go/test/nilptr/structfield.go

36 строки
1017 B
Go

// [ $GOOS != nacl ] || exit 0 # do not bother on NaCl
// $G $D/$F.go && $L $F.$A &&
// ((! sh -c ./$A.out) >/dev/null 2>&1 || 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 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.
var t *T;
println(t.i); // should crash
}