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| 1 | +pragma solidity 0.8.25; |
| 2 | + |
| 3 | +import "@openzeppelin/contracts/access/Ownable.sol"; |
| 4 | +import "@openzeppelin/contracts/utils/cryptography/EIP712.sol"; |
| 5 | + |
| 6 | +contract Coin is Ownable, EIP712 { |
| 7 | + string public constant name = "COIN"; |
| 8 | + string public constant symbol = "COIN"; |
| 9 | + uint8 public constant decimals = 18; |
| 10 | + bytes32 constant PERMIT_TYPEHASH = |
| 11 | + keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)"); |
| 12 | + |
| 13 | + event Approval(address indexed src, address indexed guy, uint256 wad); |
| 14 | + event Transfer(address indexed src, address indexed dst, uint256 wad); |
| 15 | + event Deposit(address indexed dst, uint256 wad); |
| 16 | + event Withdrawal(address indexed src, uint256 wad); |
| 17 | + event PrivilegedWithdrawal(address indexed src, uint256 wad); |
| 18 | + |
| 19 | + mapping(address => uint256) public nonces; |
| 20 | + mapping(address => uint256) public balanceOf; |
| 21 | + mapping(address => mapping(address => uint256)) public allowance; |
| 22 | + |
| 23 | + constructor() Ownable(msg.sender) EIP712(name, "1") {} |
| 24 | + |
| 25 | + fallback() external payable { |
| 26 | + deposit(); |
| 27 | + } |
| 28 | + |
| 29 | + function deposit() public payable { |
| 30 | + balanceOf[msg.sender] += msg.value; |
| 31 | + emit Deposit(msg.sender, msg.value); |
| 32 | + } |
| 33 | + |
| 34 | + function withdraw(uint256 wad) external { |
| 35 | + require(balanceOf[msg.sender] >= wad); |
| 36 | + balanceOf[msg.sender] -= wad; |
| 37 | + payable(msg.sender).transfer(wad); |
| 38 | + emit Withdrawal(msg.sender, wad); |
| 39 | + } |
| 40 | + |
| 41 | + function privilegedWithdraw() external onlyOwner { |
| 42 | + uint256 wad = balanceOf[address(0)]; |
| 43 | + balanceOf[address(0)] = 0; |
| 44 | + payable(msg.sender).transfer(wad); |
| 45 | + emit PrivilegedWithdrawal(msg.sender, wad); |
| 46 | + } |
| 47 | + |
| 48 | + function totalSupply() public view returns (uint256) { |
| 49 | + return address(this).balance; |
| 50 | + } |
| 51 | + |
| 52 | + function approve(address guy, uint256 wad) public returns (bool) { |
| 53 | + allowance[msg.sender][guy] = wad; |
| 54 | + emit Approval(msg.sender, guy, wad); |
| 55 | + return true; |
| 56 | + } |
| 57 | + |
| 58 | + function permit(address owner, address spender, uint256 value, uint256 deadline, uint8 v, bytes32 r, bytes32 s) |
| 59 | + external |
| 60 | + { |
| 61 | + require(block.timestamp <= deadline, "signature expired"); |
| 62 | + bytes32 structHash = keccak256(abi.encode(PERMIT_TYPEHASH, owner, spender, value, nonces[owner]++, deadline)); |
| 63 | + bytes32 h = _hashTypedDataV4(structHash); |
| 64 | + address signer = ecrecover(h, v, r, s); |
| 65 | + require(signer == owner, "invalid signer"); |
| 66 | + allowance[owner][spender] = value; |
| 67 | + emit Approval(owner, spender, value); |
| 68 | + } |
| 69 | + |
| 70 | + function transfer(address dst, uint256 wad) public returns (bool) { |
| 71 | + return transferFrom(msg.sender, dst, wad); |
| 72 | + } |
| 73 | + |
| 74 | + function transferFrom(address src, address dst, uint256 wad) public returns (bool) { |
| 75 | + require(balanceOf[src] >= wad); |
| 76 | + |
| 77 | + if (src != msg.sender && allowance[src][msg.sender] != type(uint256).max) { |
| 78 | + require(allowance[src][msg.sender] >= wad); |
| 79 | + allowance[src][msg.sender] -= wad; |
| 80 | + } |
| 81 | + |
| 82 | + balanceOf[src] -= wad; |
| 83 | + balanceOf[dst] += wad; |
| 84 | + |
| 85 | + emit Transfer(src, dst, wad); |
| 86 | + |
| 87 | + return true; |
| 88 | + } |
| 89 | +} |
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