From: daniel <dkinzler@wikimedia.org>
Date: Thu, 4 Oct 2018 10:49:50 +0000 (+0200)
Subject: Avoid fatal when finding no base revision for a null revision.
X-Git-Tag: 1.34.0-rc.0~3888^2
X-Git-Url: http://git.cyclocoop.org/?a=commitdiff_plain;h=539cb2816aecee668c41b418552d75cc6329e0ab;p=lhc%2Fweb%2Fwiklou.git

Avoid fatal when finding no base revision for a null revision.

Bug: T205675
Change-Id: Iae67649a1be9597086033ad34d9d00556ba35730
---

diff --git a/includes/MovePage.php b/includes/MovePage.php
index 2ad315811c..ecd12c6f8e 100644
--- a/includes/MovePage.php
+++ b/includes/MovePage.php
@@ -536,7 +536,8 @@ class MovePage {
 		# Save a null revision in the page's history notifying of the move
 		$nullRevision = Revision::newNullRevision( $dbw, $oldid, $comment, true, $user );
 		if ( !is_object( $nullRevision ) ) {
-			throw new MWException( 'No valid null revision produced in ' . __METHOD__ );
+			throw new MWException( 'Failed to create null revision while moving page ID '
+				. $oldid . ' to ' . $nt->getPrefixedDBkey() );
 		}
 
 		$nullRevId = $nullRevision->insertOn( $dbw );
diff --git a/includes/Revision.php b/includes/Revision.php
index a55b1c4d79..e45c6dce0d 100644
--- a/includes/Revision.php
+++ b/includes/Revision.php
@@ -1179,7 +1179,7 @@ class Revision implements IDBAccessObject {
 
 		$rec = self::getRevisionStore()->newNullRevision( $dbw, $title, $comment, $minor, $user );
 
-		return new Revision( $rec );
+		return $rec ? new Revision( $rec ) : null;
 	}
 
 	/**
diff --git a/includes/Storage/RevisionStore.php b/includes/Storage/RevisionStore.php
index bab1b5e38e..d9db8bd2c2 100644
--- a/includes/Storage/RevisionStore.php
+++ b/includes/Storage/RevisionStore.php
@@ -48,6 +48,7 @@ use Psr\Log\LoggerInterface;
 use Psr\Log\NullLogger;
 use RecentChange;
 use Revision;
+use RuntimeException;
 use stdClass;
 use Title;
 use User;
@@ -1058,13 +1059,15 @@ class RevisionStore
 	) {
 		$this->checkDatabaseWikiId( $dbw );
 
+		$pageId = $title->getArticleID();
+
 		// T51581: Lock the page table row to ensure no other process
 		// is adding a revision to the page at the same time.
 		// Avoid locking extra tables, compare T191892.
 		$pageLatest = $dbw->selectField(
 			'page',
 			'page_latest',
-			[ 'page_id' => $title->getArticleID() ],
+			[ 'page_id' => $pageId ],
 			__METHOD__,
 			[ 'FOR UPDATE' ]
 		);
@@ -1081,6 +1084,15 @@ class RevisionStore
 			$title
 		);
 
+		if ( !$oldRevision ) {
+			$msg = "Failed to load latest revision ID $pageLatest of page ID $pageId.";
+			$this->logger->error(
+				$msg,
+				[ 'exception' => new RuntimeException( $msg ) ]
+			);
+			return null;
+		}
+
 		// Construct the new revision
 		$timestamp = wfTimestampNow(); // TODO: use a callback, so we can override it for testing.
 		$newRevision = MutableRevisionRecord::newFromParentRevision( $oldRevision );