// Copyright 2013 The Go Authors. All rights reserved.// Use of this source code is governed by a BSD-style// license that can be found in the LICENSE file.//// +build linux package bytes_test import (	. "bytes"	"syscall"	"testing"	"unsafe") // This file tests the situation where memeq is checking// data very near to a page boundary.  We want to make sure// equal does not read across the boundary and cause a page// fault where it shouldn't. // This test runs only on linux.  The code being tested is// not OS-specific, so it does not need to be tested on all// operating systems. func TestEqualNearPageBoundary(t *testing.T) {	pagesize := syscall.Getpagesize()	b := make([]byte, 4*pagesize)	i := pagesize	for ; uintptr(unsafe.Pointer(&b[i]))%uintptr(pagesize) != 0; i++ {	}	syscall.Mprotect(b[i-pagesize:i], 0)	syscall.Mprotect(b[i+pagesize:i+2*pagesize], 0)	defer syscall.Mprotect(b[i-pagesize:i], syscall.PROT_READ|syscall.PROT_WRITE)	defer syscall.Mprotect(b[i+pagesize:i+2*pagesize], syscall.PROT_READ|syscall.PROT_WRITE) 	// both of these should fault	//pagesize += int(b[i-1])	//pagesize += int(b[i+pagesize]) 	for j := 0; j < pagesize; j++ {		b[i+j] = 'A'	}	for j := 0; j <= pagesize; j++ {		Equal(b[i:i+j], b[i+pagesize-j:i+pagesize])		Equal(b[i+pagesize-j:i+pagesize], b[i:i+j])	}}