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BoringERC20.sol
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BoringERC20.sol
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// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "../interfaces/IERC20.sol";
// solhint-disable avoid-low-level-calls
library BoringERC20 {
bytes4 private constant SIG_SYMBOL = 0x95d89b41; // symbol()
bytes4 private constant SIG_NAME = 0x06fdde03; // name()
bytes4 private constant SIG_DECIMALS = 0x313ce567; // decimals()
bytes4 private constant SIG_BALANCE_OF = 0x70a08231; // balanceOf(address)
bytes4 private constant SIG_TRANSFER = 0xa9059cbb; // transfer(address,uint256)
bytes4 private constant SIG_TRANSFER_FROM = 0x23b872dd; // transferFrom(address,address,uint256)
function returnDataToString(bytes memory data) internal pure returns (string memory) {
if (data.length >= 64) {
return abi.decode(data, (string));
} else if (data.length == 32) {
uint8 i = 0;
while (i < 32 && data[i] != 0) {
i++;
}
bytes memory bytesArray = new bytes(i);
for (i = 0; i < 32 && data[i] != 0; i++) {
bytesArray[i] = data[i];
}
return string(bytesArray);
} else {
return "???";
}
}
/// @notice Provides a safe ERC20.symbol version which returns '???' as fallback string.
/// @param token The address of the ERC-20 token contract.
/// @return (string) Token symbol.
function safeSymbol(IERC20 token) internal view returns (string memory) {
(bool success, bytes memory data) = address(token).staticcall(abi.encodeWithSelector(SIG_SYMBOL));
return success ? returnDataToString(data) : "???";
}
/// @notice Provides a safe ERC20.name version which returns '???' as fallback string.
/// @param token The address of the ERC-20 token contract.
/// @return (string) Token name.
function safeName(IERC20 token) internal view returns (string memory) {
(bool success, bytes memory data) = address(token).staticcall(abi.encodeWithSelector(SIG_NAME));
return success ? returnDataToString(data) : "???";
}
/// @notice Provides a safe ERC20.decimals version which returns '18' as fallback value.
/// @param token The address of the ERC-20 token contract.
/// @return (uint8) Token decimals.
function safeDecimals(IERC20 token) internal view returns (uint8) {
(bool success, bytes memory data) = address(token).staticcall(abi.encodeWithSelector(SIG_DECIMALS));
return success && data.length == 32 ? abi.decode(data, (uint8)) : 18;
}
/// @notice Provides a gas-optimized balance check to avoid a redundant extcodesize check in addition to the returndatasize check.
/// @param token The address of the ERC-20 token.
/// @param to The address of the user to check.
/// @return amount The token amount.
function safeBalanceOf(IERC20 token, address to) internal view returns (uint256 amount) {
(bool success, bytes memory data) = address(token).staticcall(abi.encodeWithSelector(SIG_BALANCE_OF, to));
require(success && data.length >= 32, "BoringERC20: BalanceOf failed");
amount = abi.decode(data, (uint256));
}
/// @notice Provides a safe ERC20.transfer version for different ERC-20 implementations.
/// Reverts on a failed transfer.
/// @param token The address of the ERC-20 token.
/// @param to Transfer tokens to.
/// @param amount The token amount.
function safeTransfer(
IERC20 token,
address to,
uint256 amount
) internal {
(bool success, bytes memory data) = address(token).call(abi.encodeWithSelector(SIG_TRANSFER, to, amount));
require(success && (data.length == 0 || abi.decode(data, (bool))), "BoringERC20: Transfer failed");
}
/// @notice Provides a safe ERC20.transferFrom version for different ERC-20 implementations.
/// Reverts on a failed transfer.
/// @param token The address of the ERC-20 token.
/// @param from Transfer tokens from.
/// @param to Transfer tokens to.
/// @param amount The token amount.
function safeTransferFrom(
IERC20 token,
address from,
address to,
uint256 amount
) internal {
(bool success, bytes memory data) = address(token).call(abi.encodeWithSelector(SIG_TRANSFER_FROM, from, to, amount));
require(success && (data.length == 0 || abi.decode(data, (bool))), "BoringERC20: TransferFrom failed");
}
}