NoBey/openzeppelin-contracts
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Remove hooks from ERC20 (#3838)

Browse Source 
Co-authored-by: Francisco <frangio.1@gmail.com>
This commit is contained in:
JulissaDantes
2022-12-14 14:43:45 -05:00
committed by GitHub
parent e2d2ebc8fc
commit 3c80a42866
10 changed files with 121 additions and 150 deletions
Download Patch File Download Diff File Expand all files Collapse all files

24
CHANGELOG.md
View File

@ -8,6 +8,30 @@
* Removed presets in favor of [OpenZeppelin Contracts Wizard](https://wizard.openzeppelin.com/).
* `TransparentUpgradeableProxy`: Removed `admin` and `implementation` getters, which were only callable by the proxy owner and thus not very useful. ([#3820](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3820))
* `ProxyAdmin`: Removed `getProxyAdmin` and `getProxyImplementation` getters. ([#3820](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3820))
* `ERC20`: Deleted `_beforeTokenTransfer` and `_afterTokenTransfer` hooks, added a new internal `_update` function for customizations, and refactored all extensions using those hooks to use `_update` instead. ([#3838](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3838))
### How to upgrade from 4.x
#### ERC20, ERC721, and ERC1155
These breaking changes will require modifications to ERC20, ERC721, and ERC1155 contracts, since the `_afterTokenTransfer` and `_beforeTokenTransfer` functions were removed. Any customization made through those hooks should now be done overriding the new `_update` function instead.
Minting and burning are implemented by `_update` and customizations should be done by overriding this function as well. `_mint` and `_burn` are no longer virtual (meaning they are not overridable) to guard against possible inconsistencies.
For example, a contract using `ERC20`'s `_beforeTokenTransfer` hook would have to be changed in the following way.
```diff
- function _beforeTokenTransfer(
+ function _update(
address from,
address to,
uint256 amount
) internal virtual override {
- super._beforeTokenTransfer(from, to, amount);
require(!condition(), "ERC20: wrong condition");
+ super._update(from, to, amount);
}
```
## Unreleased

166
contracts/token/ERC20/ERC20.sol
View File

@ -216,87 +216,81 @@ contract ERC20 is Context, IERC20, IERC20Metadata {
*
* Emits a {Transfer} event.
*
* Requirements:
*
* - `from` cannot be the zero address.
* - `to` cannot be the zero address.
* - `from` must have a balance of at least `amount`.
* NOTE: This function is not virtual, {_update} should be overridden instead.
*/
function _transfer(
address from,
address to,
uint256 amount
) internal virtual {
) internal {
require(from != address(0), "ERC20: transfer from the zero address");
require(to != address(0), "ERC20: transfer to the zero address");
_beforeTokenTransfer(from, to, amount);
uint256 fromBalance = _balances[from];
require(fromBalance >= amount, "ERC20: transfer amount exceeds balance");
unchecked {
_balances[from] = fromBalance - amount;
// Overflow not possible: the sum of all balances is capped by totalSupply, and the sum is preserved by
// decrementing then incrementing.
_balances[to] += amount;
}
emit Transfer(from, to, amount);
_afterTokenTransfer(from, to, amount);
}
/** @dev Creates `amount` tokens and assigns them to `account`, increasing
* the total supply.
*
* Emits a {Transfer} event with `from` set to the zero address.
*
* Requirements:
*
* - `account` cannot be the zero address.
*/
function _mint(address account, uint256 amount) internal virtual {
require(account != address(0), "ERC20: mint to the zero address");
_beforeTokenTransfer(address(0), account, amount);
_totalSupply += amount;
unchecked {
// Overflow not possible: balance + amount is at most totalSupply + amount, which is checked above.
_balances[account] += amount;
}
emit Transfer(address(0), account, amount);
_afterTokenTransfer(address(0), account, amount);
_update(from, to, amount);
}
/**
* @dev Destroys `amount` tokens from `account`, reducing the
* total supply.
* @dev Transfers `amount` of tokens from `from` to `to`, or alternatively mints (or burns) if `from` (or `to`) is
* the zero address. All customizations to transfers, mints, and burns should be done by overriding this function.
*
* Emits a {Transfer} event.
*/
function _update(
address from,
address to,
uint256 amount
) internal virtual {
if (from == address(0)) {
_totalSupply += amount;
unchecked {
// Overflow not possible: balance + amount is at most totalSupply + amount, which is checked above.
_balances[to] += amount;
}
} else if (to == address(0)) {
uint256 fromBalance = _balances[from];
require(fromBalance >= amount, "ERC20: burn amount exceeds balance");
_totalSupply -= amount;
unchecked {
// Overflow not possible: amount <= fromBalance <= totalSupply.
_balances[from] = fromBalance - amount;
}
} else {
uint256 fromBalance = _balances[from];
require(fromBalance >= amount, "ERC20: transfer amount exceeds balance");
unchecked {
_balances[from] = fromBalance - amount;
// Overflow not possible: the sum of all balances is capped by totalSupply, and the sum is preserved by
// decrementing then incrementing.
_balances[to] += amount;
}
}
emit Transfer(from, to, amount);
}
/**
* @dev Creates `amount` tokens and assigns them to `account`, by transferring it from address(0).
* Relies on the `_update` mechanism
*
* Emits a {Transfer} event with `from` set to the zero address.
*
* NOTE: This function is not virtual, {_update} should be overridden instead.
*/
function _mint(address account, uint256 amount) internal {
require(account != address(0), "ERC20: mint to the zero address");
_update(address(0), account, amount);
}
/**
* @dev Destroys `amount` tokens from `account`, by transferring it to address(0).
* Relies on the `_update` mechanism.
*
* Emits a {Transfer} event with `to` set to the zero address.
*
* Requirements:
*
* - `account` cannot be the zero address.
* - `account` must have at least `amount` tokens.
* NOTE: This function is not virtual, {_update} should be overridden instead
*/
function _burn(address account, uint256 amount) internal virtual {
function _burn(address account, uint256 amount) internal {
require(account != address(0), "ERC20: burn from the zero address");
_beforeTokenTransfer(account, address(0), amount);
uint256 accountBalance = _balances[account];
require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
unchecked {
_balances[account] = accountBalance - amount;
// Overflow not possible: amount <= accountBalance <= totalSupply.
_totalSupply -= amount;
}
emit Transfer(account, address(0), amount);
_afterTokenTransfer(account, address(0), amount);
_update(account, address(0), amount);
}
/**
@ -345,44 +339,4 @@ contract ERC20 is Context, IERC20, IERC20Metadata {
}
}
}
/**
* @dev Hook that is called before any transfer of tokens. This includes
* minting and burning.
*
* Calling conditions:
*
* - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
* will be transferred to `to`.
* - when `from` is zero, `amount` tokens will be minted for `to`.
* - when `to` is zero, `amount` of ``from``'s tokens will be burned.
* - `from` and `to` are never both zero.
*
* To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
*/
function _beforeTokenTransfer(
address from,
address to,
uint256 amount
) internal virtual {}
/**
* @dev Hook that is called after any transfer of tokens. This includes
* minting and burning.
*
* Calling conditions:
*
* - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
* has been transferred to `to`.
* - when `from` is zero, `amount` tokens have been minted for `to`.
* - when `to` is zero, `amount` of ``from``'s tokens have been burned.
* - `from` and `to` are never both zero.
*
* To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
*/
function _afterTokenTransfer(
address from,
address to,
uint256 amount
) internal virtual {}
}

15
contracts/token/ERC20/extensions/ERC20Capped.sol
View File

@ -28,10 +28,17 @@ abstract contract ERC20Capped is ERC20 {
}
/**
* @dev See {ERC20-_mint}.
* @dev See {ERC20-_transfer}.
*/
function _mint(address account, uint256 amount) internal virtual override {
require(ERC20.totalSupply() + amount <= cap(), "ERC20Capped: cap exceeded");
super._mint(account, amount);
function _update(
address from,
address to,
uint256 amount
) internal virtual override {
if (from == address(0)) {
require(ERC20.totalSupply() + amount <= cap(), "ERC20Capped: cap exceeded");
}
super._update(from, to, amount);
}
}

7
contracts/token/ERC20/extensions/ERC20Pausable.sol
View File

@ -15,19 +15,18 @@ import "../../../security/Pausable.sol";
*/
abstract contract ERC20Pausable is ERC20, Pausable {
/**
* @dev See {ERC20-_beforeTokenTransfer}.
* @dev See {ERC20-_update}.
*
* Requirements:
*
* - the contract must not be paused.
*/
function _beforeTokenTransfer(
function _update(
address from,
address to,
uint256 amount
) internal virtual override {
super._beforeTokenTransfer(from, to, amount);
require(!paused(), "ERC20Pausable: token transfer while paused");
super._update(from, to, amount);
}
}

9
contracts/token/ERC20/extensions/ERC20Snapshot.sol
View File

@ -118,15 +118,13 @@ abstract contract ERC20Snapshot is ERC20 {
return snapshotted ? value : totalSupply();
}
// Update balance and/or total supply snapshots before the values are modified. This is implemented
// in the _beforeTokenTransfer hook, which is executed for _mint, _burn, and _transfer operations.
function _beforeTokenTransfer(
// Update balance and/or total supply snapshots before the values are modified. This is executed
// for _mint, _burn, and _transfer operations.
function _update(
address from,
address to,
uint256 amount
) internal virtual override {
super._beforeTokenTransfer(from, to, amount);
if (from == address(0)) {
// mint
_updateAccountSnapshot(to);
@ -140,6 +138,7 @@ abstract contract ERC20Snapshot is ERC20 {
_updateAccountSnapshot(from);
_updateAccountSnapshot(to);
}
super._update(from, to, amount);
}
function _valueAt(uint256 snapshotId, Snapshots storage snapshots) private view returns (bool, uint256) {

15
contracts/token/ERC20/extensions/ERC20Votes.sol
View File

@ -35,13 +35,16 @@ abstract contract ERC20Votes is ERC20, Votes {
*
* Emits a {IVotes-DelegateVotesChanged} event.
*/
function _afterTokenTransfer(
function _update(
address from,
address to,
uint256 amount
) internal virtual override {
super._update(from, to, amount);
if (from == address(0)) {
require(totalSupply() <= _maxSupply(), "ERC20Votes: total supply risks overflowing votes");
}
_transferVotingUnits(from, to, amount);
super._afterTokenTransfer(from, to, amount);
}
/**
@ -64,12 +67,4 @@ abstract contract ERC20Votes is ERC20, Votes {
function _getVotingUnits(address account) internal view virtual override returns (uint256) {
return balanceOf(account);
}
/**
* @dev Snapshots the totalSupply after it has been increased.
*/
function _mint(address account, uint256 amount) internal virtual override {
super._mint(account, amount);
require(totalSupply() <= _maxSupply(), "ERC20Votes: total supply risks overflowing votes");
}
}

13
test/token/ERC20/ERC20.behavior.js
View File

@ -158,8 +158,9 @@ function shouldBehaveLikeERC20 (errorPrefix, initialSupply, initialHolder, recip
});
it('reverts', async function () {
await expectRevert(this.token.transferFrom(
tokenOwner, to, amount, { from: spender }), `${errorPrefix}: transfer to the zero address`,
await expectRevert(
this.token.transferFrom(tokenOwner, to, amount, { from: spender }),
`${errorPrefix}: transfer to the zero address`,
);
});
});
@ -240,14 +241,6 @@ function shouldBehaveLikeERC20Transfer (errorPrefix, from, to, balance, transfer
});
});
});
describe('when the recipient is the zero address', function () {
it('reverts', async function () {
await expectRevert(transfer.call(this, from, ZERO_ADDRESS, balance),
`${errorPrefix}: transfer to the zero address`,
);
});
});
}
function shouldBehaveLikeERC20Approve (errorPrefix, owner, spender, supply, approve) {

16
test/token/ERC20/ERC20.test.js
View File

@ -207,6 +207,14 @@ contract('ERC20', function (accounts) {
);
});
it('rejects overflow', async function () {
const maxUint256 = new BN('2').pow(new BN(256)).subn(1);
await expectRevert(
this.token.mint(recipient, maxUint256),
'reverted with panic code 0x11 (Arithmetic operation underflowed or overflowed outside of an unchecked block)',
);
});
describe('for a non zero account', function () {
beforeEach('minting', async function () {
this.receipt = await this.token.mint(recipient, amount);
@ -283,14 +291,6 @@ contract('ERC20', function (accounts) {
shouldBehaveLikeERC20Transfer('ERC20', initialHolder, recipient, initialSupply, function (from, to, amount) {
return this.token.transferInternal(from, to, amount);
});
describe('when the sender is the zero address', function () {
it('reverts', async function () {
await expectRevert(this.token.transferInternal(ZERO_ADDRESS, recipient, initialSupply),
'ERC20: transfer from the zero address',
);
});
});
});
describe('_approve', function () {

4
test/token/ERC20/extensions/ERC20FlashMint.test.js
View File

@ -1,8 +1,8 @@
/* eslint-disable */
const { BN, constants, expectEvent, expectRevert, time } = require('@openzeppelin/test-helpers');
const { BN, constants, expectEvent, expectRevert } = require('@openzeppelin/test-helpers');
const { expect } = require('chai');
const { MAX_UINT256, ZERO_ADDRESS, ZERO_BYTES32 } = constants;
const { MAX_UINT256, ZERO_ADDRESS } = constants;
const ERC20FlashMintMock = artifacts.require('ERC20FlashMintMock');
const ERC3156FlashBorrowerMock = artifacts.require('ERC3156FlashBorrowerMock');

2
test/token/ERC20/extensions/ERC20Votes.test.js
View File

@ -53,7 +53,7 @@ contract('ERC20Votes', function (accounts) {
const amount = new BN('2').pow(new BN('224'));
await expectRevert(
this.token.mint(holder, amount),
"SafeCast: value doesn't fit in 224 bits",
"ERC20Votes: total supply risks overflowing votes",
);
});