libv8/ext/libv8/builder.rb

unless $:.include? File.expand_path("../../../lib", __FILE__)
  $:.unshift File.expand_path("../../../lib", __FILE__)
end
require 'mkmf'
require 'rbconfig'
require 'shellwords'
require 'libv8/version'
require File.expand_path '../compiler', __FILE__
require File.expand_path '../arch', __FILE__
require File.expand_path '../make', __FILE__
require File.expand_path '../patcher', __FILE__

module Libv8
  class Builder
    include Libv8::Arch
    include Libv8::Make
    include Libv8::Patcher

    def initialize
      @compiler = choose_compiler
    end

    def make_target
      profile = enable_config('debug') ? 'debug' : 'release'
      "#{libv8_arch}.#{profile}"
    end

    def gyp_defines(*defines)
      # Do not use an external snapshot as we don't really care for binary size
      defines << 'v8_use_external_startup_data=0'

      # Do not use the GPLv3 ld.gold binary on Linux
      defines << 'linux_use_bundled_gold=0'

      # Pass clang flag to GYP in order to work around GCC compilation failures
      defines << "clang=#{@compiler.is_a?(Compiler::Clang) ? '1' : '0'}"

      "GYP_DEFINES=\"#{defines.join ' '}\""
    end

    def make_flags(*flags)
      # Disable i18n
      flags << 'i18nsupport=off'

      # Solaris / Smart OS requires additional -G flag to use with -fPIC
      flags << "CFLAGS=-G" if @compiler.target =~ /solaris/

      # Disable werror as this version of v8 is getting difficult to maintain
      # with it on
      flags << 'werror=no'

      # Append GYP variable definitions
      flags << gyp_defines

      "#{make_target} #{flags.join ' '}"
    end

    def build_libv8!
      setup_python!
      setup_build_deps!
      Dir.chdir(File.expand_path('../../../vendor/v8', __FILE__)) do
        fail 'No compilers available' if @compiler.nil?
        patch!
        print_build_info
        puts 'Beginning compilation. This will take some time.'

        command = "env CXX=#{Shellwords.escape @compiler.to_s} LINK=#{Shellwords.escape @compiler.to_s} #{make} #{make_flags}"
        puts "Building v8 with #{command}"
        system command
      end
      return $?.exitstatus
    end

    def setup_python!
      # If python v2 cannot be found in PATH,
      # create a symbolic link to python2 the current directory and put it
      # at the head of PATH. That way all commands that inherit this environment
      # will use ./python -> python2
      if python_version !~ /^2/
        unless system 'which python2 2>&1 > /dev/null'
          fail "libv8 requires python 2 to be installed in order to build, but it is currently #{python_version}"
        end
        `ln -fs #{`which python2`.chomp} python`
        ENV['PATH'] = "#{File.expand_path '.'}:#{ENV['PATH']}"
      end
    end

    ##
    # The release tag to checkout. If this is version 4.5.95.0 of the libv8 gem,
    # then this will be 4.5.95
    #
    def source_version
      Libv8::VERSION.gsub(/\.[^.]+$/, '')
    end

    ##
    # Checkout all of the V8 source and its dependencies using the
    # chromium depot tools.
    #
    # https://chromium.googlesource.com/v8/v8.git#Getting-the-Code
    #
    def setup_build_deps!
      ENV['PATH'] = "#{File.expand_path('../../../vendor/depot_tools', __FILE__)}:#{ENV['PATH']}"
      Dir.chdir(File.expand_path('../../../vendor', __FILE__)) do
        unless Dir.exists? 'v8'
          system "fetch v8" or fail "unable to fetch v8 source"
        else
          system "gclient fetch" or fail "could not fetch v8 build dependencies commits"
        end
        Dir.chdir('v8') do
          unless system "git checkout #{source_version} -- ."
            fail "unable to checkout source for v8 #{source_version}"
          end
          system "gclient sync" or fail "could not sync v8 build dependencies"
          system "git checkout Makefile" # Work around a weird bug on FreeBSD
        end
      end
    end

    private

    def choose_compiler
      compiler = if with_config('cxx') || ENV['CXX']
                   with_config('cxx') || ENV['CXX']
                 else
                   begin
                     MakeMakefile::CONFIG['CXX'] # stdlib > 2.0.0
                   rescue NameError
                     RbConfig::CONFIG['CXX'] # stdlib < 2.0.0
                   end
                 end

      Libv8::Compiler.type_of(compiler).new compiler
    end

    def python_version
      if system 'which python 2>&1 > /dev/null'
        `python -c 'import platform; print(platform.python_version())'`.chomp
      else
        "not available"
      end
    end

    def print_build_info
      puts "Compiling v8 for #{libv8_arch}"

      puts "Using python #{python_version}"

      puts "Using compiler: #{@compiler} (#{@compiler.name} version #{@compiler.version})"
      unless @compiler.compatible?
        warn "Unable to find a compiler officially supported by v8."
        warn "It is recommended to use clang v3.5 or GCC v4.8 or higher"
      end
    end
  end
end