Added GzFile for serving gzipped static files

lib/rack.rb

@@ -34,6 +34,7 @@ def self.release
   autoload :ContentType, "rack/content_type"
   autoload :ETag, "rack/etag"
   autoload :File, "rack/file"
+  autoload :GzFile, "rack/gz_file"
   autoload :Deflater, "rack/deflater"
   autoload :Directory, "rack/directory"
   autoload :ForwardRequest, "rack/recursive"

lib/rack/gz_file.rb

@@ -0,0 +1,41 @@
+module Rack
+  # Rack::GzFile behaves exactly the same as Rack::File, except that it will
+  # also serve up a gzip encoding of a file, if one is available on the
+  # filesystem.
+  #
+  # For each request, Rack::GzFile first checks the filesystem for a file with a
+  # .gz extension. If one is found, the appropriate encoding headers are added
+  # to the response and the gzip file is served.
+  #
+  # If no .gz file is found, Rack::GzFile will behave exactly like Rack::File.
+  class GzFile
+    def initialize(root, headers={}, default_mime = 'text/plain')
+      @file_server = Rack::File.new(root, headers, default_mime)
+      @default_mime = default_mime
+    end
+
+    def call(env)
+      path_info = env['PATH_INFO']
+
+      status, headers, body = @file_server.call(
+        env.merge('PATH_INFO' => path_info + '.gz')
+      )
+
+      gzip_available = status != 404
+
+      if !gzip_available || env['HTTP_ACCEPT_ENCODING'] !~ /\bgzip\b/
+        status, headers, body = @file_server.call(env)
+      else
+        headers['Content-Type'] = Mime.mime_type(::File.extname(path_info), 
+                                                 @default_mime)
+        headers['Content-Encoding'] = 'gzip'
+      end
+
+      if gzip_available
+        headers['Vary'] = 'Accept-Encoding'
+      end
+
+      [status, headers, body]
+    end
+  end
+end

test/cgi/assets/compress_me.html

@@ -0,0 +1 @@
+Hello, Rack!

test/spec_gz_file.rb

@@ -0,0 +1,43 @@
+require 'rack/gz_file'
+require 'rack/lint'
+require 'rack/mock'
+require 'zlib'
+
+describe Rack::GzFile do
+  DOCROOT = File.expand_path(File.dirname(__FILE__)) unless defined? DOCROOT
+
+  def request
+    Rack::MockRequest.new(Rack::Lint.new(Rack::GzFile.new(DOCROOT)))
+  end
+
+  should "serve an uncompressed file when gzip is not supported by the server" do
+    res = request.get('/cgi/assets/index.html')
+    res.body.should.equal "### TestFile ###\n"
+    res.headers.should.not.include 'Vary'
+    res.headers.should.not.include('Content-Encoding')
+    res.headers['Content-Length'].should.equal(
+        File.size(DOCROOT + '/cgi/assets/index.html').to_s)
+  end
+
+  should "serve an uncompressed file when gzip is not supported by the client" do
+    res = request.get('/cgi/assets/compress_me.html')
+    res.body.should.equal 'Hello, Rack!'
+    res.headers['Vary'].should.equal 'Accept-Encoding'
+    res.headers.should.not.include('Content-Encoding')
+    res.headers['Content-Length'].should.equal(
+        File.size(DOCROOT + '/cgi/assets/compress_me.html').to_s)
+  end
+
+  should "serve a compressed file" do
+    res = request.get('/cgi/assets/compress_me.html', 
+        'HTTP_ACCEPT_ENCODING' => 'gzip')
+
+    gz = Zlib::GzipReader.new(StringIO.new(res.body))
+    gz.read.should.equal "Hello, Rack!"
+    res.headers['Vary'].should.equal 'Accept-Encoding'
+    res.headers['Content-Encoding'].should.equal 'gzip'
+    res.headers['Content-Type'].should.equal 'text/html'
+    res.headers['Content-Length'].should.equal(
+        File.size(DOCROOT + '/cgi/assets/compress_me.html.gz').to_s)
+  end
+end