fix for using mongrel_rails with Rails ~> 2.3.3

config-initializers-mongrel_fix.rb

require 'rewindable_input'
ActionController::Dispatcher.middleware.insert_before ActionController::ParamsParser, RewindableInput

lib-rewindable_input.rb

class RewindableInput
  def initialize(app)
    @app = app
  end

  def call(env)
    begin
      env['rack.input'].rewind
    rescue NoMethodError, Errno::ESPIPE
      # Handles exceptions raised by input streams that cannot be rewound
      # such as when using plain CGI under Apache
      env['rack.input'] = StringIO.new(env['rack.input'].read)
    end

    @app.call(env)
  end
end