Maybe unsound in add_ref

[lwz23]

hello, thank you for your contribution in this project, I am scanning the unsoundness problem in rust project.
I notice the following code:

pub fn add_ref(&self) -> std::os::raw::c_long {
        unsafe {
            let this = self as *const IObjectArray as *const *const std::os::raw::c_void;
            let ret = ((*self.vtable).add_ref)(this);
            let ret: std::os::raw::c_long = ret.into();

            ret
        }
    }

Considering that vtable is a pub field, I assume that users can directly manipulate this field, and that add_ref is a public function. This potential situation could result in self.vtable being a null pointer, and directly dereferencing it might trigger undefined behavior (UB). For safety reasons, I felt it necessary to report this issue. If you have performed checks elsewhere that ensure this is safe, please don’t take offense at my raising this issue.

[lwz23]

and same problem for:

OpenPAL3/crosscom/runtime/rust/src/defs.rs

Line 63 in 771a2c2

pub fn release(&self) -> std::os::raw::c_long {

OpenPAL3/crosscom/runtime/rust/src/defs.rs

Line 73 in 771a2c2

pub fn len(&self) -> std::os::raw::c_int {

OpenPAL3/crosscom/runtime/rust/src/defs.rs

Line 83 in 771a2c2

pub fn get(&self, index: std::os::raw::c_int) -> crosscom::ComRc<IUnknown> {