Contract Source Code:
// SPDX-License-Identifier: MIT
pragma solidity 0.7.6;
pragma abicoder v2;
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/SafeERC20.sol";
import "@openzeppelin/contracts/math/SafeMath.sol";
import "./interfaces/IBurnable.sol";
import "./interfaces/IFarmManager.sol";
// Farm distributes the ERC20 rewards based on staked LP to each user.
contract Farm {
using SafeMath for uint256;
using SafeERC20 for IERC20;
// Info of each user.
struct UserInfo {
uint256 amount; // How many LP tokens the user has provided.
uint256 rewardDebt; // Reward debt. See explanation below.
uint256 lastClaimTime;
uint256 withdrawTime;
// We do some fancy math here. Basically, any point in time, the amount of ERC20s
// entitled to a user but is pending to be distributed is:
//
// pending reward = (user.amount * pool.accERC20PerShare) - user.rewardDebt
//
// Whenever a user deposits or withdraws LP tokens to a pool. Here's what happens:
// 1. The pool's `accERC20PerShare` (and `lastRewardBlock`) gets updated.
// 2. User receives the pending reward sent to his/her address.
// 3. User's `amount` gets updated.
// 4. User's `rewardDebt` gets updated.
}
// Info of each pool.
struct PoolInfo {
IERC20 stakingToken; // Address of staking token contract.
uint256 allocPoint; // How many allocation points assigned to this pool. ERC20s to distribute per block.
uint256 lastRewardBlock; // Last block number that ERC20s distribution occurs.
uint256 accERC20PerShare; // Accumulated ERC20s per share, times 1e36.
uint256 supply; // changes with unstakes.
bool isLP; // if the staking token is an LP token.
bool isBurnable; // if the staking token is burnable
}
// Address of the ERC20 Token contract.
IERC20 public erc20;
// The total amount of ERC20 that's paid out as reward.
uint256 public paidOut;
// ERC20 tokens rewarded per block.
uint256 public rewardPerBlock;
// Manager interface to get globals for all farms.
IFarmManager public manager;
// Info of each pool.
PoolInfo[] public poolInfo;
// Info of each user that stakes LP tokens.
mapping (uint256 => mapping (address => UserInfo)) public userInfo;
// Total allocation points. Must be the sum of all allocation points in all pools.
uint256 public totalAllocPoint;
// The block number when farming starts.
uint256 public startBlock;
// Seconds per epoch (1 day)
uint256 public constant SECS_EPOCH = 86400;
// events
event Deposit(address indexed user, uint256 indexed pid, uint256 amount);
event Withdraw(address indexed user, uint256 indexed pid);
event Claim(address indexed user, uint256 indexed pid);
event Unstake(address indexed user, uint256 indexed pid);
event Initialize(IERC20 erc20, uint256 rewardPerBlock, uint256 startBlock, address manager);
constructor(IERC20 _erc20, uint256 _rewardPerBlock, uint256 _startBlock, address _manager) public {
erc20 = _erc20;
rewardPerBlock = _rewardPerBlock;
startBlock = _startBlock;
manager = IFarmManager(_manager);
emit Initialize(_erc20, _rewardPerBlock, _startBlock, _manager);
}
// Fund the farm, increase the end block.
function fund(address _funder, uint256 _amount) external {
require(msg.sender == address(manager), "fund: sender is not manager");
erc20.safeTransferFrom(_funder, address(this), _amount);
}
// Update the given pool's ERC20 allocation point. Can only be called by the manager.
function set(uint256 _pid, uint256 _allocPoint, bool _withUpdate) external {
require(msg.sender == address(manager), "set: sender is not manager");
if (_withUpdate) {
massUpdatePools();
}
totalAllocPoint = totalAllocPoint.sub(poolInfo[_pid].allocPoint).add(_allocPoint);
poolInfo[_pid].allocPoint = _allocPoint;
}
// Add a new staking token to the pool. Can only be called by the manager.
function add(uint256 _allocPoint, IERC20 _stakingToken, bool _isLP, bool _isBurnable, bool _withUpdate) external {
require(msg.sender == address(manager), "fund: sender is not manager");
if (_withUpdate) {
massUpdatePools();
}
uint256 lastRewardBlock = block.number > startBlock ? block.number : startBlock;
totalAllocPoint = totalAllocPoint.add(_allocPoint);
poolInfo.push(PoolInfo({
stakingToken: _stakingToken,
supply: 0,
allocPoint: _allocPoint,
lastRewardBlock: lastRewardBlock,
accERC20PerShare: 0,
isLP: _isLP,
isBurnable: _isBurnable
}));
}
// Update reward variables for all pools. Be careful of gas spending!
function massUpdatePools() public {
uint256 length = poolInfo.length;
for (uint256 pid = 0; pid < length; ++pid) {
updatePool(pid);
}
}
// Update reward variables of the given pool to be up-to-date.
function updatePool(uint256 _pid) public {
PoolInfo storage pool = poolInfo[_pid];
uint256 lastBlock = block.number;
if (lastBlock <= pool.lastRewardBlock) {
return;
}
if (pool.supply == 0) {
pool.lastRewardBlock = lastBlock;
return;
}
uint256 nrOfBlocks = lastBlock.sub(pool.lastRewardBlock);
uint256 erc20Reward = nrOfBlocks.mul(rewardPerBlock).mul(pool.allocPoint).div(totalAllocPoint);
pool.accERC20PerShare = pool.accERC20PerShare.add(erc20Reward.mul(1e36).div(pool.supply));
pool.lastRewardBlock = block.number;
}
// move LP tokens from one farm to another. only callable by Manager.
function move(uint256 _pid, address _mover) external {
require(msg.sender == address(manager), "move: sender is not manager");
PoolInfo storage pool = poolInfo[_pid];
UserInfo storage user = userInfo[_pid][_mover];
updatePool(_pid);
uint256 pendingAmount = user.amount.mul(pool.accERC20PerShare).div(1e36).sub(user.rewardDebt);
erc20Transfer(_mover, pendingAmount);
pool.supply = pool.supply.sub(user.amount);
pool.stakingToken.safeTransfer(address(manager), user.amount);
user.amount = 0;
user.rewardDebt = user.amount.mul(pool.accERC20PerShare).div(1e36);
emit Withdraw(msg.sender, _pid);
}
// Deposit LP tokens to Farm for ERC20 allocation.
// can come from manager or user address directly.
// In the case the call is coming from the manager, msg.sender is the manager.
function deposit(uint256 _pid, address _depositor, uint256 _amount) external {
require(manager.getPaused()==false, "deposit: farm paused");
PoolInfo storage pool = poolInfo[_pid];
UserInfo storage user = userInfo[_pid][_depositor];
require(user.withdrawTime == 0, "deposit: user is unstaking");
// If we're not called by the farm manager, then we must ensure that the caller is the depositor.
// This way we avoid the case where someone else commits the deposit, after the depositor
// granted allowance to the farm.
if(msg.sender != address(manager)) {
require(msg.sender == _depositor, "deposit: the caller must be the depositor");
}
updatePool(_pid);
if (user.amount > 0) {
uint256 pendingAmount = user.amount.mul(pool.accERC20PerShare).div(1e36).sub(user.rewardDebt);
erc20Transfer(_depositor, pendingAmount);
}
// We tranfer from the msg.sender, because in the case when we're called by the farm manager (change pool scenario)
// it's the FM who owns the tokens, not the depositor (who in this case is the user who changes pools).
pool.stakingToken.safeTransferFrom(msg.sender, address(this), _amount);
pool.supply = pool.supply.add(_amount);
user.amount = user.amount.add(_amount);
user.rewardDebt = user.amount.mul(pool.accERC20PerShare).div(1e36);
emit Deposit(_depositor, _pid, _amount);
}
// Distribute rewards and start unstake period.
function withdraw(uint256 _pid) external {
require(manager.getPaused()==false, "withdraw: farm paused");
PoolInfo storage pool = poolInfo[_pid];
UserInfo storage user = userInfo[_pid][msg.sender];
require(user.amount > 0, "withdraw: amount must be greater than 0");
require(user.withdrawTime == 0, "withdraw: user is unstaking");
updatePool(_pid);
// transfer any rewards due
uint256 pendingAmount = user.amount.mul(pool.accERC20PerShare).div(1e36).sub(user.rewardDebt);
erc20Transfer(msg.sender, pendingAmount);
pool.supply = pool.supply.sub(user.amount);
user.rewardDebt = 0;
user.withdrawTime = block.timestamp;
emit Withdraw(msg.sender, _pid);
}
// unstake LP tokens from Farm. if done within "unstakeEpochs" days, apply burn.
function unstake(uint256 _pid) external {
require(manager.getPaused()==false, "unstake: farm paused");
PoolInfo storage pool = poolInfo[_pid];
UserInfo storage user = userInfo[_pid][msg.sender];
require(user.withdrawTime > 0, "unstake: user is not unstaking");
updatePool(_pid);
//apply burn fee if unstaking before unstake epochs.
uint256 unstakeEpochs = manager.getUnstakeEpochs();
uint256 burnRate = manager.getBurnRate();
address redistributor = manager.getRedistributor();
if((user.withdrawTime.add(SECS_EPOCH.mul(unstakeEpochs)) > block.timestamp) && burnRate > 0){
uint penalty = user.amount.mul(burnRate).div(1000);
user.amount = user.amount.sub(penalty);
// if the staking address is an LP, send 50% of penalty to redistributor, and 50% to lp lock address.
if(pool.isLP){
uint256 redistributorPenalty = penalty.div(2);
pool.stakingToken.safeTransfer(redistributor, redistributorPenalty);
pool.stakingToken.safeTransfer(manager.getLpLock(), penalty.sub(redistributorPenalty));
}else {
// for normal ERC20 tokens, a portion (50% by default) of the penalty is sent to the redistributor address
uint256 burnRatio = manager.getBurnRatio();
uint256 burnAmount = penalty.mul(burnRatio).div(1000);
pool.stakingToken.safeTransfer(redistributor, penalty.sub(burnAmount));
if(pool.isBurnable){
//if the staking token is burnable, the second portion (50% by default) is burned
IBurnable(address(pool.stakingToken)).burn(burnAmount);
}else{
//if the staking token is not burnable, the second portion (50% by default) is sent to burn valley
pool.stakingToken.safeTransfer(manager.getBurnValley(), burnAmount);
}
}
}
uint userAmount = user.amount;
// allows user to stake again.
user.withdrawTime = 0;
user.amount = 0;
pool.stakingToken.safeTransfer(address(msg.sender), userAmount);
emit Unstake(msg.sender, _pid);
}
// claim LP tokens from Farm.
function claim(uint256 _pid) external {
require(manager.getPaused() == false, "claim: farm paused");
PoolInfo storage pool = poolInfo[_pid];
UserInfo storage user = userInfo[_pid][msg.sender];
require(user.amount > 0, "claim: amount is equal to 0");
require(user.withdrawTime == 0, "claim: user is unstaking");
updatePool(_pid);
uint256 pendingAmount = user.amount.mul(pool.accERC20PerShare).div(1e36).sub(user.rewardDebt);
erc20Transfer(msg.sender, pendingAmount);
user.rewardDebt = user.amount.mul(pool.accERC20PerShare).div(1e36);
user.lastClaimTime = block.timestamp;
emit Claim(msg.sender, _pid);
}
// Transfer ERC20 and update the required ERC20 to payout all rewards
function erc20Transfer(address _to, uint256 _amount) internal {
erc20.transfer(_to, _amount);
paidOut += _amount;
}
// emergency withdraw rewards. only owner. EMERGENCY ONLY.
function emergencyWithdrawRewards(address _receiver) external {
require(msg.sender == address(manager), "emergencyWithdrawRewards: sender is not manager");
uint balance = erc20.balanceOf(address(this));
erc20.safeTransfer(_receiver, balance);
}
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <0.8.0;
/**
* @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 <0.8.0;
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 >=0.6.0 <0.8.0;
/**
* @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, with an overflow flag.
*
* _Available since v3.4._
*/
function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
uint256 c = a + b;
if (c < a) return (false, 0);
return (true, c);
}
/**
* @dev Returns the substraction of two unsigned integers, with an overflow flag.
*
* _Available since v3.4._
*/
function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
if (b > a) return (false, 0);
return (true, a - b);
}
/**
* @dev Returns the multiplication of two unsigned integers, with an overflow flag.
*
* _Available since v3.4._
*/
function tryMul(uint256 a, uint256 b) internal pure returns (bool, 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 (true, 0);
uint256 c = a * b;
if (c / a != b) return (false, 0);
return (true, c);
}
/**
* @dev Returns the division of two unsigned integers, with a division by zero flag.
*
* _Available since v3.4._
*/
function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
if (b == 0) return (false, 0);
return (true, a / b);
}
/**
* @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
*
* _Available since v3.4._
*/
function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
if (b == 0) return (false, 0);
return (true, a % b);
}
/**
* @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) {
require(b <= a, "SafeMath: subtraction overflow");
return a - b;
}
/**
* @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) {
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, reverting 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) {
require(b > 0, "SafeMath: division by zero");
return a / b;
}
/**
* @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
* reverting 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) {
require(b > 0, "SafeMath: modulo by zero");
return a % b;
}
/**
* @dev Returns the subtraction of two unsigned integers, reverting with custom message on
* overflow (when the result is negative).
*
* CAUTION: This function is deprecated because it requires allocating memory for the error
* message unnecessarily. For custom revert reasons use {trySub}.
*
* 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);
return a - b;
}
/**
* @dev Returns the integer division of two unsigned integers, reverting with custom message on
* division by zero. The result is rounded towards zero.
*
* CAUTION: This function is deprecated because it requires allocating memory for the error
* message unnecessarily. For custom revert reasons use {tryDiv}.
*
* 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);
return a / b;
}
/**
* @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
* reverting with custom message when dividing by zero.
*
* CAUTION: This function is deprecated because it requires allocating memory for the error
* message unnecessarily. For custom revert reasons use {tryMod}.
*
* 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: Unlicense
pragma solidity 0.7.6;
interface IBurnable {
function burn(uint256 amount) external;
function balanceOf(address account) external view returns (uint256);
}
// SPDX-License-Identifier: MIT
pragma solidity 0.7.6;
interface IFarmManager {
function getPaused() external view returns(bool);
function getBurnRate() external view returns(uint256);
function getBurnRatio() external view returns(uint256);
function getUnstakeEpochs() external view returns(uint256);
function getRedistributor() external view returns(address);
function getLpLock() external view returns(address);
function getBurnValley() external view returns(address);
}
// SPDX-License-Identifier: MIT
pragma solidity >=0.6.2 <0.8.0;
/**
* @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 on 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");
require(isContract(target), "Address: call to non-contract");
// solhint-disable-next-line avoid-low-level-calls
(bool success, bytes memory returndata) = target.call{ value: value }(data);
return _verifyCallResult(success, returndata, errorMessage);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but performing a static call.
*
* _Available since v3.3._
*/
function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
return functionStaticCall(target, data, "Address: low-level static call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
* but performing a static call.
*
* _Available since v3.3._
*/
function functionStaticCall(address target, bytes memory data, string memory errorMessage) internal view returns (bytes memory) {
require(isContract(target), "Address: static call to non-contract");
// solhint-disable-next-line avoid-low-level-calls
(bool success, bytes memory returndata) = target.staticcall(data);
return _verifyCallResult(success, returndata, errorMessage);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but performing a delegate call.
*
* _Available since v3.4._
*/
function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
return functionDelegateCall(target, data, "Address: low-level delegate call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
* but performing a delegate call.
*
* _Available since v3.4._
*/
function functionDelegateCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
require(isContract(target), "Address: delegate call to non-contract");
// solhint-disable-next-line avoid-low-level-calls
(bool success, bytes memory returndata) = target.delegatecall(data);
return _verifyCallResult(success, returndata, errorMessage);
}
function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private pure returns(bytes memory) {
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);
}
}
}
}