feat: Disable callable serialization in sabre/xml

This a foot-gun that we are not using, so patching it out to make sure
 this never gets called.

Signed-off-by: Côme Chilliet <come.chilliet@nextcloud.com>

Author: come-nc

.patches/sabre-xml-remove-callable-serialization.patch

@@ -0,0 +1,14 @@
+diff --git a/lib/Serializer/functions.php b/lib/Serializer/functions.php
+index 23f22d4c8..f05fdc406 100644
+--- a/lib/Serializer/functions.php
++++ b/lib/Serializer/functions.php
+@@ -160,9 +160,6 @@ function standardSerializer(Writer $writer, $value)
+     } elseif (is_object($value) && isset($writer->classMap[get_class($value)])) {
+         // It's an object which class appears in the classmap.
+         $writer->classMap[get_class($value)]($writer, $value);
+-    } elseif (is_callable($value)) {
+-        // A callback
+-        $value($writer);
+     } elseif (is_array($value) && array_key_exists('name', $value)) {
+         // if the array had a 'name' element, we assume that this array
+         // describes a 'name' and optionally 'attributes' and 'value'.

composer.patches.json

@@ -10,6 +10,9 @@
 		"sabre/vobject": {
 			"fix use RDATE in time range check and use all instances": ".patches/sabre-vobject-rdate.patch",
 			"fix send participation reply on fresh event": ".patches/sabre-vobject-iTipBroker-replies.patch"
+		},
+		"sabre/xml": {
+			"Remove callable serialization": ".patches/sabre-xml-remove-callable-serialization.patch"
 		}
 	}
 }

sabre/xml/PATCHES.txt

@@ -0,0 +1,7 @@
+This file was automatically generated by Composer Patches (https://github.com/cweagans/composer-patches)
+Patches applied to this directory:
+
+Remove callable serialization
+Source: .patches/sabre-xml-remove-callable-serialization.patch
+
+

sabre/xml/lib/Serializer/functions.php

@@ -160,9 +160,6 @@ function standardSerializer(Writer $writer, $value)
     } elseif (is_object($value) && isset($writer->classMap[get_class($value)])) {
         // It's an object which class appears in the classmap.
         $writer->classMap[get_class($value)]($writer, $value);
-    } elseif (is_callable($value)) {
-        // A callback
-        $value($writer);
     } elseif (is_array($value) && array_key_exists('name', $value)) {
         // if the array had a 'name' element, we assume that this array
         // describes a 'name' and optionally 'attributes' and 'value'.