Avoid infinite recursion when there is a redirect

[stormsilver]

After upgrading to Rails 4.2.0, I began receiving a SystemStackError when Rails boots. After quite a bit of debugging, I traced it to the fact that I am using the api! method in my controllers to auto-detect the route for a given description. After more debugging, I traced it to the fact that I have several "catchall" redirects in my routes.rb file.

Apparently when the method Apipie::Application#route_app_controller attempts to recursively figure out the controller for a given app, the app generated from redirect satisfies none of the conditions and it will recurse until Ruby stops it.

I'm not sure of the exact fix, someone with more domain knowledge will have to say whether my patch is right or not. I was able to cause the problem under Rails 4.2 by adding the redirect route; I was able to stop the problem by adding another check to the condition.

Let me know if there is something more I can do to help with this PR.

[iNecas]

Hi, thanks for reporting the issue, as well as taking time to investigating it and proposing patch. We might probably generalize that a bit more, not detecting only the direct app.app == app, but every already visited app in the stack (probably passing the list of visited apps as another argument of the method). I'm not sure, if this kind of loop can occur, but better safe than sorry.

[stormsilver]

No problem! Are you thinking of something like this?

    def route_app_controller(app, route, visited_apps = [])
      visited_apps << app
      if app.respond_to?(:controller)
        return app.controller(route.defaults)
      elsif app.respond_to?(:app) && !visited_apps.include?(app.app)
        return route_app_controller(app.app, route, visited_apps)
      end
    rescue ActionController::RoutingError
      # some errors in the routes will not stop us here: just ignoring
    end

[iNecas]

Exactly!

[stormsilver]

@iNecas updated per your comments.

[iNecas]

Thanks a lot @stormsilver . Meging

[iNecas]

apipie-rails 0.3.2 with this fix was just release. Thanks @stormsilver for the contribution!