diff -u modules/update/update.manager.inc modules/update/update.manager.inc
--- modules/update/update.manager.inc	26 Oct 2009 05:44:47 -0000
+++ modules/update/update.manager.inc	26 Oct 2009 06:23:51 -0000
@@ -426,22 +426,12 @@
       );
     }
 
-    // If the owner of the last directory we extracted is the same as the
-    // owner of our configuration directory (e.g. sites/default) where we're
-    // trying to install the code, there's no need to prompt for FTP/SSH
-    // credentials. Instead, we instantiate a FileTransferLocal and invoke
-    // update_authorize_run_update() directly.
-    if (fileowner($project_real_location) == fileowner(conf_path())) {
-      module_load_include('inc', 'update', 'update.authorize');
-      $filetransfer = new FileTransferLocal(DRUPAL_ROOT);
-      update_authorize_run_update($filetransfer, $updates);
-    }
-    // Otherwise, go through the regular workflow to prompt for FTP/SSH
-    // credentials and invoke update_authorize_run_update() indirectly with
-    // whatever FileTransfer object authorize.php creates for us.
-    else {
-      system_run_authorized('update_authorize_run_update', drupal_get_path('module', 'update') . '/update.authorize.inc', array($updates));
-    }
+    // Finally, trigger the next step in the workflow, which will either
+    // redirect to authorize.php to prompt for FTP/SSH credentials, or to
+    // directly trigger the updates via Batch API if the install location
+    // (e.g. sites/default) is already owned by the same UID that the web
+    // server is running as.
+    _update_manager_run_authorized('update_authorize_run_update', $updates, $project_real_location);
   }
 }
 
@@ -588,22 +578,12 @@
     'local_url' => $project_real_location,
   );
 
-  // If the owner of the directory we extracted is the same as the
-  // owner of our configuration directory (e.g. sites/default) where we're
-  // trying to install the code, there's no need to prompt for FTP/SSH
-  // credentials. Instead, we instantiate a FileTransferLocal and invoke
-  // update_authorize_run_install() directly.
-  if (fileowner($project_real_location) == fileowner(conf_path())) {
-    module_load_include('inc', 'update', 'update.authorize');
-    $filetransfer = new FileTransferLocal(DRUPAL_ROOT);
-    call_user_func_array('update_authorize_run_install', array_merge(array($filetransfer), $arguments));
-  }
-  // Otherwise, go through the regular workflow to prompt for FTP/SSH
-  // credentials and invoke update_authorize_run_install() indirectly with
-  // whatever FileTransfer object authorize.php creates for us.
-  else {
-    system_run_authorized('update_authorize_run_install', drupal_get_path('module', 'update') . '/update.authorize.inc', $arguments);
-  }
+  // Finally, trigger the next step in the workflow, which will either
+  // redirect to authorize.php to prompt for FTP/SSH credentials, or to
+  // directly trigger the updates via Batch API if the install location
+  // (e.g. sites/default) is already owned by the same UID that the web
+  // server is running as.
+  _update_manager_run_authorized('update_authorize_run_install', $arguments, $project_real_location);
 }
 
 /**
@@ -616,6 +596,51 @@
  */
 
 /**
+ * Run a given Update manager operation with elevated file access permissions.
+ *
+ * If the files we just extracted are owned by the same UID as the owner of
+ * our configuration directory (e.g. sites/default) where we're trying to
+ * install the code, there's no need to prompt for FTP/SSH credentials.
+ * Instead, we instantiate a FileTransferLocal and invoke the operation
+ * directly.
+ *
+ * Otherwise, we go through the regular authorize.php workflow to prompt for
+ * FTP/SSH credentials and invoke the operation indirectly with whatever
+ * FileTransfer object authorize.php creates for us.
+ *
+ * @param $operation
+ *   The name of the operation callback to invoke.
+ * @param $arguments
+ *   Arguments to pass to the operation callback.
+ * @param $extracted_path
+ *   The full path to a project we just extracted to compare ownership.
+ */
+function _update_manager_run_authorized($operation, $arguments, $extracted_path) {
+  if (fileowner($extracted_path) == fileowner(conf_path())) {
+    module_load_include('inc', 'update', 'update.authorize');
+    $filetransfer = new FileTransferLocal(DRUPAL_ROOT);
+    switch ($operation) {
+      case 'update_authorize_run_update':
+        update_authorize_run_update($filetransfer, $arguments);
+        break;
+
+      case 'update_authorize_run_install':
+        call_user_func_array('update_authorize_run_install', array_merge(array($filetransfer), $arguments));
+        break;
+    }
+  }
+  else {
+    // update_authorize_run_update() expects a nested array, and the way
+    // authorize.php invokes our callback we need to wrap our arguments in an
+    // array here.
+    if ($operation == 'update_authorize_run_update') {
+      $arguments = array($arguments);
+    }
+    system_run_authorized($operation, drupal_get_path('module', 'update') . '/update.authorize.inc', $arguments);
+  }
+}
+
+/**
  * Return the directory where update archive files should be extracted.
  *
  * If the directory does not already exist, attempt to create it.