1 files changed, 77 insertions, 0 deletions
diff --git a/pkgs/development/interpreters/ruby/build-ruby-gem/gem-post-build.rb b/pkgs/development/interpreters/ruby/build-ruby-gem/gem-post-build.rb
new file mode 100644
index 00000000000..112a9accc33
--- /dev/null
+++ b/pkgs/development/interpreters/ruby/build-ruby-gem/gem-post-build.rb
@@ -0,0 +1,77 @@
+require 'rbconfig'
+require 'rubygems'
+require 'rubygems/specification'
+require 'fileutils'
+
+ruby = File.join(ENV["ruby"], "bin", RbConfig::CONFIG['ruby_install_name'])
+out = ENV["out"]
+bin_path = File.join(ENV["out"], "bin")
+gem_home = ENV["GEM_HOME"]
+gem_path = ENV["GEM_PATH"].split(":")
+install_path = Dir.glob("#{gem_home}/gems/*").first
+gemspec_path = ARGV[0]
+
+if defined?(Encoding.default_internal)
+  Encoding.default_internal = Encoding::UTF_8
+  Encoding.default_external = Encoding::UTF_8
+end
+
+gemspec_content = File.read(gemspec_path)
+spec = nil
+if gemspec_content[0..2] == "---" # YAML header
+  spec = Gem::Specification.from_yaml(gemspec_content)
+else
+  spec = Gem::Specification.load(gemspec_path)
+end
+
+FileUtils.mkdir_p("#{out}/nix-support")
+
+# write meta-data
+meta = "#{out}/nix-support/gem-meta"
+FileUtils.mkdir_p(meta)
+FileUtils.ln_s(gemspec_path, "#{meta}/spec")
+File.open("#{meta}/name", "w") do |f|
+  f.write(spec.name)
+end
+File.open("#{meta}/install-path", "w") do |f|
+  f.write(install_path)
+end
+File.open("#{meta}/require-paths", "w") do |f|
+  f.write(spec.require_paths.join(" "))
+end
+File.open("#{meta}/executables", "w") do |f|
+  f.write(spec.executables.join(" "))
+end
+
+# add this gem to the GEM_PATH for dependencies
+File.open("#{out}/nix-support/setup-hook", "a") do |f|
+  f.puts("addToSearchPath GEM_PATH #{gem_home}")
+  spec.require_paths.each do |dir|
+    f.puts("addToSearchPath RUBYLIB #{install_path}/#{dir}")
+  end
+end
+
+# create regular rubygems binstubs
+FileUtils.mkdir_p(bin_path)
+spec.executables.each do |exe|
+  File.open("#{bin_path}/#{exe}", "w") do |f|
+    f.write(<<-EOF)
+#!#{ruby}
+#
+# This file was generated by Nix.
+#
+# The application '#{exe}' is installed as part of a gem, and
+# this file is here to facilitate running it.
+#
+
+gem_path = ENV["GEM_PATH"]
+ENV["GEM_PATH"] = "\#{gem_path}\#{":" unless gem_path.nil? || gem_path.empty?}#{(gem_path+[gem_home]).join(":")}"
+
+require 'rubygems'
+
+load Gem.bin_path(#{spec.name.inspect}, #{exe.inspect})
+    EOF
+  end
+
+  FileUtils.chmod("+x", "#{bin_path}/#{exe}")
+end