93 lines
2.9 KiB
Go
93 lines
2.9 KiB
Go
// Copyright 2020 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 genericfstree provides tools for implementing vfs.FilesystemImpls
|
|
// where a single statically-determined lock or set of locks is sufficient to
|
|
// ensure that a Dentry's name and parent are contextually immutable.
|
|
//
|
|
// Clients using this package must use the go_template_instance rule in
|
|
// tools/go_generics/defs.bzl to create an instantiation of this template
|
|
// package, providing types to use in place of Dentry.
|
|
package genericfstree
|
|
|
|
import (
|
|
"gvisor.dev/gvisor/pkg/fspath"
|
|
"gvisor.dev/gvisor/pkg/sentry/vfs"
|
|
)
|
|
|
|
// Dentry is a required type parameter that is a struct with the given fields.
|
|
//
|
|
// +stateify savable
|
|
type Dentry struct {
|
|
// vfsd is the embedded vfs.Dentry corresponding to this vfs.DentryImpl.
|
|
vfsd vfs.Dentry
|
|
|
|
// parent is the parent of this Dentry in the filesystem's tree. If this
|
|
// Dentry is a filesystem root, parent is nil.
|
|
parent *Dentry
|
|
|
|
// name is the name of this Dentry in its parent. If this Dentry is a
|
|
// filesystem root, name is unspecified.
|
|
name string
|
|
}
|
|
|
|
// IsAncestorDentry returns true if d is an ancestor of d2; that is, d is
|
|
// either d2's parent or an ancestor of d2's parent.
|
|
func IsAncestorDentry(d, d2 *Dentry) bool {
|
|
for d2 != nil { // Stop at root, where d2.parent == nil.
|
|
if d2.parent == d {
|
|
return true
|
|
}
|
|
if d2.parent == d2 {
|
|
return false
|
|
}
|
|
d2 = d2.parent
|
|
}
|
|
return false
|
|
}
|
|
|
|
// ParentOrSelf returns d.parent. If d.parent is nil, ParentOrSelf returns d.
|
|
func ParentOrSelf(d *Dentry) *Dentry {
|
|
if d.parent != nil {
|
|
return d.parent
|
|
}
|
|
return d
|
|
}
|
|
|
|
// PrependPath is a generic implementation of FilesystemImpl.PrependPath().
|
|
func PrependPath(vfsroot vfs.VirtualDentry, mnt *vfs.Mount, d *Dentry, b *fspath.Builder) error {
|
|
for {
|
|
if mnt == vfsroot.Mount() && &d.vfsd == vfsroot.Dentry() {
|
|
return vfs.PrependPathAtVFSRootError{}
|
|
}
|
|
if mnt != nil && &d.vfsd == mnt.Root() {
|
|
return nil
|
|
}
|
|
if d.parent == nil {
|
|
return vfs.PrependPathAtNonMountRootError{}
|
|
}
|
|
b.PrependComponent(d.name)
|
|
d = d.parent
|
|
}
|
|
}
|
|
|
|
// DebugPathname returns a pathname to d relative to its filesystem root.
|
|
// DebugPathname does not correspond to any Linux function; it's used to
|
|
// generate dentry pathnames for debugging.
|
|
func DebugPathname(d *Dentry) string {
|
|
var b fspath.Builder
|
|
_ = PrependPath(vfs.VirtualDentry{}, nil, d, &b)
|
|
return b.String()
|
|
}
|