rsync can silently corrupt OS X files due to lack of extended attribute support

[ned-deily (Ned Deily)]

The MacPorts rsync lacks the Apple-specific modifications to support extended attribute and resource fork copy.

        -E, --extended-attributes   copy extended attributes, resource forks

vs

        -E, --executability         preserve executability

This is particularly nasty because at least one popular port (git-core) pulls in rsync as a dependency and -aE is a valid option in both versions of rsync. So, when users install git-core via MacPorts, they may not realize that rsync is also being installed and, if they use rsync to backup OS X files, they may not find out until it is too late that crucial HFS metadata (like resource forks and other extended attributes) were not copied as expected if the Apple rsync had been used.

I would think the best solution would be to forward port the Apple -E changes but, if that's not possible, there should be some other change, perhaps a warning when -E is selected. Or remove the dependency in git-core on rsync. As it stands, considering the popularity of rsync as a backup solution, it is way too easy for users to end up with silently corrupted files.