Fix Kernel to properly handle Windows paths

lib/SimpleSAML/Kernel.php

@@ -4,6 +4,7 @@ declare(strict_types=1);
 
 namespace SimpleSAML;
 
+use SimpleSAML\Utils\System;
 use Symfony\Bundle\FrameworkBundle\FrameworkBundle;
 use Symfony\Bundle\FrameworkBundle\Kernel\MicroKernelTrait;
 use Symfony\Component\Config\Exception\FileLocatorFileNotFoundException;
@@ -51,7 +52,7 @@ class Kernel extends BaseKernel
         $configuration = Configuration::getInstance();
         $cachePath = $configuration->getString('tempdir') . '/cache/' . $this->module;
 
-        if (0 === strpos($cachePath, '/')) {
+        if (System::isAbsolutePath($cachePath)) {
             return $cachePath;
         }
 
@@ -67,7 +68,7 @@ class Kernel extends BaseKernel
         $configuration = Configuration::getInstance();
         $loggingPath = $configuration->getString('loggingdir');
 
-        if (0 === strpos($loggingPath, '/')) {
+        if (System::isAbsolutePath($loggingPath)) {
             return $loggingPath;
         }
 

lib/SimpleSAML/Utils/System.php

@@ -238,6 +238,20 @@ class System
         }
     }
 
+
+    /**
+     * Check if the supplied path is an absolute path.
+     *
+     * @param string $path
+     *
+     * @return bool
+     */
+    public static function isAbsolutePath(string $path): bool
+    {
+        return (0 === strpos($path, '/') || self::pathContainsDriveLetter($path));
+    }
+
+
     /**
      * Check if the supplied path contains a Windows-style drive letter.
      *