Editor: Prevent infinite loops when filtering the font library folder.

Changing the font library is something we expect hosts to perform.
It's important that we make this filter as seemless as possible.
This commit prevents a potential infinite loop caused by calling wp_get_upload_dir() within the font_dir filter.

Props mmaattiiaass, ironprogrammer, costdev, swissspidy.
Fixes #60652.

git-svn-id: https://develop.svn.wordpress.org/trunk@57740 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/fonts.php

@@ -96,16 +96,6 @@ function wp_unregister_font_collection( string $slug ) {
  *
  * @since 6.5.0
  *
- * @param array $defaults {
- *     Array of information about the upload directory.
- *
- *     @type string       $path    Base directory and subdirectory or full path to the fonts upload directory.
- *     @type string       $url     Base URL and subdirectory or absolute URL to the fonts upload directory.
- *     @type string       $subdir  Subdirectory
- *     @type string       $basedir Path without subdir.
- *     @type string       $baseurl URL path without subdir.
- *     @type string|false $error   False or error message.
- * }
  * @return array $defaults {
  *     Array of information about the upload directory.
  *
@@ -117,19 +107,20 @@ function wp_unregister_font_collection( string $slug ) {
  *     @type string|false $error   False or error message.
  * }
  */
-function wp_get_font_dir( $defaults = array() ) {
+function wp_get_font_dir() {
 	$site_path = '';
 	if ( is_multisite() && ! ( is_main_network() && is_main_site() ) ) {
 		$site_path = '/sites/' . get_current_blog_id();
 	}
 
-	// Sets the defaults.
-	$defaults['path']    = path_join( WP_CONTENT_DIR, 'fonts' ) . $site_path;
-	$defaults['url']     = untrailingslashit( content_url( 'fonts' ) ) . $site_path;
-	$defaults['subdir']  = '';
-	$defaults['basedir'] = path_join( WP_CONTENT_DIR, 'fonts' ) . $site_path;
-	$defaults['baseurl'] = untrailingslashit( content_url( 'fonts' ) ) . $site_path;
-	$defaults['error']   = false;
+	$defaults = array(
+		'path'    => path_join( WP_CONTENT_DIR, 'fonts' ) . $site_path,
+		'url'     => untrailingslashit( content_url( 'fonts' ) ) . $site_path,
+		'subdir'  => '',
+		'basedir' => path_join( WP_CONTENT_DIR, 'fonts' ) . $site_path,
+		'baseurl' => untrailingslashit( content_url( 'fonts' ) ) . $site_path,
+		'error'   => false,
+	);
 
 	/**
 	 * Filters the fonts directory data.

src/wp-includes/rest-api/endpoints/class-wp-rest-font-faces-controller.php

@@ -856,7 +856,21 @@ protected function sanitize_src( $value ) {
 	 */
 	protected function handle_font_file_upload( $file ) {
 		add_filter( 'upload_mimes', array( 'WP_Font_Utils', 'get_allowed_font_mime_types' ) );
-		add_filter( 'upload_dir', 'wp_get_font_dir' );
+
+		/*
+		 * Set the upload directory to the fonts directory.
+		 *
+		 * wp_get_font_dir() contains the 'font_dir' hook, whose callbacks are
+		 * likely to call wp_get_upload_dir().
+		 *
+		 * To avoid an infinite loop, don't hook wp_get_font_dir() to 'upload_dir'.
+		 * Instead, just pass its return value to the 'upload_dir' callback.
+		 */
+		$font_dir       = wp_get_font_dir();
+		$set_upload_dir = function () use ( $font_dir ) {
+			return $font_dir;
+		};
+		add_filter( 'upload_dir', $set_upload_dir );
 
 		$overrides = array(
 			'upload_error_handler' => array( $this, 'handle_font_file_upload_error' ),
@@ -874,7 +888,7 @@ protected function handle_font_file_upload( $file ) {
 
 		$uploaded_file = wp_handle_upload( $file, $overrides );
 
-		remove_filter( 'upload_dir', 'wp_get_font_dir' );
+		remove_filter( 'upload_dir', $set_upload_dir );
 		remove_filter( 'upload_mimes', array( 'WP_Font_Utils', 'get_allowed_font_mime_types' ) );
 
 		return $uploaded_file;
@@ -902,16 +916,16 @@ public function handle_font_file_upload_error( $file, $message ) {
 	}
 
 	/**
-	* Returns relative path to an uploaded font file.
-	*
-	* The path is relative to the current fonts directory.
-	*
-	* @since 6.5.0
-	* @access private
-	*
-	* @param string $path Full path to the file.
-	* @return string Relative path on success, unchanged path on failure.
-	*/
+	 * Returns relative path to an uploaded font file.
+	 *
+	 * The path is relative to the current fonts directory.
+	 *
+	 * @since 6.5.0
+	 * @access private
+	 *
+	 * @param string $path Full path to the file.
+	 * @return string Relative path on success, unchanged path on failure.
+	 */
 	protected function relative_fonts_path( $path ) {
 		$new_path = $path;