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# class Gem::Installer

The installer installs the files contained in the .gem into the Gem.home.

`Gem::Installer` does the work of putting files in all the right places on the filesystem including unpacking the gem into its gem dir, installing the gemspec in the specifications dir, storing the cached gem in the cache dir, and installing either wrappers or symlinks for executables.

The installer invokes pre and post install hooks. Hooks can be added either through a rubygems_plugin.rb file in an installed gem or via a rubygems/defaults/#{RUBY_ENGINE}.rb or rubygems/defaults/operating_system.rb file. See `Gem.pre_install` and `Gem.post_install` for details.

### Constants

ENV_PATHS

  Paths where env(1) might live. Some systems are broken and have it in /bin

### Attributes

exec_format [W]

Overrides the executable format.

This is a sprintf format with a “%s” which will be replaced with the executable name. It is based off the ruby executable name’s difference from “ruby”.

bin_dir [R]

The directory a gem’s executables will be installed into

gem_home [R]

The gem repository the gem will be installed into

options [R]

The options passed when the `Gem::Installer` was instantiated.

package [R]

The gem package instance.

### Public Class Methods

at (path, options = {})
Source

    # File lib/rubygems/installer.rb, line 85
    def self.at(path, options = {})
      security_policy = options[:security_policy]
      package = Gem::Package.new path, security_policy
      new package, options
    end

Construct an installer object for the gem file located at `path`

exec_format ()
Source

    # File lib/rubygems/installer.rb, line 77
    def exec_format
      @exec_format ||= Gem.default_exec_format
    end

Defaults to use Ruby’s program prefix and suffix.

for_spec (spec, options = {})
Source

    # File lib/rubygems/installer.rb, line 123
    def self.for_spec(spec, options = {})
      # FIXME: we should have a real Package class for this
      new FakePackage.new(spec), options
    end

Construct an installer object for an ephemeral gem (one where we don’t actually have a .gem file, just a spec)

new (package, options = {})
Source

    # File lib/rubygems/installer.rb, line 153
    def initialize(package, options = {})
      require "fileutils"

      @options = options
      @package = package

      process_options

      @package.dir_mode = options[:dir_mode]
      @package.prog_mode = options[:prog_mode]
      @package.data_mode = options[:data_mode]
    end

Constructs an `Installer` instance that will install the gem at `package` which can either be a path or an instance of `Gem::Package`. `options` is a `Hash` with the following keys:

:bin_dir

  Where to put a bin wrapper if needed.

:development

  Whether or not development dependencies should be installed.

:env_shebang

  Use /usr/bin/env in bin wrappers.

:force

  Overrides all version checks and security policy checks, except for a signed-gems-only policy.

:format_executable

  Format the executable the same as the Ruby executable. If your Ruby is ruby18, foo_exec will be installed as foo_exec18.

:ignore_dependencies

  Don’t raise if a dependency is missing.

:install_dir

  The directory to install the gem into.

:security_policy

  Use the specified security policy. See `Gem::Security`

:user_install

  Indicate that the gem should be unpacked into the users personal gem directory.

:only_install_dir

  Only validate dependencies against what is in the install_dir

:wrappers

  Install wrappers if true, symlinks if false.

:build_args

  An `Array` of arguments to pass to the extension builder process. If not set, then `Gem::Command.build_args` is used

:post_install_message

  Print gem post install message if true

### Public Instance Methods

app_script_text (bin_file_name)
Source

    # File lib/rubygems/installer.rb, line 727
      def app_script_text(bin_file_name)
        # NOTE: that the `load` lines cannot be indented, as old RG versions match
        # against the beginning of the line
        escaped_bin_file_name = bin_file_name.gsub(/[\\']/) {|c| "\\#{c}" }
        <<~TEXT
          #{shebang bin_file_name}
          #
          # This file was generated by RubyGems.
          #
          # The application '#{spec.name}' is installed as part of a gem, and
          # this file is here to facilitate running it.
          #

          require 'rubygems'
          #{gemdeps_load(spec.name)}
          version = "#{Gem::Requirement.default_prerelease}"

          str = ARGV.first
          if str
            str = str.b[/\\A_(.*)_\\z/, 1]
            if str and Gem::Version.correct?(str)
              #{explicit_version_requirement(spec.name)}
              ARGV.shift
            end
          end

          if Gem.respond_to?(:activate_and_load_bin_path)
            Gem.activate_and_load_bin_path('#{spec.name}', '#{escaped_bin_file_name}', version)
          else
            load Gem.activate_bin_path('#{spec.name}', '#{escaped_bin_file_name}', version)
          end
        TEXT
      end

Return the text for an application file.

build_extensions ()
Source

    # File lib/rubygems/installer.rb, line 819
    def build_extensions
      builder = Gem::Ext::Builder.new spec, build_args, Gem.target_rbconfig, build_jobs

      builder.build_extensions
    end

Builds extensions. Valid types of extensions are extconf.rb files, configure scripts and rakefiles or mkrf_conf files.

default_spec_dir ()
Source

    # File lib/rubygems/installer.rb, line 389
    def default_spec_dir
      dir = File.join(gem_home, "specifications", "default")
      FileUtils.mkdir_p dir
      dir
    end

default_spec_file ()
Source

    # File lib/rubygems/installer.rb, line 399
    def default_spec_file
      File.join default_spec_dir, "#{spec.full_name}.gemspec"
    end

The location of the default spec file for default gems.

dir ()
Source

    # File lib/rubygems/installer.rb, line 860
    def dir
      gem_dir.to_s
    end

Return the target directory where the gem is to be installed. This directory is not guaranteed to be populated.

ensure_dependency (spec, dependency)
Source

    # File lib/rubygems/installer.rb, line 364
    def ensure_dependency(spec, dependency)
      unless installation_satisfies_dependency? dependency
        raise Gem::InstallError, "#{spec.name} requires #{dependency}"
      end
      true
    end

Ensure that the dependency is satisfied by the current installation of gem. If it is not an exception is raised.

spec

  `Gem::Specification`

dependency

  `Gem::Dependency`

ensure_loadable_spec ()
Source

    # File lib/rubygems/installer.rb, line 595
    def ensure_loadable_spec
      ruby = spec.to_ruby_for_cache

      begin
        eval ruby
      rescue StandardError, SyntaxError => e
        raise Gem::InstallError,
              "The specification for #{spec.full_name} is corrupt (#{e.class})"
      end
    end

Ensures the `Gem::Specification` written out for this gem is loadable upon installation.

explicit_version_requirement (name)
Source

    # File lib/rubygems/installer.rb, line 770
      def explicit_version_requirement(name)
        code = "version = str"
        return code unless name == "bundler"

        code += <<~TEXT

          ENV['BUNDLER_VERSION'] = str
        TEXT
      end

extract_bin ()
Source

    # File lib/rubygems/installer.rb, line 839
    def extract_bin
      @package.extract_files gem_dir, "#{spec.bindir}/*"
    end

Extracts only the bin/ files from the gem into the gem directory. This is used by default gems to allow a gem-aware stub to function without the full gem installed.

extract_files ()
Source

    # File lib/rubygems/installer.rb, line 830
    def extract_files
      @package.extract_files gem_dir
    end

Reads the file index and extracts each file into the gem directory.

Ensures that files can’t be installed outside the gem directory.

formatted_program_filename (filename)
Source

    # File lib/rubygems/installer.rb, line 846
    def formatted_program_filename(filename)
      if @format_executable
        self.class.exec_format % File.basename(filename)
      else
        filename
      end
    end

Prefix and suffix the program filename the same as ruby.

gem ()
Source

    # File lib/rubygems/installer.rb, line 867
    def gem
      @package.gem.path
    end

Filename of the gem being installed.

gem_dir ()
Source

    # File lib/rubygems/installer.rb, line 246
    def gem_dir
      @gem_dir ||= File.join(gem_home, "gems", spec.full_name)
    end

Lazy accessor for the spec’s gem directory.

gemdeps_load (name)
Source

    # File lib/rubygems/installer.rb, line 761
      def gemdeps_load(name)
        return "" if name == "bundler"

        <<~TEXT

          Gem.use_gemdeps
        TEXT
      end

generate_bin_script (filename, bindir)
Source

    # File lib/rubygems/installer.rb, line 497
    def generate_bin_script(filename, bindir)
      bin_script_path = File.join bindir, formatted_program_filename(filename)

      Gem.open_file_with_lock(bin_script_path) do
        require "fileutils"
        FileUtils.rm_f bin_script_path # prior install may have been --no-wrappers

        File.open(bin_script_path, "wb", 0o755) do |file|
          file.write app_script_text(filename)
          file.chmod(options[:prog_mode] || 0o755)
        end
      end

      verbose bin_script_path

      generate_windows_script filename, bindir
    end

Creates the scripts to run the applications in the gem.

generate_bin_symlink (filename, bindir)
Source

    # File lib/rubygems/installer.rb, line 519
    def generate_bin_symlink(filename, bindir)
      src = File.join gem_dir, spec.bindir, filename
      dst = File.join bindir, formatted_program_filename(filename)

      if File.exist? dst
        if File.symlink? dst
          link = File.readlink(dst).split File::SEPARATOR
          cur_version = Gem::Version.create(link[-3].sub(/^.*-/, ""))
          return if spec.version < cur_version
        end
        File.unlink dst
      end

      FileUtils.symlink src, dst, verbose: Gem.configuration.really_verbose
    rescue NotImplementedError, SystemCallError
      alert_warning "Unable to use symlinks, installing wrapper"
      generate_bin_script filename, bindir
    end

Creates the symlinks to run the applications in the gem. Moves the symlink if the gem being installed has a newer version.

generate_windows_script (filename, bindir)
Source

    # File lib/rubygems/installer.rb, line 427
    def generate_windows_script(filename, bindir)
      if Gem.win_platform?
        script_name = formatted_program_filename(filename) + ".bat"
        script_path = File.join bindir, File.basename(script_name)
        File.open script_path, "w" do |file|
          file.puts windows_stub_script(bindir, filename)
        end

        verbose script_path
      end
    end

Creates windows .bat files for easy running of commands

install ()
Source

    # File lib/rubygems/installer.rb, line 268
    def install
      pre_install_checks

      run_pre_install_hooks

      # Set loaded_from to ensure extension_dir is correct
      spec.loaded_from = spec_file

      # Completely remove any previous gem files
      FileUtils.rm_rf gem_dir
      FileUtils.rm_rf spec.extension_dir

      dir_mode = options[:dir_mode]
      FileUtils.mkdir_p gem_dir, mode: dir_mode && 0o755

      extract_files

      build_extensions
      write_build_info_file
      run_post_build_hooks

      generate_bin
      generate_plugins

      write_spec
      write_cache_file

      File.chmod(dir_mode, gem_dir) if dir_mode

      say clean_text(spec.post_install_message.to_s) if options[:post_install_message] && !spec.post_install_message.nil?

      Gem::Specification.add_spec(spec) unless @install_dir

      load_plugin

      run_post_install_hooks

      spec
    rescue Errno::EACCES => e
      # Permission denied - /path/to/foo
      raise Gem::FilePermissionError, e.message.split(" - ").last
    end

Installs the gem and returns a loaded `Gem::Specification` for the installed gem.

The gem will be installed with the following structure:

    @gem_home/
      cache/<gem-version>.gem #=> a cached copy of the installed gem
      gems/<gem-version>/... #=> extracted files
      specifications/<gem-version>.gemspec #=> the Gem::Specification

installation_satisfies_dependency? (dependency)
Source

    # File lib/rubygems/installer.rb, line 374
    def installation_satisfies_dependency?(dependency)
      return true if @options[:development] && dependency.type == :development
      return true if installed_specs.detect {|s| dependency.matches_spec? s }
      return false if @only_install_dir
      !dependency.matching_specs.empty?
    end

True if the gems in the system satisfy `dependency`.

installed_specs ()
Source

    # File lib/rubygems/installer.rb, line 344
    def installed_specs
      @installed_specs ||= begin
        specs = []

        Gem::Util.glob_files_in_dir("*.gemspec", File.join(gem_home, "specifications")).each do |path|
          spec = Gem::Specification.load path
          specs << spec if spec
        end

        specs
      end
    end

Return an `Array` of Specifications contained within the `gem_home` we’ll be installing into.

pre_install_checks ()
Source

    # File lib/rubygems/installer.rb, line 880
    def pre_install_checks
      verify_gem_home

      # The name and require_paths must be verified first, since it could contain
      # ruby code that would be eval'ed in #ensure_loadable_spec
      verify_spec

      ensure_loadable_spec

      Gem.ensure_gem_subdirectories gem_home

      return true if @force

      ensure_dependencies_met unless @ignore_dependencies

      true
    end

Performs various checks before installing the gem such as the install repository is writable and its directories exist, required Ruby and rubygems versions are met and that dependencies are installed.

Version and dependency checks are skipped if this install is forced.

The dependent check will be skipped if the install is ignoring dependencies.

shebang (bin_file_name)
Source

    # File lib/rubygems/installer.rb, line 553
    def shebang(bin_file_name)
      path = File.join gem_dir, spec.bindir, bin_file_name
      first_line = File.open(path, "rb", &:gets) || ""

      if first_line.start_with?("#!")
        # Preserve extra words on shebang line, like "-w".  Thanks RPA.
        shebang = first_line.sub(/\A\#!.*?ruby\S*((\s+\S+)+)/, "#!#{Gem.ruby}")
        opts = $1
        shebang.strip! # Avoid nasty ^M issues.
      end

      if which = Gem.configuration[:custom_shebang]
        # replace bin_file_name with "ruby" to avoid endless loops
        which = which.gsub(/ #{bin_file_name}$/," #{ruby_install_name}")

        which = which.gsub(/\$(\w+)/) do
          case $1
          when "env"
            @env_path ||= ENV_PATHS.find {|env_path| File.executable? env_path }
          when "ruby"
            "#{Gem.ruby}#{opts}"
          when "exec"
            bin_file_name
          when "name"
            spec.name
          end
        end

        "#!#{which}"
      elsif @env_shebang
        # Create a plain shebang line.
        @env_path ||= ENV_PATHS.find {|env_path| File.executable? env_path }
        "#!#{@env_path} #{ruby_install_name}"
      else
        "#{bash_prolog_script}#!#{Gem.ruby}#{opts}"
      end
    end

Generates a `!` line for `bin_file_name`‘s wrapper copying arguments if necessary.

If the :custom_shebang config is set, then it is used as a template for how to create the shebang used for to run a gem’s executables.

The template supports 4 expansions:

    $env    the path to the unix env utility
    $ruby   the path to the currently running ruby interpreter
    $exec   the path to the gem's executable
    $name   the name of the gem the executable is for

spec ()
Source

    # File lib/rubygems/installer.rb, line 253
    def spec
      @package.spec
    end

Lazy accessor for the installer’s spec.

spec_file ()
Source

    # File lib/rubygems/installer.rb, line 385
    def spec_file
      File.join gem_home, "specifications", "#{spec.full_name}.gemspec"
    end

The location of the spec file that is installed.

verify_spec ()
Source

    # File lib/rubygems/installer.rb, line 682
    def verify_spec
      unless Gem::Specification::VALID_NAME_PATTERN.match?(spec.name)
        raise Gem::InstallError, "#{spec} has an invalid name"
      end

      if spec.raw_require_paths.any? {|path| path =~ /\R/ }
        raise Gem::InstallError, "#{spec} has an invalid require_paths"
      end

      if spec.extensions.any? {|ext| ext =~ /\R/ }
        raise Gem::InstallError, "#{spec} has an invalid extensions"
      end

      if /\R/.match?(spec.platform.to_s)
        raise Gem::InstallError, "#{spec.platform} is an invalid platform"
      end

      unless /\A\d+\z/.match?(spec.specification_version.to_s)
        raise Gem::InstallError, "#{spec} has an invalid specification_version"
      end

      if spec.dependencies.any? {|dep| dep.type != :runtime && dep.type != :development }
        raise Gem::InstallError, "#{spec} has an invalid dependencies"
      end

      if spec.dependencies.any? {|dep| dep.name =~ /(?:\R|[<>])/ }
        raise Gem::InstallError, "#{spec} has an invalid dependencies"
      end

      if spec.executables.any? {|name| !name.is_a?(String) || name != File.basename(name) || /\A\.\.?\z|\R/.match?(name) }
        raise Gem::InstallError, "#{spec} has an invalid executable"
      end

      raise Gem::InstallError, "#{spec} has an invalid bindir" unless spec.bindir.is_a?(String)

      expanded_gem_dir = File.expand_path(gem_dir)
      expanded_bindir = File.expand_path(File.join(gem_dir, spec.bindir))
      unless expanded_bindir == expanded_gem_dir || expanded_bindir.start_with?("#{expanded_gem_dir}/")
        raise Gem::InstallError, "#{spec} has an invalid bindir"
      end
    end

windows_stub_script (bindir, bin_file_name)
Source

    # File lib/rubygems/installer.rb, line 783
      def windows_stub_script(bindir, bin_file_name)
        rb_topdir = RbConfig::TOPDIR || File.dirname(rb_config["bindir"])

        # get ruby executable file name from RbConfig
        ruby_exe = "#{rb_config["RUBY_INSTALL_NAME"]}#{rb_config["EXEEXT"]}"
        ruby_exe = "ruby.exe" if ruby_exe.empty?

        if File.exist?(File.join(bindir, ruby_exe))
          # stub & ruby.exe within same folder.  Portable
          <<~TEXT
            @ECHO OFF
            @"%~dp0#{ruby_exe}" "%~dpn0" %*
          TEXT
        elsif bindir.downcase.start_with? rb_topdir.downcase
          # stub within ruby folder, but not standard bin.  Portable
          require "pathname"
          from = Pathname.new bindir
          to   = Pathname.new "#{rb_topdir}/bin"
          rel  = to.relative_path_from from
          <<~TEXT
            @ECHO OFF
            @"%~dp0#{rel}/#{ruby_exe}" "%~dpn0" %*
          TEXT
        else
          # outside ruby folder, maybe -user-install or bundler.  Portable, but ruby
          # is dependent on PATH
          <<~TEXT
            @ECHO OFF
            @#{ruby_exe} "%~dpn0" %*
          TEXT
        end
      end

return the stub script text used to launch the true Ruby script

write_build_info_file ()
Source

    # File lib/rubygems/installer.rb, line 902
    def write_build_info_file
      return if build_args.empty?

      build_info_dir = File.join gem_home, "build_info"

      dir_mode = options[:dir_mode]
      FileUtils.mkdir_p build_info_dir, mode: dir_mode && 0o755

      build_info_file = File.join build_info_dir, "#{spec.full_name}.info"

      File.open build_info_file, "w" do |io|
        build_args.each do |arg|
          io.puts arg
        end
      end

      File.chmod(dir_mode, build_info_dir) if dir_mode
    end

Writes the file containing the arguments for building this gem’s extensions.

write_cache_file ()
Source

    # File lib/rubygems/installer.rb, line 924
    def write_cache_file
      cache_file = File.join gem_home, "cache", spec.file_name
      @package.copy_to cache_file
    end

Writes the .gem file to the cache directory

write_default_spec ()
Source

    # File lib/rubygems/installer.rb, line 420
    def write_default_spec
      Gem.write_binary(default_spec_file, spec.to_ruby)
    end

Writes the full .gemspec specification (in Ruby) to the gem home’s specifications/default directory.

In contrast to `write_spec`, this keeps file lists, so the ‘gem contents` command works.

write_spec ()
Source

    # File lib/rubygems/installer.rb, line 407
    def write_spec
      spec.installed_by_version = Gem.rubygems_version

      Gem.write_binary(spec_file, spec.to_ruby_for_cache)
    end

Writes the .gemspec specification (in Ruby) to the gem home’s specifications directory.

### Private Instance Methods

bash_prolog_script ()
Source

    # File lib/rubygems/installer.rb, line 979
      def bash_prolog_script
        if load_relative_enabled?
          <<~EOS
            #!/bin/sh
            # -*- ruby -*-
            _=_\\
            =begin
            bindir="${0%/*}"
            ruby="$bindir/#{ruby_install_name}"
            if [ ! -f "$ruby" ]; then
              ruby="#{ruby_install_name}"
            fi
            exec "$ruby" "-x" "$0" "$@"
            =end
          EOS
        else
          ""
        end
      end

build_args ()
Source

    # File lib/rubygems/installer.rb, line 951
    def build_args
      @build_args ||= begin
                        require_relative "command"
                        Gem::Command.build_args
                      end
    end

build_jobs ()
Source

    # File lib/rubygems/installer.rb, line 958
    def build_jobs
      @build_jobs ||= begin
                        require "etc"
                        Etc.nprocessors + 1
                      rescue LoadError
                        1
                      end
    end

load_plugin ()
Source

    # File lib/rubygems/installer.rb, line 999
    def load_plugin
      specs = Gem::Specification.find_all_by_name(spec.name)
      # If old version already exists, this plugin isn't loaded
      # immediately. It's for avoiding a case that multiple versions
      # are loaded at the same time.
      return unless specs.size == 1

      plugin_files = spec.plugins.map do |plugin|
        File.join(@plugins_dir, "#{spec.name}_plugin#{File.extname(plugin)}")
      end
      Gem.load_plugin_files(plugin_files)
    end

load_relative_enabled? ()
Source

    # File lib/rubygems/installer.rb, line 975
    def load_relative_enabled?
      rb_config["LIBRUBY_RELATIVE"] == "yes"
    end

rb_config ()
Source

    # File lib/rubygems/installer.rb, line 967
    def rb_config
      Gem.target_rbconfig
    end

ruby_install_name ()
Source

    # File lib/rubygems/installer.rb, line 971
    def ruby_install_name
      rb_config["ruby_install_name"]
    end

user_install_dir ()
Source

    # File lib/rubygems/installer.rb, line 938
    def user_install_dir
      # never install to user home in --build-root mode
      return unless @build_root.nil?

      # Please note that @user_install might have three states:
      # * `true`: `--user-install`
      # * `false`: `--no-user-install` and
      # * `nil`: option was not specified
      if @user_install || (@user_install.nil? && Gem.default_user_install)
        Gem.user_dir
      end
    end