Tweaks after review 6

- Only catch InvalidFileNameException.
- Test for InvalidFileNameException instead of Throwable.
- Add CPS style arities to default-invalid-filename-handler
- Extend docstring with information about overriding the default handler
  in the async case.

ring-core/src/ring/middleware/multipart_params.clj

@@ -137,8 +137,11 @@
                  {:multipart-params params}
                  {:params params}))))
 
-(defn default-invalid-filename-handler [request e]
-  (response/bad-request (.getMessage e)))
+(defn default-invalid-filename-handler
+  ([request exception]
+   (response/bad-request (.getMessage exception)))
+  ([request exception respond raise]
+   (respond (default-invalid-filename-handler request exception))))
 
 (defn wrap-multipart-params
   "Middleware to parse multipart parameters from a request. Adds the following
@@ -173,8 +176,9 @@
 
   :invalid-filename-handler
   - A function that gets called when the file being uploaded has an invalid name.
-    The function should expect two parameters: request and an exception of type
-    InvalidFileNameException. It should return a ring response."
+    The sync handler should expect two parameters: request and an exception of
+    type InvalidFileNameException. The async version should expect four: request,
+    exception, respond and raise."
   ([handler]
    (wrap-multipart-params handler {}))
   ([handler options]
@@ -183,14 +187,14 @@
      (fn ([request]
           (let [req-or-ex (try
                             (multipart-params-request request options)
-                            (catch Exception ex ex))]
-            (if (instance? Throwable req-or-ex)
+                            (catch InvalidFileNameException ex ex))]
+            (if (instance? InvalidFileNameException req-or-ex)
               (invalid-filename-handler request req-or-ex)
               (handler req-or-ex))))
        ([request respond raise]
         (let [req-or-ex (try
                           (multipart-params-request request options)
-                          (catch Exception ex ex))]
-          (if (instance? Throwable req-or-ex)
-            (respond (invalid-filename-handler request req-or-ex))
+                          (catch InvalidFileNameException ex ex))]
+          (if (instance? InvalidFileNameException req-or-ex)
+            (invalid-filename-handler request req-or-ex respond raise)
             (handler req-or-ex respond raise))))))))