2019-12-12 19:19:18 +00:00
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// Copyright 2019 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 kernfs
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import (
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"gvisor.dev/gvisor/pkg/abi/linux"
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2020-01-27 23:17:58 +00:00
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"gvisor.dev/gvisor/pkg/context"
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2019-12-12 19:19:18 +00:00
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"gvisor.dev/gvisor/pkg/sentry/memmap"
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"gvisor.dev/gvisor/pkg/sentry/vfs"
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"gvisor.dev/gvisor/pkg/syserror"
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2020-01-27 23:17:58 +00:00
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"gvisor.dev/gvisor/pkg/usermem"
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2019-12-12 19:19:18 +00:00
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)
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// GenericDirectoryFD implements vfs.FileDescriptionImpl for a generic directory
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// inode that uses OrderChildren to track child nodes. GenericDirectoryFD is not
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// compatible with dynamic directories.
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//
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// Note that GenericDirectoryFD holds a lock over OrderedChildren while calling
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// IterDirents callback. The IterDirents callback therefore cannot hash or
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// unhash children, or recursively call IterDirents on the same underlying
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// inode.
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//
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// Must be initialize with Init before first use.
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type GenericDirectoryFD struct {
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vfs.FileDescriptionDefaultImpl
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vfs.DirectoryFileDescriptionDefaultImpl
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vfsfd vfs.FileDescription
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children *OrderedChildren
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off int64
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}
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// Init initializes a GenericDirectoryFD.
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func (fd *GenericDirectoryFD) Init(m *vfs.Mount, d *vfs.Dentry, children *OrderedChildren, opts *vfs.OpenOptions) error {
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if vfs.AccessTypesForOpenFlags(opts)&vfs.MayWrite != 0 {
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// Can't open directories for writing.
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return syserror.EISDIR
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}
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if err := fd.vfsfd.Init(fd, opts.Flags, m, d, &vfs.FileDescriptionOptions{}); err != nil {
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return err
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}
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fd.children = children
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return nil
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}
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// VFSFileDescription returns a pointer to the vfs.FileDescription representing
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// this object.
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func (fd *GenericDirectoryFD) VFSFileDescription() *vfs.FileDescription {
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return &fd.vfsfd
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}
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// ConfigureMMap implements vfs.FileDescriptionImpl.ConfigureMMap.
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func (fd *GenericDirectoryFD) ConfigureMMap(ctx context.Context, opts *memmap.MMapOpts) error {
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return fd.FileDescriptionDefaultImpl.ConfigureMMap(ctx, opts)
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}
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// Read implmenets vfs.FileDescriptionImpl.Read.
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func (fd *GenericDirectoryFD) Read(ctx context.Context, dst usermem.IOSequence, opts vfs.ReadOptions) (int64, error) {
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return fd.DirectoryFileDescriptionDefaultImpl.Read(ctx, dst, opts)
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}
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// PRead implmenets vfs.FileDescriptionImpl.PRead.
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func (fd *GenericDirectoryFD) PRead(ctx context.Context, dst usermem.IOSequence, offset int64, opts vfs.ReadOptions) (int64, error) {
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return fd.DirectoryFileDescriptionDefaultImpl.PRead(ctx, dst, offset, opts)
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}
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// Write implements vfs.FileDescriptionImpl.Write.
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func (fd *GenericDirectoryFD) Write(ctx context.Context, src usermem.IOSequence, opts vfs.WriteOptions) (int64, error) {
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return fd.DirectoryFileDescriptionDefaultImpl.Write(ctx, src, opts)
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}
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// PWrite implements vfs.FileDescriptionImpl.PWrite.
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func (fd *GenericDirectoryFD) PWrite(ctx context.Context, src usermem.IOSequence, offset int64, opts vfs.WriteOptions) (int64, error) {
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return fd.DirectoryFileDescriptionDefaultImpl.PWrite(ctx, src, offset, opts)
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}
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// Release implements vfs.FileDecriptionImpl.Release.
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func (fd *GenericDirectoryFD) Release() {}
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func (fd *GenericDirectoryFD) filesystem() *vfs.Filesystem {
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return fd.vfsfd.VirtualDentry().Mount().Filesystem()
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}
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func (fd *GenericDirectoryFD) inode() Inode {
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return fd.vfsfd.VirtualDentry().Dentry().Impl().(*Dentry).inode
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}
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// IterDirents implements vfs.FileDecriptionImpl.IterDirents. IterDirents holds
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// o.mu when calling cb.
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func (fd *GenericDirectoryFD) IterDirents(ctx context.Context, cb vfs.IterDirentsCallback) error {
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vfsFS := fd.filesystem()
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fs := vfsFS.Impl().(*Filesystem)
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vfsd := fd.vfsfd.VirtualDentry().Dentry()
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fs.mu.Lock()
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defer fs.mu.Unlock()
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// Handle ".".
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if fd.off == 0 {
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stat := fd.inode().Stat(vfsFS)
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dirent := vfs.Dirent{
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Name: ".",
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Type: linux.DT_DIR,
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Ino: stat.Ino,
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NextOff: 1,
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}
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if err := cb.Handle(dirent); err != nil {
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return err
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}
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fd.off++
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}
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// Handle "..".
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if fd.off == 1 {
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parentInode := vfsd.ParentOrSelf().Impl().(*Dentry).inode
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stat := parentInode.Stat(vfsFS)
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dirent := vfs.Dirent{
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Name: "..",
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Type: linux.FileMode(stat.Mode).DirentType(),
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Ino: stat.Ino,
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NextOff: 2,
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}
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if err := cb.Handle(dirent); err != nil {
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return err
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}
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fd.off++
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}
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// Handle static children.
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fd.children.mu.RLock()
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defer fd.children.mu.RUnlock()
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// fd.off accounts for "." and "..", but fd.children do not track
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// these.
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childIdx := fd.off - 2
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for it := fd.children.nthLocked(childIdx); it != nil; it = it.Next() {
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inode := it.Dentry.Impl().(*Dentry).inode
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stat := inode.Stat(vfsFS)
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dirent := vfs.Dirent{
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Name: it.Name,
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Type: linux.FileMode(stat.Mode).DirentType(),
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Ino: stat.Ino,
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NextOff: fd.off + 1,
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}
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if err := cb.Handle(dirent); err != nil {
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return err
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}
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fd.off++
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}
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2019-12-26 22:42:19 +00:00
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var err error
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relOffset := fd.off - int64(len(fd.children.set)) - 2
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fd.off, err = fd.inode().IterDirents(ctx, cb, fd.off, relOffset)
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return err
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2019-12-12 19:19:18 +00:00
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}
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// Seek implements vfs.FileDecriptionImpl.Seek.
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func (fd *GenericDirectoryFD) Seek(ctx context.Context, offset int64, whence int32) (int64, error) {
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fs := fd.filesystem().Impl().(*Filesystem)
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fs.mu.Lock()
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defer fs.mu.Unlock()
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switch whence {
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case linux.SEEK_SET:
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// Use offset as given.
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case linux.SEEK_CUR:
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offset += fd.off
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default:
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return 0, syserror.EINVAL
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}
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if offset < 0 {
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return 0, syserror.EINVAL
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}
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fd.off = offset
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return offset, nil
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}
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// Stat implements vfs.FileDescriptionImpl.Stat.
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func (fd *GenericDirectoryFD) Stat(ctx context.Context, opts vfs.StatOptions) (linux.Statx, error) {
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fs := fd.filesystem()
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inode := fd.inode()
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return inode.Stat(fs), nil
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}
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// SetStat implements vfs.FileDescriptionImpl.SetStat.
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func (fd *GenericDirectoryFD) SetStat(ctx context.Context, opts vfs.SetStatOptions) error {
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fs := fd.filesystem()
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inode := fd.vfsfd.VirtualDentry().Dentry().Impl().(*Dentry).inode
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return inode.SetStat(fs, opts)
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}
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