laconicd-deprecated/tests/solidity/suites/staking/contracts/lib/os/SafeERC20.sol
Federico Kunze 96cad7de9c
tests: reorganize packages (#7)
* tests: reorganize testing packages

* gitignore and minor changes
2021-05-11 07:54:55 -04:00

92 lines
3.2 KiB
Solidity

// Brought from https://github.com/aragon/aragonOS/blob/v4.3.0/contracts/common/SafeERC20.sol
// Adapted to use pragma ^0.5.8 and satisfy our linter rules
pragma solidity ^0.5.8;
import "./ERC20.sol";
library SafeERC20 {
// Before 0.5, solidity has a mismatch between `address.transfer()` and `token.transfer()`:
// https://github.com/ethereum/solidity/issues/3544
bytes4 private constant TRANSFER_SELECTOR = 0xa9059cbb;
/**
* @dev Same as a standards-compliant ERC20.transfer() that never reverts (returns false).
* Note that this makes an external call to the token.
*/
function safeTransfer(ERC20 _token, address _to, uint256 _amount) internal returns (bool) {
bytes memory transferCallData = abi.encodeWithSelector(
TRANSFER_SELECTOR,
_to,
_amount
);
return invokeAndCheckSuccess(address(_token), transferCallData);
}
/**
* @dev Same as a standards-compliant ERC20.transferFrom() that never reverts (returns false).
* Note that this makes an external call to the token.
*/
function safeTransferFrom(ERC20 _token, address _from, address _to, uint256 _amount) internal returns (bool) {
bytes memory transferFromCallData = abi.encodeWithSelector(
_token.transferFrom.selector,
_from,
_to,
_amount
);
return invokeAndCheckSuccess(address(_token), transferFromCallData);
}
/**
* @dev Same as a standards-compliant ERC20.approve() that never reverts (returns false).
* Note that this makes an external call to the token.
*/
function safeApprove(ERC20 _token, address _spender, uint256 _amount) internal returns (bool) {
bytes memory approveCallData = abi.encodeWithSelector(
_token.approve.selector,
_spender,
_amount
);
return invokeAndCheckSuccess(address(_token), approveCallData);
}
function invokeAndCheckSuccess(address _addr, bytes memory _calldata) private returns (bool) {
bool ret;
assembly {
let ptr := mload(0x40) // free memory pointer
let success := call(
gas, // forward all gas
_addr, // address
0, // no value
add(_calldata, 0x20), // calldata start
mload(_calldata), // calldata length
ptr, // write output over free memory
0x20 // uint256 return
)
if gt(success, 0) {
// Check number of bytes returned from last function call
switch returndatasize
// No bytes returned: assume success
case 0 {
ret := 1
}
// 32 bytes returned: check if non-zero
case 0x20 {
// Only return success if returned data was true
// Already have output in ptr
ret := eq(mload(ptr), 1)
}
// Not sure what was returned: don't mark as success
default { }
}
}
return ret;
}
}