This patch re-writes FS backend to support shared backend sharing locks for safe concurrent access across multiple servers.
341 lines
7.6 KiB
Go
341 lines
7.6 KiB
Go
/*
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* Quick - Quick key value store for config files and persistent state files
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*
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* Minio Client (C) 2015 Minio, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package quick
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import (
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"bytes"
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"encoding/json"
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"fmt"
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"io/ioutil"
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"os"
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"reflect"
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"runtime"
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"strings"
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"sync"
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"github.com/fatih/structs"
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"github.com/minio/minio/pkg/safe"
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)
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// Config - generic config interface functions
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type Config interface {
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String() string
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Version() string
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Save(string) error
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Load(string) error
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Data() interface{}
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Diff(Config) ([]structs.Field, error)
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DeepDiff(Config) ([]structs.Field, error)
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}
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// config - implements quick.Config interface
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type config struct {
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data interface{}
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lock *sync.RWMutex
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}
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// CheckData - checks the validity of config data. Data should be of
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// type struct and contain a string type field called "Version".
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func CheckData(data interface{}) error {
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if !structs.IsStruct(data) {
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return fmt.Errorf("Invalid argument type. Expecing \"struct\" type")
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}
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st := structs.New(data)
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f, ok := st.FieldOk("Version")
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if !ok {
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return fmt.Errorf("Invalid type of struct argument. No [%s.Version] field found", st.Name())
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}
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if f.Kind() != reflect.String {
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return fmt.Errorf("Invalid type of struct argument. Expecting \"string\" type [%s.Version] field", st.Name())
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}
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return nil
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}
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// New - instantiate a new config
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func New(data interface{}) (Config, error) {
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if err := CheckData(data); err != nil {
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return nil, err
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}
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d := new(config)
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d.data = data
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d.lock = new(sync.RWMutex)
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return d, nil
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}
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// CheckVersion - loads json and compares the version number provided returns back true or false - any failure
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// is returned as error.
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func CheckVersion(filename string, version string) (bool, error) {
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_, err := os.Stat(filename)
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if err != nil {
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return false, err
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}
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fileData, err := ioutil.ReadFile(filename)
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if err != nil {
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return false, err
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}
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if runtime.GOOS == "windows" {
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fileData = []byte(strings.Replace(string(fileData), "\r\n", "\n", -1))
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}
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data := struct {
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Version string
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}{
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Version: "",
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}
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err = json.Unmarshal(fileData, &data)
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if err != nil {
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switch err := err.(type) {
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case *json.SyntaxError:
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return false, FormatJSONSyntaxError(bytes.NewReader(fileData), err)
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default:
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return false, err
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}
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}
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config, err := New(data)
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if err != nil {
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return false, err
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}
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if config.Version() != version {
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return false, nil
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}
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return true, nil
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}
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// Load - loads json config from filename for the a given struct data
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func Load(filename string, data interface{}) (Config, error) {
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_, err := os.Stat(filename)
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if err != nil {
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return nil, err
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}
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fileData, err := ioutil.ReadFile(filename)
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if err != nil {
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return nil, err
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}
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if runtime.GOOS == "windows" {
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fileData = []byte(strings.Replace(string(fileData), "\r\n", "\n", -1))
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}
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err = json.Unmarshal(fileData, &data)
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if err != nil {
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switch err := err.(type) {
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case *json.SyntaxError:
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return nil, FormatJSONSyntaxError(bytes.NewReader(fileData), err)
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default:
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return nil, err
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}
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}
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config, err := New(data)
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if err != nil {
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return nil, err
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}
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return config, nil
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}
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// Version returns the current config file format version
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func (d config) Version() string {
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st := structs.New(d.data)
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f, ok := st.FieldOk("Version")
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if !ok {
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return ""
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}
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val := f.Value()
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ver, ok := val.(string)
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if ok {
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return ver
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}
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return ""
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}
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// writeFile writes data to a file named by filename.
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// If the file does not exist, writeFile creates it;
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// otherwise writeFile truncates it before writing.
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func writeFile(filename string, data []byte) error {
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safeFile, err := safe.CreateFile(filename)
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if err != nil {
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return err
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}
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_, err = safeFile.Write(data)
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if err != nil {
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return err
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}
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return safeFile.Close()
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}
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// String converts JSON config to printable string
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func (d config) String() string {
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configBytes, _ := json.MarshalIndent(d.data, "", "\t")
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return string(configBytes)
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}
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// Save writes config data in JSON format to a file.
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func (d config) Save(filename string) error {
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d.lock.Lock()
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defer d.lock.Unlock()
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// Check for existing file, if yes create a backup.
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st, err := os.Stat(filename)
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// If file exists and stat failed return here.
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if err != nil && !os.IsNotExist(err) {
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return err
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}
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// File exists and proceed to take backup.
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if err == nil {
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// File exists and is not a regular file return error.
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if !st.Mode().IsRegular() {
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return fmt.Errorf("%s is not a regular file", filename)
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}
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// Read old data.
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var oldData []byte
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oldData, err = ioutil.ReadFile(filename)
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if err != nil {
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return err
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}
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// Save read data to the backup file.
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if err = writeFile(filename+".old", oldData); err != nil {
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return err
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}
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}
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// Proceed to create or overwrite file.
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jsonData, err := json.MarshalIndent(d.data, "", "\t")
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if err != nil {
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return err
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}
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if runtime.GOOS == "windows" {
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jsonData = []byte(strings.Replace(string(jsonData), "\n", "\r\n", -1))
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}
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// Save data.
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return writeFile(filename, jsonData)
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}
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// Load - loads JSON config from file and merge with currently set values
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func (d *config) Load(filename string) error {
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d.lock.Lock()
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defer d.lock.Unlock()
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_, err := os.Stat(filename)
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if err != nil {
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return err
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}
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fileData, err := ioutil.ReadFile(filename)
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if err != nil {
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return err
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}
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if runtime.GOOS == "windows" {
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fileData = []byte(strings.Replace(string(fileData), "\r\n", "\n", -1))
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}
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st := structs.New(d.data)
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f, ok := st.FieldOk("Version")
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if !ok {
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return fmt.Errorf("Argument struct [%s] does not contain field \"Version\"", st.Name())
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}
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err = json.Unmarshal(fileData, d.data)
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if err != nil {
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switch err := err.(type) {
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case *json.SyntaxError:
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return FormatJSONSyntaxError(bytes.NewReader(fileData), err)
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default:
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return err
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}
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}
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if err := CheckData(d.data); err != nil {
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return err
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}
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if (*d).Version() != f.Value() {
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return fmt.Errorf("Version mismatch")
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}
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return nil
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}
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// Data - grab internal data map for reading
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func (d config) Data() interface{} {
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return d.data
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}
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//Diff - list fields that are in A but not in B
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func (d config) Diff(c Config) ([]structs.Field, error) {
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var fields []structs.Field
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err := CheckData(c.Data())
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if err != nil {
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return []structs.Field{}, err
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}
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currFields := structs.Fields(d.Data())
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newFields := structs.Fields(c.Data())
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var found bool
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for _, currField := range currFields {
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found = false
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for _, newField := range newFields {
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if reflect.DeepEqual(currField.Name(), newField.Name()) {
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found = true
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}
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}
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if !found {
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fields = append(fields, *currField)
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}
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}
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return fields, nil
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}
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//DeepDiff - list fields in A that are missing or not equal to fields in B
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func (d config) DeepDiff(c Config) ([]structs.Field, error) {
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var fields []structs.Field
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err := CheckData(c.Data())
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if err != nil {
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return []structs.Field{}, err
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}
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currFields := structs.Fields(d.Data())
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newFields := structs.Fields(c.Data())
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var found bool
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for _, currField := range currFields {
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found = false
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for _, newField := range newFields {
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if reflect.DeepEqual(currField.Value(), newField.Value()) {
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found = true
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}
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}
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if !found {
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fields = append(fields, *currField)
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}
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}
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return fields, nil
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}
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