feat(fs): use same walker for slow and fast modes

[lebauce]

Description

filepath.WalkDir doesn't follow symlink which makes it impossible to use it to walk through /proc/12345/root This PR changes the current walker to:

• handle top directory symlink
• use same walker for both slow and fast paths for consistency

PR's were push upstream but the project (https://github.com/saracen/walker) seems dead.

Other options would be to import the code (into pkg/utils/fsutils ?) or have the fork under the aqua org.

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Checklist

• I've read the guidelines for contributing to this repository.
• I've followed the conventions in the PR title.
• I've added tests that prove my fix is effective or that my feature works.
• I've updated the documentation with the relevant information (if needed).
• I've added usage information (if the PR introduces new options)
• I've included a "before" and "after" example to the description (if the PR is a user interface change).

[lebauce]

@knqyf263 Sorry, I know that you are pretty busy but if you or someone else from the team could have a look at this one, that would be very much appreciated. Thanks !

[knqyf263]

I'm sorry for the late reply. We already have a PR. Does it meet your requirements?

[lebauce]

I'm sorry for the late reply

No problem !

Does it meet your requirements?

Unfortunately no :-/
My use case is the following one : being able to scan the filesystem of a container through /proc/1234/root , which is a "somehow magic" symlink and therefore not supported by the Golang walker who ignores all the symlink including the top one.
One approach would be to handle the root directory "manually" and use the walker only for the subdirectories of this root directory. I can try to add a PR on top of yours.

[github-actions]

This PR is stale because it has been labeled with inactivity.

[knqyf263]

We've finally merged #5180. If your use-case benefits the community, we'd accept it. If not, the walker is now an interface, and you can overwrite it on your end.
https://github.com/knqyf263/trivy/blob/e8190608d6f0f29c873ba8d43c529968f1149843/pkg/fanal/artifact/local/fs.go#L36-L38