From b0acbd3c60db30a00016e7a80a52984c411b7367 Mon Sep 17 00:00:00 2001
From: Kamil Tekiela <tekiela246@gmail.com>
Date: Mon, 13 Mar 2023 14:38:55 +0000
Subject: [PATCH] Check whether ob_gzhandler is already in use

Signed-off-by: Kamil Tekiela <tekiela246@gmail.com>
---
 libraries/classes/OutputBuffering.php | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/libraries/classes/OutputBuffering.php b/libraries/classes/OutputBuffering.php
index 983fb2e4d2..fc32cbc4c1 100644
--- a/libraries/classes/OutputBuffering.php
+++ b/libraries/classes/OutputBuffering.php
@@ -8,6 +8,7 @@ use function defined;
 use function flush;
 use function function_exists;
 use function header;
+use function in_array;
 use function ini_get;
 use function ob_end_clean;
 use function ob_flush;
@@ -15,6 +16,7 @@ use function ob_get_contents;
 use function ob_get_length;
 use function ob_get_level;
 use function ob_get_status;
+use function ob_list_handlers;
 use function ob_start;
 use function sprintf;
 
@@ -78,7 +80,7 @@ class OutputBuffering
             return;
         }
 
-        if ($this->mode && function_exists('ob_gzhandler')) {
+        if ($this->mode && function_exists('ob_gzhandler') && ! in_array('ob_gzhandler', ob_list_handlers())) {
             ob_start('ob_gzhandler');
         }