96 lines
3.0 KiB
Go
96 lines
3.0 KiB
Go
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// Copyright 2018 Google Inc.
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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 "gvisor.googlesource.com/gvisor/pkg/sentry/context"
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// overlayMountSourceOperations implements MountSourceOperations for an overlay
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// mount point.
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type overlayMountSourceOperations struct {
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upper *MountSource
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lower *MountSource
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}
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func newOverlayMountSource(upper, lower *MountSource, flags MountSourceFlags) *MountSource {
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upper.IncRef()
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lower.IncRef()
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return NewMountSource(&overlayMountSourceOperations{
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upper: upper,
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lower: lower,
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}, &overlayFilesystem{}, flags)
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}
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// Revalidate panics if the upper or lower MountSource require that dirent be
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// revalidated. Otherwise always returns false.
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func (o *overlayMountSourceOperations) Revalidate(dirent *Dirent) bool {
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if o.upper.Revalidate(dirent) || o.lower.Revalidate(dirent) {
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panic("an overlay cannot revalidate file objects")
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}
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return false
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}
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// Keep returns true if either upper or lower MountSource require that the
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// dirent be kept in memory.
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func (o *overlayMountSourceOperations) Keep(dirent *Dirent) bool {
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return o.upper.Keep(dirent) || o.lower.Keep(dirent)
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}
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// ResetInodeMappings propagates the call to both upper and lower MountSource.
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func (o *overlayMountSourceOperations) ResetInodeMappings() {
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o.upper.ResetInodeMappings()
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o.lower.ResetInodeMappings()
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}
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// SaveInodeMapping propagates the call to both upper and lower MountSource.
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func (o *overlayMountSourceOperations) SaveInodeMapping(inode *Inode, path string) {
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inode.overlay.copyMu.RLock()
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defer inode.overlay.copyMu.RUnlock()
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if inode.overlay.upper != nil {
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o.upper.SaveInodeMapping(inode.overlay.upper, path)
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}
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if inode.overlay.lower != nil {
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o.lower.SaveInodeMapping(inode.overlay.lower, path)
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}
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}
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// Destroy drops references on the upper and lower MountSource.
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func (o *overlayMountSourceOperations) Destroy() {
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o.upper.DecRef()
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o.lower.DecRef()
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}
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// type overlayFilesystem is the filesystem for overlay mounts.
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type overlayFilesystem struct{}
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// Name implements Filesystem.Name.
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func (ofs *overlayFilesystem) Name() string {
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return "overlayfs"
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}
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// Flags implements Filesystem.Flags.
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func (ofs *overlayFilesystem) Flags() FilesystemFlags {
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return 0
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}
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// AllowUserMount implements Filesystem.AllowUserMount.
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func (ofs *overlayFilesystem) AllowUserMount() bool {
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return false
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}
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// Mount implements Filesystem.Mount.
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func (ofs *overlayFilesystem) Mount(ctx context.Context, device string, flags MountSourceFlags, data string) (*Inode, error) {
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panic("overlayFilesystem.Mount should not be called!")
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}
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