MDL-72312 environment: Add new optional custom check for igbinary

This optional environmental check will look if:

- the site is running php72.
- the site has igbinary extension enabled.
- the igbinary extension version is a buggy one >=3.2.2 <= 3.2.4
- the bug is reproducible.

And will warn if all the conditions are met.

admin/environment.xml

@@ -3163,6 +3163,11 @@
           <ON_CHECK message="sixtyfourbitswarning" />
         </FEEDBACK>
       </CUSTOM_CHECK>
+      <CUSTOM_CHECK file="lib/upgradelib.php" function="check_igbinary322_version" level="optional">
+        <FEEDBACK>
+          <ON_CHECK message="igbinary322buggyversion" />
+        </FEEDBACK>
+      </CUSTOM_CHECK>
     </CUSTOM_CHECKS>
   </MOODLE>
   <MOODLE version="3.10" requires="3.5">
@@ -3345,6 +3350,11 @@
           <ON_CHECK message="sixtyfourbitswarning" />
         </FEEDBACK>
       </CUSTOM_CHECK>
+      <CUSTOM_CHECK file="lib/upgradelib.php" function="check_igbinary322_version" level="optional">
+        <FEEDBACK>
+          <ON_CHECK message="igbinary322buggyversion" />
+        </FEEDBACK>
+      </CUSTOM_CHECK>
     </CUSTOM_CHECKS>
   </MOODLE>
   <MOODLE version="3.11" requires="3.6">

lang/en/admin.php

@@ -659,6 +659,7 @@
 $string['choosefiletoedit'] = 'Choose file to edit';
 $string['h5pgetcontenttypestask'] = 'Download available H5P content types from h5p.org';
 $string['iconvrequired'] = 'Installing ICONV extension is required.';
+$string['igbinary322buggyversion'] = 'The php-igbinary extension installed on the site can lead to problems when running with PHP 7.2. You are recommended to either upgrade to php-igbinary 3.2.5 or later, or alternatively to upgrade to PHP 7.3 or later.';
 $string['ignore'] = 'Ignore';
 $string['includemoduleuserdata'] = 'Include module user data';
 $string['incompatibleblocks'] = 'Incompatible blocks';

lib/upgradelib.php

@@ -2422,6 +2422,59 @@ function check_sixtyfour_bits(environment_results $result) {
     return null;
 }
 
+/**
+ * Check if the igbinary extension installed is buggy one
+ *
+ * There are a few php-igbinary versions that are buggy and
+ * return any unserialised array with wrong index. This defeats
+ * key() and next() operations on them.
+ *
+ * This library is used by MUC and also by memcached and redis
+ * when available.
+ *
+ * Let's inform if there is some problem when:
+ *   - php 7.2 is being used (php 7.3 and up are immune).
+ *   - the igbinary extension is installed.
+ *   - the version of the extension is between 3.2.2 and 3.2.4.
+ *   - the buggy behaviour is reproduced.
+ *
+ * @param environment_results $result object to update, if relevant.
+ * @return environment_results|null updated results or null.
+ */
+function check_igbinary322_version(environment_results $result) {
+
+    // No problem if using PHP version 7.3 and up.
+    $phpversion = normalize_version(phpversion());
+    if (version_compare($phpversion, '7.3', '>=')) {
+        return null;
+    }
+
+    // No problem if igbinary is not installed..
+    if (!function_exists('igbinary_serialize')) {
+        return null;
+    }
+
+    // No problem if using igbinary < 3.2.2 or > 3.2.4.
+    $igbinaryversion = normalize_version(phpversion('igbinary'));
+    if (version_compare($igbinaryversion, '3.2.2', '<') or version_compare($igbinaryversion, '3.2.4', '>')) {
+        return null;
+    }
+
+    // Let's verify the real behaviour to see if the bug is around.
+    // Note that we need this extra check because they released 3.2.5 with 3.2.4 version number, so
+    // over the paper, there are 3.2.4 working versions (3.2.5 ones with messed reflection version).
+    $data = [1, 2, 3];
+    $data = igbinary_unserialize(igbinary_serialize($data));
+    if (key($data) === 0) {
+        return null;
+    }
+
+    // Arrived here, we are using PHP 7.2 and a buggy verified igbinary version, let's inform and don't allow to continue.
+    $result->setInfo('igbinary version problem');
+    $result->setStatus(false);
+    return $result;
+}
+
 /**
  * Assert the upgrade key is provided, if it is defined.
  *