This allows ostree-prepare-root outside of the initramfs context where the
real rootfs is already mounted at /. We can't use `mount --move` in this
case because we would be trying to move / into a subdirectory of itself.
Closes: #403
Approved by: cgwalters
...for simplicity. This way we don't need to keep concatenating
deploy_path to everything. We can just refer relative to the current
working directory.
We need to do this after bind-mounting it over itself otherwise our cwd
is still on the non-bind-mounted filesystem below.
Closes: #403
Approved by: cgwalters
Typically we have our ready made-up up root at
`/sysroot/ostree/deploy/.../` (`deploy_path`) and the real rootfs at
`/sysroot` (`root_mountpoint`). We want to end up with our made-up root
at `/sysroot/` and the real rootfs under `/sysroot/sysroot` as systemd
will be responsible for moving `/sysroot` to `/`.
We need to do this in 3 moves to avoid trying to move `/sysroot` under
itself:
1. `/sysroot/ostree/deploy/...` -> `/sysroot.tmp`
2. `/sysroot` -> `/sysroot.tmp/sysroot`
3. `/sysroot.tmp` -> `/sysroot`
This is a refactoring to group all these operations together so I can
implement an alternative in terms of `pivot_root`.
Closes: #403
Approved by: cgwalters
This supports running ostree on embedded platforms without an initrd.
Specificially I'm trying to do bringup on an NVidia Tegra based Jetson TK1
dev board.
Closes: #403
Approved by: cgwalters
These tests use unshare and mount to prepare a fake initrd/early boot
directory structure so we can then test ostree-prepare-root.
Things that are tested:
* Running in an initrd environment
* Running without initrd
* /var and /sysroot being mounted correctly
* /usr being mounted read-only
Things not tested (yet):
* Running as init - this could be accomplished by unsharing the pid
namespace too.
* mounting/unmounting `/proc` if `/proc/cmdline` isn't available
* Persistent overlayfs for `/usr`
* Probably other things
The tests are basic but can be extended in the future as we do more work
on `ostree-prepare-root`.
These tests must be run as root as they require the ability to `mount`
and to `unshare` the mount namespace. Perhaps in the future we can use
user namespaces for this test once they are more widely available.
Closes: #403
Approved by: cgwalters
William Manley