Hello @simonoff - I didn't see this issue before submitting #142, but that request is relevant to your concern here. (It's not a refactor or a full solution, but it resolves the data corruption issue when modifying existing archives where the central directory entry size doesn't match the local entry size.)

Hi @jstanley0 - Yes, it's bug in what local and central entries has a different sizes. I will working on getting extra for local and central directory as different entries and merge them and after using different methods to write local and central entries. Current code has a some things about it but if extra is unknown then it will be a corrupted archive.

Closing this because I think we do handle unknown extra fields now - and #459 fixed loading extra fields from both central directory and local headers.