require 'ostruct' require 'erb' require 'rack/request' module Rack # Rack::ShowExceptions catches all exceptions raised from the app it # wraps. It shows a useful backtrace with the sourcefile and # clickable context, the whole Rack environment and the request # data. # # Be careful when you use this on public-facing sites as it could # reveal information helpful to attackers. class ShowExceptions CONTEXT = 7 def initialize(app) @app = app @template = ERB.new(TEMPLATE) end def call(env) @app.call(env) rescue StandardError, LoadError, SyntaxError => e [500, {"Content-Type" => "text/html"}, pretty(env, e)] end def pretty(env, exception) req = Rack::Request.new(env) path = (req.script_name + req.path_info).squeeze("/") frames = exception.backtrace.map { |line| frame = OpenStruct.new if line =~ /(.*?):(\d+)(:in `(.*)')?/ frame.filename = $1 frame.lineno = $2.to_i frame.function = $4 begin lineno = frame.lineno-1 lines = ::File.readlines(frame.filename) frame.pre_context_lineno = [lineno-CONTEXT, 0].max frame.pre_context = lines[frame.pre_context_lineno...lineno] frame.context_line = lines[lineno].chomp frame.post_context_lineno = [lineno+CONTEXT, lines.size].min frame.post_context = lines[lineno+1..frame.post_context_lineno] rescue end frame else nil end }.compact env["rack.errors"].puts "#{exception.class}: #{exception.message}" env["rack.errors"].puts exception.backtrace.map { |l| "\t" + l } env["rack.errors"].flush [@template.result(binding)] end def h(obj) # :nodoc: case obj when String Utils.escape_html(obj) else Utils.escape_html(obj.inspect) end end # :stopdoc: # adapted from Django # Copyright (c) 2005, the Lawrence Journal-World # Used under the modified BSD license: # http://www.xfree86.org/3.3.6/COPYRIGHT2.html#5 TEMPLATE = <<'HTML' <%=h exception.class %> at <%=h path %>

<%=h exception.class %> at <%=h path %>

<%=h exception.message %>

Ruby <%=h frames.first.filename %>: in <%=h frames.first.function %>, line <%=h frames.first.lineno %>
Web <%=h req.request_method %> <%=h(req.host + path)%>

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Traceback (innermost first)

Request information

GET

<% unless req.GET.empty? %> <% req.GET.sort_by { |k, v| k.to_s }.each { |key, val| %> <% } %>
Variable Value
<%=h key %>
<%=h val.inspect %>
<% else %>

No GET data.

<% end %>

POST

<% unless req.POST.empty? %> <% req.POST.sort_by { |k, v| k.to_s }.each { |key, val| %> <% } %>
Variable Value
<%=h key %>
<%=h val.inspect %>
<% else %>

No POST data.

<% end %> <% unless req.cookies.empty? %> <% req.cookies.each { |key, val| %> <% } %>
Variable Value
<%=h key %>
<%=h val.inspect %>
<% else %>

No cookie data.

<% end %>

Rack ENV

<% env.sort_by { |k, v| k.to_s }.each { |key, val| %> <% } %>
Variable Value
<%=h key %>
<%=h val %>

You're seeing this error because you use Rack::ShowException.

HTML # :startdoc: end end