ETH Price: $3,814.95 (-2.09%)
Gas: 9 Gwei

Transaction Decoder

Block:
17620527 at Jul-04-2023 12:21:23 PM +UTC
Transaction Fee:
0.000432818693746753 ETH $1.65
Gas Used:
27,329 Gas / 15.837341057 Gwei

Emitted Events:

234 GnosisSafeProxy.0x3d0ce9bfc3ed7d6862dbb28b2dea94561fe714a1b4d019aa8af39730d1ad7c3d( 0x3d0ce9bfc3ed7d6862dbb28b2dea94561fe714a1b4d019aa8af39730d1ad7c3d, 0x000000000000000000000000dafea492d9c6733ae3d56b7ed1adb60692c98bc5, 00000000000000000000000000000000000000000000000002b62a42f027e54b )

Account State Difference:

  Address   Before After State Difference Code
0x30140742...88Fe45681
(Ether Capital: ETH Staking Multisig)
9,724.272464211879499947 Eth9,724.467854312702049782 Eth0.195390100822549835
(Flashbots: Builder)
0.20009601599741669 Eth
Nonce: 380862
0.004273096481120102 Eth
Nonce: 380863
0.195822919516296588

Execution Trace

ETH 0.195390100822549835 GnosisSafeProxy.CALL( )
  • ETH 0.195390100822549835 GnosisSafe.DELEGATECALL( )
    File 1 of 2: GnosisSafeProxy
    // SPDX-License-Identifier: LGPL-3.0-only
    pragma solidity >=0.7.0 <0.9.0;
    
    /// @title IProxy - Helper interface to access masterCopy of the Proxy on-chain
    /// @author Richard Meissner - <[email protected]>
    interface IProxy {
        function masterCopy() external view returns (address);
    }
    
    /// @title GnosisSafeProxy - Generic proxy contract allows to execute all transactions applying the code of a master contract.
    /// @author Stefan George - <[email protected]>
    /// @author Richard Meissner - <[email protected]>
    contract GnosisSafeProxy {
        // singleton always needs to be first declared variable, to ensure that it is at the same location in the contracts to which calls are delegated.
        // To reduce deployment costs this variable is internal and needs to be retrieved via `getStorageAt`
        address internal singleton;
    
        /// @dev Constructor function sets address of singleton contract.
        /// @param _singleton Singleton address.
        constructor(address _singleton) {
            require(_singleton != address(0), "Invalid singleton address provided");
            singleton = _singleton;
        }
    
        /// @dev Fallback function forwards all transactions and returns all received return data.
        fallback() external payable {
            // solhint-disable-next-line no-inline-assembly
            assembly {
                let _singleton := and(sload(0), 0xffffffffffffffffffffffffffffffffffffffff)
                // 0xa619486e == keccak("masterCopy()"). The value is right padded to 32-bytes with 0s
                if eq(calldataload(0), 0xa619486e00000000000000000000000000000000000000000000000000000000) {
                    mstore(0, _singleton)
                    return(0, 0x20)
                }
                calldatacopy(0, 0, calldatasize())
                let success := delegatecall(gas(), _singleton, 0, calldatasize(), 0, 0)
                returndatacopy(0, 0, returndatasize())
                if eq(success, 0) {
                    revert(0, returndatasize())
                }
                return(0, returndatasize())
            }
        }
    }
    
    /// @title Proxy Factory - Allows to create new proxy contact and execute a message call to the new proxy within one transaction.
    /// @author Stefan George - <[email protected]>
    contract GnosisSafeProxyFactory {
        event ProxyCreation(GnosisSafeProxy proxy, address singleton);
    
        /// @dev Allows to create new proxy contact and execute a message call to the new proxy within one transaction.
        /// @param singleton Address of singleton contract.
        /// @param data Payload for message call sent to new proxy contract.
        function createProxy(address singleton, bytes memory data) public returns (GnosisSafeProxy proxy) {
            proxy = new GnosisSafeProxy(singleton);
            if (data.length > 0)
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    if eq(call(gas(), proxy, 0, add(data, 0x20), mload(data), 0, 0), 0) {
                        revert(0, 0)
                    }
                }
            emit ProxyCreation(proxy, singleton);
        }
    
        /// @dev Allows to retrieve the runtime code of a deployed Proxy. This can be used to check that the expected Proxy was deployed.
        function proxyRuntimeCode() public pure returns (bytes memory) {
            return type(GnosisSafeProxy).runtimeCode;
        }
    
        /// @dev Allows to retrieve the creation code used for the Proxy deployment. With this it is easily possible to calculate predicted address.
        function proxyCreationCode() public pure returns (bytes memory) {
            return type(GnosisSafeProxy).creationCode;
        }
    
        /// @dev Allows to create new proxy contact using CREATE2 but it doesn't run the initializer.
        ///      This method is only meant as an utility to be called from other methods
        /// @param _singleton Address of singleton contract.
        /// @param initializer Payload for message call sent to new proxy contract.
        /// @param saltNonce Nonce that will be used to generate the salt to calculate the address of the new proxy contract.
        function deployProxyWithNonce(
            address _singleton,
            bytes memory initializer,
            uint256 saltNonce
        ) internal returns (GnosisSafeProxy proxy) {
            // If the initializer changes the proxy address should change too. Hashing the initializer data is cheaper than just concatinating it
            bytes32 salt = keccak256(abi.encodePacked(keccak256(initializer), saltNonce));
            bytes memory deploymentData = abi.encodePacked(type(GnosisSafeProxy).creationCode, uint256(uint160(_singleton)));
            // solhint-disable-next-line no-inline-assembly
            assembly {
                proxy := create2(0x0, add(0x20, deploymentData), mload(deploymentData), salt)
            }
            require(address(proxy) != address(0), "Create2 call failed");
        }
    
        /// @dev Allows to create new proxy contact and execute a message call to the new proxy within one transaction.
        /// @param _singleton Address of singleton contract.
        /// @param initializer Payload for message call sent to new proxy contract.
        /// @param saltNonce Nonce that will be used to generate the salt to calculate the address of the new proxy contract.
        function createProxyWithNonce(
            address _singleton,
            bytes memory initializer,
            uint256 saltNonce
        ) public returns (GnosisSafeProxy proxy) {
            proxy = deployProxyWithNonce(_singleton, initializer, saltNonce);
            if (initializer.length > 0)
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    if eq(call(gas(), proxy, 0, add(initializer, 0x20), mload(initializer), 0, 0), 0) {
                        revert(0, 0)
                    }
                }
            emit ProxyCreation(proxy, _singleton);
        }
    
        /// @dev Allows to create new proxy contact, execute a message call to the new proxy and call a specified callback within one transaction
        /// @param _singleton Address of singleton contract.
        /// @param initializer Payload for message call sent to new proxy contract.
        /// @param saltNonce Nonce that will be used to generate the salt to calculate the address of the new proxy contract.
        /// @param callback Callback that will be invoced after the new proxy contract has been successfully deployed and initialized.
        function createProxyWithCallback(
            address _singleton,
            bytes memory initializer,
            uint256 saltNonce,
            IProxyCreationCallback callback
        ) public returns (GnosisSafeProxy proxy) {
            uint256 saltNonceWithCallback = uint256(keccak256(abi.encodePacked(saltNonce, callback)));
            proxy = createProxyWithNonce(_singleton, initializer, saltNonceWithCallback);
            if (address(callback) != address(0)) callback.proxyCreated(proxy, _singleton, initializer, saltNonce);
        }
    
        /// @dev Allows to get the address for a new proxy contact created via `createProxyWithNonce`
        ///      This method is only meant for address calculation purpose when you use an initializer that would revert,
        ///      therefore the response is returned with a revert. When calling this method set `from` to the address of the proxy factory.
        /// @param _singleton Address of singleton contract.
        /// @param initializer Payload for message call sent to new proxy contract.
        /// @param saltNonce Nonce that will be used to generate the salt to calculate the address of the new proxy contract.
        function calculateCreateProxyWithNonceAddress(
            address _singleton,
            bytes calldata initializer,
            uint256 saltNonce
        ) external returns (GnosisSafeProxy proxy) {
            proxy = deployProxyWithNonce(_singleton, initializer, saltNonce);
            revert(string(abi.encodePacked(proxy)));
        }
    }
    
    interface IProxyCreationCallback {
        function proxyCreated(
            GnosisSafeProxy proxy,
            address _singleton,
            bytes calldata initializer,
            uint256 saltNonce
        ) external;
    }

    File 2 of 2: GnosisSafe
    // SPDX-License-Identifier: LGPL-3.0-only
    pragma solidity >=0.7.0 <0.9.0;
    import "./base/ModuleManager.sol";
    import "./base/OwnerManager.sol";
    import "./base/FallbackManager.sol";
    import "./base/GuardManager.sol";
    import "./common/EtherPaymentFallback.sol";
    import "./common/Singleton.sol";
    import "./common/SignatureDecoder.sol";
    import "./common/SecuredTokenTransfer.sol";
    import "./common/StorageAccessible.sol";
    import "./interfaces/ISignatureValidator.sol";
    import "./external/GnosisSafeMath.sol";
    /// @title Gnosis Safe - A multisignature wallet with support for confirmations using signed messages based on ERC191.
    /// @author Stefan George - <[email protected]>
    /// @author Richard Meissner - <[email protected]>
    contract GnosisSafe is
        EtherPaymentFallback,
        Singleton,
        ModuleManager,
        OwnerManager,
        SignatureDecoder,
        SecuredTokenTransfer,
        ISignatureValidatorConstants,
        FallbackManager,
        StorageAccessible,
        GuardManager
    {
        using GnosisSafeMath for uint256;
        string public constant VERSION = "1.3.0";
        // keccak256(
        //     "EIP712Domain(uint256 chainId,address verifyingContract)"
        // );
        bytes32 private constant DOMAIN_SEPARATOR_TYPEHASH = 0x47e79534a245952e8b16893a336b85a3d9ea9fa8c573f3d803afb92a79469218;
        // keccak256(
        //     "SafeTx(address to,uint256 value,bytes data,uint8 operation,uint256 safeTxGas,uint256 baseGas,uint256 gasPrice,address gasToken,address refundReceiver,uint256 nonce)"
        // );
        bytes32 private constant SAFE_TX_TYPEHASH = 0xbb8310d486368db6bd6f849402fdd73ad53d316b5a4b2644ad6efe0f941286d8;
        event SafeSetup(address indexed initiator, address[] owners, uint256 threshold, address initializer, address fallbackHandler);
        event ApproveHash(bytes32 indexed approvedHash, address indexed owner);
        event SignMsg(bytes32 indexed msgHash);
        event ExecutionFailure(bytes32 txHash, uint256 payment);
        event ExecutionSuccess(bytes32 txHash, uint256 payment);
        uint256 public nonce;
        bytes32 private _deprecatedDomainSeparator;
        // Mapping to keep track of all message hashes that have been approve by ALL REQUIRED owners
        mapping(bytes32 => uint256) public signedMessages;
        // Mapping to keep track of all hashes (message or transaction) that have been approve by ANY owners
        mapping(address => mapping(bytes32 => uint256)) public approvedHashes;
        // This constructor ensures that this contract can only be used as a master copy for Proxy contracts
        constructor() {
            // By setting the threshold it is not possible to call setup anymore,
            // so we create a Safe with 0 owners and threshold 1.
            // This is an unusable Safe, perfect for the singleton
            threshold = 1;
        }
        /// @dev Setup function sets initial storage of contract.
        /// @param _owners List of Safe owners.
        /// @param _threshold Number of required confirmations for a Safe transaction.
        /// @param to Contract address for optional delegate call.
        /// @param data Data payload for optional delegate call.
        /// @param fallbackHandler Handler for fallback calls to this contract
        /// @param paymentToken Token that should be used for the payment (0 is ETH)
        /// @param payment Value that should be paid
        /// @param paymentReceiver Adddress that should receive the payment (or 0 if tx.origin)
        function setup(
            address[] calldata _owners,
            uint256 _threshold,
            address to,
            bytes calldata data,
            address fallbackHandler,
            address paymentToken,
            uint256 payment,
            address payable paymentReceiver
        ) external {
            // setupOwners checks if the Threshold is already set, therefore preventing that this method is called twice
            setupOwners(_owners, _threshold);
            if (fallbackHandler != address(0)) internalSetFallbackHandler(fallbackHandler);
            // As setupOwners can only be called if the contract has not been initialized we don't need a check for setupModules
            setupModules(to, data);
            if (payment > 0) {
                // To avoid running into issues with EIP-170 we reuse the handlePayment function (to avoid adjusting code of that has been verified we do not adjust the method itself)
                // baseGas = 0, gasPrice = 1 and gas = payment => amount = (payment + 0) * 1 = payment
                handlePayment(payment, 0, 1, paymentToken, paymentReceiver);
            }
            emit SafeSetup(msg.sender, _owners, _threshold, to, fallbackHandler);
        }
        /// @dev Allows to execute a Safe transaction confirmed by required number of owners and then pays the account that submitted the transaction.
        ///      Note: The fees are always transferred, even if the user transaction fails.
        /// @param to Destination address of Safe transaction.
        /// @param value Ether value of Safe transaction.
        /// @param data Data payload of Safe transaction.
        /// @param operation Operation type of Safe transaction.
        /// @param safeTxGas Gas that should be used for the Safe transaction.
        /// @param baseGas Gas costs that are independent of the transaction execution(e.g. base transaction fee, signature check, payment of the refund)
        /// @param gasPrice Gas price that should be used for the payment calculation.
        /// @param gasToken Token address (or 0 if ETH) that is used for the payment.
        /// @param refundReceiver Address of receiver of gas payment (or 0 if tx.origin).
        /// @param signatures Packed signature data ({bytes32 r}{bytes32 s}{uint8 v})
        function execTransaction(
            address to,
            uint256 value,
            bytes calldata data,
            Enum.Operation operation,
            uint256 safeTxGas,
            uint256 baseGas,
            uint256 gasPrice,
            address gasToken,
            address payable refundReceiver,
            bytes memory signatures
        ) public payable virtual returns (bool success) {
            bytes32 txHash;
            // Use scope here to limit variable lifetime and prevent `stack too deep` errors
            {
                bytes memory txHashData =
                    encodeTransactionData(
                        // Transaction info
                        to,
                        value,
                        data,
                        operation,
                        safeTxGas,
                        // Payment info
                        baseGas,
                        gasPrice,
                        gasToken,
                        refundReceiver,
                        // Signature info
                        nonce
                    );
                // Increase nonce and execute transaction.
                nonce++;
                txHash = keccak256(txHashData);
                checkSignatures(txHash, txHashData, signatures);
            }
            address guard = getGuard();
            {
                if (guard != address(0)) {
                    Guard(guard).checkTransaction(
                        // Transaction info
                        to,
                        value,
                        data,
                        operation,
                        safeTxGas,
                        // Payment info
                        baseGas,
                        gasPrice,
                        gasToken,
                        refundReceiver,
                        // Signature info
                        signatures,
                        msg.sender
                    );
                }
            }
            // We require some gas to emit the events (at least 2500) after the execution and some to perform code until the execution (500)
            // We also include the 1/64 in the check that is not send along with a call to counteract potential shortings because of EIP-150
            require(gasleft() >= ((safeTxGas * 64) / 63).max(safeTxGas + 2500) + 500, "GS010");
            // Use scope here to limit variable lifetime and prevent `stack too deep` errors
            {
                uint256 gasUsed = gasleft();
                // If the gasPrice is 0 we assume that nearly all available gas can be used (it is always more than safeTxGas)
                // We only substract 2500 (compared to the 3000 before) to ensure that the amount passed is still higher than safeTxGas
                success = execute(to, value, data, operation, gasPrice == 0 ? (gasleft() - 2500) : safeTxGas);
                gasUsed = gasUsed.sub(gasleft());
                // If no safeTxGas and no gasPrice was set (e.g. both are 0), then the internal tx is required to be successful
                // This makes it possible to use `estimateGas` without issues, as it searches for the minimum gas where the tx doesn't revert
                require(success || safeTxGas != 0 || gasPrice != 0, "GS013");
                // We transfer the calculated tx costs to the tx.origin to avoid sending it to intermediate contracts that have made calls
                uint256 payment = 0;
                if (gasPrice > 0) {
                    payment = handlePayment(gasUsed, baseGas, gasPrice, gasToken, refundReceiver);
                }
                if (success) emit ExecutionSuccess(txHash, payment);
                else emit ExecutionFailure(txHash, payment);
            }
            {
                if (guard != address(0)) {
                    Guard(guard).checkAfterExecution(txHash, success);
                }
            }
        }
        function handlePayment(
            uint256 gasUsed,
            uint256 baseGas,
            uint256 gasPrice,
            address gasToken,
            address payable refundReceiver
        ) private returns (uint256 payment) {
            // solhint-disable-next-line avoid-tx-origin
            address payable receiver = refundReceiver == address(0) ? payable(tx.origin) : refundReceiver;
            if (gasToken == address(0)) {
                // For ETH we will only adjust the gas price to not be higher than the actual used gas price
                payment = gasUsed.add(baseGas).mul(gasPrice < tx.gasprice ? gasPrice : tx.gasprice);
                require(receiver.send(payment), "GS011");
            } else {
                payment = gasUsed.add(baseGas).mul(gasPrice);
                require(transferToken(gasToken, receiver, payment), "GS012");
            }
        }
        /**
         * @dev Checks whether the signature provided is valid for the provided data, hash. Will revert otherwise.
         * @param dataHash Hash of the data (could be either a message hash or transaction hash)
         * @param data That should be signed (this is passed to an external validator contract)
         * @param signatures Signature data that should be verified. Can be ECDSA signature, contract signature (EIP-1271) or approved hash.
         */
        function checkSignatures(
            bytes32 dataHash,
            bytes memory data,
            bytes memory signatures
        ) public view {
            // Load threshold to avoid multiple storage loads
            uint256 _threshold = threshold;
            // Check that a threshold is set
            require(_threshold > 0, "GS001");
            checkNSignatures(dataHash, data, signatures, _threshold);
        }
        /**
         * @dev Checks whether the signature provided is valid for the provided data, hash. Will revert otherwise.
         * @param dataHash Hash of the data (could be either a message hash or transaction hash)
         * @param data That should be signed (this is passed to an external validator contract)
         * @param signatures Signature data that should be verified. Can be ECDSA signature, contract signature (EIP-1271) or approved hash.
         * @param requiredSignatures Amount of required valid signatures.
         */
        function checkNSignatures(
            bytes32 dataHash,
            bytes memory data,
            bytes memory signatures,
            uint256 requiredSignatures
        ) public view {
            // Check that the provided signature data is not too short
            require(signatures.length >= requiredSignatures.mul(65), "GS020");
            // There cannot be an owner with address 0.
            address lastOwner = address(0);
            address currentOwner;
            uint8 v;
            bytes32 r;
            bytes32 s;
            uint256 i;
            for (i = 0; i < requiredSignatures; i++) {
                (v, r, s) = signatureSplit(signatures, i);
                if (v == 0) {
                    // If v is 0 then it is a contract signature
                    // When handling contract signatures the address of the contract is encoded into r
                    currentOwner = address(uint160(uint256(r)));
                    // Check that signature data pointer (s) is not pointing inside the static part of the signatures bytes
                    // This check is not completely accurate, since it is possible that more signatures than the threshold are send.
                    // Here we only check that the pointer is not pointing inside the part that is being processed
                    require(uint256(s) >= requiredSignatures.mul(65), "GS021");
                    // Check that signature data pointer (s) is in bounds (points to the length of data -> 32 bytes)
                    require(uint256(s).add(32) <= signatures.length, "GS022");
                    // Check if the contract signature is in bounds: start of data is s + 32 and end is start + signature length
                    uint256 contractSignatureLen;
                    // solhint-disable-next-line no-inline-assembly
                    assembly {
                        contractSignatureLen := mload(add(add(signatures, s), 0x20))
                    }
                    require(uint256(s).add(32).add(contractSignatureLen) <= signatures.length, "GS023");
                    // Check signature
                    bytes memory contractSignature;
                    // solhint-disable-next-line no-inline-assembly
                    assembly {
                        // The signature data for contract signatures is appended to the concatenated signatures and the offset is stored in s
                        contractSignature := add(add(signatures, s), 0x20)
                    }
                    require(ISignatureValidator(currentOwner).isValidSignature(data, contractSignature) == EIP1271_MAGIC_VALUE, "GS024");
                } else if (v == 1) {
                    // If v is 1 then it is an approved hash
                    // When handling approved hashes the address of the approver is encoded into r
                    currentOwner = address(uint160(uint256(r)));
                    // Hashes are automatically approved by the sender of the message or when they have been pre-approved via a separate transaction
                    require(msg.sender == currentOwner || approvedHashes[currentOwner][dataHash] != 0, "GS025");
                } else if (v > 30) {
                    // If v > 30 then default va (27,28) has been adjusted for eth_sign flow
                    // To support eth_sign and similar we adjust v and hash the messageHash with the Ethereum message prefix before applying ecrecover
                    currentOwner = ecrecover(keccak256(abi.encodePacked("\\x19Ethereum Signed Message:\
    32", dataHash)), v - 4, r, s);
                } else {
                    // Default is the ecrecover flow with the provided data hash
                    // Use ecrecover with the messageHash for EOA signatures
                    currentOwner = ecrecover(dataHash, v, r, s);
                }
                require(currentOwner > lastOwner && owners[currentOwner] != address(0) && currentOwner != SENTINEL_OWNERS, "GS026");
                lastOwner = currentOwner;
            }
        }
        /// @dev Allows to estimate a Safe transaction.
        ///      This method is only meant for estimation purpose, therefore the call will always revert and encode the result in the revert data.
        ///      Since the `estimateGas` function includes refunds, call this method to get an estimated of the costs that are deducted from the safe with `execTransaction`
        /// @param to Destination address of Safe transaction.
        /// @param value Ether value of Safe transaction.
        /// @param data Data payload of Safe transaction.
        /// @param operation Operation type of Safe transaction.
        /// @return Estimate without refunds and overhead fees (base transaction and payload data gas costs).
        /// @notice Deprecated in favor of common/StorageAccessible.sol and will be removed in next version.
        function requiredTxGas(
            address to,
            uint256 value,
            bytes calldata data,
            Enum.Operation operation
        ) external returns (uint256) {
            uint256 startGas = gasleft();
            // We don't provide an error message here, as we use it to return the estimate
            require(execute(to, value, data, operation, gasleft()));
            uint256 requiredGas = startGas - gasleft();
            // Convert response to string and return via error message
            revert(string(abi.encodePacked(requiredGas)));
        }
        /**
         * @dev Marks a hash as approved. This can be used to validate a hash that is used by a signature.
         * @param hashToApprove The hash that should be marked as approved for signatures that are verified by this contract.
         */
        function approveHash(bytes32 hashToApprove) external {
            require(owners[msg.sender] != address(0), "GS030");
            approvedHashes[msg.sender][hashToApprove] = 1;
            emit ApproveHash(hashToApprove, msg.sender);
        }
        /// @dev Returns the chain id used by this contract.
        function getChainId() public view returns (uint256) {
            uint256 id;
            // solhint-disable-next-line no-inline-assembly
            assembly {
                id := chainid()
            }
            return id;
        }
        function domainSeparator() public view returns (bytes32) {
            return keccak256(abi.encode(DOMAIN_SEPARATOR_TYPEHASH, getChainId(), this));
        }
        /// @dev Returns the bytes that are hashed to be signed by owners.
        /// @param to Destination address.
        /// @param value Ether value.
        /// @param data Data payload.
        /// @param operation Operation type.
        /// @param safeTxGas Gas that should be used for the safe transaction.
        /// @param baseGas Gas costs for that are independent of the transaction execution(e.g. base transaction fee, signature check, payment of the refund)
        /// @param gasPrice Maximum gas price that should be used for this transaction.
        /// @param gasToken Token address (or 0 if ETH) that is used for the payment.
        /// @param refundReceiver Address of receiver of gas payment (or 0 if tx.origin).
        /// @param _nonce Transaction nonce.
        /// @return Transaction hash bytes.
        function encodeTransactionData(
            address to,
            uint256 value,
            bytes calldata data,
            Enum.Operation operation,
            uint256 safeTxGas,
            uint256 baseGas,
            uint256 gasPrice,
            address gasToken,
            address refundReceiver,
            uint256 _nonce
        ) public view returns (bytes memory) {
            bytes32 safeTxHash =
                keccak256(
                    abi.encode(
                        SAFE_TX_TYPEHASH,
                        to,
                        value,
                        keccak256(data),
                        operation,
                        safeTxGas,
                        baseGas,
                        gasPrice,
                        gasToken,
                        refundReceiver,
                        _nonce
                    )
                );
            return abi.encodePacked(bytes1(0x19), bytes1(0x01), domainSeparator(), safeTxHash);
        }
        /// @dev Returns hash to be signed by owners.
        /// @param to Destination address.
        /// @param value Ether value.
        /// @param data Data payload.
        /// @param operation Operation type.
        /// @param safeTxGas Fas that should be used for the safe transaction.
        /// @param baseGas Gas costs for data used to trigger the safe transaction.
        /// @param gasPrice Maximum gas price that should be used for this transaction.
        /// @param gasToken Token address (or 0 if ETH) that is used for the payment.
        /// @param refundReceiver Address of receiver of gas payment (or 0 if tx.origin).
        /// @param _nonce Transaction nonce.
        /// @return Transaction hash.
        function getTransactionHash(
            address to,
            uint256 value,
            bytes calldata data,
            Enum.Operation operation,
            uint256 safeTxGas,
            uint256 baseGas,
            uint256 gasPrice,
            address gasToken,
            address refundReceiver,
            uint256 _nonce
        ) public view returns (bytes32) {
            return keccak256(encodeTransactionData(to, value, data, operation, safeTxGas, baseGas, gasPrice, gasToken, refundReceiver, _nonce));
        }
    }
    // SPDX-License-Identifier: LGPL-3.0-only
    pragma solidity >=0.7.0 <0.9.0;
    import "../common/Enum.sol";
    /// @title Executor - A contract that can execute transactions
    /// @author Richard Meissner - <[email protected]>
    contract Executor {
        function execute(
            address to,
            uint256 value,
            bytes memory data,
            Enum.Operation operation,
            uint256 txGas
        ) internal returns (bool success) {
            if (operation == Enum.Operation.DelegateCall) {
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    success := delegatecall(txGas, to, add(data, 0x20), mload(data), 0, 0)
                }
            } else {
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    success := call(txGas, to, value, add(data, 0x20), mload(data), 0, 0)
                }
            }
        }
    }
    // SPDX-License-Identifier: LGPL-3.0-only
    pragma solidity >=0.7.0 <0.9.0;
    import "../common/SelfAuthorized.sol";
    /// @title Fallback Manager - A contract that manages fallback calls made to this contract
    /// @author Richard Meissner - <[email protected]>
    contract FallbackManager is SelfAuthorized {
        event ChangedFallbackHandler(address handler);
        // keccak256("fallback_manager.handler.address")
        bytes32 internal constant FALLBACK_HANDLER_STORAGE_SLOT = 0x6c9a6c4a39284e37ed1cf53d337577d14212a4870fb976a4366c693b939918d5;
        function internalSetFallbackHandler(address handler) internal {
            bytes32 slot = FALLBACK_HANDLER_STORAGE_SLOT;
            // solhint-disable-next-line no-inline-assembly
            assembly {
                sstore(slot, handler)
            }
        }
        /// @dev Allows to add a contract to handle fallback calls.
        ///      Only fallback calls without value and with data will be forwarded.
        ///      This can only be done via a Safe transaction.
        /// @param handler contract to handle fallbacks calls.
        function setFallbackHandler(address handler) public authorized {
            internalSetFallbackHandler(handler);
            emit ChangedFallbackHandler(handler);
        }
        // solhint-disable-next-line payable-fallback,no-complex-fallback
        fallback() external {
            bytes32 slot = FALLBACK_HANDLER_STORAGE_SLOT;
            // solhint-disable-next-line no-inline-assembly
            assembly {
                let handler := sload(slot)
                if iszero(handler) {
                    return(0, 0)
                }
                calldatacopy(0, 0, calldatasize())
                // The msg.sender address is shifted to the left by 12 bytes to remove the padding
                // Then the address without padding is stored right after the calldata
                mstore(calldatasize(), shl(96, caller()))
                // Add 20 bytes for the address appended add the end
                let success := call(gas(), handler, 0, 0, add(calldatasize(), 20), 0, 0)
                returndatacopy(0, 0, returndatasize())
                if iszero(success) {
                    revert(0, returndatasize())
                }
                return(0, returndatasize())
            }
        }
    }
    // SPDX-License-Identifier: LGPL-3.0-only
    pragma solidity >=0.7.0 <0.9.0;
    import "../common/Enum.sol";
    import "../common/SelfAuthorized.sol";
    interface Guard {
        function checkTransaction(
            address to,
            uint256 value,
            bytes memory data,
            Enum.Operation operation,
            uint256 safeTxGas,
            uint256 baseGas,
            uint256 gasPrice,
            address gasToken,
            address payable refundReceiver,
            bytes memory signatures,
            address msgSender
        ) external;
        function checkAfterExecution(bytes32 txHash, bool success) external;
    }
    /// @title Fallback Manager - A contract that manages fallback calls made to this contract
    /// @author Richard Meissner - <[email protected]>
    contract GuardManager is SelfAuthorized {
        event ChangedGuard(address guard);
        // keccak256("guard_manager.guard.address")
        bytes32 internal constant GUARD_STORAGE_SLOT = 0x4a204f620c8c5ccdca3fd54d003badd85ba500436a431f0cbda4f558c93c34c8;
        /// @dev Set a guard that checks transactions before execution
        /// @param guard The address of the guard to be used or the 0 address to disable the guard
        function setGuard(address guard) external authorized {
            bytes32 slot = GUARD_STORAGE_SLOT;
            // solhint-disable-next-line no-inline-assembly
            assembly {
                sstore(slot, guard)
            }
            emit ChangedGuard(guard);
        }
        function getGuard() internal view returns (address guard) {
            bytes32 slot = GUARD_STORAGE_SLOT;
            // solhint-disable-next-line no-inline-assembly
            assembly {
                guard := sload(slot)
            }
        }
    }
    // SPDX-License-Identifier: LGPL-3.0-only
    pragma solidity >=0.7.0 <0.9.0;
    import "../common/Enum.sol";
    import "../common/SelfAuthorized.sol";
    import "./Executor.sol";
    /// @title Module Manager - A contract that manages modules that can execute transactions via this contract
    /// @author Stefan George - <[email protected]>
    /// @author Richard Meissner - <[email protected]>
    contract ModuleManager is SelfAuthorized, Executor {
        event EnabledModule(address module);
        event DisabledModule(address module);
        event ExecutionFromModuleSuccess(address indexed module);
        event ExecutionFromModuleFailure(address indexed module);
        address internal constant SENTINEL_MODULES = address(0x1);
        mapping(address => address) internal modules;
        function setupModules(address to, bytes memory data) internal {
            require(modules[SENTINEL_MODULES] == address(0), "GS100");
            modules[SENTINEL_MODULES] = SENTINEL_MODULES;
            if (to != address(0))
                // Setup has to complete successfully or transaction fails.
                require(execute(to, 0, data, Enum.Operation.DelegateCall, gasleft()), "GS000");
        }
        /// @dev Allows to add a module to the whitelist.
        ///      This can only be done via a Safe transaction.
        /// @notice Enables the module `module` for the Safe.
        /// @param module Module to be whitelisted.
        function enableModule(address module) public authorized {
            // Module address cannot be null or sentinel.
            require(module != address(0) && module != SENTINEL_MODULES, "GS101");
            // Module cannot be added twice.
            require(modules[module] == address(0), "GS102");
            modules[module] = modules[SENTINEL_MODULES];
            modules[SENTINEL_MODULES] = module;
            emit EnabledModule(module);
        }
        /// @dev Allows to remove a module from the whitelist.
        ///      This can only be done via a Safe transaction.
        /// @notice Disables the module `module` for the Safe.
        /// @param prevModule Module that pointed to the module to be removed in the linked list
        /// @param module Module to be removed.
        function disableModule(address prevModule, address module) public authorized {
            // Validate module address and check that it corresponds to module index.
            require(module != address(0) && module != SENTINEL_MODULES, "GS101");
            require(modules[prevModule] == module, "GS103");
            modules[prevModule] = modules[module];
            modules[module] = address(0);
            emit DisabledModule(module);
        }
        /// @dev Allows a Module to execute a Safe transaction without any further confirmations.
        /// @param to Destination address of module transaction.
        /// @param value Ether value of module transaction.
        /// @param data Data payload of module transaction.
        /// @param operation Operation type of module transaction.
        function execTransactionFromModule(
            address to,
            uint256 value,
            bytes memory data,
            Enum.Operation operation
        ) public virtual returns (bool success) {
            // Only whitelisted modules are allowed.
            require(msg.sender != SENTINEL_MODULES && modules[msg.sender] != address(0), "GS104");
            // Execute transaction without further confirmations.
            success = execute(to, value, data, operation, gasleft());
            if (success) emit ExecutionFromModuleSuccess(msg.sender);
            else emit ExecutionFromModuleFailure(msg.sender);
        }
        /// @dev Allows a Module to execute a Safe transaction without any further confirmations and return data
        /// @param to Destination address of module transaction.
        /// @param value Ether value of module transaction.
        /// @param data Data payload of module transaction.
        /// @param operation Operation type of module transaction.
        function execTransactionFromModuleReturnData(
            address to,
            uint256 value,
            bytes memory data,
            Enum.Operation operation
        ) public returns (bool success, bytes memory returnData) {
            success = execTransactionFromModule(to, value, data, operation);
            // solhint-disable-next-line no-inline-assembly
            assembly {
                // Load free memory location
                let ptr := mload(0x40)
                // We allocate memory for the return data by setting the free memory location to
                // current free memory location + data size + 32 bytes for data size value
                mstore(0x40, add(ptr, add(returndatasize(), 0x20)))
                // Store the size
                mstore(ptr, returndatasize())
                // Store the data
                returndatacopy(add(ptr, 0x20), 0, returndatasize())
                // Point the return data to the correct memory location
                returnData := ptr
            }
        }
        /// @dev Returns if an module is enabled
        /// @return True if the module is enabled
        function isModuleEnabled(address module) public view returns (bool) {
            return SENTINEL_MODULES != module && modules[module] != address(0);
        }
        /// @dev Returns array of modules.
        /// @param start Start of the page.
        /// @param pageSize Maximum number of modules that should be returned.
        /// @return array Array of modules.
        /// @return next Start of the next page.
        function getModulesPaginated(address start, uint256 pageSize) external view returns (address[] memory array, address next) {
            // Init array with max page size
            array = new address[](pageSize);
            // Populate return array
            uint256 moduleCount = 0;
            address currentModule = modules[start];
            while (currentModule != address(0x0) && currentModule != SENTINEL_MODULES && moduleCount < pageSize) {
                array[moduleCount] = currentModule;
                currentModule = modules[currentModule];
                moduleCount++;
            }
            next = currentModule;
            // Set correct size of returned array
            // solhint-disable-next-line no-inline-assembly
            assembly {
                mstore(array, moduleCount)
            }
        }
    }
    // SPDX-License-Identifier: LGPL-3.0-only
    pragma solidity >=0.7.0 <0.9.0;
    import "../common/SelfAuthorized.sol";
    /// @title OwnerManager - Manages a set of owners and a threshold to perform actions.
    /// @author Stefan George - <[email protected]>
    /// @author Richard Meissner - <[email protected]>
    contract OwnerManager is SelfAuthorized {
        event AddedOwner(address owner);
        event RemovedOwner(address owner);
        event ChangedThreshold(uint256 threshold);
        address internal constant SENTINEL_OWNERS = address(0x1);
        mapping(address => address) internal owners;
        uint256 internal ownerCount;
        uint256 internal threshold;
        /// @dev Setup function sets initial storage of contract.
        /// @param _owners List of Safe owners.
        /// @param _threshold Number of required confirmations for a Safe transaction.
        function setupOwners(address[] memory _owners, uint256 _threshold) internal {
            // Threshold can only be 0 at initialization.
            // Check ensures that setup function can only be called once.
            require(threshold == 0, "GS200");
            // Validate that threshold is smaller than number of added owners.
            require(_threshold <= _owners.length, "GS201");
            // There has to be at least one Safe owner.
            require(_threshold >= 1, "GS202");
            // Initializing Safe owners.
            address currentOwner = SENTINEL_OWNERS;
            for (uint256 i = 0; i < _owners.length; i++) {
                // Owner address cannot be null.
                address owner = _owners[i];
                require(owner != address(0) && owner != SENTINEL_OWNERS && owner != address(this) && currentOwner != owner, "GS203");
                // No duplicate owners allowed.
                require(owners[owner] == address(0), "GS204");
                owners[currentOwner] = owner;
                currentOwner = owner;
            }
            owners[currentOwner] = SENTINEL_OWNERS;
            ownerCount = _owners.length;
            threshold = _threshold;
        }
        /// @dev Allows to add a new owner to the Safe and update the threshold at the same time.
        ///      This can only be done via a Safe transaction.
        /// @notice Adds the owner `owner` to the Safe and updates the threshold to `_threshold`.
        /// @param owner New owner address.
        /// @param _threshold New threshold.
        function addOwnerWithThreshold(address owner, uint256 _threshold) public authorized {
            // Owner address cannot be null, the sentinel or the Safe itself.
            require(owner != address(0) && owner != SENTINEL_OWNERS && owner != address(this), "GS203");
            // No duplicate owners allowed.
            require(owners[owner] == address(0), "GS204");
            owners[owner] = owners[SENTINEL_OWNERS];
            owners[SENTINEL_OWNERS] = owner;
            ownerCount++;
            emit AddedOwner(owner);
            // Change threshold if threshold was changed.
            if (threshold != _threshold) changeThreshold(_threshold);
        }
        /// @dev Allows to remove an owner from the Safe and update the threshold at the same time.
        ///      This can only be done via a Safe transaction.
        /// @notice Removes the owner `owner` from the Safe and updates the threshold to `_threshold`.
        /// @param prevOwner Owner that pointed to the owner to be removed in the linked list
        /// @param owner Owner address to be removed.
        /// @param _threshold New threshold.
        function removeOwner(
            address prevOwner,
            address owner,
            uint256 _threshold
        ) public authorized {
            // Only allow to remove an owner, if threshold can still be reached.
            require(ownerCount - 1 >= _threshold, "GS201");
            // Validate owner address and check that it corresponds to owner index.
            require(owner != address(0) && owner != SENTINEL_OWNERS, "GS203");
            require(owners[prevOwner] == owner, "GS205");
            owners[prevOwner] = owners[owner];
            owners[owner] = address(0);
            ownerCount--;
            emit RemovedOwner(owner);
            // Change threshold if threshold was changed.
            if (threshold != _threshold) changeThreshold(_threshold);
        }
        /// @dev Allows to swap/replace an owner from the Safe with another address.
        ///      This can only be done via a Safe transaction.
        /// @notice Replaces the owner `oldOwner` in the Safe with `newOwner`.
        /// @param prevOwner Owner that pointed to the owner to be replaced in the linked list
        /// @param oldOwner Owner address to be replaced.
        /// @param newOwner New owner address.
        function swapOwner(
            address prevOwner,
            address oldOwner,
            address newOwner
        ) public authorized {
            // Owner address cannot be null, the sentinel or the Safe itself.
            require(newOwner != address(0) && newOwner != SENTINEL_OWNERS && newOwner != address(this), "GS203");
            // No duplicate owners allowed.
            require(owners[newOwner] == address(0), "GS204");
            // Validate oldOwner address and check that it corresponds to owner index.
            require(oldOwner != address(0) && oldOwner != SENTINEL_OWNERS, "GS203");
            require(owners[prevOwner] == oldOwner, "GS205");
            owners[newOwner] = owners[oldOwner];
            owners[prevOwner] = newOwner;
            owners[oldOwner] = address(0);
            emit RemovedOwner(oldOwner);
            emit AddedOwner(newOwner);
        }
        /// @dev Allows to update the number of required confirmations by Safe owners.
        ///      This can only be done via a Safe transaction.
        /// @notice Changes the threshold of the Safe to `_threshold`.
        /// @param _threshold New threshold.
        function changeThreshold(uint256 _threshold) public authorized {
            // Validate that threshold is smaller than number of owners.
            require(_threshold <= ownerCount, "GS201");
            // There has to be at least one Safe owner.
            require(_threshold >= 1, "GS202");
            threshold = _threshold;
            emit ChangedThreshold(threshold);
        }
        function getThreshold() public view returns (uint256) {
            return threshold;
        }
        function isOwner(address owner) public view returns (bool) {
            return owner != SENTINEL_OWNERS && owners[owner] != address(0);
        }
        /// @dev Returns array of owners.
        /// @return Array of Safe owners.
        function getOwners() public view returns (address[] memory) {
            address[] memory array = new address[](ownerCount);
            // populate return array
            uint256 index = 0;
            address currentOwner = owners[SENTINEL_OWNERS];
            while (currentOwner != SENTINEL_OWNERS) {
                array[index] = currentOwner;
                currentOwner = owners[currentOwner];
                index++;
            }
            return array;
        }
    }
    // SPDX-License-Identifier: LGPL-3.0-only
    pragma solidity >=0.7.0 <0.9.0;
    /// @title Enum - Collection of enums
    /// @author Richard Meissner - <[email protected]>
    contract Enum {
        enum Operation {Call, DelegateCall}
    }
    // SPDX-License-Identifier: LGPL-3.0-only
    pragma solidity >=0.7.0 <0.9.0;
    /// @title EtherPaymentFallback - A contract that has a fallback to accept ether payments
    /// @author Richard Meissner - <[email protected]>
    contract EtherPaymentFallback {
        event SafeReceived(address indexed sender, uint256 value);
        /// @dev Fallback function accepts Ether transactions.
        receive() external payable {
            emit SafeReceived(msg.sender, msg.value);
        }
    }
    // SPDX-License-Identifier: LGPL-3.0-only
    pragma solidity >=0.7.0 <0.9.0;
    /// @title SecuredTokenTransfer - Secure token transfer
    /// @author Richard Meissner - <[email protected]>
    contract SecuredTokenTransfer {
        /// @dev Transfers a token and returns if it was a success
        /// @param token Token that should be transferred
        /// @param receiver Receiver to whom the token should be transferred
        /// @param amount The amount of tokens that should be transferred
        function transferToken(
            address token,
            address receiver,
            uint256 amount
        ) internal returns (bool transferred) {
            // 0xa9059cbb - keccack("transfer(address,uint256)")
            bytes memory data = abi.encodeWithSelector(0xa9059cbb, receiver, amount);
            // solhint-disable-next-line no-inline-assembly
            assembly {
                // We write the return value to scratch space.
                // See https://docs.soliditylang.org/en/v0.7.6/internals/layout_in_memory.html#layout-in-memory
                let success := call(sub(gas(), 10000), token, 0, add(data, 0x20), mload(data), 0, 0x20)
                switch returndatasize()
                    case 0 {
                        transferred := success
                    }
                    case 0x20 {
                        transferred := iszero(or(iszero(success), iszero(mload(0))))
                    }
                    default {
                        transferred := 0
                    }
            }
        }
    }
    // SPDX-License-Identifier: LGPL-3.0-only
    pragma solidity >=0.7.0 <0.9.0;
    /// @title SelfAuthorized - authorizes current contract to perform actions
    /// @author Richard Meissner - <[email protected]>
    contract SelfAuthorized {
        function requireSelfCall() private view {
            require(msg.sender == address(this), "GS031");
        }
        modifier authorized() {
            // This is a function call as it minimized the bytecode size
            requireSelfCall();
            _;
        }
    }
    // SPDX-License-Identifier: LGPL-3.0-only
    pragma solidity >=0.7.0 <0.9.0;
    /// @title SignatureDecoder - Decodes signatures that a encoded as bytes
    /// @author Richard Meissner - <[email protected]>
    contract SignatureDecoder {
        /// @dev divides bytes signature into `uint8 v, bytes32 r, bytes32 s`.
        /// @notice Make sure to peform a bounds check for @param pos, to avoid out of bounds access on @param signatures
        /// @param pos which signature to read. A prior bounds check of this parameter should be performed, to avoid out of bounds access
        /// @param signatures concatenated rsv signatures
        function signatureSplit(bytes memory signatures, uint256 pos)
            internal
            pure
            returns (
                uint8 v,
                bytes32 r,
                bytes32 s
            )
        {
            // The signature format is a compact form of:
            //   {bytes32 r}{bytes32 s}{uint8 v}
            // Compact means, uint8 is not padded to 32 bytes.
            // solhint-disable-next-line no-inline-assembly
            assembly {
                let signaturePos := mul(0x41, pos)
                r := mload(add(signatures, add(signaturePos, 0x20)))
                s := mload(add(signatures, add(signaturePos, 0x40)))
                // Here we are loading the last 32 bytes, including 31 bytes
                // of 's'. There is no 'mload8' to do this.
                //
                // 'byte' is not working due to the Solidity parser, so lets
                // use the second best option, 'and'
                v := and(mload(add(signatures, add(signaturePos, 0x41))), 0xff)
            }
        }
    }
    // SPDX-License-Identifier: LGPL-3.0-only
    pragma solidity >=0.7.0 <0.9.0;
    /// @title Singleton - Base for singleton contracts (should always be first super contract)
    ///         This contract is tightly coupled to our proxy contract (see `proxies/GnosisSafeProxy.sol`)
    /// @author Richard Meissner - <[email protected]>
    contract Singleton {
        // singleton always needs to be first declared variable, to ensure that it is at the same location as in the Proxy contract.
        // It should also always be ensured that the address is stored alone (uses a full word)
        address private singleton;
    }
    // SPDX-License-Identifier: LGPL-3.0-only
    pragma solidity >=0.7.0 <0.9.0;
    /// @title StorageAccessible - generic base contract that allows callers to access all internal storage.
    /// @notice See https://github.com/gnosis/util-contracts/blob/bb5fe5fb5df6d8400998094fb1b32a178a47c3a1/contracts/StorageAccessible.sol
    contract StorageAccessible {
        /**
         * @dev Reads `length` bytes of storage in the currents contract
         * @param offset - the offset in the current contract's storage in words to start reading from
         * @param length - the number of words (32 bytes) of data to read
         * @return the bytes that were read.
         */
        function getStorageAt(uint256 offset, uint256 length) public view returns (bytes memory) {
            bytes memory result = new bytes(length * 32);
            for (uint256 index = 0; index < length; index++) {
                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let word := sload(add(offset, index))
                    mstore(add(add(result, 0x20), mul(index, 0x20)), word)
                }
            }
            return result;
        }
        /**
         * @dev Performs a delegetecall on a targetContract in the context of self.
         * Internally reverts execution to avoid side effects (making it static).
         *
         * This method reverts with data equal to `abi.encode(bool(success), bytes(response))`.
         * Specifically, the `returndata` after a call to this method will be:
         * `success:bool || response.length:uint256 || response:bytes`.
         *
         * @param targetContract Address of the contract containing the code to execute.
         * @param calldataPayload Calldata that should be sent to the target contract (encoded method name and arguments).
         */
        function simulateAndRevert(address targetContract, bytes memory calldataPayload) external {
            // solhint-disable-next-line no-inline-assembly
            assembly {
                let success := delegatecall(gas(), targetContract, add(calldataPayload, 0x20), mload(calldataPayload), 0, 0)
                mstore(0x00, success)
                mstore(0x20, returndatasize())
                returndatacopy(0x40, 0, returndatasize())
                revert(0, add(returndatasize(), 0x40))
            }
        }
    }
    // SPDX-License-Identifier: LGPL-3.0-only
    pragma solidity >=0.7.0 <0.9.0;
    /**
     * @title GnosisSafeMath
     * @dev Math operations with safety checks that revert on error
     * Renamed from SafeMath to GnosisSafeMath to avoid conflicts
     * TODO: remove once open zeppelin update to solc 0.5.0
     */
    library GnosisSafeMath {
        /**
         * @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);
            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);
            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);
            return c;
        }
        /**
         * @dev Returns the largest of two numbers.
         */
        function max(uint256 a, uint256 b) internal pure returns (uint256) {
            return a >= b ? a : b;
        }
    }
    // SPDX-License-Identifier: LGPL-3.0-only
    pragma solidity >=0.7.0 <0.9.0;
    contract ISignatureValidatorConstants {
        // bytes4(keccak256("isValidSignature(bytes,bytes)")
        bytes4 internal constant EIP1271_MAGIC_VALUE = 0x20c13b0b;
    }
    abstract contract ISignatureValidator is ISignatureValidatorConstants {
        /**
         * @dev Should return whether the signature provided is valid for the provided data
         * @param _data Arbitrary length data signed on the behalf of address(this)
         * @param _signature Signature byte array associated with _data
         *
         * MUST return the bytes4 magic value 0x20c13b0b when function passes.
         * MUST NOT modify state (using STATICCALL for solc < 0.5, view modifier for solc > 0.5)
         * MUST allow external calls
         */
        function isValidSignature(bytes memory _data, bytes memory _signature) public view virtual returns (bytes4);
    }