bug#78574: gnome-disks cannot format partitions unless udisksd is run as root

[aurtzy]

This issue should be resolved now. See 
<https://codeberg.org/guix/guix/pulls/3466> and 
<https://codeberg.org/guix/guix/pulls/3531>.

Hey Denis,
> When running gnome-disks, even as root, I cannot format partitions with
> it: the only "filesystem" that works is "unformated".
> 
> Ext4 seems available but when selected it fails to format the partition
> and the rest of the filesystems are greyed out.
> 
> This is with (service udisks-service-type) in my system configuration.
> 
> However if run 'killall udisksd' and manually run udisksd as root,
> gnome-disks can format most filesystems.

I also see this issue, and the workaround fixes it for me too.

> What happens behind the scenes is that gnome-disks uses some dbus
> wrapper functions to ask the information to Udisks2 through the
> /org/freedesktop/UDisks2/Manager org.freedesktop.UDisks2.Manager
> CanFormat function. It then caches it.
> 
> I've confirmed with d-spy that this function returns true with
> parameters like like 'exfat' (with the quotes) when udisksd runs as
> root and false when it doesn't.
> 
> Udisksd then uses the bd_fs_can_mkfs function from blockdev to get the
> information. I've not read yet the bd_utils_check_util_version that
> does the actual check though. 
> 
> I've also tried to call bd_fs_can_mkfs in a standalone C program but it
> didn't work (it probably needs a bit more setup than copying the
> udisksd call to it).
> 
> And I also didn't look at the udisks-service-type yet. I'll try to find
> more time to dig into bd_utils_check_util_version to understand why it
> fails.

My findings are this issue is due to udisksd not inheriting PATH from the 
service that executes it, so it can't find mkfs executables from 
/run/current-system/profile/{s,}bin.

I've submitted a potential fix: https://codeberg.org/guix/guix/pulls/3466

With regards to the non-root behavior, is udisksd ever supposed to be run as a 
user? I think that might not be a problem if it's intended to be run as a D-Bus 
system service, right?

Cheers,

Alvin