github.com/SagerNet/gvisor@v0.0.0-20210707092255-7731c139d75c/pkg/state/encode_unsafe.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 state
    16  
    17  import (
    18  	"reflect"
    19  	"unsafe"
    20  )
    21  
    22  // arrayFromSlice constructs a new pointer to the slice data.
    23  //
    24  // It would be similar to the following:
    25  //
    26  //	x := make([]Foo, l, c)
    27  //	a := ([l]Foo*)(unsafe.Pointer(x[0]))
    28  //
    29  func arrayFromSlice(obj reflect.Value) reflect.Value {
    30  	return reflect.NewAt(
    31  		reflect.ArrayOf(obj.Cap(), obj.Type().Elem()),
    32  		unsafe.Pointer(obj.Pointer()))
    33  }