From 7ff8529984f993573ca44f1b7c2a573188bb36b6 Mon Sep 17 00:00:00 2001
From: Aaron Schulz <aschulz@wikimedia.org>
Date: Thu, 6 Jul 2017 16:23:32 -0700
Subject: [PATCH] Avoid high edit stash TTLs when a user signature was used

This adds a new ParserOuput user-signature tracking flag.

Bug: T84843
Change-Id: I77de05849c15e17ee2b9b31b34172f4b6a49a38e
---
 includes/api/ApiStashEdit.php |  7 +++++++
 includes/parser/Parser.php    | 16 ++++++++++------
 2 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/includes/api/ApiStashEdit.php b/includes/api/ApiStashEdit.php
index c7a00c6464..d03fca87a0 100644
--- a/includes/api/ApiStashEdit.php
+++ b/includes/api/ApiStashEdit.php
@@ -44,6 +44,7 @@ class ApiStashEdit extends ApiBase {
 
 	const PRESUME_FRESH_TTL_SEC = 30;
 	const MAX_CACHE_TTL = 300; // 5 minutes
+	const MAX_SIGNATURE_TTL = 60;
 
 	public function execute() {
 		$user = $this->getUser();
@@ -391,6 +392,12 @@ class ApiStashEdit extends ApiBase {
 		// Put an upper limit on the TTL for sanity to avoid extreme template/file staleness.
 		$since = time() - wfTimestamp( TS_UNIX, $parserOutput->getTimestamp() );
 		$ttl = min( $parserOutput->getCacheExpiry() - $since, self::MAX_CACHE_TTL );
+
+		// Avoid extremely stale user signature timestamps (T84843)
+		if ( $parserOutput->getFlag( 'user-signature' ) ) {
+			$ttl = min( $ttl, self::MAX_SIGNATURE_TTL );
+		}
+
 		if ( $ttl <= 0 ) {
 			return [ null, 0, 'no_ttl' ];
 		}
diff --git a/includes/parser/Parser.php b/includes/parser/Parser.php
index 9ea65e013d..4a78ff8321 100644
--- a/includes/parser/Parser.php
+++ b/includes/parser/Parser.php
@@ -4502,12 +4502,16 @@ class Parser {
 		# which may corrupt this parser instance via its wfMessage()->text() call-
 
 		# Signatures
-		$sigText = $this->getUserSig( $user );
-		$text = strtr( $text, [
-			'~~~~~' => $d,
-			'~~~~' => "$sigText $d",
-			'~~~' => $sigText
-		] );
+		if ( strpos( $text, '~~~' ) !== false ) {
+			$sigText = $this->getUserSig( $user );
+			$text = strtr( $text, [
+				'~~~~~' => $d,
+				'~~~~' => "$sigText $d",
+				'~~~' => $sigText
+			] );
+			# The main two signature forms used above are time-sensitive
+			$this->mOutput->setFlag( 'user-signature' );
+		}
 
 		# Context links ("pipe tricks"): [[|name]] and [[name (context)|]]
 		$tc = '[' . Title::legalChars() . ']';
-- 
2.20.1