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340 lines (295 loc) · 7.57 KB
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/*
* Quick - Quick key value store for config files and persistent state files
*
* Minio Client (C) 2015 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"
"reflect"
"runtime"
"strings"
"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
}
// 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("Invalid argument type. Expecing \"struct\" type")
}
st := structs.New(data)
f, ok := st.FieldOk("Version")
if !ok {
return fmt.Errorf("Invalid type of struct argument. No [%s.Version] field found", st.Name())
}
if f.Kind() != reflect.String {
return fmt.Errorf("Invalid type of struct argument. Expecting \"string\" type [%s.Version] field", st.Name())
}
return nil
}
// 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
}
// CheckVersion - loads json and compares the version number provided returns back true or false - any failure
// is returned as error.
func CheckVersion(filename string, version string) (bool, error) {
_, err := os.Stat(filename)
if err != nil {
return false, err
}
fileData, err := ioutil.ReadFile(filename)
if err != nil {
return false, err
}
if runtime.GOOS == "windows" {
fileData = []byte(strings.Replace(string(fileData), "\r\n", "\n", -1))
}
data := struct {
Version string
}{
Version: "",
}
err = json.Unmarshal(fileData, &data)
if err != nil {
switch err := err.(type) {
case *json.SyntaxError:
return false, FormatJSONSyntaxError(bytes.NewReader(fileData), err)
default:
return false, err
}
}
config, err := New(data)
if err != nil {
return false, err
}
if config.Version() != version {
return false, nil
}
return true, nil
}
// Load - loads json config from filename for the a given struct data
func Load(filename string, data interface{}) (Config, error) {
_, err := os.Stat(filename)
if err != nil {
return nil, err
}
fileData, err := ioutil.ReadFile(filename)
if err != nil {
return nil, err
}
if runtime.GOOS == "windows" {
fileData = []byte(strings.Replace(string(fileData), "\r\n", "\n", -1))
}
err = json.Unmarshal(fileData, &data)
if err != nil {
switch err := err.(type) {
case *json.SyntaxError:
return nil, FormatJSONSyntaxError(bytes.NewReader(fileData), err)
default:
return nil, err
}
}
config, err := New(data)
if err != nil {
return nil, err
}
return config, nil
}
// Version returns the current config file format version
func (d config) Version() string {
st := structs.New(d.data)
f, ok := st.FieldOk("Version")
if !ok {
return ""
}
val := f.Value()
ver, ok := val.(string)
if ok {
return ver
}
return ""
}
// 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()
}
// 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 in JSON format to a file.
func (d config) Save(filename string) error {
d.lock.Lock()
defer d.lock.Unlock()
// Check for existing file, if yes create a backup.
st, err := os.Stat(filename)
// If file exists and stat failed return here.
if err != nil && !os.IsNotExist(err) {
return err
}
// File exists and proceed to take backup.
if err == nil {
// File exists and is not a regular file return error.
if !st.Mode().IsRegular() {
return fmt.Errorf("%s is not a regular file", filename)
}
// Read old data.
var oldData []byte
oldData, err = ioutil.ReadFile(filename)
if err != nil {
return err
}
// Save read data to the backup file.
if err = writeFile(filename+".old", oldData); err != nil {
return err
}
}
// Proceed to create or overwrite file.
jsonData, err := json.MarshalIndent(d.data, "", "\t")
if err != nil {
return err
}
if runtime.GOOS == "windows" {
jsonData = []byte(strings.Replace(string(jsonData), "\n", "\r\n", -1))
}
// Save data.
return writeFile(filename, jsonData)
}
// Load - loads JSON config from file and merge with currently set values
func (d *config) Load(filename string) error {
d.lock.Lock()
defer d.lock.Unlock()
_, err := os.Stat(filename)
if 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))
}
st := structs.New(d.data)
f, ok := st.FieldOk("Version")
if !ok {
return fmt.Errorf("Argument struct [%s] does not contain field \"Version\"", st.Name())
}
err = json.Unmarshal(fileData, d.data)
if err != nil {
switch err := err.(type) {
case *json.SyntaxError:
return FormatJSONSyntaxError(bytes.NewReader(fileData), err)
default:
return err
}
}
if err := CheckData(d.data); err != nil {
return err
}
if (*d).Version() != f.Value() {
return fmt.Errorf("Version mismatch")
}
return nil
}
// 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
err := CheckData(c.Data())
if err != nil {
return []structs.Field{}, err
}
currFields := structs.Fields(d.Data())
newFields := structs.Fields(c.Data())
found := false
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
err := CheckData(c.Data())
if err != nil {
return []structs.Field{}, err
}
currFields := structs.Fields(d.Data())
newFields := structs.Fields(c.Data())
found := false
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
}