class PackageConfig

def search_pkg_config_by_dln_find_exe(pkg_config)
  begin
    require "dl/import"
  rescue LoadError
    return nil
  end
  dln = Module.new
  dln.module_eval do
    if DL.const_defined?(:Importer)
      extend DL::Importer
    else
      extend DL::Importable
    end
    begin
      dlload RbConfig::CONFIG["LIBRUBY"]
    rescue RuntimeError
      return nil if $!.message == "unknown error"
      return nil if /: image not found\z/ =~ $!.message
      raise
    rescue DL::DLError
      return nil
    end
    begin
      extern "const char *dln_find_exe(const char *, const char *)"
    rescue DL::DLError
      return nil
    end
  end
  path = dln.dln_find_exe(pkg_config.to_s, nil)
  if path.nil? or path.size.zero?
    nil
  else
    Pathname(path.to_s)
  end
end