WordPress 4.3
[autoinstalls/wordpress.git] / wp-admin / includes / class-wp-upgrader.php
index 2bef3eaa6e6ee98f1c42d01e3f0561e255ba9faa..235df514c1716888f480c0c59f8f5702ab33c007 100644 (file)
@@ -4,7 +4,7 @@
  *
  * This set of classes are designed to be used to upgrade/install a local set of files on the filesystem via the Filesystem Abstraction classes.
  *
- * @link http://trac.wordpress.org/ticket/7875 consolidate plugin/theme/core upgrade/install functions
+ * @link https://core.trac.wordpress.org/ticket/7875 consolidate plugin/theme/core upgrade/install functions
  *
  * @package WordPress
  * @subpackage Upgrader
@@ -21,22 +21,100 @@ require ABSPATH . 'wp-admin/includes/class-wp-upgrader-skins.php';
  * @since 2.8.0
  */
 class WP_Upgrader {
+
+       /**
+        * The error/notification strings used to update the user on the progress.
+        *
+        * @since 2.8.0
+        * @var string $strings
+        */
        public $strings = array();
+
+       /**
+        * The upgrader skin being used.
+        *
+        * @since 2.8.0
+        * @var WP_Upgrader_Skin $skin
+        */
        public $skin = null;
+
+       /**
+        * The result of the installation.
+        *
+        * This is set by {@see WP_Upgrader::install_package()}, only when the package is installed
+        * successfully. It will then be an array, unless a {@see WP_Error} is returned by the
+        * {@see 'upgrader_post_install'} filter. In that case, the `WP_Error` will be assigned to
+        * it.
+        *
+        * @since 2.8.0
+        * @var WP_Error|array $result {
+        *      @type string $source             The full path to the source the files were installed from.
+        *      @type string $source_files       List of all the files in the source directory.
+        *      @type string $destination        The full path to the install destination folder.
+        *      @type string $destination_name   The name of the destination folder, or empty if `$destination`
+        *                                       and `$local_destination` are the same.
+        *      @type string $local_destination  The full local path to the destination folder. This is usually
+        *                                       the same as `$destination`.
+        *      @type string $remote_destination The full remote path to the destination folder
+        *                                       (i.e., from `$wp_filesystem`).
+        *      @type bool   $clear_destination  Whether the destination folder was cleared.
+        * }
+        */
        public $result = array();
 
-       public function __construct($skin = null) {
+       /**
+        * The total number of updates being performed.
+        *
+        * Set by the bulk update methods.
+        *
+        * @since 3.0.0
+        * @var int $update_count
+        */
+       public $update_count = 0;
+
+       /**
+        * The current update if multiple updates are being performed.
+        *
+        * Used by the bulk update methods, and incremented for each update.
+        *
+        * @since 3.0.0
+        * @var int
+        */
+       public $update_current = 0;
+
+       /**
+        * Construct the upgrader with a skin.
+        *
+        * @since 2.8.0
+        *
+        * @param WP_Upgrader_Skin $skin The upgrader skin to use. Default is a {@see WP_Upgrader_Skin}
+        *                               instance.
+        */
+       public function __construct( $skin = null ) {
                if ( null == $skin )
                        $this->skin = new WP_Upgrader_Skin();
                else
                        $this->skin = $skin;
        }
 
+       /**
+        * Initialize the upgrader.
+        *
+        * This will set the relationship between the skin being used and this upgrader,
+        * and also add the generic strings to `WP_Upgrader::$strings`.
+        *
+        * @since 2.8.0
+        */
        public function init() {
                $this->skin->set_upgrader($this);
                $this->generic_strings();
        }
 
+       /**
+        * Add the generic strings to WP_Upgrader::$strings.
+        *
+        * @since 2.8.0
+        */
        public function generic_strings() {
                $this->strings['bad_request'] = __('Invalid Data provided.');
                $this->strings['fs_unavailable'] = __('Could not access filesystem.');
@@ -54,22 +132,39 @@ class WP_Upgrader {
                $this->strings['folder_exists'] = __('Destination folder already exists.');
                $this->strings['mkdir_failed'] = __('Could not create directory.');
                $this->strings['incompatible_archive'] = __('The package could not be installed.');
+               $this->strings['files_not_writable'] = __( 'The update cannot be installed because we will be unable to copy some files. This is usually due to inconsistent file permissions.' );
 
                $this->strings['maintenance_start'] = __('Enabling Maintenance mode…');
                $this->strings['maintenance_end'] = __('Disabling Maintenance mode…');
        }
 
-       public function fs_connect( $directories = array() ) {
+       /**
+        * Connect to the filesystem.
+        *
+        * @since 2.8.0
+        *
+        * @global WP_Filesystem_Base $wp_filesystem Subclass
+        *
+        * @param array $directories                  Optional. A list of directories. If any of these do
+        *                                            not exist, a {@see WP_Error} object will be returned.
+        *                                            Default empty array.
+        * @param bool  $allow_relaxed_file_ownership Whether to allow relaxed file ownership.
+        *                                            Default false.
+        * @return bool|WP_Error True if able to connect, false or a {@see WP_Error} otherwise.
+        */
+       public function fs_connect( $directories = array(), $allow_relaxed_file_ownership = false ) {
                global $wp_filesystem;
 
-               if ( false === ($credentials = $this->skin->request_filesystem_credentials()) )
+               if ( false === ( $credentials = $this->skin->request_filesystem_credentials( false, $directories[0], $allow_relaxed_file_ownership ) ) ) {
                        return false;
+               }
 
-               if ( ! WP_Filesystem($credentials) ) {
+               if ( ! WP_Filesystem( $credentials, $directories[0], $allow_relaxed_file_ownership ) ) {
                        $error = true;
                        if ( is_object($wp_filesystem) && $wp_filesystem->errors->get_error_code() )
                                $error = $wp_filesystem->errors;
-                       $this->skin->request_filesystem_credentials($error); //Failed to connect, Error and request again
+                       // Failed to connect, Error and request again
+                       $this->skin->request_filesystem_credentials( $error, $directories[0], $allow_relaxed_file_ownership );
                        return false;
                }
 
@@ -106,7 +201,16 @@ class WP_Upgrader {
                return true;
        } //end fs_connect();
 
-       public function download_package($package) {
+       /**
+        * Download a package.
+        *
+        * @since 2.8.0
+        *
+        * @param string $package The URI of the package. If this is the full path to an
+        *                        existing local file, it will be returned untouched.
+        * @return string|WP_Error The full path to the downloaded package file, or a {@see WP_Error} object.
+        */
+       public function download_package( $package ) {
 
                /**
                 * Filter whether to return the package.
@@ -138,7 +242,19 @@ class WP_Upgrader {
                return $download_file;
        }
 
-       public function unpack_package($package, $delete_package = true) {
+       /**
+        * Unpack a compressed package file.
+        *
+        * @since 2.8.0
+        *
+        * @global WP_Filesystem_Base $wp_filesystem Subclass
+        *
+        * @param string $package        Full path to the package file.
+        * @param bool   $delete_package Optional. Whether to delete the package file after attempting
+        *                               to unpack it. Default true.
+        * @return string|WP_Error The path to the unpacked contents, or a {@see WP_Error} on failure.
+        */
+       public function unpack_package( $package, $delete_package = true ) {
                global $wp_filesystem;
 
                $this->skin->feedback('unpack_package');
@@ -152,8 +268,8 @@ class WP_Upgrader {
                                $wp_filesystem->delete($upgrade_folder . $file['name'], true);
                }
 
-               //We need a working directory
-               $working_dir = $upgrade_folder . basename($package, '.zip');
+               // We need a working directory - Strip off any .tmp or .zip suffixes
+               $working_dir = $upgrade_folder . basename( basename( $package, '.tmp' ), '.zip' );
 
                // Clean up working directory
                if ( $wp_filesystem->is_dir($working_dir) )
@@ -177,6 +293,95 @@ class WP_Upgrader {
                return $working_dir;
        }
 
+       /**
+        * Clears the directory where this item is going to be installed into.
+        *
+        * @since 4.3.0
+        *
+        * @global WP_Filesystem_Base $wp_filesystem Subclass
+        *
+        * @param string $remote_destination The location on the remote filesystem to be cleared
+        * @return bool|WP_Error True upon success, WP_Error on failure.
+        */
+       public function clear_destination( $remote_destination ) {
+               global $wp_filesystem;
+
+               if ( ! $wp_filesystem->exists( $remote_destination ) ) {
+                       return true;
+               }
+
+               // Check all files are writable before attempting to clear the destination.
+               $unwritable_files = array();
+
+               $_files = $wp_filesystem->dirlist( $remote_destination, true, true );
+
+               // Flatten the resulting array, iterate using each as we append to the array during iteration.
+               while ( $f = each( $_files ) ) {
+                       $file = $f['value'];
+                       $name = $f['key'];
+
+                       if ( ! isset( $file['files'] ) ) {
+                               continue;
+                       }
+
+                       foreach ( $file['files'] as $filename => $details ) {
+                               $_files[ $name . '/' . $filename ] = $details;
+                       }
+               }
+
+               // Check writability.
+               foreach ( $_files as $filename => $file_details ) {
+                       if ( ! $wp_filesystem->is_writable( $remote_destination . $filename ) ) {
+
+                               // Attempt to alter permissions to allow writes and try again.
+                               $wp_filesystem->chmod( $remote_destination . $filename, ( 'd' == $file_details['type'] ? FS_CHMOD_DIR : FS_CHMOD_FILE ) );
+                               if ( ! $wp_filesystem->is_writable( $remote_destination . $filename ) ) {
+                                       $unwritable_files[] = $filename;
+                               }
+                       }
+               }
+
+               if ( ! empty( $unwritable_files ) ) {
+                       return new WP_Error( 'files_not_writable', $this->strings['files_not_writable'], implode( ', ', $unwritable_files ) );
+               }
+
+               if ( ! $wp_filesystem->delete( $remote_destination, true ) ) {
+                       return new WP_Error( 'remove_old_failed', $this->strings['remove_old_failed'] );
+               }
+
+               return true;
+       }
+
+       /**
+        * Install a package.
+        *
+        * Copies the contents of a package form a source directory, and installs them in
+        * a destination directory. Optionally removes the source. It can also optionally
+        * clear out the destination folder if it already exists.
+        *
+        * @since 2.8.0
+        *
+        * @global WP_Filesystem_Base $wp_filesystem Subclass
+        * @global array              $wp_theme_directories
+        *
+        * @param array|string $args {
+        *     Optional. Array or string of arguments for installing a package. Default empty array.
+        *
+        *     @type string $source                      Required path to the package source. Default empty.
+        *     @type string $destination                 Required path to a folder to install the package in.
+        *                                               Default empty.
+        *     @type bool   $clear_destination           Whether to delete any files already in the destination
+        *                                               folder. Default false.
+        *     @type bool   $clear_working               Whether to delete the files form the working directory
+        *                                               after copying to the destination. Default false.
+        *     @type bool   $abort_if_destination_exists Whether to abort the installation if
+        *                                               the destination folder already exists. Default true.
+        *     @type array  $hook_extra                  Extra arguments to pass to the filter hooks called by
+        *                                               {@see WP_Upgrader::install_package()}. Default empty array.
+        * }
+        *
+        * @return array|WP_Error The result (also stored in `WP_Upgrader:$result`), or a {@see WP_Error} on failure.
+        */
        public function install_package( $args = array() ) {
                global $wp_filesystem, $wp_theme_directories;
 
@@ -272,29 +477,25 @@ class WP_Upgrader {
                }
 
                if ( $clear_destination ) {
-                       //We're going to clear the destination if there's something there
+                       // We're going to clear the destination if there's something there
                        $this->skin->feedback('remove_old');
-                       $removed = true;
-                       if ( $wp_filesystem->exists( $remote_destination ) ) {
-                               $removed = $wp_filesystem->delete( $remote_destination, true );
-                       }
+
+                       $removed = $this->clear_destination( $remote_destination );
 
                        /**
                         * Filter whether the upgrader cleared the destination.
                         *
                         * @since 2.8.0
                         *
-                        * @param bool   $removed            Whether the destination was cleared.
+                        * @param mixed  $removed            Whether the destination was cleared. true on success, WP_Error on failure
                         * @param string $local_destination  The local package destination.
                         * @param string $remote_destination The remote package destination.
                         * @param array  $hook_extra         Extra arguments passed to hooked filters.
                         */
                        $removed = apply_filters( 'upgrader_clear_destination', $removed, $local_destination, $remote_destination, $args['hook_extra'] );
 
-                       if ( is_wp_error($removed) ) {
+                       if ( is_wp_error( $removed ) ) {
                                return $removed;
-                       } else if ( ! $removed ) {
-                               return new WP_Error('remove_old_failed', $this->strings['remove_old_failed']);
                        }
                } elseif ( $args['abort_if_destination_exists'] && $wp_filesystem->exists($remote_destination) ) {
                        //If we're not clearing the destination folder and something exists there already, Bail.
@@ -331,7 +532,7 @@ class WP_Upgrader {
                        $destination_name = '';
                }
 
-               $this->result = compact('local_source', 'source', 'source_name', 'source_files', 'destination', 'destination_name', 'local_destination', 'remote_destination', 'clear_destination', 'delete_source_dir');
+               $this->result = compact( 'source', 'source_files', 'destination', 'destination_name', 'local_destination', 'remote_destination', 'clear_destination' );
 
                /**
                 * Filter the install response after the installation has finished.
@@ -353,6 +554,40 @@ class WP_Upgrader {
                return $this->result;
        }
 
+       /**
+        * Run an upgrade/install.
+        *
+        * Attempts to download the package (if it is not a local file), unpack it, and
+        * install it in the destination folder.
+        *
+        * @since 2.8.0
+        *
+        * @param array $options {
+        *     Array or string of arguments for upgrading/installing a package.
+        *
+        *     @type string $package                     The full path or URI of the package to install.
+        *                                               Default empty.
+        *     @type string $destination                 The full path to the destination folder.
+        *                                               Default empty.
+        *     @type bool   $clear_destination           Whether to delete any files already in the
+        *                                               destination folder. Default false.
+        *     @type bool   $clear_working               Whether to delete the files form the working
+        *                                               directory after copying to the destination.
+        *                                               Default false.
+        *     @type bool   $abort_if_destination_exists Whether to abort the installation if the destination
+        *                                               folder already exists. When true, `$clear_destination`
+        *                                               should be false. Default true.
+        *     @type bool   $is_multi                    Whether this run is one of multiple upgrade/install
+        *                                               actions being performed in bulk. When true, the skin
+        *                                               {@see WP_Upgrader::header()} and {@see WP_Upgrader::footer()}
+        *                                               aren't called. Default false.
+        *     @type array  $hook_extra                  Extra arguments to pass to the filter hooks called by
+        *                                               {@see WP_Upgrader::run()}.
+        * }
+        *
+        * @return array|false|WP_error The result from self::install_package() on success, otherwise a WP_Error,
+        *                              or false if unable to connect to the filesystem.
+        */
        public function run( $options ) {
 
                $defaults = array(
@@ -367,6 +602,25 @@ class WP_Upgrader {
 
                $options = wp_parse_args( $options, $defaults );
 
+               /**
+                * Filter the package options before running an update.
+                *
+                * @since 4.3.0
+                *
+                * @param array $options {
+                *     Options used by the upgrader.
+                *
+                *     @type string $package                     Package for update.
+                *     @type string $destination                 Update location.
+                *     @type bool   $clear_destination           Clear the destination resource.
+                *     @type bool   $clear_working               Clear the working resource.
+                *     @type bool   $abort_if_destination_exists Abort if the Destination directory exists.
+                *     @type bool   $is_multi                    Whether the upgrader is running multiple times.
+                *     @type array  $hook_extra                  Extra hook arguments.
+                * }
+                */
+               $options = apply_filters( 'upgrader_package_options', $options );
+
                if ( ! $options['is_multi'] ) { // call $this->header separately if running multiple times
                        $this->skin->header();
                }
@@ -447,7 +701,18 @@ class WP_Upgrader {
                return $result;
        }
 
-       public function maintenance_mode($enable = false) {
+       /**
+        * Toggle maintenance mode for the site.
+        *
+        * Creates/deletes the maintenance file to enable/disable maintenance mode.
+        *
+        * @since 2.8.0
+        *
+        * @global WP_Filesystem_Base $wp_filesystem Subclass
+        *
+        * @param bool $enable True to enable maintenance mode, false to disable.
+        */
+       public function maintenance_mode( $enable = false ) {
                global $wp_filesystem;
                $file = $wp_filesystem->abspath() . '.maintenance';
                if ( $enable ) {
@@ -456,7 +721,7 @@ class WP_Upgrader {
                        $maintenance_string = '<?php $upgrading = ' . time() . '; ?>';
                        $wp_filesystem->delete($file);
                        $wp_filesystem->put_contents($file, $maintenance_string, FS_CHMOD_FILE);
-               } else if ( !$enable && $wp_filesystem->exists($file) ) {
+               } elseif ( ! $enable && $wp_filesystem->exists( $file ) ) {
                        $this->skin->feedback('maintenance_end');
                        $wp_filesystem->delete($file);
                }
@@ -473,9 +738,28 @@ class WP_Upgrader {
  */
 class Plugin_Upgrader extends WP_Upgrader {
 
+       /**
+        * Plugin upgrade result.
+        *
+        * @since 2.8.0
+        * @var array|WP_Error $result
+        * @see WP_Upgrader::$result
+        */
        public $result;
+
+       /**
+        * Whether a bulk upgrade/install is being performed.
+        *
+        * @since 2.9.0
+        * @var bool $bulk
+        */
        public $bulk = false;
 
+       /**
+        * Initialize the upgrade strings.
+        *
+        * @since 2.8.0
+        */
        public function upgrade_strings() {
                $this->strings['up_to_date'] = __('The plugin is at the latest version.');
                $this->strings['no_package'] = __('Update package not available.');
@@ -485,8 +769,14 @@ class Plugin_Upgrader extends WP_Upgrader {
                $this->strings['remove_old_failed'] = __('Could not remove the old plugin.');
                $this->strings['process_failed'] = __('Plugin update failed.');
                $this->strings['process_success'] = __('Plugin updated successfully.');
+               $this->strings['process_bulk_success'] = __('Plugins updated successfully.');
        }
 
+       /**
+        * Initialize the install strings.
+        *
+        * @since 2.8.0
+        */
        public function install_strings() {
                $this->strings['no_package'] = __('Install package not available.');
                $this->strings['downloading_package'] = __('Downloading install package from <span class="code">%s</span>&#8230;');
@@ -497,6 +787,22 @@ class Plugin_Upgrader extends WP_Upgrader {
                $this->strings['process_success'] = __('Plugin installed successfully.');
        }
 
+       /**
+        * Install a plugin package.
+        *
+        * @since 2.8.0
+        * @since 3.7.0 The `$args` parameter was added, making clearing the plugin update cache optional.
+        *
+        * @param string $package The full local path or URI of the package.
+        * @param array  $args {
+        *     Optional. Other arguments for installing a plugin package. Default empty array.
+        *
+        *     @type bool $clear_update_cache Whether to clear the plugin updates cache if successful.
+        *                                    Default true.
+        * }
+        *
+        * @return bool|WP_Error True if the install was successful, false or a WP_Error otherwise.
+        */
        public function install( $package, $args = array() ) {
 
                $defaults = array(
@@ -531,6 +837,21 @@ class Plugin_Upgrader extends WP_Upgrader {
                return true;
        }
 
+       /**
+        * Upgrade a plugin.
+        *
+        * @since 2.8.0
+        * @since 3.7.0 The `$args` parameter was added, making clearing the plugin update cache optional.
+        *
+        * @param string $plugin The basename path to the main plugin file.
+        * @param array  $args {
+        *     Optional. Other arguments for upgrading a plugin package. Defualt empty array.
+        *
+        *     @type bool $clear_update_cache Whether to clear the plugin updates cache if successful.
+        *                                    Default true.
+        * }
+        * @return bool|WP_Error True if the upgrade was successful, false or a {@see WP_Error} object otherwise.
+        */
        public function upgrade( $plugin, $args = array() ) {
 
                $defaults = array(
@@ -582,6 +903,22 @@ class Plugin_Upgrader extends WP_Upgrader {
                return true;
        }
 
+       /**
+        * Bulk upgrade several plugins at once.
+        *
+        * @since 2.8.0
+        * @since 3.7.0 The `$args` parameter was added, making clearing the plugin update cache optional.
+        *
+        * @param array $plugins Array of the basename paths of the plugins' main files.
+        * @param array $args {
+        *     Optional. Other arguments for upgrading several plugins at once. Default empty array.
+        *
+        *     @type bool $clear_update_cache Whether to clear the plugin updates cache if successful.
+        *                                    Default true.
+        * }
+        *
+        * @return array|false An array of results indexed by plugin file, or false if unable to connect to the filesystem.
+        */
        public function bulk_upgrade( $plugins, $args = array() ) {
 
                $defaults = array(
@@ -696,6 +1033,19 @@ class Plugin_Upgrader extends WP_Upgrader {
                return $results;
        }
 
+       /**
+        * Check a source package to be sure it contains a plugin.
+        *
+        * This function is added to the {@see 'upgrader_source_selection'} filter by
+        * {@see Plugin_Upgrader::install()}.
+        *
+        * @since 3.3.0
+        *
+        * @global WP_Filesystem_Base $wp_filesystem Subclass
+        *
+        * @param string $source The path to the downloaded package source.
+        * @return string|WP_Error The source as passed, or a {@see WP_Error} object if no plugins were found.
+        */
        public function check_package($source) {
                global $wp_filesystem;
 
@@ -703,16 +1053,19 @@ class Plugin_Upgrader extends WP_Upgrader {
                        return $source;
 
                $working_directory = str_replace( $wp_filesystem->wp_content_dir(), trailingslashit(WP_CONTENT_DIR), $source);
-               if ( ! is_dir($working_directory) ) // Sanity check, if the above fails, lets not prevent installation.
+               if ( ! is_dir($working_directory) ) // Sanity check, if the above fails, let's not prevent installation.
                        return $source;
 
                // Check the folder contains at least 1 valid plugin.
                $plugins_found = false;
-               foreach ( glob( $working_directory . '*.php' ) as $file ) {
-                       $info = get_plugin_data($file, false, false);
-                       if ( !empty( $info['Name'] ) ) {
-                               $plugins_found = true;
-                               break;
+               $files = glob( $working_directory . '*.php' );
+               if ( $files ) {
+                       foreach ( $files as $file ) {
+                               $info = get_plugin_data( $file, false, false );
+                               if ( ! empty( $info['Name'] ) ) {
+                                       $plugins_found = true;
+                                       break;
+                               }
                        }
                }
 
@@ -722,7 +1075,15 @@ class Plugin_Upgrader extends WP_Upgrader {
                return $source;
        }
 
-       // Return plugin info.
+       /**
+        * Retrieve the path to the file that contains the plugin info.
+        *
+        * This isn't used internally in the class, but is called by the skins.
+        *
+        * @since 2.8.0
+        *
+        * @return string|false The full path to the main plugin file, or false.
+        */
        public function plugin_info() {
                if ( ! is_array($this->result) )
                        return false;
@@ -738,7 +1099,18 @@ class Plugin_Upgrader extends WP_Upgrader {
                return $this->result['destination_name'] . '/' . $pluginfiles[0];
        }
 
-       //Hooked to pre_install
+       /**
+        * Deactivates a plugin before it is upgraded.
+        *
+        * Hooked to the {@see 'upgrader_pre_install'} filter by {@see Plugin_Upgrader::upgrade()}.
+        *
+        * @since 2.8.0
+        * @since 4.1.0 Added a return value.
+        *
+        * @param bool|WP_Error  $return Upgrade offer return.
+        * @param array          $plugin Plugin package arguments.
+        * @return bool|WP_Error The passed in $return param or {@see WP_Error}.
+        */
        public function deactivate_plugin_before_upgrade($return, $plugin) {
 
                if ( is_wp_error($return) ) //Bypass.
@@ -756,9 +1128,26 @@ class Plugin_Upgrader extends WP_Upgrader {
                        //Deactivate the plugin silently, Prevent deactivation hooks from running.
                        deactivate_plugins($plugin, true);
                }
+
+               return $return;
        }
 
-       //Hooked to upgrade_clear_destination
+       /**
+        * Delete the old plugin during an upgrade.
+        *
+        * Hooked to the {@see 'upgrader_clear_destination'} filter by
+        * {@see Plugin_Upgrader::upgrade()} and {@see Plugin_Upgrader::bulk_upgrade()}.
+        *
+        * @since 2.8.0
+        *
+        * @global WP_Filesystem_Base $wp_filesystem Subclass
+     *
+        * @param bool|WP_Error $removed
+        * @param string        $local_destination
+        * @param string        $remote_destination
+        * @param array         $plugin
+        * @return WP_Error|bool
+        */
        public function delete_old_plugin($removed, $local_destination, $remote_destination, $plugin) {
                global $wp_filesystem;
 
@@ -797,9 +1186,28 @@ class Plugin_Upgrader extends WP_Upgrader {
  */
 class Theme_Upgrader extends WP_Upgrader {
 
+       /**
+        * Result of the theme upgrade offer.
+        *
+        * @since 2.8.0
+        * @var array|WP_Erorr $result
+        * @see WP_Upgrader::$result
+        */
        public $result;
+
+       /**
+        * Whether multiple plugins are being upgraded/installed in bulk.
+        *
+        * @since 2.9.0
+        * @var bool $bulk
+        */
        public $bulk = false;
 
+       /**
+        * Initialize the upgrade strings.
+        *
+        * @since 2.8.0
+        */
        public function upgrade_strings() {
                $this->strings['up_to_date'] = __('The theme is at the latest version.');
                $this->strings['no_package'] = __('Update package not available.');
@@ -811,6 +1219,11 @@ class Theme_Upgrader extends WP_Upgrader {
                $this->strings['process_success'] = __('Theme updated successfully.');
        }
 
+       /**
+        * Initialize the install strings.
+        *
+        * @since 2.8.0
+        */
        public function install_strings() {
                $this->strings['no_package'] = __('Install package not available.');
                $this->strings['downloading_package'] = __('Downloading install package from <span class="code">%s</span>&#8230;');
@@ -831,7 +1244,19 @@ class Theme_Upgrader extends WP_Upgrader {
                $this->strings['parent_theme_not_found'] = __('<strong>The parent theme could not be found.</strong> You will need to install the parent theme, <strong>%s</strong>, before you can use this child theme.');
        }
 
-       public function check_parent_theme_filter($install_result, $hook_extra, $child_result) {
+       /**
+        * Check if a child theme is being installed and we need to install its parent.
+        *
+        * Hooked to the {@see 'upgrader_post_install'} filter by {@see Theme_Upgrader::install()}.
+        *
+        * @since 3.4.0
+        *
+        * @param bool  $install_result
+        * @param array $hook_extra
+        * @param array $child_result
+        * @return type
+        */
+       public function check_parent_theme_filter( $install_result, $hook_extra, $child_result ) {
                // Check to see if we need to install a parent theme
                $theme_info = $this->theme_info();
 
@@ -846,7 +1271,7 @@ class Theme_Upgrader extends WP_Upgrader {
                        return $install_result;
                }
 
-               // We don't have the parent theme, lets install it
+               // We don't have the parent theme, let's install it.
                $api = themes_api('theme_information', array('slug' => $theme_info->get('Template'), 'fields' => array('sections' => false, 'tags' => false) ) ); //Save on a bit of bandwidth.
 
                if ( ! $api || is_wp_error($api) ) {
@@ -890,11 +1315,39 @@ class Theme_Upgrader extends WP_Upgrader {
                return $install_result;
        }
 
-       public function hide_activate_preview_actions($actions) {
+       /**
+        * Don't display the activate and preview actions to the user.
+        *
+        * Hooked to the {@see 'install_theme_complete_actions'} filter by
+        * {@see Theme_Upgrader::check_parent_theme_filter()} when installing
+        * a child theme and installing the parent theme fails.
+        *
+        * @since 3.4.0
+        *
+        * @param array $actions Preview actions.
+        * @return array
+        */
+       public function hide_activate_preview_actions( $actions ) {
                unset($actions['activate'], $actions['preview']);
                return $actions;
        }
 
+       /**
+        * Install a theme package.
+        *
+        * @since 2.8.0
+        * @since 3.7.0 The `$args` parameter was added, making clearing the update cache optional.
+        *
+        * @param string $package The full local path or URI of the package.
+        * @param array  $args {
+        *     Optional. Other arguments for installing a theme package. Default empty array.
+        *
+        *     @type bool $clear_update_cache Whether to clear the updates cache if successful.
+        *                                    Default true.
+        * }
+        *
+        * @return bool|WP_Error True if the install was successful, false or a {@see WP_Error} object otherwise.
+        */
        public function install( $package, $args = array() ) {
 
                $defaults = array(
@@ -931,6 +1384,21 @@ class Theme_Upgrader extends WP_Upgrader {
                return true;
        }
 
+       /**
+        * Upgrade a theme.
+        *
+        * @since 2.8.0
+        * @since 3.7.0 The `$args` parameter was added, making clearing the update cache optional.
+        *
+        * @param string $theme The theme slug.
+        * @param array  $args {
+        *     Optional. Other arguments for upgrading a theme. Default empty array.
+        *
+        *     @type bool $clear_update_cache Whether to clear the update cache if successful.
+        *                                    Default true.
+        * }
+        * @return bool|WP_Error True if the upgrade was successful, false or a {@see WP_Error} object otherwise.
+        */
        public function upgrade( $theme, $args = array() ) {
 
                $defaults = array(
@@ -981,6 +1449,21 @@ class Theme_Upgrader extends WP_Upgrader {
                return true;
        }
 
+       /**
+        * Upgrade several themes at once.
+        *
+        * @since 3.0.0
+        * @since 3.7.0 The `$args` parameter was added, making clearing the update cache optional.
+        *
+        * @param array $themes The theme slugs.
+        * @param array $args {
+        *     Optional. Other arguments for upgrading several themes at once. Default empty array.
+        *
+        *     @type bool $clear_update_cache Whether to clear the update cache if successful.
+        *                                    Default true.
+        * }
+        * @return array[]|false An array of results, or false if unable to connect to the filesystem.
+        */
        public function bulk_upgrade( $themes, $args = array() ) {
 
                $defaults = array(
@@ -1083,7 +1566,21 @@ class Theme_Upgrader extends WP_Upgrader {
                return $results;
        }
 
-       public function check_package($source) {
+       /**
+        * Check that the package source contains a valid theme.
+        *
+        * Hooked to the {@see 'upgrader_source_selection'} filter by {@see Theme_Upgrader::install()}.
+        * It will return an error if the theme doesn't have style.css or index.php
+        * files.
+        *
+        * @since 3.3.0
+        *
+        * @global WP_Filesystem_Base $wp_filesystem Subclass
+        *
+        * @param string $source The full path to the package source.
+        * @return string|WP_Error The source or a WP_Error.
+        */
+       public function check_package( $source ) {
                global $wp_filesystem;
 
                if ( is_wp_error($source) )
@@ -1091,7 +1588,7 @@ class Theme_Upgrader extends WP_Upgrader {
 
                // Check the folder contains a valid theme
                $working_directory = str_replace( $wp_filesystem->wp_content_dir(), trailingslashit(WP_CONTENT_DIR), $source);
-               if ( ! is_dir($working_directory) ) // Sanity check, if the above fails, lets not prevent installation.
+               if ( ! is_dir($working_directory) ) // Sanity check, if the above fails, let's not prevent installation.
                        return $source;
 
                // A proper archive should have a style.css file in the single subdirectory
@@ -1110,8 +1607,19 @@ class Theme_Upgrader extends WP_Upgrader {
                return $source;
        }
 
+       /**
+        * Turn on maintenance mode before attempting to upgrade the current theme.
+        *
+        * Hooked to the {@see 'upgrader_pre_install'} filter by {@see Theme_Upgrader::upgrade()} and
+        * {@see Theme_Upgrader::bulk_upgrade()}.
+        *
+        * @since 2.8.0
+        *
+        * @param bool|WP_Error  $return
+        * @param array          $theme
+        * @return bool|WP_Error
+        */
        public function current_before($return, $theme) {
-
                if ( is_wp_error($return) )
                        return $return;
 
@@ -1126,6 +1634,18 @@ class Theme_Upgrader extends WP_Upgrader {
                return $return;
        }
 
+       /**
+        * Turn off maintenance mode after upgrading the current theme.
+        *
+        * Hooked to the {@see 'upgrader_post_install'} filter by {@see Theme_Upgrader::upgrade()}
+        * and {@see Theme_Upgrader::bulk_upgrade()}.
+        *
+        * @since 2.8.0
+        *
+        * @param bool|WP_Error  $return
+        * @param array          $theme
+        * @return bool|WP_Error
+        */
        public function current_after($return, $theme) {
                if ( is_wp_error($return) )
                        return $return;
@@ -1148,6 +1668,22 @@ class Theme_Upgrader extends WP_Upgrader {
                return $return;
        }
 
+       /**
+        * Delete the old theme during an upgrade.
+        *
+        * Hooked to the {@see 'upgrader_clear_destination'} filter by {@see Theme_Upgrader::upgrade()}
+        * and {@see Theme_Upgrader::bulk_upgrade()}.
+        *
+        * @since 2.8.0
+        *
+        * @global WP_Filesystem_Base $wp_filesystem Subclass
+        *
+        * @param bool   $removed
+        * @param string $local_destination
+        * @param string $remote_destination
+        * @param array  $theme
+        * @return bool
+        */
        public function delete_old_theme( $removed, $local_destination, $remote_destination, $theme ) {
                global $wp_filesystem;
 
@@ -1167,6 +1703,17 @@ class Theme_Upgrader extends WP_Upgrader {
                return true;
        }
 
+       /**
+        * Get the WP_Theme object for a theme.
+        *
+        * @since 2.8.0
+        * @since 3.0.0 The `$theme` argument was added.
+        *
+        * @param string $theme The directory name of the theme. This is optional, and if not supplied,
+        *                      the directory name from the last result will be used.
+        * @return WP_Theme|false The theme's info object, or false `$theme` is not supplied
+        *                        and the last result isn't set.
+        */
        public function theme_info($theme = null) {
 
                if ( empty($theme) ) {
@@ -1180,8 +1727,6 @@ class Theme_Upgrader extends WP_Upgrader {
 
 }
 
-add_action( 'upgrader_process_complete', array( 'Language_Pack_Upgrader', 'async_upgrade' ), 20 );
-
 /**
  * Language pack upgrader, for updating translations of plugins, themes, and core.
  *
@@ -1191,9 +1736,34 @@ add_action( 'upgrader_process_complete', array( 'Language_Pack_Upgrader', 'async
  */
 class Language_Pack_Upgrader extends WP_Upgrader {
 
+       /**
+        * Result of the language pack upgrade.
+        *
+        * @since 3.7.0
+        * @var array|WP_Error $result
+        * @see WP_Upgrader::$result
+        */
        public $result;
+
+       /**
+        * Whether a bulk upgrade/install is being performed.
+        *
+        * @since 3.7.0
+        * @var bool $bulk
+        */
        public $bulk = true;
 
+       /**
+        * Asynchronously upgrade language packs after other upgrades have been made.
+        *
+        * Hooked to the {@see 'upgrader_process_complete'} action by default.
+        *
+        * @since 3.7.0
+        *
+        * @static
+        *
+        * @param false|WP_Upgrader $upgrader
+        */
        public static function async_upgrade( $upgrader = false ) {
                // Avoid recursion.
                if ( $upgrader && $upgrader instanceof Language_Pack_Upgrader ) {
@@ -1243,6 +1813,11 @@ class Language_Pack_Upgrader extends WP_Upgrader {
                $lp_upgrader->bulk_upgrade( $language_updates );
        }
 
+       /**
+        * Initialize the upgrade strings.
+        *
+        * @since 3.7.0
+        */
        public function upgrade_strings() {
                $this->strings['starting_upgrade'] = __( 'Some of your translations need updating. Sit tight for a few more seconds while we update them as well.' );
                $this->strings['up_to_date'] = __( 'The translation is up to date.' ); // We need to silently skip this case
@@ -1253,6 +1828,16 @@ class Language_Pack_Upgrader extends WP_Upgrader {
                $this->strings['process_success'] = __( 'Translation updated successfully.' );
        }
 
+       /**
+        * Upgrade a language pack.
+        *
+        * @since 3.7.0
+        *
+        * @param string|false $update Optional. Whether an update offer is available. Default false.
+        * @param array        $args   Optional. Other optional arguments, see
+        *                             {@see Language_Pack_Upgrader::bulk_upgrade()}. Default empty array.
+        * @return array|bool|WP_Error The result of the upgrade, or a {@see wP_Error} object instead.
+        */
        public function upgrade( $update = false, $args = array() ) {
                if ( $update ) {
                        $update = array( $update );
@@ -1267,6 +1852,23 @@ class Language_Pack_Upgrader extends WP_Upgrader {
                return $results[0];
        }
 
+       /**
+        * Bulk upgrade language packs.
+        *
+        * @since 3.7.0
+        *
+        * @global WP_Filesystem_Base $wp_filesystem Subclass
+        *
+        * @param array $language_updates Optional. Language pack updates. Default empty array.
+        * @param array $args {
+        *     Optional. Other arguments for upgrading multiple language packs. Default empty array
+        *
+        *     @type bool $clear_update_cache Whether to clear the update cache when done.
+        *                                    Default true.
+        * }
+        * @return array|bool|WP_Error Will return an array of results, or true if there are no updates,
+        *                                   false or WP_Error for initial errors.
+        */
        public function bulk_upgrade( $language_updates = array(), $args = array() ) {
                global $wp_filesystem;
 
@@ -1298,7 +1900,7 @@ class Language_Pack_Upgrader extends WP_Upgrader {
                // Remove any existing upgrade filters from the plugin/theme upgraders #WP29425 & #WP29230
                remove_all_filters( 'upgrader_pre_install' );
                remove_all_filters( 'upgrader_clear_destination' );
-               remove_all_filterS( 'upgrader_post_install' );
+               remove_all_filters( 'upgrader_post_install' );
                remove_all_filters( 'upgrader_source_selection' );
 
                add_filter( 'upgrader_source_selection', array( $this, 'check_package' ), 10, 2 );
@@ -1368,14 +1970,25 @@ class Language_Pack_Upgrader extends WP_Upgrader {
                remove_filter( 'upgrader_source_selection', array( $this, 'check_package' ) );
 
                if ( $parsed_args['clear_update_cache'] ) {
-                       wp_clean_themes_cache( true );
-                       wp_clean_plugins_cache( true );
-                       delete_site_transient( 'update_core' );
+                       wp_clean_update_cache();
                }
 
                return $results;
        }
 
+       /**
+        * Check the package source to make sure there are .mo and .po files.
+        *
+        * Hooked to the {@see 'upgrader_source_selection'} filter by
+        * {@see Language_Pack_Upgrader::bulk_upgrade()}.
+        *
+        * @since 3.7.0
+        *
+        * @global WP_Filesystem_Base $wp_filesystem Subclass
+        *
+        * @param string|WP_Error $source
+        * @param string          $remote_source
+        */
        public function check_package( $source, $remote_source ) {
                global $wp_filesystem;
 
@@ -1401,11 +2014,19 @@ class Language_Pack_Upgrader extends WP_Upgrader {
                return $source;
        }
 
+       /**
+        * Get the name of an item being updated.
+        *
+        * @since 3.7.0
+        *
+        * @param object $update The data for an update.
+        * @return string The name of the item being updated.
+        */
        public function get_name_for_update( $update ) {
                switch ( $update->type ) {
                        case 'core':
                                return 'WordPress'; // Not translated
-                               break;
+
                        case 'theme':
                                $theme = wp_get_theme( $update->slug );
                                if ( $theme->exists() )
@@ -1413,7 +2034,7 @@ class Language_Pack_Upgrader extends WP_Upgrader {
                                break;
                        case 'plugin':
                                $plugin_data = get_plugins( '/' . $update->slug );
-                               $plugin_data = array_shift( $plugin_data );
+                               $plugin_data = reset( $plugin_data );
                                if ( $plugin_data )
                                        return $plugin_data['Name'];
                                break;
@@ -1432,6 +2053,11 @@ class Language_Pack_Upgrader extends WP_Upgrader {
  */
 class Core_Upgrader extends WP_Upgrader {
 
+       /**
+        * Initialize the upgrade strings.
+        *
+        * @since 2.8.0
+        */
        public function upgrade_strings() {
                $this->strings['up_to_date'] = __('WordPress is at the latest version.');
                $this->strings['no_package'] = __('Update package not available.');
@@ -1443,6 +2069,27 @@ class Core_Upgrader extends WP_Upgrader {
                $this->strings['rollback_was_required'] = __( 'Due to an error during updating, WordPress has rolled back to your previous version.' );
        }
 
+       /**
+        * Upgrade WordPress core.
+        *
+        * @since 2.8.0
+        *
+        * @global WP_Filesystem_Base $wp_filesystem Subclass
+        * @global callback           $_wp_filesystem_direct_method
+        *
+        * @param object $current Response object for whether WordPress is current.
+        * @param array  $args {
+        *        Optional. Arguments for upgrading WordPress core. Default empty array.
+        *
+        *        @type bool $pre_check_md5    Whether to check the file checksums before
+        *                                     attempting the upgrade. Default true.
+        *        @type bool $attempt_rollback Whether to attempt to rollback the chances if
+        *                                     there is a problem. Default false.
+        *        @type bool $do_rollback      Whether to perform this "upgrade" as a rollback.
+        *                                     Default false.
+        * }
+        * @return null|false|WP_Error False or WP_Error on failure, null on success.
+        */
        public function upgrade( $current, $args = array() ) {
                global $wp_filesystem;
 
@@ -1454,6 +2101,7 @@ class Core_Upgrader extends WP_Upgrader {
                        'pre_check_md5'    => true,
                        'attempt_rollback' => false,
                        'do_rollback'      => false,
+                       'allow_relaxed_file_ownership' => false,
                );
                $parsed_args = wp_parse_args( $args, $defaults );
 
@@ -1464,7 +2112,7 @@ class Core_Upgrader extends WP_Upgrader {
                if ( !isset( $current->response ) || $current->response == 'latest' )
                        return new WP_Error('up_to_date', $this->strings['up_to_date']);
 
-               $res = $this->fs_connect( array(ABSPATH, WP_CONTENT_DIR) );
+               $res = $this->fs_connect( array( ABSPATH, WP_CONTENT_DIR ), $parsed_args['allow_relaxed_file_ownership'] );
                if ( ! $res || is_wp_error( $res ) ) {
                        return $res;
                }
@@ -1561,6 +2209,7 @@ class Core_Upgrader extends WP_Upgrader {
                                'success'          => true,
                                'fs_method'        => $wp_filesystem->method,
                                'fs_method_forced' => defined( 'FS_METHOD' ) || has_filter( 'filesystem_method' ),
+                               'fs_method_direct' => !empty( $GLOBALS['_wp_filesystem_direct_method'] ) ? $GLOBALS['_wp_filesystem_direct_method'] : '',
                                'time_taken'       => time() - $start_time,
                                'reported'         => $wp_version,
                                'attempted'        => $current->version,
@@ -1590,8 +2239,17 @@ class Core_Upgrader extends WP_Upgrader {
                return $result;
        }
 
-       // Determines if this WordPress Core version should update to $offered_ver or not
-       public static function should_update_to_version( $offered_ver /* x.y.z */ ) {
+       /**
+        * Determines if this WordPress Core version should update to an offered version or not.
+        *
+        * @since 3.7.0
+        *
+        * @static
+        *
+        * @param string $offered_ver The offered version, of the format x.y.z.
+        * @return bool True if we should update to the offered version, otherwise false.
+        */
+       public static function should_update_to_version( $offered_ver ) {
                include( ABSPATH . WPINC . '/version.php' ); // $wp_version; // x.y.z
 
                $current_branch = implode( '.', array_slice( preg_split( '/[.-]/', $wp_version  ), 0, 2 ) ); // x.y
@@ -1689,6 +2347,16 @@ class Core_Upgrader extends WP_Upgrader {
                return false;
        }
 
+       /**
+        * Compare the disk file checksums agains the expected checksums.
+        *
+        * @since 3.7.0
+        *
+        * @global string $wp_version
+        * @global string $wp_local_package
+        *
+        * @return bool True if the checksums match, otherwise false.
+        */
        public function check_files() {
                global $wp_version, $wp_local_package;
 
@@ -1717,11 +2385,40 @@ class Core_Upgrader extends WP_Upgrader {
  * @since 2.8.0
  */
 class File_Upload_Upgrader {
+
+       /**
+        * The full path to the file package.
+        *
+        * @since 2.8.0
+        * @var string $package
+        */
        public $package;
+
+       /**
+        * The name of the file.
+        *
+        * @since 2.8.0
+        * @var string $filename
+        */
        public $filename;
+
+       /**
+        * The ID of the attachment post for this file.
+        *
+        * @since 3.3.0
+        * @var int $id
+        */
        public $id = 0;
 
-       public function __construct($form, $urlholder) {
+       /**
+        * Construct the upgrader for a form.
+        *
+        * @since 2.8.0
+        *
+        * @param string $form      The name of the form the file was uploaded from.
+        * @param string $urlholder The name of the `GET` parameter that holds the filename.
+        */
+       public function __construct( $form, $urlholder ) {
 
                if ( empty($_FILES[$form]['name']) && empty($_GET[$urlholder]) )
                        wp_die(__('Please select a file'));
@@ -1772,6 +2469,13 @@ class File_Upload_Upgrader {
                }
        }
 
+       /**
+        * Delete the attachment/uploaded file.
+        *
+        * @since 3.2.2
+        *
+        * @return bool Whether the cleanup was successful.
+        */
        public function cleanup() {
                if ( $this->id )
                        wp_delete_attachment( $this->id );
@@ -1896,6 +2600,8 @@ class WP_Automatic_Updater {
         *
         * @since 3.7.0
         *
+        * @global wpdb $wpdb
+        *
         * @param string $type    The type of update being checked: 'core', 'theme',
         *                        'plugin', 'translation'.
         * @param object $item    The update offer.
@@ -1909,8 +2615,14 @@ class WP_Automatic_Updater {
                if ( $this->is_disabled() )
                        return false;
 
+               // Only relax the filesystem checks when the update doesn't include new files
+               $allow_relaxed_file_ownership = false;
+               if ( 'core' == $type && isset( $item->new_files ) && ! $item->new_files ) {
+                       $allow_relaxed_file_ownership = true;
+               }
+
                // If we can't do an auto core update, we may still be able to email the user.
-               if ( ! $skin->request_filesystem_credentials( false, $context ) || $this->is_vcs_checkout( $context ) ) {
+               if ( ! $skin->request_filesystem_credentials( false, $context, $allow_relaxed_file_ownership ) || $this->is_vcs_checkout( $context ) ) {
                        if ( 'core' == $type )
                                $this->send_core_update_notification_email( $item );
                        return false;
@@ -1925,15 +2637,15 @@ class WP_Automatic_Updater {
                /**
                 * Filter whether to automatically update core, a plugin, a theme, or a language.
                 *
-                * The dynamic portion of the hook name, $type, refers to the type of update
+                * The dynamic portion of the hook name, `$type`, refers to the type of update
                 * being checked. Can be 'core', 'theme', 'plugin', or 'translation'.
                 *
                 * Generally speaking, plugins, themes, and major core versions are not updated
                 * by default, while translations and minor and development versions for core
                 * are updated by default.
                 *
-                * See the allow_dev_auto_core_updates, allow_minor_auto_core_updates, and
-                * allow_major_auto_core_updates filters for a more straightforward way to
+                * See the {@see 'allow_dev_auto_core_updates', {@see 'allow_minor_auto_core_updates'},
+                * and {@see 'allow_major_auto_core_updates'} filters for a more straightforward way to
                 * adjust core updates.
                 *
                 * @since 3.7.0
@@ -2016,6 +2728,8 @@ class WP_Automatic_Updater {
         *
         * @param string $type The type of update being checked: 'core', 'theme', 'plugin', 'translation'.
         * @param object $item The update offer.
+        *
+        * @return null|WP_Error
         */
        public function update( $type, $item ) {
                $skin = new Automatic_Upgrader_Skin;
@@ -2070,6 +2784,11 @@ class WP_Automatic_Updater {
                                break;
                }
 
+               $allow_relaxed_file_ownership = false;
+               if ( 'core' == $type && isset( $item->new_files ) && ! $item->new_files ) {
+                       $allow_relaxed_file_ownership = true;
+               }
+
                // Boom, This sites about to get a whole new splash of paint!
                $upgrade_result = $upgrader->upgrade( $upgrader_item, array(
                        'clear_update_cache' => false,
@@ -2077,6 +2796,8 @@ class WP_Automatic_Updater {
                        'pre_check_md5'      => false,
                        // Only available for core updates.
                        'attempt_rollback'   => true,
+                       // Allow relaxed file ownership in some scenarios
+                       'allow_relaxed_file_ownership' => $allow_relaxed_file_ownership,
                ) );
 
                // If the filesystem is unavailable, false is returned.
@@ -2084,7 +2805,7 @@ class WP_Automatic_Updater {
                        $upgrade_result = new WP_Error( 'fs_unavailable', __( 'Could not access filesystem.' ) );
                }
 
-               // Core doesn't output this, so lets append it so we don't get confused.
+               // Core doesn't output this, so let's append it so we don't get confused.
                if ( 'core' == $type ) {
                        if ( is_wp_error( $upgrade_result ) ) {
                                $skin->error( __( 'Installation Failed' ), $upgrade_result );
@@ -2107,6 +2828,9 @@ class WP_Automatic_Updater {
         * Kicks off the background update process, looping through all pending updates.
         *
         * @since 3.7.0
+        *
+        * @global wpdb   $wpdb
+        * @global string $wp_version
         */
        public function run() {
                global $wpdb, $wp_version;
@@ -2198,9 +2922,7 @@ class WP_Automatic_Updater {
                        }
 
                        // Clear existing caches
-                       wp_clean_plugins_cache();
-                       wp_clean_themes_cache();
-                       delete_site_transient( 'update_core' );
+                       wp_clean_update_cache();
 
                        wp_version_check();  // check for Core updates
                        wp_update_themes();  // Check for Theme updates
@@ -2244,7 +2966,9 @@ class WP_Automatic_Updater {
         * If we tried to perform a core update, check if we should send an email,
         * and if we need to avoid processing future updates.
         *
-        * @param object $update_result The result of the core update. Includes the update offer and result.
+        * @global string $wp_version
+        *
+        * @param object|WP_Error $update_result The result of the core update. Includes the update offer and result.
         */
        protected function after_core_update( $update_result ) {
                global $wp_version;
@@ -2331,6 +3055,8 @@ class WP_Automatic_Updater {
         *
         * @since 3.7.0
         *
+        * @global string $wp_version
+        *
         * @param string $type        The type of email to send. Can be one of 'success', 'fail', 'manual', 'critical'.
         * @param object $core_update The update offer that was attempted.
         * @param mixed  $result      Optional. The result for the core update. Can be WP_Error.
@@ -2588,15 +3314,15 @@ class WP_Automatic_Updater {
 
                $site_title = wp_specialchars_decode( get_bloginfo( 'name' ), ENT_QUOTES );
                if ( $failures ) {
-                       $body[] = trim( __( "
-BETA TESTING?
+                       $body[] = trim( __(
+"BETA TESTING?
 =============
 
 This debugging email is sent when you are using a development version of WordPress.
 
 If you think these failures might be due to a bug in WordPress, could you report it?
  * Open a thread in the support forums: https://wordpress.org/support/forum/alphabeta
- * Or, if you're comfortable writing a bug report: http://core.trac.wordpress.org/
+ * Or, if you're comfortable writing a bug report: https://core.trac.wordpress.org/
 
 Thanks! -- The WordPress Team" ) );
                        $body[] = '';
@@ -2606,8 +3332,8 @@ Thanks! -- The WordPress Team" ) );
                        $subject = sprintf( __( '[%s] Background updates have finished' ), $site_title );
                }
 
-               $body[] = trim( __( '
-UPDATE LOG
+               $body[] = trim( __(
+'UPDATE LOG
 ==========' ) );
                $body[] = '';