From 8050285f86443150bbe7f526cd4d5d12449b5c00 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michael=20H=C3=A4rtl?= <haertl.mike@gmail.com>
Date: Tue, 17 Oct 2023 15:00:30 +0200
Subject: [PATCH] Issue #315 Fix htmlspecialchars() warning for null values

---
 src/XfdfFile.php | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/XfdfFile.php b/src/XfdfFile.php
index 7204f98..c1be2d9 100644
--- a/src/XfdfFile.php
+++ b/src/XfdfFile.php
@@ -218,11 +218,14 @@ protected function writeFields($fp, $fields)
     }
 
     /**
-     * @param string $value the value to encode
-     * @return string the value correctly encoded for use in a XML document
+     * @param string|null $value the value to encode
+     * @return string|null the value correctly encoded for use in a XML document
      */
     protected function xmlEncode($value)
     {
+        if ($value === null) {
+            return null;
+        }
         return defined('ENT_XML1') ?
             htmlspecialchars($value, ENT_XML1, 'UTF-8') :
             htmlspecialchars($value);