Doing a QI in JS to an interface for which the .xpt file is missing, e.g. var editorShell = Components.classes["component://netscape/editor/ editorshell"].createInstance(); editorShell = editorShell.QueryInterface(Components.interfaces.nsIEditorShell); where nsIEditorShell is in editor.xpt which is missing, causes a crash. QI gets called on the implementation, with a nil IID reference. Passing nil references around is bad, and causes an attempt to read an IID from *nil.

Checked in a fix. This was a more general problem... A null or void on the JS side was getting converted into a NULL on the native side. This is usually the right thing to do. But when the xpidl param type for the value is declared as [ref] (which maps to a C++ reference) this is very bad. Now the code checks for this case and throws a JS exception with a nice message when this happens. Thanks for finding this!

Simon Fraser, could you please verify this ?

This can be verified by QA. On linux, delete editor.xpt from the components directory. Now choose 'Editor' from the tasks menu. If you should not dump core.

I'll try that. Thank you.

verified on 1999-06-17-08 RedHat Linux 5.2 kernel 2.2.7 1999-06-17-08 WinNT 4.0 sp4 1999-06-17-08 MacOS 8.51