diff --git a/core/lib/Drupal/Core/Archiver/ArchiveTar.php b/core/lib/Drupal/Core/Archiver/ArchiveTar.php
index e05a7e9..a639f51 100644
--- a/core/lib/Drupal/Core/Archiver/ArchiveTar.php
+++ b/core/lib/Drupal/Core/Archiver/ArchiveTar.php
@@ -44,6 +44,13 @@
 
 //require_once 'PEAR.php';
 //
+// OS_WINDOWS as defined in PEAR.php
+if (substr(PHP_OS, 0, 3) == 'WIN') {
+    define('OS_WINDOWS', true);
+} else {
+    define('OS_WINDOWS', false);
+}
+
 define('ARCHIVE_TAR_ATT_SEPARATOR', 90001);
 define('ARCHIVE_TAR_END_BLOCK', pack("a512", ''));
 
@@ -1674,7 +1681,7 @@ function _readHeader($v_binary_data, &$v_header)
         }
 
         // ----- Extract the properties
-        $v_header['filename'] = $v_data['filename'];
+        $v_header['filename'] = rtrim($v_data['filename'], "\0");
         if ($this->_maliciousFilename($v_header['filename'])) {
             $this->_error(
                 'Malicious .tar detected, file "' . $v_header['filename'] .
@@ -1730,6 +1737,7 @@ function _maliciousFilename($file)
     function _readLongHeader(&$v_header)
     {
       $v_filename = '';
+      $v_filesize = $v_header['size'];
       $n = floor($v_header['size']/512);
       for ($i=0; $i<$n; $i++) {
         $v_content = $this->_readBlock();
@@ -1737,7 +1745,7 @@ function _readLongHeader(&$v_header)
       }
       if (($v_header['size'] % 512) != 0) {
         $v_content = $this->_readBlock();
-        $v_filename .= trim($v_content);
+        $v_filename .= $v_content;
       }
 
       // ----- Read the next header
@@ -1747,7 +1755,7 @@ function _readLongHeader(&$v_header)
             return false;
         }
 
-        $v_filename = trim($v_filename);
+        $v_filename = rtrim(substr($v_filename, 0, $v_filesize), "\0");
         $v_header['filename'] = $v_filename;
         if ($this->_maliciousFilename($v_filename)) {
             $this->_error(