#538660 by JacobSingh, dww, JoshuaRogers, adrian, Crell, chx, anarcat, and cwgordon7: Add a functioning Plugin Manager to core. Can you say module installation and updates through the UI? I knew you could! :D

5 files changed, 756 insertions, 22 deletions

diff --git a/includes/authorize.inc b/includes/authorize.inc
new file mode 100644
index 000000000..b97d8a288
--- /dev/null
+++ b/includes/authorize.inc
@@ -0,0 +1,232 @@
+<?php
+// $Id$
+
+/**
+ * @file
+ * Helper functions and form handlers used for the authorize.php script.
+ */
+
+/**
+ * Build the form for choosing a FileTransfer type and supplying credentials.
+ */
+function authorize_filetransfer_form($form_state) {
+  global $base_url;
+  $form = array();
+
+  $form['#action'] = $base_url . '/authorize.php';
+  // CSS we depend on lives in modules/system/maintenance.css, which is loaded
+  // via the default maintenance theme.
+  $form['#attached']['js'][] = $base_url . '/misc/authorize.js';
+  
+  // Get all the available ways to transfer files.
+  if (empty($_SESSION['authorize_filetransfer_backends'])) {
+    drupal_set_message(t('Unable to continue, no available methods of file transfer'), 'error');
+    return array();
+  }
+  $available_backends = $_SESSION['authorize_filetransfer_backends'];
+  uasort($available_backends, 'drupal_sort_weight');
+
+  // Decide on a default backend.
+  if (isset($form_state['values']['connection_settings']['authorize_filetransfer_default'])) {
+    $authorize_filetransfer_default = $form_state['values']['connection_settings']['authorize_filetransfer_default'];
+  }
+  elseif ($authorize_filetransfer_default = variable_get('authorize_filetransfer_default', NULL));
+  else {
+    $authorize_filetransfer_default = key($available_backends);
+  }
+
+  $form['information']['main_header'] = array(
+    '#prefix' => '<h3>',
+    '#markup' => t('To continue please provide your server connection details'),
+    '#suffix' => '</h3>',
+  );
+
+  $form['connection_settings']['#tree'] = TRUE;
+  $form['connection_settings']['authorize_filetransfer_default'] = array(
+    '#type' => 'select',
+    '#title' => t('Connection method'),
+    '#default_value' => $authorize_filetransfer_default,
+    '#weight' => -10,
+  );
+
+  /*
+   * Here we create two submit buttons. For a JS enabled client, they will
+   * only ever see submit_process. However, if a client doesn't have JS
+   * enabled, they will see submit_connection on the first form (whden picking
+   * what filetranfer type to use, and submit_process on the second one (which
+   * leads to the actual operation)
+   */
+  $form['submit_connection'] = array(
+    '#prefix' => "<br style='clear:both'/>",
+    '#name' => 'enter_connection_settings', // This is later changed in JS.
+    '#type' => 'submit',
+    '#value' => t('Enter connetion settings'), // As is this. @see authorize.js.
+    '#weight' => 100,
+  );
+
+  $form['submit_process'] = array(
+    '#name' => 'process_updates', // This is later changed in JS.
+    '#type' => 'submit',
+    '#value' => t('Process Updates'), // As is this. @see authorize.js
+    '#weight' => 100,
+    '#attributes' => array('style' => 'display:none'),
+  );
+
+  // Build a hidden fieldset for each one.
+  foreach ($available_backends as $name => $backend) {
+    $form['connection_settings']['authorize_filetransfer_default']['#options'][$name] = $backend['title'];
+    $form['connection_settings'][$name] = array(
+      '#type' => 'fieldset',
+      '#attributes' => array('class' => "filetransfer-$name filetransfer"),
+      '#title' => t('@backend connection settings', array('@backend' => $backend['title'])),
+    );
+
+    $current_settings = variable_get("authorize_filetransfer_connection_settings_" . $name, array());
+    $form['connection_settings'][$name] += system_get_filetransfer_settings_form($name, $current_settings);
+
+    // Start non-JS code.
+    if (isset($form_state['values']['connection_settings']['authorize_filetransfer_default']) && $form_state['values']['connection_settings']['authorize_filetransfer_default'] == $name) {
+
+      // If the user switches from JS to non-JS, Drupal (and Batch API) will
+      // barf. This is a known bug: http://drupal.org/node/229825.
+      setcookie('has_js', '', time() - 3600, '/');
+      unset($_COOKIE['has_js']);
+
+      // Change the submit button to the submit_process one.
+      $form['submit_process']['#attributes'] = array();
+      unset($form['submit_connection']);
+
+      // Activate the proper filetransfer settings form.
+      $form['connection_settings'][$name]['#attributes']['style'] = 'display:block';
+      // Disable the select box.
+      $form['connection_settings']['authorize_filetransfer_default']['#disabled'] = TRUE;
+
+      // Create a button for changing the type of connection.
+      $form['connection_settings']['change_connection_type'] = array(
+        '#name' => 'change_connection_type',
+        '#type' => 'submit',
+        '#value' => t('Change connection type'),
+        '#weight' => -5,
+        '#attributes' => array('class' => 'filetransfer-change-connection-type'),
+      );
+    }
+    // End non-JS code.
+  }
+  return $form;
+}
+
+/**
+ * Validate callback for the filetransfer authorization form.
+ *
+ * @see authorize_filetransfer_form()
+ */
+function authorize_filetransfer_form_validate($form, &$form_state) {
+  if (isset($form_state['values']['connection_settings'])) {
+    $backend = $form_state['values']['connection_settings']['authorize_filetransfer_default'];
+    $filetransfer = authorize_get_filetransfer($backend, $form_state['values']['connection_settings'][$backend]);
+    try {
+      if (!$filetransfer) {
+        throw new Exception(t("Error, this type of connection protocol (%backend) doesn't exist.", array('%backend' => $backend)));
+      }
+      $filetransfer->connect();
+    }
+    catch (Exception $e) {
+      form_set_error('connection_settings', $e->getMessage());
+    }
+  }
+}
+
+/**
+ * Submit callback when a file transfer is being authorized.
+ *
+ * @see authorize_filetransfer_form()
+ */
+function authorize_filetransfer_form_submit($form, &$form_state) {
+  global $base_url;
+  switch ($form_state['clicked_button']['#name']) {
+    case 'process_updates':
+
+      // Save the connection settings to the DB.
+      $filetransfer_backend = $form_state['values']['connection_settings']['authorize_filetransfer_default'];
+
+      // If the database is available then try to save our settings. We have
+      // to make sure it is available since this code could potentially (will
+      // likely) be called during the installation process, before the
+      // database is set up.
+      if (db_is_active()) {
+        $connection_settings = array();
+        foreach ($form_state['values']['connection_settings'][$filetransfer_backend] as $key => $value) {
+          // We do *not* want to store passwords in the database, unless the
+          // backend explicitly says so via the magic #filetransfer_save form
+          // property. Otherwise, we store everything that's not explicitly
+          // marked with #filetransfer_save set to FALSE.
+          if (!isset($form['connection_settings'][$filetransfer_backend][$key]['#filetransfer_save'])) {
+            if ($form['connection_settings'][$filetransfer_backend][$key]['#type'] != 'password') {
+              $connection_settings[$key] = $value;
+            }
+          }
+          // The attribute is defined, so only save if set to TRUE.
+          elseif ($form['connection_settings'][$filetransfer_backend][$key]['#filetransfer_save']) {
+            $connection_settings[$key] = $value;
+          }
+        }
+        // Set this one as the default authorize method.
+        variable_set('authorize_filetransfer_default', $filetransfer_backend);
+        // Save the connection settings minus the password.
+        variable_set("authorize_filetransfer_connection_settings_" . $filetransfer_backend, $connection_settings);
+
+        $filetransfer = authorize_get_filetransfer($filetransfer_backend, $form_state['values']['connection_settings'][$filetransfer_backend]);
+        
+        // Now run the operation.
+        authorize_run_operation($filetransfer);
+      }
+      break;
+
+    case 'enter_connection_settings':
+      $form_state['rebuild'] = TRUE;
+      break;
+
+    case 'change_connection_type':
+      $form_state['rebuild'] = TRUE;
+      unset($form_state['values']['connection_settings']['authorize_filetransfer_default']);
+      break;
+  }
+}
+
+/**
+ * Run the operation specified in $_SESSION['authorize_operation']
+ *
+ * @param $filetransfer
+ *   The FileTransfer object to use for running the operation.
+ */
+function authorize_run_operation($filetransfer) {
+  $operation = $_SESSION['authorize_operation'];
+  unset($_SESSION['authorize_operation']);
+
+  if (!empty($operation['page_title'])) {
+    drupal_set_title(check_plain($operation['page_title']));
+  }
+
+  require_once DRUPAL_ROOT . '/' . $operation['file'];
+  call_user_func_array($operation['callback'], array_merge(array($filetransfer), $operation['arguments']));
+}
+
+/**
+ * Get a FileTransfer class for a specific transfer method and settings.
+ *
+ * @param $backend
+ *   The FileTransfer backend to get the class for.
+ * @param $settings
+ *   Array of settings for the FileTransfer.
+ * @return
+ *   An instantiated FileTransfer object for the requested method and settings,
+ *   or FALSE if there was an error finding or instantiating it.
+ */
+function authorize_get_filetransfer($backend, $settings = array()) {
+  $filetransfer = FALSE;
+  if (!empty($_SESSION['authorize_filetransfer_backends'][$backend])) {
+    $filetransfer = call_user_func_array(array($_SESSION['authorize_filetransfer_backends'][$backend]['class'], 'factory'), array(DRUPAL_ROOT, $settings));
+  }
+  return $filetransfer;
+}
+
diff --git a/includes/common.inc b/includes/common.inc
index a72039566..bcc2cbd22 100644
--- a/includes/common.inc
+++ b/includes/common.inc
@@ -4993,23 +4993,10 @@ function drupal_common_theme() {
       'arguments' => array('page' => NULL),
       'template' => 'page',
     ),
-    'maintenance_page' => array(
-      'arguments' => array('content' => NULL, 'show_messages' => TRUE),
-      'template' => 'maintenance-page',
-    ),
-    'update_page' => array(
-      'arguments' => array('content' => NULL, 'show_messages' => TRUE),
-    ),
-    'install_page' => array(
-      'arguments' => array('content' => NULL),
-    ),
     'region' => array(
       'arguments' => array('elements' => NULL),
       'template' => 'region',
     ),
-    'task_list' => array(
-      'arguments' => array('items' => NULL, 'active' => NULL),
-    ),
     'status_messages' => array(
       'arguments' => array('display' => NULL),
     ),
@@ -5064,6 +5051,26 @@ function drupal_common_theme() {
     'indentation' => array(
       'arguments' => array('size' => 1),
     ),
+    // from theme.maintenance.inc
+    'maintenance_page' => array(
+      'arguments' => array('content' => NULL, 'show_messages' => TRUE),
+      'template' => 'maintenance-page',
+    ),
+    'update_page' => array(
+      'arguments' => array('content' => NULL, 'show_messages' => TRUE),
+    ),
+    'install_page' => array(
+      'arguments' => array('content' => NULL),
+    ),
+    'task_list' => array(
+      'arguments' => array('items' => NULL, 'active' => NULL),
+    ),
+    'authorize_message' => array(
+      'arguments' => array('message' => NULL, 'success' => TRUE),
+    ),
+    'authorize_report' => array(
+      'arguments' => array('messages' => array()),
+    ),
     // from pager.inc
     'pager' => array(
       'arguments' => array('tags' => array(), 'element' => 0, 'parameters' => array(), 'quantity' => 9),
@@ -5989,3 +5996,26 @@ function archiver_get_archiver($file) {
   }
 }
 
+/**
+ * Drupal Updater registry.
+ *
+ * An Updater is a class that knows how to update various parts of the Drupal
+ * file system, for example to update modules that have newer releases, or to
+ * install a new theme.
+ *
+ * @return
+ *   Returns the Drupal Updater class registry.
+ *
+ * @see hook_updater_info()
+ * @see hook_updater_info_alter()
+ */
+function drupal_get_updaters() {
+  $updaters = &drupal_static(__FUNCTION__);
+  if (!isset($updaters)) {
+    $updaters = module_invoke_all('updater_info');
+    drupal_alter('updater_info', $updaters);
+    uasort($updaters, 'drupal_sort_weight');
+  }
+  return $updaters;
+}
+
diff --git a/includes/filetransfer/ftp.inc b/includes/filetransfer/ftp.inc
index 32e02901a..48b745ab2 100644
--- a/includes/filetransfer/ftp.inc
+++ b/includes/filetransfer/ftp.inc
@@ -5,6 +5,15 @@
  * Connection class using the FTP URL wrapper.
  */
 class FileTransferFTPWrapper extends FileTransfer {
+
+  public function __construct($jail, $username, $password, $hostname, $port) {
+    $this->username = $username;
+    $this->password = $password;
+    $this->hostname = $hostname;
+    $this->port = $port;
+    parent::__construct($jail);
+  }
+  
   function connect() {
     $this->connection = 'ftp://' . urlencode($this->username) . ':' . urlencode($this->password) . '@' . $this->hostname . ':' . $this->port . '/';
     if (!is_dir($this->connection)) {
@@ -19,29 +28,29 @@ class FileTransferFTPWrapper extends FileTransfer {
   }
 
   function createDirectoryJailed($directory) {
-    if (!@drupal_mkdir($directory)) {
+    if (!@drupal_mkdir($this->connection . $directory)) {
       $exception = new FileTransferException('Cannot create directory @directory.', NULL, array('@directory' => $directory));
       throw $exception;
     }
   }
 
   function removeDirectoryJailed($directory) {
-    if (is_dir($directory)) {
-      $dh = opendir($directory);
+    if (is_dir($this->connection . $directory)) {
+      $dh = opendir($this->connection . $directory);
       while (($resource = readdir($dh)) !== FALSE) {
         if ($resource == '.' || $resource == '..') {
           continue;
         }
         $full_path = $directory . DIRECTORY_SEPARATOR . $resource;
-        if (is_file($full_path)) {
+        if (is_file($this->connection . $full_path)) {
           $this->removeFile($full_path);
         }
-        elseif (is_dir($full_path)) {
+        elseif (is_dir($this->connection . $full_path)) {
           $this->removeDirectory($full_path . '/');
         }
       }
       closedir($dh);
-      if (!rmdir($directory)) {
+      if (!rmdir($this->connection . $directory)) {
         $exception = new FileTransferException('Cannot remove @directory.', NULL, array('@directory' => $directory));
         throw $exception;
       }
@@ -70,15 +79,18 @@ class FileTransferFTPWrapper extends FileTransfer {
   }
 
   /**
-   * This is impossible with the stream wrapper,
-   * So we cheat and use the other implementation
+   * This is impossible with the stream wrapper, so an exception is thrown.
+   *
+   * If the ftp extenstion is available, we will cheat and use it.
    *
-   * @staticvar FileTransferFTPExtension $ftp_ext_file_transfer
    * @param string $path
    * @param long $mode
    * @param bool $recursive
    */
   function chmodJailed($path, $mode, $recursive) {
+    if (!function_exists('ftp_connect')) {
+      throw new FileTransferException('Unable to set permissions on @path.  Change umask settings on server to be world executable.', array('@path' => $path));
+    }
     static $ftp_ext_file_transfer;
 
     if (!$ftp_ext_file_transfer) {
diff --git a/includes/theme.maintenance.inc b/includes/theme.maintenance.inc
index e2ebc9342..a625e15c0 100644
--- a/includes/theme.maintenance.inc
+++ b/includes/theme.maintenance.inc
@@ -202,3 +202,48 @@ function theme_update_page($variables) {
 
   return theme_render_template('themes/garland/maintenance-page.tpl.php', $variables);
 }
+
+/**
+ * Generate a report of the results from an operation run via authorize.php.
+ *
+ * @param array $variables
+ *   - messages: An array of result messages.
+ */
+function theme_authorize_report($variables) {
+  $messages = $variables['messages'];
+  $output = '';
+  if (!empty($messages)) {
+    $output .= '<div id="authorize-results">';
+    foreach ($messages as $heading => $logs) {
+      $output .= '<h3>' . check_plain($heading) . '</h3>';
+      foreach ($logs as $number => $log_message) {
+        if ($number === '#abort') {
+          continue;
+        }
+        $output .= theme('authorize_message', array('message' => $log_message['message'], 'success' => $log_message['success']));
+      }
+    }
+    $output .= '</div>';
+  }
+  return $output;
+}
+
+/**
+ * Render a single log message from the authorize.php batch operation.
+ *
+ * @param $variables
+ *   - message: The log message.
+ *   - success: A boolean indicating failure or success.
+ */
+function theme_authorize_message($variables) {
+  $output = '';
+  $message = $variables['message'];
+  $success = $variables['success'];
+  if ($success) {
+    $output .= '<li class="success">' . $message . '</li>';
+  }
+  else {
+    $output .= '<li class="failure"><strong>' . t('Failed') . ':</strong> ' . $message . '</li>';
+  }
+  return $output;
+}
diff --git a/includes/updater.inc b/includes/updater.inc
new file mode 100644
index 000000000..e11f8e1af
--- /dev/null
+++ b/includes/updater.inc
@@ -0,0 +1,415 @@
+<?php
+// $Id$
+
+/**
+ * @file
+ * Classes used for updating various files in the Drupal webroot. These
+ * classes use a FileTransfer object to actually perform the operations.
+ * Normally, the FileTransfer is provided when the site owner is redirected to
+ * authorize.php as part of a multistep process.
+ */
+ 
+/**
+ * Interface for a class which can update a Drupal project.
+ *
+ * An Updater currently serves the following purposes:
+ *   - It can take a given directory, and determine if it can operate on it.
+ *   - It can move the contents of that directoy into the appropriate place
+ *     on the system using FileTransfer classes.
+ *   - It can return a list of "next steps" after an update or install.
+ *   - In the future, it will most likely perform some of those steps as well.
+ */
+interface DrupalUpdaterInterface {
+
+  /**
+   * Checks if the project is installed.
+   * @return bool
+   */
+  public function isInstalled();
+
+  /**
+   * Returns the system name of the project.
+   *
+   * @param string $directory
+   *  A directory containing a project.
+   */
+  public static function getProjectName($directory);
+
+  /**
+   * @return string an absolute path to the default install location.
+   */
+  public function getInstallDirectory();
+
+  /**
+   * Determine if the Updater can handle the project provided in $directory.
+   *
+   * @todo: Provide something more rational here, like a project spec file.
+   *
+   * @param string $directory
+   *
+   * @return bool
+   */
+  public static function canUpdateDirectory($directory);
+
+  /**
+   * Actions to run after an install has occurred.
+   */
+  public function postInstall();
+
+  /**
+   * Actions to run after an update has occurred.
+   */
+  public function postUpdate();
+}
+
+/**
+ * Base class for Updaters used in Drupal.
+ */
+class Updater {
+
+  /**
+   * @var string $source Directory to install from.
+   */
+  public $source;
+  
+  public function __construct($source) {
+    $this->source = $source;
+    $this->name = self::getProjectName($source);
+    $this->title = self::getProjectTitle($source);
+  }
+
+  /**
+   * Return an Updater of the appropriate type depending on the source.
+   *
+   * If a directory is provided which contains a module, will return a
+   * ModuleUpdater.
+   *
+   * @param string $source
+   *   Directory of a Drupal project.
+   *
+   * @return object Updater
+   */
+  public static function factory($source) {
+    if (is_dir($source)) {
+      $updater = self::getUpdaterFromDirectory($source);
+    }
+    else {
+      throw new UpdaterException(t('Unable to determine the type of the source directory.'));
+    }
+    return new $updater($source);
+  }
+
+  /**
+   * Determine which Updater class can operate on the given directory.
+   *
+   * @param string $directory
+   *   Extracted Drupal project.
+   * @return string
+   *   The class name which can work with this project type.
+   */
+  public static function getUpdaterFromDirectory($directory) {
+    // Gets a list of possible implementing classes.
+    $updaters = drupal_get_updaters();
+    foreach ($updaters as $updater) {
+      $class = $updater['class'];
+      if (call_user_func("{$class}::canUpdateDirectory", $directory)) {
+        return $class;
+      }
+    }
+    throw new UpdaterException(t('Cannot determine the type of project.'));
+  }
+
+  /**
+   * Figure out what the most important (or only) info file is in a directory.
+   *
+   * Since there is no enforcement of which info file is the project's "main"
+   * info file, this will get one with the same name as the directory, or the
+   * first one it finds.  Not ideal, but needs a larger solution.
+   *
+   * @param string $directory
+   *   Directory to search in.
+   * @return string
+   *   Path to the info file.
+   */
+  public static function findInfoFile($directory) {
+    $info_files = file_scan_directory($directory, '/.*\.info/');
+    if (!$info_files) {
+      return FALSE;
+    }
+    foreach ($info_files as $info_file) {
+      if (drupal_substr($info_file->filename, 0, -5) == basename($directory)) {
+        // Info file Has the same name as the directory, return it.
+        return $info_file->uri;
+      }
+    }
+    // Otherwise, return the first one.
+    $info_file = array_shift($info_files);
+    return $info_file->uri;
+  }
+
+  /**
+   * Get the name of the project directory (basename).
+   *
+   * @todo: It would be nice, if projects contained an info file which could
+   *        provide their canonical name.
+   *
+   * @param string $directory
+   * @return string
+   */
+  public static function getProjectName($directory) {
+    return basename($directory);
+  }
+
+  /**
+   * Return the project name from a Drupal info file.
+   *
+   * @param string $directory
+   *   Directory to search for the info file.
+   * @return string
+   */
+  public static function getProjectTitle($directory) {
+    $info_file = self::findInfoFile($directory);
+    $info = drupal_parse_info_file($info_file);
+    if (!$info) {
+      throw new UpdaterException(t('Unable to parse info file.'));
+    }
+    return $info['name'];
+  }
+
+  /**
+   * Store the default parameters for the Updater.
+   *
+   * @param array $overrides
+   *   An array of overrides for the default parameters.
+   * @return array
+   *   An array of configuration parameters for an update or install operation.
+   */
+  protected function getInstallArgs($overrides = array()) {
+    $args = array(
+      'make_backup' => FALSE,
+      'install_dir' => $this->getInstallDirectory(),
+      'backup_dir'  => $this->getBackupDir(),
+    );
+    return array_merge($args, $overrides);
+  }
+
+  /**
+   * Updates a Drupal project, returns a list of next actions.
+   *
+   * @param FileTransfer $filetransfer
+   *   Object which is a child of FileTransfer. Used for moving files
+   *   to the server.
+   * @param array $overrides
+   *   An array of settings to override defaults
+   *   @see self::getInstallArgs
+   * @return array
+   *   An array of links which the user may need to complete the update
+   */
+  public function update(&$filetransfer, $overrides = array()) {
+    try {
+      // Establish arguments with possible overrides.
+      $args = $this->getInstallArgs($overrides);
+
+      // Take a Backup.
+      if ($args['make_backup']) {
+        $this->makeBackup($args['install_dir'], $args['backup_dir']);
+      }
+      
+      if (!$this->name) {
+        // This is bad, don't want to delete the install directory.
+        throw new UpdaterException(t('Fatal error in update, cowardly refusing to wipe out the install directory.'));
+      }
+
+      // Make sure the installation parent directory exists and is writable.
+      $this->prepareInstallDirectory($filetransfer, $args['install_dir']);
+
+      // Note: If the project is installed in sites/all, it will not be
+      // deleted. It will be installed in sites/default as that will override
+      // the sites/all reference and not break other sites which are using it.
+      if (is_dir($args['install_dir'] . '/' . $this->name)) {
+        // Remove the existing installed file.
+        $filetransfer->removeDirectory($args['install_dir'] . '/' . $this->name);
+      }
+
+      // Copy the directory in place.
+      $filetransfer->copyDirectory($this->source, $args['install_dir']);
+
+      // Make sure what we just installed is readable by the web server.
+      $this->makeWorldReadable($filetransfer, $args['install_dir'] . '/' . $this->name);
+
+      // Run the updates.
+      // @TODO: decide if we want to implement this.
+      $this->postUpdate();
+
+      // For now, just return a list of links of things to do.
+      return $this->postUpdateTasks();
+    }
+    catch (FileTransferException $e) {
+      throw new UpdaterFileTransferException(t('File Transfer failed, reason: !reason', array('!reason' => strtr($e->getMessage(), $e->arguments))));
+    }
+  }
+
+  /**
+   * Installs a Drupal project, returns a list of next actions.
+   *
+   * @param FileTransfer $filetransfer
+   *   Object which is a child of FileTransfer.
+   * @param array $overrides
+   *   An array of settings to override defaults.
+   *   @see self::getInstallArgs
+   * @return array
+   *   An array of links which the user may need to complete the install.
+   */
+  public function install(&$filetransfer, $overrides = array()) {
+    try {
+      // Establish arguments with possible overrides.
+      $args = $this->getInstallArgs($overrides);
+
+      // Make sure the installation parent directory exists and is writable.
+      $this->prepareInstallDirectory($filetransfer, $args['install_dir']);
+
+      // Copy the directory in place.
+      $filetransfer->copyDirectory($this->source, $args['install_dir']);
+
+      // Make sure what we just installed is readable by the web server.
+      $this->makeWorldReadable($filetransfer, $args['install_dir'] . '/' . $this->name);
+
+      // Potentially enable something?
+      // @TODO: decide if we want to implement this.
+      $this->postInstall();
+      // For now, just return a list of links of things to do.
+      return $this->postInstallTasks();
+    }
+    catch (FileTransferException $e) {
+      throw new UpdaterFileTransferException(t('File Transfer failed, reason: !reason', array('!reason' => strtr($e->getMessage(), $e->arguments))));
+    }
+  }
+
+  /**
+   * Make sure the installation parent directory exists and is writable.
+   *
+   * @param FileTransfer $filetransfer
+   *   Object which is a child of FileTransfer.
+   * @param string $directory
+   *   The installation directory to prepare.
+   */
+  public function prepareInstallDirectory(&$filetransfer, $directory) {
+    // Make the parent dir writable if need be and create the dir.
+    if (!is_dir($directory)) {
+      $parent_dir = dirname($directory);
+      if (!is_writable($parent_dir)) {
+        @chmod($parent_dir, 0755);
+        // It is expected that this will fail if the directory is owned by the
+        // FTP user. If the FTP user == web server, it will succeed.
+        try {
+          $filetransfer->createDirectory($directory);
+          $this->makeWorldReadable($filetransfer, $directory);
+        }
+        catch (FileTransferException $e) {
+          // Probably still not writable. Try to chmod and do it again.
+          // @todo: Make a new exception class so we can catch it differently.
+          try {
+            $old_perms = substr(sprintf('%o', fileperms($parent_dir)), -4);
+            $filetransfer->chmod($parent_dir, 0755);
+            $filetransfer->createDirectory($directory);
+            $this->makeWorldReadable($filetransfer, $directory);
+            // Put the permissions back.
+            $filetransfer->chmod($parent_dir, intval($old_perms, 8));
+          }
+          catch (FileTransferException $e) {
+            $message = t($e->getMessage(), $e->arguments);
+            $throw_message = t('Unable to create %directory due to the following: %reason', array('%directory' => $install_location, '%reason' => $message));
+            throw new UpdaterException($throw_message);
+          }
+        }
+        // Put the parent directory back.
+        @chmod($parent_dir, 0555);
+      }
+    }
+  }
+
+  /**
+   * Ensure that a given directory is world readable.
+   *
+   * @param FileTransfer $filetransfer
+   *   Object which is a child of FileTransfer.
+   * @param string $path
+   *   The file path to make world readable.
+   * @param bool $recursive
+   *   If the chmod should be applied recursively.
+   */
+  public function makeWorldReadable(&$filetransfer, $path, $recursive = TRUE) {
+    if (!is_executable($path)) {
+      // Set it to read + execute.
+      $new_perms = substr(sprintf('%o', fileperms($path)), -4, -1) . "5";
+      $filetransfer->chmod($path, intval($new_perms, 8), $recursive);
+    }
+  }
+
+  /**
+   * Perform a backup.
+   *
+   * @todo Not implemented.
+   */
+  public function makeBackup(&$filetransfer, $from, $to) {
+  }
+
+  /**
+   * Return the full path to a directory where backups should be written.
+   */
+  public function getBackupDir() {
+    return file_directory_path('temporary');
+  }
+
+  /**
+   * Perform actions after new code is updated.
+   */
+  public function postUpdate() {
+  }
+
+  /**
+   * Perform actions after installation.
+   */
+  public function postInstall() {
+  }
+
+  /**
+   * Return an array of links to pages that should be visited post operation.
+   *
+   * @return array
+   *   Links which provide actions to take after the install is finished.
+   */
+  public function postInstallTasks() {
+    return array();
+  }
+
+  /**
+   * Return an array of links to pages that should be visited post operation.
+   *
+   * @return array
+   *   Links which provide actions to take after the update is finished.
+   */
+  public function postUpdateTasks() {
+    return array();
+  }
+}
+
+/**
+ * Exception class for the Updater class hierarchy.
+ *
+ * This is identical to the base Exception class, we just give it a more
+ * specific name so that call sites that want to tell the difference can
+ * specifically catch these exceptions and treat them differently.
+ */
+class UpdaterException extends Exception {
+}
+
+/**
+ * Child class of UpdaterException that indicates a FileTransfer exception.
+ *
+ * We have to catch FileTransfer exceptions and wrap those in t(), since
+ * FileTransfer is so low-level that it doesn't use any Drupal APIs and none
+ * of the strings are translated.
+ */
+class UpdaterFileTransferException extends UpdaterException {
+}