Add ecr::rootfs with the full rootfs lifecycle behind the library:
- RootfsCache::prepare resolves an image reference, downloads through
the tarball cache (with the OCI :latest digest freshness check) and
extracts into a scratch directory tracked by PreparedRootfs.
- PreparedRootfs::persist packs the current rootfs back into its cache
entry (compressed to match the entry's extension, symlinks and
permissions preserved) and marks it with a .provisioned sidecar.
- RootfsCache::prepare_provisioned composes both into the hot-cell
flow: provision once, and every later call sharing the cache skips
the download and the provisioning step.
extract: an "oci-" cache entry without a layers.manifest is a
persisted provisioned rootfs; extract it as a plain archive.
The CLI now drives prepare and drops its inline cache/orchestration
code and the dirs/tempfile dependencies. The binfmt check moves ahead
of the download so foreign-arch runs fail before pulling an image.
The root package becomes a virtual workspace: `crates/ecr` holds the
library (package name `ecr`) and `crates/ecr-cli` the command line
front-end, which keeps installing the `ecr` binary. No behavior change.
The library must not depend on CLI types, so mount::setup_mounts now
takes the `no_bind` flag instead of a `&Args`.
- hard links in the rootfs were written as zero-size entries with no
inode set (all zero), so the kernel could link them to the wrong file;
assign a synthetic inode per (device, inode) group.
- build the cpio archive by streaming entries to disk instead of holding
the whole archive in memory.
- the VM command was joined into a single string and shell-expanded in
the guest, mangling quotes and nested commands; pass the argv
base64-encoded (ECR_ARGV) and exec it verbatim.
- parse ecr parameters from /proc/cmdline in the init script, set the
hostname via procfs (arch has no hostname binary), and give the serial
console a moment to drain before poweroff.
Add --kernel <PATH> option to boot extracted rootfs in a QEMU virtual
machine instead of namespace/chroot mode. The rootfs is converted to an
ext4 disk image using mke2fs and booted with the provided kernel.
vhaudiquet