From 318a1c9c521f9faf7a73a2249e030066bc9f1f2f Mon Sep 17 00:00:00 2001
From: Dion Hulse <dd32@git.wordpress.org>
Date: Tue, 20 Aug 2013 06:46:37 +0000
Subject: [PATCH] WP_Filesystem: Use the FTP_* path override constants during
 upgrades for prefixed paths, ie. use FTP_BASE for ABSPATH/sub-dir as well as
 just for ABSPATH/. Props vericgar for initial patch. See #14401

git-svn-id: https://develop.svn.wordpress.org/trunk@25057 602fd350-edb4-49c9-b593-d223f7449a82
---
 .../includes/class-wp-filesystem-base.php     | 38 ++++++++++++++++---
 1 file changed, 33 insertions(+), 5 deletions(-)

diff --git a/src/wp-admin/includes/class-wp-filesystem-base.php b/src/wp-admin/includes/class-wp-filesystem-base.php
index 9d7d6e8c19..495d60139f 100644
--- a/src/wp-admin/includes/class-wp-filesystem-base.php
+++ b/src/wp-admin/includes/class-wp-filesystem-base.php
@@ -147,11 +147,39 @@ class WP_Filesystem_Base {
 	 */
 	function find_folder($folder) {
 
-		if ( strpos($this->method, 'ftp') !== false ) {
-			$constant_overrides = array( 'FTP_BASE' => ABSPATH, 'FTP_CONTENT_DIR' => WP_CONTENT_DIR, 'FTP_PLUGIN_DIR' => WP_PLUGIN_DIR, 'FTP_LANG_DIR' => WP_LANG_DIR );
-			foreach ( $constant_overrides as $constant => $dir )
-				if ( defined($constant) && $folder === $dir )
-					return trailingslashit(constant($constant));
+		if ( isset( $this->cache[ $folder ] ) )
+			return $this->cache[ $folder ];
+
+		if ( stripos($this->method, 'ftp') !== false ) {
+			$constant_overrides = array(
+				'FTP_BASE' => ABSPATH,
+				'FTP_CONTENT_DIR' => WP_CONTENT_DIR,
+				'FTP_PLUGIN_DIR' => WP_PLUGIN_DIR,
+				'FTP_LANG_DIR' => WP_LANG_DIR
+			);
+
+			// Direct matches ( folder = CONSTANT/ )
+			foreach ( $constant_overrides as $constant => $dir ) {
+				if ( ! defined( $constant ) )
+					continue;
+				if ( $folder === $dir )
+					return trailingslashit( constant( $constant ) );
+			}
+
+			// Prefix Matches ( folder = CONSTANT/subdir )
+			foreach ( $constant_overrides as $constant => $dir ) {
+				if ( ! defined( $constant ) )
+					continue;
+				if ( 0 === stripos( $folder, $dir ) ) { // $folder starts with $dir
+					$potential_folder = preg_replace( '#^' . preg_quote( $dir, '#' ) . '/#i', trailingslashit( constant( $constant ) ), $folder );
+					$potential_folder = trailingslashit( $potential_folder );
+
+					if ( $this->is_dir( $potential_folder ) ) {
+						$this->cache[ $folder ] = $potential_folder;
+						return $potential_folder;
+					}
+				}
+			}
 		} elseif ( 'direct' == $this->method ) {
 			$folder = str_replace('\\', '/', $folder); //Windows path sanitisation
 			return trailingslashit($folder);