// SPDX-License-Identifier: MIT // OpenZeppelin Contracts (last updated v5.1.0) (token/ERC20/utils/SafeERC20.sol) pragma solidity ^0.8.20; import {IERC20} from "../IERC20.sol"; import {IERC1363} from "../../../interfaces/IERC1363.sol"; /** * @title SafeERC20 * @dev Wrappers around ERC-20 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 { /** * @dev An operation with an ERC-20 token failed. */ error SafeERC20FailedOperation(address token); /** * @dev Indicates a failed `decreaseAllowance` request. */ error SafeERC20FailedDecreaseAllowance(address spender, uint256 currentAllowance, uint256 requestedDecrease); /** * @dev Transfer `value` amount of `token` from the calling contract to `to`. If `token` returns no value, * non-reverting calls are assumed to be successful. */ function safeTransfer(IERC20 token, address to, uint256 value) internal { _callOptionalReturn(token, abi.encodeCall(token.transfer, (to, value))); } /** * @dev Transfer `value` amount of `token` from `from` to `to`, spending the approval given by `from` to the * calling contract. If `token` returns no value, non-reverting calls are assumed to be successful. */ function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal { _callOptionalReturn(token, abi.encodeCall(token.transferFrom, (from, to, value))); } /** * @dev Increase the calling contract's allowance toward `spender` by `value`. If `token` returns no value, * non-reverting calls are assumed to be successful. * * IMPORTANT: If the token implements ERC-7674 (ERC-20 with temporary allowance), and if the "client" * smart contract uses ERC-7674 to set temporary allowances, then the "client" smart contract should avoid using * this function. Performing a {safeIncreaseAllowance} or {safeDecreaseAllowance} operation on a token contract * that has a non-zero temporary allowance (for that particular owner-spender) will result in unexpected behavior. */ function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal { uint256 oldAllowance = token.allowance(address(this), spender); forceApprove(token, spender, oldAllowance + value); } /** * @dev Decrease the calling contract's allowance toward `spender` by `requestedDecrease`. If `token` returns no * value, non-reverting calls are assumed to be successful. * * IMPORTANT: If the token implements ERC-7674 (ERC-20 with temporary allowance), and if the "client" * smart contract uses ERC-7674 to set temporary allowances, then the "client" smart contract should avoid using * this function. Performing a {safeIncreaseAllowance} or {safeDecreaseAllowance} operation on a token contract * that has a non-zero temporary allowance (for that particular owner-spender) will result in unexpected behavior. */ function safeDecreaseAllowance(IERC20 token, address spender, uint256 requestedDecrease) internal { unchecked { uint256 currentAllowance = token.allowance(address(this), spender); if (currentAllowance < requestedDecrease) { revert SafeERC20FailedDecreaseAllowance(spender, currentAllowance, requestedDecrease); } forceApprove(token, spender, currentAllowance - requestedDecrease); } } /** * @dev Set the calling contract's allowance toward `spender` to `value`. If `token` returns no value, * non-reverting calls are assumed to be successful. Meant to be used with tokens that require the approval * to be set to zero before setting it to a non-zero value, such as USDT. * * NOTE: If the token implements ERC-7674, this function will not modify any temporary allowance. This function * only sets the "standard" allowance. Any temporary allowance will remain active, in addition to the value being * set here. */ function forceApprove(IERC20 token, address spender, uint256 value) internal { bytes memory approvalCall = abi.encodeCall(token.approve, (spender, value)); if (!_callOptionalReturnBool(token, approvalCall)) { _callOptionalReturn(token, abi.encodeCall(token.approve, (spender, 0))); _callOptionalReturn(token, approvalCall); } } /** * @dev Performs an {ERC1363} transferAndCall, with a fallback to the simple {ERC20} transfer if the target has no * code. This can be used to implement an {ERC721}-like safe transfer that rely on {ERC1363} checks when * targeting contracts. * * Reverts if the returned value is other than `true`. */ function transferAndCallRelaxed(IERC1363 token, address to, uint256 value, bytes memory data) internal { if (to.code.length == 0) { safeTransfer(token, to, value); } else if (!token.transferAndCall(to, value, data)) { revert SafeERC20FailedOperation(address(token)); } } /** * @dev Performs an {ERC1363} transferFromAndCall, with a fallback to the simple {ERC20} transferFrom if the target * has no code. This can be used to implement an {ERC721}-like safe transfer that rely on {ERC1363} checks when * targeting contracts. * * Reverts if the returned value is other than `true`. */ function transferFromAndCallRelaxed( IERC1363 token, address from, address to, uint256 value, bytes memory data ) internal { if (to.code.length == 0) { safeTransferFrom(token, from, to, value); } else if (!token.transferFromAndCall(from, to, value, data)) { revert SafeERC20FailedOperation(address(token)); } } /** * @dev Performs an {ERC1363} approveAndCall, with a fallback to the simple {ERC20} approve if the target has no * code. This can be used to implement an {ERC721}-like safe transfer that rely on {ERC1363} checks when * targeting contracts. * * NOTE: When the recipient address (`to`) has no code (i.e. is an EOA), this function behaves as {forceApprove}. * Opposedly, when the recipient address (`to`) has code, this function only attempts to call {ERC1363-approveAndCall} * once without retrying, and relies on the returned value to be true. * * Reverts if the returned value is other than `true`. */ function approveAndCallRelaxed(IERC1363 token, address to, uint256 value, bytes memory data) internal { if (to.code.length == 0) { forceApprove(token, to, value); } else if (!token.approveAndCall(to, value, data)) { revert SafeERC20FailedOperation(address(token)); } } /** * @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). * * This is a variant of {_callOptionalReturnBool} that reverts if call fails to meet the requirements. */ function _callOptionalReturn(IERC20 token, bytes memory data) private { uint256 returnSize; uint256 returnValue; assembly ("memory-safe") { let success := call(gas(), token, 0, add(data, 0x20), mload(data), 0, 0x20) // bubble errors if iszero(success) { let ptr := mload(0x40) returndatacopy(ptr, 0, returndatasize()) revert(ptr, returndatasize()) } returnSize := returndatasize() returnValue := mload(0) } if (returnSize == 0 ? address(token).code.length == 0 : returnValue != 1) { revert SafeERC20FailedOperation(address(token)); } } /** * @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). * * This is a variant of {_callOptionalReturn} that silently catches all reverts and returns a bool instead. */ function _callOptionalReturnBool(IERC20 token, bytes memory data) private returns (bool) { bool success; uint256 returnSize; uint256 returnValue; assembly ("memory-safe") { success := call(gas(), token, 0, add(data, 0x20), mload(data), 0, 0x20) returnSize := returndatasize() returnValue := mload(0) } return success && (returnSize == 0 ? address(token).code.length > 0 : returnValue == 1); } }