Bumping severity because it causes (recoverable) data loss in *links table when someone triggering a linksupdate is using HHVM.

It looks like nested Lua calls are propagating errors up further than they should. I'm investigating why.

Created attachment 16553
Test case

I've reduced this to a more minimal test case.

What's happening is that EG(exception) isn't getting cleared despite the try-catch in the PHP function, so luasandbox_call_php rethrows it.

Attached:

This problem appears quite widespread. Setting High importance.

I think the correct thing to do is to clear EG(exception) at the end of zend_wrap_func(). In Zend, EG(exception) is an "active" exception, i.e. prior to being handled by the VM. EG(exception) is cleared by the ZEND_CATCH opcode. So it makes sense to clear it before returning to HHVM's VM.

In a recursive call into zend_wrap_func() via zend_call_function(), the Zend exception will be converted to a C++ exception and back again, so there will only be one sort of exception active at any one time. Whereas in the current situation, after the return from zend_wrap_func(), we have both a Zend exception and a C++ exception being active.

https://github.com/facebook/hhvm/pull/3834

(In reply to Tim Starling from comment #6)

https://github.com/facebook/hhvm/pull/3834

Thanks Tim.