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@nventuro
nventuro authored May 7, 2019
2 parents 376820d + 0840bee commit 77bc023
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2 changes: 1 addition & 1 deletion CHANGELOG.md
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Expand Up @@ -4,7 +4,7 @@

### New features:
* `ERC1820`: added support for interacting with the [ERC1820](https://eips.ethereum.org/EIPS/eip-1820) registry contract (`IERC1820Registry`), as well as base contracts that can be registered as implementers there. ([#1677](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1677))
* `ERC777`: initial support for the [ERC777 token](https://eips.ethereum.org/EIPS/eip-777), which has multiple improvements over `ERC20` such as built-in burning, a more straightforward permission system, and optional sender and receiver hooks on transfer (mandatory for contracts!). ([#1684](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1684))
* `ERC777`: support for the [ERC777 token](https://eips.ethereum.org/EIPS/eip-777), which has multiple improvements over `ERC20` (but is backwards compatible with it) such as built-in burning, a more straightforward permission system, and optional sender and receiver hooks on transfer (mandatory for contracts!). ([#1684](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1684))
* All contracts now have revert reason strings, which give insight into error conditions, and help debug failing transactions. ([#1704](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1704))

### Improvements:
Expand Down
172 changes: 140 additions & 32 deletions contracts/drafts/ERC777/ERC777.sol
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Expand Up @@ -3,6 +3,7 @@ pragma solidity ^0.5.0;
import "./IERC777.sol";
import "./IERC777Recipient.sol";
import "./IERC777Sender.sol";
import "../../token/ERC20/IERC20.sol";
import "../../math/SafeMath.sol";
import "../../utils/Address.sol";
import "../IERC1820Registry.sol";
Expand All @@ -11,20 +12,19 @@ import "../IERC1820Registry.sol";
* @title ERC777 token implementation, with granularity harcoded to 1.
* @author etsvigun <utgarda@gmail.com>, Bertrand Masius <github@catageeks.tk>
*/
contract ERC777 is IERC777 {
contract ERC777 is IERC777, IERC20 {
using SafeMath for uint256;
using Address for address;

IERC1820Registry private _erc1820 = IERC1820Registry(0x1820a4B7618BdE71Dce8cdc73aAB6C95905faD24);

string private _name;

string private _symbol;

mapping(address => uint256) private _balances;

uint256 private _totalSupply;

string private _name;
string private _symbol;

bytes32 constant private TOKENS_SENDER_INTERFACE_HASH = keccak256("ERC777TokensSender");
bytes32 constant private TOKENS_RECIPIENT_INTERFACE_HASH = keccak256("ERC777TokensRecipient");

Expand All @@ -38,6 +38,9 @@ contract ERC777 is IERC777 {
mapping(address => mapping(address => bool)) private _operators;
mapping(address => mapping(address => bool)) private _revokedDefaultOperators;

// ERC20-allowances
mapping (address => mapping (address => uint256)) private _allowances;

constructor(
string memory name,
string memory symbol,
Expand All @@ -51,8 +54,9 @@ contract ERC777 is IERC777 {
_defaultOperators[_defaultOperatorsArray[i]] = true;
}

// register interface
// register interfaces
_erc1820.setInterfaceImplementer(address(this), keccak256("ERC777Token"), address(this));
_erc1820.setInterfaceImplementer(address(this), keccak256("ERC20Token"), address(this));
}

/**
Expand All @@ -62,7 +66,7 @@ contract ERC777 is IERC777 {
* @param data bytes information attached to the send, and intended for the recipient (to)
*/
function send(address to, uint256 amount, bytes calldata data) external {
_send(msg.sender, msg.sender, to, amount, data, "");
_sendRequireReceptionAck(msg.sender, msg.sender, to, amount, data, "");
}

/**
Expand All @@ -82,8 +86,36 @@ contract ERC777 is IERC777 {
)
external
{
require(isOperatorFor(msg.sender, from));
_send(msg.sender, from, to, amount, data, operatorData);
require(isOperatorFor(msg.sender, from), "ERC777: caller is not an operator for holder");
_send(msg.sender, from, to, amount, data, operatorData, true);
}

/**
* @dev Transfer token to a specified address.
* Required for ERC20 compatiblity. Note that transferring tokens this way may result in locked tokens (i.e. tokens
* can be sent to a contract that does not implement the ERC777TokensRecipient interface).
* @param to The address to transfer to.
* @param value The amount to be transferred.
*/
function transfer(address to, uint256 value) external returns (bool) {
_transfer(msg.sender, msg.sender, to, value);
return true;
}

/**
* @dev Transfer tokens from one address to another.
* Note that while this function emits an Approval event, this is not required as per the specification,
* and other compliant implementations may not emit the event.
* Required for ERC20 compatiblity. Note that transferring tokens this way may result in locked tokens (i.e. tokens
* can be sent to a contract that does not implement the ERC777TokensRecipient interface).
* @param from address The address which you want to send tokens from
* @param to address The address which you want to transfer to
* @param value uint256 the amount of tokens to be transferred
*/
function transferFrom(address from, address to, uint256 value) external returns (bool) {
_transfer(msg.sender, from, to, value);
_approve(from, msg.sender, _allowances[from][msg.sender].sub(value));
return true;
}

/**
Expand All @@ -103,7 +135,7 @@ contract ERC777 is IERC777 {
* @param operatorData bytes extra information provided by the operator (if any)
*/
function operatorBurn(address from, uint256 amount, bytes calldata data, bytes calldata operatorData) external {
require(isOperatorFor(msg.sender, from));
require(isOperatorFor(msg.sender, from), "ERC777: caller is not an operator for holder");
_burn(msg.sender, from, amount, data, operatorData);
}

Expand All @@ -112,7 +144,7 @@ contract ERC777 is IERC777 {
* @param operator address to be authorized as operator
*/
function authorizeOperator(address operator) external {
require(msg.sender != operator);
require(msg.sender != operator, "ERC777: authorizing self as operator");

if (_defaultOperators[operator]) {
delete _revokedDefaultOperators[msg.sender][operator];
Expand All @@ -128,7 +160,7 @@ contract ERC777 is IERC777 {
* @param operator address to revoke operator rights from
*/
function revokeOperator(address operator) external {
require(operator != msg.sender);
require(operator != msg.sender, "ERC777: revoking self as operator");

if (_defaultOperators[operator]) {
_revokedDefaultOperators[msg.sender][operator] = true;
Expand All @@ -140,17 +172,18 @@ contract ERC777 is IERC777 {
}

/**
* @return the name of the token.
*/
function name() public view returns (string memory) {
return _name;
}

/**
* @return the symbol of the token.
* @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender.
* Beware that changing an allowance with this method brings the risk that someone may use both the old
* and the new allowance by unfortunate transaction ordering. One possible solution to mitigate this
* race condition is to first reduce the spender's allowance to 0 and set the desired value afterwards:
* https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
* Required for ERC20 compatilibity.
* @param spender The address which will spend the funds.
* @param value The amount of tokens to be spent.
*/
function symbol() public view returns (string memory) {
return _symbol;
function approve(address spender, uint256 value) external returns (bool) {
_approve(msg.sender, spender, value);
return true;
}

/**
Expand All @@ -169,6 +202,27 @@ contract ERC777 is IERC777 {
return _balances[tokenHolder];
}

/**
* @return the name of the token.
*/
function name() public view returns (string memory) {
return _name;
}

/**
* @return the symbol of the token.
*/
function symbol() public view returns (string memory) {
return _symbol;
}

/**
* @return the number of decimals of the token.
*/
function decimals() public pure returns (uint8) {
return 18; // The spec requires that decimals be 18
}

/**
* @dev Gets the token's granularity,
* i.e. the smallest number of tokens (in the basic unit)
Expand Down Expand Up @@ -203,6 +257,17 @@ contract ERC777 is IERC777 {
_operators[tokenHolder][operator];
}

/**
* @dev Function to check the amount of tokens that an owner allowed to a spender.
* Required for ERC20 compatibility.
* @param owner address The address which owns the funds.
* @param spender address The address which will spend the funds.
* @return A uint256 specifying the amount of tokens still available for the spender.
*/
function allowance(address owner, address spender) public view returns (uint256) {
return _allowances[owner][spender];
}

/**
* @dev Mint tokens. Does not check authorization of operator
* @dev the caller may ckeck that operator is authorized before calling
Expand All @@ -221,15 +286,42 @@ contract ERC777 is IERC777 {
)
internal
{
require(to != address(0));
require(to != address(0), "ERC777: mint to the zero address");

// Update state variables
_totalSupply = _totalSupply.add(amount);
_balances[to] = _balances[to].add(amount);

_callTokensReceived(operator, address(0), to, amount, userData, operatorData);
_callTokensReceived(operator, address(0), to, amount, userData, operatorData, true);

emit Minted(operator, to, amount, userData, operatorData);
emit Transfer(address(0), to, amount);
}

function _transfer(address operator, address from, address to, uint256 amount) private {
_sendWithoutMandatoryReceptionAck(operator, from, to, amount, "", "");
}

function _sendRequireReceptionAck(
address operator,
address from,
address to,
uint256 amount,
bytes memory userData,
bytes memory operatorData
) private {
_send(operator, from, to, amount, userData, operatorData, true);
}

function _sendWithoutMandatoryReceptionAck(
address operator,
address from,
address to,
uint256 amount,
bytes memory userData,
bytes memory operatorData
) private {
_send(operator, from, to, amount, userData, operatorData, false);
}

/**
Expand All @@ -240,29 +332,32 @@ contract ERC777 is IERC777 {
* @param amount uint256 amount of tokens to transfer
* @param userData bytes extra information provided by the token holder (if any)
* @param operatorData bytes extra information provided by the operator (if any)
* @param requireReceptionAck if true, contract recipients are required to implement ERC777TokensRecipient
*/
function _send(
address operator,
address from,
address to,
uint256 amount,
bytes memory userData,
bytes memory operatorData
bytes memory operatorData,
bool requireReceptionAck
)
private
{
require(from != address(0));
require(to != address(0));
require(from != address(0), "ERC777: transfer from the zero address");
require(to != address(0), "ERC777: transfer to the zero address");

_callTokensToSend(operator, from, to, amount, userData, operatorData);

// Update state variables
_balances[from] = _balances[from].sub(amount);
_balances[to] = _balances[to].add(amount);

_callTokensReceived(operator, from, to, amount, userData, operatorData);
_callTokensReceived(operator, from, to, amount, userData, operatorData, requireReceptionAck);

emit Sent(operator, from, to, amount, userData, operatorData);
emit Transfer(from, to, amount);
}

/**
Expand All @@ -282,7 +377,7 @@ contract ERC777 is IERC777 {
)
private
{
require(from != address(0));
require(from != address(0), "ERC777: burn from the zero address");

_callTokensToSend(operator, from, address(0), amount, data, operatorData);

Expand All @@ -291,6 +386,17 @@ contract ERC777 is IERC777 {
_balances[from] = _balances[from].sub(amount);

emit Burned(operator, from, amount, data, operatorData);
emit Transfer(from, address(0), amount);
}

function _approve(address owner, address spender, uint256 value) private {
// TODO: restore this require statement if this function becomes internal, or is called at a new callsite. It is
// currently unnecessary.
//require(owner != address(0), "ERC777: approve from the zero address");
require(spender != address(0), "ERC777: approve to the zero address");

_allowances[owner][spender] = value;
emit Approval(owner, spender, value);
}

/**
Expand Down Expand Up @@ -327,22 +433,24 @@ contract ERC777 is IERC777 {
* @param amount uint256 amount of tokens to transfer
* @param userData bytes extra information provided by the token holder (if any)
* @param operatorData bytes extra information provided by the operator (if any)
* @param requireReceptionAck if true, contract recipients are required to implement ERC777TokensRecipient
*/
function _callTokensReceived(
address operator,
address from,
address to,
uint256 amount,
bytes memory userData,
bytes memory operatorData
bytes memory operatorData,
bool requireReceptionAck
)
private
{
address implementer = _erc1820.getInterfaceImplementer(to, TOKENS_RECIPIENT_INTERFACE_HASH);
if (implementer != address(0)) {
IERC777Recipient(implementer).tokensReceived(operator, from, to, amount, userData, operatorData);
} else {
require(!to.isContract());
} else if (requireReceptionAck) {
require(!to.isContract(), "ERC777: token recipient contract has no implementer for ERC777TokensRecipient");
}
}
}
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