cgroup: preserve errno on errors in rmdir_all_fd

[giuseppe]

Closes: #2048

[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a bug in the rmdir_all_fd function where the errno value was not properly preserved after a failed openat call. By saving and restoring errno, the change ensures that subsequent error checks accurately reflect the original cause of failure during cgroup directory removal, improving the reliability of error reporting.

Highlights

• Error Handling: Modified the rmdir_all_fd function to correctly preserve the errno value when openat fails, ensuring accurate error reporting during cgroup cleanup.

🧠 New Feature in Public Preview: You can now enable Memory to help Gemini Code Assist learn from your team's feedback. This makes future code reviews more consistent and personalized to your project's style. Click here to enable Memory in your admin console.

Changelog

• src/libcrun/cgroup-utils.c
  • Preserved errno when openat fails in rmdir_all_fd.
  • Closed the directory stream (dir) before returning on openat failure.

Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point by creating a comment using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands on the current page.

Feature	Command	Description
Code Review	/gemini review	Performs a code review for the current pull request in its current state.
Pull Request Summary	/gemini summary	Provides a summary of the current pull request in its current state.
Comment	@gemini-code-assist	Responds in comments when explicitly tagged, both in pull request comments and review comments.
Help	/gemini help	Displays a list of available commands.

Customization

To customize Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counter productive. You can react with 👍 and 👎 on @gemini-code-assist comments. If you're interested in giving your feedback about your experience with Gemini Code Assist for GitHub and other Google products, sign up here.

You can also get AI-powered code generation, chat, as well as code reviews directly in the IDE at no cost with the Gemini Code Assist IDE Extension.

Footnotes

1. Review the Privacy Notices, Generative AI Prohibited Use Policy, Terms of Service, and learn how to configure Gemini Code Assist in GitHub here. Gemini can make mistakes, so double check it and use code with caution. ↩

[gemini-code-assist]

Code Review

This pull request effectively addresses a critical issue in rmdir_all_fd by ensuring that the errno value from openat failures is preserved. The changes correctly save and restore errno before calling closedir, preventing potential overwrites of the original error code. Additionally, the explicit closing of the directory stream and nulling of the dir pointer enhance resource management and prevent unintended behavior.

[gemini-code-assist]

The introduction of saved_errno and its restoration after closedir is crucial. Without this, a failure in closedir could overwrite the original errno from openat, leading to misleading error reports for the rmdir_all_fd function's caller. This change ensures accurate error propagation.

[gemini-code-assist]

Closing the dir stream and explicitly setting it to NULL after use is important for robust resource management. This prevents potential issues like double-closing or use-after-free, especially if dir is a cleanup_dir variable.