From 2b440f71ea79a15ff4f7b58fdcba9614e1045999 Mon Sep 17 00:00:00 2001
From: daniel <daniel.kinzler@wikimedia.de>
Date: Mon, 29 Oct 2012 18:38:11 +0100
Subject: [PATCH] (Bug 41244) Gracefully handle failure to load text blob.

This change fixes fatal errors ocurring when Revision::loadText
returns false because of a failure to load the text blob.
Revision::getContent() should simply return null in such a case.

Change-Id: I1e13de14ff15b124b5a2e07155d368595a16fda7
---
 includes/Revision.php                         | 29 ++++++++++++-------
 .../phpunit/includes/RevisionStorageTest.php  | 19 ++++++++++++
 2 files changed, 38 insertions(+), 10 deletions(-)

diff --git a/includes/Revision.php b/includes/Revision.php
index 02eec315ed..fd356e12c8 100644
--- a/includes/Revision.php
+++ b/includes/Revision.php
@@ -52,7 +52,7 @@ class Revision implements IDBAccessObject {
 	protected $mContentFormat;
 
 	/**
-	 * @var Content
+	 * @var Content|null|bool
 	 */
 	protected $mContent;
 
@@ -982,25 +982,30 @@ class Revision implements IDBAccessObject {
 	}
 
 	/**
-	 * Gets the content object for the revision
+	 * Gets the content object for the revision (or null on failure).
+	 *
+	 * Note that for mutable Content objects, each call to this method will return a
+	 * fresh clone.
 	 *
 	 * @since 1.21
-	 * @return Content|null
+	 * @return Content|null the Revision's content, or null on failure.
 	 */
 	protected function getContentInternal() {
 		if( is_null( $this->mContent ) ) {
 			// Revision is immutable. Load on demand:
-
-			$handler = $this->getContentHandler();
-			$format = $this->getContentFormat();
-
 			if( is_null( $this->mText ) ) {
-				// Load text on demand:
 				$this->mText = $this->loadText();
 			}
 
-			$this->mContent = ( $this->mText === null || $this->mText === false ) ? null
-				: $handler->unserializeContent( $this->mText, $format );
+			if ( $this->mText !== null && $this->mText !== false ) {
+				// Unserialize content
+				$handler = $this->getContentHandler();
+				$format = $this->getContentFormat();
+
+				$this->mContent = $handler->unserializeContent( $this->mText, $format );
+			} else {
+				$this->mContent = false; // negative caching!
+			}
 		}
 
 		// NOTE: copy() will return $this for immutable content objects
@@ -1399,7 +1404,11 @@ class Revision implements IDBAccessObject {
 	 * Lazy-load the revision's text.
 	 * Currently hardcoded to the 'text' table storage engine.
 	 *
+<<<<<<< HEAD
 	 * @return String|boolean the revision text, or false on failure
+=======
+	 * @return String|bool the revision's text, or false on failure
+>>>>>>> (Bug 41244) Gracefully handle failure to load text blob.
 	 */
 	protected function loadText() {
 		wfProfileIn( __METHOD__ );
diff --git a/tests/phpunit/includes/RevisionStorageTest.php b/tests/phpunit/includes/RevisionStorageTest.php
index fbaa34cee2..4fa42f35a2 100644
--- a/tests/phpunit/includes/RevisionStorageTest.php
+++ b/tests/phpunit/includes/RevisionStorageTest.php
@@ -268,6 +268,25 @@ class RevisionStorageTest extends MediaWikiTestCase {
 		$this->assertEquals( 'hello hello.', $rev->getText() );
 	}
 
+	/**
+	 * @covers Revision::getContent
+	 */
+	public function testGetContent_failure()
+	{
+		$rev = new Revision( array(
+			'page'       =>  $this->the_page->getId(),
+			'content_model' => $this->the_page->getContentModel(),
+			'text_id' => 123456789, // not in the test DB
+		) );
+
+		$this->assertNull( $rev->getContent(),
+			"getContent() should return null if the revision's text blob could not be loaded." );
+
+		//NOTE: check this twice, once for lazy initialization, and once with the cached value.
+		$this->assertNull( $rev->getContent(),
+			"getContent() should return null if the revision's text blob could not be loaded." );
+	}
+
 	/**
 	 * @covers Revision::getContent
 	 */
-- 
2.20.1