I have a PHP app that creates a .zip folder out of files that are restricted to specific groups using ACL, then submits it to the user to download. Specifically, everyone is allowed to read them, but only some group names have read/write/etc.
This doesn't cause any problems on Windows that I've seen, but on OS X the Archive Utility doesn't seem to reset any ownership, which means the OS X user doesn't have Write access to the file by default unless they just 'happen' to be a member of a similarly named group.
Is there a way to fix this, either by forcing the AU to give the user access, or via something in PHP? I can gain access to individual files with Get Info, but I'm not the only user using the app.