Bug 344523: AddSearchProvider doesn't check if provider already installed (installation of an engine with the same name as an already-installed engine fails silently), r=mconnor

browser/components/search/nsSearchService.js

@@ -1124,7 +1124,7 @@ Engine.prototype = {
      * Handle an error during the load of an engine by prompting the user to
      * notify him that the load failed.
      */
-    function onError() {
+    function onError(aErrorString, aTitleString) {
       if (aEngine._engineToUpdate) {
         // We're in an update, so just fail quietly
         LOG("updating " + aEngine._engineToUpdate.name + " failed");
@@ -1132,11 +1132,15 @@ Engine.prototype = {
       }
       var sbs = Cc["@mozilla.org/intl/stringbundle;1"].
                 getService(Ci.nsIStringBundleService);
-      var searchBundle = sbs.createBundle(SEARCH_BUNDLE);
+
       var brandBundle = sbs.createBundle(BRAND_BUNDLE);
       var brandName = brandBundle.GetStringFromName("brandShortName");
-      var title = searchBundle.GetStringFromName("error_loading_engine_title");
-      var text = searchBundle.formatStringFromName("error_loading_engine_msg2",
+
+      var searchBundle = sbs.createBundle(SEARCH_BUNDLE);
+      var msgStringName = aErrorString || "error_loading_engine_msg2";
+      var titleStringName = aTitleString || "error_loading_engine_title";
+      var title = searchBundle.GetStringFromName(titleStringName);
+      var text = searchBundle.formatStringFromName(msgStringName,
                                                    [brandName, aEngine._location],
                                                    2);
 
@@ -1192,6 +1196,18 @@ Engine.prototype = {
       return;
     }
 
+    // Check to see if this is a duplicate engine. If we're confirming the
+    // engine load, then we display a "this is a duplicate engine" prompt,
+    // otherwise we fail silently.
+    var ss = Cc["@mozilla.org/browser/search-service;1"].
+             getService(Ci.nsIBrowserSearchService);
+    if (ss.getEngineByName(aEngine.name)) {
+      if (aEngine._confirm)
+        onError("error_duplicate_engine_msg", "error_invalid_engine_title");
+      LOG("_onLoad: duplicate engine found, bailing");
+      return;
+    }
+
     // If requested, confirm the addition now that we have the title.
     if (aEngine._confirm) {
       var confirmation = aEngine._confirmAddEngine();

browser/locales/en-US/chrome/browser/search.properties

@@ -14,6 +14,8 @@ addEngineAddButtonLabel=Add
 error_loading_engine_title=Download Error
 # LOCALIZATION NOTE (error_loading_engine_msg2): %1$S = brandShortName, %2$S = location
 error_loading_engine_msg2=%S could not download the search plugin from:\n%S
+error_duplicate_engine_msg=%S could not install the search plugin from "%S" because an engine with the same name already exists.
+
 error_invalid_engine_title=Install Error
 # LOCALIZATION NOTE (error_invalid_engine_msg): %S = brandShortName
 error_invalid_engine_msg=This search engine isn't supported by %S and can't be installed.