Merge branch 'sol-cov-fixes' of github.com:0xProject/0x-monorepo into sol-cov-fixes

* 'sol-cov-fixes' of github.com:0xProject/0x-monorepo: (49 commits)
  Add @return comments
  Import marshaller directly
  Update comment about ethers checksummed address behavior
  Add packages/coverage/.gitkeep file
  Update CI config and package.json to run @0xproject/utils tests on CI
  Update remaining CHANGELOG.json files
  Change amir picture
  Update CHANGELOG.json for contract-wrappers
  Update ethers typings for TypeScript 2.9.2
  Update CHANGELOG.json for base-contract
  Move some ethers-related types to typescript-typings/ethers
  Apply prettier
  Add strictArgumentEncodingCheck to BaseContract and use it in contract templates
  fix(monorepo-scripts): Fix typo in git tag command
  feat(monorepo-scripts): Add confirmation prompt before publishing
  fix comments and styling for MixinSignatureValidator
  Update TypeScript to version 2.9.2
  Use asm for hashEIP712Message, increment free memory pointer after asm hashing functions
  Fix comments, styling, and optimize hashOrder
  Remove assertion comments
  ...

4 files changed, 65 insertions, 33 deletions

diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/MixinSignatureValidator.sol b/packages/contracts/src/2.0.0/protocol/Exchange/MixinSignatureValidator.sol
index ac7382715..44de54817 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/MixinSignatureValidator.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinSignatureValidator.sol
@@ -96,14 +96,15 @@ contract MixinSignatureValidator is
             "LENGTH_GREATER_THAN_0_REQUIRED"
         );
 
-        // Ensure signature is supported
+        // Pop last byte off of signature byte array.
         uint8 signatureTypeRaw = uint8(signature.popLastByte());
+
+        // Ensure signature is supported
         require(
             signatureTypeRaw < uint8(SignatureType.NSignatureTypes),
             "SIGNATURE_UNSUPPORTED"
         );
 
-        // Pop last byte off of signature byte array.
         SignatureType signatureType = SignatureType(signatureTypeRaw);
 
         // Variables are not scoped in Solidity.
@@ -141,7 +142,12 @@ contract MixinSignatureValidator is
             v = uint8(signature[0]);
             r = signature.readBytes32(1);
             s = signature.readBytes32(33);
-            recovered = ecrecover(hash, v, r, s);
+            recovered = ecrecover(
+                hash,
+                v,
+                r,
+                s
+            );
             isValid = signerAddress == recovered;
             return isValid;
 
@@ -197,7 +203,6 @@ contract MixinSignatureValidator is
         // | 0x14 + x | 1      | Signature type is always "\x06" |
         } else if (signatureType == SignatureType.Validator) {
             // Pop last 20 bytes off of signature byte array.
-
             address validatorAddress = signature.popLast20Bytes();
             
             // Ensure signer has approved validator.
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/MixinTransactions.sol b/packages/contracts/src/2.0.0/protocol/Exchange/MixinTransactions.sol
index 88d2da7d7..b5de1a5de 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/MixinTransactions.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinTransactions.sol
@@ -123,19 +123,23 @@ contract MixinTransactions is
         bytes32 dataHash = keccak256(data);
 
         // Assembly for more efficiently computing:
-        // keccak256(abi.encode(
+        // keccak256(abi.encodePacked(
         //     EIP712_ZEROEX_TRANSACTION_SCHEMA_HASH,
         //     salt,
-        //     signerAddress,
+        //     bytes32(signerAddress),
         //     keccak256(data)
         // ));
 
         assembly {
+            // Load free memory pointer
             let memPtr := mload(64)
-            mstore(memPtr, schemaHash)
-            mstore(add(memPtr, 32), salt)
-            mstore(add(memPtr, 64), and(signerAddress, 0xffffffffffffffffffffffffffffffffffffffff))
-            mstore(add(memPtr, 96), dataHash)
+
+            mstore(memPtr, schemaHash)                                                               // hash of schema
+            mstore(add(memPtr, 32), salt)                                                            // salt
+            mstore(add(memPtr, 64), and(signerAddress, 0xffffffffffffffffffffffffffffffffffffffff))  // signerAddress
+            mstore(add(memPtr, 96), dataHash)                                                        // hash of data
+
+            // Compute hash
             result := keccak256(memPtr, 128)
         }
 
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibEIP712.sol b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibEIP712.sol
index 1fc41dafd..b02f7632e 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibEIP712.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibEIP712.sol
@@ -30,7 +30,7 @@ contract LibEIP712 {
     string constant internal EIP712_DOMAIN_VERSION = "2";
 
     // Hash of the EIP712 Domain Separator Schema
-    bytes32 public constant EIP712_DOMAIN_SEPARATOR_SCHEMA_HASH = keccak256(abi.encodePacked(
+    bytes32 constant internal EIP712_DOMAIN_SEPARATOR_SCHEMA_HASH = keccak256(abi.encodePacked(
         "EIP712Domain(",
         "string name,",
         "string version,",
@@ -45,11 +45,11 @@ contract LibEIP712 {
     constructor ()
         public
     {
-        EIP712_DOMAIN_HASH = keccak256(abi.encode(
+        EIP712_DOMAIN_HASH = keccak256(abi.encodePacked(
             EIP712_DOMAIN_SEPARATOR_SCHEMA_HASH,
             keccak256(bytes(EIP712_DOMAIN_NAME)),
             keccak256(bytes(EIP712_DOMAIN_VERSION)),
-            address(this)
+            bytes32(address(this))
         ));
     }
 
@@ -59,8 +59,28 @@ contract LibEIP712 {
     function hashEIP712Message(bytes32 hashStruct)
         internal
         view
-        returns (bytes32)
+        returns (bytes32 result)
     {
-        return keccak256(abi.encodePacked(EIP191_HEADER, EIP712_DOMAIN_HASH, hashStruct));
+        bytes32 eip712DomainHash = EIP712_DOMAIN_HASH;
+
+        // Assembly for more efficient computing:
+        // keccak256(abi.encodePacked(
+        //     EIP191_HEADER,
+        //     EIP712_DOMAIN_HASH,
+        //     hashStruct    
+        // ));
+
+        assembly {
+            // Load free memory pointer
+            let memPtr := mload(64)
+
+            mstore(memPtr, 0x1901000000000000000000000000000000000000000000000000000000000000)  // EIP191 header
+            mstore(add(memPtr, 2), eip712DomainHash)                                            // EIP712 domain hash
+            mstore(add(memPtr, 34), hashStruct)                                                 // Hash of struct
+
+            // Compute hash
+            result := keccak256(memPtr, 66)
+        }
+        return result;
     }
 }
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibOrder.sol b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibOrder.sol
index 4031ff26b..68f4f5f1b 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibOrder.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibOrder.sol
@@ -103,11 +103,12 @@ contract LibOrder is
         bytes32 takerAssetDataHash = keccak256(order.takerAssetData);
 
         // Assembly for more efficiently computing:
-        // keccak256(abi.encode(
-        //     order.makerAddress,
-        //     order.takerAddress,
-        //     order.feeRecipientAddress,
-        //     order.senderAddress,
+        // keccak256(abi.encodePacked(
+        //     EIP712_ORDER_SCHEMA_HASH,
+        //     bytes32(order.makerAddress),
+        //     bytes32(order.takerAddress),
+        //     bytes32(order.feeRecipientAddress),
+        //     bytes32(order.senderAddress),
         //     order.makerAssetAmount,
         //     order.takerAssetAmount,
         //     order.makerFee,
@@ -119,24 +120,26 @@ contract LibOrder is
         // ));
 
         assembly {
+            // Calculate memory addresses that will be swapped out before hashing
+            let pos1 := sub(order, 32)
+            let pos2 := add(order, 320)
+            let pos3 := add(order, 352)
+
             // Backup
-            // solhint-disable-next-line space-after-comma
-            let temp1 := mload(sub(order,  32))
-            let temp2 := mload(add(order, 320))
-            let temp3 := mload(add(order, 352))
+            let temp1 := mload(pos1)
+            let temp2 := mload(pos2)
+            let temp3 := mload(pos3)
             
             // Hash in place
-            // solhint-disable-next-line space-after-comma
-            mstore(sub(order,  32), schemaHash)
-            mstore(add(order, 320), makerAssetDataHash)
-            mstore(add(order, 352), takerAssetDataHash)
-            result := keccak256(sub(order, 32), 416)
+            mstore(pos1, schemaHash)
+            mstore(pos2, makerAssetDataHash)
+            mstore(pos3, takerAssetDataHash)
+            result := keccak256(pos1, 416)
             
             // Restore
-            // solhint-disable-next-line space-after-comma
-            mstore(sub(order,  32), temp1)
-            mstore(add(order, 320), temp2)
-            mstore(add(order, 352), temp3)
+            mstore(pos1, temp1)
+            mstore(pos2, temp2)
+            mstore(pos3, temp3)
         }
         return result;
     }