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/*
* Quick - Quick key value store for config files and persistent state files
*
* Quick (C) 2015, 2016, 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 (
"encoding/json"
"fmt"
"io/ioutil"
"os"
"reflect"
"sync"
"github.com/fatih/structs"
"github.com/minio/minio/pkg/safe"
)
// Config - generic config interface functions
type Config interface {
String() string
Version() string
Save(string) error
Load(string) error
Data() interface{}
Diff(Config) ([]structs.Field, error)
DeepDiff(Config) ([]structs.Field, error)
}
// config - implements quick.Config interface
type config struct {
data interface{}
lock *sync.RWMutex
}
// Version returns the current config file format version
func (d config) Version() string {
st := structs.New(d.data)
f := st.Field("Version")
return f.Value().(string)
}
// String converts JSON config to printable string
func (d config) String() string {
configBytes, _ := json.MarshalIndent(d.data, "", "\t")
return string(configBytes)
}
// Save writes config data to a file. Data format
// is selected based on file extension or JSON if
// not provided.
func (d config) Save(filename string) error {
d.lock.Lock()
defer d.lock.Unlock()
// Backup if given file exists
oldData, err := ioutil.ReadFile(filename)
if err != nil {
// Ignore if file does not exist.
if !os.IsNotExist(err) {
return err
}
} else {
// Save read data to the backup file.
backupFilename := filename + ".old"
if err = writeFile(backupFilename, oldData); err != nil {
return err
}
}
// Save data.
return saveFileConfig(filename, d.data)
}
// Load - loads config from file and merge with currently set values
// File content format is guessed from the file name extension, if not
// available, consider that we have JSON.
func (d config) Load(filename string) error {
d.lock.Lock()
defer d.lock.Unlock()
return loadFileConfig(filename, d.data)
}
// Data - grab internal data map for reading
func (d config) Data() interface{} {
return d.data
}
//Diff - list fields that are in A but not in B
func (d config) Diff(c Config) ([]structs.Field, error) {
var fields []structs.Field
currFields := structs.Fields(d.Data())
newFields := structs.Fields(c.Data())
var found bool
for _, currField := range currFields {
found = false
for _, newField := range newFields {
if reflect.DeepEqual(currField.Name(), newField.Name()) {
found = true
}
}
if !found {
fields = append(fields, *currField)
}
}
return fields, nil
}
// DeepDiff - list fields in A that are missing or not equal to fields in B
func (d config) DeepDiff(c Config) ([]structs.Field, error) {
var fields []structs.Field
currFields := structs.Fields(d.Data())
newFields := structs.Fields(c.Data())
var found bool
for _, currField := range currFields {
found = false
for _, newField := range newFields {
if reflect.DeepEqual(currField.Value(), newField.Value()) {
found = true
}
}
if !found {
fields = append(fields, *currField)
}
}
return fields, nil
}
// checkData - checks the validity of config data. Data should be of
// type struct and contain a string type field called "Version".
func checkData(data interface{}) error {
if !structs.IsStruct(data) {
return fmt.Errorf("interface must be struct type")
}
st := structs.New(data)
f, ok := st.FieldOk("Version")
if !ok {
return fmt.Errorf("struct ‘%s’ must have field ‘Version’", st.Name())
}
if f.Kind() != reflect.String {
return fmt.Errorf("‘Version’ field in struct ‘%s’ must be a string type", st.Name())
}
return nil
}
// writeFile writes data to a file named by filename.
// If the file does not exist, writeFile creates it;
// otherwise writeFile truncates it before writing.
func writeFile(filename string, data []byte) error {
safeFile, err := safe.CreateFile(filename)
if err != nil {
return err
}
_, err = safeFile.Write(data)
if err != nil {
return err
}
return safeFile.Close()
}
// New - instantiate a new config
func New(data interface{}) (Config, error) {
if err := checkData(data); err != nil {
return nil, err
}
d := new(config)
d.data = data
d.lock = new(sync.RWMutex)
return d, nil
}
// GetVersion - extracts the version information.
func GetVersion(filename string) (version string, err error) {
var qc Config
if qc, err = Load(filename, &struct {
Version string
}{}); err != nil {
return "", err
}
return qc.Version(), err
}
// Load - loads json config from filename for the a given struct data
func Load(filename string, data interface{}) (qc Config, err error) {
if qc, err = New(data); err == nil {
err = qc.Load(filename)
}
return qc, err
}
// Save - saves given configuration data into given file as JSON.
func Save(filename string, data interface{}) (err error) {
var qc Config
if qc, err = New(data); err == nil {
err = qc.Save(filename)
}
return err
}