Make the slice to create new hash have the same length with the hash

The new hash will check whether the input and the hash to create has the
same length.

Author: Seulgi Kim

state/src/item/metadata.rs

@@ -155,7 +155,9 @@ impl_address!(TOP, MetadataAddress, PREFIX);
 
 impl MetadataAddress {
     pub fn new() -> Self {
-        Self::from_transaction_hash(H256::from_slice(b"metadata address"), 0)
+        let mut key = [0u8; 32];
+        key[0..16].copy_from_slice(b"metadata address");
+        Self::from_transaction_hash(H256::from_slice(&key), 0)
     }
 }
 
@@ -238,4 +240,14 @@ mod tests {
         };
         rlp_encode_and_decode_test!(metadata);
     }
+
+    #[test]
+    fn metadata_address_is_constant() {
+        let address = MetadataAddress::new();
+        let expected = [
+            77u8, 65, 87, 171, 93, 124, 219, 195, 206, 204, 98, 127, 21, 167, 126, 51, 136, 47, 48, 19, 43, 129, 199,
+            232, 2, 92, 210, 163, 14, 209, 173, 33,
+        ];
+        assert_eq!(expected, address.as_ref());
+    }
 }

state/src/item/module.rs

@@ -90,7 +90,9 @@ impl_address!(TOP, ModuleAddress, PREFIX);
 
 impl ModuleAddress {
     pub fn new(storage_id: StorageId) -> Self {
-        Self::from_transaction_hash(H256::from_slice(b"module"), storage_id.into())
+        let mut key = [0u8; 32];
+        key[0..6].copy_from_slice(b"module");
+        Self::from_transaction_hash(H256::from_slice(&key), storage_id.into())
     }
 }