Add checkpointExtra and checkpointOptsExtra.

PiperOrigin-RevId: 823273040

Author: ayushr2

runsc/cmd/BUILD

@@ -37,6 +37,7 @@ go_library(
         "boot_impl.go",
         "capability.go",
         "checkpoint.go",
+        "checkpoint_impl.go",
         "chroot.go",
         "cmd.go",
         "cpu_features.go",

runsc/cmd/checkpoint.go

@@ -45,6 +45,8 @@ type Checkpoint struct {
 	// For example, if the checkpoint files will be stored on a network block
 	// device, which will be detached after the checkpoint is done.
 	direct bool
+
+	checkpointExtra
 }
 
 // Name implements subcommands.Command.Name.
@@ -75,6 +77,7 @@ func (c *Checkpoint) SetFlags(f *flag.FlagSet) {
 	// Unimplemented flags necessary for compatibility with docker.
 	var wp string
 	f.StringVar(&wp, "work-path", "", "ignored")
+	c.setFlagsExtra(f)
 }
 
 // Execute implements subcommands.Command.Execute.
@@ -109,6 +112,7 @@ func (c *Checkpoint) Execute(_ context.Context, f *flag.FlagSet, args ...any) su
 		SaveRestoreExecTimeout:     c.saveRestoreExecTimeout,
 		SaveRestoreExecContainerID: id,
 	}
+	c.setCheckpointOptsExtra(&opts)
 
 	if err := cont.Checkpoint(conf, c.imagePath, opts); err != nil {
 		util.Fatalf("checkpoint failed: %v", err)

runsc/cmd/checkpoint_impl.go

@@ -0,0 +1,29 @@
+// Copyright 2025 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build !false
+// +build !false
+
+package cmd
+
+import (
+	"gvisor.dev/gvisor/runsc/flag"
+	"gvisor.dev/gvisor/runsc/sandbox"
+)
+
+type checkpointExtra struct{}
+
+func (c *Checkpoint) setFlagsExtra(f *flag.FlagSet) {}
+
+func (c *Checkpoint) setCheckpointOptsExtra(opts *sandbox.CheckpointOpts) {}

runsc/sandbox/sandbox.go

@@ -1516,6 +1516,8 @@ type CheckpointOpts struct {
 	SaveRestoreExecArgv        string
 	SaveRestoreExecTimeout     time.Duration
 	SaveRestoreExecContainerID string
+
+	checkpointOptsExtra
 }
 
 // Checkpoint sends the checkpoint call for a container in the sandbox.

runsc/sandbox/sandbox_impl.go

@@ -30,6 +30,8 @@ func createSandboxProcessExtra(conf *config.Config, args *Args, cmd *exec.Cmd, d
 	return nil
 }
 
+type checkpointOptsExtra struct{}
+
 func setCheckpointOptsImpl(conf *config.Config, imagePath string, opts CheckpointOpts, opt *control.SaveOpts) error {
 	return setCheckpointOptsForLocalCheckpointFiles(conf, imagePath, opts, opt)
 }