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go/test/nilptr/structfield1.go
Russ Cox 02fd255a14 bug162, over and over
R=ken
OCL=35919
CL=35919
2009-10-20 08:03:43 -07:00

37 lines
955 B
Go

// $G $D/$F.go && $L $F.$A && (! ./$A.out || echo BUG: should fail)
// Copyright 2009 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"
var dummy [512<<20]byte; // give us a big address space
type T struct {
x [256<<20] byte;
i int;
}
func f() *T {
return nil;
}
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");
}
// The problem here is that indexing into t with a large
// enough index can jump out of the unmapped section
// at the beginning of memory and into valid memory.
// We require the pointer dereference to check.
println(f().i); // should crash
}