Reuse openzeppelin libraries

[andreiashu]

Description

In most cases the code makes use of the OpenZeppelin's standard libraries:

review-xave-lending-market-2021-10/code/contracts/buyback/Treasury.sol

Lines 7 to 9 in 15d777b

	import {SafeMath} from '@openzeppelin/contracts/math/SafeMath.sol';
	import {Ownable} from '@openzeppelin/contracts/access/Ownable.sol';
	import {IERC20} from '@openzeppelin/contracts/token/ERC20/IERC20.sol';

In other cases, however, the code uses copy-pasted versions of the same libraries:

review-xave-lending-market-2021-10/code/contracts/incentives/RnbwIncentivesController.sol

Lines 6 to 8 in 15d777b

	import {SafeMath} from './lib/SafeMath.sol';
	import {IERC20} from './interfaces/IERC20.sol';

Below we show that there are not functional differences between the ./incentives/lib/Context.sol file and the one that comes with OpenZeppelin:

$ diff -uN --ignore-all-space ./incentives/lib/Context.sol ../node_modules/@openzeppelin/contracts/GSN/Context.sol
--- ./incentives/lib/Context.sol        2021-10-22 08:00:48.000000000 +0700
+++ ../node_modules/@openzeppelin/contracts/GSN/Context.sol     2021-10-22 13:39:41.000000000 +0700
@@ -1,10 +1,9 @@
 // SPDX-License-Identifier: MIT
 
-pragma solidity 0.6.12;
+pragma solidity ^0.6.0;
 
-/**
- * @dev From https://github.com/OpenZeppelin/openzeppelin-contracts
- * Provides information about the current execution context, including the
+/*
+ * @dev Provides information about the current execution context, including the
  * sender of the transaction and its data. While these are generally available

SafeMath.sol is identical but the diff is bigger because of different code formatting:

$ diff -uN --ignore-all-space ./incentives/lib/SafeMath.sol ../node_modules/@openzeppelin/contracts/math/SafeMath.sol
--- ./incentives/lib/SafeMath.sol       2021-10-22 08:00:48.000000000 +0700
+++ ../node_modules/@openzeppelin/contracts/math/SafeMath.sol   2021-10-22 13:39:41.000000000 +0700
@@ -1,9 +1,9 @@
-// SPDX-License-Identifier: agpl-3.0
-pragma solidity 0.6.12;
+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.6.0;
 
 /**
- * @dev From https://github.com/OpenZeppelin/openzeppelin-contracts
- * Wrappers over Solidity's arithmetic operations with added overflow
+ * @dev Wrappers over Solidity's arithmetic operations with added overflow
  * checks.
  *
  * Arithmetic operations in Solidity wrap on overflow. This can easily result
@@ -23,11 +23,12 @@
    * 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');
+        require(c >= a, "SafeMath: addition overflow");
 
     return c;
   }
@@ -39,10 +40,11 @@
    * 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');
+        return sub(a, b, "SafeMath: subtraction overflow");
   }
 
   /**
@@ -52,13 +54,10 @@
    * Counterpart to Solidity's `-` operator.
    *
    * Requirements:
+     *
    * - Subtraction cannot overflow.
    */
-  function sub(
-    uint256 a,
-    uint256 b,
-    string memory errorMessage
-  ) internal pure returns (uint256) {
+    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
     require(b <= a, errorMessage);
     uint256 c = a - b;
 
@@ -72,6 +71,7 @@
    * Counterpart to Solidity's `*` operator.
    *
    * Requirements:
+     *
    * - Multiplication cannot overflow.
    */
   function mul(uint256 a, uint256 b) internal pure returns (uint256) {
@@ -83,7 +83,7 @@
     }
 
     uint256 c = a * b;
-    require(c / a == b, 'SafeMath: multiplication overflow');
+        require(c / a == b, "SafeMath: multiplication overflow");
 
     return c;
   }
@@ -97,10 +97,11 @@
    * 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');
+        return div(a, b, "SafeMath: division by zero");
   }
 
   /**
@@ -112,14 +113,10 @@
    * 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
+    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
     require(b > 0, errorMessage);
     uint256 c = a / b;
     // assert(a == b * c + a % b); // There is no case in which this doesn't hold
@@ -136,10 +133,11 @@
    * 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');
+        return mod(a, b, "SafeMath: modulo by zero");
   }
 
   /**
@@ -151,13 +149,10 @@
    * 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) {
+    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
     require(b != 0, errorMessage);
     return a % b;
   }

Recommendation

Remove the following contracts from ./code/contracts/incentives/lib/ folder and make use of the version provided with OpenZeppelin: Context, ERC20, MintableErc20, SafeMath.