mirror of
https://github.com/golang/go
synced 2024-11-21 21:24:45 -07:00
4bdf1fc02b
Add copyright notice to nilptr.go. R=golang-dev, r CC=golang-dev https://golang.org/cl/5139048
130 lines
2.4 KiB
Go
130 lines
2.4 KiB
Go
// $G $D/$F.go && $L $F.$A && ./$A.out
|
|
|
|
// Copyright 2011 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.
|
|
|
|
package main
|
|
|
|
import "unsafe"
|
|
|
|
// Having a big address space means that indexing
|
|
// at a 256 MB offset from a nil pointer might not
|
|
// cause a memory access fault. This test checks
|
|
// that Go is doing the correct explicit checks to catch
|
|
// these nil pointer accesses, not just relying on the hardware.
|
|
var dummy [512 << 20]byte // give us a big address space
|
|
|
|
func main() {
|
|
// the test only tests what we intend to test
|
|
// if dummy starts in the first 256 MB of memory.
|
|
// otherwise there might not be anything mapped
|
|
// at the address that might be accidentally
|
|
// dereferenced below.
|
|
if uintptr(unsafe.Pointer(&dummy)) > 256<<20 {
|
|
panic("dummy too far out")
|
|
}
|
|
|
|
shouldPanic(p1)
|
|
shouldPanic(p2)
|
|
shouldPanic(p3)
|
|
shouldPanic(p4)
|
|
shouldPanic(p5)
|
|
shouldPanic(p6)
|
|
shouldPanic(p7)
|
|
shouldPanic(p8)
|
|
shouldPanic(p9)
|
|
shouldPanic(p10)
|
|
}
|
|
|
|
func shouldPanic(f func()) {
|
|
defer func() {
|
|
if recover() == nil {
|
|
panic("memory reference did not panic")
|
|
}
|
|
}()
|
|
f()
|
|
}
|
|
|
|
func p1() {
|
|
// Array index.
|
|
var p *[1 << 30]byte = nil
|
|
println(p[256<<20]) // very likely to be inside dummy, but should panic
|
|
}
|
|
|
|
var xb byte
|
|
|
|
func p2() {
|
|
var p *[1 << 30]byte = nil
|
|
xb = 123
|
|
|
|
// Array index.
|
|
println(p[uintptr(unsafe.Pointer(&xb))]) // should panic
|
|
}
|
|
|
|
func p3() {
|
|
// Array to slice.
|
|
var p *[1 << 30]byte = nil
|
|
var x []byte = p[0:] // should panic
|
|
_ = x
|
|
}
|
|
|
|
var q *[1 << 30]byte
|
|
|
|
func p4() {
|
|
// Array to slice.
|
|
var x []byte
|
|
var y = &x
|
|
*y = q[0:] // should crash (uses arraytoslice runtime routine)
|
|
}
|
|
|
|
func fb([]byte) {
|
|
panic("unreachable")
|
|
}
|
|
|
|
func p5() {
|
|
// Array to slice.
|
|
var p *[1 << 30]byte = nil
|
|
fb(p[0:]) // should crash
|
|
}
|
|
|
|
func p6() {
|
|
// Array to slice.
|
|
var p *[1 << 30]byte = nil
|
|
var _ []byte = p[10 : len(p)-10] // should crash
|
|
}
|
|
|
|
type T struct {
|
|
x [256 << 20]byte
|
|
i int
|
|
}
|
|
|
|
func f() *T {
|
|
return nil
|
|
}
|
|
|
|
var y *T
|
|
var x = &y
|
|
|
|
func p7() {
|
|
// Struct field access with large offset.
|
|
println(f().i) // should crash
|
|
}
|
|
|
|
func p8() {
|
|
// Struct field access with large offset.
|
|
println((*x).i) // should crash
|
|
}
|
|
|
|
func p9() {
|
|
// Struct field access with large offset.
|
|
var t *T
|
|
println(&t.i) // should crash
|
|
}
|
|
|
|
func p10() {
|
|
// Struct field access with large offset.
|
|
var t *T
|
|
println(t.i) // should crash
|
|
}
|