Contract Name:
FestakedWithReward
Contract Source Code:
pragma solidity >=0.6.0 <0.8.0;
import "@openzeppelin/contracts/math/SafeMath.sol";
import "@openzeppelin/contracts/token/ERC20/SafeERC20.sol";
library SafeAmount {
using SafeMath for uint256;
using SafeERC20 for IERC20;
function safeTransferFrom(
address token,
address from,
address to,
uint256 amount) internal returns (uint256) {
uint256 preBalance = IERC20(token).balanceOf(to);
IERC20(token).transferFrom(from, to, amount);
uint256 postBalance = IERC20(token).balanceOf(to);
return postBalance.sub(preBalance);
}
}
pragma solidity >=0.6.0 <0.8.0;
import "../common/SafeAmount.sol";
import "@openzeppelin/contracts/math/SafeMath.sol";
import "@openzeppelin/contracts/token/ERC20/SafeERC20.sol";
library FestakedLib {
using SafeMath for uint256;
using SafeERC20 for IERC20;
event Staked(address indexed token, address indexed staker_, uint256 requestedAmount_, uint256 stakedAmount_);
event PaidOut(address indexed token, address indexed rewardToken, address indexed staker_, uint256 amount_, uint256 reward_);
struct FestakeState {
uint256 stakedTotal;
uint256 stakingCap;
uint256 stakedBalance;
uint256 withdrawnEarly;
mapping(address => uint256) _stakes;
}
struct FestakeRewardState {
uint256 rewardBalance;
uint256 rewardsTotal;
uint256 earlyWithdrawReward;
}
function VERSION() external pure returns(uint) {
return 1001;
}
function tryStake(address payer, address staker, uint256 amount,
uint256 stakingStarts,
uint256 stakingEnds,
uint256 stakingCap,
address tokenAddress,
FestakeState storage state
)
public
_after(stakingStarts)
_before(stakingEnds)
_positive(amount)
returns (uint256) {
// check the remaining amount to be staked
// For pay per transfer tokens we limit the cap on incoming tokens for simplicity. This might
// mean that cap may not necessary fill completely which is ok.
uint256 remaining = amount;
// uint256 stakedTotal = state.stakedTotal;
{
uint256 stakedBalance = state.stakedBalance;
if (stakingCap > 0 && remaining > (stakingCap.sub(stakedBalance))) {
remaining = stakingCap.sub(stakedBalance);
}
}
// These requires are not necessary, because it will never happen, but won't hurt to double check
// this is because stakedTotal and stakedBalance are only modified in this method during the staking period
require(remaining > 0, "Festaking: Staking cap is filled");
// require((remaining + stakedTotal) <= stakingCap, "Festaking: this will increase staking amount pass the cap");
// Update remaining in case actual amount paid was different.
remaining = _payMe(payer, remaining, tokenAddress);
emit Staked(tokenAddress, staker, amount, remaining);
// Transfer is completed
return remaining;
}
function stake(address payer, address staker, uint256 amount,
uint256 stakingStarts,
uint256 stakingEnds,
uint256 stakingCap,
address tokenAddress,
FestakeState storage state
)
external
returns (bool) {
uint256 remaining = tryStake(payer, staker, amount,
stakingStarts, stakingEnds, stakingCap, tokenAddress, state);
// Transfer is completed
state.stakedBalance = state.stakedBalance.add(remaining);
state.stakedTotal = state.stakedTotal.add(remaining);
state._stakes[staker] = state._stakes[staker].add(remaining);
return true;
}
function addReward(
uint256 rewardAmount,
uint256 withdrawableAmount,
address rewardTokenAddress,
FestakeRewardState storage state
)
external
returns (bool) {
require(rewardAmount > 0, "Festaking: reward must be positive");
require(withdrawableAmount >= 0, "Festaking: withdrawable amount cannot be negative");
require(withdrawableAmount <= rewardAmount, "Festaking: withdrawable amount must be less than or equal to the reward amount");
address from = msg.sender;
rewardAmount = _payMe(from, rewardAmount, rewardTokenAddress);
state.rewardsTotal = state.rewardsTotal.add(rewardAmount);
state.rewardBalance = state.rewardBalance.add(rewardAmount);
state.earlyWithdrawReward = state.earlyWithdrawReward.add(withdrawableAmount);
return true;
}
function addMarginalReward(
address rewardTokenAddress,
address tokenAddress,
address me,
uint256 stakedBalance,
FestakeRewardState storage state)
external
returns (bool) {
uint256 amount = IERC20(rewardTokenAddress).balanceOf(me).sub(state.rewardsTotal);
if (rewardTokenAddress == tokenAddress) {
amount = amount.sub(stakedBalance);
}
if (amount == 0) {
return true; // No reward to add. Its ok. No need to fail callers.
}
state.rewardsTotal = state.rewardsTotal.add(amount);
state.rewardBalance = state.rewardBalance.add(amount);
return true;
}
function tryWithdraw(
address from,
address tokenAddress,
address rewardTokenAddress,
uint256 amount,
uint256 withdrawStarts,
uint256 withdrawEnds,
uint256 stakingEnds,
FestakeState storage state,
FestakeRewardState storage rewardState
)
public
_after(withdrawStarts)
_positive(amount)
_realAddress(msg.sender)
returns (uint256) {
require(amount <= state._stakes[from], "Festaking: not enough balance");
if (now < withdrawEnds) {
return _withdrawEarly(tokenAddress, rewardTokenAddress, from, amount, withdrawEnds,
stakingEnds, state, rewardState);
} else {
return _withdrawAfterClose(tokenAddress, rewardTokenAddress, from, amount, state, rewardState);
}
}
function withdraw(
address from,
address tokenAddress,
address rewardTokenAddress,
uint256 amount,
uint256 withdrawStarts,
uint256 withdrawEnds,
uint256 stakingEnds,
FestakeState storage state,
FestakeRewardState storage rewardState
)
public
returns (bool) {
uint256 wdAmount = tryWithdraw(from, tokenAddress, rewardTokenAddress, amount, withdrawStarts,
withdrawEnds, stakingEnds, state, rewardState);
state.stakedBalance = state.stakedBalance.sub(wdAmount);
state._stakes[from] = state._stakes[from].sub(wdAmount);
return true;
}
function _withdrawEarly(
address tokenAddress,
address rewardTokenAddress,
address from,
uint256 amount,
uint256 withdrawEnds,
uint256 stakingEnds,
FestakeState storage state,
FestakeRewardState storage rewardState
)
private
_realAddress(from)
returns (uint256) {
// This is the formula to calculate reward:
// r = (earlyWithdrawReward / stakedTotal) * (now - stakingEnds) / (withdrawEnds - stakingEnds)
// w = (1+r) * a
uint256 denom = (withdrawEnds.sub(stakingEnds)).mul(state.stakedTotal);
uint256 reward = (
( (now.sub(stakingEnds)).mul(rewardState.earlyWithdrawReward) ).mul(amount)
).div(denom);
rewardState.rewardBalance = rewardState.rewardBalance.sub(reward);
bool principalPaid = _payDirect(from, amount, tokenAddress);
bool rewardPaid = _payDirect(from, reward, rewardTokenAddress);
require(principalPaid && rewardPaid, "Festaking: error paying");
emit PaidOut(tokenAddress, rewardTokenAddress, from, amount, reward);
return amount;
}
function _withdrawAfterClose(
address tokenAddress,
address rewardTokenAddress,
address from,
uint256 amount,
FestakeState storage state,
FestakeRewardState storage rewardState
) private
_realAddress(from)
returns (uint256) {
uint256 rewBal = rewardState.rewardBalance;
uint256 reward = (rewBal.mul(amount)).div(state.stakedBalance);
rewardState.rewardBalance = rewBal.sub(reward);
bool principalPaid = _payDirect(from, amount, tokenAddress);
bool rewardPaid = _payDirect(from, reward, rewardTokenAddress);
require(principalPaid && rewardPaid, "Festaking: error paying");
emit PaidOut(tokenAddress, rewardTokenAddress, from, amount, reward);
return amount;
}
function _payMe(address payer, uint256 amount, address token)
internal
returns (uint256) {
return _payTo(payer, address(this), amount, token);
}
function _payTo(address allower, address receiver, uint256 amount, address token)
internal
returns (uint256) {
// Request to transfer amount from the contract to receiver.
// contract does not own the funds, so the allower must have added allowance to the contract
// Allower is the original owner.
return SafeAmount.safeTransferFrom(token, allower, receiver, amount);
}
function _payDirect(address to, uint256 amount, address token)
private
returns (bool) {
if (amount == 0) {
return true;
}
IERC20(token).safeTransfer(to, amount);
return true;
}
modifier _realAddress(address addr) {
require(addr != address(0), "Festaking: zero address");
_;
}
modifier _positive(uint256 amount) {
require(amount != 0, "Festaking: negative amount");
_;
}
modifier _after(uint eventTime) {
require(now >= eventTime, "Festaking: bad timing for the request");
_;
}
modifier _before(uint eventTime) {
require(now < eventTime, "Festaking: bad timing for the request");
_;
}
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <0.8.0;
import "./IFestaked.sol";
import "./Festaked.Library.sol";
/**
* A staking contract distributes rewards.
* One can create several TraditionalFestaking over one
* staking and give different rewards for a single
* staking contract.
*/
contract FestakedOptimized is IFestaked {
mapping (address => uint256) internal _stakes;
string private _name;
address public override tokenAddress;
uint public override stakingStarts;
uint public override stakingEnds;
uint public withdrawStarts;
uint public withdrawEnds;
uint public stakingCap;
FestakedLib.FestakeState public stakeState;
uint constant LIB_VERSION = 1001;
/**
* Fixed periods. For an open ended contract use end dates from very distant future.
*/
constructor (
string memory name_,
address tokenAddress_,
uint stakingStarts_,
uint stakingEnds_,
uint withdrawStarts_,
uint withdrawEnds_,
uint256 stakingCap_) public {
require(FestakedLib.VERSION() == LIB_VERSION, "Bad linked library version");
_name = name_;
require(tokenAddress_ != address(0), "Festaking: 0 address");
tokenAddress = tokenAddress_;
require(stakingStarts_ > 0, "Festaking: zero staking start time");
if (stakingStarts_ < now) {
stakingStarts = now;
} else {
stakingStarts = stakingStarts_;
}
require(stakingEnds_ >= stakingStarts, "Festaking: staking end must be after staking starts");
stakingEnds = stakingEnds_;
require(withdrawStarts_ >= stakingEnds, "Festaking: withdrawStarts must be after staking ends");
withdrawStarts = withdrawStarts_;
require(withdrawEnds_ >= withdrawStarts, "Festaking: withdrawEnds must be after withdraw starts");
withdrawEnds = withdrawEnds_;
require(stakingCap_ >= 0, "Festaking: stakingCap cannot be negative");
stakingCap = stakingCap_;
}
function name() external view returns (string memory) {
return _name;
}
function stakedTotal() external override view returns (uint256) {
return stakeState.stakedTotal;
}
function stakedBalance() public override view returns (uint256) {
return stakeState.stakedBalance;
}
function stakeOf(address account) external override view returns (uint256) {
return stakeState._stakes[account];
}
function stakeFor(address staker, uint256 amount)
external
override
returns (bool) {
return _stake(msg.sender, staker, amount);
}
/**
* Requirements:
* - `amount` Amount to be staked
*/
function stake(uint256 amount)
external
override
returns (bool) {
address from = msg.sender;
return _stake(from, from, amount);
}
function _stake(address payer, address staker, uint256 amount) internal virtual returns (bool) {
return FestakedLib.stake(payer, staker, amount,
stakingStarts, stakingEnds, stakingCap, tokenAddress,
stakeState);
}
}
pragma solidity >=0.6.0 <0.8.0;
import "./IFestaked.sol";
import "./FestakedOptimized.sol";
abstract contract RewardAdder is IFestaked {
address public rewardTokenAddress;
FestakedLib.FestakeRewardState public rewardState;
address public rewardSetter; // Not using Ownable to save on deployment gas
function rewardsTotal() external view returns (uint256) {
return rewardState.rewardsTotal;
}
function earlyWithdrawReward() external view returns (uint256) {
return rewardState.earlyWithdrawReward;
}
function rewardBalance() external view returns (uint256) {
return rewardState.rewardBalance;
}
function addReward(uint256 rewardAmount, uint256 withdrawableAmount)
external returns (bool) {
return FestakedLib.addReward(rewardAmount, withdrawableAmount,
rewardTokenAddress, rewardState);
}
}
contract FestakedWithReward is FestakedOptimized, RewardAdder {
constructor (string memory name_,
address tokenAddress_,
address rewardTokenAddress_,
uint stakingStarts_,
uint stakingEnds_,
uint withdrawStarts_,
uint withdrawEnds_,
uint256 stakingCap_) FestakedOptimized (
name_,
tokenAddress_,
stakingStarts_,
stakingEnds_,
withdrawStarts_,
withdrawEnds_,
stakingCap_
) public {
require(rewardTokenAddress_ != address(0), "Festaking: 0 reward address");
rewardTokenAddress = rewardTokenAddress_;
rewardSetter = msg.sender;
}
function addMarginalReward(uint256 withdrawableAmount)
external {
require(msg.sender == rewardSetter, "Festaking: Not allowed");
rewardState.earlyWithdrawReward = withdrawableAmount;
FestakedLib.addMarginalReward(rewardTokenAddress, tokenAddress,
address(this), stakedBalance(), rewardState);
}
function withdraw(uint256 amount) virtual
public
returns (bool) {
return FestakedLib.withdraw(
msg.sender,
tokenAddress,
rewardTokenAddress,
amount,
withdrawStarts,
withdrawEnds,
stakingEnds,
stakeState,
rewardState);
}
}
pragma solidity >=0.6.0 <0.8.0;
/**
* @dev Ferrum Staking interface
*/
interface IFestaked {
event Staked(address indexed token, address indexed staker_, uint256 requestedAmount_, uint256 stakedAmount_);
event PaidOut(address indexed token, address indexed rewardToken, address indexed staker_, uint256 amount_, uint256 reward_);
function stake (uint256 amount) external returns (bool);
function stakeFor (address staker, uint256 amount) external returns (bool);
function stakeOf(address account) external view returns (uint256);
function tokenAddress() external view returns (address);
function stakedTotal() external view returns (uint256);
function stakedBalance() external view returns (uint256);
function stakingStarts() external view returns (uint256);
function stakingEnds() external view returns (uint256);
}
// 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;
/**
* @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);
}
}
}
}