From beeef2e82245ff9ff2fcc73a7fb8c55f7eee45f5 Mon Sep 17 00:00:00 2001
From: Brion Vibber <brion@users.mediawiki.org>
Date: Tue, 11 Aug 2009 23:23:46 +0000
Subject: [PATCH] Add an install/update-time test for the PHP+libxml2 horrible
 XML input corruption bug. Now need to find a known-bad system to confirm the
 test on :D

---
 install-utils.inc | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/install-utils.inc b/install-utils.inc
index 473cdf56a7..d8f73ceb04 100644
--- a/install-utils.inc
+++ b/install-utils.inc
@@ -33,6 +33,16 @@ function install_version_checks() {
 			"or higher. ABORTING. (http://bugs.php.net/bug.php?id=34879 for details)\n";
 		die( -1 );
 	}
+	
+	$test = new PhpXmlBugTester();
+	if( !$test->ok ) {
+		echo "Your system has a combination of PHP and libxml2 versions which is buggy\n" .
+			"and can cause hidden data corruption in MediaWiki and other web apps.\n" .
+			"Upgrade to PHP 5.2.9 or later and libxml2 2.7.2 or later!\n" .
+			"ABORTING (http://bugs.php.net/bug.php?id=45996 for details).\n";
+		die( -1 );
+	}
+	
 
 	global $wgCommandLineMode;
 	$wgCommandLineMode = true;
@@ -40,6 +50,28 @@ function install_version_checks() {
 	@set_time_limit( 0 );
 }
 
+/**
+ * Test for PHP+libxml2 bug which breaks XML input subtly with certain versions.
+ * http://bugs.php.net/bug.php?id=45996
+ * Known fixed with PHP 5.2.9 + libxml2-2.7.3
+ */
+class PhpXmlBugTester {
+	var $parsedData = '';
+	var $ok = false;
+	function __construct() {
+		$charData = '<b>c</b>';
+		$xml = '<a>' . htmlspecialchars( $charData ) . '</a>';
+		
+		$parser = xml_parser_create();
+		xml_set_character_data_handler( $parser, array( $this, 'chardata' ) );
+		$parsedOk = xml_parse($parser, $xml, true);
+		$this->ok = $parsedOk && ($this->parsedData == $charData);
+	}
+	function chardata($parser, $data) {
+		$this->parsedData .= $data;
+	}
+}
+
 function readconsole( $prompt = '' ) {
 	static $isatty = null;
 	if ( is_null( $isatty ) ) {
-- 
2.20.1