Proxy.sol

pragma solidity 0.5;


/// @title Proxy - Generic proxy contract allows to execute all transactions applying the code of a master contract.
/// @author Stefan George - <stefan@gnosis.pm>
contract Proxy {

  // masterCopy always needs to be first declared variable, to ensure that it is at the same location in the contracts to which calls are delegated.
  address masterCopy;

  /// @dev Constructor function sets address of master copy contract.
  /// @param _masterCopy Master copy address.
  constructor(address _masterCopy)
    public
  {
    require(_masterCopy != address(0), "Invalid master copy address provided");
    masterCopy = _masterCopy;
  }

  /// @dev Fallback function forwards all transactions and returns all received return data.
  function ()
    external
    payable
  {
    // solium-disable-next-line security/no-inline-assembly
    assembly {
      let masterCopy := and(sload(0), 0xffffffffffffffffffffffffffffffffffffffff)
      calldatacopy(0, 0, calldatasize())
      let success := delegatecall(gas, masterCopy, 0, calldatasize(), 0, 0)
      returndatacopy(0, 0, returndatasize())
      if eq(success, 0) { revert(0, returndatasize()) }
      return(0, returndatasize())
    }
  }

  function implementation()
    public
    view
    returns (address)
  {
    return masterCopy;
  }

  function proxyType()
    public
    pure
    returns (uint256)
  {
    return 2;
  }
}