From 83f5ab5c79b2603b8861ad312ba780f1cb3b0c1e Mon Sep 17 00:00:00 2001
From: Andrew Dolgov <fox@fakecake.org>
Date: Sat, 12 Aug 2023 09:00:57 +0300
Subject: [PATCH] fix basename() being passed a NULL value

---
 classes/diskcache.php | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/classes/diskcache.php b/classes/diskcache.php
index 6a9038289..b5c10e89d 100644
--- a/classes/diskcache.php
+++ b/classes/diskcache.php
@@ -243,8 +243,9 @@ class DiskCache implements Cache_Adapter {
 		return $this->adapter->make_dir();
 	}
 
+	/** @param string|null $filename null means check that cache directory itself is writable */
 	public function is_writable(?string $filename = null): bool {
-		return $this->adapter->is_writable(basename($filename));
+		return $this->adapter->is_writable($filename ? basename($filename) : null);
 	}
 
 	public function exists(string $filename): bool {