Fonts: Keep font names through CSS validation, storage, and output

src/wp-includes/fonts/class-wp-font-collection.php

@@ -259,7 +259,7 @@ private static function get_sanitization_schema() {
 						'preview'    => 'sanitize_url',
 						'fontFace'   => array(
 							array(
-								'fontFamily'            => 'sanitize_text_field',
+								'fontFamily'            => 'WP_Font_Utils::sanitize_font_family',
 								'fontStyle'             => 'sanitize_text_field',
 								'fontWeight'            => 'sanitize_text_field',
 								'src'                   => static function ( $value ) {

src/wp-includes/fonts/class-wp-font-face-resolver.php

@@ -113,16 +113,13 @@ private static function parse_settings( array $settings ) {
 	 * parse and return the fist font from the list.
 	 *
 	 * @since 6.4.0
+	 * @since 7.2.0 Returns the name as a quoted CSS string, or an empty string if the value is invalid.
 	 *
 	 * @param string $font_family Font family `fontFamily' to parse.
 	 * @return string Font-family name.
 	 */
 	private static function maybe_parse_name_from_comma_separated_list( $font_family ) {
-		if ( str_contains( $font_family, ',' ) ) {
-			$font_family = explode( ',', $font_family )[0];
-		}
-
-		return trim( $font_family, "\"'" );
+		return WP_Font_Utils::get_font_face_family( $font_family );
 	}
 
 	/**

src/wp-includes/fonts/class-wp-font-face.php

@@ -11,6 +11,7 @@
  * Font Face generates and prints `@font-face` styles for given fonts.
  *
  * @since 6.4.0
+ * @since 7.2.0 Writes the font-family descriptor as a quoted CSS string.
  */
 class WP_Font_Face {
 
@@ -82,8 +83,9 @@ public function generate_and_print( array $fonts ) {
 
 		/*
 		 * The font-face CSS is contained within <style> tags and can only be interpreted
-		 * as CSS in the browser. Using wp_strip_all_tags() is sufficient escaping
-		 * to avoid malicious attempts to close </style> and open a <script>.
+		 * as CSS in the browser. The font-family descriptor escapes `<` as a CSS escape,
+		 * so a font name cannot close the style element. wp_strip_all_tags() removes any
+		 * remaining markup from the other descriptors.
 		 */
 		$css = wp_strip_all_tags( $css );
 
@@ -146,6 +148,23 @@ private function validate_font_face_declarations( array $font_face ) {
 			return false;
 		}
 
+		/*
+		 * Write the font-family descriptor as a quoted CSS string. The value
+		 * can be CSS, such as `"ACME, Sans"`, or a plain name, such as
+		 * `O'Reilly Sans`. The decoded name does not change.
+		 */
+		$font_face['font-family'] = WP_Font_Utils::get_font_face_family( $font_face['font-family'] );
+
+		if ( '' === $font_face['font-family'] ) {
+			// @todo replace with `wp_trigger_error()`.
+			_doing_it_wrong(
+				__METHOD__,
+				__( 'Font font-family must be a valid CSS font family value or a plain font name.' ),
+				'7.2.0'
+			);
+			return false;
+		}
+
 		// Make sure that local fonts have 'src' defined.
 		if ( empty( $font_face['src'] ) || ( ! is_string( $font_face['src'] ) && ! is_array( $font_face['src'] ) ) ) {
 			// @todo replace with `wp_trigger_error()`.
@@ -307,18 +326,7 @@ private function order_src( array $font_face ) {
 	private function build_font_face_css( array $font_face ) {
 		$css = '';
 
-		/*
-		 * Wrap font-family in quotes if it contains spaces
-		 * and is not already wrapped in quotes.
-		 */
-		if (
-			str_contains( $font_face['font-family'], ' ' ) &&
-			! str_contains( $font_face['font-family'], '"' ) &&
-			! str_contains( $font_face['font-family'], "'" )
-		) {
-			$font_face['font-family'] = '"' . $font_face['font-family'] . '"';
-		}
-
+		// The font-family is already a quoted CSS string. See ::validate_font_face_declarations().
 		foreach ( $font_face as $key => $value ) {
 			// Compile the "src" parameter.
 			if ( 'src' === $key ) {