cloudinit/system/file.go
2014-10-17 15:36:22 -07:00

115 lines
2.7 KiB
Go

/*
Copyright 2014 CoreOS, Inc.
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 system
import (
"errors"
"fmt"
"io/ioutil"
"os"
"os/exec"
"path"
"strconv"
"github.com/coreos/coreos-cloudinit/config"
)
// File is a top-level structure which embeds its underlying configuration,
// config.File, and provides the system-specific Permissions().
type File struct {
config.File
}
func (f *File) Permissions() (os.FileMode, error) {
if f.RawFilePermissions == "" {
return os.FileMode(0644), nil
}
// Parse string representation of file mode as octal
perm, err := strconv.ParseInt(f.RawFilePermissions, 8, 32)
if err != nil {
return 0, errors.New("Unable to parse file permissions as octal integer")
}
return os.FileMode(perm), nil
}
func WriteFile(f *File, root string) (string, error) {
if f.Encoding != "" {
return "", fmt.Errorf("Unable to write file with encoding %s", f.Encoding)
}
fullpath := path.Join(root, f.Path)
dir := path.Dir(fullpath)
if err := EnsureDirectoryExists(dir); err != nil {
return "", err
}
perm, err := f.Permissions()
if err != nil {
return "", err
}
var tmp *os.File
// Create a temporary file in the same directory to ensure it's on the same filesystem
if tmp, err = ioutil.TempFile(dir, "cloudinit-temp"); err != nil {
return "", err
}
if err := ioutil.WriteFile(tmp.Name(), []byte(f.Content), perm); err != nil {
return "", err
}
if err := tmp.Close(); err != nil {
return "", err
}
// Ensure the permissions are as requested (since WriteFile can be affected by sticky bit)
if err := os.Chmod(tmp.Name(), perm); err != nil {
return "", err
}
if f.Owner != "" {
// We shell out since we don't have a way to look up unix groups natively
cmd := exec.Command("chown", f.Owner, tmp.Name())
if err := cmd.Run(); err != nil {
return "", err
}
}
if err := os.Rename(tmp.Name(), fullpath); err != nil {
return "", err
}
return fullpath, nil
}
func EnsureDirectoryExists(dir string) error {
info, err := os.Stat(dir)
if err == nil {
if !info.IsDir() {
return fmt.Errorf("%s is not a directory", dir)
}
} else {
err = os.MkdirAll(dir, 0755)
if err != nil {
return err
}
}
return nil
}