This commit checks early if cross architecture building support via
`qemu-user-static` (or similar tooling) is missing and errors in
a more user friendly way.
Note that there is no integration test right now because testing
this for real requires mutating the very global state of
`echo 0 > /proc/sys/fs/binfmt_misc/qemu-aarch64`
which would make the test non-parallelizable and even risks
failing other cross-arch tests running on the same host (because
binfmt-misc is not namespaced (yet)).
I ran into the `--local` option not working at least in my
setup with the current container image (which for some reason
hasn't been updated, and predates the latest tip commit
which talks about btrfs)
On this current test system (MacOS + podman 5 + default podman-machine)
things do work with the tip commit.
However...I don't quite understand the need to *both* try to
run `systemd-detect-virt` *and* parse `/proc/self/mountinfo`.
(BTW, the logic for `insideContainer` was really confusing me because
it only returned `true` if we were *not* in a container...I wonder
if that was really intentional?)
Anyways, I think the goal here is just a friendly direct error
message if it doesn't look like the mount is there, which we can
do by just checking for the file path. If it isn't mounted
from the host then nothing will be there.
Signed-off-by: Colin Walters <walters@verbum.org>
When the container storage is checked it may come from a btrfs
subvolume. In /proc/self/mountinfo this looks like:
```
1364 1345 0:33 /root/var/lib/containers/storage /var/lib/containers/storage rw,relatime - btrfs /dev/mapper/luks-1356123c-c7b9-1bd7-a8bf-e13d4cbb5500 rw,seclabel,compress=zstd:1,ssd,discard=async,space_cache,subvolid=257,subvol=/root
```
as a quick fix just compare the suffix of the root instead of the
full path.
Thanks for Ondrej!
