ETH Price: $2,343.61 (-0.74%)

Transaction Decoder

Block:
14629658 at Apr-21-2022 05:40:37 PM +UTC
Transaction Fee:
0.018435779485171002 ETH $43.21
Gas Used:
143,373 Gas / 128.586131874 Gwei

Emitted Events:

396 0x3e6046b4d127179f0a421f3148b43cf52c08fc41.0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef( 0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef, 0x0000000000000000000000000000000000000000000000000000000000000000, 0x000000000000000000000000f96a23502c48b3c7ee053db35367ee9b7660f2f5, 0x0000000000000000000000000000000000000000000000000000000000000490 )
397 GnosisSafeProxy.0x3d0ce9bfc3ed7d6862dbb28b2dea94561fe714a1b4d019aa8af39730d1ad7c3d( 0x3d0ce9bfc3ed7d6862dbb28b2dea94561fe714a1b4d019aa8af39730d1ad7c3d, 0x0000000000000000000000005a25d511b8ccf2894950243d1c57ca9f1447caba, 00000000000000000000000000000000000000000000000000f8b0a10e470000 )
398 0x5a25d511b8ccf2894950243d1c57ca9f1447caba.0x4896181ff8f4543cc00db9fe9b6fb7e6f032b7eb772c72ab1ec1b4d2e03b9369( 0x4896181ff8f4543cc00db9fe9b6fb7e6f032b7eb772c72ab1ec1b4d2e03b9369, 0x000000000000000000000000f96a23502c48b3c7ee053db35367ee9b7660f2f5, 0x00000000000000000000000000000000000000000000000000000000000001f9 )

Account State Difference:

  Address   Before After State Difference Code
0x3e6046b4...52c08Fc41
0x5A25d511...F1447cabA
0xc4ea960B...15Fa2B124 275.777016379695039286 Eth275.847016379695039286 Eth0.07
(Ethermine)
1,119.871779681768180461 Eth1,119.871994741268180461 Eth0.0002150595
0xF96a2350...B7660f2F5
2.672475028061875462 Eth
Nonce: 629
2.58403924857670446 Eth
Nonce: 630
0.088435779485171002

Execution Trace

ETH 0.07 0x5a25d511b8ccf2894950243d1c57ca9f1447caba.db006a75( )
  • BFF Friendship Bracelets: ✺BFF Token.6352211e( )
    • 0x477c17e53a5f5bc17a6fd54f94219713fda0f562.6352211e( )
    • 0x3e6046b4d127179f0a421f3148b43cf52c08fc41.755edd17( )
      • 0x477c17e53a5f5bc17a6fd54f94219713fda0f562.755edd17( )
        • 0x543b8a295a485b50ba0db1d686ab806656d7d542.601ef880( )
        • 0x3e6046b4d127179f0a421f3148b43cf52c08fc41.STATICCALL( )
          • 0x477c17e53a5f5bc17a6fd54f94219713fda0f562.DELEGATECALL( )
          • ETH 0.07 GnosisSafeProxy.CALL( )
            • ETH 0.07 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 - <richard@gnosis.io>
              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 - <stefan@gnosis.io>
              /// @author Richard Meissner - <richard@gnosis.io>
              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 - <stefan@gnosis.pm>
              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 - <stefan@gnosis.io>
              /// @author Richard Meissner - <richard@gnosis.io>
              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 - <richard@gnosis.pm>
              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 - <richard@gnosis.pm>
              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 - <richard@gnosis.pm>
              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 - <stefan@gnosis.pm>
              /// @author Richard Meissner - <richard@gnosis.pm>
              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 - <stefan@gnosis.pm>
              /// @author Richard Meissner - <richard@gnosis.pm>
              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 - <richard@gnosis.pm>
              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 - <richard@gnosis.pm>
              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 - <richard@gnosis.pm>
              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 - <richard@gnosis.pm>
              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 - <richard@gnosis.pm>
              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 - <richard@gnosis.io>
              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);
              }