Fix phpGH-10234: Setting DOMAttr::textContent results in an empty attribute value.

We can't directly call xmlNodeSetContent, because it might encode the string
through xmlStringLenGetNodeList for types
XML_DOCUMENT_FRAG_NODE, XML_ELEMENT_NODE, XML_ATTRIBUTE_NODE.
In these cases we need to use a text node to avoid the encoding.
For the other cases, we *can* rely on xmlNodeSetContent because it is either
a no-op, or handles the content without encoding and clears the properties
field if needed.

The test was taken from the issue report, for the test:
Co-authored-by: ThomasWeinert <[email protected]>

Closes phpGH-10245.

Author: nielsdos

ext/dom/node.c

@@ -769,17 +769,28 @@ int dom_node_text_content_write(dom_object *obj, zval *newval)
 		return FAILURE;
 	}
 
-	if (nodep->type == XML_ELEMENT_NODE || nodep->type == XML_ATTRIBUTE_NODE) {
+	const xmlChar *xmlChars = (const xmlChar *) ZSTR_VAL(str);
+	int type = nodep->type;
+
+	/* We can't directly call xmlNodeSetContent, because it might encode the string through
+	 * xmlStringLenGetNodeList for types XML_DOCUMENT_FRAG_NODE, XML_ELEMENT_NODE, XML_ATTRIBUTE_NODE.
+	 * See tree.c:xmlNodeSetContent in libxml.
+	 * In these cases we need to use a text node to avoid the encoding.
+	 * For the other cases, we *can* rely on xmlNodeSetContent because it is either a no-op, or handles
+	 * the content without encoding and clears the properties field if needed. */
+	if (type == XML_DOCUMENT_FRAG_NODE || type == XML_ELEMENT_NODE || type == XML_ATTRIBUTE_NODE) {
 		if (nodep->children) {
 			node_list_unlink(nodep->children);
 			php_libxml_node_free_list((xmlNodePtr) nodep->children);
 			nodep->children = NULL;
 		}
+
+		xmlNode *textNode = xmlNewText(xmlChars);
+		xmlAddChild(nodep, textNode);
+	} else {
+		xmlNodeSetContent(nodep, xmlChars);
 	}
 
-	/* we have to use xmlNodeAddContent() to get the same behavior as with xmlNewText() */
-	xmlNodeSetContent(nodep, (xmlChar *) "");
-	xmlNodeAddContent(nodep, (xmlChar *) ZSTR_VAL(str));
 	zend_string_release_ex(str, 0);
 
 	return SUCCESS;

ext/dom/tests/gh10234.phpt

@@ -0,0 +1,52 @@
+--TEST--
+GH-10234 (Setting DOMAttr::textContent results in an empty attribute value.)
+--EXTENSIONS--
+dom
+--FILE--
+<?php
+$document = new DOMDocument();
+$document->loadXML('<element attribute="value"/>');
+$attribute = $document->documentElement->getAttributeNode('attribute');
+
+var_dump($document->saveHTML());
+var_dump($attribute->textContent);
+
+$attribute->textContent = 'new value';
+var_dump($attribute->textContent);
+var_dump($document->saveHTML());
+
+$attribute->textContent = 'hello & world';
+var_dump($attribute->textContent);
+var_dump($document->saveHTML());
+
+$attribute->textContent = '<b>hi</b>';
+var_dump($attribute->textContent);
+var_dump($document->saveHTML());
+
+$document->documentElement->textContent = 'hello & world';
+var_dump($document->documentElement->textContent);
+var_dump($document->saveHTML());
+
+$document->documentElement->textContent = '<b>hi</b>';
+var_dump($document->documentElement->textContent);
+var_dump($document->saveHTML());
+?>
+--EXPECT--
+string(38) "<element attribute="value"></element>
+"
+string(5) "value"
+string(9) "new value"
+string(42) "<element attribute="new value"></element>
+"
+string(13) "hello & world"
+string(50) "<element attribute="hello &amp; world"></element>
+"
+string(9) "<b>hi</b>"
+string(54) "<element attribute="&lt;b&gt;hi&lt;/b&gt;"></element>
+"
+string(13) "hello & world"
+string(71) "<element attribute="&lt;b&gt;hi&lt;/b&gt;">hello &amp; world</element>
+"
+string(9) "<b>hi</b>"
+string(75) "<element attribute="&lt;b&gt;hi&lt;/b&gt;">&lt;b&gt;hi&lt;/b&gt;</element>
+"