display stock quantity to specific vendor (ver 3.60)

hi, ladies and gentlemen,
i update my question here:


a customer's email account is [email protected]
the vendor - testVender's email is set to [email protected]
a known variable of the stockQuantity is in Libraries\Nop.Services\Catalog\ProductExtensions.cs line#102

how to get the emails of the current customer and the vendor?
i want to add a condition in this program block to judge whether these two emails are the same

the answer i need becomes simpler, but still need help
thank you :)

thanks,
but i can't implement _vendorService
what should i do first to use all the object(?) with underscore?

the current logged in user's email, i use
EngineContext.Current.Resolve<IWorkContext>().CurrentCustomer.Email
this works. may no problem this way i guess

_vendorService=EngineContext.Current.Resolve<IVendorService>();

var vendor=_vendorService.GetVendorById(product.VendorId);

string vendorEmail=vendor.Email