behave identically. Nevertheless, I am testing it now, but I think you are wasting time here.

I told you already, faketime has known problems like this. It is perfectly expected that this +213 days value will cause something to break. That is why we don't just add it to dpkg-buildpackage and say "everything is reproducible" already. If for some magical reason it turns out it is not at fault here for glibc, it will still cause something *else* to break in the future. So an option to disable it is prudent.

X

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