gcc/testsuite/go.test/test/nilptr/structfield2.go

   1 // [ $GOOS != nacl ] || exit 0  # do not bother on NaCl
   2 // $G $D/$F.go && $L $F.$A &&
   3 //      ((! sh -c ./$A.out) >/dev/null 2>&1 || echo BUG: should fail)
   4
   5 // Copyright 2009 The Go Authors. All rights reserved.
   6 // Use of this source code is governed by a BSD-style
   7 // license that can be found in the LICENSE file.
   8
   9 package main
  10
  11 import "unsafe"
  12
  13 var dummy [512<<20]byte // give us a big address space
  14 type T struct {
  15         x [256<<20] byte
  16         i int
  17 }
  18
  19 var y *T
  20 var x = &y
  21
  22 func main() {
  23         // the test only tests what we intend to test
  24         // if dummy starts in the first 256 MB of memory.
  25         // otherwise there might not be anything mapped
  26         // at the address that might be accidentally
  27         // dereferenced below.
  28         if uintptr(unsafe.Pointer(&dummy)) > 256<<20 {
  29                 panic("dummy too far out")
  30         }
  31
  32         // The problem here is that indexing into t with a large
  33         // enough index can jump out of the unmapped section
  34         // at the beginning of memory and into valid memory.
  35         // We require the pointer dereference to check.
  36         println((*x).i) // should crash
  37 }