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https://github.com/golang/go
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130 lines
2.4 KiB
Go
130 lines
2.4 KiB
Go
// $G $D/$F.go && $L $F.$A && ./$A.out
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// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package main
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import "unsafe"
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// Having a big address space means that indexing
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// at a 256 MB offset from a nil pointer might not
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// cause a memory access fault. This test checks
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// that Go is doing the correct explicit checks to catch
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// these nil pointer accesses, not just relying on the hardware.
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var dummy [256 << 20]byte // give us a big address space
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func main() {
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// the test only tests what we intend to test
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// if dummy starts in the first 256 MB of memory.
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// otherwise there might not be anything mapped
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// at the address that might be accidentally
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// dereferenced below.
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if uintptr(unsafe.Pointer(&dummy)) > 256<<20 {
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panic("dummy too far out")
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}
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shouldPanic(p1)
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shouldPanic(p2)
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shouldPanic(p3)
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shouldPanic(p4)
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shouldPanic(p5)
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shouldPanic(p6)
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shouldPanic(p7)
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shouldPanic(p8)
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shouldPanic(p9)
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shouldPanic(p10)
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}
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func shouldPanic(f func()) {
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defer func() {
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if recover() == nil {
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panic("memory reference did not panic")
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}
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}()
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f()
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}
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func p1() {
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// Array index.
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var p *[1 << 30]byte = nil
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println(p[256<<20]) // very likely to be inside dummy, but should panic
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}
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var xb byte
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func p2() {
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var p *[1 << 30]byte = nil
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xb = 123
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// Array index.
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println(p[uintptr(unsafe.Pointer(&xb))]) // should panic
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}
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func p3() {
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// Array to slice.
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var p *[1 << 30]byte = nil
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var x []byte = p[0:] // should panic
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_ = x
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}
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var q *[1 << 30]byte
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func p4() {
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// Array to slice.
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var x []byte
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var y = &x
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*y = q[0:] // should crash (uses arraytoslice runtime routine)
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}
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func fb([]byte) {
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panic("unreachable")
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}
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func p5() {
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// Array to slice.
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var p *[1 << 30]byte = nil
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fb(p[0:]) // should crash
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}
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func p6() {
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// Array to slice.
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var p *[1 << 30]byte = nil
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var _ []byte = p[10 : len(p)-10] // should crash
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}
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type T struct {
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x [256 << 20]byte
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i int
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}
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func f() *T {
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return nil
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}
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var y *T
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var x = &y
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func p7() {
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// Struct field access with large offset.
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println(f().i) // should crash
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}
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func p8() {
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// Struct field access with large offset.
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println((*x).i) // should crash
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}
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func p9() {
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// Struct field access with large offset.
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var t *T
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println(&t.i) // should crash
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}
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func p10() {
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// Struct field access with large offset.
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var t *T
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println(t.i) // should crash
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}
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