cloned_binary: do not close file descriptor twice

[eriksjolund]

Closes: #2013

[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 a critical bug related to file descriptor handling within the clone_binary function. By refactoring the scope of a specific file descriptor, it prevents a double-close scenario that could cause instability or incorrect resource management. The change ensures that file descriptors are properly closed exactly once, improving the robustness of the binary cloning process.

Highlights

• File Descriptor Management: The binfd file descriptor, used for reading the current binary, was previously declared at the function scope with cleanup_close, leading to an implicit close. An explicit close(binfd) call was also present, causing a double-close issue.
• Scope Refactoring: The declaration of binfd has been moved into a new inner block scope. This ensures that the cleanup_close attribute correctly closes the file descriptor when execution leaves that specific block, eliminating the need for an explicit close() call and preventing the double-close.
• Bug Fix: This change resolves a bug where the binfd file descriptor could be closed twice, which could lead to undefined behavior or errors in the cloned_binary function.

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Changelog

• src/libcrun/cloned_binary.c
  • Removed the cleanup_close int binfd = -1; declaration from the main function scope.
  • Introduced a new inner block scope for binfd declaration, ensuring cleanup_close applies correctly.
  • Removed the explicit close(binfd); call, as it is now handled by the cleanup_close attribute upon exiting the new scope.

Activity

• The pull request was created to address issue file descriptor closed twice in cloned_binary() #2013, indicating a known problem with file descriptor handling.

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[gemini-code-assist]

Code Review

This pull request correctly resolves a double-close issue with a file descriptor by reducing the scope of the binfd variable and relying on the cleanup_close attribute for proper resource management. The change is logical and improves the robustness of the code. I have one minor suggestion regarding code style.

[packit-as-a-service]

Ephemeral COPR build failed. @containers/packit-build please check.

[packit-as-a-service]

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

[giuseppe]

I don't think we can call seal if there is an open fd.

It is safer to do:

close(binfd);
binfd = -1;

[giuseppe]

nevermind, I said something silly.

That is not a problem (and different fd)

[giuseppe]

LGTM