873152 - Add explicit rooting API to ctypes

Status: NEW

(Core :: js-ctypes, defect)

Description

[Benjamin Smedberg]

ctypes clients want to do this:

callCFunction(arg, function() {
  ... callback
});

This is obviously rooting-unsafe if the function is asynchronous. But unfortunately the alternatives are often pretty gross. In particular, you'd need to save the callback in something accessible from a global variable.

I'd like to propose that we add an explicit rooting API to ctypes to make this case easier:

var cb = function() {
  ... callback
  ctypes.unroot(cb);
};
ctypes.root(cb);
callCFunction(arg, cb);

You could even add some JS decoration (assuming the callback is once-only).