Exemplo n.º 1
0
func TestMkdir(t *testing.T) {
	tmp := tempdir.New(t)
	defer tmp.Cleanup()
	app := bazfstestutil.NewApp(t, tmp.Subdir("data"))
	defer app.Close()
	bazfstestutil.CreateVolume(t, app, "default")

	mnt := bazfstestutil.Mounted(t, app, "default")
	defer mnt.Close()

	p := path.Join(mnt.Dir, "sub")
	err := os.Mkdir(p, 0700)
	if err != nil {
		t.Fatalf("cannot mkdir sub: %v", err)
	}

	dirf, err := os.Open(mnt.Dir)
	if err != nil {
		t.Fatalf("cannot open root dir: %v", err)
	}
	defer dirf.Close()
	names, err := dirf.Readdirnames(10)
	if err != nil && err != io.EOF {
		t.Fatalf("cannot list root dir: %v", err)
	}
	if len(names) != 1 {
		t.Fatalf("unexpected content in root dir: %v", names)
	}
	if names[0] != "sub" {
		t.Errorf("unexpected file in root dir: %q", names[0])
	}
}
Exemplo n.º 2
0
func TestRemoveFile(t *testing.T) {
	tmp := tempdir.New(t)
	defer tmp.Cleanup()
	app := bazfstestutil.NewApp(t, tmp.Subdir("data"))
	defer app.Close()
	bazfstestutil.CreateVolume(t, app, "default")

	mnt := bazfstestutil.Mounted(t, app, "default")
	defer mnt.Close()

	p := path.Join(mnt.Dir, "hello")
	GREETING := "hello, world\n"
	err := ioutil.WriteFile(p, []byte(GREETING), 0644)
	if err != nil {
		t.Fatalf("cannot create hello: %v", err)
	}

	err = os.Remove(p)
	if err != nil {
		t.Fatalf("cannot delete hello: %v", err)
	}

	dirf, err := os.Open(mnt.Dir)
	if err != nil {
		t.Fatalf("cannot open root dir: %v", err)
	}
	defer dirf.Close()
	names, err := dirf.Readdirnames(10)
	if err != nil && err != io.EOF {
		t.Fatalf("cannot list root dir: %v", err)
	}
	if len(names) != 0 {
		t.Errorf("unexpected content in root dir: %v", names)
	}
}
Exemplo n.º 3
0
func TestStatFile(t *testing.T) {
	tmp := tempdir.New(t)
	defer tmp.Cleanup()
	app := bazfstestutil.NewApp(t, tmp.Subdir("data"))
	defer app.Close()
	bazfstestutil.CreateVolume(t, app, "default")

	mnt := bazfstestutil.Mounted(t, app, "default")
	defer mnt.Close()

	p := path.Join(mnt.Dir, "hello")
	f, err := os.Create(p)
	if err != nil {
		t.Fatalf("cannot create hello: %v", err)
	}
	defer f.Close()
	GREETING := "hello, world\n"
	n, err := f.Write([]byte(GREETING))
	if err != nil {
		t.Fatalf("cannot write to hello: %v", err)
	}
	if n != len(GREETING) {
		t.Fatalf("bad length write to hello: %d != %d", n, len(GREETING))
	}
	err = f.Close()
	if err != nil {
		t.Fatalf("closing hello failed: %v", err)
	}

	fi, err := os.Stat(p)
	if err != nil {
		t.Fatalf("cannot stat hello: %v", err)
	}
	mode := fi.Mode()
	if (mode & os.ModeType) != 0 {
		t.Errorf("hello is not a file: %#v", fi)
	}
	if mode.Perm() != 0644 {
		t.Errorf("file has weird access mode: %v", mode.Perm())
	}
	switch stat := fi.Sys().(type) {
	case *syscall.Stat_t:
		if stat.Nlink != 1 {
			t.Errorf("file has wrong link count: %v", stat.Nlink)
		}
		if stat.Uid != uint32(syscall.Getuid()) {
			t.Errorf("file has wrong uid: %d", stat.Uid)
		}
		if stat.Gid != uint32(syscall.Getgid()) {
			t.Errorf("file has wrong gid: %d", stat.Gid)
		}
		if stat.Gid != uint32(syscall.Getgid()) {
			t.Errorf("file has wrong gid: %d", stat.Gid)
		}
	}
	if fi.Size() != int64(len(GREETING)) {
		t.Errorf("file has wrong size: %d != %d", fi.Size(), len(GREETING))
	}
}
Exemplo n.º 4
0
func TestRenameCrossDir(t *testing.T) {
	tmp := tempdir.New(t)
	defer tmp.Cleanup()
	app := bazfstestutil.NewApp(t, tmp.Subdir("data"))
	defer app.Close()
	bazfstestutil.CreateVolume(t, app, "default")

	mnt := bazfstestutil.Mounted(t, app, "default")
	defer mnt.Close()

	p := path.Join(mnt.Dir, "hello")
	GREETING := "hello, world\n"
	err := ioutil.WriteFile(p, []byte(GREETING), 0644)
	if err != nil {
		t.Fatalf("cannot create file: %v", err)
	}

	pd := path.Join(mnt.Dir, "subdir")
	err = os.Mkdir(pd, 0755)
	if err != nil {
		t.Fatalf("cannot mkdir: %v", err)
	}

	p2 := path.Join(pd, "cheers")
	err = os.Rename(p, p2)
	if err == nil {
		t.Fatalf("expected an error from rename: %v", err)
	}
	lerr, ok := err.(*os.LinkError)
	if !ok {
		t.Fatalf("expected a LinkError from rename: %v", err)
	}
	if g, e := lerr.Op, "rename"; g != e {
		t.Errorf("wrong LinkError.Op: %q != %q", g, e)
	}
	if g, e := lerr.Old, p; g != e {
		t.Errorf("wrong LinkError.Old: %q != %q", g, e)
	}
	if g, e := lerr.New, p2; g != e {
		t.Errorf("wrong LinkError.New: %q != %q", g, e)
	}
	if g, e := lerr.Err, syscall.EXDEV; g != e {
		t.Errorf("expected EXDEV: %T %v", lerr.Err, lerr.Err)
	}

	buf, err := ioutil.ReadFile(p)
	if err != nil {
		t.Fatalf("cannot read: %v", err)
	}
	if string(buf) != GREETING {
		t.Fatalf("hello content is wrong: %q", buf)
	}

}
Exemplo n.º 5
0
func TestSimple(t *testing.T) {
	tmp := tempdir.New(t)
	defer tmp.Cleanup()
	app := bazfstestutil.NewApp(t, tmp.Subdir("data"))
	defer app.Close()
	bazfstestutil.CreateVolume(t, app, "default")

	mnt := bazfstestutil.Mounted(t, app, "default")
	defer mnt.Close()

	fi, err := os.Stat(mnt.Dir)
	if err != nil {
		t.Fatalf("root getattr failed with %v", err)
	}
	mode := fi.Mode()
	if (mode & os.ModeType) != os.ModeDir {
		t.Errorf("root is not a directory: %#v", fi)
	}
	if mode.Perm() != 0755 {
		t.Errorf("root has weird access mode: %v", mode.Perm())
	}
	switch stat := fi.Sys().(type) {
	case *syscall.Stat_t:
		if stat.Nlink != 1 {
			t.Errorf("root has wrong link count: %v", stat.Nlink)
		}
		if stat.Uid != uint32(syscall.Getuid()) {
			t.Errorf("root has wrong uid: %d", stat.Uid)
		}
		if stat.Gid != uint32(syscall.Getgid()) {
			t.Errorf("root has wrong gid: %d", stat.Gid)
		}
		if stat.Gid != uint32(syscall.Getgid()) {
			t.Errorf("root has wrong gid: %d", stat.Gid)
		}
	}

	dirf, err := os.Open(mnt.Dir)
	if err != nil {
		t.Fatalf("cannot open root dir: %v", err)
	}
	defer dirf.Close()
	names, err := dirf.Readdirnames(10)
	if err != nil && err != io.EOF {
		t.Fatalf("cannot list root dir: %v", err)
	}
	if len(names) > 0 {
		t.Errorf("unexpected content in root dir: %v", names)
	}
	err = dirf.Close()
	if err != nil {
		t.Fatalf("closing root dir failed: %v", err)
	}
}
Exemplo n.º 6
0
func TestSnapRecord(t *testing.T) {
	tmp := tempdir.New(t)
	defer tmp.Cleanup()
	app := bazfstestutil.NewApp(t, tmp.Subdir("data"))
	defer app.Close()
	bazfstestutil.CreateVolume(t, app, "default")

	func() {
		mnt := bazfstestutil.Mounted(t, app, "default")
		defer mnt.Close()

		// write test data
		sub := path.Join(mnt.Dir, "greetings")
		err := os.Mkdir(sub, 0755)
		if err != nil {
			t.Fatalf("cannot make directory: %v", err)
		}
		p := path.Join(sub, "hello")
		f, err := os.Create(p)
		if err != nil {
			t.Fatalf("cannot create hello: %v", err)
		}
		defer f.Close()
		_, err = f.Write([]byte(GREETING))
		if err != nil {
			t.Fatalf("cannot write to hello: %v", err)
		}
		err = f.Close()
		if err != nil {
			t.Fatalf("closing hello failed: %v", err)
		}

		// make a snapshot
		err = os.Mkdir(path.Join(mnt.Dir, ".snap", "mysnap"), 0755)
		if err != nil {
			t.Fatalf("snapshot failed: %v", err)
		}
	}()

	// mount again, to make sure cached dentry from Mkdir is flushed
	mnt := bazfstestutil.Mounted(t, app, "default")
	defer mnt.Close()

	// verify snapshot contents
	{
		data, err := ioutil.ReadFile(path.Join(mnt.Dir, ".snap", "mysnap", "greetings", "hello"))
		if err != nil {
			t.Fatalf("reading greeting failed: %v\n", err)
		}
		if g, e := string(data), GREETING; g != e {
			t.Errorf("wrong greeting: %q != %q", g, e)
		}
	}
}
Exemplo n.º 7
0
func benchmark(b *testing.B, fn func(b *testing.B, mnt string)) {
	tmp := tempdir.New(b)
	defer tmp.Cleanup()
	app := bazfstestutil.NewApp(b, tmp.Subdir("data"))
	defer app.Close()
	bazfstestutil.CreateVolume(b, app, "default")

	mnt := bazfstestutil.Mounted(b, app, "default")
	defer mnt.Close()

	fn(b, mnt.Dir)
}
Exemplo n.º 8
0
func TestRenameOverwrite(t *testing.T) {
	tmp := tempdir.New(t)
	defer tmp.Cleanup()
	app := bazfstestutil.NewApp(t, tmp.Subdir("data"))
	defer app.Close()
	bazfstestutil.CreateVolume(t, app, "default")

	mnt := bazfstestutil.Mounted(t, app, "default")
	defer mnt.Close()

	one := path.Join(mnt.Dir, "one")
	err := ioutil.WriteFile(one, []byte("foobar"), 0644)
	if err != nil {
		t.Fatalf("cannot create file: %v", err)
	}

	two := path.Join(mnt.Dir, "two")
	err = ioutil.WriteFile(two, []byte("xyzzy"), 0644)
	if err != nil {
		t.Fatalf("cannot create file: %v", err)
	}

	err = os.Rename(one, two)
	if err != nil {
		t.Fatalf("unexpected error from rename: %v", err)
	}

	dirf, err := os.Open(mnt.Dir)
	if err != nil {
		t.Fatalf("cannot open root dir: %v", err)
	}
	defer dirf.Close()
	names, err := dirf.Readdirnames(10)
	if err != nil && err != io.EOF {
		t.Fatalf("cannot list root dir: %v", err)
	}
	if len(names) != 1 {
		t.Errorf("unexpected content in root dir: %v", names)
	}
	if names[0] != "two" {
		t.Errorf("unexpected file in root dir: %q", names[0])
	}

	buf, err := ioutil.ReadFile(two)
	if err != nil {
		t.Fatalf("cannot read: %v", err)
	}
	if string(buf) != "foobar" {
		t.Fatalf("two content is wrong: %q", buf)
	}
}
Exemplo n.º 9
0
func TestTruncate(t *testing.T) {
	tmp := tempdir.New(t)
	defer tmp.Cleanup()
	app := bazfstestutil.NewApp(t, tmp.Subdir("data"))
	defer app.Close()
	bazfstestutil.CreateVolume(t, app, "default")

	mnt := bazfstestutil.Mounted(t, app, "default")
	defer mnt.Close()

	p := path.Join(mnt.Dir, "hello")
	f, err := os.Create(p)
	if err != nil {
		t.Fatalf("cannot create hello: %v", err)
	}
	defer f.Close()
	GREETING := "hello, world\n"
	n, err := f.Write([]byte(GREETING))
	if err != nil {
		t.Fatalf("cannot write to hello: %v", err)
	}
	if n != len(GREETING) {
		t.Fatalf("bad length write to hello: %d != %d", n, len(GREETING))
	}
	err = f.Close()
	if err != nil {
		t.Fatalf("closing hello failed: %v", err)
	}

	err = os.Truncate(p, 3)
	if err != nil {
		t.Fatalf("truncate failed: %v", err)
	}

	f2, err := os.Open(p)
	if err != nil {
		t.Fatalf("cannot open hello: %v", err)
	}
	defer f2.Close()
	buf, err := ioutil.ReadAll(f2)
	if err != nil {
		t.Fatalf("cannot read from hello: %v", err)
	}
	if g, e := string(buf), GREETING[:3]; g != e {
		t.Fatalf("hello content is wrong: %q != %q", g, e)
	}
	err = f2.Close()
	if err != nil {
		t.Fatalf("closing hello failed: %v", err)
	}
}
Exemplo n.º 10
0
func TestPersistentMkdir(t *testing.T) {
	tmp := tempdir.New(t)
	defer tmp.Cleanup()
	app := bazfstestutil.NewApp(t, tmp.Subdir("data"))
	defer app.Close()
	bazfstestutil.CreateVolume(t, app, "default")

	func() {
		mnt := bazfstestutil.Mounted(t, app, "default")
		defer mnt.Close()

		p := path.Join(mnt.Dir, "subdir")
		err := os.Mkdir(p, 0755)
		if err != nil {
			t.Fatalf("cannot create subdir: %v", err)
		}
	}()

	t.Logf("Unmounted to check persistency")
	time.Sleep(3 * time.Second)

	func() {
		mnt := bazfstestutil.Mounted(t, app, "default")
		defer mnt.Close()

		dirf, err := os.Open(mnt.Dir)
		if err != nil {
			t.Fatalf("cannot open root dir: %v", err)
		}
		defer dirf.Close()
		names, err := dirf.Readdirnames(10)
		if err != nil && err != io.EOF {
			t.Fatalf("cannot list root dir: %v", err)
		}
		if len(names) != 1 {
			t.Errorf("unexpected content in root dir: %v", names)
		}
		if len(names) > 0 && names[0] != "subdir" {
			t.Errorf("unexpected file in root dir: %q", names[0])
		}

		p := path.Join(mnt.Dir, "subdir")
		fi, err := os.Stat(p)
		if err != nil {
			t.Fatalf("cannot stat subdir: %v", err)
		}
		if !fi.IsDir() {
			t.Fatalf("subdir is not a directory: %v", fi)
		}
	}()
}
Exemplo n.º 11
0
func TestSnapList(t *testing.T) {
	tmp := tempdir.New(t)
	defer tmp.Cleanup()
	app := bazfstestutil.NewApp(t, tmp.Subdir("data"))
	defer app.Close()
	bazfstestutil.CreateVolume(t, app, "default")

	mnt := bazfstestutil.Mounted(t, app, "default")
	defer mnt.Close()

	// make some snapshots
	{
		err := os.Mkdir(path.Join(mnt.Dir, ".snap", "snapone"), 0755)
		if err != nil {
			t.Fatalf("snapshot failed: %v", err)
		}
		err = os.Mkdir(path.Join(mnt.Dir, ".snap", "snaptwo"), 0755)
		if err != nil {
			t.Fatalf("snapshot failed: %v", err)
		}
		err = os.Mkdir(path.Join(mnt.Dir, ".snap", "alphabetical"), 0755)
		if err != nil {
			t.Fatalf("snapshot failed: %v", err)
		}
	}

	// list snapshots
	{
		fis, err := ioutil.ReadDir(path.Join(mnt.Dir, ".snap"))
		if err != nil {
			t.Fatalf("listing snapshots failed: %v\n", err)
		}
		for _, fi := range fis {
			if fi.Mode() != os.ModeDir|0555 {
				t.Errorf("snapshot has bad mode: %q is %#o", fi.Name(), fi.Mode())
			}
			// TODO fi.ModTime()
		}
		if g, e := len(fis), 3; g != e {
			t.Fatalf("wrong number of snapshots: %d != %d: %v", g, e, fis)
		}
		expect := []string{"alphabetical", "snapone", "snaptwo"}
		for i, fi := range fis {
			if g, e := fi.Name(), expect[i]; g != e {
				t.Errorf("wrong snapshot entry: %q != %q", g, e)
			}
		}
	}
}
Exemplo n.º 12
0
func TestRemoveFileWhileOpen(t *testing.T) {
	tmp := tempdir.New(t)
	defer tmp.Cleanup()
	app := bazfstestutil.NewApp(t, tmp.Subdir("data"))
	defer app.Close()
	bazfstestutil.CreateVolume(t, app, "default")

	mnt := bazfstestutil.Mounted(t, app, "default")
	defer mnt.Close()

	p := path.Join(mnt.Dir, "hello")
	f, err := os.Create(p)
	if err != nil {
		t.Fatalf("cannot create hello: %v", err)
	}
	defer f.Close()

	err = os.Remove(p)
	if err != nil {
		t.Fatalf("cannot delete hello: %v", err)
	}

	// this must not resurrect a deleted file
	GREETING := "hello, world\n"
	n, err := f.Write([]byte(GREETING))
	if err != nil {
		t.Fatalf("cannot write to hello: %v", err)
	}
	if n != len(GREETING) {
		t.Fatalf("bad length write to hello: %d != %d", n, len(GREETING))
	}
	err = f.Close()
	if err != nil {
		t.Fatalf("closing hello failed: %v", err)
	}

	dirf, err := os.Open(mnt.Dir)
	if err != nil {
		t.Fatalf("cannot open root dir: %v", err)
	}
	defer dirf.Close()
	names, err := dirf.Readdirnames(10)
	if err != nil && err != io.EOF {
		t.Fatalf("cannot list root dir: %v", err)
	}
	if len(names) != 0 {
		t.Errorf("unexpected content in root dir: %v", names)
	}
}
Exemplo n.º 13
0
func TestRemoveNonexistent(t *testing.T) {
	tmp := tempdir.New(t)
	defer tmp.Cleanup()
	app := bazfstestutil.NewApp(t, tmp.Subdir("data"))
	defer app.Close()
	bazfstestutil.CreateVolume(t, app, "default")

	mnt := bazfstestutil.Mounted(t, app, "default")
	defer mnt.Close()

	p := path.Join(mnt.Dir, "does-not-exist")
	err := os.Remove(p)
	if err == nil {
		t.Fatalf("deleting non-existent file should have failed")
	}
	if !os.IsNotExist(err) {
		t.Fatalf("deleting non-existent file gave wrong error: %v", err)
	}
}
Exemplo n.º 14
0
func TestRenameOverwriteWhileOpen(t *testing.T) {
	tmp := tempdir.New(t)
	defer tmp.Cleanup()
	app := bazfstestutil.NewApp(t, tmp.Subdir("data"))
	defer app.Close()
	bazfstestutil.CreateVolume(t, app, "default")

	func() {
		mnt := bazfstestutil.Mounted(t, app, "default")
		defer mnt.Close()

		one := path.Join(mnt.Dir, "one")
		two := path.Join(mnt.Dir, "two")

		err := ioutil.WriteFile(one, []byte("foobar"), 0644)
		if err != nil {
			t.Fatalf("cannot create file: %v", err)
		}

		f, err := os.Create(two)
		if err != nil {
			t.Fatalf("cannot create hello: %v", err)
		}
		defer f.Close()

		err = os.Rename(one, two)
		if err != nil {
			t.Fatalf("unexpected error from rename: %v", err)
		}

		// this must not resurrect a deleted file
		GREETING := "hello, world\n"
		n, err := f.Write([]byte(GREETING))
		if err != nil {
			t.Fatalf("cannot write to hello: %v", err)
		}
		if n != len(GREETING) {
			t.Fatalf("bad length write to hello: %d != %d", n, len(GREETING))
		}
		err = f.Close()
		if err != nil {
			t.Fatalf("closing hello failed: %v", err)
		}
	}()

	t.Logf("Unmounted to flush cache")

	func() {
		mnt := bazfstestutil.Mounted(t, app, "default")
		defer mnt.Close()

		dirf, err := os.Open(mnt.Dir)
		if err != nil {
			t.Fatalf("cannot open root dir: %v", err)
		}
		defer dirf.Close()
		names, err := dirf.Readdirnames(10)
		if err != nil && err != io.EOF {
			t.Fatalf("cannot list root dir: %v", err)
		}
		if len(names) != 1 {
			t.Errorf("unexpected content in root dir: %v", names)
		}
		if names[0] != "two" {
			t.Errorf("unexpected file in root dir: %q", names[0])
		}

		two := path.Join(mnt.Dir, "two")

		buf, err := ioutil.ReadFile(two)
		if err != nil {
			t.Fatalf("cannot read: %v", err)
		}
		if string(buf) != "foobar" {
			t.Fatalf("two content is wrong: %q", buf)
		}
	}()
}
Exemplo n.º 15
0
func TestRename(t *testing.T) {
	tmp := tempdir.New(t)
	defer tmp.Cleanup()
	app := bazfstestutil.NewApp(t, tmp.Subdir("data"))
	defer app.Close()
	bazfstestutil.CreateVolume(t, app, "default")

	mnt := bazfstestutil.Mounted(t, app, "default")
	defer mnt.Close()

	p := path.Join(mnt.Dir, "hello")
	f, err := os.Create(p)
	if err != nil {
		t.Fatalf("cannot create hello: %v", err)
	}
	defer f.Close()
	GREETING := "hello, world\n"
	n, err := f.Write([]byte(GREETING))
	if err != nil {
		t.Fatalf("cannot write to hello: %v", err)
	}
	if n != len(GREETING) {
		t.Fatalf("bad length write to hello: %d != %d", n, len(GREETING))
	}
	err = f.Close()
	if err != nil {
		t.Fatalf("closing hello failed: %v", err)
	}

	p2 := path.Join(mnt.Dir, "bye")
	err = os.Rename(p, p2)
	if err != nil {
		t.Fatalf("unexpected error from rename: %v", err)
	}

	dirf, err := os.Open(mnt.Dir)
	if err != nil {
		t.Fatalf("cannot open root dir: %v", err)
	}
	defer dirf.Close()
	names, err := dirf.Readdirnames(10)
	if err != nil && err != io.EOF {
		t.Fatalf("cannot list root dir: %v", err)
	}
	if len(names) != 1 {
		t.Errorf("unexpected content in root dir: %v", names)
	}
	if names[0] != "bye" {
		t.Errorf("unexpected file in root dir: %q", names[0])
	}

	f, err = os.Open(p2)
	if err != nil {
		t.Fatalf("cannot open bye: %v", err)
	}
	defer f.Close()
	buf, err := ioutil.ReadAll(f)
	if err != nil {
		t.Fatalf("cannot read from bye: %v", err)
	}
	if string(buf) != GREETING {
		t.Fatalf("bye content is wrong: %q", buf)
	}
	err = f.Close()
	if err != nil {
		t.Fatalf("closing bye failed: %v", err)
	}
}
Exemplo n.º 16
0
func TestAppend(t *testing.T) {
	tmp := tempdir.New(t)
	defer tmp.Cleanup()
	app := bazfstestutil.NewApp(t, tmp.Subdir("data"))
	defer app.Close()
	bazfstestutil.CreateVolume(t, app, "default")

	mnt := bazfstestutil.Mounted(t, app, "default")
	defer mnt.Close()

	p := path.Join(mnt.Dir, "hello")
	f, err := os.Create(p)
	if err != nil {
		t.Fatalf("cannot create hello: %v", err)
	}
	defer f.Close()
	GREETING := "hello, world\n"
	n, err := f.Write([]byte(GREETING))
	if err != nil {
		t.Fatalf("cannot write to hello: %v", err)
	}
	if n != len(GREETING) {
		t.Fatalf("bad length write to hello: %d != %d", n, len(GREETING))
	}
	err = f.Close()
	if err != nil {
		t.Fatalf("closing hello failed: %v", err)
	}

	f2, err := os.OpenFile(p, os.O_WRONLY|os.O_APPEND, 0666)
	if err != nil {
		t.Fatalf("cannot open hello again: %v", err)
	}
	defer f2.Close()
	GREETING2 := "more\n"
	n, err = f2.Write([]byte(GREETING2))
	if err != nil {
		t.Fatalf("cannot append to hello: %v", err)
	}
	if n != len(GREETING2) {
		t.Fatalf("bad length append to hello: %d != %d", n, len(GREETING2))
	}
	err = f2.Close()
	if err != nil {
		t.Fatalf("closing hello failed: %v", err)
	}

	f3, err := os.Open(p)
	if err != nil {
		t.Fatalf("cannot open hello: %v", err)
	}
	defer f3.Close()
	buf, err := ioutil.ReadAll(f3)
	if err != nil {
		t.Fatalf("cannot read from hello: %v", err)
	}
	if string(buf) != GREETING+GREETING2 {
		t.Fatalf("hello content is wrong: %q", buf)
	}
	err = f3.Close()
	if err != nil {
		t.Fatalf("closing hello failed: %v", err)
	}
}