fix OS checks. fixes dokuwiki#4446 and dokuwiki#4445

Access to /etc might be restricted. We simply ignore the errors and
pretend the file does not exist.

Strictly speaking, the files are not in ini format. But parsing them as
ini mostly works, except for some comments (on synology), so we strip
the comments first.

This also makes sure the correct file is read on synology.

Author: splitbrain

inc/infoutils.php

@@ -184,7 +184,7 @@ function getRuntimeVersions()
 
     if (getenv('KUBERNETES_SERVICE_HOST')) {
         $data['container'] = 'Kubernetes';
-    } elseif (file_exists('/.dockerenv')) {
+    } elseif (@file_exists('/.dockerenv')) {
         $data['container'] = 'Docker';
     }
 
@@ -199,14 +199,16 @@ function getRuntimeVersions()
  */
 function getOsRelease()
 {
+    $reader = fn($file) => @parse_ini_string(preg_replace('/#.*$/m', '', file_get_contents($file)));
+
     $osRelease = [];
-    if (file_exists('/etc/os-release')) {
+    if (@file_exists('/etc/os-release')) {
         // pretty much any common Linux distribution has this
-        $osRelease = parse_ini_file('/etc/os-release');
-    } elseif (file_exists('/etc/synoinfo.conf') && file_exists('/etc/VERSION')) {
+        $osRelease = $reader('/etc/os-release');
+    } elseif (@file_exists('/etc/synoinfo.conf') && @file_exists('/etc/VERSION')) {
         // Synology DSM has its own way
-        $synoInfo = parse_ini_file('/usr/lib/synoinfo.conf');
-        $synoVersion = parse_ini_file('/etc/VERSION');
+        $synoInfo = $reader('/etc/synoinfo.conf');
+        $synoVersion = $reader('/etc/VERSION');
         $osRelease['NAME'] = 'Synology DSM';
         $osRelease['ID'] = 'synology';
         $osRelease['ID_LIKE'] = 'linux';
@@ -218,6 +220,7 @@ function getOsRelease()
     return $osRelease;
 }
 
+
 /**
  * Run a few sanity checks
  *