mw.loader.store: Wrap script eval in try/catch

All sorts of things can happen to our localStorage entry, from
clueless users through malicious scripts and browser bugs to hard disk
failures. Let's not explode irrecoverably when the code from store
refuses to execute.

Bug: 57567
Change-Id: I1b40a82595fe37dfeeb3648f7ecfbcac01bf9079

diff --git a/resources/mediawiki/mediawiki.js b/resources/mediawiki/mediawiki.js
index 26f84f5..f2b1901 100644 (file)
--- a/resources/mediawiki/mediawiki.js
+++ b/resources/mediawiki/mediawiki.js
@@ -1405,7 +1405,7 @@ var mw = ( function ( $, undefined ) {
                                 */
                                work: function () {
                                        var     reqBase, splits, maxQueryLength, q, b, bSource, bGroup, bSourceGroup,
-                                               source, concatSource, group, g, i, modules, maxVersion, sourceLoadScript,
+                                               source, concatSource, origBatch, group, g, i, modules, maxVersion, sourceLoadScript,
                                                currReqBase, currReqBaseLength, moduleMap, l,
                                                lastDotIndex, prefix, suffix, bytesAdded, async;
 
@@ -1435,6 +1435,7 @@ var mw = ( function ( $, undefined ) {
                                        mw.loader.store.init();
                                        if ( mw.loader.store.enabled ) {
                                                concatSource = [];
+                                               origBatch = batch;
                                                batch = $.grep( batch, function ( module ) {
                                                        var source = mw.loader.store.get( module );
                                                        if ( source ) {
@@ -1443,7 +1444,29 @@ var mw = ( function ( $, undefined ) {
                                                        }
                                                        return true;
                                                } );
-                                               $.globalEval( concatSource.join( ';' ) );
+                                               try {
+                                                       $.globalEval( concatSource.join( ';' ) );
+                                               } catch ( err ) {
+                                                       // Not good, the cached mw.loader.implement calls failed! This should
+                                                       // never happen, barring ResourceLoader bugs, browser bugs and PEBKACs.
+                                                       // Depending on how corrupt the string is, it is likely that some
+                                                       // modules' implement() succeeded while the ones after the error will
+                                                       // never run and leave their modules in the 'loading' state forever.
+
+                                                       // Since this is an error not caused by an individual module but by
+                                                       // something that infected the implement call itself, don't take any
+                                                       // risks and clear everything in this cache.
+                                                       mw.loader.store.clear();
+                                                       // Re-add the ones still pending back to the batch and let the server
+                                                       // repopulate these modules to the cache.
+                                                       // This means that at most one module will be useless (the one that had
+                                                       // the error) instead of all of them.
+                                                       log( 'Error while evaluating data from mw.loader.store', err );
+                                                       origBatch = $.grep( origBatch, function ( module ) {
+                                                               return registry[module].state === 'loading';
+                                                       } );
+                                                       batch = batch.concat( origBatch );
+                                               }
                                        }
 
                                        // Early exit if there's nothing to load...
@@ -2093,6 +2116,14 @@ var mw = ( function ( $, undefined ) {
                                                }
                                        },
 
+                                       /**
+                                        * Clear the entire module store right now.
+                                        */
+                                       clear: function () {
+                                               mw.loader.store.items = {};
+                                               localStorage.removeItem( mw.loader.store.getStoreKey() );
+                                       },
+
                                        /**
                                         * Sync modules to localStorage.
                                         *