runv: implement pause and resume

Implement the pause and resume commands of OCI. According to
the spec, pause suspends all processes in the container, and
resume resumes them.

Signed-off-by: Antonios Motakis <antonios.motakis@huawei.com>

Author: tvelocity

main.go

@@ -159,6 +159,8 @@ func main() {
 		stateCommand,
 		manageCommand,
 		shimCommand,
+		pauseCommand,
+		resumeCommand,
 		containerd.ContainerdCommand,
 	}
 	if err := app.Run(os.Args); err != nil {

pause.go

@@ -0,0 +1,79 @@
+package main
+
+import (
+	"fmt"
+	"path/filepath"
+
+	"github.com/hyperhq/runv/containerd/api/grpc/types"
+	"github.com/hyperhq/runv/lib/linuxsignal"
+	"github.com/urfave/cli"
+	netcontext "golang.org/x/net/context"
+)
+
+var pauseCommand = cli.Command{
+	Name:      "pause",
+	Usage:     "suspend all processes in the container",
+	ArgsUsage: `<container-id>`,
+	Action: func(context *cli.Context) error {
+		container := context.Args().First()
+		if container == "" {
+			return cli.NewExitError(fmt.Sprintf("container id cannot be empty"), -1)
+		}
+
+		c, err := getClient(filepath.Join(context.GlobalString("root"), container, "namespace/namespaced.sock"))
+		if err != nil {
+			return cli.NewExitError(fmt.Sprintf("failed to get client: %v", err), -1)
+		}
+
+		plist, err := getProcessList(c, container)
+		if err != nil {
+			return cli.NewExitError(fmt.Sprintf("can't get process list, %v", err), -1)
+		}
+
+		for _, p := range plist {
+			if _, err := c.Signal(netcontext.Background(), &types.SignalRequest{
+				Id:     container,
+				Pid:    p,
+				Signal: uint32(linuxsignal.SIGSTOP),
+			}); err != nil {
+				return cli.NewExitError(fmt.Sprintf("suspend signal failed, %v", err), -1)
+			}
+		}
+
+		return nil
+	},
+}
+
+var resumeCommand = cli.Command{
+	Name:      "resume",
+	Usage:     "resume all processes in the container",
+	ArgsUsage: `<container-id>`,
+	Action: func(context *cli.Context) error {
+		container := context.Args().First()
+		if container == "" {
+			return cli.NewExitError(fmt.Sprintf("container id cannot be empty"), -1)
+		}
+
+		c, err := getClient(filepath.Join(context.GlobalString("root"), container, "namespace/namespaced.sock"))
+		if err != nil {
+			return cli.NewExitError(fmt.Sprintf("failed to get client: %v", err), -1)
+		}
+
+		plist, err := getProcessList(c, container)
+		if err != nil {
+			return cli.NewExitError(fmt.Sprintf("can't get process list, %v", err), -1)
+		}
+
+		for _, p := range plist {
+			if _, err := c.Signal(netcontext.Background(), &types.SignalRequest{
+				Id:     container,
+				Pid:    p,
+				Signal: uint32(linuxsignal.SIGCONT),
+			}); err != nil {
+				return cli.NewExitError(fmt.Sprintf("resume signal failed, %v", err), -1)
+			}
+		}
+
+		return nil
+	},
+}