Demi Marie Obenour <demiobenour@gmail.com> writes:

> On 7/13/26 05:39, Alyssa Ross wrote:
>> Demi Marie Obenour <demiobenour@gmail.com> writes:
>> 
>>> cgroup-setup is written in Rust and uses the Rust standard library.

FWIW it might be good to say "cgroup-setup, a tool which will be
introduced in a later patch" or something.  Otherwise I have to guess
what this is referring to.

>>> It also relies on cgroupfs being mounted at /sys/fs/cgroup.
>>> Furthermore, it runs very, *very* early on, since it sets up the cgroups
>>> in which s6-svscan and s6-supervise processes run.  This allows setting
>>> up sub-cgroups without having to worry about name collisions.
>>>
>>> While it would be possible to only mount the bare minimum necessary,
>>> it's simpler to just mount everything before starting any services.
>>> These mounts are all pseudo-filesystems or tmpfs instances, and none
>>> have any dependencies.
>>>
>>> Signed-off-by: Demi Marie Obenour <demiobenour@gmail.com>
>>> ---
>>>  host/rootfs/image/etc/init                          | 11 ++++++++++-
>>>  host/rootfs/image/etc/s6-linux-init/scripts/rc.init |  9 +--------
>>>  2 files changed, 11 insertions(+), 9 deletions(-)
>>>
>>> diff --git a/host/rootfs/image/etc/init b/host/rootfs/image/etc/init
>>> index db8a6d9c747e3d212c21b6c983c8f7e299822abe..8ec7859ab00e24007a93d4000c8f34e353de50ae 100755
>>> --- a/host/rootfs/image/etc/init
>>> +++ b/host/rootfs/image/etc/init
>>> @@ -1,6 +1,15 @@
>>>  #!/bin/execlineb -Ws0
>>>  # SPDX-License-Identifier: EUPL-1.2+
>>> -# SPDX-FileCopyrightText: 2022 Alyssa Ross <hi@alyssa.is>
>>> +# SPDX-FileCopyrightText: 2020-2022, 2024 Alyssa Ross <hi@alyssa.is>
>>>  
>>>  /bin/setpriv --no-new-privs --
>>> +
>>> +if { /bin/ln -s /proc/self/fd /dev }
>>> +if { /bin/ln -s /proc/self/fd/0 /dev/stdin }
>>> +if { /bin/ln -s /proc/self/fd/1 /dev/stdout }
>>> +if { /bin/ln -s /proc/self/fd/2 /dev/stderr }
>> 
>> I guess the idea is that the Rust standard library might want these?
>
> I don't know if it actually does, though I would not be surprised if
> it is not tested without them.  What *is* necessary is for a cgroup
> filesystem to be mounted at /sys/fs/cgroup.  This allows setting up
> cgroup controllers and moving PID 1 to a sub-cgroup.

Yeah, that's what I thought.  It doesn't do any harm to create them
early anyway, so this is fine.

>>> +
>>> +if { /bin/mount --make-shared / }
>>> +if { /bin/mount -a --mkdir }
>>> +
>>>  /bin/s6-linux-init -c /etc/s6-linux-init -s /run/param -- $@
>>> diff --git a/host/rootfs/image/etc/s6-linux-init/scripts/rc.init b/host/rootfs/image/etc/s6-linux-init/scripts/rc.init
>>> index f638e373589884acb959c868462fdf532380a851..fba305c4e9cbb9f7535f11bb4c06d8da8a34837b 100755
>>> --- a/host/rootfs/image/etc/s6-linux-init/scripts/rc.init
>>> +++ b/host/rootfs/image/etc/s6-linux-init/scripts/rc.init
>>> @@ -4,13 +4,6 @@
>>>  
>>>  if { s6-rc-init -c /etc/s6-rc /run/service }
>>>  
>>> -if { ln -s /proc/self/fd /dev }
>>> -if { ln -s /proc/self/fd/0 /dev/stdin }
>>> -if { ln -s /proc/self/fd/1 /dev/stdout }
>>> -if { ln -s /proc/self/fd/2 /dev/stderr }
>>> -
>>> -if { mount --make-shared / }
>>> -if { mount --make-shared /run }
>>> -if { mount -a --mkdir }
>>> +if { /bin/mount --make-shared /run }
>> 
>> Presumably this does not actually suddenly need an absolute path.
>
> You are correct.

Alright then, with that fixed:

Reviewed-by: Alyssa Ross <hi@alyssa.is>