Fixup "criu: support mounts where dest is a symlink"

[kolyshkin]

This fixes issues brought by #1747, and also cherry-picks #1756 so that the changes can be tested.

Summary by Sourcery

Fix CRIU checkpoint and restore procedures to support bind mounts where the destination in rootfs is a symlink

Bug Fixes:

• Fall back to using the original mount destination when chroot_realpath fails with ENOENT instead of erroring out

Enhancements:

• Resolve mount destinations against status->rootfs directly and remove redundant path concatenation in restore
• Rename internal rootfs variable to path in checkpoint function

[sourcery-ai]

Reviewer's Guide

Refactor CRIU root path handling by renaming internal variables, remove redundant rootfs setup in restore, and improve external bind mount resolution to handle symlink destinations and missing paths gracefully.

Sequence Diagram: Updated External Mount Path Resolution in CRIU Checkpoint

sequenceDiagram
    participant C as libcrun_container_checkpoint_linux_criu
    participant CRR as chroot_realpath
    participant LCW as libcriu_wrapper

    C->>CRR: Call chroot_realpath(status->rootfs, mount->destination, buf)
    CRR-->>C: Return resolved_path_absolute or NULL
    alt resolved_path_absolute is NULL
        C->>C: Check errno
        alt errno is ENOENT
            C->>C: dest_in_root = mount->destination
        else errno is not ENOENT
            C->>C: Handle error (unable to resolve mount)
        end
    else resolved_path_absolute is not NULL
        C->>C: dest_in_root = resolved_path_absolute + strlen(status->rootfs)
    end
    C->>LCW: criu_add_ext_mount(dest_in_root, dest_in_root)

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Sequence Diagram: Updated External Mount Path Resolution in CRIU Restore

sequenceDiagram
    participant R as libcrun_container_restore_linux_criu
    participant CRR as chroot_realpath
    participant LCW as libcriu_wrapper

    R->>CRR: Call chroot_realpath(status->rootfs, mount->destination, buf)
    CRR-->>R: Return resolved_path_absolute or NULL
    alt resolved_path_absolute is NULL
        R->>R: Check errno
        alt errno is ENOENT
            R->>R: dest_in_root = mount->destination
        else errno is not ENOENT
            R->>R: Handle error (unable to resolve mount)
        end
    else resolved_path_absolute is not NULL
        R->>R: dest_in_root = resolved_path_absolute + strlen(status->rootfs)
    end
    R->>LCW: criu_add_ext_mount(dest_in_root, mount->source)

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File-Level Changes

Change	Details	Files
Rename and consolidate CRIU root path variable in checkpoint	Rename cleanup_free char *rootfs to cleanup_free char *path Update append_paths invocation to populate path Change criu_set_root calls and error messages to reference path	src/libcrun/criu.c
Enhance external bind mount resolution logic	Switch chroot_realpath base from previous root variable to status->rootfs Introduce ENOENT branch to fallback to original destination when not under rootfs Adjust dest_in_root pointer arithmetic accordingly Refine error messages for mount resolution failures	src/libcrun/criu.c
Remove redundant rootfs setup in restore function	Eliminate local rootfs variable and its append_paths call in restore Simplify restore mount loop to use status->rootfs directly	src/libcrun/criu.c

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[sourcery-ai]

Hey @kolyshkin - I've reviewed your changes and they look great!

Here's what I looked at during the review

• 🟢 General issues: all looks good
• 🟢 Security: all looks good
• 🟢 Testing: all looks good
• 🟢 Complexity: all looks good
• 🟢 Documentation: all looks good

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[packit-as-a-service]

TMT tests failed. @containers/packit-build please check.

[giuseppe]

LGTM

[lsm5]

podman checkpoint tests pass. So, LGTM from me.

[lsm5]

Looks like centos stream 10 has issues with criu. I remember we've had issues with criu in the past on centos targets. Maybe we can ignore it here and I'll remove centos job in another PR.

[lsm5]

/packit retest-failed

[packit-as-a-service]

Account lsm5 has no write access nor is author of PR!

[lsm5]

Looks like centos stream 10 has issues with criu.

It's only x86_64 failing, so let me know how you'd prefer to deal with that. I don't have access to retry the failed test.

[giuseppe]

Looks like centos stream 10 has issues with criu.

It's only x86_64 failing, so let me know how you'd prefer to deal with that. I don't have access to retry the failed test.

does not look like a flake, I've retried it

[lsm5]

I suggest we get this PR in asap as that would make CI green in podman and some other places where I'm trying to get revdep testing with podman. Maybe the cs10 test failure can be done elsewhere? I'd be happy to disable it for the time being if that helps.