aboutsummaryrefslogtreecommitdiffstats
path: root/packages/contracts/src/2.0.0/tokens/UnlimitedAllowanceToken
diff options
context:
space:
mode:
Diffstat (limited to 'packages/contracts/src/2.0.0/tokens/UnlimitedAllowanceToken')
-rw-r--r--packages/contracts/src/2.0.0/tokens/UnlimitedAllowanceToken/UnlimitedAllowanceToken.sol58
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;
+ }
+}