Solidity
由於還原操作碼,很可能沒有完成價值轉移
當我想向 erc20 合約發送一些 eth 時,我收到以下錯誤:“由於還原操作碼,很可能沒有完成價值轉移”。
我修改了備份功能,以便在收到 eth 付款後通過以下方式發送令牌:
function () public payable { uint amount = msg.value; uint tokens = amount * 10; transfer(msg.sender, tokens); }
這是整個程式碼:
pragma solidity ^0.4.18; contract SafeMath { function safeAdd(uint a, uint b) public pure returns (uint c) { c = a + b; require(c >= a); } function safeSub(uint a, uint b) public pure returns (uint c) { require(b <= a); c = a - b; } function safeMul(uint a, uint b) public pure returns (uint c) { c = a * b; require(a == 0 || c / a == b); } function safeDiv(uint a, uint b) public pure returns (uint c) { require(b > 0); c = a / b; } } contract ERC20Interface { function totalSupply() public constant returns (uint); function balanceOf(address tokenOwner) public constant returns (uint balance); function allowance(address tokenOwner, address spender) public constant returns (uint remaining); function transfer(address to, uint tokens) public returns (bool success); function approve(address spender, uint tokens) public returns (bool success); function transferFrom(address from, address to, uint tokens) public returns (bool success); event Transfer(address indexed from, address indexed to, uint tokens); event Approval(address indexed tokenOwner, address indexed spender, uint tokens); } contract ApproveAndCallFallBack { function receiveApproval(address from, uint256 tokens, address token, bytes data) public; } contract Owned { address public owner; address public newOwner; event OwnershipTransferred(address indexed _from, address indexed _to); function Owned() public { owner = msg.sender; } modifier onlyOwner { require(msg.sender == owner); _; } function transferOwnership(address _newOwner) public onlyOwner { newOwner = _newOwner; } function acceptOwnership() public { require(msg.sender == newOwner); OwnershipTransferred(owner, newOwner); owner = newOwner; newOwner = address(0); } } contract MaToken is ERC20Interface, Owned, SafeMath { string public symbol; string public name; uint8 public decimals; uint public _totalSupply; mapping(address => uint) balances; mapping(address => mapping(address => uint)) allowed; // ------------------------------------------------------------------------ // Constructor // ------------------------------------------------------------------------ function MaToken() public { symbol = "MATK"; name = "MaToken"; decimals = 18; _totalSupply = 100000000000000000000000000; balances[0x9596f1439576e0142976F0822883DE62e326B542] = _totalSupply; Transfer(address(0), 0x9596f1439576e0142976F0822883DE62e326B542, _totalSupply); } // ------------------------------------------------------------------------ // Total supply // ------------------------------------------------------------------------ function totalSupply() public constant returns (uint) { return _totalSupply - balances[address(0)]; } // ------------------------------------------------------------------------ // Get the token balance for account tokenOwner // ------------------------------------------------------------------------ function balanceOf(address tokenOwner) public constant returns (uint balance) { return balances[tokenOwner]; } // ------------------------------------------------------------------------ // Transfer the balance from token owner's account to to account // - Owner's account must have sufficient balance to transfer // - 0 value transfers are allowed // ------------------------------------------------------------------------ function transfer(address to, uint tokens) public returns (bool success) { balances[msg.sender] = safeSub(balances[msg.sender], tokens); balances[to] = safeAdd(balances[to], tokens); Transfer(msg.sender, to, tokens); return true; } // ------------------------------------------------------------------------ // Token owner can approve for spender to transferFrom(...) tokens // from the token owner's account // // https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20-token-standard.md // recommends that there are no checks for the approval double-spend attack // as this should be implemented in user interfaces // ------------------------------------------------------------------------ function approve(address spender, uint tokens) public returns (bool success) { allowed[msg.sender][spender] = tokens; Approval(msg.sender, spender, tokens); return true; } // ------------------------------------------------------------------------ // Transfer tokens from the from account to the to account // // The calling account must already have sufficient tokens approve(...)-d // for spending from the from account and // - From account must have sufficient balance to transfer // - Spender must have sufficient allowance to transfer // - 0 value transfers are allowed // ------------------------------------------------------------------------ function transferFrom(address from, address to, uint tokens) public returns (bool success) { balances[from] = safeSub(balances[from], tokens); allowed[from][msg.sender] = safeSub(allowed[from][msg.sender], tokens); balances[to] = safeAdd(balances[to], tokens); Transfer(from, to, tokens); return true; } // ------------------------------------------------------------------------ // Returns the amount of tokens approved by the owner that can be // transferred to the spender's account // ------------------------------------------------------------------------ function allowance(address tokenOwner, address spender) public constant returns (uint remaining) { return allowed[tokenOwner][spender]; } // ------------------------------------------------------------------------ // Token owner can approve for spender to transferFrom(...) tokens // from the token owner's account. The spender contract function // receiveApproval(...) is then executed // ------------------------------------------------------------------------ function approveAndCall(address spender, uint tokens, bytes data) public returns (bool success) { allowed[msg.sender][spender] = tokens; Approval(msg.sender, spender, tokens); ApproveAndCallFallBack(spender).receiveApproval(msg.sender, tokens, this, data); return true; } // ------------------------------------------------------------------------ // Sending token after having received ethereum // ------------------------------------------------------------------------ function () public payable { //revert(); // Received amount of ether uint amount = msg.value; // Convert to tokens uint tokens = amount * 10; // Transfer tokens assigned to this contract to sender transfer(msg.sender, tokens); } // ------------------------------------------------------------------------ // Owner can transfer out any accidentally sent ERC20 tokens // ------------------------------------------------------------------------ function transferAnyERC20Token(address tokenAddress, uint tokens) public onlyOwner returns (bool success) { return ERC20Interface(tokenAddress).transfer(owner, tokens); } }
出於安全原因,備用功能具有2300 gas的固定津貼。因此它不會執行您放入其中的程式碼。您需要定義一個應呼叫的應付函式以將乙太幣發送到合約
例如
function deposit() payable{ uint amount = msg.value; uint tokens = amount * 10; transfer(msg.sender, tokens); }