PKGBUILD/pkg/config/io.go

package config

import (
	"encoding/json"
	"fmt"
	"io"
	"os"
	"path/filepath"
)

// Decode a configuration from a reader
func Decode(r io.Reader) (*Config, error) {
	cnf := new(Config)
	jsonDecoder := json.NewDecoder(r)
	if err := jsonDecoder.Decode(&cnf); err != nil {
		return nil, fmt.Errorf("Can not unmarshal JSON: %v", err)
	}
	return cnf, nil
}

// Encode a configuration to a writer
func Encode(cnf *Config, w io.Writer) error {
	encoder := json.NewEncoder(w)
	encoder.SetIndent("", "  ")
	err := encoder.Encode(cnf)
	if err != nil {
		return fmt.Errorf("Error encoding config to json: %v", err)
	}
	return nil
}

// Read the configuration file
func Read(configFile string) (*Config, error) {
	f, err := os.Open(configFile)
	if err != nil {
		return nil, fmt.Errorf("Can not open file %v: %v", configFile, err)
	}
	defer f.Close()

	return Decode(f)

}

// Write the configuration into a file, specified by the configuration filepath
func Write(cnf *Config, configFile string) error {
	if _, err := os.Stat(configFile); os.IsNotExist(err) {
		configDir := filepath.Dir(configFile)
		err := os.MkdirAll(configDir, os.ModeDir)
		if err != nil {
			return fmt.Errorf("Failed to create config directory %v: %v", configDir, err)
		}
	}

	f, err := os.Create(configFile)
	if err != nil {
		return fmt.Errorf("Failed not create config file %v: %v", configFile, err)
	}
	defer f.Close()

	return Encode(cnf, f)
}