1 files changed, 70 insertions, 0 deletions
diff --git a/contracts/erc20/contracts/src/UnlimitedAllowanceERC20Token.sol b/contracts/erc20/contracts/src/UnlimitedAllowanceERC20Token.sol
new file mode 100644
index 000000000..3a43c250d
--- /dev/null
+++ b/contracts/erc20/contracts/src/UnlimitedAllowanceERC20Token.sol
@@ -0,0 +1,70 @@
+/*
+
+  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;
+
+import "./ERC20Token.sol";
+
+
+contract UnlimitedAllowanceERC20Token is
+    ERC20Token
+{
+    uint256 constant internal 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
+    )
+        external
+        returns (bool)
+    {
+        uint256 allowance = allowed[_from][msg.sender];
+        require(
+            balances[_from] >= _value,
+            "ERC20_INSUFFICIENT_BALANCE"
+        );
+        require(
+            allowance >= _value,
+            "ERC20_INSUFFICIENT_ALLOWANCE"
+        );
+        require(
+            balances[_to] + _value >= balances[_to],
+            "UINT256_OVERFLOW"
+        );
+
+        balances[_to] += _value;
+        balances[_from] -= _value;
+        if (allowance < MAX_UINT) {
+            allowed[_from][msg.sender] -= _value;
+        }
+
+        emit Transfer(
+            _from,
+            _to,
+            _value
+        );
+
+        return true;
+    }
+}