Fix #1020 os.Chtimes invalid arg

The zero value of time.Time is not a valid argument to os.Chtimes
because of the syscall that os.Chtimes calls. Instead we update the zero
value of time.Time to the zero value of Unix Epoch

pkg/util/fs_util.go

@@ -298,9 +298,7 @@ func ExtractFile(dest string, hdr *tar.Header, tr io.Reader) error {
 			return err
 		}
 
-		// We set AccessTime because its a required arg but we only care about
-		// ModTime. The file will get accessed again so AccessTime will change.
-		if err := os.Chtimes(path, hdr.AccessTime, hdr.ModTime); err != nil {
+		if err = setFileTimes(path, hdr.AccessTime, hdr.ModTime); err != nil {
 			return err
 		}
 
@@ -737,6 +735,34 @@ func setFilePermissions(path string, mode os.FileMode, uid, gid int) error {
 	return os.Chmod(path, mode)
 }
 
+func setFileTimes(path string, aTime, mTime time.Time) error {
+	// The zero value of time.Time is not a valid argument to os.Chtimes as it cannot be
+	// converted into a valid argument to the syscall that os.Chtimes uses. If mTime or
+	// aTime are zero we convert them to the zero value for Unix Epoch.
+	if mTime.IsZero() {
+		logrus.Tracef("mod time for %s is zero, converting to zero for epoch", path)
+		mTime = time.Unix(0, 0)
+	}
+
+	if aTime.IsZero() {
+		logrus.Tracef("access time for %s is zero, converting to zero for epoch", path)
+		aTime = time.Unix(0, 0)
+	}
+
+	// We set AccessTime because its a required arg but we only care about
+	// ModTime. The file will get accessed again so AccessTime will change.
+	if err := os.Chtimes(path, aTime, mTime); err != nil {
+		return errors.Wrapf(
+			err,
+			"couldn't modify times: atime %v mtime %v",
+			aTime,
+			mTime,
+		)
+	}
+
+	return nil
+}
+
 // CreateTargetTarfile creates target tar file for downloading the context file.
 // Make directory if directory does not exist
 func CreateTargetTarfile(tarpath string) (*os.File, error) {

pkg/util/fs_util_test.go

@@ -1314,3 +1314,57 @@ func TestUpdateWhitelist(t *testing.T) {
 		})
 	}
 }
+
+func Test_setFileTimes(t *testing.T) {
+	testDir, err := ioutil.TempDir("", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	defer os.RemoveAll(testDir)
+
+	p := filepath.Join(testDir, "foo.txt")
+
+	if err := ioutil.WriteFile(p, []byte("meow"), 0777); err != nil {
+		t.Fatal(err)
+	}
+
+	type testcase struct {
+		desc  string
+		path  string
+		aTime time.Time
+		mTime time.Time
+	}
+
+	testCases := []testcase{
+		{
+			desc: "zero for mod and access",
+			path: p,
+		},
+		{
+			desc:  "zero for mod",
+			path:  p,
+			aTime: time.Now(),
+		},
+		{
+			desc:  "zero for access",
+			path:  p,
+			mTime: time.Now(),
+		},
+		{
+			desc:  "both non-zero",
+			path:  p,
+			mTime: time.Now(),
+			aTime: time.Now(),
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.desc, func(t *testing.T) {
+			err := setFileTimes(tc.path, tc.aTime, tc.mTime)
+			if err != nil {
+				t.Errorf("expected err to be nil not %s", err)
+			}
+		})
+	}
+}