package main

import (
	"errors"
	"fmt"
	"net"
	"net/http"
	"os"
	"path/filepath"
)

func mainWithError() error {
	listenerFile := os.NewFile(uintptr(3), "listener")
	if listenerFile == nil {
		return errors.New("FD3 is not open")
	}

	listener, err := net.FileListener(listenerFile)
	if err != nil {
		return err
	}

	if err := os.Chdir(filepath.Dir(filepath.Dir(os.Args[0]))); err != nil {
		return err
	}

	return http.Serve(listener, http.FileServer(http.Dir("public")))
}

func main() {
	if err := mainWithError(); err != nil {
		fmt.Fprintf(os.Stderr, "%s: error: %v\n", os.Args[0], err)
		os.Exit(1)
	}
}