laconicd-deprecated/tests/solidity/suites/staking/contracts/test/mocks/BadTokenMock.sol

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// Copied from https://github.com/OpenZeppelin/openzeppelin-solidity/blob/a9f910d34f0ab33a1ae5e714f69f9596a02b4d91/contracts/token/ERC20/StandardToken.sol
// transfer function always returns false!
pragma solidity 0.5.17;
//import "./ERC20.sol";
import "../../lib/os/ERC20.sol";
import "../../lib/os/SafeMath.sol";
/**
* @title Standard ERC20 token
*
* @dev Implementation of the basic standard token.
* https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md
* Based on code by FirstBlood: https://github.com/Firstbloodio/token/blob/master/smart_contract/FirstBloodToken.sol
*/
contract BadTokenMock is ERC20 {
using SafeMath for uint256;
mapping (address => uint256) private balances;
mapping (address => mapping (address => uint256)) private allowed;
uint256 private totalSupply_;
constructor(address initialAccount, uint256 initialBalance) public {
balances[initialAccount] = initialBalance;
totalSupply_ = initialBalance;
}
function mint (address account, uint256 amount) public {
balances[account] = balances[account].add(amount);
totalSupply_ = totalSupply_.add(amount);
}
/**
* @dev Total number of tokens in existence
*/
function totalSupply() public view returns (uint256) {
return totalSupply_;
}
/**
* @dev Gets the balance of the specified address.
* @param _owner The address to query the the balance of.
* @return An uint256 representing the amount owned by the passed address.
*/
function balanceOf(address _owner) public view returns (uint256) {
return balances[_owner];
}
/**
* @dev Function to check the amount of tokens that an owner allowed to a spender.
* @param _owner address The address which owns the funds.
* @param _spender address The address which will spend the funds.
* @return A uint256 specifying the amount of tokens still available for the spender.
*/
function allowance(
address _owner,
address _spender
)
public
view
returns (uint256)
{
return allowed[_owner][_spender];
}
/**
* @dev Transfer token for a specified address
* @param _to The address to transfer to.
* @param _value The amount to be transferred.
*/
function transfer(address _to, uint256 _value) public returns (bool) {
require(_value <= balances[msg.sender]);
require(_to != address(0));
balances[msg.sender] = balances[msg.sender].sub(_value);
balances[_to] = balances[_to].add(_value);
emit Transfer(msg.sender, _to, _value);
return false; // <--- Bad Token!!
}
/**
* @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender.
* Beware that changing an allowance with this method brings the risk that someone may use both the old
* and the new allowance by unfortunate transaction ordering. One possible solution to mitigate this
* race condition is to first reduce the spender's allowance to 0 and set the desired value afterwards:
* https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
* @param _spender The address which will spend the funds.
* @param _value The amount of tokens to be spent.
*/
function approve(address _spender, uint256 _value) public returns (bool) {
allowed[msg.sender][_spender] = _value;
emit Approval(msg.sender, _spender, _value);
return true;
}
/**
* @dev Transfer tokens from one address to another
* @param _from address The address which you want to send tokens from
* @param _to address The address which you want to transfer to
* @param _value uint256 the amount of tokens to be transferred
*/
function transferFrom(
address _from,
address _to,
uint256 _value
)
public
returns (bool)
{
require(_value <= balances[_from]);
require(_value <= allowed[_from][msg.sender]);
require(_to != address(0));
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;
}
/**
* @dev Increase the amount of tokens that an owner allowed to a spender.
* approve should be called when allowed[_spender] == 0. To increment
* allowed value is better to use this function to avoid 2 calls (and wait until
* the first transaction is mined)
* From MonolithDAO Token.sol
* @param _spender The address which will spend the funds.
* @param _addedValue The amount of tokens to increase the allowance by.
*/
function increaseApproval(
address _spender,
uint256 _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;
}
/**
* @dev Decrease the amount of tokens that an owner allowed to a spender.
* approve should be called when allowed[_spender] == 0. To decrement
* allowed value is better to use this function to avoid 2 calls (and wait until
* the first transaction is mined)
* From MonolithDAO Token.sol
* @param _spender The address which will spend the funds.
* @param _subtractedValue The amount of tokens to decrease the allowance by.
*/
function decreaseApproval(
address _spender,
uint256 _subtractedValue
)
public
returns (bool)
{
uint256 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;
}
/**
* @dev Internal function that mints an amount of the token and assigns it to
* an account. This encapsulates the modification of balances such that the
* proper events are emitted.
* @param _account The account that will receive the created tokens.
* @param _amount The amount that will be created.
*/
function _mint(address _account, uint256 _amount) internal {
require(_account != address(0));
totalSupply_ = totalSupply_.add(_amount);
balances[_account] = balances[_account].add(_amount);
emit Transfer(address(0), _account, _amount);
}
/**
* @dev Internal function that burns an amount of the token of a given
* account.
* @param _account The account whose tokens will be burnt.
* @param _amount The amount that will be burnt.
*/
function _burn(address _account, uint256 _amount) internal {
require(_account != address(0));
require(_amount <= balances[_account]);
totalSupply_ = totalSupply_.sub(_amount);
balances[_account] = balances[_account].sub(_amount);
emit Transfer(_account, address(0), _amount);
}
/**
* @dev Internal function that burns an amount of the token of a given
* account, deducting from the sender's allowance for said account. Uses the
* internal _burn function.
* @param _account The account whose tokens will be burnt.
* @param _amount The amount that will be burnt.
*/
function _burnFrom(address _account, uint256 _amount) internal {
require(_amount <= allowed[_account][msg.sender]);
// Should https://github.com/OpenZeppelin/zeppelin-solidity/issues/707 be accepted,
// this function needs to emit an event with the updated approval.
allowed[_account][msg.sender] = allowed[_account][msg.sender].sub(_amount);
_burn(_account, _amount);
}
}