Prepare startContainer() to have more action

Currently startContainer() is used to create and to run a container.
In the next patch it will be used to restore a container.

Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

create.go

@@ -62,7 +62,7 @@ command(s) that get executed on start, edit the args parameter of the spec. See
 		if err != nil {
 			return err
 		}
-		status, err := startContainer(context, spec, true)
+		status, err := startContainer(context, spec, CT_ACT_CREATE, nil)
 		if err != nil {
 			return err
 		}

exec.go

@@ -135,6 +135,7 @@ func execProcess(context *cli.Context) (int, error) {
 		consoleSocket:   context.String("console-socket"),
 		detach:          detach,
 		pidFile:         context.String("pid-file"),
+		action:          CT_ACT_RUN,
 	}
 	return r.run(p)
 }

restore.go

@@ -5,13 +5,8 @@ package main
 import (
 	"fmt"
 	"os"
-	"syscall"
 
-	"github.com/Sirupsen/logrus"
 	"github.com/opencontainers/runc/libcontainer"
-	"github.com/opencontainers/runc/libcontainer/configs"
-	"github.com/opencontainers/runc/libcontainer/specconv"
-	"github.com/opencontainers/runtime-spec/specs-go"
 	"github.com/urfave/cli"
 )
 
@@ -92,111 +87,22 @@ using the runc checkpoint command.`,
 			return fmt.Errorf("runc restore requires root")
 		}
 
-		imagePath := context.String("image-path")
+		spec, err := setupSpec(context)
-		id := context.Args().First()
-		if id == "" {
-			return errEmptyID
-		}
-		if imagePath == "" {
-			imagePath = getDefaultImagePath(context)
-		}
-		bundle := context.String("bundle")
-		if bundle != "" {
-			if err := os.Chdir(bundle); err != nil {
-				return err
-			}
-		}
-		spec, err := loadSpec(specConfig)
 		if err != nil {
 			return err
 		}
-		config, err := specconv.CreateLibcontainerConfig(&specconv.CreateOpts{
+		options := criuOptions(context)
-			CgroupName:       id,
+		status, err := startContainer(context, spec, CT_ACT_RESTORE, options)
-			UseSystemdCgroup: context.GlobalBool("systemd-cgroup"),
-			NoPivotRoot:      context.Bool("no-pivot"),
-			Spec:             spec,
-		})
 		if err != nil {
 			return err
 		}
-		status, err := restoreContainer(context, spec, config, imagePath)
+		// exit with the container's exit status so any external supervisor is
-		if err == nil {
+		// notified of the exit with the correct exit status.
-			os.Exit(status)
+		os.Exit(status)
-		}
+		return nil
-		return err
 	},
 }
 
-func restoreContainer(context *cli.Context, spec *specs.Spec, config *configs.Config, imagePath string) (int, error) {
-	var (
-		rootuid = 0
-		rootgid = 0
-		id      = context.Args().First()
-	)
-	factory, err := loadFactory(context)
-	if err != nil {
-		return -1, err
-	}
-	container, err := factory.Load(id)
-	if err != nil {
-		container, err = factory.Create(id, config)
-		if err != nil {
-			return -1, err
-		}
-	}
-	options := criuOptions(context)
-
-	status, err := container.Status()
-	if err != nil {
-		logrus.Error(err)
-	}
-	if status == libcontainer.Running {
-		fatalf("Container with id %s already running", id)
-	}
-
-	setManageCgroupsMode(context, options)
-
-	if err = setEmptyNsMask(context, options); err != nil {
-		return -1, err
-	}
-
-	// ensure that the container is always removed if we were the process
-	// that created it.
-	detach := context.Bool("detach")
-	if !detach {
-		defer destroy(container)
-	}
-	process := &libcontainer.Process{}
-	tty, err := setupIO(process, rootuid, rootgid, false, detach, "")
-	if err != nil {
-		return -1, err
-	}
-
-	notifySocket := newNotifySocket(context, os.Getenv("NOTIFY_SOCKET"), id)
-	if notifySocket != nil {
-		notifySocket.setupSpec(context, spec)
-		notifySocket.setupSocket()
-	}
-
-	handler := newSignalHandler(!context.Bool("no-subreaper"), notifySocket)
-	if err := container.Restore(process, options); err != nil {
-		return -1, err
-	}
-	// We don't need to do a tty.recvtty because config.Terminal is always false.
-	defer tty.Close()
-	if err := tty.ClosePostStart(); err != nil {
-		return -1, err
-	}
-	if pidFile := context.String("pid-file"); pidFile != "" {
-		if err := createPidFile(pidFile, process); err != nil {
-			_ = process.Signal(syscall.SIGKILL)
-			_, _ = process.Wait()
-			return -1, err
-		}
-	}
-	return handler.forward(process, tty, detach)
-}
-
 func criuOptions(context *cli.Context) *libcontainer.CriuOpts {
 	imagePath := getCheckpointImagePath(context)
 	if err := os.MkdirAll(imagePath, 0655); err != nil {

run.go

@@ -73,7 +73,7 @@ command(s) that get executed on start, edit the args parameter of the spec. See
 		if err != nil {
 			return err
 		}
-		status, err := startContainer(context, spec, false)
+		status, err := startContainer(context, spec, CT_ACT_RUN, nil)
 		if err == nil {
 			// exit with the container's exit status so any external supervisor is
 			// notified of the exit with the correct exit status.

utils_linux.go

@@ -220,8 +220,9 @@ type runner struct {
 	pidFile         string
 	consoleSocket   string
 	container       libcontainer.Container
-	create          bool
+	action          CtAct
 	notifySocket    *notifySocket
+	criuOpts        *libcontainer.CriuOpts
 }
 
 func (r *runner) run(config *specs.Process) (int, error) {
@@ -253,12 +254,8 @@ func (r *runner) run(config *specs.Process) (int, error) {
 		return -1, err
 	}
 	var (
-		detach  = r.detach || r.create
+		detach = r.detach || (r.action == CT_ACT_CREATE)
-		startFn = r.container.Start
 	)
-	if !r.create {
-		startFn = r.container.Run
-	}
 	// Setting up IO is a two stage process. We need to modify process to deal
 	// with detaching containers, and then we get a tty after the container has
 	// started.
@@ -269,7 +266,18 @@ func (r *runner) run(config *specs.Process) (int, error) {
 		return -1, err
 	}
 	defer tty.Close()
-	if err = startFn(process); err != nil {
+
+	switch r.action {
+	case CT_ACT_CREATE:
+		err = r.container.Start(process)
+	case CT_ACT_RESTORE:
+		err = r.container.Restore(process, r.criuOpts)
+	case CT_ACT_RUN:
+		err = r.container.Run(process)
+	default:
+		panic("Unknown action")
+	}
+	if err != nil {
 		r.destroy()
 		return -1, err
 	}
@@ -313,7 +321,7 @@ func (r *runner) terminate(p *libcontainer.Process) {
 }
 
 func (r *runner) checkTerminal(config *specs.Process) error {
-	detach := r.detach || r.create
+	detach := r.detach || (r.action == CT_ACT_CREATE)
 	// Check command-line for sanity.
 	if detach && config.Terminal && r.consoleSocket == "" {
 		return fmt.Errorf("cannot allocate tty if runc will detach without setting console socket")
@@ -337,7 +345,15 @@ func validateProcessSpec(spec *specs.Process) error {
 	return nil
 }
 
-func startContainer(context *cli.Context, spec *specs.Spec, create bool) (int, error) {
+type CtAct uint8
+
+const (
+	CT_ACT_CREATE CtAct = iota + 1
+	CT_ACT_RUN
+	CT_ACT_RESTORE
+)
+
+func startContainer(context *cli.Context, spec *specs.Spec, action CtAct, criuOpts *libcontainer.CriuOpts) (int, error) {
 	id := context.Args().First()
 	if id == "" {
 		return -1, errEmptyID
@@ -372,7 +388,8 @@ func startContainer(context *cli.Context, spec *specs.Spec, create bool) (int, e
 		detach:          context.Bool("detach"),
 		pidFile:         context.String("pid-file"),
 		preserveFDs:     context.Int("preserve-fds"),
-		create:          create,
+		action:          action,
+		criuOpts:        criuOpts,
 	}
 	return r.run(&spec.Process)
 }