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 = {})

Construct an installer object for the gem file located at path

# 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

exec_format ()

Defaults to use Ruby’s program prefix and suffix.

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

for_spec (spec, options = {})

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

# 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

new (package, options = {})

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

# 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

Public Instance Methods

app_script_text (bin_file_name)

Return the text for an application file.

# File lib/rubygems/installer.rb, line 715
  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
    <<~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}', '#{bin_file_name}', version)
      else
        load Gem.activate_bin_path('#{spec.name}', '#{bin_file_name}', version)
      end
    TEXT
  end

build_extensions ()

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

# File lib/rubygems/installer.rb, line 806
def build_extensions
  builder = Gem::Ext::Builder.new spec, build_args, Gem.target_rbconfig, build_jobs

  builder.build_extensions
end

default_spec_dir ()

# 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 ()

The location of the default spec file for default gems.

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

dir ()

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

# File lib/rubygems/installer.rb, line 847
def dir
  gem_dir.to_s
end

ensure_dependency (spec, dependency)

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

# 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_loadable_spec ()

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

# 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

explicit_version_requirement (name)

# File lib/rubygems/installer.rb, line 757
  def explicit_version_requirement(name)
    code = "version = str"
    return code unless name == "bundler"

    code += <<~TEXT

      ENV['BUNDLER_VERSION'] = str
    TEXT
  end

extract_bin ()

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.

# File lib/rubygems/installer.rb, line 826
def extract_bin
  @package.extract_files gem_dir, "#{spec.bindir}/*"
end

extract_files ()

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

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

# File lib/rubygems/installer.rb, line 817
def extract_files
  @package.extract_files gem_dir
end

formatted_program_filename (filename)

Prefix and suffix the program filename the same as ruby.

# File lib/rubygems/installer.rb, line 833
def formatted_program_filename(filename)
  if @format_executable
    self.class.exec_format % File.basename(filename)
  else
    filename
  end
end

gem ()

Filename of the gem being installed.

# File lib/rubygems/installer.rb, line 854
def gem
  @package.gem.path
end

gem_dir ()

Lazy accessor for the spec’s gem directory.

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

gemdeps_load (name)

# File lib/rubygems/installer.rb, line 748
  def gemdeps_load(name)
    return "" if name == "bundler"

    <<~TEXT

      Gem.use_gemdeps
    TEXT
  end

generate_bin_script (filename, bindir)

Creates the scripts to run the applications in the gem.

# 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

generate_bin_symlink (filename, bindir)

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

# 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

generate_windows_script (filename, bindir)

Creates windows .bat files for easy running of commands

# 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

install ()

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

# 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 spec.post_install_message 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

installation_satisfies_dependency? (dependency)

True if the gems in the system satisfy dependency.

# 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

installed_specs ()

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

# 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

pre_install_checks ()

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.

# File lib/rubygems/installer.rb, line 867
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

shebang (bin_file_name)

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

# 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

spec ()

Lazy accessor for the installer’s spec.

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

spec_file ()

The location of the spec file that is installed.

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

verify_spec ()

# 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
end

windows_stub_script (bindir, bin_file_name)

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

# File lib/rubygems/installer.rb, line 770
  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

write_build_info_file ()

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

# File lib/rubygems/installer.rb, line 889
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

write_cache_file ()

Writes the .gem file to the cache directory

# File lib/rubygems/installer.rb, line 911
def write_cache_file
  cache_file = File.join gem_home, "cache", spec.file_name
  @package.copy_to cache_file
end

write_default_spec ()

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.

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

write_spec ()

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

# 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