1// Copyright 2013 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5package runtime_test
6
7import (
8	"io/ioutil"
9	"os"
10	"reflect"
11	"syscall"
12	"testing"
13	"unsafe"
14)
15
16// TestMemmoveOverflow maps 3GB of memory and calls memmove on
17// the corresponding slice.
18func TestMemmoveOverflow(t *testing.T) {
19	t.Parallel()
20	// Create a temporary file.
21	tmp, err := ioutil.TempFile("", "go-memmovetest")
22	if err != nil {
23		t.Fatal(err)
24	}
25	_, err = tmp.Write(make([]byte, 65536))
26	if err != nil {
27		t.Fatal(err)
28	}
29	defer os.Remove(tmp.Name())
30	defer tmp.Close()
31
32	// Set up mappings.
33	base, _, errno := syscall.Syscall6(syscall.SYS_MMAP,
34		0xa0<<32, 3<<30, syscall.PROT_READ|syscall.PROT_WRITE, syscall.MAP_PRIVATE|syscall.MAP_ANONYMOUS, ^uintptr(0), 0)
35	if errno != 0 {
36		t.Skipf("could not create memory mapping: %s", errno)
37	}
38	syscall.Syscall(syscall.SYS_MUNMAP, base, 3<<30, 0)
39
40	for off := uintptr(0); off < 3<<30; off += 65536 {
41		_, _, errno := syscall.Syscall6(syscall.SYS_MMAP,
42			base+off, 65536, syscall.PROT_READ|syscall.PROT_WRITE, syscall.MAP_SHARED|syscall.MAP_FIXED, tmp.Fd(), 0)
43		if errno != 0 {
44			t.Skipf("could not map a page at requested 0x%x: %s", base+off, errno)
45		}
46		defer syscall.Syscall(syscall.SYS_MUNMAP, base+off, 65536, 0)
47	}
48
49	var s []byte
50	sp := (*reflect.SliceHeader)(unsafe.Pointer(&s))
51	sp.Data = base
52	sp.Len, sp.Cap = 3<<30, 3<<30
53
54	n := copy(s[1:], s)
55	if n != 3<<30-1 {
56		t.Fatalf("copied %d bytes, expected %d", n, 3<<30-1)
57	}
58	n = copy(s, s[1:])
59	if n != 3<<30-1 {
60		t.Fatalf("copied %d bytes, expected %d", n, 3<<30-1)
61	}
62}
63