ext/xml: Refactor extension to use FCC instead of zvals for handlers

UPGRADING

@@ -45,6 +45,17 @@ PHP 8.4 UPGRADE NOTES
     for invalid modes. Previously invalid modes would have been interpreted as
     PHP_ROUND_HALF_UP.
 
+- XML:
+  . The xml_set_*_handler() functions now declare and check for an effective
+    signature of callable|string|null for the $handler parameters.
+    Moreover, values of type string that correspond to method names,
+    of object set with xml_set_object() are now checked to see if the method
+    exists on the class of the previously passed object.
+    This means that xml_set_object() must now always be called prior to setting
+    method names as callables.
+    Passing an empty string to disable the handler is still allowed,
+    but not recommended.
+
 - XSL:
   . XSLTProcessor::setParameter() will now throw a ValueError when its arguments
     contain null bytes. This never actually worked correctly in the first place,

ext/xml/tests/bug30266.phpt

@@ -42,6 +42,7 @@ class XML_Parser
 $p1 = new Xml_Parser();
 try {
     $p1->parse('<tag1><tag2></tag2></tag1>');
+    echo "Exception swallowed\n";
 } catch (Exception $e) {
     echo "OK\n";
 }

ext/xml/tests/bug32001.phpt

@@ -100,8 +100,8 @@ HERE;
 
         $parser = xml_parser_create(NULL);
         xml_parser_set_option($parser, XML_OPTION_CASE_FOLDING, 0);
-        xml_set_element_handler($parser, "start_element", "end_element");
         xml_set_object($parser, $this);
+        xml_set_element_handler($parser, "start_element", "end_element");
 
         if ($this->chunk_size == 0) {
             $success = @xml_parse($parser, $data, true);

ext/xml/tests/bug73135.phpt

@@ -6,18 +6,20 @@ xml
 edgarsandi - <[email protected]>
 --FILE--
 <?php
-    function start_elem($parser, $xml) {
-        xml_parse($parser, $xml);
-    }
+function start_elem($parser, $xml) {
+    xml_parse($parser, $xml);
+}
+
+function dummy() {}
 
-    $xml = <<<HERE
-    <a xmlns="ahihi">
-        <bar foo="ahihi"/>
-    </a>
+$xml = <<<HERE
+<a xmlns="ahihi">
+    <bar foo="ahihi"/>
+</a>
 HERE;
 
     $parser = xml_parser_create_ns();
-    xml_set_element_handler($parser, 'start_elem', 'ahihi');
+    xml_set_element_handler($parser, 'start_elem', 'dummy');
     xml_parse($parser, $xml);
 ?>
 --EXPECTF--

ext/xml/tests/set_element_handler_trampoline.phpt

@@ -0,0 +1,97 @@
+--TEST--
+Test xml_set_element_handler handlers as trampoline callback
+--EXTENSIONS--
+xml
+--FILE--
+<?php
+
+class CustomXmlParser
+{
+    public function startHandler($XmlParser, $tag, $attr)
+    {
+        echo 'Method start handler: ', $tag, PHP_EOL;
+    }
+
+    public function endHandler($XmlParser, $tag)
+    {
+        echo 'Method end handler: ', $tag, PHP_EOL;
+    }
+}
+
+$customParser = new CustomXmlParser;
+
+class TrampolineTest {
+    public function __call(string $name, array $arguments) {
+        echo 'Trampoline for ', $name, PHP_EOL;
+        echo 'Tag: ', $arguments[1], PHP_EOL;
+    }
+}
+
+$o = new TrampolineTest();
+$startCallback = [$o, 'start_handler'];
+$endCallback = [$o, 'end_handler'];
+
+$xml = <<<HERE
+<a>
+  <b/>
+  <c>Text</c>
+</a>
+HERE;
+
+echo "Both handlers are trampolines:\n";
+$parser = xml_parser_create();
+xml_set_element_handler($parser, $startCallback, $endCallback);
+xml_parse($parser, $xml, true);
+xml_parser_free($parser);
+
+echo "\nStart handler is trampoline, end handler method string:\n";
+$parser = xml_parser_create();
+xml_set_object($parser, $customParser);
+xml_set_element_handler($parser, $startCallback, 'endHandler');
+xml_parse($parser, $xml, true);
+xml_parser_free($parser);
+
+echo "\nEnd handler is trampoline, start handler method string:\n";
+$parser = xml_parser_create();
+xml_set_object($parser, $customParser);
+xml_set_element_handler($parser, 'startHandler', $endCallback);
+xml_parse($parser, $xml, true);
+xml_parser_free($parser);
+
+?>
+--EXPECT--
+Both handlers are trampolines:
+Trampoline for start_handler
+Tag: A
+Trampoline for start_handler
+Tag: B
+Trampoline for end_handler
+Tag: B
+Trampoline for start_handler
+Tag: C
+Trampoline for end_handler
+Tag: C
+Trampoline for end_handler
+Tag: A
+
+Start handler is trampoline, end handler method string:
+Trampoline for start_handler
+Tag: A
+Trampoline for start_handler
+Tag: B
+Method end handler: B
+Trampoline for start_handler
+Tag: C
+Method end handler: C
+Method end handler: A
+
+End handler is trampoline, start handler method string:
+Method start handler: A
+Method start handler: B
+Trampoline for end_handler
+Tag: B
+Method start handler: C
+Trampoline for end_handler
+Tag: C
+Trampoline for end_handler
+Tag: A

ext/xml/tests/set_element_handler_trampoline_errors.phpt

@@ -0,0 +1,46 @@
+--TEST--
+Test xml_set_element_handler handlers as trampoline callback
+--EXTENSIONS--
+xml
+--FILE--
+<?php
+
+class TrampolineTest {
+    public function __call(string $name, array $arguments) {
+        echo 'Trampoline for ', $name, PHP_EOL;
+        echo 'Tag: ', $arguments[1], PHP_EOL;
+    }
+}
+
+$o = new TrampolineTest();
+$startCallback = [$o, 'start_handler'];
+$endCallback = [$o, 'end_handler'];
+
+$xml = <<<HERE
+<a>
+  <b/>
+  <c>Text</c>
+</a>
+HERE;
+
+$parser = xml_parser_create();
+echo "2nd arg is rubbish:\n";
+try {
+    xml_set_element_handler($parser, [], $endCallback);
+} catch (\Throwable $e) {
+    echo $e::class, ': ', $e->getMessage(), PHP_EOL;
+}
+echo "3rd arg is rubbish:\n";
+try {
+    xml_set_element_handler($parser, $startCallback, []);
+} catch (\Throwable $e) {
+    echo $e::class, ': ', $e->getMessage(), PHP_EOL;
+}
+xml_parser_free($parser);
+
+?>
+--EXPECT--
+2nd arg is rubbish:
+TypeError: xml_set_element_handler(): Argument #2 ($start_handler) must be of type callable|string|null
+3rd arg is rubbish:
+TypeError: xml_set_element_handler(): Argument #2 ($start_handler) must be of type callable|string|null

ext/xml/tests/set_handler_errors.phpt

@@ -0,0 +1,61 @@
+--TEST--
+Error conditions when setting invalid handler callables
+--EXTENSIONS--
+xml
+--FILE--
+<?php
+declare(strict_types=1);
+
+/* Use xml_set_processing_instruction_handler() for generic implementation */
+echo 'Invalid $parser:', PHP_EOL;
+$obj = new stdClass();
+try {
+    xml_set_processing_instruction_handler($obj, null);
+} catch (\Throwable $e) {
+    echo $e::class, ': ', $e->getMessage(), PHP_EOL;
+}
+
+/* Create valid parser */
+$parser = xml_parser_create();
+
+echo 'Invalid callable type true:', PHP_EOL;
+try {
+    xml_set_processing_instruction_handler($parser, true);
+} catch (\Throwable $e) {
+    echo $e::class, ': ', $e->getMessage(), PHP_EOL;
+}
+
+echo 'Invalid callable type int:', PHP_EOL;
+try {
+    xml_set_processing_instruction_handler($parser, 10);
+} catch (\Throwable $e) {
+    echo $e::class, ': ', $e->getMessage(), PHP_EOL;
+}
+
+echo 'String not callable and no object set:', PHP_EOL;
+try {
+    xml_set_processing_instruction_handler($parser, "nonexistent_method");
+} catch (\Throwable $e) {
+    echo $e::class, ': ', $e->getMessage(), PHP_EOL;
+}
+
+echo 'String non existent method on set object:', PHP_EOL;
+xml_set_object($parser, $obj);
+try {
+    xml_set_processing_instruction_handler($parser, "nonexistent_method");
+} catch (\Throwable $e) {
+    echo $e::class, ': ', $e->getMessage(), PHP_EOL;
+}
+
+?>
+--EXPECT--
+Invalid $parser:
+TypeError: xml_set_processing_instruction_handler(): Argument #1 ($parser) must be of type XMLParser, stdClass given
+Invalid callable type true:
+TypeError: xml_set_processing_instruction_handler(): Argument #2 ($handler) must be of type callable|string|null
+Invalid callable type int:
+TypeError: xml_set_processing_instruction_handler(): Argument #2 ($handler) must be of type callable|string|null
+String not callable and no object set:
+ValueError: xml_set_processing_instruction_handler(): Argument #2 ($handler) an object must be set via xml_set_object() to be able to lookup method
+String non existent method on set object:
+ValueError: xml_set_processing_instruction_handler(): Argument #2 ($handler) method stdClass::nonexistent_method() does not exist

ext/xml/tests/set_handler_trampoline.phpt

@@ -0,0 +1,33 @@
+--TEST--
+Test XMLParser generic handlers as trampoline callback
+--EXTENSIONS--
+xml
+--FILE--
+<?php
+class TrampolineTest {
+    public function __call(string $name, array $arguments) {
+        echo 'Trampoline for ', $name, PHP_EOL;
+        echo 'Target: ', $arguments[1], PHP_EOL;
+        echo 'Data: ', $arguments[2], PHP_EOL;
+    }
+}
+
+$o = new TrampolineTest();
+$callback = [$o, 'pi_handler'];
+
+$xml = <<<HERE
+<?xml version="1.0" encoding="ISO-8859-1"?>
+<?xml-stylesheet href="default.xsl" type="text/xml"?>
+HERE;
+
+/* Use xml_set_processing_instruction_handler() for generic implementation */
+$parser = xml_parser_create();
+xml_set_processing_instruction_handler($parser, $callback);
+xml_parse($parser, $xml, true);
+xml_parser_free($parser);
+
+?>
+--EXPECT--
+Trampoline for pi_handler
+Target: xml-stylesheet
+Data: href="default.xsl" type="text/xml"