Contract Name:
StakingPool
Contract Source Code:
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.12;
import "openzeppelin-solidity/contracts/math/SafeMath.sol";
struct AttoDecimal {
uint256 mantissa;
}
library AttoDecimalLib {
using SafeMath for uint256;
uint256 internal constant BASE = 10;
uint256 internal constant EXPONENTIATION = 18;
uint256 internal constant ONE_MANTISSA = BASE**EXPONENTIATION;
uint256 internal constant SQUARED_ONE_MANTISSA = ONE_MANTISSA * ONE_MANTISSA;
function convert(uint256 integer) internal pure returns (AttoDecimal memory) {
return AttoDecimal({mantissa: integer.mul(ONE_MANTISSA)});
}
function add(AttoDecimal memory a, AttoDecimal memory b) internal pure returns (AttoDecimal memory) {
return AttoDecimal({mantissa: a.mantissa.add(b.mantissa)});
}
function sub(AttoDecimal memory a, uint256 b) internal pure returns (AttoDecimal memory) {
return AttoDecimal({mantissa: a.mantissa.sub(b.mul(ONE_MANTISSA))});
}
function sub(AttoDecimal memory a, AttoDecimal memory b) internal pure returns (AttoDecimal memory) {
return AttoDecimal({mantissa: a.mantissa.sub(b.mantissa)});
}
function mul(AttoDecimal memory a, uint256 b) internal pure returns (AttoDecimal memory) {
return AttoDecimal({mantissa: a.mantissa.mul(b)});
}
function div(uint256 a, uint256 b) internal pure returns (AttoDecimal memory) {
return AttoDecimal({mantissa: a.mul(ONE_MANTISSA).div(b)});
}
function div(uint256 a, AttoDecimal memory b) internal pure returns (AttoDecimal memory) {
return AttoDecimal({mantissa: a.mul(SQUARED_ONE_MANTISSA).div(b.mantissa)});
}
function div(AttoDecimal memory a, AttoDecimal memory b) internal pure returns (AttoDecimal memory) {
return AttoDecimal({mantissa: a.mantissa.mul(ONE_MANTISSA).div(b.mantissa)});
}
function ceil(AttoDecimal memory a) internal pure returns (uint256) {
return a.mantissa.div(ONE_MANTISSA).add(a.mantissa % ONE_MANTISSA > 0 ? 1 : 0);
}
function floor(AttoDecimal memory a) internal pure returns (uint256) {
return a.mantissa.div(ONE_MANTISSA);
}
function lte(AttoDecimal memory a, AttoDecimal memory b) internal pure returns (bool) {
return a.mantissa <= b.mantissa;
}
function toTuple(AttoDecimal memory a)
internal
pure
returns (
uint256 mantissa,
uint256 base,
uint256 exponentiation
)
{
return (a.mantissa, BASE, EXPONENTIATION);
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.12;
interface IStakingPoolMigrator {
function stakingPoolV1Balance() external view returns (uint256);
function calculatePriceParams()
external
view
returns (uint256 stakingPoolV1Balance_, uint256 burnedSyntheticAmount);
function update() external returns (bool success);
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.12;
pragma experimental ABIEncoderV2;
import "openzeppelin-solidity/contracts/math/Math.sol";
import "openzeppelin-solidity/contracts/math/SafeMath.sol";
import "openzeppelin-solidity/contracts/token/ERC20/ERC20.sol";
import "openzeppelin-solidity/contracts/token/ERC20/IERC20.sol";
import "openzeppelin-solidity/contracts/token/ERC20/SafeERC20.sol";
import "openzeppelin-solidity/contracts/utils/ReentrancyGuard.sol";
import "./AttoDecimal.sol";
import "./IStakingPoolMigrator.sol";
import "./TwoStageOwnable.sol";
contract StakingPool is ERC20, ReentrancyGuard, TwoStageOwnable {
using SafeMath for uint256;
using SafeERC20 for IERC20;
using AttoDecimalLib for AttoDecimal;
struct Strategy {
uint256 endBlockNumber;
uint256 perBlockReward;
uint256 startBlockNumber;
}
struct Unstake {
uint256 amount;
uint256 applicableAt;
}
uint256 public constant MIN_STAKE_BALANCE = 10**18;
bool public migratorInitialized;
uint256 public claimingFeePercent;
uint256 public lastUpdateBlockNumber;
IStakingPoolMigrator public migrator;
uint256 private _feePool;
uint256 private _lockedRewards;
uint256 private _totalStaked;
uint256 private _totalUnstaked;
uint256 private _unstakingTime;
IERC20 private _stakingToken;
AttoDecimal private _DEFAULT_PRICE;
AttoDecimal private _price;
Strategy private _currentStrategy;
Strategy private _nextStrategy;
mapping(address => Unstake) private _unstakes;
function getBlockNumber() internal view virtual returns (uint256) {
return block.number;
}
function getTimestamp() internal view virtual returns (uint256) {
return block.timestamp;
}
function feePool() public view returns (uint256) {
return _feePool;
}
function lockedRewards() public view returns (uint256) {
return _lockedRewards;
}
function totalStaked() public view returns (uint256) {
return _totalStaked;
}
function totalUnstaked() public view returns (uint256) {
return _totalUnstaked;
}
function stakingToken() public view returns (IERC20) {
return _stakingToken;
}
function unstakingTime() public view returns (uint256) {
return _unstakingTime;
}
function currentStrategy() public view returns (Strategy memory) {
return _currentStrategy;
}
function nextStrategy() public view returns (Strategy memory) {
return _nextStrategy;
}
function getUnstake(address account) public view returns (Unstake memory result) {
result = _unstakes[account];
}
function DEFAULT_PRICE()
external
view
returns (
uint256 mantissa,
uint256 base,
uint256 exponentiation
)
{
return _DEFAULT_PRICE.toTuple();
}
function getCurrentStrategyUnlockedRewards() public view returns (uint256 unlocked) {
unlocked = _getStrategyUnlockedRewards(_currentStrategy);
}
function getUnlockedRewards() public view returns (uint256 unlocked, bool currentStrategyEnded) {
unlocked = _getStrategyUnlockedRewards(_currentStrategy);
if (_currentStrategy.endBlockNumber != 0 && getBlockNumber() >= _currentStrategy.endBlockNumber) {
currentStrategyEnded = true;
unlocked = unlocked.add(_getStrategyUnlockedRewards(_nextStrategy));
}
}
/// @notice Calculates price of synthetic token for current block
function price()
public
view
returns (
uint256 mantissa,
uint256 base,
uint256 exponentiation
)
{
(uint256 unlocked, ) = getUnlockedRewards();
uint256 totalStaked_ = _totalStaked;
uint256 totalSupply_ = totalSupply();
if (migratorInitialized) {
(uint256 stakingPoolV1Balance, uint256 burnedSyntheticAmount) = migrator.calculatePriceParams();
totalStaked_ = totalStaked_.add(stakingPoolV1Balance);
totalSupply_ = totalSupply_.sub(burnedSyntheticAmount);
}
AttoDecimal memory result;
if (totalSupply_ == 0) result = _DEFAULT_PRICE;
else result = AttoDecimalLib.div(totalStaked_.add(unlocked), totalSupply_);
return (result.mantissa, AttoDecimalLib.BASE, AttoDecimalLib.EXPONENTIATION);
}
/// @notice Returns last updated price of synthetic token
function priceStored()
public
view
returns (
uint256 mantissa,
uint256 base,
uint256 exponentiation
)
{
return (_price.mantissa, AttoDecimalLib.BASE, AttoDecimalLib.EXPONENTIATION);
}
/// @notice Calculates expected result of swapping synthetic tokens for OM tokens
/// @param account Account that wants to swap
/// @param amount Minimum amount of OM tokens that should be received at swapping process
/// @return unstakedAmount Amount of OM tokens that should be received at swapping process
/// @return burnedAmount Amount of synthetic tokens that should be burned at swapping process
function calculateUnstake(address account, uint256 amount)
public
view
returns (uint256 unstakedAmount, uint256 burnedAmount)
{
(uint256 mantissa_, , ) = price();
return _calculateUnstake(account, amount, AttoDecimal(mantissa_));
}
event Claimed(
address indexed account,
uint256 requestedAmount,
uint256 claimedAmount,
uint256 feeAmount,
uint256 burnedAmount
);
event CurrentStrategyUpdated(uint256 perBlockReward, uint256 startBlockNumber, uint256 endBlockNumber);
event FeeClaimed(address indexed receiver, uint256 amount);
event Migrated(
address indexed account,
uint256 omTokenV1StakeAmount,
uint256 stakingPoolV1Reward,
uint256 stakingPoolV2Reward
);
event MigratorInitialized();
event MigratorUpdated(address indexed migrator);
event NextStrategyUpdated(uint256 perBlockReward, uint256 startBlockNumber, uint256 endBlockNumber);
event UnstakingTimeUpdated(uint256 unstakingTime);
event NextStrategyRemoved();
event PoolIncreased(address indexed payer, uint256 amount);
event PriceUpdated(uint256 mantissa, uint256 base, uint256 exponentiation);
event RewardsUnlocked(uint256 amount);
event Staked(address indexed account, address indexed payer, uint256 stakedAmount, uint256 mintedAmount);
event Unstaked(address indexed account, uint256 requestedAmount, uint256 unstakedAmount, uint256 burnedAmount);
event UnstakingCanceled(address indexed account, uint256 amount);
event Withdrawed(address indexed account, uint256 amount);
constructor(
string memory syntheticTokenName,
string memory syntheticTokenSymbol,
IERC20 stakingToken_,
address owner_,
uint256 claimingFeePercent_,
uint256 perBlockReward_,
uint256 startBlockNumber_,
uint256 duration_,
uint256 unstakingTime_,
uint256 defaultPriceMantissa
) public TwoStageOwnable(owner_) ERC20(syntheticTokenName, syntheticTokenSymbol) {
_DEFAULT_PRICE = AttoDecimal(defaultPriceMantissa);
_stakingToken = stakingToken_;
_setClaimingFeePercent(claimingFeePercent_);
_validateStrategyParameters(perBlockReward_, startBlockNumber_, duration_);
_setUnstakingTime(unstakingTime_);
_setCurrentStrategy(perBlockReward_, startBlockNumber_, startBlockNumber_.add(duration_));
lastUpdateBlockNumber = getBlockNumber();
_price = _DEFAULT_PRICE;
}
/// @notice Burns synthetic tokens. May be called only by migrator contract
/// @param amount Synthetic tokens amount to be burned
function burn(uint256 amount) external onlyMigrator returns (bool success) {
_burn(msg.sender, amount);
return true;
}
/// @notice Cancels unstaking by staking locked for withdrawals tokens
/// @param amount Amount of locked for withdrawals tokens
function cancelUnstaking(uint256 amount) external onlyPositiveAmount(amount) returns (bool success) {
_update();
address caller = msg.sender;
Unstake storage unstake_ = _unstakes[caller];
uint256 unstakingAmount = unstake_.amount;
require(unstakingAmount >= amount, "Not enough unstaked balance");
uint256 stakedAmount = _price.mul(balanceOf(caller)).floor();
require(
stakedAmount.add(amount) >= MIN_STAKE_BALANCE,
"Resulting stake balance less than minimal stake balance"
);
uint256 synthAmount = AttoDecimalLib.div(amount, _price).floor();
_mint(caller, synthAmount);
_totalStaked = _totalStaked.add(amount);
_totalUnstaked = _totalUnstaked.sub(amount);
unstake_.amount = unstakingAmount.sub(amount);
emit Staked(caller, address(0), amount, synthAmount);
emit UnstakingCanceled(caller, amount);
return true;
}
/// @notice Swaps synthetic tokens for OM tokens and immediately sends them to the caller but takes some fee
/// @param amount OM tokens amount to swap for. Fee will be taked from this amount
/// @return claimedAmount Amount of OM tokens that was been sended to caller
/// @return burnedAmount Amount of synthetic tokens that was burned while swapping
function claim(uint256 amount)
external
onlyPositiveAmount(amount)
returns (uint256 claimedAmount, uint256 burnedAmount)
{
_update();
address caller = msg.sender;
(claimedAmount, burnedAmount) = _calculateUnstake(caller, amount, _price);
uint256 fee = claimedAmount.mul(claimingFeePercent).div(100);
_burn(caller, burnedAmount);
_totalStaked = _totalStaked.sub(claimedAmount);
claimedAmount = claimedAmount.sub(fee);
_feePool = _feePool.add(fee);
emit Claimed(caller, amount, claimedAmount, fee, burnedAmount);
_stakingToken.safeTransfer(caller, claimedAmount);
}
/// @notice Withdraws all OM tokens, that have been accumulated in imidiatly claiming process.
/// Allowed to be called only by the owner
/// @return amount Amount of accumulated and withdrawed tokens
function claimFees() external onlyOwner returns (uint256 amount) {
require(_feePool > 0, "No fees");
amount = _feePool;
_feePool = 0;
emit FeeClaimed(owner, amount);
_stakingToken.safeTransfer(owner, amount);
}
/// @notice Creates new strategy. Allowed to be called only by the owner
/// @param perBlockReward_ Reward that should be added to common OM tokens pool every block
/// @param startBlockNumber_ Number of block from which strategy should starts
/// @param duration_ Blocks count for which new strategy should be applied
function createNewStrategy(
uint256 perBlockReward_,
uint256 startBlockNumber_,
uint256 duration_
) public onlyOwner returns (bool success) {
_update();
_validateStrategyParameters(perBlockReward_, startBlockNumber_, duration_);
uint256 endBlockNumber = startBlockNumber_.add(duration_);
Strategy memory strategy =
Strategy({
perBlockReward: perBlockReward_,
startBlockNumber: startBlockNumber_,
endBlockNumber: endBlockNumber
});
if (_currentStrategy.startBlockNumber > getBlockNumber()) {
delete _nextStrategy;
emit NextStrategyRemoved();
_currentStrategy = strategy;
emit CurrentStrategyUpdated(perBlockReward_, startBlockNumber_, endBlockNumber);
} else {
emit NextStrategyUpdated(perBlockReward_, startBlockNumber_, endBlockNumber);
_nextStrategy = strategy;
if (_currentStrategy.endBlockNumber > startBlockNumber_) {
_currentStrategy.endBlockNumber = startBlockNumber_;
emit CurrentStrategyUpdated(
_currentStrategy.perBlockReward,
_currentStrategy.startBlockNumber,
startBlockNumber_
);
}
}
return true;
}
/// @notice Increases pool of rewards
/// @param amount Amount of OM tokens (in wei) that should be added to rewards pool
function increasePool(uint256 amount) external onlyPositiveAmount(amount) returns (bool success) {
_update();
address payer = msg.sender;
_lockedRewards = _lockedRewards.add(amount);
emit PoolIncreased(payer, amount);
_stakingToken.safeTransferFrom(payer, address(this), amount);
return true;
}
/// @notice Method may be called only by nominated migrator contract. Sets caller as a migrator
function initializeMigrator() external returns (bool success) {
_update();
assertCallerIsMigrator();
migratorInitialized = true;
emit MigratorInitialized();
return true;
}
/// @notice Mints requested amount of synthetic tokens to specific account.
/// This method can be called only by migrator
/// @param account Address for which synthetic tokens should be minted
/// @param amount Amount of synthetic tokens to be minted
function mint(address account, uint256 amount) external onlyMigrator returns (bool success) {
_mint(account, amount);
return true;
}
/// @notice Nominates some contract to the migrator role. Method allowed to be called only by the owner
/// @param migrator_ Address of migration contract to be nominated
function setMigrator(IStakingPoolMigrator migrator_) external onlyOwner returns (bool success) {
require(!migratorInitialized, "Migrator already initialized");
migrator = migrator_;
emit MigratorUpdated(address(migrator_));
return true;
}
/// @notice Converts OM tokens to synthetic tokens
/// @param amount Amount of OM tokens to be swapped
/// @return mintedAmount Amount of synthetic tokens that was received at swapping process
function stake(uint256 amount) external onlyPositiveAmount(amount) returns (uint256 mintedAmount) {
address staker = msg.sender;
return _stake(staker, staker, amount);
}
/// @notice Converts OM tokens to synthetic tokens and sends them to specific account
/// @param account Receiver of synthetic tokens
/// @param amount Amount of OM tokens to be swapped
/// @return mintedAmount Amount of synthetic tokens that was received by specified account at swapping process
function stakeForUser(address account, uint256 amount)
external
onlyPositiveAmount(amount)
returns (uint256 mintedAmount)
{
return _stake(account, msg.sender, amount);
}
/// @notice Moves locked for rewards OM tokens to OM tokens pool. Allowed to be called only by migrator contract
/// @param amount Amount of OM tokens to be unlocked
/// @dev Will cause price increasing from next block
function unlockRewards(uint256 amount) external onlyMigrator returns (bool success) {
_lockedRewards = _lockedRewards.sub(amount, "Reward pool is extinguished");
_totalStaked = _totalStaked.add(amount);
emit RewardsUnlocked(amount);
return true;
}
/// @notice Swapes synthetic tokens for OM tokens and locks them for some period
/// @param amount Minimum amount of OM tokens that should be locked after swapping process
/// @return unstakedAmount Amount of OM tokens that was locked
/// @return burnedAmount Amount of synthetic tokens that was burned
function unstake(uint256 amount)
external
onlyPositiveAmount(amount)
returns (uint256 unstakedAmount, uint256 burnedAmount)
{
_update();
address caller = msg.sender;
(unstakedAmount, burnedAmount) = _calculateUnstake(caller, amount, _price);
_burn(caller, burnedAmount);
_totalStaked = _totalStaked.sub(unstakedAmount);
_totalUnstaked = _totalUnstaked.add(unstakedAmount);
Unstake storage unstake_ = _unstakes[caller];
unstake_.amount = unstake_.amount.add(unstakedAmount);
unstake_.applicableAt = getTimestamp().add(_unstakingTime);
emit Unstaked(caller, amount, unstakedAmount, burnedAmount);
}
/// @notice Swapes migrator's synthetic tokens for OM tokens and imidiatly sends them.
/// Allowed to be called only by migrator contract
/// @param amount Amount of OM tokens that should be received from swapping process
/// @return synthToBurn Amount of burned synthetic tokens
function unstakeLocked(uint256 amount) external onlyMigrator returns (uint256 synthToBurn) {
_update();
synthToBurn = AttoDecimalLib.div(amount, _price).floor();
_burn(address(migrator), synthToBurn);
_totalStaked = _totalStaked.sub(amount, "Not enough staked OM amount");
_stakingToken.safeTransfer(address(migrator), amount);
}
/// @notice Updates price of synthetic token
/// @dev Automatically has been called on every contract action, that uses or can affect price
function update() external returns (bool success) {
_update();
return true;
}
/// @notice Withdraws unstaked OM tokens
function withdraw() external returns (bool success) {
address caller = msg.sender;
Unstake storage unstake_ = _unstakes[caller];
uint256 amount = unstake_.amount;
require(amount > 0, "Not unstaked");
require(unstake_.applicableAt <= getTimestamp(), "Not released at");
delete _unstakes[caller];
_totalUnstaked = _totalUnstaked.sub(amount);
emit Withdrawed(caller, amount);
_stakingToken.safeTransfer(caller, amount);
return true;
}
/// @notice Change unstaking time. Can be called only by the owner
/// @param unstakingTime_ New unstaking process duration in seconds
function setUnstakingTime(uint256 unstakingTime_) external onlyOwner returns (bool success) {
_setUnstakingTime(unstakingTime_);
return true;
}
function _getStrategyUnlockedRewards(Strategy memory strategy_) internal view returns (uint256 unlocked) {
uint256 currentBlockNumber = getBlockNumber();
if (currentBlockNumber < strategy_.startBlockNumber || currentBlockNumber == lastUpdateBlockNumber) {
return unlocked;
}
uint256 lastRewardedBlockNumber = Math.max(lastUpdateBlockNumber, strategy_.startBlockNumber);
uint256 lastRewardableBlockNumber = Math.min(currentBlockNumber, strategy_.endBlockNumber);
if (lastRewardedBlockNumber < lastRewardableBlockNumber) {
uint256 blocksDiff = lastRewardableBlockNumber.sub(lastRewardedBlockNumber);
unlocked = unlocked.add(blocksDiff.mul(strategy_.perBlockReward));
}
}
function _calculateUnstake(
address account,
uint256 amount,
AttoDecimal memory price_
) internal view returns (uint256 unstakedAmount, uint256 burnedAmount) {
unstakedAmount = amount;
burnedAmount = AttoDecimalLib.div(amount, price_).ceil();
uint256 balance = balanceOf(account);
require(burnedAmount > 0, "Too small unstaking amount");
require(balance >= burnedAmount, "Not enough synthetic tokens");
uint256 remainingSyntheticBalance = balance.sub(burnedAmount);
uint256 remainingStake = _price.mul(remainingSyntheticBalance).floor();
if (remainingStake < 10**18) {
burnedAmount = balance;
unstakedAmount = unstakedAmount.add(remainingStake);
}
}
function _unlockRewardsAndStake() internal {
(uint256 unlocked, bool currentStrategyEnded) = getUnlockedRewards();
if (currentStrategyEnded) {
_currentStrategy = _nextStrategy;
emit NextStrategyRemoved();
if (_currentStrategy.endBlockNumber != 0) {
emit CurrentStrategyUpdated(
_currentStrategy.perBlockReward,
_currentStrategy.startBlockNumber,
_currentStrategy.endBlockNumber
);
}
delete _nextStrategy;
}
unlocked = Math.min(unlocked, _lockedRewards);
if (unlocked > 0) {
emit RewardsUnlocked(unlocked);
_lockedRewards = _lockedRewards.sub(unlocked);
_totalStaked = _totalStaked.add(unlocked);
}
lastUpdateBlockNumber = getBlockNumber();
}
function _update() internal {
if (getBlockNumber() <= lastUpdateBlockNumber) return;
if (migratorInitialized) migrator.update();
_unlockRewardsAndStake();
_updatePrice();
}
function _updatePrice() internal {
uint256 totalStaked_ = _totalStaked;
uint256 totalSupply_ = totalSupply();
if (migratorInitialized) totalStaked_ = totalStaked_.add(migrator.stakingPoolV1Balance());
if (totalSupply_ == 0) _price = _DEFAULT_PRICE;
else _price = AttoDecimalLib.div(totalStaked_, totalSupply_);
emit PriceUpdated(_price.mantissa, AttoDecimalLib.BASE, AttoDecimalLib.EXPONENTIATION);
}
function _validateStrategyParameters(
uint256 perBlockReward,
uint256 startBlockNumber,
uint256 duration
) internal view {
require(duration > 0, "Duration is zero");
require(startBlockNumber >= getBlockNumber(), "Start block number less then current");
require(perBlockReward <= 188 * 10**18, "Per block reward overflow");
}
function _setClaimingFeePercent(uint256 feePercent) internal {
require(feePercent >= 0 && feePercent <= 100, "Percent fee should be in range [0; 100]");
claimingFeePercent = feePercent;
}
function _setUnstakingTime(uint256 unstakingTime_) internal {
_unstakingTime = unstakingTime_;
emit UnstakingTimeUpdated(unstakingTime_);
}
function _beforeTokenTransfer(
address from,
address to,
uint256 amount
) internal override {
if (msg.sender == address(migrator)) return;
_update();
string memory errorText = "Minimal stake balance should be more or equal to 1 token";
if (from != address(0)) {
uint256 fromNewBalance = _price.mul(balanceOf(from).sub(amount)).floor();
require(fromNewBalance >= MIN_STAKE_BALANCE || fromNewBalance == 0, errorText);
}
if (to != address(0)) {
require(_price.mul(balanceOf(to).add(amount)).floor() >= MIN_STAKE_BALANCE, errorText);
}
}
function _setCurrentStrategy(
uint256 perBlockReward_,
uint256 startBlockNumber_,
uint256 endBlockNumber_
) private {
_currentStrategy = Strategy({
perBlockReward: perBlockReward_,
startBlockNumber: startBlockNumber_,
endBlockNumber: endBlockNumber_
});
emit CurrentStrategyUpdated(perBlockReward_, startBlockNumber_, endBlockNumber_);
}
function _stake(
address staker,
address payer,
uint256 amount
) private returns (uint256 mintedAmount) {
_update();
mintedAmount = AttoDecimalLib.div(amount, _price).floor();
require(mintedAmount > 0, "Too small staking amount");
_mint(staker, mintedAmount);
_totalStaked = _totalStaked.add(amount);
emit Staked(staker, payer, amount, mintedAmount);
_stakingToken.safeTransferFrom(payer, address(this), amount);
}
function assertCallerIsMigrator() internal view {
require(msg.sender == address(migrator), "Allowed only by migrator");
}
modifier onlyMigrator() {
assertCallerIsMigrator();
require(migratorInitialized, "Migrator not initialized");
_;
}
modifier onlyPositiveAmount(uint256 amount) {
require(amount > 0, "Amount is not positive");
_;
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.12;
abstract contract TwoStageOwnable {
address public nominatedOwner;
address public owner;
event OwnerChanged(address indexed newOwner);
event OwnerNominated(address indexed nominatedOwner);
constructor(address owner_) internal {
require(owner_ != address(0), "Owner cannot be zero address");
_setOwner(owner_);
}
function acceptOwnership() external returns (bool success) {
require(msg.sender == nominatedOwner, "Not nominated to ownership");
_setOwner(nominatedOwner);
nominatedOwner = address(0);
return true;
}
function nominateNewOwner(address owner_) external onlyOwner returns (bool success) {
_nominateNewOwner(owner_);
return true;
}
modifier onlyOwner {
require(msg.sender == owner, "Ownable: caller is not the owner");
_;
}
function _nominateNewOwner(address owner_) internal {
nominatedOwner = owner_;
emit OwnerNominated(owner_);
}
function _setOwner(address newOwner) internal {
owner = newOwner;
emit OwnerChanged(newOwner);
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
/*
* @dev Provides information about the current execution context, including the
* sender of the transaction and its data. While these are generally available
* via msg.sender and msg.data, they should not be accessed in such a direct
* manner, since when dealing with GSN meta-transactions the account sending and
* paying for execution may not be the actual sender (as far as an application
* is concerned).
*
* This contract is only required for intermediate, library-like contracts.
*/
abstract contract Context {
function _msgSender() internal view virtual returns (address payable) {
return msg.sender;
}
function _msgData() internal view virtual returns (bytes memory) {
this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
return msg.data;
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
/**
* @dev Standard math utilities missing in the Solidity language.
*/
library Math {
/**
* @dev Returns the largest of two numbers.
*/
function max(uint256 a, uint256 b) internal pure returns (uint256) {
return a >= b ? a : b;
}
/**
* @dev Returns the smallest of two numbers.
*/
function min(uint256 a, uint256 b) internal pure returns (uint256) {
return a < b ? a : b;
}
/**
* @dev Returns the average of two numbers. The result is rounded towards
* zero.
*/
function average(uint256 a, uint256 b) internal pure returns (uint256) {
// (a + b) / 2 can overflow, so we distribute
return (a / 2) + (b / 2) + ((a % 2 + b % 2) / 2);
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
/**
* @dev Wrappers over Solidity's arithmetic operations with added overflow
* checks.
*
* Arithmetic operations in Solidity wrap on overflow. This can easily result
* in bugs, because programmers usually assume that an overflow raises an
* error, which is the standard behavior in high level programming languages.
* `SafeMath` restores this intuition by reverting the transaction when an
* operation overflows.
*
* Using this library instead of the unchecked operations eliminates an entire
* class of bugs, so it's recommended to use it always.
*/
library SafeMath {
/**
* @dev Returns the addition of two unsigned integers, reverting on
* overflow.
*
* Counterpart to Solidity's `+` operator.
*
* Requirements:
*
* - Addition cannot overflow.
*/
function add(uint256 a, uint256 b) internal pure returns (uint256) {
uint256 c = a + b;
require(c >= a, "SafeMath: addition overflow");
return c;
}
/**
* @dev Returns the subtraction of two unsigned integers, reverting on
* overflow (when the result is negative).
*
* Counterpart to Solidity's `-` operator.
*
* Requirements:
*
* - Subtraction cannot overflow.
*/
function sub(uint256 a, uint256 b) internal pure returns (uint256) {
return sub(a, b, "SafeMath: subtraction overflow");
}
/**
* @dev Returns the subtraction of two unsigned integers, reverting with custom message on
* overflow (when the result is negative).
*
* Counterpart to Solidity's `-` operator.
*
* Requirements:
*
* - Subtraction cannot overflow.
*/
function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
require(b <= a, errorMessage);
uint256 c = a - b;
return c;
}
/**
* @dev Returns the multiplication of two unsigned integers, reverting on
* overflow.
*
* Counterpart to Solidity's `*` operator.
*
* Requirements:
*
* - Multiplication cannot 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-contracts/pull/522
if (a == 0) {
return 0;
}
uint256 c = a * b;
require(c / a == b, "SafeMath: multiplication overflow");
return c;
}
/**
* @dev Returns the integer division of two unsigned integers. Reverts on
* division by zero. The result is rounded towards zero.
*
* Counterpart to Solidity's `/` operator. Note: this function uses a
* `revert` opcode (which leaves remaining gas untouched) while Solidity
* uses an invalid opcode to revert (consuming all remaining gas).
*
* Requirements:
*
* - The divisor cannot be zero.
*/
function div(uint256 a, uint256 b) internal pure returns (uint256) {
return div(a, b, "SafeMath: division by zero");
}
/**
* @dev Returns the integer division of two unsigned integers. Reverts with custom message on
* division by zero. The result is rounded towards zero.
*
* Counterpart to Solidity's `/` operator. Note: this function uses a
* `revert` opcode (which leaves remaining gas untouched) while Solidity
* uses an invalid opcode to revert (consuming all remaining gas).
*
* Requirements:
*
* - The divisor cannot be zero.
*/
function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
require(b > 0, errorMessage);
uint256 c = a / b;
// assert(a == b * c + a % b); // There is no case in which this doesn't hold
return c;
}
/**
* @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
* Reverts when dividing by zero.
*
* Counterpart to Solidity's `%` operator. This function uses a `revert`
* opcode (which leaves remaining gas untouched) while Solidity uses an
* invalid opcode to revert (consuming all remaining gas).
*
* Requirements:
*
* - The divisor cannot be zero.
*/
function mod(uint256 a, uint256 b) internal pure returns (uint256) {
return mod(a, b, "SafeMath: modulo by zero");
}
/**
* @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
* Reverts with custom message when dividing by zero.
*
* Counterpart to Solidity's `%` operator. This function uses a `revert`
* opcode (which leaves remaining gas untouched) while Solidity uses an
* invalid opcode to revert (consuming all remaining gas).
*
* Requirements:
*
* - The divisor cannot be zero.
*/
function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
require(b != 0, errorMessage);
return a % b;
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
import "../../GSN/Context.sol";
import "./IERC20.sol";
import "../../math/SafeMath.sol";
import "../../utils/Address.sol";
/**
* @dev Implementation of the {IERC20} interface.
*
* This implementation is agnostic to the way tokens are created. This means
* that a supply mechanism has to be added in a derived contract using {_mint}.
* For a generic mechanism see {ERC20PresetMinterPauser}.
*
* TIP: For a detailed writeup see our guide
* https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
* to implement supply mechanisms].
*
* We have followed general OpenZeppelin guidelines: functions revert instead
* of returning `false` on failure. This behavior is nonetheless conventional
* and does not conflict with the expectations of ERC20 applications.
*
* Additionally, an {Approval} event is emitted on calls to {transferFrom}.
* This allows applications to reconstruct the allowance for all accounts just
* by listening to said events. Other implementations of the EIP may not emit
* these events, as it isn't required by the specification.
*
* Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
* functions have been added to mitigate the well-known issues around setting
* allowances. See {IERC20-approve}.
*/
contract ERC20 is Context, IERC20 {
using SafeMath for uint256;
using Address for address;
mapping (address => uint256) private _balances;
mapping (address => mapping (address => uint256)) private _allowances;
uint256 private _totalSupply;
string private _name;
string private _symbol;
uint8 private _decimals;
/**
* @dev Sets the values for {name} and {symbol}, initializes {decimals} with
* a default value of 18.
*
* To select a different value for {decimals}, use {_setupDecimals}.
*
* All three of these values are immutable: they can only be set once during
* construction.
*/
constructor (string memory name, string memory symbol) public {
_name = name;
_symbol = symbol;
_decimals = 18;
}
/**
* @dev Returns the name of the token.
*/
function name() public view returns (string memory) {
return _name;
}
/**
* @dev Returns the symbol of the token, usually a shorter version of the
* name.
*/
function symbol() public view returns (string memory) {
return _symbol;
}
/**
* @dev Returns the number of decimals used to get its user representation.
* For example, if `decimals` equals `2`, a balance of `505` tokens should
* be displayed to a user as `5,05` (`505 / 10 ** 2`).
*
* Tokens usually opt for a value of 18, imitating the relationship between
* Ether and Wei. This is the value {ERC20} uses, unless {_setupDecimals} is
* called.
*
* NOTE: This information is only used for _display_ purposes: it in
* no way affects any of the arithmetic of the contract, including
* {IERC20-balanceOf} and {IERC20-transfer}.
*/
function decimals() public view returns (uint8) {
return _decimals;
}
/**
* @dev See {IERC20-totalSupply}.
*/
function totalSupply() public view override returns (uint256) {
return _totalSupply;
}
/**
* @dev See {IERC20-balanceOf}.
*/
function balanceOf(address account) public view override returns (uint256) {
return _balances[account];
}
/**
* @dev See {IERC20-transfer}.
*
* Requirements:
*
* - `recipient` cannot be the zero address.
* - the caller must have a balance of at least `amount`.
*/
function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
_transfer(_msgSender(), recipient, amount);
return true;
}
/**
* @dev See {IERC20-allowance}.
*/
function allowance(address owner, address spender) public view virtual override returns (uint256) {
return _allowances[owner][spender];
}
/**
* @dev See {IERC20-approve}.
*
* Requirements:
*
* - `spender` cannot be the zero address.
*/
function approve(address spender, uint256 amount) public virtual override returns (bool) {
_approve(_msgSender(), spender, amount);
return true;
}
/**
* @dev See {IERC20-transferFrom}.
*
* Emits an {Approval} event indicating the updated allowance. This is not
* required by the EIP. See the note at the beginning of {ERC20};
*
* Requirements:
* - `sender` and `recipient` cannot be the zero address.
* - `sender` must have a balance of at least `amount`.
* - the caller must have allowance for ``sender``'s tokens of at least
* `amount`.
*/
function transferFrom(address sender, address recipient, uint256 amount) public virtual override returns (bool) {
_transfer(sender, recipient, amount);
_approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance"));
return true;
}
/**
* @dev Atomically increases the allowance granted to `spender` by the caller.
*
* This is an alternative to {approve} that can be used as a mitigation for
* problems described in {IERC20-approve}.
*
* Emits an {Approval} event indicating the updated allowance.
*
* Requirements:
*
* - `spender` cannot be the zero address.
*/
function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
_approve(_msgSender(), spender, _allowances[_msgSender()][spender].add(addedValue));
return true;
}
/**
* @dev Atomically decreases the allowance granted to `spender` by the caller.
*
* This is an alternative to {approve} that can be used as a mitigation for
* problems described in {IERC20-approve}.
*
* Emits an {Approval} event indicating the updated allowance.
*
* Requirements:
*
* - `spender` cannot be the zero address.
* - `spender` must have allowance for the caller of at least
* `subtractedValue`.
*/
function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
_approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, "ERC20: decreased allowance below zero"));
return true;
}
/**
* @dev Moves tokens `amount` from `sender` to `recipient`.
*
* This is internal function is equivalent to {transfer}, and can be used to
* e.g. implement automatic token fees, slashing mechanisms, etc.
*
* Emits a {Transfer} event.
*
* Requirements:
*
* - `sender` cannot be the zero address.
* - `recipient` cannot be the zero address.
* - `sender` must have a balance of at least `amount`.
*/
function _transfer(address sender, address recipient, uint256 amount) internal virtual {
require(sender != address(0), "ERC20: transfer from the zero address");
require(recipient != address(0), "ERC20: transfer to the zero address");
_beforeTokenTransfer(sender, recipient, amount);
_balances[sender] = _balances[sender].sub(amount, "ERC20: transfer amount exceeds balance");
_balances[recipient] = _balances[recipient].add(amount);
emit Transfer(sender, recipient, amount);
}
/** @dev Creates `amount` tokens and assigns them to `account`, increasing
* the total supply.
*
* Emits a {Transfer} event with `from` set to the zero address.
*
* Requirements
*
* - `to` cannot be the zero address.
*/
function _mint(address account, uint256 amount) internal virtual {
require(account != address(0), "ERC20: mint to the zero address");
_beforeTokenTransfer(address(0), account, amount);
_totalSupply = _totalSupply.add(amount);
_balances[account] = _balances[account].add(amount);
emit Transfer(address(0), account, amount);
}
/**
* @dev Destroys `amount` tokens from `account`, reducing the
* total supply.
*
* Emits a {Transfer} event with `to` set to the zero address.
*
* Requirements
*
* - `account` cannot be the zero address.
* - `account` must have at least `amount` tokens.
*/
function _burn(address account, uint256 amount) internal virtual {
require(account != address(0), "ERC20: burn from the zero address");
_beforeTokenTransfer(account, address(0), amount);
_balances[account] = _balances[account].sub(amount, "ERC20: burn amount exceeds balance");
_totalSupply = _totalSupply.sub(amount);
emit Transfer(account, address(0), amount);
}
/**
* @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
*
* This internal function is equivalent to `approve`, and can be used to
* e.g. set automatic allowances for certain subsystems, etc.
*
* Emits an {Approval} event.
*
* Requirements:
*
* - `owner` cannot be the zero address.
* - `spender` cannot be the zero address.
*/
function _approve(address owner, address spender, uint256 amount) internal virtual {
require(owner != address(0), "ERC20: approve from the zero address");
require(spender != address(0), "ERC20: approve to the zero address");
_allowances[owner][spender] = amount;
emit Approval(owner, spender, amount);
}
/**
* @dev Sets {decimals} to a value other than the default one of 18.
*
* WARNING: This function should only be called from the constructor. Most
* applications that interact with token contracts will not expect
* {decimals} to ever change, and may work incorrectly if it does.
*/
function _setupDecimals(uint8 decimals_) internal {
_decimals = decimals_;
}
/**
* @dev Hook that is called before any transfer of tokens. This includes
* minting and burning.
*
* Calling conditions:
*
* - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
* will be to transferred to `to`.
* - when `from` is zero, `amount` tokens will be minted for `to`.
* - when `to` is zero, `amount` of ``from``'s tokens will be burned.
* - `from` and `to` are never both zero.
*
* To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
*/
function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual { }
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
/**
* @dev Interface of the ERC20 standard as defined in the EIP.
*/
interface IERC20 {
/**
* @dev Returns the amount of tokens in existence.
*/
function totalSupply() external view returns (uint256);
/**
* @dev Returns the amount of tokens owned by `account`.
*/
function balanceOf(address account) external view returns (uint256);
/**
* @dev Moves `amount` tokens from the caller's account to `recipient`.
*
* Returns a boolean value indicating whether the operation succeeded.
*
* Emits a {Transfer} event.
*/
function transfer(address recipient, uint256 amount) external returns (bool);
/**
* @dev Returns the remaining number of tokens that `spender` will be
* allowed to spend on behalf of `owner` through {transferFrom}. This is
* zero by default.
*
* This value changes when {approve} or {transferFrom} are called.
*/
function allowance(address owner, address spender) external view returns (uint256);
/**
* @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
*
* Returns a boolean value indicating whether the operation succeeded.
*
* IMPORTANT: 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
*
* Emits an {Approval} event.
*/
function approve(address spender, uint256 amount) external returns (bool);
/**
* @dev Moves `amount` tokens from `sender` to `recipient` using the
* allowance mechanism. `amount` is then deducted from the caller's
* allowance.
*
* Returns a boolean value indicating whether the operation succeeded.
*
* Emits a {Transfer} event.
*/
function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
/**
* @dev Emitted when `value` tokens are moved from one account (`from`) to
* another (`to`).
*
* Note that `value` may be zero.
*/
event Transfer(address indexed from, address indexed to, uint256 value);
/**
* @dev Emitted when the allowance of a `spender` for an `owner` is set by
* a call to {approve}. `value` is the new allowance.
*/
event Approval(address indexed owner, address indexed spender, uint256 value);
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
import "./IERC20.sol";
import "../../math/SafeMath.sol";
import "../../utils/Address.sol";
/**
* @title SafeERC20
* @dev Wrappers around ERC20 operations that throw on failure (when the token
* contract returns false). Tokens that return no value (and instead revert or
* throw on failure) are also supported, non-reverting calls are assumed to be
* successful.
* To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
* which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
*/
library SafeERC20 {
using SafeMath for uint256;
using Address for address;
function safeTransfer(IERC20 token, address to, uint256 value) internal {
_callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
}
function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
_callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
}
/**
* @dev Deprecated. This function has issues similar to the ones found in
* {IERC20-approve}, and its usage is discouraged.
*
* Whenever possible, use {safeIncreaseAllowance} and
* {safeDecreaseAllowance} instead.
*/
function safeApprove(IERC20 token, address spender, uint256 value) internal {
// safeApprove should only be called when setting an initial allowance,
// or when resetting it to zero. To increase and decrease it, use
// 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
// solhint-disable-next-line max-line-length
require((value == 0) || (token.allowance(address(this), spender) == 0),
"SafeERC20: approve from non-zero to non-zero allowance"
);
_callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
}
function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
uint256 newAllowance = token.allowance(address(this), spender).add(value);
_callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
}
function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
uint256 newAllowance = token.allowance(address(this), spender).sub(value, "SafeERC20: decreased allowance below zero");
_callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
}
/**
* @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
* on the return value: the return value is optional (but if data is returned, it must not be false).
* @param token The token targeted by the call.
* @param data The call data (encoded using abi.encode or one of its variants).
*/
function _callOptionalReturn(IERC20 token, bytes memory data) private {
// We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
// we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
// the target address contains contract code and also asserts for success in the low-level call.
bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
if (returndata.length > 0) { // Return data is optional
// solhint-disable-next-line max-line-length
require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
}
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.2;
/**
* @dev Collection of functions related to the address type
*/
library Address {
/**
* @dev Returns true if `account` is a contract.
*
* [IMPORTANT]
* ====
* It is unsafe to assume that an address for which this function returns
* false is an externally-owned account (EOA) and not a contract.
*
* Among others, `isContract` will return false for the following
* types of addresses:
*
* - an externally-owned account
* - a contract in construction
* - an address where a contract will be created
* - an address where a contract lived, but was destroyed
* ====
*/
function isContract(address account) internal view returns (bool) {
// This method relies in extcodesize, which returns 0 for contracts in
// construction, since the code is only stored at the end of the
// constructor execution.
uint256 size;
// solhint-disable-next-line no-inline-assembly
assembly { size := extcodesize(account) }
return size > 0;
}
/**
* @dev Replacement for Solidity's `transfer`: sends `amount` wei to
* `recipient`, forwarding all available gas and reverting on errors.
*
* https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
* of certain opcodes, possibly making contracts go over the 2300 gas limit
* imposed by `transfer`, making them unable to receive funds via
* `transfer`. {sendValue} removes this limitation.
*
* https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
*
* IMPORTANT: because control is transferred to `recipient`, care must be
* taken to not create reentrancy vulnerabilities. Consider using
* {ReentrancyGuard} or the
* https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
*/
function sendValue(address payable recipient, uint256 amount) internal {
require(address(this).balance >= amount, "Address: insufficient balance");
// solhint-disable-next-line avoid-low-level-calls, avoid-call-value
(bool success, ) = recipient.call{ value: amount }("");
require(success, "Address: unable to send value, recipient may have reverted");
}
/**
* @dev Performs a Solidity function call using a low level `call`. A
* plain`call` is an unsafe replacement for a function call: use this
* function instead.
*
* If `target` reverts with a revert reason, it is bubbled up by this
* function (like regular Solidity function calls).
*
* Returns the raw returned data. To convert to the expected return value,
* use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
*
* Requirements:
*
* - `target` must be a contract.
* - calling `target` with `data` must not revert.
*
* _Available since v3.1._
*/
function functionCall(address target, bytes memory data) internal returns (bytes memory) {
return functionCall(target, data, "Address: low-level call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
* `errorMessage` as a fallback revert reason when `target` reverts.
*
* _Available since v3.1._
*/
function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
return _functionCallWithValue(target, data, 0, errorMessage);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but also transferring `value` wei to `target`.
*
* Requirements:
*
* - the calling contract must have an ETH balance of at least `value`.
* - the called Solidity function must be `payable`.
*
* _Available since v3.1._
*/
function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
}
/**
* @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
* with `errorMessage` as a fallback revert reason when `target` reverts.
*
* _Available since v3.1._
*/
function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
require(address(this).balance >= value, "Address: insufficient balance for call");
return _functionCallWithValue(target, data, value, errorMessage);
}
function _functionCallWithValue(address target, bytes memory data, uint256 weiValue, string memory errorMessage) private returns (bytes memory) {
require(isContract(target), "Address: call to non-contract");
// solhint-disable-next-line avoid-low-level-calls
(bool success, bytes memory returndata) = target.call{ value: weiValue }(data);
if (success) {
return returndata;
} else {
// Look for revert reason and bubble it up if present
if (returndata.length > 0) {
// The easiest way to bubble the revert reason is using memory via assembly
// solhint-disable-next-line no-inline-assembly
assembly {
let returndata_size := mload(returndata)
revert(add(32, returndata), returndata_size)
}
} else {
revert(errorMessage);
}
}
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
/**
* @dev Contract module that helps prevent reentrant calls to a function.
*
* Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
* available, which can be applied to functions to make sure there are no nested
* (reentrant) calls to them.
*
* Note that because there is a single `nonReentrant` guard, functions marked as
* `nonReentrant` may not call one another. This can be worked around by making
* those functions `private`, and then adding `external` `nonReentrant` entry
* points to them.
*
* TIP: If you would like to learn more about reentrancy and alternative ways
* to protect against it, check out our blog post
* https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
*/
contract ReentrancyGuard {
// Booleans are more expensive than uint256 or any type that takes up a full
// word because each write operation emits an extra SLOAD to first read the
// slot's contents, replace the bits taken up by the boolean, and then write
// back. This is the compiler's defense against contract upgrades and
// pointer aliasing, and it cannot be disabled.
// The values being non-zero value makes deployment a bit more expensive,
// but in exchange the refund on every call to nonReentrant will be lower in
// amount. Since refunds are capped to a percentage of the total
// transaction's gas, it is best to keep them low in cases like this one, to
// increase the likelihood of the full refund coming into effect.
uint256 private constant _NOT_ENTERED = 1;
uint256 private constant _ENTERED = 2;
uint256 private _status;
constructor () internal {
_status = _NOT_ENTERED;
}
/**
* @dev Prevents a contract from calling itself, directly or indirectly.
* Calling a `nonReentrant` function from another `nonReentrant`
* function is not supported. It is possible to prevent this from happening
* by making the `nonReentrant` function external, and make it call a
* `private` function that does the actual work.
*/
modifier nonReentrant() {
// On the first call to nonReentrant, _notEntered will be true
require(_status != _ENTERED, "ReentrancyGuard: reentrant call");
// Any calls to nonReentrant after this point will fail
_status = _ENTERED;
_;
// By storing the original value once again, a refund is triggered (see
// https://eips.ethereum.org/EIPS/eip-2200)
_status = _NOT_ENTERED;
}
}