Contracts: Translate .wat fixtures to rust (#2654)

- Translate all pallet-contracts fixtures from `wat` to Rust files.
- Fix read_sandbox_memory_as to not use MaxEncodedLen as this could
break if used with types with a non-fixed encoded len.

---------

Co-authored-by: alvicsam <alvicsam@gmail.com>
Co-authored-by: Alexander Samusev <41779041+alvicsam@users.noreply.github.com>
Co-authored-by: Alexander Theißen <alex.theissen@me.com>
Co-authored-by: command-bot <>

substrate/frame/contracts/src/wasm/mod.rs

@@ -2460,7 +2460,7 @@ mod tests {
 		assert_eq!(
 			result,
 			Err(ExecError {
-				error: Error::<Test>::OutOfBounds.into(),
+				error: Error::<Test>::DecodingFailed.into(),
 				origin: ErrorOrigin::Caller,
 			})
 		);
@@ -3428,4 +3428,20 @@ mod tests {
 		assert_eq!(delegate_dependencies.len(), 1);
 		assert_eq!(delegate_dependencies[0].as_bytes(), [1; 32]);
 	}
+
+	// This test checks that [`Runtime::read_sandbox_memory_as`] works, when the decoded type has a
+	// max_len greater than the memory size, but the decoded data fits into the memory.
+	#[test]
+	fn read_sandbox_memory_as_works_with_max_len_out_of_bounds_but_fitting_actual_data() {
+		use frame_support::BoundedVec;
+		use sp_core::ConstU32;
+
+		let mut ext = MockExt::default();
+		let runtime = Runtime::new(&mut ext, vec![]);
+		let data = vec![1u8, 2, 3];
+		let memory = data.encode();
+		let decoded: BoundedVec<u8, ConstU32<128>> =
+			runtime.read_sandbox_memory_as(&memory, 0u32).unwrap();
+		assert_eq!(decoded.into_inner(), data);
+	}
 }

substrate/frame/contracts/src/wasm/runtime.rs

@@ -583,9 +583,8 @@ impl<'a, E: Ext + 'a> Runtime<'a, E> {
 		ptr: u32,
 	) -> Result<D, DispatchError> {
 		let ptr = ptr as usize;
-		let mut bound_checked = memory
-			.get(ptr..ptr + D::max_encoded_len() as usize)
-			.ok_or_else(|| Error::<E::T>::OutOfBounds)?;
+		let mut bound_checked = memory.get(ptr..).ok_or_else(|| Error::<E::T>::OutOfBounds)?;
+
 		let decoded = D::decode_with_depth_limit(MAX_DECODE_NESTING, &mut bound_checked)
 			.map_err(|_| DispatchError::from(Error::<E::T>::DecodingFailed))?;
 		Ok(decoded)