run maps the flags onto RunOptions, promotes the first read-write share
to the workspace, inherits stdio, and exits with the guest's code; probe
reports what a run would find (KVM, libkrun loadability with the
remediation, nested virt, cache writability) and fails when a run
would. T6, the no-mount audit, lives here where the binary is built,
ignored behind ECROU_BIN for CI.
run() probes KVM, prepares the rootfs through the cache, generates the
guest init into the scratch, wires a libkrun context to it, and blocks
in krun_start_enter on this thread; the exit code comes back through
the control file, and a killed consumer kills the machine with the
process. Shares are validated and tagged in one place so the script and
the virtiofs setup stay ordered; anything overlapping the scratch
rootfs is refused, since the guest could otherwise rewrite its own
init. The guest environment is composed from scratch; the host
environment never crosses.
Generated into the scratch rootfs before boot: mounts each virtiofs
share (ro through the mount option), runs the payload as a child so the
init survives to write its exit code to the control file, then powers
off through sysrq, which works without a poweroff binary in the rootfs.
Shell quoting keeps payload argv and share paths free of interpolation.
Eleven calls from the stable-1.19.x headers plus krun_free_ctx, loaded
at runtime so a missing install names the remediation instead of failing
to link. Symbol lookup goes through a macro that carries the signature
from libkrun.h, every unsafe block states its invariant, and negative
returns map onto errno errors. The KVM probe ports ecr's open-then-
KVM_GET_API_VERSION check and reports KvmUnavailable with the full
remediation text.
ecrou's workspace starts from ecr's confinement-neutral half: image
reference resolution, the content cache with digest freshness, layer
extraction with whiteouts and deferred directory modes, provisioned
hot cells, and the progress/error/config plumbing. Adaptations: the
cache lives in ~/.cache/ecrou, the namespace-era error variants and
utils constants are gone, KvmUnavailable arrives ahead of its caller,
rootfs loses its exec() delegation, and uname(2) goes through libc
now that nix is no longer a dependency. The CLI crate is a stub until
its commit.
Valentin Haudiquet