Contract Address Details

// SPDX-FileCopyrightText: 2023 Lido <info@lido.fi>
// SPDX-License-Identifier: GPL-3.0

/* See contracts/COMPILERS.md */
pragma solidity 0.4.24;

import "@aragon/os/contracts/apps/AragonApp.sol";
import "@aragon/os/contracts/lib/math/SafeMath.sol";

import "../common/interfaces/ILidoLocator.sol";
import "../common/interfaces/IBurner.sol";

import "./lib/StakeLimitUtils.sol";
import "../common/lib/Math256.sol";

import "./StETHPermit.sol";

import "./utils/Versioned.sol";

interface IPostTokenRebaseReceiver {
    function handlePostTokenRebase(
        uint256 _reportTimestamp,
        uint256 _timeElapsed,
        uint256 _preTotalShares,
        uint256 _preTotalEther,
        uint256 _postTotalShares,
        uint256 _postTotalEther,
        uint256 _sharesMintedAsFees
    ) external;
}

interface IOracleReportSanityChecker {
    function checkAccountingOracleReport(
        uint256 _timeElapsed,
        uint256 _preCLBalance,
        uint256 _postCLBalance,
        uint256 _withdrawalVaultBalance,
        uint256 _elRewardsVaultBalance,
        uint256 _sharesRequestedToBurn,
        uint256 _preCLValidators,
        uint256 _postCLValidators
    ) external view;

    function smoothenTokenRebase(
        uint256 _preTotalPooledEther,
        uint256 _preTotalShares,
        uint256 _preCLBalance,
        uint256 _postCLBalance,
        uint256 _withdrawalVaultBalance,
        uint256 _elRewardsVaultBalance,
        uint256 _sharesRequestedToBurn,
        uint256 _etherToLockForWithdrawals,
        uint256 _newSharesToBurnForWithdrawals
    ) external view returns (
        uint256 withdrawals,
        uint256 elRewards,
        uint256 simulatedSharesToBurn,
        uint256 sharesToBurn
    );

    function checkWithdrawalQueueOracleReport(
        uint256 _lastFinalizableRequestId,
        uint256 _reportTimestamp
    ) external view;

    function checkSimulatedShareRate(
        uint256 _postTotalPooledEther,
        uint256 _postTotalShares,
        uint256 _etherLockedOnWithdrawalQueue,
        uint256 _sharesBurntDueToWithdrawals,
        uint256 _simulatedShareRate
    ) external view;
}

interface ILidoExecutionLayerRewardsVault {
    function withdrawRewards(uint256 _maxAmount) external returns (uint256 amount);
}

interface IWithdrawalVault {
    function withdrawWithdrawals(uint256 _amount) external;
}

interface IStakingRouter {
    function deposit(
        uint256 _depositsCount,
        uint256 _stakingModuleId,
        bytes _depositCalldata
    ) external payable;

    function getStakingRewardsDistribution()
        external
        view
        returns (
            address[] memory recipients,
            uint256[] memory stakingModuleIds,
            uint96[] memory stakingModuleFees,
            uint96 totalFee,
            uint256 precisionPoints
        );

    function getWithdrawalCredentials() external view returns (bytes32);

    function reportRewardsMinted(uint256[] _stakingModuleIds, uint256[] _totalShares) external;

    function getTotalFeeE4Precision() external view returns (uint16 totalFee);

    function getStakingFeeAggregateDistributionE4Precision() external view returns (
        uint16 modulesFee, uint16 treasuryFee
    );

    function getStakingModuleMaxDepositsCount(uint256 _stakingModuleId, uint256 _maxDepositsValue)
        external
        view
        returns (uint256);

    function TOTAL_BASIS_POINTS() external view returns (uint256);
}

interface IWithdrawalQueue {
    function prefinalize(uint256[] _batches, uint256 _maxShareRate)
        external
        view
        returns (uint256 ethToLock, uint256 sharesToBurn);

    function finalize(uint256 _lastIdToFinalize, uint256 _maxShareRate) external payable;

    function isPaused() external view returns (bool);

    function unfinalizedStETH() external view returns (uint256);

    function isBunkerModeActive() external view returns (bool);
}

/**
* @title Liquid staking pool implementation
*
* Lido is an Ethereum liquid staking protocol solving the problem of frozen staked ether on Consensus Layer
* being unavailable for transfers and DeFi on Execution Layer.
*
* Since balances of all token holders change when the amount of total pooled Ether
* changes, this token cannot fully implement ERC20 standard: it only emits `Transfer`
* events upon explicit transfer between holders. In contrast, when Lido oracle reports
* rewards, no Transfer events are generated: doing so would require emitting an event
* for each token holder and thus running an unbounded loop.
*
* ---
* NB: Order of inheritance must preserve the structured storage layout of the previous versions.
*
* @dev Lido is derived from `StETHPermit` that has a structured storage:
* SLOT 0: mapping (address => uint256) private shares (`StETH`)
* SLOT 1: mapping (address => mapping (address => uint256)) private allowances (`StETH`)
* SLOT 2: mapping(address => uint256) internal noncesByAddress (`StETHPermit`)
*
* `Versioned` and `AragonApp` both don't have the pre-allocated structured storage.
*/
contract Lido is Versioned, StETHPermit, AragonApp {
    using SafeMath for uint256;
    using UnstructuredStorage for bytes32;
    using StakeLimitUnstructuredStorage for bytes32;
    using StakeLimitUtils for StakeLimitState.Data;

    /// ACL
    bytes32 public constant PAUSE_ROLE =
        0x139c2898040ef16910dc9f44dc697df79363da767d8bc92f2e310312b816e46d; // keccak256("PAUSE_ROLE");
    bytes32 public constant RESUME_ROLE =
        0x2fc10cc8ae19568712f7a176fb4978616a610650813c9d05326c34abb62749c7; // keccak256("RESUME_ROLE");
    bytes32 public constant STAKING_PAUSE_ROLE =
        0x84ea57490227bc2be925c684e2a367071d69890b629590198f4125a018eb1de8; // keccak256("STAKING_PAUSE_ROLE")
    bytes32 public constant STAKING_CONTROL_ROLE =
        0xa42eee1333c0758ba72be38e728b6dadb32ea767de5b4ddbaea1dae85b1b051f; // keccak256("STAKING_CONTROL_ROLE")
    bytes32 public constant UNSAFE_CHANGE_DEPOSITED_VALIDATORS_ROLE =
        0xe6dc5d79630c61871e99d341ad72c5a052bed2fc8c79e5a4480a7cd31117576c; // keccak256("UNSAFE_CHANGE_DEPOSITED_VALIDATORS_ROLE")

    uint256 private constant DEPOSIT_SIZE = 32 ether;

    /// @dev storage slot position for the Lido protocol contracts locator
    bytes32 internal constant LIDO_LOCATOR_POSITION =
        0x9ef78dff90f100ea94042bd00ccb978430524befc391d3e510b5f55ff3166df7; // keccak256("lido.Lido.lidoLocator")
    /// @dev storage slot position of the staking rate limit structure
    bytes32 internal constant STAKING_STATE_POSITION =
        0xa3678de4a579be090bed1177e0a24f77cc29d181ac22fd7688aca344d8938015; // keccak256("lido.Lido.stakeLimit");
    /// @dev amount of Ether (on the current Ethereum side) buffered on this smart contract balance
    bytes32 internal constant BUFFERED_ETHER_POSITION =
        0xed310af23f61f96daefbcd140b306c0bdbf8c178398299741687b90e794772b0; // keccak256("lido.Lido.bufferedEther");
    /// @dev number of deposited validators (incrementing counter of deposit operations).
    bytes32 internal constant DEPOSITED_VALIDATORS_POSITION =
        0xe6e35175eb53fc006520a2a9c3e9711a7c00de6ff2c32dd31df8c5a24cac1b5c; // keccak256("lido.Lido.depositedValidators");
    /// @dev total amount of ether on Consensus Layer (sum of all the balances of Lido validators)
    // "beacon" in the `keccak256()` parameter is staying here for compatibility reason
    bytes32 internal constant CL_BALANCE_POSITION =
        0xa66d35f054e68143c18f32c990ed5cb972bb68a68f500cd2dd3a16bbf3686483; // keccak256("lido.Lido.beaconBalance");
    /// @dev number of Lido's validators available in the Consensus Layer state
    // "beacon" in the `keccak256()` parameter is staying here for compatibility reason
    bytes32 internal constant CL_VALIDATORS_POSITION =
        0x9f70001d82b6ef54e9d3725b46581c3eb9ee3aa02b941b6aa54d678a9ca35b10; // keccak256("lido.Lido.beaconValidators");
    /// @dev Just a counter of total amount of execution layer rewards received by Lido contract. Not used in the logic.
    bytes32 internal constant TOTAL_EL_REWARDS_COLLECTED_POSITION =
        0xafe016039542d12eec0183bb0b1ffc2ca45b027126a494672fba4154ee77facb; // keccak256("lido.Lido.totalELRewardsCollected");

    // Staking was paused (don't accept user's ether submits)
    event StakingPaused();
    // Staking was resumed (accept user's ether submits)
    event StakingResumed();
    // Staking limit was set (rate limits user's submits)
    event StakingLimitSet(uint256 maxStakeLimit, uint256 stakeLimitIncreasePerBlock);
    // Staking limit was removed
    event StakingLimitRemoved();

    // Emits when validators number delivered by the oracle
    event CLValidatorsUpdated(
        uint256 indexed reportTimestamp,
        uint256 preCLValidators,
        uint256 postCLValidators
    );

    // Emits when var at `DEPOSITED_VALIDATORS_POSITION` changed
    event DepositedValidatorsChanged(
        uint256 depositedValidators
    );

    // Emits when oracle accounting report processed
    event ETHDistributed(
        uint256 indexed reportTimestamp,
        uint256 preCLBalance,
        uint256 postCLBalance,
        uint256 withdrawalsWithdrawn,
        uint256 executionLayerRewardsWithdrawn,
        uint256 postBufferedEther
    );

    // Emits when token rebased (total supply and/or total shares were changed)
    event TokenRebased(
        uint256 indexed reportTimestamp,
        uint256 timeElapsed,
        uint256 preTotalShares,
        uint256 preTotalEther,
        uint256 postTotalShares,
        uint256 postTotalEther,
        uint256 sharesMintedAsFees
    );

    // Lido locator set
    event LidoLocatorSet(address lidoLocator);

    // The amount of ETH withdrawn from LidoExecutionLayerRewardsVault to Lido
    event ELRewardsReceived(uint256 amount);

    // The amount of ETH withdrawn from WithdrawalVault to Lido
    event WithdrawalsReceived(uint256 amount);

    // Records a deposit made by a user
    event Submitted(address indexed sender, uint256 amount, address referral);

    // The `amount` of ether was sent to the deposit_contract.deposit function
    event Unbuffered(uint256 amount);

    /**
    * @dev As AragonApp, Lido contract must be initialized with following variables:
    *      NB: by default, staking and the whole Lido pool are in paused state
    *
    * The contract's balance must be non-zero to allow initial holder bootstrap.
    *
    * @param _lidoLocator lido locator contract
    * @param _eip712StETH eip712 helper contract for StETH
    */
    function initialize(address _lidoLocator, address _eip712StETH)
        public
        payable
        onlyInit
    {
        _bootstrapInitialHolder();
        _initialize_v2(_lidoLocator, _eip712StETH);
        initialized();
    }

    /**
     * initializer for the Lido version "2"
     */
    function _initialize_v2(address _lidoLocator, address _eip712StETH) internal {
        _setContractVersion(2);

        LIDO_LOCATOR_POSITION.setStorageAddress(_lidoLocator);
        _initializeEIP712StETH(_eip712StETH);

        // set infinite allowance for burner from withdrawal queue
        // to burn finalized requests' shares
        _approve(
            ILidoLocator(_lidoLocator).withdrawalQueue(),
            ILidoLocator(_lidoLocator).burner(),
            INFINITE_ALLOWANCE
        );

        emit LidoLocatorSet(_lidoLocator);
    }

    /**
     * @notice A function to finalize upgrade to v2 (from v1). Can be called only once
     * @dev Value "1" in CONTRACT_VERSION_POSITION is skipped due to change in numbering
     *
     * The initial protocol token holder must exist.
     *
     * For more details see https://github.com/lidofinance/lido-improvement-proposals/blob/develop/LIPS/lip-10.md
     */
    function finalizeUpgrade_v2(address _lidoLocator, address _eip712StETH) external {
        _checkContractVersion(0);
        require(hasInitialized(), "NOT_INITIALIZED");

        require(_lidoLocator != address(0), "LIDO_LOCATOR_ZERO_ADDRESS");
        require(_eip712StETH != address(0), "EIP712_STETH_ZERO_ADDRESS");

        require(_sharesOf(INITIAL_TOKEN_HOLDER) != 0, "INITIAL_HOLDER_EXISTS");

        _initialize_v2(_lidoLocator, _eip712StETH);
    }

    /**
     * @notice Stops accepting new Ether to the protocol
     *
     * @dev While accepting new Ether is stopped, calls to the `submit` function,
     * as well as to the default payable function, will revert.
     *
     * Emits `StakingPaused` event.
     */
    function pauseStaking() external {
        _auth(STAKING_PAUSE_ROLE);

        _pauseStaking();
    }

    /**
     * @notice Resumes accepting new Ether to the protocol (if `pauseStaking` was called previously)
     * NB: Staking could be rate-limited by imposing a limit on the stake amount
     * at each moment in time, see `setStakingLimit()` and `removeStakingLimit()`
     *
     * @dev Preserves staking limit if it was set previously
     *
     * Emits `StakingResumed` event
     */
    function resumeStaking() external {
        _auth(STAKING_CONTROL_ROLE);
        require(hasInitialized(), "NOT_INITIALIZED");

        _resumeStaking();
    }

    /**
     * @notice Sets the staking rate limit
     *
     * ▲ Stake limit
     * │.....  .....   ........ ...            ....     ... Stake limit = max
     * │      .       .        .   .   .      .    . . .
     * │     .       .              . .  . . .      . .
     * │            .                .  . . .
     * │──────────────────────────────────────────────────> Time
     * │     ^      ^          ^   ^^^  ^ ^ ^     ^^^ ^     Stake events
     *
     * @dev Reverts if:
     * - `_maxStakeLimit` == 0
     * - `_maxStakeLimit` >= 2^96
     * - `_maxStakeLimit` < `_stakeLimitIncreasePerBlock`
     * - `_maxStakeLimit` / `_stakeLimitIncreasePerBlock` >= 2^32 (only if `_stakeLimitIncreasePerBlock` != 0)
     *
     * Emits `StakingLimitSet` event
     *
     * @param _maxStakeLimit max stake limit value
     * @param _stakeLimitIncreasePerBlock stake limit increase per single block
     */
    function setStakingLimit(uint256 _maxStakeLimit, uint256 _stakeLimitIncreasePerBlock) external {
        _auth(STAKING_CONTROL_ROLE);

        STAKING_STATE_POSITION.setStorageStakeLimitStruct(
            STAKING_STATE_POSITION.getStorageStakeLimitStruct().setStakingLimit(_maxStakeLimit, _stakeLimitIncreasePerBlock)
        );

        emit StakingLimitSet(_maxStakeLimit, _stakeLimitIncreasePerBlock);
    }

    /**
     * @notice Removes the staking rate limit
     *
     * Emits `StakingLimitRemoved` event
     */
    function removeStakingLimit() external {
        _auth(STAKING_CONTROL_ROLE);

        STAKING_STATE_POSITION.setStorageStakeLimitStruct(STAKING_STATE_POSITION.getStorageStakeLimitStruct().removeStakingLimit());

        emit StakingLimitRemoved();
    }

    /**
     * @notice Check staking state: whether it's paused or not
     */
    function isStakingPaused() external view returns (bool) {
        return STAKING_STATE_POSITION.getStorageStakeLimitStruct().isStakingPaused();
    }


    /**
     * @notice Returns how much Ether can be staked in the current block
     * @dev Special return values:
     * - 2^256 - 1 if staking is unlimited;
     * - 0 if staking is paused or if limit is exhausted.
     */
    function getCurrentStakeLimit() external view returns (uint256) {
        return _getCurrentStakeLimit(STAKING_STATE_POSITION.getStorageStakeLimitStruct());
    }

    /**
     * @notice Returns full info about current stake limit params and state
     * @dev Might be used for the advanced integration requests.
     * @return isStakingPaused staking pause state (equivalent to return of isStakingPaused())
     * @return isStakingLimitSet whether the stake limit is set
     * @return currentStakeLimit current stake limit (equivalent to return of getCurrentStakeLimit())
     * @return maxStakeLimit max stake limit
     * @return maxStakeLimitGrowthBlocks blocks needed to restore max stake limit from the fully exhausted state
     * @return prevStakeLimit previously reached stake limit
     * @return prevStakeBlockNumber previously seen block number
     */
    function getStakeLimitFullInfo()
        external
        view
        returns (
            bool isStakingPaused,
            bool isStakingLimitSet,
            uint256 currentStakeLimit,
            uint256 maxStakeLimit,
            uint256 maxStakeLimitGrowthBlocks,
            uint256 prevStakeLimit,
            uint256 prevStakeBlockNumber
        )
    {
        StakeLimitState.Data memory stakeLimitData = STAKING_STATE_POSITION.getStorageStakeLimitStruct();

        isStakingPaused = stakeLimitData.isStakingPaused();
        isStakingLimitSet = stakeLimitData.isStakingLimitSet();

        currentStakeLimit = _getCurrentStakeLimit(stakeLimitData);

        maxStakeLimit = stakeLimitData.maxStakeLimit;
        maxStakeLimitGrowthBlocks = stakeLimitData.maxStakeLimitGrowthBlocks;
        prevStakeLimit = stakeLimitData.prevStakeLimit;
        prevStakeBlockNumber = stakeLimitData.prevStakeBlockNumber;
    }

    /**
    * @notice Send funds to the pool
    * @dev Users are able to submit their funds by transacting to the fallback function.
    * Unlike vanilla Ethereum Deposit contract, accepting only 32-Ether transactions, Lido
    * accepts payments of any size. Submitted Ethers are stored in Buffer until someone calls
    * deposit() and pushes them to the Ethereum Deposit contract.
    */
    // solhint-disable-next-line no-complex-fallback
    function() external payable {
        // protection against accidental submissions by calling non-existent function
        require(msg.data.length == 0, "NON_EMPTY_DATA");
        _submit(0);
    }

    /**
     * @notice Send funds to the pool with optional _referral parameter
     * @dev This function is alternative way to submit funds. Supports optional referral address.
     * @return Amount of StETH shares generated
     */
    function submit(address _referral) external payable returns (uint256) {
        return _submit(_referral);
    }

    /**
     * @notice A payable function for execution layer rewards. Can be called only by `ExecutionLayerRewardsVault`
     * @dev We need a dedicated function because funds received by the default payable function
     * are treated as a user deposit
     */
    function receiveELRewards() external payable {
        require(msg.sender == getLidoLocator().elRewardsVault());

        TOTAL_EL_REWARDS_COLLECTED_POSITION.setStorageUint256(getTotalELRewardsCollected().add(msg.value));

        emit ELRewardsReceived(msg.value);
    }

    /**
    * @notice A payable function for withdrawals acquisition. Can be called only by `WithdrawalVault`
    * @dev We need a dedicated function because funds received by the default payable function
    * are treated as a user deposit
    */
    function receiveWithdrawals() external payable {
        require(msg.sender == getLidoLocator().withdrawalVault());

        emit WithdrawalsReceived(msg.value);
    }

    /**
     * @notice Stop pool routine operations
     */
    function stop() external {
        _auth(PAUSE_ROLE);

        _stop();
        _pauseStaking();
    }

    /**
     * @notice Resume pool routine operations
     * @dev Staking is resumed after this call using the previously set limits (if any)
     */
    function resume() external {
        _auth(RESUME_ROLE);

        _resume();
        _resumeStaking();
    }

    /**
     * The structure is used to aggregate the `handleOracleReport` provided data.
     * @dev Using the in-memory structure addresses `stack too deep` issues.
     */
    struct OracleReportedData {
        // Oracle timings
        uint256 reportTimestamp;
        uint256 timeElapsed;
        // CL values
        uint256 clValidators;
        uint256 postCLBalance;
        // EL values
        uint256 withdrawalVaultBalance;
        uint256 elRewardsVaultBalance;
        uint256 sharesRequestedToBurn;
        // Decision about withdrawals processing
        uint256[] withdrawalFinalizationBatches;
        uint256 simulatedShareRate;
    }

    /**
     * The structure is used to preload the contract using `getLidoLocator()` via single call
     */
    struct OracleReportContracts {
        address accountingOracle;
        address elRewardsVault;
        address oracleReportSanityChecker;
        address burner;
        address withdrawalQueue;
        address withdrawalVault;
        address postTokenRebaseReceiver;
    }

    /**
    * @notice Updates accounting stats, collects EL rewards and distributes collected rewards
    *         if beacon balance increased, performs withdrawal requests finalization
    * @dev periodically called by the AccountingOracle contract
    *
    * @param _reportTimestamp the moment of the oracle report calculation
    * @param _timeElapsed seconds elapsed since the previous report calculation
    * @param _clValidators number of Lido validators on Consensus Layer
    * @param _clBalance sum of all Lido validators' balances on Consensus Layer
    * @param _withdrawalVaultBalance withdrawal vault balance on Execution Layer at `_reportTimestamp`
    * @param _elRewardsVaultBalance elRewards vault balance on Execution Layer at `_reportTimestamp`
    * @param _sharesRequestedToBurn shares requested to burn through Burner at `_reportTimestamp`
    * @param _withdrawalFinalizationBatches the ascendingly-sorted array of withdrawal request IDs obtained by calling
    * WithdrawalQueue.calculateFinalizationBatches. Empty array means that no withdrawal requests should be finalized
    * @param _simulatedShareRate share rate that was simulated by oracle when the report data created (1e27 precision)
    *
    * NB: `_simulatedShareRate` should be calculated off-chain by calling the method with `eth_call` JSON-RPC API
    * while passing empty `_withdrawalFinalizationBatches` and `_simulatedShareRate` == 0, plugging the returned values
    * to the following formula: `_simulatedShareRate = (postTotalPooledEther * 1e27) / postTotalShares`
    *
    * @return postRebaseAmounts[0]: `postTotalPooledEther` amount of ether in the protocol after report
    * @return postRebaseAmounts[1]: `postTotalShares` amount of shares in the protocol after report
    * @return postRebaseAmounts[2]: `withdrawals` withdrawn from the withdrawals vault
    * @return postRebaseAmounts[3]: `elRewards` withdrawn from the execution layer rewards vault
    */
    function handleOracleReport(
        // Oracle timings
        uint256 _reportTimestamp,
        uint256 _timeElapsed,
        // CL values
        uint256 _clValidators,
        uint256 _clBalance,
        // EL values
        uint256 _withdrawalVaultBalance,
        uint256 _elRewardsVaultBalance,
        uint256 _sharesRequestedToBurn,
        // Decision about withdrawals processing
        uint256[] _withdrawalFinalizationBatches,
        uint256 _simulatedShareRate
    ) external returns (uint256[4] postRebaseAmounts) {
        _whenNotStopped();

        return _handleOracleReport(
            OracleReportedData(
                _reportTimestamp,
                _timeElapsed,
                _clValidators,
                _clBalance,
                _withdrawalVaultBalance,
                _elRewardsVaultBalance,
                _sharesRequestedToBurn,
                _withdrawalFinalizationBatches,
                _simulatedShareRate
            )
        );
    }

    /**
     * @notice Unsafely change deposited validators
     *
     * The method unsafely changes deposited validator counter.
     * Can be required when onboarding external validators to Lido
     * (i.e., had deposited before and rotated their type-0x00 withdrawal credentials to Lido)
     *
     * @param _newDepositedValidators new value
     */
    function unsafeChangeDepositedValidators(uint256 _newDepositedValidators) external {
        _auth(UNSAFE_CHANGE_DEPOSITED_VALIDATORS_ROLE);

        DEPOSITED_VALIDATORS_POSITION.setStorageUint256(_newDepositedValidators);

        emit DepositedValidatorsChanged(_newDepositedValidators);
    }

    /**
     * @notice Overrides default AragonApp behaviour to disallow recovery.
     */
    function transferToVault(address /* _token */) external {
        revert("NOT_SUPPORTED");
    }

    /**
    * @notice Get the amount of Ether temporary buffered on this contract balance
    * @dev Buffered balance is kept on the contract from the moment the funds are received from user
    * until the moment they are actually sent to the official Deposit contract.
    * @return amount of buffered funds in wei
    */
    function getBufferedEther() external view returns (uint256) {
        return _getBufferedEther();
    }

    /**
     * @notice Get total amount of execution layer rewards collected to Lido contract
     * @dev Ether got through LidoExecutionLayerRewardsVault is kept on this contract's balance the same way
     * as other buffered Ether is kept (until it gets deposited)
     * @return amount of funds received as execution layer rewards in wei
     */
    function getTotalELRewardsCollected() public view returns (uint256) {
        return TOTAL_EL_REWARDS_COLLECTED_POSITION.getStorageUint256();
    }

    /**
     * @notice Gets authorized oracle address
     * @return address of oracle contract
     */
    function getLidoLocator() public view returns (ILidoLocator) {
        return ILidoLocator(LIDO_LOCATOR_POSITION.getStorageAddress());
    }

    /**
    * @notice Returns the key values related to Consensus Layer side of the contract. It historically contains beacon
    * @return depositedValidators - number of deposited validators from Lido contract side
    * @return beaconValidators - number of Lido validators visible on Consensus Layer, reported by oracle
    * @return beaconBalance - total amount of ether on the Consensus Layer side (sum of all the balances of Lido validators)
    *
    * @dev `beacon` in naming still here for historical reasons
    */
    function getBeaconStat() external view returns (uint256 depositedValidators, uint256 beaconValidators, uint256 beaconBalance) {
        depositedValidators = DEPOSITED_VALIDATORS_POSITION.getStorageUint256();
        beaconValidators = CL_VALIDATORS_POSITION.getStorageUint256();
        beaconBalance = CL_BALANCE_POSITION.getStorageUint256();
    }

    /**
     * @dev Check that Lido allows depositing buffered ether to the consensus layer
     * Depends on the bunker state and protocol's pause state
     */
    function canDeposit() public view returns (bool) {
        return !_withdrawalQueue().isBunkerModeActive() && !isStopped();
    }

    /**
     * @dev Returns depositable ether amount.
     * Takes into account unfinalized stETH required by WithdrawalQueue
     */
    function getDepositableEther() public view returns (uint256) {
        uint256 bufferedEther = _getBufferedEther();
        uint256 withdrawalReserve = _withdrawalQueue().unfinalizedStETH();
        return bufferedEther > withdrawalReserve ? bufferedEther - withdrawalReserve : 0;
    }

    /**
     * @dev Invokes a deposit call to the Staking Router contract and updates buffered counters
     * @param _maxDepositsCount max deposits count
     * @param _stakingModuleId id of the staking module to be deposited
     * @param _depositCalldata module calldata
     */
    function deposit(uint256 _maxDepositsCount, uint256 _stakingModuleId, bytes _depositCalldata) external {
        ILidoLocator locator = getLidoLocator();

        require(msg.sender == locator.depositSecurityModule(), "APP_AUTH_DSM_FAILED");
        require(canDeposit(), "CAN_NOT_DEPOSIT");

        IStakingRouter stakingRouter = _stakingRouter();
        uint256 depositsCount = Math256.min(
            _maxDepositsCount,
            stakingRouter.getStakingModuleMaxDepositsCount(_stakingModuleId, getDepositableEther())
        );

        uint256 depositsValue;
        if (depositsCount > 0) {
            depositsValue = depositsCount.mul(DEPOSIT_SIZE);
            /// @dev firstly update the local state of the contract to prevent a reentrancy attack,
            ///     even if the StakingRouter is a trusted contract.
            BUFFERED_ETHER_POSITION.setStorageUint256(_getBufferedEther().sub(depositsValue));
            emit Unbuffered(depositsValue);

            uint256 newDepositedValidators = DEPOSITED_VALIDATORS_POSITION.getStorageUint256().add(depositsCount);
            DEPOSITED_VALIDATORS_POSITION.setStorageUint256(newDepositedValidators);
            emit DepositedValidatorsChanged(newDepositedValidators);
        }

        /// @dev transfer ether to StakingRouter and make a deposit at the same time. All the ether
        ///     sent to StakingRouter is counted as deposited. If StakingRouter can't deposit all
        ///     passed ether it MUST revert the whole transaction (never happens in normal circumstances)
        stakingRouter.deposit.value(depositsValue)(depositsCount, _stakingModuleId, _depositCalldata);
    }

    /// DEPRECATED PUBLIC METHODS

    /**
     * @notice Returns current withdrawal credentials of deposited validators
     * @dev DEPRECATED: use StakingRouter.getWithdrawalCredentials() instead
     */
    function getWithdrawalCredentials() external view returns (bytes32) {
        return _stakingRouter().getWithdrawalCredentials();
    }

    /**
     * @notice Returns legacy oracle
     * @dev DEPRECATED: the `AccountingOracle` superseded the old one
     */
    function getOracle() external view returns (address) {
        return getLidoLocator().legacyOracle();
    }

    /**
     * @notice Returns the treasury address
     * @dev DEPRECATED: use LidoLocator.treasury()
     */
    function getTreasury() external view returns (address) {
        return _treasury();
    }

    /**
     * @notice Returns current staking rewards fee rate
     * @dev DEPRECATED: Now fees information is stored in StakingRouter and
     * with higher precision. Use StakingRouter.getStakingFeeAggregateDistribution() instead.
     * @return totalFee total rewards fee in 1e4 precision (10000 is 100%). The value might be
     * inaccurate because the actual value is truncated here to 1e4 precision.
     */
    function getFee() external view returns (uint16 totalFee) {
        totalFee = _stakingRouter().getTotalFeeE4Precision();
    }

    /**
     * @notice Returns current fee distribution, values relative to the total fee (getFee())
     * @dev DEPRECATED: Now fees information is stored in StakingRouter and
     * with higher precision. Use StakingRouter.getStakingFeeAggregateDistribution() instead.
     * @return treasuryFeeBasisPoints return treasury fee in TOTAL_BASIS_POINTS (10000 is 100% fee) precision
     * @return insuranceFeeBasisPoints always returns 0 because the capability to send fees to
     * insurance from Lido contract is removed.
     * @return operatorsFeeBasisPoints return total fee for all operators of all staking modules in
     * TOTAL_BASIS_POINTS (10000 is 100% fee) precision.
     * Previously returned total fee of all node operators of NodeOperatorsRegistry (Curated staking module now)
     * The value might be inaccurate because the actual value is truncated here to 1e4 precision.
     */
    function getFeeDistribution()
        external view
        returns (
            uint16 treasuryFeeBasisPoints,
            uint16 insuranceFeeBasisPoints,
            uint16 operatorsFeeBasisPoints
        )
    {
        IStakingRouter stakingRouter = _stakingRouter();
        uint256 totalBasisPoints = stakingRouter.TOTAL_BASIS_POINTS();
        uint256 totalFee = stakingRouter.getTotalFeeE4Precision();
        (uint256 treasuryFeeBasisPointsAbs, uint256 operatorsFeeBasisPointsAbs) = stakingRouter
            .getStakingFeeAggregateDistributionE4Precision();

        insuranceFeeBasisPoints = 0;  // explicitly set to zero
        treasuryFeeBasisPoints = uint16((treasuryFeeBasisPointsAbs * totalBasisPoints) / totalFee);
        operatorsFeeBasisPoints = uint16((operatorsFeeBasisPointsAbs * totalBasisPoints) / totalFee);
    }

    /*
     * @dev updates Consensus Layer state snapshot according to the current report
     *
     * NB: conventions and assumptions
     *
     * `depositedValidators` are total amount of the **ever** deposited Lido validators
     * `_postClValidators` are total amount of the **ever** appeared on the CL side Lido validators
     *
     * i.e., exited Lido validators persist in the state, just with a different status
     */
    function _processClStateUpdate(
        uint256 _reportTimestamp,
        uint256 _preClValidators,
        uint256 _postClValidators,
        uint256 _postClBalance
    ) internal returns (uint256 preCLBalance) {
        uint256 depositedValidators = DEPOSITED_VALIDATORS_POSITION.getStorageUint256();
        require(_postClValidators <= depositedValidators, "REPORTED_MORE_DEPOSITED");
        require(_postClValidators >= _preClValidators, "REPORTED_LESS_VALIDATORS");

        if (_postClValidators > _preClValidators) {
            CL_VALIDATORS_POSITION.setStorageUint256(_postClValidators);
        }

        uint256 appearedValidators = _postClValidators - _preClValidators;
        preCLBalance = CL_BALANCE_POSITION.getStorageUint256();
        // Take into account the balance of the newly appeared validators
        preCLBalance = preCLBalance.add(appearedValidators.mul(DEPOSIT_SIZE));

        // Save the current CL balance and validators to
        // calculate rewards on the next push
        CL_BALANCE_POSITION.setStorageUint256(_postClBalance);

        emit CLValidatorsUpdated(_reportTimestamp, _preClValidators, _postClValidators);
    }

    /**
     * @dev collect ETH from ELRewardsVault and WithdrawalVault, then send to WithdrawalQueue
     */
    function _collectRewardsAndProcessWithdrawals(
        OracleReportContracts memory _contracts,
        uint256 _withdrawalsToWithdraw,
        uint256 _elRewardsToWithdraw,
        uint256[] _withdrawalFinalizationBatches,
        uint256 _simulatedShareRate,
        uint256 _etherToLockOnWithdrawalQueue
    ) internal {
        // withdraw execution layer rewards and put them to the buffer
        if (_elRewardsToWithdraw > 0) {
            ILidoExecutionLayerRewardsVault(_contracts.elRewardsVault).withdrawRewards(_elRewardsToWithdraw);
        }

        // withdraw withdrawals and put them to the buffer
        if (_withdrawalsToWithdraw > 0) {
            IWithdrawalVault(_contracts.withdrawalVault).withdrawWithdrawals(_withdrawalsToWithdraw);
        }

        // finalize withdrawals (send ether, assign shares for burning)
        if (_etherToLockOnWithdrawalQueue > 0) {
            IWithdrawalQueue withdrawalQueue = IWithdrawalQueue(_contracts.withdrawalQueue);
            withdrawalQueue.finalize.value(_etherToLockOnWithdrawalQueue)(
                _withdrawalFinalizationBatches[_withdrawalFinalizationBatches.length - 1],
                _simulatedShareRate
            );
        }

        uint256 postBufferedEther = _getBufferedEther()
            .add(_elRewardsToWithdraw) // Collected from ELVault
            .add(_withdrawalsToWithdraw) // Collected from WithdrawalVault
            .sub(_etherToLockOnWithdrawalQueue); // Sent to WithdrawalQueue

        _setBufferedEther(postBufferedEther);
    }

    /**
     * @dev return amount to lock on withdrawal queue and shares to burn
     * depending on the finalization batch parameters
     */
    function _calculateWithdrawals(
        OracleReportContracts memory _contracts,
        OracleReportedData memory _reportedData
    ) internal view returns (
        uint256 etherToLock, uint256 sharesToBurn
    ) {
        IWithdrawalQueue withdrawalQueue = IWithdrawalQueue(_contracts.withdrawalQueue);

        if (!withdrawalQueue.isPaused()) {
            IOracleReportSanityChecker(_contracts.oracleReportSanityChecker).checkWithdrawalQueueOracleReport(
                _reportedData.withdrawalFinalizationBatches[_reportedData.withdrawalFinalizationBatches.length - 1],
                _reportedData.reportTimestamp
            );

            (etherToLock, sharesToBurn) = withdrawalQueue.prefinalize(
                _reportedData.withdrawalFinalizationBatches,
                _reportedData.simulatedShareRate
            );
        }
    }

    /**
     * @dev calculate the amount of rewards and distribute it
     */
    function _processRewards(
        OracleReportContext memory _reportContext,
        uint256 _postCLBalance,
        uint256 _withdrawnWithdrawals,
        uint256 _withdrawnElRewards
    ) internal returns (uint256 sharesMintedAsFees) {
        uint256 postCLTotalBalance = _postCLBalance.add(_withdrawnWithdrawals);
        // Don’t mint/distribute any protocol fee on the non-profitable Lido oracle report
        // (when consensus layer balance delta is zero or negative).
        // See LIP-12 for details:
        // https://research.lido.fi/t/lip-12-on-chain-part-of-the-rewards-distribution-after-the-merge/1625
        if (postCLTotalBalance > _reportContext.preCLBalance) {
            uint256 consensusLayerRewards = postCLTotalBalance - _reportContext.preCLBalance;

            sharesMintedAsFees = _distributeFee(
                _reportContext.preTotalPooledEther,
                _reportContext.preTotalShares,
                consensusLayerRewards.add(_withdrawnElRewards)
            );
        }
    }

    /**
     * @dev Process user deposit, mints liquid tokens and increase the pool buffer
     * @param _referral address of referral.
     * @return amount of StETH shares generated
     */
    function _submit(address _referral) internal returns (uint256) {
        require(msg.value != 0, "ZERO_DEPOSIT");

        StakeLimitState.Data memory stakeLimitData = STAKING_STATE_POSITION.getStorageStakeLimitStruct();
        // There is an invariant that protocol pause also implies staking pause.
        // Thus, no need to check protocol pause explicitly.
        require(!stakeLimitData.isStakingPaused(), "STAKING_PAUSED");

        if (stakeLimitData.isStakingLimitSet()) {
            uint256 currentStakeLimit = stakeLimitData.calculateCurrentStakeLimit();

            require(msg.value <= currentStakeLimit, "STAKE_LIMIT");

            STAKING_STATE_POSITION.setStorageStakeLimitStruct(stakeLimitData.updatePrevStakeLimit(currentStakeLimit - msg.value));
        }

        uint256 sharesAmount = getSharesByPooledEth(msg.value);

        _mintShares(msg.sender, sharesAmount);

        _setBufferedEther(_getBufferedEther().add(msg.value));
        emit Submitted(msg.sender, msg.value, _referral);

        _emitTransferAfterMintingShares(msg.sender, sharesAmount);
        return sharesAmount;
    }

    /**
     * @dev Staking router rewards distribution.
     *
     * Corresponds to the return value of `IStakingRouter.newTotalPooledEtherForRewards()`
     * Prevents `stack too deep` issue.
     */
    struct StakingRewardsDistribution {
        address[] recipients;
        uint256[] moduleIds;
        uint96[] modulesFees;
        uint96 totalFee;
        uint256 precisionPoints;
    }

    /**
     * @dev Get staking rewards distribution from staking router.
     */
    function _getStakingRewardsDistribution() internal view returns (
        StakingRewardsDistribution memory ret,
        IStakingRouter router
    ) {
        router = _stakingRouter();

        (
            ret.recipients,
            ret.moduleIds,
            ret.modulesFees,
            ret.totalFee,
            ret.precisionPoints
        ) = router.getStakingRewardsDistribution();

        require(ret.recipients.length == ret.modulesFees.length, "WRONG_RECIPIENTS_INPUT");
        require(ret.moduleIds.length == ret.modulesFees.length, "WRONG_MODULE_IDS_INPUT");
    }

    /**
     * @dev Distributes fee portion of the rewards by minting and distributing corresponding amount of liquid tokens.
     * @param _preTotalPooledEther Total supply before report-induced changes applied
     * @param _preTotalShares Total shares before report-induced changes applied
     * @param _totalRewards Total rewards accrued both on the Execution Layer and the Consensus Layer sides in wei.
     */
    function _distributeFee(
        uint256 _preTotalPooledEther,
        uint256 _preTotalShares,
        uint256 _totalRewards
    ) internal returns (uint256 sharesMintedAsFees) {
        // We need to take a defined percentage of the reported reward as a fee, and we do
        // this by minting new token shares and assigning them to the fee recipients (see
        // StETH docs for the explanation of the shares mechanics). The staking rewards fee
        // is defined in basis points (1 basis point is equal to 0.01%, 10000 (TOTAL_BASIS_POINTS) is 100%).
        //
        // Since we are increasing totalPooledEther by _totalRewards (totalPooledEtherWithRewards),
        // the combined cost of all holders' shares has became _totalRewards StETH tokens more,
        // effectively splitting the reward between each token holder proportionally to their token share.
        //
        // Now we want to mint new shares to the fee recipient, so that the total cost of the
        // newly-minted shares exactly corresponds to the fee taken:
        //
        // totalPooledEtherWithRewards = _preTotalPooledEther + _totalRewards
        // shares2mint * newShareCost = (_totalRewards * totalFee) / PRECISION_POINTS
        // newShareCost = totalPooledEtherWithRewards / (_preTotalShares + shares2mint)
        //
        // which follows to:
        //
        //                        _totalRewards * totalFee * _preTotalShares
        // shares2mint = --------------------------------------------------------------
        //                 (totalPooledEtherWithRewards * PRECISION_POINTS) - (_totalRewards * totalFee)
        //
        // The effect is that the given percentage of the reward goes to the fee recipient, and
        // the rest of the reward is distributed between token holders proportionally to their
        // token shares.

        (
            StakingRewardsDistribution memory rewardsDistribution,
            IStakingRouter router
        ) = _getStakingRewardsDistribution();

        if (rewardsDistribution.totalFee > 0) {
            uint256 totalPooledEtherWithRewards = _preTotalPooledEther.add(_totalRewards);

            sharesMintedAsFees =
                _totalRewards.mul(rewardsDistribution.totalFee).mul(_preTotalShares).div(
                    totalPooledEtherWithRewards.mul(
                        rewardsDistribution.precisionPoints
                    ).sub(_totalRewards.mul(rewardsDistribution.totalFee))
                );

            _mintShares(address(this), sharesMintedAsFees);

            (uint256[] memory moduleRewards, uint256 totalModuleRewards) =
                _transferModuleRewards(
                    rewardsDistribution.recipients,
                    rewardsDistribution.modulesFees,
                    rewardsDistribution.totalFee,
                    sharesMintedAsFees
                );

            _transferTreasuryRewards(sharesMintedAsFees.sub(totalModuleRewards));

            router.reportRewardsMinted(
                rewardsDistribution.moduleIds,
                moduleRewards
            );
        }
    }

    function _transferModuleRewards(
        address[] memory recipients,
        uint96[] memory modulesFees,
        uint256 totalFee,
        uint256 totalRewards
    ) internal returns (uint256[] memory moduleRewards, uint256 totalModuleRewards) {
        moduleRewards = new uint256[](recipients.length);

        for (uint256 i; i < recipients.length; ++i) {
            if (modulesFees[i] > 0) {
                uint256 iModuleRewards = totalRewards.mul(modulesFees[i]).div(totalFee);
                moduleRewards[i] = iModuleRewards;
                _transferShares(address(this), recipients[i], iModuleRewards);
                _emitTransferAfterMintingShares(recipients[i], iModuleRewards);
                totalModuleRewards = totalModuleRewards.add(iModuleRewards);
            }
        }
    }

    function _transferTreasuryRewards(uint256 treasuryReward) internal {
        address treasury = _treasury();
        _transferShares(address(this), treasury, treasuryReward);
        _emitTransferAfterMintingShares(treasury, treasuryReward);
    }

    /**
     * @dev Gets the amount of Ether temporary buffered on this contract balance
     */
    function _getBufferedEther() internal view returns (uint256) {
        return BUFFERED_ETHER_POSITION.getStorageUint256();
    }

    function _setBufferedEther(uint256 _newBufferedEther) internal {
        BUFFERED_ETHER_POSITION.setStorageUint256(_newBufferedEther);
    }

    /// @dev Calculates and returns the total base balance (multiple of 32) of validators in transient state,
    ///     i.e. submitted to the official Deposit contract but not yet visible in the CL state.
    /// @return transient balance in wei (1e-18 Ether)
    function _getTransientBalance() internal view returns (uint256) {
        uint256 depositedValidators = DEPOSITED_VALIDATORS_POSITION.getStorageUint256();
        uint256 clValidators = CL_VALIDATORS_POSITION.getStorageUint256();
        // clValidators can never be less than deposited ones.
        assert(depositedValidators >= clValidators);
        return (depositedValidators - clValidators).mul(DEPOSIT_SIZE);
    }

    /**
     * @dev Gets the total amount of Ether controlled by the system
     * @return total balance in wei
     */
    function _getTotalPooledEther() internal view returns (uint256) {
        return _getBufferedEther()
            .add(CL_BALANCE_POSITION.getStorageUint256())
            .add(_getTransientBalance());
    }

    function _pauseStaking() internal {
        STAKING_STATE_POSITION.setStorageStakeLimitStruct(
            STAKING_STATE_POSITION.getStorageStakeLimitStruct().setStakeLimitPauseState(true)
        );

        emit StakingPaused();
    }

    function _resumeStaking() internal {
        STAKING_STATE_POSITION.setStorageStakeLimitStruct(
            STAKING_STATE_POSITION.getStorageStakeLimitStruct().setStakeLimitPauseState(false)
        );

        emit StakingResumed();
    }

    function _getCurrentStakeLimit(StakeLimitState.Data memory _stakeLimitData) internal view returns (uint256) {
        if (_stakeLimitData.isStakingPaused()) {
            return 0;
        }
        if (!_stakeLimitData.isStakingLimitSet()) {
            return uint256(-1);
        }

        return _stakeLimitData.calculateCurrentStakeLimit();
    }

    /**
     * @dev Size-efficient analog of the `auth(_role)` modifier
     * @param _role Permission name
     */
    function _auth(bytes32 _role) internal view {
        require(canPerform(msg.sender, _role, new uint256[](0)), "APP_AUTH_FAILED");
    }

    /**
     * @dev Intermediate data structure for `_handleOracleReport`
     * Helps to overcome `stack too deep` issue.
     */
    struct OracleReportContext {
        uint256 preCLValidators;
        uint256 preCLBalance;
        uint256 preTotalPooledEther;
        uint256 preTotalShares;
        uint256 etherToLockOnWithdrawalQueue;
        uint256 sharesToBurnFromWithdrawalQueue;
        uint256 simulatedSharesToBurn;
        uint256 sharesToBurn;
        uint256 sharesMintedAsFees;
    }

    /**
     * @dev Handle oracle report method operating with the data-packed structs
     * Using structs helps to overcome 'stack too deep' issue.
     *
     * The method updates the protocol's accounting state.
     * Key steps:
     * 1. Take a snapshot of the current (pre-) state
     * 2. Pass the report data to sanity checker (reverts if malformed)
     * 3. Pre-calculate the ether to lock for withdrawal queue and shares to be burnt
     * 4. Pass the accounting values to sanity checker to smoothen positive token rebase
     *    (i.e., postpone the extra rewards to be applied during the next rounds)
     * 5. Invoke finalization of the withdrawal requests
     * 6. Burn excess shares within the allowed limit (can postpone some shares to be burnt later)
     * 7. Distribute protocol fee (treasury & node operators)
     * 8. Complete token rebase by informing observers (emit an event and call the external receivers if any)
     * 9. Sanity check for the provided simulated share rate
     */
    function _handleOracleReport(OracleReportedData memory _reportedData) internal returns (uint256[4]) {
        OracleReportContracts memory contracts = _loadOracleReportContracts();

        require(msg.sender == contracts.accountingOracle, "APP_AUTH_FAILED");
        require(_reportedData.reportTimestamp <= block.timestamp, "INVALID_REPORT_TIMESTAMP");

        OracleReportContext memory reportContext;

        // Step 1.
        // Take a snapshot of the current (pre-) state
        reportContext.preTotalPooledEther = _getTotalPooledEther();
        reportContext.preTotalShares = _getTotalShares();
        reportContext.preCLValidators = CL_VALIDATORS_POSITION.getStorageUint256();
        reportContext.preCLBalance = _processClStateUpdate(
            _reportedData.reportTimestamp,
            reportContext.preCLValidators,
            _reportedData.clValidators,
            _reportedData.postCLBalance
        );

        // Step 2.
        // Pass the report data to sanity checker (reverts if malformed)
        _checkAccountingOracleReport(contracts, _reportedData, reportContext);

        // Step 3.
        // Pre-calculate the ether to lock for withdrawal queue and shares to be burnt
        // due to withdrawal requests to finalize
        if (_reportedData.withdrawalFinalizationBatches.length != 0) {
            (
                reportContext.etherToLockOnWithdrawalQueue,
                reportContext.sharesToBurnFromWithdrawalQueue
            ) = _calculateWithdrawals(contracts, _reportedData);

            if (reportContext.sharesToBurnFromWithdrawalQueue > 0) {
                IBurner(contracts.burner).requestBurnShares(
                    contracts.withdrawalQueue,
                    reportContext.sharesToBurnFromWithdrawalQueue
                );
            }
        }

        // Step 4.
        // Pass the accounting values to sanity checker to smoothen positive token rebase

        uint256 withdrawals;
        uint256 elRewards;
        (
            withdrawals, elRewards, reportContext.simulatedSharesToBurn, reportContext.sharesToBurn
        ) = IOracleReportSanityChecker(contracts.oracleReportSanityChecker).smoothenTokenRebase(
            reportContext.preTotalPooledEther,
            reportContext.preTotalShares,
            reportContext.preCLBalance,
            _reportedData.postCLBalance,
            _reportedData.withdrawalVaultBalance,
            _reportedData.elRewardsVaultBalance,
            _reportedData.sharesRequestedToBurn,
            reportContext.etherToLockOnWithdrawalQueue,
            reportContext.sharesToBurnFromWithdrawalQueue
        );

        // Step 5.
        // Invoke finalization of the withdrawal requests (send ether to withdrawal queue, assign shares to be burnt)
        _collectRewardsAndProcessWithdrawals(
            contracts,
            withdrawals,
            elRewards,
            _reportedData.withdrawalFinalizationBatches,
            _reportedData.simulatedShareRate,
            reportContext.etherToLockOnWithdrawalQueue
        );

        emit ETHDistributed(
            _reportedData.reportTimestamp,
            reportContext.preCLBalance,
            _reportedData.postCLBalance,
            withdrawals,
            elRewards,
            _getBufferedEther()
        );

        // Step 6.
        // Burn the previously requested shares
        if (reportContext.sharesToBurn > 0) {
            IBurner(contracts.burner).commitSharesToBurn(reportContext.sharesToBurn);
            _burnShares(contracts.burner, reportContext.sharesToBurn);
        }

        // Step 7.
        // Distribute protocol fee (treasury & node operators)
        reportContext.sharesMintedAsFees = _processRewards(
            reportContext,
            _reportedData.postCLBalance,
            withdrawals,
            elRewards
        );

        // Step 8.
        // Complete token rebase by informing observers (emit an event and call the external receivers if any)
        (
            uint256 postTotalShares,
            uint256 postTotalPooledEther
        ) = _completeTokenRebase(
            _reportedData,
            reportContext,
            IPostTokenRebaseReceiver(contracts.postTokenRebaseReceiver)
        );

        // Step 9. Sanity check for the provided simulated share rate
        if (_reportedData.withdrawalFinalizationBatches.length != 0) {
            IOracleReportSanityChecker(contracts.oracleReportSanityChecker).checkSimulatedShareRate(
                postTotalPooledEther,
                postTotalShares,
                reportContext.etherToLockOnWithdrawalQueue,
                reportContext.sharesToBurn.sub(reportContext.simulatedSharesToBurn),
                _reportedData.simulatedShareRate
            );
        }

        return [postTotalPooledEther, postTotalShares, withdrawals, elRewards];
    }

    /**
     * @dev Pass the provided oracle data to the sanity checker contract
     * Works with structures to overcome `stack too deep`
     */
    function _checkAccountingOracleReport(
        OracleReportContracts memory _contracts,
        OracleReportedData memory _reportedData,
        OracleReportContext memory _reportContext
    ) internal view {
        IOracleReportSanityChecker(_contracts.oracleReportSanityChecker).checkAccountingOracleReport(
            _reportedData.timeElapsed,
            _reportContext.preCLBalance,
            _reportedData.postCLBalance,
            _reportedData.withdrawalVaultBalance,
            _reportedData.elRewardsVaultBalance,
            _reportedData.sharesRequestedToBurn,
            _reportContext.preCLValidators,
            _reportedData.clValidators
        );
    }

    /**
     * @dev Notify observers about the completed token rebase.
     * Emit events and call external receivers.
     */
    function _completeTokenRebase(
        OracleReportedData memory _reportedData,
        OracleReportContext memory _reportContext,
        IPostTokenRebaseReceiver _postTokenRebaseReceiver
    ) internal returns (uint256 postTotalShares, uint256 postTotalPooledEther) {
        postTotalShares = _getTotalShares();
        postTotalPooledEther = _getTotalPooledEther();

        if (_postTokenRebaseReceiver != address(0)) {
            _postTokenRebaseReceiver.handlePostTokenRebase(
                _reportedData.reportTimestamp,
                _reportedData.timeElapsed,
                _reportContext.preTotalShares,
                _reportContext.preTotalPooledEther,
                postTotalShares,
                postTotalPooledEther,
                _reportContext.sharesMintedAsFees
            );
        }

        emit TokenRebased(
            _reportedData.reportTimestamp,
            _reportedData.timeElapsed,
            _reportContext.preTotalShares,
            _reportContext.preTotalPooledEther,
            postTotalShares,
            postTotalPooledEther,
            _reportContext.sharesMintedAsFees
        );
    }

    /**
     * @dev Load the contracts used for `handleOracleReport` internally.
     */
    function _loadOracleReportContracts() internal view returns (OracleReportContracts memory ret) {
        (
            ret.accountingOracle,
            ret.elRewardsVault,
            ret.oracleReportSanityChecker,
            ret.burner,
            ret.withdrawalQueue,
            ret.withdrawalVault,
            ret.postTokenRebaseReceiver
        ) = getLidoLocator().oracleReportComponentsForLido();
    }

    function _stakingRouter() internal view returns (IStakingRouter) {
        return IStakingRouter(getLidoLocator().stakingRouter());
    }

    function _withdrawalQueue() internal view returns (IWithdrawalQueue) {
        return IWithdrawalQueue(getLidoLocator().withdrawalQueue());
    }

    function _treasury() internal view returns (address) {
        return getLidoLocator().treasury();
    }

    /**
     * @notice Mints shares on behalf of 0xdead address,
     * the shares amount is equal to the contract's balance.     *
     *
     * Allows to get rid of zero checks for `totalShares` and `totalPooledEther`
     * and overcome corner cases.
     *
     * NB: reverts if the current contract's balance is zero.
     *
     * @dev must be invoked before using the token
     */
    function _bootstrapInitialHolder() internal {
        uint256 balance = address(this).balance;
        assert(balance != 0);

        if (_getTotalShares() == 0) {
            // if protocol is empty bootstrap it with the contract's balance
            // address(0xdead) is a holder for initial shares
            _setBufferedEther(balance);
            // emitting `Submitted` before Transfer events to preserver events order in tx
            emit Submitted(INITIAL_TOKEN_HOLDER, balance, 0);
            _mintInitialShares(balance);
        }
    }
}
        

// Inspired by AdEx (https://github.com/AdExNetwork/adex-protocol-eth/blob/b9df617829661a7518ee10f4cb6c4108659dd6d5/contracts/libs/SafeERC20.sol)
// and 0x (https://github.com/0xProject/0x-monorepo/blob/737d1dc54d72872e24abce5a1dbe1b66d35fa21a/contracts/protocol/contracts/protocol/AssetProxy/ERC20Proxy.sol#L143)

pragma solidity ^0.4.24;

import "../lib/token/ERC20.sol";


library SafeERC20 {
    // Before 0.5, solidity has a mismatch between `address.transfer()` and `token.transfer()`:
    // https://github.com/ethereum/solidity/issues/3544
    bytes4 private constant TRANSFER_SELECTOR = 0xa9059cbb;

    string private constant ERROR_TOKEN_BALANCE_REVERTED = "SAFE_ERC_20_BALANCE_REVERTED";
    string private constant ERROR_TOKEN_ALLOWANCE_REVERTED = "SAFE_ERC_20_ALLOWANCE_REVERTED";

    function invokeAndCheckSuccess(address _addr, bytes memory _calldata)
        private
        returns (bool)
    {
        bool ret;
        assembly {
            let ptr := mload(0x40)    // free memory pointer

            let success := call(
                gas,                  // forward all gas
                _addr,                // address
                0,                    // no value
                add(_calldata, 0x20), // calldata start
                mload(_calldata),     // calldata length
                ptr,                  // write output over free memory
                0x20                  // uint256 return
            )

            if gt(success, 0) {
                // Check number of bytes returned from last function call
                switch returndatasize

                // No bytes returned: assume success
                case 0 {
                    ret := 1
                }

                // 32 bytes returned: check if non-zero
                case 0x20 {
                    // Only return success if returned data was true
                    // Already have output in ptr
                    ret := eq(mload(ptr), 1)
                }

                // Not sure what was returned: don't mark as success
                default { }
            }
        }
        return ret;
    }

    function staticInvoke(address _addr, bytes memory _calldata)
        private
        view
        returns (bool, uint256)
    {
        bool success;
        uint256 ret;
        assembly {
            let ptr := mload(0x40)    // free memory pointer

            success := staticcall(
                gas,                  // forward all gas
                _addr,                // address
                add(_calldata, 0x20), // calldata start
                mload(_calldata),     // calldata length
                ptr,                  // write output over free memory
                0x20                  // uint256 return
            )

            if gt(success, 0) {
                ret := mload(ptr)
            }
        }
        return (success, ret);
    }

    /**
    * @dev Same as a standards-compliant ERC20.transfer() that never reverts (returns false).
    *      Note that this makes an external call to the token.
    */
    function safeTransfer(ERC20 _token, address _to, uint256 _amount) internal returns (bool) {
        bytes memory transferCallData = abi.encodeWithSelector(
            TRANSFER_SELECTOR,
            _to,
            _amount
        );
        return invokeAndCheckSuccess(_token, transferCallData);
    }

    /**
    * @dev Same as a standards-compliant ERC20.transferFrom() that never reverts (returns false).
    *      Note that this makes an external call to the token.
    */
    function safeTransferFrom(ERC20 _token, address _from, address _to, uint256 _amount) internal returns (bool) {
        bytes memory transferFromCallData = abi.encodeWithSelector(
            _token.transferFrom.selector,
            _from,
            _to,
            _amount
        );
        return invokeAndCheckSuccess(_token, transferFromCallData);
    }

    /**
    * @dev Same as a standards-compliant ERC20.approve() that never reverts (returns false).
    *      Note that this makes an external call to the token.
    */
    function safeApprove(ERC20 _token, address _spender, uint256 _amount) internal returns (bool) {
        bytes memory approveCallData = abi.encodeWithSelector(
            _token.approve.selector,
            _spender,
            _amount
        );
        return invokeAndCheckSuccess(_token, approveCallData);
    }

    /**
    * @dev Static call into ERC20.balanceOf().
    * Reverts if the call fails for some reason (should never fail).
    */
    function staticBalanceOf(ERC20 _token, address _owner) internal view returns (uint256) {
        bytes memory balanceOfCallData = abi.encodeWithSelector(
            _token.balanceOf.selector,
            _owner
        );

        (bool success, uint256 tokenBalance) = staticInvoke(_token, balanceOfCallData);
        require(success, ERROR_TOKEN_BALANCE_REVERTED);

        return tokenBalance;
    }

    /**
    * @dev Static call into ERC20.allowance().
    * Reverts if the call fails for some reason (should never fail).
    */
    function staticAllowance(ERC20 _token, address _owner, address _spender) internal view returns (uint256) {
        bytes memory allowanceCallData = abi.encodeWithSelector(
            _token.allowance.selector,
            _owner,
            _spender
        );

        (bool success, uint256 allowance) = staticInvoke(_token, allowanceCallData);
        require(success, ERROR_TOKEN_ALLOWANCE_REVERTED);

        return allowance;
    }

    /**
    * @dev Static call into ERC20.totalSupply().
    * Reverts if the call fails for some reason (should never fail).
    */
    function staticTotalSupply(ERC20 _token) internal view returns (uint256) {
        bytes memory totalSupplyCallData = abi.encodeWithSelector(_token.totalSupply.selector);

        (bool success, uint256 totalSupply) = staticInvoke(_token, totalSupplyCallData);
        require(success, ERROR_TOKEN_ALLOWANCE_REVERTED);

        return totalSupply;
    }
}
          

/*
 * SPDX-License-Identifier:    MIT
 */

pragma solidity ^0.4.24;


contract ACLSyntaxSugar {
    function arr() internal pure returns (uint256[]) {
        return new uint256[](0);
    }

    function arr(bytes32 _a) internal pure returns (uint256[] r) {
        return arr(uint256(_a));
    }

    function arr(bytes32 _a, bytes32 _b) internal pure returns (uint256[] r) {
        return arr(uint256(_a), uint256(_b));
    }

    function arr(address _a) internal pure returns (uint256[] r) {
        return arr(uint256(_a));
    }

    function arr(address _a, address _b) internal pure returns (uint256[] r) {
        return arr(uint256(_a), uint256(_b));
    }

    function arr(address _a, uint256 _b, uint256 _c) internal pure returns (uint256[] r) {
        return arr(uint256(_a), _b, _c);
    }

    function arr(address _a, uint256 _b, uint256 _c, uint256 _d) internal pure returns (uint256[] r) {
        return arr(uint256(_a), _b, _c, _d);
    }

    function arr(address _a, uint256 _b) internal pure returns (uint256[] r) {
        return arr(uint256(_a), uint256(_b));
    }

    function arr(address _a, address _b, uint256 _c, uint256 _d, uint256 _e) internal pure returns (uint256[] r) {
        return arr(uint256(_a), uint256(_b), _c, _d, _e);
    }

    function arr(address _a, address _b, address _c) internal pure returns (uint256[] r) {
        return arr(uint256(_a), uint256(_b), uint256(_c));
    }

    function arr(address _a, address _b, uint256 _c) internal pure returns (uint256[] r) {
        return arr(uint256(_a), uint256(_b), uint256(_c));
    }

    function arr(uint256 _a) internal pure returns (uint256[] r) {
        r = new uint256[](1);
        r[0] = _a;
    }

    function arr(uint256 _a, uint256 _b) internal pure returns (uint256[] r) {
        r = new uint256[](2);
        r[0] = _a;
        r[1] = _b;
    }

    function arr(uint256 _a, uint256 _b, uint256 _c) internal pure returns (uint256[] r) {
        r = new uint256[](3);
        r[0] = _a;
        r[1] = _b;
        r[2] = _c;
    }

    function arr(uint256 _a, uint256 _b, uint256 _c, uint256 _d) internal pure returns (uint256[] r) {
        r = new uint256[](4);
        r[0] = _a;
        r[1] = _b;
        r[2] = _c;
        r[3] = _d;
    }

    function arr(uint256 _a, uint256 _b, uint256 _c, uint256 _d, uint256 _e) internal pure returns (uint256[] r) {
        r = new uint256[](5);
        r[0] = _a;
        r[1] = _b;
        r[2] = _c;
        r[3] = _d;
        r[4] = _e;
    }
}


contract ACLHelpers {
    function decodeParamOp(uint256 _x) internal pure returns (uint8 b) {
        return uint8(_x >> (8 * 30));
    }

    function decodeParamId(uint256 _x) internal pure returns (uint8 b) {
        return uint8(_x >> (8 * 31));
    }

    function decodeParamsList(uint256 _x) internal pure returns (uint32 a, uint32 b, uint32 c) {
        a = uint32(_x);
        b = uint32(_x >> (8 * 4));
        c = uint32(_x >> (8 * 8));
    }
}
          

/*
 * SPDX-License-Identifier:    MIT
 */

pragma solidity ^0.4.24;


interface IVaultRecoverable {
    event RecoverToVault(address indexed vault, address indexed token, uint256 amount);

    function transferToVault(address token) external;

    function allowRecoverability(address token) external view returns (bool);
    function getRecoveryVault() external view returns (address);
}
          

pragma solidity ^0.4.24;


library ConversionHelpers {
    string private constant ERROR_IMPROPER_LENGTH = "CONVERSION_IMPROPER_LENGTH";

    function dangerouslyCastUintArrayToBytes(uint256[] memory _input) internal pure returns (bytes memory output) {
        // Force cast the uint256[] into a bytes array, by overwriting its length
        // Note that the bytes array doesn't need to be initialized as we immediately overwrite it
        // with the input and a new length. The input becomes invalid from this point forward.
        uint256 byteLength = _input.length * 32;
        assembly {
            output := _input
            mstore(output, byteLength)
        }
    }

    function dangerouslyCastBytesToUintArray(bytes memory _input) internal pure returns (uint256[] memory output) {
        // Force cast the bytes array into a uint256[], by overwriting its length
        // Note that the uint256[] doesn't need to be initialized as we immediately overwrite it
        // with the input and a new length. The input becomes invalid from this point forward.
        uint256 intsLength = _input.length / 32;
        require(_input.length == intsLength * 32, ERROR_IMPROPER_LENGTH);

        assembly {
            output := _input
            mstore(output, intsLength)
        }
    }
}
          

/*
 * SPDX-License-Identifier:    MIT
 */

pragma solidity ^0.4.24;

import "../acl/IACL.sol";
import "../common/IVaultRecoverable.sol";


interface IKernelEvents {
    event SetApp(bytes32 indexed namespace, bytes32 indexed appId, address app);
}


// This should be an interface, but interfaces can't inherit yet :(
contract IKernel is IKernelEvents, IVaultRecoverable {
    function acl() public view returns (IACL);
    function hasPermission(address who, address where, bytes32 what, bytes how) public view returns (bool);

    function setApp(bytes32 namespace, bytes32 appId, address app) public;
    function getApp(bytes32 namespace, bytes32 appId) public view returns (address);
}
          

/*
 * SPDX-License-Identifier:    MIT
 */

pragma solidity ^0.4.24;


interface IACL {
    function initialize(address permissionsCreator) external;

    // TODO: this should be external
    // See https://github.com/ethereum/solidity/issues/4832
    function hasPermission(address who, address where, bytes32 what, bytes how) public view returns (bool);
}
          

/*
 * SPDX-License-Identifier:    MIT
 */

pragma solidity ^0.4.24;


interface IEVMScriptExecutor {
    function execScript(bytes script, bytes input, address[] blacklist) external returns (bytes);
    function executorType() external pure returns (bytes32);
}
          

/*
 * SPDX-License-Identifier:    MIT
 */

pragma solidity ^0.4.24;

import "./AppStorage.sol";
import "../acl/ACLSyntaxSugar.sol";
import "../common/Autopetrified.sol";
import "../common/ConversionHelpers.sol";
import "../common/ReentrancyGuard.sol";
import "../common/VaultRecoverable.sol";
import "../evmscript/EVMScriptRunner.sol";


// Contracts inheriting from AragonApp are, by default, immediately petrified upon deployment so
// that they can never be initialized.
// Unless overriden, this behaviour enforces those contracts to be usable only behind an AppProxy.
// ReentrancyGuard, EVMScriptRunner, and ACLSyntaxSugar are not directly used by this contract, but
// are included so that they are automatically usable by subclassing contracts
contract AragonApp is AppStorage, Autopetrified, VaultRecoverable, ReentrancyGuard, EVMScriptRunner, ACLSyntaxSugar {
    string private constant ERROR_AUTH_FAILED = "APP_AUTH_FAILED";

    modifier auth(bytes32 _role) {
        require(canPerform(msg.sender, _role, new uint256[](0)), ERROR_AUTH_FAILED);
        _;
    }

    modifier authP(bytes32 _role, uint256[] _params) {
        require(canPerform(msg.sender, _role, _params), ERROR_AUTH_FAILED);
        _;
    }

    /**
    * @dev Check whether an action can be performed by a sender for a particular role on this app
    * @param _sender Sender of the call
    * @param _role Role on this app
    * @param _params Permission params for the role
    * @return Boolean indicating whether the sender has the permissions to perform the action.
    *         Always returns false if the app hasn't been initialized yet.
    */
    function canPerform(address _sender, bytes32 _role, uint256[] _params) public view returns (bool) {
        if (!hasInitialized()) {
            return false;
        }

        IKernel linkedKernel = kernel();
        if (address(linkedKernel) == address(0)) {
            return false;
        }

        return linkedKernel.hasPermission(
            _sender,
            address(this),
            _role,
            ConversionHelpers.dangerouslyCastUintArrayToBytes(_params)
        );
    }

    /**
    * @dev Get the recovery vault for the app
    * @return Recovery vault address for the app
    */
    function getRecoveryVault() public view returns (address) {
        // Funds recovery via a vault is only available when used with a kernel
        return kernel().getRecoveryVault(); // if kernel is not set, it will revert
    }
}
          

/*
 * SPDX-License-Identifier:    MIT
 */

pragma solidity ^0.4.24;

import "../common/UnstructuredStorage.sol";
import "../kernel/IKernel.sol";


contract AppStorage {
    using UnstructuredStorage for bytes32;

    /* Hardcoded constants to save gas
    bytes32 internal constant KERNEL_POSITION = keccak256("aragonOS.appStorage.kernel");
    bytes32 internal constant APP_ID_POSITION = keccak256("aragonOS.appStorage.appId");
    */
    bytes32 internal constant KERNEL_POSITION = 0x4172f0f7d2289153072b0a6ca36959e0cbe2efc3afe50fc81636caa96338137b;
    bytes32 internal constant APP_ID_POSITION = 0xd625496217aa6a3453eecb9c3489dc5a53e6c67b444329ea2b2cbc9ff547639b;

    function kernel() public view returns (IKernel) {
        return IKernel(KERNEL_POSITION.getStorageAddress());
    }

    function appId() public view returns (bytes32) {
        return APP_ID_POSITION.getStorageBytes32();
    }

    function setKernel(IKernel _kernel) internal {
        KERNEL_POSITION.setStorageAddress(address(_kernel));
    }

    function setAppId(bytes32 _appId) internal {
        APP_ID_POSITION.setStorageBytes32(_appId);
    }
}
          

// SPDX-FileCopyrightText: 2023 Lido <info@lido.fi>
// SPDX-License-Identifier: GPL-3.0

// See contracts/COMPILERS.md
// solhint-disable-next-line
pragma solidity >=0.4.24 <0.9.0;

interface ILidoLocator {
    function accountingOracle() external view returns(address);
    function depositSecurityModule() external view returns(address);
    function elRewardsVault() external view returns(address);
    function legacyOracle() external view returns(address);
    function lido() external view returns(address);
    function oracleReportSanityChecker() external view returns(address);
    function burner() external view returns(address);
    function stakingRouter() external view returns(address);
    function treasury() external view returns(address);
    function validatorsExitBusOracle() external view returns(address);
    function withdrawalQueue() external view returns(address);
    function withdrawalVault() external view returns(address);
    function postTokenRebaseReceiver() external view returns(address);
    function oracleDaemonConfig() external view returns(address);
    function coreComponents() external view returns(
        address elRewardsVault,
        address oracleReportSanityChecker,
        address stakingRouter,
        address treasury,
        address withdrawalQueue,
        address withdrawalVault
    );
    function oracleReportComponentsForLido() external view returns(
        address accountingOracle,
        address elRewardsVault,
        address oracleReportSanityChecker,
        address burner,
        address withdrawalQueue,
        address withdrawalVault,
        address postTokenRebaseReceiver
    );
}
          

pragma solidity ^0.4.24;


library Uint256Helpers {
    uint256 private constant MAX_UINT64 = uint64(-1);

    string private constant ERROR_NUMBER_TOO_BIG = "UINT64_NUMBER_TOO_BIG";

    function toUint64(uint256 a) internal pure returns (uint64) {
        require(a <= MAX_UINT64, ERROR_NUMBER_TOO_BIG);
        return uint64(a);
    }
}
          

// SPDX-FileCopyrightText: 2023 Lido <info@lido.fi>
// SPDX-License-Identifier: GPL-3.0
pragma solidity 0.4.24;

import "@aragon/os/contracts/common/UnstructuredStorage.sol";

/**
 * @title Adapted code of /contracts/0.8.9/utils/Versioned.sol
 *
 * This contract contains only core part of original Versioned.sol
 * to reduce contract size
 */
contract Versioned {
    using UnstructuredStorage for bytes32;

    event ContractVersionSet(uint256 version);

    /// @dev Storage slot: uint256 version
    /// Version of the initialized contract storage.
    /// The version stored in CONTRACT_VERSION_POSITION equals to:
    /// - 0 right after the deployment, before an initializer is invoked (and only at that moment);
    /// - N after calling initialize(), where N is the initially deployed contract version;
    /// - N after upgrading contract by calling finalizeUpgrade_vN().
    bytes32 internal constant CONTRACT_VERSION_POSITION =
        0x4dd0f6662ba1d6b081f08b350f5e9a6a7b15cf586926ba66f753594928fa64a6; // keccak256("lido.Versioned.contractVersion");

    uint256 internal constant PETRIFIED_VERSION_MARK = uint256(-1);

    constructor() public {
        // lock version in the implementation's storage to prevent initialization
        CONTRACT_VERSION_POSITION.setStorageUint256(PETRIFIED_VERSION_MARK);
    }

    /// @notice Returns the current contract version.
    function getContractVersion() public view returns (uint256) {
        return CONTRACT_VERSION_POSITION.getStorageUint256();
    }

    function _checkContractVersion(uint256 version) internal view {
        require(version == getContractVersion(), "UNEXPECTED_CONTRACT_VERSION");
    }

    function _setContractVersion(uint256 version) internal {
        CONTRACT_VERSION_POSITION.setStorageUint256(version);
        emit ContractVersionSet(version);
    }
}
          

// SPDX-FileCopyrightText: 2023 Lido <info@lido.fi>
// SPDX-License-Identifier: GPL-3.0

// See contracts/COMPILERS.md
// solhint-disable-next-line
pragma solidity >=0.4.24 <0.9.0;

interface IBurner {
    /**
     * Commit cover/non-cover burning requests and logs cover/non-cover shares amount just burnt.
     *
     * NB: The real burn enactment to be invoked after the call (via internal Lido._burnShares())
     */
    function commitSharesToBurn(uint256 _stETHSharesToBurn) external;

    /**
     * Request burn shares
     */
    function requestBurnShares(address _from, uint256 _sharesAmount) external;

    /**
      * Returns the current amount of shares locked on the contract to be burnt.
      */
    function getSharesRequestedToBurn() external view returns (uint256 coverShares, uint256 nonCoverShares);

    /**
      * Returns the total cover shares ever burnt.
      */
    function getCoverSharesBurnt() external view returns (uint256);

    /**
      * Returns the total non-cover shares ever burnt.
      */
    function getNonCoverSharesBurnt() external view returns (uint256);
}
          

/*
 * SPDX-License-Identifier:    MIT
 */

pragma solidity ^0.4.24;

import "../common/UnstructuredStorage.sol";


contract ReentrancyGuard {
    using UnstructuredStorage for bytes32;

    /* Hardcoded constants to save gas
    bytes32 internal constant REENTRANCY_MUTEX_POSITION = keccak256("aragonOS.reentrancyGuard.mutex");
    */
    bytes32 private constant REENTRANCY_MUTEX_POSITION = 0xe855346402235fdd185c890e68d2c4ecad599b88587635ee285bce2fda58dacb;

    string private constant ERROR_REENTRANT = "REENTRANCY_REENTRANT_CALL";

    modifier nonReentrant() {
        // Ensure mutex is unlocked
        require(!REENTRANCY_MUTEX_POSITION.getStorageBool(), ERROR_REENTRANT);

        // Lock mutex before function call
        REENTRANCY_MUTEX_POSITION.setStorageBool(true);

        // Perform function call
        _;

        // Unlock mutex after function call
        REENTRANCY_MUTEX_POSITION.setStorageBool(false);
    }
}
          

/*
 * SPDX-License-Identifier:    MIT
 */

pragma solidity ^0.4.24;

import "./Uint256Helpers.sol";


contract TimeHelpers {
    using Uint256Helpers for uint256;

    /**
    * @dev Returns the current block number.
    *      Using a function rather than `block.number` allows us to easily mock the block number in
    *      tests.
    */
    function getBlockNumber() internal view returns (uint256) {
        return block.number;
    }

    /**
    * @dev Returns the current block number, converted to uint64.
    *      Using a function rather than `block.number` allows us to easily mock the block number in
    *      tests.
    */
    function getBlockNumber64() internal view returns (uint64) {
        return getBlockNumber().toUint64();
    }

    /**
    * @dev Returns the current timestamp.
    *      Using a function rather than `block.timestamp` allows us to easily mock it in
    *      tests.
    */
    function getTimestamp() internal view returns (uint256) {
        return block.timestamp; // solium-disable-line security/no-block-members
    }

    /**
    * @dev Returns the current timestamp, converted to uint64.
    *      Using a function rather than `block.timestamp` allows us to easily mock it in
    *      tests.
    */
    function getTimestamp64() internal view returns (uint64) {
        return getTimestamp().toUint64();
    }
}
          

// SPDX-FileCopyrightText: 2023 Lido <info@lido.fi>
// SPDX-License-Identifier: GPL-3.0

pragma solidity 0.4.24;

import "@aragon/os/contracts/common/UnstructuredStorage.sol";


contract Pausable {
    using UnstructuredStorage for bytes32;

    event Stopped();
    event Resumed();

    // keccak256("lido.Pausable.activeFlag")
    bytes32 internal constant ACTIVE_FLAG_POSITION =
        0x644132c4ddd5bb6f0655d5fe2870dcec7870e6be4758890f366b83441f9fdece;

    function _whenNotStopped() internal view {
        require(ACTIVE_FLAG_POSITION.getStorageBool(), "CONTRACT_IS_STOPPED");
    }

    function _whenStopped() internal view {
        require(!ACTIVE_FLAG_POSITION.getStorageBool(), "CONTRACT_IS_ACTIVE");
    }

    function isStopped() public view returns (bool) {
        return !ACTIVE_FLAG_POSITION.getStorageBool();
    }

    function _stop() internal {
        _whenNotStopped();

        ACTIVE_FLAG_POSITION.setStorageBool(false);
        emit Stopped();
    }

    function _resume() internal {
        _whenStopped();

        ACTIVE_FLAG_POSITION.setStorageBool(true);
        emit Resumed();
    }
}
          

// See https://github.com/OpenZeppelin/openzeppelin-solidity/blob/a9f910d34f0ab33a1ae5e714f69f9596a02b4d91/contracts/token/ERC20/ERC20.sol

pragma solidity ^0.4.24;


/**
 * @title ERC20 interface
 * @dev see https://github.com/ethereum/EIPs/issues/20
 */
contract ERC20 {
    function totalSupply() public view returns (uint256);

    function balanceOf(address _who) public view returns (uint256);

    function allowance(address _owner, address _spender)
        public view returns (uint256);

    function transfer(address _to, uint256 _value) public returns (bool);

    function approve(address _spender, uint256 _value)
        public returns (bool);

    function transferFrom(address _from, address _to, uint256 _value)
        public returns (bool);

    event Transfer(
        address indexed from,
        address indexed to,
        uint256 value
    );

    event Approval(
        address indexed owner,
        address indexed spender,
        uint256 value
    );
}
          

// SPDX-FileCopyrightText: 2023 Lido <info@lido.fi>
// SPDX-License-Identifier: MIT

/* See contracts/COMPILERS.md */
// solhint-disable-next-line lido/fixed-compiler-version
pragma solidity >=0.4.24 <0.9.0;

import {ECDSA} from "./ECDSA.sol";


library SignatureUtils {
    /**
     * @dev The selector of the ERC1271's `isValidSignature(bytes32 hash, bytes signature)` function,
     * serving at the same time as the magic value that the function should return upon success.
     *
     * See https://eips.ethereum.org/EIPS/eip-1271.
     *
     * bytes4(keccak256("isValidSignature(bytes32,bytes)")
     */
    bytes4 internal constant ERC1271_IS_VALID_SIGNATURE_SELECTOR = 0x1626ba7e;

    /**
     * @dev Checks signature validity.
     *
     * If the signer address doesn't contain any code, assumes that the address is externally owned
     * and the signature is a ECDSA signature generated using its private key. Otherwise, issues a
     * static call to the signer address to check the signature validity using the ERC-1271 standard.
     */
    function isValidSignature(
        address signer,
        bytes32 msgHash,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal view returns (bool) {
        if (_hasCode(signer)) {
            bytes memory sig = abi.encodePacked(r, s, v);
            // Solidity <0.5 generates a regular CALL instruction even if the function being called
            // is marked as `view`, and the only way to perform a STATICCALL is to use assembly
            bytes memory data = abi.encodeWithSelector(ERC1271_IS_VALID_SIGNATURE_SELECTOR, msgHash, sig);
            bytes32 retval;
            /// @solidity memory-safe-assembly
            assembly {
                // allocate memory for storing the return value
                let outDataOffset := mload(0x40)
                mstore(0x40, add(outDataOffset, 32))
                // issue a static call and load the result if the call succeeded
                let success := staticcall(gas(), signer, add(data, 32), mload(data), outDataOffset, 32)
                if and(eq(success, 1), eq(returndatasize(), 32)) {
                    retval := mload(outDataOffset)
                }
            }
            return retval == bytes32(ERC1271_IS_VALID_SIGNATURE_SELECTOR);
        } else {
            return ECDSA.recover(msgHash, v, r, s) == signer;
        }
    }

    function _hasCode(address addr) internal view returns (bool) {
        uint256 size;
        /// @solidity memory-safe-assembly
        assembly { size := extcodesize(addr) }
        return size > 0;
    }
}
          

// SPDX-FileCopyrightText: 2023 Lido <info@lido.fi>
// SPDX-License-Identifier: GPL-3.0

/* See contracts/COMPILERS.md */
pragma solidity 0.4.24;

import "@aragon/os/contracts/common/UnstructuredStorage.sol";

//
// We need to pack four variables into the same 256bit-wide storage slot
// to lower the costs per each staking request.
//
// As a result, slot's memory aligned as follows:
//
// MSB ------------------------------------------------------------------------------> LSB
// 256____________160_________________________128_______________32_____________________ 0
// |_______________|___________________________|________________|_______________________|
// | maxStakeLimit | maxStakeLimitGrowthBlocks | prevStakeLimit | prevStakeBlockNumber  |
// |<-- 96 bits -->|<---------- 32 bits ------>|<-- 96 bits --->|<----- 32 bits ------->|
//
//
// NB: Internal representation conventions:
//
// - the `maxStakeLimitGrowthBlocks` field above represented as follows:
// `maxStakeLimitGrowthBlocks` = `maxStakeLimit` / `stakeLimitIncreasePerBlock`
//           32 bits                 96 bits               96 bits
//
//
// - the "staking paused" state is encoded by `prevStakeBlockNumber` being zero,
// - the "staking unlimited" state is encoded by `maxStakeLimit` being zero and `prevStakeBlockNumber` being non-zero.
//

/**
* @notice Library for the internal structs definitions
* @dev solidity <0.6 doesn't support top-level structs
* using the library to have a proper namespace
*/
library StakeLimitState {
    /**
      * @dev Internal representation struct (slot-wide)
      */
    struct Data {
        uint32 prevStakeBlockNumber;      // block number of the previous stake submit
        uint96 prevStakeLimit;            // limit value (<= `maxStakeLimit`) obtained on the previous stake submit
        uint32 maxStakeLimitGrowthBlocks; // limit regeneration speed expressed in blocks
        uint96 maxStakeLimit;             // maximum limit value
    }
}

library StakeLimitUnstructuredStorage {
    using UnstructuredStorage for bytes32;

    /// @dev Storage offset for `maxStakeLimit` (bits)
    uint256 internal constant MAX_STAKE_LIMIT_OFFSET = 160;
    /// @dev Storage offset for `maxStakeLimitGrowthBlocks` (bits)
    uint256 internal constant MAX_STAKE_LIMIT_GROWTH_BLOCKS_OFFSET = 128;
    /// @dev Storage offset for `prevStakeLimit` (bits)
    uint256 internal constant PREV_STAKE_LIMIT_OFFSET = 32;
    /// @dev Storage offset for `prevStakeBlockNumber` (bits)
    uint256 internal constant PREV_STAKE_BLOCK_NUMBER_OFFSET = 0;

    /**
    * @dev Read stake limit state from the unstructured storage position
    * @param _position storage offset
    */
    function getStorageStakeLimitStruct(bytes32 _position) internal view returns (StakeLimitState.Data memory stakeLimit) {
        uint256 slotValue = _position.getStorageUint256();

        stakeLimit.prevStakeBlockNumber = uint32(slotValue >> PREV_STAKE_BLOCK_NUMBER_OFFSET);
        stakeLimit.prevStakeLimit = uint96(slotValue >> PREV_STAKE_LIMIT_OFFSET);
        stakeLimit.maxStakeLimitGrowthBlocks = uint32(slotValue >> MAX_STAKE_LIMIT_GROWTH_BLOCKS_OFFSET);
        stakeLimit.maxStakeLimit = uint96(slotValue >> MAX_STAKE_LIMIT_OFFSET);
    }

     /**
    * @dev Write stake limit state to the unstructured storage position
    * @param _position storage offset
    * @param _data stake limit state structure instance
    */
    function setStorageStakeLimitStruct(bytes32 _position, StakeLimitState.Data memory _data) internal {
        _position.setStorageUint256(
            uint256(_data.prevStakeBlockNumber) << PREV_STAKE_BLOCK_NUMBER_OFFSET
                | uint256(_data.prevStakeLimit) << PREV_STAKE_LIMIT_OFFSET
                | uint256(_data.maxStakeLimitGrowthBlocks) << MAX_STAKE_LIMIT_GROWTH_BLOCKS_OFFSET
                | uint256(_data.maxStakeLimit) << MAX_STAKE_LIMIT_OFFSET
        );
    }
}

/**
* @notice Interface library with helper functions to deal with stake limit struct in a more high-level approach.
*/
library StakeLimitUtils {
    /**
    * @notice Calculate stake limit for the current block.
    * @dev using `_constGasMin` to make gas consumption independent of the current block number
    */
    function calculateCurrentStakeLimit(StakeLimitState.Data memory _data) internal view returns(uint256 limit) {
        uint256 stakeLimitIncPerBlock;
        if (_data.maxStakeLimitGrowthBlocks != 0) {
            stakeLimitIncPerBlock = _data.maxStakeLimit / _data.maxStakeLimitGrowthBlocks;
        }

        uint256 blocksPassed = block.number - _data.prevStakeBlockNumber;
        uint256 projectedLimit = _data.prevStakeLimit + blocksPassed * stakeLimitIncPerBlock;

        limit = _constGasMin(
            projectedLimit,
            _data.maxStakeLimit
        );
    }

    /**
    * @notice check if staking is on pause
    */
    function isStakingPaused(StakeLimitState.Data memory _data) internal pure returns(bool) {
        return _data.prevStakeBlockNumber == 0;
    }

    /**
    * @notice check if staking limit is set (otherwise staking is unlimited)
    */
    function isStakingLimitSet(StakeLimitState.Data memory _data) internal pure returns(bool) {
        return _data.maxStakeLimit != 0;
    }

    /**
    * @notice update stake limit repr with the desired limits
    * @dev input `_data` param is mutated and the func returns effectively the same pointer
    * @param _data stake limit state struct
    * @param _maxStakeLimit stake limit max value
    * @param _stakeLimitIncreasePerBlock stake limit increase (restoration) per block
    */
    function setStakingLimit(
        StakeLimitState.Data memory _data,
        uint256 _maxStakeLimit,
        uint256 _stakeLimitIncreasePerBlock
    ) internal view returns (StakeLimitState.Data memory) {
        require(_maxStakeLimit != 0, "ZERO_MAX_STAKE_LIMIT");
        require(_maxStakeLimit <= uint96(-1), "TOO_LARGE_MAX_STAKE_LIMIT");
        require(_maxStakeLimit >= _stakeLimitIncreasePerBlock, "TOO_LARGE_LIMIT_INCREASE");
        require(
            (_stakeLimitIncreasePerBlock == 0)
            || (_maxStakeLimit / _stakeLimitIncreasePerBlock <= uint32(-1)),
            "TOO_SMALL_LIMIT_INCREASE"
        );

        // reset prev stake limit to the new max stake limit if
        if (
            // staking was paused or
            _data.prevStakeBlockNumber == 0 ||
            // staking was unlimited or
            _data.maxStakeLimit == 0 ||
            // new maximum limit value is lower than the value obtained on the previous stake submit
            _maxStakeLimit < _data.prevStakeLimit
        ) {
            _data.prevStakeLimit = uint96(_maxStakeLimit);
        }
        _data.maxStakeLimitGrowthBlocks =
            _stakeLimitIncreasePerBlock != 0 ? uint32(_maxStakeLimit / _stakeLimitIncreasePerBlock) : 0;

        _data.maxStakeLimit = uint96(_maxStakeLimit);

        if (_data.prevStakeBlockNumber != 0) {
            _data.prevStakeBlockNumber = uint32(block.number);
        }

        return _data;
    }

    /**
    * @notice update stake limit repr to remove the limit
    * @dev input `_data` param is mutated and the func returns effectively the same pointer
    * @param _data stake limit state struct
    */
    function removeStakingLimit(
        StakeLimitState.Data memory _data
    ) internal pure returns (StakeLimitState.Data memory) {
        _data.maxStakeLimit = 0;

        return _data;
    }

    /**
    * @notice update stake limit repr after submitting user's eth
    * @dev input `_data` param is mutated and the func returns effectively the same pointer
    * @param _data stake limit state struct
    * @param _newPrevStakeLimit new value for the `prevStakeLimit` field
    */
    function updatePrevStakeLimit(
        StakeLimitState.Data memory _data,
        uint256 _newPrevStakeLimit
    ) internal view returns (StakeLimitState.Data memory) {
        assert(_newPrevStakeLimit <= uint96(-1));
        assert(_data.prevStakeBlockNumber != 0);

        _data.prevStakeLimit = uint96(_newPrevStakeLimit);
        _data.prevStakeBlockNumber = uint32(block.number);

        return _data;
    }

    /**
    * @notice set stake limit pause state (on or off)
    * @dev input `_data` param is mutated and the func returns effectively the same pointer
    * @param _data stake limit state struct
    * @param _isPaused pause state flag
    */
    function setStakeLimitPauseState(
        StakeLimitState.Data memory _data,
        bool _isPaused
    ) internal view returns (StakeLimitState.Data memory) {
        _data.prevStakeBlockNumber = uint32(_isPaused ? 0 : block.number);

        return _data;
    }

    /**
     * @notice find a minimum of two numbers with a constant gas consumption
     * @dev doesn't use branching logic inside
     * @param _lhs left hand side value
     * @param _rhs right hand side value
     */
    function _constGasMin(uint256 _lhs, uint256 _rhs) internal pure returns (uint256 min) {
        uint256 lhsIsLess;
        assembly {
            lhsIsLess := lt(_lhs, _rhs) // lhsIsLess = (_lhs < _rhs) ? 1 : 0
        }
        min = (_lhs * lhsIsLess) + (_rhs * (1 - lhsIsLess));
    }
}
          

/*
 * SPDX-License-Identifier:    MIT
 */

pragma solidity ^0.4.24;

import "./IEVMScriptExecutor.sol";


contract EVMScriptRegistryConstants {
    /* Hardcoded constants to save gas
    bytes32 internal constant EVMSCRIPT_REGISTRY_APP_ID = apmNamehash("evmreg");
    */
    bytes32 internal constant EVMSCRIPT_REGISTRY_APP_ID = 0xddbcfd564f642ab5627cf68b9b7d374fb4f8a36e941a75d89c87998cef03bd61;
}


interface IEVMScriptRegistry {
    function addScriptExecutor(IEVMScriptExecutor executor) external returns (uint id);
    function disableScriptExecutor(uint256 executorId) external;

    // TODO: this should be external
    // See https://github.com/ethereum/solidity/issues/4832
    function getScriptExecutor(bytes script) public view returns (IEVMScriptExecutor);
}
          

// SPDX-License-Identifier: MIT

// Extracted from:
// https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v3.4.0/contracts/cryptography/ECDSA.sol#L53
// https://github.com/OpenZeppelin/openzeppelin-contracts/blob/541e821/contracts/utils/cryptography/ECDSA.sol#L112

/* See contracts/COMPILERS.md */
// solhint-disable-next-line
pragma solidity >=0.4.24 <0.9.0;


library ECDSA {
    /**
     * @dev Returns the address that signed a hashed message (`hash`).
     * This address can then be used for verification purposes.
     * Receives the `v`, `r` and `s` signature fields separately.
     *
     * 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.
     */
    function recover(bytes32 hash, uint8 v, bytes32 r, bytes32 s) internal pure returns (address)
    {
        // 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 (281): 0 < s < secp256k1n ÷ 2 + 1, and for v in (282): 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.
        require(uint256(s) <= 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0, "ECDSA: invalid signature 's' value");

        // If the signature is valid (and not malleable), return the signer address
        address signer = ecrecover(hash, v, r, s);
        require(signer != address(0), "ECDSA: invalid signature");

        return signer;
    }

    /**
     * @dev Overload of `recover` that receives the `r` and `vs` short-signature fields separately.
     * See https://eips.ethereum.org/EIPS/eip-2098[EIP-2098 short signatures]
     */
    function recover(bytes32 hash, bytes32 r, bytes32 vs) internal pure returns (address) {
        bytes32 s;
        uint8 v;
        assembly {
            s := and(vs, 0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff)
            v := add(shr(255, vs), 27)
        }
        return recover(hash, v, r, s);
    }
}
          

/*
 * SPDX-License-Identifier:    MIT
 */

pragma solidity ^0.4.24;

import "../lib/token/ERC20.sol";
import "./EtherTokenConstant.sol";
import "./IsContract.sol";
import "./IVaultRecoverable.sol";
import "./SafeERC20.sol";


contract VaultRecoverable is IVaultRecoverable, EtherTokenConstant, IsContract {
    using SafeERC20 for ERC20;

    string private constant ERROR_DISALLOWED = "RECOVER_DISALLOWED";
    string private constant ERROR_VAULT_NOT_CONTRACT = "RECOVER_VAULT_NOT_CONTRACT";
    string private constant ERROR_TOKEN_TRANSFER_FAILED = "RECOVER_TOKEN_TRANSFER_FAILED";

    /**
     * @notice Send funds to recovery Vault. This contract should never receive funds,
     *         but in case it does, this function allows one to recover them.
     * @param _token Token balance to be sent to recovery vault.
     */
    function transferToVault(address _token) external {
        require(allowRecoverability(_token), ERROR_DISALLOWED);
        address vault = getRecoveryVault();
        require(isContract(vault), ERROR_VAULT_NOT_CONTRACT);

        uint256 balance;
        if (_token == ETH) {
            balance = address(this).balance;
            vault.transfer(balance);
        } else {
            ERC20 token = ERC20(_token);
            balance = token.staticBalanceOf(this);
            require(token.safeTransfer(vault, balance), ERROR_TOKEN_TRANSFER_FAILED);
        }

        emit RecoverToVault(vault, _token, balance);
    }

    /**
    * @dev By default deriving from AragonApp makes it recoverable
    * @param token Token address that would be recovered
    * @return bool whether the app allows the recovery
    */
    function allowRecoverability(address token) public view returns (bool) {
        return true;
    }

    // Cast non-implemented interface to be public so we can use it internally
    function getRecoveryVault() public view returns (address);
}
          

// SPDX-FileCopyrightText: 2023 Lido <info@lido.fi>
// SPDX-License-Identifier: MIT

// Copied from: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/0457042d93d9dfd760dbaa06a4d2f1216fdbe297/contracts/utils/math/Math.sol

// See contracts/COMPILERS.md
// solhint-disable-next-line
pragma solidity >=0.4.24 <0.9.0;

library Math256 {
    /// @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 largest of two numbers.
    function max(int256 a, int256 b) internal pure returns (int256) {
        return a > b ? a : b;
    }

    /// @dev Returns the smallest of two numbers.
    function min(int256 a, int256 b) internal pure returns (int256) {
        return a < b ? a : b;
    }

    /// @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;
    }

    /// @dev Returns absolute difference of two numbers.
    function absDiff(uint256 a, uint256 b) internal pure returns (uint256) {
        return a > b ? a - b : b - a;
    }
}
          

/*
 * SPDX-License-Identifier:    MIT
 */

pragma solidity ^0.4.24;


library UnstructuredStorage {
    function getStorageBool(bytes32 position) internal view returns (bool data) {
        assembly { data := sload(position) }
    }

    function getStorageAddress(bytes32 position) internal view returns (address data) {
        assembly { data := sload(position) }
    }

    function getStorageBytes32(bytes32 position) internal view returns (bytes32 data) {
        assembly { data := sload(position) }
    }

    function getStorageUint256(bytes32 position) internal view returns (uint256 data) {
        assembly { data := sload(position) }
    }

    function setStorageBool(bytes32 position, bool data) internal {
        assembly { sstore(position, data) }
    }

    function setStorageAddress(bytes32 position, address data) internal {
        assembly { sstore(position, data) }
    }

    function setStorageBytes32(bytes32 position, bytes32 data) internal {
        assembly { sstore(position, data) }
    }

    function setStorageUint256(bytes32 position, uint256 data) internal {
        assembly { sstore(position, data) }
    }
}
          

// SPDX-FileCopyrightText: 2023 OpenZeppelin, Lido <info@lido.fi>
// SPDX-License-Identifier: GPL-3.0

// See contracts/COMPILERS.md
// solhint-disable-next-line
pragma solidity >=0.4.24 <0.9.0;

/**
 * @dev Helper interface of EIP712 StETH-dedicated helper.
 *
 * Has an access to the CHAIN_ID opcode and relies on immutables internally
 * Both are unavailable for Solidity 0.4.24.
 */
interface IEIP712StETH {
    /**
     * @dev Returns the domain separator for the current chain.
     */
    function domainSeparatorV4(address _stETH) external view returns (bytes32);

    /**
     * @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(address _stETH, bytes32 _structHash) external view returns (bytes32);

    /**
     * @dev returns the fields and values that describe the domain separator
     * used by stETH for EIP-712 signature.
     */
    function eip712Domain(address _stETH) external view returns (
        string memory name,
        string memory version,
        uint256 chainId,
        address verifyingContract
    );
}
          

// SPDX-FileCopyrightText: 2023 OpenZeppelin, Lido <info@lido.fi>
// SPDX-License-Identifier: GPL-3.0

/* See contracts/COMPILERS.md */
pragma solidity 0.4.24;

import {UnstructuredStorage} from "@aragon/os/contracts/common/UnstructuredStorage.sol";

import {SignatureUtils} from "../common/lib/SignatureUtils.sol";
import {IEIP712StETH} from "../common/interfaces/IEIP712StETH.sol";

import {StETH} from "./StETH.sol";

/**
 * @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.
 */
interface IERC2612 {
    /**
     * @dev Sets `value` as the allowance of `spender` over ``owner``'s tokens,
     * given ``owner``'s signed approval.
     * 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}).
     */
    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);
}


contract StETHPermit is IERC2612, StETH {
    using UnstructuredStorage for bytes32;

    /**
     * @dev Service event for initialization
     */
    event EIP712StETHInitialized(address eip712StETH);

    /**
     * @dev Nonces for ERC-2612 (Permit)
     */
    mapping(address => uint256) internal noncesByAddress;

    /**
     * @dev Storage position used for the EIP712 message utils contract
     *
     * keccak256("lido.StETHPermit.eip712StETH")
     */
    bytes32 internal constant EIP712_STETH_POSITION =
        0x42b2d95e1ce15ce63bf9a8d9f6312cf44b23415c977ffa3b884333422af8941c;

    /**
     * @dev Typehash constant for ERC-2612 (Permit)
     *
     * keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)")
     */
    bytes32 internal constant PERMIT_TYPEHASH =
        0x6e71edae12b1b97f4d1f60370fef10105fa2faae0126114a169c64845d6126c9;

    /**
     * @dev Sets `value` as the allowance of `spender` over ``owner``'s tokens,
     * given ``owner``'s signed approval.
     * 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}).
     */
    function permit(
        address _owner, address _spender, uint256 _value, uint256 _deadline, uint8 _v, bytes32 _r, bytes32 _s
    ) external {
        require(block.timestamp <= _deadline, "DEADLINE_EXPIRED");

        bytes32 structHash = keccak256(
            abi.encode(PERMIT_TYPEHASH, _owner, _spender, _value, _useNonce(_owner), _deadline)
        );

        bytes32 hash = IEIP712StETH(getEIP712StETH()).hashTypedDataV4(address(this), structHash);

        require(SignatureUtils.isValidSignature(_owner, hash, _v, _r, _s), "INVALID_SIGNATURE");
        _approve(_owner, _spender, _value);
    }

    /**
     * @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) {
        return noncesByAddress[owner];
    }

    /**
     * @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) {
        return IEIP712StETH(getEIP712StETH()).domainSeparatorV4(address(this));
    }

    /**
     * @dev returns the fields and values that describe the domain separator used by this contract for EIP-712
     * signature.
     *
     * NB: compairing to the full-fledged ERC-5267 version:
     * - `salt` and `extensions` are unused
     * - `flags` is hex"0f" or 01111b
     *
     * @dev using shortened returns to reduce a bytecode size
     */
    function eip712Domain() external view returns (
        string memory name,
        string memory version,
        uint256 chainId,
        address verifyingContract
    ) {
        return IEIP712StETH(getEIP712StETH()).eip712Domain(address(this));
    }

    /**
     * @dev "Consume a nonce": return the current value and increment.
     */
    function _useNonce(address _owner) internal returns (uint256 current) {
        current = noncesByAddress[_owner];
        noncesByAddress[_owner] = current.add(1);
    }

    /**
     * @dev Initialize EIP712 message utils contract for stETH
     */
    function _initializeEIP712StETH(address _eip712StETH) internal {
        require(_eip712StETH != address(0), "ZERO_EIP712STETH");
        require(getEIP712StETH() == address(0), "EIP712STETH_ALREADY_SET");

        EIP712_STETH_POSITION.setStorageAddress(_eip712StETH);

        emit EIP712StETHInitialized(_eip712StETH);
    }

    /**
     * @dev Get EIP712 message utils contract
     */
    function getEIP712StETH() public view returns (address) {
        return EIP712_STETH_POSITION.getStorageAddress();
    }
}
          

pragma solidity ^0.4.24;

/**
 * @title ERC20 interface
 * @dev see https://github.com/ethereum/EIPs/issues/20
 */
interface IERC20 {
  function totalSupply() external view returns (uint256);

  function balanceOf(address who) external view returns (uint256);

  function allowance(address owner, address spender)
    external view returns (uint256);

  function transfer(address to, uint256 value) external returns (bool);

  function approve(address spender, uint256 value)
    external returns (bool);

  function transferFrom(address from, address to, uint256 value)
    external returns (bool);

  event Transfer(
    address indexed from,
    address indexed to,
    uint256 value
  );

  event Approval(
    address indexed owner,
    address indexed spender,
    uint256 value
  );
}
          

/*
 * SPDX-License-Identifier:    MIT
 */

pragma solidity ^0.4.24;


contract KernelAppIds {
    /* Hardcoded constants to save gas
    bytes32 internal constant KERNEL_CORE_APP_ID = apmNamehash("kernel");
    bytes32 internal constant KERNEL_DEFAULT_ACL_APP_ID = apmNamehash("acl");
    bytes32 internal constant KERNEL_DEFAULT_VAULT_APP_ID = apmNamehash("vault");
    */
    bytes32 internal constant KERNEL_CORE_APP_ID = 0x3b4bf6bf3ad5000ecf0f989d5befde585c6860fea3e574a4fab4c49d1c177d9c;
    bytes32 internal constant KERNEL_DEFAULT_ACL_APP_ID = 0xe3262375f45a6e2026b7e7b18c2b807434f2508fe1a2a3dfb493c7df8f4aad6a;
    bytes32 internal constant KERNEL_DEFAULT_VAULT_APP_ID = 0x7e852e0fcfce6551c13800f1e7476f982525c2b5277ba14b24339c68416336d1;
}


contract KernelNamespaceConstants {
    /* Hardcoded constants to save gas
    bytes32 internal constant KERNEL_CORE_NAMESPACE = keccak256("core");
    bytes32 internal constant KERNEL_APP_BASES_NAMESPACE = keccak256("base");
    bytes32 internal constant KERNEL_APP_ADDR_NAMESPACE = keccak256("app");
    */
    bytes32 internal constant KERNEL_CORE_NAMESPACE = 0xc681a85306374a5ab27f0bbc385296a54bcd314a1948b6cf61c4ea1bc44bb9f8;
    bytes32 internal constant KERNEL_APP_BASES_NAMESPACE = 0xf1f3eb40f5bc1ad1344716ced8b8a0431d840b5783aea1fd01786bc26f35ac0f;
    bytes32 internal constant KERNEL_APP_ADDR_NAMESPACE = 0xd6f028ca0e8edb4a8c9757ca4fdccab25fa1e0317da1188108f7d2dee14902fb;
}
          

/*
 * SPDX-License-Identifier:    MIT
 */

pragma solidity ^0.4.24;


contract IsContract {
    /*
    * NOTE: this should NEVER be used for authentication
    * (see pitfalls: https://github.com/fergarrui/ethereum-security/tree/master/contracts/extcodesize).
    *
    * This is only intended to be used as a sanity check that an address is actually a contract,
    * RATHER THAN an address not being a contract.
    */
    function isContract(address _target) internal view returns (bool) {
        if (_target == address(0)) {
            return false;
        }

        uint256 size;
        assembly { size := extcodesize(_target) }
        return size > 0;
    }
}
          

/*
 * SPDX-License-Identifier:    MIT
 */

pragma solidity ^0.4.24;

import "./IEVMScriptExecutor.sol";
import "./IEVMScriptRegistry.sol";

import "../apps/AppStorage.sol";
import "../kernel/KernelConstants.sol";
import "../common/Initializable.sol";


contract EVMScriptRunner is AppStorage, Initializable, EVMScriptRegistryConstants, KernelNamespaceConstants {
    string private constant ERROR_EXECUTOR_UNAVAILABLE = "EVMRUN_EXECUTOR_UNAVAILABLE";
    string private constant ERROR_PROTECTED_STATE_MODIFIED = "EVMRUN_PROTECTED_STATE_MODIFIED";

    /* This is manually crafted in assembly
    string private constant ERROR_EXECUTOR_INVALID_RETURN = "EVMRUN_EXECUTOR_INVALID_RETURN";
    */

    event ScriptResult(address indexed executor, bytes script, bytes input, bytes returnData);

    function getEVMScriptExecutor(bytes _script) public view returns (IEVMScriptExecutor) {
        return IEVMScriptExecutor(getEVMScriptRegistry().getScriptExecutor(_script));
    }

    function getEVMScriptRegistry() public view returns (IEVMScriptRegistry) {
        address registryAddr = kernel().getApp(KERNEL_APP_ADDR_NAMESPACE, EVMSCRIPT_REGISTRY_APP_ID);
        return IEVMScriptRegistry(registryAddr);
    }

    function runScript(bytes _script, bytes _input, address[] _blacklist)
        internal
        isInitialized
        protectState
        returns (bytes)
    {
        IEVMScriptExecutor executor = getEVMScriptExecutor(_script);
        require(address(executor) != address(0), ERROR_EXECUTOR_UNAVAILABLE);

        bytes4 sig = executor.execScript.selector;
        bytes memory data = abi.encodeWithSelector(sig, _script, _input, _blacklist);

        bytes memory output;
        assembly {
            let success := delegatecall(
                gas,                // forward all gas
                executor,           // address
                add(data, 0x20),    // calldata start
                mload(data),        // calldata length
                0,                  // don't write output (we'll handle this ourselves)
                0                   // don't write output
            )

            output := mload(0x40) // free mem ptr get

            switch success
            case 0 {
                // If the call errored, forward its full error data
                returndatacopy(output, 0, returndatasize)
                revert(output, returndatasize)
            }
            default {
                switch gt(returndatasize, 0x3f)
                case 0 {
                    // Need at least 0x40 bytes returned for properly ABI-encoded bytes values,
                    // revert with "EVMRUN_EXECUTOR_INVALID_RETURN"
                    // See remix: doing a `revert("EVMRUN_EXECUTOR_INVALID_RETURN")` always results in
                    // this memory layout
                    mstore(output, 0x08c379a000000000000000000000000000000000000000000000000000000000)         // error identifier
                    mstore(add(output, 0x04), 0x0000000000000000000000000000000000000000000000000000000000000020) // starting offset
                    mstore(add(output, 0x24), 0x000000000000000000000000000000000000000000000000000000000000001e) // reason length
                    mstore(add(output, 0x44), 0x45564d52554e5f4558454355544f525f494e56414c49445f52455455524e0000) // reason

                    revert(output, 100) // 100 = 4 + 3 * 32 (error identifier + 3 words for the ABI encoded error)
                }
                default {
                    // Copy result
                    //
                    // Needs to perform an ABI decode for the expected `bytes` return type of
                    // `executor.execScript()` as solidity will automatically ABI encode the returned bytes as:
                    //    [ position of the first dynamic length return value = 0x20 (32 bytes) ]
                    //    [ output length (32 bytes) ]
                    //    [ output content (N bytes) ]
                    //
                    // Perform the ABI decode by ignoring the first 32 bytes of the return data
                    let copysize := sub(returndatasize, 0x20)
                    returndatacopy(output, 0x20, copysize)

                    mstore(0x40, add(output, copysize)) // free mem ptr set
                }
            }
        }

        emit ScriptResult(address(executor), _script, _input, output);

        return output;
    }

    modifier protectState {
        address preKernel = address(kernel());
        bytes32 preAppId = appId();
        _; // exec
        require(address(kernel()) == preKernel, ERROR_PROTECTED_STATE_MODIFIED);
        require(appId() == preAppId, ERROR_PROTECTED_STATE_MODIFIED);
    }
}
          

/*
 * SPDX-License-Identifier:    MIT
 */

pragma solidity ^0.4.24;


// aragonOS and aragon-apps rely on address(0) to denote native ETH, in
// contracts where both tokens and ETH are accepted
contract EtherTokenConstant {
    address internal constant ETH = address(0);
}
          

/*
 * SPDX-License-Identifier:    MIT
 */

pragma solidity ^0.4.24;

import "./Initializable.sol";


contract Petrifiable is Initializable {
    // Use block UINT256_MAX (which should be never) as the initializable date
    uint256 internal constant PETRIFIED_BLOCK = uint256(-1);

    function isPetrified() public view returns (bool) {
        return getInitializationBlock() == PETRIFIED_BLOCK;
    }

    /**
    * @dev Function to be called by top level contract to prevent being initialized.
    *      Useful for freezing base contracts when they're used behind proxies.
    */
    function petrify() internal onlyInit {
        initializedAt(PETRIFIED_BLOCK);
    }
}
          

// SPDX-FileCopyrightText: 2023 Lido <info@lido.fi>
// SPDX-License-Identifier: GPL-3.0

/* See contracts/COMPILERS.md */
pragma solidity 0.4.24;

import "openzeppelin-solidity/contracts/token/ERC20/IERC20.sol";
import "@aragon/os/contracts/common/UnstructuredStorage.sol";
import "@aragon/os/contracts/lib/math/SafeMath.sol";
import "./utils/Pausable.sol";

/**
 * @title Interest-bearing ERC20-like token for Lido Liquid Stacking protocol.
 *
 * This contract is abstract. To make the contract deployable override the
 * `_getTotalPooledEther` function. `Lido.sol` contract inherits StETH and defines
 * the `_getTotalPooledEther` function.
 *
 * StETH balances are dynamic and represent the holder's share in the total amount
 * of Ether controlled by the protocol. Account shares aren't normalized, so the
 * contract also stores the sum of all shares to calculate each account's token balance
 * which equals to:
 *
 *   shares[account] * _getTotalPooledEther() / _getTotalShares()
 *
 * For example, assume that we have:
 *
 *   _getTotalPooledEther() -> 10 ETH
 *   sharesOf(user1) -> 100
 *   sharesOf(user2) -> 400
 *
 * Therefore:
 *
 *   balanceOf(user1) -> 2 tokens which corresponds 2 ETH
 *   balanceOf(user2) -> 8 tokens which corresponds 8 ETH
 *
 * Since balances of all token holders change when the amount of total pooled Ether
 * changes, this token cannot fully implement ERC20 standard: it only emits `Transfer`
 * events upon explicit transfer between holders. In contrast, when total amount of
 * pooled Ether increases, no `Transfer` events are generated: doing so would require
 * emitting an event for each token holder and thus running an unbounded loop.
 *
 * The token inherits from `Pausable` and uses `whenNotStopped` modifier for methods
 * which change `shares` or `allowances`. `_stop` and `_resume` functions are overridden
 * in `Lido.sol` and might be called by an account with the `PAUSE_ROLE` assigned by the
 * DAO. This is useful for emergency scenarios, e.g. a protocol bug, where one might want
 * to freeze all token transfers and approvals until the emergency is resolved.
 */
contract StETH is IERC20, Pausable {
    using SafeMath for uint256;
    using UnstructuredStorage for bytes32;

    address constant internal INITIAL_TOKEN_HOLDER = 0xdead;
    uint256 constant internal INFINITE_ALLOWANCE = ~uint256(0);

    /**
     * @dev StETH balances are dynamic and are calculated based on the accounts' shares
     * and the total amount of Ether controlled by the protocol. Account shares aren't
     * normalized, so the contract also stores the sum of all shares to calculate
     * each account's token balance which equals to:
     *
     *   shares[account] * _getTotalPooledEther() / _getTotalShares()
    */
    mapping (address => uint256) private shares;

    /**
     * @dev Allowances are nominated in tokens, not token shares.
     */
    mapping (address => mapping (address => uint256)) private allowances;

    /**
     * @dev Storage position used for holding the total amount of shares in existence.
     *
     * The Lido protocol is built on top of Aragon and uses the Unstructured Storage pattern
     * for value types:
     *
     * https://blog.openzeppelin.com/upgradeability-using-unstructured-storage
     * https://blog.8bitzen.com/posts/20-02-2020-understanding-how-solidity-upgradeable-unstructured-proxies-work
     *
     * For reference types, conventional storage variables are used since it's non-trivial
     * and error-prone to implement reference-type unstructured storage using Solidity v0.4;
     * see https://github.com/lidofinance/lido-dao/issues/181#issuecomment-736098834
     *
     * keccak256("lido.StETH.totalShares")
     */
    bytes32 internal constant TOTAL_SHARES_POSITION =
        0xe3b4b636e601189b5f4c6742edf2538ac12bb61ed03e6da26949d69838fa447e;

    /**
      * @notice An executed shares transfer from `sender` to `recipient`.
      *
      * @dev emitted in pair with an ERC20-defined `Transfer` event.
      */
    event TransferShares(
        address indexed from,
        address indexed to,
        uint256 sharesValue
    );

    /**
     * @notice An executed `burnShares` request
     *
     * @dev Reports simultaneously burnt shares amount
     * and corresponding stETH amount.
     * The stETH amount is calculated twice: before and after the burning incurred rebase.
     *
     * @param account holder of the burnt shares
     * @param preRebaseTokenAmount amount of stETH the burnt shares corresponded to before the burn
     * @param postRebaseTokenAmount amount of stETH the burnt shares corresponded to after the burn
     * @param sharesAmount amount of burnt shares
     */
    event SharesBurnt(
        address indexed account,
        uint256 preRebaseTokenAmount,
        uint256 postRebaseTokenAmount,
        uint256 sharesAmount
    );

    /**
     * @return the name of the token.
     */
    function name() external pure returns (string) {
        return "Liquid staked Ether 2.0";
    }

    /**
     * @return the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() external pure returns (string) {
        return "stETH";
    }

    /**
     * @return the number of decimals for getting user representation of a token amount.
     */
    function decimals() external pure returns (uint8) {
        return 18;
    }

    /**
     * @return the amount of tokens in existence.
     *
     * @dev Always equals to `_getTotalPooledEther()` since token amount
     * is pegged to the total amount of Ether controlled by the protocol.
     */
    function totalSupply() external view returns (uint256) {
        return _getTotalPooledEther();
    }

    /**
     * @return the entire amount of Ether controlled by the protocol.
     *
     * @dev The sum of all ETH balances in the protocol, equals to the total supply of stETH.
     */
    function getTotalPooledEther() external view returns (uint256) {
        return _getTotalPooledEther();
    }

    /**
     * @return the amount of tokens owned by the `_account`.
     *
     * @dev Balances are dynamic and equal the `_account`'s share in the amount of the
     * total Ether controlled by the protocol. See `sharesOf`.
     */
    function balanceOf(address _account) external view returns (uint256) {
        return getPooledEthByShares(_sharesOf(_account));
    }

    /**
     * @notice Moves `_amount` tokens from the caller's account to the `_recipient` account.
     *
     * @return a boolean value indicating whether the operation succeeded.
     * Emits a `Transfer` event.
     * Emits a `TransferShares` event.
     *
     * Requirements:
     *
     * - `_recipient` cannot be the zero address.
     * - the caller must have a balance of at least `_amount`.
     * - the contract must not be paused.
     *
     * @dev The `_amount` argument is the amount of tokens, not shares.
     */
    function transfer(address _recipient, uint256 _amount) external returns (bool) {
        _transfer(msg.sender, _recipient, _amount);
        return true;
    }

    /**
     * @return the remaining number of tokens that `_spender` is allowed to spend
     * on behalf of `_owner` through `transferFrom`. This is zero by default.
     *
     * @dev This value changes when `approve` or `transferFrom` is called.
     */
    function allowance(address _owner, address _spender) external view returns (uint256) {
        return allowances[_owner][_spender];
    }

    /**
     * @notice Sets `_amount` as the allowance of `_spender` over the caller's tokens.
     *
     * @return a boolean value indicating whether the operation succeeded.
     * Emits an `Approval` event.
     *
     * Requirements:
     *
     * - `_spender` cannot be the zero address.
     *
     * @dev The `_amount` argument is the amount of tokens, not shares.
     */
    function approve(address _spender, uint256 _amount) external returns (bool) {
        _approve(msg.sender, _spender, _amount);
        return true;
    }

    /**
     * @notice Moves `_amount` tokens from `_sender` to `_recipient` using the
     * allowance mechanism. `_amount` is then deducted from the caller's
     * allowance.
     *
     * @return a boolean value indicating whether the operation succeeded.
     *
     * Emits a `Transfer` event.
     * Emits a `TransferShares` event.
     * Emits an `Approval` event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `_sender` and `_recipient` cannot be the zero addresses.
     * - `_sender` must have a balance of at least `_amount`.
     * - the caller must have allowance for `_sender`'s tokens of at least `_amount`.
     * - the contract must not be paused.
     *
     * @dev The `_amount` argument is the amount of tokens, not shares.
     */
    function transferFrom(address _sender, address _recipient, uint256 _amount) external returns (bool) {
        _spendAllowance(_sender, msg.sender, _amount);
        _transfer(_sender, _recipient, _amount);
        return true;
    }

    /**
     * @notice Atomically increases the allowance granted to `_spender` by the caller by `_addedValue`.
     *
     * This is an alternative to `approve` that can be used as a mitigation for
     * problems described in:
     * https://github.com/OpenZeppelin/openzeppelin-contracts/blob/b709eae01d1da91902d06ace340df6b324e6f049/contracts/token/ERC20/IERC20.sol#L57
     * Emits an `Approval` event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `_spender` cannot be the the zero address.
     */
    function increaseAllowance(address _spender, uint256 _addedValue) external returns (bool) {
        _approve(msg.sender, _spender, allowances[msg.sender][_spender].add(_addedValue));
        return true;
    }

    /**
     * @notice Atomically decreases the allowance granted to `_spender` by the caller by `_subtractedValue`.
     *
     * This is an alternative to `approve` that can be used as a mitigation for
     * problems described in:
     * https://github.com/OpenZeppelin/openzeppelin-contracts/blob/b709eae01d1da91902d06ace340df6b324e6f049/contracts/token/ERC20/IERC20.sol#L57
     * 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) external returns (bool) {
        uint256 currentAllowance = allowances[msg.sender][_spender];
        require(currentAllowance >= _subtractedValue, "ALLOWANCE_BELOW_ZERO");
        _approve(msg.sender, _spender, currentAllowance.sub(_subtractedValue));
        return true;
    }

    /**
     * @return the total amount of shares in existence.
     *
     * @dev The sum of all accounts' shares can be an arbitrary number, therefore
     * it is necessary to store it in order to calculate each account's relative share.
     */
    function getTotalShares() external view returns (uint256) {
        return _getTotalShares();
    }

    /**
     * @return the amount of shares owned by `_account`.
     */
    function sharesOf(address _account) external view returns (uint256) {
        return _sharesOf(_account);
    }

    /**
     * @return the amount of shares that corresponds to `_ethAmount` protocol-controlled Ether.
     */
    function getSharesByPooledEth(uint256 _ethAmount) public view returns (uint256) {
        return _ethAmount
            .mul(_getTotalShares())
            .div(_getTotalPooledEther());
    }

    /**
     * @return the amount of Ether that corresponds to `_sharesAmount` token shares.
     */
    function getPooledEthByShares(uint256 _sharesAmount) public view returns (uint256) {
        return _sharesAmount
            .mul(_getTotalPooledEther())
            .div(_getTotalShares());
    }

    /**
     * @notice Moves `_sharesAmount` token shares from the caller's account to the `_recipient` account.
     *
     * @return amount of transferred tokens.
     * Emits a `TransferShares` event.
     * Emits a `Transfer` event.
     *
     * Requirements:
     *
     * - `_recipient` cannot be the zero address.
     * - the caller must have at least `_sharesAmount` shares.
     * - the contract must not be paused.
     *
     * @dev The `_sharesAmount` argument is the amount of shares, not tokens.
     */
    function transferShares(address _recipient, uint256 _sharesAmount) external returns (uint256) {
        _transferShares(msg.sender, _recipient, _sharesAmount);
        uint256 tokensAmount = getPooledEthByShares(_sharesAmount);
        _emitTransferEvents(msg.sender, _recipient, tokensAmount, _sharesAmount);
        return tokensAmount;
    }

    /**
     * @notice Moves `_sharesAmount` token shares from the `_sender` account to the `_recipient` account.
     *
     * @return amount of transferred tokens.
     * Emits a `TransferShares` event.
     * Emits a `Transfer` event.
     *
     * Requirements:
     *
     * - `_sender` and `_recipient` cannot be the zero addresses.
     * - `_sender` must have at least `_sharesAmount` shares.
     * - the caller must have allowance for `_sender`'s tokens of at least `getPooledEthByShares(_sharesAmount)`.
     * - the contract must not be paused.
     *
     * @dev The `_sharesAmount` argument is the amount of shares, not tokens.
     */
    function transferSharesFrom(
        address _sender, address _recipient, uint256 _sharesAmount
    ) external returns (uint256) {
        uint256 tokensAmount = getPooledEthByShares(_sharesAmount);
        _spendAllowance(_sender, msg.sender, tokensAmount);
        _transferShares(_sender, _recipient, _sharesAmount);
        _emitTransferEvents(_sender, _recipient, tokensAmount, _sharesAmount);
        return tokensAmount;
    }

    /**
     * @return the total amount (in wei) of Ether controlled by the protocol.
     * @dev This is used for calculating tokens from shares and vice versa.
     * @dev This function is required to be implemented in a derived contract.
     */
    function _getTotalPooledEther() internal view returns (uint256);

    /**
     * @notice Moves `_amount` tokens from `_sender` to `_recipient`.
     * Emits a `Transfer` event.
     * Emits a `TransferShares` event.
     */
    function _transfer(address _sender, address _recipient, uint256 _amount) internal {
        uint256 _sharesToTransfer = getSharesByPooledEth(_amount);
        _transferShares(_sender, _recipient, _sharesToTransfer);
        _emitTransferEvents(_sender, _recipient, _amount, _sharesToTransfer);
    }

    /**
     * @notice Sets `_amount` as the allowance of `_spender` over the `_owner` s tokens.
     *
     * Emits an `Approval` event.
     *
     * NB: the method can be invoked even if the protocol paused.
     *
     * Requirements:
     *
     * - `_owner` cannot be the zero address.
     * - `_spender` cannot be the zero address.
     */
    function _approve(address _owner, address _spender, uint256 _amount) internal {
        require(_owner != address(0), "APPROVE_FROM_ZERO_ADDR");
        require(_spender != address(0), "APPROVE_TO_ZERO_ADDR");

        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 {
        uint256 currentAllowance = allowances[_owner][_spender];
        if (currentAllowance != INFINITE_ALLOWANCE) {
            require(currentAllowance >= _amount, "ALLOWANCE_EXCEEDED");
            _approve(_owner, _spender, currentAllowance - _amount);
        }
    }

    /**
     * @return the total amount of shares in existence.
     */
    function _getTotalShares() internal view returns (uint256) {
        return TOTAL_SHARES_POSITION.getStorageUint256();
    }

    /**
     * @return the amount of shares owned by `_account`.
     */
    function _sharesOf(address _account) internal view returns (uint256) {
        return shares[_account];
    }

    /**
     * @notice Moves `_sharesAmount` shares from `_sender` to `_recipient`.
     *
     * Requirements:
     *
     * - `_sender` cannot be the zero address.
     * - `_recipient` cannot be the zero address or the `stETH` token contract itself
     * - `_sender` must hold at least `_sharesAmount` shares.
     * - the contract must not be paused.
     */
    function _transferShares(address _sender, address _recipient, uint256 _sharesAmount) internal {
        require(_sender != address(0), "TRANSFER_FROM_ZERO_ADDR");
        require(_recipient != address(0), "TRANSFER_TO_ZERO_ADDR");
        require(_recipient != address(this), "TRANSFER_TO_STETH_CONTRACT");
        _whenNotStopped();

        uint256 currentSenderShares = shares[_sender];
        require(_sharesAmount <= currentSenderShares, "BALANCE_EXCEEDED");

        shares[_sender] = currentSenderShares.sub(_sharesAmount);
        shares[_recipient] = shares[_recipient].add(_sharesAmount);
    }

    /**
     * @notice Creates `_sharesAmount` shares and assigns them to `_recipient`, increasing the total amount of shares.
     * @dev This doesn't increase the token total supply.
     *
     * NB: The method doesn't check protocol pause relying on the external enforcement.
     *
     * Requirements:
     *
     * - `_recipient` cannot be the zero address.
     * - the contract must not be paused.
     */
    function _mintShares(address _recipient, uint256 _sharesAmount) internal returns (uint256 newTotalShares) {
        require(_recipient != address(0), "MINT_TO_ZERO_ADDR");

        newTotalShares = _getTotalShares().add(_sharesAmount);
        TOTAL_SHARES_POSITION.setStorageUint256(newTotalShares);

        shares[_recipient] = shares[_recipient].add(_sharesAmount);

        // Notice: we're not emitting a Transfer event from the zero address here since shares mint
        // works by taking the amount of tokens corresponding to the minted shares from all other
        // token holders, proportionally to their share. The total supply of the token doesn't change
        // as the result. This is equivalent to performing a send from each other token holder's
        // address to `address`, but we cannot reflect this as it would require sending an unbounded
        // number of events.
    }

    /**
     * @notice Destroys `_sharesAmount` shares from `_account`'s holdings, decreasing the total amount of shares.
     * @dev This doesn't decrease the token total supply.
     *
     * Requirements:
     *
     * - `_account` cannot be the zero address.
     * - `_account` must hold at least `_sharesAmount` shares.
     * - the contract must not be paused.
     */
    function _burnShares(address _account, uint256 _sharesAmount) internal returns (uint256 newTotalShares) {
        require(_account != address(0), "BURN_FROM_ZERO_ADDR");

        uint256 accountShares = shares[_account];
        require(_sharesAmount <= accountShares, "BALANCE_EXCEEDED");

        uint256 preRebaseTokenAmount = getPooledEthByShares(_sharesAmount);

        newTotalShares = _getTotalShares().sub(_sharesAmount);
        TOTAL_SHARES_POSITION.setStorageUint256(newTotalShares);

        shares[_account] = accountShares.sub(_sharesAmount);

        uint256 postRebaseTokenAmount = getPooledEthByShares(_sharesAmount);

        emit SharesBurnt(_account, preRebaseTokenAmount, postRebaseTokenAmount, _sharesAmount);

        // Notice: we're not emitting a Transfer event to the zero address here since shares burn
        // works by redistributing the amount of tokens corresponding to the burned shares between
        // all other token holders. The total supply of the token doesn't change as the result.
        // This is equivalent to performing a send from `address` to each other token holder address,
        // but we cannot reflect this as it would require sending an unbounded number of events.

        // We're emitting `SharesBurnt` event to provide an explicit rebase log record nonetheless.
    }

    /**
     * @dev Emits {Transfer} and {TransferShares} events
     */
    function _emitTransferEvents(address _from, address _to, uint _tokenAmount, uint256 _sharesAmount) internal {
        emit Transfer(_from, _to, _tokenAmount);
        emit TransferShares(_from, _to, _sharesAmount);
    }

    /**
     * @dev Emits {Transfer} and {TransferShares} events where `from` is 0 address. Indicates mint events.
     */
    function _emitTransferAfterMintingShares(address _to, uint256 _sharesAmount) internal {
        _emitTransferEvents(address(0), _to, getPooledEthByShares(_sharesAmount), _sharesAmount);
    }

    /**
     * @dev Mints shares to INITIAL_TOKEN_HOLDER
     */
    function _mintInitialShares(uint256 _sharesAmount) internal {
        _mintShares(INITIAL_TOKEN_HOLDER, _sharesAmount);
        _emitTransferAfterMintingShares(INITIAL_TOKEN_HOLDER, _sharesAmount);
    }
}
          

// See https://github.com/OpenZeppelin/openzeppelin-solidity/blob/d51e38758e1d985661534534d5c61e27bece5042/contracts/math/SafeMath.sol
// Adapted to use pragma ^0.4.24 and satisfy our linter rules

pragma solidity ^0.4.24;


/**
 * @title SafeMath
 * @dev Math operations with safety checks that revert on error
 */
library SafeMath {
    string private constant ERROR_ADD_OVERFLOW = "MATH_ADD_OVERFLOW";
    string private constant ERROR_SUB_UNDERFLOW = "MATH_SUB_UNDERFLOW";
    string private constant ERROR_MUL_OVERFLOW = "MATH_MUL_OVERFLOW";
    string private constant ERROR_DIV_ZERO = "MATH_DIV_ZERO";

    /**
    * @dev Multiplies two numbers, reverts on overflow.
    */
    function mul(uint256 _a, uint256 _b) internal pure returns (uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
        if (_a == 0) {
            return 0;
        }

        uint256 c = _a * _b;
        require(c / _a == _b, ERROR_MUL_OVERFLOW);

        return c;
    }

    /**
    * @dev Integer division of two numbers truncating the quotient, reverts on division by zero.
    */
    function div(uint256 _a, uint256 _b) internal pure returns (uint256) {
        require(_b > 0, ERROR_DIV_ZERO); // Solidity only automatically asserts when dividing by 0
        uint256 c = _a / _b;
        // assert(_a == _b * c + _a % _b); // There is no case in which this doesn't hold

        return c;
    }

    /**
    * @dev Subtracts two numbers, reverts on overflow (i.e. if subtrahend is greater than minuend).
    */
    function sub(uint256 _a, uint256 _b) internal pure returns (uint256) {
        require(_b <= _a, ERROR_SUB_UNDERFLOW);
        uint256 c = _a - _b;

        return c;
    }

    /**
    * @dev Adds two numbers, reverts on overflow.
    */
    function add(uint256 _a, uint256 _b) internal pure returns (uint256) {
        uint256 c = _a + _b;
        require(c >= _a, ERROR_ADD_OVERFLOW);

        return c;
    }

    /**
    * @dev Divides two numbers and returns the remainder (unsigned integer modulo),
    * reverts when dividing by zero.
    */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b != 0, ERROR_DIV_ZERO);
        return a % b;
    }
}
          

/*
 * SPDX-License-Identifier:    MIT
 */

pragma solidity ^0.4.24;

import "./TimeHelpers.sol";
import "./UnstructuredStorage.sol";


contract Initializable is TimeHelpers {
    using UnstructuredStorage for bytes32;

    // keccak256("aragonOS.initializable.initializationBlock")
    bytes32 internal constant INITIALIZATION_BLOCK_POSITION = 0xebb05b386a8d34882b8711d156f463690983dc47815980fb82aeeff1aa43579e;

    string private constant ERROR_ALREADY_INITIALIZED = "INIT_ALREADY_INITIALIZED";
    string private constant ERROR_NOT_INITIALIZED = "INIT_NOT_INITIALIZED";

    modifier onlyInit {
        require(getInitializationBlock() == 0, ERROR_ALREADY_INITIALIZED);
        _;
    }

    modifier isInitialized {
        require(hasInitialized(), ERROR_NOT_INITIALIZED);
        _;
    }

    /**
    * @return Block number in which the contract was initialized
    */
    function getInitializationBlock() public view returns (uint256) {
        return INITIALIZATION_BLOCK_POSITION.getStorageUint256();
    }

    /**
    * @return Whether the contract has been initialized by the time of the current block
    */
    function hasInitialized() public view returns (bool) {
        uint256 initializationBlock = getInitializationBlock();
        return initializationBlock != 0 && getBlockNumber() >= initializationBlock;
    }

    /**
    * @dev Function to be called by top level contract after initialization has finished.
    */
    function initialized() internal onlyInit {
        INITIALIZATION_BLOCK_POSITION.setStorageUint256(getBlockNumber());
    }

    /**
    * @dev Function to be called by top level contract after initialization to enable the contract
    *      at a future block number rather than immediately.
    */
    function initializedAt(uint256 _blockNumber) internal onlyInit {
        INITIALIZATION_BLOCK_POSITION.setStorageUint256(_blockNumber);
    }
}
          

/*
 * SPDX-License-Identifier:    MIT
 */

pragma solidity ^0.4.24;

import "./Petrifiable.sol";


contract Autopetrified is Petrifiable {
    constructor() public {
        // Immediately petrify base (non-proxy) instances of inherited contracts on deploy.
        // This renders them uninitializable (and unusable without a proxy).
        petrify();
    }
}