Worked on containers/container-libs to address a critical issue affecting permission correctness during archive extraction on BSD systems. Focused on backend development using Go, the work involved implementing a syscallMode translator that accurately maps Go’s higher-order FileMode bits to POSIX chmod equivalents. This solution preserved setuid and setgid bits during untar operations, preventing potential security vulnerabilities and ensuring reliable permission handling. Regression tests were added to safeguard against future regressions in BSD-specific code paths. The changes improved the security and reproducibility of tar and untar processes across CI and production environments, with minimal disruption to unrelated functionality.