Contract and harness for as_ptr, cast, as_mut_ptr, and as_non_null_ptr #126
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zhassan-aws
reviewed
Oct 22, 2024
|
@zhassan-aws , I have made the required changes based on your feedback. Kindly review it again. |
zhassan-aws
reviewed
Nov 11, 2024
| @@ -1803,4 +1813,41 @@ mod verify { | |||
| let maybe_null_ptr = if kani::any() { xptr as *mut i32 } else { null_mut() }; | |||
| let _ = NonNull::new(maybe_null_ptr); | |||
| } | |||
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| #[kani::proof_for_contract(NonNull::as_ptr)] | |||
| pub fn non_null_check_as_ptr() { | |||
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Since the API under verification (NonNull::as_ptr) has no requirements on the data, it is better to use a less-restrictive harness that passes any pointer value, e.g.
let non_null_ptr: *mut i32 = kani::any::<usize>() as *mut i32;
let ptr = NonNull::new(non_null_ptr).unwrap();
...This guarantees that the API works for all possible pointer values.
| // Create a non-null slice pointer | ||
| let mut value: i32 = kani::any(); | ||
| let ptr = NonNull::new(&mut value as *mut i32).unwrap(); | ||
| let slice_ptr = NonNull::slice_from_raw_parts(ptr, 1); |
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Can we use a bigger length? value will need to be an array.
| #[kani::proof_for_contract(NonNull::<T>::cast)] | ||
| pub fn non_null_check_cast() { | ||
| // Create a non-null pointer to a random value | ||
| let mut x: i32 = kani::any(); |
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Same comment about using any pointer value (using kani::any::<usize>())
| let mut value: i32 = kani::any(); | ||
| let ptr = NonNull::new(&mut value as *mut i32).unwrap(); | ||
| // Create a slice pointer | ||
| let slice_ptr = NonNull::slice_from_raw_parts(ptr, 1); |
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Same comment about the slice length.
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Description
This PR includes contracts and proof harnesses for the four APIs as_ptr, cast, as_mut_ptr, and as_non_null_ptr which are part of the NonNull library in Rust.
Changes Overview:
Covered APIs:
NonNull::as_ptr: Acquires the underlying *mut pointer
NonNull::cast: Casts to a pointer of another type
NonNull:: as_mut_ptr: Returns raw pointer to array's buffer
NonNull::as_non_null_ptr: Returns a non-null pointer to slice's buffer
Proof harness:
non_null_check_as_ptr
non_null_check_cast
non_null_check_as_mut_ptr
non_null_check_as_non_null_ptr
Revalidation
To revalidate the verification results, run kani verify-std -Z unstable-options "path/to/library" -Z function-contracts -Z mem-predicates --harness ptr::non_null::verify. This will run all four harnesses in the module. All default checks should pass:
Resolves #53
By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 and MIT licenses.