78 lines
2.4 KiB
Go
78 lines
2.4 KiB
Go
// Copyright 2018 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package fs
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import (
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"fmt"
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"sync/atomic"
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"gvisor.dev/gvisor/pkg/refs"
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)
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// beforeSave is invoked by stateify.
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func (d *Dirent) beforeSave() {
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// Refuse to save if the file is on a non-virtual file system and has
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// already been deleted (but still has open fds, which is why the Dirent
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// is still accessible). We know the the restore re-opening of the file
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// will always fail. This condition will last until all the open fds and
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// this Dirent are closed and released.
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//
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// Such "dangling" open files on virtual file systems (e.g., tmpfs) is
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// OK to save as their restore does not require re-opening the files.
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//
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// Note that this is rejection rather than failure---it would be
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// perfectly OK to save---we are simply disallowing it here to prevent
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// generating non-restorable state dumps. As the program continues its
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// execution, it may become allowed to save again.
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if !d.Inode.IsVirtual() && atomic.LoadInt32(&d.deleted) != 0 {
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n, _ := d.FullName(nil /* root */)
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panic(ErrSaveRejection{fmt.Errorf("deleted file %q still has open fds", n)})
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}
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}
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// saveChildren is invoked by stateify.
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func (d *Dirent) saveChildren() map[string]*Dirent {
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c := make(map[string]*Dirent)
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for name, w := range d.children {
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if rc := w.Get(); rc != nil {
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// Drop the reference count obtain in w.Get()
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rc.DecRef()
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cd := rc.(*Dirent)
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if cd.IsNegative() {
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// Don't bother saving negative Dirents.
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continue
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}
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c[name] = cd
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}
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}
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return c
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}
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// loadChildren is invoked by stateify.
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func (d *Dirent) loadChildren(children map[string]*Dirent) {
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d.children = make(map[string]*refs.WeakRef)
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for name, c := range children {
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d.children[name] = refs.NewWeakRef(c, nil)
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}
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}
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// afterLoad is invoked by stateify.
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func (d *Dirent) afterLoad() {
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if d.userVisible {
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allDirents.add(d)
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}
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}
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