Ticket #28441: wp-plugin-paths.php

<?php

/**
 * Store and resolve plugin paths.
 *
 * Used to make symlinked plugins work correctly.
 *
 * @since 4.2.0
 */
final class WP_Plugin_Paths {

        /**
         * The path to the plugins directory.
         *
         * @since 4.2.0
         *
         * @var string
         */
        private static $plugins_dir;

        /**
         * The registered plugin paths.
         *
         * Each element has the following keys:
         * - 'plugin_path' The path to the plugin directory.
         * - 'plugin_realpath' The path to the plugin directory, with symlinks resolved.
         * - 'realpath_length' The string length of the realpath.
         *
         * @since 4.2.0
         *
         * @var array
         */
        private static $paths = array();

        /**
         * Whether the paths have been sorted.
         *
         * Saves us from sorting them multiple times.
         *
         * @since 4.2.0
         *
         * @var bool $paths_sorted
         */
        private static $paths_sorted = false;

        /**
         * Register a plugin's real path.
         *
         * The real path is used to resolve symlinked plugins.
         *
         * Single-file plugin's symlinks aren't resolved, because they don't include any
         * assets, so they have no need to get the URL relative to themselves.
         *
         * @since 4.2.0
         *
         * @param string $file The known path to the plugin's main file.
         *
         * @return bool Whether the path was able to be registered.
         */
        public static function register( $file ) {

                $file = wp_normalize_path( $file );

                // We store this so that we don't have to keep normalizing a constant value.
                if ( ! isset( self::$plugins_dir ) ) {
                        self::$plugins_dir = wp_normalize_path( WP_PLUGINS_DIR );
                }

                $plugin_path = wp_normalize_path( dirname( $file ) );

                // It was a single-file plugin.
                if ( $plugin_path . '/' === self::$plugins_dir ) {
                        return false;
                }

                $plugin_realpath = wp_normalize_path( dirname( realpath( $file ) ) );

                if ( $plugin_path !== $plugin_realpath ) {

                        $realpath_length = strlen( $plugin_realpath );

                        // Use unique keys, but still easy to sort by realpath length.
                        self::$paths[ $realpath_length . '-' . $plugin_path ] = array(
                                'plugin_path'     => $plugin_path,
                                'plugin_realpath' => $plugin_realpath,
                                'realpath_length' => $realpath_length,
                        );

                        self::$paths_sorted = false;
                }

                return true;
        }

        /**
         * Reverse resolve a plugin symlink path from the realpath.
         *
         * @since 4.2.0
         *
         * @param string $file The real path of the main plugin file.
         *
         * @return string The path to the symlink in the plugins directory.
         */
        public static function resolve( $file ) {

                $file = wp_normalize_path( $file );

                // Sort the paths by the realpath length, see https://core.trac.wordpress.org/ticket/28441.
                if ( ! self::$paths_sorted ) {
                        krsort( self::$paths );
                        self::$paths_sorted = true;
                }

                foreach ( self::$paths as $path ) {
                        if ( 0 === strpos( $file, $path['plugin_realpath'] ) ) {
                                $file = $path['plugin_path'] . substr( $file, $path['realpath_length'] );
                        }
                }

                return $file;
        }
}