/
cloudinit.go
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/
cloudinit.go
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// Copyright (c) 2019 SAP SE or an SAP affiliate company. All rights reserved. This file is licensed under the Apache Software License, v. 2 except as noted otherwise in the LICENSE file
//
// 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 cloudinit
import (
"bytes"
"compress/gzip"
"encoding/base64"
"fmt"
"io/ioutil"
)
// FileCodecID is the id of a FileCodec for cloud-init scripts.
type FileCodecID string
const (
// B64FileCodecID is the base64 file codec id.
B64FileCodecID FileCodecID = "b64"
// GZIPFileCodecID is the gzip file codec id.
GZIPFileCodecID FileCodecID = "gzip"
// GZIPB64FileCodecID is the gzip combined with base64 codec id.
GZIPB64FileCodecID FileCodecID = "gzip+b64"
)
var validFileCodecIDs = map[FileCodecID]struct{}{
B64FileCodecID: {},
GZIPFileCodecID: {},
GZIPB64FileCodecID: {},
}
// FileCodec is a codec to en- and decode data in cloud-init scripts with.j
type FileCodec interface {
Encode([]byte) ([]byte, error)
Decode([]byte) ([]byte, error)
}
var (
// B64FileCodec is the base64 FileCodec.
B64FileCodec FileCodec = b64FileCodec{}
// GZIPFileCodec is the gzip FileCodec.
GZIPFileCodec FileCodec = gzipFileCodec{}
)
type b64FileCodec struct{}
var encoding = base64.StdEncoding
func (b64FileCodec) Encode(data []byte) ([]byte, error) {
dst := make([]byte, encoding.EncodedLen(len(data)))
encoding.Encode(dst, data)
return dst, nil
}
func (b64FileCodec) Decode(data []byte) ([]byte, error) {
dst := make([]byte, encoding.DecodedLen(len(data)))
n, err := encoding.Decode(dst, data)
return dst[:n], err
}
type gzipFileCodec struct{}
func (gzipFileCodec) Encode(data []byte) ([]byte, error) {
var out bytes.Buffer
w := gzip.NewWriter(&out)
if _, err := w.Write(data); err != nil {
return nil, err
}
if err := w.Close(); err != nil {
return nil, err
}
return out.Bytes(), nil
}
func (gzipFileCodec) Decode(data []byte) ([]byte, error) {
r, err := gzip.NewReader(bytes.NewReader(data))
if err != nil {
return nil, err
}
defer func() { _ = r.Close() }()
return ioutil.ReadAll(r)
}
// ParseFileCodecID tries to parse a string into a FileCodecID.
func ParseFileCodecID(s string) (FileCodecID, error) {
id := FileCodecID(s)
if _, ok := validFileCodecIDs[id]; !ok {
return id, fmt.Errorf("invalid file codec id %q", id)
}
return id, nil
}
var fileCodecIDToFileCodec = map[FileCodecID]FileCodec{
B64FileCodecID: B64FileCodec,
GZIPFileCodecID: GZIPFileCodec,
}
// FileCodecForID retrieves the FileCodec for the given FileCodecID.
func FileCodecForID(id FileCodecID) FileCodec {
return fileCodecIDToFileCodec[id]
}
// Decode decodes the given data using the codec from resolving the given codecIDString.
// It's a shorthand for parsing the FileCodecID and calling the `Decode` method on the obtained
// FileCodec.
func Decode(codecIDString string, data []byte) ([]byte, error) {
id, err := ParseFileCodecID(codecIDString)
if err != nil {
return nil, err
}
return FileCodecForID(id).Decode(data)
}