From 9393fe36438ede860dd8d469032a1d6355236bea Mon Sep 17 00:00:00 2001
From: Cameron Ball <cameronball@catalyst-au.net>
Date: Wed, 5 Jan 2022 18:22:21 +0800
Subject: [PATCH] MDL-73427 core: Remove $SESSION->fromurl

---
 lib/moodlelib.php           |  5 -----
 lib/setuplib.php            |  7 +------
 lib/tests/setuplib_test.php | 26 --------------------------
 mod/forum/post.php          |  8 +-------
 4 files changed, 2 insertions(+), 44 deletions(-)

diff --git a/lib/moodlelib.php b/lib/moodlelib.php
index 32e0234bf3d..cc6bd768b78 100644
--- a/lib/moodlelib.php
+++ b/lib/moodlelib.php
@@ -2727,11 +2727,6 @@ function require_login($courseorid = null, $autologinguest = true, $cm = null, $
                 $SESSION->wantsurl = qualified_me();
             }
 
-            $referer = get_local_referer(false);
-            if (!empty($referer)) {
-                $SESSION->fromurl = $referer;
-            }
-
             // Give auth plugins an opportunity to authenticate or redirect to an external login page
             $authsequence = get_enabled_auth_plugins(); // Auths, in sequence.
             foreach($authsequence as $authname) {
diff --git a/lib/setuplib.php b/lib/setuplib.php
index 2af28136af9..f1ad98d70ae 100644
--- a/lib/setuplib.php
+++ b/lib/setuplib.php
@@ -588,12 +588,7 @@ function get_exception_info($ex) {
     $moreinfourl = $errordoclink . 'error/' . $modulelink . '/' . $errorcode;
 
     if (empty($link)) {
-        if (!empty($SESSION->fromurl)) {
-            $link = $SESSION->fromurl;
-            unset($SESSION->fromurl);
-        } else {
-            $link = $CFG->wwwroot .'/';
-        }
+        $link = get_local_referer(false) ?: ($CFG->wwwroot . '/');
     }
 
     // When printing an error the continue button should never link offsite.
diff --git a/lib/tests/setuplib_test.php b/lib/tests/setuplib_test.php
index 9291605e9cd..9d165b99dd7 100644
--- a/lib/tests/setuplib_test.php
+++ b/lib/tests/setuplib_test.php
@@ -412,32 +412,6 @@ class core_setuplib_testcase extends advanced_testcase {
         $exception = new moodle_exception('none', 'error', $url);
         $infos = $this->get_exception_info($exception);
         $this->assertSame($CFG->wwwroot . '/', $infos->link);
-
-        // Internal link from fromurl.
-        $SESSION->fromurl = $url = $CFG->wwwroot . '/something/here?really=yes';
-        $exception = new moodle_exception('none');
-        $infos = $this->get_exception_info($exception);
-        $this->assertSame($url, $infos->link);
-
-        // Internal HTTPS link from fromurl.
-        $SESSION->fromurl = $url = $httpswwwroot . '/something/here?really=yes';
-        $exception = new moodle_exception('none');
-        $infos = $this->get_exception_info($exception);
-        $this->assertSame($url, $infos->link);
-
-        // External link from fromurl.
-        $SESSION->fromurl = 'http://moodle.org/something/here?really=yes';
-        $exception = new moodle_exception('none');
-        $infos = $this->get_exception_info($exception);
-        $this->assertSame($CFG->wwwroot . '/', $infos->link);
-
-        // External HTTPS link from fromurl.
-        $SESSION->fromurl = 'https://moodle.org/something/here?really=yes';
-        $exception = new moodle_exception('none');
-        $infos = $this->get_exception_info($exception);
-        $this->assertSame($CFG->wwwroot . '/', $infos->link);
-
-        $SESSION->fromurl = '';
     }
 
     /**
diff --git a/mod/forum/post.php b/mod/forum/post.php
index 7d9e3abc288..ae162ebfa75 100644
--- a/mod/forum/post.php
+++ b/mod/forum/post.php
@@ -160,8 +160,6 @@ if (!empty($forum)) {
             );
     }
 
-    $SESSION->fromurl = get_local_referer(false);
-
     // Load up the $post variable.
 
     $post = new stdClass();
@@ -780,11 +778,7 @@ if ($mformpost->is_cancelled()) {
     }
 } else if ($mformpost->is_submitted() && !$mformpost->no_submit_button_pressed() && $fromform = $mformpost->get_data()) {
 
-    if (empty($SESSION->fromurl)) {
-        $errordestination = $urlfactory->get_forum_view_url_from_forum($forumentity);
-    } else {
-        $errordestination = $SESSION->fromurl;
-    }
+    $errordestination = get_local_referer(false) ?: $urlfactory->get_forum_view_url_from_forum($forumentity);
 
     $fromform->itemid        = $fromform->message['itemid'];
     $fromform->messageformat = $fromform->message['format'];