From 5d003429c748abf52e078c15492a09b14b46b385 Mon Sep 17 00:00:00 2001 From: The3D Date: Thu, 13 May 2021 19:56:55 +0200 Subject: [PATCH] feat: replaced SafeMath library --- .../openzeppelin/contracts/SafeMath.sol | 190 ++++-------------- 1 file changed, 38 insertions(+), 152 deletions(-) diff --git a/contracts/dependencies/openzeppelin/contracts/SafeMath.sol b/contracts/dependencies/openzeppelin/contracts/SafeMath.sol index 80f7d679..d9605fca 100644 --- a/contracts/dependencies/openzeppelin/contracts/SafeMath.sol +++ b/contracts/dependencies/openzeppelin/contracts/SafeMath.sol @@ -1,163 +1,49 @@ // SPDX-License-Identifier: agpl-3.0 pragma solidity 0.6.12; -/** - * @dev Wrappers over Solidity's arithmetic operations with added overflow - * checks. - * - * Arithmetic operations in Solidity wrap on overflow. This can easily result - * in bugs, because programmers usually assume that an overflow raises an - * error, which is the standard behavior in high level programming languages. - * `SafeMath` restores this intuition by reverting the transaction when an - * operation overflows. - * - * Using this library instead of the unchecked operations eliminates an entire - * class of bugs, so it's recommended to use it always. - */ +/// @title Optimized overflow and underflow safe math operations +/// @notice Contains methods for doing math operations that revert on overflow or underflow for minimal gas cost library SafeMath { - /** - * @dev Returns the addition of two unsigned integers, reverting on - * overflow. - * - * Counterpart to Solidity's `+` operator. - * - * Requirements: - * - Addition cannot overflow. - */ - function add(uint256 a, uint256 b) internal pure returns (uint256) { - uint256 c = a + b; - require(c >= a, 'SafeMath: addition overflow'); - - return c; - } - - /** - * @dev Returns the subtraction of two unsigned integers, reverting on - * overflow (when the result is negative). - * - * Counterpart to Solidity's `-` operator. - * - * Requirements: - * - Subtraction cannot overflow. - */ - function sub(uint256 a, uint256 b) internal pure returns (uint256) { - return sub(a, b, 'SafeMath: subtraction overflow'); - } - - /** - * @dev Returns the subtraction of two unsigned integers, reverting with custom message on - * overflow (when the result is negative). - * - * Counterpart to Solidity's `-` operator. - * - * Requirements: - * - Subtraction cannot overflow. - */ - function sub( - uint256 a, - uint256 b, - string memory errorMessage - ) internal pure returns (uint256) { - require(b <= a, errorMessage); - uint256 c = a - b; - - return c; - } - - /** - * @dev Returns the multiplication of two unsigned integers, reverting on - * overflow. - * - * Counterpart to Solidity's `*` operator. - * - * Requirements: - * - Multiplication cannot 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-contracts/pull/522 - if (a == 0) { - return 0; + /// @notice Returns x + y, reverts if sum overflows uint256 + /// @param x The augend + /// @param y The addend + /// @return z The sum of x and y + function add(uint256 x, uint256 y) internal pure returns (uint256 z) { + require((z = x + y) >= x); } - uint256 c = a * b; - require(c / a == b, 'SafeMath: multiplication overflow'); + /// @notice Returns x - y, reverts if underflows + /// @param x The minuend + /// @param y The subtrahend + /// @return z The difference of x and y + function sub(uint256 x, uint256 y) internal pure returns (uint256 z) { + require((z = x - y) <= x); + } - return c; - } + /// @notice Returns x - y, reverts if underflows + /// @param x The minuend + /// @param y The subtrahend + /// @param message The error msg + /// @return z The difference of x and y + function sub(uint256 x, uint256 y, string memory message) internal pure returns (uint256 z) { + require((z = x - y) <= x, message); + } - /** - * @dev Returns the integer division of two unsigned integers. Reverts on - * division by zero. The result is rounded towards zero. - * - * Counterpart to Solidity's `/` operator. Note: this function uses a - * `revert` opcode (which leaves remaining gas untouched) while Solidity - * uses an invalid opcode to revert (consuming all remaining gas). - * - * Requirements: - * - The divisor cannot be zero. - */ - function div(uint256 a, uint256 b) internal pure returns (uint256) { - return div(a, b, 'SafeMath: division by zero'); - } - /** - * @dev Returns the integer division of two unsigned integers. Reverts with custom message on - * division by zero. The result is rounded towards zero. - * - * Counterpart to Solidity's `/` operator. Note: this function uses a - * `revert` opcode (which leaves remaining gas untouched) while Solidity - * uses an invalid opcode to revert (consuming all remaining gas). - * - * Requirements: - * - The divisor cannot be zero. - */ - function div( - uint256 a, - uint256 b, - string memory errorMessage - ) internal pure returns (uint256) { - // Solidity only automatically asserts when dividing by 0 - require(b > 0, errorMessage); - uint256 c = a / b; - // assert(a == b * c + a % b); // There is no case in which this doesn't hold + /// @notice Returns x * y, reverts if overflows + /// @param x The multiplicand + /// @param y The multiplier + /// @return z The product of x and y + function mul(uint256 x, uint256 y) internal pure returns (uint256 z) { + require(x == 0 || (z = x * y) / x == y); + } - return c; - } + /// @notice Returns x / y, reverts if overflows - no specific check, solidity reverts on division by 0 + /// @param x The numerator + /// @param y The denominator + /// @return z The product of x and y + function div(uint256 x, uint256 y) internal pure returns (uint256 z) { + return x / y; + } - /** - * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo), - * Reverts when dividing by zero. - * - * Counterpart to Solidity's `%` operator. This function uses a `revert` - * opcode (which leaves remaining gas untouched) while Solidity uses an - * invalid opcode to revert (consuming all remaining gas). - * - * Requirements: - * - The divisor cannot be zero. - */ - function mod(uint256 a, uint256 b) internal pure returns (uint256) { - return mod(a, b, 'SafeMath: modulo by zero'); - } - - /** - * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo), - * Reverts with custom message when dividing by zero. - * - * Counterpart to Solidity's `%` operator. This function uses a `revert` - * opcode (which leaves remaining gas untouched) while Solidity uses an - * invalid opcode to revert (consuming all remaining gas). - * - * Requirements: - * - The divisor cannot be zero. - */ - function mod( - uint256 a, - uint256 b, - string memory errorMessage - ) internal pure returns (uint256) { - require(b != 0, errorMessage); - return a % b; - } -} +} \ No newline at end of file