// Vulnerability label: clean
pragma solidity ^0.5.7;

interface IERC20 {
    function totalSupply() external view returns (uint256);
    function balanceOf(address who) external view returns (uint256);
    function allowance(address owner, address spender) external view returns (uint256);

    function transfer(address to, uint256 value) external returns (bool);
    function approve(address spender, uint256 value) external returns (bool);
    function transferFrom(address from, address to, uint256 value) external returns (bool);

    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

interface IERC223 {
    function name() external view returns (string memory);
    function symbol() external view returns (string memory);
    function decimals() external view returns (uint8);
    function totalSupply() external view returns (uint256);

    function balanceOf(address who) external view returns (uint);

    function transfer(address to, uint value) external returns (bool);
    function transfer(address to, uint value, bytes calldata data) external returns (bool);

    event Transfer(address indexed from, address indexed to, uint value, bytes indexed data);
}

contract ContractReceiver {
    function tokenFallback(address _from, uint _value, bytes memory _data) public {
        
    }
}

/**
 * @title SafeMath
 * @dev Unsigned math operations with safety checks that revert on error.
 */
library SafeMath {
    /**
      * @dev Multiplies two unsigned integers, reverts on overflow.
      */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b);

        return c;
    }

    /**
      * @dev Integer division of two unsigned integers truncating the quotient,
      * reverts on division by zero.
      */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
      * @dev Subtracts two unsigned integers, reverts on overflow
      * (i.e. if subtrahend is greater than minuend).
      */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a);
        uint256 c = a - b;

        return c;
    }

    /**
      * @dev Adds two unsigned integers, reverts on overflow.
      */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a);

        return c;
    }

    /**
      * @dev Divides two unsigned integers and returns the remainder (unsigned integer modulo),
      * reverts when dividing by zero.
      */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b != 0);
        return a % b;
    }
}


contract StandardToken is IERC20, IERC223 {
    uint256 public totalSupply;

    using SafeMath for uint;

    mapping (address => uint256) internal balances;
    mapping (address => mapping (address => uint256)) internal allowed;

    function balanceOf(address _owner) public view returns (uint256 balance) {
        return balances[_owner];
    }

    function transferFrom(address _from, address _to, uint256 _value) public returns (bool) {
        require(_to != address(0));
        require(_value <= balances[_from]);
        require(_value <= allowed[_from][msg.sender]);
        balances[_from] = balances[_from].sub(_value);
        balances[_to] = balances[_to].add(_value);
        allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);
        emit Transfer(_from, _to, _value);
        return true;
    }

    function approve(address _spender, uint256 _value) public returns (bool) {
        //require(_value == 0 || allowed[msg.sender][_spender] == 0);
        allowed[msg.sender][_spender] = _value;
        emit Approval(msg.sender, _spender, _value);
        return true;
    }

    function allowance(address _owner, address _spender) public view returns (uint256) {
        return allowed[_owner][_spender];
    }

    function increaseApproval(address _spender, uint _addedValue) public returns (bool) {
        allowed[msg.sender][_spender] = allowed[msg.sender][_spender].add(_addedValue);
        emit Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
        return true;
    }

    function decreaseApproval(address _spender, uint _subtractedValue) public returns (bool) {
        uint oldValue = allowed[msg.sender][_spender];
        if (_subtractedValue > oldValue) {
            allowed[msg.sender][_spender] = 0;
        } else {
            allowed[msg.sender][_spender] = oldValue.sub(_subtractedValue);
        }
        emit Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
        return true;
    }

    // Function that is called when a user or another contract wants to transfer funds.
    function transfer(address _to, uint _value, bytes memory _data) public returns (bool success) {
        if (isContract(_to)) {
            return transferToContract(_to, _value, _data);
        } else {
            return transferToAddress(_to, _value, _data);
        }
    }

    // Standard function transfer similar to ERC20 transfer with no _data.
    // Added due to backwards compatibility reasons.
    function transfer(address _to, uint _value) public returns (bool success) {
        bytes memory empty;
        if (isContract(_to)) {
            return transferToContract(_to, _value, empty);
        } else {
            return transferToAddress(_to, _value, empty);
        }
    }

    // Assemble the given address bytecode. If bytecode exists then the _addr is a contract.
    function isContract(address _addr) private view returns (bool is_contract) {
        uint length;
        require(_addr != address(0));
        assembly {
            //retrieve the size of the code on target address, this needs assembly
            length := extcodesize(_addr)
        }
        return (length > 0);
    }

    // Function that is called when transaction target is an address.
    function transferToAddress(address _to, uint _value, bytes memory _data) private returns (bool success) {
        require(balances[msg.sender] >= _value);
        balances[msg.sender] = balances[msg.sender].sub(_value);
        balances[_to] = balances[_to].add(_value);
        emit Transfer(msg.sender, _to, _value);
        emit Transfer(msg.sender, _to, _value, _data);
        return true;
    }

    // Function that is called when transaction target is a contract.
    function transferToContract(address _to, uint _value, bytes memory _data) private returns (bool success) {
        require(balances[msg.sender] >= _value);
        balances[msg.sender] = balances[msg.sender].sub(_value);
        balances[_to] = balances[_to].add(_value);
        ContractReceiver receiver = ContractReceiver(_to);
        receiver.tokenFallback(msg.sender, _value, _data);
        emit Transfer(msg.sender, _to, _value);
        emit Transfer(msg.sender, _to, _value, _data);
        return true;
    }
}

contract XBase is StandardToken {
    string public constant name = "Eterbase Coin";
    string public constant symbol = "XBASE";
    uint8 public constant decimals = 18;
    uint256 public constant initialSupply = 1000000000 * 10 ** uint256(decimals);

    constructor () public {
        totalSupply = initialSupply;
        balances[msg.sender] = initialSupply;
    }
}