This tries to shorten the race of device reuse a bit more: let's ignore
udev database entries that are older than the time where we started to
use a loopback device.
This doesn't fix the whole loopback device raciness mess, but it makes
the race window a bit shorter.
Let's drop all monitor uevent that were enqueued before we actually
started setting up the device.
This doesn't fix the race, but it makes the race window smaller: since
we cannot determine the uevent seqnum and the loopback attachment
atomically, there's a tiny window where uevents might be generated by
the device which we mistake for being associated with out use of the
loopback device.
Previously, the flag did two things at once: enable support for using
generic partitions as root fs if there were only one/allow use of
partition-table-less images as root fs. And secondly, insist that there
was a rootfs, and fail if not. Let's split these two in two separate
options so that they can be used independently of each other.
There are cases where one wants to use one without the other (i.e. when
inspecting things with systemd-dissect tool it should be OK to do so
even if image has no root fs), and it's cleaner anyway.
Let's make use of the new dissection in all tools where this makes
sense, which are all tools that dissect images, except for those which
inherently operate on state/configuraiton and thus where an image
without state nor configuration is useless (e.g.
systemd-tmpfiles/systemd-firstboot/… --image= switch).
The old name originates when this was used to discover "machine" images,
as managed by machined/machinectl. But nowadays this is also used by
portable services and system extensions, hence let's use a more generic
name for this API. Taking inspiration from "dissect-image.[ch]", let's call
this "discover-image.[ch]".
This is pure renaming, no other changes.
I think this formatting was originally used because it simplified
adding new options to the help messages. However, these days, most
tools their help message end with "\nSee the %s for details.\n" so
the final line almost never has to be edited which eliminates the
benefit of the custom formatting used for printf() help messages.
Let's make things more consistent and use the same formatting for
printf() help messages that we use everywhere else.
Prompted by https://github.com/systemd/systemd/pull/18355#discussion_r567241580
Lennart Poettering
Zbigniew Jędrzejewski-Szmek
Yu Watanabe
Luca Boccassi
Daan De Meyer