external_config.go

// Copyright (C) 2021 Storj Labs, Inc.
// See LICENSE for copying information.

package main

import (
	"os"
	"path/filepath"
	"sort"
	"strings"

	"github.com/zeebo/errs"
	"github.com/zeebo/ini"
)

// loadConfig loads the configuration file from disk if it is not already loaded.
// This makes calls to loadConfig idempotent.
func (ex *external) loadConfig() error {
	if ex.config.values != nil {
		return nil
	}
	ex.config.values = make(map[string][]string)

	fh, err := os.Open(ex.ConfigFile())
	if os.IsNotExist(err) {
		return nil
	} else if err != nil {
		return errs.Wrap(err)
	}
	defer func() { _ = fh.Close() }()

	err = ini.Read(fh, func(ent ini.Entry) error {
		if ent.Section != "" {
			ent.Key = ent.Section + "." + ent.Key
		}
		ex.config.values[ent.Key] = append(ex.config.values[ent.Key], ent.Value)
		return nil
	})
	if err != nil {
		return err
	}

	ex.config.loaded = true
	return nil
}

// SaveConfig writes out the config file using the provided values.
// It is only intended to be used during initial migration and setup.
func (ex *external) SaveConfig(values map[string]string) error {
	entries := make([]ini.Entry, 0, len(values))
	for k, v := range values {
		var section string
		if idx := strings.LastIndexByte(k, '.'); idx >= 0 {
			section, k = k[:idx], k[idx+1:]
		}
		entries = append(entries, ini.Entry{
			Section: section,
			Key:     k,
			Value:   v,
		})
	}
	sort.Slice(entries, func(i, j int) bool {
		if entries[i].Section == entries[j].Section {
			return entries[i].Key < entries[j].Key
		}
		return entries[i].Section < entries[j].Section
	})
	err := ex.saveConfig(entries)
	if err != nil {
		return err
	}
	ex.config.values = make(map[string][]string, len(values))
	for k, v := range values {
		ex.config.values[k] = []string{v}
	}
	return nil
}

// saveConfig writes out the config file using the provided values.
// It is only intended to be used during initial migration and setup.
func (ex *external) saveConfig(entries []ini.Entry) error {
	// TODO(jeff): write it atomically

	path := ex.ConfigFile()
	dir := filepath.Dir(path)

	if err := os.MkdirAll(dir, 0755); err != nil {
		return errs.Wrap(err)
	}

	newFh, err := os.Create(path)
	if err != nil {
		return errs.Wrap(err)
	}
	defer func() { _ = newFh.Close() }()

	err = ini.Write(newFh, func(emit func(ini.Entry)) {
		for _, ent := range entries {
			emit(ent)
		}
	})
	if err != nil {
		return errs.Wrap(err)
	}

	if err := newFh.Sync(); err != nil {
		return errs.Wrap(err)
	}

	if err := newFh.Close(); err != nil {
		return errs.Wrap(err)
	}

	return nil
}