container

type Backend struct {
	Log    *slog.Logger
	Layout Layout
	// RuntimePath is the runc executable (only runc is supported). Empty means
	// DefaultRuntimePath.
	RuntimePath string
	// CheckRuntime verifies the runtime executable exists before the unit is
	// started, so a missing runtime is a clear error instead of a unit systemd
	// quietly skips. Nil skips the check; the agent sets it.
	CheckRuntime func(path string) error
	// KernelRelease reports the running kernel's release string, for choosing
	// recursive read-only binds. Nil reads <SourceRoot>/proc/sys/kernel/osrelease;
	// an unknown kernel keeps plain "ro".
	KernelRelease func() string
	// HelperPath is the agent binary providing node-lifecycle hooks.
	HelperPath string
	// SystemdDir is where the unit is written. Empty means SystemdDir.
	SystemdDir string
	// Host is used by preflight and SELinux detection. Nil means DefaultHostFS.
	Host *HostFS
	// Run executes host commands. Nil uses executil.OutputCmd.
	Run Runner
	// Stream starts streaming commands (logs). Nil uses os/exec.
	Stream Streamer
	// Unpack materializes the rootfs. Nil requires the rootfs to exist already.
	Unpack Unpacker
	// StatDevice describes a granted device node. Nil stats the real device.
	StatDevice func(path string) (DeviceInfo, error)
	// MountInfoPath is read before removing a rootfs. Empty means /proc/self/mountinfo.
	MountInfoPath string
	// SourceRoot prefixes same-path source directories created by Prepare.
	// Empty means the real host root; tests use a temporary directory.
	SourceRoot string
	// WritableCheck overrides the writable path probe. Nil uses none.CheckWritable.
	WritableCheck func(paths ...string) error
	// RuntimeProvisioned tells Preflight that the agent installs the runtime
	// later in bootstrap, so a missing runtime file is expected on a clean host.
	// The runtime is still required to be executable when it is present.
	RuntimeProvisioned bool
	// RefreshGrants, when set, replaces the recorded grants at Regenerate. The
	// pre-start hook uses it to follow devices and driver libraries that a host
	// reboot or driver change moved since Prepare. It receives the grants
	// recorded by Prepare and returns the ones to render and record from now on.
	RefreshGrants func(ctx context.Context, recorded []isolation.Grant) ([]isolation.Grant, error)
	// UnitRequires lists host units the supervising unit requires and orders
	// after, such as the LocalDNS network unit.
	UnitRequires []string
	// GoneTimeout bounds how long Stop waits for the runtime to report the
	// container gone, before and again after killing it. Zero is
	// DefaultGoneTimeout.
	GoneTimeout time.Duration
	// PollInterval is the wait between runtime state checks. Zero is
	// DefaultPollInterval.
	PollInterval time.Duration
}

type BundleInput struct {
	// Slot selects the slot's bpffs and cgroup.
	Slot      string
	RootfsDir string
	SELinux   SELinuxMode
	Grants    []isolation.Grant
	// Devices maps a granted device path to its node description.
	Devices map[string]DeviceInfo
	// ExtraBinds are bound after the same-path mounts and before grants.
	ExtraBinds []ExtraBind
	// RecursiveReadOnly makes read-only binds "rro" instead of "ro". With "ro"
	// a recursive bind keeps its submounts writable. The runtime (runc 1.1) and
	// the kernel (5.12, mount_setattr) must both support it, so the backend sets
	// this only after checking them.
	RecursiveReadOnly bool
}

type DeviceInfo struct {
	Type  string // "c" or "b"
	Major int64
	Minor int64
	Mode  uint32
}

type ExtraBind struct {
	Source   string
	Target   string
	ReadOnly bool
}

type HostFS struct {
	// CgroupControllers exists only on a cgroup v2 unified hierarchy.
	CgroupControllers string
	// SELinuxEnforce holds "1" when enforcing and "0" when permissive. Absent
	// means SELinux is disabled.
	SELinuxEnforce string
	// SELinuxContext is the kernel's context validation interface. Writing a
	// context to it and reading it back fails when the type is unknown.
	SELinuxContext string
}

type Layout struct {
	// Base is the directory holding the slots. Empty means DefaultBase.
	Base string
}

type Root struct {
	SlotName string
	// Dir is the unpacked rootfs.
	Dir string
	// HostRoot prefixes the same-path host directories. Empty is the real host;
	// tests use a temporary tree.
	HostRoot string
}

type Runner = none.Runner

type SELinuxMode string

type SameMount struct {
	Path   string
	Shared bool // rshared propagation
}

type Streamer func(ctx context.Context, name string, args ...string) (io.ReadCloser, error)

type UnitSpec struct {
	Slot string
	// RuntimePath is the OCI runtime executable.
	RuntimePath string
	// BundleDir is the OCI bundle directory.
	BundleDir string
	// HelperPath is the agent binary that provides the node-lifecycle hooks.
	// Empty omits the hooks.
	HelperPath string
	// After lists host-global units to order after.
	After []string
	// Requires lists host-global units the container needs. Each is also
	// ordered before the container, as the nspawn machine's LocalDNS drop-in
	// does.
	Requires []string
}

type Unpacker func(ctx context.Context, n isolation.NodeSpec, dir string) error