From 0e1b52a40e15f229e4920945350b77ce09b1c9b2 Mon Sep 17 00:00:00 2001
From: Arlo Breault <abreault@wikimedia.org>
Date: Mon, 26 Jun 2017 19:20:31 -0400
Subject: [PATCH] Make multiple colons escaping interlanguage links invalid,
 consistently

 * Right now, one or two are permitted.  This patch limits it to one.
   The current behaviour seems more a byproduct of refactoring than an
   explicit goal.

 * Note that this will break links on a handful of pages surfaced in
   Parsoid's roundtrip testing.

Change-Id: Icabd34bbf15781bb891bd8e0c079d1a65eb28595
---
 includes/parser/Parser.php             | 14 +++++++-------
 includes/title/MediaWikiTitleCodec.php |  3 ++-
 tests/parser/parserTests.txt           | 13 +++++++++++++
 3 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/includes/parser/Parser.php b/includes/parser/Parser.php
index 9ea65e013d..0cc2aac87c 100644
--- a/includes/parser/Parser.php
+++ b/includes/parser/Parser.php
@@ -2240,12 +2240,6 @@ class Parser {
 				$link = $origLink;
 			}
 
-			$noforce = ( substr( $origLink, 0, 1 ) !== ':' );
-			if ( !$noforce ) {
-				# Strip off leading ':'
-				$link = substr( $link, 1 );
-			}
-
 			$unstrip = $this->mStripState->unstripNoWiki( $link );
 			$nt = is_string( $unstrip ) ? Title::newFromText( $unstrip ) : null;
 			if ( $nt === null ) {
@@ -2256,6 +2250,8 @@ class Parser {
 			$ns = $nt->getNamespace();
 			$iw = $nt->getInterwiki();
 
+			$noforce = ( substr( $origLink, 0, 1 ) !== ':' );
+
 			if ( $might_be_img ) { # if this is actually an invalid link
 				if ( $ns == NS_FILE && $noforce ) { # but might be an image
 					$found = false;
@@ -2300,6 +2296,10 @@ class Parser {
 			$wasblank = ( $text == '' );
 			if ( $wasblank ) {
 				$text = $link;
+				if ( !$noforce ) {
+					# Strip off leading ':'
+					$text = substr( $text, 1 );
+				}
 			} else {
 				# T6598 madness. Handle the quotes only if they come from the alternate part
 				# [[Lista d''e paise d''o munno]] -> <a href="...">Lista d''e paise d''o munno</a>
@@ -2324,7 +2324,7 @@ class Parser {
 					}
 
 					$s = rtrim( $s . $prefix );
-					$s .= trim( $trail, "\n" ) == '' ? '': $prefix . $trail;
+					$s .= trim( $trail, "\n" ) == '' ? '' : $prefix . $trail;
 					continue;
 				}
 
diff --git a/includes/title/MediaWikiTitleCodec.php b/includes/title/MediaWikiTitleCodec.php
index 0fff97cb26..dd8b97546b 100644
--- a/includes/title/MediaWikiTitleCodec.php
+++ b/includes/title/MediaWikiTitleCodec.php
@@ -301,7 +301,7 @@ class MediaWikiTitleCodec implements TitleFormatter, TitleParser {
 
 		# Initial colon indicates main namespace rather than specified default
 		# but should not create invalid {ns,title} pairs such as {0,Project:Foo}
-		if ( $dbkey !== '' && ':' == $dbkey[0] ) {
+		if ( $dbkey !== '' && $dbkey[0] == ':' ) {
 			$parts['namespace'] = NS_MAIN;
 			$dbkey = substr( $dbkey, 1 ); # remove the colon but continue processing
 			$dbkey = trim( $dbkey, '_' ); # remove any subsequent whitespace
@@ -368,6 +368,7 @@ class MediaWikiTitleCodec implements TitleFormatter, TitleParser {
 					if ( $dbkey !== '' && $dbkey[0] == ':' ) {
 						$parts['namespace'] = NS_MAIN;
 						$dbkey = substr( $dbkey, 1 );
+						$dbkey = trim( $dbkey, '_' );
 					}
 				}
 				# If there's no recognized interwiki or namespace,
diff --git a/tests/parser/parserTests.txt b/tests/parser/parserTests.txt
index 44bcdffeb4..f7629cd472 100644
--- a/tests/parser/parserTests.txt
+++ b/tests/parser/parserTests.txt
@@ -8741,6 +8741,19 @@ Blah blah blah
 <a rel="mw:ExtLink" href="http://zh.wikipedia.org/wiki/Chinese" title="zh:Chinese"> zh : Chinese </a></p>
 !! end
 
+!! test
+Multiple colons escaping interlanguage links
+!! wikitext
+[[:es:Spanish]]
+[[::es:Spanish]]
+[[:::es:Spanish]]
+!! html/php
+<p><a href="http://es.wikipedia.org/wiki/Spanish" class="extiw" title="es:Spanish">es:Spanish</a>
+[[::es:Spanish]]
+[[:::es:Spanish]]
+</p>
+!! end
+
 ## parsoid html2wt will normalize the space to _
 !! test
 Space and question mark encoding in interlanguage links (T95473)
-- 
2.20.1