Question about mkfs.erofs and reproducible builds

[Gao Xiang]

Hi Todor,

On Wed, Oct 27, 2021 at 02:11:24PM +0300, Todor Ivanov wrote:
>         Hello,
> 
>         We are trying to replace squashfs with erofs and face an issue with
> reproducing the build from one and the same source folder. The source
> folder is "/etc" actually taken from an offline ubuntu 20.04 image and
> mounted as read-only.
>         I managed to narrow down the scope and it turns out that the issue
> is when you have a file starting with "." (dot) in this folder. I.e.:
> 
> etc/.anyfilename
> 
> If I remove this file the erofs image of "etc" is reproducible (-T and -U
> are used as well)
> 
> The issue is somehow related to the other 76 subfolders of etc and this
> file starting with dot. For example if I create such .anyfilename in usr or
> var, there is no issue. Also if I create this file under
> etc/xdg/.anyfilename, this is fine as well.
> I also tried with etc from debian10 and the result is the same. Removing
> any file that starts with dot directly under etc, makes the erofs build
> reproducible.
> Do you have any advice on this?

In principle filenames starting with '.' won't impact anything about
reproducible builds...

Let me investigate it now... But may I ask which erofs-utils version
is used? Does it still happen on the latest dev branch?

Thanks,
Gao Xiang

> 
> Regards,
> Todor