// Copyright 2019 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 ext

import (
	"gvisor.dev/gvisor/pkg/context"
	"gvisor.dev/gvisor/pkg/sentry/vfs"
)

// dentry implements vfs.DentryImpl.
//
// +stateify savable
type dentry struct {
	vfsd vfs.Dentry

	// Protected by filesystem.mu.
	parent *dentry
	name   string

	// inode is the inode represented by this dentry. Multiple Dentries may
	// share a single non-directory Inode (with hard links). inode is
	// immutable.
	inode *inode
}

// Compiles only if dentry implements vfs.DentryImpl.
var _ vfs.DentryImpl = (*dentry)(nil)

// newDentry is the dentry constructor.
func newDentry(in *inode) *dentry {
	d := &dentry{
		inode: in,
	}
	d.vfsd.Init(d)
	return d
}

// IncRef implements vfs.DentryImpl.IncRef.
func (d *dentry) IncRef() {
	d.inode.incRef()
}

// TryIncRef implements vfs.DentryImpl.TryIncRef.
func (d *dentry) TryIncRef() bool {
	return d.inode.tryIncRef()
}

// DecRef implements vfs.DentryImpl.DecRef.
func (d *dentry) DecRef(ctx context.Context) {
	// FIXME(b/134676337): filesystem.mu may not be locked as required by
	// inode.decRef().
	d.inode.decRef()
}

// InotifyWithParent implements vfs.DentryImpl.InotifyWithParent.
//
// TODO(b/134676337): Implement inotify.
func (d *dentry) InotifyWithParent(ctx context.Context, events, cookie uint32, et vfs.EventType) {}

// Watches implements vfs.DentryImpl.Watches.
//
// TODO(b/134676337): Implement inotify.
func (d *dentry) Watches() *vfs.Watches {
	return nil
}

// OnZeroWatches implements vfs.Dentry.OnZeroWatches.
//
// TODO(b/134676337): Implement inotify.
func (d *dentry) OnZeroWatches(context.Context) {}