This format is pretty much the same as the "bare" format, except the
file ownership and xattrs is not stored in the actual filesystem object, but
rather on the side in a user xattr. This means two things:
1) An unprivileged user can store such a repo independent of the types
of files in it or their xattrs. And you can later (as root)
reconstruct the real filesystem tree with ownership. Although you
can't do that using hardlink-sharing. This also means ostree
fsck does a full verification.
2) Such a repository can be checked out with user-mode (checkout -U)
as an unprivileged user using hardlinks for space sharing.
Additionally, symlinks are stored as regular files (with the content
being the symlink target) because user xattrs are not supported on
symlinks. We know at checkout time if the file is a symlink because
the original st_mode is stored in the xattr metadata.
https://bugzilla.gnome.org/show_bug.cgi?id=741125
Applying xattrs on a symlink during checkout failed since
it was setting the xattrs on the final filename, not the
temporary name.
This made the "checkout union 1" test in test-basic.sh
fail.
https://bugzilla.gnome.org/show_bug.cgi?id=741125
When commiting a symlink we do store the uid/gid of the actual
symlink (i.e. not target). However, this was not restored
on non-user-mode checkout as it should.
This commit fixes that, and additionally it ensures xattrs
on symlinks are not set in user-mode checkout.
https://bugzilla.gnome.org/show_bug.cgi?id=741125
Alexander Larsson