--- /dev/null
+require 'rack/utils'
+
+module Rack
+ # Sets the Content-Length header on responses with fixed-length bodies.
+ class ContentLength
+ include Rack::Utils
+
+ def initialize(app)
+ @app = app
+ end
+
+ def call(env)
+ status, headers, body = @app.call(env)
+ headers = HeaderHash.new(headers)
+
+ if !STATUS_WITH_NO_ENTITY_BODY.include?(status) &&
+ !headers['Content-Length'] &&
+ !headers['Transfer-Encoding'] &&
+ (body.respond_to?(:to_ary) || body.respond_to?(:to_str))
+
+ body = [body] if body.respond_to?(:to_str) # rack 0.4 compat
+ length = body.to_ary.inject(0) { |len, part| len + bytesize(part) }
+ headers['Content-Length'] = length.to_s
+ end
+
+ [status, headers, body]
+ end
+ end
+end