agent/fileutil/harden.go

package fileutil

import (
	"fmt"
	"io/ioutil"
	"os"
	"path/filepath"
)

const (
	RWPermission = 0600
)

// HardenedWriteFile calls ioutil.WriteFile and guarantees a hardened permission
// control. If the file already exists, it hardens the permissions before
// writing data to it.
func HardenedWriteFile(filename string, data []byte) (err error) {

	if _, err = os.Stat(filename); err != nil {
		if os.IsNotExist(err) {
			f, err := os.Create(filename)
			if err != nil {
				return fmt.Errorf("Failed to create the file, %s", err)
			}
			defer f.Close()
		} else {
			return
		}
	}

	if err = Harden(filename); err != nil {
		return
	}

	if err = ioutil.WriteFile(filename, data, RWPermission); err != nil {
		return
	}

	return
}

// RecursivelyHarden the files and directory under the specified path.
func RecursivelyHarden(path string) error {
	return filepath.Walk(path, func(p string, fi os.FileInfo, err error) error {
		return Harden(p)
	})
}