# File lib/mkmf.rb, line 499
def install_files(mfile, ifiles, map = nil, srcprefix = nil)
  ifiles or return
  srcprefix ||= '$(srcdir)'
  Config::expand(srcdir = srcprefix.dup)
  dirs = []
  path = Hash.new {|h, i| h[i] = dirs.push([i])[-1]}
  ifiles.each do |files, dir, prefix|
    dir = map_dir(dir, map)
    prefix = %r|\A#{Regexp.quote(prefix)}/?| if prefix
    if /\A\.\// =~ files
      # install files which are in current working directory.
      files = files[2..-1]
      len = nil
    else
      # install files which are under the $(srcdir).
      files = File.join(srcdir, files)
      len = srcdir.size
    end
    f = nil
    Dir.glob(files) do |f|
      f[0..len] = "" if len
      d = File.dirname(f)
      d.sub!(prefix, "") if prefix
      d = (d.empty? || d == ".") ? dir : File.join(dir, d)
      f = File.join(srcprefix, f) if len
      path[d] << f
    end
    unless len or f
      d = File.dirname(files)
      d.sub!(prefix, "") if prefix
      d = (d.empty? || d == ".") ? dir : File.join(dir, d)
      path[d] << files
    end
  end
  dirs
end