85 lines
2.1 KiB
Solidity
85 lines
2.1 KiB
Solidity
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pragma solidity >=0.5.17;
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/**
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* @title Careful Math
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* @author Compound
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* @notice Derived from OpenZeppelin's SafeMath library
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* https://github.com/OpenZeppelin/openzeppelin-solidity/blob/master/contracts/math/SafeMath.sol
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*/
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contract CarefulMath {
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/**
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* @dev Possible error codes that we can return
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*/
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enum MathError {
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NO_ERROR,
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DIVISION_BY_ZERO,
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INTEGER_OVERFLOW,
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INTEGER_UNDERFLOW
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}
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/**
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* @dev Multiplies two numbers, returns an error on overflow.
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*/
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function mulUInt(uint a, uint b) internal pure returns (MathError, uint) {
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if (a == 0) {
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return (MathError.NO_ERROR, 0);
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}
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uint c = a * b;
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if (c / a != b) {
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return (MathError.INTEGER_OVERFLOW, 0);
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} else {
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return (MathError.NO_ERROR, c);
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}
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}
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/**
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* @dev Integer division of two numbers, truncating the quotient.
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*/
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function divUInt(uint a, uint b) internal pure returns (MathError, uint) {
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if (b == 0) {
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return (MathError.DIVISION_BY_ZERO, 0);
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}
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return (MathError.NO_ERROR, a / b);
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}
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/**
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* @dev Subtracts two numbers, returns an error on overflow (i.e. if subtrahend is greater than minuend).
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*/
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function subUInt(uint a, uint b) internal pure returns (MathError, uint) {
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if (b <= a) {
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return (MathError.NO_ERROR, a - b);
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} else {
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return (MathError.INTEGER_UNDERFLOW, 0);
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}
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}
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/**
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* @dev Adds two numbers, returns an error on overflow.
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*/
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function addUInt(uint a, uint b) internal pure returns (MathError, uint) {
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uint c = a + b;
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if (c >= a) {
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return (MathError.NO_ERROR, c);
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} else {
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return (MathError.INTEGER_OVERFLOW, 0);
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}
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}
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/**
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* @dev add a and b and then subtract c
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*/
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function addThenSubUInt(uint a, uint b, uint c) internal pure returns (MathError, uint) {
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(MathError err0, uint sum) = addUInt(a, b);
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if (err0 != MathError.NO_ERROR) {
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return (err0, 0);
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}
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return subUInt(sum, c);
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}
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}
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