75 lines
2.6 KiB
Solidity
75 lines
2.6 KiB
Solidity
/*
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Copyright 2020 DODO ZOO.
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SPDX-License-Identifier: Apache-2.0
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This is a simplified version of OpenZepplin's SafeERC20 library
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*/
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pragma solidity 0.6.9;
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pragma experimental ABIEncoderV2;
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import {IERC20} from "../intf/IERC20.sol";
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import {SafeMath} from "./SafeMath.sol";
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/**
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* @title SafeERC20
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* @dev Wrappers around ERC20 operations that throw on failure (when the token
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* contract returns false). Tokens that return no value (and instead revert or
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* throw on failure) are also supported, non-reverting calls are assumed to be
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* successful.
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* To use this library you can add a `using SafeERC20 for ERC20;` statement to your contract,
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* which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
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*/
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library SafeERC20 {
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using SafeMath for uint256;
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function safeTransfer(
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IERC20 token,
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address to,
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uint256 value
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) internal {
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_callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
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}
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function safeTransferFrom(
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IERC20 token,
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address from,
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address to,
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uint256 value
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) internal {
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_callOptionalReturn(
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token,
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abi.encodeWithSelector(token.transferFrom.selector, from, to, value)
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);
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}
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/**
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* @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
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* on the return value: the return value is optional (but if data is returned, it must not be false).
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* @param token The token targeted by the call.
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* @param data The call data (encoded using abi.encode or one of its variants).
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*/
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function _callOptionalReturn(IERC20 token, bytes memory data) private {
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// We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
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// we're implementing it ourselves.
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// A Solidity high level call has three parts:
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// 1. The target address is checked to verify it contains contract code
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// 2. The call itself is made, and success asserted
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// 3. The return value is decoded, which in turn checks the size of the returned data.
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// solhint-disable-next-line max-line-length
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// solhint-disable-next-line avoid-low-level-calls
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(bool success, bytes memory returndata) = address(token).call(data);
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require(success, "SafeERC20: low-level call failed");
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if (returndata.length > 0) {
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// Return data is optional
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// solhint-disable-next-line max-line-length
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require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
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}
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}
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}
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