test: add basic integration tests

Signed-off-by: Justin Chadwell <me@jedevc.com>

vendor/github.com/containerd/continuity/driver/lchmod_unix.go

@@ -0,0 +1,35 @@
+//go:build darwin || freebsd || netbsd || openbsd || solaris
+// +build darwin freebsd netbsd openbsd solaris
+
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package driver
+
+import (
+	"os"
+
+	"golang.org/x/sys/unix"
+)
+
+// Lchmod changes the mode of a file not following symlinks.
+func (d *driver) Lchmod(path string, mode os.FileMode) error {
+	err := unix.Fchmodat(unix.AT_FDCWD, path, uint32(mode), unix.AT_SYMLINK_NOFOLLOW)
+	if err != nil {
+		err = &os.PathError{Op: "lchmod", Path: path, Err: err}
+	}
+	return err
+}