I am pretty sure /etc/hosts (i.e. an explicitly configured, local,
trusted database) should be useful for overriding the automatic
myhostname logic.
resolved's internal logic handles it that way and hence we should
suggest it in the NSS fallback line, too.
Let's also bring the factory file back into sync with what the docs say.
And update the prose a bit too, to actually match what we recommend.
Unprivileged test-fs-util fails on my system since /sys/dev/block is
inaccessible for unprivileged users, so let's skip encrypted path test if we
get EACCES or similar.
If we don't succeed on the first try it's because another process is
opening the same device. Do a microsleep for 2ms to increase the
chances it has completed the next time around the loop.
The symlink /dev/mapper/dm_name is created by udev after a mapper
device is set up. So libdevmapper/libcrypsetup might tell us that
a verity device exists, but the symlink we use as the source for
the mount operation might not be there yet.
Instead of falling back to a new unique device set up, wait for
the udev event matching on the expected devlink for at least 100ms
(after which the benefits of sharing a device in terms of setup
time start to disappear - on my production machines, opening a new
verity device seems to take between 150ms and 300ms)
This effectively makes little difference because we exit soon later
anyway, which will close the fds, too. However, it's still useful since
it means the parent will get EOF events on them in the order we process
things and isn't delayed to process the data from the pipes until the
child dies.
Let's use a proper table for outputting partition information. Let's
also put the general information about the image first, and the table
after that.
Moreover, dissect the image before showing any output, so that we can
early on return an error if the image is not valid.
That way we can turn off kernel partition scanning if verity data is
available (as we don't support verity for full GPT images, only for
simple file system images).
LOOP_CONFIGURE allows us to configure a loopback device in one ioctl
instead of two, which is not just faster but also removes the race that
udev might start probing the device before we adjusted things properly.
Unfortunately LOOP_CONFIGURE is broken in regards to LO_FLAGS_PARTSCAN
as of kernel 5.8.0. This patch contains a work-around for that, to
fallback to old behaviour if partition scanning is requested but does
not work. Sucks a bit.
Proposed upstream fix for that issue:
https://lkml.org/lkml/2020/8/6/97