Added a way of handling requirements for H5P core

h5p-requirements.class.php

@@ -0,0 +1,68 @@
+<?php
+class H5PRequirements {
+
+  // Set warning threshold (32 MB)
+  const UPLOAD_SIZE_WARNING_THRESHOLD = 33554432;
+
+  public static function validatePrerequisites() {
+    $results = array();
+    // Need mbstring
+    if (!extension_loaded('mbstring')) {
+      $results[] = (Object)array (
+        'mandatory' => true,
+        'message' => 'H5 need the mbstring php extension',
+        'url' => 'https://h5p.org/h5p-php-core-prerequisites#mbstring'
+      );
+    }
+
+    if (!class_exists('ZipArchive')) {
+      $results[] = (Object)array (
+        'mandatory' => true,
+        'message' => 'Your PHP version does not support ZipArchive',
+        'url' => 'https://h5p.org/h5p-php-core-prerequisites#ziparchive'
+      );
+    }
+
+    // Check upload sizes:
+    $maxFileUploadSize = self::getMaxFileUploadSize();
+    if ($maxFileUploadSize < self::UPLOAD_SIZE_WARNING_THRESHOLD) {
+      $results[] = (Object)array (
+        'mandatory' => false,
+        'message' => "Your webserver's file upload settings makes it impossible to upload files larger than {$maxFileUploadSize} bytes. This might be a problem when trying to upload e.g. video files",
+        'url' => 'https://h5p.org/h5p-php-core-prerequisites#fileuploadsize'
+      );
+    }
+
+    // Other things to check might be:
+    // - php version
+    // - possible to run http get/post from server to h5p.org?
+    // - extension_loaded('openssl') ?
+
+    return $results;
+  }
+
+  private static function getMaxFileUploadSize () {
+    $max_upload = self::humanSizeTobytes(ini_get('upload_max_filesize'));
+    //select post limit
+    $max_post = self::humanSizeTobytes(ini_get('post_max_size'));
+    //select memory limit
+    $memory_limit = self::humanSizeTobytes(ini_get('memory_limit'));
+    // return the smallest of them, this defines the real limit
+    return min($max_upload, $max_post, $memory_limit);
+  }
+
+  private static function humanSizeTobytes($val) {
+    $val = trim($val);
+    $last = strtolower($val[strlen($val)-1]);
+    switch($last)
+    {
+      case 'g':
+      $val *= 1024;
+      case 'm':
+      $val *= 1024;
+      case 'k':
+      $val *= 1024;
+    }
+    return $val;
+  }
+}