instiki/vendor/rails/actionpack/lib/action_controller/failsafe.rb

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require 'erb'
module ActionController
# The Failsafe middleware is usually the top-most middleware in the Rack
# middleware chain. It returns the underlying middleware's response, but if
# the underlying middle raises an exception then Failsafe will log the
# exception into the Rails log file, and will attempt to return an error
# message response.
#
# Failsafe is a last resort for logging errors and for telling the HTTP
# client that something went wrong. Do not confuse this with the
# ActionController::Rescue module, which is responsible for catching
# exceptions at deeper levels. Unlike Failsafe, which is as simple as
# possible, Rescue provides features that allow developers to hook into
# the error handling logic, and can customize the error message response
# based on the HTTP client's IP.
class Failsafe
cattr_accessor :error_file_path
self.error_file_path = Rails.public_path if defined?(Rails.public_path)
def initialize(app)
@app = app
end
def call(env)
@app.call(env)
rescue Exception => exception
# Reraise exception in test environment
if defined?(Rails) && Rails.env.test?
raise exception
else
failsafe_response(exception)
end
end
private
def failsafe_response(exception)
log_failsafe_exception(exception)
[500, {'Content-Type' => 'text/html'}, [failsafe_response_body]]
rescue Exception => failsafe_error # Logger or IO errors
$stderr.puts "Error during failsafe response: #{failsafe_error}"
end
def failsafe_response_body
error_template_path = "#{self.class.error_file_path}/500.html"
if File.exist?(error_template_path)
begin
result = render_template(error_template_path)
rescue Exception
result = nil
end
else
result = nil
end
if result.nil?
result = "<html><body><h1>500 Internal Server Error</h1>" <<
"If you are the administrator of this website, then please read this web " <<
"application's log file to find out what went wrong.</body></html>"
end
result
end
# The default 500.html uses the h() method.
def h(text) # :nodoc:
ERB::Util.h(text)
end
def render_template(filename)
ERB.new(File.read(filename)).result(binding)
end
def log_failsafe_exception(exception)
message = "/!\\ FAILSAFE /!\\ #{Time.now}\n Status: 500 Internal Server Error\n"
message << " #{exception}\n #{exception.backtrace.join("\n ")}" if exception
failsafe_logger.fatal(message)
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failsafe_logger.flush if failsafe_logger.respond_to?(:flush)
end
def failsafe_logger
if defined?(Rails) && Rails.logger
Rails.logger
else
Logger.new($stderr)
end
end
end
end