Initial

system/Helpers/security_helper.php

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+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+use Config\Services;
+
+// CodeIgniter Security Helpers
+
+if (! function_exists('sanitize_filename')) {
+    /**
+     * Sanitize a filename to use in a URI.
+     */
+    function sanitize_filename(string $filename): string
+    {
+        return Services::security()->sanitizeFilename($filename);
+    }
+}
+
+if (! function_exists('strip_image_tags')) {
+    /**
+     * Strip Image Tags
+     */
+    function strip_image_tags(string $str): string
+    {
+        return preg_replace(
+            [
+                '#<img[\s/]+.*?src\s*=\s*(["\'])([^\\1]+?)\\1.*?\>#i',
+                '#<img[\s/]+.*?src\s*=\s*?(([^\s"\'=<>`]+)).*?\>#i',
+            ],
+            '\\2',
+            $str
+        );
+    }
+}
+
+if (! function_exists('encode_php_tags')) {
+    /**
+     * Convert PHP tags to entities
+     */
+    function encode_php_tags(string $str): string
+    {
+        return str_replace(['<?', '?>'], ['&lt;?', '?&gt;'], $str);
+    }
+}