// File contracts/math/SafeMath.sol
/**
* @dev Wrappers over Solidity's arithmetic operations with added overflow
* checks.
*
* Arithmetic operations in Solidity wrap on overflow. This can easily result
* in bugs, because programmers usually assume that an overflow raises an
* error, which is the standard behavior in high level programming languages.
* `SafeMath` restores this intuition by reverting the transaction when an
* operation overflows.
*
* Using this library instead of the unchecked operations eliminates an entire
* class of bugs, so it's recommended to use it always.
*/
library SafeMath {
/**
* @dev Returns the addition of two unsigned integers, reverting on
* overflow.
*
* Counterpart to Solidity's `+` operator.
*
* Requirements:
* - Addition cannot overflow.
*/
function add(uint256 a, uint256 b) internal pure returns (uint256) {
uint256 c = a + b;
require(c >= a, "SafeMath: addition overflow");
return c;
}
/**
* @dev Returns the subtraction of two unsigned integers, reverting on
* overflow (when the result is negative).
*
* Counterpart to Solidity's `-` operator.
*
* Requirements:
* - Subtraction cannot overflow.
*/
function sub(uint256 a, uint256 b) internal pure returns (uint256) {
return sub(a, b, "SafeMath: subtraction overflow");
}
/**
* @dev Returns the subtraction of two unsigned integers, reverting with custom message on
* overflow (when the result is negative).
*
* Counterpart to Solidity's `-` operator.
*
* Requirements:
* - Subtraction cannot overflow.
*
* _Available since v2.4.0._
*/
function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
require(b <= a, errorMessage);
uint256 c = a - b;
return c;
}
/**
* @dev Returns the multiplication of two unsigned integers, reverting on
* overflow.
*
* Counterpart to Solidity's `*` operator.
*
* Requirements:
* - Multiplication cannot overflow.
*/
function mul(uint256 a, uint256 b) internal pure returns (uint256) {
// Gas optimization: this is cheaper than requiring 'a' not being zero, but the
// benefit is lost if 'b' is also tested.
// See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
if (a == 0) {
return 0;
}
uint256 c = a * b;
require(c / a == b, "SafeMath: multiplication overflow");
return c;
}
/**
* @dev Returns the integer division of two unsigned integers. Reverts on
* division by zero. The result is rounded towards zero.
*
* Counterpart to Solidity's `/` operator. Note: this function uses a
* `revert` opcode (which leaves remaining gas untouched) while Solidity
* uses an invalid opcode to revert (consuming all remaining gas).
*
* Requirements:
* - The divisor cannot be zero.
*/
function div(uint256 a, uint256 b) internal pure returns (uint256) {
return div(a, b, "SafeMath: division by zero");
}
/**
* @dev Returns the integer division of two unsigned integers. Reverts with custom message on
* division by zero. The result is rounded towards zero.
*
* Counterpart to Solidity's `/` operator. Note: this function uses a
* `revert` opcode (which leaves remaining gas untouched) while Solidity
* uses an invalid opcode to revert (consuming all remaining gas).
*
* Requirements:
* - The divisor cannot be zero.
*
* _Available since v2.4.0._
*/
function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
// Solidity only automatically asserts when dividing by 0
require(b > 0, errorMessage);
uint256 c = a / b;
// assert(a == b * c + a % b); // There is no case in which this doesn't hold
return c;
}
/**
* @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
* Reverts when dividing by zero.
*
* Counterpart to Solidity's `%` operator. This function uses a `revert`
* opcode (which leaves remaining gas untouched) while Solidity uses an
* invalid opcode to revert (consuming all remaining gas).
*
* Requirements:
* - The divisor cannot be zero.
*/
function mod(uint256 a, uint256 b) internal pure returns (uint256) {
return mod(a, b, "SafeMath: modulo by zero");
}
/**
* @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
* Reverts with custom message when dividing by zero.
*
* Counterpart to Solidity's `%` operator. This function uses a `revert`
* opcode (which leaves remaining gas untouched) while Solidity uses an
* invalid opcode to revert (consuming all remaining gas).
*
* Requirements:
* - The divisor cannot be zero.
*
* _Available since v2.4.0._
*/
function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
require(b != 0, errorMessage);
return a % b;
}
}
// File contracts/introspection/KIP13.sol
/**
* @dev Implementation of the `IKIP13` interface.
*
* Contracts may inherit from this and call `_registerInterface` to declare
* their support of an interface.
*/
contract KIP13 is IKIP13 {
/*
* bytes4(keccak256('supportsInterface(bytes4)')) == 0x01ffc9a7
*/
bytes4 private constant _INTERFACE_ID_KIP13 = 0x01ffc9a7;
/**
* @dev Mapping of interface ids to whether or not it's supported.
*/
mapping(bytes4 => bool) private _supportedInterfaces;
constructor () internal {
// Derived contracts need only register support for their own interfaces,
// we register support for KIP13 itself here
_registerInterface(_INTERFACE_ID_KIP13);
}
/**
* @dev See `IKIP13.supportsInterface`.
*
* Time complexity O(1), guaranteed to always use less than 30 000 gas.
*/
function supportsInterface(bytes4 interfaceId) external view returns (bool) {
return _supportedInterfaces[interfaceId];
}
/**
* @dev Registers the contract as an implementer of the interface defined by
* `interfaceId`. Support of the actual KIP13 interface is automatic and
* registering its interface id is not required.
*
* See `IKIP13.supportsInterface`.
*
* Requirements:
*
* - `interfaceId` cannot be the KIP13 invalid interface (`0xffffffff`).
*/
function _registerInterface(bytes4 interfaceId) internal {
require(interfaceId != 0xffffffff, "KIP13: invalid interface id");
_supportedInterfaces[interfaceId] = true;
}
}
// File contracts/utils/Address.sol
/**
* @dev Collection of functions related to the address type,
*/
library Address {
/**
* @dev Returns true if `account` is a contract.
*
* This test is non-exhaustive, and there may be false-negatives: during the
* execution of a contract's constructor, its address will be reported as
* not containing a contract.
*
* > It is unsafe to assume that an address for which this function returns
* false is an externally-owned account (EOA) and not a contract.
*/
function isContract(address account) internal view returns (bool) {
// This method relies in extcodesize, which returns 0 for contracts in
// construction, since the code is only stored at the end of the
// constructor execution.
uint256 size;
// solhint-disable-next-line no-inline-assembly
assembly { size := extcodesize(account) }
return size > 0;
}
}
// File contracts/token/KIP7/IKIP7Receiver.sol
/**
* @title KIP-7 Fungible Token Standard, optional wallet interface
* @dev Note: the KIP-13 identifier for this interface is 0x9d188c22.
* see http://kips.klaytn.com/KIPs/kip-7-fungible_token
*/
contract IKIP7Receiver {
/**
* @notice Handle the receipt of KIP-7 token
* @dev The KIP-7 smart contract calls this function on the recipient
* after a `safeTransfer`. This function MAY throw to revert and reject the
* transfer. Return of other than the magic value MUST result in the
* transaction being reverted.
* Note: the contract address is always the message sender.
* @param _operator The address which called `safeTransferFrom` function
* @param _from The address which previously owned the token
* @param _amount The token amount which is being transferred.
* @param _data Additional data with no specified format
* @return `bytes4(keccak256("onKIP7Received(address,address,uint256,bytes)"))`
* unless throwing
*/
function onKIP7Received(address _operator, address _from, uint256 _amount, bytes memory _data) public returns (bytes4);
}
// File contracts/token/KIP7/KIP7.sol
/**
* @dev Implementation of the `IKIP7` 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 `KIP7Mintable`.
*
* 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 KIP7 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 KIP may not emit
* these events, as it isn't required by the specification.
*
* See http://kips.klaytn.com/KIPs/kip-7-fungible_token
*/
contract KIP7 is KIP13, IKIP7 {
using SafeMath for uint256;
using Address for address;
// Equals to `bytes4(keccak256("onKIP7Received(address,address,uint256,bytes)"))`
// which can be also obtained as `IKIP7Receiver(0).onKIP7Received.selector`
bytes4 private constant _KIP7_RECEIVED = 0x9d188c22;
mapping (address => uint256) private _balances;
mapping (address => mapping (address => uint256)) private _allowances;
uint256 private _totalSupply;
/*
* bytes4(keccak256('totalSupply()')) == 0x18160ddd
* bytes4(keccak256('balanceOf(address)')) == 0x70a08231
* bytes4(keccak256('transfer(address,uint256)')) == 0xa9059cbb
* bytes4(keccak256('allowance(address,address)')) == 0xdd62ed3e
* bytes4(keccak256('approve(address,uint256)')) == 0x095ea7b3
* bytes4(keccak256('transferFrom(address,address,uint256)')) == 0x23b872dd
* bytes4(keccak256("safeTransfer(address,uint256)")) == 0x423f6cef
* bytes4(keccak256("safeTransfer(address,uint256,bytes)")) == 0xeb795549
* bytes4(keccak256("safeTransferFrom(address,address,uint256)")) == 0x42842e0e
* bytes4(keccak256("safeTransferFrom(address,address,uint256,bytes)")) == 0xb88d4fde
*
* => 0x18160ddd ^ 0x70a08231 ^ 0xa9059cbb ^ 0xdd62ed3e ^ 0x095ea7b3 ^ 0x23b872dd ^ 0x423f6cef ^ 0xeb795549 ^ 0x42842e0e ^ 0xb88d4fde == 0x65787371
*/
bytes4 private constant _INTERFACE_ID_KIP7 = 0x65787371;
constructor () public {
// register the supported interfaces to conform to KIP7 via KIP13
_registerInterface(_INTERFACE_ID_KIP7);
}
/**
* @dev See `IKIP7.totalSupply`.
*/
function totalSupply() public view returns (uint256) {
return _totalSupply;
}
/**
* @dev See `IKIP7.balanceOf`.
*/
function balanceOf(address account) public view returns (uint256) {
return _balances[account];
}
/**
* @dev See `IKIP7.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 returns (bool) {
_transfer(msg.sender, recipient, amount);
return true;
}
/**
* @dev See `IKIP7.allowance`.
*/
function allowance(address owner, address spender) public view returns (uint256) {
return _allowances[owner][spender];
}
/**
* @dev See `IKIP7.approve`.
*
* Requirements:
*
* - `spender` cannot be the zero address.
*/
function approve(address spender, uint256 value) public returns (bool) {
_approve(msg.sender, spender, value);
return true;
}
/**
* @dev See `IKIP7.transferFrom`.
*
* Emits an `Approval` event indicating the updated allowance. This is not
* required by the KIP. See the note at the beginning of `KIP7`;
*
* Requirements:
* - `sender` and `recipient` cannot be the zero address.
* - `sender` must have a balance of at least `value`.
* - the caller must have allowance for `sender`'s tokens of at least
* `amount`.
*/
function transferFrom(address sender, address recipient, uint256 amount) public returns (bool) {
_transfer(sender, recipient, amount);
_approve(sender, msg.sender, _allowances[sender][msg.sender].sub(amount));
return true;
}
/**
* @dev Moves `amount` tokens from the caller's account to `recipient`.
*/
function safeTransfer(address recipient, uint256 amount) public {
safeTransfer(recipient, amount, "");
}
/**
* @dev Moves `amount` tokens from the caller's account to `recipient`.
*/
function safeTransfer(address recipient, uint256 amount, bytes memory data) public {
transfer(recipient, amount);
require(_checkOnKIP7Received(msg.sender, recipient, amount, data), "KIP7: transfer to non KIP7Receiver implementer");
}
/**
* @dev Moves `amount` tokens from `sender` to `recipient` using the allowance mechanism.
* `amount` is then deducted from the caller's allowance.
*/
function safeTransferFrom(address sender, address recipient, uint256 amount) public {
safeTransferFrom(sender, recipient, amount, "");
}
/**
* @dev Moves `amount` tokens from `sender` to `recipient` using the allowance mechanism.
* `amount` is then deducted from the caller's allowance.
*/
function safeTransferFrom(address sender, address recipient, uint256 amount, bytes memory data) public {
transferFrom(sender, recipient, amount);
require(_checkOnKIP7Received(sender, recipient, amount, data), "KIP7: transfer to non KIP7Receiver implementer");
}
/**
* @dev Moves tokens `amount` from `sender` to `recipient`.
*
* This is 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 {
require(sender != address(0), "KIP7: transfer from the zero address");
require(recipient != address(0), "KIP7: transfer to the zero address");
_balances[sender] = _balances[sender].sub(amount);
_balances[recipient] = _balances[recipient].add(amount);
emit Transfer(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
*
* - `to` cannot be the zero address.
*/
function _mint(address account, uint256 amount) internal {
require(account != address(0), "KIP7: mint to the zero address");
_totalSupply = _totalSupply.add(amount);
_balances[account] = _balances[account].add(amount);
emit Transfer(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 value) internal {
require(account != address(0), "KIP7: burn from the zero address");
_totalSupply = _totalSupply.sub(value);
_balances[account] = _balances[account].sub(value);
emit Transfer(account, address(0), value);
}