129 lines
3.5 KiB
Solidity
129 lines
3.5 KiB
Solidity
/*
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* @source: https://github.com/SmartContractSecurity/SWC-registry/blob/master/test_cases/transaction_order_dependence/ERC20.sol
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* @author: -
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* @vulnerable_at_lines: 110,113
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*/
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pragma solidity ^0.4.24;
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/** Taken from the OpenZeppelin github
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* @title SafeMath
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* @dev Math operations with safety checks that revert on error
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*/
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library SafeMath {
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/**
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* @dev Multiplies two numbers, reverts on overflow.
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*/
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function mul(uint256 a, uint256 b) internal pure returns (uint256) {
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// Gas optimization: this is cheaper than requiring 'a' not being zero, but the
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// benefit is lost if 'b' is also tested.
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// See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
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if (a == 0) {
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return 0;
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}
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uint256 c = a * b;
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require(c / a == b);
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return c;
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}
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/**
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* @dev Integer division of two numbers truncating the quotient, reverts on division by zero.
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*/
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function div(uint256 a, uint256 b) internal pure returns (uint256) {
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require(b > 0); // Solidity only automatically asserts when dividing by 0
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uint256 c = a / b;
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// assert(a == b * c + a % b); // There is no case in which this doesn't hold
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return c;
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}
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/**
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* @dev Subtracts two numbers, reverts on overflow (i.e. if subtrahend is greater than minuend).
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*/
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function sub(uint256 a, uint256 b) internal pure returns (uint256) {
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require(b <= a);
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uint256 c = a - b;
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return c;
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}
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/**
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* @dev Adds two numbers, reverts on overflow.
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*/
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function add(uint256 a, uint256 b) internal pure returns (uint256) {
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uint256 c = a + b;
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require(c >= a);
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return c;
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}
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/**
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* @dev Divides two numbers and returns the remainder (unsigned integer modulo),
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* reverts when dividing by zero.
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*/
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function mod(uint256 a, uint256 b) internal pure returns (uint256) {
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require(b != 0);
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return a % b;
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}
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}
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contract ERC20 {
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event Transfer( address indexed from, address indexed to, uint256 value );
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event Approval( address indexed owner, address indexed spender, uint256 value);
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using SafeMath for *;
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mapping (address => uint256) private _balances;
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mapping (address => mapping (address => uint256)) private _allowed;
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uint256 private _totalSupply;
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constructor(uint totalSupply){
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_balances[msg.sender] = totalSupply;
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}
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function balanceOf(address owner) public view returns (uint256) {
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return _balances[owner];
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}
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function allowance(address owner, address spender) public view returns (uint256)
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{
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return _allowed[owner][spender];
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}
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function transfer(address to, uint256 value) public returns (bool) {
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require(value <= _balances[msg.sender]);
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require(to != address(0));
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_balances[msg.sender] = _balances[msg.sender].sub(value);
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_balances[to] = _balances[to].add(value);
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emit Transfer(msg.sender, to, value);
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return true;
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}
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// <yes> <report> FRONT_RUNNING
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function approve(address spender, uint256 value) public returns (bool) {
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require(spender != address(0));
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// <yes> <report> FRONT_RUNNING
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_allowed[msg.sender][spender] = value;
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emit Approval(msg.sender, spender, value);
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return true;
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}
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function transferFrom(address from, address to, uint256 value) public returns (bool) {
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require(value <= _balances[from]);
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require(value <= _allowed[from][msg.sender]);
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require(to != address(0));
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_balances[from] = _balances[from].sub(value);
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_balances[to] = _balances[to].add(value);
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_allowed[from][msg.sender] = _allowed[from][msg.sender].sub(value);
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emit Transfer(from, to, value);
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return true;
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}
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} |