1 // Copyright 2013 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 // +build linux 6 7 package bytes_test 8 9 import ( 10 . "bytes" 11 "syscall" 12 "testing" 13 "unsafe" 14 ) 15 16 // This file tests the situation where memeq is checking 17 // data very near to a page boundary. We want to make sure 18 // equal does not read across the boundary and cause a page 19 // fault where it shouldn't. 20 21 // This test runs only on linux. The code being tested is 22 // not OS-specific, so it does not need to be tested on all 23 // operating systems. 24 25 func TestEqualNearPageBoundary(t *testing.T) { 26 pagesize := syscall.Getpagesize() 27 b := make([]byte, 4*pagesize) 28 i := pagesize 29 for ; uintptr(unsafe.Pointer(&b[i]))%uintptr(pagesize) != 0; i++ { 30 } 31 syscall.Mprotect(b[i-pagesize:i], 0) 32 syscall.Mprotect(b[i+pagesize:i+2*pagesize], 0) 33 defer syscall.Mprotect(b[i-pagesize:i], syscall.PROT_READ|syscall.PROT_WRITE) 34 defer syscall.Mprotect(b[i+pagesize:i+2*pagesize], syscall.PROT_READ|syscall.PROT_WRITE) 35 36 // both of these should fault 37 //pagesize += int(b[i-1]) 38 //pagesize += int(b[i+pagesize]) 39 40 for j := 0; j < pagesize; j++ { 41 b[i+j] = 'A' 42 } 43 for j := 0; j <= pagesize; j++ { 44 Equal(b[i:i+j], b[i+pagesize-j:i+pagesize]) 45 Equal(b[i+pagesize-j:i+pagesize], b[i:i+j]) 46 } 47 } 48
