Contract Name:
TokenVesting
Contract Source Code:
File 1 of 1 : TokenVesting
pragma solidity ^0.4.24;
/**
* @title SafeMath
* @dev Math operations with safety checks that throw on error
*/
library SafeMath {
/**
* @dev Multiplies two numbers, throws on overflow.
*/
function mul(uint256 _a, uint256 _b) internal pure returns (uint256 c) {
// Gas optimization: this is cheaper than asserting 'a' not being zero, but the
// benefit is lost if 'b' is also tested.
// See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
if (_a == 0) {
return 0;
}
c = _a * _b;
assert(c / _a == _b);
return c;
}
/**
* @dev Integer division of two numbers, truncating the quotient.
*/
function div(uint256 _a, uint256 _b) internal pure returns (uint256) {
// assert(_b > 0); // Solidity automatically throws when dividing by 0
// uint256 c = _a / _b;
// assert(_a == _b * c + _a % _b); // There is no case in which this doesn't hold
return _a / _b;
}
/**
* @dev Subtracts two numbers, throws on overflow (i.e. if subtrahend is greater than minuend).
*/
function sub(uint256 _a, uint256 _b) internal pure returns (uint256) {
assert(_b <= _a);
return _a - _b;
}
/**
* @dev Adds two numbers, throws on overflow.
*/
function add(uint256 _a, uint256 _b) internal pure returns (uint256 c) {
c = _a + _b;
assert(c >= _a);
return c;
}
}
// File: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v1.12.0/contracts/token/ERC20/ERC20Basic.sol
pragma solidity ^0.4.24;
/**
* @title ERC20Basic
* @dev Simpler version of ERC20 interface
* See https://github.com/ethereum/EIPs/issues/179
*/
contract ERC20Basic {
function totalSupply() public view returns (uint256);
function balanceOf(address _who) public view returns (uint256);
function transfer(address _to, uint256 _value) public returns (bool);
event Transfer(address indexed from, address indexed to, uint256 value);
}
// File: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v1.12.0/contracts/token/ERC20/ERC20.sol
pragma solidity ^0.4.24;
/**
* @title ERC20 interface
* @dev see https://github.com/ethereum/EIPs/issues/20
*/
contract ERC20 is ERC20Basic {
function allowance(address _owner, address _spender)
public view returns (uint256);
function transferFrom(address _from, address _to, uint256 _value)
public returns (bool);
function approve(address _spender, uint256 _value) public returns (bool);
event Approval(
address indexed owner,
address indexed spender,
uint256 value
);
}
// File: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v1.12.0/contracts/token/ERC20/SafeERC20.sol
pragma solidity ^0.4.24;
/**
* @title SafeERC20
* @dev Wrappers around ERC20 operations that throw on failure.
* To use this library you can add a `using SafeERC20 for ERC20;` statement to your contract,
* which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
*/
library SafeERC20 {
function safeTransfer(
ERC20Basic _token,
address _to,
uint256 _value
)
internal
{
require(_token.transfer(_to, _value));
}
function safeTransferFrom(
ERC20 _token,
address _from,
address _to,
uint256 _value
)
internal
{
require(_token.transferFrom(_from, _to, _value));
}
function safeApprove(
ERC20 _token,
address _spender,
uint256 _value
)
internal
{
require(_token.approve(_spender, _value));
}
}
// File: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v1.12.0/contracts/ownership/Ownable.sol
pragma solidity ^0.4.24;
/**
* @title Ownable
* @dev The Ownable contract has an owner address, and provides basic authorization control
* functions, this simplifies the implementation of "user permissions".
*/
contract Ownable {
address public owner;
event OwnershipRenounced(address indexed previousOwner);
event OwnershipTransferred(
address indexed previousOwner,
address indexed newOwner
);
/**
* @dev The Ownable constructor sets the original `owner` of the contract to the sender
* account.
*/
constructor() public {
owner = msg.sender;
}
/**
* @dev Throws if called by any account other than the owner.
*/
modifier onlyOwner() {
require(msg.sender == owner);
_;
}
/**
* @dev Allows the current owner to relinquish control of the contract.
* @notice Renouncing to ownership will leave the contract without an owner.
* It will not be possible to call the functions with the `onlyOwner`
* modifier anymore.
*/
function renounceOwnership() public onlyOwner {
emit OwnershipRenounced(owner);
owner = address(0);
}
/**
* @dev Allows the current owner to transfer control of the contract to a newOwner.
* @param _newOwner The address to transfer ownership to.
*/
function transferOwnership(address _newOwner) public onlyOwner {
_transferOwnership(_newOwner);
}
/**
* @dev Transfers control of the contract to a newOwner.
* @param _newOwner The address to transfer ownership to.
*/
function _transferOwnership(address _newOwner) internal {
require(_newOwner != address(0));
emit OwnershipTransferred(owner, _newOwner);
owner = _newOwner;
}
}
// File: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v1.12.0/contracts/token/ERC20/TokenVesting.sol
/* solium-disable security/no-block-members */
pragma solidity ^0.4.24;
/**
* @title TokenVesting
* @dev A token holder contract that can release its token balance gradually like a
* typical vesting scheme, with a cliff and vesting period. Optionally revocable by the
* owner.
*/
contract TokenVesting is Ownable {
using SafeMath for uint256;
using SafeERC20 for ERC20Basic;
event Released(uint256 amount);
event Revoked();
// beneficiary of tokens after they are released
address public beneficiary;
uint256 public cliff;
uint256 public start;
uint256 public duration;
bool public revocable;
mapping (address => uint256) public released;
mapping (address => bool) public revoked;
/**
* @dev Creates a vesting contract that vests its balance of any ERC20 token to the
* _beneficiary, gradually in a linear fashion until _start + _duration. By then all
* of the balance will have vested.
* @param _beneficiary address of the beneficiary to whom vested tokens are transferred
* @param _cliff duration in seconds of the cliff in which tokens will begin to vest
* @param _start the time (as Unix time) at which point vesting starts
* @param _duration duration in seconds of the period in which the tokens will vest
* @param _revocable whether the vesting is revocable or not
*/
constructor(
address _beneficiary,
uint256 _start,
uint256 _cliff,
uint256 _duration,
bool _revocable
)
public
{
require(_beneficiary != address(0));
require(_cliff <= _duration);
beneficiary = _beneficiary;
revocable = _revocable;
duration = _duration;
cliff = _start.add(_cliff);
start = _start;
}
/**
* @notice Transfers vested tokens to beneficiary.
* @param _token ERC20 token which is being vested
*/
function release(ERC20Basic _token) public {
uint256 unreleased = releasableAmount(_token);
require(unreleased > 0);
released[_token] = released[_token].add(unreleased);
_token.safeTransfer(beneficiary, unreleased);
emit Released(unreleased);
}
/**
* @notice Allows the owner to revoke the vesting. Tokens already vested
* remain in the contract, the rest are returned to the owner.
* @param _token ERC20 token which is being vested
*/
function revoke(ERC20Basic _token) public onlyOwner {
require(revocable);
require(!revoked[_token]);
uint256 balance = _token.balanceOf(address(this));
uint256 unreleased = releasableAmount(_token);
uint256 refund = balance.sub(unreleased);
revoked[_token] = true;
_token.safeTransfer(owner, refund);
emit Revoked();
}
/**
* @dev Calculates the amount that has already vested but hasn't been released yet.
* @param _token ERC20 token which is being vested
*/
function releasableAmount(ERC20Basic _token) public view returns (uint256) {
return vestedAmount(_token).sub(released[_token]);
}
/**
* @dev Calculates the amount that has already vested.
* @param _token ERC20 token which is being vested
*/
function vestedAmount(ERC20Basic _token) public view returns (uint256) {
uint256 currentBalance = _token.balanceOf(address(this));
uint256 totalBalance = currentBalance.add(released[_token]);
if (block.timestamp < cliff) {
return 0;
} else if (block.timestamp >= start.add(duration) || revoked[_token]) {
return totalBalance;
} else {
return totalBalance.mul(block.timestamp.sub(start)).div(duration);
}
}
}