Beware that getContent() may return null

Before the introduction of the content handler, missing content was
signified by getText() returning null instead of a string. null will
work much like an empty string in most contexts, so in many places,
it was not checked explcitely whether the conent was null.

Now, when getContent() returns null, this often caused a fatal error,
because the code would access whatever getContent() returned as an object,
without checking whether it was null (because no such check was performed
previously, when the content was represented as a string).

This check introduces explicite checks for getContent() returning null
in the most essential core classes.

Change-Id: I551a90b0b67b8edc7570ca5d252ecc1de903f097

includes/Article.php

@@ -688,7 +688,7 @@ class Article extends Page {
 						$outputDone = true;
 					} else {
 						$content = $this->getContentObject();
-						$rt = $content->getRedirectChain();
+						$rt = $content ? $content->getRedirectChain() : null;
 						if ( $rt ) {
 							wfDebug( __METHOD__ . ": showing redirect=no page\n" );
 							# Viewing a redirect page (e.g. with parameter redirect=no)
@@ -842,10 +842,14 @@ class Article extends Page {
 				'clearyourcache' );
 		}
 
-		// Give hooks a chance to customise the output
-		if ( ContentHandler::runLegacyHooks( 'ShowRawCssJs', array( $this->fetchContentObject(), $this->getTitle(), $outputPage ) ) ) {
-			$po = $this->mContentObject->getParserOutput( $this->getTitle() );
-			$outputPage->addHTML( $po->getText() );
+		$this->fetchContentObject();
+
+		if ( $this->mContentObject ) {
+			// Give hooks a chance to customise the output
+			if ( ContentHandler::runLegacyHooks( 'ShowRawCssJs', array( $this->mContentObject, $this->getTitle(), $outputPage ) ) ) {
+				$po = $this->mContentObject->getParserOutput( $this->getTitle() );
+				$outputPage->addHTML( $po->getText() );
+			}
 		}
 	}
 

includes/Revision.php

@@ -999,7 +999,8 @@ class Revision implements IDBAccessObject {
 				$this->mText = $this->loadText();
 			}
 
-			$this->mContent = is_null( $this->mText ) ? null : $handler->unserializeContent( $this->mText, $format );
+			$this->mContent = ( $this->mText === null || $this->mText === false ) ? null
+				: $handler->unserializeContent( $this->mText, $format );
 		}
 
 		return $this->mContent->copy(); // NOTE: copy() will return $this for immutable content objects
@@ -1377,7 +1378,7 @@ class Revision implements IDBAccessObject {
 
 		$content = $this->getContent( Revision::RAW );
 
-		if ( !$content->isValid() ) {
+		if ( !$content || !$content->isValid() ) {
 			$t = $title->getPrefixedDBkey();
 
 			throw new MWException( "Content of $t is not valid! Content model is $model" );
@@ -1397,7 +1398,7 @@ class Revision implements IDBAccessObject {
 	 * Lazy-load the revision's text.
 	 * Currently hardcoded to the 'text' table storage engine.
 	 *
-	 * @return String
+	 * @return String|boolean the revision text, or false on failure
 	 */
 	protected function loadText() {
 		wfProfileIn( __METHOD__ );

includes/Title.php

@@ -3981,7 +3981,7 @@ class Title {
 		$content = $rev->getContent();
 		# Does the redirect point to the source?
 		# Or is it a broken self-redirect, usually caused by namespace collisions?
-		$redirTitle = $content->getRedirectTarget();
+		$redirTitle = $content ? $content->getRedirectTarget() : null;
 
 		if ( $redirTitle ) {
 			if ( $redirTitle->getPrefixedDBkey() != $this->getPrefixedDBkey() &&

includes/WikiPage.php

@@ -1237,8 +1237,8 @@ class WikiPage extends Page implements IDBAccessObject {
 		wfProfileIn( __METHOD__ );
 
 		$content = $revision->getContent();
-		$len = $content->getSize();
-		$rt = $content->getUltimateRedirectTarget();
+		$len = $content ? $content->getSize() : 0;
+		$rt = $content ? $content->getUltimateRedirectTarget() : null;
 
 		$conditions = array( 'page_id' => $this->getId() );
 
@@ -1469,11 +1469,6 @@ class WikiPage extends Page implements IDBAccessObject {
 			// Bug 30711: always use current version when adding a new section
 			if ( is_null( $edittime ) || $section == 'new' ) {
 				$oldContent = $this->getContent();
-				if ( ! $oldContent ) {
-					wfDebug( __METHOD__ . ": no page text\n" );
-					wfProfileOut( __METHOD__ );
-					return null;
-				}
 			} else {
 				$dbw = wfGetDB( DB_MASTER );
 				$rev = Revision::loadFromTimestamp( $dbw, $this->mTitle, $edittime );
@@ -1488,6 +1483,13 @@ class WikiPage extends Page implements IDBAccessObject {
 				$oldContent = $rev->getContent();
 			}
 
+			if ( ! $oldContent ) {
+				wfDebug( __METHOD__ . ": no page text\n" );
+				wfProfileOut( __METHOD__ );
+				return null;
+			}
+
+			//FIXME: $oldContent might be null?
 			$newContent = $oldContent->replaceSection( $section, $sectionContent, $sectionTitle );
 		}
 
@@ -1852,6 +1854,10 @@ class WikiPage extends Page implements IDBAccessObject {
 			# Bug 37225: use accessor to get the text as Revision may trim it
 			$content = $revision->getContent(); // sanity; get normalized version
 
+			if ( $content ) {
+				$newsize = $content->getSize();
+			}
+
 			# Update the page record with revision data
 			$this->updateRevisionOn( $dbw, $revision, 0 );
 
@@ -1864,7 +1870,7 @@ class WikiPage extends Page implements IDBAccessObject {
 					$this->mTitle->getUserPermissionsErrors( 'autopatrol', $user ) );
 				# Add RC row to the DB
 				$rc = RecentChange::notifyNew( $now, $this->mTitle, $isminor, $user, $summary, $bot,
-					'', $content->getSize(), $revisionId, $patrolled );
+					'', $newsize, $revisionId, $patrolled );
 
 				# Log auto-patrolled edits
 				if ( $patrolled ) {
@@ -1956,7 +1962,7 @@ class WikiPage extends Page implements IDBAccessObject {
 	 * @since 1.21
 	 */
 	public function prepareContentForEdit( Content $content, $revid = null, User $user = null, $serialization_format = null ) {
-		global $wgParser, $wgContLang, $wgUser;
+		global $wgContLang, $wgUser;
 		$user = is_null( $user ) ? $wgUser : $user;
 		//XXX: check $user->getId() here???
 
@@ -1977,23 +1983,21 @@ class WikiPage extends Page implements IDBAccessObject {
 		$edit = (object)array();
 		$edit->revid = $revid;
 
-		$edit->pstContent = $content->preSaveTransform( $this->mTitle, $user, $popts );
-		$edit->pst = $edit->pstContent->serialize( $serialization_format ); #XXX: do we need this??
+		$edit->pstContent = $content ? $content->preSaveTransform( $this->mTitle, $user, $popts ) : null;
+
 		$edit->format = $serialization_format;
-
 		$edit->popts = $this->makeParserOptions( 'canonical' );
-
-		$edit->output = $edit->pstContent->getParserOutput( $this->mTitle, $revid, $edit->popts );
+		$edit->output = $edit->pstContent ? $edit->pstContent->getParserOutput( $this->mTitle, $revid, $edit->popts ) : null;
 
 		$edit->newContent = $content;
 		$edit->oldContent = $this->getContent( Revision::RAW );
 
 		#NOTE: B/C for hooks! don't use these fields!
-		$edit->newText = ContentHandler::getContentText( $edit->newContent );
+		$edit->newText = $edit->newContent ? ContentHandler::getContentText( $edit->newContent ) : '';
 		$edit->oldText = $edit->oldContent ? ContentHandler::getContentText( $edit->oldContent ) : '';
+		$edit->pst = $edit->pstContent ? $edit->pstContent->serialize( $serialization_format ) : '';
 
 		$this->mPreparedEdit = $edit;
-
 		return $edit;
 	}
 
@@ -2038,8 +2042,10 @@ class WikiPage extends Page implements IDBAccessObject {
 		}
 
 		# Update the links tables and other secondary data
-		$updates = $content->getSecondaryDataUpdates( $this->getTitle(), null, true, $editInfo->output );
-		DataUpdate::runUpdates( $updates );
+		if ( $content ) {
+			$updates = $content->getSecondaryDataUpdates( $this->getTitle(), null, true, $editInfo->output );
+			DataUpdate::runUpdates( $updates );
+		}
 
 		wfRunHooks( 'ArticleEditUpdates', array( &$this, &$editInfo, $options['changed'] ) );
 
@@ -2111,7 +2117,7 @@ class WikiPage extends Page implements IDBAccessObject {
 
 		if ( $this->mTitle->getNamespace() == NS_MEDIAWIKI ) {
 			#XXX: could skip pseudo-messages like js/css here, based on content model.
-			$msgtext = $content->getWikitextForTransclusion();
+			$msgtext = $content ? $content->getWikitextForTransclusion() : null;
 			if ( $msgtext === false || $msgtext === null ) $msgtext = '';
 
 			MessageCache::singleton()->replace( $shortTitle, $msgtext );

includes/diff/DifferenceEngine.php

@@ -522,8 +522,10 @@ class DifferenceEngine extends ContextSource {
 				if ( ContentHandler::runLegacyHooks( 'ShowRawCssJs', array( $this->mNewContent, $this->mNewPage, $out ) ) ) {
 					// NOTE: deprecated hook, B/C only
 					// use the content object's own rendering
-					$po = $this->mNewRev->getContent()->getParserOutput( $this->mNewRev->getTitle(), $this->mNewRev->getId() );
-					$out->addHTML( $po->getText() );
+					$cnt = $this->mNewRev->getContent();
+					$po = $cnt ? $cnt->getParserOutput( $this->mNewRev->getTitle(), $this->mNewRev->getId() ) : null;
+					$txt = $po ? $po->getText() : '';
+					$out->addHTML( $txt );
 				}
 			} elseif( !wfRunHooks( 'ArticleContentViewCustom', array( $this->mNewContent, $this->mNewPage, $out ) ) ) {
 				// Handled by extension
@@ -545,7 +547,7 @@ class DifferenceEngine extends ContextSource {
 				$parserOutput = $this->getParserOutput( $wikiPage, $this->mNewRev );
 
 				# Also try to load it as a redirect
-				$rt = $this->mNewContent->getRedirectTarget();
+				$rt = $this->mNewContent ? $this->mNewContent->getRedirectTarget() : null;
 
 				if ( $rt ) {
 					$article = Article::newFromTitle( $this->mNewPage, $this->getContext() );
@@ -1169,13 +1171,13 @@ class DifferenceEngine extends ContextSource {
 		}
 		if ( $this->mOldRev ) {
 			$this->mOldContent = $this->mOldRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
-			if ( $this->mOldContent === false ) {
+			if ( $this->mOldContent === null ) {
 				return false;
 			}
 		}
 		if ( $this->mNewRev ) {
 			$this->mNewContent = $this->mNewRev->getContent( Revision::FOR_THIS_USER, $this->getUser() );
-			if ( $this->mNewContent === false ) {
+			if ( $this->mNewContent === null ) {
 				return false;
 			}
 		}

includes/job/jobs/DoubleRedirectJob.php

@@ -94,7 +94,7 @@ class DoubleRedirectJob extends Job {
 			return true;
 		}
 		$content = $targetRev->getContent();
-		$currentDest = $content->getRedirectTarget();
+		$currentDest = $content ? $content->getRedirectTarget() : null;
 		if ( !$currentDest || !$currentDest->equals( $this->redirTitle ) ) {
 			wfDebug( __METHOD__.": Redirect has changed since the job was queued\n" );
 			return true;

includes/job/jobs/RefreshLinksJob.php

@@ -70,18 +70,17 @@ class RefreshLinksJob extends Job {
 	}
 
 	public static function runForTitleInternal( Title $title, Revision $revision, $fname ) {
-		global $wgContLang;
+		wfProfileIn( $fname );
+		$content = $revision->getContent( Revision::RAW );
 
-		wfProfileIn( $fname . '-parse' );
-		$options = ParserOptions::newFromUserAndLang( new User, $wgContLang );
-		$content = $revision->getContent();
-		$parserOutput = $content->getParserOutput( $title, $revision->getId(), $options, false );
-		wfProfileOut( $fname . '-parse' );
+		if ( !$content ) {
+			// if there is no content, pretend the content is empty
+			$content = $revision->getContentHandler()->makeEmptyContent();
+		}
 
-		wfProfileIn( $fname . '-update' );
-		$updates = $content->getSecondaryDataUpdates( $title, null, false, $parserOutput  );
+		$updates = $content->getSecondaryDataUpdates( $title, null, false );
 		DataUpdate::runUpdates( $updates );
-		wfProfileOut( $fname . '-update' );
+		wfProfileOut( $fname );
 	}
 }
 

includes/parser/Parser.php

@@ -3617,7 +3617,7 @@ class Parser {
 
 			if ( $rev ) {
 				$content = $rev->getContent();
-				$text = $content->getWikitextForTransclusion();
+				$text = $content ? $content->getWikitextForTransclusion() : null;
 
 				if ( $text === false || $text === null ) {
 					$text = false;

includes/resourceloader/ResourceLoaderWikiModule.php

@@ -77,10 +77,16 @@ abstract class ResourceLoaderWikiModule extends ResourceLoaderModule {
 		}
 
 		$content = $revision->getContent( Revision::RAW );
+
+		if ( !$content ) {
+			wfDebug( __METHOD__ . "failed to load content of JS/CSS page!\n" );
+			return null;
+		}
+
 		$model = $content->getModel();
 
 		if ( $model !== CONTENT_MODEL_CSS && $model !== CONTENT_MODEL_JAVASCRIPT ) {
-			wfDebug( __METHOD__ . "bad content model #$model for JS/CSS page!\n" );
+			wfDebug( __METHOD__ . "bad content model $model for JS/CSS page!\n" );
 			return null;
 		}
 

includes/search/SearchEngine.php

@@ -795,7 +795,7 @@ class SearchResult {
 				//TODO: if we could plug in some code that knows about special content models *and* about
 				//      special features of the search engine, the search could benefit.
 				$content = $this->mRevision->getContent();
-				$this->mText = $content->getTextForSearchIndex();
+				$this->mText = $content ? $content->getTextForSearchIndex() : '';
 			} else { // TODO: can we fetch raw wikitext for commons images?
 				$this->mText = '';
 			}