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67 lines
3.0 KiB
67 lines
3.0 KiB
pragma solidity ^0.5.5;
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/**
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* @dev Collection of functions related to the address type
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*/
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library Address {
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/**
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* @dev Returns true if `account` is a contract.
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*
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* This test is non-exhaustive, and there may be false-negatives: during the
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* execution of a contract's constructor, its address will be reported as
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* not containing a contract.
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*
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* IMPORTANT: It is unsafe to assume that an address for which this
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* function returns false is an externally-owned account (EOA) and not a
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* contract.
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*/
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function isContract(address account) internal view returns (bool) {
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// This method relies in extcodesize, which returns 0 for contracts in
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// construction, since the code is only stored at the end of the
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// constructor execution.
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// According to EIP-1052, 0x0 is the value returned for not-yet created accounts
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// and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
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// for accounts without code, i.e. `keccak256('')`
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bytes32 codehash;
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bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
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// solhint-disable-next-line no-inline-assembly
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assembly { codehash := extcodehash(account) }
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return (codehash != 0x0 && codehash != accountHash);
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}
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/**
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* @dev Converts an `address` into `address payable`. Note that this is
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* simply a type cast: the actual underlying value is not changed.
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*
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* NOTE: This is a feature of the next version of OpenZeppelin Contracts.
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* @dev Get it via `npm install @openzeppelin/contracts@next`.
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*/
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function toPayable(address account) internal pure returns (address payable) {
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return address(uint160(account));
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}
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/**
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* @dev Replacement for Solidity's `transfer`: sends `amount` wei to
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* `recipient`, forwarding all available gas and reverting on errors.
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*
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* https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
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* of certain opcodes, possibly making contracts go over the 2300 gas limit
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* imposed by `transfer`, making them unable to receive funds via
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* `transfer`. {sendValue} removes this limitation.
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*
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* https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
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*
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* IMPORTANT: because control is transferred to `recipient`, care must be
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* taken to not create reentrancy vulnerabilities. Consider using
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* {ReentrancyGuard} or the
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* https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
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*/
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function sendValue(address payable recipient, uint256 amount) internal {
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require(address(this).balance >= amount, "Address: insufficient balance");
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// solhint-disable-next-line avoid-call-value
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(bool success, ) = recipient.call.value(amount)("");
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require(success, "Address: unable to send value, recipient may have reverted");
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}
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}
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