1*88d15eacSSasha Smundak// Copyright 2017, The Go Authors. All rights reserved. 2*88d15eacSSasha Smundak// Use of this source code is governed by a BSD-style 3*88d15eacSSasha Smundak// license that can be found in the LICENSE file. 4*88d15eacSSasha Smundak 5*88d15eacSSasha Smundak//go:build !purego 6*88d15eacSSasha Smundak// +build !purego 7*88d15eacSSasha Smundak 8*88d15eacSSasha Smundakpackage cmp 9*88d15eacSSasha Smundak 10*88d15eacSSasha Smundakimport ( 11*88d15eacSSasha Smundak "reflect" 12*88d15eacSSasha Smundak "unsafe" 13*88d15eacSSasha Smundak) 14*88d15eacSSasha Smundak 15*88d15eacSSasha Smundakconst supportExporters = true 16*88d15eacSSasha Smundak 17*88d15eacSSasha Smundak// retrieveUnexportedField uses unsafe to forcibly retrieve any field from 18*88d15eacSSasha Smundak// a struct such that the value has read-write permissions. 19*88d15eacSSasha Smundak// 20*88d15eacSSasha Smundak// The parent struct, v, must be addressable, while f must be a StructField 21*88d15eacSSasha Smundak// describing the field to retrieve. If addr is false, 22*88d15eacSSasha Smundak// then the returned value will be shallowed copied to be non-addressable. 23*88d15eacSSasha Smundakfunc retrieveUnexportedField(v reflect.Value, f reflect.StructField, addr bool) reflect.Value { 24*88d15eacSSasha Smundak ve := reflect.NewAt(f.Type, unsafe.Pointer(uintptr(unsafe.Pointer(v.UnsafeAddr()))+f.Offset)).Elem() 25*88d15eacSSasha Smundak if !addr { 26*88d15eacSSasha Smundak // A field is addressable if and only if the struct is addressable. 27*88d15eacSSasha Smundak // If the original parent value was not addressable, shallow copy the 28*88d15eacSSasha Smundak // value to make it non-addressable to avoid leaking an implementation 29*88d15eacSSasha Smundak // detail of how forcibly exporting a field works. 30*88d15eacSSasha Smundak if ve.Kind() == reflect.Interface && ve.IsNil() { 31*88d15eacSSasha Smundak return reflect.Zero(f.Type) 32*88d15eacSSasha Smundak } 33*88d15eacSSasha Smundak return reflect.ValueOf(ve.Interface()).Convert(f.Type) 34*88d15eacSSasha Smundak } 35*88d15eacSSasha Smundak return ve 36*88d15eacSSasha Smundak} 37