Omniscia Olympus DAO Audit

sOlympusERC20 Code Style Findings

sOlympusERC20 Code Style Findings

OEC-01C: Deprecated Representation Style

TypeSeverityLocation
Code StyleInformationalsOlympusERC20.sol:L54

Description:

The maximum of uint256 representation in use (~uint256(0)) has been deprecated in favor of the special type operator.

Example:

contracts/sOlympusERC20.sol
54uint256 private constant MAX_UINT256 = ~uint256(0);

Recommendation:

We advise the operator to be used to instead assign the maximum (type(uint256).max).

Alleviation:

The representation of the maximum was adjusted according to our recommendation.

OEC-02C: Inefficient Code Structure

Description:

All approve style functions can internally use the _approve function.

Example:

contracts/sOlympusERC20.sol
184function approve( address spender, uint256 value ) public override returns (bool) {
185     _allowedValue[ msg.sender ][ spender ] = value;
186     emit Approval( msg.sender, spender, value );
187     return true;
188}
189

190function increaseAllowance( address spender, uint256 addedValue ) public override returns (bool) {
191    _allowedValue[ msg.sender ][ spender ] = _allowedValue[ msg.sender ][ spender ].add( addedValue );
192    emit Approval( msg.sender, spender, _allowedValue[ msg.sender ][ spender ] );
193    return true;
194}
195

196function decreaseAllowance( address spender, uint256 subtractedValue ) public override returns (bool) {
197    uint256 oldValue = _allowedValue[ msg.sender ][ spender ];
198    if (subtractedValue >= oldValue) {
199        _allowedValue[ msg.sender ][ spender ] = 0;
200    } else {
201        _allowedValue[ msg.sender ][ spender ] = oldValue.sub( subtractedValue );
202    }
203    emit Approval( msg.sender, spender, _allowedValue[ msg.sender ][ spender ] );
204    return true;
205}
206

207/* ========== INTERNAL FUNCTIONS ========== */
208

209// called in a permit
210function _approve( address owner, address spender, uint256 value ) internal override virtual {
211    _allowedValue[owner][spender] = value;
212    emit Approval( owner, spender, value );
213}

Recommendation:

We advise them to do so to signficantly reduce the bytecode size of the contract.

Alleviation:

The code was refactored to properly utilize _approve in all instances possible.

OEC-03C: Inexistent Error Messages

TypeSeverityLocation
Code StyleInformationalsOlympusERC20.sol:L80, L81, L86, L87, L88, L94, L96

Description:

The linked require checks contain no descriptive error messages.

Example:

contracts/sOlympusERC20.sol
79function setIndex( uint _INDEX ) external {
80    require( msg.sender == initializer );
81    require( INDEX == 0 );
82    INDEX = gonsForBalance( _INDEX );
83}
84

85function setgOHM( address _gOHM ) external {
86    require( msg.sender == initializer );
87    require( address( gOHM ) == address(0) );
88    require( _gOHM != address(0) );
89    gOHM = IgOHM( _gOHM );
90}
91

92// do this last
93function initialize( address stakingContract_ ) external {
94    require( msg.sender == initializer );
95

96    require( stakingContract_ != address(0) );
97    stakingContract = stakingContract_;
98    _gonBalances[ stakingContract ] = TOTAL_GONS;
99

100    emit Transfer( address(0x0), stakingContract, _totalSupply );
101    emit LogStakingContractUpdated( stakingContract_ );
102    
103    initializer = address(0);
104}

Recommendation:

We advise them to be set so to aid in the debugging of the application and to also enable more accurate validation of the require conditions.

Alleviation:

Error messages were introduced in all linked require checks.

OEC-04C: Inexistent Variable Visibility Specifiers

TypeSeverityLocation
Code StyleInformationalsOlympusERC20.sol:L45, L47

Description:

The linked variables have no visibility specifier explicitly set.

Example:

contracts/sOlympusERC20.sol
45address initializer;
46

47uint INDEX; // Index Gons - tracks rebase growth

Recommendation:

We advise one to be set so to avoid potential compilation discrepancies in the future as the current compiler behaviour is to assign a specifier automatically.

Alleviation:

The Olympus DAO team considered this exhibit but opted not to apply any remediation for it.

OEC-05C: Redundant Event Argument

TypeSeverityLocation
Code StyleInformationalsOlympusERC20.sol:L20, L118, L159

Description:

The current timestamp that a LogSupply event emits is already attached to each event emittance by the blockchain itself.

Example:

contracts/sOlympusERC20.sol
20event LogSupply(uint256 indexed epoch, uint256 timestamp, uint256 totalSupply );

Recommendation:

We advise the timestamp member to be omitted from the event as it is redundant.

Alleviation:

The redundant event argument was safely omitted from the codebase.

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