gcc/testsuite/go.test/test/nilptr/arraytoslice.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 func f([]byte) {
  14         panic("unreachable")
  15 }
  16
  17 var dummy [512<<20]byte // give us a big address space
  18 func main() {
  19         // the test only tests what we intend to test
  20         // if dummy starts in the first 256 MB of memory.
  21         // otherwise there might not be anything mapped
  22         // at the address that might be accidentally
  23         // dereferenced below.
  24         if uintptr(unsafe.Pointer(&dummy)) > 256<<20 {
  25                 panic("dummy too far out")
  26         }
  27
  28         // The problem here is that indexing into p[] with a large
  29         // enough index can jump out of the unmapped section
  30         // at the beginning of memory and into valid memory.
  31         //
  32         // To avoid needing a check on every slice beyond the
  33         // usual len and cap, we require the *array -> slice
  34         // conversion to do the check.
  35         var p *[1<<30]byte = nil
  36         f(p[0:])        // should crash
  37 }