From e9fcdec98b086c8a55dbbb8b09d98fe9e55b36e5 Mon Sep 17 00:00:00 2001
From: "Eloy Lafuente (stronk7)" <stronk7@moodle.org>
Date: Tue, 18 Apr 2023 16:03:19 +0200
Subject: [PATCH] MDL-77953 pagelib: Ensure that null $SCRIPT continues
 behaving the same

It's possible to have some Moodle components soft linked instead
of being real directories within codebase (within dirroot).

For example, Composer's "vendor" directory can be soft linked
(from elsewhere), or also plugins can be installed using soft
links.

In those cases, Moodle calculates the $SCRIPT global as null. And,
then, string operations on it are emitting a PHP deprecation message
with PHP 8.1 and up.

This fix just ensures that the behaviour is the same than before
PHP 8.1, aka: ltrim(null) = '' (empty string), without any PHP warning.
---
 lib/pagelib.php | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/pagelib.php b/lib/pagelib.php
index 4b9d7e81cac..b272c0238f1 100644
--- a/lib/pagelib.php
+++ b/lib/pagelib.php
@@ -1873,7 +1873,7 @@ class moodle_page {
         }
 
         if (is_null($script)) {
-            $script = ltrim($SCRIPT, '/');
+            $script = ltrim($SCRIPT ?? '', '/');
             $len = strlen($CFG->admin);
             if (substr($script, 0, $len) == $CFG->admin) {
                 $script = 'admin' . substr($script, $len);