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author | Fabio Berger <me@fabioberger.com> | 2018-08-22 18:41:42 +0800 |
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committer | Fabio Berger <me@fabioberger.com> | 2018-08-22 18:41:42 +0800 |
commit | 0248add542ac801bcb021fa7b13c182baec5612e (patch) | |
tree | 1d04404632ee381621b384f1e82ade97c06c9b92 /packages/contracts/src/2.0.0/tokens/ERC20Token/UnlimitedAllowanceERC20Token.sol | |
parent | c12f0d04bb2f0d5ad73943d02a592a110423a423 (diff) | |
parent | 80e52464a6fdf9576776214f77e46d441b959b06 (diff) | |
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Merge development branch
Diffstat (limited to 'packages/contracts/src/2.0.0/tokens/ERC20Token/UnlimitedAllowanceERC20Token.sol')
-rw-r--r-- | packages/contracts/src/2.0.0/tokens/ERC20Token/UnlimitedAllowanceERC20Token.sol | 71 |
1 files changed, 71 insertions, 0 deletions
diff --git a/packages/contracts/src/2.0.0/tokens/ERC20Token/UnlimitedAllowanceERC20Token.sol b/packages/contracts/src/2.0.0/tokens/ERC20Token/UnlimitedAllowanceERC20Token.sol new file mode 100644 index 000000000..e6f7c063e --- /dev/null +++ b/packages/contracts/src/2.0.0/tokens/ERC20Token/UnlimitedAllowanceERC20Token.sol @@ -0,0 +1,71 @@ +/* + + 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/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; + } +} |