From d0fe0bb3916e1273a52f1de22d3f3b9002d95cbd Mon Sep 17 00:00:00 2001
From: Brendan Heywood <brendan@catalyst-au.net>
Date: Thu, 30 Mar 2023 22:32:31 +1100
Subject: [PATCH] MDL-77797 filter_tex: Add public immutable caching headers

---
 filter/tex/pix.php | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/filter/tex/pix.php b/filter/tex/pix.php
index 570e47330fa..c95073d3bb1 100644
--- a/filter/tex/pix.php
+++ b/filter/tex/pix.php
@@ -66,7 +66,10 @@ define('NO_MOODLE_COOKIES', true); // Because it interferes with caching
     }
 
     if (file_exists($pathname)) {
-        send_file($pathname, $image);
+        send_file($pathname, $image, YEARSECS, 0, false, false, '', false, [
+            'cacheability' => 'public',
+            'immutable' => true,
+        ]);
     } else {
         if (debugging()) {
             echo "The shell command<br />$cmd<br />returned status = $status<br />\n";