1 files changed, 32 insertions, 0 deletions
diff --git a/Library/Homebrew/utils.rb b/Library/Homebrew/utils.rb
index c37633e41..60af39d93 100644
--- a/Library/Homebrew/utils.rb
+++ b/Library/Homebrew/utils.rb
@@ -221,6 +221,38 @@ module Homebrew
     EOS
   end
 
+  def run_bundler_if_needed!
+    return unless Pathname.glob("#{HOMEBREW_GEM_HOME}/bin/*").empty?
+
+    if Gem::Specification.find_all_by_name("bundler").empty?
+      ohai "Installing Bundler..."
+
+      # Do `gem install [...]` without having to spawn a separate process or
+      # having to find the right `gem` binary for the running Ruby interpreter.
+      require "rubygems/commands/install_command"
+      install_cmd = Gem::Commands::InstallCommand.new
+      install_cmd.handle_options(%w[--no-ri --no-rdoc bundler])
+      exit_code = 1 # Should not matter as `install_cmd.execute` always throws.
+      begin
+        install_cmd.execute
+      rescue Gem::SystemExitException => e
+        exit_code = e.exit_code
+      end
+      odie "Failed to install Bundler!" if exit_code.nonzero?
+    end
+
+    HOMEBREW_REPOSITORY.cd do
+      unless quiet_system("bundle", "check")
+        ohai "Installing RubyGems..."
+        success = system "bundle", "install",
+                         "--path", "Library/Homebrew/vendor",
+                         "--standalone",
+                         "--jobs", "3"
+        odie "Failed to install RubyGems!" unless success
+      end
+    end
+  end
+
   # Hash of Module => Set(method_names)
   @injected_dump_stat_modules = {}