1 files changed, 129 insertions, 0 deletions
diff --git a/test/nilptr.go b/test/nilptr.go
new file mode 100644
index 000000000..b0c1df2d9
--- /dev/null
+++ b/test/nilptr.go
@@ -0,0 +1,129 @@
+// $G $D/$F.go && $L $F.$A && ./$A.out
+
+// Copyright 2011 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"
+
+// Having a big address space means that indexing
+// at a 256 MB offset from a nil pointer might not
+// cause a memory access fault. This test checks
+// that Go is doing the correct explicit checks to catch
+// these nil pointer accesses, not just relying on the hardware.
+var dummy [256 << 20]byte // give us a big address space
+
+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")
+	}
+
+	shouldPanic(p1)
+	shouldPanic(p2)
+	shouldPanic(p3)
+	shouldPanic(p4)
+	shouldPanic(p5)
+	shouldPanic(p6)
+	shouldPanic(p7)
+	shouldPanic(p8)
+	shouldPanic(p9)
+	shouldPanic(p10)
+}
+
+func shouldPanic(f func()) {
+	defer func() {
+		if recover() == nil {
+			panic("memory reference did not panic")
+		}
+	}()
+	f()
+}
+
+func p1() {
+	// Array index.
+	var p *[1 << 30]byte = nil
+	println(p[256<<20]) // very likely to be inside dummy, but should panic
+}
+
+var xb byte
+
+func p2() {
+	var p *[1 << 30]byte = nil
+	xb = 123
+
+	// Array index.
+	println(p[uintptr(unsafe.Pointer(&xb))]) // should panic
+}
+
+func p3() {
+	// Array to slice.
+	var p *[1 << 30]byte = nil
+	var x []byte = p[0:] // should panic
+	_ = x
+}
+
+var q *[1 << 30]byte
+
+func p4() {
+	// Array to slice.
+	var x []byte
+	var y = &x
+	*y = q[0:] // should crash (uses arraytoslice runtime routine)
+}
+
+func fb([]byte) {
+	panic("unreachable")
+}
+
+func p5() {
+	// Array to slice.
+	var p *[1 << 30]byte = nil
+	fb(p[0:]) // should crash
+}
+
+func p6() {
+	// Array to slice.
+	var p *[1 << 30]byte = nil
+	var _ []byte = p[10 : len(p)-10] // should crash
+}
+
+type T struct {
+	x [256 << 20]byte
+	i int
+}
+
+func f() *T {
+	return nil
+}
+
+var y *T
+var x = &y
+
+func p7() {
+	// Struct field access with large offset.
+	println(f().i) // should crash
+}
+
+func p8() {
+	// Struct field access with large offset.
+	println((*x).i) // should crash
+}
+
+func p9() {
+	// Struct field access with large offset.
+	var t *T
+	println(&t.i) // should crash
+}
+
+func p10() {
+	// Struct field access with large offset.
+	var t *T
+	println(t.i) // should crash
+}