ericwlange
commented
5 years ago Interesting. According to the issue you referenced, these direct syscalls were replaced in libuv 1.23.1. Node 8.9.3, which is the version used by LiquidCore uses v1.15.0. The latest 8.x LTS (8.15.0) uses v1.23.2, probably not coincidentally. It looks like it is time for me to upgrade node versions. I have been planning to upgrade to 11.x eventually, but a minor upgrade should be much simpler so I'll do that. Do you have a simple failing test I can use to make sure this is the right solution?
As for a workaround, you can certainly polyfill it with a native implementation. Untested, it would probably look something like:
private SparseArray<Thread> threadMap = new SparseArray<>();
// MicroService.ServiceOnStartListener --
@Override
public void onStart(MicroService service) {
service.getProcess().addEventListener(new Process.EventListener() {
@Override public void onProcessStart(Process process, final JSContext context) {
context.property("setTimeout", new JSFunction(context, "setTimeout") {
public Integer setTimeout(final JSFunction fn, final Integer ms, final JSValue ... args) {
final Thread thread = new Thread() {
@Override public void run() {
Thread.sleep(ms);
if (threadMap.get(thread.hashCode()) == thread) {
fn.apply(null, args);
threadMap.remove(thread.hashCode());
}
}
};
threadMap.put(thread.hashCode(), thread);
thread.start();
return thread.hashCode();
}
});
// You would then have to implement setInterval and clearTimer similarly
}
@Override public void onProcessAboutToExit(Process process, int exitCode) {}
@Override public void onProcessExit(Process process, int exitCode) {}
@Override public void onProcessFailed(Process process, Exception error) {}
});
}The only challenge with this is that setTimeout() in node does some magic to keep the process alive while it is running. I don't think this polyfill will do that, although I am not entirely sure. You might also have to call process.keepAlive() explicitly in the above onStart() handler.
If you come up with a version that generally works, please post it here so others can use the workaround. I'll work on getting node 8.15.0 integrated.
neopryn
I've been implementing LiquidCore into Xamarin.Android as a way to execute JS in android and so far it's been pretty simple. While testing across a few different devices i've run into an issue with a core event method that seems to crash the app entirely on android version 26 and up.
The issue comes from using setTimeout and the resulting exception when its used is
Fatal signal 31 (SIGSYS), code 1 (SYS_SECCOMP). After digging around a bit I've found its got something to do with a syscall filter introduced in API version 26 of android that blacklists syscalls that have been found to have security implications. Details can be found here: https://android-developers.googleblog.com/2017/07/seccomp-filter-in-android-o.htmlI can't get full details on the sys_call that cause the failure but i've found some evidence that one of the dependencies for node 8.9.3 called libuv is responsible for making a particular blacklisted sys_call
epoll_waitthat triggers this https://github.com/libuv/libuv/issues/2105. I feel like there's multiple ways of getting around this however I wouldn't be surprised if this ends up being a problem in future with other restricted calls that node doesn't typically have problems with.Is there strategy for dealing with this sort of this and is it possible to polyfill the behaviour of these methods (maybe by using native timers)?