krun: fix error code

[eriksjolund]

Closes: #1963

[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 resolves an issue where the krun handler was reporting an uninformative error code when a virtual machine configuration failed. The change ensures that the underlying system error number (errno) is correctly captured and presented, which will significantly improve the diagnostic capabilities for krun VM setup failures.

Highlights

• Error Handling Fix: The error reporting mechanism in the libkrun_exec function has been updated to provide more accurate error codes. Instead of using a generic return value, the errno specific to the failure is now retrieved using crun_error_get_errno and passed to the error function.

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[gemini-code-assist]

Code Review

This pull request correctly fixes a bug in the krun handler where an incorrect error code was being reported upon failure of libkrun_configure_vm. Instead of using the return value of the function, which is not the errno, the change now correctly extracts the errno from the libcrun_error_t object. This ensures that the correct error information is propagated. I have one minor suggestion to improve code readability in the error handling block.

[gemini-code-assist]

The use of tmp_err can be a bit confusing given the multiple levels of pointer indirection involved with the error handling functions. To improve clarity, consider renaming tmp_err to something like err_p to more clearly indicate that it is a pointer to the err variable. This makes the code slightly easier to follow.

      libcrun_error_t *err_p = &err;
      libcrun_error_write_warning_and_release (NULL, &err_p);

[packit-as-a-service]

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

[giuseppe]

LGTM