@0x/zero-ex: Address CD post-audit feedback.

Add `LogMetadataTransformer`.

contracts/zero-ex/CHANGELOG.json

@@ -17,6 +17,14 @@
             {
                 "note": "Refund unused protocol fees to `refundReceiver` in FQT",
                 "pr": 2657
+            },
+            {
+                "note": "Address CD post-audit feedback",
+                "pr": 2657
+            },
+            {
+                "note": "Add `LogMetadataTransformer`",
+                "pr": 2657
             }
         ]
     },

contracts/zero-ex/contracts/src/features/Bootstrap.sol

@@ -77,6 +77,7 @@ contract Bootstrap is
     /// @dev Self-destructs this contract.
     ///      Can only be called by the deployer.
     function die() external {
+        assert(address(this) == _implementation);
         if (msg.sender != _deployer) {
             LibProxyRichErrors.InvalidDieCallerError(msg.sender, _deployer).rrevert();
         }

contracts/zero-ex/contracts/src/features/MetaTransactions.sol

@@ -271,7 +271,9 @@ contract MetaTransactions is
 
         _validateMetaTransaction(state);
 
-        // Mark the transaction executed.
+        // Mark the transaction executed by storing the block at which it was executed.
+        // Currently the block number just indicates that the mtx was executed and
+        // serves no other purpose from within this contract.
         LibMetaTransactionsStorage.getStorage()
             .mtxHashToExecutedBlockNumber[state.hash] = block.number;
 

contracts/zero-ex/contracts/src/features/Ownable.sol

@@ -44,10 +44,6 @@ contract Ownable is
 
     using LibRichErrorsV06 for bytes;
 
-    constructor() public FixinCommon() {
-        // solhint-disable-next-line no-empty-blocks
-    }
-
     /// @dev Initializes this feature. The intial owner will be set to this (ZeroEx)
     ///      to allow the bootstrappers to call `extend()`. Ownership should be
     ///      transferred to the real owner by the bootstrapper after

contracts/zero-ex/contracts/src/features/SignatureValidator.sol

@@ -49,10 +49,6 @@ contract SignatureValidator is
     /// @dev Version of this feature.
     uint256 public immutable override FEATURE_VERSION = _encodeVersion(1, 0, 0);
 
-    constructor() public FixinCommon() {
-        // solhint-disable-next-line no-empty-blocks
-    }
-
     /// @dev Initialize and register this feature.
     ///      Should be delegatecalled by `Migrate.migrate()`.
     /// @return success `LibMigrate.SUCCESS` on success.

contracts/zero-ex/contracts/src/features/SimpleFunctionRegistry.sol

@@ -42,10 +42,6 @@ contract SimpleFunctionRegistry is
 
     using LibRichErrorsV06 for bytes;
 
-    constructor() public FixinCommon() {
-        // solhint-disable-next-line no-empty-blocks
-    }
-
     /// @dev Initializes this feature, registering its own functions.
     /// @return success Magic bytes if successful.
     function bootstrap()

contracts/zero-ex/contracts/src/features/TokenSpender.sol

@@ -48,10 +48,6 @@ contract TokenSpender is
 
     using LibRichErrorsV06 for bytes;
 
-    constructor() public FixinCommon() {
-        // solhint-disable-next-line no-empty-blocks
-    }
-
     /// @dev Initialize and register this feature. Should be delegatecalled
     ///      into during a `Migrate.migrate()`.
     /// @param allowanceTarget An `allowanceTarget` instance, configured to have

contracts/zero-ex/contracts/src/features/TransformERC20.sol

@@ -61,10 +61,6 @@ contract TransformERC20 is
     /// @dev Version of this feature.
     uint256 public immutable override FEATURE_VERSION = _encodeVersion(1, 2, 0);
 
-    constructor() public FixinCommon() {
-        // solhint-disable-next-line no-empty-blocks
-    }
-
     /// @dev Initialize and register this feature.
     ///      Should be delegatecalled by `Migrate.migrate()`.
     /// @param transformerDeployer The trusted deployer for transformers.
@@ -257,16 +253,15 @@ contract TransformERC20 is
         // Compute how much output token has been transferred to the taker.
         state.takerOutputTokenBalanceAfter =
             LibERC20Transformer.getTokenBalanceOf(args.outputToken, args.taker);
-        if (state.takerOutputTokenBalanceAfter > state.takerOutputTokenBalanceBefore) {
+        if (state.takerOutputTokenBalanceAfter < state.takerOutputTokenBalanceBefore) {
-            outputTokenAmount = state.takerOutputTokenBalanceAfter.safeSub(
-                state.takerOutputTokenBalanceBefore
-            );
-        } else if (state.takerOutputTokenBalanceAfter < state.takerOutputTokenBalanceBefore) {
             LibTransformERC20RichErrors.NegativeTransformERC20OutputError(
                 address(args.outputToken),
                 state.takerOutputTokenBalanceBefore - state.takerOutputTokenBalanceAfter
             ).rrevert();
         }
+        outputTokenAmount = state.takerOutputTokenBalanceAfter.safeSub(
+            state.takerOutputTokenBalanceBefore
+        );
         // Ensure enough output token has been sent to the taker.
         if (outputTokenAmount < args.minOutputTokenAmount) {
             LibTransformERC20RichErrors.IncompleteTransformERC20Error(

contracts/zero-ex/contracts/src/transformers/AffiliateFeeTransformer.sol

@@ -32,7 +32,6 @@ import "./LibERC20Transformer.sol";
 contract AffiliateFeeTransformer is
     Transformer
 {
-    // solhint-disable no-empty-blocks
     using LibRichErrorsV06 for bytes;
     using LibSafeMathV06 for uint256;
     using LibERC20Transformer for IERC20TokenV06;
@@ -51,12 +50,6 @@ contract AffiliateFeeTransformer is
 
     uint256 private constant MAX_UINT256 = uint256(-1);
 
-    /// @dev Create this contract.
-    constructor()
-        public
-        Transformer()
-    {}
-
     /// @dev Transfers tokens to recipients.
     /// @param context Context information.
     /// @return success The success bytes (`LibERC20Transformer.TRANSFORMER_SUCCESS`).

contracts/zero-ex/contracts/src/transformers/LogMetadataTransformer.sol

@@ -0,0 +1,46 @@
+/*
+
+  Copyright 2020 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.6.5;
+pragma experimental ABIEncoderV2;
+
+import "./Transformer.sol";
+import "./LibERC20Transformer.sol";
+
+
+/// @dev A transformer that just emits an event with an arbitrary byte payload.
+contract LogMetadataTransformer is
+    Transformer
+{
+    event TransformerMetadata(bytes32 callDataHash, address sender, address taker, bytes data);
+
+    /// @dev Maximum uint256 value.
+    uint256 private constant MAX_UINT256 = uint256(-1);
+
+    /// @dev Emits an event.
+    /// @param context Context information.
+    /// @return success The success bytes (`LibERC20Transformer.TRANSFORMER_SUCCESS`).
+    function transform(TransformContext calldata context)
+        external
+        override
+        returns (bytes4 success)
+    {
+        emit TransformerMetadata(context.callDataHash, context.sender, context.taker, context.data);
+        return LibERC20Transformer.TRANSFORMER_SUCCESS;
+    }
+}

contracts/zero-ex/package.json

@@ -39,9 +39,9 @@
         "publish:private": "yarn build && gitpkg publish"
     },
     "config": {
-        "publicInterfaceContracts": "IZeroEx,ZeroEx,FullMigration,InitialMigration,IFlashWallet,IAllowanceTarget,IERC20Transformer,IOwnable,ISimpleFunctionRegistry,ITokenSpender,ITransformERC20,FillQuoteTransformer,PayTakerTransformer,WethTransformer,Ownable,SimpleFunctionRegistry,TransformERC20,TokenSpender,AffiliateFeeTransformer,SignatureValidator,MetaTransactions",
+        "publicInterfaceContracts": "IZeroEx,ZeroEx,FullMigration,InitialMigration,IFlashWallet,IAllowanceTarget,IERC20Transformer,IOwnable,ISimpleFunctionRegistry,ITokenSpender,ITransformERC20,FillQuoteTransformer,PayTakerTransformer,WethTransformer,Ownable,SimpleFunctionRegistry,TransformERC20,TokenSpender,AffiliateFeeTransformer,SignatureValidator,MetaTransactions,LogMetadataTransformer",
         "abis:comment": "This list is auto-generated by contracts-gen. Don't edit manually.",
-        "abis": "./test/generated-artifacts/@(AffiliateFeeTransformer|AllowanceTarget|Bootstrap|FillQuoteTransformer|FixinCommon|FixinEIP712|FixinGasToken|FixinReentrancyGuard|FlashWallet|FullMigration|IAllowanceTarget|IBootstrap|IERC20Bridge|IERC20Transformer|IExchange|IFeature|IFlashWallet|IGasToken|IMetaTransactions|IOwnable|ISignatureValidator|ISimpleFunctionRegistry|ITestSimpleFunctionRegistryFeature|ITokenSpender|ITransformERC20|IZeroEx|InitialMigration|LibBootstrap|LibCommonRichErrors|LibERC20Transformer|LibMetaTransactionsRichErrors|LibMetaTransactionsStorage|LibMigrate|LibOwnableRichErrors|LibOwnableStorage|LibProxyRichErrors|LibProxyStorage|LibReentrancyGuardStorage|LibSignatureRichErrors|LibSignedCallData|LibSimpleFunctionRegistryRichErrors|LibSimpleFunctionRegistryStorage|LibSpenderRichErrors|LibStorage|LibTokenSpenderStorage|LibTransformERC20RichErrors|LibTransformERC20Storage|LibWalletRichErrors|MetaTransactions|Ownable|PayTakerTransformer|SignatureValidator|SimpleFunctionRegistry|TestCallTarget|TestDelegateCaller|TestFillQuoteTransformerBridge|TestFillQuoteTransformerExchange|TestFillQuoteTransformerHost|TestFullMigration|TestInitialMigration|TestMetaTransactionsTransformERC20Feature|TestMigrator|TestMintTokenERC20Transformer|TestMintableERC20Token|TestSimpleFunctionRegistryFeatureImpl1|TestSimpleFunctionRegistryFeatureImpl2|TestTokenSpender|TestTokenSpenderERC20Token|TestTransformERC20|TestTransformerBase|TestTransformerDeployerTransformer|TestTransformerHost|TestWeth|TestWethTransformerHost|TestZeroExFeature|TokenSpender|TransformERC20|Transformer|TransformerDeployer|WethTransformer|ZeroEx).json"
+        "abis": "./test/generated-artifacts/@(AffiliateFeeTransformer|AllowanceTarget|Bootstrap|FillQuoteTransformer|FixinCommon|FixinEIP712|FixinGasToken|FixinReentrancyGuard|FlashWallet|FullMigration|IAllowanceTarget|IBootstrap|IERC20Bridge|IERC20Transformer|IExchange|IFeature|IFlashWallet|IGasToken|IMetaTransactions|IOwnable|ISignatureValidator|ISimpleFunctionRegistry|ITestSimpleFunctionRegistryFeature|ITokenSpender|ITransformERC20|IZeroEx|InitialMigration|LibBootstrap|LibCommonRichErrors|LibERC20Transformer|LibMetaTransactionsRichErrors|LibMetaTransactionsStorage|LibMigrate|LibOwnableRichErrors|LibOwnableStorage|LibProxyRichErrors|LibProxyStorage|LibReentrancyGuardStorage|LibSignatureRichErrors|LibSignedCallData|LibSimpleFunctionRegistryRichErrors|LibSimpleFunctionRegistryStorage|LibSpenderRichErrors|LibStorage|LibTokenSpenderStorage|LibTransformERC20RichErrors|LibTransformERC20Storage|LibWalletRichErrors|LogMetadataTransformer|MetaTransactions|Ownable|PayTakerTransformer|SignatureValidator|SimpleFunctionRegistry|TestCallTarget|TestDelegateCaller|TestFillQuoteTransformerBridge|TestFillQuoteTransformerExchange|TestFillQuoteTransformerHost|TestFullMigration|TestInitialMigration|TestMetaTransactionsTransformERC20Feature|TestMigrator|TestMintTokenERC20Transformer|TestMintableERC20Token|TestSimpleFunctionRegistryFeatureImpl1|TestSimpleFunctionRegistryFeatureImpl2|TestTokenSpender|TestTokenSpenderERC20Token|TestTransformERC20|TestTransformerBase|TestTransformerDeployerTransformer|TestTransformerHost|TestWeth|TestWethTransformerHost|TestZeroExFeature|TokenSpender|TransformERC20|Transformer|TransformerDeployer|WethTransformer|ZeroEx).json"
     },
     "repository": {
         "type": "git",

contracts/zero-ex/src/artifacts.ts

@@ -17,6 +17,7 @@ import * as ISimpleFunctionRegistry from '../generated-artifacts/ISimpleFunction
 import * as ITokenSpender from '../generated-artifacts/ITokenSpender.json';
 import * as ITransformERC20 from '../generated-artifacts/ITransformERC20.json';
 import * as IZeroEx from '../generated-artifacts/IZeroEx.json';
+import * as LogMetadataTransformer from '../generated-artifacts/LogMetadataTransformer.json';
 import * as MetaTransactions from '../generated-artifacts/MetaTransactions.json';
 import * as Ownable from '../generated-artifacts/Ownable.json';
 import * as PayTakerTransformer from '../generated-artifacts/PayTakerTransformer.json';
@@ -48,4 +49,5 @@ export const artifacts = {
     AffiliateFeeTransformer: AffiliateFeeTransformer as ContractArtifact,
     SignatureValidator: SignatureValidator as ContractArtifact,
     MetaTransactions: MetaTransactions as ContractArtifact,
+    LogMetadataTransformer: LogMetadataTransformer as ContractArtifact,
 };

contracts/zero-ex/src/index.ts

@@ -9,6 +9,7 @@ export {
     ITokenSpenderContract,
     ITransformERC20Contract,
     IZeroExContract,
+    LogMetadataTransformerContract,
     PayTakerTransformerContract,
     WethTransformerContract,
     ZeroExContract,

contracts/zero-ex/src/wrappers.ts

@@ -15,6 +15,7 @@ export * from '../generated-wrappers/i_token_spender';
 export * from '../generated-wrappers/i_transform_erc20';
 export * from '../generated-wrappers/i_zero_ex';
 export * from '../generated-wrappers/initial_migration';
+export * from '../generated-wrappers/log_metadata_transformer';
 export * from '../generated-wrappers/meta_transactions';
 export * from '../generated-wrappers/ownable';
 export * from '../generated-wrappers/pay_taker_transformer';

contracts/zero-ex/test/artifacts.ts

@@ -53,6 +53,7 @@ import * as LibTokenSpenderStorage from '../test/generated-artifacts/LibTokenSpe
 import * as LibTransformERC20RichErrors from '../test/generated-artifacts/LibTransformERC20RichErrors.json';
 import * as LibTransformERC20Storage from '../test/generated-artifacts/LibTransformERC20Storage.json';
 import * as LibWalletRichErrors from '../test/generated-artifacts/LibWalletRichErrors.json';
+import * as LogMetadataTransformer from '../test/generated-artifacts/LogMetadataTransformer.json';
 import * as MetaTransactions from '../test/generated-artifacts/MetaTransactions.json';
 import * as Ownable from '../test/generated-artifacts/Ownable.json';
 import * as PayTakerTransformer from '../test/generated-artifacts/PayTakerTransformer.json';
@@ -139,6 +140,7 @@ export const artifacts = {
     FillQuoteTransformer: FillQuoteTransformer as ContractArtifact,
     IERC20Transformer: IERC20Transformer as ContractArtifact,
     LibERC20Transformer: LibERC20Transformer as ContractArtifact,
+    LogMetadataTransformer: LogMetadataTransformer as ContractArtifact,
     PayTakerTransformer: PayTakerTransformer as ContractArtifact,
     Transformer: Transformer as ContractArtifact,
     WethTransformer: WethTransformer as ContractArtifact,

contracts/zero-ex/test/wrappers.ts

@@ -51,6 +51,7 @@ export * from '../test/generated-wrappers/lib_token_spender_storage';
 export * from '../test/generated-wrappers/lib_transform_erc20_rich_errors';
 export * from '../test/generated-wrappers/lib_transform_erc20_storage';
 export * from '../test/generated-wrappers/lib_wallet_rich_errors';
+export * from '../test/generated-wrappers/log_metadata_transformer';
 export * from '../test/generated-wrappers/meta_transactions';
 export * from '../test/generated-wrappers/ownable';
 export * from '../test/generated-wrappers/pay_taker_transformer';

contracts/zero-ex/tsconfig.json

@@ -15,6 +15,7 @@
         "generated-artifacts/ITransformERC20.json",
         "generated-artifacts/IZeroEx.json",
         "generated-artifacts/InitialMigration.json",
+        "generated-artifacts/LogMetadataTransformer.json",
         "generated-artifacts/MetaTransactions.json",
         "generated-artifacts/Ownable.json",
         "generated-artifacts/PayTakerTransformer.json",
@@ -72,6 +73,7 @@
         "test/generated-artifacts/LibTransformERC20RichErrors.json",
         "test/generated-artifacts/LibTransformERC20Storage.json",
         "test/generated-artifacts/LibWalletRichErrors.json",
+        "test/generated-artifacts/LogMetadataTransformer.json",
         "test/generated-artifacts/MetaTransactions.json",
         "test/generated-artifacts/Ownable.json",
         "test/generated-artifacts/PayTakerTransformer.json",