Fix infinite recursion when a plugin on pdoToolsOnFenomInit re-enters getFenom()

core/components/pdotools/docs/changelog.txt

@@ -1,5 +1,9 @@
 Changelog for pdoTools.
 
+Unreleased
+==============
+- Fixed infinite recursion (memory exhaustion) when a plugin attached to the pdoToolsOnFenomInit event re-enters CoreTools::getFenom() while Fenom is being constructed (e.g. loading a static element with the pdoParser active). The event is now fired once from getFenom() after the Fenom instance is registered in the services container.
+
 3.0.2-pl (11.04.2023)
 ==============
 - Support for file snippets in the pdoPage class.

core/components/pdotools/src/CoreTools.php

@@ -20,6 +20,8 @@ class CoreTools
     protected $modx;
     /** @var Fenom $fenom */
     protected $fenom;
+    /** @var bool $fenomInitialized Whether the pdoToolsOnFenomInit event has been fired */
+    protected $fenomInitialized = false;
     /** @var array $config Array with class config */
     protected $config = [];
     /** @var array $store Array for cache elements and user data */
@@ -146,7 +148,22 @@ public function getFenom()
             $this->modx->services->add('fenom', new $class($this->modx, $this));
         }
 
-        return $this->modx->services->get('fenom');
+        /** @var Fenom $fenom */
+        $fenom = $this->modx->services->get('fenom');
+
+        // Fire pdoToolsOnFenomInit only once, and only AFTER the instance has been
+        // stored in the services container. If the event were fired from the Fenom
+        // constructor (i.e. before the container memoizes the instance), a plugin
+        // attached to pdoToolsOnFenomInit that re-enters getFenom() - for example the
+        // pdoParser parsing media source properties while a static element is being
+        // loaded - would build another Fenom and recurse until the memory limit is
+        // exhausted.
+        if (!$this->fenomInitialized) {
+            $this->fenomInitialized = true;
+            $fenom->invokeInitEvent();
+        }
+
+        return $fenom;
     }
 
     /**

core/components/pdotools/src/Parsing/Fenom/Fenom.php

@@ -60,12 +60,24 @@ public function __construct(modX $modx, CoreTools $pdoTools)
         $this->setOptions($options);
 
         $this->_addDefaultModifiers();
+    }
 
+    /**
+     * Fire the pdoToolsOnFenomInit event so plugins can extend Fenom
+     * (register custom modifiers, functions, etc).
+     *
+     * This is intentionally NOT called from the constructor. It must be invoked
+     * by CoreTools::getFenom() AFTER the instance has been registered in the
+     * services container - otherwise a plugin attached to pdoToolsOnFenomInit
+     * that re-enters getFenom() would build another Fenom and recurse endlessly.
+     */
+    public function invokeInitEvent()
+    {
         $this->modx->invokeEvent(
             'pdoToolsOnFenomInit',
             [
                 'fenom' => $this,
-                'config' => $pdoTools->config(),
+                'config' => $this->pdoTools->config(),
             ]
         );
     }