From 8465dec59ad72ef216eaeae346c9dbf6684314eb Mon Sep 17 00:00:00 2001
From: Weston Ruter <westonruter@git.wordpress.org>
Date: Wed, 19 Apr 2023 01:24:40 +0000
Subject: [PATCH] Script Loader: Optimize performance of
 `_wp_normalize_relative_css_links()` by more than 2x.

* Replace `preg_match_all()` and its secondary `str_replace()` call with `preg_replace_callback()`.
* Fix case where paths beginning with `http` and `https` (but not `http:` and `https:`) were erroneously not counted as relative.
* Improve code style and readability by consolidating conditions and returning once.
* Use `str_starts_with()` consistently instead of `strpos()`.

Follow-up to [52036], [52695], and [52754].

Fixes #58069.
See #54243.


git-svn-id: https://develop.svn.wordpress.org/trunk@55658 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-includes/script-loader.php           | 59 +++++++++------------
 tests/phpunit/tests/dependencies/styles.php |  8 +++
 2 files changed, 34 insertions(+), 33 deletions(-)

diff --git a/src/wp-includes/script-loader.php b/src/wp-includes/script-loader.php
index ba94e3b3d2..9423145a77 100644
--- a/src/wp-includes/script-loader.php
+++ b/src/wp-includes/script-loader.php
@@ -2939,41 +2939,34 @@ function wp_maybe_inline_styles() {
  * @return string The CSS with URLs made relative to the WordPress installation.
  */
 function _wp_normalize_relative_css_links( $css, $stylesheet_url ) {
-	$has_src_results = preg_match_all( '#url\s*\(\s*[\'"]?\s*([^\'"\)]+)#', $css, $src_results );
-	if ( $has_src_results ) {
-		// Loop through the URLs to find relative ones.
-		foreach ( $src_results[1] as $src_index => $src_result ) {
-			// Skip if this is an absolute URL.
-			if ( 0 === strpos( $src_result, 'http' ) || 0 === strpos( $src_result, '//' ) ) {
-				continue;
+	return preg_replace_callback(
+		'#(url\s*\(\s*[\'"]?\s*)([^\'"\)]+)#',
+		static function ( $matches ) use ( $stylesheet_url ) {
+			list( , $prefix, $url ) = $matches;
+
+			if ( ! (
+				str_starts_with( $url, 'http:' )
+				||
+				str_starts_with( $url, 'https:' )
+				||
+				str_starts_with( $url, '//' )
+				||
+				str_starts_with( $url, '#' )
+				||
+				str_starts_with( $url, 'data:' )
+			) ) {
+				// Build the absolute URL.
+				$absolute_url = dirname( $stylesheet_url ) . '/' . $url;
+				$absolute_url = str_replace( '/./', '/', $absolute_url );
+
+				// Convert to URL related to the site root.
+				$url = wp_make_link_relative( $absolute_url );
 			}
 
-			// Skip if the URL is an HTML ID.
-			if ( str_starts_with( $src_result, '#' ) ) {
-				continue;
-			}
-
-			// Skip if the URL is a data URI.
-			if ( str_starts_with( $src_result, 'data:' ) ) {
-				continue;
-			}
-
-			// Build the absolute URL.
-			$absolute_url = dirname( $stylesheet_url ) . '/' . $src_result;
-			$absolute_url = str_replace( '/./', '/', $absolute_url );
-			// Convert to URL related to the site root.
-			$relative_url = wp_make_link_relative( $absolute_url );
-
-			// Replace the URL in the CSS.
-			$css = str_replace(
-				$src_results[0][ $src_index ],
-				str_replace( $src_result, $relative_url, $src_results[0][ $src_index ] ),
-				$css
-			);
-		}
-	}
-
-	return $css;
+			return $prefix . $url;
+		},
+		$css
+	);
 }
 
 /**
diff --git a/tests/phpunit/tests/dependencies/styles.php b/tests/phpunit/tests/dependencies/styles.php
index 0d2f8e664b..e0a13af5e3 100644
--- a/tests/phpunit/tests/dependencies/styles.php
+++ b/tests/phpunit/tests/dependencies/styles.php
@@ -240,6 +240,14 @@ class Tests_Dependencies_Styles extends WP_UnitTestCase {
 				'css'      => 'img {mask-image: url(\'data:image/svg+xml;utf8,<svg></svg>\');}',
 				'expected' => 'img {mask-image: url(\'data:image/svg+xml;utf8,<svg></svg>\');}',
 			),
+			'URLs with path beginning with http'           => array(
+				'css'      => 'p {background:url( "http-is-awesome.png" );}',
+				'expected' => 'p {background:url( "/wp-content/themes/test/http-is-awesome.png" );}',
+			),
+			'URLs with path beginning with https'          => array(
+				'css'      => 'p {background:url( "https-is-more-awesome.png" );}',
+				'expected' => 'p {background:url( "/wp-content/themes/test/https-is-more-awesome.png" );}',
+			),
 		);
 	}