DebTik/update_helpers.go

package debtik

import (
	_ "embed"
	"fmt"
	"os"
	"path/filepath"
)

// Embed the helpers so an upgrade launched by a legacy updater also updates
// its own tooling when the newly installed server starts.
//
//go:embed scripts/debtik-update
var updateHelper []byte

//go:embed scripts/release-version.py
var versionHelper []byte

// RefreshUpdateHelpers refreshes an existing installation, without creating one
// when the server is run from a development checkout.
func RefreshUpdateHelpers(dir string) error {
	if _, err := os.Stat(filepath.Join(dir, "debtik-update")); os.IsNotExist(err) {
		return nil
	} else if err != nil {
		return err
	}
	for _, helper := range []struct {
		name string
		data []byte
	}{{"debtik-update", updateHelper}, {"debtik-release-version", versionHelper}} {
		if err := writeHelper(dir, helper.name, helper.data); err != nil {
			return err
		}
	}
	return nil
}

func writeHelper(dir, name string, data []byte) error {
	f, err := os.CreateTemp(dir, ".debtik-helper-*")
	if err != nil {
		return err
	}
	defer os.Remove(f.Name())
	if err = f.Chmod(0750); err == nil {
		_, err = f.Write(data)
	}
	if err == nil {
		err = f.Sync()
	}
	closeErr := f.Close()
	if err == nil {
		err = closeErr
	}
	if err == nil {
		err = os.Rename(f.Name(), filepath.Join(dir, name))
	}
	if err != nil {
		return fmt.Errorf("install %s: %w", name, err)
	}
	return nil
}