libgocryptfs/tests/matrix/matrix_test.go

// Tests run for (almost all) combinations of openssl, aessiv, plaintextnames.
package matrix

// File reading, writing, modification, truncate
//
// Runs everything four times, for all combinations of
// "-plaintextnames" and "-openssl".
//
// Test Matrix:
//                       openssl=true openssl=false
// plaintextnames=false  X            X
// plaintextnames=true   X            X

import (
	"bytes"
	"flag"
	"fmt"
	"io/ioutil"
	"os"
	"os/exec"
	"runtime"
	"sync"
	"syscall"
	"testing"

	"github.com/rfjakob/gocryptfs/internal/cryptocore"
	"github.com/rfjakob/gocryptfs/internal/nametransform"
	"github.com/rfjakob/gocryptfs/internal/syscallcompat"
	"github.com/rfjakob/gocryptfs/tests/test_helpers"
)

// Several tests need to be aware if plaintextnames is active or not, so make this
// a global variable
var testcase testcaseMatrix

type testcaseMatrix struct {
	plaintextnames bool
	openssl        string
	aessiv         bool
	raw64          bool
}

var matrix = []testcaseMatrix{
	// Normal
	{false, "auto", false, false},
	{false, "true", false, false},
	{false, "false", false, false},
	// Plaintextnames
	{true, "true", false, false},
	{true, "false", false, false},
	// AES-SIV (does not use openssl, no need to test permutations)
	{false, "auto", true, false},
	{true, "auto", true, false},
	// Raw64
	{false, "auto", false, true},
}

// This is the entry point for the tests
func TestMain(m *testing.M) {
	// Make "testing.Verbose()" return the correct value
	flag.Parse()
	for _, testcase = range matrix {
		if !cryptocore.HaveModernGoGCM && testcase.openssl != "true" {
			fmt.Printf("Skipping Go GCM variant, Go installation is too old")
			continue
		}
		if testcase.raw64 && !nametransform.HaveRaw64 {
			fmt.Printf("Skipping raw64 test, Go installation is too old")
			continue
		}
		if testing.Verbose() {
			fmt.Printf("matrix: testcase = %#v\n", testcase)
		}
		test_helpers.ResetTmpDir(!testcase.plaintextnames)
		opts := []string{"-zerokey"}
		opts = append(opts, fmt.Sprintf("-openssl=%v", testcase.openssl))
		opts = append(opts, fmt.Sprintf("-plaintextnames=%v", testcase.plaintextnames))
		opts = append(opts, fmt.Sprintf("-aessiv=%v", testcase.aessiv))
		opts = append(opts, fmt.Sprintf("-raw64=%v", testcase.raw64))
		test_helpers.MountOrExit(test_helpers.DefaultCipherDir, test_helpers.DefaultPlainDir, opts...)
		r := m.Run()
		test_helpers.UnmountPanic(test_helpers.DefaultPlainDir)
		if r != 0 {
			os.Exit(r)
		}
	}
	os.Exit(0)
}

// Write "n" zero bytes to filename "fn", read again, compare hash
func testWriteN(t *testing.T, fn string, n int) string {
	file, err := os.Create(test_helpers.DefaultPlainDir + "/" + fn)
	if err != nil {
		t.Fatal(err)
	}

	d := make([]byte, n)
	written, err := file.Write(d)
	if err != nil || written != len(d) {
		t.Errorf("err=\"%s\", written=%d", err, written)
	}
	err = file.Close()
	if err != nil {
		t.Error(err)
	}

	test_helpers.VerifySize(t, test_helpers.DefaultPlainDir+"/"+fn, n)

	hashWant := test_helpers.Md5hex(d)

	hashActual := test_helpers.Md5fn(test_helpers.DefaultPlainDir + "/" + fn)

	if hashActual != hashWant {
		t.Errorf("Wrong content, hashWant=%s hashActual=%s", hashWant, hashActual)
	}

	return hashActual
}

func TestWrite10(t *testing.T) {
	testWriteN(t, "10", 10)
}

func TestWrite100(t *testing.T) {
	testWriteN(t, "100", 100)
}

func TestWrite1M(t *testing.T) {
	testWriteN(t, "1M", 1024*1024)
}

func TestWrite100x100(t *testing.T) {
	hashWant := testWriteN(t, "100x100", 100)
	// Read and check 100 times to catch race conditions
	var i int
	for i = 0; i < 100; i++ {
		hashActual := test_helpers.Md5fn(test_helpers.DefaultPlainDir + "/100")
		if hashActual != hashWant {
			fmt.Printf("Read corruption in loop #%d\n", i)
			t.FailNow()
		} else {
			//fmt.Print(".")
		}
	}
}

// Hint for calculating reference md5sums:
// dd if=/dev/zero count=1 bs=XYZ | md5sum
func TestTruncate(t *testing.T) {
	fn := test_helpers.DefaultPlainDir + "/truncate"
	file, err := os.Create(fn)
	if err != nil {
		t.FailNow()
	}
	// Grow to two blocks
	file.Truncate(7000)
	test_helpers.VerifySize(t, fn, 7000)
	if md5 := test_helpers.Md5fn(fn); md5 != "95d4ec7038e3e4fdbd5f15c34c3f0b34" {
		t.Errorf("Wrong md5 %s", md5)
	}
	// Shrink - needs RMW
	file.Truncate(6999)
	test_helpers.VerifySize(t, fn, 6999)
	if md5 := test_helpers.Md5fn(fn); md5 != "35fd15873ec6c35380064a41b9b9683b" {
		t.Errorf("Wrong md5 %s", md5)
	}
	// Shrink to one partial block
	file.Truncate(465)
	test_helpers.VerifySize(t, fn, 465)
	if md5 := test_helpers.Md5fn(fn); md5 != "a1534d6e98a6b21386456a8f66c55260" {
		t.Errorf("Wrong md5 %s", md5)
	}
	// Grow to exactly one block
	file.Truncate(4096)
	test_helpers.VerifySize(t, fn, 4096)
	if md5 := test_helpers.Md5fn(fn); md5 != "620f0b67a91f7f74151bc5be745b7110" {
		t.Errorf("Wrong md5 %s", md5)
	}
	// Truncate to zero
	file.Truncate(0)
	test_helpers.VerifySize(t, fn, 0)
	// Grow to 10MB (creates file holes)
	var sz int
	sz = 10 * 1024 * 1024
	file.Truncate(int64(sz))
	test_helpers.VerifySize(t, fn, sz)
	if md5 := test_helpers.Md5fn(fn); md5 != "f1c9645dbc14efddc7d8a322685f26eb" {
		t.Errorf("Wrong md5 %s", md5)
	}
	// Grow to 10MB + 100B (partial block on the end)
	sz = 10*1024*1024 + 100
	file.Truncate(int64(sz))
	test_helpers.VerifySize(t, fn, sz)
	if md5 := test_helpers.Md5fn(fn); md5 != "c23ea79b857b91a7ff07c6ecf185f1ca" {
		t.Errorf("Wrong md5 %s", md5)
	}
	// Grow to 20MB (creates file holes, partial block on the front)
	sz = 20 * 1024 * 1024
	file.Truncate(int64(sz))
	test_helpers.VerifySize(t, fn, sz)
	if md5 := test_helpers.Md5fn(fn); md5 != "8f4e33f3dc3e414ff94e5fb6905cba8c" {
		t.Errorf("Wrong md5 %s", md5)
	}
}

const (
	// From man statfs
	TMPFS_MAGIC      = 0x01021994
	EXT4_SUPER_MAGIC = 0xef53
)

// isWellKnownFS decides if the backing filesystem is well-known.
// The expected allocated sizes are only valid on tmpfs and ext4. btrfs
// gives different results, but that's not an error.
func isWellKnownFS(fn string) bool {
	var fs syscall.Statfs_t
	err := syscall.Statfs(fn, &fs)
	if err != nil {
		panic(err)
	}
	if fs.Type == EXT4_SUPER_MAGIC || fs.Type == TMPFS_MAGIC {
		return true
	}
	return false
}

const FALLOC_DEFAULT = 0x00
const FALLOC_FL_KEEP_SIZE = 0x01

func TestFallocate(t *testing.T) {
	if runtime.GOOS == "darwin" {
		t.Skipf("OSX does not support fallocate")
	}
	fn := test_helpers.DefaultPlainDir + "/fallocate"
	file, err := os.Create(fn)
	if err != nil {
		t.FailNow()
	}
	wellKnown := isWellKnownFS(test_helpers.DefaultCipherDir)
	fd := int(file.Fd())
	nBytes := test_helpers.Du(t, fd)
	if nBytes != 0 {
		t.Fatalf("Empty file has %d bytes", nBytes)
	}
	// Allocate 30 bytes, keep size
	// gocryptfs ||        (0 blocks)
	//      ext4 |  d   |  (1 block)
	err = syscallcompat.Fallocate(fd, FALLOC_FL_KEEP_SIZE, 0, 30)
	if err != nil {
		t.Error(err)
	}
	var want int64
	nBytes = test_helpers.Du(t, fd)
	want = 4096
	if nBytes != want {
		t.Errorf("Expected %d allocated bytes, have %d", want, nBytes)
	}
	test_helpers.VerifySize(t, fn, 0)
	// Three ciphertext blocks. The middle one should be a file hole.
	// gocryptfs |  h   |   h  | d|   (1 block)
	//      ext4 |  d  |  h  |  d  |  (2 blocks)
	// (Note that gocryptfs blocks are slightly bigger than the ext4 blocks,
	// but the last one is partial)
	err = file.Truncate(9000)
	if err != nil {
		t.Fatal(err)
	}
	nBytes = test_helpers.Du(t, fd)
	want = 2 * 4096
	if wellKnown && nBytes != want {
		t.Errorf("Expected %d allocated bytes, have %d", want, nBytes)
	}
	if md5 := test_helpers.Md5fn(fn); md5 != "5420afa22f6423a9f59e669540656bb4" {
		t.Errorf("Wrong md5 %s", md5)
	}
	// Allocate the whole file space
	// gocryptfs |  h   |   h  | d|   (1 block)
	//      ext4 |  d  |  d  |  d  |  (3 blocks
	err = syscallcompat.Fallocate(fd, FALLOC_DEFAULT, 0, 9000)
	if err != nil {
		t.Fatal(err)
	}
	nBytes = test_helpers.Du(t, fd)
	want = 3 * 4096
	if nBytes != want {
		t.Errorf("Expected %d allocated bytes, have %d", want, nBytes)
	}
	// Neither apparent size nor content should have changed
	test_helpers.VerifySize(t, fn, 9000)
	if md5 := test_helpers.Md5fn(fn); md5 != "5420afa22f6423a9f59e669540656bb4" {
		t.Errorf("Wrong md5 %s", md5)
	}

	// Partial block on the end. The first ext4 block is dirtied by the header.
	// gocryptfs |  h   |   h  | d|   (1 block)
	//      ext4 |  d  |  h  |  d  |  (2 blocks)
	file.Truncate(0)
	file.Truncate(9000)
	nBytes = test_helpers.Du(t, fd)
	want = 2 * 4096
	if wellKnown && nBytes != want {
		t.Errorf("Expected %d allocated bytes, have %d", want, nBytes)
	}
	// Allocate 10 bytes in the second block
	// gocryptfs |  h   |   h  | d|   (1 block)
	//      ext4 |  d  |  d  |  d  |  (3 blocks)
	syscallcompat.Fallocate(fd, FALLOC_DEFAULT, 5000, 10)
	nBytes = test_helpers.Du(t, fd)
	want = 3 * 4096
	if wellKnown && nBytes != want {
		t.Errorf("Expected %d allocated bytes, have %d", want, nBytes)
	}
	// Neither apparent size nor content should have changed
	test_helpers.VerifySize(t, fn, 9000)
	if md5 := test_helpers.Md5fn(fn); md5 != "5420afa22f6423a9f59e669540656bb4" {
		t.Errorf("Wrong md5 %s", md5)
	}
	// Grow the file to 4 blocks
	// gocryptfs |  h   |  h   |  d   |d|  (2 blocks)
	//      ext4 |  d  |  d  |  d  |  d  | (4 blocks)
	syscallcompat.Fallocate(fd, FALLOC_DEFAULT, 15000, 10)
	nBytes = test_helpers.Du(t, fd)
	want = 4 * 4096
	if wellKnown && nBytes != want {
		t.Errorf("Expected %d allocated bytes, have %d", want, nBytes)
	}
	test_helpers.VerifySize(t, fn, 15010)
	if md5 := test_helpers.Md5fn(fn); md5 != "c4c44c7a41ab7798a79d093eb44f99fc" {
		t.Errorf("Wrong md5 %s", md5)
	}
	// Shrinking a file using fallocate should have no effect
	for _, off := range []int64{0, 10, 2000, 5000} {
		for _, sz := range []int64{0, 1, 42, 6000} {
			syscallcompat.Fallocate(fd, FALLOC_DEFAULT, off, sz)
			test_helpers.VerifySize(t, fn, 15010)
			if md5 := test_helpers.Md5fn(fn); md5 != "c4c44c7a41ab7798a79d093eb44f99fc" {
				t.Errorf("Wrong md5 %s", md5)
			}
		}
	}
	// Cleanup
	file.Close()
	syscall.Unlink(fn)
	if !wellKnown {
		// Even though most tests have been executed still, inform the user
		// that some were disabled
		t.Skipf("backing fs is not ext4 or tmpfs, skipped some disk-usage checks\n")
	}
}

func TestAppend(t *testing.T) {
	fn := test_helpers.DefaultPlainDir + "/append"
	file, err := os.Create(fn)
	if err != nil {
		t.FailNow()
	}
	data := []byte("testdata123456789") // length 17
	var buf bytes.Buffer
	var hashWant string
	for i := 0; i <= 500; i++ {
		file.Write(data)
		buf.Write(data)
		hashWant = test_helpers.Md5hex(buf.Bytes())
		hashActual := test_helpers.Md5fn(fn)
		if hashWant != hashActual {
			t.FailNow()
		}
	}

	// Overwrite with the same data
	// Hash must stay the same
	file.Seek(0, 0)
	for i := 0; i <= 500; i++ {
		file.Write(data)
		hashActual := test_helpers.Md5fn(fn)
		if hashWant != hashActual {
			t.FailNow()
		}
	}
}

// Create a file with holes by writing to offset 0 (block #0) and
// offset 4096 (block #1).
func TestFileHoles(t *testing.T) {
	fn := test_helpers.DefaultPlainDir + "/fileholes"
	file, err := os.Create(fn)
	if err != nil {
		t.Errorf("file create failed")
	}
	foo := []byte("foo")
	file.Write(foo)
	file.WriteAt(foo, 4096)
	_, err = ioutil.ReadFile(fn)
	if err != nil {
		t.Error(err)
	}
}

// sContains - does the slice of strings "haystack" contain "needle"?
func sContains(haystack []string, needle string) bool {
	for _, element := range haystack {
		if element == needle {
			return true
		}
	}
	return false
}

func TestRmwRace(t *testing.T) {

	runtime.GOMAXPROCS(10)

	fn := test_helpers.DefaultPlainDir + "/rmwrace"
	f1, err := os.Create(fn)
	if err != nil {
		t.Fatalf("file create failed")
	}
	f2, err := os.Create(fn)
	if err != nil {
		t.Fatalf("file create failed")
	}

	oldBlock := bytes.Repeat([]byte("o"), 4096)

	newBlock := bytes.Repeat([]byte("n"), 4096)

	shortBlock := bytes.Repeat([]byte("s"), 16)

	mergedBlock := make([]byte, 4096)
	copy(mergedBlock, newBlock)
	copy(mergedBlock[4080:], shortBlock)

	goodMd5 := make(map[string]int)

	for i := 0; i < 1000; i++ {
		// Reset to [ooooooooo]
		_, err = f1.WriteAt(oldBlock, 0)
		if err != nil {
			t.Fatalf("Write failed")
		}

		var wg sync.WaitGroup
		wg.Add(2)

		// Write to the end of the file, [....ssss]
		go func() {
			f1.WriteAt(shortBlock, 4080)
			wg.Done()
		}()

		// Overwrite to [nnnnnnn]
		go func() {
			f2.WriteAt(newBlock, 0)
			wg.Done()
		}()

		wg.Wait()

		// The file should be either:
		// [nnnnnnnnnn] (md5: 6c1660fdabccd448d1359f27b3db3c99) or
		// [nnnnnnssss] (md5: da885006a6a284530a427c73ce1e5c32)
		// but it must not be
		// [oooooossss]

		buf, _ := ioutil.ReadFile(fn)
		m := test_helpers.Md5hex(buf)
		goodMd5[m] = goodMd5[m] + 1

		/*
			if m == "6c1660fdabccd448d1359f27b3db3c99" {
				fmt.Println(hex.Dump(buf))
				t.FailNow()
			}
		*/
	}
}

// With "--plaintextnames", the name "/gocryptfs.conf" is reserved.
// Otherwise there should be no restrictions.
func TestFiltered(t *testing.T) {
	filteredFile := test_helpers.DefaultPlainDir + "/gocryptfs.conf"
	file, err := os.Create(filteredFile)
	if testcase.plaintextnames && err == nil {
		t.Errorf("should have failed but didn't")
	} else if !testcase.plaintextnames && err != nil {
		t.Error(err)
	}
	file.Close()

	err = os.Remove(filteredFile)
	if testcase.plaintextnames && err == nil {
		t.Errorf("should have failed but didn't")
	} else if !testcase.plaintextnames && err != nil {
		t.Error(err)
	}
}

func TestFilenameEncryption(t *testing.T) {
	file, err := os.Create(test_helpers.DefaultPlainDir + "/TestFilenameEncryption.txt")
	file.Close()
	if err != nil {
		t.Fatal(err)
	}
	_, err = os.Stat(test_helpers.DefaultCipherDir + "/TestFilenameEncryption.txt")
	if testcase.plaintextnames && err != nil {
		t.Errorf("plaintextnames not working: %v", err)
	} else if !testcase.plaintextnames && err == nil {
		t.Errorf("file name encryption not working")
	}
}

// Test Mkdir and Rmdir
func testMkdirRmdir(t *testing.T) {
	test_helpers.TestMkdirRmdir(t, test_helpers.DefaultPlainDir)
}

// Test Rename
func testRename(t *testing.T) {
	test_helpers.TestRename(t, test_helpers.DefaultPlainDir)
}

// Overwrite an empty directory with another directory
func TestDirOverwrite(t *testing.T) {
	dir1 := test_helpers.DefaultPlainDir + "/DirOverwrite1"
	dir2 := test_helpers.DefaultPlainDir + "/DirOverwrite2"
	err := os.Mkdir(dir1, 0777)
	if err != nil {
		t.Fatal(err)
	}
	err = os.Mkdir(dir2, 0777)
	if err != nil {
		t.Fatal(err)
	}
	err = os.Rename(dir1, dir2)
	if err != nil {
		t.Fatal(err)
	}
}

func TestLongNames(t *testing.T) {
	fi, err := ioutil.ReadDir(test_helpers.DefaultCipherDir)
	if err != nil {
		t.Fatal(err)
	}
	cnt1 := len(fi)
	wd := test_helpers.DefaultPlainDir + "/"
	// Create file with long name
	n255x := string(bytes.Repeat([]byte("x"), 255))
	f, err := os.Create(wd + n255x)
	if err != nil {
		t.Fatalf("Could not create n255x: %v", err)
	}
	f.Close()
	if !test_helpers.VerifyExistence(wd + n255x) {
		t.Errorf("n255x is not in directory listing")
	}
	// Rename long to long
	n255y := string(bytes.Repeat([]byte("y"), 255))
	err = os.Rename(wd+n255x, wd+n255y)
	if err != nil {
		t.Fatalf("Could not rename n255x to n255y: %v", err)
	}
	if !test_helpers.VerifyExistence(wd + n255y) {
		t.Errorf("n255y is not in directory listing")
	}
	// Rename long to short
	err = os.Rename(wd+n255y, wd+"short")
	if err != nil {
		t.Fatalf("Could not rename n255y to short: %v", err)
	}
	if !test_helpers.VerifyExistence(wd + "short") {
		t.Errorf("short is not in directory listing")
	}
	// Rename short to long
	err = os.Rename(wd+"short", wd+n255x)
	if err != nil {
		t.Fatalf("Could not rename short to n255x: %v", err)
	}
	if !test_helpers.VerifyExistence(wd + n255x) {
		t.Errorf("255x is not in directory listing II")
	}
	// Unlink
	err = syscall.Unlink(wd + n255x)
	if err != nil {
		t.Fatalf("Could not unlink n255x: %v", err)
	}
	if test_helpers.VerifyExistence(wd + n255x) {
		t.Errorf("n255x still there after unlink")
	}
	// Long symlink
	n255s := string(bytes.Repeat([]byte("s"), 255))
	err = os.Symlink("/", wd+n255s)
	if err != nil {
		t.Fatal(err)
	}
	if !test_helpers.VerifyExistence(wd + n255s) {
		t.Errorf("n255s is not in directory listing")
	}
	err = syscall.Unlink(wd + n255s)
	if err != nil {
		t.Error(err)
	}
	// Long dir
	n255d := string(bytes.Repeat([]byte("d"), 255))
	err = os.Mkdir(wd+n255d, 0777)
	if err != nil {
		t.Fatal(err)
	}
	err = syscall.Rmdir(wd + n255d)
	if err != nil {
		t.Error(err)
	}
	// Check for orphaned files
	fi, err = ioutil.ReadDir(test_helpers.DefaultCipherDir)
	if err != nil {
		t.Fatal(err)
	}
	cnt2 := len(fi)
	if cnt1 != cnt2 {
		t.Errorf("Leftover files, cnt1=%d cnt2=%d", cnt1, cnt2)
	}
}

// Create hard link with long name.
// This was broken up to v1.2.
func TestLongLink(t *testing.T) {
	wd := test_helpers.DefaultPlainDir + "/"
	target := wd + "TestLongLink.target"
	f, err := os.Create(target)
	if err != nil {
		t.Fatalf("%v", err)
	}
	f.Close()
	l255 := string(bytes.Repeat([]byte("l"), 255))
	err = os.Link(target, wd+l255)
	if err != nil {
		t.Error(err)
	}
}

func TestLchown(t *testing.T) {
	name := test_helpers.DefaultPlainDir + "/symlink"
	err := os.Symlink("/target/does/not/exist", name)
	if err != nil {
		t.Fatal(err)
	}
	err = os.Chown(name, os.Getuid(), os.Getgid())
	if err == nil {
		t.Error("Chown on dangling symlink should fail")
	}
	err = os.Lchown(name, os.Getuid(), os.Getgid())
	if err != nil {
		t.Error(err)
	}
}

// Set nanoseconds by path, symlink
func TestUtimesNanoSymlink(t *testing.T) {
	path := test_helpers.DefaultPlainDir + "/utimesnano_symlink"
	err := os.Symlink("/some/nonexisting/file", path)
	if err != nil {
		t.Fatal(err)
	}
	// syscall.UtimesNano does not provide a way to pass AT_SYMLINK_NOFOLLOW,
	// so we call the external utility "touch", which does.
	cmd := exec.Command("touch", "--no-dereference", path)
	cmd.Stderr = os.Stderr
	cmd.Stdout = os.Stdout
	err = cmd.Run()
	if err != nil {
		t.Error(err)
	}
}

type utimesTestcaseStruct struct {
	// Input atime and mtime
	in [2]syscall.Timespec
	// Expected output atime and mtime
	out [2]syscall.Timespec
}

func compareUtimes(want [2]syscall.Timespec, actual [2]syscall.Timespec) error {
	tsNames := []string{"atime", "mtime"}
	for i := range want {
		if want[i].Sec != actual[i].Sec {
			return fmt.Errorf("Wrong %s seconds: want=%d actual=%d", tsNames[i], want[i].Sec, actual[i].Sec)
		}
		if want[i].Nsec != actual[i].Nsec {
			return fmt.Errorf("Wrong %s nanoseconds: want=%d actual=%d", tsNames[i], want[i].Nsec, actual[i].Nsec)
		}
	}
	return nil
}

const _UTIME_OMIT = ((1 << 30) - 2)

// doTestUtimesNano verifies that setting nanosecond-precision times on "path"
// works correctly. Pass "/proc/self/fd/N" to test a file descriptor.
func doTestUtimesNano(t *testing.T, path string) {
	utimeTestcases := []utimesTestcaseStruct{
		{
			in:  [2]syscall.Timespec{{Sec: 50, Nsec: 0}, {Sec: 50, Nsec: 0}},
			out: [2]syscall.Timespec{{Sec: 50, Nsec: 0}, {Sec: 50, Nsec: 0}},
		},
		{
			in:  [2]syscall.Timespec{{Sec: 1, Nsec: 2}, {Sec: 3, Nsec: 4}},
			out: [2]syscall.Timespec{{Sec: 1, Nsec: 2}, {Sec: 3, Nsec: 4}},
		},
		{
			in:  [2]syscall.Timespec{{Sec: 7, Nsec: 8}, {Sec: 99, Nsec: _UTIME_OMIT}},
			out: [2]syscall.Timespec{{Sec: 7, Nsec: 8}, {Sec: 3, Nsec: 4}},
		},
		{
			in:  [2]syscall.Timespec{{Sec: 99, Nsec: _UTIME_OMIT}, {Sec: 5, Nsec: 6}},
			out: [2]syscall.Timespec{{Sec: 7, Nsec: 8}, {Sec: 5, Nsec: 6}},
		},
	}
	for i, tc := range utimeTestcases {
		err := syscall.UtimesNano(path, tc.in[:])
		if err != nil {
			t.Fatal(err)
		}
		var st syscall.Stat_t
		err = syscall.Stat(path, &st)
		if err != nil {
			t.Fatal(err)
		}
		err = compareUtimes(tc.out, extractAtimeMtime(st))
		if err != nil {
			t.Errorf("Testcase %d: %v", i, err)
		}
	}
}

// Set nanoseconds by path, normal file
func TestUtimesNano(t *testing.T) {
	path := test_helpers.DefaultPlainDir + "/utimesnano"
	err := ioutil.WriteFile(path, []byte("foobar"), 0600)
	if err != nil {
		t.Fatal(err)
	}
	doTestUtimesNano(t, path)
}

// Set nanoseconds by fd
func TestUtimesNanoFd(t *testing.T) {
	path := test_helpers.DefaultPlainDir + "/utimesnanofd"
	f, err := os.Create(path)
	if err != nil {
		t.Fatal(err)
	}
	procPath := fmt.Sprintf("/proc/self/fd/%d", f.Fd())
	doTestUtimesNano(t, procPath)
}