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minio/pkg/quick/encoding.go

141 lines
3.9 KiB

/*
* Quick - Quick key value store for config files and persistent state files
*
* Quick (C) 2017 Minio, 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 quick
import (
"bytes"
"encoding/json"
"fmt"
"io/ioutil"
"os"
"path/filepath"
"runtime"
"strings"
yaml "gopkg.in/yaml.v2"
)
// ConfigEncoding is a generic interface which
// marshal/unmarshal configuration.
type ConfigEncoding interface {
Unmarshal([]byte, interface{}) error
Marshal(interface{}) ([]byte, error)
}
// YAML encoding implements ConfigEncoding
type yamlEncoding struct{}
func (y yamlEncoding) Unmarshal(b []byte, v interface{}) error {
return yaml.Unmarshal(b, v)
}
func (y yamlEncoding) Marshal(v interface{}) ([]byte, error) {
return yaml.Marshal(v)
}
// JSON encoding implements ConfigEncoding
type jsonEncoding struct{}
func (j jsonEncoding) Unmarshal(b []byte, v interface{}) error {
err := json.Unmarshal(b, v)
if err != nil {
// Try to return a sophisticated json error message if possible
switch jerr := err.(type) {
case *json.SyntaxError:
return fmt.Errorf("Unable to parse JSON schema due to a syntax error at '%s'",
FormatJSONSyntaxError(bytes.NewReader(b), jerr.Offset))
case *json.UnmarshalTypeError:
return fmt.Errorf("Unable to parse JSON, type '%v' cannot be converted into the Go '%v' type",
jerr.Value, jerr.Type)
}
return err
}
return nil
}
func (j jsonEncoding) Marshal(v interface{}) ([]byte, error) {
return json.MarshalIndent(v, "", "\t")
}
// Convert a file extension to the appropriate struct capable
// to marshal/unmarshal data
func ext2EncFormat(fileExtension string) ConfigEncoding {
// Lower the file extension
ext := strings.ToLower(fileExtension)
ext = strings.TrimPrefix(ext, ".")
// Return the appropriate encoder/decoder according
// to the extension
switch ext {
case "yml", "yaml":
// YAML
return yamlEncoding{}
default:
// JSON
return jsonEncoding{}
}
}
// toMarshaller returns the right marshal function according
// to the given file extension
func toMarshaller(ext string) func(interface{}) ([]byte, error) {
return ext2EncFormat(ext).Marshal
}
// toUnmarshaller returns the right marshal function according
// to the given file extension
func toUnmarshaller(ext string) func([]byte, interface{}) error {
return ext2EncFormat(ext).Unmarshal
}
// saveFileConfig marshals with the right encoding format
// according to the filename extension, if no extension is
// provided, json will be selected.
func saveFileConfig(filename string, v interface{}) error {
// Fetch filename's extension
ext := filepath.Ext(filename)
// Marshal data
dataBytes, err := toMarshaller(ext)(v)
if err != nil {
return err
}
if runtime.GOOS == "windows" {
dataBytes = []byte(strings.Replace(string(dataBytes), "\n", "\r\n", -1))
}
// Save data.
return writeFile(filename, dataBytes)
}
// loadFileConfig unmarshals the file's content with the right
// decoder format according to the filename extension. If no
// extension is provided, json will be selected by default.
func loadFileConfig(filename string, v interface{}) error {
if _, err := os.Stat(filename); err != nil {
return err
}
fileData, err := ioutil.ReadFile(filename)
if err != nil {
return err
}
if runtime.GOOS == "windows" {
fileData = []byte(strings.Replace(string(fileData), "\r\n", "\n", -1))
}
// Unmarshal file's content
return toUnmarshaller(filepath.Ext(filename))(fileData, v)
}