Fix approval assets bug plus ts tests

precompiles/assets-erc20/src/lib.rs

@@ -276,7 +276,6 @@ where
 		context: &Context,
 	) -> EvmResult<PrecompileOutput> {
 		let mut gasometer = Gasometer::new(target_gas);
-		gasometer.record_cost(RuntimeHelper::<Runtime>::db_write_gas_cost())?;
 		gasometer.record_log_costs_manual(3, 32)?;
 
 		// Parse input.
@@ -291,40 +290,38 @@ where
 				Runtime::account_to_asset_id(execution_address)
 					.ok_or(error("non-assetId address"))?;
 
-			let caller: Runtime::AccountId =
-				Runtime::AddressMapping::into_account_id(context.caller);
+			let origin = Runtime::AddressMapping::into_account_id(context.caller);
+
 			let spender: Runtime::AccountId = Runtime::AddressMapping::into_account_id(spender);
 
 			// Dispatch call (if enough gas).
 			// We first cancel any existing approvals
 			// Since we cannot check storage, we need to execute this call without knowing whether
 			// another approval exists already.
-			// But we know that if no approval exists we should get "Unknown"
 			// Allowance() should be checked instead of doing this Result matching
 			let used_gas = match RuntimeHelper::<Runtime>::try_dispatch(
-				<<Runtime as frame_system::Config>::Call as Dispatchable>::Origin::root(),
-				pallet_assets::Call::<Runtime, Instance>::force_cancel_approval {
+				Some(origin.clone()).into(),
+				pallet_assets::Call::<Runtime, Instance>::cancel_approval {
 					id: asset_id,
-					owner: Runtime::Lookup::unlookup(caller),
 					delegate: Runtime::Lookup::unlookup(spender.clone()),
 				},
 				gasometer.remaining_gas()?,
 			) {
 				Ok(gas_used) => Ok(gas_used),
-				Err(ExitError::Other(e)) => {
-					// One DB read for checking the approval did not exist
-					if e.contains("Unknown") {
-						Ok(RuntimeHelper::<Runtime>::db_read_gas_cost())
-					} else {
-						Err(ExitError::Other(e))
-					}
-				}
+				// ExitError::Other is only returned if the dispatchable fails with an error
+				// We cannot format the error in wasm
+				// In our case, we know that if cancel_approval fails approve_transfer will also
+				// fail in all cases except the one we are interested on: that it does not exist
+				// a previous approval. In this case we still want to continue, so it is safe
+				// to do this
+				// TODO: Once 0.9.12 is here, we should be able to only call cance_approval if
+				// such approval exists.
+				Err(ExitError::Other(_e)) => Ok(2 * RuntimeHelper::<Runtime>::db_read_gas_cost()),
+				// Any other error can be returned
 				Err(e) => Err(e),
 			}?;
 			gasometer.record_cost(used_gas)?;
 
-			let origin = Runtime::AddressMapping::into_account_id(context.caller);
-
 			// Dispatch call (if enough gas).
 			let used_gas = RuntimeHelper::<Runtime>::try_dispatch(
 				Some(origin).into(),
@@ -413,8 +410,6 @@ where
 		context: &Context,
 	) -> EvmResult<PrecompileOutput> {
 		let mut gasometer = Gasometer::new(target_gas);
-		gasometer.record_cost(RuntimeHelper::<Runtime>::db_read_gas_cost())?;
-		gasometer.record_cost(RuntimeHelper::<Runtime>::db_write_gas_cost())?;
 		gasometer.record_log_costs_manual(3, 32)?;
 
 		// Parse input.

precompiles/assets-erc20/src/tests.rs

@@ -727,7 +727,7 @@ fn transfer_from_non_incremental_approval() {
 				Some(Ok(PrecompileOutput {
 					exit_status: ExitSucceed::Returned,
 					output: Default::default(),
-					cost: 115329756u64,
+					cost: 114357756u64,
 					logs: LogsBuilder::new(Account::AssetId(0u128).into())
 						.log3(
 							SELECTOR_LOG_APPROVAL,

runtime/moonbase/src/lib.rs

@@ -1382,6 +1382,7 @@ impl Contains<Call> for NormalFilter {
 				pallet_assets::Call::transfer_keep_alive { .. } => true,
 				pallet_assets::Call::approve_transfer { .. } => true,
 				pallet_assets::Call::transfer_approved { .. } => true,
+				pallet_assets::Call::cancel_approval { .. } => true,
 				_ => false,
 			},
 			_ => true,

tests/contracts/sources.ts

@@ -893,4 +893,137 @@ export const contractSources: { [key: string]: string } = {
         return F(rounds, h, m, t, f);
       }
     }`,
+  ERC20Instance: `
+    // SPDX-License-Identifier: GPL-3.0-only
+    pragma solidity ^0.8.0;
+
+    /**
+     * @title ERC20 interface
+     * @dev see https://github.com/ethereum/EIPs/issues/20
+     * @dev copied from https://github.com/OpenZeppelin/openzeppelin-contracts
+     */
+    interface IERC20 {
+    /**
+     * @dev Total number of tokens in existence
+     * Selector: 18160ddd
+     */
+    function totalSupply() external view returns (uint256);
+
+    /**
+     * @dev Gets the balance of the specified address.
+     * Selector: 70a08231
+     * @param who The address to query the balance of.
+     * @return An uint256 representing the amount owned by the passed address.
+     */
+    function balanceOf(address who) external view returns (uint256);
+
+    /**
+     * @dev Function to check the amount of tokens that an owner allowed to a spender.
+     * Selector: dd62ed3e
+     * @param owner address The address which owns the funds.
+     * @param spender address The address which will spend the funds.
+     * @return A uint256 specifying the amount of tokens still available for the spender.
+     */
+    function allowance(address owner, address spender)
+        external view returns (uint256);
+
+    /**
+     * @dev Transfer token for a specified address
+     * Selector: a9059cbb
+     * @param to The address to transfer to.
+     * @param value The amount to be transferred.
+     */
+    function transfer(address to, uint256 value) external returns (bool);
+
+    /**
+     * @dev Approve the passed address to spend the specified amount of tokens on behalf
+     * of msg.sender.
+     * Beware that changing an allowance with this method brings the risk that someone may
+     * use both the old
+     * and the new allowance by unfortunate transaction ordering. One possible solution to
+     * mitigate this race condition is to first reduce the spender's allowance to 0 and set
+     * the desired value afterwards:
+     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
+     * Selector: 095ea7b3
+     * @param spender The address which will spend the funds.
+     * @param value The amount of tokens to be spent.
+     */
+    function approve(address spender, uint256 value)
+        external returns (bool);
+
+    /**
+     * @dev Transfer tokens from one address to another
+     * Selector: 23b872dd
+     * @param from address The address which you want to send tokens from
+     * @param to address The address which you want to transfer to
+     * @param value uint256 the amount of tokens to be transferred
+     */
+    function transferFrom(address from, address to, uint256 value)
+        external returns (bool);
+
+    /**
+     * @dev Event emited when a transfer has been performed.
+     * Selector: ddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef
+     * @param from address The address sending the tokens
+     * @param to address The address receiving the tokens.
+     * @param value uint256 The amount of tokens transfered.
+     */
+    event Transfer(
+        address indexed from,
+        address indexed to,
+        uint256 value
+    );
+
+    /**
+     * @dev Event emited when an approval has been registered.
+     * Selector: 8c5be1e5ebec7d5bd14f71427d1e84f3dd0314c0f7b2291e5b200ac8c7c3b925
+     * @param owner address Owner of the tokens.
+     * @param spender address Allowed spender.
+     * @param value uint256 Amount of tokens approved.
+     */
+    event Approval(
+        address indexed owner,
+        address indexed spender,
+        uint256 value
+    );
+    }
+
+    contract ERC20Instance is IERC20 {
+
+        /// The ierc20 at the known pre-compile address.
+        IERC20 public erc20 = IERC20(0x0000000000000000000000000000000000000802);
+
+            function totalSupply() override external view returns (uint256){
+                // We nominate our target collator with all the tokens provided
+                return erc20.totalSupply();
+            }
+
+            function balanceOf(address who) override external view returns (uint256){
+                // We nominate our target collator with all the tokens provided
+                return erc20.balanceOf(who);
+            }
+
+            function allowance(
+                address owner,
+                address spender
+            ) override external view returns (uint256){
+                return erc20.allowance(owner, spender);
+            }
+
+            function transfer(address to, uint256 value) override external returns (bool) {
+                return erc20.transfer(to, value);
+            }
+
+            function approve(address spender, uint256 value) override external returns (bool) {
+                return erc20.transfer(spender, value);
+            }
+
+            function transferFrom(
+                address from,
+                address to, 
+                int256 value
+            ) override external returns (bool) {
+                return erc20.transferFrom(from,  to, value);
+            }
+    }`,
 };