The rootfs was a virtiofs share over an extracted tree, and that
showed: the tree's owners were the host user's, because an
unprivileged extract cannot chown to a tar's uid, and every chown
inside the machine failed with EPERM against the host side.
The rootfs crosses as a raw ext4 image now. mke2fs builds the cache
image straight from the entry tarball (-d takes gz, xz and zst, and
bakes each entry's recorded uid, gid and mode), the run copies it
into a scratch directory with cp --reflink=auto --sparse=auto, and
the engine attaches it with krun_add_disk +
krun_set_root_disk_remount; the init blob mounts /dev/vda at / and
chroots. The OCI layer bundle merges into one plain tar first, with
whiteouts applied across layers and headers passed verbatim, so
registry images keep their ownership too.
Per-run provisioning rides debugfs: the generated init lands at
/ecrou-init, the host resolver overwrites /etc/resolv.conf (unlink
first - resolver-bearing images ship it as a symlink), a stale
control file goes. The exit-code control file now outranks the
machine child's exit code: with a block root the engine's exit-code
channel (an ioctl through the virtiofs root device) never fires, so
decode_status reads the file first and treats the child's code as
machinery talk. Shell detection and the rare control-file read are
debugfs stats, no extracted tree to walk.
extract.rs keeps what the image build consumes (the tar decoder and
the OCI merge) and drops the extraction-to-disk path it once carried;
the module is private now. The engine needs the blk feature from here
on: the snap and the CI engine build follow in their own commits.
vm.rs composed run options and supervised the machine process in
one file. The process half moves out: the fork that enters the VM
loop, the console relay, the wait and exit-status decode, and the
termios save/restore. run_prepared keeps the composition and calls
into the new module. No behavior change.
rootfs.rs mixed the cache lifecycle with the tree-to-tarball
writer that persisting relies on. The packer moves to pack.rs
beside extract.rs: pack_rootfs becomes crate-internal, its
partial-cleanup test moves with it. No behavior change.
download.rs carried two clients in one file: the plain transfer
plumbing and a full OCI Distribution Spec client (token auth,
manifest lists, layer blobs). The registry half moves to its own
module; download.rs keeps hashing, checksum files and file
transfers. fetch_oci_digest moves with it; rootfs imports it from
the new home. No behavior change.
The founding rule restated SPEC.md, which stays the source of truth
for the confinement budget. Commit bodies gain a length cap, and a
commit must build and work on its own; bisectability outranks the
one-component-per-commit split when the two collide.
vhaudiquet
Valentin Haudiquet