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// 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 ramfs
import (
"gvisor.googlesource.com/gvisor/pkg/abi/linux"
"gvisor.googlesource.com/gvisor/pkg/sentry/context"
"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
"gvisor.googlesource.com/gvisor/pkg/sentry/fs/fsutil"
"gvisor.googlesource.com/gvisor/pkg/waiter"
)
// Symlink represents a symlink.
//
// +stateify savable
type Symlink struct {
fsutil.InodeGenericChecker `state:"nosave"`
fsutil.InodeNoopRelease `state:"nosave"`
fsutil.InodeNoopWriteOut `state:"nosave"`
fsutil.InodeNotAllocatable `state:"nosave"`
fsutil.InodeNotDirectory `state:"nosave"`
fsutil.InodeNotMappable `state:"nosave"`
fsutil.InodeNotSocket `state:"nosave"`
fsutil.InodeNotTruncatable `state:"nosave"`
fsutil.InodeVirtual `state:"nosave"`
fsutil.InodeSimpleAttributes
fsutil.InodeSimpleExtendedAttributes
// Target is the symlink target.
Target string
}
var _ fs.InodeOperations = (*Symlink)(nil)
// NewSymlink returns a new Symlink.
func NewSymlink(ctx context.Context, owner fs.FileOwner, target string) *Symlink {
// A symlink is assumed to always have permissions 0777.
return &Symlink{
InodeSimpleAttributes: fsutil.NewInodeSimpleAttributes(ctx, owner, fs.FilePermsFromMode(0777), linux.RAMFS_MAGIC),
Target: target,
}
}
// UnstableAttr returns all attributes of this ramfs symlink.
func (s *Symlink) UnstableAttr(ctx context.Context, inode *fs.Inode) (fs.UnstableAttr, error) {
uattr, err := s.InodeSimpleAttributes.UnstableAttr(ctx, inode)
if err != nil {
return fs.UnstableAttr{}, err
}
uattr.Size = int64(len(s.Target))
uattr.Usage = uattr.Size
return uattr, nil
}
// SetPermissions on a symlink is always rejected.
func (s *Symlink) SetPermissions(context.Context, *fs.Inode, fs.FilePermissions) bool {
return false
}
// Readlink reads the symlink value.
func (s *Symlink) Readlink(ctx context.Context, _ *fs.Inode) (string, error) {
s.NotifyAccess(ctx)
return s.Target, nil
}
// Getlink returns ErrResolveViaReadlink, falling back to walking to the result
// of Readlink().
func (*Symlink) Getlink(context.Context, *fs.Inode) (*fs.Dirent, error) {
return nil, fs.ErrResolveViaReadlink
}
// GetFile implements fs.FileOperations.GetFile.
func (s *Symlink) GetFile(ctx context.Context, dirent *fs.Dirent, flags fs.FileFlags) (*fs.File, error) {
return fs.NewFile(ctx, dirent, flags, &symlinkFileOperations{}), nil
}
// +stateify savable
type symlinkFileOperations struct {
fsutil.FileNoIoctl `state:"nosave"`
fsutil.FileNoMMap `state:"nosave"`
fsutil.FileNoRead `state:"nosave"`
fsutil.FileNoSeek `state:"nosave"`
fsutil.FileNoSplice `state:"nosave"`
fsutil.FileNoWrite `state:"nosave"`
fsutil.FileNoopFlush `state:"nosave"`
fsutil.FileNoopFsync `state:"nosave"`
fsutil.FileNoopRelease `state:"nosave"`
fsutil.FileNotDirReaddir `state:"nosave"`
fsutil.FileUseInodeUnstableAttr `state:"nosave"`
waiter.AlwaysReady `state:"nosave"`
}
var _ fs.FileOperations = (*symlinkFileOperations)(nil)
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