this fixes #515

src/js/assets.js

@@ -307,6 +307,14 @@ var updateLocalChecksums = function() {
 var getRepoMetadata = function(callback) {
     callback = callback || nullFunc;
 
+    // https://github.com/gorhill/uBlock/issues/515
+    // Handle re-entrancy here, i.e. we MUST NOT tamper with the waiting list
+    // of callers, if any, except to add one at the end of the list.
+    if ( repoMetadata !== null && repoMetadata.waiting.length !== 0 ) {
+        repoMetadata.waiting.push(callback);
+        return;
+    }
+
     if ( exports.allowRemoteFetch && lastRepoMetaIsRemote === false ) {
         lastRepoMetaTimestamp = 0;
     }
@@ -314,11 +322,7 @@ var getRepoMetadata = function(callback) {
         repoMetadata = null;
     }
     if ( repoMetadata !== null ) {
-        if ( repoMetadata.waiting.length !== 0 ) {
-            repoMetadata.waiting.push(callback);
-        } else {
-            callback(repoMetadata);
-        }
+        callback(repoMetadata);
         return;
     }
 
@@ -356,9 +360,16 @@ var getRepoMetadata = function(callback) {
             updateLocalChecksums();
         }
         // Notify all waiting callers
-        while ( callback = repoMetadata.waiting.pop() ) {
-            callback(repoMetadata);
+        // https://github.com/gorhill/uBlock/issues/515
+        // VERY IMPORTANT: because of re-entrancy, we MUST:
+        // - process the waiting callers in a FIFO manner
+        // - not cache repoMetadata.waiting.length, we MUST use the live
+        //   value, because it can change while looping
+        // - not change the waiting list until they are all processed
+        for ( var i = 0; i < repoMetadata.waiting.length; i++ ) {
+            repoMetadata.waiting[i](repoMetadata);
         }
+        repoMetadata.waiting.length = 0;
     };
 
     var validateChecksums = function(details) {

src/js/mirrors.js

@@ -497,7 +497,7 @@ var load = function() {
     var loadContent = function(urlKey, hash) {
         var binKey = storageKeyFromHash(hash);
         var onContentReady = function(bin) {
-            if ( vAPI.lastError || bin.hasOwnProperty(binKey) === false ) {
+            if ( vAPI.lastError() || bin.hasOwnProperty(binKey) === false ) {
                 //console.debug('mirrors.load(): failed to load content "%s"', binKey);
                 removeMetadata(urlKey);
                 removeContent(binKey);

src/js/storage.js

@@ -418,6 +418,7 @@
 
         // https://github.com/gorhill/httpswitchboard/issues/15
         // Ensure localhost et al. don't end up in the ubiquitous blacklist.
+        // TODO: do this only if it's not an [Adblock] list
         line = line
             .replace(/\s+#.*$/, '')
             .toLowerCase()
@@ -594,10 +595,18 @@
     var µb = this;
     var fromSelfie = false;
 
+    // Filter lists
+    // Whitelist
+    var countdown = 2;
+
     // Final initialization steps after all needed assets are in memory.
     // - Initialize internal state with maybe already existing tabs.
     // - Schedule next update operation.
-    var onAllDone = function() {
+    var doCountdown = function() {
+        countdown -= 1;
+        if ( countdown !== 0 ) {
+            return;
+        }
         // https://github.com/gorhill/uBlock/issues/426
         // Important: remove barrier to remote fetching, this was useful only
         // for launch time.
@@ -610,16 +619,10 @@
         µb.updater.restart(µb.firstUpdateAfter);
     };
 
-    var filtersReady = false;
-    var whitelistReady = false;
-
     // Filters are in memory.
     // Filter engines need PSL to be ready.
     var onFiltersReady = function() {
-        filtersReady = true;
-        if ( whitelistReady ) {
-            onAllDone();
-        }
+        doCountdown();
     };
 
     // https://github.com/gorhill/uBlock/issues/226
@@ -627,10 +630,7 @@
     // Whitelist parser needs PSL to be ready.
     // gorhill 2014-12-15: not anymore
     var onWhitelistReady = function() {
-        whitelistReady = true;
-        if ( filtersReady ) {
-            onAllDone();
-        }
+        doCountdown();
     };
 
     // Load order because dependencies: