From f2cc9969e37064cf8b4c348af00d8030af54a56c Mon Sep 17 00:00:00 2001
From: Jan Szaszi <jszaszi@qualityunit.com>
Date: Mon, 21 Feb 2022 13:32:06 +0100
Subject: [PATCH] fix: match also empty value for decoding

---
 src/Header/Part/MimeLiteralPart.php                      | 2 +-
 tests/MailMimeParser/Header/Part/MimeLiteralPartTest.php | 7 +++++++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/Header/Part/MimeLiteralPart.php b/src/Header/Part/MimeLiteralPart.php
index 974c2f92..05a8cf63 100644
--- a/src/Header/Part/MimeLiteralPart.php
+++ b/src/Header/Part/MimeLiteralPart.php
@@ -125,7 +125,7 @@ private function decodeMatchedEntity($matches)
      */
     private function decodeSplitPart($entity)
     {
-        if (preg_match('/^=\?([A-Za-z\-_0-9]+)\*?([A-Za-z\-_0-9]+)?\?([QBqb])\?([^\?]+)\?=$/', $entity, $matches)) {
+        if (preg_match('/^=\?([A-Za-z\-_0-9]+)\*?([A-Za-z\-_0-9]+)?\?([QBqb])\?([^\?]*)\?=$/', $entity, $matches)) {
             return $this->decodeMatchedEntity($matches);
         }
         $decoded = $this->convertEncoding($entity);
diff --git a/tests/MailMimeParser/Header/Part/MimeLiteralPartTest.php b/tests/MailMimeParser/Header/Part/MimeLiteralPartTest.php
index fee843f7..22f5b3fd 100644
--- a/tests/MailMimeParser/Header/Part/MimeLiteralPartTest.php
+++ b/tests/MailMimeParser/Header/Part/MimeLiteralPartTest.php
@@ -47,6 +47,13 @@ public function testMimeEncoding()
         $this->assertDecoded('Kilgore Trout', '=?US-ASCII?Q?Kilgore_Trout?=');
     }
 
+    public function testDecodeEmpty()
+    {
+        $this->assertDecoded('', '=?US-ASCII?Q??=');
+        $this->assertDecoded('', '=?utf-8?Q??=');
+    }
+
+
     public function testMimeEncodingNullLanguage()
     {
         $part = $this->assertDecoded('Kilgore Trout', '=?US-ASCII?Q?Kilgore_Trout?=');