Remove deprecated host functions (#5038)

Sadly we need to keep one function `ext_blake2_256`. This function is
manually defined in `sp-core`.

substrate/primitives/io/src/lib.rs

@@ -915,6 +915,56 @@ pub fn oom(_: core::alloc::Layout) -> ! {
 #[cfg(feature = "std")]
 pub type TestExternalities = sp_state_machine::TestExternalities<sp_core::Blake2Hasher, u64>;
 
+#[cfg(feature = "std")]
+mod ext_blake2_256 {
+	use sp_wasm_interface::{Signature, Function, HostFunctions, ValueType, Value, FunctionContext};
+
+	/// There is a custom `extern function` in `sp_core::hasher` for `ext_blake2_256` hasher. This
+	/// custom extern was missed to remove and requires us to support this now. This type is a custom
+	/// implementation for the wasm function in native.
+	pub struct ExtBlake2_256;
+
+	impl HostFunctions for ExtBlake2_256 {
+		fn host_functions() -> Vec<&'static dyn Function> {
+			vec![&ExtBlake2_256]
+		}
+	}
+
+	impl Function for ExtBlake2_256 {
+		fn name(&self) -> &str {
+			"ext_blake2_256"
+		}
+
+		fn signature(&self) -> Signature {
+			Signature::new_with_args(&[ValueType::I32, ValueType::I32, ValueType::I32][..])
+		}
+
+		fn execute(
+			&self,
+			context: &mut dyn FunctionContext,
+			args: &mut dyn Iterator<Item = Value>,
+		) -> sp_wasm_interface::Result<Option<Value>> {
+			let data = args.next().and_then(|v| v.as_i32())
+				.ok_or_else(|| "`data` not present or not an `i32`")? as u32;
+			let len = args.next().and_then(|v| v.as_i32())
+				.ok_or_else(|| "`len` not present or not an `i32`")? as u32;
+			let out = args.next().and_then(|v| v.as_i32())
+				.ok_or_else(|| "`out` not present or not an `i32`")? as u32;
+
+			let result: [u8; 32] = if len == 0 {
+				sp_core::hashing::blake2_256(&[0u8; 0])
+			} else {
+				let mem = context.read_memory(data.into(), len)
+					.map_err(|_| "Invalid attempt to get data in ext_blake2_256")?;
+				sp_core::hashing::blake2_256(&mem)
+			};
+			context.write_memory(out.into(), &result)
+				.map_err(|_| "Invalid attempt to set result in ext_blake2_256")?;
+			Ok(None)
+		}
+	}
+}
+
 /// The host functions Substrate provides for the Wasm runtime environment.
 ///
 /// All these host functions will be callable from inside the Wasm environment.
@@ -929,6 +979,7 @@ pub type SubstrateHostFunctions = (
 	logging::HostFunctions,
 	sandbox::HostFunctions,
 	crate::trie::HostFunctions,
+	ext_blake2_256::ExtBlake2_256,
 );
 
 #[cfg(test)]

substrate/primitives/runtime-interface/test-wasm/src/lib.rs

@@ -105,23 +105,6 @@ pub trait TestApi {
 	}
 }
 
-/// Two random external functions from the old runtime interface.
-/// This ensures that we still inherently export these functions from the host and that we are still
-/// compatible with old wasm runtimes.
-#[cfg(not(feature = "std"))]
-extern "C" {
-	pub fn ext_clear_storage(key_data: *const u8, key_len: u32);
-	pub fn ext_keccak_256(data: *const u8, len: u32, out: *mut u8);
-}
-
-/// Make sure the old runtime interface needs to be imported.
-#[no_mangle]
-#[cfg(not(feature = "std"))]
-pub fn force_old_runtime_interface_import() {
-	unsafe { ext_clear_storage(sp_std::ptr::null(), 0); }
-	unsafe { ext_keccak_256(sp_std::ptr::null(), 0, sp_std::ptr::null_mut()); }
-}
-
 /// This function is not used, but we require it for the compiler to include `sp-io`.
 /// `sp-io` is required for its panic and oom handler.
 #[no_mangle]
@@ -248,4 +231,14 @@ wasm_export_functions! {
 		}
 		assert_eq!(0, len);
 	}
+
+	fn test_ext_blake2_256() {
+		use sp_core::Hasher;
+
+		let data = "hey, hash me please!";
+		let hash = sp_core::Blake2Hasher::hash(data.as_bytes());
+
+		let expected = sp_io::hashing::blake2_256(data.as_bytes());
+		assert_eq!(&expected, hash.as_ref());
+	}
 }

substrate/primitives/runtime-interface/test/src/lib.rs

@@ -33,7 +33,6 @@ fn call_wasm_method<HF: HostFunctionsT>(method: &str) -> TestExternalities {
 		(
 			HF,
 			sp_io::SubstrateHostFunctions,
-			sc_executor::deprecated_host_interface::SubstrateExternals
 		)
 	>(
 		method,
@@ -128,3 +127,8 @@ fn test_encoded_return_value_memory_is_freed() {
 fn test_array_return_value_memory_is_freed() {
 	call_wasm_method::<HostFunctions>("test_array_return_value_memory_is_freed");
 }
+
+#[test]
+fn test_ext_blake2_256() {
+	call_wasm_method::<HostFunctions>("test_ext_blake2_256");
+}

substrate/primitives/wasm-interface/src/lib.rs

@@ -170,6 +170,12 @@ impl<T: PointerType> Pointer<T> {
 	}
 }
 
+impl<T: PointerType> From<u32> for Pointer<T> {
+	fn from(ptr: u32) -> Self {
+		Pointer::new(ptr)
+	}
+}
+
 impl<T: PointerType> From<Pointer<T>> for u32 {
 	fn from(ptr: Pointer<T>) -> Self {
 		ptr.ptr