Use mount namespace to simplify code

[champtar]

With mount namespace we don't need to remount /boot read only before exit.
Also do not try to parse /proc/self/mountinfo, just use '-w' test flag.

If a command is called directly without systemd, reexec ourselves with unshare -m.

[champtar]

All the interesting "CI Test" are skipped, can someone trigger then manually ?

[yih-redhat]

Hi @champtar currently the CI test for this pull request is skipped, I fixed it in main branch in #226.
Could you please rebase this pull request and push again? and then the maintainer of this repo can trigger CI by comment /test.

[champtar]

rebase done

[yih-redhat]

/test

[yih-redhat]

CI is triggered and running here https://github.com/fedora-iot/greenboot/actions/runs/17999478754 , some jobs failed because of the download site in secrets cannot be accessed. Will update the secrets and run again.

(CI triggered by comment /test should update the status of current check jobs, it's a minor bug here, I will fix it soon.)

[yih-redhat]

Hi @champtar sorry to bother you, but could you please rebase this pull request and push again?

Rebase can include:

1. fixed issue that new CI jobs triggered by comment /test cannot update the status of check jobs in this pull request.
2. updated download site secret to fix errors in CI jobs.

[champtar]

@yih-redhat no problem, rebased again
BTW I don't know if you are aware of this GH feature, as Allow edits and access to secrets by maintainers is enabled on this PR, you can rebase and push to my branch
https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/proposing-changes-to-your-work-with-pull-requests/committing-changes-to-a-pull-request-branch-created-from-a-fork

[say-paul]

/test