fix: Make action paths compatible with both GitHub-hosted and self-hosted runners

[smockle]

Follow-up to #59 (which explains why copy steps and relative paths are used)

Fixes #71

Instead of assuming actions can be copied to /home/runner/work (a path which does not exist on some self-hosted runners), this PR uses $GITHUB_WORKSPACE/../.. (i.e. the directory above the workflow’s repo and owner directories, aka $RUNNER_TEMP/..). That is /home/runner/work on GitHub-hosted runners, but it might be /actions-runner/_work or /home/runner/_work (etc.) on self-hosted runners.

Additionally, this PR uses cp in place of rsync, since the latter is not installed on some self-hosted runners. It adds an rsync-like guard to avoid (errors due to) copying a file over itself.

I tested this branch’s:

• Top-level scanner action on a self-hosted runner: https://github.com/github/accessibility-sandbox/actions/runs/19862994002 (Hubber access only) (this run failed, but for reasons unrelated to paths)
• Top-level scanner action on a GitHub-hosted runner: https://github.com/github/accessibility-sandbox/actions/runs/19863037045 (Hubber access only)
• Nested gh-cache/* actions on a self-hosted runner: https://github.com/github/accessibility-sandbox/actions/runs/19863906871 (Hubber access only)
• Nested gh-cache/* actions on a GitHub-hosted runner: https://github.com/github/accessibility-sandbox/actions/runs/19863535680 (Hubber access only)

[Copilot]

Pull request overview

This PR enhances the accessibility-scanner action to work on both GitHub-hosted and self-hosted runners by replacing hardcoded runner paths with dynamic path resolution and switching from rsync to cp for better compatibility.

Key Changes:

• Dynamically determines the runner's work directory using GITHUB_WORKSPACE/../.. instead of hardcoding /home/runner/work
• Replaces rsync with cp -a for file copying operations to support runners without rsync installed
• Updates all action path references to include the full organization/repository path (github/accessibility-scanner) for consistency

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
action.yml	Updates the top-level action to use portable path resolution and includes the repository name in the action directory structure
.github/actions/gh-cache/cache/action.yml	Updates the nested cache action with the same portable path resolution and action reference updates

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[JoyceZhu]

@smockle just checking since I hadn't seen -a before (manpages say "Preserves structure and attributes of files but not directory structure"), is this intentional vs using something like -r to recursively copy everything?

[smockle]

Great question! cp -a includes -R; from https://www.gnu.org/software/coreutils/manual/html_node/cp-invocation.html#index-_002da-7:

…Equivalent to -dR --preserve=all with the reduced diagnostics.

If you’re familiar with rsync, rsync -a (archive) is similar.

[JoyceZhu]

ah oops, there we go -- misremembered the flag as lowercase -r!

[smockle]

POSIX cp only supports -R: https://pubs.opengroup.org/onlinepubs/9799919799/utilities/cp.html

GNU cp supports -R and -r: https://www.gnu.org/software/coreutils/manual/html_node/cp-invocation.html#index-_002dR-3

The latter doc explains the difference:

It is not portable to use -r to copy symbolic links or special files. On some non-GNU systems, -r implies the equivalent of -L and --copy-contents for historical reasons. Also, it is not portable to use -R to copy symbolic links unless you also specify -P, as POSIX allows implementations that dereference symbolic links by default.

Those differences aren’t enormously significant in our case: This repo doesn’t include symbolic links, and the ubuntu-latest runner’s cp supports both -R and -r. Regardless, our command (cp -a) is portable, because -a includes -d, and -d includes --no-dereference (aka -P).