1 // Copyright 2018 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 file. 4 5 //go:build !purego 6 7 // Package alias implements memory aliasing tests. 8 package alias 9 10 import "unsafe" 11 12 // AnyOverlap reports whether x and y share memory at any (not necessarily 13 // corresponding) index. The memory beyond the slice length is ignored. 14 func AnyOverlap(x, y []byte) bool { 15 return len(x) > 0 && len(y) > 0 && 16 uintptr(unsafe.Pointer(&x[0])) <= uintptr(unsafe.Pointer(&y[len(y)-1])) && 17 uintptr(unsafe.Pointer(&y[0])) <= uintptr(unsafe.Pointer(&x[len(x)-1])) 18 } 19 20 // InexactOverlap reports whether x and y share memory at any non-corresponding 21 // index. The memory beyond the slice length is ignored. Note that x and y can 22 // have different lengths and still not have any inexact overlap. 23 // 24 // InexactOverlap can be used to implement the requirements of the crypto/cipher 25 // AEAD, Block, BlockMode and Stream interfaces. 26 func InexactOverlap(x, y []byte) bool { 27 if len(x) == 0 || len(y) == 0 || &x[0] == &y[0] { 28 return false 29 } 30 return AnyOverlap(x, y) 31 } 32