68 lines
1.4 KiB
Solidity
68 lines
1.4 KiB
Solidity
pragma solidity ^0.4.24;
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import "./ERC20.sol";
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import "./IERC20.sol";
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/**
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* @title SafeERC20
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* @dev Wrappers around ERC20 operations that throw on failure.
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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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function safeTransfer(
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IERC20 token,
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address to,
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uint256 value
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)
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internal
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{
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require(token.transfer(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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)
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internal
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{
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require(token.transferFrom(from, to, value));
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}
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function safeApprove(
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IERC20 token,
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address spender,
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uint256 value
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)
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internal
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{
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// safeApprove should only be called when setting an initial allowance,
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// or when resetting it to zero. To increase and decrease it, use
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// 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
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require((value == 0) || (token.allowance(msg.sender, spender) == 0));
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require(token.approve(spender, value));
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}
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function safeIncreaseAllowance(
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IERC20 token,
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address spender,
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uint256 addedValue
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)
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internal
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{
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require(token.increaseAllowance(spender, addedValue));
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}
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function safeDecreaseAllowance(
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IERC20 token,
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address spender,
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uint256 subtractedValue
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)
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internal
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{
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require(token.decreaseAllowance(spender, subtractedValue));
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}
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}
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