[RFC] sysroot: Support boot counting for boot entries

[igoropaniuk]

Add support for boot counting for bootloader entries [1]. The boot counting data is stored in the name of the boot loader entry. A boot loader entry file name may contain a plus (+) followed by a number. This may optionally be followed by a minus (-) followed by a second number. The dot (.) and file name suffix (conf or efi) must immediately follow.

All "pending" entries (in the middle of boot counting) are automatically removed during creation of new boot entries for new deployments.

Testing:
$ ostree admin deploy 91fc19319be9e79d07159303dff125f40f10e5c25614630dcbed23d95e36f907 Copying /etc changes: 2 modified, 3 removed, 4 added bootfs is sufficient for calculated new size: 0 bytes Transaction complete; bootconfig swap: yes; bootversion: boot.0.1, deployment count change: 1

$ ls /boot/loader/entries
ostree-1+3.conf ostree-2+3.conf

[1] https://uapi-group.org/specifications/specs/boot_loader_specification/#boot-counting

[openshift-ci]

Hi @igoropaniuk. Thanks for your PR.

I'm waiting for a ostreedev member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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[igoropaniuk]

This PR was created for initial feedback, I'll address the naming in the tests if needed and re-push

[cgwalters]

I love the idea of integrating here, thanks for starting this! This came up before in at least #3032

Hmm don't we need to consider how we make this configurable? Currently systemd kernel-install parses /etc/kernel/tries. (I think we should also support a /usr/lib variant of this, but that's mostly an aside). I guess we could in theory just start honoring that file too?