Merge pull request #2830 from Ace-Tang/support_cr_without_image

cr: support checkpoint/restore without image

runtime/v1/shim/service.go

@@ -448,6 +448,7 @@ func (s *Service) Checkpoint(ctx context.Context, r *shimapi.CheckpointTaskReque
 		AllowTerminal:            options.Terminal,
 		FileLocks:                options.FileLocks,
 		EmptyNamespaces:          options.EmptyNamespaces,
+		WorkDir:                  options.WorkPath,
 	}); err != nil {
 		return nil, errdefs.ToGRPC(err)
 	}
@@ -657,5 +658,11 @@ func newInit(ctx context.Context, path, workDir, runtimeRoot, namespace, criu st
 	p.IoGID = int(options.IoGid)
 	p.NoPivotRoot = options.NoPivotRoot
 	p.NoNewKeyring = options.NoNewKeyring
+	p.CriuWorkPath = options.CriuWorkPath
+	if p.CriuWorkPath == "" {
+		// if criu work path not set, use container WorkDir
+		p.CriuWorkPath = p.WorkDir
+	}
+
 	return p, nil
 }