Filesystem: Rewrite FTP/FTP Sockets `exists()` methods to implement a more stable check.

WordPress FTP file checking was previously based upon `ftp_nlist()`. This function can be problematic at scale with a directory containing a large number of files. The same issue occurred using it with ftpsockets.

This changeset rewrites the FTP `exists()` functions to utilize a more efficient and stable check.

Props giox069, desrosj, mkox, afragen, costdev, pbiron, peterwilsoncc.
Fixes #51170.
See #53318, #39781.

Built from https://develop.svn.wordpress.org/trunk@53860


git-svn-id: http://core.svn.wordpress.org/trunk@53419 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/class-wp-filesystem-ftpext.php

@@ -412,18 +412,18 @@ class WP_Filesystem_FTPext extends WP_Filesystem_Base {
 	 * Checks if a file or directory exists.
 	 *
 	 * @since 2.5.0
+	 * @since 6.1.0 Rewrite using ftp_rawlist, uses 'LIST' on FTP server
+	 *              takes file path or directory path as parameter.
 	 *
 	 * @param string $file Path to file or directory.
 	 * @return bool Whether $file exists or not.
 	 */
 	public function exists( $file ) {
-		$list = ftp_nlist( $this->link, $file );
-
-		if ( empty( $list ) && $this->is_dir( $file ) ) {
-			return true; // File is an empty directory.
+		if ( $this->is_dir( $file ) ) {
+			return true;
 		}
 
-		return ! empty( $list ); // Empty list = no file, so invert.
+		return ! empty( ftp_rawlist( $this->link, $file ) );
 	}
 
 	/**
@@ -510,9 +510,10 @@ class WP_Filesystem_FTPext extends WP_Filesystem_Base {
 	 * Gets the file size (in bytes).
 	 *
 	 * @since 2.5.0
+	 * @since 6.1.0 Update for proper return values.
 	 *
 	 * @param string $file Path to file.
-	 * @return int|false Size of the file in bytes on success, false on failure.
+	 * @return int Size of the file in bytes on success, -1 on failure.
 	 */
 	public function size( $file ) {
 		return ftp_size( $this->link, $file );

wp-admin/includes/class-wp-filesystem-ftpsockets.php

@@ -414,19 +414,17 @@ class WP_Filesystem_ftpsockets extends WP_Filesystem_Base {
 	 * Checks if a file or directory exists.
 	 *
 	 * @since 2.5.0
+	 * @since 6.1.0 Rewrite using file size.
 	 *
 	 * @param string $file Path to file or directory.
 	 * @return bool Whether $file exists or not.
 	 */
 	public function exists( $file ) {
-		$list = $this->ftp->nlist( $file );
-
-		if ( empty( $list ) && $this->is_dir( $file ) ) {
-			return true; // File is an empty directory.
+		if ( $this->is_dir( $file ) ) {
+			return true;
 		}
 
-		return ! empty( $list ); // Empty list = no file, so invert.
-		// Return $this->ftp->is_exists($file); has issues with ABOR+426 responses on the ncFTPd server.
+		return is_numeric( $this->size( $file ) );
 	}
 
 	/**

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.1-alpha-53859';
+$wp_version = '6.1-alpha-53860';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.