Index: includes/plugins.inc
===================================================================
RCS file: includes/plugins.inc
diff -N includes/plugins.inc
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ includes/plugins.inc	10 Mar 2009 22:24:29 -0000
@@ -0,0 +1,196 @@
+<?php
+// $Id$
+
+/**
+ * @file
+ * Provides an API for automatically installing modules and themes.
+ */
+
+/**
+ * URL to check for updates, if a given project doesn't define its own.
+ */
+define('PLUGIN_DEFAULT_URL', 'http://updates.drupal.org/release-history');
+
+/**
+ * Get a list of all available backends that can upload files onto the system.
+ *
+ * @return
+ *   Array containing the names of all available backends.
+ */
+function plugin_list_backends() {
+  $backends = module_invoke_all('backend_plugin');
+  sort($backends);
+  return $backends;
+}
+
+/**
+ * Attempts to get a file using drupal_http_request and to store it locally.
+ *
+ * @param $path
+ *   The URL of the file to grab.
+ * @return
+ *   On success the address the files was saved to, FALSE on failure.
+ */
+function plugin_get_file($path) {
+  // Get each of the specified files.
+  $parsed_url = parse_url($path);
+  $local = file_directory_temp() . "/plugin_cache/" . basename($parsed_url['path']);
+
+  // Check the cache and download the file if needed.
+  if (!file_exists($local)) {
+    // $result->data is the actual contents of the downloaded file. This saves
+    // it into a local file, whose path is stored in $local. $local is stored
+    // relative to the drupal installation.
+    $result = drupal_http_request($path);
+    if ($result->code != 200 || !file_save_data($result->data, $local)) {
+      drupal_set_message(t('@remote could not be saved.', array('@remote' => $path)), 'error');
+      return FALSE;
+    }
+  }
+  return $local;
+}
+
+/**
+ * Untars a file.
+ *
+ * @param $file
+ *   The file to untar.
+ * @return
+ *   An array containing the locations of the extracted files, or FALSE on
+ *   failure.
+ */
+function plugin_manager_untar($file) {
+  $dir = file_directory_temp() .'/plugin_manager_extraction/';
+  $file_safe = escapeshellarg($file);
+  $dir_safe  = escapeshellarg($dir);
+  $file_list = array();
+
+  // Try to use tar to extract the files.
+  if (function_exists('popen')) {
+    $handle = popen("tar -zvxf $file_safe -C $dir_safe", "r");
+    while ($line = fgets($handle)) {
+      $file_list[] = trim($line);
+    }
+    pclose($handle);
+  }
+
+  // If tar returned something, then it is present, so return it.
+  if (!empty($file_list)) {
+    return $file_list;
+  }
+
+  return FALSE;
+}
+
+/**
+ * Downloads the list of available themes/modules.
+ *
+ * @return
+ *  An form array to be displayed.
+ */
+function plugin_list_reload() {
+  // Download a new copy of the project-list.
+  $file = drupal_http_request(PLUGIN_DEFAULT_URL . '/project-list/all');
+  if (isset($file->error)) {
+    drupal_set_message(t($file->error), 'error');
+    return array();
+  }
+
+  // Parse it.
+  $xml = simplexml_load_string($file->data);
+  if ($xml == FALSE) {
+    return array();
+  }
+
+  // @todo Clear cache here.
+
+  // Look at each project node.
+  $drupal_version = constant("DRUPAL_CORE_COMPATIBILITY");
+  foreach ($xml->project AS $project) {
+    // If there isn't a release for this version of Drupal then skip it.
+    if (!isset($project->api_versions)) {
+      continue;
+    }
+    $versions = (array) $project->api_versions;
+    if (!is_array($versions['api_version'])) {
+      $versions['api_version'] = array($versions['api_version']);
+    }
+    if (!in_array($drupal_version, $versions['api_version'])) {
+      continue;
+    }
+
+    // @todo Cache data here.
+  }
+  drupal_set_message(t("The repository was updated successfully."), "status");
+  variable_set("plugin_manager_last_reload", date('U'));
+  return array();
+}
+
+/**
+ * Get the information about each plugin.
+ *
+ * @param $projects
+ *  The project or projects on which information is desired.
+ * @return
+ *  An array containing info on the supplied projects.
+ */
+function plugin_get_release_history($projects) {
+  $version = DRUPAL_CORE_COMPATIBILITY;
+  $results = array();
+
+  // If projects isn't an array, turn it into one.
+  if (!is_array($projects)) {
+    $projects = array($projects);
+  }
+
+  // Look up the data for every project requested.
+  foreach ($projects AS $project) {
+    $file = drupal_http_request(PLUGIN_DEFAULT_URL . "/$project/$version");
+    $xml = simplexml_load_string($file->data);
+
+    // If it failed, then quit.
+    if ($xml == FALSE) {
+      drupal_set_message(t('Downloading the release history failed for @project.', array('@project' => $project)), "error");
+      return FALSE;
+    }
+
+    // Get the title, release_link and download_link.
+    $results[$project]['title'] = (string)$xml->title;
+
+    // Get the information about every release
+    foreach ($xml->releases->release AS $release) {
+      $release_version = (string)$release->version;
+      $results[$project]['release'][] = array(
+        'release_link' => (string)$release->release_link,
+        'download_link' => (string)$release->download_link,
+        'date' => (string)$release->date,
+        'version' => $release_version,
+      );
+      $results[$project]['version'][] = $release_version;
+    }
+  }
+
+  // Order them and then return the results.
+  ksort($results);
+  return $results;
+}
+
+/**
+ * See if everything that is needed to use the plugin manager is available.
+ *
+ * @return
+ *  TRUE if all of the required dependencies are available, FALSE otherwise.
+ */
+function plugin_manager_runnable() {
+  // See if we have a way to untar the files.
+  $handle = popen("tar --version", "r");
+  if (!fgets($handle)) {
+    pclose($handle);
+    return FALSE;
+  }
+  pclose($handle);
+
+  // See if we have any available backends.
+  $backends = plugin_manager_backends();
+  return !empty($backends);
+}
\ No newline at end of file
Index: modules/system/system.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.module,v
retrieving revision 1.671
diff -u -p -r1.671 system.module
--- modules/system/system.module	9 Mar 2009 11:44:54 -0000	1.671
+++ modules/system/system.module	10 Mar 2009 22:26:09 -0000
@@ -228,6 +228,27 @@ function system_rdf_namespaces() {
 }
 
 /**
+ * Implementation of hook_backend_plugin().
+ */
+function system_backend_plugin() {
+  $backends = array();
+
+  // FTP backend is only available if the proper PHP extension is installed or
+  // allow_url_fopen is on.
+  if (function_exists('ftp_connect') || ini_get('allow_url_fopen')) {
+    $backends[] = 'ftp';
+  }
+
+  // SSH2 lib backend is only available if the proper PHP extension is
+  // installed.
+  if (function_exists('ssh2_connect')) {
+    $backends[] = 'ssh';
+  }
+
+  return $backends;
+}
+
+/**
  * Implementation of hook_elements().
  */
 function system_elements() {
Index: modules/update/update.fetch.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/update/update.fetch.inc,v
retrieving revision 1.15
diff -u -p -r1.15 update.fetch.inc
--- modules/update/update.fetch.inc	14 Jan 2009 21:13:42 -0000	1.15
+++ modules/update/update.fetch.inc	10 Mar 2009 21:50:03 -0000
@@ -77,7 +77,7 @@ function _update_refresh() {
  * @see update_get_projects()
  */
 function _update_build_fetch_url($project, $site_key = '') {
-  $default_url = variable_get('update_fetch_url', UPDATE_DEFAULT_URL);
+  $default_url = variable_get('update_fetch_url', PLUGIN_DEFAULT_URL);
   if (!isset($project['info']['project status url'])) {
     $project['info']['project status url'] = $default_url;
   }
Index: modules/update/update.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/update/update.module,v
retrieving revision 1.30
diff -u -p -r1.30 update.module
--- modules/update/update.module	22 Jan 2009 03:11:54 -0000	1.30
+++ modules/update/update.module	10 Mar 2009 21:48:52 -0000
@@ -9,11 +9,6 @@
  * (admin/reports/status), the module and theme pages, and optionally via email.
  */
 
-/**
- * URL to check for updates, if a given project doesn't define its own.
- */
-define('UPDATE_DEFAULT_URL', 'http://updates.drupal.org/release-history');
-
 // These are internally used constants for this code, do not modify.
 
 /**