1// Copyright 2017, The Go Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style 3// license that can be found in the LICENSE.md file. 4 5// +build !purego 6 7package cmp 8 9import ( 10 "reflect" 11 "unsafe" 12) 13 14const supportExporters = true 15 16// retrieveUnexportedField uses unsafe to forcibly retrieve any field from 17// a struct such that the value has read-write permissions. 18// 19// The parent struct, v, must be addressable, while f must be a StructField 20// describing the field to retrieve. If addr is false, 21// then the returned value will be shallowed copied to be non-addressable. 22func retrieveUnexportedField(v reflect.Value, f reflect.StructField, addr bool) reflect.Value { 23 ve := reflect.NewAt(f.Type, unsafe.Pointer(uintptr(unsafe.Pointer(v.UnsafeAddr()))+f.Offset)).Elem() 24 if !addr { 25 // A field is addressable if and only if the struct is addressable. 26 // If the original parent value was not addressable, shallow copy the 27 // value to make it non-addressable to avoid leaking an implementation 28 // detail of how forcibly exporting a field works. 29 if ve.Kind() == reflect.Interface && ve.IsNil() { 30 return reflect.Zero(f.Type) 31 } 32 return reflect.ValueOf(ve.Interface()).Convert(f.Type) 33 } 34 return ve 35} 36