Merge branch 'v2-prototype' into v2-contract-wrappers-WIP

1 files changed, 58 insertions, 0 deletions

diff --git a/packages/contracts/src/2.0.0/tokens/UnlimitedAllowanceToken/UnlimitedAllowanceToken.sol b/packages/contracts/src/2.0.0/tokens/UnlimitedAllowanceToken/UnlimitedAllowanceToken.sol
new file mode 100644
index 000000000..f62602ab3
--- /dev/null
+++ b/packages/contracts/src/2.0.0/tokens/UnlimitedAllowanceToken/UnlimitedAllowanceToken.sol
@@ -0,0 +1,58 @@
+/*
+
+  Copyright 2018 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 ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../ERC20Token/ERC20Token.sol";
+
+contract UnlimitedAllowanceToken is ERC20Token {
+
+    uint256 constant MAX_UINT = 2**256 - 1;
+
+    /// @dev ERC20 transferFrom, modified such that an allowance of MAX_UINT represents an unlimited allowance. See https://github.com/ethereum/EIPs/issues/717
+    /// @param _from Address to transfer from.
+    /// @param _to Address to transfer to.
+    /// @param _value Amount to transfer.
+    /// @return Success of transfer.
+    function transferFrom(address _from, address _to, uint256 _value)
+        public
+        returns (bool)
+    {
+        uint256 allowance = allowed[_from][msg.sender];
+        require(
+            balances[_from] >= _value,
+            INSUFFICIENT_BALANCE
+        );
+        require(
+            allowance >= _value,
+            INSUFFICIENT_ALLOWANCE
+        );
+        require(
+            balances[_to] + _value >= balances[_to],
+            OVERFLOW
+        );
+        balances[_to] += _value;
+        balances[_from] -= _value;
+        if (allowance < MAX_UINT) {
+            allowed[_from][msg.sender] -= _value;
+        }
+        emit Transfer(_from, _to, _value);
+        return true;
+    }
+}