linux: do not use errno after successful calls

[eriksjolund]

No description provided.

[gemini-code-assist]

Summary of Changes

Hello @eriksjolund, 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 an issue in the libcrun library where the errno global variable was being misused. The change ensures that application-specific errors, such as invalid input parsing, do not incorrectly report system error codes, leading to more accurate error reporting and preventing misleading error messages.

Highlights

• Fixing errno usage: Corrected an instance where 'errno' was incorrectly used as an error code in 'crun_make_error' when handling invalid mount options. The 'errno' variable should only be used after a system call or library function indicates a failure, not for application-level validation errors.

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[gemini-code-assist]

Code Review

This pull request correctly fixes a bug in error handling within parse_idmapped_mount_option. The original code used the errno variable when creating an error for an invalid mapping string. However, this check is a logical validation, and no system call that sets errno on failure precedes it. This could lead to misleading error messages containing a stale error code from a previous, unrelated operation. By changing errno to 0, the error is correctly reported as a logical failure without an associated system error code. This is the right approach and improves the robustness of error reporting. The change is correct and I approve it.

[packit-as-a-service]

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

[giuseppe]

LGTM