1 files changed, 77 insertions, 0 deletions
diff --git a/pkg/sentry/fs/dirent_state.go b/pkg/sentry/fs/dirent_state.go
new file mode 100644
index 000000000..18652b809
--- /dev/null
+++ b/pkg/sentry/fs/dirent_state.go
@@ -0,0 +1,77 @@
+// Copyright 2018 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.
+
+package fs
+
+import (
+	"fmt"
+	"sync/atomic"
+
+	"gvisor.googlesource.com/gvisor/pkg/refs"
+)
+
+// beforeSave is invoked by stateify.
+func (d *Dirent) beforeSave() {
+	// Refuse to save if the file is on a non-virtual file system and has
+	// already been deleted (but still has open fds, which is why the Dirent
+	// is still accessible). We know the the restore re-opening of the file
+	// will always fail. This condition will last until all the open fds and
+	// this Dirent are closed and released.
+	//
+	// Such "dangling" open files on virtual file systems (e.g., tmpfs) is
+	// OK to save as their restore does not require re-opening the files.
+	//
+	// Note that this is rejection rather than failure---it would be
+	// perfectly OK to save---we are simply disallowing it here to prevent
+	// generating non-restorable state dumps. As the program continues its
+	// execution, it may become allowed to save again.
+	if !d.Inode.IsVirtual() && atomic.LoadInt32(&d.deleted) != 0 {
+		n, _ := d.FullName(nil /* root */)
+		panic(ErrSaveRejection{fmt.Errorf("deleted file %q still has open fds", n)})
+	}
+}
+
+// saveChildren is invoked by stateify.
+func (d *Dirent) saveChildren() map[string]*Dirent {
+	c := make(map[string]*Dirent)
+	for name, w := range d.children {
+		if rc := w.Get(); rc != nil {
+			// Drop the reference count obtain in w.Get()
+			rc.DecRef()
+
+			cd := rc.(*Dirent)
+			if cd.IsNegative() {
+				// Don't bother saving negative Dirents.
+				continue
+			}
+			c[name] = cd
+		}
+	}
+	return c
+}
+
+// loadChildren is invoked by stateify.
+func (d *Dirent) loadChildren(children map[string]*Dirent) {
+	d.children = make(map[string]*refs.WeakRef)
+	for name, c := range children {
+		d.children[name] = refs.NewWeakRef(c, nil)
+	}
+}
+
+// afterLoad is invoked by stateify.
+func (d *Dirent) afterLoad() {
+	if d.userVisible {
+		allDirents.add(d)
+	}
+}