test: merge nilptr/* into one test

The 512 MB array causes load delays on some systems.
Now that we have recover, we can do all the tests in
one binary, so that the delay is incurred just once.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/5142044

1 files changed, 125 insertions, 0 deletions

diff --git a/test/nilptr.go b/test/nilptr.go
new file mode 100644
index 0000000000..41d8f23528
--- /dev/null
+++ b/test/nilptr.go
@@ -0,0 +1,125 @@
+// $G $D/$F.go && $L $F.$A && ./$A.out
+
+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 [512 << 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
+}