85 lines
2 KiB
Go
85 lines
2 KiB
Go
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// Package config defines utils to simplify configuration
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// management
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package conf
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import (
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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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"path/filepath"
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)
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// LoadFile reads the file at path, parses its json content and fills the struct
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// with the content of the file.
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func LoadFile(path string, data interface{}) error {
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return read(path, data)
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}
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// SaveFile writes the given data serialized in JSON in the given path
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func SaveFile(path string, data interface{}) error {
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return write(path, data)
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}
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// LoadAndUpdateFile reads the config fileat path and
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// updates it, meaning that it adds new options, removes
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// old ones, and update it by calling the Update method of
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// data if it implements the interface Updater.
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//
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// If no file is found at path, it is created and
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// initialized with the default values.
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//
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// An error is returned only if the config file cannot be
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// written.
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func LoadAndUpdateFile(path string, data interface{}) error {
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if _, err := os.Stat(path); !os.IsNotExist(err) {
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err2 := read(path, data)
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if err2 != nil {
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return err2
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}
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if data, ok := data.(Updater); ok {
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data.Update()
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}
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}
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return write(path, data)
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}
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// Updater is the interface that can be implemented by
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// config structs. If it is implemented, Update() is
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// called by LoadAndUpdateFile(). It allows one to modify
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// the data and persist those changes, for example to
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// change default values
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type Updater interface {
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Update()
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}
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func read(path string, data interface{}) error {
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content, err := ioutil.ReadFile(filepath.Clean(path))
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if err != nil {
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return fmt.Errorf("cannot read config file: %w", err)
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}
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err = json.Unmarshal(content, &data)
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if err != nil {
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return fmt.Errorf("cannot parse config file: %w", err)
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}
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return nil
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}
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func write(path string, data interface{}) error {
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content, err := json.MarshalIndent(data, "", " ")
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if err != nil {
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return fmt.Errorf("cannot generate config content: %w", err)
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}
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err = ioutil.WriteFile(path, content, 0644)
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if err != nil {
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return fmt.Errorf("cannot write config file '%s': %w", path, err)
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}
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return nil
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}
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