Sets the restore environment for restoring a container.

Updated how restoring occurs through boot.go with a separate Restore function.
This prevents a new process and new mounts from being created.
Added tests to ensure the container is restored.
Registered checkpoint and restore commands so they can be used.
Docker support for these commands is still limited.
Working on #80.

PiperOrigin-RevId: 202710950
Change-Id: I2b893ceaef6b9442b1ce3743bd112383cb92af0c

1 files changed, 26 insertions, 1 deletions

diff --git a/pkg/sentry/fs/gofer/inode_state.go b/pkg/sentry/fs/gofer/inode_state.go
index 82d1dd4da..33ec33364 100644
--- a/pkg/sentry/fs/gofer/inode_state.go
+++ b/pkg/sentry/fs/gofer/inode_state.go
@@ -17,6 +17,7 @@ package gofer
 import (
 	"errors"
 	"fmt"
+	"path/filepath"
 	"strings"
 
 	"gvisor.googlesource.com/gvisor/pkg/p9"
@@ -77,6 +78,29 @@ func (i *inodeFileState) saveLoading() struct{} {
 	return struct{}{}
 }
 
+// splitAbsolutePath splits the path on slashes ignoring the leading slash.
+func splitAbsolutePath(path string) []string {
+	if len(path) == 0 {
+		panic("There is no path!")
+	}
+	if path != filepath.Clean(path) {
+		panic(fmt.Sprintf("path %q is not clean", path))
+	}
+	// This case is to return {} rather than {""}
+	if path == "/" {
+		return []string{}
+	}
+	if path[0] != '/' {
+		panic(fmt.Sprintf("path %q is not absolute", path))
+	}
+
+	s := strings.Split(path, "/")
+
+	// Since p is absolute, the first component of s
+	// is an empty string. We must remove that.
+	return s[1:]
+}
+
 // loadLoading is invoked by stateify.
 func (i *inodeFileState) loadLoading(_ struct{}) {
 	i.loading.Lock()
@@ -98,7 +122,8 @@ func (i *inodeFileState) afterLoad() {
 		// TODO: Context is not plumbed to save/restore.
 		ctx := &dummyClockContext{context.Background()}
 		var err error
-		_, i.file, err = i.s.attach.walk(ctx, strings.Split(name, "/"))
+
+		_, i.file, err = i.s.attach.walk(ctx, splitAbsolutePath(name))
 		if err != nil {
 			return fmt.Errorf("failed to walk to %q: %v", name, err)
 		}