Chain extension (#662)

Cargo.toml

@@ -18,4 +18,6 @@ exclude = [
   "fork-off",
   "benches/payout-stakers",
   "bin/cliain",
+  "bin/runtime/src/chain_extension/snarcos-extension",
+  "contracts/snarcos-contract",
 ]

bin/runtime/src/chain_extension/mod.rs

@@ -0,0 +1,49 @@
+use frame_support::log::error;
+use pallet_contracts::chain_extension::{
+    ChainExtension, Environment, Ext, InitState, RetVal, SysConfig,
+};
+use sp_core::crypto::UncheckedFrom;
+use sp_runtime::DispatchError;
+
+use crate::Runtime;
+
+pub const SNARCOS_CHAIN_EXT: u32 = 41;
+
+pub struct AlephChainExtension;
+impl ChainExtension<Runtime> for AlephChainExtension {
+    fn call<E: Ext>(func_id: u32, env: Environment<E, InitState>) -> Result<RetVal, DispatchError>
+    where
+        <E::T as SysConfig>::AccountId: UncheckedFrom<<E::T as SysConfig>::Hash> + AsRef<[u8]>,
+    {
+        match func_id {
+            SNARCOS_CHAIN_EXT => {
+                use pallet_snarcos::{Error, Pallet as Snarcos};
+
+                // The argument-passing-mode doesn't matter for now. All the data to runtime call
+                // are mocked now.
+                let mut env = env.buf_in_buf_out();
+                // After benchmarking is merged and `pallet_snarcos::WeightInfo` is available,
+                // use real weight here.
+                env.charge_weight(41)?;
+
+                match Snarcos::<Runtime>::bare_store_key([0u8; 4], [0u8; 8].to_vec()) {
+                    // In case `DispatchResultWithPostInfo` was returned (or some simpler
+                    // equivalent for `bare_store_key`), we could adjust weight. However, for the
+                    // storing key action it doesn't make sense.
+                    Ok(_) => {
+                        // Return status code for success.
+                        Ok(RetVal::Converging(0))
+                    }
+                    Err(Error::<Runtime>::VerificationKeyTooLong) => Ok(RetVal::Converging(1)),
+                    Err(Error::<Runtime>::IdentifierAlreadyInUse) => Ok(RetVal::Converging(2)),
+                    // Unknown error.
+                    _ => Ok(RetVal::Converging(3)),
+                }
+            }
+            _ => {
+                error!("Called an unregistered `func_id`: {}", func_id);
+                Err(DispatchError::Other("Unimplemented func_id"))
+            }
+        }
+    }
+}