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0.7
VVS Process Quality Review
Score: 81%

Overview

This is a VVS Finance Process Quality Review completed on the 4th of December, 2021. It was performed using the Process Review process (version 0.7.3) and is documented here. The review was performed by Nick of DeFiSafety. Check out our Telegram.
The final score of the review is 81%, a PASS.The breakdown of the scoring is in Scoring Appendix. For our purposes, a pass is 70%.

Summary of the Process

Very simply, the review looks for the following declarations from the developer's site. With these declarations, it is reasonable to trust the smart contracts.
  • Here are my smart contracts on the blockchain
  • Here is the documentation that explains what my smart contracts do
  • Here are the tests I ran to verify my smart contract
  • Here are the audit(s) performed on my code by third party experts
  • Here are the admin controls and strategies

Disclaimer

This report is for informational purposes only and does not constitute investment advice of any kind, nor does it constitute an offer to provide investment advisory or other services. Nothing in this report shall be considered a solicitation or offer to buy or sell any security, token, future, option or other financial instrument or to offer or provide any investment advice or service to any person in any jurisdiction. Nothing contained in this report constitutes investment advice or offers any opinion with respect to the suitability of any security, and the views expressed in this report should not be taken as advice to buy, sell or hold any security. The information in this report should not be relied upon for the purpose of investing. In preparing the information contained in this report, we have not taken into account the investment needs, objectives and financial circumstances of any particular investor. This information has no regard to the specific investment objectives, financial situation and particular needs of any specific recipient of this information and investments discussed may not be suitable for all investors.
Any views expressed in this report by us were prepared based upon the information available to us at the time such views were written. The views expressed within this report are limited to DeFiSafety and the author and do not reflect those of any additional or third party and are strictly based upon DeFiSafety, its authors, interpretations and evaluation of relevant data. Changed or additional information could cause such views to change. All information is subject to possible correction. Information may quickly become unreliable for various reasons, including changes in market conditions or economic circumstances.
This completed report is copyright (c) DeFiSafety 2021. Permission is given to copy in whole, retaining this copyright label.

Chain

This section indicates the blockchains used by this protocol. This report covers all of the blockchains upon which the protocol is deployed.
Chain: Cronos
Guidance: Ethereum Binance Smart Chain Polygon Avalanche Terra Celo Arbitrum Solana

Code and Team

This section looks at the code deployed on the Mainnet that gets reviewed and its corresponding software repository. The document explaining these questions is here. This review will answer the following questions:
1) Are the executing code addresses readily available? (%) 2) Is the code actively being used? (%) 3) Is there a public software repository? (Y/N) 4) Is there a development history visible? (%) 5) Is the team public (not anonymous)? (Y/N)

1) Are the executing code addresses readily available? (%)

Answer: 100%
Contracts are well labelled in the docs at https://docs.vvs.finance/fundamentals/smart-contracts-and-security, as shown in the Appendix.
Guidance: 100% Clearly labelled and on website, docs or repo, quick to find 70% Clearly labelled and on website, docs or repo but takes a bit of looking 40% Addresses in mainnet.json, in discord or sub graph, etc 20% Address found but labeling not clear or easy to find 0% Executing addresses could not be found

2) Is the code actively being used? (%)

Answer: 100%
Activity is 100+ transactions a day on contract Factory, as indicated in the Appendix.

Guidance:

100% More than 10 transactions a day 70% More than 10 transactions a week 40% More than 10 transactions a month 10% Less than 10 transactions a month 0% No activity

3) Is there a public software repository? (Y/N)

Answer: Yes
Is there a public software repository with the code at a minimum, but also normally test and scripts. Even if the repository was created just to hold the files and has just 1 transaction, it gets a "Yes". For teams with private repositories, this answer is "No".

4) Is there a development history visible? (%)

Answer: 100%
At 200+ commits, this history is rock-solid.
This metric checks if the software repository demonstrates a strong steady history. This is normally demonstrated by commits, branches and releases in a software repository. A healthy history demonstrates a history of more than a month (at a minimum).
Guidance: 100% Any one of 100+ commits, 10+branches 70% Any one of 70+ commits, 7+branches 50% Any one of 50+ commits, 5+branches 30% Any one of 30+ commits, 3+branches 0% Less than 2 branches or less than 30 commits

5) Is the team public (not anonymous)? (Y/N)

Answer: No
Location: VVS' team is anonymous.
For a "Yes" in this question, the real names of some team members must be public on the website or other documentation (LinkedIn, etc). If the team is anonymous, then this question is a "No".

Documentation

This section looks at the software documentation. The document explaining these questions is here.
Required questions are;
6) Is there a whitepaper? (Y/N) 7) Are the basic software functions documented? (Y/N) 8) Does the software function documentation fully (100%) cover the deployed contracts? (%) 9) Are there sufficiently detailed comments for all functions within the deployed contract code (%) 10) Is it possible to trace from software documentation to the implementation in code (%)

6) Is there a whitepaper? (Y/N)

Answer: Yes

7) Are the basic software functions documented? (Y/N)

Answer: Yes
Software functions are documented.

How to improve this score:

Write the document based on the deployed code. For guidance, refer to the SecurEth System Description Document.

8) Does the software function documentation fully (100%) cover the deployed contracts? (%)

Answer: 100%
All software functions are documented.
Guidance:
100% All contracts and functions documented 80% Only the major functions documented 79-1% Estimate of the level of software documentation 0% No software documentation

How to improve this score:

This score can be improved by adding content to the software functions document such that it comprehensively covers the requirements. For guidance, refer to the SecurEth System Description Document. Using tools that aid traceability detection will help.

9) Are there sufficiently detailed comments for all functions within the deployed contract code (%)

Answer: 0%
Code examples are in the Appendix. As per the SLOC, there is 4% commenting to code (CtC).
The Comments to Code (CtC) ratio is the primary metric for this score.
Guidance: 100% CtC > 100 Useful comments consistently on all code 90-70% CtC > 70 Useful comment on most code 60-20% CtC > 20 Some useful commenting 0% CtC < 20 No useful commenting

How to improve this score

This score can improve by adding comments to the deployed code such that it comprehensively covers the code. For guidance, refer to the SecurEth Software Requirements.

10) Is it possible to trace from software documentation to the implementation in code (%)

Answer: 100%
Contracts are explicitly traceable.
Guidance: 100% Clear explicit traceability between code and documentation at a requirement level for all code 60% Clear association between code and documents via non explicit traceability 40% Documentation lists all the functions and describes their functions 0% No connection between documentation and code

How to improve this score:

This score can improve by adding traceability from documentation to code such that it is clear where each outlined function is coded in the source code. For reference, check the SecurEth guidelines on traceability.

Testing

This section looks at the software testing available. It is explained in this document. This section answers the following questions;
11) Full test suite (Covers all the deployed code) (%) 12) Code coverage (Covers all the deployed lines of code, or explains misses) (%) 13) Scripts and instructions to run the tests (Y/N) 14) Report of the results (%) 15) Formal Verification test done (%) 16) Stress Testing environment (%)

11) Is there a Full test suite? (%)

Answer: 100%
Code examples are in the Appendix. As per the SLOC, there is 150% testing to code (TtC).
This score is guided by the Test to Code ratio (TtC). Generally a good test to code ratio is over 100%. However the reviewers best judgement is the final deciding factor.
Guidance: 100% TtC > 120% Both unit and system test visible 80% TtC > 80% Both unit and system test visible 40% TtC < 80% Some tests visible 0% No tests obvious

How to improve this score:

This score can improved by adding tests to fully cover the code. Document what is covered by traceability or test results in the software repository.

12) Code coverage (Covers all the deployed lines of code, or explains misses) (%)

Answer: 91%
A coverage report details 90.9% coverage.
Guidance: 100% Documented full coverage 99-51% Value of test coverage from documented results 50% No indication of code coverage but clearly there is a reasonably complete set of tests 30% Some tests evident but not complete 0% No test for coverage seen

How to improve this score:

This score can improved by adding tests that achieve full code coverage. A clear report and scripts in the software repository will guarantee a high score.

13) Scripts and instructions to run the tests (Y/N)

Answer: Yes

14) Report of the results (%)

Answer: 100%
A test report is evident.
Guidance: 100% Detailed test report as described below 70% GitHub code coverage report visible 0% No test report evident

How to improve this score

Add a report with the results. The test scripts should generate the report or elements of it.

15) Formal Verification test done (%)

Answer: 0%
No formal verification was documented.

16) Stress Testing environment (%)

Answer: 0%
No testnet deployment was documented.

Security

This section looks at the 3rd party software audits done. It is explained in this document. This section answers the following questions;
17) Did 3rd Party audits take place? (%) 18) Is the bounty value acceptably high?

17) Did 3rd Party audits take place? (%)

Answer: 90%
VVS was audited before deployment.
Guidance: 100% Multiple Audits performed before deployment and results public and implemented or not required 90% Single audit performed before deployment and results public and implemented or not required 70% Audit(s) performed after deployment and no changes required. Audit report is public
50% Audit(s) performed after deployment and changes needed but not implemented 20% No audit performed 0% Audit Performed after deployment, existence is public, report is not public and no improvements deployed OR smart contract address' not found, (where question 1 is 0%)
Deduct 25% if code is in a private repo and no note from auditors that audit is applicable to deployed code

18) Is the bounty value acceptably high (%)

Answer: 100%
VVS has bug bounty applicable up $1,337,133 administered through Immunefi in conjuction with Cronos.
Guidance:
100% Bounty is 10% TVL or at least $1M AND active program (see below) 90% Bounty is 5% TVL or at least 500k AND active program 80% Bounty is 5% TVL or at least 500k 70% Bounty is 100k or over AND active program 60% Bounty is 100k or over 50% Bounty is 50k or over AND active program 40% Bounty is 50k or over 20% Bug bounty program bounty is less than 50k 0% No bug bounty program offered
An active program means that a third party (such as Immunefi) is actively driving hackers to the site. An inactive program would be static mentions on the docs.

Access Controls

This section covers the documentation of special access controls for a DeFi protocol. The admin access controls are the contracts that allow updating contracts or coefficients in the protocol. Since these contracts can allow the protocol admins to "change the rules", complete disclosure of capabilities is vital for user's transparency. It is explained in this document. The questions this section asks are as follow;
19) Can a user clearly and quickly find the status of the admin controls? 20) Is the information clear and complete? 21) Is the information in non-technical terms that pertain to the investments? 22) Is there Pause Control documentation including records of tests?

19) Can a user clearly and quickly find the status of the access controls (%)

Answer: 100%
Admin Control information can easily be found.
Guidance: 100% Clearly labelled and on website, docs or repo, quick to find 70% Clearly labelled and on website, docs or repo but takes a bit of looking 40% Access control docs in multiple places and not well labelled 20% Access control docs in multiple places and not labelled 0% Admin Control information could not be found

20) Is the information clear and complete (%)

Answer: 90%
Admin Control information details which contracts are not upgradeable (all of them), the OnlyOwner is identified and the change capability is identified (none).
Guidance: All the contracts are immutable -- 100% OR
a) All contracts are clearly labelled as upgradeable (or not) -- 30% AND b) The type of ownership is clearly indicated (OnlyOwner / MultiSig / Defined Roles) -- 30% AND c) The capabilities for change in the contracts are described -- 30%

How to improve this score:

Create a document that covers the items described above. An example is enclosed.

21) Is the information in non-technical terms that pertain to the investments (%)

Answer: 90%
This information is very clear and easily to understand.
Guidance: 100% All the contracts are immutable 90% Description relates to investments safety and updates in clear, complete non-software l language 30% Description all in software specific language 0% No admin control information could not be found

How to improve this score:

Create a document that covers the items described above in plain language that investors can understand. An example is enclosed.

22) Is there Pause Control documentation including records of tests (%)

Answer: 0%
Pause control not documented or explained.
Guidance: 100% All the contracts are immutable or no pause control needed and this is explained OR 100% Pause control(s) are clearly documented and there is records of at least one test within 3 months 80% Pause control(s) explained clearly but no evidence of regular tests 40% Pause controls mentioned with no detail on capability or tests 0% Pause control not documented or explained

How to improve this score:

Create a document that covers the items described above in plain language that investors can understand. An example is enclosed.

Appendices

Author Details

The author of this review is Rex of DeFi Safety.
Email : [email protected] Twitter : @defisafety
I started with Ethereum just before the DAO and that was a wonderful education. It showed the importance of code quality. The second Parity hack also showed the importance of good process. Here my aviation background offers some value. Aerospace knows how to make reliable code using quality processes.
I was coaxed to go to EthDenver 2018 and there I started SecuEth.org with Bryant and Roman. We created guidelines on good processes for blockchain code development. We got EthFoundation funding to assist in their development.
Process Quality Reviews are an extension of the SecurEth guidelines that will further increase the quality processes in Solidity and Vyper development.
DeFiSafety is my full time gig and we are working on funding vehicles for a permanent staff.

Scoring Appendix

Executing Code Appendix

Code Used Appendix

Example Code Appendix

1
import './interfaces/IVVSPair.sol';
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import './VVSERC20.sol';
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import './libraries/Math.sol';
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import './libraries/UQ112x112.sol';
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import './interfaces/IERC20.sol';
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import './interfaces/IVVSFactory.sol';
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import './interfaces/IVVSCallee.sol';
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contract VVSPair is IVVSPair, VVSERC20 {
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using SafeMath for uint;
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using UQ112x112 for uint224;
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uint public constant MINIMUM_LIQUIDITY = 10**3;
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bytes4 private constant SELECTOR = bytes4(keccak256(bytes('transfer(address,uint256)')));
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address public factory;
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address public token0;
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address public token1;
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uint112 private reserve0; // uses single storage slot, accessible via getReserves
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uint112 private reserve1; // uses single storage slot, accessible via getReserves
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uint32 private blockTimestampLast; // uses single storage slot, accessible via getReserves
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uint public price0CumulativeLast;
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uint public price1CumulativeLast;
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uint public kLast; // reserve0 * reserve1, as of immediately after the most recent liquidity event
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uint private unlocked = 1;
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modifier lock() {
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require(unlocked == 1, 'VVS: LOCKED');
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unlocked = 0;
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_;
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unlocked = 1;
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}
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function getReserves() public view returns (uint112 _reserve0, uint112 _reserve1, uint32 _blockTimestampLast) {
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_reserve0 = reserve0;
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_reserve1 = reserve1;
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_blockTimestampLast = blockTimestampLast;
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}
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function _safeTransfer(address token, address to, uint value) private {
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(bool success, bytes memory data) = token.call(abi.encodeWithSelector(SELECTOR, to, value));
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require(success && (data.length == 0 || abi.decode(data, (bool))), 'VVS: TRANSFER_FAILED');
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}
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event Mint(address indexed sender, uint amount0, uint amount1);
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event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);
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event Swap(
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address indexed sender,
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uint amount0In,
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uint amount1In,
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uint amount0Out,
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uint amount1Out,
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address indexed to
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);
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event Sync(uint112 reserve0, uint112 reserve1);
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constructor() public {
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factory = msg.sender;
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}
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// called once by the factory at time of deployment
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function initialize(address _token0, address _token1) external {
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require(msg.sender == factory, 'VVS: FORBIDDEN'); // sufficient check
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token0 = _token0;
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token1 = _token1;
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}
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// update reserves and, on the first call per block, price accumulators
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function _update(uint balance0, uint balance1, uint112 _reserve0, uint112 _reserve1) private {
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require(balance0 <= uint112(-1) && balance1 <= uint112(-1), 'VVS: OVERFLOW');
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uint32 blockTimestamp = uint32(block.timestamp % 2**32);
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uint32 timeElapsed = blockTimestamp - blockTimestampLast; // overflow is desired
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if (timeElapsed > 0 && _reserve0 != 0 && _reserve1 != 0) {
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// * never overflows, and + overflow is desired
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price0CumulativeLast += uint(UQ112x112.encode(_reserve1).uqdiv(_reserve0)) * timeElapsed;
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price1CumulativeLast += uint(UQ112x112.encode(_reserve0).uqdiv(_reserve1)) * timeElapsed;
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}
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reserve0 = uint112(balance0);
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reserve1 = uint112(balance1);
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blockTimestampLast = blockTimestamp;
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emit Sync(reserve0, reserve1);
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}
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// if fee is on, mint liquidity equivalent to 1/3th of the growth in sqrt(k)
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function _mintFee(uint112 _reserve0, uint112 _reserve1) private returns (bool feeOn) {
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address feeTo = IVVSFactory(factory).feeTo();
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feeOn = feeTo != address(0);
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uint _kLast = kLast; // gas savings
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if (feeOn) {
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if (_kLast != 0) {
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uint rootK = Math.sqrt(uint(_reserve0).mul(_reserve1));
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uint rootKLast = Math.sqrt(_kLast);
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if (rootK > rootKLast) {
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uint numerator = totalSupply.mul(rootK.sub(rootKLast));
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uint denominator = rootK.mul(2).add(rootKLast);
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uint liquidity = numerator / denominator;
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if (liquidity > 0) _mint(feeTo, liquidity);
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}
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}
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} else if (_kLast != 0) {
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kLast = 0;
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}
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}
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// this low-level function should be called from a contract which performs important safety checks
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function mint(address to) external lock returns (uint liquidity) {
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(uint112 _reserve0, uint112 _reserve1,) = getReserves(); // gas savings
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uint balance0 = IERC20(token0).balanceOf(address(this));
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uint balance1 = IERC20(token1).balanceOf(address(this));
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uint amount0 = balance0.sub(_reserve0);
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uint amount1 = balance1.sub(_reserve1);
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bool feeOn = _mintFee(_reserve0, _reserve1);
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uint _totalSupply = totalSupply; // gas savings, must be defined here since totalSupply can update in _mintFee
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if (_totalSupply == 0) {
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liquidity = Math.sqrt(amount0.mul(amount1)).sub(MINIMUM_LIQUIDITY);
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_mint(address(0), MINIMUM_LIQUIDITY); // permanently lock the first MINIMUM_LIQUIDITY tokens
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} else {
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liquidity = Math.min(amount0.mul(_totalSupply) / _reserve0, amount1.mul(_totalSupply) / _reserve1);
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}
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require(liquidity > 0, 'VVS: INSUFFICIENT_LIQUIDITY_MINTED');
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_mint(to, liquidity);
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_update(balance0, balance1, _reserve0, _reserve1);
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if (feeOn) kLast = uint(reserve0).mul(reserve1); // reserve0 and reserve1 are up-to-date
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emit Mint(msg.sender, amount0, amount1);
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}
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// this low-level function should be called from a contract which performs important safety checks
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function burn(address to) external lock returns (uint amount0, uint amount1) {
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(uint112 _reserve0, uint112 _reserve1,) = getReserves(); // gas savings
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address _token0 = token0; // gas savings
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address _token1 = token1; // gas savings
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uint balance0 = IERC20(_token0).balanceOf(address(this));
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uint balance1 = IERC20(_token1).balanceOf(address(this));
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uint liquidity = balanceOf[address(this)];
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bool feeOn = _mintFee(_reserve0, _reserve1);
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uint _totalSupply = totalSupply; // gas savings, must be defined here since totalSupply can update in _mintFee
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amount0 = liquidity.mul(balance0) / _totalSupply; // using balances ensures pro-rata distribution
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amount1 = liquidity.mul(balance1) / _totalSupply; // using balances ensures pro-rata distribution
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require(amount0 > 0 && amount1 > 0, 'VVS: INSUFFICIENT_LIQUIDITY_BURNED');
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_burn(address(this), liquidity);
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_safeTransfer(_token0, to, amount0);
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_safeTransfer(_token1, to, amount1);
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balance0 = IERC20(_token0).balanceOf(address(this));
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balance1 = IERC20(_token1).balanceOf(address(this));
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_update(balance0, balance1, _reserve0, _reserve1);
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if (feeOn) kLast = uint(reserve0).mul(reserve1); // reserve0 and reserve1 are up-to-date
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emit Burn(msg.sender, amount0, amount1, to);
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}
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// this low-level function should be called from a contract which performs important safety checks
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function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external lock {
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require(amount0Out > 0 || amount1Out > 0, 'VVS: INSUFFICIENT_OUTPUT_AMOUNT');
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(uint112 _reserve0, uint112 _reserve1,) = getReserves(); // gas savings
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require(amount0Out < _reserve0 && amount1Out < _reserve1, 'VVS: INSUFFICIENT_LIQUIDITY');
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uint balance0;
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uint balance1;
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{ // scope for _token{0,1}, avoids stack too deep errors
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address _token0 = token0;
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address _token1 = token1;
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require(to != _token0 && to != _token1, 'VVS: INVALID_TO');
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if (amount0Out > 0) _safeTransfer(_token0, to, amount0Out); // optimistically transfer tokens
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if (amount1Out > 0) _safeTransfer(_token1, to, amount1Out); // optimistically transfer tokens
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if (data.length > 0) IVVSCallee(to).vvsCall(msg.sender, amount0Out, amount1Out, data);
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balance0 = IERC20(_token0).balanceOf(address(this));
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balance1 = IERC20(_token1).balanceOf(address(this));
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}
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uint amount0In = balance0 > _reserve0 - amount0Out ? balance0 - (_reserve0 - amount0Out) : 0;
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uint amount1In = balance1 > _reserve1 - amount1Out ? balance1 - (_reserve1 - amount1Out) : 0;
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require(amount0In > 0 || amount1In > 0, 'VVS: INSUFFICIENT_INPUT_AMOUNT');
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{ // scope for reserve{0,1}Adjusted, avoids stack too deep errors
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uint balance0Adjusted = (balance0.mul(1000).sub(amount0In.mul(3)));
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uint balance1Adjusted = (balance1.mul(1000).sub(amount1In.mul(3)));
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require(balance0Adjusted.mul(balance1Adjusted) >= uint(_reserve0).mul(_reserve1).mul(1000**2), 'VVS: K');
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}
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_update(balance0, balance1, _reserve0, _reserve1);
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emit Swap(msg.sender, amount0In, amount1In, amount0Out, amount1Out, to);
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}
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// force balances to match reserves
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function skim(address to) external lock {
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address _token0 = token0; // gas savings
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address _token1 = token1; // gas savings
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_safeTransfer(_token0, to, IERC20(_token0).balanceOf(address(this)).sub(reserve0));
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_safeTransfer(_token1, to, IERC20(_token1).balanceOf(address(this)).sub(reserve1));
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}
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// force reserves to match balances
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function sync() external lock {
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_update(IERC20(token0).balanceOf(address(this)), IERC20(token1).balanceOf(address(this)), reserve0, reserve1);
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}
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}
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SLOC Appendix

Solidity Contracts

Language
Files
Lines
Blanks
Comments
Code
Complexity
Solidity
2
252
35
9
208
42
Comments to Code 9/208= 4%

Javascript Tests

Language
Files
Lines
Blanks
Comments
Code
Complexity
JavaScript
2
371
55
5
311
6
Tests to Code 311/208 = 150%
Last modified 10d ago