fix a couple file upload problems

Change-Id: I6c8bfb22709655a8bd2cff2375ab0e4be9dcc5ec
Reviewed-on: https://gerrit.instructure.com/2604
Reviewed-by: JT Olds <jt@instructure.com>
Tested-by: Hudson <hudson@instructure.com>

app/controllers/files_controller.rb

@@ -459,6 +459,8 @@ class FilesController < ApplicationController
 
       res[:id] = @attachment.id
       res[:upload_params].merge!({
+        'Filename' => '',
+        'folder' => '',
         'key' => full_filename,
         'acl' => 'private',
         'Policy' => policy_encoded,

lib/authentication_methods.rb

@@ -33,7 +33,8 @@ module AuthenticationMethods
   
   def load_pseudonym_from_policy
     skip_session_save = false
-    if (policy_encoded = params['Policy']) &&
+    if session.to_hash.empty? && # if there's already some session data, defer to normal auth
+        (policy_encoded = params['Policy']) &&
         (signature = params['Signature']) &&
         signature == Base64.encode64(OpenSSL::HMAC.digest(OpenSSL::Digest::Digest.new('sha1'), Attachment.shared_secret, policy_encoded)).gsub(/\n/, '') &&
         (policy = JSON.parse(Base64.decode64(policy_encoded)) rescue nil) &&

public/javascripts/instructure_helper.js

@@ -1950,7 +1950,7 @@
     $newForm.formSubmit({
       fileUpload: true,
       success: success,
-      onlyGivenParameters: options.onlyGivenParameters,
+      onlyGivenParameters: options ? options.onlyGivenParameters : false,
       error: error
     });
     (function() {