AFXbXL9t

1mod ralloc {
2    use ::std::{
3        mem::ManuallyDrop,
4        ops::{Deref, DerefMut},
5    };
6
7    #[derive(Debug)]
8    pub struct ZeroDropBox<T> /* = */ (Box< ManuallyDrop<T> >);
9
10    impl<T> Drop for ZeroDropBox<T>
11    {
12        fn drop (
13        self: &mut Self,
14        )
15        { unsafe {
16            ManuallyDrop::drop(&mut self.0);
17            ::std::ptr::write_volatile(
18              &mut self.0 as &mut T,
19              ::std::mem::zeroed(),
20            );
21            // we could even go as far as to zero the pointer itself ...
22        }}
23    }
24    
25    impl<T> From<T> for ZeroDropBox<T>
26    {
27        #[inline(always)]
28        fn from (inline_value: T) -> Self
29        {
30            ZeroDropBox(
31                Box::new(
32                    ManuallyDrop::new(
33                        inline_value
34                    )
35                )
36            )
37        }
38    }
39    
40    impl<T> Deref for ZeroDropBox<T>
41    {
42        type Target = T;
43        
44        #[inline]
45        fn deref (
46            self: &Self,
47        ) -> &Self::Target
48        {
49            &self.0
50        }
51    }
52    impl<T> DerefMut for ZeroDropBox<T>
53    {
54        #[inline]
55        fn deref_mut (
56            self: &mut Self,
57        ) -> &mut Self::Target
58        {
59            &mut self.0
60        }
61    }
62}
63pub use self::ralloc::ZeroDropBox;
64
65fn main ()
66{
67    let mut secret_key = ZeroDropBox::from([42_u8; 16]);
68    dbg!(&secret_key as &[u8; 16]);
69    let secret_key_after_free: &[u8; 16] = unsafe {
70        &*(&secret_key as &[u8; 16] as *const _)
71    };
72    ::std::mem::drop(secret_key);
73    dbg!(secret_key_after_free);
74}