Add :max-file-size option to wrap-multipart-params

[ryfow]

I'd like to be able to limit the size of the files read/created by wrap-multipart params. This change accomplishes that by setting FileUpload.setFileSizeMax but I need some guidance on:

1. Error handling. Right now it just propagates the commons-fileupload exception.

2. Testing. I don't see an example of testing the actual MIME parsing. I'm wondering what you'd like to see.

Thanks!
Ryan

[weavejester]

Please see PR #98.

[ryfow]

Thanks. Sorry for not looking that up.

After reading that thread I decided what I really want is a limit on the request size. This is what I ended up with. If you think this would be generally useful, I'll submit another PR.

(defn- limited-stream [is max-size]
  (proxy [LimitedInputStream]
      [is max-size]
    (raiseError [max count]
      (throw (ex-info "Request too large."
                      {:max max
                       :count count
                       :type :request-too-large})))))

(defn wrap-request-size-limit [h max-size request-too-large-fn]
  (fn [r]
    (let [content-length (Long/valueOf (get-in r [:headers "content-length"] "0"))
          body (:body r)]
      (cond (< max-size content-length)
            (request-too-large-fn r max-size content-length)

            (instance? java.io.InputStream body)
            (try
              (h (assoc r :body (limited-stream body max-size)))
              (catch Exception e
                (let [d (ex-data e)]
                  (if (= (:type d) :request-too-large)
                    (request-too-large-fn r (:max d) (:count d))
                    (throw e)))))

            :default
            (h r)))))

[weavejester]

I'm currently considering merging #98 into Ring 1.4, because the rewrite of the multipart namespace keeps getting delayed.

In general, new middleware like wrap-request-size-limit should be tried out as a third party library first. If it proves sufficiently popular, it can then be merged into Ring core.