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// Copyright 2018 Google LLC
//
// 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)
}
}
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