Re: [PATCH v2 0/4] Fix ccache issues

["Moessbauer, Felix" <felix.moessbauer@siemens.com>]

On Wed, 2023-04-05 at 15:28 +0200, Baurzhan Ismagulov wrote:
> On 2023-04-05 11:56, Moessbauer, Felix wrote:
> > > What about sudo addgroup ccache; sudo adduser build ccache; sudo
> > > chgrp -R
> > > ccache /ccache; sudo chmod -R g+w /ccache; find /ccache -type d
> > > |sudo
> > > xargs
> > > chmod g+s? Maybe also sudo adduser root ccache.
> > 
> > This would solve the permission issues at the cost of always
> > touching a
> > lot of files.
> 
> Hmm, why always a lot? This is meant as a one-time action during
> setup. Set the
> directory group to ccache, set the mode to at least 2770 -- anything
> that is
> created under it should be readable and writable by anyone in the
> group. I used
> this in the past, but didn't test with root and NFS.

Is this a one-time action per dpkg-build task, or how often is that
called? I'm also a bit unsure how that works together with other ccache
instances from older ISAR versions that simultaneously work on the same
cache, but using root. The automatic internal cleanup logic of the
ccache as builder might then want to delete ccache entries which have
been created by a ccache running as root, but after the chmod:

An example sequence is the following (A: old, B:new):

B: run chmod
A: create cache entries
B: write to cache, fill it up and delete entries created by A

Do I miss something?

Best regards,
Felix

> 
> With kind regards,
> Baurzhan
>