From 4e8b1045434086720383d349bd3b8fe101c378d2 Mon Sep 17 00:00:00 2001
From: 3D-I <480857+3D-I@users.noreply.github.com>
Date: Fri, 27 Nov 2020 20:50:06 +0100
Subject: [PATCH] [ticket/16641] Fix config.php validation in ACP - PHP 8

PHPBB3-16641
---
 phpBB/includes/acp/acp_main.php       | 5 ++---
 phpBB/phpbb/filesystem/filesystem.php | 9 +++------
 2 files changed, 5 insertions(+), 9 deletions(-)

diff --git a/phpBB/includes/acp/acp_main.php b/phpBB/includes/acp/acp_main.php
index 368e7c5996..a222bfa1cc 100644
--- a/phpBB/includes/acp/acp_main.php
+++ b/phpBB/includes/acp/acp_main.php
@@ -679,11 +679,10 @@ class acp_main
 			}
 		}
 
+		// We define the variable so we avoid redundancies
 		$config_ref = $phpbb_root_path . 'config.' . $phpEx;
 
-		if (!defined('PHPBB_DISABLE_CONFIG_CHECK') && file_exists($config_ref)
-			&& (function_exists('is_writable') ? is_writable($config_ref) : $phpbb_filesystem->is_writable($config_ref))
-		)
+		if (!defined('PHPBB_DISABLE_CONFIG_CHECK') && file_exists($config_ref) && $phpbb_filesystem->is_writable($config_ref))
 		{
 			// World-Writable? (000x)
 			$template->assign_var('S_WRITABLE_CONFIG', (bool) (@fileperms($config_ref) & 0x0002));
diff --git a/phpBB/phpbb/filesystem/filesystem.php b/phpBB/phpbb/filesystem/filesystem.php
index 7f44d5f1de..fc7cbdf27d 100644
--- a/phpBB/phpbb/filesystem/filesystem.php
+++ b/phpBB/phpbb/filesystem/filesystem.php
@@ -613,13 +613,10 @@ class filesystem implements filesystem_interface
 			}
 			else
 			{
-				$handle = @fopen($file, 'c');
+				$handle = new \SplFileInfo($file);
 
-				if (is_resource($handle))
-				{
-					fclose($handle);
-					return true;
-				}
+				// Returns TRUE if writable, FALSE otherwise
+				return $handle->isWritable();
 			}
 		}
 		else