require 'mkmf' target = "io/wait" unless /djgpp|mswin|mingw|human/ =~ RUBY_PLATFORM fionread = %w[sys/ioctl.h sys/filio.h].find do |h| checking_for("FIONREAD") {macro_defined?("FIONREAD", "#include <#{h}>\n")} end if fionread $defs << "-DFIONREAD_HEADER=\"<#{fionread}>\"" create_makefile(target) end end