/lib/mkmf.rb

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# module to create Makefile for extension modules
# invoke like: ruby -r mkmf extconf.rb

require 'rbconfig'
require 'fileutils'
require 'shellwords'

# :stopdoc:
class String
  # Wraps a string in escaped quotes if it contains whitespace.
  def quote
    /\s/ =~ self ? "\"#{self}\"" : "#{self}"
  end

  # Escape whitespaces for Makefile.
  def unspace
    gsub(/\s/, '\\\\\\&')
  end

  # Generates a string used as cpp macro name.
  def tr_cpp
    strip.upcase.tr_s("^A-Z0-9_*", "_").tr_s("*", "P")
  end

  def funcall_style
    /\)\z/ =~ self ? dup : "#{self}()"
  end

  def sans_arguments
    self[/\A[^()]+/]
  end
end

class Array
  # Wraps all strings in escaped quotes if they contain whitespace.
  def quote
    map {|s| s.quote}
  end
end
# :startdoc:

##
# mkmf.rb is used by ruby C extensions to generate a Makefile which will
# correctly compile and link the C extension to ruby and a third-party
# library.
module MakeMakefile

  CONFIG = RbConfig::MAKEFILE_CONFIG
  ORIG_LIBPATH = ENV['LIB']

  C_EXT = %w[c m]
  CXX_EXT = %w[cc mm cxx cpp]
  if File::FNM_SYSCASE.zero?
    CXX_EXT.concat(%w[C])
  end
  SRC_EXT = C_EXT + CXX_EXT
  HDR_EXT = %w[h hpp]
  $static = nil
  $config_h = '$(arch_hdrdir)/ruby/config.h'
  $default_static = $static

  unless defined? $configure_args
    $configure_args = {}
    args = CONFIG["configure_args"]
    if ENV["CONFIGURE_ARGS"]
      args << " " << ENV["CONFIGURE_ARGS"]
    end
    for arg in Shellwords::shellwords(args)
      arg, val = arg.split('=', 2)
      next unless arg
      arg.tr!('_', '-')
      if arg.sub!(/^(?!--)/, '--')
        val or next
        arg.downcase!
      end
      next if /^--(?:top|topsrc|src|cur)dir$/ =~ arg
      $configure_args[arg] = val || true
    end
    for arg in ARGV
      arg, val = arg.split('=', 2)
      next unless arg
      arg.tr!('_', '-')
      if arg.sub!(/^(?!--)/, '--')
        val or next
        arg.downcase!
      end
      $configure_args[arg] = val || true
    end
  end

  $libdir = CONFIG["libdir"]
  $rubylibdir = CONFIG["rubylibdir"]
  $archdir = CONFIG["archdir"]
  $sitedir = CONFIG["sitedir"]
  $sitelibdir = CONFIG["sitelibdir"]
  $sitearchdir = CONFIG["sitearchdir"]
  $vendordir = CONFIG["vendordir"]
  $vendorlibdir = CONFIG["vendorlibdir"]
  $vendorarchdir = CONFIG["vendorarchdir"]

  $mswin = /mswin/ =~ RUBY_PLATFORM
  $bccwin = /bccwin/ =~ RUBY_PLATFORM
  $mingw = /mingw/ =~ RUBY_PLATFORM
  $cygwin = /cygwin/ =~ RUBY_PLATFORM
  $netbsd = /netbsd/ =~ RUBY_PLATFORM
  $os2 = /os2/ =~ RUBY_PLATFORM
  $beos = /beos/ =~ RUBY_PLATFORM
  $haiku = /haiku/ =~ RUBY_PLATFORM
  $solaris = /solaris/ =~ RUBY_PLATFORM
  $universal = /universal/ =~ RUBY_PLATFORM
  $dest_prefix_pattern = (File::PATH_SEPARATOR == ';' ? /\A([[:alpha:]]:)?/ : /\A/)

  # :stopdoc:

  def config_string(key, config = CONFIG)
    s = config[key] and !s.empty? and block_given? ? yield(s) : s
  end
  module_function :config_string

  def dir_re(dir)
    Regexp.new('\$(?:\('+dir+'\)|\{'+dir+'\})(?:\$(?:\(target_prefix\)|\{target_prefix\}))?')
  end
  module_function :dir_re

  def relative_from(path, base)
    dir = File.join(path, "")
    if File.expand_path(dir) == File.expand_path(dir, base)
      path
    else
      File.join(base, path)
    end
  end

  INSTALL_DIRS = [
    [dir_re('commondir'), "$(RUBYCOMMONDIR)"],
    [dir_re('sitedir'), "$(RUBYCOMMONDIR)"],
    [dir_re('vendordir'), "$(RUBYCOMMONDIR)"],
    [dir_re('rubylibdir'), "$(RUBYLIBDIR)"],
    [dir_re('archdir'), "$(RUBYARCHDIR)"],
    [dir_re('sitelibdir'), "$(RUBYLIBDIR)"],
    [dir_re('vendorlibdir'), "$(RUBYLIBDIR)"],
    [dir_re('sitearchdir'), "$(RUBYARCHDIR)"],
    [dir_re('vendorarchdir'), "$(RUBYARCHDIR)"],
    [dir_re('rubyhdrdir'), "$(RUBYHDRDIR)"],
    [dir_re('sitehdrdir'), "$(SITEHDRDIR)"],
    [dir_re('vendorhdrdir'), "$(VENDORHDRDIR)"],
    [dir_re('bindir'), "$(BINDIR)"],
  ]

  def install_dirs(target_prefix = nil)
    if $extout
      dirs = [
        ['BINDIR',        '$(extout)/bin'],
        ['RUBYCOMMONDIR', '$(extout)/common'],
        ['RUBYLIBDIR',    '$(RUBYCOMMONDIR)$(target_prefix)'],
        ['RUBYARCHDIR',   '$(extout)/$(arch)$(target_prefix)'],
        ['HDRDIR',        '$(extout)/include/ruby$(target_prefix)'],
        ['ARCHHDRDIR',    '$(extout)/include/$(arch)/ruby$(target_prefix)'],
        ['extout',        "#$extout"],
        ['extout_prefix', "#$extout_prefix"],
      ]
    elsif $extmk
      dirs = [
        ['BINDIR',        '$(bindir)'],
        ['RUBYCOMMONDIR', '$(rubylibdir)'],
        ['RUBYLIBDIR',    '$(rubylibdir)$(target_prefix)'],
        ['RUBYARCHDIR',   '$(archdir)$(target_prefix)'],
        ['HDRDIR',        '$(rubyhdrdir)/ruby$(target_prefix)'],
        ['ARCHHDRDIR',    '$(rubyhdrdir)/$(arch)/ruby$(target_prefix)'],
      ]
    elsif $configure_args.has_key?('--vendor')
      dirs = [
        ['BINDIR',        '$(bindir)'],
        ['RUBYCOMMONDIR', '$(vendordir)$(target_prefix)'],
        ['RUBYLIBDIR',    '$(vendorlibdir)$(target_prefix)'],
        ['RUBYARCHDIR',   '$(vendorarchdir)$(target_prefix)'],
        ['HDRDIR',        '$(rubyhdrdir)/ruby$(target_prefix)'],
        ['ARCHHDRDIR',    '$(rubyhdrdir)/$(arch)/ruby$(target_prefix)'],
      ]
    else
      dirs = [
        ['BINDIR',        '$(bindir)'],
        ['RUBYCOMMONDIR', '$(sitedir)$(target_prefix)'],
        ['RUBYLIBDIR',    '$(sitelibdir)$(target_prefix)'],
        ['RUBYARCHDIR',   '$(sitearchdir)$(target_prefix)'],
        ['HDRDIR',        '$(rubyhdrdir)/ruby$(target_prefix)'],
        ['ARCHHDRDIR',    '$(rubyhdrdir)/$(arch)/ruby$(target_prefix)'],
      ]
    end
    dirs << ['target_prefix', (target_prefix ? "/#{target_prefix}" : "")]
    dirs
  end

  def map_dir(dir, map = nil)
    map ||= INSTALL_DIRS
    map.inject(dir) {|d, (orig, new)| d.gsub(orig, new)}
  end

  topdir = File.dirname(File.dirname(__FILE__))
  path = File.expand_path($0)
  $extmk = path[0, topdir.size+1] == topdir+"/"
  $extmk &&= %r"\A(?:ext|enc|tool|test(?:/.+)?)\z" =~ File.dirname(path[topdir.size+1..-1])
  $extmk &&= true
  if not $extmk and File.exist?(RbConfig::CONFIG["rubyhdrdir"] + "/ruby/ruby.h")
    $hdrdir = CONFIG["rubyhdrdir"]
    $topdir = $hdrdir
    $top_srcdir = $hdrdir
    $arch_hdrdir = "$(hdrdir)/$(arch)"
  elsif File.exist?(($hdrdir = ($top_srcdir ||= topdir) + "/include")  + "/ruby.h")
    $topdir ||= RbConfig::CONFIG["topdir"]
    $arch_hdrdir = "$(extout)/include/$(arch)"
  else
    abort "mkmf.rb can't find header files for ruby at #{$hdrdir}/ruby.h"
  end

  OUTFLAG = CONFIG['OUTFLAG']
  COUTFLAG = CONFIG['COUTFLAG']
  CPPOUTFILE = CONFIG['CPPOUTFILE']

  CONFTEST_C = "conftest.c".freeze

  def rm_f(*files)
    opt = (Hash === files.last ? [files.pop] : [])
    FileUtils.rm_f(Dir[*files.flatten], *opt)
  end
  module_function :rm_f

  def rm_rf(*files)
    opt = (Hash === files.last ? [files.pop] : [])
    FileUtils.rm_rf(Dir[*files.flatten], *opt)
  end
  module_function :rm_rf

  # Returns time stamp of the +target+ file if it exists and is newer than or
  # equal to all of +times+.
  def modified?(target, times)
    (t = File.mtime(target)) rescue return nil
    Array === times or times = [times]
    t if times.all? {|n| n <= t}
  end

  def split_libs(*strs)
    strs.map {|s| s.split(/\s+(?=-|\z)/)}.flatten
  end

  def merge_libs(*libs)
    libs.inject([]) do |x, y|
      xy = x & y
      xn = yn = 0
      y = y.inject([]) {|ary, e| ary.last == e ? ary : ary << e}
      y.each_with_index do |v, yi|
        if xy.include?(v)
          xi = [x.index(v), xn].max()
          x[xi, 1] = y[yn..yi]
          xn, yn = xi + (yi - yn + 1), yi + 1
        end
      end
      x.concat(y[yn..-1] || [])
    end
  end

  # This is a custom logging module. It generates an mkmf.log file when you
  # run your extconf.rb script. This can be useful for debugging unexpected
  # failures.
  #
  # This module and its associated methods are meant for internal use only.
  #
  module Logging
    @log = nil
    @logfile = 'mkmf.log'
    @orgerr = $stderr.dup
    @orgout = $stdout.dup
    @postpone = 0
    @quiet = $extmk

    def self::log_open
      @log ||= File::open(@logfile, 'wb')
      @log.sync = true
    end

    def self::open
      log_open
      $stderr.reopen(@log)
      $stdout.reopen(@log)
      yield
    ensure
      $stderr.reopen(@orgerr)
      $stdout.reopen(@orgout)
    end

    def self::message(*s)
      log_open
      @log.printf(*s)
    end

    def self::logfile file
      @logfile = file
      log_close
    end

    def self::log_close
      if @log and not @log.closed?
        @log.flush
        @log.close
        @log = nil
      end
    end

    def self::postpone
      tmplog = "mkmftmp#{@postpone += 1}.log"
      open do
        log, *save = @log, @logfile, @orgout, @orgerr
        @log, @logfile, @orgout, @orgerr = nil, tmplog, log, log
        begin
          log.print(open {yield @log})
        ensure
          @log.close if @log and not @log.closed?
          File::open(tmplog) {|t| FileUtils.copy_stream(t, log)} if File.exist?(tmplog)
          @log, @logfile, @orgout, @orgerr = log, *save
          @postpone -= 1
          MakeMakefile.rm_f tmplog
        end
      end
    end

    class << self
      attr_accessor :quiet
    end
  end

  def xsystem command, opts = nil
    varpat = /\$\((\w+)\)|\$\{(\w+)\}/
    if varpat =~ command
      vars = Hash.new {|h, k| h[k] = ''; ENV[k]}
      command = command.dup
      nil while command.gsub!(varpat) {vars[$1||$2]}
    end
    Logging::open do
      puts command.quote
      if opts and opts[:werror]
        result = nil
        Logging.postpone do |log|
          result = (system(command) and File.zero?(log.path))
          ""
        end
        result
      else
        system(command)
      end
    end
  end

  def xpopen command, *mode, &block
    Logging::open do
      case mode[0]
      when nil, /^r/
        puts "#{command} |"
      else
        puts "| #{command}"
      end
      IO.popen(command, *mode, &block)
    end
  end

  def log_src(src, heading="checked program was")
    src = src.split(/^/)
    fmt = "%#{src.size.to_s.size}d: %s"
    Logging::message <<"EOM"
#{heading}:
/* begin */
EOM
    src.each_with_index {|line, no| Logging::message fmt, no+1, line}
    Logging::message <<"EOM"
/* end */

EOM
  end

  def create_tmpsrc(src)
    src = "#{COMMON_HEADERS}\n#{src}"
    src = yield(src) if block_given?
    src.gsub!(/[ \t]+$/, '')
    src.gsub!(/\A\n+|^\n+$/, '')
    src.sub!(/[^\n]\z/, "\\&\n")
    count = 0
    begin
      open(CONFTEST_C, "wb") do |cfile|
        cfile.print src
      end
    rescue Errno::EACCES
      if (count += 1) < 5
        sleep 0.2
        retry
      end
    end
    src
  end

  def have_devel?
    unless defined? $have_devel
      $have_devel = true
      $have_devel = try_link(MAIN_DOES_NOTHING)
    end
    $have_devel
  end

  def try_do(src, command, *opts, &b)
    unless have_devel?
      raise <<MSG
The compiler failed to generate an executable file.
You have to install development tools first.
MSG
    end
    begin
      src = create_tmpsrc(src, &b)
      xsystem(command, *opts)
    ensure
      log_src(src)
      MakeMakefile.rm_rf 'conftest.dSYM'
    end
  end

  def link_command(ldflags, opt="", libpath=$DEFLIBPATH|$LIBPATH)
    librubyarg = $extmk ? $LIBRUBYARG_STATIC : "$(LIBRUBYARG)"
    conf = RbConfig::CONFIG.merge('hdrdir' => $hdrdir.quote,
                                  'src' => "#{CONFTEST_C}",
                                  'arch_hdrdir' => $arch_hdrdir.quote,
                                  'top_srcdir' => $top_srcdir.quote,
                                  'INCFLAGS' => "#$INCFLAGS",
                                  'CPPFLAGS' => "#$CPPFLAGS",
                                  'CFLAGS' => "#$CFLAGS",
                                  'ARCH_FLAG' => "#$ARCH_FLAG",
                                  'LDFLAGS' => "#$LDFLAGS #{ldflags}",
                                  'LOCAL_LIBS' => "#$LOCAL_LIBS #$libs",
                                  'LIBS' => "#{librubyarg} #{opt} #$LIBS")
    conf['LIBPATH'] = libpathflag(libpath.map {|s| RbConfig::expand(s.dup, conf)})
    RbConfig::expand(TRY_LINK.dup, conf)
  end

  def cc_command(opt="")
    conf = RbConfig::CONFIG.merge('hdrdir' => $hdrdir.quote, 'srcdir' => $srcdir.quote,
                                  'arch_hdrdir' => $arch_hdrdir.quote,
                                  'top_srcdir' => $top_srcdir.quote)
    RbConfig::expand("$(CC) #$INCFLAGS #$CPPFLAGS #$CFLAGS #$ARCH_FLAG #{opt} -c #{CONFTEST_C}",
                     conf)
  end

  def cpp_command(outfile, opt="")
    conf = RbConfig::CONFIG.merge('hdrdir' => $hdrdir.quote, 'srcdir' => $srcdir.quote,
                                  'arch_hdrdir' => $arch_hdrdir.quote,
                                  'top_srcdir' => $top_srcdir.quote)
    if $universal and (arch_flag = conf['ARCH_FLAG']) and !arch_flag.empty?
      conf['ARCH_FLAG'] = arch_flag.gsub(/(?:\G|\s)-arch\s+\S+/, '')
    end
    RbConfig::expand("$(CPP) #$INCFLAGS #$CPPFLAGS #$CFLAGS #{opt} #{CONFTEST_C} #{outfile}",
                     conf)
  end

  def libpathflag(libpath=$DEFLIBPATH|$LIBPATH)
    libpath.map{|x|
      case x
      when "$(topdir)", /\A\./
        LIBPATHFLAG
      else
        LIBPATHFLAG+RPATHFLAG
      end % x.quote
    }.join
  end

  def with_werror(opt, opts = nil)
    if opts
      if opts[:werror] and config_string("WERRORFLAG") {|flag| opt = opt ? "#{opt} #{flag}" : flag}
        (opts = opts.dup).delete(:werror)
      end
      yield(opt, opts)
    else
      yield(opt)
    end
  end

  def try_link0(src, opt="", *opts, &b) # :nodoc:
    cmd = link_command("", opt)
    if $universal
      require 'tmpdir'
      Dir.mktmpdir("mkmf_", oldtmpdir = ENV["TMPDIR"]) do |tmpdir|
        begin
          ENV["TMPDIR"] = tmpdir
          try_do(src, cmd, *opts, &b)
        ensure
          ENV["TMPDIR"] = oldtmpdir
        end
      end
    else
      try_do(src, cmd, *opts, &b)
    end and File.executable?("conftest#{$EXEEXT}")
  end

  # Returns whether or not the +src+ can be compiled as a C source and linked
  # with its depending libraries successfully.  +opt+ is passed to the linker
  # as options. Note that +$CFLAGS+ and +$LDFLAGS+ are also passed to the
  # linker.
  #
  # If a block given, it is called with the source before compilation. You can
  # modify the source in the block.
  #
  # [+src+] a String which contains a C source
  # [+opt+] a String which contains linker options
  def try_link(src, opt="", *opts, &b)
    try_link0(src, opt, *opts, &b)
  ensure
    MakeMakefile.rm_f "conftest*", "c0x32*"
  end

  # Returns whether or not the +src+ can be compiled as a C source.  +opt+ is
  # passed to the C compiler as options. Note that +$CFLAGS+ is also passed to
  # the compiler.
  #
  # If a block given, it is called with the source before compilation. You can
  # modify the source in the block.
  #
  # [+src+] a String which contains a C source
  # [+opt+] a String which contains compiler options
  def try_compile(src, opt="", *opts, &b)
    with_werror(opt, *opts) {|_opt, *_opts| try_do(src, cc_command(_opt), *_opts, &b)} and
      File.file?("conftest.#{$OBJEXT}")
  ensure
    MakeMakefile.rm_f "conftest*"
  end

  # Returns whether or not the +src+ can be preprocessed with the C
  # preprocessor.  +opt+ is passed to the preprocessor as options. Note that
  # +$CFLAGS+ is also passed to the preprocessor.
  #
  # If a block given, it is called with the source before preprocessing. You
  # can modify the source in the block.
  #
  # [+src+] a String which contains a C source
  # [+opt+] a String which contains preprocessor options
  def try_cpp(src, opt="", *opts, &b)
    try_do(src, cpp_command(CPPOUTFILE, opt), *opts, &b) and
      File.file?("conftest.i")
  ensure
    MakeMakefile.rm_f "conftest*"
  end

  alias_method :try_header, (config_string('try_header') || :try_cpp)

  def cpp_include(header)
    if header
      header = [header] unless header.kind_of? Array
      header.map {|h| String === h ? "#include <#{h}>\n" : h}.join
    else
      ""
    end
  end

  def with_cppflags(flags)
    cppflags = $CPPFLAGS
    $CPPFLAGS = flags
    ret = yield
  ensure
    $CPPFLAGS = cppflags unless ret
  end

  def try_cppflags(flags)
    with_cppflags(flags) do
      try_header("int main() {return 0;}")
    end
  end

  def with_cflags(flags)
    cflags = $CFLAGS
    $CFLAGS = flags
    ret = yield
  ensure
    $CFLAGS = cflags unless ret
  end

  def try_cflags(flags)
    with_cflags(flags) do
      try_compile("int main() {return 0;}")
    end
  end

  def with_ldflags(flags)
    ldflags = $LDFLAGS
    $LDFLAGS = flags
    ret = yield
  ensure
    $LDFLAGS = ldflags unless ret
  end

  def try_ldflags(flags)
    with_ldflags(flags) do
      try_link("int main() {return 0;}")
    end
  end

  def try_static_assert(expr, headers = nil, opt = "", &b)
    headers = cpp_include(headers)
    try_compile(<<SRC, opt, &b)
#{headers}
/*top*/
int conftest_const[(#{expr}) ? 1 : -1];
SRC
  end

  def try_constant(const, headers = nil, opt = "", &b)
    includes = cpp_include(headers)
    if CROSS_COMPILING
      if try_static_assert("#{const} > 0", headers, opt)
        # positive constant
      elsif try_static_assert("#{const} < 0", headers, opt)
        neg = true
        const = "-(#{const})"
      elsif try_static_assert("#{const} == 0", headers, opt)
        return 0
      else
        # not a constant
        return nil
      end
      upper = 1
      lower = 0
      until try_static_assert("#{const} <= #{upper}", headers, opt)
        lower = upper
        upper <<= 1
      end
      return nil unless lower
      while upper > lower + 1
        mid = (upper + lower) / 2
        if try_static_assert("#{const} > #{mid}", headers, opt)
          lower = mid
        else
          upper = mid
        end
      end
      upper = -upper if neg
      return upper
    else
      src = %{#{includes}
#include <stdio.h>
/*top*/
int conftest_const = (int)(#{const});
int main() {printf("%d\\n", conftest_const); return 0;}
}
      begin
        if try_link0(src, opt, &b)
          xpopen("./conftest") do |f|
            return Integer(f.gets)
          end
        end
      ensure
        MakeMakefile.rm_f "conftest*"
      end
    end
    nil
  end

  # You should use +have_func+ rather than +try_func+.
  #
  # [+func+] a String which contains a symbol name
  # [+libs+] a String which contains library names.
  # [+headers+] a String or an Array of strings which contains names of header
  #             files.
  def try_func(func, libs, headers = nil, opt = "", &b)
    headers = cpp_include(headers)
    case func
    when /^&/
      decltype = proc {|x|"const volatile void *#{x}"}
    when /\)$/
      call = func
    else
      call = "#{func}()"
      decltype = proc {|x| "void ((*#{x})())"}
    end
    if opt and !opt.empty?
      [[:to_str], [:join, " "], [:to_s]].each do |meth, *args|
        if opt.respond_to?(meth)
          break opt = opt.send(meth, *args)
        end
      end
      opt = "#{opt} #{libs}"
    else
      opt = libs
    end
    decltype && try_link(<<"SRC", opt, &b) or
#{headers}
/*top*/
#{MAIN_DOES_NOTHING}
extern int t(void);
int t(void) { #{decltype["volatile p"]}; p = (#{decltype[]})#{func}; return 0; }
SRC
    call && try_link(<<"SRC", opt, &b)
#{headers}
/*top*/
#{MAIN_DOES_NOTHING}
extern int t(void);
int t(void) { #{call}; return 0; }
SRC
  end

  # You should use +have_var+ rather than +try_var+.
  def try_var(var, headers = nil, opt = "", &b)
    headers = cpp_include(headers)
    try_compile(<<"SRC", opt, &b)
#{headers}
/*top*/
#{MAIN_DOES_NOTHING}
extern int t(void);
int t(void) { const volatile void *volatile p; p = &(&#{var})[0]; return 0; }
SRC
  end

  # Returns whether or not the +src+ can be preprocessed with the C
  # preprocessor and matches with +pat+.
  #
  # If a block given, it is called with the source before compilation. You can
  # modify the source in the block.
  #
  # [+pat+] a Regexp or a String
  # [+src+] a String which contains a C source
  # [+opt+] a String which contains preprocessor options
  #
  # NOTE: When pat is a Regexp the matching will be checked in process,
  # otherwise egrep(1) will be invoked to check it.
  def egrep_cpp(pat, src, opt = "", &b)
    src = create_tmpsrc(src, &b)
    xpopen(cpp_command('', opt)) do |f|
      if Regexp === pat
        puts("    ruby -ne 'print if #{pat.inspect}'")
        f.grep(pat) {|l|
          puts "#{f.lineno}: #{l}"
          return true
        }
        false
      else
        puts("    egrep '#{pat}'")
        begin
          stdin = $stdin.dup
          $stdin.reopen(f)
          system("egrep", pat)
        ensure
          $stdin.reopen(stdin)
        end
      end
    end
  ensure
    MakeMakefile.rm_f "conftest*"
    log_src(src)
  end

  # This is used internally by the have_macro? method.
  def macro_defined?(macro, src, opt = "", &b)
    src = src.sub(/[^\n]\z/, "\\&\n")
    try_compile(src + <<"SRC", opt, &b)
/*top*/
#ifndef #{macro}
# error
>>>>>> #{macro} undefined <<<<<<
#endif
SRC
  end

  # Returns whether or not:
  # * the +src+ can be compiled as a C source,
  # * the result object can be linked with its depending libraries
  #   successfully,
  # * the linked file can be invoked as an executable
  # * and the executable exits successfully
  #
  # +opt+ is passed to the linker as options. Note that +$CFLAGS+ and
  # +$LDFLAGS+ are also passed to the linker.
  #
  # If a block given, it is called with the source before compilation. You can
  # modify the source in the block.
  #
  # [+src+] a String which contains a C source
  # [+opt+] a String which contains linker options
  #
  # Returns true when the executable exits successfully, false when it fails,
  # or nil when preprocessing, compilation or link fails.
  def try_run(src, opt = "", &b)
    if try_link0(src, opt, &b)
      xsystem("./conftest")
    else
      nil
    end
  ensure
    MakeMakefile.rm_f "conftest*"
  end

  def install_files(mfile, ifiles, map = nil, srcprefix = nil)
    ifiles or return
    ifiles.empty? and return
    srcprefix ||= "$(srcdir)/#{srcprefix}".chomp('/')
    RbConfig::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 /\A\.\// =~ files
        # install files which are in current working directory.
        files = files[2..-1]
        len = nil
      else
        # install files which are under the $(srcdir).
        files = File.join(srcdir, files)
        len = srcdir.size
      end
      f = nil
      Dir.glob(files) do |fx|
        f = fx
        f[0..len] = "" if len
        case File.basename(f)
        when *$NONINSTALLFILES
          next
        end
        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

  def install_rb(mfile, dest, srcdir = nil)
    install_files(mfile, [["lib/**/*.rb", dest, "lib"]], nil, srcdir)
  end

  def append_library(libs, lib) # :no-doc:
    format(LIBARG, lib) + " " + libs
  end

  def message(*s)
    unless Logging.quiet and not $VERBOSE
      printf(*s)
      $stdout.flush
    end
  end

  # This emits a string to stdout that allows users to see the results of the
  # various have* and find* methods as they are tested.
  #
  # Internal use only.
  #
  def checking_for(m, fmt = nil)
    f = caller[0][/in `([^<].*)'$/, 1] and f << ": " #` for vim #'
    m = "checking #{/\Acheck/ =~ f ? '' : 'for '}#{m}... "
    message "%s", m
    a = r = nil
    Logging::postpone do
      r = yield
      a = (fmt ? "#{fmt % r}" : r ? "yes" : "no") << "\n"
      "#{f}#{m}-------------------- #{a}\n"
    end
    message(a)
    Logging::message "--------------------\n\n"
    r
  end

  def checking_message(target, place = nil, opt = nil)
    [["in", place], ["with", opt]].inject("#{target}") do |msg, (pre, noun)|
      if noun
        [[:to_str], [:join, ","], [:to_s]].each do |meth, *args|
          if noun.respond_to?(meth)
            break noun = noun.send(meth, *args)
          end
        end
        msg << " #{pre} #{noun}" unless noun.empty?
      end
      msg
    end
  end

  # :startdoc:

  # Returns whether or not +macro+ is defined either in the common header
  # files or within any +headers+ you provide.
  #
  # Any options you pass to +opt+ are passed along to the compiler.
  #
  def have_macro(macro, headers = nil, opt = "", &b)
    checking_for checking_message(macro, headers, opt) do
      macro_defined?(macro, cpp_include(headers), opt, &b)
    end
  end

  # Returns whether or not the given entry point +func+ can be found within
  # +lib+.  If +func+ is +nil+, the <code>main()</code> entry point is used by
  # default.  If found, it adds the library to list of libraries to be used
  # when linking your extension.
  #
  # If +headers+ are provided, it will include those header files as the
  # header files it looks in when searching for +func+.
  #
  # The real name of the library to be linked can be altered by
  # <code>--with-FOOlib</code> configuration option.
  #
  def have_library(lib, func = nil, headers = nil, opt = "", &b)
    func = "main" if !func or func.empty?
    lib = with_config(lib+'lib', lib)
    checking_for checking_message(func.funcall_style, LIBARG%lib, opt) do
      if COMMON_LIBS.include?(lib)
        true
      else
        libs = append_library($libs, lib)
        if try_func(func, libs, headers, opt, &b)
          $libs = libs
          true
        else
          false
        end
      end
    end
  end

  # Returns whether or not the entry point +func+ can be found within the
  # library +lib+ in one of the +paths+ specified, where +paths+ is an array
  # of strings.  If +func+ is +nil+ , then the <code>main()</code> function is
  # used as the entry point.
  #
  # If +lib+ is found, then the path it was found on is added to the list of
  # library paths searched and linked against.
  #
  def find_library(lib, func, *paths, &b)
    func = "main" if !func or func.empty?
    lib = with_config(lib+'lib', lib)
    paths = paths.collect {|path| path.split(File::PATH_SEPARATOR)}.flatten
    checking_for(func.funcall_style, LIBARG%lib) do
      libpath = $LIBPATH
      libs = append_library($libs, lib)
      begin
        until r = try_func(func, libs, &b) or paths.empty?
          $LIBPATH = libpath | [paths.shift]
        end
        if r
          $libs = libs
          libpath = nil
        end
      ensure
        $LIBPATH = libpath if libpath
      end
      r
    end
  end

  # Returns whether or not the function +func+ can be found in the common
  # header files, or within any +headers+ that you provide.  If found, a macro
  # is passed as a preprocessor constant to the compiler using the function
  # name, in uppercase, prepended with +HAVE_+.
  #
  # To check functions in an additional library, you need to check that
  # library first using <code>have_library()</code>.  The +func+ shall be
  # either mere function name or function name with arguments.
  #
  # For example, if <code>have_func('foo')</code> returned +true+, then the
  # +HAVE_FOO+ preprocessor macro would be passed to the compiler.
  #
  def have_func(func, headers = nil, opt = "", &b)
    checking_for checking_message(func.funcall_style, headers, opt) do
      if try_func(func, $libs, headers, opt, &b)
        $defs << "-DHAVE_#{func.sans_arguments.tr_cpp}"
        true
      else
        false
      end
    end
  end

  # Returns whether or not the variable +var+ can be found in the common
  # header files, or within any +headers+ that you provide.  If found, a macro
  # is passed as a preprocessor constant to the compiler using the variable
  # name, in uppercase, prepended with +HAVE_+.
  #
  # To check variables in an additional library, you need to check that
  # library first using <code>have_library()</code>.
  #
  # For example, if <code>have_var('foo')</code> returned true, then the
  # +HAVE_FOO+ preprocessor macro would be passed to the compiler.
  #
  def have_var(var, headers = nil, opt = "", &b)
    checking_for checking_message(var, headers, opt) do
      if try_var(var, headers, opt, &b)
        $defs.push(format("-DHAVE_%s", var.tr_cpp))
        true
      else
        false
      end
    end
  end

  # Returns whether or not the given +header+ file can be found on your system.
  # If found, a macro is passed as a preprocessor constant to the compiler
  # using the header file name, in uppercase, prepended with +HAVE_+.
  #
  # For example, if <code>have_header('foo.h')</code> returned true, then the
  # +HAVE_FOO_H+ preprocessor macro would be passed to the compiler.
  #
  def have_header(header, preheaders = nil, opt = "", &b)
    checking_for header do
      if try_header(cpp_include(preheaders)+cpp_include(header), opt, &b)
        $defs.push(format("-DHAVE_%s", header.tr_cpp))
        true
      else
        false
      end
    end
  end

  # Returns whether or not the given +framework+ can be found on your system.
  # If found, a macro is passed as a preprocessor constant to the compiler
  # using the framework name, in uppercase, prepended with +HAVE_FRAMEWORK_+.
  #
  # For example, if <code>have_framework('Ruby')</code> returned true, then
  # the +HAVE_FRAMEWORK_RUBY+ preprocessor macro would be passed to the
  # compiler.
  #
  def have_framework(fw, &b)
    checking_for fw do
      src = cpp_include("#{fw}/#{fw}.h") << "\n" "int main(void){return 0;}"
      opt = " -framework #{fw}"
      if try_link(src, "-ObjC#{opt}", &b)
        $defs.push(format("-DHAVE_FRAMEWORK_%s", fw.tr_cpp))
        # TODO: non-worse way than this hack, to get rid of separating
        # option and its argument.
        $LDFLAGS << " -ObjC" unless /(\A|\s)-ObjC(\s|\z)/ =~ $LDFLAGS
        $LDFLAGS << opt
        true
      else
        false
      end
    end
  end

  # Instructs mkmf to search for the given +header+ in any of the +paths+
  # provided, and returns whether or not it was found in those paths.
  #
  # If the header is found then the path it was found on is added to the list
  # of included directories that are sent to the compiler (via the
  # <code>-I</code> switch).
  #
  def find_header(header, *paths)
    message = checking_message(header, paths)
    header = cpp_include(header)
    checking_for message do
      if try_header(header)
        true
      else
        found = false
        paths.each do |dir|
          opt = "-I#{dir}".quote
          if try_header(header, opt)
            $INCFLAGS << " " << opt
            found = true
            break
          end
        end
        found
      end
    end
  end

  # Returns whether or not the struct of type +type+ contains +member+.  If
  # it does not, or the struct type can't be found, then false is returned.
  # You may optionally specify additional +headers+ in which to look for the
  # struct (in addition to the common header files).
  #
  # If found, a macro is passed as a preprocessor constant to the compiler
  # using the type name and the member name, in uppercase, prepended with
  # +HAVE_+.
  #
  # For example, if <code>have_struct_member('struct foo', 'bar')</code>
  # returned true, then the +HAVE_STRUCT_FOO_BAR+ preprocessor macro would be
  # passed to the compiler.
  #
  # +HAVE_ST_BAR+ is also defined for backward compatibility.
  #
  def have_struct_member(type, member, headers = nil, opt = "", &b)
    checking_for checking_message("#{type}.#{member}", headers) do
      if try_compile(<<"SRC", opt, &b)
#{cpp_include(headers)}
/*top*/
#{MAIN_DOES_NOTHING}
int s = (char *)&((#{type}*)0)->#{member} - (char *)0;
SRC
        $defs.push(format("-DHAVE_%s_%s", type.tr_cpp, member.tr_cpp))
        $defs.push(format("-DHAVE_ST_%s", member.tr_cpp)) # backward compatibility
        true
      else
        false
      end
    end
  end

  # Returns whether or not the static type +type+ is defined.
  #
  # See also +have_type+
  #
  def try_type(type, headers = nil, opt = "", &b)
    if try_compile(<<"SRC", opt, &b)
#{cpp_include(headers)}
/*top*/
typedef #{type} conftest_type;
int conftestval[sizeof(conftest_type)?1:-1];
SRC
      $defs.push(format("-DHAVE_TYPE_%s", type.tr_cpp))
      true
    else
      false
    end
  end

  # Returns whether or not the static type +type+ is defined.  You may
  # optionally pass additional +headers+ to check against in addition to the
  # common header files.
  #
  # You may also pass additional flags to +opt+ which are then passed along to
  # the compiler.
  #
  # If found, a macro is passed as a preprocessor constant to the compiler
  # using the type name, in uppercase, prepended with +HAVE_TYPE_+.
  #
  # For example, if <code>have_type('foo')</code> returned true, then the
  # +HAVE_TYPE_FOO+ preprocessor macro would be passed to the compiler.
  #
  def have_type(type, headers = nil, opt = "", &b)
    checking_for checking_message(type, headers, opt) do
      try_type(type, headers, opt, &b)
    end
  end

  # Returns where the static type +type+ is defined.
  #
  # You may also pass additional flags to +opt+ which are then passed along to
  # the compiler.
  #
  # See also +have_type+.
  #
  def find_type(type, opt, *headers, &b)
    opt ||= ""
    fmt = "not found"
    def fmt.%(x)
      x ? x.respond_to?(:join) ? x.join(",") : x : self
    end
    checking_for checking_message(type, nil, opt), fmt do
      headers.find do |h|
        try_type(type, h, opt, &b)
      end
    end
  end

  # Returns whether or not the constant +const+ is defined.
  #
  # See also +have_const+
  #
  def try_const(const, headers = nil, opt = "", &b)
    const, type = *const
    if try_compile(<<"SRC", opt, &b)
#{cpp_include(headers)}
/*top*/
typedef #{type || 'int'} conftest_type;
conftest_type conftestval = #{type ? '' : '(int)'}#{const};
SRC
      $defs.push(format("-DHAVE_CONST_%s", const.tr_cpp))
      true
    else
      false
    end
  end

  # Returns whether or not the constant +const+ is defined.  You may
  # optionally pass the +type+ of +const+ as <code>[const, type]</code>,
  # such as:
  #
  #   have_const(%w[PTHREAD_MUTEX_INITIALIZER pthread_mutex_t], "pthread.h")
  #
  # You may also pass additional +headers+ to check against in addition to the
  # common header files, and additional flags to +opt+ which are then passed
  # along to the compiler.
  #
  # If found, a macro is passed as a preprocessor constant to the compiler
  # using the type name, in uppercase, prepended with +HAVE_CONST_+.
  #
  # For example, if <code>have_const('foo')</code> returned true, then the
  # +HAVE_CONST_FOO+ preprocessor macro would be passed to the compiler.
  #
  def have_const(const, headers = nil, opt = "", &b)
    checking_for checking_message([*const].compact.join(' '), headers, opt) do
      try_const(const, headers, opt, &b)
    end
  end

  # :stopdoc:
  STRING_OR_FAILED_FORMAT = "%s"
  def STRING_OR_FAILED_FORMAT.%(x)
    x ? super : "failed"
  end

  def typedef_expr(type, headers)
    typename, member = type.split('.', 2)
    prelude = cpp_include(headers).split(/$/)
    prelude << "typedef #{typename} rbcv_typedef_;\n"
    return "rbcv_typedef_", member, prelude
  end

  def try_signedness(type, member, headers = nil, opts = nil)
    raise ArgumentError, "don't know how to tell signedness of members" if member
    if try_static_assert("(#{type})-1 < 0", headers, opts)
      return -1
    elsif try_static_assert("(#{type})-1 > 0", headers, opts)
      return +1
    end
  end

  # :startdoc:

  # Returns the size of the given +type+.  You may optionally specify
  # additional +headers+ to search in for the +type+.
  #
  # If found, a macro is passed as a preprocessor constant to the compiler
  # using the type name, in uppercase, prepended with +SIZEOF_+, followed by
  # the type name, followed by <code>=X</code> where "X" is the actual size.
  #
  # For example, if <code>check_sizeof('mystruct')</code> returned 12, then
  # the <code>SIZEOF_MYSTRUCT=12</code> preprocessor macro would be passed to
  # the compiler.
  #
  def check_sizeof(type, headers = nil, opts = "", &b)
    typedef, member, prelude = typedef_expr(type, headers)
    prelude << "static #{typedef} *rbcv_ptr_;\n"
    prelude = [prelude]
    expr = "sizeof((*rbcv_ptr_)#{"." << member if member})"
    fmt = STRING_OR_FAILED_FORMAT
    checking_for checking_message("size of #{type}", headers), fmt do
      if size = try_constant(expr, prelude, opts, &b)
        $defs.push(format("-DSIZEOF_%s=%s", type.tr_cpp, size))
        size
      end
    end
  end

  # Returns the signedness of the given +type+.  You may optionally specify
  # additional +headers+ to search in for the +type+.
  #
  # If the +type+ is found and is a numeric type, a macro is passed as a
  # preprocessor constant to the compiler using the +type+ name, in uppercase,
  # prepended with +SIGNEDNESS_OF_+, followed by the +type+ name, followed by
  # <code>=X</code> where "X" is positive integer if the +type+ is unsigned
  # and a negative integer if the +type+ is signed.
  #
  # For example, if +size_t+ is defined as unsigned, then
  # <code>check_signedness('size_t')</code> would return +1 and the
  # <code>SIGNEDNESS_OF_SIZE_T=+1</code> preprocessor macro would be passed to
  # the compiler.  The <code>SIGNEDNESS_OF_INT=-1</code> macro would be set
  # for <code>check_signedness('int')</code>
  #
  def check_signedness(type, headers = nil, opts = nil, &b)
    typedef, member, prelude = typedef_expr(type, headers)
    signed = nil
    checking_for("signedness of #{type}", STRING_OR_FAILED_FORMAT) do
      signed = try_signedness(typedef, member, [prelude], opts, &b) or next nil
      $defs.push("-DSIGNEDNESS_OF_%s=%+d" % [type.tr_cpp, signed])
      signed < 0 ? "signed" : "unsigned"
    end
    signed
  end

  # Returns the convertible integer type of the given +type+.  You may
  # optionally specify additional +headers+ to search in for the +type+.
  # _convertible_ means actually the same type, or typedef'd from the same
  # type.
  #
  # If the +type+ is a integer type and the _convertible_ type is found,
  # the following macros are passed as preprocessor constants to the compiler
  # using the +type+ name, in uppercase.
  #
  # * +TYPEOF_+, followed by the +type+ name, followed by <code>=X</code>
  #   where "X" is the found _convertible_ type name.
  # * +TYP2NUM+ and +NUM2TYP+,
  #   where +TYP+ is the +type+ name in uppercase with replacing an +_t+
  #   suffix with "T", followed by <code>=X</code> where "X" is the macro name
  #   to convert +type+ to an Integer object, and vice versa.
  #
  # For example, if +foobar_t+ is defined as unsigned long, then
  # <code>convertible_int("foobar_t")</code> would return "unsigned long", and
  # define these macros:
  #
  #   #define TYPEOF_FOOBAR_T unsigned long
  #   #define FOOBART2NUM ULONG2NUM
  #   #define NUM2FOOBART NUM2ULONG
  #
  def convertible_int(type, headers = nil, opts = nil, &b)
    type, macname = *type
    checking_for("convertible type of #{type}", STRING_OR_FAILED_FORMAT) do
      if UNIVERSAL_INTS.include?(type)
        type
      else
        typedef, member, prelude = typedef_expr(type, headers, &b)
        if member
          prelude << "static rbcv_typedef_ rbcv_var;"
          compat = UNIVERSAL_INTS.find {|t|
            try_static_assert("sizeof(rbcv_var.#{member}) == sizeof(#{t})", [prelude], opts, &b)
          }
        else
          next unless signed = try_signedness(typedef, member, [prelude])
          u = "unsigned " if signed > 0
          prelude << "extern rbcv_typedef_ foo();"
          compat = UNIVERSAL_INTS.find {|t|
            try_compile([prelude, "extern #{u}#{t} foo();"].join("\n"), opts, :werror=>true, &b)
          }
        end
        if compat
          macname ||= type.sub(/_(?=t\z)/, '').tr_cpp
          conv = (compat == "long long" ? "LL" : compat.upcase)
          compat = "#{u}#{compat}"
          typename = type.tr_cpp
          $defs.push(format("-DSIZEOF_%s=SIZEOF_%s", typename, compat.tr_cpp))
          $defs.push(format("-DTYPEOF_%s=%s", typename, compat.quote))
          $defs.push(format("-DPRI_%s_PREFIX=PRI_%s_PREFIX", macname, conv))
          conv = (u ? "U" : "") + conv
          $defs.push(format("-D%s2NUM=%s2NUM", macname, conv))
          $defs.push(format("-DNUM2%s=NUM2%s", macname, conv))
          compat
        end
      end
    end
  end
  # :stopdoc:

  # Used internally by the what_type? method to determine if +type+ is a scalar
  # pointer.
  def scalar_ptr_type?(type, member = nil, headers = nil, &b)
    try_compile(<<"SRC", &b)   # pointer
#{cpp_include(headers)}
/*top*/
volatile #{type} conftestval;
#{MAIN_DOES_NOTHING}
extern int t(void);
int t(void) {return (int)(1-*(conftestval#{member ? ".#{member}" : ""}));}
SRC
  end

  # Used internally by the what_type? method to determine if +type+ is a scalar
  # pointer.
  def scalar_type?(type, member = nil, headers = nil, &b)
    try_compile(<<"SRC", &b)   # pointer
#{cpp_include(headers)}
/*top*/
volatile #{type} conftestval;
#{MAIN_DOES_NOTHING}
extern int t(void);
int t(void) {return (int)(1-(conftestval#{member ? ".#{member}" : ""}));}
SRC
  end

  # Used internally by the what_type? method to check if the _typeof_ GCC
  # extension is available.
  def have_typeof?
    return $typeof if defined?($typeof)
    $typeof = %w[__typeof__ typeof].find do |t|
      try_compile(<<SRC)
int rbcv_foo;
#{t}(rbcv_foo) rbcv_bar;
SRC
    end
  end

  def what_type?(type, member = nil, headers = nil, &b)
    m = "#{type}"
    var = val = "*rbcv_var_"
    func = "rbcv_func_(void)"
    if member
      m << "." << member
    else
      type, member = type.split('.', 2)
    end
    if member
      val = "(#{var}).#{member}"
    end
    prelude = [cpp_include(headers).split(/^/)]
    prelude << ["typedef #{type} rbcv_typedef_;\n",
                "extern rbcv_typedef_ *#{func};\n",
                "static rbcv_typedef_ #{var};\n",
               ]
    type = "rbcv_typedef_"
    fmt = member && !(typeof = have_typeof?) ? "seems %s" : "%s"
    if typeof
      var = "*rbcv_member_"
      func = "rbcv_mem_func_(void)"
      member = nil
      type = "rbcv_mem_typedef_"
      prelude[-1] << "typedef #{typeof}(#{val}) #{type};\n"
      prelude[-1] << "extern #{type} *#{func};\n"
      prelude[-1] << "static #{type} #{var};\n"
      val = var
    end
    def fmt.%(x)
      x ? super : "unknown"
    end
    checking_for checking_message(m, headers), fmt do
      if scalar_ptr_type?(type, member, prelude, &b)
        if try_static_assert("sizeof(*#{var}) == 1", prelude)
          return "string"
        end
        ptr = "*"
      elsif scalar_type?(type, member, prelude, &b)
        unless member and !typeof or try_static_assert("(#{type})-1 < 0", prelude)
          unsigned = "unsigned"
        end
        ptr = ""
      else
        next
      end
      type = UNIVERSAL_INTS.find do |t|
        pre = prelude
        unless member
          pre += [["static #{unsigned} #{t} #{ptr}#{var};\n",
                   "extern #{unsigned} #{t} #{ptr}*#{func};\n"]]
        end
        try_static_assert("sizeof(#{ptr}#{val}) == sizeof(#{unsigned} #{t})", pre)
      end
      type or next
      [unsigned, type, ptr].join(" ").strip
    end
  end

  # This method is used internally by the find_executable method.
  #
  # Internal use only.
  #
  def find_executable0(bin, path = nil)
    executable_file = proc do |name|
      begin
        stat = File.stat(name)
      rescue SystemCallError
      else
        next name if stat.file? and stat.executable?
      end
    end

    exts = config_string('EXECUTABLE_EXTS') {|s| s.split} || config_string('EXEEXT') {|s| [s]}
    if File.expand_path(bin) == bin
      return bin if executable_file.call(bin)
      if exts
        exts.each {|ext| executable_file.call(file = bin + ext) and return file}
      end
      return nil
    end
    if path ||= ENV['PATH']
      path = path.split(File::PATH_SEPARATOR)
    else
      path = %w[/usr/local/bin /usr/ucb /usr/bin /bin]
    end
    file = nil
    path.each do |dir|
      return file if executable_file.call(file = File.join(dir, bin))
      if exts
        exts.each {|ext| executable_file.call(ext = file + ext) and return ext}
      end
    end
    nil
  end

  # :startdoc:

  # Searches for the executable +bin+ on +path+.  The default path is your
  # +PATH+ environment variable. If that isn't defined, it will resort to
  # searching /usr/local/bin, /usr/ucb, /usr/bin and /bin.
  #
  # If found, it will return the full path, including the executable name, of
  # where it was found.
  #
  # Note that this method does not actually affect the generated Makefile.
  #
  def find_executable(bin, path = nil)
    checking_for checking_message(bin, path) do
      find_executable0(bin, path)
    end
  end

  # :stopdoc:

  def arg_config(config, default=nil, &block)
    $arg_config << [config, default]
    defaults = []
    if default
      defaults << default
    elsif !block
      defaults << nil
    end
    $configure_args.fetch(config.tr('_', '-'), *defaults, &block)
  end

  # :startdoc:

  # Tests for the presence of a <tt>--with-</tt>_config_ or
  # <tt>--without-</tt>_config_ option.  Returns +true+ if the with option is
  # given, +false+ if the without option is given, and the default value
  # otherwise.
  #
  # This can be useful for adding custom definitions, such as debug
  # information.
  #
  # Example:
  #
  #    if with_config("debug")
  #       $defs.push("-DOSSL_DEBUG") unless $defs.include? "-DOSSL_DEBUG"
  #    end
  #
  def with_config(config, default=nil)
    config = config.sub(/^--with[-_]/, '')
    val = arg_config("--with-"+config) do
      if arg_config("--without-"+config)
        false
      elsif block_given?
        yield(config, default)
      else
        break default
      end
    end
    case val
    when "yes"
      true
    when "no"
      false
    else
      val
    end
  end

  # Tests for the presence of an <tt>--enable-</tt>_config_ or
  # <tt>--disable-</tt>_config_ option. Returns +true+ if the enable option is
  # given, +false+ if the disable option is given, and the default value
  # otherwise.
  #
  # This can be useful for adding custom definitions, such as debug
  # information.
  #
  # Example:
  #
  #    if enable_config("debug")
  #       $defs.push("-DOSSL_DEBUG") unless $defs.include? "-DOSSL_DEBUG"
  #    end
  #
  def enable_config(config, default=nil)
    if arg_config("--enable-"+config)
      true
    elsif arg_config("--disable-"+config)
      false
    elsif block_given?
      yield(config, default)
    else
      return default
    end
  end

  # Generates a header file consisting of the various macro definitions
  # generated by other methods such as have_func and have_header. These are
  # then wrapped in a custom <code>#ifndef</code> based on the +header+ file
  # name, which defaults to "extconf.h".
  #
  # For example:
  #
  #   # extconf.rb
  #   require 'mkmf'
  #   have_func('realpath')
  #   have_header('sys/utime.h')
  #   create_header
  #   create_makefile('foo')
  #
  # The above script would generate the following extconf.h file:
  #
  #   #ifndef EXTCONF_H
  #   #define EXTCONF_H
  #   #define HAVE_REALPATH 1
  #   #define HAVE_SYS_UTIME_H 1
  #   #endif
  #
  # Given that the create_header method generates a file based on definitions
  # set earlier in your extconf.rb file, you will probably want to make this
  # one of the last methods you call in your script.
  #
  def create_header(header = "extconf.h")
    message "creating %s\n", header
    sym = header.tr_cpp
    hdr = ["#ifndef #{sym}\n#define #{sym}\n"]
    for line in $defs
      case line
      when /^-D([^=]+)(?:=(.*))?/
        hdr << "#define #$1 #{$2 ? Shellwords.shellwords($2)[0].gsub(/(?=\t+)/, "\\\n") : 1}\n"
      when /^-U(.*)/
        hdr << "#undef #$1\n"
      end
    end
    hdr << "#endif\n"
    hdr = hdr.join("")
    log_src(hdr, "#{header} is")
    unless (IO.read(header) == hdr rescue false)
      open(header, "wb") do |hfile|
        hfile.write(hdr)
      end
    end
    $extconf_h = header
  end

  # Sets a +target+ name that the user can then use to configure various
  # "with" options with on the command line by using that name.  For example,
  # if the target is set to "foo", then the user could use the
  # <code>--with-foo-dir</code> command line option.
  #
  # You may pass along additional "include" or "lib" defaults via the
  # +idefault+ and +ldefault+ parameters, respectively.
  #
  # Note that dir_config only adds to the list of places to search for
  # libraries and include files.  It does not link the libraries into your
  # application.
  #
  def dir_config(target, idefault=nil, ldefault=nil)
    if dir = with_config(target + "-dir", (idefault unless ldefault))
      defaults = Array === dir ? dir : dir.split(File::PATH_SEPARATOR)
      idefault = ldefault = nil
    end

    idir = with_config(target + "-include", idefault)
    $arg_config.last[1] ||= "${#{target}-dir}/include"
    ldir = with_config(target + "-lib", ldefault)
    $arg_config.last[1] ||= "${#{target}-dir}/#{@libdir_basename}"

    idirs = idir ? Array === idir ? idir.dup : idir.split(File::PATH_SEPARATOR) : []
    if defaults
      idirs.concat(defaults.collect {|d| d + "/include"})
      idir = ([idir] + idirs).compact.join(File::PATH_SEPARATOR)
    end
    unless idirs.empty?
      idirs.colle…