qvm-volume list [--full] confusing behavior

[aronowski]

How to file a helpful issue

Qubes OS release

4.1.2

Brief summary

The behavior and documentation of qvm-volume list seem confusing when considering its --full option.

The documentation says this:

List block devices. By default the internal devices are hidden. When the
stdout is connected to a TTY `qvm-volume list` will print a pretty table by
omitting redundant data. This behaviour is disabled when `--full` option is
passed or stdout is redirected to a pipe or file.

[...]

.. option:: --full

   print domain names

A comment in the qvm_volume.py script says:

If :program:`qvm-volume` is running in a TTY, it will ommit duplicate
        data.

[...]

        :param bool full:    If set to true duplicate data is printed even when
                             running from TTY.

So, as far as I understand, there's something that can be referred to as internal devices, redundant/duplicate data and domain names. Seems confusing to me, even though I spent some time to dig deep in this script as part of PR #259, but maybe it's just me, so let's compare the aforementioned default behavior with its disabled counterpart both by using the --full option and piping, using sys-net as VMNAME:

Steps to reproduce

[user@dom0 ~]$ diff --report-identical-files <(qvm-volume list sys-net) <(qvm-volume list --full sys-net)
Files /dev/fd/63 and /dev/fd/62 are identical
[user@dom0 ~]$ diff --report-identical-files <(qvm-volume list sys-net) <(qvm-volume list sys-net | cat)
Files /dev/fd/63 and /dev/fd/62 are identical

Apparently the logic does not work and it always seems to default to the non-default, A.K.A. the disabled behavior:

[user@dom0 ~]$ qvm-volume list sys-net
POOL:VOLUME                             VMNAME   VOLUME_NAME  REVERT_POSSIBLE
linux-kernel:6.1.42-1.fc32              sys-net  kernel       No
vm-pool:qubes_dom0/vm-sys-net-private   sys-net  private      Yes
vm-pool:qubes_dom0/vm-sys-net-root      sys-net  root         No
vm-pool:qubes_dom0/vm-sys-net-volatile  sys-net  volatile     No
[user@dom0 ~]$ qvm-volume list --full sys-net
POOL:VOLUME                             VMNAME   VOLUME_NAME  REVERT_POSSIBLE
linux-kernel:6.1.42-1.fc32              sys-net  kernel       No
vm-pool:qubes_dom0/vm-sys-net-private   sys-net  private      Yes
vm-pool:qubes_dom0/vm-sys-net-root      sys-net  root         No
vm-pool:qubes_dom0/vm-sys-net-volatile  sys-net  volatile     No
[user@dom0 ~]$ qvm-volume list sys-net | cat
POOL:VOLUME                             VMNAME   VOLUME_NAME  REVERT_POSSIBLE
linux-kernel:6.1.42-1.fc32              sys-net  kernel       No
vm-pool:qubes_dom0/vm-sys-net-private   sys-net  private      Yes
vm-pool:qubes_dom0/vm-sys-net-root      sys-net  root         No
vm-pool:qubes_dom0/vm-sys-net-volatile  sys-net  volatile     No

Expected behavior

I don't know. What's more confusing, the script says:

                if full or not sys.stdout.isatty():
                    output += [(str(volume), vmname, volume_name,
                            volume.revisions)]
                else:
                    output += [('', vmname, volume_name, volume.revisions)]

So the expected behavior might have been something like:

[user@dom0 ~]$ qvm-volume list sys-net
VMNAME   VOLUME_NAME  REVERT_POSSIBLE
sys-net  kernel       No
sys-net  private      Yes
sys-net  root         No
sys-net  volatile     No

where we would refer to the non-printed part (str(volume)) as internal devices. But this would contradict the documentation, which says:

.. option:: --full

   print domain names

So maybe the documentation is wrong too?

Actual behavior

See Steps to reproduce above.

[aronowski]

Affects 4.2