Exhibit 4.2
// SPDX-License-Identifier: GPL-3.0
pragma solidity 0.8.20;
import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "@openzeppelin/contracts/token/ERC20/extensions/ERC20Burnable.sol";
import "@openzeppelin/contracts/token/ERC20/extensions/ERC20Permit.sol";
import "@openzeppelin/contracts/access/Ownable2Step.sol";
import "./interfaces/IENADefinitions.sol";
/**
* @title ENA
* @notice Governance token for the Ethena protocol
*/
contract ENA is Ownable2Step, ERC20Burnable, ERC20Permit, IENADefinitions {
/// @notice Maximum inflation rate per year (percentage) expressed as an integer
uint8 public constant MAX_INFLATION = 10;
/// @notice The maximum frequency of inflationary mint invocations
uint32 public constant MINT_WAIT_PERIOD = 365 days;
/// @notice The last time the mint function was called
uint40 public lastMintTimestamp;
constructor(address _initialOwner, address _treasury, address _foundation) ERC20("ENA", "ENA") ERC20Permit("ENA") {
// first mint not allowed until 1 year after deployment
lastMintTimestamp = uint40(block.timestamp);
if (_initialOwner == address(0) || _treasury == address(0) || _foundation == address(0)) revert ZeroAddressException();
_transferOwnership(_initialOwner);
// initial supply of 15 billion tokens
_mint(_treasury, 3_750_000_000 * 10 ** 18);
_mint(_foundation, 11_250_000_000 * 10 ** 18);
}
/**
* @notice Mints new ENA tokens
* @param to The address to mint tokens to
* @param amount The amount of tokens to mint
* @dev Only callable by the owner once per year and amount must be less than max inflation rate
*/
function mint(address to, uint256 amount) external onlyOwner {
if (block.timestamp - lastMintTimestamp < MINT_WAIT_PERIOD) revert MintWaitPeriodInProgress();
uint256 _maxInflationAmount = totalSupply() * MAX_INFLATION / 100;
if (amount > _maxInflationAmount) revert MaxInflationExceeded();
lastMintTimestamp = uint40(block.timestamp);
_mint(to, amount);
emit Mint(to, amount);
}
/// @notice Prevents the owner from renouncing ownership
function renounceOwnership() public view override onlyOwner {
revert CantRenounceOwnership();
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (token/ERC20/ERC20.sol)
pragma solidity ^0.8.0;
import "./IERC20.sol";
import "./extensions/IERC20Metadata.sol";
import "../../utils/Context.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.openzeppelin.com/t/how-to-implement-erc20-supply-mechanisms/226[How
* to implement supply mechanisms].
*
* The default value of {decimals} is 18. To change this, you should override
* this function so it returns a different value.
*
* We have followed general OpenZeppelin Contracts guidelines: functions revert
* instead 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, IERC20Metadata {
mapping(address => uint256) private _balances;
mapping(address => mapping(address => uint256)) private _allowances;
uint256 private _totalSupply;
string private _name;
string private _symbol;
/**
* @dev Sets the values for {name} and {symbol}.
*
* All two of these values are immutable: they can only be set once during
* construction.
*/
constructor(string memory name_, string memory symbol_) {
_name = name_;
_symbol = symbol_;
}
/**
* @dev Returns the name of the token.
*/
function name() public view virtual override returns (string memory) {
return _name;
}
/**
* @dev Returns the symbol of the token, usually a shorter version of the
* name.
*/
function symbol() public view virtual override 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 default value returned by this function, unless
* it's overridden.
*
* 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 virtual override returns (uint8) {
return 18;
}
/**
* @dev See {IERC20-totalSupply}.
*/
function totalSupply() public view virtual override returns (uint256) {
return _totalSupply;
}
/**
* @dev See {IERC20-balanceOf}.
*/
function balanceOf(address account) public view virtual override returns (uint256) {
return _balances[account];
}
/**
* @dev See {IERC20-transfer}.
*
* Requirements:
*
* - `to` cannot be the zero address.
* - the caller must have a balance of at least `amount`.
*/
function transfer(address to, uint256 amount) public virtual override returns (bool) {
address owner = _msgSender();
_transfer(owner, to, 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}.
*
* NOTE: If `amount` is the maximum `uint256`, the allowance is not updated on
* `transferFrom`. This is semantically equivalent to an infinite approval.
*
* Requirements:
*
* - `spender` cannot be the zero address.
*/
function approve(address spender, uint256 amount) public virtual override returns (bool) {
address owner = _msgSender();
_approve(owner, 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}.
*
* NOTE: Does not update the allowance if the current allowance
* is the maximum `uint256`.
*
* Requirements:
*
* - `from` and `to` cannot be the zero address.
* - `from` must have a balance of at least `amount`.
* - the caller must have allowance for ``from``'s tokens of at least
* `amount`.
*/
function transferFrom(address from, address to, uint256 amount) public virtual override returns (bool) {
address spender = _msgSender();
_spendAllowance(from, spender, amount);
_transfer(from, to, amount);
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) {
address owner = _msgSender();
_approve(owner, spender, allowance(owner, spender) + 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) {
address owner = _msgSender();
uint256 currentAllowance = allowance(owner, spender);
require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
unchecked {
_approve(owner, spender, currentAllowance - subtractedValue);
}
return true;
}
/**
* @dev Moves `amount` of tokens from `from` to `to`.
*
* This 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:
*
* - `from` cannot be the zero address.
* - `to` cannot be the zero address.
* - `from` must have a balance of at least `amount`.
*/
function _transfer(address from, address to, uint256 amount) internal virtual {
require(from != address(0), "ERC20: transfer from the zero address");
require(to != address(0), "ERC20: transfer to the zero address");
_beforeTokenTransfer(from, to, amount);
uint256 fromBalance = _balances[from];
require(fromBalance >= amount, "ERC20: transfer amount exceeds balance");
unchecked {
_balances[from] = fromBalance - amount;
// Overflow not possible: the sum of all balances is capped by totalSupply, and the sum is preserved by
// decrementing then incrementing.
_balances[to] += amount;
}
emit Transfer(from, to, amount);
_afterTokenTransfer(from, to, 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:
*
* - `account` 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 += amount;
unchecked {
// Overflow not possible: balance + amount is at most totalSupply + amount, which is checked above.
_balances[account] += amount;
}
emit Transfer(address(0), account, amount);
_afterTokenTransfer(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);
uint256 accountBalance = _balances[account];
require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
unchecked {
_balances[account] = accountBalance - amount;
// Overflow not possible: amount <= accountBalance <= totalSupply.
_totalSupply -= amount;
}
emit Transfer(account, address(0), amount);
_afterTokenTransfer(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 Updates `owner` s allowance for `spender` based on spent `amount`.
*
* Does not update the allowance amount in case of infinite allowance.
* Revert if not enough allowance is available.
*
* Might emit an {Approval} event.
*/
function _spendAllowance(address owner, address spender, uint256 amount) internal virtual {
uint256 currentAllowance = allowance(owner, spender);
if (currentAllowance != type(uint256).max) {
require(currentAllowance >= amount, "ERC20: insufficient allowance");
unchecked {
_approve(owner, spender, currentAllowance - amount);
}
}
}
/**
* @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 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 {}
/**
* @dev Hook that is called after any transfer of tokens. This includes
* minting and burning.
*
* Calling conditions:
*
* - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
* has been transferred to `to`.
* - when `from` is zero, `amount` tokens have been minted for `to`.
* - when `to` is zero, `amount` of ``from``'s tokens have been 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 _afterTokenTransfer(address from, address to, uint256 amount) internal virtual {}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (token/ERC20/extensions/ERC20Burnable.sol)
pragma solidity ^0.8.0;
import "../ERC20.sol";
import "../../../utils/Context.sol";
/**
* @dev Extension of {ERC20} that allows token holders to destroy both their own
* tokens and those that they have an allowance for, in a way that can be
* recognized off-chain (via event analysis).
*/
abstract contract ERC20Burnable is Context, ERC20 {
/**
* @dev Destroys `amount` tokens from the caller.
*
* See {ERC20-_burn}.
*/
function burn(uint256 amount) public virtual {
_burn(_msgSender(), amount);
}
/**
* @dev Destroys `amount` tokens from `account`, deducting from the caller's
* allowance.
*
* See {ERC20-_burn} and {ERC20-allowance}.
*
* Requirements:
*
* - the caller must have allowance for ``accounts``'s tokens of at least
* `amount`.
*/
function burnFrom(address account, uint256 amount) public virtual {
_spendAllowance(account, _msgSender(), amount);
_burn(account, amount);
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.4) (token/ERC20/extensions/ERC20Permit.sol)
pragma solidity ^0.8.0;
import "./IERC20Permit.sol";
import "../ERC20.sol";
import "../../../utils/cryptography/ECDSA.sol";
import "../../../utils/cryptography/EIP712.sol";
import "../../../utils/Counters.sol";
/**
* @dev Implementation of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
* https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
*
* Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
* presenting a message signed by the account. By not relying on `{IERC20-approve}`, the token holder account doesn't
* need to send a transaction, and thus is not required to hold Ether at all.
*
* _Available since v3.4._
*/
abstract contract ERC20Permit is ERC20, IERC20Permit, EIP712 {
using Counters for Counters.Counter;
mapping(address => Counters.Counter) private _nonces;
// solhint-disable-next-line var-name-mixedcase
bytes32 private constant _PERMIT_TYPEHASH =
keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");
/**
* @dev In previous versions `_PERMIT_TYPEHASH` was declared as `immutable`.
* However, to ensure consistency with the upgradeable transpiler, we will continue
* to reserve a slot.
* @custom:oz-renamed-from _PERMIT_TYPEHASH
*/
// solhint-disable-next-line var-name-mixedcase
bytes32 private _PERMIT_TYPEHASH_DEPRECATED_SLOT;
/**
* @dev Initializes the {EIP712} domain separator using the `name` parameter, and setting `version` to `"1"`.
*
* It's a good idea to use the same `name` that is defined as the ERC20 token name.
*/
constructor(string memory name) EIP712(name, "1") {}
/**
* @inheritdoc IERC20Permit
*/
function permit(
address owner,
address spender,
uint256 value,
uint256 deadline,
uint8 v,
bytes32 r,
bytes32 s
) public virtual override {
require(block.timestamp <= deadline, "ERC20Permit: expired deadline");
bytes32 structHash = keccak256(abi.encode(_PERMIT_TYPEHASH, owner, spender, value, _useNonce(owner), deadline));
bytes32 hash = _hashTypedDataV4(structHash);
address signer = ECDSA.recover(hash, v, r, s);
require(signer == owner, "ERC20Permit: invalid signature");
_approve(owner, spender, value);
}
/**
* @inheritdoc IERC20Permit
*/
function nonces(address owner) public view virtual override returns (uint256) {
return _nonces[owner].current();
}
/**
* @inheritdoc IERC20Permit
*/
// solhint-disable-next-line func-name-mixedcase
function DOMAIN_SEPARATOR() external view override returns (bytes32) {
return _domainSeparatorV4();
}
/**
* @dev "Consume a nonce": return the current value and increment.
*
* _Available since v4.1._
*/
function _useNonce(address owner) internal virtual returns (uint256 current) {
Counters.Counter storage nonce = _nonces[owner];
current = nonce.current();
nonce.increment();
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (access/Ownable2Step.sol)
pragma solidity ^0.8.0;
import "./Ownable.sol";
/**
* @dev Contract module which provides access control mechanism, where
* there is an account (an owner) that can be granted exclusive access to
* specific functions.
*
* By default, the owner account will be the one that deploys the contract. This
* can later be changed with {transferOwnership} and {acceptOwnership}.
*
* This module is used through inheritance. It will make available all functions
* from parent (Ownable).
*/
abstract contract Ownable2Step is Ownable {
address private _pendingOwner;
event OwnershipTransferStarted(address indexed previousOwner, address indexed newOwner);
/**
* @dev Returns the address of the pending owner.
*/
function pendingOwner() public view virtual returns (address) {
return _pendingOwner;
}
/**
* @dev Starts the ownership transfer of the contract to a new account. Replaces the pending transfer if there is one.
* Can only be called by the current owner.
*/
function transferOwnership(address newOwner) public virtual override onlyOwner {
_pendingOwner = newOwner;
emit OwnershipTransferStarted(owner(), newOwner);
}
/**
* @dev Transfers ownership of the contract to a new account (`newOwner`) and deletes any pending owner.
* Internal function without access restriction.
*/
function _transferOwnership(address newOwner) internal virtual override {
delete _pendingOwner;
super._transferOwnership(newOwner);
}
/**
* @dev The new owner accepts the ownership transfer.
*/
function acceptOwnership() public virtual {
address sender = _msgSender();
require(pendingOwner() == sender, "Ownable2Step: caller is not the new owner");
_transferOwnership(sender);
}
}
// SPDX-License-Identifier: GPL-3.0
pragma solidity 0.8.20;
interface IENADefinitions {
/// @notice Event emitted when a new ENA token is minted (inflation) by the owner
event Mint(address indexed to, uint256 amount);
/// @notice This error is returned if the zero address is used
error ZeroAddressException();
/// @notice This error is returned if mint is called within 1 year of last mint
error MintWaitPeriodInProgress();
/// @notice This error is returned if the owner tries to renounce ownership
error CantRenounceOwnership();
/// @notice This error is returned if the max inflation rate is exceeded on mint
error MaxInflationExceeded();
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (token/ERC20/IERC20.sol)
pragma solidity ^0.8.0;
/**
* @dev Interface of the ERC20 standard as defined in the EIP.
*/
interface IERC20 {
/**
* @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);
/**
* @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 `to`.
*
* Returns a boolean value indicating whether the operation succeeded.
*
* Emits a {Transfer} event.
*/
function transfer(address to, 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 `from` to `to` 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 from, address to, uint256 amount) external returns (bool);
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/IERC20Metadata.sol)
pragma solidity ^0.8.0;
import "../IERC20.sol";
/**
* @dev Interface for the optional metadata functions from the ERC20 standard.
*
* _Available since v4.1._
*/
interface IERC20Metadata is IERC20 {
/**
* @dev Returns the name of the token.
*/
function name() external view returns (string memory);
/**
* @dev Returns the symbol of the token.
*/
function symbol() external view returns (string memory);
/**
* @dev Returns the decimals places of the token.
*/
function decimals() external view returns (uint8);
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.4) (utils/Context.sol)
pragma solidity ^0.8.0;
/**
* @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 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) {
return msg.sender;
}
function _msgData() internal view virtual returns (bytes calldata) {
return msg.data;
}
function _contextSuffixLength() internal view virtual returns (uint256) {
return 0;
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.4) (token/ERC20/extensions/IERC20Permit.sol)
pragma solidity ^0.8.0;
/**
* @dev Interface of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
* https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
*
* Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
* presenting a message signed by the account. By not relying on {IERC20-approve}, the token holder account doesn't
* need to send a transaction, and thus is not required to hold Ether at all.
*
* ==== Security Considerations
*
* There are two important considerations concerning the use of `permit`. The first is that a valid permit signature
* expresses an allowance, and it should not be assumed to convey additional meaning. In particular, it should not be
* considered as an intention to spend the allowance in any specific way. The second is that because permits have
* built-in replay protection and can be submitted by anyone, they can be frontrun. A protocol that uses permits should
* take this into consideration and allow a `permit` call to fail. Combining these two aspects, a pattern that may be
* generally recommended is:
*
* ```solidity
* function doThingWithPermit(..., uint256 value, uint256 deadline, uint8 v, bytes32 r, bytes32 s) public {
* try token.permit(msg.sender, address(this), value, deadline, v, r, s) {} catch {}
* doThing(..., value);
* }
*
* function doThing(..., uint256 value) public {
* token.safeTransferFrom(msg.sender, address(this), value);
* ...
* }
* ```
*
* Observe that: 1) `msg.sender` is used as the owner, leaving no ambiguity as to the signer intent, and 2) the use of
* `try/catch` allows the permit to fail and makes the code tolerant to frontrunning. (See also
* {SafeERC20-safeTransferFrom}).
*
* Additionally, note that smart contract wallets (such as Argent or Safe) are not able to produce permit signatures, so
* contracts should have entry points that don't rely on permit.
*/
interface IERC20Permit {
/**
* @dev Sets `value` as the allowance of `spender` over ``owner``'s tokens,
* given ``owner``'s signed approval.
*
* IMPORTANT: The same issues {IERC20-approve} has related to transaction
* ordering also apply here.
*
* Emits an {Approval} event.
*
* Requirements:
*
* - `spender` cannot be the zero address.
* - `deadline` must be a timestamp in the future.
* - `v`, `r` and `s` must be a valid `secp256k1` signature from `owner`
* over the EIP712-formatted function arguments.
* - the signature must use ``owner``'s current nonce (see {nonces}).
*
* For more information on the signature format, see the
* https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP
* section].
*
* CAUTION: See Security Considerations above.
*/
function permit(
address owner,
address spender,
uint256 value,
uint256 deadline,
uint8 v,
bytes32 r,
bytes32 s
) external;
/**
* @dev Returns the current nonce for `owner`. This value must be
* included whenever a signature is generated for {permit}.
*
* Every successful call to {permit} increases ``owner``'s nonce by one. This
* prevents a signature from being used multiple times.
*/
function nonces(address owner) external view returns (uint256);
/**
* @dev Returns the domain separator used in the encoding of the signature for {permit}, as defined by {EIP712}.
*/
// solhint-disable-next-line func-name-mixedcase
function DOMAIN_SEPARATOR() external view returns (bytes32);
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (utils/cryptography/ECDSA.sol)
pragma solidity ^0.8.0;
import "../Strings.sol";
/**
* @dev Elliptic Curve Digital Signature Algorithm (ECDSA) operations.
*
* These functions can be used to verify that a message was signed by the holder
* of the private keys of a given address.
*/
library ECDSA {
enum RecoverError {
NoError,
InvalidSignature,
InvalidSignatureLength,
InvalidSignatureS,
InvalidSignatureV // Deprecated in v4.8
}
function _throwError(RecoverError error) private pure {
if (error == RecoverError.NoError) {
return; // no error: do nothing
} else if (error == RecoverError.InvalidSignature) {
revert("ECDSA: invalid signature");
} else if (error == RecoverError.InvalidSignatureLength) {
revert("ECDSA: invalid signature length");
} else if (error == RecoverError.InvalidSignatureS) {
revert("ECDSA: invalid signature 's' value");
}
}
/**
* @dev Returns the address that signed a hashed message (`hash`) with
* `signature` or error string. This address can then be used for verification purposes.
*
* The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
* this function rejects them by requiring the `s` value to be in the lower
* half order, and the `v` value to be either 27 or 28.
*
* IMPORTANT: `hash` _must_ be the result of a hash operation for the
* verification to be secure: it is possible to craft signatures that
* recover to arbitrary addresses for non-hashed data. A safe way to ensure
* this is by receiving a hash of the original message (which may otherwise
* be too long), and then calling {toEthSignedMessageHash} on it.
*
* Documentation for signature generation:
* - with https://web3js.readthedocs.io/en/v1.3.4/web3-eth-accounts.html#sign[Web3.js]
* - with https://docs.ethers.io/v5/api/signer/#Signer-signMessage[ethers]
*
* _Available since v4.3._
*/
function tryRecover(bytes32 hash, bytes memory signature) internal pure returns (address, RecoverError) {
if (signature.length == 65) {
bytes32 r;
bytes32 s;
uint8 v;
// ecrecover takes the signature parameters, and the only way to get them
// currently is to use assembly.
/// @solidity memory-safe-assembly
assembly {
r := mload(add(signature, 0x20))
s := mload(add(signature, 0x40))
v := byte(0, mload(add(signature, 0x60)))
}
return tryRecover(hash, v, r, s);
} else {
return (address(0), RecoverError.InvalidSignatureLength);
}
}
/**
* @dev Returns the address that signed a hashed message (`hash`) with
* `signature`. This address can then be used for verification purposes.
*
* The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
* this function rejects them by requiring the `s` value to be in the lower
* half order, and the `v` value to be either 27 or 28.
*
* IMPORTANT: `hash` _must_ be the result of a hash operation for the
* verification to be secure: it is possible to craft signatures that
* recover to arbitrary addresses for non-hashed data. A safe way to ensure
* this is by receiving a hash of the original message (which may otherwise
* be too long), and then calling {toEthSignedMessageHash} on it.
*/
function recover(bytes32 hash, bytes memory signature) internal pure returns (address) {
(address recovered, RecoverError error) = tryRecover(hash, signature);
_throwError(error);
return recovered;
}
/**
* @dev Overload of {ECDSA-tryRecover} that receives the `r` and `vs` short-signature fields separately.
*
* See https://eips.ethereum.org/EIPS/eip-2098[EIP-2098 short signatures]
*
* _Available since v4.3._
*/
function tryRecover(bytes32 hash, bytes32 r, bytes32 vs) internal pure returns (address, RecoverError) {
bytes32 s = vs & bytes32(0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff);
uint8 v = uint8((uint256(vs) >> 255) + 27);
return tryRecover(hash, v, r, s);
}
/**
* @dev Overload of {ECDSA-recover} that receives the `r and `vs` short-signature fields separately.
*
* _Available since v4.2._
*/
function recover(bytes32 hash, bytes32 r, bytes32 vs) internal pure returns (address) {
(address recovered, RecoverError error) = tryRecover(hash, r, vs);
_throwError(error);
return recovered;
}
/**
* @dev Overload of {ECDSA-tryRecover} that receives the `v`,
* `r` and `s` signature fields separately.
*
* _Available since v4.3._
*/
function tryRecover(bytes32 hash, uint8 v, bytes32 r, bytes32 s) internal pure returns (address, RecoverError) {
// EIP-2 still allows signature malleability for ecrecover(). Remove this possibility and make the signature
// unique. Appendix F in the Ethereum Yellow paper (https://ethereum.github.io/yellowpaper/paper.pdf), defines
// the valid range for s in (301): 0 < s < secp256k1n ÷ 2 + 1, and for v in (302): v ∈ {27, 28}. Most
// signatures from current libraries generate a unique signature with an s-value in the lower half order.
//
// If your library generates malleable signatures, such as s-values in the upper range, calculate a new s-value
// with 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 - s1 and flip v from 27 to 28 or
// vice versa. If your library also generates signatures with 0/1 for v instead 27/28, add 27 to v to accept
// these malleable signatures as well.
if (uint256(s) > 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0) {
return (address(0), RecoverError.InvalidSignatureS);
}
// If the signature is valid (and not malleable), return the signer address
address signer = ecrecover(hash, v, r, s);
if (signer == address(0)) {
return (address(0), RecoverError.InvalidSignature);
}
return (signer, RecoverError.NoError);
}
/**
* @dev Overload of {ECDSA-recover} that receives the `v`,
* `r` and `s` signature fields separately.
*/
function recover(bytes32 hash, uint8 v, bytes32 r, bytes32 s) internal pure returns (address) {
(address recovered, RecoverError error) = tryRecover(hash, v, r, s);
_throwError(error);
return recovered;
}
/**
* @dev Returns an Ethereum Signed Message, created from a `hash`. This
* produces hash corresponding to the one signed with the
* https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
* JSON-RPC method as part of EIP-191.
*
* See {recover}.
*/
function toEthSignedMessageHash(bytes32 hash) internal pure returns (bytes32 message) {
// 32 is the length in bytes of hash,
// enforced by the type signature above
/// @solidity memory-safe-assembly
assembly {
mstore(0x00, "\x19Ethereum Signed Message:\n32")
mstore(0x1c, hash)
message := keccak256(0x00, 0x3c)
}
}
/**
* @dev Returns an Ethereum Signed Message, created from `s`. This
* produces hash corresponding to the one signed with the
* https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
* JSON-RPC method as part of EIP-191.
*
* See {recover}.
*/
function toEthSignedMessageHash(bytes memory s) internal pure returns (bytes32) {
return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n", Strings.toString(s.length), s));
}
/**
* @dev Returns an Ethereum Signed Typed Data, created from a
* `domainSeparator` and a `structHash`. This produces hash corresponding
* to the one signed with the
* https://eips.ethereum.org/EIPS/eip-712[`eth_signTypedData`]
* JSON-RPC method as part of EIP-712.
*
* See {recover}.
*/
function toTypedDataHash(bytes32 domainSeparator, bytes32 structHash) internal pure returns (bytes32 data) {
/// @solidity memory-safe-assembly
assembly {
let ptr := mload(0x40)
mstore(ptr, "\x19\x01")
mstore(add(ptr, 0x02), domainSeparator)
mstore(add(ptr, 0x22), structHash)
data := keccak256(ptr, 0x42)
}
}
/**
* @dev Returns an Ethereum Signed Data with intended validator, created from a
* `validator` and `data` according to the version 0 of EIP-191.
*
* See {recover}.
*/
function toDataWithIntendedValidatorHash(address validator, bytes memory data) internal pure returns (bytes32) {
return keccak256(abi.encodePacked("\x19\x00", validator, data));
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (utils/cryptography/EIP712.sol)
pragma solidity ^0.8.8;
import "./ECDSA.sol";
import "../ShortStrings.sol";
import "../../interfaces/IERC5267.sol";
/**
* @dev https://eips.ethereum.org/EIPS/eip-712[EIP 712] is a standard for hashing and signing of typed structured data.
*
* The encoding specified in the EIP is very generic, and such a generic implementation in Solidity is not feasible,
* thus this contract does not implement the encoding itself. Protocols need to implement the type-specific encoding
* they need in their contracts using a combination of `abi.encode` and `keccak256`.
*
* This contract implements the EIP 712 domain separator ({_domainSeparatorV4}) that is used as part of the encoding
* scheme, and the final step of the encoding to obtain the message digest that is then signed via ECDSA
* ({_hashTypedDataV4}).
*
* The implementation of the domain separator was designed to be as efficient as possible while still properly updating
* the chain id to protect against replay attacks on an eventual fork of the chain.
*
* NOTE: This contract implements the version of the encoding known as "v4", as implemented by the JSON RPC method
* https://docs.metamask.io/guide/signing-data.html[`eth_signTypedDataV4` in MetaMask].
*
* NOTE: In the upgradeable version of this contract, the cached values will correspond to the address, and the domain
* separator of the implementation contract. This will cause the `_domainSeparatorV4` function to always rebuild the
* separator from the immutable values, which is cheaper than accessing a cached version in cold storage.
*
* _Available since v3.4._
*
* @custom:oz-upgrades-unsafe-allow state-variable-immutable state-variable-assignment
*/
abstract contract EIP712 is IERC5267 {
using ShortStrings for *;
bytes32 private constant _TYPE_HASH =
keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)");
// Cache the domain separator as an immutable value, but also store the chain id that it corresponds to, in order to
// invalidate the cached domain separator if the chain id changes.
bytes32 private immutable _cachedDomainSeparator;
uint256 private immutable _cachedChainId;
address private immutable _cachedThis;
bytes32 private immutable _hashedName;
bytes32 private immutable _hashedVersion;
ShortString private immutable _name;
ShortString private immutable _version;
string private _nameFallback;
string private _versionFallback;
/**
* @dev Initializes the domain separator and parameter caches.
*
* The meaning of `name` and `version` is specified in
* https://eips.ethereum.org/EIPS/eip-712#definition-of-domainseparator[EIP 712]:
*
* - `name`: the user readable name of the signing domain, i.e. the name of the DApp or the protocol.
* - `version`: the current major version of the signing domain.
*
* NOTE: These parameters cannot be changed except through a xref:learn::upgrading-smart-contracts.adoc[smart
* contract upgrade].
*/
constructor(string memory name, string memory version) {
_name = name.toShortStringWithFallback(_nameFallback);
_version = version.toShortStringWithFallback(_versionFallback);
_hashedName = keccak256(bytes(name));
_hashedVersion = keccak256(bytes(version));
_cachedChainId = block.chainid;
_cachedDomainSeparator = _buildDomainSeparator();
_cachedThis = address(this);
}
/**
* @dev Returns the domain separator for the current chain.
*/
function _domainSeparatorV4() internal view returns (bytes32) {
if (address(this) == _cachedThis && block.chainid == _cachedChainId) {
return _cachedDomainSeparator;
} else {
return _buildDomainSeparator();
}
}
function _buildDomainSeparator() private view returns (bytes32) {
return keccak256(abi.encode(_TYPE_HASH, _hashedName, _hashedVersion, block.chainid, address(this)));
}
/**
* @dev Given an already https://eips.ethereum.org/EIPS/eip-712#definition-of-hashstruct[hashed struct], this
* function returns the hash of the fully encoded EIP712 message for this domain.
*
* This hash can be used together with {ECDSA-recover} to obtain the signer of a message. For example:
*
* ```solidity
* bytes32 digest = _hashTypedDataV4(keccak256(abi.encode(
* keccak256("Mail(address to,string contents)"),
* mailTo,
* keccak256(bytes(mailContents))
* )));
* address signer = ECDSA.recover(digest, signature);
* ```
*/
function _hashTypedDataV4(bytes32 structHash) internal view virtual returns (bytes32) {
return ECDSA.toTypedDataHash(_domainSeparatorV4(), structHash);
}
/**
* @dev See {EIP-5267}.
*
* _Available since v4.9._
*/
function eip712Domain()
public
view
virtual
override
returns (
bytes1 fields,
string memory name,
string memory version,
uint256 chainId,
address verifyingContract,
bytes32 salt,
uint256[] memory extensions
)
{
return (
hex"0f", // 01111
_name.toStringWithFallback(_nameFallback),
_version.toStringWithFallback(_versionFallback),
block.chainid,
address(this),
bytes32(0),
new uint256[](0)
);
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Counters.sol)
pragma solidity ^0.8.0;
/**
* @title Counters
* @author Matt Condon (@shrugs)
* @dev Provides counters that can only be incremented, decremented or reset. This can be used e.g. to track the number
* of elements in a mapping, issuing ERC721 ids, or counting request ids.
*
* Include with `using Counters for Counters.Counter;`
*/
library Counters {
struct Counter {
// This variable should never be directly accessed by users of the library: interactions must be restricted to
// the library's function. As of Solidity v0.5.2, this cannot be enforced, though there is a proposal to add
// this feature: see https://github.com/ethereum/solidity/issues/4637
uint256 _value; // default: 0
}
function current(Counter storage counter) internal view returns (uint256) {
return counter._value;
}
function increment(Counter storage counter) internal {
unchecked {
counter._value += 1;
}
}
function decrement(Counter storage counter) internal {
uint256 value = counter._value;
require(value > 0, "Counter: decrement overflow");
unchecked {
counter._value = value - 1;
}
}
function reset(Counter storage counter) internal {
counter._value = 0;
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (access/Ownable.sol)
pragma solidity ^0.8.0;
import "../utils/Context.sol";
/**
* @dev Contract module which provides a basic access control mechanism, where
* there is an account (an owner) that can be granted exclusive access to
* specific functions.
*
* By default, the owner account will be the one that deploys the contract. This
* can later be changed with {transferOwnership}.
*
* This module is used through inheritance. It will make available the modifier
* `onlyOwner`, which can be applied to your functions to restrict their use to
* the owner.
*/
abstract contract Ownable is Context {
address private _owner;
event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
/**
* @dev Initializes the contract setting the deployer as the initial owner.
*/
constructor() {
_transferOwnership(_msgSender());
}
/**
* @dev Throws if called by any account other than the owner.
*/
modifier onlyOwner() {
_checkOwner();
_;
}
/**
* @dev Returns the address of the current owner.
*/
function owner() public view virtual returns (address) {
return _owner;
}
/**
* @dev Throws if the sender is not the owner.
*/
function _checkOwner() internal view virtual {
require(owner() == _msgSender(), "Ownable: caller is not the owner");
}
/**
* @dev Leaves the contract without owner. It will not be possible to call
* `onlyOwner` functions. Can only be called by the current owner.
*
* NOTE: Renouncing ownership will leave the contract without an owner,
* thereby disabling any functionality that is only available to the owner.
*/
function renounceOwnership() public virtual onlyOwner {
_transferOwnership(address(0));
}
/**
* @dev Transfers ownership of the contract to a new account (`newOwner`).
* Can only be called by the current owner.
*/
function transferOwnership(address newOwner) public virtual onlyOwner {
require(newOwner != address(0), "Ownable: new owner is the zero address");
_transferOwnership(newOwner);
}
/**
* @dev Transfers ownership of the contract to a new account (`newOwner`).
* Internal function without access restriction.
*/
function _transferOwnership(address newOwner) internal virtual {
address oldOwner = _owner;
_owner = newOwner;
emit OwnershipTransferred(oldOwner, newOwner);
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (utils/Strings.sol)
pragma solidity ^0.8.0;
import "./math/Math.sol";
import "./math/SignedMath.sol";
/**
* @dev String operations.
*/
library Strings {
bytes16 private constant _SYMBOLS = "0123456789abcdef";
uint8 private constant _ADDRESS_LENGTH = 20;
/**
* @dev Converts a `uint256` to its ASCII `string` decimal representation.
*/
function toString(uint256 value) internal pure returns (string memory) {
unchecked {
uint256 length = Math.log10(value) + 1;
string memory buffer = new string(length);
uint256 ptr;
/// @solidity memory-safe-assembly
assembly {
ptr := add(buffer, add(32, length))
}
while (true) {
ptr--;
/// @solidity memory-safe-assembly
assembly {
mstore8(ptr, byte(mod(value, 10), _SYMBOLS))
}
value /= 10;
if (value == 0) break;
}
return buffer;
}
}
/**
* @dev Converts a `int256` to its ASCII `string` decimal representation.
*/
function toString(int256 value) internal pure returns (string memory) {
return string(abi.encodePacked(value < 0 ? "-" : "", toString(SignedMath.abs(value))));
}
/**
* @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
*/
function toHexString(uint256 value) internal pure returns (string memory) {
unchecked {
return toHexString(value, Math.log256(value) + 1);
}
}
/**
* @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
*/
function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
bytes memory buffer = new bytes(2 * length + 2);
buffer[0] = "0";
buffer[1] = "x";
for (uint256 i = 2 * length + 1; i > 1; --i) {
buffer[i] = _SYMBOLS[value & 0xf];
value >>= 4;
}
require(value == 0, "Strings: hex length insufficient");
return string(buffer);
}
/**
* @dev Converts an `address` with fixed length of 20 bytes to its not checksummed ASCII `string` hexadecimal representation.
*/
function toHexString(address addr) internal pure returns (string memory) {
return toHexString(uint256(uint160(addr)), _ADDRESS_LENGTH);
}
/**
* @dev Returns true if the two strings are equal.
*/
function equal(string memory a, string memory b) internal pure returns (bool) {
return keccak256(bytes(a)) == keccak256(bytes(b));
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (utils/ShortStrings.sol)
pragma solidity ^0.8.8;
import "./StorageSlot.sol";
// | string | 0xAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA |
// | length | 0x BB |
type ShortString is bytes32;
/**
* @dev This library provides functions to convert short memory strings
* into a `ShortString` type that can be used as an immutable variable.
*
* Strings of arbitrary length can be optimized using this library if
* they are short enough (up to 31 bytes) by packing them with their
* length (1 byte) in a single EVM word (32 bytes). Additionally, a
* fallback mechanism can be used for every other case.
*
* Usage example:
*
* ```solidity
* contract Named {
* using ShortStrings for *;
*
* ShortString private immutable _name;
* string private _nameFallback;
*
* constructor(string memory contractName) {
* _name = contractName.toShortStringWithFallback(_nameFallback);
* }
*
* function name() external view returns (string memory) {
* return _name.toStringWithFallback(_nameFallback);
* }
* }
* ```
*/
library ShortStrings {
// Used as an identifier for strings longer than 31 bytes.
bytes32 private constant _FALLBACK_SENTINEL = 0x00000000000000000000000000000000000000000000000000000000000000FF;
error StringTooLong(string str);
error InvalidShortString();
/**
* @dev Encode a string of at most 31 chars into a `ShortString`.
*
* This will trigger a `StringTooLong` error is the input string is too long.
*/
function toShortString(string memory str) internal pure returns (ShortString) {
bytes memory bstr = bytes(str);
if (bstr.length > 31) {
revert StringTooLong(str);
}
return ShortString.wrap(bytes32(uint256(bytes32(bstr)) | bstr.length));
}
/**
* @dev Decode a `ShortString` back to a "normal" string.
*/
function toString(ShortString sstr) internal pure returns (string memory) {
uint256 len = byteLength(sstr);
// using `new string(len)` would work locally but is not memory safe.
string memory str = new string(32);
/// @solidity memory-safe-assembly
assembly {
mstore(str, len)
mstore(add(str, 0x20), sstr)
}
return str;
}
/**
* @dev Return the length of a `ShortString`.
*/
function byteLength(ShortString sstr) internal pure returns (uint256) {
uint256 result = uint256(ShortString.unwrap(sstr)) & 0xFF;
if (result > 31) {
revert InvalidShortString();
}
return result;
}
/**
* @dev Encode a string into a `ShortString`, or write it to storage if it is too long.
*/
function toShortStringWithFallback(string memory value, string storage store) internal returns (ShortString) {
if (bytes(value).length < 32) {
return toShortString(value);
} else {
StorageSlot.getStringSlot(store).value = value;
return ShortString.wrap(_FALLBACK_SENTINEL);
}
}
/**
* @dev Decode a string that was encoded to `ShortString` or written to storage using {setWithFallback}.
*/
function toStringWithFallback(ShortString value, string storage store) internal pure returns (string memory) {
if (ShortString.unwrap(value) != _FALLBACK_SENTINEL) {
return toString(value);
} else {
return store;
}
}
/**
* @dev Return the length of a string that was encoded to `ShortString` or written to storage using {setWithFallback}.
*
* WARNING: This will return the "byte length" of the string. This may not reflect the actual length in terms of
* actual characters as the UTF-8 encoding of a single character can span over multiple bytes.
*/
function byteLengthWithFallback(ShortString value, string storage store) internal view returns (uint256) {
if (ShortString.unwrap(value) != _FALLBACK_SENTINEL) {
return byteLength(value);
} else {
return bytes(store).length;
}
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (interfaces/IERC5267.sol)
pragma solidity ^0.8.0;
interface IERC5267 {
/**
* @dev MAY be emitted to signal that the domain could have changed.
*/
event EIP712DomainChanged();
/**
* @dev returns the fields and values that describe the domain separator used by this contract for EIP-712
* signature.
*/
function eip712Domain()
external
view
returns (
bytes1 fields,
string memory name,
string memory version,
uint256 chainId,
address verifyingContract,
bytes32 salt,
uint256[] memory extensions
);
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (utils/math/Math.sol)
pragma solidity ^0.8.0;
/**
* @dev Standard math utilities missing in the Solidity language.
*/
library Math {
enum Rounding {
Down, // Toward negative infinity
Up, // Toward infinity
Zero // Toward zero
}
/**
* @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.
return (a & b) + (a ^ b) / 2;
}
/**
* @dev Returns the ceiling of the division of two numbers.
*
* This differs from standard division with `/` in that it rounds up instead
* of rounding down.
*/
function ceilDiv(uint256 a, uint256 b) internal pure returns (uint256) {
// (a + b - 1) / b can overflow on addition, so we distribute.
return a == 0 ? 0 : (a - 1) / b + 1;
}
/**
* @notice Calculates floor(x * y / denominator) with full precision. Throws if result overflows a uint256 or denominator == 0
* @dev Original credit to Remco Bloemen under MIT license (https://xn--2-umb.com/21/muldiv)
* with further edits by Uniswap Labs also under MIT license.
*/
function mulDiv(uint256 x, uint256 y, uint256 denominator) internal pure returns (uint256 result) {
unchecked {
// 512-bit multiply [prod1 prod0] = x * y. Compute the product mod 2^256 and mod 2^256 - 1, then use
// use the Chinese Remainder Theorem to reconstruct the 512 bit result. The result is stored in two 256
// variables such that product = prod1 * 2^256 + prod0.
uint256 prod0; // Least significant 256 bits of the product
uint256 prod1; // Most significant 256 bits of the product
assembly {
let mm := mulmod(x, y, not(0))
prod0 := mul(x, y)
prod1 := sub(sub(mm, prod0), lt(mm, prod0))
}
// Handle non-overflow cases, 256 by 256 division.
if (prod1 == 0) {
// Solidity will revert if denominator == 0, unlike the div opcode on its own.
// The surrounding unchecked block does not change this fact.
// See https://docs.soliditylang.org/en/latest/control-structures.html#checked-or-unchecked-arithmetic.
return prod0 / denominator;
}
// Make sure the result is less than 2^256. Also prevents denominator == 0.
require(denominator > prod1, "Math: mulDiv overflow");
///////////////////////////////////////////////
// 512 by 256 division.
///////////////////////////////////////////////
// Make division exact by subtracting the remainder from [prod1 prod0].
uint256 remainder;
assembly {
// Compute remainder using mulmod.
remainder := mulmod(x, y, denominator)
// Subtract 256 bit number from 512 bit number.
prod1 := sub(prod1, gt(remainder, prod0))
prod0 := sub(prod0, remainder)
}
// Factor powers of two out of denominator and compute largest power of two divisor of denominator. Always >= 1.
// See https://cs.stackexchange.com/q/138556/92363.
// Does not overflow because the denominator cannot be zero at this stage in the function.
uint256 twos = denominator & (~denominator + 1);
assembly {
// Divide denominator by twos.
denominator := div(denominator, twos)
// Divide [prod1 prod0] by twos.
prod0 := div(prod0, twos)
// Flip twos such that it is 2^256 / twos. If twos is zero, then it becomes one.
twos := add(div(sub(0, twos), twos), 1)
}
// Shift in bits from prod1 into prod0.
prod0 |= prod1 * twos;
// Invert denominator mod 2^256. Now that denominator is an odd number, it has an inverse modulo 2^256 such
// that denominator * inv = 1 mod 2^256. Compute the inverse by starting with a seed that is correct for
// four bits. That is, denominator * inv = 1 mod 2^4.
uint256 inverse = (3 * denominator) ^ 2;
// Use the Newton-Raphson iteration to improve the precision. Thanks to Hensel's lifting lemma, this also works
// in modular arithmetic, doubling the correct bits in each step.
inverse *= 2 - denominator * inverse; // inverse mod 2^8
inverse *= 2 - denominator * inverse; // inverse mod 2^16
inverse *= 2 - denominator * inverse; // inverse mod 2^32
inverse *= 2 - denominator * inverse; // inverse mod 2^64
inverse *= 2 - denominator * inverse; // inverse mod 2^128
inverse *= 2 - denominator * inverse; // inverse mod 2^256
// Because the division is now exact we can divide by multiplying with the modular inverse of denominator.
// This will give us the correct result modulo 2^256. Since the preconditions guarantee that the outcome is
// less than 2^256, this is the final result. We don't need to compute the high bits of the result and prod1
// is no longer required.
result = prod0 * inverse;
return result;
}
}
/**
* @notice Calculates x * y / denominator with full precision, following the selected rounding direction.
*/
function mulDiv(uint256 x, uint256 y, uint256 denominator, Rounding rounding) internal pure returns (uint256) {
uint256 result = mulDiv(x, y, denominator);
if (rounding == Rounding.Up && mulmod(x, y, denominator) > 0) {
result += 1;
}
return result;
}
/**
* @dev Returns the square root of a number. If the number is not a perfect square, the value is rounded down.
*
* Inspired by Henry S. Warren, Jr.'s "Hacker's Delight" (Chapter 11).
*/
function sqrt(uint256 a) internal pure returns (uint256) {
if (a == 0) {
return 0;
}
// For our first guess, we get the biggest power of 2 which is smaller than the square root of the target.
//
// We know that the "msb" (most significant bit) of our target number `a` is a power of 2 such that we have
// `msb(a) <= a < 2*msb(a)`. This value can be written `msb(a)=2**k` with `k=log2(a)`.
//
// This can be rewritten `2**log2(a) <= a < 2**(log2(a) + 1)`
// → `sqrt(2**k) <= sqrt(a) < sqrt(2**(k+1))`
// → `2**(k/2) <= sqrt(a) < 2**((k+1)/2) <= 2**(k/2 + 1)`
//
// Consequently, `2**(log2(a) / 2)` is a good first approximation of `sqrt(a)` with at least 1 correct bit.
uint256 result = 1 << (log2(a) >> 1);
// At this point `result` is an estimation with one bit of precision. We know the true value is a uint128,
// since it is the square root of a uint256. Newton's method converges quadratically (precision doubles at
// every iteration). We thus need at most 7 iteration to turn our partial result with one bit of precision
// into the expected uint128 result.
unchecked {
result = (result + a / result) >> 1;
result = (result + a / result) >> 1;
result = (result + a / result) >> 1;
result = (result + a / result) >> 1;
result = (result + a / result) >> 1;
result = (result + a / result) >> 1;
result = (result + a / result) >> 1;
return min(result, a / result);
}
}
/**
* @notice Calculates sqrt(a), following the selected rounding direction.
*/
function sqrt(uint256 a, Rounding rounding) internal pure returns (uint256) {
unchecked {
uint256 result = sqrt(a);
return result + (rounding == Rounding.Up && result * result < a ? 1 : 0);
}
}
/**
* @dev Return the log in base 2, rounded down, of a positive value.
* Returns 0 if given 0.
*/
function log2(uint256 value) internal pure returns (uint256) {
uint256 result = 0;
unchecked {
if (value >> 128 > 0) {
value >>= 128;
result += 128;
}
if (value >> 64 > 0) {
value >>= 64;
result += 64;
}
if (value >> 32 > 0) {
value >>= 32;
result += 32;
}
if (value >> 16 > 0) {
value >>= 16;
result += 16;
}
if (value >> 8 > 0) {
value >>= 8;
result += 8;
}
if (value >> 4 > 0) {
value >>= 4;
result += 4;
}
if (value >> 2 > 0) {
value >>= 2;
result += 2;
}
if (value >> 1 > 0) {
result += 1;
}
}
return result;
}
/**
* @dev Return the log in base 2, following the selected rounding direction, of a positive value.
* Returns 0 if given 0.
*/
function log2(uint256 value, Rounding rounding) internal pure returns (uint256) {
unchecked {
uint256 result = log2(value);
return result + (rounding == Rounding.Up && 1 << result < value ? 1 : 0);
}
}
/**
* @dev Return the log in base 10, rounded down, of a positive value.
* Returns 0 if given 0.
*/
function log10(uint256 value) internal pure returns (uint256) {
uint256 result = 0;
unchecked {
if (value >= 10 ** 64) {
value /= 10 ** 64;
result += 64;
}
if (value >= 10 ** 32) {
value /= 10 ** 32;
result += 32;
}
if (value >= 10 ** 16) {
value /= 10 ** 16;
result += 16;
}
if (value >= 10 ** 8) {
value /= 10 ** 8;
result += 8;
}
if (value >= 10 ** 4) {
value /= 10 ** 4;
result += 4;
}
if (value >= 10 ** 2) {
value /= 10 ** 2;
result += 2;
}
if (value >= 10 ** 1) {
result += 1;
}
}
return result;
}
/**
* @dev Return the log in base 10, following the selected rounding direction, of a positive value.
* Returns 0 if given 0.
*/
function log10(uint256 value, Rounding rounding) internal pure returns (uint256) {
unchecked {
uint256 result = log10(value);
return result + (rounding == Rounding.Up && 10 ** result < value ? 1 : 0);
}
}
/**
* @dev Return the log in base 256, rounded down, of a positive value.
* Returns 0 if given 0.
*
* Adding one to the result gives the number of pairs of hex symbols needed to represent `value` as a hex string.
*/
function log256(uint256 value) internal pure returns (uint256) {
uint256 result = 0;
unchecked {
if (value >> 128 > 0) {
value >>= 128;
result += 16;
}
if (value >> 64 > 0) {
value >>= 64;
result += 8;
}
if (value >> 32 > 0) {
value >>= 32;
result += 4;
}
if (value >> 16 > 0) {
value >>= 16;
result += 2;
}
if (value >> 8 > 0) {
result += 1;
}
}
return result;
}
/**
* @dev Return the log in base 256, following the selected rounding direction, of a positive value.
* Returns 0 if given 0.
*/
function log256(uint256 value, Rounding rounding) internal pure returns (uint256) {
unchecked {
uint256 result = log256(value);
return result + (rounding == Rounding.Up && 1 << (result << 3) < value ? 1 : 0);
}
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (utils/math/SignedMath.sol)
pragma solidity ^0.8.0;
/**
* @dev Standard signed math utilities missing in the Solidity language.
*/
library SignedMath {
/**
* @dev Returns the largest of two signed numbers.
*/
function max(int256 a, int256 b) internal pure returns (int256) {
return a > b ? a : b;
}
/**
* @dev Returns the smallest of two signed numbers.
*/
function min(int256 a, int256 b) internal pure returns (int256) {
return a < b ? a : b;
}
/**
* @dev Returns the average of two signed numbers without overflow.
* The result is rounded towards zero.
*/
function average(int256 a, int256 b) internal pure returns (int256) {
// Formula from the book "Hacker's Delight"
int256 x = (a & b) + ((a ^ b) >> 1);
return x + (int256(uint256(x) >> 255) & (a ^ b));
}
/**
* @dev Returns the absolute unsigned value of a signed value.
*/
function abs(int256 n) internal pure returns (uint256) {
unchecked {
// must be unchecked in order to support `n = type(int256).min`
return uint256(n >= 0 ? n : -n);
}
}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (utils/StorageSlot.sol)
// This file was procedurally generated from scripts/generate/templates/StorageSlot.js.
pragma solidity ^0.8.0;
/**
* @dev Library for reading and writing primitive types to specific storage slots.
*
* Storage slots are often used to avoid storage conflict when dealing with upgradeable contracts.
* This library helps with reading and writing to such slots without the need for inline assembly.
*
* The functions in this library return Slot structs that contain a `value` member that can be used to read or write.
*
* Example usage to set ERC1967 implementation slot:
* ```solidity
* contract ERC1967 {
* bytes32 internal constant _IMPLEMENTATION_SLOT = 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc;
*
* function _getImplementation() internal view returns (address) {
* return StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value;
* }
*
* function _setImplementation(address newImplementation) internal {
* require(Address.isContract(newImplementation), "ERC1967: new implementation is not a contract");
* StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value = newImplementation;
* }
* }
* ```
*
* _Available since v4.1 for `address`, `bool`, `bytes32`, `uint256`._
* _Available since v4.9 for `string`, `bytes`._
*/
library StorageSlot {
struct AddressSlot {
address value;
}
struct BooleanSlot {
bool value;
}
struct Bytes32Slot {
bytes32 value;
}
struct Uint256Slot {
uint256 value;
}
struct StringSlot {
string value;
}
struct BytesSlot {
bytes value;
}
/**
* @dev Returns an `AddressSlot` with member `value` located at `slot`.
*/
function getAddressSlot(bytes32 slot) internal pure returns (AddressSlot storage r) {
/// @solidity memory-safe-assembly
assembly {
r.slot := slot
}
}
/**
* @dev Returns an `BooleanSlot` with member `value` located at `slot`.
*/
function getBooleanSlot(bytes32 slot) internal pure returns (BooleanSlot storage r) {
/// @solidity memory-safe-assembly
assembly {
r.slot := slot
}
}
/**
* @dev Returns an `Bytes32Slot` with member `value` located at `slot`.
*/
function getBytes32Slot(bytes32 slot) internal pure returns (Bytes32Slot storage r) {
/// @solidity memory-safe-assembly
assembly {
r.slot := slot
}
}
/**
* @dev Returns an `Uint256Slot` with member `value` located at `slot`.
*/
function getUint256Slot(bytes32 slot) internal pure returns (Uint256Slot storage r) {
/// @solidity memory-safe-assembly
assembly {
r.slot := slot
}
}
/**
* @dev Returns an `StringSlot` with member `value` located at `slot`.
*/
function getStringSlot(bytes32 slot) internal pure returns (StringSlot storage r) {
/// @solidity memory-safe-assembly
assembly {
r.slot := slot
}
}
/**
* @dev Returns an `StringSlot` representation of the string storage pointer `store`.
*/
function getStringSlot(string storage store) internal pure returns (StringSlot storage r) {
/// @solidity memory-safe-assembly
assembly {
r.slot := store.slot
}
}
/**
* @dev Returns an `BytesSlot` with member `value` located at `slot`.
*/
function getBytesSlot(bytes32 slot) internal pure returns (BytesSlot storage r) {
/// @solidity memory-safe-assembly
assembly {
r.slot := slot
}
}
/**
* @dev Returns an `BytesSlot` representation of the bytes storage pointer `store`.
*/
function getBytesSlot(bytes storage store) internal pure returns (BytesSlot storage r) {
/// @solidity memory-safe-assembly
assembly {
r.slot := store.slot
}
}
}