From d1e841c03b794be451ab942b9e64f35b5d9e19ac Mon Sep 17 00:00:00 2001
From: Boone Gorges <boonebgorges@git.wordpress.org>
Date: Wed, 19 Nov 2014 01:52:57 +0000
Subject: [PATCH] Improvements to `wp_make_link_relative()`.

* Support relative URL input.
* When the URL being made relative has another URL as a parameter, don't make the second URL relative.

Props voldemortensen.
Fixes #30373.

git-svn-id: https://develop.svn.wordpress.org/trunk@30383 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-includes/formatting.php |  2 +-
 tests/phpunit/tests/link.php   | 32 +++++++++++++++++++++++++++++++-
 2 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/src/wp-includes/formatting.php b/src/wp-includes/formatting.php
index 411eaa8601..57cfcb1eac 100644
--- a/src/wp-includes/formatting.php
+++ b/src/wp-includes/formatting.php
@@ -3239,7 +3239,7 @@ function tag_escape($tag_name) {
  * @return string Absolute path.
  */
 function wp_make_link_relative( $link ) {
-	return preg_replace( '|https?://[^/]+(/.*)|i', '$1', $link );
+	return preg_replace( '|^(https?:)?//[^/]+(/.*)|i', '$2', $link );
 }
 
 /**
diff --git a/tests/phpunit/tests/link.php b/tests/phpunit/tests/link.php
index 9e3a39d1a0..ec94d6084e 100644
--- a/tests/phpunit/tests/link.php
+++ b/tests/phpunit/tests/link.php
@@ -256,4 +256,34 @@ class Tests_Link extends WP_UnitTestCase {
 		$this->assertEquals( $four, get_adjacent_post( true, array( $exclude ), true ) );
 		$this->assertEmpty( get_adjacent_post( false, array(), false ) );
 	}
-}
\ No newline at end of file
+
+	public function test_wp_make_link_relative_with_http_scheme() {
+		$link = 'http://example.com/this-is-a-test-http-url/';
+		$relative_link = wp_make_link_relative( $link );
+		$this->assertEquals( '/this-is-a-test-http-url/', $relative_link );
+	}
+
+	public function test_wp_make_link_relative_with_https_scheme() {
+		$link = 'https://example.com/this-is-a-test-https-url/';
+		$relative_link = wp_make_link_relative( $link );
+		$this->assertEquals( '/this-is-a-test-https-url/', $relative_link );
+	}
+
+	/**
+	 * @ticket 30373
+	 */
+	public function test_wp_make_link_relative_with_no_scheme() {
+		$link = '//example.com/this-is-a-test-schemeless-url/';
+		$relative_link = wp_make_link_relative( $link );
+		$this->assertEquals( '/this-is-a-test-schemeless-url/', $relative_link );
+	}
+
+	/**
+	 * @ticket 30373
+	 */
+	public function test_wp_make_link_relative_should_retain_URL_param_that_is_also_a_URL() {
+		$link = 'https://example.com/this-is-a-test/?redirect=https://example.org/a-different-test-post/';
+		$relative_link = wp_make_link_relative( $link );
+		$this->assertEquals( '/this-is-a-test/?redirect=https://example.org/a-different-test-post/', $relative_link );
+	}
+}