MDL-76362 various: Avoid passing nulls to functions that don't allow nulls

PHP 8.1 is more strict on the parameter type. Functions such as trim(), strlen(), str_replace(), etc
show notice when null is passed as an argument

admin/tool/analytics/classes/output/helper.php

@@ -45,7 +45,7 @@ class helper {
         // Form field is PARAM_ALPHANUMEXT and we are sending fully qualified class names
         // as option names, but replacing the backslash for a string that is really unlikely
         // to ever be part of a class name.
-        return str_replace('\\', '__', $class);
+        return str_replace('\\', '__', $class ?? '');
     }
 
     /**

admin/tool/behat/cli/run.php

@@ -437,7 +437,7 @@ function print_combined_run_output($processes, $stoponfail = false) {
                         $process->stop(0);
                     }
 
-                    $strlentoprint = strlen($update);
+                    $strlentoprint = strlen($update ?? '');
 
                     // If not enough dots printed on line then just print.
                     if ($strlentoprint < $remainingprintlen) {

admin/tool/brickfield/classes/manager.php

@@ -205,7 +205,7 @@ class manager {
      * @return string
      */
     public static function get_contenthash(?string $content = null): string {
-        return sha1($content);
+        return sha1($content ?? '');
     }
 
     /**

admin/tool/dataprivacy/classes/data_registry.php

@@ -47,7 +47,7 @@ class data_registry {
      * @return string[]
      */
     public static function var_names_from_context($classname, $pluginname = '') {
-        $pluginname = trim($pluginname);
+        $pluginname = trim($pluginname ?? '');
         if (!empty($pluginname)) {
             $categoryvar = $classname . '_' . $pluginname . '_category';
             $purposevar = $classname . '_' . $pluginname . '_purpose';

admin/tool/dataprivacy/classes/external/purpose_exporter.php

@@ -109,7 +109,7 @@ class purpose_exporter extends persistent_exporter {
         $values['formattedlawfulbases'] = $formattedbases;
 
         $formattedsensitivereasons = [];
-        $sensitivereasons = explode(',', $this->persistent->get('sensitivedatareasons'));
+        $sensitivereasons = explode(',', $this->persistent->get('sensitivedatareasons') ?? '');
         if (!empty($sensitivereasons)) {
             foreach ($sensitivereasons as $reason) {
                 if (empty(trim($reason))) {

admin/tool/log/classes/helper/reader.php

@@ -74,10 +74,10 @@ trait reader {
      * @return mixed Decoded value
      */
     public static function decode_other(?string $other) {
-        if ($other === 'N;' || preg_match('~^.:~', $other)) {
+        if ($other === 'N;' || preg_match('~^.:~', $other ?? '')) {
             return unserialize($other);
         } else {
-            return json_decode($other, true);
+            return json_decode($other ?? '', true);
         }
     }
 

admin/tool/moodlenet/classes/local/remote_resource.php

@@ -60,8 +60,8 @@ class remote_resource {
     public function __construct(\curl $curl, url $url, \stdClass $metadata) {
         $this->curl = $curl;
         $this->url = $url;
-        $this->filename = pathinfo($this->url->get_path(), PATHINFO_FILENAME);
+        $this->filename = pathinfo($this->url->get_path() ?? '', PATHINFO_FILENAME);
-        $this->extension = pathinfo($this->url->get_path(), PATHINFO_EXTENSION);
+        $this->extension = pathinfo($this->url->get_path() ?? '', PATHINFO_EXTENSION);
         $this->metadata = $metadata;
     }
 

analytics/classes/model.php

@@ -1828,7 +1828,7 @@ class model {
      */
     public function get_name() {
 
-        if (trim($this->model->name) === '') {
+        if (trim($this->model->name ?? '') === '') {
             return $this->get_target()->get_name();
 
         } else {

backup/moodle2/backup_custom_fields.php

@@ -197,7 +197,7 @@ class encrypted_final_element extends backup_final_element {
         $iv = self::generate_encryption_random_key(openssl_cipher_iv_length(backup::CIPHER));
 
         // Everything is ready, let's encrypt and prepend the 1-shot iv.
-        $value = $iv . openssl_encrypt($value, backup::CIPHER, $this->key, OPENSSL_RAW_DATA, $iv);
+        $value = $iv . openssl_encrypt($value ?? '', backup::CIPHER, $this->key, OPENSSL_RAW_DATA, $iv);
 
         // Calculate the hmac of the value (iv + encrypted) and prepend it.
         $hmac = hash_hmac('sha256', $value, $this->key, true);

backup/util/helper/restore_decode_processor.class.php

@@ -170,7 +170,7 @@ class restore_decode_processor {
      */
     protected function precheck_content($content) {
         // Look for $@ in content (all interlinks contain that)
-        return (strpos($content, '$@') === false) ? false : $content;
+        return (strpos($content ?? '', '$@') === false) ? false : $content;
     }
 }
 

backup/util/helper/restore_structure_parser_processor.class.php

@@ -55,7 +55,7 @@ class restore_structure_parser_processor extends grouped_parser_processor {
             return '';
         } else if (is_numeric($cdata)) {
             return $cdata;
-        } else if (strlen($cdata) < 32) { // Impossible to have one link in 32cc
+        } else if (strlen($cdata ?? '') < 32) { // Impossible to have one link in 32cc
             return $cdata;                // (http://10.0.0.1/file.php/1/1.jpg, http://10.0.0.1/mod/url/view.php?id=)
         }
 

backup/util/xml/output/xml_output.class.php

@@ -107,7 +107,7 @@ abstract class xml_output {
         if (!$this->running) {
             throw new xml_output_exception('xml_output_not_started');
         }
-        $lenc = strlen($content); // Get length in bytes
+        $lenc = strlen($content ?? ''); // Get length in bytes
         if ($lenc == 0) { // 0 length contents, nothing to do
             return;
         }

backup/util/xml/xml_writer.class.php

@@ -260,7 +260,7 @@ class xml_writer {
      * ignores the rest of characters. Also normalize linefeeds and return chars.
      */
     protected function xml_safe_utf8($content) {
-        $content = preg_replace('/[\x-\x8\xb-\xc\xe-\x1f\x7f]/is','', $content); // clean CTRL chars
+        $content = preg_replace('/[\x-\x8\xb-\xc\xe-\x1f\x7f]/is','', $content ?? ''); // clean CTRL chars
         $content = preg_replace("/\r\n|\r/", "\n", $content); // Normalize line&return=>line
         return $content;
     }

badges/classes/backpack_api_mapping.php

@@ -170,8 +170,8 @@ class backpack_api_mapping {
         $url = str_replace('[SCHEME]', $urlscheme, $url);
         $url = str_replace('[HOST]', $urlhost, $url);
         $url = str_replace('[URL]', $apiurl, $url);
-        $url = str_replace('[PARAM1]', $param1, $url);
+        $url = str_replace('[PARAM1]', $param1 ?? '', $url);
-        $url = str_replace('[PARAM2]', $param2, $url);
+        $url = str_replace('[PARAM2]', $param2 ?? '', $url);
 
         return $url;
     }

cache/classes/helper.php

@@ -634,7 +634,7 @@ class cache_helper {
      */
     public static function hash_key($key, cache_definition $definition) {
         if ($definition->uses_simple_keys()) {
-            if (debugging() && preg_match('#[^a-zA-Z0-9_]#', $key)) {
+            if (debugging() && preg_match('#[^a-zA-Z0-9_]#', $key ?? '')) {
                 throw new coding_exception('Cache definition '.$definition->get_id().' requires simple keys. Invalid key provided.', $key);
             }
             // We put the key first so that we can be sure the start of the key changes.

course/classes/external/course_summary_exporter.php

@@ -64,7 +64,7 @@ class course_summary_exporter extends \core\external\exporter {
         if ($progress === 0 || $progress > 0) {
             $hasprogress = true;
         }
-        $progress = floor($progress);
+        $progress = floor($progress ?? 0);
         $coursecategory = \core_course_category::get($this->data->category, MUST_EXIST, true);
         return array(
             'fullnamedisplay' => get_course_display_name_for_list($this->data),

course/format/classes/base.php

@@ -618,7 +618,7 @@ abstract class base {
         $course = $this->get_course();
         try {
             $sectionpreferences = (array) json_decode(
-                get_user_preferences('coursesectionspreferences_' . $course->id, null, $USER->id)
+                get_user_preferences('coursesectionspreferences_' . $course->id, null, $USER->id) ?? ''
             );
             if (empty($sectionpreferences)) {
                 $sectionpreferences = [];

course/format/classes/output/local/content/frontpagesection.php

@@ -84,7 +84,7 @@ class frontpagesection implements named_templatable, renderable {
         $sectionoutput = new $this->sectionclass($format, $section);
         $sectionoutput->hide_controls();
 
-        if (trim($section->name) == '') {
+        if (trim($section->name ?? '') == '') {
             $sectionoutput->hide_title();
         }
 

course/user.php

@@ -148,7 +148,7 @@ switch ($mode) {
             $coursenode->collapse = true;
             $coursenode->make_inactive();
 
-            if (!preg_match('/^user\d{0,}$/', $activenode->key)) { // No user name found.
+            if (!preg_match('/^user\d{0,}$/', $activenode->key ?? '')) { // No user name found.
                 $userurl = new moodle_url('/user/view.php', array('id' => $user->id, 'course' => $course->id));
                 // Add the user name.
                 $usernode = $activenode->add(fullname($user), $userurl, navigation_node::TYPE_SETTING);

customfield/classes/field.php

@@ -92,6 +92,6 @@ class field extends persistent {
      * @return array
      */
     protected function get_configdata() : array {
-        return json_decode($this->raw_get('configdata'), true) ?? array();
+        return json_decode($this->raw_get('configdata') ?? '', true) ?? array();
     }
 }

enrol/lti/classes/data_connector.php

@@ -997,7 +997,7 @@ class data_connector extends DataConnector {
         $consumer->consumerName = $record->consumername;
         $consumer->consumerVersion = $record->consumerversion;
         $consumer->consumerGuid = $record->consumerguid;
-        $consumer->profile = json_decode($record->profile);
+        $consumer->profile = json_decode($record->profile ?? '');
         $consumer->toolProxy = $record->toolproxy;
         $settings = unserialize($record->settings);
         if (!is_array($settings)) {

enrol/lti/classes/local/ltiadvantage/lib/http_client.php

@@ -78,8 +78,8 @@ class http_client implements IHttpClient {
         if (!$this->curlclient->get_errno() && !$this->curlclient->error) {
             // No errors, so format the response.
             $headersize = $info['header_size'];
-            $resheaders = substr($res, 0, $headersize);
+            $resheaders = substr($res ?? '', 0, $headersize);
-            $resbody = substr($res, $headersize);
+            $resbody = substr($res ?? '', $headersize);
             $headerlines = array_filter(explode("\r\n", $resheaders));
             $parsedresponseheaders = [
                 'httpstatus' => array_shift($headerlines)

grade/report/singleview/classes/local/screen/user.php

@@ -410,7 +410,7 @@ class user extends tablelike implements selectable_items {
 
                 $isscale = ($gradeitem->gradetype == GRADE_TYPE_SCALE);
 
-                $empties = (trim($value) === '' or ($isscale and $value == -1));
+                $empties = (trim($value ?? '') === '' or ($isscale and $value == -1));
 
                 if ($filter == 'all' or $empties) {
                     $data->$varname = ($isscale and empty($insertvalue)) ?

h5p/ajax.php

@@ -59,7 +59,7 @@ switch ($action) {
 
         // Normalise Moodle language using underscore, as opposed to H5P which uses dash.
         $language = optional_param('default-language', null, PARAM_RAW);
-        $language = clean_param(str_replace('-', '_', $language), PARAM_LANG);
+        $language = clean_param(str_replace('-', '_', $language ?? ''), PARAM_LANG);
 
         if (!empty($name)) {
             $editor->ajax->action(H5PEditorEndpoints::SINGLE_LIBRARY, $name,

h5p/classes/api.php

@@ -163,7 +163,7 @@ class api {
             unset($library->major_version);
             $library->minorVersion = (int) $library->minorversion;
             unset($library->minorversion);
-            $library->metadataSettings = json_decode($library->metadatasettings);
+            $library->metadataSettings = json_decode($library->metadatasettings ?? '');
 
             // If we already add this library means that it is an old version,as the previous query was sorted by version.
             if (isset($added[$library->name])) {

h5p/classes/editor_framework.php

@@ -274,7 +274,7 @@ class editor_framework implements H5peditorStorage {
                 if ($details) {
                     $library->title = $details->title;
                     $library->runnable = $details->runnable;
-                    $library->metadataSettings = json_decode($details->metadatasettings);
+                    $library->metadataSettings = json_decode($details->metadatasettings ?? '');
                     $library->example = $details->example;
                     $library->tutorial = $details->tutorial;
                     $librariesin[] = $library;

lib/accesslib.php

@@ -4560,7 +4560,7 @@ function role_get_name(stdClass $role, $context = null, $rolenamedisplay = ROLEN
     }
 
     if ($rolenamedisplay == ROLENAME_ALIAS) {
-        if ($coursecontext and trim($role->coursealias) !== '') {
+        if ($coursecontext and trim($role->coursealias ?? '') !== '') {
             return format_string($role->coursealias, true, array('context'=>$coursecontext));
         } else {
             return $original;
@@ -4568,7 +4568,7 @@ function role_get_name(stdClass $role, $context = null, $rolenamedisplay = ROLEN
     }
 
     if ($rolenamedisplay == ROLENAME_BOTH) {
-        if ($coursecontext and trim($role->coursealias) !== '') {
+        if ($coursecontext and trim($role->coursealias ?? '') !== '') {
             return format_string($role->coursealias, true, array('context'=>$coursecontext)) . " ($original)";
         } else {
             return $original;

lib/behat/extension/Moodle/BehatExtension/Locator/FilesystemSkipPassedListLocator.php

@@ -64,7 +64,7 @@ final class FilesystemSkipPassedListLocator implements SpecificationLocator {
      * @return SpecificationIterator
      */
     public function locateSpecifications(Suite $suite, $locator) {
-        if (!is_file($locator) || 'passed' !== pathinfo($locator, PATHINFO_EXTENSION)) {
+        if (!$locator || !is_file($locator) || 'passed' !== pathinfo($locator, PATHINFO_EXTENSION)) {
             return new NoSpecificationsIterator($suite);
         }
 

lib/classes/component.php

@@ -1004,7 +1004,7 @@ $cache = '.var_export($cache, true).';
             return (bool)preg_match('/^[a-z][a-z0-9]*$/', $pluginname);
 
         } else {
-            return (bool)preg_match('/^[a-z](?:[a-z0-9_](?!__))*[a-z0-9]+$/', $pluginname);
+            return (bool)preg_match('/^[a-z](?:[a-z0-9_](?!__))*[a-z0-9]+$/', $pluginname ?? '');
         }
     }
 

lib/classes/date.php

@@ -319,7 +319,7 @@ class core_date {
         if (!defined('PHPUNIT_TEST')) {
             throw new coding_exception('core_date::phpunit_override_default_php_timezone() must be used only from unit tests');
         }
-        $result = timezone_open($tz); // This triggers error if $tz invalid.
+        $result = timezone_open($tz ?? ''); // This triggers error if $tz invalid.
         if ($result !== false) {
             self::$defaultphptimezone = $tz;
         } else {

lib/dml/pgsql_native_moodle_database.php

@@ -594,7 +594,7 @@ class pgsql_native_moodle_database extends moodle_database {
 
             } else if (preg_match('/int(\d)/i', $rawcolumn->type, $matches)) {
                 $info->type = 'int';
-                if (strpos($rawcolumn->adsrc, 'nextval') === 0) {
+                if (strpos($rawcolumn->adsrc ?? '', 'nextval') === 0) {
                     $info->primary_key   = true;
                     $info->meta_type     = 'R';
                     $info->unique        = true;

lib/evalmath/evalmath.class.php

@@ -260,7 +260,7 @@ class EvalMath {
                     if (is_null($o2)) return $this->trigger(get_string('unexpectedclosingbracket', 'mathslib'));
                     else $output[] = $o2;
                 }
-                if (preg_match('/^('.self::$namepat.')\($/', $stack->last(2), $matches)) { // did we just close a function?
+                if (preg_match('/^('.self::$namepat.')\($/', $stack->last(2) ?? '', $matches)) { // did we just close a function?
                     $fnn = $matches[1]; // get the function name
                     $arg_count = $stack->pop(); // see how many arguments there were (cleverly stored on the stack, thank you)
                     $fn = $stack->pop();

lib/evalmath/readme_moodle.txt

@@ -13,6 +13,7 @@ Our changes:
 * added round, ceil and floor functions.
 * EvalMath::EvalMath() changed to EvalMath::__construct() and there is a new EvalMath::EvalMath
   function to maintain backwards compatibility
+* Ensure a string is passed to preg_match in EvalMath::nfx.
 
 To see all changes diff against version 1.1, available from:
 http://www.phpclasses.org/browse/package/2695.html
@@ -27,4 +28,4 @@ Changes by Stefan Erlachner, Thomas Niedermaier (MDL-64414):
 * add function or:
 e.g. if (or(condition_1, condition_2, ... condition_n))
 * add function and:
-e.g. if (and(condition_1, condition_2, ... condition_n))
+e.g. if (and(condition_1, condition_2, ... condition_n))

lib/filebrowser/file_info.php

@@ -100,7 +100,7 @@ abstract class file_info {
      */
     protected function build_search_files_sql($extensions, $prefix = null) {
         global $DB;
-        if (strlen($prefix)) {
+        if (strlen($prefix ?? '')) {
             $prefix = $prefix.'.';
         } else {
             $prefix = '';

lib/filelib.php

@@ -518,9 +518,9 @@ function file_rewrite_pluginfile_urls($text, $file, $contextid, $component, $fil
     }
 
     if (!empty($options['reverse'])) {
-        return str_replace($baseurl, '@@PLUGINFILE@@/', $text);
+        return str_replace($baseurl, '@@PLUGINFILE@@/', $text ?? '');
     } else {
-        return str_replace('@@PLUGINFILE@@/', $baseurl, $text);
+        return str_replace('@@PLUGINFILE@@/', $baseurl, $text ?? '');
     }
 }
 
@@ -785,7 +785,7 @@ function file_get_drafarea_files($draftitemid, $filepath = '/') {
             }
             // find the file this draft file was created from and count all references in local
             // system pointing to that file
-            $source = @unserialize($file->get_source());
+            $source = @unserialize($file->get_source() ?? '');
             if (isset($source->original)) {
                 $item->refcount = $fs->search_references_count($source->original);
             }
@@ -905,7 +905,7 @@ function file_get_submitted_draft_itemid($elname) {
  * @return stored_file
  */
 function file_restore_source_field_from_draft_file($storedfile) {
-    $source = @unserialize($storedfile->get_source());
+    $source = @unserialize($storedfile->get_source() ?? '');
     if (!empty($source)) {
         if (is_object($source)) {
             $restoredsource = $source->source;
@@ -1199,7 +1199,7 @@ function file_save_draft_area_files($draftitemid, $contextid, $component, $filea
             // Let's check if we can update this file or we need to delete and create.
             if ($newfile->is_directory()) {
                 // Directories are always ok to just update.
-            } else if (($source = @unserialize($newfile->get_source())) && isset($source->original)) {
+            } else if (($source = @unserialize($newfile->get_source() ?? '')) && isset($source->original)) {
                 // File has the 'original' - we need to update the file (it may even have not been changed at all).
                 $original = file_storage::unpack_reference($source->original);
                 if ($original['filename'] !== $oldfile->get_filename() || $original['filepath'] !== $oldfile->get_filepath()) {
@@ -1235,7 +1235,7 @@ function file_save_draft_area_files($draftitemid, $contextid, $component, $filea
             // Field files.source for draftarea files contains serialised object with source and original information.
             // We only store the source part of it for non-draft file area.
             $newsource = $newfile->get_source();
-            if ($source = @unserialize($newfile->get_source())) {
+            if ($source = @unserialize($newfile->get_source() ?? '')) {
                 $newsource = $source->source;
             }
             if ($oldfile->get_source() !== $newsource) {
@@ -1269,7 +1269,7 @@ function file_save_draft_area_files($draftitemid, $contextid, $component, $filea
         // the size and subdirectory tests are extra safety only, the UI should prevent it
         foreach ($newhashes as $file) {
             $file_record = array('contextid'=>$contextid, 'component'=>$component, 'filearea'=>$filearea, 'itemid'=>$itemid, 'timemodified'=>time());
-            if ($source = @unserialize($file->get_source())) {
+            if ($source = @unserialize($file->get_source() ?? '')) {
                 // Field files.source for draftarea files contains serialised object with source and original information.
                 // We only store the source part of it for non-draft file area.
                 $file_record['source'] = $source->source;
@@ -1478,7 +1478,7 @@ function format_postdata_for_curlcall($postdata) {
                 $currentdata = urlencode($k);
                 format_array_postdata_for_curlcall($v, $currentdata, $data);
             }  else {
-                $data[] = urlencode($k).'='.urlencode($v);
+                $data[] = urlencode($k).'='.urlencode($v ?? '');
             }
         }
         $convertedpostdata = implode('&', $data);
@@ -1771,7 +1771,7 @@ function mimeinfo($element, $filename) {
     $mimeinfo = & get_mimetypes_array();
     static $iconpostfixes = array(256=>'-256', 128=>'-128', 96=>'-96', 80=>'-80', 72=>'-72', 64=>'-64', 48=>'-48', 32=>'-32', 24=>'-24', 16=>'');
 
-    $filetype = strtolower(pathinfo($filename, PATHINFO_EXTENSION));
+    $filetype = strtolower(pathinfo($filename ?? '', PATHINFO_EXTENSION));
     if (empty($filetype)) {
         $filetype = 'xxx'; // file without extension
     }
@@ -2028,8 +2028,8 @@ function get_mimetype_description($obj, $capitalise=false) {
     }
 
     // MIME types may include + symbol but this is not permitted in string ids.
-    $safemimetype = str_replace('+', '_', $mimetype);
+    $safemimetype = str_replace('+', '_', $mimetype ?? '');
-    $safemimetypestr = str_replace('+', '_', $mimetypestr);
+    $safemimetypestr = str_replace('+', '_', $mimetypestr ?? '');
     $customdescription = mimeinfo('customdescription', $filename);
     if ($customdescription) {
         // Call format_string on the custom description so that multilang
@@ -2919,7 +2919,7 @@ function file_overwrite_existing_draftfile(stored_file $newfile, stored_file $ex
 
     $fs = get_file_storage();
     // Remember original file source field.
-    $source = @unserialize($existingfile->get_source());
+    $source = @unserialize($existingfile->get_source() ?? '');
     // Remember the original sortorder.
     $sortorder = $existingfile->get_sortorder();
     if ($newfile->is_external_file()) {
@@ -2943,7 +2943,7 @@ function file_overwrite_existing_draftfile(stored_file $newfile, stored_file $ex
     $newfile = $fs->create_file_from_storedfile($newfilerecord, $newfile);
     // Preserve original file location (stored in source field) for handling references.
     if (isset($source->original)) {
-        if (!($newfilesource = @unserialize($newfile->get_source()))) {
+        if (!($newfilesource = @unserialize($newfile->get_source() ?? ''))) {
             $newfilesource = new stdClass();
         }
         $newfilesource->original = $source->original;

lib/filestorage/file_storage.php

@@ -1800,7 +1800,7 @@ class file_storage {
                 // the latter of which can go to 100, we need to make sure that quality here is
                 // in a safe range or PHP WILL CRASH AND DIE. You have been warned.
                 $quality = $quality > 9 ? (int)(max(1.0, (float)$quality / 100.0) * 9.0) : $quality;
-                imagepng($img, NULL, $quality, NULL);
+                imagepng($img, NULL, $quality, PNG_NO_FILTER);
                 break;
 
             default:
@@ -2462,6 +2462,6 @@ class file_storage {
      * @return  string The file's content hash
      */
     public static function hash_from_string($content) {
-        return sha1($content);
+        return sha1($content ?? '');
     }
 }

lib/filestorage/file_system_filedir.php

@@ -426,7 +426,7 @@ class file_system_filedir extends file_system {
 
         $contenthash = file_storage::hash_from_string($content);
         // Binary length.
-        $filesize = strlen($content);
+        $filesize = strlen($content ?? '');
 
         $hashpath = $this->get_fulldir_from_hash($contenthash);
         $hashfile = $this->get_local_path_from_hash($contenthash, false);

lib/filestorage/tgz_extractor.php

@@ -493,7 +493,7 @@ class tgz_extractor {
                 unlink($this->currentfile);
             } else {
                 // For index file, get number of files and delete temp file.
-                $contents = file_get_contents($this->currentfile, null, null, null, 128);
+                $contents = file_get_contents($this->currentfile, false, null, 0, 128);
                 $matches = array();
                 if (preg_match('~^' . preg_quote(tgz_packer::ARCHIVE_INDEX_COUNT_PREFIX) .
                         '([0-9]+)~', $contents, $matches)) {

lib/form/classes/filetypes_util.php

@@ -62,7 +62,7 @@ class filetypes_util {
      */
     public function normalize_file_types($types) {
 
-        if ($types === '') {
+        if ($types === '' || $types === null) {
             return [];
         }
 

lib/form/passwordunmask.php

@@ -86,7 +86,7 @@ class MoodleQuickForm_passwordunmask extends MoodleQuickForm_password {
      */
     public function export_for_template(renderer_base $output) {
         $context = parent::export_for_template($output);
-        $context['valuechars'] = array_fill(0, strlen($context['value']), 'x');
+        $context['valuechars'] = array_fill(0, strlen($context['value'] ?? ''), 'x');
 
         return $context;
     }

lib/formslib.php

@@ -3261,7 +3261,7 @@ class MoodleQuickForm_Renderer extends HTML_QuickForm_Renderer_Tableless{
             $html = str_replace('{type}', $element->getType(), $html);
             $html = str_replace('{name}', $element->getName(), $html);
             $html = str_replace('{groupname}', '', $html);
-            $html = str_replace('{class}', $element->getAttribute('class'), $html);
+            $html = str_replace('{class}', $element->getAttribute('class') ?? '', $html);
             $emptylabel = '';
             if ($element->getLabel() == '') {
                 $emptylabel = 'femptylabel';

lib/html2text/lib.php

@@ -52,7 +52,7 @@ class core_html2text extends \Html2Text\Html2Text {
      */
     function __construct($html = '', $options = array()) {
         // Call the parent constructor.
-        parent::__construct($html, $options);
+        parent::__construct($html ?? '', $options);
 
         // MDL-27736: Trailing spaces before newline or tab.
         $this->entSearch[] = '/[ ]+([\n\t])/';

lib/mathslib.php

@@ -123,7 +123,7 @@ class calc_formula {
      * @return string localised formula
      */
     public static function localize($formula) {
-        $formula = str_replace('.', '$', $formula); // temp placeholder
+        $formula = str_replace('.', '$', $formula ?? ''); // temp placeholder
         $formula = str_replace(',', get_string('listsep', 'langconfig'), $formula);
         $formula = str_replace('$', get_string('decsep', 'langconfig'), $formula);
         return $formula;

lib/navigationlib.php

@@ -5836,7 +5836,7 @@ class navigation_json {
         }
 
         if ($child->forcetitle || $child->title !== $child->text) {
-            $attributes['title'] = htmlentities($child->title, ENT_QUOTES, 'UTF-8');
+            $attributes['title'] = htmlentities($child->title ?? '', ENT_QUOTES, 'UTF-8');
         }
         if (array_key_exists($child->key.':'.$child->type, $this->expandable)) {
             $attributes['expandable'] = $child->key;

lib/outputcomponents.php

@@ -2352,7 +2352,7 @@ class html_writer {
         if (!is_null($for)) {
             $attributes = array_merge($attributes, array('for' => $for));
         }
-        $text = trim($text);
+        $text = trim($text ?? '');
         $label = self::tag('label', $text, $attributes);
 
         // TODO MDL-12192 $colonize disabled for now yet

lib/outputlib.php

@@ -1854,7 +1854,7 @@ class theme_config {
         // Now resolve all theme settings or do any other postprocessing.
         // This needs to be done before calling core parser, since the parser strips [[settings]] tags.
         $csspostprocess = $this->csspostprocess;
-        if (function_exists($csspostprocess)) {
+        if ($csspostprocess && function_exists($csspostprocess)) {
             $css = $csspostprocess($css, $this);
         }
 

lib/setuplib.php

@@ -634,6 +634,7 @@ function get_docs_url($path = null) {
         $path = '';
     }
 
+    $path = $path ?? '';
     // Absolute URLs are used unmodified.
     if (substr($path, 0, 7) === 'http://' || substr($path, 0, 8) === 'https://') {
         return $path;

lib/tablelib.php

@@ -1463,7 +1463,7 @@ class flexible_table {
 
         // Load any existing user preferences.
         if ($this->persistent) {
-            $this->prefs = json_decode(get_user_preferences('flextable_' . $this->uniqueid), true);
+            $this->prefs = json_decode(get_user_preferences('flextable_' . $this->uniqueid) ?? '', true);
             $oldprefs = $this->prefs;
         } else if (isset($SESSION->flextable[$this->uniqueid])) {
             $this->prefs = $SESSION->flextable[$this->uniqueid];

lib/tests/behat/behat_accessibility.php

@@ -131,7 +131,7 @@ return (() => {
 EOF;
 
         for ($i = 0; $i < self::get_extended_timeout() * 10; $i++) {
-            $results = json_decode($this->evaluate_script($getresults));
+            $results = json_decode($this->evaluate_script($getresults) ?? '');
             if ($results) {
                 break;
             }

lib/weblib.php

@@ -97,7 +97,7 @@ function s($var) {
     }
 
     return preg_replace('/&#(\d+|x[0-9a-f]+);/i', '&#$1;',
-            htmlspecialchars($var, ENT_QUOTES | ENT_HTML401 | ENT_SUBSTITUTE));
+            htmlspecialchars($var ?? '', ENT_QUOTES | ENT_HTML401 | ENT_SUBSTITUTE));
 }
 
 /**
@@ -149,7 +149,7 @@ function addslashes_js($var) {
  */
 function strip_querystring($url) {
 
-    if ($commapos = strpos($url, '?')) {
+    if ($commapos = strpos($url ?? '', '?')) {
         return substr($url, 0, $commapos);
     } else {
         return $url;
@@ -336,6 +336,7 @@ class moodle_url {
             $this->anchor = $url->anchor;
 
         } else {
+            $url = $url ?? '';
             // Detect if anchor used.
             $apos = strpos($url, '#');
             if ($apos !== false) {
@@ -1127,7 +1128,7 @@ function validate_email($address) {
 
     require_once("{$CFG->libdir}/phpmailer/moodle_phpmailer.php");
 
-    return moodle_phpmailer::validateAddress($address) && !preg_match('/[<>]/', $address);
+    return moodle_phpmailer::validateAddress($address ?? '') && !preg_match('/[<>]/', $address);
 }
 
 /**
@@ -1540,7 +1541,7 @@ function format_string($string, $striplinks = true, $options = null) {
  * @return string
  */
 function replace_ampersands_not_followed_by_entity($string) {
-    return preg_replace("/\&(?![a-zA-Z0-9#]{1,8};)/", "&amp;", $string);
+    return preg_replace("/\&(?![a-zA-Z0-9#]{1,8};)/", "&amp;", $string ?? '');
 }
 
 /**

media/player/youtube/classes/plugin.php

@@ -63,7 +63,7 @@ class media_youtube_plugin extends core_media_player_external {
 
     protected function embed_external(moodle_url $url, $name, $width, $height, $options) {
 
-        $info = trim($name);
+        $info = trim($name ?? '');
         if (empty($info) or strpos($info, 'http') === 0) {
             $info = get_string('pluginname', 'media_youtube');
         }
@@ -125,7 +125,7 @@ OET;
         if (is_numeric($rawtime)) {
             // Start time already specified as a number of seconds; ensure it's an integer.
             $seconds = $rawtime;
-        } else if (preg_match('/(\d+?h)?(\d+?m)?(\d+?s)?/i', $rawtime, $matches)) {
+        } else if (preg_match('/(\d+?h)?(\d+?m)?(\d+?s)?/i', $rawtime ?? '', $matches)) {
             // Convert into a raw number of seconds, as that's all embedded players accept.
             for ($i = 1; $i < count($matches); $i++) {
                 if (empty($matches[$i])) {

mod/data/classes/preset.php

@@ -310,7 +310,7 @@ class preset {
         $instance = $this->manager->get_instance();
         foreach (manager::TEMPLATES_LIST as $templatename => $templatefilename) {
             $templatefile = fopen("$exportdir/$templatefilename", 'w');
-            fwrite($templatefile, $instance->{$templatename});
+            fwrite($templatefile, $instance->{$templatename} ?? '');
             fclose($templatefile);
         }
 
@@ -710,7 +710,7 @@ class preset {
         $presetxmldata = "<preset>\n\n";
 
         // Add description.
-        $presetxmldata .= '<description>' . htmlspecialchars($this->description, ENT_COMPAT) . "</description>\n\n";
+        $presetxmldata .= '<description>' . htmlspecialchars($this->description ?? '', ENT_COMPAT) . "</description>\n\n";
 
         // Add settings.
         // Raw settings are not preprocessed during saving of presets.

mod/data/classes/search/entry.php

@@ -304,7 +304,7 @@ class entry extends \core_search\base_mod {
                 continue;
             }
             $content->priority = $classname::get_priority();
-            $content->addtemplateposition = strpos($template, '[['.$content->fldname.']]');
+            $content->addtemplateposition = strpos($template ?? '', '[['.$content->fldname.']]');
         }
 
         $orderqueue = new \SPLPriorityQueue();

mod/data/field/latlong/field.class.php

@@ -170,11 +170,11 @@ class data_field_latlong extends data_field_base {
         }
 
         $lat = $content->content;
-        if (strlen($lat) < 1) {
+        if (strlen($lat ?? '') < 1) {
             return '';
         }
         $long = $content->content1;
-        if (strlen($long) < 1) {
+        if (strlen($long ?? '') < 1) {
             return '';
         }
         // We use format_float to display in the regional format.
@@ -254,7 +254,7 @@ class data_field_latlong extends data_field_base {
         // When updating these values (which might be region formatted) we should format
         // the float to allow for a consistent float format in the database.
         $value = unformat_float($value);
-        $value = trim($value);
+        $value = trim($value ?? '');
         if (strlen($value) > 0) {
             $value = floatval($value);
         } else {

mod/data/field/number/field.class.php

@@ -68,7 +68,7 @@ class data_field_number extends data_field_base {
             return '';
         }
         $number = $content->content;
-        $decimals = trim($this->field->param1);
+        $decimals = trim($this->field->param1 ?? '');
         // Only apply number formatting if param1 contains an integer number >= 0.
         if (preg_match("/^\d+$/", $decimals)) {
             $decimals = $decimals * 1;

mod/data/lib.php

@@ -840,19 +840,19 @@ function data_replace_field_in_templates($data, $searchfieldname, $newfieldname)
     $newdata = new stdClass();
     $newdata->id = $data->id;
     $newdata->singletemplate = str_ireplace('[['.$searchfieldname.']]',
-            $prestring.$newfieldname.$poststring, $data->singletemplate);
+            $prestring.$newfieldname.$poststring, $data->singletemplate ?? '');
 
     $newdata->listtemplate = str_ireplace('[['.$searchfieldname.']]',
-            $prestring.$newfieldname.$poststring, $data->listtemplate);
+            $prestring.$newfieldname.$poststring, $data->listtemplate ?? '');
 
     $newdata->addtemplate = str_ireplace('[['.$searchfieldname.']]',
-            $prestring.$newfieldname.$poststring, $data->addtemplate);
+            $prestring.$newfieldname.$poststring, $data->addtemplate ?? '');
 
     $newdata->addtemplate = str_ireplace('[['.$searchfieldname.'#id]]',
-            $prestring.$newfieldname.$idpart.$poststring, $data->addtemplate);
+            $prestring.$newfieldname.$idpart.$poststring, $data->addtemplate ?? '');
 
     $newdata->rsstemplate = str_ireplace('[['.$searchfieldname.']]',
-            $prestring.$newfieldname.$poststring, $data->rsstemplate);
+            $prestring.$newfieldname.$poststring, $data->rsstemplate ?? '');
 
     return $DB->update_record('data', $newdata);
 }

mod/h5pactivity/classes/xapi/handler.php

@@ -83,7 +83,7 @@ class handler extends handler_base {
         // H5P add some extra params to ID to define subcontents.
         $parts = explode('?', $xapiobject, 2);
         $contextid = array_shift($parts);
-        $subcontent = str_replace('subContentId=', '', array_shift($parts));
+        $subcontent = str_replace('subContentId=', '', array_shift($parts) ?? '');
         if (empty($contextid) || !is_numeric($contextid)) {
             return null;
         }

mod/lti/lib.php

@@ -318,7 +318,7 @@ function mod_lti_get_all_content_items(\core_course\local\entity\content_item $d
         $type->name     = 'lti_type_' . $ltitype->id;
         // Clean the name. We don't want tags here.
         $type->title    = clean_param($ltitype->name, PARAM_NOTAGS);
-        $trimmeddescription = trim($ltitype->description);
+        $trimmeddescription = trim($ltitype->description ?? '');
         $type->help = '';
         if ($trimmeddescription != '') {
             // Clean the description. We don't want tags here.

mod/lti/locallib.php

@@ -2437,7 +2437,7 @@ function lti_get_configured_types($courseid, $sectionreturn = 0) {
         $type->name     = 'lti_type_' . $ltitype->id;
         // Clean the name. We don't want tags here.
         $type->title    = clean_param($ltitype->name, PARAM_NOTAGS);
-        $trimmeddescription = trim($ltitype->description);
+        $trimmeddescription = trim($ltitype->description ?? '');
         if ($trimmeddescription != '') {
             // Clean the description. We don't want tags here.
             $type->help     = clean_param($trimmeddescription, PARAM_NOTAGS);
@@ -2454,7 +2454,7 @@ function lti_get_configured_types($courseid, $sectionreturn = 0) {
 function lti_get_domain_from_url($url) {
     $matches = array();
 
-    if (preg_match(LTI_URL_DOMAIN_REGEX, $url, $matches)) {
+    if (preg_match(LTI_URL_DOMAIN_REGEX, $url ?? '', $matches)) {
         return $matches[1];
     }
 }

mod/quiz/accessrule/seb/classes/seb_quiz_settings.php

@@ -662,7 +662,7 @@ class seb_quiz_settings extends persistent {
      * @return array of string, the separate keys.
      */
     private function split_keys($keys) : array {
-        $keys = preg_split('~[ \t\n\r,;]+~', $keys, -1, PREG_SPLIT_NO_EMPTY);
+        $keys = preg_split('~[ \t\n\r,;]+~', $keys ?? '', -1, PREG_SPLIT_NO_EMPTY);
         foreach ($keys as $i => $key) {
             $keys[$i] = strtolower($key);
         }

mod/survey/classes/privacy/provider.php

@@ -227,7 +227,7 @@ class provider implements
                 'options' => $record->qoptions
             ]);
             $qtype = $record->qtype;
-            $options = explode(',', $q->options);
+            $options = explode(',', $q->options ?? '');
 
             $carry[] = [
                 'question' => array_merge((array) $q, [

mod/workshop/classes/portfolio_caller.php

@@ -342,7 +342,7 @@ class mod_workshop_portfolio_caller extends portfolio_module_caller_base {
         }
 
         if ($this->workshop->overallfeedbackmode) {
-            if ($assessment->feedbackauthorattachment or trim($assessment->feedbackauthor) !== '') {
+            if ($assessment->feedbackauthorattachment or trim($assessment->feedbackauthor ?? '') !== '') {
                 $output .= html_writer::tag('h3', get_string('overallfeedback', 'mod_workshop'));
                 $content = $this->format_exported_text($assessment->feedbackauthor, $assessment->feedbackauthorformat);
                 $content = portfolio_rewrite_pluginfile_urls($content, $this->workshop->context->id, 'mod_workshop',

privacy/classes/local/request/moodle_content_writer.php

@@ -179,7 +179,7 @@ class moodle_content_writer implements content_writer {
         $returnstring = $path . DIRECTORY_SEPARATOR . $this->get_files_target_url($component, $filearea, $itemid) . '/';
         $returnstring = clean_param($returnstring, PARAM_PATH);
 
-        return str_replace('@@PLUGINFILE@@/', $returnstring, $text);
+        return str_replace('@@PLUGINFILE@@/', $returnstring, $text ?? '');
     }
 
     /**

privacy/classes/tests/request/content_writer.php

@@ -382,7 +382,7 @@ class content_writer implements \core_privacy\local\request\content_writer {
      * @return  string                      The processed string
      */
     public function rewrite_pluginfile_urls(array $subcontext, $component, $filearea, $itemid, $text) : string {
-        return str_replace('@@PLUGINFILE@@/', 'files/', $text);
+        return str_replace('@@PLUGINFILE@@/', 'files/', $text ?? '');
     }
 
     /**

question/engine/renderer.php

@@ -149,7 +149,7 @@ class core_question_renderer extends plugin_renderer_base {
      * @return HTML fragment.
      */
     protected function number($number) {
-        if (trim($number) === '') {
+        if (trim($number ?? '') === '') {
             return '';
         }
         $numbertext = '';

question/type/calculated/db/upgradelib.php

@@ -270,7 +270,7 @@ class qtype_calculated_qe2_attempt_updater extends question_qtype_attempt_update
      *      corresponding value.
      */
     protected function substitute_values_for_eval($expression) {
-        return str_replace($this->search, $this->safevalue, $expression);
+        return str_replace($this->search ?? '', $this->safevalue ?? '', $expression ?? '');
     }
 
     /**
@@ -282,7 +282,7 @@ class qtype_calculated_qe2_attempt_updater extends question_qtype_attempt_update
      *      corresponding value.
      */
     protected function substitute_values_pretty($text) {
-        return str_replace($this->search, $this->prettyvalue, $text);
+        return str_replace($this->search ?? '', $this->prettyvalue ?? '', $text ?? '');
     }
 
     /**
@@ -296,7 +296,7 @@ class qtype_calculated_qe2_attempt_updater extends question_qtype_attempt_update
         $text = preg_replace_callback('~\{=([^{}]*(?:\{[^{}]+}[^{}]*)*)}~',
                 function ($matches) use ($vs, $format, $length) {
                     return $vs->format_float($vs->calculate($matches[1]), $length, $format);
-                }, $text);
+                }, $text ?? '');
         return $this->substitute_values_pretty($text);
     }
 }

question/type/calculatedmulti/db/upgradelib.php

@@ -294,7 +294,7 @@ class qtype_calculatedmulti_qe2_attempt_updater extends question_qtype_attempt_u
      *      corresponding value.
      */
     protected function substitute_values_for_eval($expression) {
-        return str_replace($this->search, $this->safevalue, $expression);
+        return str_replace($this->search ?? '', $this->safevalue ?? '', $expression ?? '');
     }
 
     /**
@@ -306,7 +306,7 @@ class qtype_calculatedmulti_qe2_attempt_updater extends question_qtype_attempt_u
      *      corresponding value.
      */
     protected function substitute_values_pretty($text) {
-        return str_replace($this->search, $this->prettyvalue, $text);
+        return str_replace($this->search ?? '', $this->prettyvalue ?? '', $text ?? '');
     }
 
     /**
@@ -320,7 +320,7 @@ class qtype_calculatedmulti_qe2_attempt_updater extends question_qtype_attempt_u
         $text = preg_replace_callback(qtype_calculated::FORMULAS_IN_TEXT_REGEX,
                 function ($matches) use ($vs, $format, $length) {
                     return $vs->format_float($vs->calculate($matches[1]), $length, $format);
-                }, $text);
+                }, $text ?? '');
         return $this->substitute_values_pretty($text);
     }
 }

question/type/multianswer/renderer.php

@@ -235,7 +235,7 @@ class qtype_multianswer_textfield_renderer extends qtype_multianswer_subq_render
         }
 
         // Work out a good input field size.
-        $size = max(1, core_text::strlen(trim($response)) + 1);
+        $size = max(1, core_text::strlen(trim($response ?? '')) + 1);
         foreach ($subq->answers as $ans) {
             $size = max($size, core_text::strlen(trim($ans->answer)));
         }

question/type/numerical/questiontype.php

@@ -653,7 +653,7 @@ class qtype_numerical_answer_processor {
     public function apply_units($response, $separateunit = null) {
         // Strip spaces (which may be thousands separators) and change other forms
         // of writing e to e.
-        $response = str_replace(' ', '', $response);
+        $response = str_replace(' ', '', $response ?? '');
         $response = preg_replace('~(?:e|E|(?:x|\*|×)10(?:\^|\*\*))([+-]?\d+)~', 'e$1', $response);
 
         // If a . is present or there are multiple , (i.e. 2,456,789 ) assume ,