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Uniswap Flashloan
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pragma solidity >=0.5.0; | |
interface IUniswapV2Callee { | |
function uniswapV2Call(address sender, uint amount0, uint amount1, bytes calldata data) external; | |
} |
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... | |
// this low-level function should be called from a contract which performs important safety checks | |
function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external lock { | |
require(amount0Out > 0 || amount1Out > 0, 'UniswapV2: INSUFFICIENT_OUTPUT_AMOUNT'); | |
(uint112 _reserve0, uint112 _reserve1,) = getReserves(); // gas savings | |
require(amount0Out < _reserve0 && amount1Out < _reserve1, 'UniswapV2: INSUFFICIENT_LIQUIDITY'); | |
uint balance0; | |
uint balance1; | |
{ // scope for _token{0,1}, avoids stack too deep errors | |
address _token0 = token0; | |
address _token1 = token1; | |
require(to != _token0 && to != _token1, 'UniswapV2: INVALID_TO'); | |
if (amount0Out > 0) _safeTransfer(_token0, to, amount0Out); // optimistically transfer tokens | |
if (amount1Out > 0) _safeTransfer(_token1, to, amount1Out); // optimistically transfer tokens | |
if (data.length > 0) IUniswapV2Callee(to).uniswapV2Call(msg.sender, amount0Out, amount1Out, data); | |
balance0 = IERC20(_token0).balanceOf(address(this)); | |
balance1 = IERC20(_token1).balanceOf(address(this)); | |
} | |
uint amount0In = balance0 > _reserve0 - amount0Out ? balance0 - (_reserve0 - amount0Out) : 0; | |
uint amount1In = balance1 > _reserve1 - amount1Out ? balance1 - (_reserve1 - amount1Out) : 0; | |
require(amount0In > 0 || amount1In > 0, 'UniswapV2: INSUFFICIENT_INPUT_AMOUNT'); | |
{ // scope for reserve{0,1}Adjusted, avoids stack too deep errors | |
uint balance0Adjusted = balance0.mul(1000).sub(amount0In.mul(3)); | |
uint balance1Adjusted = balance1.mul(1000).sub(amount1In.mul(3)); | |
require(balance0Adjusted.mul(balance1Adjusted) >= uint(_reserve0).mul(_reserve1).mul(1000**2), 'UniswapV2: K'); | |
} | |
_update(balance0, balance1, _reserve0, _reserve1); | |
emit Swap(msg.sender, amount0In, amount1In, amount0Out, amount1Out, to); | |
} | |
... |
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... | |
function swapExactTokensForTokens( | |
uint amountIn, | |
uint amountOutMin, | |
address[] calldata path, | |
address to, | |
uint deadline | |
) external virtual override ensure(deadline) returns (uint[] memory amounts) { | |
amounts = UniswapV2Library.getAmountsOut(factory, amountIn, path); | |
require(amounts[amounts.length - 1] >= amountOutMin, 'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT'); | |
TransferHelper.safeTransferFrom( | |
path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0] | |
); | |
_swap(amounts, path, to); | |
} | |
... |
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