transfer changeset 59447 from svn

37 files changed, 86 insertions, 73 deletions

diff --git a/app/controllers/files.php b/app/controllers/files.php
index 4e11440..11457cc 100644
--- a/app/controllers/files.php
+++ b/app/controllers/files.php
@@ -365,9 +365,9 @@ class FilesController extends AuthenticatedController
                     $_SESSION['files_overview']['course_id'] = $this->course_id;
                 }
             } else {
-                $this->begin = $_SESSION['files_overview']['begin'];
-                $this->end = $_SESSION['files_overview']['end'];
-                $this->course_id = $_SESSION['files_overview']['course_id'];
+                $this->begin = $_SESSION['files_overview']['begin'] ?? null;
+                $this->end = $_SESSION['files_overview']['end'] ?? null;
+                $this->course_id = $_SESSION['files_overview']['course_id'] ?? null;
             }
         }
 
@@ -473,7 +473,7 @@ class FilesController extends AuthenticatedController
             $new_file_refs = FileRef::findAll($GLOBALS['user']->id, $this->begin, $this->end, $this->course_id, $this->page_size, $offset);
             //Group the file refs by their folder:
             foreach ($new_file_refs as $file_ref) {
-                if (!is_array($folders[$file_ref->folder_id])) {
+                if (!isset($folders[$file_ref->folder_id]) || !is_array($folders[$file_ref->folder_id])) {
                     $folders[$file_ref->folder_id] = [
                         'folder' => $file_ref->folder->getTypedFolder(),
                         'file_refs' => []
diff --git a/app/controllers/studip_controller.php b/app/controllers/studip_controller.php
index fd52034..357ded7 100644
--- a/app/controllers/studip_controller.php
+++ b/app/controllers/studip_controller.php
@@ -293,7 +293,7 @@ abstract class StudipController extends Trails_Controller
         $to = implode('/', $args);
 
         //preserve fragment
-        [$to, $fragment] = explode('#', $to);
+        [$to, $fragment] = @explode('#', $to);
 
         $url = parent::url_for($to);
 
diff --git a/app/views/files/_overview.php b/app/views/files/_overview.php
index 6fd203f..7b03f44 100644
--- a/app/views/files/_overview.php
+++ b/app/views/files/_overview.php
@@ -102,6 +102,6 @@
     </div>
 <? endif ?>
 
-<? if ($no_files) : ?>
+<? if ($no_files ?? false) : ?>
     <?= MessageBox::info(_('Es sind keine Dateien vorhanden, die für Sie zugänglich sind!')) ?>
 <? endif ?>
diff --git a/app/views/files/flat.php b/app/views/files/flat.php
index 7702767..f8c3b4b 100644
--- a/app/views/files/flat.php
+++ b/app/views/files/flat.php
@@ -55,7 +55,7 @@ foreach ($topFolder->getAdditionalActionButtons() as $button) {
                  :files="files"
                  :folders="folders"
                  :topfolder="topfolder"
-                 enable_table_filter="<?= $enable_table_filter ? 'true' : 'false' ?>"
+                 enable_table_filter="<?= $enable_table_filter ?? false ? 'true' : 'false' ?>"
                  table_title="<?= htmlReady($table_title) ?>"
                  pagination="<?= htmlReady($pagination_html) ?>"
                  :initial_sort="{sortedBy:'chdate',sortDirection:'desc'}"
diff --git a/app/views/files_dashboard/_input-group-search.php b/app/views/files_dashboard/_input-group-search.php
index 0606b68..f685461 100644
--- a/app/views/files_dashboard/_input-group-search.php
+++ b/app/views/files_dashboard/_input-group-search.php
@@ -1,7 +1,7 @@
 <div class="input-group files-search">
     <input
         name="q"
-        value="<?= htmlReady($query) ?>"
+        value="<?= htmlReady($query ?? '') ?>"
         placeholder="<?= _('Was suchen Sie?') ?>"
         aria-label="<?= _('Was suchen Sie?') ?>"
         minlength="4"
@@ -13,7 +13,7 @@
             <?= Icon::create('search')->asImg(['title' => _("Suche starten")]) ?>
         </button>
 
-        <? if ($query != '') : ?>
+        <? if ($query ?? false) : ?>
             <?= \Studip\LinkButton::createReset(_('Zurücksetzen'), $controller->url_for('files_dashboard/search')) ?>
         <? endif ?>
     </span>
diff --git a/db/migrations/5.1.22_resize_oer_content_type_length.php b/db/migrations/5.1.22_resize_oer_content_type_length.php
index 0fd36b6..0fd36b6 100644..100755
--- a/db/migrations/5.1.22_resize_oer_content_type_length.php
+++ b/db/migrations/5.1.22_resize_oer_content_type_length.php
diff --git a/lib/bootstrap.php b/lib/bootstrap.php
index 608f929..4c8622a 100644
--- a/lib/bootstrap.php
+++ b/lib/bootstrap.php
@@ -50,11 +50,15 @@ if (isset($_SERVER['SERVER_NAME'])) {
             explode(':', $_SERVER['SERVER_NAME']);
     }
 
-    $ABSOLUTE_URI_STUDIP = $_SERVER['HTTPS'] == 'on' ? 'https' : 'http';
+    $is_https = isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] === 'on';
+
+    $ABSOLUTE_URI_STUDIP = $is_https ? 'https' : 'http';
     $ABSOLUTE_URI_STUDIP .= '://'.$_SERVER['SERVER_NAME'];
 
-    if ($_SERVER['HTTPS'] == 'on' && $_SERVER['SERVER_PORT'] != 443 ||
-        $_SERVER['HTTPS'] != 'on' && $_SERVER['SERVER_PORT'] != 80) {
+    if (
+        ($is_https && $_SERVER['SERVER_PORT'] != 443)
+        || (!$is_https && $_SERVER['SERVER_PORT'] != 80)
+    ) {
         $ABSOLUTE_URI_STUDIP .= ':'.$_SERVER['SERVER_PORT'];
     }
 
diff --git a/lib/classes/Log.php b/lib/classes/Log.php
index 22c9f6c..fc3a2e1 100644
--- a/lib/classes/Log.php
+++ b/lib/classes/Log.php
@@ -119,9 +119,8 @@ class Log
     public static function set($name = '', $log_handler = null)
     {
         $name = mb_strlen($name) ? $name : 0;
-        if (isset(self::$instances[$name])) {
-            $old = self::$instances[$name];
-        }
+
+        $old = self::$instances[$name] ?? null;
         self::$instances[$name] = new Log($log_handler);
         return $old;
     }
diff --git a/lib/classes/NotificationCenter.class.php b/lib/classes/NotificationCenter.class.php
index dce878e..1adf5f2 100644
--- a/lib/classes/NotificationCenter.class.php
+++ b/lib/classes/NotificationCenter.class.php
@@ -65,9 +65,10 @@ class NotificationCenter
                   };
         }
 
-        self::$observers[$event][] =
-            ['predicate' => $predicate ?: NULL,
-                  'observer'  => [$observer, $method]];
+        self::$observers[$event][] = [
+            'predicate' => $predicate ?? NULL,
+            'observer'  => [$observer, $method]
+        ];
     }
 
     /**
diff --git a/lib/classes/PageLayout.php b/lib/classes/PageLayout.php
index e40b22b..a8f3ffa 100644
--- a/lib/classes/PageLayout.php
+++ b/lib/classes/PageLayout.php
@@ -463,7 +463,7 @@ class PageLayout
      */
     public static function isHeaderEnabled()
     {
-        return self::$display_header && !$GLOBALS['_NOHEADER'];
+        return self::$display_header && empty($GLOBALS['_NOHEADER']);
     }
 
     /**
diff --git a/lib/classes/RangeConfig.class.php b/lib/classes/RangeConfig.class.php
index c384661..fc90434 100644
--- a/lib/classes/RangeConfig.class.php
+++ b/lib/classes/RangeConfig.class.php
@@ -52,7 +52,7 @@ class RangeConfig extends Config
             $range_id = $range_id->getRangeId();
         }
 
-        if (static::$instances[$range_id] === null) {
+        if (!isset(static::$instances[$range_id])) {
             static::$instances[$range_id] = new static($range_id);
         }
         return static::$instances[$range_id];
@@ -121,7 +121,7 @@ class RangeConfig extends Config
             }
             while ($row = $statement->fetch(PDO::FETCH_ASSOC)) {
                 $this->data[$row['field']] = $this->convertFromDatabase(
-                    $this->metadata[$row['field']]['type'],
+                    $this->metadata[$row['field']]['type'] ?? 'string',
                     $row['value'],
                     $row['field']
                 );
diff --git a/lib/classes/SemBrowse.class.php b/lib/classes/SemBrowse.class.php
index a60201a..af6b2f3 100644
--- a/lib/classes/SemBrowse.class.php
+++ b/lib/classes/SemBrowse.class.php
@@ -1169,7 +1169,7 @@ class SemBrowse {
         if (!$option['visible'] || $option['target'] != $target) {
             return null;
         }
-        if (!$option['url']) {
+        if (empty($option['url'])) {
             switch ($option_name) {
                 case 'courses':
                 case 'semtree':
diff --git a/lib/classes/SkipLinks.php b/lib/classes/SkipLinks.php
index b906ed5..455790f 100644
--- a/lib/classes/SkipLinks.php
+++ b/lib/classes/SkipLinks.php
@@ -83,7 +83,7 @@ class SkipLinks
      * @param integer $position the position of the link in the list
      * @param boolean $overwriteable false if position is not overwritable by another link
      */
-    public static function addIndex($name, $id, $position = null, $overwriteable = false)
+    public static function addIndex($name, $id, $position = null, $overwritable = false)
     {
         $url = '#' . $id;
         self::addLink($name, $url, $position, $overwriteable);
@@ -124,7 +124,7 @@ class SkipLinks
         if (isset(self::$position[$link['position']])) {
             return false;
         }
-        if (!$link['overwrite']) {
+        if (!isset($link['overwrite']) || !$link['overwrite']) {
             self::$position[$link['position']] = true;
         }
         return true;
diff --git a/lib/classes/StudipPDO.class.php b/lib/classes/StudipPDO.class.php
index 2153ecf..eb3b0df 100644
--- a/lib/classes/StudipPDO.class.php
+++ b/lib/classes/StudipPDO.class.php
@@ -178,12 +178,12 @@ class StudipPDO extends PDO
      * @param mixed     fetch mode parameter (see PDOStatement::setFetchMode)
      * @return object   PDOStatement object
      */
-    public function query($statement, $mode = NULL, $arg1 = NULL, $arg2 = NULL)
+    public function query($statement, $fetch_mode = NULL, ...$fetch_args)
     {
         $this->verify($statement);
 
         if (isset($mode)) {
-            $stmt = parent::query($statement, $mode, $arg1, $arg2);
+            $stmt = parent::query($statement, $mode, ...$fetchArgs);
         } else {
             $stmt = parent::query($statement);
         }
diff --git a/lib/classes/StudipPDOStatement.php b/lib/classes/StudipPDOStatement.php
index 51972ed..bb1af0d 100644
--- a/lib/classes/StudipPDOStatement.php
+++ b/lib/classes/StudipPDOStatement.php
@@ -117,6 +117,7 @@ class StudipPDOStatement implements IteratorAggregate
             }
         }
 
+        $emulate_prepare = false;
         // emulate prepared statement if necessary
         foreach ($this->params as $key => $param) {
             if ($param['type'] === StudipPDO::PARAM_ARRAY ||
diff --git a/lib/classes/URLHelper.php b/lib/classes/URLHelper.php
index a36cc10..e11d8de 100644
--- a/lib/classes/URLHelper.php
+++ b/lib/classes/URLHelper.php
@@ -169,8 +169,8 @@ class URLHelper
     {
         $link_params = $ignore_registered_params ? [] : self::$params;
 
-        list($url, $fragment) = explode('#', $url);
-        list($url, $query)    = explode('?', $url);
+        @list($url, $fragment) = explode('#', $url);
+        @list($url, $query)    = explode('?', $url);
 
         if ($url !== '') {
             $url = self::resolveURL($url);
diff --git a/lib/classes/WidgetContainer.php b/lib/classes/WidgetContainer.php
index 5287305..1b0578e 100644
--- a/lib/classes/WidgetContainer.php
+++ b/lib/classes/WidgetContainer.php
@@ -24,12 +24,12 @@ abstract class WidgetContainer
     public static function Get()
     {
         $class = get_called_class();
-        if (static::$instances[$class] === null) {
+        if (!isset(static::$instances[$class])) {
             static::$instances[$class] = new static;
         }
         return static::$instances[$class];
     }
-    
+
     /**
      * Private constructor to ensure that the singleton Get() method is always
      * used.
@@ -39,12 +39,12 @@ abstract class WidgetContainer
     protected function __construct()
     {
     }
-    
+
     /**
      * Contains the widgets of the container
      */
     protected $widgets = [];
-    
+
     /**
      * Add a widget to the container.
      *
@@ -75,9 +75,9 @@ abstract class WidgetContainer
     public function insertWidget(Widget $widget, $before_index, $index = null)
     {
         $index = $index ?: $this->guessIndex($widget);
-        
+
         $inserted = false;
-        
+
         $widgets = [];
         foreach ($this->widgets as $idx => $wdgt) {
             if ($idx === $before_index) {
@@ -96,7 +96,7 @@ abstract class WidgetContainer
         }
 
         $this->widgets = $widgets;
-        
+
         return $widget;
     }
 
@@ -151,7 +151,7 @@ abstract class WidgetContainer
      *
      * @param String $index Index/name of the widget to remove.
      * @throws Exception if the specified position is invalid
-     */ 
+     */
     public function removeWidget($index)
     {
         if (!isset($this->widgets[$index])) {
diff --git a/lib/classes/sidebar/LinkElement.php b/lib/classes/sidebar/LinkElement.php
index b38a145..29f0fd4 100644
--- a/lib/classes/sidebar/LinkElement.php
+++ b/lib/classes/sidebar/LinkElement.php
@@ -151,9 +151,7 @@ class LinkElement extends WidgetElement implements ArrayAccess
      */
     public function addClass($class)
     {
-        $this->attributes['class'] = $this->attributes['class']
-            ? $this->attributes['class'] . " " . $class
-            : $class;
+        $this->attributes['class'] = trim(($this->attributes['class'] ?? '') . " {$class}");
         return $this;
     }
 
diff --git a/lib/filesystem/HiddenFolder.php b/lib/filesystem/HiddenFolder.php
index 60a8cbd..107d35c 100644
--- a/lib/filesystem/HiddenFolder.php
+++ b/lib/filesystem/HiddenFolder.php
@@ -107,7 +107,7 @@ class HiddenFolder extends PermissionEnabledFolder
     public function __get($attribute)
     {
         if ($attribute === 'download_allowed') {
-            return $this->folderdata['data_content']['download_allowed'];
+            return $this->folderdata['data_content']['download_allowed'] ?? null;
         }
         return $this->folderdata[$attribute];
     }
diff --git a/lib/functions.php b/lib/functions.php
index bbed629..eced4fa 100644
--- a/lib/functions.php
+++ b/lib/functions.php
@@ -1007,7 +1007,7 @@ function format_help_url($keyword)
 {
     // all help urls need short language tag (de, en)
     $lang = 'de';
-    if ($_SESSION['_language']) {
+    if (isset($_SESSION['_language'])) {
         [$lang] = explode('_', $_SESSION['_language']);
     }
 
@@ -1428,6 +1428,8 @@ function get_route($route = '')
         $trails = explode('dispatch.php/', $route);
         $dispatcher = new StudipDispatcher();
         $pieces = explode('/', $trails[1]);
+
+        $trail = '';
         foreach ($pieces as $index => $piece) {
             $trail .= ($trail ? '/' : '') . $piece;
             if ($dispatcher->file_exists($trail . '.php')) {
diff --git a/lib/models/HelpTour.class.php b/lib/models/HelpTour.class.php
index d200eba..9bb815d 100644
--- a/lib/models/HelpTour.class.php
+++ b/lib/models/HelpTour.class.php
@@ -82,6 +82,9 @@ class HelpTour extends SimpleORMap
     public static function GetHelpbarTourData()
     {
         $visible_tours = [];
+        $active_tour_id = null;
+        $active_tour_step_nr = null;
+
         $route = get_route();
         $tours = HelpTour::getToursByRoute($route);
         foreach($tours as $index => $tour) {
@@ -100,7 +103,7 @@ class HelpTour extends SimpleORMap
             }
         }
         //if there is an active tour, initialize it
-        if ($_SESSION['active_tour']['tour_id']
+        if (isset($_SESSION['active_tour']['tour_id'])
             && ($_SESSION['active_tour']['last_route'] === $route
                 || $_SESSION['active_tour']['next_route'] === $route))
         {
diff --git a/lib/models/SimpleORMap.class.php b/lib/models/SimpleORMap.class.php
index 8397fa0..7983f0c 100644
--- a/lib/models/SimpleORMap.class.php
+++ b/lib/models/SimpleORMap.class.php
@@ -241,7 +241,7 @@ class SimpleORMap implements ArrayAccess, Countable, IteratorAggregate
         }
 
         foreach (['has_many', 'belongs_to', 'has_one', 'has_and_belongs_to_many'] as $type) {
-            if (is_array($config[$type])) {
+            if (isset($config[$type]) && is_array($config[$type])) {
                 foreach (array_keys($config[$type]) as $one) {
                     $config['relations'][$one] = null;
                 }
@@ -310,9 +310,9 @@ class SimpleORMap implements ArrayAccess, Countable, IteratorAggregate
 
         $config['known_slots'] = array_merge(
             array_keys($config['db_fields']),
-            array_keys($config['alias_fields'] ?: []),
-            array_keys($config['additional_fields'] ?: []),
-            array_keys($config['relations'] ?: [])
+            array_keys($config['alias_fields'] ?? []),
+            array_keys($config['additional_fields'] ?? []),
+            array_keys($config['relations'] ?? [])
         );
 
         foreach (array_map('strtolower', get_class_methods($class)) as $method) {
@@ -339,7 +339,7 @@ class SimpleORMap implements ArrayAccess, Countable, IteratorAggregate
             static::configure();
         }
 
-        return self::$config[static::class][$key];
+        return self::$config[static::class][$key] ?? null;
     }
 
     /**
@@ -1027,7 +1027,7 @@ class SimpleORMap implements ArrayAccess, Countable, IteratorAggregate
         if (!$options['class_name']) {
             throw new Exception('Option class_name not set for relation ' . $name);
         }
-        if (!$options['assoc_foreign_key']) {
+        if (!isset($options['assoc_foreign_key']) || !$options['assoc_foreign_key']) {
             if ($type === 'has_many' || $type === 'has_one') {
                 $options['assoc_foreign_key'] = $this->pk[0];
             } else if ($type === 'belongs_to') {
@@ -1062,14 +1062,14 @@ class SimpleORMap implements ArrayAccess, Countable, IteratorAggregate
                 throw new Exception("For relation " . $name . " assoc_foreign_key must be a name of a column");
             }
         }
-        if (!$options['assoc_func']) {
+        if (!isset($options['assoc_func']) || !$options['assoc_func']) {
             if ($type !== 'has_and_belongs_to_many') {
                 $options['assoc_func'] = $options['assoc_foreign_key'] === 'id' ? 'find' : 'findBy' . $options['assoc_foreign_key'];
             } else {
                 $options['assoc_func'] = 'findThru';
             }
         }
-        if (!$options['foreign_key']) {
+        if (!isset($options['foreign_key']) || !$options['foreign_key']) {
             $options['foreign_key'] = 'id';
         }
         if ($options['foreign_key'] instanceof Closure) {
@@ -1758,7 +1758,7 @@ class SimpleORMap implements ArrayAccess, Countable, IteratorAggregate
         $where_query = null;
         $pk_not_set = [];
         foreach ($this->pk as $key) {
-            $pk = $this->content_db[$key] ?: $this->content[$key];
+            $pk = $this->content_db[$key] ?? $this->content[$key] ?? null;
             if (isset($pk)) {
                 $where_query[] = "`{$this->db_table}`.`{$key}` = "  . DBManager::get()->quote($pk);
             } else {
@@ -2134,7 +2134,7 @@ class SimpleORMap implements ArrayAccess, Countable, IteratorAggregate
             }
             $params = $options['assoc_func_params_func'];
             if ($options['type'] === 'has_many') {
-                $records = function($record) use ($to_call, $params, $options) {$p = (array)$params($record); return call_user_func_array($to_call, array_merge(count($p) ? $p : [null], [$options['order_by']]));};
+                $records = function($record) use ($to_call, $params, $options) {$p = (array)$params($record); return call_user_func_array($to_call, array_merge(count($p) ? $p : [null], [$options['order_by'] ?? null]));};
                 $this->relations[$relation] = new SimpleORMapCollection($records, $options, $this);
             } elseif ($options['type'] === 'has_and_belongs_to_many') {
                 $records = function($record) use ($to_call, $params, $options) {$p = (array)$params($record); return call_user_func_array($to_call, array_merge(count($p) ? $p : [null], [$options]));};
diff --git a/lib/models/User.class.php b/lib/models/User.class.php
index db670fb..497b76e 100644
--- a/lib/models/User.class.php
+++ b/lib/models/User.class.php
@@ -535,7 +535,7 @@ class User extends AuthUserMd5 implements Range, PrivacyObject
             $format = 'full';
         }
 
-        $sql = $GLOBALS['_fullname_sql'][$format];
+        $sql = $GLOBALS['_fullname_sql'][$format] ?? null;
         if (!$sql || $format == 'no_title') {
             return $this->vorname . ' ' . $this->nachname;
         }
diff --git a/lib/navigation/BrowseNavigation.php b/lib/navigation/BrowseNavigation.php
index e178817..ea67233 100644
--- a/lib/navigation/BrowseNavigation.php
+++ b/lib/navigation/BrowseNavigation.php
@@ -24,6 +24,8 @@ class BrowseNavigation extends Navigation
     {
         global $user, $perm;
 
+        $courselink = false;
+
         // check if logged in
         if (is_object($user) && $user->id != 'nobody') {
             $coursetext = _('Veranstaltungen');
diff --git a/lib/navigation/Navigation.php b/lib/navigation/Navigation.php
index 45b5bbf..e019eb7 100644
--- a/lib/navigation/Navigation.php
+++ b/lib/navigation/Navigation.php
@@ -120,7 +120,7 @@ class Navigation implements IteratorAggregate
             }
 
             $subnav = $node->getSubNavigation();
-            $node = $subnav[$name];
+            $node = $subnav[$name] ?? null;
 
             if (!isset($node)) {
                 throw new InvalidArgumentException("navigation item '$path' not found");
diff --git a/lib/navigation/StartNavigation.php b/lib/navigation/StartNavigation.php
index 646ba4d..305767c 100644
--- a/lib/navigation/StartNavigation.php
+++ b/lib/navigation/StartNavigation.php
@@ -30,6 +30,7 @@ class StartNavigation extends Navigation
     {
         parent::initItem();
 
+        $news = 0;
         if (mb_stripos($_SERVER['REQUEST_URI'], "web_migrate.php") === false && is_object($GLOBALS['user']) && $GLOBALS['user']->id != 'nobody') {
             if (WidgetHelper::hasWidget($GLOBALS['user']->id, 'News')) {
                 $news = StudipNews::CountUnread();
diff --git a/lib/phplib/Seminar_Auth.class.php b/lib/phplib/Seminar_Auth.class.php
index db2828c..2cf0482 100644
--- a/lib/phplib/Seminar_Auth.class.php
+++ b/lib/phplib/Seminar_Auth.class.php
@@ -265,7 +265,9 @@ class Seminar_Auth
         $cfg = Config::GetInstance();
         //check if the user got kicked meanwhile, or if user is locked out
         if ($this->auth['uid'] && !in_array($this->auth['uid'], ['form', 'nobody'])) {
-            $user = $GLOBALS['user']->id == $this->auth['uid'] ? $GLOBALS['user'] : User::find($this->auth['uid']);
+            $user = (isset($GLOBALS['user']) && $GLOBALS['user']->id == $this->auth['uid'])
+                  ? $GLOBALS['user']
+                  : User::find($this->auth['uid']);
             $exp_d = $user->username ? UserConfig::get($user->id)->EXPIRATION_DATE : 0;
             if (!$user->username || $user->locked || ($exp_d > 0 && $exp_d < time())) {
                 $this->unauth();
diff --git a/lib/phplib/Seminar_Perm.class.php b/lib/phplib/Seminar_Perm.class.php
index e846983..ed12b06 100644
--- a/lib/phplib/Seminar_Perm.class.php
+++ b/lib/phplib/Seminar_Perm.class.php
@@ -216,7 +216,7 @@ class Seminar_Perm
     {
 
         $pageperm = $this->permissions[$perm];
-        $userperm = $this->permissions[$this->get_studip_perm($range_id, $user_id)];
+        $userperm = $this->permissions[$this->get_studip_perm($range_id, $user_id)] ?? 0;
 
         return $pageperm <= $userperm;
     }
diff --git a/lib/phplib/Seminar_Session.class.php b/lib/phplib/Seminar_Session.class.php
index 422419b..a5bc592 100644
--- a/lib/phplib/Seminar_Session.class.php
+++ b/lib/phplib/Seminar_Session.class.php
@@ -207,7 +207,7 @@ class Seminar_Session
             $this->that_class = 'CT_Cache';
         }
         $this->cookie_path = $this->cookie_path ?: $GLOBALS['CANONICAL_RELATIVE_PATH_STUDIP'];
-        $this->cookie_secure = $_SERVER['HTTPS'] === 'on';
+        $this->cookie_secure = isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] === 'on';
         $this->name(get_class($this));
     }
 
diff --git a/lib/phplib/page_open.php b/lib/phplib/page_open.php
index 5e63897..48de189 100644
--- a/lib/phplib/page_open.php
+++ b/lib/phplib/page_open.php
@@ -30,7 +30,7 @@ function page_open($feature) {
             # the perm feature depends on auth and sess
             if (isset($feature["perm"])) {
 
-                if (!is_object($GLOBALS['perm'])) {
+                if (!isset($GLOBALS['perm']) || !is_object($GLOBALS['perm'])) {
                     $GLOBALS['perm'] = new $feature["perm"];
                 }
             }
@@ -38,7 +38,7 @@ function page_open($feature) {
             # the user feature depends on auth and sess
             if (isset($feature["user"])) {
 
-                if (!is_object($GLOBALS['user'])) {
+                if (!isset($GLOBALS['user']) || !is_object($GLOBALS['user'])) {
 
                     $GLOBALS['user'] = new $feature["user"]($GLOBALS['auth']->auth["uid"]);
                 }
diff --git a/lib/plugins/engine/PluginManager.class.php b/lib/plugins/engine/PluginManager.class.php
index 1745e50..659126c 100644
--- a/lib/plugins/engine/PluginManager.class.php
+++ b/lib/plugins/engine/PluginManager.class.php
@@ -568,7 +568,7 @@ class PluginManager
             $plugin = $plugin_class->newInstance();
         }
 
-        return $this->plugin_cache[$class] = $plugin;
+        return $this->plugin_cache[$class] = $plugin ?? null;
     }
 
     /**
@@ -587,7 +587,7 @@ class PluginManager
             $plugin = $this->getCachedPlugin($plugin_info);
         }
 
-        return $plugin;
+        return $plugin ?? null;
     }
 
     /**
diff --git a/templates/footer.php b/templates/footer.php
index 0ea313b..28731fb 100644
--- a/templates/footer.php
+++ b/templates/footer.php
@@ -41,7 +41,7 @@
             <li>
             <a
             <? if (is_internal_url($url = $nav->getURL())) : ?>
-                href="<?= URLHelper::getLink($url, $header_template->link_params) ?>"
+                href="<?= URLHelper::getLink($url, $header_template->link_params ?? []) ?>"
             <? else: ?>
                 href="<?= htmlReady($url) ?>" target="_blank" rel="noopener noreferrer"
             <? endif ?>
diff --git a/templates/header-navigation-item.php b/templates/header-navigation-item.php
index a163140..ba70ce5 100644
--- a/templates/header-navigation-item.php
+++ b/templates/header-navigation-item.php
@@ -2,7 +2,7 @@
 $attributes = $nav->getLinkAttributes();
 
 $image_attributes = $nav->getImage()->getAttributes();
-$attributes['title'] = $image_attributes['title'];
+$attributes['title'] = $image_attributes['title'] ?? null;
 
 // Add badge number to link attributes
 if ($nav->getBadgeNumber()) {
diff --git a/templates/header.php b/templates/header.php
index 8f29921..efaedd8 100644
--- a/templates/header.php
+++ b/templates/header.php
@@ -85,7 +85,7 @@ if (isset($_COOKIE['navigation-length'])) {
                             $alert = true;
                         }
                     } ?>
-                    <div id="notification_marker"<?= $alert ? ' class="alert"' : "" ?> title="<?= _("Benachrichtigungen") ?>" data-lastvisit="<?= $lastvisit ?>">
+                    <div id="notification_marker"<?= $alert ?? false ? ' class="alert"' : "" ?> title="<?= _("Benachrichtigungen") ?>" data-lastvisit="<?= $lastvisit ?>">
                         <?= count($notifications) ?>
                     </div>
                     <div class="list below" id="notification_list">
diff --git a/templates/layouts/base.php b/templates/layouts/base.php
index 6fde8c9..409f331 100644
--- a/templates/layouts/base.php
+++ b/templates/layouts/base.php
@@ -1,5 +1,5 @@
 <?php
-NotificationCenter::postNotification('PageWillRender', $body_id ? : PageLayout::getBodyElementId());
+NotificationCenter::postNotification('PageWillRender', $body_id ?? PageLayout::getBodyElementId());
 $navigation = PageLayout::getTabNavigation();
 $tab_root_path = PageLayout::getTabNavigationPath();
 if ($navigation) {
@@ -98,7 +98,7 @@ $getInstalledLanguages = function () {
     </script>
 </head>
 
-<body id="<?= $body_id ?: PageLayout::getBodyElementId() ?>" <? if (SkipLinks::isEnabled()) echo 'class="enable-skiplinks"'; ?>>
+<body id="<?= $body_id ?? PageLayout::getBodyElementId() ?>" <? if (SkipLinks::isEnabled()) echo 'class="enable-skiplinks"'; ?>>
 <div id="layout_wrapper">
     <? SkipLinks::insertContainer() ?>
     <? SkipLinks::addIndex(_('Hauptinhalt'), 'layout_content', 100, true) ?>
@@ -138,7 +138,7 @@ $getInstalledLanguages = function () {
         <? endif ?>
 
         <? if (PageLayout::isHeaderEnabled() /*&& isset($navigation)*/) : ?>
-            <?= $this->render_partial('tabs', compact('navigation', 'membership')) ?>
+            <?= $this->render_partial('tabs', @compact('navigation', 'membership')) ?>
         <? endif; ?>
         </nav>
     <? endif; ?>
@@ -199,4 +199,4 @@ $getInstalledLanguages = function () {
     </a>
 </body>
 </html>
-<?php NotificationCenter::postNotification('PageDidRender', $body_id ? : PageLayout::getBodyElementId());
+<?php NotificationCenter::postNotification('PageDidRender', $body_id ?? PageLayout::getBodyElementId());
diff --git a/templates/sidebar/time-range-filter.php b/templates/sidebar/time-range-filter.php
index 1e343b0..cfec69c 100644
--- a/templates/sidebar/time-range-filter.php
+++ b/templates/sidebar/time-range-filter.php
@@ -2,12 +2,12 @@
     <?= CSRFProtection::tokenTag() ?>
     <label>
         <?= _('Dateien neuer als') ?>:
-        <input type="text" name="begin" value="<?= htmlReady($begin) ?>"
+        <input type="text" name="begin" value="<?= htmlReady($begin ?? '') ?>"
                class="has-date-picker">
     </label>
     <label>
         <?= _('Dateien älter als') ?>:
-        <input type="text" name="end" value="<?= htmlReady($end) ?>"
+        <input type="text" name="end" value="<?= htmlReady($end ?? '') ?>"
                class="has-date-picker submit-on-change">
     </label>
     <? if ($course_options) : ?>
diff --git a/templates/sidebar/widget-layout.php b/templates/sidebar/widget-layout.php
index de3f82f..2140188 100644
--- a/templates/sidebar/widget-layout.php
+++ b/templates/sidebar/widget-layout.php
@@ -1,9 +1,9 @@
 <div class="<?= $base_class ?>-widget <? if ($layout_css_classes && is_array($layout_css_classes)) echo htmlReady(implode(' ', $layout_css_classes)); ?>"
-    <? if ($id) printf('id="%s"', htmlReady($id)) ?>
-    <? if ($style) printf('style="%s"', $style) ?>>
+    <? if ($id ?? false) printf('id="%s"', htmlReady($id)) ?>
+    <? if ($style ?? false) printf('style="%s"', $style) ?>>
 <? if ($title): ?>
     <div class="<?= $base_class ?>-widget-header">
-    <? if ($extra): ?>
+    <? if ($extra ?? false): ?>
         <div class="<?= $base_class ?>-widget-extra"><?= $extra ?></div>
     <? endif; ?>
         <?= htmlReady($title) ?>