From: Bartosz Dziewoński <matma.rex@gmail.com>
Date: Mon, 30 Jul 2018 19:37:45 +0000 (+0200)
Subject: Use multibyte-aware truncation to avoid invalid UTF-8 in cl_sortkey_prefix
X-Git-Tag: 1.34.0-rc.0~4622^2
X-Git-Url: http://git.cyclocoop.org/?a=commitdiff_plain;h=62f7cdc33169d8abf590e8e2f70c8ddf43aeec14;p=lhc%2Fweb%2Fwiklou.git

Use multibyte-aware truncation to avoid invalid UTF-8 in cl_sortkey_prefix

The invalid UTF-8 could cause incorrect sorting of affected pages in
category lists on wikis using UCA collations. On my local testing
wiki, the generated cl_sortkey was just 0x30 regardless of the value
of cl_sortkey_prefix.

This doesn't fix existing bad data in the database. It will only be
updated when the affected page is edited (or null-edited).

The cl_timestamp field will also be updated when that happens, which
apparently may affect Wikinews' DynamicPageList extension, according
to comments on T27254. This is not easily avoidable.

Bug: T200623
Change-Id: I4baa9ea3c7f831ff3c9c51e6b8e5d66e7da42a91
---

diff --git a/includes/deferred/LinksUpdate.php b/includes/deferred/LinksUpdate.php
index 39e8bd989e..141888cda6 100644
--- a/includes/deferred/LinksUpdate.php
+++ b/includes/deferred/LinksUpdate.php
@@ -141,14 +141,9 @@ class LinksUpdate extends DataUpdate implements EnqueueableDataUpdate {
 		}
 
 		foreach ( $this->mCategories as &$sortkey ) {
-			# If the sortkey is longer then 255 bytes,
-			# it truncated by DB, and then doesn't get
-			# matched when comparing existing vs current
-			# categories, causing T27254.
-			# Also. substr behaves weird when given "".
-			if ( $sortkey !== '' ) {
-				$sortkey = substr( $sortkey, 0, 255 );
-			}
+			# If the sortkey is longer then 255 bytes, it is truncated by DB, and then doesn't match
+			# when comparing existing vs current categories, causing T27254.
+			$sortkey = mb_strcut( $sortkey, 0, 255 );
 		}
 
 		$this->mRecursive = $recursive;