From 5e0f3e7bd4e7035efdb8bc62cd61d4613e1ad6b1 Mon Sep 17 00:00:00 2001
From: Brion Vibber <brion@pobox.com>
Date: Thu, 7 Oct 2010 12:32:10 -0700
Subject: [PATCH] Workaround for regression in input validation due to more
 PCRE oddities. Recommend redoing common_validate_utf8() using something more
 reliable, perhaps. :P

---
 lib/util.php | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/lib/util.php b/lib/util.php
index 35fcfdb090..c05fcf15a2 100644
--- a/lib/util.php
+++ b/lib/util.php
@@ -919,7 +919,12 @@ function common_shorten_links($text, $always = false)
 function common_validate_utf8($str)
 {
     // preg_replace will return NULL on invalid UTF-8 input.
-    return preg_replace('//u', '', $str);
+    //
+    // Note: empty regex //u also caused NULL return on some
+    // production machines, but none of our test machines.
+    //
+    // This should be replaced with a more reliable check.
+    return preg_replace('/\x00/u', '', $str);
 }
 
 /**