// Copyright 2018 The Netstack Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package tcp

import (
	"gvisor.googlesource.com/gvisor/pkg/tcpip/buffer"
)

// saveData is invoked by stateify.
func (s *segment) saveData() buffer.VectorisedView {
	// We cannot save s.data directly as s.data.views may alias to s.views,
	// which is not allowed by state framework (in-struct pointer).
	return s.data.Clone(nil)
}

// loadData is invoked by stateify.
func (s *segment) loadData(data buffer.VectorisedView) {
	// NOTE: We cannot do the s.data = data.Clone(s.views[:]) optimization
	// here because data.views is not guaranteed to be loaded by now. Plus,
	// data.views will be allocated anyway so there really is little point
	// of utilizing s.views for data.views.
	s.data = data
}

// saveOptions is invoked by stateify.
func (s *segment) saveOptions() []byte {
	// We cannot save s.options directly as it may point to s.data's trimmed
	// tail, which is not allowed by state framework (in-struct pointer).
	b := make([]byte, 0, cap(s.options))
	return append(b, s.options...)
}

// loadOptions is invoked by stateify.
func (s *segment) loadOptions(options []byte) {
	// NOTE: We cannot point s.options back into s.data's trimmed tail. But
	// it is OK as they do not need to aliased. Plus, options is already
	// allocated so there is no cost here.
	s.options = options
}