OwnerZero.sol

OwnerZero.sol

// SPDX-License-Identifier: GPL-3.0
pragma solidity >=0.6.0 <0.9.0;

contract Test {
    address public regMsgSender = address(0);
    function setMsgSender () external
    {
        regMsgSender = msg.sender;
    }

    function getMsgSender () public view returns (address) 
    {
        return regMsgSender;
    }

    function setMsgSender2 () public
    {
         string memory s = string(abi.encodePacked("Violation: msg.sender is not the sender before: ", toAsciiString(regMsgSender), " - ", toAsciiString(msg.sender)));
        require(regMsgSender == msg.sender,  s);
        regMsgSender = msg.sender;
    }
    
    function toAsciiString(address x) internal pure returns (string memory) {
    bytes memory s = new bytes(40);
    for (uint i = 0; i < 20; i++) {
        bytes1 b = bytes1(uint8(uint(uint160(x)) / (2**(8*(19 - i)))));
        bytes1 hi = bytes1(uint8(b) / 16);
        bytes1 lo = bytes1(uint8(b) - 16 * uint8(hi));
        s[2*i] = char(hi);
        s[2*i+1] = char(lo);            
    }
    return string(s);
}

    function char(bytes1 b) internal pure returns (bytes1 c) {
        if (uint8(b) < 10) return bytes1(uint8(b) + 0x30);
        else return bytes1(uint8(b) + 0x57);
    }
}