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CToken.sol
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CToken.sol
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pragma solidity ^0.5.16;
import "./ComptrollerInterface.sol";
import "./CTokenInterfaces.sol";
import "./ErrorReporter.sol";
import "./Exponential.sol";
import "./EIP20Interface.sol";
import "./EIP20NonStandardInterface.sol";
import "./InterestRateModel.sol";
/**
* @title Compound's CToken Contract
* @notice Abstract base for CTokens
* @author Compound
*/
contract CToken is CTokenInterface, Exponential, TokenErrorReporter {
/**
* @notice Initialize the money market
* @param comptroller_ The address of the Comptroller
* @param interestRateModel_ The address of the interest rate model
* @param initialExchangeRateMantissa_ The initial exchange rate, scaled by 1e18
* @param name_ EIP-20 name of this token
* @param symbol_ EIP-20 symbol of this token
* @param decimals_ EIP-20 decimal precision of this token
*/
function initialize(ComptrollerInterface comptroller_,
InterestRateModel interestRateModel_,
uint initialExchangeRateMantissa_,
string memory name_,
string memory symbol_,
uint8 decimals_) public {
require(msg.sender == admin, "only admin may initialize the market");
require(accrualBlockNumber == 0 && borrowIndex == 0, "market may only be initialized once");
// Set initial exchange rate
initialExchangeRateMantissa = initialExchangeRateMantissa_;
require(initialExchangeRateMantissa > 0, "initial exchange rate must be greater than zero.");
// Set the comptroller
uint err = _setComptroller(comptroller_);
require(err == uint(Error.NO_ERROR), "setting comptroller failed");
// Initialize block number and borrow index (block number mocks depend on comptroller being set)
accrualBlockNumber = getBlockNumber();
borrowIndex = mantissaOne;
// Set the interest rate model (depends on block number / borrow index)
err = _setInterestRateModelFresh(interestRateModel_);
require(err == uint(Error.NO_ERROR), "setting interest rate model failed");
name = name_;
symbol = symbol_;
decimals = decimals_;
// The counter starts true to prevent changing it from zero to non-zero (i.e. smaller cost/refund)
_notEntered = true;
}
/**
* @notice Transfer `amount` tokens from `msg.sender` to `dst`
* @param dst The address of the destination account
* @param amount The number of tokens to transfer
* @return Whether or not the transfer succeeded
*/
function transfer(address dst, uint256 amount) external nonReentrant returns (bool) {
return transferTokens(msg.sender, msg.sender, dst, amount) == uint(Error.NO_ERROR);
}
/**
* @notice Transfer `amount` tokens from `src` to `dst`
* @param src The address of the source account
* @param dst The address of the destination account
* @param amount The number of tokens to transfer
* @return Whether or not the transfer succeeded
*/
function transferFrom(address src, address dst, uint256 amount) external nonReentrant returns (bool) {
return transferTokens(msg.sender, src, dst, amount) == uint(Error.NO_ERROR);
}
/**
* @notice Approve `spender` to transfer up to `amount` from `src`
* @dev This will overwrite the approval amount for `spender`
* and is subject to issues noted [here](https://eips.ethereum.org/EIPS/eip-20#approve)
* @param spender The address of the account which may transfer tokens
* @param amount The number of tokens that are approved (-1 means infinite)
* @return Whether or not the approval succeeded
*/
function approve(address spender, uint256 amount) external returns (bool) {
address src = msg.sender;
transferAllowances[src][spender] = amount;
emit Approval(src, spender, amount);
return true;
}
/**
* @notice Get the current allowance from `owner` for `spender`
* @param owner The address of the account which owns the tokens to be spent
* @param spender The address of the account which may transfer tokens
* @return The number of tokens allowed to be spent (-1 means infinite)
*/
function allowance(address owner, address spender) external view returns (uint256) {
return transferAllowances[owner][spender];
}
/**
* @notice Get the token balance of the `owner`
* @param owner The address of the account to query
* @return The number of tokens owned by `owner`
*/
function balanceOf(address owner) external view returns (uint256) {
return accountTokens[owner];
}
/**
* @notice Get the underlying balance of the `owner`
* @dev This also accrues interest in a transaction
* @param owner The address of the account to query
* @return The amount of underlying owned by `owner`
*/
function balanceOfUnderlying(address owner) external returns (uint) {
Exp memory exchangeRate = Exp({mantissa: exchangeRateCurrent()});
return mul_ScalarTruncate(exchangeRate, accountTokens[owner]);
}
/**
* @notice Get a snapshot of the account's balances, and the cached exchange rate
* @dev This is used by comptroller to more efficiently perform liquidity checks.
* @param account Address of the account to snapshot
* @return (possible error, token balance, borrow balance, exchange rate mantissa)
*/
function getAccountSnapshot(address account) external view returns (uint, uint, uint, uint) {
uint cTokenBalance = getCTokenBalanceInternal(account);
uint borrowBalance = borrowBalanceStoredInternal(account);
uint exchangeRateMantissa = exchangeRateStoredInternal();
return (uint(Error.NO_ERROR), cTokenBalance, borrowBalance, exchangeRateMantissa);
}
/**
* @dev Function to simply retrieve block number
* This exists mainly for inheriting test contracts to stub this result.
*/
function getBlockNumber() internal view returns (uint) {
return block.number;
}
/**
* @notice Returns the current per-block borrow interest rate for this cToken
* @return The borrow interest rate per block, scaled by 1e18
*/
function borrowRatePerBlock() external view returns (uint) {
return interestRateModel.getBorrowRate(getCashPrior(), totalBorrows, totalReserves);
}
/**
* @notice Returns the current per-block supply interest rate for this cToken
* @return The supply interest rate per block, scaled by 1e18
*/
function supplyRatePerBlock() external view returns (uint) {
return interestRateModel.getSupplyRate(getCashPrior(), totalBorrows, totalReserves, reserveFactorMantissa);
}
/**
* @notice Returns the estimated per-block borrow interest rate for this cToken after some change
* @return The borrow interest rate per block, scaled by 1e18
*/
function estimateBorrowRatePerBlockAfterChange(uint256 change, bool repay) external view returns (uint) {
uint256 cashPriorNew;
uint256 totalBorrowsNew;
if (repay) {
cashPriorNew = add_(getCashPrior(), change);
totalBorrowsNew = sub_(totalBorrows, change);
} else {
cashPriorNew = sub_(getCashPrior(), change);
totalBorrowsNew = add_(totalBorrows, change);
}
return interestRateModel.getBorrowRate(cashPriorNew, totalBorrowsNew, totalReserves);
}
/**
* @notice Returns the estimated per-block supply interest rate for this cToken after some change
* @return The supply interest rate per block, scaled by 1e18
*/
function estimateSupplyRatePerBlockAfterChange(uint256 change, bool repay) external view returns (uint) {
uint256 cashPriorNew;
uint256 totalBorrowsNew;
if (repay) {
cashPriorNew = add_(getCashPrior(), change);
totalBorrowsNew = sub_(totalBorrows, change);
} else {
cashPriorNew = sub_(getCashPrior(), change);
totalBorrowsNew = add_(totalBorrows, change);
}
return interestRateModel.getSupplyRate(cashPriorNew, totalBorrowsNew, totalReserves, reserveFactorMantissa);
}
/**
* @notice Returns the current total borrows plus accrued interest
* @return The total borrows with interest
*/
function totalBorrowsCurrent() external nonReentrant returns (uint) {
require(accrueInterest() == uint(Error.NO_ERROR), "accrue interest failed");
return totalBorrows;
}
/**
* @notice Accrue interest to updated borrowIndex and then calculate account's borrow balance using the updated borrowIndex
* @param account The address whose balance should be calculated after updating borrowIndex
* @return The calculated balance
*/
function borrowBalanceCurrent(address account) external nonReentrant returns (uint) {
require(accrueInterest() == uint(Error.NO_ERROR), "accrue interest failed");
return borrowBalanceStored(account);
}
/**
* @notice Return the borrow balance of account based on stored data
* @param account The address whose balance should be calculated
* @return The calculated balance
*/
function borrowBalanceStored(address account) public view returns (uint) {
return borrowBalanceStoredInternal(account);
}
/**
* @notice Return the borrow balance of account based on stored data
* @param account The address whose balance should be calculated
* @return the calculated balance or 0 if error code is non-zero
*/
function borrowBalanceStoredInternal(address account) internal view returns (uint) {
/* Get borrowBalance and borrowIndex */
BorrowSnapshot storage borrowSnapshot = accountBorrows[account];
/* If borrowBalance = 0 then borrowIndex is likely also 0.
* Rather than failing the calculation with a division by 0, we immediately return 0 in this case.
*/
if (borrowSnapshot.principal == 0) {
return 0;
}
/* Calculate new borrow balance using the interest index:
* recentBorrowBalance = borrower.borrowBalance * market.borrowIndex / borrower.borrowIndex
*/
uint principalTimesIndex = mul_(borrowSnapshot.principal, borrowIndex);
uint result = div_(principalTimesIndex, borrowSnapshot.interestIndex);
return result;
}
/**
* @notice Accrue interest then return the up-to-date exchange rate
* @return Calculated exchange rate scaled by 1e18
*/
function exchangeRateCurrent() public nonReentrant returns (uint) {
require(accrueInterest() == uint(Error.NO_ERROR), "accrue interest failed");
return exchangeRateStored();
}
/**
* @notice Calculates the exchange rate from the underlying to the CToken
* @dev This function does not accrue interest before calculating the exchange rate
* @return Calculated exchange rate scaled by 1e18
*/
function exchangeRateStored() public view returns (uint) {
return exchangeRateStoredInternal();
}
/**
* @notice Calculates the exchange rate from the underlying to the CToken
* @dev This function does not accrue interest before calculating the exchange rate
* @return calculated exchange rate scaled by 1e18
*/
function exchangeRateStoredInternal() internal view returns (uint) {
uint _totalSupply = totalSupply;
if (_totalSupply == 0) {
/*
* If there are no tokens minted:
* exchangeRate = initialExchangeRate
*/
return initialExchangeRateMantissa;
} else {
/*
* Otherwise:
* exchangeRate = (totalCash + totalBorrows - totalReserves) / totalSupply
*/
uint totalCash = getCashPrior();
uint cashPlusBorrowsMinusReserves = sub_(add_(totalCash, totalBorrows), totalReserves);
uint exchangeRate = div_(cashPlusBorrowsMinusReserves, Exp({mantissa: _totalSupply}));
return exchangeRate;
}
}
/**
* @notice Get cash balance of this cToken in the underlying asset
* @return The quantity of underlying asset owned by this contract
*/
function getCash() external view returns (uint) {
return getCashPrior();
}
/**
* @notice Applies accrued interest to total borrows and reserves
* @dev This calculates interest accrued from the last checkpointed block
* up to the current block and writes new checkpoint to storage.
*/
function accrueInterest() public returns (uint) {
/* Remember the initial block number */
uint currentBlockNumber = getBlockNumber();
uint accrualBlockNumberPrior = accrualBlockNumber;
/* Short-circuit accumulating 0 interest */
if (accrualBlockNumberPrior == currentBlockNumber) {
return uint(Error.NO_ERROR);
}
/* Read the previous values out of storage */
uint cashPrior = getCashPrior();
uint borrowsPrior = totalBorrows;
uint reservesPrior = totalReserves;
uint borrowIndexPrior = borrowIndex;
/* Calculate the current borrow interest rate */
uint borrowRateMantissa = interestRateModel.getBorrowRate(cashPrior, borrowsPrior, reservesPrior);
require(borrowRateMantissa <= borrowRateMaxMantissa, "borrow rate is absurdly high");
/* Calculate the number of blocks elapsed since the last accrual */
uint blockDelta = sub_(currentBlockNumber, accrualBlockNumberPrior);
/*
* Calculate the interest accumulated into borrows and reserves and the new index:
* simpleInterestFactor = borrowRate * blockDelta
* interestAccumulated = simpleInterestFactor * totalBorrows
* totalBorrowsNew = interestAccumulated + totalBorrows
* totalReservesNew = interestAccumulated * reserveFactor + totalReserves
* borrowIndexNew = simpleInterestFactor * borrowIndex + borrowIndex
*/
Exp memory simpleInterestFactor = mul_(Exp({mantissa: borrowRateMantissa}), blockDelta);
uint interestAccumulated = mul_ScalarTruncate(simpleInterestFactor, borrowsPrior);
uint totalBorrowsNew = add_(interestAccumulated, borrowsPrior);
uint totalReservesNew = mul_ScalarTruncateAddUInt(Exp({mantissa: reserveFactorMantissa}), interestAccumulated, reservesPrior);
uint borrowIndexNew = mul_ScalarTruncateAddUInt(simpleInterestFactor, borrowIndexPrior, borrowIndexPrior);
/////////////////////////
// EFFECTS & INTERACTIONS
// (No safe failures beyond this point)
/* We write the previously calculated values into storage */
accrualBlockNumber = currentBlockNumber;
borrowIndex = borrowIndexNew;
totalBorrows = totalBorrowsNew;
totalReserves = totalReservesNew;
/* We emit an AccrueInterest event */
emit AccrueInterest(cashPrior, interestAccumulated, borrowIndexNew, totalBorrowsNew);
return uint(Error.NO_ERROR);
}
/**
* @notice Sender supplies assets into the market and receives cTokens in exchange
* @dev Accrues interest whether or not the operation succeeds, unless reverted
* @param mintAmount The amount of the underlying asset to supply
* @return (uint, uint) An error code (0=success, otherwise a failure, see ErrorReporter.sol), and the actual mint amount.
*/
function mintInternal(uint mintAmount) internal nonReentrant returns (uint, uint) {
uint error = accrueInterest();
if (error != uint(Error.NO_ERROR)) {
// accrueInterest emits logs on errors, but we still want to log the fact that an attempted borrow failed
return (fail(Error(error), FailureInfo.MINT_ACCRUE_INTEREST_FAILED), 0);
}
// mintFresh emits the actual Mint event if successful and logs on errors, so we don't need to
return mintFresh(msg.sender, mintAmount);
}
/**
* @notice Sender redeems cTokens in exchange for the underlying asset
* @dev Accrues interest whether or not the operation succeeds, unless reverted
* @param redeemTokens The number of cTokens to redeem into underlying
* @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
*/
function redeemInternal(uint redeemTokens) internal nonReentrant returns (uint) {
uint error = accrueInterest();
if (error != uint(Error.NO_ERROR)) {
// accrueInterest emits logs on errors, but we still want to log the fact that an attempted redeem failed
return fail(Error(error), FailureInfo.REDEEM_ACCRUE_INTEREST_FAILED);
}
// redeemFresh emits redeem-specific logs on errors, so we don't need to
return redeemFresh(msg.sender, redeemTokens, 0);
}
/**
* @notice Sender redeems cTokens in exchange for a specified amount of underlying asset
* @dev Accrues interest whether or not the operation succeeds, unless reverted
* @param redeemAmount The amount of underlying to receive from redeeming cTokens
* @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
*/
function redeemUnderlyingInternal(uint redeemAmount) internal nonReentrant returns (uint) {
uint error = accrueInterest();
if (error != uint(Error.NO_ERROR)) {
// accrueInterest emits logs on errors, but we still want to log the fact that an attempted redeem failed
return fail(Error(error), FailureInfo.REDEEM_ACCRUE_INTEREST_FAILED);
}
// redeemFresh emits redeem-specific logs on errors, so we don't need to
return redeemFresh(msg.sender, 0, redeemAmount);
}
/**
* @notice Sender borrows assets from the protocol to their own address
* @param borrowAmount The amount of the underlying asset to borrow
* @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
*/
function borrowInternal(uint borrowAmount) internal nonReentrant returns (uint) {
uint error = accrueInterest();
if (error != uint(Error.NO_ERROR)) {
// accrueInterest emits logs on errors, but we still want to log the fact that an attempted borrow failed
return fail(Error(error), FailureInfo.BORROW_ACCRUE_INTEREST_FAILED);
}
// borrowFresh emits borrow-specific logs on errors, so we don't need to
return borrowFresh(msg.sender, borrowAmount);
}
struct BorrowLocalVars {
MathError mathErr;
uint accountBorrows;
uint accountBorrowsNew;
uint totalBorrowsNew;
}
/**
* @notice Users borrow assets from the protocol to their own address
* @param borrowAmount The amount of the underlying asset to borrow
* @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
*/
function borrowFresh(address payable borrower, uint borrowAmount) internal returns (uint) {
/* Fail if borrow not allowed */
uint allowed = comptroller.borrowAllowed(address(this), borrower, borrowAmount);
if (allowed != 0) {
return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.BORROW_COMPTROLLER_REJECTION, allowed);
}
/* Verify market's block number equals current block number */
if (accrualBlockNumber != getBlockNumber()) {
return fail(Error.MARKET_NOT_FRESH, FailureInfo.BORROW_FRESHNESS_CHECK);
}
/* Fail gracefully if protocol has insufficient underlying cash */
if (getCashPrior() < borrowAmount) {
return fail(Error.TOKEN_INSUFFICIENT_CASH, FailureInfo.BORROW_CASH_NOT_AVAILABLE);
}
BorrowLocalVars memory vars;
/*
* We calculate the new borrower and total borrow balances, failing on overflow:
* accountBorrowsNew = accountBorrows + borrowAmount
* totalBorrowsNew = totalBorrows + borrowAmount
*/
vars.accountBorrows = borrowBalanceStoredInternal(borrower);
vars.accountBorrowsNew = add_(vars.accountBorrows, borrowAmount);
vars.totalBorrowsNew = add_(totalBorrows, borrowAmount);
/////////////////////////
// EFFECTS & INTERACTIONS
// (No safe failures beyond this point)
/*
* We invoke doTransferOut for the borrower and the borrowAmount.
* Note: The cToken must handle variations between ERC-20 and ETH underlying.
* On success, the cToken borrowAmount less of cash.
* doTransferOut reverts if anything goes wrong, since we can't be sure if side effects occurred.
*/
doTransferOut(borrower, borrowAmount);
/* We write the previously calculated values into storage */
accountBorrows[borrower].principal = vars.accountBorrowsNew;
accountBorrows[borrower].interestIndex = borrowIndex;
totalBorrows = vars.totalBorrowsNew;
/* We emit a Borrow event */
emit Borrow(borrower, borrowAmount, vars.accountBorrowsNew, vars.totalBorrowsNew);
/* We call the defense hook */
// unused function
// comptroller.borrowVerify(address(this), borrower, borrowAmount);
return uint(Error.NO_ERROR);
}
/**
* @notice Sender repays their own borrow
* @param repayAmount The amount to repay
* @return (uint, uint) An error code (0=success, otherwise a failure, see ErrorReporter.sol), and the actual repayment amount.
*/
function repayBorrowInternal(uint repayAmount) internal nonReentrant returns (uint, uint) {
uint error = accrueInterest();
if (error != uint(Error.NO_ERROR)) {
// accrueInterest emits logs on errors, but we still want to log the fact that an attempted borrow failed
return (fail(Error(error), FailureInfo.REPAY_BORROW_ACCRUE_INTEREST_FAILED), 0);
}
// repayBorrowFresh emits repay-borrow-specific logs on errors, so we don't need to
return repayBorrowFresh(msg.sender, msg.sender, repayAmount);
}
/**
* @notice Sender repays a borrow belonging to borrower
* @param borrower the account with the debt being payed off
* @param repayAmount The amount to repay
* @return (uint, uint) An error code (0=success, otherwise a failure, see ErrorReporter.sol), and the actual repayment amount.
*/
function repayBorrowBehalfInternal(address borrower, uint repayAmount) internal nonReentrant returns (uint, uint) {
uint error = accrueInterest();
if (error != uint(Error.NO_ERROR)) {
// accrueInterest emits logs on errors, but we still want to log the fact that an attempted borrow failed
return (fail(Error(error), FailureInfo.REPAY_BEHALF_ACCRUE_INTEREST_FAILED), 0);
}
// repayBorrowFresh emits repay-borrow-specific logs on errors, so we don't need to
return repayBorrowFresh(msg.sender, borrower, repayAmount);
}
struct RepayBorrowLocalVars {
Error err;
MathError mathErr;
uint repayAmount;
uint borrowerIndex;
uint accountBorrows;
uint accountBorrowsNew;
uint totalBorrowsNew;
uint actualRepayAmount;
}
/**
* @notice Borrows are repaid by another user (possibly the borrower).
* @param payer the account paying off the borrow
* @param borrower the account with the debt being payed off
* @param repayAmount the amount of undelrying tokens being returned
* @return (uint, uint) An error code (0=success, otherwise a failure, see ErrorReporter.sol), and the actual repayment amount.
*/
function repayBorrowFresh(address payer, address borrower, uint repayAmount) internal returns (uint, uint) {
/* Fail if repayBorrow not allowed */
uint allowed = comptroller.repayBorrowAllowed(address(this), payer, borrower, repayAmount);
if (allowed != 0) {
return (failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.REPAY_BORROW_COMPTROLLER_REJECTION, allowed), 0);
}
/* Verify market's block number equals current block number */
if (accrualBlockNumber != getBlockNumber()) {
return (fail(Error.MARKET_NOT_FRESH, FailureInfo.REPAY_BORROW_FRESHNESS_CHECK), 0);
}
RepayBorrowLocalVars memory vars;
/* We remember the original borrowerIndex for verification purposes */
vars.borrowerIndex = accountBorrows[borrower].interestIndex;
/* We fetch the amount the borrower owes, with accumulated interest */
vars.accountBorrows = borrowBalanceStoredInternal(borrower);
/* If repayAmount == -1, repayAmount = accountBorrows */
if (repayAmount == uint(-1)) {
vars.repayAmount = vars.accountBorrows;
} else {
vars.repayAmount = repayAmount;
}
/////////////////////////
// EFFECTS & INTERACTIONS
// (No safe failures beyond this point)
/*
* We call doTransferIn for the payer and the repayAmount
* Note: The cToken must handle variations between ERC-20 and ETH underlying.
* On success, the cToken holds an additional repayAmount of cash.
* doTransferIn reverts if anything goes wrong, since we can't be sure if side effects occurred.
* it returns the amount actually transferred, in case of a fee.
*/
vars.actualRepayAmount = doTransferIn(payer, vars.repayAmount);
/*
* We calculate the new borrower and total borrow balances, failing on underflow:
* accountBorrowsNew = accountBorrows - actualRepayAmount
* totalBorrowsNew = totalBorrows - actualRepayAmount
*/
vars.accountBorrowsNew = sub_(vars.accountBorrows, vars.actualRepayAmount);
vars.totalBorrowsNew = sub_(totalBorrows, vars.actualRepayAmount);
/* We write the previously calculated values into storage */
accountBorrows[borrower].principal = vars.accountBorrowsNew;
accountBorrows[borrower].interestIndex = borrowIndex;
totalBorrows = vars.totalBorrowsNew;
/* We emit a RepayBorrow event */
emit RepayBorrow(payer, borrower, vars.actualRepayAmount, vars.accountBorrowsNew, vars.totalBorrowsNew);
/* We call the defense hook */
// unused function
// comptroller.repayBorrowVerify(address(this), payer, borrower, vars.actualRepayAmount, vars.borrowerIndex);
return (uint(Error.NO_ERROR), vars.actualRepayAmount);
}
/**
* @notice The sender liquidates the borrowers collateral.
* The collateral seized is transferred to the liquidator.
* @param borrower The borrower of this cToken to be liquidated
* @param cTokenCollateral The market in which to seize collateral from the borrower
* @param repayAmount The amount of the underlying borrowed asset to repay
* @return (uint, uint) An error code (0=success, otherwise a failure, see ErrorReporter.sol), and the actual repayment amount.
*/
function liquidateBorrowInternal(address borrower, uint repayAmount, CTokenInterface cTokenCollateral) internal nonReentrant returns (uint, uint) {
uint error = accrueInterest();
if (error != uint(Error.NO_ERROR)) {
// accrueInterest emits logs on errors, but we still want to log the fact that an attempted liquidation failed
return (fail(Error(error), FailureInfo.LIQUIDATE_ACCRUE_BORROW_INTEREST_FAILED), 0);
}
error = cTokenCollateral.accrueInterest();
if (error != uint(Error.NO_ERROR)) {
// accrueInterest emits logs on errors, but we still want to log the fact that an attempted liquidation failed
return (fail(Error(error), FailureInfo.LIQUIDATE_ACCRUE_COLLATERAL_INTEREST_FAILED), 0);
}
// liquidateBorrowFresh emits borrow-specific logs on errors, so we don't need to
return liquidateBorrowFresh(msg.sender, borrower, repayAmount, cTokenCollateral);
}
/**
* @notice The liquidator liquidates the borrowers collateral.
* The collateral seized is transferred to the liquidator.
* @param borrower The borrower of this cToken to be liquidated
* @param liquidator The address repaying the borrow and seizing collateral
* @param cTokenCollateral The market in which to seize collateral from the borrower
* @param repayAmount The amount of the underlying borrowed asset to repay
* @return (uint, uint) An error code (0=success, otherwise a failure, see ErrorReporter.sol), and the actual repayment amount.
*/
function liquidateBorrowFresh(address liquidator, address borrower, uint repayAmount, CTokenInterface cTokenCollateral) internal returns (uint, uint) {
/* Fail if liquidate not allowed */
uint allowed = comptroller.liquidateBorrowAllowed(address(this), address(cTokenCollateral), liquidator, borrower, repayAmount);
if (allowed != 0) {
return (failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.LIQUIDATE_COMPTROLLER_REJECTION, allowed), 0);
}
/* Verify market's block number equals current block number */
if (accrualBlockNumber != getBlockNumber()) {
return (fail(Error.MARKET_NOT_FRESH, FailureInfo.LIQUIDATE_FRESHNESS_CHECK), 0);
}
/* Verify cTokenCollateral market's block number equals current block number */
if (cTokenCollateral.accrualBlockNumber() != getBlockNumber()) {
return (fail(Error.MARKET_NOT_FRESH, FailureInfo.LIQUIDATE_COLLATERAL_FRESHNESS_CHECK), 0);
}
/* Fail if borrower = liquidator */
if (borrower == liquidator) {
return (fail(Error.INVALID_ACCOUNT_PAIR, FailureInfo.LIQUIDATE_LIQUIDATOR_IS_BORROWER), 0);
}
/* Fail if repayAmount = 0 */
if (repayAmount == 0) {
return (fail(Error.INVALID_CLOSE_AMOUNT_REQUESTED, FailureInfo.LIQUIDATE_CLOSE_AMOUNT_IS_ZERO), 0);
}
/* Fail if repayAmount = -1 */
if (repayAmount == uint(-1)) {
return (fail(Error.INVALID_CLOSE_AMOUNT_REQUESTED, FailureInfo.LIQUIDATE_CLOSE_AMOUNT_IS_UINT_MAX), 0);
}
/* Fail if repayBorrow fails */
(uint repayBorrowError, uint actualRepayAmount) = repayBorrowFresh(liquidator, borrower, repayAmount);
if (repayBorrowError != uint(Error.NO_ERROR)) {
return (fail(Error(repayBorrowError), FailureInfo.LIQUIDATE_REPAY_BORROW_FRESH_FAILED), 0);
}
/////////////////////////
// EFFECTS & INTERACTIONS
// (No safe failures beyond this point)
/* We calculate the number of collateral tokens that will be seized */
(uint amountSeizeError, uint seizeTokens) = comptroller.liquidateCalculateSeizeTokens(address(this), address(cTokenCollateral), actualRepayAmount);
require(amountSeizeError == uint(Error.NO_ERROR), "LIQUIDATE_COMPTROLLER_CALCULATE_AMOUNT_SEIZE_FAILED");
/* Revert if borrower collateral token balance < seizeTokens */
require(cTokenCollateral.balanceOf(borrower) >= seizeTokens, "LIQUIDATE_SEIZE_TOO_MUCH");
// If this is also the collateral, run seizeInternal to avoid re-entrancy, otherwise make an external call
uint seizeError;
if (address(cTokenCollateral) == address(this)) {
seizeError = seizeInternal(address(this), liquidator, borrower, seizeTokens);
} else {
seizeError = cTokenCollateral.seize(liquidator, borrower, seizeTokens);
}
/* Revert if seize tokens fails (since we cannot be sure of side effects) */
require(seizeError == uint(Error.NO_ERROR), "token seizure failed");
/* We emit a LiquidateBorrow event */
emit LiquidateBorrow(liquidator, borrower, actualRepayAmount, address(cTokenCollateral), seizeTokens);
/* We call the defense hook */
// unused function
// comptroller.liquidateBorrowVerify(address(this), address(cTokenCollateral), liquidator, borrower, actualRepayAmount, seizeTokens);
return (uint(Error.NO_ERROR), actualRepayAmount);
}
/**
* @notice Transfers collateral tokens (this market) to the liquidator.
* @dev Will fail unless called by another cToken during the process of liquidation.
* Its absolutely critical to use msg.sender as the borrowed cToken and not a parameter.
* @param liquidator The account receiving seized collateral
* @param borrower The account having collateral seized
* @param seizeTokens The number of cTokens to seize
* @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
*/
function seize(address liquidator, address borrower, uint seizeTokens) external nonReentrant returns (uint) {
return seizeInternal(msg.sender, liquidator, borrower, seizeTokens);
}
/*** Admin Functions ***/
/**
* @notice Begins transfer of admin rights. The newPendingAdmin must call `_acceptAdmin` to finalize the transfer.
* @dev Admin function to begin change of admin. The newPendingAdmin must call `_acceptAdmin` to finalize the transfer.
* @param newPendingAdmin New pending admin.
* @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
*/
function _setPendingAdmin(address payable newPendingAdmin) external returns (uint) {
// Check caller = admin
if (msg.sender != admin) {
return fail(Error.UNAUTHORIZED, FailureInfo.SET_PENDING_ADMIN_OWNER_CHECK);
}
// Save current value, if any, for inclusion in log
address oldPendingAdmin = pendingAdmin;
// Store pendingAdmin with value newPendingAdmin
pendingAdmin = newPendingAdmin;
// Emit NewPendingAdmin(oldPendingAdmin, newPendingAdmin)
emit NewPendingAdmin(oldPendingAdmin, newPendingAdmin);
return uint(Error.NO_ERROR);
}
/**
* @notice Accepts transfer of admin rights. msg.sender must be pendingAdmin
* @dev Admin function for pending admin to accept role and update admin
* @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
*/
function _acceptAdmin() external returns (uint) {
// Check caller is pendingAdmin and pendingAdmin ≠ address(0)
if (msg.sender != pendingAdmin || msg.sender == address(0)) {
return fail(Error.UNAUTHORIZED, FailureInfo.ACCEPT_ADMIN_PENDING_ADMIN_CHECK);
}
// Save current values for inclusion in log
address oldAdmin = admin;
address oldPendingAdmin = pendingAdmin;
// Store admin with value pendingAdmin
admin = pendingAdmin;
// Clear the pending value
pendingAdmin = address(0);
emit NewAdmin(oldAdmin, admin);
emit NewPendingAdmin(oldPendingAdmin, pendingAdmin);
return uint(Error.NO_ERROR);
}
/**
* @notice Sets a new comptroller for the market
* @dev Admin function to set a new comptroller
* @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
*/
function _setComptroller(ComptrollerInterface newComptroller) public returns (uint) {
// Check caller is admin
if (msg.sender != admin) {
return fail(Error.UNAUTHORIZED, FailureInfo.SET_COMPTROLLER_OWNER_CHECK);
}
ComptrollerInterface oldComptroller = comptroller;
// Ensure invoke comptroller.isComptroller() returns true
require(newComptroller.isComptroller(), "marker method returned false");
// Set market's comptroller to newComptroller
comptroller = newComptroller;
// Emit NewComptroller(oldComptroller, newComptroller)
emit NewComptroller(oldComptroller, newComptroller);
return uint(Error.NO_ERROR);
}
/**
* @notice accrues interest and sets a new reserve factor for the protocol using _setReserveFactorFresh
* @dev Admin function to accrue interest and set a new reserve factor
* @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
*/
function _setReserveFactor(uint newReserveFactorMantissa) external nonReentrant returns (uint) {
uint error = accrueInterest();
if (error != uint(Error.NO_ERROR)) {
// accrueInterest emits logs on errors, but on top of that we want to log the fact that an attempted reserve factor change failed.
return fail(Error(error), FailureInfo.SET_RESERVE_FACTOR_ACCRUE_INTEREST_FAILED);
}
// _setReserveFactorFresh emits reserve-factor-specific logs on errors, so we don't need to.
return _setReserveFactorFresh(newReserveFactorMantissa);
}
/**
* @notice Sets a new reserve factor for the protocol (*requires fresh interest accrual)
* @dev Admin function to set a new reserve factor
* @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
*/
function _setReserveFactorFresh(uint newReserveFactorMantissa) internal returns (uint) {
// Check caller is admin
if (msg.sender != admin) {
return fail(Error.UNAUTHORIZED, FailureInfo.SET_RESERVE_FACTOR_ADMIN_CHECK);
}
// Verify market's block number equals current block number
if (accrualBlockNumber != getBlockNumber()) {
return fail(Error.MARKET_NOT_FRESH, FailureInfo.SET_RESERVE_FACTOR_FRESH_CHECK);
}
// Check newReserveFactor ≤ maxReserveFactor
if (newReserveFactorMantissa > reserveFactorMaxMantissa) {
return fail(Error.BAD_INPUT, FailureInfo.SET_RESERVE_FACTOR_BOUNDS_CHECK);
}
uint oldReserveFactorMantissa = reserveFactorMantissa;
reserveFactorMantissa = newReserveFactorMantissa;
emit NewReserveFactor(oldReserveFactorMantissa, newReserveFactorMantissa);
return uint(Error.NO_ERROR);
}
/**
* @notice Accrues interest and reduces reserves by transferring from msg.sender
* @param addAmount Amount of addition to reserves
* @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
*/
function _addReservesInternal(uint addAmount) internal nonReentrant returns (uint) {
uint error = accrueInterest();
if (error != uint(Error.NO_ERROR)) {
// accrueInterest emits logs on errors, but on top of that we want to log the fact that an attempted reduce reserves failed.
return fail(Error(error), FailureInfo.ADD_RESERVES_ACCRUE_INTEREST_FAILED);
}
// _addReservesFresh emits reserve-addition-specific logs on errors, so we don't need to.
(error, ) = _addReservesFresh(addAmount);
return error;
}
/**
* @notice Add reserves by transferring from caller
* @dev Requires fresh interest accrual
* @param addAmount Amount of addition to reserves
* @return (uint, uint) An error code (0=success, otherwise a failure (see ErrorReporter.sol for details)) and the actual amount added, net token fees
*/
function _addReservesFresh(uint addAmount) internal returns (uint, uint) {
// totalReserves + actualAddAmount
uint totalReservesNew;
uint actualAddAmount;
// We fail gracefully unless market's block number equals current block number
if (accrualBlockNumber != getBlockNumber()) {
return (fail(Error.MARKET_NOT_FRESH, FailureInfo.ADD_RESERVES_FRESH_CHECK), actualAddAmount);
}
/////////////////////////
// EFFECTS & INTERACTIONS
// (No safe failures beyond this point)
/*
* We call doTransferIn for the caller and the addAmount
* Note: The cToken must handle variations between ERC-20 and ETH underlying.
* On success, the cToken holds an additional addAmount of cash.
* doTransferIn reverts if anything goes wrong, since we can't be sure if side effects occurred.
* it returns the amount actually transferred, in case of a fee.
*/
actualAddAmount = doTransferIn(msg.sender, addAmount);
totalReservesNew = add_(totalReserves, actualAddAmount);
// Store reserves[n+1] = reserves[n] + actualAddAmount
totalReserves = totalReservesNew;
/* Emit NewReserves(admin, actualAddAmount, reserves[n+1]) */
emit ReservesAdded(msg.sender, actualAddAmount, totalReservesNew);
/* Return (NO_ERROR, actualAddAmount) */
return (uint(Error.NO_ERROR), actualAddAmount);
}
/**
* @notice Accrues interest and reduces reserves by transferring to admin
* @param reduceAmount Amount of reduction to reserves
* @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
*/
function _reduceReserves(uint reduceAmount) external nonReentrant returns (uint) {
uint error = accrueInterest();
if (error != uint(Error.NO_ERROR)) {
// accrueInterest emits logs on errors, but on top of that we want to log the fact that an attempted reduce reserves failed.
return fail(Error(error), FailureInfo.REDUCE_RESERVES_ACCRUE_INTEREST_FAILED);
}
// _reduceReservesFresh emits reserve-reduction-specific logs on errors, so we don't need to.
return _reduceReservesFresh(reduceAmount);
}
/**
* @notice Reduces reserves by transferring to admin
* @dev Requires fresh interest accrual
* @param reduceAmount Amount of reduction to reserves
* @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
*/
function _reduceReservesFresh(uint reduceAmount) internal returns (uint) {
// totalReserves - reduceAmount
uint totalReservesNew;
// Check caller is admin
if (msg.sender != admin) {
return fail(Error.UNAUTHORIZED, FailureInfo.REDUCE_RESERVES_ADMIN_CHECK);
}
// We fail gracefully unless market's block number equals current block number
if (accrualBlockNumber != getBlockNumber()) {
return fail(Error.MARKET_NOT_FRESH, FailureInfo.REDUCE_RESERVES_FRESH_CHECK);
}
// Fail gracefully if protocol has insufficient underlying cash
if (getCashPrior() < reduceAmount) {
return fail(Error.TOKEN_INSUFFICIENT_CASH, FailureInfo.REDUCE_RESERVES_CASH_NOT_AVAILABLE);
}
// Check reduceAmount ≤ reserves[n] (totalReserves)
if (reduceAmount > totalReserves) {
return fail(Error.BAD_INPUT, FailureInfo.REDUCE_RESERVES_VALIDATION);
}
/////////////////////////
// EFFECTS & INTERACTIONS
// (No safe failures beyond this point)
totalReservesNew = sub_(totalReserves, reduceAmount);
// Store reserves[n+1] = reserves[n] - reduceAmount
totalReserves = totalReservesNew;
// doTransferOut reverts if anything goes wrong, since we can't be sure if side effects occurred.
doTransferOut(admin, reduceAmount);
emit ReservesReduced(admin, reduceAmount, totalReservesNew);
return uint(Error.NO_ERROR);
}
/**
* @notice accrues interest and updates the interest rate model using _setInterestRateModelFresh
* @dev Admin function to accrue interest and update the interest rate model
* @param newInterestRateModel the new interest rate model to use
* @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
*/
function _setInterestRateModel(InterestRateModel newInterestRateModel) public returns (uint) {
uint error = accrueInterest();
if (error != uint(Error.NO_ERROR)) {
// accrueInterest emits logs on errors, but on top of that we want to log the fact that an attempted change of interest rate model failed
return fail(Error(error), FailureInfo.SET_INTEREST_RATE_MODEL_ACCRUE_INTEREST_FAILED);
}
// _setInterestRateModelFresh emits interest-rate-model-update-specific logs on errors, so we don't need to.
return _setInterestRateModelFresh(newInterestRateModel);
}
/**
* @notice updates the interest rate model (*requires fresh interest accrual)
* @dev Admin function to update the interest rate model
* @param newInterestRateModel the new interest rate model to use
* @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
*/
function _setInterestRateModelFresh(InterestRateModel newInterestRateModel) internal returns (uint) {
// Used to store old model for use in the event that is emitted on success
InterestRateModel oldInterestRateModel;
// Check caller is admin
if (msg.sender != admin) {
return fail(Error.UNAUTHORIZED, FailureInfo.SET_INTEREST_RATE_MODEL_OWNER_CHECK);
}
// We fail gracefully unless market's block number equals current block number
if (accrualBlockNumber != getBlockNumber()) {
return fail(Error.MARKET_NOT_FRESH, FailureInfo.SET_INTEREST_RATE_MODEL_FRESH_CHECK);
}