Contract Source Code:
File 1 of 1 : BToken
// SPDX-License-Identifier: BUSL-1.1
pragma solidity 0.8.6;
// Part: IBetaBank
interface IBetaBank {
/// @dev Returns the address of BToken of the given underlying token, or 0 if not exists.
function bTokens(address _underlying) external view returns (address);
/// @dev Returns the address of the underlying of the given BToken, or 0 if not exists.
function underlyings(address _bToken) external view returns (address);
/// @dev Returns the address of the oracle contract.
function oracle() external view returns (address);
/// @dev Returns the address of the config contract.
function config() external view returns (address);
/// @dev Returns the interest rate model smart contract.
function interestModel() external view returns (address);
/// @dev Returns the position's collateral token and AmToken.
function getPositionTokens(address _owner, uint _pid)
external
view
returns (address _collateral, address _bToken);
/// @dev Returns the debt of the given position. Can't be view as it needs to call accrue.
function fetchPositionDebt(address _owner, uint _pid) external returns (uint);
/// @dev Returns the LTV of the given position. Can't be view as it needs to call accrue.
function fetchPositionLTV(address _owner, uint _pid) external returns (uint);
/// @dev Opens a new position in the Beta smart contract.
function open(
address _owner,
address _underlying,
address _collateral
) external returns (uint pid);
/// @dev Borrows tokens on the given position.
function borrow(
address _owner,
uint _pid,
uint _amount
) external;
/// @dev Repays tokens on the given position.
function repay(
address _owner,
uint _pid,
uint _amount
) external;
/// @dev Puts more collateral to the given position.
function put(
address _owner,
uint _pid,
uint _amount
) external;
/// @dev Takes some collateral out of the position.
function take(
address _owner,
uint _pid,
uint _amount
) external;
/// @dev Liquidates the given position.
function liquidate(
address _owner,
uint _pid,
uint _amount
) external;
}
// Part: IBetaConfig
interface IBetaConfig {
/// @dev Returns the risk level for the given asset.
function getRiskLevel(address token) external view returns (uint);
/// @dev Returns the rate of interest collected to be distributed to the protocol reserve.
function reserveRate() external view returns (uint);
/// @dev Returns the beneficiary to receive a portion interest rate for the protocol.
function reserveBeneficiary() external view returns (address);
/// @dev Returns the ratio of which the given token consider for collateral value.
function getCollFactor(address token) external view returns (uint);
/// @dev Returns the max amount of collateral to accept globally.
function getCollMaxAmount(address token) external view returns (uint);
/// @dev Returns max ltv of collateral / debt to allow a new position.
function getSafetyLTV(address token) external view returns (uint);
/// @dev Returns max ltv of collateral / debt to liquidate a position of the given token.
function getLiquidationLTV(address token) external view returns (uint);
/// @dev Returns the bonus incentive reward factor for liquidators.
function getKillBountyRate(address token) external view returns (uint);
}
// Part: IBetaInterestModel
interface IBetaInterestModel {
/// @dev Returns the initial interest rate per year (times 1e18).
function initialRate() external view returns (uint);
/// @dev Returns the next interest rate for the market.
/// @param prevRate The current interest rate.
/// @param totalAvailable The current available liquidity.
/// @param totalLoan The current outstanding loan.
/// @param timePast The time past since last interest rate rebase in seconds.
function getNextInterestRate(
uint prevRate,
uint totalAvailable,
uint totalLoan,
uint timePast
) external view returns (uint);
}
// Part: OpenZeppelin/[email protected]/Address
/**
* @dev Collection of functions related to the address type
*/
library Address {
/**
* @dev Returns true if `account` is a contract.
*
* [IMPORTANT]
* ====
* It is unsafe to assume that an address for which this function returns
* false is an externally-owned account (EOA) and not a contract.
*
* Among others, `isContract` will return false for the following
* types of addresses:
*
* - an externally-owned account
* - a contract in construction
* - an address where a contract will be created
* - an address where a contract lived, but was destroyed
* ====
*/
function isContract(address account) internal view returns (bool) {
// This method relies on extcodesize, which returns 0 for contracts in
// construction, since the code is only stored at the end of the
// constructor execution.
uint256 size;
assembly {
size := extcodesize(account)
}
return size > 0;
}
/**
* @dev Replacement for Solidity's `transfer`: sends `amount` wei to
* `recipient`, forwarding all available gas and reverting on errors.
*
* https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
* of certain opcodes, possibly making contracts go over the 2300 gas limit
* imposed by `transfer`, making them unable to receive funds via
* `transfer`. {sendValue} removes this limitation.
*
* https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
*
* IMPORTANT: because control is transferred to `recipient`, care must be
* taken to not create reentrancy vulnerabilities. Consider using
* {ReentrancyGuard} or the
* https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
*/
function sendValue(address payable recipient, uint256 amount) internal {
require(address(this).balance >= amount, "Address: insufficient balance");
(bool success, ) = recipient.call{value: amount}("");
require(success, "Address: unable to send value, recipient may have reverted");
}
/**
* @dev Performs a Solidity function call using a low level `call`. A
* plain `call` is an unsafe replacement for a function call: use this
* function instead.
*
* If `target` reverts with a revert reason, it is bubbled up by this
* function (like regular Solidity function calls).
*
* Returns the raw returned data. To convert to the expected return value,
* use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
*
* Requirements:
*
* - `target` must be a contract.
* - calling `target` with `data` must not revert.
*
* _Available since v3.1._
*/
function functionCall(address target, bytes memory data) internal returns (bytes memory) {
return functionCall(target, data, "Address: low-level call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
* `errorMessage` as a fallback revert reason when `target` reverts.
*
* _Available since v3.1._
*/
function functionCall(
address target,
bytes memory data,
string memory errorMessage
) internal returns (bytes memory) {
return functionCallWithValue(target, data, 0, errorMessage);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but also transferring `value` wei to `target`.
*
* Requirements:
*
* - the calling contract must have an ETH balance of at least `value`.
* - the called Solidity function must be `payable`.
*
* _Available since v3.1._
*/
function functionCallWithValue(
address target,
bytes memory data,
uint256 value
) internal returns (bytes memory) {
return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
}
/**
* @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
* with `errorMessage` as a fallback revert reason when `target` reverts.
*
* _Available since v3.1._
*/
function functionCallWithValue(
address target,
bytes memory data,
uint256 value,
string memory errorMessage
) internal returns (bytes memory) {
require(address(this).balance >= value, "Address: insufficient balance for call");
require(isContract(target), "Address: call to non-contract");
(bool success, bytes memory returndata) = target.call{value: value}(data);
return _verifyCallResult(success, returndata, errorMessage);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but performing a static call.
*
* _Available since v3.3._
*/
function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
return functionStaticCall(target, data, "Address: low-level static call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
* but performing a static call.
*
* _Available since v3.3._
*/
function functionStaticCall(
address target,
bytes memory data,
string memory errorMessage
) internal view returns (bytes memory) {
require(isContract(target), "Address: static call to non-contract");
(bool success, bytes memory returndata) = target.staticcall(data);
return _verifyCallResult(success, returndata, errorMessage);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but performing a delegate call.
*
* _Available since v3.4._
*/
function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
return functionDelegateCall(target, data, "Address: low-level delegate call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
* but performing a delegate call.
*
* _Available since v3.4._
*/
function functionDelegateCall(
address target,
bytes memory data,
string memory errorMessage
) internal returns (bytes memory) {
require(isContract(target), "Address: delegate call to non-contract");
(bool success, bytes memory returndata) = target.delegatecall(data);
return _verifyCallResult(success, returndata, errorMessage);
}
function _verifyCallResult(
bool success,
bytes memory returndata,
string memory errorMessage
) private pure returns (bytes memory) {
if (success) {
return returndata;
} else {
// Look for revert reason and bubble it up if present
if (returndata.length > 0) {
// The easiest way to bubble the revert reason is using memory via assembly
assembly {
let returndata_size := mload(returndata)
revert(add(32, returndata), returndata_size)
}
} else {
revert(errorMessage);
}
}
}
}
// Part: OpenZeppelin/[email protected]/Context
/*
* @dev Provides information about the current execution context, including the
* sender of the transaction and its data. While these are generally available
* via msg.sender and msg.data, they should not be accessed in such a direct
* manner, since when dealing with meta-transactions the account sending and
* paying for execution may not be the actual sender (as far as an application
* is concerned).
*
* This contract is only required for intermediate, library-like contracts.
*/
abstract contract Context {
function _msgSender() internal view virtual returns (address) {
return msg.sender;
}
function _msgData() internal view virtual returns (bytes calldata) {
return msg.data;
}
}
// Part: OpenZeppelin/[email protected]/Counters
/**
* @title Counters
* @author Matt Condon (@shrugs)
* @dev Provides counters that can only be incremented, decremented or reset. This can be used e.g. to track the number
* of elements in a mapping, issuing ERC721 ids, or counting request ids.
*
* Include with `using Counters for Counters.Counter;`
*/
library Counters {
struct Counter {
// This variable should never be directly accessed by users of the library: interactions must be restricted to
// the library's function. As of Solidity v0.5.2, this cannot be enforced, though there is a proposal to add
// this feature: see https://github.com/ethereum/solidity/issues/4637
uint256 _value; // default: 0
}
function current(Counter storage counter) internal view returns (uint256) {
return counter._value;
}
function increment(Counter storage counter) internal {
unchecked {
counter._value += 1;
}
}
function decrement(Counter storage counter) internal {
uint256 value = counter._value;
require(value > 0, "Counter: decrement overflow");
unchecked {
counter._value = value - 1;
}
}
function reset(Counter storage counter) internal {
counter._value = 0;
}
}
// Part: OpenZeppelin/[email protected]/ECDSA
/**
* @dev Elliptic Curve Digital Signature Algorithm (ECDSA) operations.
*
* These functions can be used to verify that a message was signed by the holder
* of the private keys of a given address.
*/
library ECDSA {
/**
* @dev Returns the address that signed a hashed message (`hash`) with
* `signature`. This address can then be used for verification purposes.
*
* The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
* this function rejects them by requiring the `s` value to be in the lower
* half order, and the `v` value to be either 27 or 28.
*
* IMPORTANT: `hash` _must_ be the result of a hash operation for the
* verification to be secure: it is possible to craft signatures that
* recover to arbitrary addresses for non-hashed data. A safe way to ensure
* this is by receiving a hash of the original message (which may otherwise
* be too long), and then calling {toEthSignedMessageHash} on it.
*
* Documentation for signature generation:
* - with https://web3js.readthedocs.io/en/v1.3.4/web3-eth-accounts.html#sign[Web3.js]
* - with https://docs.ethers.io/v5/api/signer/#Signer-signMessage[ethers]
*/
function recover(bytes32 hash, bytes memory signature) internal pure returns (address) {
// Check the signature length
// - case 65: r,s,v signature (standard)
// - case 64: r,vs signature (cf https://eips.ethereum.org/EIPS/eip-2098) _Available since v4.1._
if (signature.length == 65) {
bytes32 r;
bytes32 s;
uint8 v;
// ecrecover takes the signature parameters, and the only way to get them
// currently is to use assembly.
assembly {
r := mload(add(signature, 0x20))
s := mload(add(signature, 0x40))
v := byte(0, mload(add(signature, 0x60)))
}
return recover(hash, v, r, s);
} else if (signature.length == 64) {
bytes32 r;
bytes32 vs;
// ecrecover takes the signature parameters, and the only way to get them
// currently is to use assembly.
assembly {
r := mload(add(signature, 0x20))
vs := mload(add(signature, 0x40))
}
return recover(hash, r, vs);
} else {
revert("ECDSA: invalid signature length");
}
}
/**
* @dev Overload of {ECDSA-recover} that receives the `r` and `vs` short-signature fields separately.
*
* See https://eips.ethereum.org/EIPS/eip-2098[EIP-2098 short signatures]
*
* _Available since v4.2._
*/
function recover(
bytes32 hash,
bytes32 r,
bytes32 vs
) internal pure returns (address) {
bytes32 s;
uint8 v;
assembly {
s := and(vs, 0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff)
v := add(shr(255, vs), 27)
}
return recover(hash, v, r, s);
}
/**
* @dev Overload of {ECDSA-recover} that receives the `v`, `r` and `s` signature fields separately.
*/
function recover(
bytes32 hash,
uint8 v,
bytes32 r,
bytes32 s
) internal pure returns (address) {
// EIP-2 still allows signature malleability for ecrecover(). Remove this possibility and make the signature
// unique. Appendix F in the Ethereum Yellow paper (https://ethereum.github.io/yellowpaper/paper.pdf), defines
// the valid range for s in (281): 0 < s < secp256k1n ÷ 2 + 1, and for v in (282): v ∈ {27, 28}. Most
// signatures from current libraries generate a unique signature with an s-value in the lower half order.
//
// If your library generates malleable signatures, such as s-values in the upper range, calculate a new s-value
// with 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 - s1 and flip v from 27 to 28 or
// vice versa. If your library also generates signatures with 0/1 for v instead 27/28, add 27 to v to accept
// these malleable signatures as well.
require(
uint256(s) <= 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0,
"ECDSA: invalid signature 's' value"
);
require(v == 27 || v == 28, "ECDSA: invalid signature 'v' value");
// If the signature is valid (and not malleable), return the signer address
address signer = ecrecover(hash, v, r, s);
require(signer != address(0), "ECDSA: invalid signature");
return signer;
}
/**
* @dev Returns an Ethereum Signed Message, created from a `hash`. This
* produces hash corresponding to the one signed with the
* https://eth.wiki/json-rpc/API#eth_sign[`eth_sign`]
* JSON-RPC method as part of EIP-191.
*
* See {recover}.
*/
function toEthSignedMessageHash(bytes32 hash) internal pure returns (bytes32) {
// 32 is the length in bytes of hash,
// enforced by the type signature above
return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", hash));
}
/**
* @dev Returns an Ethereum Signed Typed Data, created from a
* `domainSeparator` and a `structHash`. This produces hash corresponding
* to the one signed with the
* https://eips.ethereum.org/EIPS/eip-712[`eth_signTypedData`]
* JSON-RPC method as part of EIP-712.
*
* See {recover}.
*/
function toTypedDataHash(bytes32 domainSeparator, bytes32 structHash) internal pure returns (bytes32) {
return keccak256(abi.encodePacked("\x19\x01", domainSeparator, structHash));
}
}
// Part: OpenZeppelin/[email protected]/IERC20
/**
* @dev Interface of the ERC20 standard as defined in the EIP.
*/
interface IERC20 {
/**
* @dev Returns the amount of tokens in existence.
*/
function totalSupply() external view returns (uint256);
/**
* @dev Returns the amount of tokens owned by `account`.
*/
function balanceOf(address account) external view returns (uint256);
/**
* @dev Moves `amount` tokens from the caller's account to `recipient`.
*
* Returns a boolean value indicating whether the operation succeeded.
*
* Emits a {Transfer} event.
*/
function transfer(address recipient, uint256 amount) external returns (bool);
/**
* @dev Returns the remaining number of tokens that `spender` will be
* allowed to spend on behalf of `owner` through {transferFrom}. This is
* zero by default.
*
* This value changes when {approve} or {transferFrom} are called.
*/
function allowance(address owner, address spender) external view returns (uint256);
/**
* @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
*
* Returns a boolean value indicating whether the operation succeeded.
*
* IMPORTANT: Beware that changing an allowance with this method brings the risk
* that someone may use both the old and the new allowance by unfortunate
* transaction ordering. One possible solution to mitigate this race
* condition is to first reduce the spender's allowance to 0 and set the
* desired value afterwards:
* https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
*
* Emits an {Approval} event.
*/
function approve(address spender, uint256 amount) external returns (bool);
/**
* @dev Moves `amount` tokens from `sender` to `recipient` using the
* allowance mechanism. `amount` is then deducted from the caller's
* allowance.
*
* Returns a boolean value indicating whether the operation succeeded.
*
* Emits a {Transfer} event.
*/
function transferFrom(
address sender,
address recipient,
uint256 amount
) external returns (bool);
/**
* @dev Emitted when `value` tokens are moved from one account (`from`) to
* another (`to`).
*
* Note that `value` may be zero.
*/
event Transfer(address indexed from, address indexed to, uint256 value);
/**
* @dev Emitted when the allowance of a `spender` for an `owner` is set by
* a call to {approve}. `value` is the new allowance.
*/
event Approval(address indexed owner, address indexed spender, uint256 value);
}
// Part: OpenZeppelin/[email protected]/IERC20Permit
/**
* @dev Interface of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
* https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
*
* Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
* presenting a message signed by the account. By not relying on {IERC20-approve}, the token holder account doesn't
* need to send a transaction, and thus is not required to hold Ether at all.
*/
interface IERC20Permit {
/**
* @dev Sets `value` as the allowance of `spender` over ``owner``'s tokens,
* given ``owner``'s signed approval.
*
* IMPORTANT: The same issues {IERC20-approve} has related to transaction
* ordering also apply here.
*
* Emits an {Approval} event.
*
* Requirements:
*
* - `spender` cannot be the zero address.
* - `deadline` must be a timestamp in the future.
* - `v`, `r` and `s` must be a valid `secp256k1` signature from `owner`
* over the EIP712-formatted function arguments.
* - the signature must use ``owner``'s current nonce (see {nonces}).
*
* For more information on the signature format, see the
* https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP
* section].
*/
function permit(
address owner,
address spender,
uint256 value,
uint256 deadline,
uint8 v,
bytes32 r,
bytes32 s
) external;
/**
* @dev Returns the current nonce for `owner`. This value must be
* included whenever a signature is generated for {permit}.
*
* Every successful call to {permit} increases ``owner``'s nonce by one. This
* prevents a signature from being used multiple times.
*/
function nonces(address owner) external view returns (uint256);
/**
* @dev Returns the domain separator used in the encoding of the signature for {permit}, as defined by {EIP712}.
*/
// solhint-disable-next-line func-name-mixedcase
function DOMAIN_SEPARATOR() external view returns (bytes32);
}
// Part: OpenZeppelin/[email protected]/Math
/**
* @dev Standard math utilities missing in the Solidity language.
*/
library Math {
/**
* @dev Returns the largest of two numbers.
*/
function max(uint256 a, uint256 b) internal pure returns (uint256) {
return a >= b ? a : b;
}
/**
* @dev Returns the smallest of two numbers.
*/
function min(uint256 a, uint256 b) internal pure returns (uint256) {
return a < b ? a : b;
}
/**
* @dev Returns the average of two numbers. The result is rounded towards
* zero.
*/
function average(uint256 a, uint256 b) internal pure returns (uint256) {
// (a + b) / 2 can overflow, so we distribute.
return (a / 2) + (b / 2) + (((a % 2) + (b % 2)) / 2);
}
/**
* @dev Returns the ceiling of the division of two numbers.
*
* This differs from standard division with `/` in that it rounds up instead
* of rounding down.
*/
function ceilDiv(uint256 a, uint256 b) internal pure returns (uint256) {
// (a + b - 1) / b can overflow on addition, so we distribute.
return a / b + (a % b == 0 ? 0 : 1);
}
}
// Part: OpenZeppelin/[email protected]/ReentrancyGuard
/**
* @dev Contract module that helps prevent reentrant calls to a function.
*
* Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
* available, which can be applied to functions to make sure there are no nested
* (reentrant) calls to them.
*
* Note that because there is a single `nonReentrant` guard, functions marked as
* `nonReentrant` may not call one another. This can be worked around by making
* those functions `private`, and then adding `external` `nonReentrant` entry
* points to them.
*
* TIP: If you would like to learn more about reentrancy and alternative ways
* to protect against it, check out our blog post
* https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
*/
abstract contract ReentrancyGuard {
// Booleans are more expensive than uint256 or any type that takes up a full
// word because each write operation emits an extra SLOAD to first read the
// slot's contents, replace the bits taken up by the boolean, and then write
// back. This is the compiler's defense against contract upgrades and
// pointer aliasing, and it cannot be disabled.
// The values being non-zero value makes deployment a bit more expensive,
// but in exchange the refund on every call to nonReentrant will be lower in
// amount. Since refunds are capped to a percentage of the total
// transaction's gas, it is best to keep them low in cases like this one, to
// increase the likelihood of the full refund coming into effect.
uint256 private constant _NOT_ENTERED = 1;
uint256 private constant _ENTERED = 2;
uint256 private _status;
constructor() {
_status = _NOT_ENTERED;
}
/**
* @dev Prevents a contract from calling itself, directly or indirectly.
* Calling a `nonReentrant` function from another `nonReentrant`
* function is not supported. It is possible to prevent this from happening
* by making the `nonReentrant` function external, and make it call a
* `private` function that does the actual work.
*/
modifier nonReentrant() {
// On the first call to nonReentrant, _notEntered will be true
require(_status != _ENTERED, "ReentrancyGuard: reentrant call");
// Any calls to nonReentrant after this point will fail
_status = _ENTERED;
_;
// By storing the original value once again, a refund is triggered (see
// https://eips.ethereum.org/EIPS/eip-2200)
_status = _NOT_ENTERED;
}
}
// Part: OpenZeppelin/[email protected]/EIP712
/**
* @dev https://eips.ethereum.org/EIPS/eip-712[EIP 712] is a standard for hashing and signing of typed structured data.
*
* The encoding specified in the EIP is very generic, and such a generic implementation in Solidity is not feasible,
* thus this contract does not implement the encoding itself. Protocols need to implement the type-specific encoding
* they need in their contracts using a combination of `abi.encode` and `keccak256`.
*
* This contract implements the EIP 712 domain separator ({_domainSeparatorV4}) that is used as part of the encoding
* scheme, and the final step of the encoding to obtain the message digest that is then signed via ECDSA
* ({_hashTypedDataV4}).
*
* The implementation of the domain separator was designed to be as efficient as possible while still properly updating
* the chain id to protect against replay attacks on an eventual fork of the chain.
*
* NOTE: This contract implements the version of the encoding known as "v4", as implemented by the JSON RPC method
* https://docs.metamask.io/guide/signing-data.html[`eth_signTypedDataV4` in MetaMask].
*
* _Available since v3.4._
*/
abstract contract EIP712 {
/* solhint-disable var-name-mixedcase */
// Cache the domain separator as an immutable value, but also store the chain id that it corresponds to, in order to
// invalidate the cached domain separator if the chain id changes.
bytes32 private immutable _CACHED_DOMAIN_SEPARATOR;
uint256 private immutable _CACHED_CHAIN_ID;
bytes32 private immutable _HASHED_NAME;
bytes32 private immutable _HASHED_VERSION;
bytes32 private immutable _TYPE_HASH;
/* solhint-enable var-name-mixedcase */
/**
* @dev Initializes the domain separator and parameter caches.
*
* The meaning of `name` and `version` is specified in
* https://eips.ethereum.org/EIPS/eip-712#definition-of-domainseparator[EIP 712]:
*
* - `name`: the user readable name of the signing domain, i.e. the name of the DApp or the protocol.
* - `version`: the current major version of the signing domain.
*
* NOTE: These parameters cannot be changed except through a xref:learn::upgrading-smart-contracts.adoc[smart
* contract upgrade].
*/
constructor(string memory name, string memory version) {
bytes32 hashedName = keccak256(bytes(name));
bytes32 hashedVersion = keccak256(bytes(version));
bytes32 typeHash = keccak256(
"EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"
);
_HASHED_NAME = hashedName;
_HASHED_VERSION = hashedVersion;
_CACHED_CHAIN_ID = block.chainid;
_CACHED_DOMAIN_SEPARATOR = _buildDomainSeparator(typeHash, hashedName, hashedVersion);
_TYPE_HASH = typeHash;
}
/**
* @dev Returns the domain separator for the current chain.
*/
function _domainSeparatorV4() internal view returns (bytes32) {
if (block.chainid == _CACHED_CHAIN_ID) {
return _CACHED_DOMAIN_SEPARATOR;
} else {
return _buildDomainSeparator(_TYPE_HASH, _HASHED_NAME, _HASHED_VERSION);
}
}
function _buildDomainSeparator(
bytes32 typeHash,
bytes32 nameHash,
bytes32 versionHash
) private view returns (bytes32) {
return keccak256(abi.encode(typeHash, nameHash, versionHash, block.chainid, address(this)));
}
/**
* @dev Given an already https://eips.ethereum.org/EIPS/eip-712#definition-of-hashstruct[hashed struct], this
* function returns the hash of the fully encoded EIP712 message for this domain.
*
* This hash can be used together with {ECDSA-recover} to obtain the signer of a message. For example:
*
* ```solidity
* bytes32 digest = _hashTypedDataV4(keccak256(abi.encode(
* keccak256("Mail(address to,string contents)"),
* mailTo,
* keccak256(bytes(mailContents))
* )));
* address signer = ECDSA.recover(digest, signature);
* ```
*/
function _hashTypedDataV4(bytes32 structHash) internal view virtual returns (bytes32) {
return ECDSA.toTypedDataHash(_domainSeparatorV4(), structHash);
}
}
// Part: OpenZeppelin/[email protected]/IERC20Metadata
/**
* @dev Interface for the optional metadata functions from the ERC20 standard.
*
* _Available since v4.1._
*/
interface IERC20Metadata is IERC20 {
/**
* @dev Returns the name of the token.
*/
function name() external view returns (string memory);
/**
* @dev Returns the symbol of the token.
*/
function symbol() external view returns (string memory);
/**
* @dev Returns the decimals places of the token.
*/
function decimals() external view returns (uint8);
}
// Part: OpenZeppelin/[email protected]/Pausable
/**
* @dev Contract module which allows children to implement an emergency stop
* mechanism that can be triggered by an authorized account.
*
* This module is used through inheritance. It will make available the
* modifiers `whenNotPaused` and `whenPaused`, which can be applied to
* the functions of your contract. Note that they will not be pausable by
* simply including this module, only once the modifiers are put in place.
*/
abstract contract Pausable is Context {
/**
* @dev Emitted when the pause is triggered by `account`.
*/
event Paused(address account);
/**
* @dev Emitted when the pause is lifted by `account`.
*/
event Unpaused(address account);
bool private _paused;
/**
* @dev Initializes the contract in unpaused state.
*/
constructor() {
_paused = false;
}
/**
* @dev Returns true if the contract is paused, and false otherwise.
*/
function paused() public view virtual returns (bool) {
return _paused;
}
/**
* @dev Modifier to make a function callable only when the contract is not paused.
*
* Requirements:
*
* - The contract must not be paused.
*/
modifier whenNotPaused() {
require(!paused(), "Pausable: paused");
_;
}
/**
* @dev Modifier to make a function callable only when the contract is paused.
*
* Requirements:
*
* - The contract must be paused.
*/
modifier whenPaused() {
require(paused(), "Pausable: not paused");
_;
}
/**
* @dev Triggers stopped state.
*
* Requirements:
*
* - The contract must not be paused.
*/
function _pause() internal virtual whenNotPaused {
_paused = true;
emit Paused(_msgSender());
}
/**
* @dev Returns to normal state.
*
* Requirements:
*
* - The contract must be paused.
*/
function _unpause() internal virtual whenPaused {
_paused = false;
emit Unpaused(_msgSender());
}
}
// Part: OpenZeppelin/[email protected]/SafeERC20
/**
* @title SafeERC20
* @dev Wrappers around ERC20 operations that throw on failure (when the token
* contract returns false). Tokens that return no value (and instead revert or
* throw on failure) are also supported, non-reverting calls are assumed to be
* successful.
* To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
* which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
*/
library SafeERC20 {
using Address for address;
function safeTransfer(
IERC20 token,
address to,
uint256 value
) internal {
_callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
}
function safeTransferFrom(
IERC20 token,
address from,
address to,
uint256 value
) internal {
_callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
}
/**
* @dev Deprecated. This function has issues similar to the ones found in
* {IERC20-approve}, and its usage is discouraged.
*
* Whenever possible, use {safeIncreaseAllowance} and
* {safeDecreaseAllowance} instead.
*/
function safeApprove(
IERC20 token,
address spender,
uint256 value
) internal {
// safeApprove should only be called when setting an initial allowance,
// or when resetting it to zero. To increase and decrease it, use
// 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
require(
(value == 0) || (token.allowance(address(this), spender) == 0),
"SafeERC20: approve from non-zero to non-zero allowance"
);
_callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
}
function safeIncreaseAllowance(
IERC20 token,
address spender,
uint256 value
) internal {
uint256 newAllowance = token.allowance(address(this), spender) + value;
_callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
}
function safeDecreaseAllowance(
IERC20 token,
address spender,
uint256 value
) internal {
unchecked {
uint256 oldAllowance = token.allowance(address(this), spender);
require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
uint256 newAllowance = oldAllowance - value;
_callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
}
}
/**
* @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
* on the return value: the return value is optional (but if data is returned, it must not be false).
* @param token The token targeted by the call.
* @param data The call data (encoded using abi.encode or one of its variants).
*/
function _callOptionalReturn(IERC20 token, bytes memory data) private {
// We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
// we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
// the target address contains contract code and also asserts for success in the low-level call.
bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
if (returndata.length > 0) {
// Return data is optional
require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
}
}
}
// Part: OpenZeppelin/[email protected]/ERC20
/**
* @dev Implementation of the {IERC20} interface.
*
* This implementation is agnostic to the way tokens are created. This means
* that a supply mechanism has to be added in a derived contract using {_mint}.
* For a generic mechanism see {ERC20PresetMinterPauser}.
*
* TIP: For a detailed writeup see our guide
* https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
* to implement supply mechanisms].
*
* We have followed general OpenZeppelin guidelines: functions revert instead
* of returning `false` on failure. This behavior is nonetheless conventional
* and does not conflict with the expectations of ERC20 applications.
*
* Additionally, an {Approval} event is emitted on calls to {transferFrom}.
* This allows applications to reconstruct the allowance for all accounts just
* by listening to said events. Other implementations of the EIP may not emit
* these events, as it isn't required by the specification.
*
* Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
* functions have been added to mitigate the well-known issues around setting
* allowances. See {IERC20-approve}.
*/
contract ERC20 is Context, IERC20, IERC20Metadata {
mapping(address => uint256) private _balances;
mapping(address => mapping(address => uint256)) private _allowances;
uint256 private _totalSupply;
string private _name;
string private _symbol;
/**
* @dev Sets the values for {name} and {symbol}.
*
* The default value of {decimals} is 18. To select a different value for
* {decimals} you should overload it.
*
* All two of these values are immutable: they can only be set once during
* construction.
*/
constructor(string memory name_, string memory symbol_) {
_name = name_;
_symbol = symbol_;
}
/**
* @dev Returns the name of the token.
*/
function name() public view virtual override returns (string memory) {
return _name;
}
/**
* @dev Returns the symbol of the token, usually a shorter version of the
* name.
*/
function symbol() public view virtual override returns (string memory) {
return _symbol;
}
/**
* @dev Returns the number of decimals used to get its user representation.
* For example, if `decimals` equals `2`, a balance of `505` tokens should
* be displayed to a user as `5,05` (`505 / 10 ** 2`).
*
* Tokens usually opt for a value of 18, imitating the relationship between
* Ether and Wei. This is the value {ERC20} uses, unless this function is
* overridden;
*
* NOTE: This information is only used for _display_ purposes: it in
* no way affects any of the arithmetic of the contract, including
* {IERC20-balanceOf} and {IERC20-transfer}.
*/
function decimals() public view virtual override returns (uint8) {
return 18;
}
/**
* @dev See {IERC20-totalSupply}.
*/
function totalSupply() public view virtual override returns (uint256) {
return _totalSupply;
}
/**
* @dev See {IERC20-balanceOf}.
*/
function balanceOf(address account) public view virtual override returns (uint256) {
return _balances[account];
}
/**
* @dev See {IERC20-transfer}.
*
* Requirements:
*
* - `recipient` cannot be the zero address.
* - the caller must have a balance of at least `amount`.
*/
function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
_transfer(_msgSender(), recipient, amount);
return true;
}
/**
* @dev See {IERC20-allowance}.
*/
function allowance(address owner, address spender) public view virtual override returns (uint256) {
return _allowances[owner][spender];
}
/**
* @dev See {IERC20-approve}.
*
* Requirements:
*
* - `spender` cannot be the zero address.
*/
function approve(address spender, uint256 amount) public virtual override returns (bool) {
_approve(_msgSender(), spender, amount);
return true;
}
/**
* @dev See {IERC20-transferFrom}.
*
* Emits an {Approval} event indicating the updated allowance. This is not
* required by the EIP. See the note at the beginning of {ERC20}.
*
* Requirements:
*
* - `sender` and `recipient` cannot be the zero address.
* - `sender` must have a balance of at least `amount`.
* - the caller must have allowance for ``sender``'s tokens of at least
* `amount`.
*/
function transferFrom(
address sender,
address recipient,
uint256 amount
) public virtual override returns (bool) {
_transfer(sender, recipient, amount);
uint256 currentAllowance = _allowances[sender][_msgSender()];
require(currentAllowance >= amount, "ERC20: transfer amount exceeds allowance");
unchecked {
_approve(sender, _msgSender(), currentAllowance - amount);
}
return true;
}
/**
* @dev Atomically increases the allowance granted to `spender` by the caller.
*
* This is an alternative to {approve} that can be used as a mitigation for
* problems described in {IERC20-approve}.
*
* Emits an {Approval} event indicating the updated allowance.
*
* Requirements:
*
* - `spender` cannot be the zero address.
*/
function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
_approve(_msgSender(), spender, _allowances[_msgSender()][spender] + addedValue);
return true;
}
/**
* @dev Atomically decreases the allowance granted to `spender` by the caller.
*
* This is an alternative to {approve} that can be used as a mitigation for
* problems described in {IERC20-approve}.
*
* Emits an {Approval} event indicating the updated allowance.
*
* Requirements:
*
* - `spender` cannot be the zero address.
* - `spender` must have allowance for the caller of at least
* `subtractedValue`.
*/
function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
uint256 currentAllowance = _allowances[_msgSender()][spender];
require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
unchecked {
_approve(_msgSender(), spender, currentAllowance - subtractedValue);
}
return true;
}
/**
* @dev Moves `amount` of tokens from `sender` to `recipient`.
*
* This internal function is equivalent to {transfer}, and can be used to
* e.g. implement automatic token fees, slashing mechanisms, etc.
*
* Emits a {Transfer} event.
*
* Requirements:
*
* - `sender` cannot be the zero address.
* - `recipient` cannot be the zero address.
* - `sender` must have a balance of at least `amount`.
*/
function _transfer(
address sender,
address recipient,
uint256 amount
) internal virtual {
require(sender != address(0), "ERC20: transfer from the zero address");
require(recipient != address(0), "ERC20: transfer to the zero address");
_beforeTokenTransfer(sender, recipient, amount);
uint256 senderBalance = _balances[sender];
require(senderBalance >= amount, "ERC20: transfer amount exceeds balance");
unchecked {
_balances[sender] = senderBalance - amount;
}
_balances[recipient] += amount;
emit Transfer(sender, recipient, amount);
_afterTokenTransfer(sender, recipient, amount);
}
/** @dev Creates `amount` tokens and assigns them to `account`, increasing
* the total supply.
*
* Emits a {Transfer} event with `from` set to the zero address.
*
* Requirements:
*
* - `account` cannot be the zero address.
*/
function _mint(address account, uint256 amount) internal virtual {
require(account != address(0), "ERC20: mint to the zero address");
_beforeTokenTransfer(address(0), account, amount);
_totalSupply += amount;
_balances[account] += amount;
emit Transfer(address(0), account, amount);
_afterTokenTransfer(address(0), account, amount);
}
/**
* @dev Destroys `amount` tokens from `account`, reducing the
* total supply.
*
* Emits a {Transfer} event with `to` set to the zero address.
*
* Requirements:
*
* - `account` cannot be the zero address.
* - `account` must have at least `amount` tokens.
*/
function _burn(address account, uint256 amount) internal virtual {
require(account != address(0), "ERC20: burn from the zero address");
_beforeTokenTransfer(account, address(0), amount);
uint256 accountBalance = _balances[account];
require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
unchecked {
_balances[account] = accountBalance - amount;
}
_totalSupply -= amount;
emit Transfer(account, address(0), amount);
_afterTokenTransfer(account, address(0), amount);
}
/**
* @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
*
* This internal function is equivalent to `approve`, and can be used to
* e.g. set automatic allowances for certain subsystems, etc.
*
* Emits an {Approval} event.
*
* Requirements:
*
* - `owner` cannot be the zero address.
* - `spender` cannot be the zero address.
*/
function _approve(
address owner,
address spender,
uint256 amount
) internal virtual {
require(owner != address(0), "ERC20: approve from the zero address");
require(spender != address(0), "ERC20: approve to the zero address");
_allowances[owner][spender] = amount;
emit Approval(owner, spender, amount);
}
/**
* @dev Hook that is called before any transfer of tokens. This includes
* minting and burning.
*
* Calling conditions:
*
* - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
* will be transferred to `to`.
* - when `from` is zero, `amount` tokens will be minted for `to`.
* - when `to` is zero, `amount` of ``from``'s tokens will be burned.
* - `from` and `to` are never both zero.
*
* To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
*/
function _beforeTokenTransfer(
address from,
address to,
uint256 amount
) internal virtual {}
/**
* @dev Hook that is called after any transfer of tokens. This includes
* minting and burning.
*
* Calling conditions:
*
* - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
* has been transferred to `to`.
* - when `from` is zero, `amount` tokens have been minted for `to`.
* - when `to` is zero, `amount` of ``from``'s tokens have been burned.
* - `from` and `to` are never both zero.
*
* To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
*/
function _afterTokenTransfer(
address from,
address to,
uint256 amount
) internal virtual {}
}
// Part: OpenZeppelin/[email protected]/ERC20Permit
/**
* @dev Implementation of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
* https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
*
* Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
* presenting a message signed by the account. By not relying on `{IERC20-approve}`, the token holder account doesn't
* need to send a transaction, and thus is not required to hold Ether at all.
*
* _Available since v3.4._
*/
abstract contract ERC20Permit is ERC20, IERC20Permit, EIP712 {
using Counters for Counters.Counter;
mapping(address => Counters.Counter) private _nonces;
// solhint-disable-next-line var-name-mixedcase
bytes32 private immutable _PERMIT_TYPEHASH =
keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");
/**
* @dev Initializes the {EIP712} domain separator using the `name` parameter, and setting `version` to `"1"`.
*
* It's a good idea to use the same `name` that is defined as the ERC20 token name.
*/
constructor(string memory name) EIP712(name, "1") {}
/**
* @dev See {IERC20Permit-permit}.
*/
function permit(
address owner,
address spender,
uint256 value,
uint256 deadline,
uint8 v,
bytes32 r,
bytes32 s
) public virtual override {
require(block.timestamp <= deadline, "ERC20Permit: expired deadline");
bytes32 structHash = keccak256(abi.encode(_PERMIT_TYPEHASH, owner, spender, value, _useNonce(owner), deadline));
bytes32 hash = _hashTypedDataV4(structHash);
address signer = ECDSA.recover(hash, v, r, s);
require(signer == owner, "ERC20Permit: invalid signature");
_approve(owner, spender, value);
}
/**
* @dev See {IERC20Permit-nonces}.
*/
function nonces(address owner) public view virtual override returns (uint256) {
return _nonces[owner].current();
}
/**
* @dev See {IERC20Permit-DOMAIN_SEPARATOR}.
*/
// solhint-disable-next-line func-name-mixedcase
function DOMAIN_SEPARATOR() external view override returns (bytes32) {
return _domainSeparatorV4();
}
/**
* @dev "Consume a nonce": return the current value and increment.
*
* _Available since v4.1._
*/
function _useNonce(address owner) internal virtual returns (uint256 current) {
Counters.Counter storage nonce = _nonces[owner];
current = nonce.current();
nonce.increment();
}
}
// File: BToken.sol
contract BToken is ERC20Permit, ReentrancyGuard {
using SafeERC20 for IERC20;
event Accrue(uint interest);
event Mint(address indexed caller, address indexed to, uint amount, uint credit);
event Burn(address indexed caller, address indexed to, uint amount, uint credit);
uint public constant MINIMUM_LIQUIDITY = 10**6; // minimum liquidity to be locked in the pool when first mint occurs
address public immutable betaBank; // BetaBank address
address public immutable underlying; // the underlying token
uint public interestRate; // current interest rate
uint public lastAccrueTime; // last interest accrual timestamp
uint public totalLoanable; // total asset amount available to be borrowed
uint public totalLoan; // total amount of loan
uint public totalDebtShare; // total amount of debt share
/// @dev Initializes the BToken contract.
/// @param _betaBank BetaBank address.
/// @param _underlying The underlying token address for the bToken.
constructor(address _betaBank, address _underlying)
ERC20Permit('B Token')
ERC20('B Token', 'bTOKEN')
{
require(_betaBank != address(0), 'constructor/betabank-zero-address');
require(_underlying != address(0), 'constructor/underlying-zero-address');
betaBank = _betaBank;
underlying = _underlying;
interestRate = IBetaInterestModel(IBetaBank(_betaBank).interestModel()).initialRate();
lastAccrueTime = block.timestamp;
}
/// @dev Returns the name of the token.
function name() public view override returns (string memory) {
try IERC20Metadata(underlying).name() returns (string memory data) {
return string(abi.encodePacked('B ', data));
} catch (bytes memory) {
return ERC20.name();
}
}
/// @dev Returns the symbol of the token.
function symbol() public view override returns (string memory) {
try IERC20Metadata(underlying).symbol() returns (string memory data) {
return string(abi.encodePacked('b', data));
} catch (bytes memory) {
return ERC20.symbol();
}
}
/// @dev Returns the decimal places of the token.
function decimals() public view override returns (uint8) {
try IERC20Metadata(underlying).decimals() returns (uint8 data) {
return data;
} catch (bytes memory) {
return ERC20.decimals();
}
}
/// @dev Accrues interest rate and adjusts the rate. Can be called by anyone at any time.
function accrue() public {
// 1. Check time past condition
uint timePassed = block.timestamp - lastAccrueTime;
if (timePassed == 0) return;
lastAccrueTime = block.timestamp;
// 2. Check bank pause condition
require(!Pausable(betaBank).paused(), 'BetaBank/paused');
// 3. Compute the accrued interest value over the past time
(uint totalLoan_, uint totalLoanable_, uint interestRate_) = (
totalLoan,
totalLoanable,
interestRate
); // gas saving by avoiding multiple SLOADs
IBetaConfig config = IBetaConfig(IBetaBank(betaBank).config());
IBetaInterestModel model = IBetaInterestModel(IBetaBank(betaBank).interestModel());
uint interest = (interestRate_ * totalLoan_ * timePassed) / (365 days) / 1e18;
// 4. Update total loan and next interest rate
totalLoan_ += interest;
totalLoan = totalLoan_;
interestRate = model.getNextInterestRate(interestRate_, totalLoanable_, totalLoan_, timePassed);
// 5. Send a portion of collected interest to the beneficiary
if (interest > 0) {
uint reserveRate = config.reserveRate();
if (reserveRate > 0) {
uint toReserve = (interest * reserveRate) / 1e18;
_mint(
config.reserveBeneficiary(),
(toReserve * totalSupply()) / (totalLoan_ + totalLoanable_ - toReserve)
);
}
emit Accrue(interest);
}
}
/// @dev Returns the debt value for the given debt share. Automatically calls accrue.
function fetchDebtShareValue(uint _debtShare) external returns (uint) {
accrue();
if (_debtShare == 0) {
return 0;
}
return Math.ceilDiv(_debtShare * totalLoan, totalDebtShare); // round up
}
/// @dev Mints new bToken to the given address.
/// @param _to The address to mint new bToken for.
/// @param _amount The amount of underlying tokens to deposit via `transferFrom`.
/// @return credit The amount of bToken minted.
function mint(address _to, uint _amount) external nonReentrant returns (uint credit) {
accrue();
uint amount;
{
uint balBefore = IERC20(underlying).balanceOf(address(this));
IERC20(underlying).safeTransferFrom(msg.sender, address(this), _amount);
uint balAfter = IERC20(underlying).balanceOf(address(this));
amount = balAfter - balBefore;
}
uint supply = totalSupply();
if (supply == 0) {
credit = amount - MINIMUM_LIQUIDITY;
// Permanently lock the first MINIMUM_LIQUIDITY tokens
totalLoanable += credit;
totalLoan += MINIMUM_LIQUIDITY;
totalDebtShare += MINIMUM_LIQUIDITY;
_mint(address(1), MINIMUM_LIQUIDITY); // OpenZeppelin ERC20 does not allow minting to 0
} else {
credit = (amount * supply) / (totalLoanable + totalLoan);
totalLoanable += amount;
}
require(credit > 0, 'mint/no-credit-minted');
_mint(_to, credit);
emit Mint(msg.sender, _to, _amount, credit);
}
/// @dev Burns the given bToken for the proportional amount of underlying tokens.
/// @param _to The address to send the underlying tokens to.
/// @param _credit The amount of bToken to burn.
/// @return amount The amount of underlying tokens getting transferred out.
function burn(address _to, uint _credit) external nonReentrant returns (uint amount) {
accrue();
uint supply = totalSupply();
amount = (_credit * (totalLoanable + totalLoan)) / supply;
require(amount > 0, 'burn/no-amount-returned');
totalLoanable -= amount;
_burn(msg.sender, _credit);
IERC20(underlying).safeTransfer(_to, amount);
emit Burn(msg.sender, _to, amount, _credit);
}
/// @dev Borrows the funds for the given address. Must only be called by BetaBank.
/// @param _to The address to borrow the funds for.
/// @param _amount The amount to borrow.
/// @return debtShare The amount of new debt share minted.
function borrow(address _to, uint _amount) external nonReentrant returns (uint debtShare) {
require(msg.sender == betaBank, 'borrow/not-BetaBank');
accrue();
IERC20(underlying).safeTransfer(_to, _amount);
debtShare = Math.ceilDiv(_amount * totalDebtShare, totalLoan); // round up
totalLoanable -= _amount;
totalLoan += _amount;
totalDebtShare += debtShare;
}
/// @dev Repays the debt using funds from the given address. Must only be called by BetaBank.
/// @param _from The address to drain the funds to repay.
/// @param _amount The amount of funds to call via `transferFrom`.
/// @return debtShare The amount of debt share repaid.
function repay(address _from, uint _amount) external nonReentrant returns (uint debtShare) {
require(msg.sender == betaBank, 'repay/not-BetaBank');
accrue();
uint amount;
{
uint balBefore = IERC20(underlying).balanceOf(address(this));
IERC20(underlying).safeTransferFrom(_from, address(this), _amount);
uint balAfter = IERC20(underlying).balanceOf(address(this));
amount = balAfter - balBefore;
}
require(amount <= totalLoan, 'repay/amount-too-high');
debtShare = (amount * totalDebtShare) / totalLoan; // round down
totalLoanable += amount;
totalLoan -= amount;
totalDebtShare -= debtShare;
require(totalDebtShare >= MINIMUM_LIQUIDITY, 'repay/too-low-sum-debt-share');
}
/// @dev Recovers tokens in this contract. EMERGENCY ONLY. Full trust in BetaBank.
/// @param _token The token to recover, can even be underlying so please be careful.
/// @param _to The address to recover tokens to.
/// @param _amount The amount of tokens to recover, or MAX_UINT256 if whole balance.
function recover(
address _token,
address _to,
uint _amount
) external nonReentrant {
require(msg.sender == betaBank, 'recover/not-BetaBank');
if (_amount == type(uint).max) {
_amount = IERC20(_token).balanceOf(address(this));
}
IERC20(_token).safeTransfer(_to, _amount);
}
}