Fix #81433: DOMElement::setIdAttribute() called twice may remove ID

We must only remove the attribute id, if the user requested that.

Closes GH-7482.

Author: vicvolk

NEWS

@@ -2,6 +2,9 @@ PHP                                                                        NEWS
 |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 ?? ??? ????, PHP 7.4.25
 
+- DOM:
+  . Fixed bug #81433 (DOMElement::setIdAttribute() called twice may remove ID).
+    (Viktor Volkov)
 
 23 Dep 2021, PHP 7.4.24
 

ext/dom/element.c

@@ -1157,11 +1157,9 @@ static void php_set_attribute_id(xmlAttrPtr attrp, zend_bool is_id) /* {{{ */
 			xmlAddID(NULL, attrp->doc, id_val, attrp);
 			xmlFree(id_val);
 		}
-	} else {
-		if (attrp->atype == XML_ATTRIBUTE_ID) {
-			xmlRemoveID(attrp->doc, attrp);
-			attrp->atype = 0;
-		}
+	} else if (is_id == 0 && attrp->atype == XML_ATTRIBUTE_ID) {
+		xmlRemoveID(attrp->doc, attrp);
+		attrp->atype = 0;
 	}
 }
 /* }}} */

ext/dom/tests/bug81433.phpt

@@ -0,0 +1,26 @@
+--TEST--
+Bug #81433 (DOMElement::setIdAttribute(attr, true) called twice removes ID)
+--SKIPIF--
+<?php
+require_once('skipif.inc');
+?>
+--FILE--
+<?php
+$dom = new DOMDocument('1.0', 'utf-8');
+
+$element = $dom->createElement('test', 'root');
+
+$dom->appendChild($element);
+
+$element->setAttribute("id", 123);
+$element->setIdAttribute("id", true);
+
+$node = $element->getAttributeNode("id");
+var_dump($node->isId());
+
+$element->setIdAttribute("id", true);
+var_dump($node->isId());
+?>
+--EXPECT--
+bool(true)
+bool(true)