proc

type Backend struct {
	// contains filtered or unexported fields
}

type Dumped struct {
	// PID is the tree's root as the host sees it.
	PID int
	// Zygote is the warm instance's process as the host sees it, the
	// container's init. It is PID itself when the zygote is dumped.
	Zygote int
	// Workspace says the tree is a fiber with a mount namespace of its
	// own, a copy of the zygote's, that holds its workspace at
	// backend.WorkspaceMount.
	Workspace bool
}

type Inherit struct {
	Key  string
	File *os.File
}

type Launcher interface {
	// Name is the backend name this launcher gives the fork backend.
	Name() string
	// Command builds the command that starts argv as the warm instance
	// for spec with ctl as its fd 3, logging to logf. It is exec'd by the
	// backend inside spec's cgroup.
	Command(spec backend.WarmSpec, argv []string, ctl, logf *os.File) (*exec.Cmd, error)
	// Channel is the control channel to speak to the started instance
	// on, given boot, the host's end of the pair Command was handed.
	// A launcher whose instance lives in a network namespace of its own
	// makes a pair there and hands the instance its end over boot, so the
	// instance can be checkpointed holding it. Returning boot keeps it.
	Channel(ctx context.Context, spec backend.WarmSpec, cmd *exec.Cmd, boot *net.UnixConn) (*net.UnixConn, error)
	// Socketpair makes a unix pair a fiber forked from the instance can
	// be checkpointed with, its channel. pid is the instance as the host
	// sees it.
	Socketpair(spec backend.WarmSpec, pid int, typ int) ([2]int, error)
	// PID is the zygote process itself (the container's init) once
	// Command has started, as the host sees it.
	PID(ctx context.Context, spec backend.WarmSpec, cmd *exec.Cmd) (int, error)
	// Restored is told of every tree of spec's grant criu brought back,
	// rooted at pid as the host sees it, for what the restored
	// namespaces still need.
	Restored(spec backend.WarmSpec, pid int) error
	// RestoredGone is told once for every RestoreExtra, when the restore
	// failed or when the restored tree has exited, so what RestoreExtra
	// made for it on this home can go.
	RestoredGone(spec backend.WarmSpec)
	// Release ends whatever Command created besides the process.
	Release(spec backend.WarmSpec)
	// Endpoint maps a host path in spec.WorkDir to where the zygote sees
	// it (the run directory is bind-mounted into its namespace).
	Endpoint(spec backend.WarmSpec, hostPath string) string
	// DumpExtra and RestoreExtra are criu arguments for a tree that
	// lives inside the launcher's namespaces. Both are given the image
	// directory. DumpExtra is told which tree is dumped and may record
	// beside the images what its restore will need to know. RestoreExtra
	// may have to make what the restore needs on this home first (a root
	// filesystem for a grant it never warmed, images the restored tree's
	// own identity may read), and may hand the tree files of this home
	// in place of ones its images name. The backend numbers those and
	// closes them once criu has them.
	DumpExtra(spec backend.WarmSpec, dir string, d Dumped) ([]string, error)
	RestoreExtra(spec backend.WarmSpec, dir string) ([]string, []Inherit, error)
}

type Options struct {
	// CRIU names the criu binary (default "criu").
	CRIU string
	// CRIUWrap is a command `criu restore` runs through, with criu's
	// argv after its own (criu.Options.Wrap). A launcher whose restores
	// need mounts of their own sets it.
	CRIUWrap []string
	// Launcher, when set, starts the zygote some other way than a plain
	// exec: inside an OCI container (pkg/backend/runc). Fibers are still
	// forked by the zygote over the control socket, checkpointed with
	// criu and computed as deltas; the launcher supplies what criu needs
	// to dump and restore trees that live in its namespaces.
	Launcher Launcher
	// RootBind is where the host's / is bind-mounted as the root of a
	// restored fiber's mount namespace, on the first resume that needs it
	// (default fiberd-root-<pid> under the temp directory). Every later
	// fiber unmounts it from its own namespace, because the bind would show
	// what HIDE covers, and a zygote of any other home drops it as a bind
	// of /. The backend makes the leaf directory and removes it
	// at Close, so its parent must be a place only fiberd writes. It
	// refuses a symlink or another user's directory there, and unmounts a
	// stale bind at the same path when it opens.
	RootBind string
	// Commander runs criu (criu.Options.Commander). Nil runs the binary
	// CRIU names.
	Commander criu.Commander
	// Borrow takes a duplicate of descriptor fd of process pid, as
	// pidfd_getfd(2) does, which a park and a resume use to reach the
	// fiber's channel. Nil is that system call, and a test sets one that
	// hands out ends of pairs of its own.
	Borrow func(pid, fd int) (*os.File, error)
	// Signal sends sig to process pid, which a park uses to ask the
	// fiber to stop serving. Nil is kill(2), and a test sets one that
	// records the signal.
	Signal func(pid int, sig syscall.Signal) error
	// contains filtered or unexported fields
}