github.com/sagernet/gvisor@v0.0.0-20240428053021-e691de28565f/pkg/tcpip/transport/tcp/segment_state.go (about)

     1  // Copyright 2018 The gVisor Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package tcp
    16  
    17  import (
    18  	"context"
    19  )
    20  
    21  // saveOptions is invoked by stateify.
    22  func (s *segment) saveOptions() []byte {
    23  	// We cannot save s.options directly as it may point to s.data's trimmed
    24  	// tail, which is not allowed by state framework (in-struct pointer).
    25  	b := make([]byte, 0, cap(s.options))
    26  	return append(b, s.options...)
    27  }
    28  
    29  // loadOptions is invoked by stateify.
    30  func (s *segment) loadOptions(_ context.Context, options []byte) {
    31  	// NOTE: We cannot point s.options back into s.data's trimmed tail. But
    32  	// it is OK as they do not need to aliased. Plus, options is already
    33  	// allocated so there is no cost here.
    34  	s.options = options
    35  }